Patent Publication Number: US-2023160996-A1

Title: Communication device and sensing method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a communication apparatus and a sensing method. 
     BACKGROUND ART 
     Non-Patent Literatures (hereinafter, each referred to as “NPL”) 1 and 2 disclose that a pulse signal is used for sensing of an object. NPL 3 discloses sensing of an object based on a frequency modulated continuous wave (FMCW) scheme and a phase modulated continuous wave (PMCW) scheme. Further, NPL 4 discloses that an orthogonal frequency division multiplexing (OFDM) signal is used for sensing of an object. 
     CITATION LIST 
     Non-Patent Literature 
     NPL 1 
     
         
         S. Schuster, S. Scheiblhofer, R. Feger, and A. Stelzer, “Signal model and statistical analysis for the sequential sampling pulse radar technique,” in Proc. IEEE Radar Conf, 2008, pp. 1-6, 2008 
       
    
     NPL 2 
     
         
         D. Cao, T. Li, P. Kang. H. Liu, S. Zhou, H. Su, “Single-Pulse Multi-Beams Operation of Phased Array Radar”, 2016 CIE International Conference on Radar (RADAR), pp. 1-4, 2016 
       
    
     NPL 3 
     
         
         A. Bourdoux, K. Parashar, and M. Bauduin, “Phenomenology of mutual interference of FMCW and PMCW automotive radars,” in 2017 IEEE Radar Conference (Radar Conf.), pp. 1709-1714, 2017 
       
    
     NPL 4 
     
         
         J. Fink, F. K. Jondral, “Comparison of OFDM radar and chirp sequence radar,” in 2015 16th International Radar Symposium (IRS), pp. 315-320, 2015 
       
    
     SUMMARY OF INVENTION 
     The 5th Generation Mobile Communication System has been discussing position estimation, and the Institute of Electrical and Electronics Engineers (IEEE) has been discussing sensing of an object in a wireless local area network (LAN). 
     However, a method for performing position estimation and specific specifications for performing sensing of an object have not been developed. 
     One non-limiting and exemplary embodiment facilitates providing a communication apparatus, which performs sensing of an object, and a sensing method. 
     Solution to Problem 
     A communication apparatus according to an exemplary embodiment of the present disclosure is a communication apparatus including: a transmitter that transmits request information for requesting sensing of a target; a receiver that receives result information indicating a sensing result from a first communication apparatus in which the sensing of the target has been performed in accordance with the request information; and a controller that determines a state of the target based on the sensing result indicated in the result information and a sensing result of sensing of the target that has been performed in the communication apparatus. 
     A sensing method according to an exemplary embodiment of the present disclosure is a sensing method in a communication apparatus and includes: transmitting request information for requesting sensing of a target; receiving result information indicating a sensing result from a first communication apparatus in which the sensing of the target has been performed in accordance with the request information; and determining a state of the target based on the sensing result indicated in the result information and a sensing result of sensing of the target that has been performed in the communication apparatus. 
     It should be noted that general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. 
     According to an exemplary embodiment of the present disclosure, the communication apparatus is capable of performing sensing of an object. 
     Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    illustrates an example of a configuration of an apparatus that performs sensing; 
         FIG.  2    illustrates an example of a configuration of an apparatus that performs sensing; 
         FIG.  3    illustrates an example of a configuration of an apparatus that performs communication and sensing; 
         FIG.  4    illustrates an example of a communication system; 
         FIG.  5    illustrates a configuration example of a frame for data transmission; 
         FIG.  6 A  illustrates a configuration example of a frame for sensing; 
         FIG.  6 B  illustrates a configuration example of a frame for sensing; 
         FIG.  7    illustrates an example of a frame state in a time axis of a certain frequency band; 
         FIG.  8    illustrates another example of a frame state in a time axis of a certain frequency band; 
         FIG.  9    illustrates a time-frequency example of signals transmitted by a base station; 
         FIG.  10    illustrates a time-frequency example of signals transmitted by terminals; 
         FIG.  11    illustrates a system configuration example provided for describing an example of triangulation; 
         FIG.  12    illustrates a system configuration example; 
         FIG.  13    is a diagram provided for describing an example of information on sensing capability; 
         FIG.  14    illustrates a procedure example for sensing in the system example in  FIG.  12   ; 
         FIG.  15 A  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  15 B  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  15 C  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  15 D  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  15 E  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  15 F  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  16    illustrates another procedure example for sensing; 
         FIG.  17    is a diagram provided for describing an example of base station selection; 
         FIG.  18    illustrates a system configuration example; 
         FIG.  19    illustrates a procedure example for sensing in the system example in  FIG.  18   ; 
         FIG.  20    illustrates another procedure example for sensing in the system example in  FIG.  18   ; 
         FIG.  21 A  illustrates a configuration example of an apparatus and a base station; 
         FIG.  21 B  illustrates a configuration example of an apparatus and a base station; 
         FIG.  22    illustrates an exemplary state when an apparatus and a base station are performing a sensing operation; 
         FIG.  23 A  illustrates a system configuration example; 
         FIG.  23 B  illustrates a procedure example for sensing; 
         FIG.  24    illustrates an example of a configuration of the apparatus (base station) in  FIGS.  12  and  23 A ; 
         FIG.  25    illustrates a transmission antenna-related configuration example; 
         FIG.  26    illustrates an example of a frame of a signal for sensing; 
         FIG.  27    illustrates an example of a configuration of a signal for sensing; 
         FIG.  28    illustrates an example of a configuration of a signal for sensing; 
         FIG.  29    illustrates a system configuration example; 
         FIG.  30    is a diagram provided for describing an example of information on sensing capability; 
         FIG.  31    illustrates a procedure example for sensing in the system example in  FIG.  29   ; 
         FIG.  32 A  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 B  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 C  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 D  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 E  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 F  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 G  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  32 H  is a diagram provided for describing an acquisition example of distance information; 
         FIG.  33    illustrates another procedure example for sensing; 
         FIG.  34    illustrates yet another procedure example for sensing; 
         FIG.  35    illustrates still another procedure example for sensing; 
         FIG.  36    illustrates a system configuration example; 
         FIG.  37    illustrates a procedure example for sensing in the system example in  FIG.  36   ; 
         FIG.  38    illustrates another procedure example for sensing; 
         FIG.  39    illustrates yet another procedure example for sensing; 
         FIG.  40    illustrates still another procedure example for sensing; 
         FIG.  41    illustrates exemplary transmission frames; 
         FIG.  42    illustrates exemplary transmission frames; 
         FIG.  43    illustrates exemplary transmission frames; 
         FIG.  44    illustrates exemplary transmission frames; 
         FIG.  45    illustrates exemplary transmission frames; 
         FIG.  46    illustrates exemplary transmission frames; 
         FIG.  47    illustrates exemplary transmission frames; 
         FIG.  48    illustrates exemplary transmission frames; 
         FIG.  49    illustrates exemplary transmission frames; 
         FIG.  50    illustrates exemplary transmission frames; 
         FIG.  51    illustrates a system configuration example; 
         FIG.  52    illustrates a system configuration example; 
         FIG.  53    illustrates a system configuration example; 
         FIG.  54    illustrates a system configuration example; 
         FIG.  55 A  illustrates an operation example when apparatuses and a base station perform sensing; 
         FIG.  55 B  illustrates an operation example when the apparatuses and the base station perform sensing; 
         FIG.  56 A  illustrates an operation example when the apparatuses and the base station perform sensing; 
         FIG.  56 B  illustrates an operation example when the apparatuses and the base station perform sensing; 
         FIG.  57    illustrates a system configuration example; 
         FIG.  58    illustrates a system configuration example; 
         FIG.  59    illustrates a system configuration example; 
         FIG.  60 A  illustrates an operation example when apparatuses and a base station perform sensing; 
         FIG.  60 B  illustrates an operation example when the apparatuses and the base station perform sensing; 
         FIG.  61 A  illustrates an operation example when the apparatuses and the base station perform sensing; and 
         FIG.  61 B  illustrates an operation example when the apparatus and the base station perform sensing. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, a detailed description more than necessary may be omitted, such as a detailed description of an already well-known matter and a duplicate description for a substantially identical configuration, to avoid unnecessary redundancy of the following description and to facilitate understanding by the person skilled in the art. 
     Note that, the accompanying drawings and the following description are provided for the person skilled in the art to sufficiently understand the present disclosure, and are not intended to limit the subject matter described in the claims. 
     Hereinafter, sensing may include estimation of the position of an object, detection of an object, grasping the outer shape of an object, estimation of movement of an object, and estimation of a gesture of an object. An object to be subjected to sensing may also be referred to as a target object. Further, living things such as humans and animals also become objects to be subjected to sensing. As a matter of course, objects to be subjected to sensing may not be living things. 
     The main purpose of estimation of the position of an object is to estimate a position of an object. Estimation of the position of an object may include estimating both detection of an object and movement of the object. The position of an object may be estimated by means of triangulation using a radio wave, light, an ultrasound wave, or the like. Movement of an object may be detected by using a Doppler frequency. Further, estimation of a gesture of an object may also be performed. Note that, the above description is an example, and the present disclosure is not limited thereto. 
     The main purpose of detection of an object is to detect an object. Detection of an object may include specifying an object. An object may be detected by using detection of reflection of a radio wave, light, an ultrasound wave, or the like, and/or detection of a reflected wave. Detection of an object may or may not include estimation of the position of an object. Note that, the above description is an example, and the present disclosure is not limited thereto. 
     The main purpose of grasping the outer shape of an object is to detect the outer shape of an object. Grasping the outer shape of an object may include, for example, specifying an object. Further, grasping the outer shape of an object may also include, for example, a change or movement of the outer shape of an object. The outer shape of an object may be grasped by using a pulsed spread spectrum signal, and/or a signal with a certain band. Grasping the outer shape of an object may or may not include estimation of the position of an object. Further, estimation of a gesture of an object may also be performed. Note that, the above description is an example, and the present disclosure is not limited thereto. 
     Estimation of the position of an object, detection of an object, grasping the outer shape of an object, estimation of movement of an object, and estimation of a gesture of an object may also be referred to as estimation of the state of an object. In other words, the state of an object may include at least one of the position of the object, detection (presence or absence) of the object, the outer shape of the object, movement of the object, and/or a gesture of the object. Further, the gesture of the object may also be included in the movement of the object. 
     In the present disclosure, the terminal may have a communication function. The terminal may also have a function of sensing of an object. The terminal may also have a communication function and a function of sensing of an object. The AP or the base station may or may not have a function of sensing of an object. The AP or the base station has at least a function of communicating with the terminal. The terminal may also be referred to as an apparatus or a communication apparatus. 
     Embodiment 1 
     First, configurations of an apparatus related to the present disclosure that performs sensing and an apparatus related to the present disclosure that performs communication and sensing, or the like will be described. Note that, the sensing method in an apparatus having a sensing function (capability), such as an apparatus that perform sensing and an apparatus that performs communication and sensing, may be any scheme of methods described herein, for example. 
       FIG.  1    illustrates an example of a configuration of apparatus X 100  that performs sensing by transmitting a signal for sensing and receiving the signal for sensing that has reflected off an object around apparatus X 100  and has returned. Apparatus X 100  performs sensing of an object by transmitting a signal for sensing and receiving the signal for sensing that has reflected off an object around apparatus X 100  and has returned. 
     Transmission apparatus X 101  generates transmission signals X 102 _ 1  to X 102 _M. Transmission signals X 102 _ 1  to X 102 _M are signals for sensing. Transmission apparatus X 101  transmits transmission signals X 102 _ 1  to X 102 _M, which have been generated, from antennas X 103 _ 1  to X 103 _M, respectively. Here, the number of antennas used for transmission is M, where M is an integer larger than or equal to 1 or an integer larger than or equal to 2. 
     For example, transmission apparatus X 101  may generate transmission signals X 102 _ 1  to X 102 _M by multiplying the same sensing signal by coefficients determined for each antenna, and transmit transmission signals X 102 _ 1  to X 102 _M from antennas X 103 _ 1  to X 103 _M to perform directivity control for the sensing signal. Further, for example, transmission apparatus X 101  may generate transmission signals X 102 _ 1  to X 102 _M by multiplying a plurality of sensing signals by coefficients determined for each sensing signal and each antenna, respectively, and combining the resulting plurality of sensing signals, and transmit transmission signals X 102 _ 1  to X 102 _M from antennas X 103 _ 1  to X 103 _M. Thus, it is possible to perform directivity control for each sensing signal. 
     The coefficients determined for each antenna or the coefficients determined for each sensing signal and each antenna are expressed as complex numbers or real numbers. The amplitudes and/or phases of sensing signals transmitted from each antenna vary depending on the values of the coefficients. However, the coefficients may be one. In this case, a sensing signal generated by transmission apparatus X 101  is transmitted as it is from an antenna for which the coefficient value is one. 
     Note that, transmission apparatus X 101  may also transmit a transmission signal without performing directivity control. For example, transmission apparatus X 101  may output a plurality of sensing signals as they are as transmission signals from the corresponding antennas, respectively, and transmit the plurality of sensing signals from antennas X 103 _ 1  to X 103 _M. 
     Although a case where there is a plurality of signals for sensing and there is a plurality of antennas has been described above, the number of signals for sensing generated by transmission apparatus X 101  and the number of antennas that transmit signals for sensing may be one, respectively. 
     Signals for sensing transmitted from antennas X 103 _ 1  to X 103 _M are reflected off object # 1  (X 110 _ 1 ) or object # 2  (X 110 _ 2 ). The reflected signals for sensing are received by antennas X 104 _ 1  to X 104 _N included in apparatus X 100 . Here, the number of antennas that receive signals for sensing is N, where N is an integer larger than or equal to one or an integer larger than or equal to two. Number M of antennas used for transmission may be the same as or different than number N of antennas used for reception. 
     Reception signals X 105 _ 1  to X 105 _N received by antennas X 104 _ 1  to X 104 _N are inputted into reception apparatus X 106 . For example, reception apparatus X 106  performs, on reception signals X 105 _ 1  to X 105 _N, filter processing of extracting a frequency band, in which signals for sensing are transmitted, or only channel components in the frequency band, frequency conversion processing of conversion from a radio frequency band to an intermediate frequency band (IF) and/or to a frequency band of a baseband signal, weighting/combining processing on N reception signals, and/or the like, and outputs estimation signal X 107 . 
     Coefficients used in the weighting/combining processing on the N reception signals may be configured for each of reception signals X 105 _ 1  to X 105 _N. Apparatus X 100  can perform reception directivity control by changing the values of the coefficients. The coefficients may be estimated in advance, or reception signals X 105 _ 1  to X 105 _N may be used to estimate coefficients in which the amplitude or signal-to-noise ratio (SNR) of a sensing signal component after the weighting/combining processing is larger than that in a case where other coefficients are used, or exceeds a predetermined threshold. 
     Further, reception apparatus X 106  may use a plurality of sets of N coefficients corresponding to reception signals X 105 _ 1  to X 105 _N to acquire signals having directivities corresponding to each set of coefficients at the same time. Note that, reception apparatus X 106  may not perform the weighting/combining processing. 
     Estimator X 108  performs sensing, that is, estimation processing on the surrounding environment by using estimation signal X 107 . Details of the estimation processing performed by estimator X 108  will be described later. 
     Control signal X 109  is a control signal that is inputted into transmission apparatus X 101 , reception apparatus X 106 , and estimator X 108 , and instructs transmission apparatus X 101 , reception apparatus X 106 , and estimator X 108  to perform sensing, performs sensing range instruction and control of sensing timing for transmission apparatus X 101 , reception apparatus X 106 , and estimator X 108 , and/or the like. 
     An example of the configuration of apparatus X 100  has been described thus far. 
     Note that, although a case where signals generated by apparatus X 100  are transmitted from M antennas and signals received by N antennas are subjected to signal processing by reception apparatus X 106  has been described as an example in  FIG.  1   , the configuration of the apparatus that performs the sensing method described herein is not limited thereto. 
     For example, a plurality of transmission antenna processors that transmits signals may be each formed of a plurality of antenna units each of which includes a plurality of antennas. Here, the plurality of antenna units may have the same directivity and directivity control function, or ranges in which directivity control can be performed may differ between the antenna units. At this time, one transmission apparatus X 101  may select an antenna unit to be used for sensing signal transmission from among the plurality of antenna units, or the same sensing signal may be transmitted from the plurality of antenna units at the same time. 
     Further, transmission apparatus X 101  may switch between transmitting one sensing signal from one antenna unit and transmitting one sensing signal from a plurality of antenna units at the same time. Further, apparatus X 100  may include a plurality of transmission apparatuses X 101  or may include one transmission apparatus X 101  for each antenna unit. 
     In the same manner, a plurality of reception antenna processors that receives signals may be each formed of a plurality of antenna units each of which includes a plurality of antennas. Here, the plurality of antenna units may have the same directivity control capabilities such as directivity control range and directivity control accuracy, or directivity control capabilities may differ between the antenna units. Further, the plurality of antenna units may be disposed such that the directivity control capabilities such as directivity control range and directivity control accuracy are the same, but spatial areas in which directivity control can be performed differ. At this time, one reception apparatus X 106  may select an antenna unit that acquires reception signals from among a plurality of antenna units, or signals received from a plurality of antenna units may be subjected to signal processing at the same time. 
     Further, reception apparatus X 106  may also switch between subjecting only reception signals received from one antenna unit to signal processing and subjecting reception signals received from a plurality of antenna units to signal processing at the same time. Further, apparatus X 100  may include a plurality of reception apparatuses X 106 , and may include one reception apparatus X 106  for each antenna unit. 
     Further, apparatus X 100  may also include a plurality of antennas that can be used for both transmission and reception of signals, rather than including a plurality of antennas for transmission and a plurality of antennas for reception separately. In this case, apparatus X 100  may select and switch between using each antenna for transmission and using each antenna for reception, or may temporally switch between using a plurality of antennas for transmission and using a plurality of antennas for reception. 
     Further, apparatus X 100  may include a transmission and reception antenna processor that can be used commonly for both signal transmission and signal reception. Here, the transmission and reception antenna processor includes a plurality of antenna units, and can switch between using each antenna unit for transmission and using each antenna unit for reception. Apparatus X 100  may also include a selector that selects and switches between an antenna unit used to transmit a signal generated by transmission apparatus X 101  and an antenna unit used to receive a signal to be subjected to signal processing by reception apparatus X 106 . 
     In a case where sensing signals are transmitted by using a plurality of antenna units at the same time, the directivities of the signals transmitted from each antenna unit may be the same or different. In a case where apparatus X 100  transmits sensing signals with the same directivity from a plurality of antenna units, there is a possibility that the distances that the sensing signals reach can be lengthened or the distances to reflection positions at which the reflected sensing signals are receivable can be lengthened. 
     Note that, the number of antennas that form the antenna unit described above does not need to be the same between the antenna units and may vary between the antenna units. 
     Next, the estimation processing performed by estimator X 108  will be described as an example. 
     For example, estimator X 108  estimates the distance between apparatus X 100  and an object that has reflected a sensing signal. Estimation of the distance between apparatus X 100  and an object that has reflected a sensing signal can be derived, for example, by detecting a delay time between the time of transmission of the sensing signal and the time of reception thereof, and multiplying the delay time by the propagation velocity of the electromagnetic wave. 
     Estimator X 108  may estimate the direction of arrival of a reception signal, that is, the direction of an object that has reflected a sensing signal by using a direction-of-arrival estimation method such as a multiple signal classification (MUSIC) method, for example. Estimator X 108  can estimate the position of an object that has reflected a transmitted signal by estimating the direction in addition to the distance between apparatus X 100  and an object. 
     For example, estimator X 108  can estimate the position of an object by performing triangulation by using information on direction-of-arrival estimation by the MUSIC method or the like, the positions of transmission antennas, the positions of reception antennas, and the direction of transmission directivity control, or the like. Estimator X 108  may detect an object, movement of an object, the material of an object, and the like by using a reception signal. Further, estimator X 108  may also estimate detection of an object, the position of an object, movement of an object, and the like by an estimation method other than triangulation. Note that, the method described herein can be mentioned as an example of the sensing method. 
     The position of an object may be expressed in a polar coordinate system or in a three-dimensional orthogonal coordinate system. The origin of the coordinate system may be, for example, an arbitrary position in apparatus X 100 , and the axes in the coordinate system may be oriented arbitrarily. 
     Note that, in a case where a device including apparatus X 100  includes a plurality of radio sensors or other distance sensors having the same configuration as or a different configuration from that of apparatus X 100  in addition to apparatus X 100 , the origins and axes of coordinate systems of data acquired by each sensor may be common among the sensors or may be unique to each sensor. Estimator X 108  may output position information expressed in the unique coordinate systems described above as it is or may perform conversion into a common coordinate system in the device and output the common coordinate system. The converted coordinate system may be a coordinate system unique to the device or may be a coordinate system common to those of other devices, such as a coordinate system that is the same as a three-dimensional map data utilized by the device. 
     Further, estimator X 108  may estimate distances to an object that has reflected signals in each of a plurality of directions and acquire three-dimensional coordinates of a plurality of estimated reflection positions as a point cloud. Note that, the format of data of a plurality of distance measurement results acquired by estimator X 108  may not be a point cloud format including three-dimensional coordinate values, but may be, for example, a distance image format or any other format. In a case where the distance image format is used, positions (coordinates) of a distance image in a two-dimensional plane correspond to directions of arrival of reception signals viewed from apparatus X 100 , and distances to an object in directions corresponding to pixel positions of each image are stored as pixel sample values. 
     Further, estimator X 108  may also perform recognition processing such as estimation of the shape of an object by using the above-described point cloud data or distance image data. For example, estimator X 108  can regard and extract “one or more points of positions which are close to each other and whose distances are within a predetermined range”, a plurality of points or an image area as the same object, and estimate the shape of an object based on the positional relationship of the one or plurality of points or the shape of the image area. Estimator X 108  may perform identification of an object subjected to sensing as recognition processing using an estimation result of the shape of an object. In this case, for example, estimator X 108  performs identification whether an object in a sensing range is a person or an animal, performs identification of the type of the object, and the like. 
     Note that, the recognition processing performed by estimator X 108  may not be identification of an object. For example, as the recognition processing, estimator X 108  may detect the number of persons, automobiles, or the like in a sensing range, and/or may estimate the face position, posture or the like of a detected person. As recognition processing different from the above-described recognition processing, estimator X 108  may perform processing such as face authentication in which it is determined whether the shape of the face of a detected person matches that of a person registered in advance, which person the detected person is, or the like. 
     Further, estimator X 108  may also measure the distance between apparatus X 100  and an object at different timings a plurality of times to acquire a temporal change in the distance between apparatus X 100  and the object or in the position of a detected point. In this case, estimator X 108  may also estimate the velocity, acceleration and the like of a moving object as recognition processing that uses a temporal change in the distance between apparatus X 100  and the object or in the position of the point. For example, estimator X 108  may also estimate the velocity, movement direction and the like of an automobile driving in a sensing range. 
     Note that, the recognition processing performed by estimator X 108  using a temporal change in a distance or in the position of a point may not be estimation of the velocity and acceleration of an object. For example, estimator X 108  may detect based on a change in the posture of a detected person whether the person has performed a specific action, and may utilize apparatus X 100  as a gesture-inputting device for an electronic device such as a smart phone, a tablet, and a personal computer. 
     The estimation of the velocity of a moving object described above may be derived by comparing the frequency of a transmitted sensing signal with the frequency of a received reflected signal to estimate a change in frequency due to a Doppler effect received by the reflected signal. 
     Next, the sensing signal used in transmission apparatus X 101  and reception apparatus X 106  will be described as an example. 
     Apparatus X 100  may transmit, for example, the pulse signal disclosed in NPLs 1 and 2 as a signal for sensing. Apparatus X 100  transmits the pulse signal in a frequency band used for sensing, and measures the distance to an object that has reflected the signal for sensing, based on a delay time between the time of transmission of the pulse signal and the time of reception of a reflected signal. 
     As another example of the signal for sensing, apparatus X 100  may use the signal in the FMCW scheme or the PMCW scheme described in NPL 3. The FMCW signal is a signal obtained by converting a chirp signal, whose frequency has been temporally changed, into a radio frequency. As estimation processing that uses a FMCW signal, estimator X 108  superimposes a signal to be transmitted from transmission apparatus X 101  and a signal received by reception apparatus X 106  with a mixer. As a result, the superimposed signal becomes a signal having an intermediate frequency in accordance with the time of flight of the received signal so that the distance to an object that has reflected the FMCW signal is measured by detecting a frequency component included in the superimposed signal. 
     As another example of the signal for sensing. apparatus X 100  may use a signal obtained by frequency-converting a modulated signal having a predetermined frequency into a signal of a frequency band used for sensing. In this case, for example, estimator X 108  can estimate the distance to an object that has reflected a signal for sensing, based on a difference between the phase of a modulation component of a signal to be transmitted from transmission apparatus X 101  and the phase of a modulation component of a signal received by reception apparatus X 106 . 
     Further, estimator X 108  may also compare the frequency of a transmitted modulated signal with the frequency of a received modulated signal to thereby detect a variation in frequency due to a Doppler effect between the reflection of a sensing signal and the reception thereof, and estimate the movement velocity and direction of a moving object. Note that, there may be a plurality of frequency components included in a modulated signal and, for example, multicarrier transmission including a plurality of frequency components, such as an OFDM signal, may be used as the modulated signal described in NPL 4. 
     Examples of the signal for sensing are not limited to the above examples. The signal for sensing may be a signal modulated by a modulation scheme, may be an unmodulated carrier, or any other signal may be used. 
     As described above, apparatus X 100  may use a plurality of antennas to transmit a plurality of sensing signals at the same time, or may use a plurality of antenna units each of which includes a plurality of antennas to transmit a plurality of sensing signals at the same time. 
     Here, as an example, a case where a distance is measured based on a difference between the time of transmission of a sensing signal and the time of reception of a reflected signal has been described as the estimation processing performed by estimator X 108 . However, the estimation processing performed by estimator X 108  is not limited to the case described above. 
     For example, estimator X 108  may estimate a transmission path state based on a received reflected signal and perform recognition processing based on a temporal change in the estimated transmission path state and comparison of the estimated transmission path state with an average value of past estimated transmission path states and/or a feature amount to determine whether an object is present in a sensing range, to detect the presence or absence of movement of an object, and the like. Further, estimator X 108  may also detect the presence or absence of rainfall based on an attenuation situation of a reception signal, or the like. 
     Further, an example in which a reflected wave of a transmitted sensing signal is used for sensing has been described here. However, the apparatus that performs sensing by using a sensing signal is not limited to the apparatus that transmits the sensing signal. 
     For example, reception apparatus X 106  of apparatus X 100  may receive a sensing signal transmitted from another apparatus and, based on the reception signal, estimator X 108  may determine that the other apparatus is in a range in which the sensing signal reaches and may estimate the direction of the other apparatus. Further, estimator X 108  may also estimate the distance to the other apparatus based on the signal strength of the received sensing signal. 
     Further, reception apparatus X 106  of apparatus X 100  may also transmit a sensing signal such that another apparatus can use the sensing signal for sensing. The sensing signal to be transmitted at this time may be a sensing signal to be transmitted for apparatus X 100  to perform sensing by using a reflected wave or may be periodically transmitted for another apparatus to perform sensing. Further, in a case where apparatus X 100  receives a sensing signal transmitted from another apparatus, apparatus X 100  may use transmission apparatus X 101  to transmit a sensing signal in the direction in which the reception signal has been received. Note that, the sensing signal to be transmitted to another apparatus may be transmitted without performing directivity control. Further, the sensing signal may also be generated by the method described herein. 
     Further, although  FIG.  1    illustrates an example in which apparatus X 100  that performs sensing receives signals reflected off objects # 1  and # 2 , apparatus X 100  may use signals obtained by reflecting off objects # 1  and # 2  and further reflecting off other object(s) or matter to estimate detection of an object, the distance to an object, the position of an object, and the like. 
     Next, an example of a sensing method that uses radio waves different from those in  FIG.  1    will be described. 
       FIG.  2    illustrates an example of a configuration of apparatus X 200  that performs sensing by using radio waves. In the configuration illustrated in  FIG.  2   , the configuration elements having the same functions as those in the configuration illustrated in  FIG.  1    are denoted by the same reference signs, and detailed descriptions thereof will be omitted. 
     Apparatus X 200  differs from apparatus X 100  in that apparatus X 200  performs sensing by using a modulated signal for sensing and/or a modulated signal for communication. Here, for example, apparatus X 200  transmits signals and the terminal as the communication partner captures a change between the signals transmitted by apparatus X 200  to estimate the position and size of an object (for example, object # 1  in  FIG.  2   ), the distance to an object (for example, object # 2  in  FIG.  2   ), or the like. Note that, in a case where apparatus X 200  transmits a modulated signal for communication, data communication with the terminal is also possible. Hereinafter, a case in which sensing is performed by using a modulated signal for communication will be described. 
     Transmission apparatus X 201  inputs control signal X 109  and transmission data X 210 , and performs error correction coding processing, modulation processing, precoding, multiplexing processing and/or the like to generate transmission signals for communication X 202 _ 1  to X 202 _M. Apparatus X 200  transmits transmission signals X 202 _ 1  to X 202 _M from antennas X 103 _ 1  to X 103 _M, respectively. 
     The number of transmission signals and the number of antennas used for transmission are the same as described with respect to  FIG.  1   , and may be two or more or may be one. The description with reference to  FIG.  2    differs from the description with reference to  FIG.  1    in that the transmission signal in the description with reference to  FIG.  1    includes a sensing signal component, whereas the transmission signal in  FIG.  2    includes a component of a signal of modulated transmission data. However, transmission apparatus X 201  and transmission apparatus X 101  are the same in terms of being capable of performing directivity control by coefficients used in weighting/combining processing for generating a transmission signal. Further, in the same manner as apparatus X 100 , apparatus X 200  may include one antenna unit including a plurality of antennas or may include a plurality of antenna units. 
     In a case where directivity control is performed, transmission apparatus X 101  of  FIG.  1    performs transmission directivity control in a direction in which sensing is to be performed, whereas transmission apparatus X 201  of  FIG.  2    performs transmission directivity control such that communication quality with the terminal as the communication partner improves. However, transmission apparatus X 201  may perform transmission signal directivity control toward a direction in which sensing is to be performed, or may perform directivity control such that the terminal as the communication partner can use a signal transmitted by apparatus X 200  to obtain a desirable sensing result in performing sensing. 
     In a case where transmission apparatus X 201  performs directivity control for sensing by the terminal, transmission apparatus X 201  transmits a signal by using a coefficient designated by the terminal. The signal to be transmitted here may or may not include a signal component modulated by using transmission data. The signal that does not include a signal component modulated by using transmission data is a signal modulated by a value known on a side of the terminal, such as a preamble and a reference signal, for example. Further, transmission apparatus X 201  may perform different directivity controls depending on whether a signal including a signal component modulated by using transmission data is transmitted or a signal including no signal component modulated by using transmission data is transmitted. 
     Note that, the terminal obtains data (performs communication) as well as performs sensing by receiving a modulated signal transmitted by apparatus X 200 . 
     Further, the terminal may transmit signals and apparatus X 200  as the communication partner may capture a change between the signals transmitted by the terminal to estimate the position and size of an object (for example, object # 1  in  FIG.  2   ), the distance to an object (for example, object # 1  in  FIG.  2   ), the type and material of an object (for example, object # 1  in  FIG.  2   ), and the like. Note that, in a case where the terminal transmits a modulated signal for communication, data communication with apparatus X 200  is also possible. 
     For example, apparatus X 200  uses antennas X 104 _ 1  to X 104 _N to receive modulated signals transmitted by the terminal. Reception apparatus X 206  inputs control signal X 109  and reception signals X 205 _ 1  to X 205 _N and performs demodulation processing, error correction decoding processing and the like to acquire reception data. Further, reception apparatus X 206  outputs, as estimation signal X 207 , transmission path characteristics and the like obtained by reception processing. 
     Coefficients used in the weighting/combining processing on the N reception signals can be configured for each of reception signals X 105 _ 1  to X 105 _N, and reception directivity control can be performed by changing the values of the coefficients. The coefficients may be estimated in advance, or reception signals X 105 _ 1  to X 105 _N may be used to estimate coefficients in which the amplitude or signal-to-noise ratio (SNR) of a sensing signal component after the weighting/combining processing is larger than that in a case where other coefficient are used, or exceeds a predetermined threshold. Further, reception apparatus X 206  may use a plurality of sets of N coefficients corresponding to reception signals X 105 _ 1  to X 105 _N to acquire signals having directivities corresponding to each set of coefficients at the same time. 
     Estimator X 208  inputs control signal X 109  and estimation signal X 207 , and performs estimation processing by using estimation signal X 207 . Estimator X 208  estimates the surrounding environment, such as whether an object is present around, based on transmission path characteristics included in estimation signal X 207 , for example. Further, estimator X 208  may also detect movement of an object, approach of an object or the like based on a temporal change in the transmission path characteristics. 
     For example, estimator X 208  may estimate the direction of arrival of a reception signal, that is, the direction of an object that has reflected a sensing signal, by using a direction-of-arrival estimation method such as the MUSIC method. For example, estimator X 208  may estimate the position of an object by performing triangulation by using information on direction-of-arrival estimation by the MUSIC method or the like, the positions of antennas (for example, the positions of the transmission apparatus and the reception apparatus), and the direction of transmission directivity control, or the like. Estimator X 208  may also detect an object, movement of an object, the material of an object, and the like by using a reception signal. 
     For example, estimator X 208  performs the aforementioned estimation processing, for example, signal processing in accordance with an event to be detected, such as the presence or absence of an object and the presence or absence of movement of an object as described above, on estimation signal X 207 . At this time, the estimation processing is performed, for example, based on a determination result of whether a feature amount extracted by the signal processing exceeds a predetermined threshold. 
     Estimator X 208  may perform the estimation processing based on signal processing other than the signal processing exemplified above. For example, the estimation processing may also be performed with a model created by machine learning using a neural network having a multi-layered structure. In a case where a model created by machine learning using a neural network having a multi-layered structure is utilized in the estimation processing, estimator X 208  may perform predetermined preprocessing on estimation signal X 207  and then input the preprocessed data into the model created by the machine learning using the neural network having the multi-layered structure. 
     Further, estimator X 208  may also use information on a frequency band used for communication, a channel number in the frequency band, or the like. Further, estimator X 208  may also use the address of a communication apparatus that has transmitted a received signal for communication or the address of a communication apparatus that is the destination of the signal. Thus, by using information on a received signal for communication, such as a frequency band and the address of a communication apparatus, it is possible to perform a comparison between signals for communication, in which conditions, such as the positions of communication apparatuses, which have transmitted signals, and directivities used when signals are transmitted, are the same or similar, and there is a possibility that the estimation accuracy will improve. 
     A case where sensing is performed by using a signal for communication transmitted by a communication partner has been described above. Although  FIG.  2    illustrates the configuration of apparatus X 200  in which transmission apparatus X 201  and antennas X 103 _ 1  to X 103 _M, which are the configurations for performing transmission processing, and reception apparatus X 206  and antennas X 104 _ 1  to X 104 _N, which are the configurations for performing reception processing, are different, the configuration of apparatus X 200  is not limited thereto. 
     For example, transmission apparatus X 201  and reception apparatus X 206  may be realized as one configuration element, and/or a plurality of antennas may be commonly used for transmission and reception. Further, in the same manner as in the description with reference to  FIG.  1   , the plurality of antennas for transmission in apparatus X 200  may be formed of a plurality of antenna units, and the plurality of antennas for reception in apparatus X 200  may be formed of a plurality of antenna units. Further, the plurality of antennas for transmission and the plurality of antennas for reception in apparatus X 200  may be formed as a common transmission and reception antenna processor. 
     Further, a signal for sensing may be used instead of a signal for communication. That is, a first apparatus may use a signal for sensing transmitted by another apparatus to estimate the position and size of an object (for example, object # 1  in  FIG.  2   ), the distance to an object (for example, object # 1  in  FIG.  2   ), the type and material of an object (for example, object # 1  in  FIG.  2   ), and the like. 
     The sensing method using a signal for communication may also be utilized for the same purpose as the example described with reference to  FIG.  1    in which a sensing signal is transmitted to another apparatus. That is, apparatus X 200  may also use a signal for communication transmitted from another apparatus such as a terminal, based on transmission path characteristics and the like of the signal, not for sensing the surrounding environment, but for determining that the other apparatus is in a range in which the signal for communication reaches or for estimating the direction of the other apparatus. 
     Note that, apparatus X 200  may perform only a demodulation operation without performing a sensing operation when receiving a modulated signal for communication transmitted by, for example, the terminal as the communication partner. 
     Next, an apparatus that performs communication and sensing will be described. 
       FIG.  3    illustrates an example of a configuration of apparatus X 300  that performs communication and sensing. In the configuration illustrated in  FIG.  3   . the configurations having the same functions as those in the configurations illustrated in  FIGS.  1  and  2    are denoted by the same reference signs, and detailed descriptions thereof will be omitted. 
     Apparatus X 300  performs both sensing using a modulated signal for sensing and sensing using a modulated signal for communication. 
     That is, transmission apparatus X 301  of apparatus X 300  has a function of transmitting a signal for sensing in the same manner as transmission apparatus X 101 , and a function of transmitting a signal for communication to another communication apparatus in the same manner as transmission apparatus X 201 . 
     In addition, reception apparatus X 306  of apparatus X 300  has a function of receiving a signal for sensing in the same manner as reception apparatus X 106 , and a function of receiving a signal for communication transmitted by another communication apparatus in the same manner as reception apparatus X 206 . 
     Further, estimator X 308  performs both estimation processing using a signal for sensing in the same manner as estimator X 108 , and estimation processing using a signal for communication in the same manner as estimator X 208 . 
     In the processing performed by each configuration element of apparatus X 300 , the processing of transmitting and receiving signals for sensing is the same as with apparatus X 100  illustrated in  FIG.  1   , and the processing for transmitting and receiving signals for communication is the same as with apparatus X 200  illustrated in  FIG.  2   . Accordingly, descriptions thereof will be omitted. 
     Although  FIG.  3    illustrates the configuration of apparatus X 300  in which transmission apparatus X 301  and antennas X 103 _ 1  to X 103 _M, which perform transmission processing, and reception apparatus X 306  and antennas X 104 _ 1  to X 104 _N, which perform reception processing, are different, the configuration of apparatus X 300  is not limited thereto. For example, transmission apparatus X 301  and reception apparatus X 306  may be realized as one configuration element, and one or more antennas or a plurality of antennas may be used commonly for transmission and reception. 
     Apparatus X 300  may also include, apart from the transmission apparatus for communication, a transmission apparatus for sensing. At this time, the transmission apparatus for communication and the transmission apparatus for sensing may use the same one or more antennas or the same plurality of antennas by switching, or may include one or more antennas or a plurality of antennas for communication and one or more antennas or a plurality of antennas for sensing, where the one or more antennas or the plurality of antennas for communication differ from the one or more antennas or the plurality of antennas for sensing. 
     Note that, transmission apparatus X 301  for signals for communication and sensing may switch between transmitting a signal for sensing and transmitting a modulated signal for communication based on mode information included in control signal X 309  and transmit the signal from the antenna. That is, a mode for transmitting a signal for sensing and a mode for transmitting a modulated signal for communication may be present. Further, transmission apparatus X 301  for communication and sensing may also transmit a signal obtained by combining a signal for sensing and a modulated signal for communication. 
     Apparatus X 300  may also include, apart from the reception apparatus for communication, a reception apparatus for sensing. At this time, the reception apparatus for communication and the reception apparatus for sensing may use the same one or more antennas or the same plurality of antennas by switching, or may include one or more antennas or a plurality of antennas for communication and one or more antennas or a plurality of antennas for sensing, where the one or more antennas or the plurality of antennas for communication differ from the one or more antennas or the plurality of antennas for sensing. 
     Further, apparatus X 300  may also include a transmission apparatus for communication, a transmission apparatus for sensing, a reception apparatus for communication, and a reception apparatus for sensing separately from each another. Further, apparatus X 300  may also include a transmission-reception apparatus for communication and a transmission-reception apparatus for sensing. Further, apparatus X 300  may also include a transmission-reception apparatus for communication, a transmission apparatus for sensing, and a reception apparatus for sensing. 
     Further, in  FIG.  3   , in the same manner as in the descriptions with reference to  FIGS.  1  and  2   , one or more antennas for transmission or a plurality of antennas for transmission may be formed of one or more antenna units or a plurality of antenna units, and one or more antennas for reception or a plurality of antennas for reception may be formed of one or more antenna units or a plurality of antenna units. Further, the one or more antennas for transmission or the plurality of antennas for transmission and the one or more antennas for reception or the plurality of antennas for reception may be formed as a common transmission and reception antenna processor. 
       FIG.  4    illustrates an example of a communication system according to the present invention. As an example, a base station and terminals communicate with each other. The base station has at least a communication function, and therefore has the configuration of apparatus X 200  in  FIG.  2    or apparatus X 300  in  FIG.  3   . 
     The terminal may or may not have a communication function. For example, terminal # 4  in  FIG.  4    may have a function of sensing of an object and may not have a communication function. Thus, the terminals having a communication function (terminals # 1 , # 2 , and # 3  in  FIG.  3   ) have the configuration of apparatus X 200  in  FIG.  2    or apparatus X 300  in  FIG.  3   . The terminal having no communication function (terminal # 4  in  FIG.  3   ) has the configuration of apparatus X 100  in  FIG.  1   . 
     Hereinafter, an exemplary embodiment in a case where a modulated signal for communication and a signal for sensing are present in the same frequency band will be described. 
       FIG.  5    illustrates a configuration example of a frame for data transmission transmitted by a base station and a terminal having a communication function. The preamble illustrated in  FIG.  5    is, for example, a symbol for a communication partner to perform signal detection, time synchronization, frequency synchronization, channel estimation, frequency offset estimation, and the like. 
     The control information symbol is a symbol for transmitting information on a data size, a method of transmitting a data symbol (for example, a modulation and coding scheme (MCS) such as the number of transmission streams and an error correction coding method), and the like. 
     The data symbol is a symbol for transmitting data. The data symbol may include other symbols (for example, a reference symbol, a pilot symbol, a pilot carrier, or the like). 
     The frame configuration for the frame for data transmission is not limited to the above example. The frame for data transmission may include symbols other than those illustrated in  FIG.  5   . 
       FIGS.  6 A and  6 B  illustrate configuration examples of a frame for sensing transmitted by a base station and a terminal which have a sensing function.  FIG.  6 A  illustrates a first example of the frame for sensing and  FIG.  6 B  illustrates a second example of the frame for sensing. 
     The first example of the frame for sensing in  FIG.  6 A  is formed of a reference symbol for sensing. However, other symbols may also be included in the frame for sensing. 
     The base station and the terminal perform sensing processing by using the reference symbol for sensing in  FIG.  6 A . The base station and the terminal may temporally continuously transmit reference symbols for sensing. Note that, although the term “reference symbol for sensing” is used, an unmodulated signal or a signal such as a carrier wave may also be used. In this regard, the same applies to  FIG.  6 B . 
     The second example of the frame for sensing in  FIG.  6 B  is formed of, for example, a preamble, a control information symbol, and a reference symbol for sensing. However, other symbols may also be included in the frame for sensing. 
     The base station and the terminal perform sensing processing by using the reference symbol for sensing in  FIG.  6 B . 
     The preamble in  FIG.  6 B  is, for example, a symbol for a communication partner to perform signal detection, time synchronization, frequency synchronization, channel estimation, frequency offset estimation, and the like. Note that, it is assumed that the base station and the terminal which have a communication function can also detect this preamble. For example, the configuration of the preamble may be the same (or may not be the same) as that of the preamble in  FIG.  5   . 
     In this way, the base station and the terminal which has a communication function can know the presence of a frame for sensing so that it is possible to obtain the effect that interference between a frame for sensing and a frame for communication can be reduced. 
     The control information symbol in  FIG.  6 B  is a symbol including information on a reference symbol for sensing. The control information symbol may also include other information. 
     Examples of the information on a reference symbol for sensing include as follows: 
     The type of a sensing reference signal, which is assumed to be designatable from a plurality of symbol types, for example; 
     The frequency band of a sensing reference signal, which is assumed to be designatable from a plurality of frequency bands, for example; and 
     The time domain of a sensing reference signal, which is assumed to be designatable from a plurality of time intervals, for example. 
     The base station and the terminal which have a sensing function can configure a desired sensing accuracy by designating the information on a reference symbol for sensing in the control information symbol. However, the information in the control information symbol is not limited thereto. 
     The base station and the terminal perform sensing processing by using the reference symbol for sensing in  FIG.  6 B . The base station and the terminal may temporally continuously transmit reference symbols for sensing. 
     The configuration of the frame for sensing is not limited to those in  FIGS.  6 A and  6 B . The frame for sensing may include symbols other than those illustrated in  FIGS.  6 A and  6 B . 
       FIG.  7    illustrates an example of a frame state in a time axis of a certain frequency band. As illustrated in  FIG.  7   , for example, the base station may switch between the frame for data transmission and the frame for sensing for transmission thereof. The terminal may switch between the frame for data transmission and the frame for sensing for transmission thereof. 
     It is desirable that the base station and the terminal transmit frames and perform control such that the frames do not overlap at a certain frequency, that is, the frames do not interfere with each other as in  FIG.  7   , for example. 
       FIG.  8    illustrates another example of a frame state in a time axis of a certain frequency band. As illustrated in  FIG.  8   , for example, the base station may switch among the frame for data transmission, the frame for sensing, and the frame, in which a symbol for data transmission and a sensing signal are present, for transmission thereof. The terminal may switch among the frame for data transmission, the frame for sensing, and the frame, in which a symbol for data transmission and a sensing signal are present, for transmission thereof. 
     The base station and the terminal transmit frames and perform control such that the frames do not overlap at a certain frequency, that is, the frames do not interfere with each other as in  FIG.  8   , for example. 
     Note that, although a case where the frequency (or frequency band) of a signal transmitted by a base station and the frequency (or frequency band) of a signal transmitted by a terminal are partially the same or are the same has been described above as an example, the present disclosure is not limited to this example, and the frequency (or frequency band) of a signal transmitted by a base station and the frequency (or frequency band) of a signal transmitted by a terminal may be different. At this time, the temporal timing when the base station transmits a signal and the temporal timing when the terminal transmits a signal are not limited to the example described above as long as the signals do not interfere with each other, and the timings may be the same or may be different. 
     Another example when the base station in  FIG.  4    transmits a signal will be described.  FIG.  9    illustrates an exemplary state when a base station transmits signals, in which the horizontal axis indicates time and the vertical axis indicates frequency. Note that, it is assumed that the base station transmits, as the signal, a signal using a multicarrier transmission method such as orthogonal frequency division multiplexing (OFDM), for example. 
     In  FIG.  9   , “RESOURCE FOR TERMINAL # 1   901 ” indicates a resource to be transmitted by the base station to terminal # 1  in  FIG.  4   , “RESOURCE FOR TERMINAL # 2   902 ” indicates a resource to be transmitted by the base station to terminal # 2  in  FIG.  4   , “RESOURCE FOR TERMINAL # 3   903 ” indicates a resource to be transmitted by the base station to terminal # 3  in  FIG.  4   , and “RESOURCE FOR SENSING  904 ” indicates a resource to be transmitted by the base station in  FIG.  4    for sensing. In  FIG.  9   , it is assumed that “RESOURCE FOR TERMINAL # 1   901 ”, “RESOURCE FOR TERMINAL # 2   902 ”, “RESOURCE FOR TERMINAL # 3   903 ” and “RESOURCE FOR SENSING  904 ” are present in time T 1 . 
     “RESOURCE FOR TERMINAL # 1   911 ” indicates a resource to be transmitted by the base station to terminal # 1  in  FIG.  4   . “RESOURCE FOR TERMINAL # 2   912 ” indicates a resource to be transmitted by the base station to terminal # 2  in  FIG.  4   . “RESOURCE FOR TERMINAL # 3   913 ” indicates a resource to be transmitted by the base station to terminal # 3  in  FIG.  4   . “RESOURCE FOR SENSING  914 ” indicates a resource to be transmitted by the base station in  FIG.  4    for sensing. In  FIG.  9   , it is assumed that “RESOURCE FOR TERMINAL # 1   911 ”, “RESOURCE FOR TERMINAL # 2   912 ”, “RESOURCE FOR TERMINAL # 3   913 ” and “RESOURCE FOR SENSING  914 ” are present in time T 2 . 
     As described above, it is assumed that frequency allocation for the resources for terminals and the resources for sensing can be changed timewise. Note that, the allocation method for the resources for terminals and the resources for sensing in time and frequency is not limited to the example in  FIG.  9   . 
     “RESOURCE FOR TERMINAL # 1   901 ” and “RESOURCE FOR TERMINAL # 1   911 ” may include data for terminal # 1  in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR TERMINAL # 2   902 ” and “RESOURCE FOR TERMINAL # 2   912 ” may include data for terminal # 2  in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR TERMINAL # 3   903 ” and “RESOURCE FOR TERMINAL # 3   913 ” may include data for terminal # 3  in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR SENSING  904 ” and “RESOURCE FOR SENSING  914 ” include a signal for sensing for the base station in  FIG.  4    to perform sensing. These resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     An example when terminals # 1 , # 2 , # 3 , and # 4  in  FIG.  4    transmit signals will be described.  FIG.  10    illustrates an example of a state when terminals # 1 , # 2 , # 3 , and # 4  in  FIG.  4    transmit signals, in which the horizontal axis indicates time and the vertical axis indicates frequency. Note that, it is assumed that terminals # 1 , # 2 , # 3 , and # 4  transmit, as the signals, signals using a multicarrier transmission method such as OFDM, for example. For example, terminal # 1  transmits resource for terminal # 1  signal transmission  1001  and resource for terminal # 1  signal transmission  1011 . 
     In  FIG.  10   , “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1001 ” indicates a resource transmitted by terminal # 1  in  FIG.  4    to the base station, “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1002 ” indicates a resource transmitted by terminal # 2  in  FIG.  4    to the base station, “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1003 ” indicates a resource transmitted by terminal # 3  in  FIG.  4    to the base station, and “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1004 ” indicates a resource transmitted by terminal # 4  in  FIG.  4    to the base station. In  FIG.  10   , it is assumed that “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1001 ”, “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1002 ”, “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1003 ”, and “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1004 ” are present in time t 1 . 
     “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1011 ” indicates a resource transmitted by terminal # 1  in  FIG.  4    to the base station. “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1012 ” indicates a resource transmitted by terminal # 2  in  FIG.  4    to the base station. “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1013 ” indicates a resource transmitted by terminal # 3  in  FIG.  4    to the base station. “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1004 ” indicates a resource transmitted by terminal # 4  in  FIG.  4    to the base station. In  FIG.  10   , it is assumed that “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1011 ”, “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1012 ”, “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1013 ”, and “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1014 ” are present in time t 2 . 
     As described above, it is assumed that frequency allocation for the resources for terminal signal transmission can be changed timewise. Note that, the allocation method for the resources for terminal signal transmission in time and frequency is not limited to the example in  FIG.  10   . 
     “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1001 ” and “RESOURCE FOR TERMINAL # 1  SIGNAL TRANSMISSION  1011 ” may include data for the base station in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1002 ” and “RESOURCE FOR TERMINAL # 2  SIGNAL TRANSMISSION  1012 ” may include data for the base station in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1003 ” and “RESOURCE FOR TERMINAL # 3  SIGNAL TRANSMISSION  1013 ” may include data for the base station in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1004 ” and “RESOURCE FOR TERMINAL # 4  SIGNAL TRANSMISSION  1014 ” may include data for the base station in  FIG.  4    and may include a signal for sensing. Further, these resources may include control information and include a reference signal that allows time synchronization, frequency synchronization, frequency offset estimation, phase noise estimation, and the like. Further, these resources may include signals other than those described above. 
     Note that, the signals for sensing herein, such as the frames for sensing and the resources for sensing, include signals capable of realizing sensing. As examples of the “signals capable of realizing sensing”, albeit not limited thereto, pilot symbols, pilot signals, reference symbols, reference signals, preambles, mid-ambles, known signals, known symbols, and the like are applicable. Further, data may be transmitted by “signals capable of realizing sensing”. 
     The triangulation has been described above. Hereinafter, methods of triangulation other than the triangulation described above will be described. 
     First Method: 
     Triangulation can be realized by performing processing A, processing B, processing C, and processing D each of which will be described below. 
     Processing A: 
       FIG.  11    illustrates a system configuration example provided for describing an example of triangulation. In  FIG.  11   , first apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off second apparatus  1102 , and first apparatus  1101  obtains this reflected signal to thereby acquire (recognize) a “distance between first apparatus  1101  and second apparatus  1102 ”. 
     Further, as another method, second apparatus  1102  transmits a signal by using a radio wave, for example. First apparatus  1101  obtains this signal to thereby acquire the “distance between first apparatus  1101  and second apparatus  1102 ”. 
     Note that, first apparatus  1101  and second apparatus  1102  may share information on the “distance between first apparatus  1101  and second apparatus  1102 ”. 
     Processing B: 
     First apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and first apparatus  1101  obtains this reflected signal to thereby acquire a “distance between first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  and second apparatus  1102  may share information on the “distance between first apparatus  1101  and target (object)  1103 ”. 
     Processing C: 
     Second apparatus  1102  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and second apparatus  1102  obtains this reflected signal to thereby acquire a “distance between second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  and first apparatus  1101  may share information on the “distance between second apparatus  1102  and target (object)  1103 ”. 
     Processing D: 
     First apparatus  1101  and/or second apparatus  1102  have/has acquired information on the “distance between first apparatus  1101  and second apparatus  1102 ”, information on the “distance between first apparatus  1101  and target (object)  1103 ”, and information on the “distance between second apparatus  6602  and target (object)  1103 ” by processing A, processing B, and processing C, and perform(s) triangulation by using these pieces of information to acquire (calculate) the position of target (object)  1103 . 
     Second Method: 
     Triangulation can be realized by performing processing E, processing F, processing G, and processing H each of which will be described below 
     Processing E: 
     In  FIG.  11   , it is assumed that first apparatus  1101  and/or second apparatus  1102  retain(s) information on a “distance between first apparatus  1101  and second apparatus  1102 ” at the time of installation, for example, 
     Processing F: 
     First apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and first apparatus  1101  obtains this reflected signal to thereby acquire a “distance between first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  and second apparatus  1102  may share information on the “distance between first apparatus  1101  and target (object)  1103 ”. 
     Processing G: 
     Second apparatus  1102  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and second apparatus  1102  obtains this reflected signal to thereby acquire a “distance between second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  and first apparatus  1101  may share information on the “distance between second apparatus  1102  and target (object)  1103 ”. 
     Processing H: 
     First apparatus  1101  and/or second apparatus  1102  have/has acquired information on the “distance between first apparatus  1101  and second apparatus  1102 ”, information on the “distance between first apparatus  1101  and target (object)  1103 ”, and information on the “distance between second apparatus  1102  and target (object)  1103 ” by processing E, processing F, and processing G, and perform(s) triangulation by using these pieces of information to acquire (calculate) the position of target (object)  1103 . Note that, first apparatus  1101  and second apparatus  1102  may form one apparatus. 
     Third Method: 
     Triangulation can be realized by performing processing XA, processing XB, processing XC, and processing XD each of which will be described below. 
     Processing XA: 
     In  FIG.  11   , first apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off second apparatus  1102 , and first apparatus  1101  obtains this reflected signal to thereby acquire a “distance between first apparatus  1101  and second apparatus  1102 ”. 
     As another method, second apparatus  1102  transmits a signal by using a radio wave, for example. First apparatus  1101  obtains this signal to thereby be capable of acquiring the “distance between first apparatus  1101  and second apparatus  1102 ”. 
     Note that, first apparatus  1101  and second apparatus  1102  may share information on the “distance between first apparatus  1101  and second apparatus  1102 ”. 
     Processing XB: 
     First apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and first apparatus  1101  obtains this reflected signal to thereby acquire a “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  and second apparatus  1102  may share information on the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  obtains a “direction (of arrival) of second apparatus  1102  and target (object)  1103 ” to thereby be capable of obtaining an estimated value of an “angle formed by a first line segment and a second line segment” where “the first line segment is a line segment formed by first apparatus  1101  and second apparatus  1102 ” and “the second line segment is a line segment formed by first apparatus  1101  and target (object)  1103 , for example. 
     Processing XC: 
     Second apparatus  1102  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and second apparatus  1102  obtains this reflected signal to thereby acquire the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  and first apparatus  1101  may share information on the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  obtains the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ” to thereby be capable of obtaining an estimated value of an “angle formed by the first line segment and a third line segment” where “the first line segment is a line segment formed by first apparatus  1101  and second apparatus  1102 ” and “the third line segment is a line segment formed by second apparatus  1102  and target (object)  1103 , for example. 
     Processing XD: 
     First apparatus  1101  and/or second apparatus  1102  have/has acquired information on the “distance between first apparatus  1101  and second apparatus  1102 ”, information on the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”, and information on the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ” by processing XA, processing XB, and processing XC, and performs triangulation by using these pieces of information to thereby be capable of acquiring the position of target (object)  1103 . 
     Fourth Method: 
     Triangulation can be realized by performing processing XE, processing XF, processing XG, and processing XH each of which will be described below. 
     Processing XE: 
     In  FIG.  11   , it is assumed that first apparatus  1101  and/or second apparatus  1102  retain(s) information on a “distance between first apparatus  1101  and second apparatus  1102 ” at the time of installation, for example. 
     Processing XF: 
     First apparatus  1101  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and first apparatus  1101  obtains this reflected signal to thereby acquire a “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  and second apparatus  1102  may share information on the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”. Note that, first apparatus  1101  obtains a “direction (of arrival) of second apparatus  1102  and target (object)  1103 ” to thereby be capable of obtaining an estimated value of an “angle formed by a first line segment and a second line segment” where “the first line segment is a line segment formed by first apparatus  1101  and second apparatus  1102 ” and “the second line segment is a line segment formed by first apparatus  1101  and target (object)  1103 , for example. 
     Processing XG: 
     Second apparatus  1102  transmits a signal by using a radio wave, for example. This signal reflects off target (object)  1103 , and second apparatus  1102  obtains this reflected signal to thereby acquire the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  and first apparatus  1101  may share information on the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ”. Note that, second apparatus  1102  obtains the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ” to thereby be capable of obtaining an estimated value of an “angle formed by the first line segment and a third line segment” where “the first line segment is a line segment formed by first apparatus  1101  and second apparatus  1102 ” and “the third line segment is a line segment formed by second apparatus  1102  and target (object)  1103 , for example. 
     Processing XH: 
     First apparatus  1101  and/or second apparatus  1102  have/has acquired information on the “distance between first apparatus  1101  and second apparatus  1102 ”, information on the “direction (of arrival) of first apparatus  1101  and target (object)  1103 ”, and information on the “direction (of arrival) of second apparatus  1102  and target (object)  1103 ” by processing XE, processing XF, and processing XG, and performs triangulation by using these pieces of information to thereby be capable of acquiring the position of target (object)  1103 . Note that, first apparatus  1101  and second apparatus  1102  may form one apparatus. 
     In the present embodiment, a sensing method related to the present invention has been described above. The present invention to be described below makes it possible to perform highly-accurate “sensing of position estimation, detection of an object, distance estimation, and the like” by using the sensing method described in the present embodiment, for example. Note that, the sensing method described in the present embodiment is merely an example, and the sensing method is not limited to that described in the present embodiment. 
     Embodiment 2 
     In the present embodiment, a “sensing system” or “sensing and communication system” using the sensing method described in Embodiment 1 will be described. 
       FIG.  12    illustrates an example of the “sensing system” or “sensing and communication system” in the present embodiment. 
     In  FIG.  12   , base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  communicate with a terminal. 
     First apparatus  1201  is, for example, a terminal, and communicates with base station # 1  of  1202 _ 1  and/or base station # 2  of  1202 _ 2  and/or base station # 3  of  1202 _ 3 . 
     Target (object)  1203  is a target object whose position is estimated by sensing. 
     In the present embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 1  of  1202 _ 1 ”, “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the “triangulation described in Embodiment 1 with first apparatus  1201  and base station # 3  of  1202 _ 3 ” will be described as an example. 
     It is assumed that first apparatus  1201  is an apparatus having a function of performing sensing described in Embodiment 1. Further, it is assumed that first apparatus  1201  has a communication function and communicates with, for example, base station # 1  of  1202 _ 1 , bases station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with one of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , base station # 3  of  1202 _ 3  to realize triangulation. However, it is supposed that there is/are a base station(s) that does/do not correspond to sensing due to factors such as the size of the base station(s) and the time of the installation. 
     Accordingly, it is assumed that base stations such as base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  transmit control information including information on sensing capability  1301  as illustrated in subsequent  FIG.  13   . 
     Note that, it is assumed that the control information including information on sensing capability  1301  is transmitted by a base station using a physical broadcast channel (PBCH), a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH), for example. The channel through which the above control information is transmitted is not limited to the examples described above. 
       FIG.  13    is a diagram provided for describing an example of information on sensing capability. As illustrated in  FIG.  13   , it is assumed that information on sensing capability  1301  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and/or “INFORMATION ON WHETHER. SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”: 
     This information is used to notify, for example, a terminal, a repeater, other base station(s) or the like of “whether a base station is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, it is assumed that a base station that transmits information  1311  has a sensing function. Further, it is assumed that this base station has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether sensing is performable” when a base station receives a sensing request from the terminal (a request of the terminal for the base station to perform sensing). 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” may also be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another apparatus, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether a base station accepts sensing from the terminal” when the base station receives a sensing request from the terminal (a request of the terminal for the base station to perform sensing). 
     Accordingly, there are modes in which, even when there is a sensing request from a terminal, a base station “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” may be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, a terminal, a repeater, another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with a base station” can be performed. 
     Note that, the apparatus that transmits information on sensing capability  1301  in  FIG.  13    has been described as a base station above, but is merely an example, and information on sensing capability  1301  may be transmitted by a communication apparatus such as a repeater, a terminal, and an access point. 
     Further, although the description “[ . . . ] SENSING REQUEST FROM TERMINAL” is used in “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” and “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” which are transmitted by the apparatus that transmits information on sensing capability  1301  in  FIG.  13   , a sensing request may be not from a terminal, but may be from, for example, a communication apparatus such as a base station, a repeater, and an access point. Accordingly, implementation is also possible with  1312  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS PERFORMABLE OR NOT PERFORMABLE” and  1313  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS ACCEPTABLE OR NOT ACCEPTABLE”. 
     Next, operations of first apparatus  1201  and base station # 2  of  1202 _ 2  in  FIG.  12    will be described as an example. 
     Note that, first apparatus  1201  may be a terminal capable of communicating with a base station. Alternatively, first apparatus  1201  may be a base station. In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. Further, first apparatus  1201  in  FIG.  12    may be a repeater, and base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  may be repeaters. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  12   , distance-based triangulation whose examples are the first method and the second method, and direction-based triangulation whose examples are the third method and the fourth method will be described separately. 
     Case of Distance-Based Triangulation: 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     First apparatus  1201  obtains information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and acquires each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
       FIG.  14    illustrates a procedure example for sensing in the system example in  FIG.  12   . In  FIG.  14   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1405 ” is performed. 
     Further, in  FIG.  14   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1402 ” is performed. 
     Before describing  FIG.  14   , a method of obtaining information on a “distance between first apparatus  1201  and the base station” will be described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F . Note that, in this case, the base station is base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , or base station # 3  of  1202 _ 3 . 
     In  FIG.  15 A , base station  1501  first transmits a signal ( 1501 ). Then, first apparatus  1201  receives this signal to thereby estimate the “distance between first apparatus  1201  and the base station” ( 1502 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1 a description thereof will be omitted. 
     As another method, in  FIG.  15 B , first apparatus  1201  first transmits a signal to the base station ( 1511 ). Then, first apparatus  1201  receives this signal and estimates the “distance between first apparatus  1201  and the base station” ( 1512 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  15 C , first apparatus  1201  first transmits a signal to the base station ( 1521 ). Then, the base station receives this signal and estimates the “distance between first apparatus  1201  and the base station” ( 1522 ). The base station transmits a modulated signal including information on the “distance between first apparatus  1201  and the base station” to first apparatus  1201  ( 1523 ). First apparatus  1201  receives the modulated signal including the information on the “distance between first apparatus  1201  and the base station” and obtains the information on the “distance between first apparatus  1201  and the base station” ( 1524 ). 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     First apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS (Global Positioning System, Global Positioning Satellite), for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     As another method, in  FIG.  15 D , first apparatus  1201  first transmits a signal to the base station ( 1531 ). The base station receives this signal and estimates the “distance between first apparatus  1201  and the base station” ( 1532 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  15 E , the base station first transmits a signal to first apparatus  1201  ( 1541 ). The base station receives this signal and estimates the “distance between first apparatus  1201  and the base station” ( 1542 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  15 F , the base station first transmits a signal to first apparatus  1201  ( 1551 ). First apparatus  1201  receives this signal and estimates the “distance between first apparatus  1201  and the base station” ( 1552 ). First apparatus  1201  transmits a modulated signal including information on the “distance between first apparatus  1201  and the base station” to the base station ( 1553 ). The base station receives the modulated signal including the information on the “distance between first apparatus  1201  and the base station” and obtains the information on the “distance between first apparatus  1201  and the base station” ( 1554 ). 
     Examples of the method of obtaining information on a “distance between first apparatus  1201  and the base station” have been described above with reference to  FIGS.  15 A to  15 F . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  14   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  12    to obtain an estimated value of a “distance between first apparatus  1201  and target  1203 ” ( 1401 ). 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “distance between first apparatus  1201  and target  1203 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 1402 ). 
     Note that, it is assumed in the example of  FIG.  14    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the distance to target  1203 . However, when the base station which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1402 ” may not be performed. 
     Further, first apparatus  1201  may also broadcast information for requesting sensing. First apparatus  1201  may select a base station, which senses a target, from base stations that have returned a response to the request. For example, as described in  FIG.  17   , first apparatus  1201  may select a base station, which senses a target, such that first apparatus  1201 , the base station, and the target form an obtuse triangle. Note that, an example of the channel of the broadcast is as described herein. 
     First apparatus  1201  transmits information on a request for “performing estimation of a distance to target  1203 ” to base station # 2  of  1202 _ 2  ( 1403 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “performing the estimation of the distance to target  1203 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1411 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1404 ). 
     Base station # 2  of  1202 _ 2  transmits a signal for performing sensing and obtains an estimated value of a “distance between base station # 2  of  1202 _ 2  and target  1203 ” ( 1412 ). 
     Base station # 2  of  1202 _ 2  transmits information on the “distance between base station # 2  of  1202 _ 2  and target  1203 ” to first apparatus  1201  ( 1413 ). 
     First apparatus  1201  obtains the information on the “distance between base station # 2  of  1202 _ 2  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “distance between first apparatus  1201  and target  1203 ”, and the “distance between base station # 2  of  1202 _ 2  and target  1203 ”, and estimates the position of target  1203 , for example ( 1405 ). 
     First apparatus  1201  transmits information on the “position of target  1203 ” to base station # 2  of  1202 _ 2  ( 1406 ). 
     Note that, in a case where first apparatus  1201  and base station # 2  of  1202 _ 2  do not need to share the information on the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the “position of target  1203 ” to base station # 2  of  1202 _ 2 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Next, another example when the distance-based triangulation whose examples are the first method and the second method is used will be described with reference to  FIG.  16   . 
       FIG.  16    illustrates another procedure example for sensing. It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  16   , it is assumed that base station # 2  of  1202 _ 2  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. Further, first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. 
     Further, in  FIG.  16   , it is assumed that base station # 2  of  1202 _ 2  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1602 ” is performed. Further, in  FIG.  16   , first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  16   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  12    to obtain an estimated value of a “distance between first apparatus  1201  and target  1203 ” ( 1601 ). 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “distance between first apparatus  1201  and target  1203 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 1602 ). 
     Note that, it is assumed in the example of  FIG.  16    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the distance to target  1203 . However, when the base station which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1602 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a distance to target  1203 ” to base station # 2  of  1202 _ 2  ( 1603 ). Further, first apparatus  1201  transmits information on the “distance between first apparatus  1201  and target  1203 ” to base station # 2  of  1202 _ 2  ( 1603 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the distance to target  1203 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1611 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1604 ). 
     Base station # 2  of  1202 _ 2  transmits a signal for performing sensing and obtains an estimated value of a “distance between base station # 2  of  1202 _ 2  and target  1203 ” ( 1612 ). 
     Base station # 2  of  1202 _ 2  obtains the information on the “distance between base station # 2  of  1202 _ 2  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “distance between first apparatus  1201  and target  1203 ”, and the “distance between base station # 2  of  1202 _ 2  and target  1203 ”, and estimates the position of target  1203 , for example ( 1613 ). 
     Note that, base station # 2  of  1202 _ 2  obtains the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” at one stage. 
     Base station # 2  of  1202 _ 2  transmits information on an estimation result of the “position of target  1203 ” to first apparatus  1201  ( 1614 ). 
     Note that, in a case where base station # 2  of  1202 _ 2  and first apparatus  1201  do not need to share the information on the estimation result of the “position of target  1203 ”, base station # 2  of  1202 _ 2  may not transmit the information on the estimation result of the “position of target  1203 ” to first apparatus  1201 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  14   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1405 ” is performed. 
     Further, in  FIG.  14   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1402 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  14   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  12    to obtain an estimated value of a “direction (of arrival) of first apparatus  1201  and target  1203 ” ( 1401 ). 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a direction (of arrival) with target  1203 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 1402 ). 
     Note that, it is assumed in the example of  FIG.  14    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the direction (of arrival) with target  1203 . However, when the base station which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1402 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to base station # 2  of  1202 _ 2  ( 1403 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1411 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1404 ). 
     Base station # 2  of  1202 _ 2  transmits a signal for performing sensing and obtains an estimated value of a “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ” ( 1412 ). 
     Base station # 2  of  1202 _ 2  transmits information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ” to first apparatus  1201  ( 1413 ). 
     First apparatus  1201  obtains the information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and the “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ”, and estimates the position of target  1203 , for example ( 1405 ). 
     First apparatus  1201  transmits information on the “position of target  1203 ” to base station # 2  of  1202 _ 2  ( 1406 ). 
     Note that, in a case where first apparatus  1201  and base station # 2  of  1202 _ 2  do not need to share the information on the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the “position of target  1203 ” to base station # 2  of  1202 _ 2 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Next, another example when the direction-based triangulation whose examples are the third method and the fourth method is used will be described with reference to  FIG.  16   . 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1  base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  16   , it is assumed that base station # 2  of  1202 _ 2  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. Further, first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. 
     Further, in  FIG.  16   , it is assumed that base station # 2  of  1202 _ 2  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF TARGET  1602 ” is performed. Further, in  FIG.  16   , first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  1613 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  16   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  12    to obtain an estimated value of a “direction (of arrival) of first apparatus  1201  and target  1203 ” ( 1601 ). 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a direction (of arrival) with target  1203 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 1602 ). 
     Note that, it is assumed in the example of  FIG.  16    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the direction (of arrival) with target  1203 . However, when the base station which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET)  1602 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to base station # 2  of  1202 _ 2  ( 1603 ). Further, first apparatus  1201  transmits information on the “direction (of arrival) of first apparatus  1201  and target  1203 ” to base station # 2  of  1202 _ 2  ( 1603 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1611 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1604 ). 
     Base station # 2  of  1202 _ 2  transmits a signal for performing sensing and obtains an estimated value of a “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ” ( 1612 ). 
     Base station # 2  of  1202 _ 2  obtains the information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and the “direction (of arrival) of base station # 2  of  1202 _ 2  and target  1203 ”, and estimates the position of target  1203 , for example ( 1613 ). 
     Note that, base station # 2  of  1202 _ 2  obtains the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” at one stage. 
     Base station # 2  of  1202 _ 2  transmits information on an estimation result of the “position of target  1203 ” to first apparatus  1201  ( 1614 ). 
     Note that, in a case where base station # 2  of  1202 _ 2  and first apparatus  1201  do not need to share the information on the estimation result of the “position of target  1203 ”, base station # 2  of  1202 _ 2  may not transmit the information on the estimation result of the “position of target  1203 ” to first apparatus  1201 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     An example of base station selection will be described. In the above description, in  FIG.  14   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 1401 )” before “SELECT BASE STATION OF SENSING OF TARGET ( 1402 )” is performed. In the same manner, in  FIG.  16   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 1601 )” before “SELECT BASE STATION FOR SENSING OF TARGET (SENSING TARGET) ( 1602 )” is performed. 
       FIG.  17    is a diagram provided for describing an example of base station selection. In  FIG.  17   , parts which operate in the same manner as in  FIG.  12    are denoted with the same numbers, and descriptions thereof will be omitted. 
     In  FIG.  17   , in a case where “first apparatus  1201 ” and “base station # 2  of  1202 _ 2 ” are apparatuses that sense target (object)  1203  (sense the target), the triangle formed by triangulation is “second triangle  1702 ”. 
     In a case where “first apparatus  1201 ” and “base station # 3  of  1202 _ 3 ” are apparatuses that sense target (object)  1203 , on the other hand, the triangle formed by triangulation is “third triangle  1703 ”. 
     At this time, second triangle  1702  is an obtuse triangle, and third triangle  1703  is an acute triangle. At this time, when an estimation error occurs in sensing in the acute triangle state, an estimation error in position estimation or the like may become large. Given this point, second triangle  1702  may be more suitable for sensing. 
     Thus, in  FIG.  14   , first apparatus  1201  can select the state of the triangle by means of base station selection by performing “PERFORM SENSING OF TARGET (SENSING TARGET) ( 1401 )” before “SELECT BASE STATION OF SENSING OF TARGET (THAT SENSES TARGET) ( 1402 )” is performed, so that estimation errors due to sensing may be reduced. 
     In the same manner, in  FIG.  16   , first apparatus  1201  can select the state of the triangle by means of base station selection by performing “PERFORM SENSING OF TARGET ( 1601 )” before “SELECT BASE STATION FOR SENSING OF TARGET (THAT SENSES TARGET) ( 1602 )” is performed, so that estimation errors due to sensing may be reduced. 
     By performing as described above, it is possible to perform highly-accurate triangulation so that it is possible to obtain the effect that each apparatus can grasp the position of a target or the like. 
     Note that, in a case where first apparatus  1201  and the base station “grasp positions (or position information) on the map in advance” or in a case where first apparatus  1201  and the base station “can grasp positions (or position information) on the map by, for example, a position estimation system such as GPS”, each apparatus can grasp the position (or position information) of a target on the map. 
     Further, in a case where first apparatus  1201  “transmits information on a sensing request” to the base station in  FIG.  14  or  16   , the communication may be radio communication or may be wired communication. 
     Further, signals transmitted by, for example, base stations, terminals, and repeaters for sensing a target (object) in the above description may be referred to as reference signals, reference symbols, pilot symbols, pilot signals, or preamble, although the designations are not limited to the above examples. 
     Next, an exemplary embodiment that differs from those in  FIGS.  12 ,  14  and  16    will be described. An exemplary embodiment in a case where a target transmits a radio wave will be described. 
       FIG.  18    illustrates an example of the “sensing system” or “sensing and communication system” exemplified here. In  FIG.  18   , parts which operate in the same manner as in  FIG.  12    are denoted with the same numbers and have already been described. Accordingly, descriptions thereof will be omitted. 
     In  FIG.  18   , second apparatus  1802  is a target object whose position is estimated by sensing. 
     In this exemplary embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 1  of  1202 _ 1 ”, “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the “triangulation described in Embodiment 1 with first apparatus  1201  and base station # 3  of  1202 _ 3 ” will be described as an example. 
     It is assumed that first apparatus  1201  is an apparatus having a function of performing sensing described in Embodiment 1. Further, it is assumed that first apparatus  1201  has a communication function and communicates with, for example, base station # 1  of  1202 _ 1 , bases station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     It is assumed that second apparatus  1802  in  FIG.  18    is an apparatus capable of transmitting a radio wave. 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with one of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , base station # 3  of  1202 _ 3  to realize triangulation. However, it is supposed that there is/are a base station(s) that does/do not correspond to sensing due to factors such as the size of the base station(s) and the time of the installation. 
     Accordingly, it is assumed that base stations such as base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  transmit control information including information on sensing capability  1301  as illustrated in  FIG.  13   . 
     Note that, it is assumed that the control information including information on sensing capability  1301  is transmitted by a base station using a PBCH, a PDSCH or a PDCCH, for example. The channel through which the above control information is transmitted is not limited to the examples described above. 
     As illustrated in  FIG.  13   , it is assumed that information on sensing capability  1301  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and/or “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”: 
     This information is used to notify, for example, a terminal, a repeater, other base station(s) or the like of “whether a base station is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, it is assumed that a base station that transmits information  1311  has a sensing function. Further, it is assumed that this base station has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether sensing is performable” when a base station receives a sensing request from the terminal. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” may also be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another apparatus, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMMION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether a base station accepts sensing from the terminal” when there is a sensing request for the base station from the terminal. 
     Accordingly, there are modes in which, even when there is a sensing request from a terminal, a base station “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” may be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, a terminal, a repeater, another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with a base station” can be performed. 
     Next, operations of first apparatus  1201 , second apparatus  1802 , and base station # 2  of  1202 _ 2  in  FIG.  18    will be described as an example. 
     Note that, first apparatus  1201  may be a terminal capable of communicating with a base station. Alternatively, first apparatus  1201  may be a base station. In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. Further, first apparatus  1201  in  FIG.  12    may be a repeater, and base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  may be repeaters. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  12   , distance-based triangulation whose examples are the first method and the second method, and direction-based triangulation whose examples are the third method and the fourth method will be described separately. 
     Case of Distance-Based Triangulation: 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     First apparatus  1201  obtains information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and acquires each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
       FIG.  19    illustrates a procedure example for sensing in the system example in  FIG.  18   . In  FIG.  19   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  1905 ” is performed. 
     Further, in  FIG.  19   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS (THAT SENSES SECOND APPARATUS)  1902 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  19   , second apparatus  1802  transmits a signal (for sensing) ( 1921 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between first apparatus  1201  and second apparatus  1802 ” ( 1901 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a distance to second apparatus  1802 , based on the estimated value of the “distance between first apparatus  1201  and second apparatus  1802 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  12023 ” ( 1902 ). 
     Note that, it is assumed in the example of  FIG.  19    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  18    as the base station which is requested to perform the estimation of the distance to second apparatus  1802 . However, when the base station which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS  1802  (SENSING SECOND APPARATUS)  1402 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 1903 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the distance to second apparatus  1802 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1911 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1904 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 1922 ). 
     Base station # 2  of  1202 _ 2  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ” ( 1912 ). 
     Base station # 2  of  1202 _ 2  transmits information on the “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ” to first apparatus  1201  ( 1913 ). 
     First apparatus  1201  obtains the information on the “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “distance between first apparatus  1201  and second apparatus  1802 ”, and the “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 1905 ). 
     First apparatus  1201  transmits information on the “position of second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 1906 ). 
     Note that, in a case where first apparatus  1201  and base station # 2  of  1202 _ 2  do not need to share the information on the “position of second apparatus  1802 ”, first apparatus  1201  may not transmit the information on the “position of second apparatus  1802 ” to base station # 2  of  1202 _ 2 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Next, another example when the distance-based triangulation whose examples are the first method and the second method is used will be described with reference to  FIG.  20   . 
       FIG.  20    illustrates another procedure example for sensing in the system example in  FIG.  18   . It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  20   , it is assumed that base station # 2  of  1202 _ 2  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. Further, first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. 
     Further, in  FIG.  20   , it is assumed that base station # 2  of  1202 _ 2  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS (THAT SENSES SECOND APPARATUS)  2002 ” is performed. Further, in  FIG.  20   , first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its ow position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  20   , second apparatus  1802  transmits a signal (for sensing) ( 2021 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between first apparatus  1201  and second apparatus  1802 ” ( 2001 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a distance to second apparatus  1802 , based on the estimated value of the “distance between first apparatus  1201  and second apparatus  1802 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 2002 ). 
     Note that, it is assumed in the example of  FIG.  20    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the distance to second apparatus  1802 . However, when the base station which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS  1802  (SENSING SECOND APPARATUS)  2002 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 2003 ). Further, first apparatus  1201  transmits information on the “distance between first apparatus  1201  and second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 2003 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the distance to second apparatus  1802 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 2011 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 2004 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 2022 ). 
     Base station # 2  of  1202 _ 2  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ” ( 2012 ). 
     Base station # 2  of  1202 _ 2  obtains information on the “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “distance between first apparatus  1201  and second apparatus  1802 ”, and the “distance between base station # 2  of  1202 _ 2  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 2013 ). 
     Note that, base station # 2  of  1202 _ 2  obtains the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” at one stage. 
     Base station # 2  of  1202 _ 2  transmits information on an estimation result of the “position of second apparatus  1802 ” to first apparatus  1201  ( 2014 ). 
     Note that, in a case where base station # 2  of  1202 _ 2  and first apparatus  1201  do not need to share the information on the estimation result of the “position of second apparatus  1802 ”, base station # 2  of  1202 _ 2  may not transmit the information on the estimation result of the “position of second apparatus  1802 ” to first apparatus  1201 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  19   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  1905 ” is performed. 
     Further, in  FIG.  19   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS (THAT SENSES SECOND APPARATUS)  1902 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  19   , second apparatus  1802  transmits a signal (for sensing) ( 1921 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” ( 1901 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a direction (of arrival) with second apparatus  1802 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 1902 ). 
     Note that, it is assumed in the example of  FIG.  19    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  18    as the base station which is requested to perform the estimation of the direction (of arrival) with second apparatus  1802 . However, when the base station which is requested to perform the estimation of the direction (of arrival) with second apparatus  1802  is determined (in advance), “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS  1802  (SENSING SECOND APPARATUS)  1402 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of the direction (of arrival) with second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 1903 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 1911 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 1904 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 1922 ). 
     Base station # 2  of  1202 _ 2  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ” ( 1912 ). 
     Base station # 2  of  1202 _ 2  transmits information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ” to first apparatus  1201  ( 1913 ). 
     First apparatus  1201  obtains the information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, and the “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 1905 ). 
     First apparatus  1201  transmits information on the “position of second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 1906 ). 
     Note that, in a case where first apparatus  1201  and base station # 2  of  1202 _ 2  do not need to share the information on the “position of second apparatus  1802 ”, first apparatus  1201  may not transmit the information on the “position of second apparatus  1802 ” to base station # 2  of  1202 _ 2 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Next, another example when the direction-based triangulation whose examples are the third method and the fourth method is used will be described with reference to  FIG.  20   . 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In  FIG.  20   , it is assumed that base station # 2  of  1202 _ 2  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. Further, first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. 
     Further, in  FIG.  20   , it is assumed that base station # 2  of  1202 _ 2  has obtained information on a “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and information on a “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” before “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS (THAT SENSES SECOND APPARATUS)  2002 ” is performed. Further, in  FIG.  20   , first apparatus  1201  may have obtained at least the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF SECOND APPARATUS  2013 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station know positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  20   , second apparatus  1802  transmits a signal (for sensing) ( 2021 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” ( 2001 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects a base station, which is requested to perform estimation of a direction (of arrival) with second apparatus  1802 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, the information on the “distance between first apparatus  1201  and base station # 1  of  1202 _ 1 ”, the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the information on the “distance between first apparatus  1201  and base station # 3  of  1202 _ 3 ” ( 2002 ). 
     Note that, it is assumed in the example of  FIG.  20    that first apparatus  1201  has selected base station # 2  of  1202 _ 2  in  FIG.  12    as the base station which is requested to perform the estimation of the direction (of arrival) with second apparatus  1802 . However, when the base station which is requested to perform the estimation of the direction (of arrival) with second apparatus  1802  is determined (in advance), “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS  1802  (SENSING SECOND APPARATUS)  2002 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of the direction (of arrival) with second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 2003 ). Further, first apparatus  1201  transmits information on the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” to base station # 2  of  1202 _ 2  ( 2003 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 2011 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 2004 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 2022 ). 
     Base station # 2  of  1202 _ 2  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ” ( 2012 ). 
     Base station # 2  of  1202 _ 2  obtains the information on the “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, and the “direction (of arrival) of base station # 2  of  1202 _ 2  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 2013 ). 
     Note that, base station # 2  of  1202 _ 2  obtains the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” at one stage. 
     Base station # 2  of  1202 _ 2  transmits information on an estimation result of the “position of second apparatus  1802 ” to first apparatus  1201  ( 2014 ). 
     Note that, in a case where base station # 2  of  1202 _ 2  and first apparatus  1201  do not need to share the information on the estimation result of the “position of second apparatus  1802 ”, base station # 2  of  1202 _ 2  may not transmit the information on the estimation result of the “position of second apparatus  1802 ” to first apparatus  1201 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     An example of base station selection will be described. In the above description, in  FIG.  19   , first apparatus  1201  performs “PERFORM SENSING OF SECOND APPARATUS  1802  (SENSES SECOND APPARATUS) ( 1901 )” before “SELECT BASE STATION OF SENSING OF SECOND APPARATUS  1802  ( 1902 )” is performed. In the same manner, in  FIG.  20   , first apparatus  1201  performs “PEFORM SENSING OF SECOND APPARATUS  1802  (SENSES SECOND APPARATUS) ( 2001 )” before “SELECT BASE STATION FOR SENSING OF SECOND APPARATUS  1802  (SENSING SECOND APPARATUS) ( 2002 )” is performed. 
     In this way, estimation errors due to sensing may be reduced. Since the reason for the above has already been described, a description thereof will be omitted. 
     By performing as described above, it is possible to perform highly-accurate triangulation so that it is possible to obtain the effect that each apparatus can grasp the position of a target or the like. 
     Note that, in a case where first apparatus  1201  and the base station “grasp positions (or position information) on the map in advance” or in a case where first apparatus  1201  and the base station “can grasp positions (or position information) on the map by, for example, a position estimation system such as GPS”, each apparatus can grasp the position (or position information) of a target on map. 
     Further, in a case where first apparatus  1201  “transmits information on a request of second apparatus  1802 ” to the base station in  FIG.  19  or  20   , the communication may be radio communication or may be wired communication. 
     Note that, the signal transmitted by the second apparatus for sensing in the above description may also be referred to as a reference signal, a reference symbol, a pilot symbol, a pilot signal, or a preamble, although the designation is not limited to the above examples. 
     Examples of the characteristic points of the examples described above can be described as follows. 
     A first apparatus transmits a radio wave and receives the radio wave to measure a first distance or the like, a second apparatus transmits a radio wave and receives the radio wave to measure a second distance or the like, and the position of a target is measured by using the first distance or the like and the second distance or the like. For this reason, there are two transmission apparatuses and two reception apparatuses, and further the first apparatus and the second apparatus share information on the acquired first distance or the like and the acquired second distance or the like. 
     The second apparatus includes a reception apparatus for obtaining first distance information or the like obtained by the first apparatus. 
     The first apparatus includes a reception apparatus for obtaining second distance information or the like obtained by the second apparatus. 
     The first apparatus and the second apparatus estimate the position of the target by using the first distance information and the second distance information. 
     Note that, one or more apparatuses that differ from the second apparatus may estimate the distance to the target. 
     Further, the one or more apparatuses may also estimate the distance to the target, generate a plurality of pieces of distance information, and transmit these pieces of information to the second apparatus. The second apparatus may estimate the position of the target by generating one piece of first distance information from these pieces of information and using the first distance information and the second distance information. 
     Operation examples of sensing of each apparatus in  FIGS.  12  and  18    have been described above. Hereinafter, configuration examples of apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  in  FIGS.  12  and  18    will be described. 
       FIGS.  21 A and  21 B  illustrate configuration examples of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Signal generator  2102  inputs control signal  2100 , and generates and outputs a signal based on information of control signal  2100 . Specific examples thereof (a first example and a second example) will be described. 
     FIRST EXAMPLE 
     For example, in a case where control signal  2100  indicates that “a modulated signal for communication is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “a modulated signal for communication and a signal for sensing are transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101  and transmits a modulated signal as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N, and generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     In a case where control signal  2100  indicates that “a signal for sensing is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     In a case where a signal for sensing is transmitted from antenna port  2106 , the signal for sensing reflects off, for example, target  2110  and the reflected wave reaches antenna port  2112 . 
     Note that, in the case of  FIG.  18   , a signal for sensing transmitted by second apparatus  1802  reaches antenna port  2112 . For example, as in  FIG.  21 B , a signal for sensing transmitted by second apparatus  2120  (corresponding to second apparatus  1802 ) reaches antenna port  2112 . 
     For example, in a case where control signal  2100  indicates that “demodulation for communication is performed”, a modulated signal is received by using at least one antenna port of antenna port of antenna port  2111 _ 1  to antenna port  211 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116 . Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “demodulation for communication is performed and processing for sensing is performed”, a modulated signal is received by using at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116 , and inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In a case where control signal  2100  indicates that “processing for sensing is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports for communication, and antenna port  2106  is a transmission antenna port for sensing. Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports for communication, and antenna port  2112  is a reception antenna port for sensing. 
       FIG.  22    illustrates an exemplary state when apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  perform an operation for sensing. 
     As in (A) in  FIG.  22   , it is assumed that the section in which the apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , which have the configuration in  FIG.  21 A , transmit a signal for sensing is signal transmission section  2201  present between time v 1  and time v 2 . 
     The apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , which have the configuration in  FIG.  21 A , receive a signal in signal transmission section  2201  present between v 1  and time v 2  and perform signal processing to thereby perform sensing of a target. 
     Accordingly, the apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , which have the configuration in  FIG.  21   , perform a sensing-related reception operation in the section of reception-related operation  2202  present between time v 1  and time v 2  as in (B) in  FIG.  22   . 
     That is, when sensing is performed, there may be a time section in which the apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  perform both processing of an operation in a signal transmission section and processing of a signal reception-related operation. Thus, such an apparatus configuration that includes an antenna port for communication and an antenna port for sensing separately may be capable of improving the communication performance and sensing performance. 
     Note that, the antenna port may be a logical antenna (antenna group) formed of one or a plurality of physical antennas. That is, the antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna or the like formed of a plurality of antennas. 
     For example, it is not specified how many physical antennas the antenna port is formed of, and a terminal station may be specified as the smallest unit that can transmit a reference signal. 
     Further, the antenna port may be specified as a precoding vector, as a unit that multiplies weighting of a precoding matrix, or as the smallest unit. Note that, the above-described content related to the antenna port becomes the content related to the present specification in its entirety. 
     Further, at least one or more antennas may be shared by antenna ports. For example, there may be an antenna for transmission to be used in a plurality of antenna ports for transmission. Then, for example, there may be an antenna for reception to be used in a plurality of antenna ports for reception. Further, for example, there may be an antenna to be used in a plurality of antenna ports. Note that, the above-described content related to the antenna port becomes the content related to the present specification in its entirety. 
     SECOND EXAMPLE 
     A first mode and a second mode are defined as follows. 
     First mode (for example, a mode corresponding to the standard of the first release): 
     It is assumed that the first mode is a mode corresponding to the first communication scheme. 
     Second mode (for example, a mode corresponding to the standard of the second release): 
     It is assumed that the second mode is a mode corresponding to the second communication scheme and corresponding to sensing. 
     Hereinafter, three cases will be described. 
     Case 1: 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates “‘a modulated signal and/or a signal for sensing’ of the second mode are/is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2106 , and/or signal generator  2102  generates a signal for sensing, and transmits the signal as a radio wave from antenna port  2106 . 
     In a case where control signal  2100  indicates “a modulated signal of the first mode is transmitted and ‘a modulated signal and/or a signal for sensing’ of the second mode are/is transmitted”, the control signal generator  2102  performs the following two operations: 
     (1) Signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     (2) Signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2106 , and/or signal generator  2102  generates a signal for sensing, and transmits the signal as a radio wave from antenna port  2106 . 
     Further, in  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that “demodulation of the first mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “processing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target, and/or, signal processor  2115  receives a modulated signal by using antenna port  2112 , inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In a case where control signal  2100  indicates that “demodulation of the first mode is performed and processing of the second mode is performed”, the following two operations are performed. 
     (3) At least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. 
     (4) Signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target, and/or, signal processor  2115  receives a modulated signal by using antenna port  2112 , inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports of the first mode, and antenna port  2106  is a transmission antenna port of the second mode. Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports of the first mode, and antenna port  2112  is a reception antenna port of the second mode. 
     Case 2: 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _(N−1). Note that, it is assumed that N is an integer larger than or equal to 2. 
     In a case where control signal  2100  indicates that “at least ‘a modulated signal for communication’ of the second mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2105 _N. 
     In a case where control signal  2100  indicates that “at least ‘a signal for sensing’ of the second mode is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     Further, in  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “demodulation of the first mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _(M−1) is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 2. 
     In a case where control signal  2100  indicates that at least “demodulation of the second mode is performed”, a modulated signal is received by using antenna port  211 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In a case where control signal  2100  indicates that at least “processing for sensing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _(N−1) are transmission antenna ports of the first mode, antenna port  2105 _N is a transmission antenna port for communication of the second mode, and antenna port  2106  is a transmission antenna port for sensing of the second mode. 
     Further, antenna ports  2111 _ 1  to  2111 _(M−1) are reception antenna ports of the first mode, antenna port  2111 _M is a reception antenna port for communication of the second mode, and antenna port  2112  is a reception antenna port for sensing of the second mode. 
     Case 3: 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “at least ‘a modulated signal for communication’ of the second mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. 
     In a case where control signal  2100  indicates that “at least ‘a signal for sensing’ of the second mode is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     Further, in  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “demodulation of the first mode is performed”, at least one antenna port of antenna port  2131 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that at least “demodulation of the second mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In a case where control signal  2100  indicates that at least “processing for sensing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports of the first mode and transmission antenna ports for communication of the second mode, and antenna port  2106  is a transmission antenna port for sensing of the second mode. 
     Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports of the first mode and reception antenna ports for communication of the second mode, and antenna port  2112  is a reception antenna port for sensing of the second mode. 
     As described above, it is possible to obtain the effect that both high-quality communication and highly-accurate sensing can be achieved by selectively using an antenna port used at the time of communication and an antenna port used at the time of sensing. 
     As described above,  FIGS.  21 A and  21 B  have been indicated as the configurations of the apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and the use method of antenna ports has been described. As a matter of course, the configurations of the apparatuses of first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and the use method of antenna ports are applicable to embodiments other than the present embodiment. 
     Further, when there are two apparatuses (named apparatuses #A and #B) in the present embodiment and apparatus #A or #B transmits a radio wave and estimates a “distance between apparatuses #A and #B”, apparatus #A or #B may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of a target with higher accuracy. 
     In the same manner, when apparatus #A transmits a radio wave and estimates a “distance between apparatus #A and a target”, apparatus #A may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of the target with higher accuracy. 
     Further, when apparatus #A or #B transmits a radio wave and estimates a direction of arrival, apparatus #A or #B may estimate the “distance between apparatuses #A and #B” and utilize an estimated value of the above “distance between apparatuses #A and #B” to perform position estimation of a target with higher accuracy. 
     When apparatus #A transmits a radio wave and apparatus A estimates the direction of arrival of the radio wave obtained by the radio wave, for example, reflecting off a target, apparatus #A may estimate the “distance between apparatus #A and the target” and utilize the above “distance between apparatus #A and the target” to perform position estimation of the target with higher accuracy. 
     Note that, although  FIGS.  14 ,  15 A,  15 B,  15 C,  15 D,  15 E,  15 F, and  16    have been indicated as examples of the operation flows of the first apparatus and the base station, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. Further, although  FIGS.  19  and  20    have been indicated as examples of the operation flows of the first apparatus, the second apparatus, and the base station, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     Embodiment 3 
     In the present embodiment, an exemplary embodiment that differs from Embodiment 2 will be described. 
       FIG.  12    illustrates an example of the “sensing system” or “sensing and communication system” in the present embodiment. 
     In  FIG.  12   , base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  communicate with a terminal. 
     First apparatus  1201  is, for example, a terminal, and communicates with base station # 1  of  1202 _ 1  and/or base station # 2  of  1202 _ 2  and/or base station # 3  of  1202 _ 3 . 
     Target (object)  1203  is a target object whose position is estimated by sensing. 
     In the present embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 1  of  1202 _ 1 ”, “the triangulation described in Embodiment 1 with first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the “triangulation described in Embodiment 1 with first apparatus  1201  and base station # 3  of  1202 _ 3 ” will be described as an example. 
     It is assumed that first apparatus  1201  is an apparatus having a function of performing sensing described in Embodiment 1. Further, it is assumed that first apparatus  1201  has a communication function and communicates with, for example, base station # 1  of  1202 _ 1 , bases station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with one of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , base station # 3  of  1202 _ 3  to realize triangulation. However, it is supposed that there is/are a base station(s) that does/do not correspond to sensing due to factors such as the size of the base station(s) and the time of the installation. 
     Accordingly, it is assumed that base stations such as base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  transmit control information including information on sensing capability  1301  as illustrated in  FIG.  13   . 
     Note that, it is assumed that the control information including information on sensing capability  1301  is transmitted by a base station using a PBCH, a PDSCH or a PDCCH, for example. Note that, the channel through which the above control information is transmitted is not limited to the examples described above. 
     As illustrated in  FIG.  13   , it is assumed that information on sensing capability  1301  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and/or “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”: 
     This information is used to notify, for example, a terminal, a repeater, other base station(s) or the like of “whether a base station is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  1311 ”, it is assumed that a base station has a sensing function. Further, it is assumed that this base station has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether sensing is performable” when a base station receives a sensing request from the terminal (a request of the terminal for the base station to perform sensing). 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” may also be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another apparatus, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ”: 
     This information is used to notify, for example, a terminal or the like of information on “whether a base station accepts sensing from the terminal” when the base station receives a sensing request from the terminal (a request of the terminal for the base station to perform sensing). 
     Accordingly, there are modes in which, even when there is a sensing request from a terminal, a base station “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” may be “information on whether a sensing request from an apparatus other than a terminal, such as a repeater and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, a terminal, a repeater, another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with a base station” can be performed. 
     Note that, the apparatus that transmits information on sensing capability  1301  in  FIG.  13    has been described as a base station above, but is merely an example, and information on sensing capability  1301  may be transmitted by a communication apparatus such as a repeater, a terminal, and an access point. 
     Further, although the description “[ . . . ] SENSING REQUEST FROM TERMINAL” is used in “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS PERFORMABLE OR NOT PERFORMABLE  1312 ” and “INFORMATION ON WHETHER SENSING REQUEST FROM TERMINAL IS ACCEPTABLE OR NOT ACCEPTABLE  1313 ” which are transmitted by the apparatus that transmits information on sensing capability  1301  in  FIG.  13   , a sensing request may be not from a terminal, but may be from, for example, a communication apparatus such as a base station, a repeater, and an access point. Accordingly, implementation is also possible with  1312  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS PERFORMABLE OR NOT PERFORMABLE” and  1313  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS ACCEPTABLE OR NOT ACCEPTABLE”. 
     Next, operations of first apparatus  1201  and base station # 2  of  1202 _ 2  in  FIG.  12    will be described as an example. 
     First apparatus  1201  may be a terminal capable of communicating with a base station. Alternatively, first apparatus  1201  may be a base station. In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. Further, first apparatus  1201  in  FIG.  12    may be a repeater, and base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  may be repeaters. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  12   , direction-based triangulation whose examples are the third method and the fourth method will be described. Note that, the present embodiment is a variation of the third method and the fourth method. 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  1301  in  FIG.  13   , which is transmitted by base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 , and has acquired each status of response to sensing of base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 . 
     Hereinafter, it is assumed as an example that base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform sensing, and that in a case where there is a sensing request from the terminal, base station # 1  of  1202 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3  can all perform a sensing operation for the request for performing sensing. 
     In the present example, it is assumed as in  FIG.  23 A  that first apparatus  1201  transmits a signal for sensing, this signal comes into contact with target  1203 , and base station # 2  of  1202 _ 2  receives the signal for sensing, thereby performing position estimation, for example. 
     In  FIG.  23 B , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  2305 ” is performed. 
     Note that, since the method of obtaining information on the “distance between first apparatus  1201  and the base station” has already been described with reference to  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E, and  15 F , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and the base station may have acquired the “distance between first apparatus  1201  and the base station” in advance. 
     Further, first apparatus  1201  and the base station may acquire positions by a position estimation system such as GPS, for example. Then, the base station may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and the base station” from information on its own position and the information on the position of the base station. Then, first apparatus  1201  may transmit the information on its own position to the base station and the base station may determine the “distance between first apparatus  1201  and the base station” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     First apparatus  1201  in  FIGS.  12  and  23 A  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to base station # 2  of  1202 _ 2  ( 2301 ). 
     Base station # 2  of  1202 _ 2  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether base station # 2  of  1202 _ 2  accepts the request” ( 2311 ). Note that, in the example here, a description will be given on the assumption that base station # 2  of  1202 _ 2  “accepts the request”. 
     First apparatus  1201  receives information on the response to the request ( 2303 ). 
     First apparatus  1201  transmits a signal for sensing ( 2304 ). Note that, details of the transmission method of the signal for sensing to be transmitted by first apparatus  1201  will be described later. 
     Base station # 2  of  1202 _ 2  receives the signal for sensing transmitted by first apparatus  1201  and, for example, performs estimation of a (reception) direction of arrival ( 2312 ). 
     Base station # 2  of  1202 _ 2  transmits a (reception) direction-of-arrival estimation result and feedback information to first apparatus  1201  ( 2313 ). Note that, a specific operation example will be described later. 
     First apparatus  1201  performs, for example, triangulation by using the “(reception) direction-of-arrival estimation result and feedback information” transmitted by base station # 2  of  1202 _ 2 , the information on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, and the like, and obtains an estimation result of the “position of target (object)  1203 ” in  FIGS.  12  and  23 A  ( 2305 ). Note that, a specific operation example will be described later. 
     First apparatus  1201  transmits information on the estimation result of the “position of target (object)  1203 ” to base station # 2  of  1202 _ 2  ( 2306 ). 
     Note that, in a case where first apparatus  1201  and base station # 2  of  1202 _ 2  do not need to share the information on the estimation result of the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the estimation result of the “position of target  1203 ” to base station # 2  of  1202 _ 2 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Next, operation examples of  2304 ,  2312 ,  2313 , and  2305  in  FIG.  23 B  will be described. 
     In  FIG.  23 A , base station # 2  of  1202 _ 2  can estimate the angle formed by the “line segment formed by base station # 2  of  1202 _ 2  and first apparatus  1201 ” and the “line segment formed by base station # 2  of  1202 _ 2  and target  1203 ” in  FIG.  23 B  by receiving a signal for sensing transmitted by first apparatus  1201  to perform direction(-of-arrival) estimation. 
     As an example, triangulation can be realized when the angle formed by the “line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ” and the “line segment formed by first apparatus  1201  and target  1203 ” can be estimated. Hereinafter, a method of estimating the angle formed by the “line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ” and the “line segment formed by first apparatus  1201  and target  1203 ” will be described. 
       FIG.  24    illustrates an example of a configuration of first apparatus  1201  (and base station # 2  of  1202 _ 2 ) in  FIGS.  12  and  23 A . In  FIG.  24   , parts which operate in the same manner as in  FIG.  21    are denoted with the same numbers, and descriptions thereof will be omitted. Note that, a description will be given with an example in which first apparatus  1201  has the configuration in  FIG.  24   . 
     As illustrated in  FIG.  24   , it is assumed that first apparatus  1201  includes transmission antennas  2402 _ 1  to  2402 _L. Note that, it is assumed that L is an integer larger than or equal to 1. 
       FIG.  25    illustrates a configuration example related to transmission antenna  2402 _ i  (where i is an integer larger than or equal to 1 and smaller than or equal to L). 
     As illustrated in  FIG.  25   , it is assumed that transmission antenna  2402 _ i  is formed of four antennas as in, for example, antennas  2504 _ 1 ,  2504 _ 2 ,  2504 _ 3  and  2405 _ 4 . Although an example in which transmission antenna  2402 _ i  is formed of four antennas has been indicated here, the number of antennas is not limited to this example as long as transmission antenna  2402 _ i  is formed of two or more antennas. 
     Processor  2502  inputs signal  2501  (corresponding to signal  2401 _ i  in  FIG.  24   ) and control signal  2500  (corresponding to control signal  2100  in  FIG.  24   ). In a case where control signal  2500  indicates that “a signal for sensing is transmitted”, processor  2502  performs transmission directivity control processing on signal  2501  and outputs signal  2503 _ i  after the transmission directivity control processing. Note that, i is an integer larger than or equal to 1 and smaller than or equal to 4. Further, signal  2503 _ i  after the transmission directivity control processing is outputted as a radio wave from antenna  2504 _ i.    
     A specific configuration example of a signal for sensing to be transmitted by first apparatus  1201  will be described. 
       FIG.  26    illustrates an example of frame of signal for sensing  2601  to be transmitted by first apparatus  1201 . 
     It is assumed that frame of signal for sensing  2601  is formed of, for example, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING FIRST ANTENNA  2611 _ 1 ”, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING SECOND ANTENNA  2611 _ 2 ”, . . . , “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING L-TH ANTENNA  2611 _L”. 
     “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING FIRST ANTENNA  2611 _ 1 ” is a signal to be transmitted from transmission antenna  2402 _ 1  of first apparatus  1201 . 
     “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING L-TH ANTENNA  2611 _L” is a signal to transmitted from transmission antenna  2402 _L of first apparatus  1201 . 
     That is, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i ” is a signal to be transmitted from transmission antenna  2402 _ i  of first apparatus  1201 . Note that, i is an integer larger than or equal to 1 and smaller than or equal to L. 
       FIG.  27    illustrates an example of a configuration of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i ” in  FIG.  26   . 
     As illustrated in  FIG.  27   , it is assumed that SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i  is formed of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ”, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ”, . . . , “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ”. Note that, it is assumed that z is “an integer larger than or equal to 1” or “an integer larger than or equal to 2”. 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the first parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ”. “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the second parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ”. “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the z-th parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ”. “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
       FIG.  28    illustrates a configuration example of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” in  FIG.  27   . Note that, j is an integer larger than or equal to 1 and smaller than or equal to z. 
     As illustrated in  FIG.  28   , it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” includes, for example, “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ”. Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” includes, albeit not illustrated in  FIG.  28   , a signal for performing sensing. 
     It is assumed that “ANTENNA INFORMATION  2801 ” includes information that allows the use of “the i-th antenna” to be identified (for example, information on antenna ID (identification) or the like). Accordingly, base station # 2  of  1202 _ 2  that has been able to receive “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” can obtain information on an antenna used when first apparatus  1201  transmits a signal for sensing. 
     Further, it is assumed that “PARAMETER INFORMATION  2802 ” includes information that allows a parameter used for transmission directivity control to be identified (for example, information on parameter ID (identification) or the like). Accordingly, base station # 2  of  1202 _ 2  that has been able to receive “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” can obtain information on a parameter for antenna transmission directivity control used when first apparatus  1201  transmits a signal for sensing. 
     Note that, first apparatus  1201  and base station # 2  of  1202 _ 2  may transmit reference signal  2899  (for sensing) in  FIG.  28    together with the information described above. Note that, reference signal  2899  is transmitted by using the i-th antenna and the j-th parameter. 
     In  2304  and  2312  in  FIG.  23 B , base station # 2  of  1202 _ 2  can receive, of frame for sensing  2601  transmitted by first apparatus  1201 , one signal of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ”. Then base station # 2  of  1202 _ 2  sets, as feedback information, “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ” of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” which base station # 2  of  1202 _ 2  has been able to receive, and transmits this feedback information to first apparatus  1201 . 
     Base station # 2  of  1202 _ 2  obtains this feedback information, and can know the transmission directivity, that is, the direction, of the signal, which base station # 2  of  1202 _ 2  has been able to receive, that is, can estimate the angle formed by the “line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ” and the “line segment formed by first apparatus  1201  and target (object)  1203 ” in  FIG.  23 A . 
     Accordingly, base station # 2  of  1202 _ 2  has obtained “the angle formed by the ‘line segment formed by base station # 2  of  1202 _ 2  and first apparatus  1201 ’ and the ‘line segment formed by base station # 2  of  1202 _ 2  and target  1203 ’”, “the angle formed by the ‘line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ’ and the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’”, and the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” in  FIG.  23 A , and therefore can estimate the position of target (object)  1203 . 
     Note that, although “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ” have been described separately in  FIG.  28   , information may be generated without making a distinction therebetween. 
     For example, an ID is given with ID ♭ 1  in the case of “the first antenna and the first parameter”, ID ♭ 2  in the case of “the first antenna and the second parameter”, ID ♭ 3  in the case of “the second antenna and the first parameter”, ID ♭ 4  in the case of “the second antenna and the second parameter”, . . . . 
     Then, for example, first apparatus  1201  transmits a “signal for sensing to be transmitted by using the first antenna and the first parameter” such that the “signal for sensing to be transmitted by using the first antenna and the first parameter” includes information on ID ♭ 1 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the first antenna and the second parameter” such that the “signal for sensing to be transmitted by using the first antenna and the second parameter” includes information on ID ♭ 2 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the second antenna and the first parameter” such that the “signal for sensing to be transmitted by using the second antenna and the first parameter” includes information on ID ♭ 3 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the second antenna and the second parameter” such that the “signal for sensing to be transmitted by using the second antenna and the second parameter” includes information on ID ♭ 4 . 
     Then, base station # 2  of  1202 _ 2  sets, as feedback information, ID information (for example, ID ♭ 1 , ID ♭ 2 , . . . ) of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING ANTENNA AND j-TH PARAMETER  2701 _ 1 ” which base station # 2  of  1202 _ 2  has been able to receive, and transmits this feedback information to first apparatus  1201 . 
     First apparatus  1201  obtains this feedback information, and can know the transmission directivity, that is, the direction, of the signal, which base station # 2  of  1202 _ 2  has been able to receive, that is, can estimate the angle formed by the “line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ” and the “line segment formed by first apparatus  1201  and target (object)  1203 ”. 
     Accordingly, base station # 2  of  1202 _ 2  has obtained “the angle formed by the ‘line segment formed by base station # 2  of  1202 _ 2  and first apparatus  1201 ’ and the ‘line segment formed by base station # 2  of  1202 _ 2  and target  1203 ’”, “the angle formed by the ‘line segment formed by first apparatus  1201  and base station # 2  of  1202 _ 2 ’ and the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’”, and the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ” in  FIG.  23 A , and therefore can estimate the position of target (object)  1203 . 
     Another example of operations in  2304 ,  2312 ,  2313 , and  2305  in  FIG.  23 B  will be described. 
     Base station # 2  of  1202 _ 2  can estimate the angle formed by the “line segment formed by base station # 2  of  1202 _ 2  and first apparatus  1201 ” and the “line segment formed by base station # 2  of  1202 _ 2  and target  1203 ” in  FIG.  23 A  by receiving a signal for sensing transmitted by first apparatus  1201  to perform direction(-of-arrival) estimation. 
     Further, triangulation can be performed by estimating the sum of the “line segment formed by first apparatus  1201  and target (object)  1203 ” and the “line segment formed by target (object)  1203  and base station # 2  of  1202 _ 2 ” in  FIG.  23 A . 
     Accordingly, first apparatus  1201  transmits a signal for sensing as in  2304  of  FIG.  23 B , base station # 2  of  1202 _ 2  receives this signal for sensing ( 2312 ) and estimates the sum of the “line segment formed by first apparatus  1201  and target (object)  1203 ” and the “line segment formed by target (object)  1203  and base station # 2  of  1202 _ 2 ”, and base station # 2  of  1202 _ 2  transmits information on this estimation value to first apparatus  1201 . Further, base station # 2  of  1202 _ 2  transmits a reception direction-of-arrival estimation result to first apparatus  1201 . Note that, since the transmission method of the signal for sensing to be transmitted by first apparatus  1201  has been described with reference to  FIGS.  24 ,  25 ,  26 ,  27 , and  28   , a description thereof will be omitted. 
     Then, first apparatus  1201  can estimate the position of target (object)  1203  based on the “distance between first apparatus  1201  and base station # 2  of  1202 _ 2 ”, “the sum of the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’ and the ‘line segment formed by target (object)  1203  and base station # 2  of  1202 _ 2 ’”, and “the angle formed by the ‘line segment formed by base station # 2  of  1202 _ 2  and first apparatus  1201 ’ and the ‘line segment formed by base station # 2  of  1202 _ 2  and target  1203 ’”. 
     By performing as described above, it is possible to realize triangulation. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Note that, when there are two apparatuses (named apparatuses #A and #B) in the present embodiment and apparatus #A or #B transmits a radio wave and estimates a “distance between apparatuses #A and #B”, apparatus #A or #B may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of a target with higher accuracy. 
     In the same manner, when apparatus #A transmits a radio wave and estimates a “distance between apparatus #A and a target”, apparatus #A may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of the target with higher accuracy. 
     Further, when apparatus #A or #B transmits a radio wave and estimates a direction of arrival, apparatus #A or #B may estimate the “distance between apparatuses #A and #B” and utilize an estimated value of the above “distance between apparatuses #A and #B” to perform position estimation of a target with higher accuracy. 
     When apparatus #A transmits a radio wave and apparatus A estimates the direction of arrival of the radio wave obtained by the radio wave, for example, reflecting off a target, apparatus #A may estimate the “distance between apparatus #A and the target” and utilize the above “distance between apparatus #A and the target” to perform position estimation of the target with higher accuracy. 
     Note that, although  FIGS.  15 A,  15 B,  15 C,  15 D,  15 E,  15 F, and  23 B  have been indicated as examples of the operation flows of the first apparatus and the base station, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     Further, in the same manner as in Embodiment 2, first apparatus  1201  may change the base station which is requested to perform sensing in order to increase the accuracy of position estimation of a target in the operation flow of  FIG.  23 B . 
     For example, in a case where base station # 2  of  1202 _ 2  performs “TRANSMIT DIRECTION-OF-ARRIVAL ESTIMATION RESULT AND FEEDBACK INFORMATION  2313 ”, first apparatus  1201  receives the result and the feedback information, and determines, as described in Embodiment 2, that position estimation of a target may not be obtained with high accuracy, first apparatus  1201  may change the base station which is requested to perform sensing. 
     Further, in a case where first apparatus  1201  estimates the position of a target ( 2305 ) and determines that the position estimation of the target has not been obtained with high accuracy, first apparatus  1201  may request another base station to perform sensing. 
     Embodiment 4 
     In the present embodiment, an exemplary embodiment that differs from Embodiment 2 will be described. 
       FIG.  29    illustrates an example of the “sensing system” or “sensing and communication system” in the present embodiment. In  FIG.  29   , parts which operate in the same manner as in  FIG.  12    are denoted with the same numbers. 
     In  FIG.  29   , third apparatus  2903  communicates with first apparatus  1201  by using a third frequency (band). 
     Fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q perform communication by using a fourth frequency (band). Note that, it is assumed that Q is an integer larger than or equal to 1. 
     Note that, there is a method in which the third frequency (band) is frequency range (FR) 1 and/or FR2 and the fourth frequency (band) is a frequency of 52.6 GHz or higher, for example. It is assumed, however, that FR1 is a “frequency from 450 MHz to smaller than or equal to 6 GHz” and FR2 is a “frequency from 24.25 GHz to 52.6 GHz”. Further, as another example, the fourth frequency (band) may be a frequency higher than the third frequency (band). As yet another example, the third frequency (band) may be FR1 and the fourth frequency (band) may be FR2. 
     Further, it is assumed that third apparatus  2903  communicates with fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q. The communication this time may be radio communication or wired communication. 
     Communication may be possible between two apparatuses of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. Note that, the communication this time may be radio communication or wired communication. 
     Target (object)  1203  is a target object whose position is estimated by sensing. 
     In the present embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ”, “the triangulation described in Embodiment 1 with first apparatus  1201  and fourth_ 2  apparatus of  2904 _ 2 ”, the “triangulation described in Embodiment 1 with first apparatus  1201  and fourth_Q apparatus of  2904 _Q” will be described as an example. 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with one of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” to realize triangulation. However, it is supposed that there is fourth_i apparatus of  2904 _ i  that does not correspond to sensing due to factors such as the size of fourth_i apparatus of  2904 _ i  and the time of the installation. Note that, it is assumed that i is an integer larger than or equal to 1 and smaller than or equal to Q. 
     Accordingly, it is assumed that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” transmit control information including information on sensing capability  3001  as illustrated in  FIG.  30   . For example, it is assumed that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” transmit the control information including information on sensing capability  3001  by using, for example, a PBCH, a PDSCH or a PDCCH. 
     The channel through which the above control information is transmitted is not limited to the examples described above. Further, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  to first apparatus  1201  or third apparatus  2903 . 
       FIG.  30    is a diagram provided for describing an example of information on sensing capability. As illustrated in  FIG.  30   , it is assumed that information on sensing capability  3001  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and/or “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”: 
     This information is used to notify, for example, first apparatus  1201 , a repeater, another fourth_x apparatus, third apparatus  2903 , or the like of “whether fourth_i apparatus of  2904 _ i  is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, it is assumed that fourth_i apparatus of  2904 _ i  has a sensing function. Further, it is assumed that this fourth_i apparatus of  2904 _ i  has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”: 
     This information is used to notify, for example, first apparatus  1201 , third apparatus  2903 , or the like of information on “whether sensing is performable” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201  (a request of the terminal for first apparatus  1201  to perform sensing). 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” may also be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”: 
     This information is used to notify, for example, first apparatus  1201  or the like of information on “whether fourth_i apparatus of  2904 _ i  accepts sensing from first apparatus  1201 ” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201  (a request of the terminal for first apparatus  1201  to perform sensing). 
     Accordingly, there are modes in which, even when there is a sensing request from first apparatus  1201 , fourth_i apparatus of  2904 _ i  “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” may be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, first apparatus  1201 , a repeater, third apparatus  2903 , another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with fourth_i apparatus of  2904 _ i ” can be performed. 
     Note that, the apparatus that transmits information on sensing capability  3001  in  FIG.  30    has been described as fourth_i apparatus of  2904 _ i  above, but is merely an example, and information on sensing capability  3001  may be transmitted by a communication apparatus such as a repeater, a terminal, an access point, and third apparatus  2903 . 
     Further, although the description “[ . . . ] SENSING REQUEST FROM FIRST APPARATUS  1201 ” is used in “INFORMAIION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” which are transmitted by the apparatus that transmits information on sensing capability  3001  in  FIG.  30   , a sensing request may be not from first apparatus  1201 , but may be from, for example, a communication apparatus such as a base station, a repeater, an access point, and third apparatus  2903 . Accordingly, implementation is also possible with  3012  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS PERFORMABLE OR NOT PERFORMABLE” and  3013  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS ACCEPTABLE OR NOT ACCEPTABLE”. 
     Next, sensing by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29    will be described. 
     First apparatus  1201  may be a terminal capable of communicating with third apparatus  2903  and fourth_i apparatus of  2904 _ i.  Alternatively, first apparatus  1201  may be a base station (or an access point, a repeater, or the like). In addition, first apparatus  1201  may also be fourth_x apparatus of  2904 _ x  (where x is a natural number, for example). Further, third apparatus  2903  may be a base station or may be a terminal, a repeater, an access point, or the like. Fourth_i apparatus of  2904 _ i  may be a base station or may be a terminal, a repeater, an access point, or the like. 
     In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station, an access point or a repeater. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  29   , distance-based triangulation whose examples are the first method and the second method, and direction-based triangulation whose examples are the third method and the fourth method will be described separately. 
     Case of Distance-Based Triangulation: 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     First apparatus  1201  obtains information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and acquires each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  knows each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
       FIG.  31    illustrates a procedure example for sensing in the system example in  FIG.  29   . In  FIG.  31   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  3104 ” is performed. 
     Further, in  FIG.  31   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3102 ” is performed. 
     Before describing  FIG.  31   , a method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” will be described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H . 
     In  FIG.  32 A , fourth_i apparatus of  2904 _ i  first transmits a signal ( 3201 ). Then, first apparatus  1201  receives this signal to thereby estimate the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” ( 3202 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  32 B , first apparatus  1201  first transmits a signal to fourth_i apparatus of  2904 _ i  ( 3211 ). Then, first apparatus  1201  receives this signal and estimates the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” ( 3212 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  32 C , first apparatus  1201  first transmits a signal to fourth_i apparatus of  2904 _ i  ( 3221 ). Then, fourth_i apparatus of  2904 _ i  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3222 ). Fourth_i apparatus of  2904 _ i  transmits a modulated signal including information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” to first apparatus  1201  ( 3223 ). First apparatus  1201  receives the modulated signal including the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” and obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3224 ). 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     First apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     As another method, in  FIG.  32 D , first apparatus  1201  first transmits a signal to fourth_i apparatus of  2904 _ i  ( 3231 ). Then, fourth_i apparatus of  2904 _ i  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3232 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  32 E , fourth_i apparatus of  2904 _ i  first transmits a signal to first apparatus  1201  ( 3241 ). Then, fourth_i apparatus of  2904 _ i  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3242 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. 
     As another method, in  FIG.  32 F , fourth_i apparatus of  2904 _ i  first transmits a signal to first apparatus  1201  ( 3251 ). Then, first apparatus  1201  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3252 ). First apparatus  1201  transmits a modulated signal including information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” to fourth_i apparatus of  2904 _ i  ( 3253 ). Fourth_i apparatus of  2904 _ i  receives the modulated signal including the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” and obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3254 ). 
     As another method, in  FIG.  32 G , first apparatus  1201  first transmits a signal to fourth_i apparatus of  2904 _ i  ( 3261 ). Then, fourth_i apparatus of  2904 _ i  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3262 ). Fourth_i apparatus of  2904 _ i  transmits a modulated signal including information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” to third apparatus  2903  ( 3263 ). Third apparatus  2903  obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3264 ). Third apparatus  2903  transmits a modulated signal to first apparatus  1201  including the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3265 ), and first apparatus  1201  obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3266 ). 
     As another method, in  FIG.  32 H , fourth_i apparatus of  2904 _ i  first transmits a signal to first apparatus  1201  ( 3271 ). Then, fourth_i apparatus of  2904 _ i  receives this signal and estimates the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3272 ). Note that, since the detailed method of distance estimation has been described in Embodiment 1, a description thereof will be omitted. Fourth_i apparatus of  2904 _ i  transmits a modulated signal including information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” to third apparatus  2903  ( 3273 ). Third apparatus  2903  obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3274 ). Third apparatus  2903  transmits a modulated signal including the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” to first apparatus  1201  ( 3275 ), and first apparatus  1201  obtains the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3276 ). 
     Examples of the method of obtaining information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” have been described above with reference to  FIGS.  32 A to  32 H . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  31   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  29    to obtain an estimated value of a “distance between first apparatus  1201  and target  1203 ” ( 3101 ). 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “distance between first apparatus  1201  and target  1203 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3102 ). 
     Note that, it is assumed in the example of  FIG.  31    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3102 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of the distance to target  1203 ” to third apparatus  2903  ( 3103 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the distance to target  1203 ” and transmits the information on the request for “estimation of the distance to target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3121 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the distance to target  1203 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3111 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3122 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits a signal for performing sensing and obtains an estimated value of a “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” ( 3112 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” to third apparatus  2903  ( 3113 ). 
     Third apparatus  2903  receives the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and transmits the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” to first apparatus  1201  ( 3123 ). 
     First apparatus  1201  obtains the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “distance between first apparatus  1201  and target  1203 ”, and the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, and estimates the position of target  1203 , for example ( 3104 ). 
     First apparatus  1201  transmits information on the “position of target  1203 ” to third apparatus  2903  ( 3105 ). 
     Third apparatus  2903  receives the information on the “position of target  1203 ” and transmits the information on the “position of target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3124 ). 
     Note that, in a case where first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  do not need to share the information on the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the “position of target  1203 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, a procedure example for sensing different from that in  FIG.  31    will be described with reference to  FIG.  33   .  FIG.  33    illustrates another procedure example for sensing. In  FIG.  33   , parts which operate in the same manner as in  FIG.  31    are denoted with the same numbers. In  FIG.  33   , a difference from  FIG.  31    will be described. In  FIG.  33   , the difference from  FIG.  31    is as follows. 
     The difference is that “in  FIG.  31   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) ( 3102 )”, whereas “in  FIG.  33   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) for first apparatus  1201  ( 3399 )”. 
     As in  FIG.  33   , first apparatus  1201  transmits information on a request for “estimation of a distance to target  1203 ” to third apparatus  2903  ( 3103 ). Note that, at this time, first apparatus  1201  may transmit information on the “distance to target  1203 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the distance to target  1203 ”, based on the information on the “distance to target  1203 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3399 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3399 ” may not be performed. 
     Since the operations after that in  3399  in  FIG.  33    have already been described with reference to  FIG.  31   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, another example when the distance-based triangulation whose examples are the first method and the second method is used will be described with reference to  FIG.  34   . 
       FIG.  34    illustrates another procedure example for sensing. It is assumed that first apparatus  1201  has obtained information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  can acquire each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
     Further, in  FIG.  34   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  3413 ” is performed. Then, in  FIG.  34   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3402 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” this time has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  34   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  29    to obtain an estimated value of a “distance between first apparatus  1201  and target  1203 ” ( 3401 ). 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “distance between first apparatus  1201  and target  1203 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3402 ). 
     Note that, it is assumed in the example of  FIG.  34    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3402 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of the distance to target  1203 ” to third apparatus  2903 . Further, first apparatus  1201  transmits information on the estimated value of the “distance between first apparatus  1201  and target  1203 ” to third apparatus  2903  ( 3403 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the distance to target  1203 ” and the information on the estimated value of the “distance between first apparatus  1201  and target  1203 ”, and transmits the information on the request for “estimation of the distance to target  1203 ” and the information on the estimated value of the “distance between first apparatus  1201  and target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3421 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the distance to target  1203 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3411 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3422 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits a signal for performing sensing and obtains an estimated value of a “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” ( 3412 ). 
     Fourth_ 1  apparatus of  2904 _ 1  performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “distance between first apparatus  1201  and target  1203 ”, and the “distance between fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, and estimates the position of target  1203 , for example ( 3413 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “position of target  1203 ” to third apparatus  2903  ( 3414 ). 
     Third apparatus  2903  receives the information on the “position of target  1203 ”, and transmits the information on the “position of target  1203 ” to first apparatus  1201  ( 3423 ). 
     Note that, in a case where fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201  do not need to share the information on the “position of target  1203 ”, fourth_ 1  apparatus of  2904 _ 1  may not transmit the information on the “position of target  1203 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  34    will be described with reference to  FIG.  35   .  FIG.  35    illustrates another procedure example for sensing. In  FIG.  35   , parts which operate in the same manner as in  FIG.  34    are denoted with the same numbers. In  FIG.  35   , a difference from  FIG.  34    will be described. In  FIG.  35   , the difference from  FIG.  34    is as follows. 
     The difference is that “in  FIG.  34   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) ( 3402 )”, whereas “in  FIG.  35   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) for first apparatus  1201  ( 3599 )”. 
     As in  FIG.  35   , first apparatus  1201  transmits information on a request for “estimation of a distance to target  1203 ” to third apparatus  2903  ( 3403 ). Note that, at this time, first apparatus  1201  may transmit information on the “distance to target  1203 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the distance to target  1203 ”, based on the information on the “distance to target  1203 ”, the status of response to sensing of fourth_i apparatus of  2904  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3599 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3599 ” may not be performed. 
     Since the operations after that in  3599  in  FIG.  35    have already been described with reference to  FIG.  34   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  can acquire each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
     Further, in  FIG.  31   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  3104 ” is performed. Then, in  FIG.  31   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  1402 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  31   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  29    to obtain an estimated value of a “direction (of arrival) of first apparatus  1201  and target  1203 ” ( 3101 ). 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a direction (of arrival) with target  1203 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3102 ). 
     Note that, it is assumed in the example of  FIG.  31    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (THAT SENSES TARGET)  3102 ” may not be performed. 
     Then, first apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to third apparatus  2903  ( 3103 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ” and transmits the information on the request for “estimation of the direction (of arrival) with target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3121 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3111 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3122 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits a signal for performing sensing and obtains an estimated value of a “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” ( 3112 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” to third apparatus  2903  ( 3113 ). 
     Third apparatus  2903  receives the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and transmits the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” to first apparatus  1201  ( 3123 ). 
     First apparatus  1201  obtains the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, and estimates the position of target  1203 , for example ( 3104 ). 
     First apparatus  1201  transmits information on the “position of target  1203 ” to third apparatus  2903  ( 3105 ). 
     Third apparatus  2903  receives the information on the “position of target  1203 ” and transmits the information on the “position of target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3124 ). 
     Note that, in a case where first apparatus  1201  and fourth_i apparatus of  2904 _ i  do not need to share the information on the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the “position of target  1203 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  31    will be described with reference to  FIG.  33   . In  FIG.  33   , parts which operate in the same manner as in  FIG.  31    are denoted with the same numbers. In  FIG.  33   , a difference from  FIG  31    will be described. In  FIG.  33   , the difference from  FIG.  31    is as follows. 
     The difference is that “in  FIG.  31   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) ( 3102 )”, whereas “in  FIG.  33   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (sensing the target) for first apparatus  1201  ( 3399 )”. 
     As in  FIG.  33   , first apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to third apparatus  2903  ( 3103 ). Note that, at this time, first apparatus  1201  may transmit information on the “direction (of arrival) with target  1203 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the direction (of arrival) with target  1203 ”, based on the information on the “estimation of the direction (of arrival) with target  1203 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3399 ). Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . 
     Since the operations after that in  3399  in  FIG.  33    have already been described with reference to  FIG.  31   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, another example when the direction-based triangulation whose examples are the third method and the fourth method is used will be described with reference to  FIG.  34   . 
     It is assumed that first apparatus  1201  has obtained information on sensing capabil 4   3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  can acquire each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
     Further, in  FIG.  34   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  3413 ” is performed. 
     Then, in  FIG.  34   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (SENSING TARGET)  3402 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  34   , first apparatus  1201  first performs sensing of target (object)  1203  in  FIG.  29    to obtain an estimated value of a “direction (of arrival) of first apparatus  1201  and target  1203 ” ( 3401 ). 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a direction (of arrival) with target  1203 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3402 ). 
     Note that, it is assumed in the example of  FIG.  34    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (THAT SENSES TARGET)  3402 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to third apparatus  2903 . Further, first apparatus  1201  transmits information on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ” to third apparatus  2903  ( 3403 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ” and the information on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and transmits the information on the request for “estimation of the direction (of arrival) with target  1203 ” and the information on the estimated value of the “direction (of arrival) of first apparatus  1201  and target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3421 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3411 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3422 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits a signal for performing sensing, and obtains an estimated value of a “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” ( 3412 ). 
     Fourth_ 1  apparatus of  2904 _ 1  performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, and estimates the position of target  1203 , for example ( 3413 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “position of target  1203 ” to third apparatus  2903  ( 3414 ). 
     Third apparatus  2903  receives the information on the “position of target  1203 ”, and transmits the information on the “position of target  1203 ” to first apparatus  1201  ( 3423 ). 
     Note that, in a case where fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201  do not need to share the information on the “position of target  1203 ”, fourth_ 1  apparatus of  2904 _ 1  may not transmit the information on the “position of target  1203 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  34    will be described with reference to  FIG.  35   . Note that, in  FIG.  35   , parts which operate in the same manner as in  FIG.  34    are denoted with the same numbers. In  FIG.  35   , a difference from  FIG.  34    will be described. In  FIG.  35   , the difference from  FIG.  34    is as follows. 
     The difference is that “in  FIG.  34   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (that senses the target) ( 3402 )”, whereas “in  FIG.  35   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of target  1203  (that senses the target) for first apparatus  1201  ( 3599 )”. 
     As in  FIG.  35   , first apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to third apparatus  2903  ( 3403 ). Note that, at this time, first apparatus  1201  may transmit information on the “direction (of arrival) with target  1203 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the direction (of arrival) with target  1203 ”, based on the information on the “estimation of the direction (of arrival) with target  1203 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3599 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (THAT SENSES TARGET)  3599 ” may not be performed. 
     Since the operations after that in  3599  in  FIG.  35    have already been described with reference to  FIG.  34   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     An example of base station selection will be described. In the above description, in  FIG.  31   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 3101 )” before “SELECT FOURTH_i APPARATUS OF  2904 _ i  OF SENSING OF TARGET (THAT SENSES TARGET) ( 3102 )” is performed. 
     In the same manner, in  FIG.  33   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 3101 )” before third apparatus  2903  performs “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSEING OF TARGET (SENSING TARGET) ( 3399 )”. 
     Further, in  FIG.  34   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 3401 )” before “SELECT FOURTH_i APPARATUS OF  2904 _ i  OF SENSING OF TARGET (THAT SENSES TARGET) ( 3402 )” is performed. 
     Then, in  FIG.  35   , first apparatus  1201  performs “PERFORM SENSING OF TARGET (SENSE TARGET) ( 3401 )” before third apparatus  2903  perform “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (THAT SENSES TARGET) ( 3599 )”. 
     At this time, in  FIG.  29   , fourth_i apparatus of  2904 _ i  can be selected based on the shape of the triangle formed by “first apparatus  1201 , target  1203 , and fourth_i apparatus of  2904 _ i ”. Since this point has been described in detail in Embodiment 2, a description thereof will be omitted. 
     In this way, estimation errors due to sensing may be reduced. 
     By performing as described above, it is possible to perform highly-accurate triangulation so that it is possible to obtain the effect that each apparatus can grasp the position of a target or the like. Note that, in a case where first apparatus  1201  and the base station “grasp positions (or position information) on the map in advance” or in a case where first apparatus  1201  and the base station “can grasp positions (or position information) on the map by, for example, a position estimation system such as GPS”, each apparatus can grasp the position (or position information) of a target on the map. 
     Note that, signals transmitted by, for example, base stations, terminals, and repeaters for sensing a target (object) in the above description may be referred to as reference signals, reference symbols, pilot symbols, pilot signals, or preamble, although the designations are not limited to the above examples. 
     Further, each operation has been described above with reference to  FIGS.  29  to  35    or the like. In addition,  FIG.  29    has been dealt with as an example of the “sensing system” or “sensing and communication system”. In  FIG.  29   , a description has been made with an example in which first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing by using the fourth frequency, but one of first apparatus  1201  and fourth_i apparatus of  2904 _ i  may perform sensing by using any other frequency. 
     Next, an exemplary embodiment that differs from that described above will be described. An exemplary embodiment in a case where a target transmits a radio wave will be described. 
       FIG.  36    illustrates an example of the “sensing system” or “sensing and communication system” exemplified here. In  FIG.  36   , parts which operate in the same manner as in  FIGS.  12 ,  18   , and/or  29  are denoted with the same numbers. 
     In  FIG.  36   , second apparatus  1802  is a target object whose position is estimated by sensing. 
     In this exemplary embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and fourth_i apparatus of  2904 _ i ” will be described as an example. 
     It is assumed that first apparatus  1201  is an apparatus having a function of performing sensing described in Embodiment 1. Note that, it is assumed that first apparatus  1201  performs sensing by using the fourth frequency (band). 
     It is assumed that first apparatus  1201  has a communication function and communicates with, for example, third apparatus  2903  by using the third frequency (band). 
     Note that, first apparatus  1201  may communicate with fourth_i apparatus of  2904 _ i  by using the fourth frequency (band). 
     It is assumed that second apparatus  1802  is an apparatus capable of transmitting a radio wave of the fourth frequency (band). 
     It is assumed that fourth_i apparatus of  2904 _ i  is an apparatus having a function of performing sensing described in Embodiment 1. Note that, it is assumed that fourth_i apparatus of  2904 _ i  performs sensing by using the fourth frequency (band). 
     Further, fourth_i apparatus of  2904 _ i  may have a communication function and may be capable of performing communication by using the fourth frequency (band). 
     It is assumed that third apparatus  2903  communicates with fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q. The communication this time may be radio communication or wired communication. 
     Communication may be possible between two apparatuses of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. Note that, the communication this time may be radio communication or wired communication. 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with fourth_i apparatus of  2904 _ i  to realize triangulation. However, it is supposed that there is fourth_x apparatus of  2904 _ x  that does correspond to sensing due to factors such as the size of fourth_i apparatus of  2904 _ i  and the time of the installation. 
     Accordingly, it is assumed that fourth_i apparatus of  2904 _ i  transmits control information including information on sensing capability  3001  as illustrated in  FIG.  30   . For example, it is assumed that a base station transmits the control information including information on sensing capability  3001  by using a PBCH, a PDSCH or a PDCCH. Note that, the channel through which the above control information is transmitted is not limited to the examples described above. 
     As illustrated in  FIG.  30   , it is assumed that information on sensing capability  3001  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and/or “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”: 
     This information is used to notify, for example, first apparatus  1201 , a repeater, another fourth_x apparatus, third apparatus  2903 , or the like of “whether fourth_i apparatus of  2904 _ i  is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, it is assumed that fourth_i apparatus of  2904 _ i  has a sensing function. Further, it is assumed that this fourth_i apparatus of  2904 _ i  has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”: 
     This information is used to notify, for example, first apparatus  1201 , third apparatus  2903 , or the like of information on “whether sensing is performable” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201 . 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” may also be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”: 
     This information is used to notify, for example, first apparatus  1201  or the like of information on “whether fourth_i apparatus of  2904 _ i  accepts sensing from first apparatus  1201 ” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201 . 
     Accordingly, there are modes in which, even when there is a sensing request from first apparatus  1201 , fourth_i apparatus of  2904 _ i  “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” may be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, first apparatus  1201 , a repeater, third apparatus  2903 , another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with fourth_i apparatus of  2904 _ i ” can be performed. 
     Note that, the apparatus that transmits information on sensing capability  3001  in  FIG.  30    has been described as fourth_i apparatus of  2904 _ i  above, but is merely an example, and information on sensing capability  3001  may be transmitted by a communication apparatus such as a repeater, a terminal, an access point, and third apparatus  2903 . 
     Further, although the description “[ . . . ] SENSING REQUEST FROM FIRST APPARATUS  1201 ” is used in “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” which are transmitted by the apparatus that transmits information on sensing capability  3001  in  FIG.  30   , a sensing request may be not from first apparatus  1201 , but may be from, for example, a communication apparatus such as a base station, a repeater, an access point, and third apparatus  2903 . Accordingly, implementation is also possible with  3012  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS PERFORMABLE OR NOT PERFORMABLE” and  3013  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS ACCEPTABLE OR NOT ACCEPTABLE”. 
     Next, sensing by first apparatus  1201 , second apparatus  1802 , and fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36    will be described. 
     First apparatus  1201  may be a terminal capable of communicating with third apparatus  2903  and fourth_i apparatus of  2904 _ i.  Alternatively, first apparatus  1201  may be a base station (or an access point, a repeater, or the like). In addition, first apparatus  1201  may also be fourth_x apparatus of  2904 _ x  (where x is a natural number, for example). Further, third apparatus  2903  may be a base station or may be a terminal, a repeater, an access point, or the like. Fourth_i apparatus of  2904 _ i  may be a base station or may be a terminal, a repeater, an access point, or the like. 
     In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station, an access point or a repeater. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  12   , distance-based triangulation whose examples are the first method and the second method, and direction-based triangulation whose examples are the third method and the fourth method will be described separately. 
     Case of Distance-Based Triangulation: 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     First apparatus  1201  obtains information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and knows each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  knows each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201  “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
       FIG.  37    illustrates a procedure example for sensing in the system example in  FIG.  36   . In  FIG.  37   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF SECOND APPARATUS  3704 ” is performed. In  FIG.  37   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS (THAT SENSES SECOND APPARATUS)  3702 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     First apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  37   , second apparatus  1802  transmits a signal (for sensing) ( 3731 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between first apparatus  1201  and second apparatus  1802 ” ( 3701 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “distance between first apparatus  1201  and second apparatus  1802 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3702 ). 
     Note that, it is assumed in the example of  FIG.  37    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3702 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to third apparatus  2903  ( 3703 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the distance to second apparatus  1802 ”, and transmits the information on the request for “estimation of the distance to second apparatus  1802 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3721 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the distance to second apparatus  1802 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3711 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3722 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 3732 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” ( 3712 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” to third apparatus  2903  ( 3713 ). 
     Third apparatus  2903  receives the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and transmits the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” to first apparatus  1201  ( 3723 ). 
     First apparatus  1201  obtains the information on the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “distance between first apparatus  1201  and second apparatus  1802 ”, and the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 3704 ). 
     First apparatus  1201  transmits information on the “position of second apparatus  1802 ” to third apparatus  2903  ( 3705 ). 
     Third apparatus  2903  receives the information on the “position of second apparatus  1802 ”, and transmits the information on the “position of second apparatus  1802 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3724 ). 
     Note that, in a case where first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  do not need to share the information on the “position of second apparatus  1802 ”, first apparatus  1201  may not transmit the information on the “position of second apparatus  1802 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, a procedure example for sensing different from that in  FIG.  37    will be described with reference to  FIG.  38   . 
       FIG.  38    illustrates another procedure example for sensing. In  FIG.  38   , parts which operate in the same manner as in  FIG.  37    are denoted with the same numbers. In  FIG.  38   , a difference from  FIG.  37    will be described. In  FIG.  38   , the difference from  FIG.  37    is as follows. 
     The difference is that “in  FIG.  37   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) ( 3102 )”, whereas “in  FIG.  38   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) for first apparatus  1201  ( 3399 )”. 
     As in  FIG.  38   , first apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to third apparatus  2903  ( 3703 ). Note that, at this time, first apparatus  1201  may transmit information on the “distance to second apparatus  1802 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the distance to second apparatus  1802 ”, based on the information on the “distance to second apparatus  1802 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3899 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3899 ” may not be performed. 
     Since the operations after that in  3899  in  FIG.  38    have already been described with reference to  FIG.  37   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, another example when the distance-based triangulation whose examples are the first method and the second method is used will be described with reference to  FIG.  39   . 
       FIG.  39    illustrates another procedure example for sensing. It is assumed that first apparatus  1201  has obtained information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  can acquire each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for sensing. 
     Further, in  FIG.  39   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF SECOND APPARATUS  1802   3913 ” is performed. 
     Then, in  FIG.  39   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3902 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the distance-based triangulation whose examples are the first method and the second method described in Embodiment 1 is used will be described. 
     In  FIG.  39   , second apparatus  1802  transmits a signal (for sensing) ( 3931 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between first apparatus  1201  and second apparatus  1802 ” ( 3901 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to second apparatus  1802 , based on the estimated value of the “distance between first apparatus  1201  and second apparatus  1802 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3902 ). 
     Note that, it is assumed in the example of  FIG.  39    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36    as fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3902 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to third apparatus  2903  ( 3903 ). 
     First apparatus  1201  transmits information on the “distance between first apparatus  1201  and second apparatus  1802 ” to third apparatus  2903  ( 3903 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the distance to second apparatus  1802 ” and the information on the “distance between first apparatus  1201  and second apparatus  1802 ”, and transmits these pieces of information to fourth_ 1  apparatus of  2904 _ 1  ( 3921 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the distance to second apparatus  1802 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3911 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3922 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 3932 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” ( 3912 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     Fourth_ 1  apparatus of  2904 _ 1  performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “distance between first apparatus  1201  and second apparatus  1802 ”, and the “distance between fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 3913 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “position of second apparatus  1802 ” to third apparatus  2903  ( 3914 ). 
     Third apparatus  2903  receives the information on the “position of second apparatus  1802 ”, and transmits the information on the “position of second apparatus  1802 ” to first apparatus  1201  ( 3923 ). 
     Note that, in a case where fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201  do not need to share the information on the “position of second apparatus  1802 ”, fourth_ 1  apparatus of  2904 _ 1  may not transmit the information on the “position of second apparatus  1802 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  39    will be described with reference to  FIG.  40   .  FIG.  40    illustrates another procedure example for sensing. In  FIG.  40   , parts which operate in the same manner as in  FIG.  39    are denoted with the same numbers. In  FIG.  40   , a difference from  FIG.  39    will be described. In  FIG.  40   , the difference from  FIG.  39    is as follows. 
     The difference is that “in  FIG.  39   , first apparatus  1201  “selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) ( 3902 )”, whereas “in  FIG.  40   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) for first apparatus  1201  ( 4099 )”. 
     As in  FIG.  40   , first apparatus  1201  transmits information on a request for “estimation of a distance to second apparatus  1802 ” to third apparatus  2903  ( 3903 ). Note that, at this time, first apparatus  1201  may transmit information on the “distance to second apparatus  1802 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the distance to second apparatus  1802 ”, based on the information on the “distance to second apparatus  1802 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 4099 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the distance to second apparatus  1802  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  4099 ” may not be performed. 
     Since the operations after that in  4099  in  FIG.  40    have already been described with reference to  FIG.  39   . a description thereof will be omitted. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  can acquire each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for sensing. 
     Further, in  FIG.  37   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF SECOND APPARATUS  3704 ” is performed. Then, in  FIG.  37   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3702 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  37   , second apparatus  1802  transmits a signal (for sensing) ( 3731 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” ( 3701 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to target  1203 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3702 ). 
     Note that, it is assumed in the example of  FIG.  37    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36    as fourth_i apparatus of  2904 _ i  which is requested to perform estimation of a “direction (of arrival) with second apparatus  1802 ”. However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the “direction (of arrival) with second apparatus  1802 ” is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3702 ” may not be performed. 
     Then, first apparatus  1201  transmits information on a request for “estimation of the direction (of arrival) with second apparatus  1802 ” to third apparatus  2903  ( 3703 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ”, and transmits the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3721 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3711 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3722 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 3732 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” ( 3712 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” to third apparatus  2903  ( 3713 ). 
     Third apparatus  2903  receives the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and transmits the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” to first apparatus  1201  ( 3723 ). 
     First apparatus  1201  obtains the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, and the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 3704 ). 
     First apparatus  1201  transmits information on the “position of second apparatus  1802 ” to third apparatus  2903  ( 3705 ). 
     Third apparatus  2903  receives the information on the “position of second apparatus  1802 ”, and transmits the information on the “position of second apparatus  1802 ” to fourth_ 1  apparatus of  2904 _ 1  ( 3724 ). 
     Note that, in a case where first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  do not need to share the information on the “position of second apparatus  1802 ”, first apparatus  1201  may not transmit the information on the “position of second apparatus  1802 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the direction(-of-arrival)-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  37    will be described with reference to  FIG.  38   . Note that, in  FIG.  38   , parts which operate in the same manner as in  FIG.  37    are denoted with the same numbers, in  FIG.  38   , a difference from  FIG.  37    will be described. In  FIG.  38   , the difference from  FIG.  37    is as follows. 
     The difference is that “in  FIG.  37   , first apparatus  1201  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) ( 3102 )”, whereas “in  FIG.  38   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) for first apparatus  1201  ( 3399 )”. 
     As in  FIG.  38   , first apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with second apparatus  1802 ” to third apparatus  2903  ( 3703 ). Note that, at this time, first apparatus  1201  may transmit information on the “direction (of arrival) with second apparatus  1802 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the “direction (of arrival) with second apparatus  1802 ”, based on the information on the “direction (of arrival) with second apparatus  1802 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 3899 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the “direction (of arrival) with second apparatus  1802 ” is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3899 ” may not be performed. 
     Since the operations after that in  3899  in  FIG.  38    have already been described with reference to  FIG.  37   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the direction-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, another example when the direction-based triangulation whose examples are the third method and the fourth method is used will be described with reference to  FIG.  39   . 
     It is assumed that first apparatus  1201  has obtained information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and has acquired each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  knows each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for sensing. 
     Further, in  FIG.  39   , it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF SECOND APPARATUS  1802   3913 ” is performed. 
     Then, in  FIG.  39   , it is assumed that first apparatus  1201  has obtained information on a “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” (where i is an integer larger than or equal to 1 and smaller than or equal to Q) before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3902 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     In  FIG.  39   , second apparatus  1802  transmits a signal (for sensing) ( 3931 ). 
     First apparatus  1201  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” ( 3901 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     First apparatus  1201  selects fourth_i apparatus of  2904 _ i,  which is requested to perform estimation of a distance to second apparatus  1802 , based on the estimated value of the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” and the information on the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” ( 3902 ). 
     Note that, it is assumed in the example of  FIG.  39    that first apparatus  1201  has selected fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36    as fourth_i apparatus of  2904 _ i  which is requested to perform estimation of a “direction (of arrival) with second apparatus  1802 ”. However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the “direction (of arrival) with second apparatus  1802 ” is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  3902 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with second apparatus  1802 ” to third apparatus  2903  ( 3903 ). 
     First apparatus  1201  transmits information on the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ” to third apparatus  2903  ( 3903 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ” and the information on the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, and transmits these pieces of information to fourth_ 1  apparatus of  2904 _ 1  ( 3921 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the direction (of arrival) with second apparatus  1802 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 3911 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 3922 ). 
     Second apparatus  1802  transmits a signal (for sensing) ( 3932 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the signal transmitted by second apparatus  1802 , performs processing for sensing, and obtains an estimated value of a “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ” ( 3912 ). Note that, since the processing for sensing has already been described in the other embodiment, a description thereof will be omitted. 
     Fourth_ 1  apparatus of  2904 _ 1  performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “direction (of arrival) of first apparatus  1201  and second apparatus  1802 ”, and the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and second apparatus  1802 ”, and estimates the position of second apparatus  1802 , for example ( 3913 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “position of second apparatus  1802 ” to third apparatus  2903  ( 3914 ). 
     Third apparatus  2903  receives the information on the “position of second apparatus  1802 ”, and transmits the information on the “position of second apparatus  1802 ” to first apparatus  1201  ( 3923 ). 
     Note that, in a case where fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201  do not need to share the information on the “position of second apparatus  1802 ”, fourth_ 1  apparatus of  2904 _ 1  may not transmit the information on the “position of second apparatus  1802 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the direction-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Next, an exemplary embodiment that differs from that in  FIG.  39    will be described with reference to  FIG.  40   . Note that, in  FIG.  40   , parts which operate in the same manner as in  FIG.  39    are denoted with the same numbers. In  FIG.  40   , a difference from  FIG.  39    will be described. In  FIG.  40   , the difference from  FIG.  39    is as follows. 
     The difference is that “in  FIG.  39   , first apparatus  1201  “selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) ( 3902 )”, whereas “in  FIG.  40   , third apparatus  2903  selects fourth_i apparatus of  2904 _ i  for sensing of second apparatus  1802  (that senses the second apparatus) for first apparatus  1201  ( 4099 )”. 
     As in  FIG.  40   , first apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with second apparatus  1802 ” to third apparatus  2903  ( 3903 ). Note that, at this time, first apparatus  1201  may transmit information on the “direction (of arrival) with second apparatus  1802 ” to third apparatus  2903 . 
     Then, third apparatus  2903  selects, for first apparatus  1201 , fourth_i apparatus of  2904 _ i,  which performs “estimation of the “direction (of arrival) with second apparatus  1802 ”, based on the information on the “direction(of arrival) with second apparatus  1802 ”, the status of response to sensing of fourth_i apparatus of  2904 _ i  (information on sensing capability  3001  in  FIG.  30   ), and the like ( 4099 ). 
     Note that, it is assumed here that the apparatus which performs sensing is fourth_ 1  apparatus of  2904 _ 1 . However, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the “direction (of arrival) with second apparatus  1802 ” is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS)  4099 ” may not be performed. 
     Since the operations after that in  4099  in  FIG.  40    have already been described with reference to  FIG.  39   , a description thereof will be omitted. 
     By performing as described above, it is possible to realize the direction-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of second apparatus  1802 . 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     An example of base station selection will be described. In the above description, in  FIG.  37   , first apparatus  1201  performs “PERFORM SENSING OF SECOND APPARATUS  1802  ( 3701 )” before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS) ( 3702 )” is performed. 
     In the same manner, in  FIG.  38   , first apparatus  1201  performs “PERFORM SENSING OF SECOND APPARATUS  1802  (SENSE SECOND APPARATUS) ( 3701 )” before third apparatus  2903  performs “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS) ( 3899 )”. 
     Further, in  FIG.  39   , first apparatus  1201  performs “PERFORM SENSING OF SECOND APPARATUS  1802  (SENSE SECOND APPARATUS) ( 3901 )” before “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAT SENSES SECOND APPARATUS) ( 3902 )” is performed. 
     Then, in  FIG.  40   , first apparatus  1201  performs “PERFORM SENSING OF SECOND APPARATUS  1802  (SENSE SECOND APPARATUS) ( 3901 )” before third apparatus  2903  performs “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF SECOND APPARATUS  1802  (THAI SENSES SECOND APPARATUS) ( 4099 )”. 
     At this time, in  FIG.  36   , fourth_i apparatus of  2904 _ i  can be selected based on the shape of the triangle formed by “first apparatus  1201 , second apparatus  1802 , and fourth_i apparatus of  2904 _ i ”. Since this point has been described in detail in Embodiment 2, a description thereof will be omitted. 
     In this way, estimation errors due to sensing may be reduced. 
     By performing as described above, it is possible to perform highly-accurate triangulation so that it is possible to obtain the effect that each apparatus can grasp the position of second apparatus  1802  or the like. Note that, in a case where first apparatus  1201  and the base station “grasp positions (or position information) on the map in advance” or in a case where first apparatus  1201  and the base station “can grasp positions (or position information) on the map by, for example, a position estimation system such as GPS”, each apparatus can grasp the position (or position information) of a target on the map. 
     Note that, signals transmitted by, for example, base stations, terminals, and repeaters for sensing second apparatus  1802  in the above description may be referred to as reference signals, reference symbols, pilot symbols, pilot signals, or preamble, although the designations are not limited to the above examples. 
     Further, each operation has been described above with reference to  FIGS.  36  to  40    or the like. In addition,  FIG.  36    has been dealt with as an example of the “sensing system” or “sensing and communication system”. In  FIG.  36   , a description has been made with an example in which first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing by using the fourth frequency, but one of first apparatus  1201  and fourth_i apparatus of  2904 _ i  may perform sensing by using any other frequency. 
     Examples of the characteristic points of the examples described above can be described as follows. 
     A first apparatus transmits a radio wave and receives the radio wave to measure a first distance or the like, a second apparatus transmits a radio wave and receives the radio wave to measure a second distance or the like, and the position of a target is measured by using the first distance or the like and the second distance or the like. For this reason, there are two transmission apparatuses and two reception apparatuses, and further the first apparatus and the second apparatus share information on the acquired first distance or the like and the acquired second distance or the like via a third apparatus. 
     The second apparatus includes a reception apparatus for obtaining first distance information or the like obtained by the first apparatus. 
     The first apparatus includes a reception apparatus for obtaining second distance information or the like obtained by the second apparatus. 
     The first apparatus and the second apparatus estimate the position of the target by using the first distance information and the second distance information. 
     Note that, one or more apparatus that differ from the second apparatus may estimate the distance to the target. 
     Further, the one or more apparatuses may also estimate the distance to the target, generate a plurality of pieces of distance information, and transmit these pieces of information to the second apparatus, and the second apparatus may estimate the position of the target by generating one piece of first distance information from these pieces of information and using the first distance information and the second distance information. 
     Frame configuration examples of each apparatus when sensing is performed in the “sensing system” or “sensing and communication system” in  FIG.  29    will be described. 
       FIG.  41    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . It is assumed that the horizontal axis indicates time. 
     As described above, fourth_ 1  apparatus of  2904 _ 1  transmits frame for sensing  4101  for sensing target  1203 . 
     Fourth_ 1  apparatus of  2904 _ 1  may transmit a frame for communication in addition to frame for sensing  4101  (fourth_ 1  apparatus of  2904 _ 1  may not transmit a frame for communication). Frame # 1  for communication of  4102 _ 1 , frame # 2  for communication of  4102 _ 2 , . . . in  FIG.  41    are frames for communication that are transmitted by fourth_ 1  apparatus of  2904 _ 1 . At this time, the destination of “frame # 1  for communication of  4102 _ 1 , frame # 2  for communication of  4102 _ 2 , . . . ” may be first apparatus  1201  or another communication apparatus. 
     Note that, when the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in  FIG.  41   . Accordingly, a frame for communication may be transmitted temporally ahead of a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     (A) in  FIG.  42    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . (B) in  FIG.  42    illustrates exemplary transmission frames of first apparatus  1201  in  FIG.  29   . Note that, it is assumed that the horizontal axis in (A) and (B) in  FIG.  42    indicates time. Further, both (A) and (B) in  FIG.  42    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  42   , fourth_ 1  apparatus of  2904 _ 1  transmits frame  4201  for sensing, frame # 1  for communication of  4202 _ 1 , frame # 2  for communication of  4202 _ 2 , . . . . 
     That is, fourth_ 1  apparatus of  2904 _ 1  may transmit a frame for communication in addition to frame  4201  for sensing (fourth_ 1  apparatus of  2904 _ 1  may not transmit a frame for communication). Frame # 1  for communication of  4202 _ 1 , frame # 2  for communication of  4202 _ 2 , . . . in (A) in  FIG.  42    are frames for communication that are transmitted by fourth_ 1  apparatus of  2904 _ 1 . At this time, the destination of “frame # 1  for communication of  42021 , frame # 2  for communication of  4202 _ 2 , . . . ” may be first apparatus  1201  or another communication apparatus. 
     Note that, when the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (A) in  FIG.  42   . Accordingly, a frame for communication may be transmitted temporally ahead of a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     Further, (A) and (B) in  FIG.  42    are exemplary frames to which, for example, time division multiplexing (TDM) or time division duplex (TDD) is performed so as to reduce interference in each frame. 
     As in (B) in  FIG.  42   , frames are mapped such that TDM or TDD is performed, and first apparatus  1201  transmits frame ♭ 1  for communication of  4212 _ 1 , frame ♭ 2  for communication of  4212 _ 2 , . . . . At this time, frame ♭ 1  for communication of  4212 _ 1 , frame ♭ 2  for communication of  4212 _ 2 , . . . may be frames for fourth_ 1  apparatus of  2904 _ 1  or may be frames for fourth_i apparatus of  2904 _ .    
     Note that, when the region for first apparatus  1201  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block (although no frame for sensing is described in (B) in  FIG.  42   ). 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (B) in  FIG.  42   . Accordingly, first apparatus  1201  may transmit a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     (A) in  FIG.  43    illustrates an exemplary transmission frame of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . (B) in  FIG.  43    illustrates exemplary transmission frames of fourth_ 2  apparatus of  2904 _ 2  in  FIG.  29   . Note that, it is assumed that the horizontal axis in (A) and (B) in  FIG.  43    indicates time. Further, both (A) and (B) in  FIG.  43    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  43   , fourth_ 1  apparatus of  2904 _ 1  transmits frame for sensing  4301 . 
     Then, as illustrated in (B) in  FIG.  43   , fourth_ 2  apparatus of  2904 _ 2  transmits frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . . 
     At this time, frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . may be frames for first apparatus  1201  or may be frames for another communication apparatus. 
     When frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . are frames for first apparatus  1201 , first apparatus  1201  performs communication by utilizing the fourth frequency (hand) even during a sensing-related operation. 
     Note that, when each of the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal and the region for fourth_ 2  apparatus of  2904 _ 2  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     (A) in  FIG.  44    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . (B) in  FIG.  44    illustrates exemplary transmission frames of fourth_ 2  apparatus of  2904 _ 2  in  FIG.  29   . Note that, it is assumed that the horizontal axis in (A) and (B) in  FIG.  44    indicates time. Further, both (A) and (B)  FIG.  44    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  44   , fourth_ 1  apparatus of  2904 _ 1  transmits frame for sensing  4301 , frame # 1  for communication of  4402 _ 1 , frame # 2  for communication of  4402 _ 2 , . . . . 
     At this time, frame # 1  for communication of  4402 _ 1 , frame # 2  for communication of  4402 _ 2 , . . . may be frames for first apparatus  1201  or may be frames for another communication apparatus. 
     Then, as illustrated in (B) in  FIG.  44   , fourth_ 2  apparatus of  2904 _ 2  transmits frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . . 
     At this time, flame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . may be frames for first apparatus  1201  or may be frames for another communication apparatus. 
     When “frame # 1  for communication of  4402 _ 1 , frame # 2  for communication of  4402 _ 2 , . . . are frames for first apparatus  1201 ” and “frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . are frames for first apparatus  1201 ”, first apparatus  1201  performs communication by utilizing the fourth frequency (band) even during a sensing-related operation, and further first apparatus  1201  communicates with two fourth_i apparatuses. 
     Note that, when each of the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal and the region for fourth_ 2  apparatus of  2904 _ 2  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     (A) in  FIG.  45    illustrates an exemplary transmission frame of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . (B) in  FIG.  45    illustrates exemplary transmission frames of fourth_ 2  apparatus of  2904 _ 2  in  FIG.  29   . (C) in  FIG.  45    illustrates exemplary transmission frames of first apparatus  1201  in  FIG.  29   . Note that, it is assumed that the horizontal axis in (A), (B), and (C) in  FIG.  45    indicates time. Further, all of (A), (B), and (C) in  FIG.  45    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  45   , fourth_ 1  apparatus of  2904 _ 1  transmits frame for sensing  4501 . 
     Further, (A), (B), and (C) in  FIG.  45    are exemplary frames to which, for example, TDM or TDD is performed so as to reduce interference in each frame. 
     As illustrated in (B) in  FIG.  45   , frames are mapped such that TDM or TDD is performed, and fourth_ 2  apparatus of  2904 _ 2  transmits frame  1 * for communication of  4522 _ 1 , frame  2 * for communication of  4522 _ 2 , . . . . 
     At this time, frame  1 * for communication of  4522 _ 1 , frame  2 * for communication of  4522 _ 2 , . . . may be frames for first apparatus  1201  or may be frames for another communication apparatus. 
     Then, as illustrated in (C) in  FIG.  45   , frames are mapped such that TDM or TDD is performed, and first apparatus  1201  transmits frame ♭ 1  for communication of  4512 _ 1 , frame ♭ 2  for communication of  4512 _ 2 , frame ♭ 3  for communication of  4512 _ 3  for communication, . . . . 
     Frame ♭ 1  for communication of  4512 _ 1 , frame ♭ 2  for communication of  4512 _ 2 , frame ♭ 3  for communication of  4512 _ 3  for communication, . . . may be frames for fourth_ 1  apparatus of  2904 _ 1  or may be frames for fourth_i apparatus of  2904 _ i.    
     Note that, when each of the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal and the region for fourth_ 2  apparatus of  2904 _ 2  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block (although no frame for sensing is described in (A) in  FIG.  45   ). 
     Further, when the region for first apparatus  1201  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     When “frame  1 * for communication of  4322 _ 1 , frame  2 * for communication of  4322 _ 2 , . . . are frames for first apparatus  1201 ”, first apparatus  1201  performs communication by utilizing the fourth frequency (band) even during a sensing-related operation. Further, fourth_ 1  apparatus of  2904 _ 1  performs a sensing-related operation. 
     (A) in  FIG.  46    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  29   . (B) in  FIG.  46    illustrates exemplary transmission frames of fourth_ 2  apparatus of  2904 _ 2  in  FIG.  29   . (C) in  FIG.  46    illustrates exemplary transmission frames of first apparatus  1201  in  FIG.  29   . Note that, it is assumed that the horizontal axis in (A), (B), and (C) in  FIG.  46    indicates time. Further, all of (A), (B), and (C) in  FIG.  46    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  46   , fourth_ 1  apparatus of  2904 _ 1  transmits frame for sensing  4601 , frame # 1  for communication of  4602 _ 1 , . . . . 
     Further, (A), (B), and (C) in  FIG.  46    are exemplary frames to which, for example, TDM or TDD is performed so as to reduce interference in each frame. 
     As illustrated in (B) in  FIG.  46   , frames are mapped such that TDM or TDD is performed, and fourth_ 2  apparatus of  2904 _ 2  transmits frame  1 * for communication of  4522 _ 1 , frame  2 * for communication of  4522 _ 2 , . . . . 
     At this time, frame  1 * for communication of  4522 _ 1 , frame  2 * for communication of  4522 _ 2 , . . . may be frames for first apparatus  1201  or may be frames for another communication apparatus. 
     Then, as illustrated in (C) in  FIG.  46   , frames are mapped such that TDM or TDD is performed, and first apparatus  1201  transmits frame ♭ 1  for communication of  4512 _ 1 , frame ♭ 2  for communication of  4512 _ 2 , frame ♭ 3  for communication of  4512 _ 3  for communication, . . . . 
     Frame ♭ 1  for communication of  4512 _ 1 , frame ♭ 2  for communication of  4512 _ 2 , frame ♭ 3  for communication of  4512 _ 3  for communication, . . . may be frames for fourth_ 1  apparatus of  2904 _ 1  or may be frames for fourth_i apparatus of  2904 _ i.    
     Note that, when each of the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal and the region for fourth_ 2  apparatus of  2904 _ 2  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, when the region for first apparatus  1201  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     When “frame # 1  for communication of  4602 _ 1 , . . . are frames for first apparatus  1201 ” and “frame  1 * for communication of  4522 _ 1 , frame  2 * for communication of  4522 _ 2 , . . . are frames for first apparatus  1201 ”, first apparatus  1201  performs communication by utilizing the fourth frequency (band) even during a sensing-related operation, and further first apparatus  1201  communicates with two fourth_i apparatuses. In addition, fourth_ 1  apparatus of  2904 _ 1  performs a sensing-related operation. 
     As described above, first apparatus  1201  performs sensing and communication by using the fourth frequency (band), and fourth_i apparatus of  2904 _ i  also performs sensing and communication by using the fourth frequency (band) so that it is possible to obtain the effect of improving the frequency utilization efficiency of the fourth frequency (band). 
     Note that, although  FIG.  41   , (A) and (B) in  FIG.  42   , (A) and (B) in  FIG.  43   , (A) and (B) in  FIG.  44   , (A), (B), and (C) in  FIG.  45   , and (A), (B), and (C) in  FIG.  46    have been indicated as examples of transmission statuses, the transmission method is not limited to these examples. 
     Further, although the apparatus that transmits a frame for communication is fourth_ 2  apparatus of  2904 _ 2  in (A) and (B) in  FIG.  43   , fourth_i apparatus of  2904 _ i  other than the above apparatus described above may transmit a frame for communication. 
     Although the apparatuses that transmit a frame for communication are fourth_ 1  apparatus of  2904 _ 1  and fourth  2  apparatus of  2904 _ 2  in (A) and (B) in  FIG.  44   , fourth_i apparatus of  2904 _ i  other than the above apparatuses may also transmit a frame for communication. 
     Although the apparatus that transmits a frame for communication is fourth_ 2  apparatus of  2904 _ 2  in (A), (B), and (C) in  FIG.  45   , fourth_i apparatus of  2904 _ i  other than the above apparatus may also transmit a frame for communication. 
     Although the apparatuses that transmit a frame for communication are fourth_ 1  apparatus of  2904 _ 1  and fourth_ 2  apparatus of  2904 _ 2  in (A), (B), and (C) in  FIG.  46   , fourth_i apparatus of  2904 _ i  other than the above apparatuses may also transmit a frame for communication. 
     Next, frame configuration examples of each apparatus when sensing is performed in the “sensing system” or “sensing and communication system” in  FIG.  36    will be described. 
       FIG.  47    illustrates exemplary transmission frames of second apparatus  1802  in  FIG.  36   . It is assumed that the horizontal axis indicates time. 
     As described above, second apparatus  1802  transmits frame for sensing  4701  for first apparatus  1201  or fourth_ 1  apparatus of  2904 _ 1  to perform sensing. 
     Further, second apparatus  1802  may transmit a frame for communication in addition to frame for sensing  4701  (second apparatus  1802  may not transmit a frame for communication). 
     Frame # 1  for communication of  4702 _ 1 , frame # 2  for communication of  4702 _ 2 , . . . in  FIG.  47    are frames for communication that are transmitted by second apparatus  1802 . At this time, the destination of “frame # 1  for communication of  4702 _ 1 , frame # 2  for communication of  4702 _ 2 , . . . ” may be first apparatus  1201 , fourth apparatus of  2904 _ i,  or another communication apparatus. 
     Note that, when the region for second apparatus  1802  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in  FIG.  47   . Accordingly, a frame for communication may be transmitted temporally ahead of a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     (A) in  FIG.  48    illustrates exemplary transmission frames of second apparatus  1802  in  FIG.  36   . (B) in  FIG.  48    illustrates exemplary transmission frames of first apparatus  1201  in  FIG.  36   . Note that, it is assumed that the horizontal axis in (A) and (B) in  FIG.  48    indicates time. Further, both (A) and (B) in  FIG.  48    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  48   , second apparatus  1802  transmits frame for sensing  4801 , frame # 1  for communication of  4802 _ 1 , frame # 2  for communication of  4802 _ 2 , . . . . At this time, frame for sensing  4801  is, for example, a frame for first apparatus  1201  or fourth_ 1  apparatus of  2904 _ 1  to perform sensing. 
     That is, second apparatus  1802  may transmit a frame for communication in addition to frame for sensing  4801  (second apparatus  1802  may not transmit a frame for communication). Frame # 1  for communication  4802 _ 1 , frame # 2  for communication in  4802 _ 2 , . . . in (A) in  FIG.  48    are frames for communication that are transmitted by second apparatus  1802 . At this time, the destination of “frame # 1  for communication  4802 _ 1 , frame # 2  for communication in  4802 _ 2 , . . . ” may be first apparatus  1201 , fourth apparatus of  2904 _ i,  or another communication apparatus. 
     Note that, when the region for second apparatus  1802  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (A) in  FIG.  48   . Accordingly, a frame for communication may be transmitted temporally ahead of a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     Further, (A) and (B) in  FIG.  48    are exemplary frames to which for example, TDM or TDD is performed so as to reduce interference in each frame. 
     As in (B) in  FIG.  48   , frames are mapped such that TDM or TDD is performed, and first apparatus  1201  transmits frame ♭ 1  for communication of  4812 _ 1 , frame ♭ 2  for communication of  4812 _ 2 , . . . . At this time, frame ♭ 1  for communication of  4812 _ 1 , frame ♭ 2  for communication of  4812 _ 2 , . . . may be frames for fourth_ 1  apparatus of  2904 _ 1 , may be frames for fourth_i apparatus of  2904 _ i,  or may be frames for second apparatus  1802 . 
     Note that, when the region for first apparatus  1201  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (B) in  FIG.  48   . Accordingly, first apparatus  1201  may transmit a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     (A) in  FIG.  49    illustrates exemplary transmission frames of second apparatus  1802  in  FIG.  36   . (B) in  FIG.  49    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36   . Note that, it is assumed that the horizontal axis in (A) and (B) in  FIG.  49    indicates time. Further, both (A) and (B) in  FIG.  49    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  49   , second apparatus  1802  transmits frame for sensing  4901 , frame # 1  for communication of  4902 _ 1 , frame # 2  for communication of  4902 _ 2 , . . . . At this time, frame for sensing  4901  is, for example, a frame for first apparatus  1201  or fourth_ 1  apparatus of  2904 _ 1  to perform sensing. 
     That is, second apparatus  1802  may transmit a frame for communication in addition to frame for sensing  4901  (second apparatus  1802  may not transmit a frame for communication). Frame # 1  for communication  4902 _ 1 , frame # 2  for communication in  4902 _ 2 , . . . in (A) in  FIG.  49    are frames for communication that are transmitted by second apparatus  1802 . At this time, the destination of “frame # 1  for communication  4902 _ 1 , frame # 2  for communication in  4902 _ 2 , . . . ” may be first apparatus  1201 , fourth apparatus of  2904 _ i,  or another communication apparatus. 
     Note that, when the region for second apparatus  1802  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (A) in  FIG.  49   . Accordingly, a frame for communication may be transmitted temporally ahead of a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     Further, (A) and (B) in  FIG.  49    are exemplary frames to which, for example, TDM or TDD is performed so as to reduce interference in each frame. 
     As in (B) in  FIG.  49   , frames are mapped such that TDM or TDD is performed, and fourth_ 1  apparatus of  2904 _ 1  transmits frame  1 * for communication of  4912 _ 1 , frame  2 * for communication of  4912 _ 2 , . . . . At this time, frame  1 * for communication of  4912 _ 1 , frame  2 * for communication of  4912 _ 2 , . . . may be frames for first apparatus  1201 , may be frames for fourth_i apparatus of  2904 _ i,  or may be frames for second apparatus  1802 . 
     Note that, when the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, the method of allocating a frame for sensing and a frame for communication in the time axis is not limited to the example in (B) in  FIG.  49   . Accordingly, fourth_ 1  apparatus of  2904 _ 1  may transmit a frame for sensing. Further, in a case where a symbol and a frame can be mapped in the frequency-axis direction, a frame for sensing and a frame for communication may be transmitted on the same time. 
     (A) in  FIG.  50    illustrates exemplary transmission frames of second apparatus  1802  in  FIG.  36   . (B) in  FIG.  50    illustrates exemplary transmission frames of fourth_ 1  apparatus of  2904 _ 1  in  FIG.  36   . (C) in  FIG.  50    illustrates exemplary transmission frames of fourth_ 2  apparatus of  2904 _ 2  in  FIG.  36   . Note that, it is assumed that the horizontal axis in (A), (B), and (C) in  FIG.  50    indicates time. Further, all of (A), (B), and (C) in  FIG.  50    indicate the transmission statuses in the fourth frequency (band). 
     As illustrated in (A) in  FIG.  50   , second apparatus  1802  transmits frame for sensing  5001 , frame # 1  for communication of  5002 _ 1 , . . . . 
     Further, (A), (B), and (C) in  FIG.  50    are exemplary frames to which, for example, TDM or TDD is performed so as to reduce interference in each frame. 
     As illustrated in (B) in  FIG.  50   , frames are mapped such that TDM or TDD is performed, and fourth_ 1  apparatus of  2904 _ 1  transmits frame  1 * for communication of  5012 _ 1 , frame  2 * for communication of  5012 _ 2 , . . . . 
     At this time, frame  1 * for communication of  5012 _ 1 , frame  2 * for communication of  5012 _ 2 , . . . may be frames for first apparatus  1201 , may be frames for second apparatus  1802 , may be frames for fourth apparatus of  2904 _ i,  or may be frames for another communication apparatus. 
     Then, as illustrated in (C) of  FIG.  50   , frames are mapped such that TDM or TDD is performed, and fourth_ 2  apparatus of  2904 _ 2  transmits frame ♭ 1  for communication of  5022 _ 1 , frame ♭ 2  for communication of  5022 _ 2 , frame ♭ 3  for communication of  5022 _ 3 , . . . . 
     Frame ♭ 1  for communication of  5022 _ 1 , frame ♭ 2  for communication of  5022 _ 2 , frame ♭ 3  for communication of  5022 _ 3 , . . . may be frames for first apparatus  1201 , may be frames for second apparatus  1802 , may be frames for fourth_i apparatus of  2904 _ i,  or may be frames for another communication apparatus. 
     Note that, when each of the region for fourth_ 1  apparatus of  2904 _ 1  to transmit a signal and the region for fourth_ 2  apparatus of  2904 _ 2  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     Further, when the region for second apparatus  1802  to transmit a signal is named a resource block, a frame for sensing may be allocated to the resource block or a frame for communication may be allocated to the resource block. 
     When “frame  1 * for communication of  5012 _ 1 , frame  2 * for communication of  5012 _ 2 , . . . are frames for first apparatus  1201 ” and “frame ♭ 1  for communication of  5022 _ 1 , frame ♭ 2  for communication of  5022 _ 2 , frame ♭ 3  for communication of  5022 _ 3 , . . . are frames for first apparatus  1201 ”, first apparatus  1201  performs communication by utilizing the fourth frequency (band) even during a sensing-related operation, and further first apparatus  1201  communicates with two fourth_i apparatuses. 
     When “frame  1 * for communication of  5012 _ 1 , frame  2 * for communication of  5012 _ 2 , . . . are frames for second apparatus  1802 ” and “frame ♭ 1  for communication of  5022 _ 1 , frame ♭ 2  for communication of  5022 _ 2 , frame ♭ 3  for communication of  5022 _ 3 , . . . are frames for second apparatus  1802 ”, second apparatus  1802  performs communication by utilizing the fourth frequency (band) even during a sensing-related operation, and further second apparatus  1802  communicates with two fourth_i apparatuses. 
     As described above, first apparatus  1201  and second apparatus  1802  perform sensing and communication by using the fourth frequency (band), and fourth_i apparatus of  2904 _ i  also performs sensing and communication by using the fourth frequency (band) so that it is possible to obtain the effect of improving the frequency utilization efficiency of the fourth frequency (band). 
     Note that, although  FIG.  47   , (A) and (B) in  FIG.  48   , (A) and (B) in  FIG.  49   , and (A), (B), and (C) in  FIG.  50    have been indicated as examples of transmission statuses, the transmission method is not limited to these examples. 
     Further, although the apparatus that transmits a frame for communication is fourth_ 1  apparatus of  2904 _ 1  in (A) and (B) in  FIG.  49   , fourth_i apparatus of  2904 _ i  other than the above apparatus may also transmit a frame for communication. 
     Further, although the apparatuses that transmit a frame for communication are fourth_ 1  apparatus of  2904 _ 1  and fourth_ 2  apparatus of  2904 _ 2  in (A), (B), and (C) in  FIG.  50   , fourth_i apparatus of  2904 _ i  other than the above apparatuses may also transmit a frame for communication. 
     Operation examples of sensing of each apparatus in  FIGS.  29  and  36    have been described above. Hereinafter, configuration examples of first apparatus  1201 , fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q in  FIGS.  29  and  36    will be described. 
       FIGS.  21 A and  21 B  illustrate configuration examples of “first apparatus  1201 , fourth_ 1  apparatus of  2901 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Signal generator  2102  inputs control signal  2100 , and generates and outputs a signal based on information of control signal  2100 . Specific examples thereof (fourth- 2  example and fourth- 2  example) will be described. 
     Fourth- 1  Example: 
     (Transmission) 
     For example, in a case where control signal  2100  indicates that “a modulated signal for communication is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “a modulated signal for communication and a signal for sensing are transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Signal generator  2102  also generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     In a case where control signal  2100  indicates that “a signal for sensing is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     Note that, in a case where the apparatuses in  FIGS.  21 A and  21 B  transmit a modulated signal for communication, the “antenna port used when a modulated signal of the third frequency (band) is transmitted” and the “antenna port used when a modulated signal of the fourth frequency (band) is transmitted” may be the same or different. 
     Further, in a case where a signal for sensing is transmitted from antenna port  2106 , the signal for sensing reflects off, for example, target  2110  and the reflected wave reaches antenna port  2112 . 
     Note that, in the case of  FIG.  36   , a signal for sensing transmitted by second apparatus  1802  reaches antenna port  2112 . 
     (Reception) 
     For example, in a case where control signal  2100  indicates that “demodulation for communication is performed”, a modulated signal is received by using at least one antenna port of antenna port of antenna port  2111 _ 1  to antenna port  211 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116 . Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “demodulation for communication is performed and processing for sensing is performed”, a modulated signal is received by using at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116 . Signal processor  2115  also inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In a case where control signal  2100  indicates that “processing for sensing is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     Note that, in a case where the apparatuses in  FIGS.  21 A and  21 B  receive a modulated signal for communication, the “antenna port used when a modulated signal of the third frequency (band) is received” and the “antenna port used when a modulated signal of the fourth frequency (band) is received” may be the same or different. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports for communication, and antenna port  2106  is a transmission antenna port for sensing. Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports for communication, and antenna port  2112  is a reception antenna port for sensing. 
     Note that, for example, (A) and (B) in  FIG.  22    illustrate an example of a state when the apparatuses of “first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 ” which have the configuration in  FIG.  21 A or  21 B  perform an operation for sensing. For example, as in (A) of  FIG.  22   , it is assumed that the section in which the apparatuses of “first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 ” which have the configuration in  FIG.  21    transmit a signal for sensing is signal transmission section  2201  present between time v 1  and time v 2 . 
     The apparatuses of “first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 ” which have the configuration in  FIG.  21 A or  21 B  receive a signal in “signal transmission section  2201  present between time v 1  and time v 2 ” and perform signal processing to thereby perform sensing of a target. Accordingly, the apparatuses of “first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 ” which have the configuration in  FIG.  21    perform a sensing-related reception operation in the section of “reception-related operation  2202  present between time v 1  and time v 2 ” as in (B) in  FIG.  22   . 
     That is, when sensing is performed, there may be a time section in which the apparatuses of “first apparatus  1201 , base station # 1  of  1201 _ 1 , base station # 2  of  1202 _ 2 , and base station # 3  of  1202 _ 3 ” perform both processing of an operation in a signal transmission section and processing of a signal reception-related operation. Accordingly, such an apparatus configuration that includes an antenna port for communication and an antenna port for sensing separately may be capable of improving the communication performance and sensing performance. 
     Note that, the antenna port may be a logical antenna (antenna group) formed of one or a plurality of physical antennas. That is, the antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna or the like formed of a plurality of antennas. 
     For example, it is not specified how many physical antennas the antenna port is formed of, and a terminal station may be specified as the smallest unit that can transmit a reference signal. Further, the antenna port may be specified as a precoding vector, as a unit that multiplies weighting of a precoding matrix, or as the smallest unit. Note that, the above-described content related to the antenna port becomes the content related to the present specification in its entirety. 
     Further, at least one or more antennas may be shared by antenna ports. For example, there may be an antenna for transmission to be used in a plurality of antenna ports for transmission. Then, for example, there may be an antenna for reception to be used in a plurality of antenna ports for reception. Further, for example, there may be an antenna to be used in a plurality of antenna ports. Note that, the above-described content related to the antenna port becomes the content related to the present specification in its entirety. 
     Fourth- 2  Example: 
     A first mode and a second mode are defined as follows. 
     First mode (for example, a mode corresponding to the standard of the first release): 
     It is assumed that the first mode is a mode corresponding to the first communication scheme. 
     Second mode (for example, a mode corresponding to the standard of the second release): 
     It is assumed that the second mode is a mode corresponding to the second communication scheme and corresponding to sensing. 
     Here, it is assumed that the first mode includes at least a scheme of the third frequency (band), and that the second mode includes at least a scheme of the fourth frequency (band). 
     Hereinafter, three cases will be described. 
     Case 1: 
     (Transmission) 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates “‘a modulated signal and/or a signal for sensing’ of the second mode are/is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2106 , and/or signal generator  2102  generates a signal for sensing, and transmits the signal as a radio wave from antenna port  2106 . 
     In a case where control signal  2100  indicates “a modulated signal of the first mode is transmitted and ‘a modulated signal and/or a signal for sensing’ of the second mode are/is transmitted”, the following two operations are performed: 
     (1) Signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     (2) Signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2106 , and/or signal generator  2102  generates a signal for sensing, and transmits the signal as a radio wave from antenna port  2106 . 
     Note that, when the mode is the second mode, the antenna port through which a signal for sensing is transmitted and the antenna port through which a signal for communication is transmitted may be the same or different. 
     (Reception) 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that “demodulation of the first mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “processing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target, and/or, signal processor  2115  receives a modulated signal by using antenna port  2112 , inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode.” 
     In a case where control signal  2100  indicates that “demodulation of the first mode is performed and processing of the second mode is performed”, the following two operations are performed. 
     (3) At least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. 
     (4) Signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target, and/or, signal processor  2115  receives a modulated signal by using antenna port  2112 , inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports of the first mode, and antenna port  2106  is a transmission antenna port of the second mode. Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports of the first mode, and antenna port  2112  is a reception antenna port of the second mode. 
     Note that, when the mode is the second mode, the antenna port through which a signal for sensing is received and the antenna port through which a signal for communication is received may be the same or different. 
     Case 2: 
     (Transmission) 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _(N−1). Note that, it is assumed that N is an integer larger than or equal to 2. 
     In a case where control signal  2100  indicates that “at least ‘a modulated signal for communication’ of the second mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using antenna port  2105 _N. 
     In a case where control signal  2100  indicates that “at least ‘a signal for sensing’ of the second mode is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     (Reception) 
     Further, in  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “demodulation of the first mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _(M−1) is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 2. 
     In a case where control signal  2100  indicates that at least “demodulation of the second mode is performed”, a modulated signal is received by using antenna port  2111 _M, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In a case where control signal  2100  indicates that at least “processing for sensing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _(N−1) are transmission antenna ports of the first mode, antenna port  2105 _N is a transmission antenna port for communication of the second mode, and antenna port  2106  is a transmission antenna port for sensing of the second mode. Further, antenna ports  2111 _ 1  to  2111 _(M−1) are reception antenna ports of the first mode, antenna port  2111 _M is a reception antenna port for communication of the second mode, and antenna port  2112  is a reception antenna port for sensing of the second mode. 
     Case 3: 
     (Transmission) 
     In  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “a modulated signal of the first mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the first mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. Note that, it is assumed that N is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that “at least ‘a modulated signal for communication’ of the second mode is transmitted”, signal generator  2102  performs processing, which includes error correction coding, modulation (mapping), and processing based on a transmission method, on data  2101 , and transmits a modulated signal of the second mode as a radio wave by using at least one antenna port of antenna port  2105 _ 1  to antenna port  2105 _N. 
     In a case where control signal  2100  indicates that “at least ‘a signal for sensing’ of the second mode is transmitted”, signal generator  2102  generates a signal for sensing and transmits the signal as a radio wave from antenna port  2106 . 
     (Reception) 
     Further, in  FIGS.  21 A and  21 B , for example, in a case where control signal  2100  indicates that at least “demodulation of the first mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the first mode. Note that, it is assumed that M is an integer larger than or equal to 1. 
     In a case where control signal  2100  indicates that at least “demodulation of the second mode is performed”, at least one antenna port of antenna port  2111 _ 1  to antenna port  2111 _M is used to receive a modulated signal, and signal processor  2115  inputs this modulated signal, performs processing including demodulation, and outputs reception data  2116  of the second mode. 
     In a case where control signal  2100  indicates that at least “processing for sensing of the second mode is performed”, signal processor  2115  inputs a signal received by antenna port  2112 , performs processing for sensing, and, for example, outputs distance information or the like  2117  of a target. 
     In the examples described above, antenna ports  2105 _ 1  to  2105 _N are transmission antenna ports of the first mode and transmission antenna ports for communication of the second mode, and antenna port  2106  is a transmission antenna port for sensing of the second mode. Further, antenna ports  2111 _ 1  to  2111 _M are reception antenna ports of the first mode and reception antenna ports for communication of the second mode, and antenna port  2112  is a reception antenna port for sensing of the second mode. 
     As described above, it is possible to obtain the effect that both high-quality communication and highly-accurate sensing can be achieved by selectively using an antenna port used at the time of communication and an antenna port used at the time of sensing. 
     Note that, as described above,  FIGS.  21 A and  21 B  have been indicated as the configurations of first apparatus  1201 , fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q, and the use method of antenna ports has been described. As a matter of course, “first apparatus  1201 , fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and the “use method of antenna ports” are applicable to embodiments other than the present embodiment. 
     Further, when there are two apparatuses (named apparatuses #A and #B) in the present embodiment and apparatus #A or #B transmits a radio wave and estimates a “distance between apparatuses #A and #B”, apparatus #A or #B may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to estimate the position of a target with more accuracy. 
     In the same manner, when apparatus #A transmits a radio wave and estimates a “distance between apparatus #A and a target”, apparatus #A may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of the target with higher accuracy. 
     Further, when apparatus #A or #B transmits a radio wave and estimates a direction of arrival, apparatus #A or #B may estimate the “distance between apparatuses #A and #B” and utilize an estimated value of the above “distance between apparatuses #A and #B” to perform position estimation of a target with higher accuracy. 
     When apparatus #A transmits a radio wave and apparatus A estimates the direction of arrival of the radio wave obtained by the radio wave, for example, reflecting off a target, apparatus #A may estimate the “distance between apparatus #A and the target” and utilize the above “distance between apparatus #A and the target” to perform position estimation of the target with higher accuracy. 
     Note that, although  FIGS.  31 ,  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G,  32 H,  33 ,  34   , and  35  have been indicated as examples of the operation flows of the first apparatus, the third apparatus, and the fourth_ 1  apparatus, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. Further, although  FIGS.  37 ,  38 ,  39 , and  40    have been indicated as examples of the operation flows of the first apparatus, the second apparatus, the third apparatus, and the fourth_ 1  apparatus, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     Further,  FIG.  41   , (A) and (B) in  FIG.  42   , (A) in  FIG.  43   , (B) in  FIG.  44   , (A), (B), and (C) in  FIG.  45   , (A), (B), and (C) in  FIG.  46   ,  FIG.  47   , (A) and (B) in  FIG.  48   , (A) and (B) in  FIG.  49   , and (A), (B), and (C) of  FIG.  50    have been indicated as frame configuration examples of each apparatus, but are merely examples, and frames other than those indicated in the drawings, such as a frame for transmitting control information, a signal for performing beamforming (for example, a signal for sector sweeping), and a reference signal may be present. 
     Embodiment 5 
     In the present embodiment, an exemplary embodiment that differs from Embodiment 4 will be described. 
       FIG.  51    illustrates an example of the “sensing system” or “sensing and communication system” in the present embodiment. 
     In  FIG.  51   , third apparatus  2903  communicates with first apparatus  1201  by using a third frequency (band). 
     Fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q perform communication by using a fourth frequency (band). Note that, it is assumed that Q is an integer larger than or equal to 1. 
     Note that, there is a method in which the third frequency (band) is FR1 and/or FR2 and the fourth frequency (band) is a frequency of 52.6 GHz or higher, for example. It is assumed, however, that FR1 is a “frequency from 450 MHz to smaller than or equal to 6 GHz” and FR2 is a “frequency from 24.25 GHz to 52.6 GHz”. Further, as another example, the fourth frequency (band) may be a frequency higher than the third frequency (band). As yet another example, the third frequency (band) may be FR1 and the fourth frequency (band) may be FR2. 
     Further, it is assumed that third apparatus  2903  communicates with fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q. The communication this time may be radio communication or wired communication. 
     Communication may be possible between two apparatuses of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. Note that, the communication this time may be radio communication or wired communication. 
     Target (object)  1203  is a target object whose position is estimated by sensing. 
     In the present embodiment, a method of performing “the triangulation described in Embodiment 1 with first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ”, “the triangulation described in Embodiment 1 with first apparatus  1201  and fourth_ 2  apparatus of  2904 _ 2 ”, . . . , the “triangulation described in Embodiment 1 with first apparatus  1201  and fourth_Q apparatus of  2904 _Q” will be described as an example. 
     Here, it is assumed that first apparatus  1201  performs sensing for performing triangulation. At this time, first apparatus  1201  performs sensing with one of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” to realize triangulation. However, it is supposed that there is fourth_i apparatus of  2904 _ i  that does not correspond to sensing due to factors such as the size of fourth_i apparatus of  2904 _ i  and the time of the installation. Note that, it is assumed that i is an integer larger than or equal to 1 and smaller than or equal to Q. 
     Accordingly, it is assumed that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” transmit control information including information on sensing capability  3001  as illustrated in  FIG.  30   . For example, it is assumed that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” transmit the control information including information on sensing capability  3001  by using, for example, a PBCH, a PDSCH or a PDCCH. 
     The channel through which the above control information is transmitted is not limited to the examples described above. Further, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  to first apparatus  1201  or third apparatus  2903 . 
     As illustrated in  FIG.  30   , it is assumed that information on sensing capability  3001  includes at least one of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and/or “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”. 
     It is assumed that specific examples of “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”, and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” are as follows. 
     “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”: 
     This information is used to notify, for example, first apparatus  1201 , a repeater, another fourth_x apparatus, third apparatus  2903 , or the like of “whether fourth_i apparatus of  2904 _ i  is capable of performing sensing”. 
     Thus, in a case where at least information that “sensing is performable” is included as “INFORMATION ON WHETHER SENSING IS POSSIBLE OR IMPOSSIBLE  3011 ”, it is assumed that fourth_i apparatus of  2904 _ i  has a sensing function. Further, it is assumed that this fourth_i apparatus of  2904 _ i  has a communication function. Note that, since the specific configuration has already been described in Embodiment 1, a description thereof will be omitted. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ”: 
     This information is used to notify, for example, first apparatus  1201 , third apparatus  2903 , or the like of information on “whether sensing is performable” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201  (a request of the terminal for first apparatus  1201  to perform sensing). 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” may also be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is performable or not performable”. Further, details of the “sensing request” will be described later. 
     “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ”: 
     This information is used to notify, for example, first apparatus  1201  or the like of information on “whether fourth_i apparatus of  2904 _ i  accepts sensing from first apparatus  1201 ” when fourth_i apparatus of  2904 _ i  receives a sensing request from first apparatus  1201  (a request of the terminal for first apparatus  1201  to perform sensing). 
     Accordingly, there are modes in which, even when there is a sensing request from first apparatus  1201 , fourth_i apparatus of  2904 _ i  “accepts” and “does not accept” the sensing request. 
     Note that, although “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” is named here, “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” may be “information on whether a sensing request from an apparatus other than first apparatus  1201 , such as a repeater, third apparatus  2903 , and another base station, is acceptable or not acceptable”. Further, details of the “sensing request” will be described later. 
     By configuring the above, first apparatus  1201 , a repeater, third apparatus  2903 , another base station, and the like can know sensing of a base station and a state with respect to a sensing request so that it is possible to obtain the effect that suitable “sensing-related control and communication with fourth_i apparatus of  2904 _ i ” can be performed. 
     Note that, the apparatus that transmits information on sensing capability  3001  in  FIG.  30    has been described as fourth_i apparatus of  2904 _ i  above, but is merely an example, and information on sensing capability  3001  may be transmitted by a communication apparatus such as a repeater, a terminal, an access point, and third apparatus  2903 . 
     Further, although the description “[ . . . ] SENSING REQUEST FROM FIRST APPARATUS  1201 ” is used in “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS PERFORMABLE OR NOT PERFORMABLE  3012 ” and “INFORMATION ON WHETHER SENSING REQUEST FROM FIRST APPARATUS  1201  IS ACCEPTABLE OR NOT ACCEPTABLE  3013 ” which are transmitted by the apparatus that transmits information on sensing capability  3001  in  FIG.  30   , a sensing request may be not from first apparatus  1201 , but may be from, for example, a communication apparatus such as a base station, a repeater, an access point, and third apparatus  2903 . Accordingly, implementation is also possible with  3012  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS PERFORMABLE OR NOT PERFORMABLE” and  3013  as “INFORMATION ON WHETHER SENSING REQUEST FROM COMMUNICATION APPARATUS IS ACCEPTABLE OR NOT ACCEPTABLE”. 
     Next, sensing by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  in  FIG.  51    will be described. 
     First apparatus  1201  may be a terminal capable of communicating with third apparatus  2903  and fourth_i apparatus of  2904 _ i.  Alternatively, first apparatus  1201  may be a base station (or an access point, a repeater, or the like). In addition, first apparatus  1201  may also be fourth_x apparatus of  2904 _ x  (where x is a natural number, for example). Further, third apparatus  2903  may be a base station or may be a terminal, a repeater, an access point, or the like. Fourth_i apparatus of  2904 _ i  may be a base station or may be a terminal, a repeater, an access point, or the like. 
     In the following description, first apparatus  1201  will be described as a terminal, but it is also performable in the same manner even when first apparatus  1201  is a base station, an access point or a repeater. However, in a case where a particular operation occurs when first apparatus  1201  is a base station, a supplementary description will be provided. 
     The present embodiment deals with triangulation. Examples of the specific triangulation method have been described in Embodiment 1. The first method and the second method are triangulation based on the fact that information on a distance is obtained by performing sensing. 
     The third method and the fourth method are, on the other hand, triangulation based on the fact that information on a direction (of arrival) (having said that, a distance may also be obtained) is obtained by performing sensing. 
     Hereinafter, with respect to  FIG.  51   , direction-based triangulation whose examples are the third method and the fourth method will be described. Note that, the present embodiment is a variation of the third method and the fourth method. 
     Case of Direction-Based Triangulation: 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     First apparatus  1201  obtains information on sensing capability  3001  in  FIG.  30   , which is transmitted by “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”, and acquires each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     As another method, “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” may transmit information on sensing capability  3001  in  FIG.  30    to third apparatus  2903 , and third apparatus  2903  may transmit control information including information on sensing capability of each apparatus of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” by using the third frequency. Thus, first apparatus  1201  knows each status of response to sensing of “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q”. 
     Hereinafter, it is assumed as an example that “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform sensing, and that in a case where there is a sensing request from, for example, a terminal such as first apparatus  1201 , “fourth_ 1  apparatus of  2904 _ 1 , fourth_ 2  apparatus of  2904 _ 2 , . . . , fourth_Q apparatus of  2904 _Q” can all perform a sensing operation for the request for performing sensing. 
       FIG.  52    illustrates a procedure example for sensing in the system example in  FIG.  51   . It is assumed that first apparatus  1201  transmits a signal for sensing, this signal comes into contact with target  1203 , and fourth_ 1  apparatus of  2904 _ 1  receives the signal for sensing, thereby performing position estimation, for example. 
     Further, it is assumed that first apparatus  1201  has obtained at least information on a “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” before “ESTIMATE POSITION OF TARGET (OBJECT)  5204 ” is performed. 
     Note that, since the method of obtaining the information on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” has already been described with reference to  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G, and  32 H , a description thereof will be omitted. 
     As another method, when first apparatus  1201  is a base station or a fixedly installed terminal, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may have acquired the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” in advance. 
     Further, first apparatus  1201  and fourth_i apparatus of  2904 _ i  may acquire positions by a position estimation system such as GPS, for example. Then, fourth_i apparatus of  2904 _ i  may transmit information on its own position to first apparatus  1201 , and first apparatus  1201  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from information on its own position and the information on the position of fourth_i apparatus of  2904 _ i.  Then, first apparatus  1201  may transmit the information on its own position to fourth_i apparatus of  2904 _ i  and fourth_i apparatus of  2904 _ i  may determine the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ” from the information on its own position and the information on the position of first apparatus  1201 . 
     An example when the direction-based triangulation whose examples are the third method and the fourth method described in Embodiment 1 is used will be described. 
     As in  FIG.  52   , the first apparatus in  FIG.  51    selects fourth_ 1  apparatus of  2904 _ 1  as the apparatus that operates for sensing of target  1203  (that senses the target) ( 5201 ). 
     Note that, when fourth_i apparatus of  2904 _ i  which is requested to perform the estimation of the direction (of arrival) with target  1203  is determined (in advance), “SELECT FOURTH_i APPARATUS OF  2904 _ i  FOR SENSING OF TARGET (THAT SENSES TARGET)  5201 ” may not be performed. 
     First apparatus  1201  transmits information on a request for “estimation of a direction (of arrival) with target  1203 ” to third apparatus  2903  ( 5202 ). 
     Third apparatus  2903  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and transmits the information on the request for “estimation of the direction (of arrival) with target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 5221 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the information on the request for “estimation of the direction (of arrival) with target  1203 ”, and responds “whether fourth_ 1  apparatus of  2904 _ 1  accepts the request” ( 5211 ). Note that, in the example here, a description will be given on the assumption that fourth_ 1  apparatus of  2904 _ 1  “accepts the request”. 
     Third apparatus  2903  receives information on the response to the request. Then, third apparatus  2903  transmits the information on the response to the request to first apparatus  1201  ( 5222 ). 
     First apparatus  1201  transmits a signal for performing sensing ( 5203 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives the signal for performing sensing transmitted by first apparatus  1201 , and obtains an estimated value of a “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” ( 5212 ). 
     Fourth_ 1  apparatus of  2904 _ 1  transmits information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and feedback information to third apparatus  2903  ( 5213 ). 
     Third apparatus  2903  receives the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and the feedback information, and transmits the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and the feedback information to first apparatus  1201  ( 5223 ). 
     First apparatus  1201  obtains the information on the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” and the feedback information, performs triangulation by using the “distance between first apparatus  1201  and fourth_i apparatus of  2904 _ i ”, the “direction (of arrival) of first apparatus  1201  and target  1203 ”, and the “direction (of arrival) of fourth_ 1  apparatus of  2904 _ 1  and target  1203 ”, and estimates the position of target  1203 , for example ( 5204 ). 
     Then, first apparatus  1201  transmits information on the “position of target  1203 ” to third apparatus  2903  ( 5205 ). Third apparatus  2903  receives the information on the “position of target  1203 ” and transmits the information on the “position of target  1203 ” to fourth_ 1  apparatus of  2904 _ 1  ( 5224 ). 
     Note that, in a case where first apparatus  1201  and fourth_i apparatus of  2904 _ i  do not need to share the information on the “position of target  1203 ”, first apparatus  1201  may not transmit the information on the “position of target  1203 ” to third apparatus  2903 . 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Operation examples of  5203 ,  5212 ,  5213 , and  5204  in  FIG.  52    will be described. In  FIG.  51   , fourth_ 1  apparatus of  2904 _ 1  can estimate the angle formed by the “line segment formed by fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201 ” and the “line segment formed by fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” in  FIG.  52    by receiving a signal for sensing transmitted by first apparatus  1201  to perform direction(-of-arrival) estimation. 
     As an example, triangulation can be realized when the angle formed by the “line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” and the “line segment formed by first apparatus  1201  and target  1203 ” can be estimated. Hereinafter, a method of estimating the angle formed by the “line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” and the “line segment formed by first apparatus  1201  and target  1203 ” will be described. 
       FIG.  24    illustrates an example of a configuration of first apparatus  1201  (and fourth_ 1  apparatus of  2904 _ 1  and fourth_i apparatus of  2904 _ i ) in  FIG.  51   . In  FIG.  24   , parts which operate in the same manner as in  FIG.  21    are denoted with the same numbers, and descriptions thereof will be omitted. 
     Note that, a description will be given with an example in which first apparatus  1201  has the configuration in  FIG.  24   . Further, although the configuration in  FIG.  24    is related to transmission and reception in the fourth frequency (band)  FIG.  24    does not describe a configuration related to transmission and reception in the third frequency (band), first apparatus  1201  (and fourth_ 1  apparatus of  2904 _ 1 ) may include apparatuses related to transmission and reception in the third frequency (band). 
     As illustrated in  FIG.  24   , it is assumed that first apparatus  1201  includes transmission antennas  2402 _ 1  to  2402 _L. Note that, it is assumed that L is an integer larger than or equal to 1. 
       FIG.  25    illustrates a configuration example related to transmission antenna  2402 _ i  (where i is an integer larger than or equal to 1 and smaller than or equal to L). 
     As illustrated in  FIG.  25   , it is assumed that transmission antenna  2402 _ i  is formed of four antennas as in, for example, antennas  2504 _ 1 ,  2504 _ 2 ,  2504 _ 3 , and  2405 _ 4 . Although an example in which transmission antenna  2402 _ i  is formed of four antennas has been indicated here, the number of antennas is not limited to this example as long as transmission antenna  2402 _ i  is formed of two or more antennas. 
     Processor  2502  inputs signal  2501  (corresponding to signal  2401 _ i  in  FIG.  24   ) and control signal  2500  (corresponding to control signal  2100  in  FIG.  24   ). In a case where control signal  2500  indicates that “a signal for sensing is transmitted”, processor  2502  performs transmission directivity control processing on signal  2501  and outputs signal  2503 _ i  after the transmission directivity control processing. Note that, i is an integer larger than or equal to 1 and smaller than or equal to 4. Further, signal  2503 _ i  after the transmission directivity control processing is outputted as a radio wave from antenna  2504 _ i.    
     A specific configuration example of a signal for sensing to be transmitted by first apparatus  1201  will be described. 
       FIG.  26    illustrates an example of frame of signal for sensing  2601  (in the fourth frequency (band)) to be transmitted by first apparatus  1201 . 
     It is assumed that frame of signal for sensing  2601  is formed of, for example, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING FIRST ANTENNA  2611 _ 1 ”, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING SECOND ANTENNA  2611 _ 2 ”, . . . , “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING L-TH ANTENNA  2611 _L”. 
     “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING FIRST ANTENNA  2611 _ 1 ” is a signal to be transmitted from transmission antenna  2402 _ 1  of first apparatus  1201 . 
     “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING L-TH ANTENNA  2611 _L” is a signal to transmitted from transmission antenna  2402 _L of first apparatus  1201 . 
     That is, SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i  is a signal to be transmitted from transmission antenna  2402 _ i  of first apparatus  1201 . Note that, i is an integer larger than or equal to 1 and smaller than or equal to L. 
       FIG.  27    illustrates an example of a configuration of SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i  in  FIG.  26   . 
     As illustrated in  FIG.  27   , it is assumed that SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA  2611 _ i  is formed of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ”, “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ”, . . . , “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ”. Note that, it is assumed that z is “an integer larger than or equal to 1” or “an integer larger than or equal to 2”. 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the first parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ”, and “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND FIRST PARAMETER  2701 _ 1 ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the second parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ”, and “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND SECOND PARAMETER  2701 _ 2 ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
     In transmission antenna  2402 _ i  in  FIG.  24    of first apparatus  1201 , processor  2502  in  FIG.  25    performs transmission directivity control by using the z-th parameter and generates “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ”, and “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ” is transmitted by using antennas  2504 _ 1  to  2504 _ 4  in  FIG.  25   . Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND z-TH PARAMETER  2701 _ z ” is formed of four signals of signals  2503 _ 1 ,  2503 _ 2 ,  2503 _ 3 , and  2503 _ 4 . 
       FIG.  28    illustrates a configuration example of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” in  FIG.  27   . Note that, j is an integer larger than or equal to 1 and smaller than or equal to z. 
     As illustrated in  FIG.  28   , it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” includes, for example, “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ”. Note that, it is assumed that “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” includes, albeit not illustrated in  FIG.  28   , a signal for performing sensing. 
     It is assumed that “ANTENNA INFORMATION  2801 ” includes information that allows the use of “the i-th antenna” to be identified (for example, information on antenna ID (identification) or the like). Accordingly, fourth_ 1  apparatus of  2904 _ 1  that has been able to receive “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” can obtain information on an antenna used when first apparatus  1201  transmits a signal for sensing. 
     Further, it is assumed that “PARAMETER INFORMATION  2802 ” includes information that allows a parameter used for transmission directivity control to be identified (for example, information on parameter ID (identification) or the like). Accordingly, fourth_ 1  apparatus of  2904 _ 1  that has been able to receive “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” can obtain information on a parameter for antenna transmission directivity control used when first apparatus  1201  transmits a signal for sensing. 
     Note that, first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  may transmit reference signal  2899  (for sensing) in  FIG.  28    together with the information described above. Note that, reference signal  2899  is transmitted by using the i-th antenna and the j-th parameter. 
     In  5203  and  5212  in  FIG.  52   , fourth_ 1  apparatus of  2904 _ 1  can receive, of frame for sensing  2601  transmitted by first apparatus  1201 , one signal of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ”. Then fourth_ 1  apparatus of  2904 _ 1  sets, as feedback information, “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ” of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” which fourth_ 1  apparatus of  2904 _ 1  has been able to receive, and transmits this feedback information to first apparatus  1201  via, third apparatus  2903 . 
     First apparatus  1201  obtains this feedback information, and can know the transmission directivity, that is, the direction, of the signal, which fourth_ 1  apparatus of  2904 _ 1  has been able to receive, that is, can estimate the angle formed by the “line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” and the “line segment formed by first apparatus  1201  and target (object)  1203 ” in  FIG.  51   . 
     Accordingly, fourth_ 1  apparatus of  2904 _ 1  has obtained “the angle formed by the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201 ’ and the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and target  1203 ’”, “the angle formed by the ‘line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ’ and the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’”, and the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” in  FIG.  51   , and therefore can estimate the position of target (object)  1203 . 
     Note that, although “ANTENNA INFORMATION  2801 ” and “PARAMETER INFORMATION  2802 ” have been described separately in  FIG.  28   , information may be generated without making a distinction therebetween. 
     For example, an ID is given with ID ♭ 1  in the case of “the first antenna and the first parameter”, ID ♭ 2  in the case of “the first antenna and the second parameter”, ID ♭ 3  in the case of “the second antenna and the first parameter”, ID ♭ 4  in the case of “the second antenna and the second parameter”, . . . . 
     Then, for example, first apparatus  1201  transmits a “signal for sensing to be transmitted by using the first antenna and the first parameter” such that the “signal for sensing to be transmitted by using the first antenna and the first parameter” includes information on ID ♭ 1 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the first antenna and the second parameter” such that the “signal for sensing to be transmitted by using the first antenna and the second parameter” includes information on ID ♭ 2 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the second antenna and the first parameter” such that the “signal for sensing to be transmitted by using the second antenna and the first parameter” includes information on ID ♭ 3 . 
     First apparatus  1201  transmits a “signal for sensing to be transmitted by using the second antenna and the second parameter” such that the “signal for sensing to be transmitted by using the second antenna and the second parameter” includes information on ID ♭ 4 . 
     Then, fourth_ 1  apparatus of  2904 _ 1  sets, as feedback information, ID information (for example, ID ♭ 1 , ID ♭ 2 , . . . ) of “SIGNAL FOR SENSING TO BE TRANSMITTED BY USING i-TH ANTENNA AND j-TH PARAMETER  2701 _ j ” which fourth_ 1  apparatus of  2904 _ 1  has been able to receive, and transmits this feedback information to first apparatus  1201  via third apparatus  2903 . 
     First apparatus  1201  obtains this feedback information, and can know the transmission directivity, that is, the direction, of the signal, which fourth_ 1  apparatus of  2904 _ 1  has been able to receive, that is, can estimate the angle formed by the “line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” and the “line segment formed by first apparatus  1201  and target (object)  1203 ”. 
     Accordingly, fourth_ 1  apparatus of  2904 _ 1  has obtained “the angle formed by the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201 ’ and the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and target  1203 ’”, “the angle formed by the ‘line segment formed by first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ’ and the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’”, and the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ” in  FIG.  51   , and therefore can estimate the position of target (object)  1203 . 
     Another example of operations in  5203 ,  5212 ,  5213 , and  5204  in  FIG.  52    will be described. 
     Fourth_ 1  apparatus of  2904 _ 1  can estimate the angle formed by the “line segment formed by fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201 ” and the “line segment formed by fourth_ 1  apparatus of  2904 _ 1  and target  1203 ” in  FIG.  51    by receiving a signal for sensing transmitted by first apparatus  1201  to perform direction(-of-arrival) estimation. 
     Further, triangulation can be performed by estimating the sum of the “line segment formed by first apparatus  1201  and target (object)  1203 ” and the “line segment formed by target (object)  1203  and fourth_ 1  apparatus of  2904 _ 1 ” in  FIG.  51   . 
     Accordingly, as in  5203  of  FIG.  52   , first apparatus  1201  transmits a signal for sensing, fourth_ 1  apparatus of  2904 _ 1  receives this signal for sensing ( 5212 ) and estimates the sum of the “line segment formed by first apparatus  1201  and target (object)  1203 ” and the “line segment formed by target (object)  1203  and fourth_ 1  apparatus of  2904 _ 1 ”, and fourth_ 1  apparatus of  2904 _ 1  transmits information on this estimation value to first apparatus  1201 . Further, fourth_ 1  apparatus of  2904 _ 1  transmits a reception direction-of-arrival estimation result to first apparatus  1201 . Note that, since the transmission method of the signal for sensing to be transmitted by first apparatus  1201  has been described with reference to  FIGS.  24 ,  25 ,  26 ,  27 , and  28   , a description thereof will be omitted. 
     Then, first apparatus  1201  can estimate the position of target (object)  1203  based on the “distance between first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 ”, “the sum of the ‘line segment formed by first apparatus  1201  and target (object)  1203 ’ and the ‘line segment formed by target (object)  1203  and fourth_ 1  apparatus of  2904 _ 1 ’”, and “the angle formed by the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and first apparatus  1201 ’ and the ‘line segment formed by fourth_ 1  apparatus of  2904 _ 1  and target  1203 ’”. 
     By performing as described above, it is possible to realize triangulation. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Note that, when there are two apparatuses (named apparatuses #A and #B) in the present embodiment and apparatus #A or #B transmits a radio wave and estimates a “distance between apparatuses #A and #B”, apparatus #A or #B may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of a target with higher accuracy. 
     In the same manner, when apparatus #A transmits a radio wave and estimates a “distance between apparatus #A and a target”, apparatus #A may estimate a direction of arrival and utilize an estimated value of the above direction of arrival to perform position estimation of the target with higher accuracy. 
     Further, when apparatus #A or #B transmits a radio wave and estimates a direction of arrival, apparatus #A or #B may estimate the “distance between apparatuses #A and #B” and utilize an estimated value of the above “distance between apparatuses #A and #B” to perform position estimation of a target with higher accuracy. 
     When apparatus #A transmits a radio wave and apparatus A estimates the direction of arrival of the radio wave obtained by the radio wave, for example, reflecting off a target, apparatus #A may estimate the “distance between apparatus #A and the target” and utilize the above “distance between apparatus #A and the target” to perform position estimation of the target with higher accuracy. 
     Note that, although  FIGS.  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G,  32 H, and  52    have been indicated as examples of the operation flows of the first apparatus, fourth_i apparatus of  2904 _ i,  and the third apparatus, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     Further, in the same manner as in Embodiment 4, first apparatus  1201  may change fourth_i apparatus of  2904 _ i  which is requested to perform sensing in order to increase the accuracy of position estimation of a target in the operation flow of  FIG.  52   . 
     For example, in a case where fourth_i apparatus of  2904 _ i  performs “TRANSMIT DIRECTION-OF-ARRIVAL ESTIMATION RESULT AND FEEDBACK INFORMATION  5213 ”, first apparatus  1201  receives the result and the feedback information, and determines, as described in Embodiment 4, that position estimation of a target may not be obtained with high accuracy, first apparatus  1201  may change fourth_i apparatus of  2904 _ i  which is requested to perform sensing. 
     Further, in a case where first apparatus  1201  performs position estimation of a target ( 5204 ) and determines that the position estimation of the target has not been obtained with high accuracy, first apparatus  1201  may request another fourth_i apparatus of  2904 _ i  to perform sensing. 
     Embodiment 6 
     In the present embodiment, a variation of Embodiments 2 and 3 will be described. Note that, in the present embodiment, a description will be made by using the terms of the first apparatus and the base station as described in Embodiments 2 and 3, but it is assumed that the first apparatus is the base station. 
       FIGS.  53  and  54    illustrate examples of the “sensing system” or “sensing and communication system” in the present embodiment. 
     In  FIG.  53   , first apparatus  1201  and base station # 2  of  1202 _ 2  perform sensing of a target as described in Embodiments 2 and 3. Since the sensing-related operation this time has been described in detail in Embodiments 2 and 3, a description thereof will be omitted in the present embodiment. 
     It is assumed that tenth apparatus  5301  in  FIG.  53    is, for example, a terminal, and that first apparatus  1201  and the base stations perform sensing based on an instruction by tenth apparatus  5301 . Note that, tenth apparatus  5301  has been described as a terminal, but is not limited thereto. 
     In  FIG.  54   , first apparatus  1201  and base station # 2  of  1202 _ 2  perform sensing of second apparatus  1802  as described in Embodiments 2 and 3. Since the sensing-related operation this time has been described in detail in Embodiments 2 and 3, a description thereof will be omitted in the present embodiment. 
     It is assumed that tenth apparatus  5301  in  FIG.  54    is, for example, a terminal, and that first apparatus  1201  and the base stations perform sensing based on an instruction by tenth apparatus  5301 . Note that, tenth apparatus  5301  has been described as a terminal, but is not limited thereto. 
       FIGS.  55 A and  55 B  illustrate operation examples when first apparatus  1201  and a base station perform sensing based on an instruction by tenth apparatus  5301  in  FIG.  53  or  54   . 
     As in  FIG.  55 A , tenth apparatus  5301  in  FIG.  53  or  54    transmits information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201  ( 5501 ). 
     First apparatus  1201  receives this information, and transmits a response ( 5511 ). Note that, it is assumed here that first apparatus  1201  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Then, it is assumed that first apparatus  1201  and base station # 2  of  1202 _ 2  perform the sensing described in Embodiments 2 and 3. 
     Tenth apparatus  5301  receives a response to the request for sensing ( 5502 ). 
     Case where First Apparatus Demands Sensing Result: 
     As in  FIG.  55 B , first apparatus  1201  transmits, for example, information on a sensing result obtained by performing triangulation to tenth apparatus  5301  ( 5512 ). 
     Tenth apparatus  5301  receives this information on the sensing result ( 5503 ). 
     Case where Base Station # 2  Demands Sensing Result: 
     As in  FIG.  55 B , base station # 2  of  1202 _ 2  transmits, for example, information on a sensing result obtained by performing triangulation to tenth apparatus  5301  ( 5521 ). 
     Tenth apparatus  5301  receives this information on the sensing result ( 5503 ). 
     Note that,  FIG.  55 B  may not be performed if not necessary. 
     Next,  FIGS.  56 A and  56 B  that differ from  FIGS.  55 A and  55 B  will be described. 
       FIGS.  56 A and  56 B  illustrate operation examples when first apparatus  1201  and a base station perform sensing based on an instruction by tenth apparatus  5301  in  FIG.  53  or  54   . 
     As in  FIG.  56 A , tenth apparatus  5301  in  FIG.  53  or  54    transmits information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201  and base station # 2  of  1202 _ 2  ( 5601 ). 
     First apparatus  1201  receives the information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, detection of the position of target (object)  1203  or second apparatus  1802 ), and transmits a response ( 5611 ). 
     Note that, it is assumed here that first apparatus  1201  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Further, base station # 2  of  1202 _ 2  receives the information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, detection of the position of target (object)  1203  or second apparatus  1802 ), and transmits a response ( 5621 ). 
     Note that, it is assumed here that base station # 2  of  1202 _ 2  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Then, it is assumed that first apparatus  1201  and base station # 2  of  1202 _ 2  perform the sensing described in Embodiments 2 and 3. 
     Tenth apparatus  5301  receives responses to the request for sensing ( 5602 ). 
     Case where First Apparatus Demands Sensing Result: 
     As in  FIG.  56 B , first apparatus  1201  transmits, for example, information on a sensing result obtained by performing triangulation to tenth apparatus  5301  ( 5612 ). 
     Tenth apparatus  5301  receives this information on the sensing result ( 5603 ). 
     Case where Base Station # 2  Demands Sensing Result: 
     As in  FIG.  56 B , base station # 2  of  1202 _ 2  transmits, for example, information on a sensing result obtained by performing triangulation to tenth apparatus  5301  ( 5622 ). 
     Tenth apparatus  5301  receives this information on the sensing result ( 5603 ). 
     Note that,  FIG.  55 B  may not be performed if not necessary. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Note that, although  FIGS.  55 A,  55 B,  56 A, and  56 B  have been indicated as examples of the operation flows of the tenth apparatus, the first apparatus, and the base station, they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     Embodiment 7 
     In the present embodiment, a variation of Embodiments 4 and 5 will be described. Note that, in the present embodiment, a description will be made by using the terms of the first apparatus and the base station as described in Embodiments 4 and 4, but it is assumed that the first apparatus is the base station. 
       FIGS.  57 ,  58 , and  59    illustrate examples of the “sensing system” or “sensing and communication system” in the present embodiment. 
     In  FIG.  57   , first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing of a target as described in Embodiments 4 and 5. Since the sensing-related operation this time has been described in detail in Embodiments 4 and 5, a description thereof will be omitted in the present embodiment. 
     It is assumed that tenth apparatus  5301  in  FIG.  57    is, for example, a terminal, and that first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing based on an instruction by tenth apparatus  5301 . Note that, tenth apparatus  5301  has been described as a terminal, but is not limited thereto. 
     In  FIG.  58   , first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing of second apparatus  1802  as described in Embodiments 4 and 5. Since the sensing-related operation this time has been described in detail in Embodiments 4 and 5, a description thereof will be omitted in the present embodiment. 
     It is assumed that tenth apparatus  5301  in  FIG.  58    is, for example, a terminal, and that first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing based on an instruction by tenth apparatus  5301 . Note that, tenth apparatus  5301  has been described as a terminal, but is not limited thereto. 
     In  FIG.  59   , first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing of a target as described in Embodiments 4 and 5. Since the sensing-related operation this time has been described in detail in Embodiments 4 and 5, a description thereof will be omitted in the present embodiment. 
     It is assumed that tenth apparatus  5301  in  FIG.  59    is, for example, a terminal, and that first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing based on an instruction by tenth apparatus  5301 . Note that, tenth apparatus  5301  has been described as a terminal, but is not limited thereto. 
       FIGS.  60 A and  60 B  illustrate operation examples when first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing based on an instruction by tenth apparatus  5301  in  FIG.  57 ,  58  or  59   . 
     As in  FIG.  60 A , for transmitting information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201 , tenth apparatus  5301  in  FIG.  57 ,  58  or  59    transmits information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ) to third apparatus  2903  for first apparatus  1201  ( 6001 ). 
     Third apparatus  2903  receives this information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ), and transmits the information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201 . 
     First apparatus  1201  receives this information, and transmits a response ( 6021 ). 
     Note that, it is assumed here that first apparatus  1201  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Then, it is assumed that first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  perform the sensing described in Embodiments 4 and 5. 
     Case where First Apparatus Demands Sensing Result: 
     As in  FIG.  60 B , first apparatus  1201  transmits, for example, information on a sensing result obtained by performing triangulation to third apparatus  2903  ( 6022 ). 
     Third apparatus  2903  receives this “information on the sensing result obtained by performing triangulation”, and transmits the “information on the sensing result obtained by performing triangulation” to tenth apparatus  5301 . 
     Tenth apparatus  5301  receives this information on the sensing result ( 6002 ). 
     Case where Fourth_i Apparatus of  2904 _ i  Demands Sensing Result: 
     As in  FIG.  60 B , fourth_ 1  apparatus of  2904 _ 1  transmits, for example, information on a sensing result obtained by performing triangulation to third apparatus  2903  ( 6031 ). 
     Third apparatus  2903  receives this “information on the sensing result obtained by performing triangulation”, and transmits the “information on the sensing result obtained by performing triangulation” to tenth apparatus  5301 . 
     Tenth apparatus  5301  receives this information on the sensing result ( 6002 ). 
     Note that,  FIG.  60 B  may not be performed if not necessary. 
     Next, an exemplary embodiment that differs from those in  FIGS.  60 A and  60 B  will be described. 
       FIGS.  61 A and  61 B  illustrate operation examples when first apparatus  1201  and fourth_i apparatus of  2904 _ i  perform sensing based on an instruction by tenth apparatus  5301  in  FIG.  57 ,  58  or  59   . 
     As in  FIG.  61 A , for transmitting information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 , tenth apparatus  5301  in  FIG.  57 ,  58  or  59    transmits information on a request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ) to third apparatus  2903  for first apparatus  1201  ( 6101 ). 
     Third apparatus  2903  receives this information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ), and transmits the information on the request for sensing of “target (object)  1203  or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object)  1203  or second apparatus  1802 ) to first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1 . 
     First apparatus  1201  receives this information, and transmits a response to third apparatus  2903  ( 6121 ). 
     Note that, it is assumed here that first apparatus  1201  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Fourth_ 1  apparatus of  2904 _ 1  receives this information, and transmits a response to third apparatus  2903  ( 6131 ). Note that, it is assumed here that fourth_ 1  apparatus of  2904 _ 1  performs sensing of “target (object  1203 ) or second apparatus  1802 ” (for example, an operation related to detection of the position of target (object  1203 ) or second apparatus  1802 ). 
     Third apparatus  2903  receives the response transmitted by first apparatus  1201  and the response transmitted by fourth_ 1  apparatus of  2904 _ 1 , and transmits these responses to tenth apparatus  5301 . Tenth apparatus  5301  receives these responses ( 6102 ). 
     Then, it is assumed that first apparatus  1201  and fourth_ 1  apparatus of  2904 _ 1  perform the sensing described in Embodiments 4 and 5. 
     Case where First Apparatus Demands Sensing Result: 
     As in  FIG.  61 B , first apparatus  1201  transmits, for example, information on a sensing result obtained by performing triangulation to third apparatus  2903  ( 6122 ). 
     Third apparatus  2903  receives this “information on the sensing result obtained by performing triangulation”, and transmits the “information on the sensing result obtained by performing triangulation” to tenth apparatus  5301 . 
     Tenth apparatus  5301  receives this information on the sensing result ( 6103 ). 
     Case where Fourth_ 1  Apparatus of  2904 _ 1  Demands Sensing Result: 
     As in  FIG.  61 B , fourth_ 1  apparatus of  2904 _ 1  transmits, for example, information on a sensing result obtained by performing triangulation to third apparatus  2903  ( 6132 ). 
     Third apparatus  2903  receives this “information on the sensing result obtained by performing triangulation”, and transmits the “information on the sensing result obtained by performing triangulation” to tenth apparatus  5301 . 
     Tenth apparatus  5301  receives this information on the sensing result ( 6103 ). 
     Note that,  FIG.  61 B  may not be performed if not necessary. 
     By performing as described above, it is possible to realize the distance-based triangulation described in Embodiment 1. Thus, it is possible to obtain the effect of being capable of specifying the position of a target. 
     Further, it is possible to obtain the effect that first apparatus  1201  can transmit information properly by communicating with fourth_ 1  apparatus of  2904 _ 1  via third apparatus  2903 , and further that highly-accurate sensing can be performed by fourth_ 1  apparatus of  2904 _ 1  performing sensing. Note that, this effect is due to the relationship between the third frequency and the fourth frequency. 
     Note that, although  FIGS.  60 A,  60 B,  61 A, and  61 B  have been indicated as examples of the operation flows of the tenth apparatus, the first apparatus, and fourth_ 1  apparatus of  2904 _ 1 , they are merely examples, and the order of operations may be different from the orders indicated in the drawings. 
     (Description of Supplements) 
     Although the embodiments have been described thus far, the embodiments may be combined. Further, the embodiments may also be combined with supplements described below. 
     The signal for sensing herein may be a signal using a multicarrier scheme such as OFDM or may be a signal using a single-carrier scheme. Further, the signal for sensing may also be a tone signal, an impulse signal, a bandlimited impulse signal, or the like. 
     Although position estimation of a target has been performed herein, the shape of the target, the materials that forms the target, the movement velocity of the target or the like may also be estimated. 
     The embodiments are merely exemplary. For example, even when “a modulation scheme, an error correction coding scheme (error correction code, code length, coding rate, and the like to be used), control information, and the like” are exemplified, the present disclosure can be implemented with the same configuration even in a case where other “modulation scheme, error correction coding scheme (error correction code, code length, coding rate, and the like to be used), control information, and the like” are applied. 
     Regarding the modulation scheme, the embodiments and other contents described herein can be implemented even when a modulation scheme other than the modulation scheme described herein is used. For example, amplitude phase shift keying (APSK) (for example, 16APSK, 64APSK, 128APSK, 256APSK, 1024APSK, 4096APSK, and the like), pulse amplitude modulation (PAM) (for example, 4PAM, 8PAM, 16PAM, 64PAM, 128PAM, 256PAM, 1024PAM, 4096PAM, and the like), phase shift keying (PSK) (for example, BPSK, QPSK, 8PSK, 16PSK, 64PSK, 128PSK, 256PSK, 1024PSK, 4096PSK, and the like), quadrature amplitude modulation (QAM) (for example, 4QAM, 8QAM, 16QAM, 64QAM, 128QAM, 256QAM, 1024QAM, 4096QAM, and the like), or the like may be applied, or uniform mapping or non-uniform mapping may be performed in each modulation scheme. 
     Further, the method of mapping 2, 4, 8, 16, 64, 128, 256, 1024, and the like of signal points on an I(in-phase)-Q(quadrature) plane (a modulation scheme including 2, 4, 8, 16, 64, 128, 256, 1024, and the like of signal points) is not limited to the signal point mapping method of the modulation scheme described herein. 
     It can be considered that the device including the first apparatus, the second apparatus, the third apparatus, the fourth_i apparatus, and the tenth apparatus herein is a communication and broadcast device such as a broadcast station, a base station, an access point, a terminal, and a mobile phone, or a device such as a television, a radio, a personal computer, an eNB (eNodeB), a gNB (gNodeB), a repeater, a server, a home electric appliance, a smart phone, a tablet, a vehicle, an automobile, a ship, an airplane, a drone, a satellite, an electric bicycle, an electric bike, an electric kickboard, an electric kick scooter, a bicycle, a bike, a motorcycle, a kickboard, and a kick scooter. 
     Further, although the operations related to the base station have been described herein, the operations of the base station may be the operations of “a communication and broadcast device such as a broadcast station, an access point, a terminal, and a mobile phone, or a device, a communication apparatus or the like such as a television, a radio, a personal computer, an eNB (eNodeB), a gNB (gNodeB), a repeater, a server, a home electric appliance, a smart phone, a tablet, a vehicle, an automobile, a ship, an airplane, a drone, a satellite, an electric bicycle, an electric bike, an electric kickboard, an electric kick scooter, a bicycle, a bike, a motorcycle, a kickboard, and a kick scooter”. 
     Although the operations related to the terminal have been described herein, the operations of the terminal may be the operations of “a communication and broadcast device such as a broadcast station, an access point, a base station, and a mobile phone, or a device, a communication apparatus or the like such as a television, a radio, a personal computer, an eNB (eNodeB), a gNB (gNodeB), a repeater, a server, a home electric appliance, a smart phone, a tablet, a vehicle, an automobile, a ship, an airplane, a drone, a satellite, an electric bicycle, an electric bike, an electric kickboard, an electric kick scooter, a bicycle, a bike, a motorcycle, a kickboard, and a kick scooter”. 
     Further, it is also considered that the transmission apparatus and the reception apparatus in the present disclosure are devices having a sensing function and/or a communication function, and that the devices are configured to be connectable to an apparatus for executing an application of a television, a radio, a personal computer, a mobile phone, or the like, via a certain interface. 
     Note that, the present disclosure is not limited to the embodiments, and can be implemented by various modifications. For example, although the embodiments describe apparatuses, the present disclosure is not limited thereto, and a communication method of the apparatuses can also be implemented as software. 
     For example, a program for executing the communication method and the sensing method that are described above may be stored in a ROM in advance to cause a CPU to operate the program. 
     Further, a program for executing the communication method and the sensing method that are described above may be stored in a computer-readable storage medium, the program stored in the storage medium may be recorded in a RAM of a computer, and the computer may be caused to operate in accordance with the program. 
     Each configuration of the embodiments described above or the like may be realized as an LSI which is typically an integrated circuit that includes an input terminal and an output terminal. The LSIs may be individually formed as chips, or one chip may be formed so as to include the entire configuration or part of the configuration of each embodiment. The LSI here may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on a difference in the degree of integration. However, the technique of implementing an integrated circuit is not limited to the LSI and may be realized by using. a dedicated circuit or a general-purpose processor. An FPGA that can be programmed after the manufacture of the LSI or a reconfigurable processor in which the connections and the settings of circuit cells disposed inside the LSI can be reconfigured may be used. If future integrated circuit technology replaces LSIs as a result of the advancement of semiconductor technology or other derivative technology, the functional blocks could be integrated using the future integrated circuit technology. Biotechnology can also be applied. 
     Note that, the transmission method supported by the apparatuses described herein may be a multicarrier scheme such as OFDM or may be a single-carrier scheme. Further, the base station, the terminal, and the access point may support both a multicarrier scheme and a single-carrier scheme. At this time, there is a plurality of methods that generates a single-carrier-scheme modulated signal, and implementation is possible regardless of which method is used. Examples of the single-carrier scheme include “discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM)”, “trajectory constrained DFT-spread OFDM”, “OFDM based single carrier (SC)”, “single carrier (SC)-frequency division multiple access (FDMA)”, and “guard interval DFT-spread OFDM”. 
     At least one of the field programmable gate array (FPGA) and/or the central processing unit (CPU) may be configured such that all or some of software that needs to realize the communication method and/or the sensing method described herein can be downloaded by radio communication or wired communication. Further, at least one of the FPGA and/or the CPU may also be configured such that all or some of software for updating can be downloaded by radio communication or wired communication. Further, it may also be configured such that the digital signal processing described herein is performed by storing the downloaded software in a storage and operating at least one of the FPGA and/or the CPU based on the stored software. 
     At this time, radio connection or wired connection between a device including at least one of the FPGA and/or the CPU and a communication modem may be established, and the device and the communication modern may realize the communication method and/or the sensing method each described herein. 
     For example, the communication and/or sensing apparatuses of the apparatuses described herein may include at least one of the FPGA and/or the CPU, and may include an interface for obtaining software for operating at least one of the FPGA and/or the CPU from an external source. Further, the communication and/or sensing apparatuses may include a storage for storing software obtained from the external source, and realize the signal processing described herein by operating the FPGA and/or the CPU based on the stored software. 
     When the apparatuses described herein transmit a signal for communication, a data symbol or the like or transmit a signal for sensing, a multiple-input multiple-output (MIMO) transmission scheme for transmitting a plurality of modulated signals from a plurality of antennas may be used or one signal may be transmitted by using one or more antennas. 
     The communication of the apparatuses described herein is performed by, for example, carrier sense multiple access (CSMA), carrier sense multiple access with collision avoidance (CSMA/CA), time division duplex (TDD), time division multiplexing (TDM), frequency division duplex (FDD), or frequency division multiplexing (FDM). The communication between the gNB and the terminal is performed by, for example, TDD, TDM, FDD or FDM. 
     In the embodiments described above, the notation “ . . . processor”, “-er”, “-or”, and “-ar” used for each component may be replaced with another notation such as “ . . . circuitry”, “ . . . device”, “. . . unit” or “ . . . module”. 
     Although the embodiments have been described thus far with reference to the accompanying drawings, the present disclosure is not limited to the given examples. It is apparent that the person skilled in the art could arrive at various changes or modifications within the scope described in the claims. It should be understood that such changes or modifications also belong to the technical scope of the present disclosure. Further, the components in the embodiments may be arbitrarily combined without departing from the spirit of the present disclosure. 
     The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of each embodiment described above can be party or entirely realized by an LSI such as an integrated circuit, and each process described in the each embodiment may be controlled partly or entirely by the same LSI or a combination of LSIs. The LSI may be individually formed as chips, or one chip may be formed so as to include a part or all of the functional blocks. The LSI may include a data input and output coupled thereto. The LSI here may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on a difference in the degree of integration. 
     However, the technique of implementing an integrated circuit is not limited to the LSI and may be realized by using a dedicated circuit, a general-purpose processor, or a special-purpose processor. In addition, a field programmable gate array (FPGA) that can be programmed after the manufacture of the LSI or a reconfigurable processor in which the connections and the settings of circuit cells disposed inside the LSI can be reconfigured may be used. The present disclosure can be realized as digital processing or analogue processing. 
     If future integrated circuit technology replaces LSIs as a result of the advancement of semiconductor technology or other derivative technology, the functional blocks could be integrated using the future integrated circuit technology. Biotechnology can also be applied. 
     The present disclosure can be realized by any kind of apparatus, device or system having a function of communication and/or a function of sensing, which is referred to as a communication apparatus. The communication apparatus may comprise a transceiver and processing/control circuitry. The transceiver may comprise and/or function as a receiver and a transmitter. The transceiver, as the transmitter and receiver, may include a radio frequency (RF) module including amplifiers, RF modulators/demodulators and the like, and one or more antennas. Some non-limiting examples of such a communication apparatus include a phone (e.g., cellular (cell) phone, smart phone), a tablet, a personal computer (PC) (e.g., laptop, desktop, netbook), a camera (e.g., digital still/video camera), a digital player (digital audio/video player), a wearable device (e.g., wearable camera, smart watch, tracking device), a game console, a digital book reader, a telehealth/telemedicine (remote health and medicine) device, and a vehicle providing communication functionality (e.g., automotive, airplane, ship), and various combinations thereof. 
     The communication apparatus and the sensing apparatus are not limited to be portable or movable, and may also include any kind of apparatus, device or system being non-portable or stationary, such as a smart home device (e.g., an appliance, lighting, smart meter, control panel), a vending machine, and any other “things” in a network of an “Internet of Things (IoT)”. 
     The communication may include exchanging data through, for example, a cellular system, a wireless LAN system, a satellite system, etc., and various combinations thereof. 
     The communication apparatus may comprise a device such as a controller or a sensor which is coupled to a communication device performing a function of communication described herein. For example, the communication apparatus may comprise a controller or a sensor that generates control signals or data signals which are used by a communication device performing a communication function of the communication apparatus. 
     The communication apparatus also may include an infrastructure facility, such as a base station, an access point, and any other apparatus, device or system that communicates with or controls apparatuses such as those in the above non-limiting examples. 
     Data whose examples include control information, data, and feedback information that are transmitted by the apparatuses such as the base station and the terminal herein may be include in, for example, a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), a “synchronization signals (SS) block”, a “physical broadcast channel (PBCH) block”, an “SS/PBCH block”, a “physical downlink control channel (PDCCH)”, a “broadcast channel (BCH)”, a “downlink shared channel (DL-SCH)”, a “paging channel (PCH)”, an “uplink shared channel (UL-SCH)”, a “random access channel (RACH)”, a “physical random access channel (PRACH)”, a “physical uplink control channel (PUCCH)”, and the like. 
     The communication of the apparatuses described herein may be performed by, for example, spatial division multiplexing (SDM). The communication between the gNB and the terminal may be performed by, for example, SDM. 
     (Summary of the Present Disclosure) 
     A communication apparatus according to the present disclosure is a communication apparatus including: 
     a transmitter that transmits request information for requesting sensing of a target; 
     a receiver that receives result information indicating a sensing result from a first communication apparatus in which the sensing of the target has been performed in accordance with the request information; and 
     a controller that determines a state of the target based on the sensing result indicated in the result information and a sensing result of sensing of the target that has been performed in the communication apparatus. 
     In the communication apparatus according to the present disclosure, the controller may determine at least one of a position of the target, presence or absence of the target, an outer shape of the target, and/or movement of the target. 
     In the communication apparatus according to the present disclosure, the receiver may receive a response to the request information from the first communication apparatus and then receive the result information. 
     In the communication apparatus according to the present disclosure, the transmitter may transmit a determination result of a position of the target to the first communication apparatus. 
     In the communication apparatus according to the present disclosure, the receiver may receive capability information on sensing capability from the first communication apparatus. 
     In the communication apparatus according to the present disclosure, the controller may perform the sensing of the target by using an antenna port different from an antenna port that is used in data communication. 
     In the communication apparatus according to the present disclosure, the transmitter may transmit the request information to the first communication apparatus via a second communication apparatus, and the receiver may receive the result information via the second communication apparatus. 
     In the communication apparatus according to the present disclosure, a frequency used in communication with the first communication apparatus may be higher than a frequency used in communication with the second communication apparatus. 
     In the communication apparatus according to the present disclosure, the transmitter may transmit, by using beamforming, a signal used in the sensing, the receiver may receive directivity information on directivity of the beamforming from the first communication apparatus, and the controller may determine a direction of the target based on the directivity information. 
     A sensing method according to the present disclosure is a sensing method in a communication apparatus and includes: transmitting request information for requesting sensing of a target; receiving result information indicating a sensing result from a first communication apparatus in which the sensing of the target has been performed in accordance with the request information; and determining a state of the target based on the sensing result indicated in the result information and a sensing result of sensing of the target that has been performed in the communication apparatus. 
     The disclosure of Japanese Patent Application No. 2020-077688, filed on Apr. 24, 2020, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is useful for sensing of an object in a communication system. 
     REFERENCE SIGNS LIST 
     
         
         X 100 , X 200 , X 300  Apparatus 
         X 101 , X 201 , X 301  Transmission apparatus 
         X 103 _ 1  to X 103 _M, X 104 _ 1  to X 104 _M Antenna 
         X 106 , X 206 , X 306  Reception apparatus 
         X 108 , X 208 , X 308  Estimator 
           151  Terminal 
           152  Base station 
           1101  First apparatus 
           1102 ,  1802  Second apparatus 
           2903  Third apparatus 
           2904  Fourth apparatus 
           5301  Tenth apparatus 
           1202  Base station 
           1103 ,  1203  Target