Patent Publication Number: US-2020296743-A1

Title: Base station device, terminal device, and transmission method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/295,404, filed Mar. 7, 2019, now pending, which is a continuation of International Application No. PCT/JP2016/078923, filed on Sep. 29, 2016, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The embodiments discussed herein are related to a base station device, a terminal device, and a transmission method. 
     BACKGROUND 
     In recent years, in the  3   rd  Generation Partnership Project (3GPP) that is the standards organization related to radio communication systems, studies have been conducted on the fifth generation mobile communication system (5G). In the fifth generation mobile communication systems, services conforming to eMBB (enhanced mobile broadband), mMTC (massive machine type communications), URLLC (Ultra Reliability and Low Latency Communications), and the like are going to be started. 
     For example, eMBB responds to a service of transmission of large-volume data, such as moving image data. In contrast, URLLC responds to a service in which high-reliable and low-latency communication is needed, such as automatic operations or telesurgery. In order to implement these services, discussions are actively conducted on how to set communication parameters, such as Transmission Time Interval (TTI), that is the duration of time represented by, for example, flames or subframes. 
     Specifically, for example, when eMBB data and URLLC data are transmitted by using the same frequency band, it is conceivable to multiplex the eMBB data and the URLLC data by using time-division multiplexing or frequency-division multiplexing. At this time, because a low latency is needed for the URLLC data, a large reduction in TTI of URLLC compared to TTI of eMBB is studied. 
     Non-Patent Document 1: LG Electronics, “Handling URLLC in new RAT”, 3GPP TSG RAN WG 1  Meeting #86, R1-166886, August 2016 
     Non-Patent Document 2: NTT DOCOMO, INC., “On co-existence of eMBB and URLLC”, 3GPP TSG RAN WG 1  Meeting #86, R1-167391, August 2016 
     Non-Patent Document 3: Samsung, “Discussion on URLLC support in NR”, 3GPP TSG RAN WG1 Meeting #86, R1-166759, August 2016 
     However, when eMBB data and URLLC data are multiplexed in the same frequency band, there is a problem in that the efficiency of using time and frequency resources is reduced. Specifically, because URLLC data is transmitted to control, for example, automatic operations, URLLC data to be transmitted is not always present and, accordingly, intermittent transmission occurs in URLLC data. Nevertheless, if time and frequency resources are fixedly allocated to URLLC data, the resources allocated to the URLLC data are wasted when URLLC data to be transmitted is not present. 
     SUMMARY 
     According to an aspect of an embodiment, a base station device includes: a processor circuitry configured to generate an indication signal; and a transmitter configured to transmit the indication signal to a terminal device. The indication signal indicates that there is no transmission of first data to be scheduled in a resource, and the resource may be assigned second data to be transmitted at low latency. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a configuration of a radio communication system according to a first embodiment; 
         FIG. 2  is a block diagram illustrating a configuration of a base station device according to the first embodiment; 
         FIG. 3  is a diagram illustrating a specific example of resource allocation according to the first embodiment; 
         FIG. 4  is a flowchart illustrating a transmission process according to the first embodiment; 
         FIG. 5  is a block diagram illustrating a configuration of a user terminal device according to the first embodiment; 
         FIG. 6  is a flowchart illustrating a reception process according to the first embodiment; 
         FIG. 7  is a block diagram illustrating a configuration of another user terminal device according to the first embodiment; 
         FIG. 8  is a flowchart illustrating another reception process according to the first embodiment; 
         FIG. 9  is a diagram illustrating another specific example of resource allocation according to the first embodiment; 
         FIG. 10  is a diagram illustrating a specific example of resource allocation according to a second embodiment; 
         FIG. 11  is a block diagram illustrating a configuration of a user terminal device according to the second embodiment; and 
         FIG. 12  is a flowchart illustrating a reception process according to the second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of the present invention will be explained with reference to accompanying drawings. Furthermore, the present invention is not limited to the embodiments. 
     [a] First Embodiment 
       FIG. 1  is a diagram illustrating a configuration of a radio communication system according to a first embodiment. The radio communication system illustrated in  FIG. 1  includes a base station device  100  and a plurality of user terminal devices  200 . 
     The base station device  100  transmits signals including, for example, eMBB data and URLLC data to the user terminal devices  200 . Namely, the base station device  100  allocates resources constituted of time and frequency to the eMBB data and the URLLC data addressed to each of the plurality of user terminal devices  200  and then generates a transmission signal. 
     At this time, the base station device  100  provides an area (hereinafter, referred to as an “URLLC area”) that is temporarily reserved, as an area in which URLLC data is to be arranged, in a resource area to which eMBB data is allocated and then allocates, if URLLC data to be transmitted is present, a resource of the URLLC area to the subject URLLC data. Then, the base station device  100  arranges, in the URLLC area, an indication signal indicating whether the resource of the URLLC area has been allocated to the URLLC data. 
     Thus, if the URLLC data to be transmitted is present, the resource of the URLLC area is allocated to the URLLC data and this state is notified by the indication signal. Furthermore, if the URLLC data to be transmitted is not present, the resource of the URLLC area is allocated to the eMBB data and information indicating that the URLLC data is not transmitted is notified by the indication signal. 
     Each of the user terminal devices  200  receives a signal including eMBB data and URLLC data that are transmitted from the base station device  100 . Specifically, the user terminal devices  200  are classified into devices that use a service related to eMBB, devices that use a service related to URLLC, and devices that use services related to both eMBB and URLLC. Each of the user terminal devices  200  that uses the service related to eMBB specifies, based on a control signal and an indication signal included in a reception signal, eMBB data addressed to the own device and then demodulates the eMBB data. 
     Furthermore, each of the user terminal devices  200  that uses a service related to URLLC determines, based on the indication signal included in the reception signal, whether URLLC data is included in the reception signal and then demodulates, based on the control signal if the URLLC data is included, the URLLC data addressed to the own device. Furthermore, each of the user terminal devices  200  that uses a service related to both eMBB and URLLC demodulates eMBB data and then demodulates URLLC data in a similar manner described above. 
       FIG. 2  is a block diagram illustrating a configuration of the base station device  100  according to the first embodiment. The base station device  100  illustrated in  FIG. 2  includes a processor  100   a , a memory  100   b , and a radio transmission unit  100   c.    
     The processor  100   a  includes, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or a digital signal processor (DSP), or the like and performs overall control of the base station device  100 . Specifically, the processor  100   a  includes a scheduler unit  110 , an eMBB data generating unit  120 , an URLLC data generating unit  130 , an indication signal generating unit  140 , a control signal generating unit  150 , a mapping unit  160 , an inverse Fast Fourier transformation (IFFT) unit  170 , and a cyclic prefix (CP) attaching unit  180 . 
     The scheduler unit  110  performs scheduling that allocates resources to eMBB data and URLLC data addressed to the plurality of user terminal devices  200 . Specifically, the scheduler unit  110  estimates, for example, a channel state between each of the plurality of user terminal devices  200  and performs eMBB scheduling that decides, in accordance with the channel state, a resource to be allocated to eMBB data that is addressed to each of the user terminal devices  200 . Furthermore, the scheduler unit  110  determines whether URLLC data addressed to one of the user terminal devices  200  is generated and performs, if the URLLC data has been generated, URLLC scheduling that decides a resource to be allocated to the URLLC data. 
     The scheduler unit  110  arranges, at the time of URLLC scheduling, URLLC data in an URLLC area that is provided in the resource area to which the eMBB data is allocated. Namely, the resource for a transmission signal has an eMBB control channel area in which an eMBB control signal is arranged and an eMBB data area in which eMBB data is arranged; however, an URLLC area that is temporarily reserved as an area in which the URLLC data is to be arranged is provided in the eMBB data area. Thus, if URLLC data to be transmitted is generated, the scheduler unit  110  allocates a resource to be used for the URLLC area to the URLLC data. 
     The eMBB data generating unit  120  generates, in accordance with eMBB scheduling performed by the scheduler unit  110 , eMBB data to be addressed to each of the user terminal devices  200 . Namely, the eMBB data generating unit  120  encodes and modulates the eMBB data addressed to each of the user terminal devices  200 . 
     The URLLC data generating unit  130  generates, in accordance with URLLC scheduling performed by the scheduler unit  110 , URLLC data addressed to each of the user terminal devices  200 . Namely, the URLLC data generating unit  130  encodes and modulates the URLLC data addressed to each of the user terminal devices  200 . 
     The indication signal generating unit  140  generates, in accordance with the result of determination whether URLLC scheduling has been performed by the scheduler unit  110 , an indication signal indicating whether URLLC data is present. Namely, if URLLC data to be transmitted is not present and if the URLLC data is not arranged in an URLLC area, the indication signal generating unit  140  generates an indication signal indicating that URLLC data is not present. Furthermore, if URLLC data to be transmitted is present and if the URLLC data is arranged in an URLLC area, the indication signal generating unit  140  indicates that the URLLC data to be transmitted is present and then generates an indication signal that specifies a resource to be allocated to the URLLC data that is addressed to each of the user terminal devices  200 . Namely, the indication signal generating unit  140  generates an indication signal that includes 1 bit indicating whether URLLC data is present and N bits (N is an integer equal to or greater than two) that specifies, in a case where URLLC data is present, a resource to be allocated to the subject URLLC data. 
     The control signal generating unit  150  generates a control signal of each of eMBB and URLLC in accordance with eMBB scheduling and URLLC scheduling performed by the scheduler unit  110 . Specifically, the control signal generating unit  150  generates an eMBB control signal including information for specifying a resource to be allocated to eMBB data addressed to each of the user terminal devices  200  and information indicating a coding rate of eMBB data, a modulation scheme of eMBB data, transmission power of eMBB data, and the like. Furthermore, if URLLC data is arranged in an URLLC area, the control signal generating unit  150  generates an URLLC control signal including information indicating a coding rate, a modulation scheme of URLLC data, transmission power of URLLC data, and the like. 
     The mapping unit  160  maps eMBB data, URLLC data, an indication signal, and a control signal and generates a transmission signal. Namely, the mapping unit  160  arranges the eMBB data, the URLLC data, the indication signal, and the control signal in the resources in accordance with scheduling. 
     Specifically, the mapping unit  160  generates a transmission signal in which the resources illustrated in, for example,  FIG. 3  have been allocated.  FIG. 3  illustrates a specific example of allocating resources having, for example, a frequency bandwidth corresponding to the number of predetermined subcarriers and duration of time corresponding to a single TTI. As illustrated in  FIG. 3 , the resource of this TTI includes an eMBB control channel area  301  and an eMBB data area  302 . Then, URLLC areas  311  to  313  that are temporarily reserved as areas in each of which URLLC data is to be arranged is provided in the eMBB data area  302 . In the URLLC areas  311  to  313 , indication signals  321  to  323 , an URLLC control signal  331  and URLLC data  332  are mapped. 
     The mapping unit  160  maps the eMBB control signal generated by the control signal generating unit  150  to the eMBB control channel area  301  and maps the eMBB data generated by the eMBB data generating unit  120  to the eMBB data area  302 . Furthermore, if URLLC scheduling has been performed, the mapping unit  160  maps both of the URLLC control signal  331  generated by the control signal generating unit  150  and the URLLC data  332  generated by the URLLC data generating unit  130  onto the URLLC areas  311  to  313 . Furthermore, the mapping unit  160  maps the indication signals  321  to  323  generated by the indication signal generating unit  140  onto the URLLC areas  311  to  313 , respectively. 
     At this time, as illustrated in  FIG. 3 , because the URLLC data has been arranged in the URLLC areas  311  and  312 , each of the indication signals  321  and  322  includes 1 bit indicating that URLLC data is present and N bits specifying URLLC data addressed to each of the user terminal devices  200 . Namely, for example, because three pieces of URLLC data addressed to the user terminal devices  200  of UEs # 1  to # 3  are arranged in the URLLC area  311 , the indication signal  321  includes N bits that specify the frequency bands of the corresponding pieces of URLLC data addressed to the UEs # 1  to # 3 . In contrast, because URLLC data is not arranged in the URLLC area  313 , the indication signal  323  includes only 1 bit indicating that URLLC data is not present. 
     Furthermore, in the URLLC area  312 , because URLLC data is mapped to a part of the URLLC area  312 , eMBB data is mapped in the rest of the area. Similarly, in the URLLC area  313 , because URLLC data is not mapped, the eMBB data is mapped in the entire of the URLLC area  313 . In this way, if URLLC data to be transmitted is not present, because eMBB data is mapped to the URLLC areas  311  to  313 , it is possible to effectively use the resources. In particular, because eMBB data is arranged in free areas in the URLLC areas  311  to  313 , it is possible to allocate the maximum amount of resources to eMBB data and thus it is possible to increase the capacity based on eMBB. 
     A description will be given here by referring back to  FIG. 2 . The IFFT unit  170  performs inverse Fast Fourier transformation on the transmission signal generated by the mapping unit  160  and generates a transmission signal in time domain. Then, the IFFT unit  170  outputs the transmission signal to the CP attaching unit  180 . 
     The CP attaching unit  180  attaches, in units of symbols, CP to the transmission signal output from the IFFT unit  170 . Then, the CP attaching unit  180  outputs, to the radio transmission unit  100   c , the transmission signal to which the CP has been attached. 
     The memory  100   b  includes, for example, a random access memory (RAM), a read only memory (ROM), or the like and stores various kinds of information when a process is performed by the processor  100   a.    
     The radio transmission unit  100   c  performs, on the transmission signal output from the CP attaching unit  180 , a radio transmission process, such as digital/analog (D/A) conversion and up-conversion. Then, the radio transmission unit  100   c  transmits the transmission signal via an antenna. 
     In the following, a transmission process performed by the base station device  100  having configuration described above will be described with reference to the flowchart illustrated in  FIG. 4 . 
     First, the scheduler unit  110  performs eMBB scheduling in which the resource to be allocated to the eMBB data addressed to each of the user terminal devices  200 , a coding rate, and a modulation scheme are decided (Step S 101 ). The eMBB scheduling mentioned here is performed based on, for example, a channel state of a downlink reported from each of the user terminal devices  200 . In eMBB scheduling, pieces of eMBB data addressed to each of the user terminal devices  200  are arranged in the eMBB data area in each TTI. 
     Furthermore, it is determined, by the scheduler unit  110 , whether URLLC data to be addressed to one of the user terminal devices  200  has been generated (Step S 102 ). Based on this determination result, if URLLC data to be transmitted is generated (Yes at Step S 102 ), the URLLC scheduling for deciding a resource to be allocated to the URLLC data, a coding rate, and a modulation scheme is performed by the scheduler unit  110  (Step S 103 ). The URLLC scheduling is performed based on, for example, a channel state of a downlink reported from each of the user terminal devices  200 . In URLLC scheduling, pieces of URLLC data addressed to the corresponding user terminal devices  200  are arranged in the URLLC areas provided in the eMBB data area in each TTI. 
     Then, the result of scheduling is notified to the eMBB data generating unit  120 , the URLLC data generating unit  130 , the indication signal generating unit  140 , and the control signal generating unit  150  and then pieces of URLLC data to be arranged in the URLLC areas are generated by the URLLC data generating unit  130  (Step S 104 ). Namely, URLLC data is encoded and modulated by the URLLC data generating unit  130  by using the coding rate and the modulation scheme decided by the URLLC scheduling. Furthermore, an indication signal that indicates that URLLC data is present and that specifies the resource of the URLLC area that has been allocated to the URLLC data that is addressed to each of the user terminal devices  200  is generated by the indication signal generating unit  140  (Step S 105 ). 
     In contrast, based on the result of determination obtained at Step S 102 , if URLLC data to be transmitted is not generated (No at Step S 102 ), the result of the eMBB scheduling is notified to the eMBB data generating unit  120 , the indication signal generating unit  140 , and the control signal generating unit  150 . Then, an indication signal indicating that URLLC data is not present is generated by the indication signal generating unit  140  (Step S 106 ). 
     Furthermore, regardless whether URLLC data is present, eMBB data to be arranged in the eMBB data area is generated by the eMBB data generating unit  120  (Step S 107 ). Namely, eMBB data is encoded and modulated by the eMBB data generating unit  120  by using the coding rate and the modulation scheme decided by the eMBB scheduling. 
     Furthermore, if URLLC data is arranged in an URLLC area, transmission of eMBB data that was scheduled to be arranged in this area may also be stopped. Furthermore, it is possible to orthogonalize URLLC data and eMBB data by using different codes or sequences (for example, Zadoff-Chu sequence) and arrange the URLLC data and the eMBB data in the same area. When arranging the URLLC data and the eMBB data in the same area, these pieces of data interfere with each other; however, it is possible to reduce interference by using a technology, such as minimum mean square error-interference rejection combining (MMSE-IRC), symbol level interference cancellation (SLIC), and interference measurement (interference aware detection). 
     If eMBB data has been generated, the resource that is located in the eMBB data area allocated to the eMBB data addressed to each of the user terminal devices  200  is specified by the control signal generating unit  150  and a control signal that notifies of the coding rate of the eMBB data, the modulation scheme of the eMBB data, the transmission power of the eMBB data, and the like is generated by the control signal generating unit  150 . Furthermore, if URLLC data has been generated, a control signal that notifies of the coding rate of the URLLC data, the modulation scheme of the URLLC data, the transmission power of the URLLC data, and the like is generated by the control signal generating unit  150 . 
     Then, the eMBB data, the URLLC data, the indication signal, and the control signal are mapped to each of the areas in TTI by the mapping unit  160  (Step S 108 ). Namely, as illustrated in  FIG. 3 , the eMBB control signal is mapped to the eMBB control channel area  301  and the eMBB data is mapped to the eMBB data area  302 . Furthermore, if URLLC data is generated, the URLLC control signal and the URLLC data are mapped to the URLLC areas  311  to  313 . Then, an indication signal indicating whether URLLC data is present is mapped to each of the URLLC areas  311  to  313 . Consequently, a transmission signal is generated. 
     The transmission signal is subjected to inverse Fast Fourier transformation by the IFFT unit  170  (Step S 109 ) and transformed to a transmission signal in time domain. Then, a CP is attached, in units of symbols, to the transmission signal by the CP attaching unit  180  (Step S 110 ) and a radio transmission process is performed on the transmission signal by the radio transmission unit  100   c  (Step S 111 ). Thereafter, the transmission signal is transmitted to the user terminal device  200  via the antenna (Step S 112 ). 
     As described above, an URLLC area that is used to arrange URLLC data is provided in the eMBB; if URLLC data is present, the URLLC data is arranged in the URLLC area; and if URLLC data is not present, eMBB data is arranged in the URLLC area. Then, an indication signal indicating whether the URLLC data has been arranged in the URLLC area is arranged in each of the URLLC areas. Consequently, if URLLC data is generated, it is possible to transmit the URLLC data in low latency, whereas, if the URLLC data is not generated, it is possible to use the resource of the URLLC area in order to transmit the eMBB data. As the result, regardless whether URLLC data is present, it is possible to prevent the resources from being wasted and thus it is possible to efficiently use the resources. 
     In the following, a configuration of the user terminal device  200  will be described.  FIG. 5  is a block diagram illustrating a configuration of the user terminal device  200  according to the first embodiment. The user terminal device  200  illustrated in  FIG. 5  is a user terminal device that uses a service related to eMBB and includes a radio receiving unit  200   a , a processor  200   b , and a memory  200   c.    
     The radio receiving unit  200   a  receives a signal via an antenna and performs, on a reception signal, a radio reception process, such as down-conversion, and analog/digital (A/D) conversion. Then, the radio receiving unit  200   a  outputs the reception signal to the processor  200   b.    
     The processor  200   b  includes, for example, a CPU, an FPGA, a DSP, or the like and performs overall control of the user terminal device  200 . Specifically, the processor  200   b  includes a CP removing unit  210 , a fast Fourier transformation (FFT) unit  220 , an indication signal demodulating unit  230 , a control signal demodulating unit  240 , and an eMBB data demodulating unit  250 . 
     The CP removing unit  210  removes a CP attached, in units of symbols, to a reception signal. Then, the CP removing unit  210  outputs, to the FFT unit  220 , a reception signal from which the CP has been removed. 
     The FFT unit  220  performs fast Fourier transformation on the reception signal output form the CP removing unit  210  and transforms the signal to a reception signal in frequency domain. Then, the FFT unit  220  outputs the reception signal to the indication signal demodulating unit  230 , the control signal demodulating unit  240 , and the eMBB data demodulating unit  250 . 
     The indication signal demodulating unit  230  demodulates the indication signals arranged in the URLLC area in the reception signal. Namely, because the positions of the indication signals in the URLLC area and the URLLC area are already known, the indication signal demodulating unit  230  demodulates the indication signal in each of the URLLC areas. Consequently, the indication signal demodulating unit  230  grasps whether URLLC data is included in each of the URLLC areas. Furthermore, if URLLC data is included in an URLLC area, the indication signal demodulating unit  230  specifies, based on the indication signal, the resource allocated to the URLLC data. 
     The control signal demodulating unit  240  demodulates the control signal arranged in the eMBB control channel area in the reception signal. Namely, the control signal demodulating unit  240  demodulates the eMBB control signal and acquires information on the resource allocated to the eMBB data that is addressed to the own device and information on the coding rate of the eMBB data, the modulation scheme of the eMBB data, and the like. 
     The eMBB data demodulating unit  250  demodulates the eMBB data arranged in the eMBB data area in the reception signal. At this time, the eMBB data demodulating unit  250  excludes, from the eMBB data area based on the demodulation result of the indication signal, the area in which the URLLC data has been arranged and specifies, from the eMBB data area in which the URLLC data has been excluded and based on the demodulation result of the control signal, the resource of the eMBB data that is addressed to the own device. Then, the eMBB data demodulating unit  250  demodulates the eMBB data addressed to the own device based on the coding rate, the modulation scheme, and the like indicated by the control signal. Furthermore, if the eMBB data and the URLLC data are orthogonalized by using different codes or sequences, the eMBB data demodulating unit  250  does not need to exclude, from the eMBB data area, the area in which the URLLC data has been arranged. This is because that, if the eMBB data and the URLLC data are orthogonalized by codes or sequences, eMBB data is multiplexed, by using another code or sequence, in the time domain and the frequency domain in which the URLLC data is arranged. 
     In the following, a reception process performed by the user terminal device  200  according to eMBB configured described above will be described with reference to the flowchart illustrated in  FIG. 6 . 
     The signal from the base station device  100  is received via the antenna (Step S 201 ) and a radio reception process is performed on the reception signal by the radio receiving unit  200   a  (Step S 202 ). Then, the CP attached to the reception signal in units of symbols is removed by the CP removing unit  210  (Step S 203 ) the reception signal is subjected to fast Fourier transformation by the FFT unit  220  (Step S 204 ), thereby a reception signal in frequency domain is obtained. 
     Because an URLLC area is provided in an eMBB data area in a reception signal and the resource of the URLLC area is already known, the indication signal arranged in the URLLC area is demodulated by the indication signal demodulating unit  230  (Step S 205 ). Consequently, it is determined whether URLLC data is included in the URLLC area and, if the URLLC data is included, the position of the URLLC data in the URLLC area is specified. In other words, the area that is except for the resource allocated to the URLLC data and in which the eMBB data is actually arranged is specified in the eMBB data area. 
     Furthermore, the control signal arranged in the eMBB control channel area in the reception signal is demodulated by the control signal demodulating unit  240  (Step S 206 ); the resource allocated to the eMBB data addressed to the own devices is specified; and the coding rate of the eMBB data, the modulation scheme of the eMBB data, and the like are specified. Consequently, the eMBB data addressed to the own device is acquired from the reception signal and is demodulated by the eMBB data demodulating unit  250  (Step S 207 ). At this time, based on the demodulation result of the indication signal, the eMBB data addressed to the own device may also be acquired from the area in which the resource allocated to the URLLC data has been removed. Furthermore, if the URLLC data and the eMBB data are orthogonalized by using different codes or sequences, the eMBB data addressed to the own device may also be acquired from the entire eMBB data area including the resource that has been allocated to the URLLC data. 
       FIG. 7  is a block diagram illustrating a configuration of the other user terminal device  200  according to the first embodiment. In  FIG. 7 , components having the same configuration as those illustrated in  FIG. 5  are assigned the same reference numerals and descriptions thereof in detail will be omitted. The user terminal device  200  illustrated in  FIG. 7  is a user terminal device that uses a service related to URLLC and includes, similarly to the user terminal device  200  illustrated in  FIG. 5 , the radio receiving unit  200   a , the processor  200   b , and the memory  200   c . However, the processor  200   b  in the user terminal device  200  illustrated in  FIG. 7  includes, instead of the eMBB data demodulating unit  250  illustrated in  FIG. 5 , an URLLC data demodulating unit  260 . 
     If the URLLC data demodulating unit  260  determines that, based on the demodulation result of the indication signal, the URLLC data addressed to the own device is included in the reception signal, the URLLC data demodulating unit  260  demodulates the URLLC data that is addressed to the own device and that is arranged in the URLLC area in the reception signal. At this time, the URLLC data demodulating unit  260  specifies, from the URLLC area based on the demodulation result of the indication signal, the resource for the URLLC data addressed to the own device. Then, the URLLC data demodulating unit  260  demodulates the URLLC data addressed to the own device based on the coding rate, the modulation scheme, and the like indicated by the URLLC control signal that is demodulated by the control signal demodulating unit  240 . 
     In the following, a reception process performed by the user terminal device  200  according to URLLC configured described above will be described with reference to the flowchart illustrated in  FIG. 8 . In  FIG. 8 , the same processes as those illustrated in  FIG. 6  are assigned the same reference numerals and descriptions thereof in detail will be omitted. 
     Regarding the signal transmitted from the base station device  100 , a reception signal in the frequency domain is obtained from an antenna via the radio receiving unit  200   a , the CP removing unit  210 , and the FFT unit  220  (Steps S 201  to S 204 ). Then, the indication signal arranged in the URLLC area in the reception signal is demodulated by the indication signal demodulating unit  230  (Step S 205 ) and it is determined whether the URLLC data is included in the URLLC area (Step S 301 ). 
     If the URLLC data is not included in the URLLC area (No at Step S 301 ), the process is ended because the URLLC data addressed to the own device is not present. In contrast, if the URLLC data is included in the URLLC area (Yes at Step S 301 ), the URLLC control signal is demodulated by the control signal demodulating unit  240  (Step S 302 ). Namely, because the resources allocated to the control signal and the URLLC data addressed to the own device are specified based on the demodulation result of the indication signal, the URLLC control signal addressed to the own device is demodulated by the control signal demodulating unit  240 . Consequently, the coding rate, the modulation scheme, or the like of the URLLC data addressed to the own device are specified. 
     Furthermore, the URLLC data addressed to the own device is acquired, by the URLLC data demodulating unit  260  based on the demodulation result of the indication signal, from the reception signal and the URLLC data is demodulated based on the demodulation result of the control signal (Step S 303 ). 
     As described above, according to the embodiment, the URLLC area that is temporarily reserved as an area in which the URLLC data is arranged is provided in the eMBB data area and, if URLLC data is generated, the URLLC data is transmitted by using the resource of the URLLC area. Furthermore, an indication signal indicating whether the URLLC data is present is arranged in the URLLC area. Consequently, if URLLC data is generated, it is possible to promptly transmit the URLLC data without any delay and, if URLLC data is not generated, it is possible to transmit the eMBB data by using the resource of the URLLC area. Furthermore, the user terminal device on the reception side can grasp whether the URLLC data is present based on the indication signal and thus reliably acquire the URLLC data to be addressed to the own device from the reception signal. As the result, it is possible to efficiently use the resources while maintaining high reliability and low latency of the URLLC data. 
     Furthermore, in the first embodiment, the user terminal devices  200  related to eMBB and the user terminal devices  200  related to URLLC are separately described; however, the single user terminal device  200  may also demodulate both of the eMBB data and the URLLC data. In this case, the processor  200   b  in the user terminal device  200  includes both of the eMBB data demodulating unit  250  illustrated in  FIG. 5  and the URLLC data demodulating unit  260  illustrated in  FIG. 7 . 
     Furthermore, in the first embodiment, the URLLC area is provided in the eMBB data area; however, the entire eMBB data area may also be the URLLC area. Namely, for example, as illustrated in  FIG. 9 , a single TTI is divided into a plurality of short TTIs (hereinafter, referred to as a “short TTI”) and all of the short TTIs except for the short TTI that includes the eMBB control channel may also be used as URLLC areas  341 . 
     Furthermore, as illustrated in  FIG. 9 , an indication signal  342  arranged in each of the URLLC areas  341  may also be a 1-bit signal indicating whether the URLLC data is included in each of the URLLC areas  341 . In this case, the information that specifies the resource allocated to the URLLC data  332  addressed to each of the user terminal devices  200  is included in the URLLC control signal  331 . 
     [b] Second Embodiment 
     The characteristic of a second embodiment is that, if URLLC data is included in a reception signal, a user terminal device estimates transmission power for each subcarrier and specifies, based on the transmission power, a subcarrier including the URLLC data. 
     The configuration of the radio communication system and the base station device  100  according to the second embodiment is the same as that of the first embodiment ( FIGS. 1 and 2 ); therefore, descriptions thereof will be omitted. However, the base station device  100  controls transmission power of the eMBB data and the URLLC data and transmits the URLLC data, in which high reliability is requested, by using transmission power that is greater than that of the eMBB data. Specifically, when the mapping unit  160  arranges URLLC data in an URLLC area, the mapping unit  160  sets the transmission power of the subcarrier in which the URLLC data is to be arranged larger than the transmission power of the subcarrier in which the eMBB data is to be arranged. Thus, if the URLLC data is arranged in an URLLC area and is transmitted, the transmission power of the subcarrier in which URLLC data is arranged is larger than the transmission power of the subcarrier in which the eMBB data is arranged. 
       FIG. 10  is a diagram illustrating a specific example of resource allocation according to the second embodiment. The resource illustrated in  FIG. 10  has subcarriers  351  to  353  and an eMBB control channel area is provided at the top of the resource. Furthermore, the areas other than the eMBB control channel area are eMBB data areas; however, in the eMBB data area, URLLC areas  361  to  363  temporarily reserved as the areas for arranging URLLC data is provided. In the URLLC areas  361  to  363 , indication signals  371  to  373  are mapped and the URLLC control signal and URLLC data are mapped onto the subcarriers  351  to  353  as units. 
     Specifically, for example, in the URLLC area  361 , the URLLC data addressed to the user terminal device UE # 2  is mapped onto a subcarrier  352  and the URLLC data addressed to the user terminal device UE # 1  is mapped onto the subcarrier  353 . Furthermore, for example, in the URLLC area  362 , the URLLC data addressed to the user terminal device UE # 3  is mapped onto the subcarrier  353 . 
     Here, because the URLLC data is data in which high reliability is requested, the transmission power of the URLLC data is larger than that of the eMBB data. Thus, for example, in the URLLC area  361 , the transmission power of the subcarriers  352  and  353  in each of which the URLLC data is mapped is larger than the transmission power of the subcarrier  351  in which the eMBB data is mapped. Similarly, for example, in the URLLC area  362 , the transmission power of the subcarrier  353  in which the URLLC data is mapped is larger than the transmission power of the subcarriers  351  and  352  in each of which the eMBB data is mapped. 
     Namely, in each of the URLLC areas  361  to  363 , based on the transmission power for each subcarrier, it is possible to determine which one of the pieces of the eMBB data and URLLC data is mapped in the subcarriers  351  to  353 . Therefore, each of the indication signals  371  to  373  is a 1-bit signal indicating whether the URLLC data is included in each of the URLLC areas  361  to  363  and thus information for specifying a subcarrier in which the URLLC data is to be mapped is not included in the indication signals  371  to  373 . 
       FIG. 11  is a block diagram illustrating a configuration of the user terminal device  200  according to the second embodiment.  FIG. 11 , components having the same configuration as those illustrated in  FIG. 5  are assigned the same reference numerals and descriptions thereof in detail will be omitted. The user terminal device  200  illustrated in  FIG. 11  is a user terminal device that uses a service related to eMBB and includes, similarly to the user terminal device  200  illustrated in  FIG. 5 , the radio receiving unit  200   a , the processor  200   b , and the memory  200   c . However, the processor  200   b  in the user terminal device  200  illustrated in  FIG. 11  has a configuration in which, instead of the indication signal demodulating unit  230  and the eMBB data demodulating unit  250  illustrated in  FIG. 5 , an indication signal demodulating unit  410  and an eMBB data demodulating unit  440  are included and a reception power measuring unit  420  and a transmission power estimating unit  430  are added. 
     The indication signal demodulating unit  410  demodulates the indication signal arranged in an URLLC area in a reception signal. Namely, because the position of the indication signal in each of the URLLC area and the URLLC area is already known, the indication signal demodulating unit  410  demodulates the indication signal in each of the URLLC areas. Consequently, the indication signal demodulating unit  410  grasps whether the URLLC data is included in each of the URLLC areas. Then, the URLLC data is included in the URLLC area, the indication signal demodulating unit  410  notifies the reception power measuring unit  420  and the eMBB data demodulating unit  440  of this state. 
     If the reception power measuring unit  420  receives the notification indicating that the URLLC data is included in the URLLC area from the indication signal demodulating unit  410 , the reception power measuring unit  420  measures the reception power for each subcarrier in the URLLC area in the reception signal. 
     The transmission power estimating unit  430  estimates the transmission power for each subcarrier based on the reception power for each subcarrier measured by the reception power measuring unit  420 . Specifically, the transmission power estimating unit  430  estimates, for example, the propagation loss between the base station device  100  and the user terminal device  200  by using the reference signal and estimates the transmission power at the base station device  100  based on the reception power and the propagation loss. 
     The eMBB data demodulating unit  440  demodulates the eMBB data arranged in the eMBB data area in the reception signal. At this time, if the eMBB data demodulating unit  440  receives a notification indicating that the URLLC data is included in the URLLC area from the indication signal demodulating unit  410 , the eMBB data demodulating unit  440  specifies, based on the transmission power for each subcarrier, the subcarrier in which the eMBB data has been arranged. Namely, the eMBB data demodulating unit  440  compares the transmission power for each subcarrier estimated by the transmission power estimating unit  430  with a predetermined threshold. Then, the eMBB data demodulating unit  440  specifies that the URLLC data has been arranged in the subcarriers in each of which the transmission power is equal to or greater than the predetermined threshold and specifies that the eMBB data has been arranged in the subcarriers in each of which the transmission power is less than the predetermined threshold. Consequently, the eMBB data demodulation unit  440  specifies the resource in which the eMBB data is arranged in the entire eMBB data area that includes the URLLC area, and demodulates the eMBB data addressed to the own device based on the demodulation result of the control signal. 
     In the following, a reception process performed by the user terminal device  200  related to eMBB having the configuration described above will be described with reference to the flowchart illustrated in  FIG. 12 . In  FIG. 12 , the same processes as those illustrated in  FIG. 6  are assigned the same reference numerals and descriptions thereof in detail will be omitted. 
     Regarding the signal transmitted from the base station device  100 , a reception signal in the frequency domain is obtained from the antenna via the radio receiving unit  200   a , the CP removing unit  210 , and the FFT unit  220  (Step S 201 -S 204 ). Then, the indication signal arranged in the URLLC area in the reception signal is demodulated by the indication signal demodulating unit  410  (Step S 205 ) and it is determined whether the URLLC data is included in the URLLC area (Step S 401 ). 
     If the URLLC data is included in the URLLC area (Yes at Step S 401 ), the reception power for each subcarrier in the URLLC area is measured by the reception power measuring unit  420  (Step S 402 ). Then, the transmission power for each subcarrier is estimated from the reception power for each subcarrier by the transmission power estimating unit  430  (Step S 403 ). Namely, for example, the propagation loss between the base station device  100  and the user terminal device  200  is estimated and then the transmission power for each subcarrier in the base station device  100  is estimated by adding the electrical power having an amount corresponding to the propagation loss to the reception power. 
     The estimation result of the transmission power is notified to the eMBB data demodulating unit  440  and the subcarrier in which the URLLC data in the URLLC area has been arranged is specified by the eMBB data demodulating unit  440  (Step S 404 ). Specifically, the transmission power estimated for each subcarrier is compared to the predetermined threshold by the eMBB data demodulating unit  440  and it is determined that the URLLC data has been arranged in the subcarriers in each of which the transmission power is equal to or greater than the predetermined threshold. In contrast, it is determined that the eMBB data has been arranged in the subcarriers in each of which the transmission power in the URLLC area is less than the predetermined threshold. Consequently, in also the case where the URLLC data in the URLLC area is included, the area in which the eMBB data in the eMBB data area is arranged is specified. 
     Then, if the area in which the eMBB data is arranged is specified, the control signal that has been arranged in the eMBB control channel area in the reception signal is demodulated by the control signal demodulating unit  240  (Step S 206 ) and the resource allocated to the eMBB data that is addressed to the own device is specified. Furthermore, the eMBB data addressed to the own device is acquired from the reception signal and demodulated by the eMBB data demodulating unit  440  (Step S 207 ). 
     Furthermore, if the URLLC data is not included in the URLLC area (No at Step S 401 ), based on the demodulation result of the control signal, the resource allocated to the eMBB data addressed to the own device is specified from the entire eMBB data area and then the eMBB data addressed to the own device is demodulated by the eMBB data demodulating unit  440 . 
     As described above, according to the embodiment, the URLLC area that is temporarily reserved as the area for arranging the URLLC data is provided in the eMBB data area and, if URLLC data is generated, the URLLC data is transmitted by using the resource of the URLLC area. Furthermore, in the URLLC area, the indication signal indicating whether the URLLC data is present is arranged. Consequently, if URLLC data is generated, it is possible to promptly transmit the URLLC data without delay and, if URLLC data is not generated, it is possible to transmit eMBB data by using the resource of the URLLC area. Furthermore, if URLLC data is included in the URLLC area, the user terminal device on the reception side estimates the transmission power for each subcarrier in the URLLC area and specifies, based on the transmission power, the subcarrier in which the URLLC data has been arranged. Consequently, the information for specifying the resource that is used to arrange the URLLC data does not need to be included in the indication signal and thus it is possible to reduce the size of the indication signal. 
     Furthermore, in the second embodiment described above, the user terminal device  200  related to URLLC has been described; however, similarly to the user terminal device  200  related to eMBB, the user terminal device  200  related to URLLC also specifies, from the transmission power for each subcarrier, the subcarrier in which the URLLC data has been arranged. 
     Furthermore, in each of the embodiments, a description has been given with the assumption that an indication signal is arranged in an URLLC area; however, the indication signal does not always need to be arranged in the URLLC area. Namely, if it is possible to specify the association relationship between an indication signal and an URLLC area, the indication signal may also be transmitted separated from eMBB data and URLLC data. Furthermore, the indication signal may also be transmitted by, for example, dynamic signaling, such as physical downlink control channel (PDCCH) signaling, or may also be transmitted by quasi-static signaling, such as radio resource control (RRC) signaling. 
     According to an aspect of an embodiment of the base station device, the terminal device, and the transmission method disclosed in the present application, an advantage is provided in that it is possible to efficiently use the resources. 
     All examples and conditional language recited herein are intended for pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.