Patent Publication Number: US-2011065466-A1

Title: Mobile station device, base station device, and radio communication system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mobile station device, a base station device, and a radio communication system. 
     2. Description of the Related Art 
     (Data Rate Variation in Cellular Radio Communication System) 
     In the case of performing data communication in a cellular radio communication system (hereinafter, may be simply referred to as “radio communication system”), it is general that a transmission band to be provided varies depending on the position where a mobile station device (hereinafter, may be simply referred to as “mobile station”) is located. That is because, when the mobile station is located near a base station device (hereinafter, may be simply referred to as “base station”), high reception SNR (Signal to Noise ratio) can be expected, and hence, a modulation system which is capable of providing a high throughput such as 16 QAM (Quadrature Amplitude Modulation) or 64 QAM can be used, but on the other hand, when the mobile station is located far away from the base station, the mobile station has to communicate at low reception SNR, and hence is forced to use a low order modulation system such as BPSK (Binary Phase Shift Keying) or QPSK (Quadrature Phase Shift Keying). Under the circumstances where communication quality varies, there are proposed various methods as a methodology for avoiding stress imparted to users. 
     For example, there is disclosed a method in which communication quality confirmation data is distributed from a base station prior to start of communication and whether the communication quality is poor is determined before the communication (e.g., see JP-A-1999-127108). Further, there is disclosed a method in which a mobile station exchanges its position information and data rate estimation information with a base station and an estimate value of the data rate to be provided is displayed to a user (e.g., see JP-A-2002-353876). 
     In addition, there are known a system which distributes alarm information to a terminal station in the case where the communication quality may become poor during real-time communication (e.g., see JP-A-2006-352620), and a method of classifying distribution requests based on whether the requests are real-time service or not, and determining whether a network is capable of satisfying a distribution request (e.g., see JP-W-2008-536409). 
     (Study on Side of Operator of Cellular Radio Communication System) 
     On the other hand, it is important that data communication connection service providers arrange base stations in a manner that satisfies a user. Actually, radio wave propagation is largely influenced by buildings and the like, which is called shadowing, and hence, it is difficult to appropriately send radio waves to all the areas that the user visits even though, for example, the base stations are arranged at regular intervals. In many cases, there are places where no signal from any base stations is sent and places where too many signals are sent from multiple base stations and signals are interfered with each other, for example. It is necessary that the service providers arrange the base stations in such a manner to decrease those places as much as possible. For example, it is necessary that the service providers perform computational simulation on radio wave arrival state beforehand and investigate where to arrange the base stations (e.g., see JP-A-2001-94502 and JP-W-2004-510372). 
     SUMMARY OF THE INVENTION 
     However, although various methods are proposed as the methodology for avoiding stress imparted to the users under the circumstances where the communication quality varies as described above, it was difficult to essentially enhance the communication quality, and the degree which contributed to the improvement was small. 
     Further, although the computational simulation on radio wave arrival state is performed beforehand and where to arrange the base stations is attempted to be investigated, there is a gap between the computational results output from the computer and the actuality, and hence, there occurs a problematic area. In addition, the information on which location the user performs massive data communication fluctuates dynamically, and therefore, there are limitations to the computational simulation. 
     Accordingly, when there is a deficit in the service area, it is necessary that the user call the service provider and complain “the connection was bad in such and such a place” to require improvement in service. Further, it is also necessary that the service provider take the trouble to respond to the complaint, confirm the degree of the content of the complaint by on-the-spot investigation, and examine whether or not to place a base station, and hence, in many cases, it took great efforts to build a satisfactory service area. 
     In light of the foregoing, it is desirable to provide a novel and improved technology which enables to extract efficiently and automatically information on a location where a user carrying a mobile station device is dissatisfied with a service. 
     According to an embodiment of the present invention, there is provided a mobile station device which includes a reception section which receives a radio signal from a base station device, a communication information acquisition section which acquires, based on the radio signal received by the reception section, communication information which is information related to communication with the base station, a position information acquisition section which acquires position information indicating a position of the mobile station device, and a transmission section which transmits the position information acquired by the position information acquisition section and the communication information acquired by the communication information acquisition section to the base station device using a radio signal. 
     The communication information acquisition section may measure communication quality of communication with the base station using a radio signal, and may acquire communication quality information indicating the measured communication quality as the communication information. 
     When it is determined that the communication quality information is higher than a threshold, the communication information acquisition section may not acquire the communication quality information as the communication information. The transmission section may not transmit the position information and the communication information to the base station device. 
     The communication information acquisition section may measure, as the communication quality, a received power strength of a radio signal which is received from the base station device by the reception section or a signal-to-interference-noise ratio of the radio signal. 
     The communication information acquisition section may acquire a data amount contained in a radio signal received from the base station device by the reception section and a time at which the radio signal is received, may calculate, based on the acquired data amount and the acquired time, a data amount every predetermined hour as a reception average throughput, and may measure the calculated reception average throughput as the communication quality. 
     The mobile station device may further include an input section which accepts input of communication quality information from a user. The communication information acquisition section may acquire the communication quality information as the communication information, the input of the communication quality information from the user being accepted by the input section. 
     The position information and the communication quality information transmitted to the base station device by the transmission section may be transmitted to a data management device by the base station device, and may be used for the data management device to specify a position at which the communication quality is poor based on pieces of the position information and pieces of the communication quality information transmitted from a plurality of the base station devices. 
     When the mobile station device adds mobile station identification information, which is information for identifying the mobile station, to at least one of the position information and the communication information and transmits the position information and the communication information to the base station device, the mobile station identification information may be deleted by the base station device and then the position information and the communication information may be transmitted to the data management device. 
     The mobile station device may further include a storage section and a retransmission control section which causes the storage section to store the position information and the communication information when the transmission section is incapable of transmitting the position information and the communication information using a radio signal, and which acquires the position information and the communication information from the storage section when it is detected that communication with the base station device becomes possible. The transmission section may transmit the position information and the communication information acquired by the retransmission control section to the base station device using a radio signal. 
     When the transmission section transmits the position information and the communication information to the base station device using a radio signal, a charge imposed on a user of the mobile station device for communication between the mobile station device and the base station device using a radio signal may be reduced. 
     The communication information acquisition section may extract frequency channel information indicating a frequency channel used for communication with the base station device from the radio signal received by the reception section, and may acquire the extracted frequency channel information as the communication information. 
     The communication information acquisition section may measure, as communication quality, the received power strength of a radio signal which is received from the base station device by the reception section or the signal-to-interference-noise ratio of the radio signal, and may further acquire communication quality information indicating the measured communication quality. The transmission section may further transmit the communication quality information to the base station device using a radio signal. 
     The position information and the frequency channel information transmitted from the base station device by the transmission section may be transmitted to a data management device by the base station device, and may be used for the data management device to specify, based on pieces of the position information and pieces of the frequency channel information transmitted from a plurality of the base station devices, a position at which a radio signal transmitted from the base station device is received for each of the pieces of the frequency channel information. 
     According to the embodiments of the present invention described above, it becomes possible to extract efficiently and automatically information on a location where a user carrying a mobile station device is dissatisfied with a service. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a configuration example of a radio communication system according to a first embodiment of the present invention; 
         FIG. 2  is a diagram showing an example of usage of a frequency resource according to the embodiment; 
         FIG. 3  is a summarized diagram of signal types transmitted by a base station according to the embodiment; 
         FIG. 4  is a diagram illustrating a weak signal area and an intercell interference area; 
         FIG. 5  is a diagram showing a hardware configuration of a mobile station according to the first embodiment of the present invention; 
         FIG. 6  is a diagram showing a functional configuration of the mobile station according to the embodiment; 
         FIG. 7  is a diagram showing a hardware configuration of the base station according to the embodiment; 
         FIG. 8  is a diagram showing a functional configuration of the base station according to the embodiment; 
         FIG. 9  is a flowchart showing a flow of processing executed by the mobile station according to the embodiment; 
         FIG. 10  is a flowchart showing a flow of processing from the start to the end of a session; 
         FIG. 11  is a diagram showing a configuration example of a radio communication system in which a data management device is present; 
         FIG. 12  is a diagram showing a configuration example of a packet; and 
         FIG. 13  is a diagram showing a configuration example of a radio communication system in which a relay station is present. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the appended drawings. Note that, in this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these structural elements is omitted. 
     Note that the description will be given in the following order.
     1. First embodiment
       1-1. Outline of radio communication system according to present embodiment   1-2. Weak signal area and intercell interference area   1-3. Hardware configuration of mobile station   1-4. Functional configuration of mobile station   1-5. Hardware configuration of base station   1-6. Functional configuration of base station   1-7. Processing in mobile station (measurement and notification of communication quality)   1-8. Other example of processing in mobile station   1-9. Description on session   1-10. Processing in mobile station (measurement and notification of frequency channel in use)   1-11. Processing in network side (aggregate of communication quality)   1-12. Processing in network side (measurement and notification of frequency channel in use)   1-13. Link with charging   
       2. Modified example   3. Summary   

     1. First Embodiment 
     1-1. Outline of Radio Communication System According to Present Embodiment 
       FIG. 1  is a diagram showing a configuration example of a radio communication system according to a first embodiment of the present invention. As shown in  FIG. 1 , it is known as a cellular radio communication system that a system in which a mobile station  100  wirelessly communicates with a base station  200  which is installed on a rooftop of a building or the like and a base station  200  connects to an outside network  40 . A so-called cellular phone system is one example of the cellular radio communication system. 
     In a radio communication system  1 , a service provider installs many base stations  200  and develops service areas in such a manner that the mobile station  100  can connect to the base station  200  wherever the mobile station  100  is located. This state is shown in  FIG. 1 . In  FIG. 1 , a service area  20  represents an area within which communication with the base station  200  is assumed to be performed. The area which can provide a service to the base station  200  is referred to as, for example, cell. When the mobile station  100  is located, for example, within a service area  20 E and a service area  20 D, the mobile station  100  is connected to a base station  200 E and a base station  200 D, respectively. In this way, by changing the base stations  200  to be connected to depending on the place at which the mobile station  100  is located, the connection between the mobile station  100  and the base station  200  is not interrupted even in the case where the mobile station  100  is transferred. 
     In the system, at the edge of the service area  20 , the mobile station  100  can receive signals from multiple base stations  200 . For this reason, there is a case where respective base stations  200  are arranged in such a manner that service areas  20  provided with services from base stations  200  using the same frequency channel do not overlap with each other. This example will be described with reference to  FIG. 2 . 
       FIG. 2  is a diagram showing an example of usage of a frequency resource, which schematically shows the way in which the frequency resource allocated to a service provider is used. In most of the radio communication systems  1 , there is adopted a mode called FDD (Frequency Division Duplex), in which different frequency bands are allocated to an uplink channel (channel in a direction from the mobile station  100  to the base station  200 ) and a downlink channel (channel in a direction from the base station  200  to the mobile station  100 ). In addition, the uplink channel and the downlink channel are each further compartmentalized, and in a certain base station  200 , a frequency channel is allocated such that only a part thereof is used. Accordingly, by systematically arranging the base stations  200  in such a manner that the same frequency band is not shared between the base stations  200  placed adjacently to each other, the system is controlled not to cause interference. 
     Information on the radio communication system  1  is described in detail in, for example, “Digital Mobile Communication” ISBN-4-905577-26-8, supervising editor: Moriji Kuwabara, so please refer to those documents for detail. A base station  200  transmits/receives a signal necessary for the communication with the mobile station  100  within a frequency band whose availability in the base station  200  is preliminarily set. 
       FIG. 3  is a summarized diagram of signal types transmitted by a base station. First, the base station  200  transmits a synchronization signal at regular intervals to the mobile station  100  for the purpose of notifying the mobile station  100  that the base station  200  is present and also notifying the mobile station  100  of a reference time of the base station  200 . By receiving the synchronization signal, the mobile station  100  detects that the base station  200  is present in the periphery thereof, and extracts information on timing at which the signal is to be received in order to receive a control signal. 
     Further, the base station  200  transmits a reference signal at regular intervals in a known pattern, and the reference signal is used for estimating a transmission path of a symbol in which information is modulated. In addition, the base station  200  transmits a control channel for notifying the mobile station  100  of control information. The control channel is a signal that can be demodulated and received depending on timing information obtained from the synchronization signal and the transmission path estimation results obtained from the reference signal. The mobile station  100  can extract brief information of the base station  200  by receiving the control channel 
     As the control channel, there are defined multiple kinds of control channels, and the mobile station  100  first receives a control type identification channel to thereby obtain basic information on which frequency band and at which timing the control channel is transmitted in that cell. In accordance with the basic information, the mobile station  100  receives a downlink control channel Accordingly, the mobile station  100  acquires a system parameter and the like, and determines whether it is possible to communicate with the base station  200  and whether to perform communication, for example. In the case where the mobile station  100  actually communicates with the base station  200 , the mobile station  100  notifies the base station  200  of a traffic channel allocation request, and a traffic channel is allocated to the mobile station  100  from the base station  200 . 
     Signal formats used in the radio communication system  1  are described in, for example, 3GPP TS 36.211 (3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation), and 3GPP TS 36.213 (3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures), so please refer to those documents for detail. 
     1-2. Weak Signal Area and Intercell Interference Area 
       FIG. 4  is a diagram illustrating a weak signal area and an intercell interference area. As described above, it is important that data communication connection service providers arrange base stations  200  in a manner that satisfies a user. Actually, radio wave propagation is largely influenced by buildings and the like, which is called shadowing, and hence, it is difficult to appropriately send radio waves to all the areas that the user visits even though, for example, the base stations  200  are arranged at regular intervals. In many cases, there are places where no signal from any base stations  200  is sent (e.g., a weak signal area  21  shown in  FIG. 4 ) and places where too many signals are sent from multiple base stations and signals are interfered with each other (e.g., an intercell interference area  22  shown in  FIG. 4 ), for example. It is necessary that the service providers arrange the base stations  200  in such a manner to decrease those places as much as possible. 
     1-3. Hardware Configuration of Mobile Station 
       FIG. 5  is a diagram showing a hardware configuration of a mobile station according to the first embodiment of the present invention. With reference to  FIG. 5 , the hardware configuration of the mobile station according to the present embodiment will be described. Typically, there is assumed a form like a cellular phone terminal for the mobile station  100 , but the mobile station  100  is not limited to the cellular phone terminal. The mobile station  100  includes a radio signal processing section  730 . The radio signal processing section  730  is a module for performing signal processing for communicating with the base station  200  and signal processing necessary for performing communication indicating which base station  200  or which provider&#39;s network the mobile station  100  is to be connected to. The signal processed by the module is transmitted to/received from the base station  200  which is a communication partner, via an antenna  710 . 
     The mobile station  100  includes a non-volatile memory  760 . The mobile station  100  further includes a CPU  740 . A signal transmitted/received via the radio signal processing section  730  and a signal retrieved from the non-volatile memory  760  are subjected to digital signal processing in the CPU  740 , and for example, the signals are each treated as a signal processed into various forms such as image information. The signal is output from the output device  780  (such as a display and a speaker). Further, the CPU  740  may accept an input of an instruction from a user via an input device  770  (such as an input button, a numeric keypad, and a touch panel), and in accordance with the instruction, the CPU  740  can develop a program stored in the non-volatile memory  760  in a RAM (Random Access Memory)  750  and execute the program. Further, the CPU  740  can develop and execute an application stored in the non-volatile memory  760  in the RAM  750  in accordance with the instruction from the user, and can start or finish communication. 
     The mobile station  100  may have a hardware configuration capable of acquiring position information. However, there is no limitation on the way in which the mobile station  100  acquires the position information. For example, the mobile station  100  may acquire position information by mounting thereon a device such as a GPS receiver, or may also estimate the position of the mobile station  100  by a method of specifying a position by using a signal of a cellular radio communication system (e.g., see JP-W-2004-532576), a method of specifying the position by using base station identification information included in a radio signal transmitted from the base station  200 , or by a combination of those methods. The mobile station  100  can obtain position information at the present moment by using position information acquisition means. 
     1-4. Functional Configuration of Mobile Station 
       FIG. 6  is a diagram showing a functional configuration of the mobile station according to the embodiment. With reference to  FIG. 6 , the functional configuration of the mobile station according to the present embodiment will be described. As shown in  FIG. 6 , the mobile station  100  includes a reception section  110 , a control section  120 , a transmission section  130 , an input section  140 , a storage section  150 , an output section  160 , and the like. 
     The reception section  110  has a function of receiving a radio signal from the base station  200 . The reception section  110  has an antenna, for example, and the antenna included in the reception section  110  may be identical to or different from an antenna included in the transmission section  130 . 
     The control section  120  includes a communication information acquisition section  121 , a position information acquisition section  122 , a retransmission control section  123 , and the like. Further, the control section  120  has a function of controlling operation of each functional block that the mobile station  100  has. The control section  120  includes a CPU, for example, and the function thereof can be realized by developing a program stored in a non-volatile memory in a RAM by the CPU and executing the program developed in the RAM by the CPU. 
     The transmission section  130  has a function of transmitting a radio signal. The transmission section  130  has an antenna, for example, and the antenna included in the transmission section  130  may be identical to or different from the antenna included in the reception section  110 . 
     The storage section  150  has a function of storing data. The hardware configuration of the storage section  150  is not particularly limited as long as it has a function of storing data, and storage section  150  has a non-volatile memory, for example. 
     The output section  160  has a function of outputting audio and image based on audio data and image data. The output section  160  has a speaker and a display device, for example. 
     The communication information acquisition section  121  has a function of acquiring, based on the radio signal received by the reception section  110 , communication information which is information related to communication with the base station  200 . It is assumed that there are various pieces of communication information. The communication information acquisition section  121  may measure communication quality of the communication with the base station  200  using a radio signal, and may acquire communication quality information indicating the measured communication quality as the communication information, for example. Further, the communication information acquisition section  121  may extract frequency channel information indicating a frequency channel used for the communication with the base station  200  from the radio signal received by the reception section  110 , and may acquire the extracted frequency channel information as the communication information, for example. 
     The position information acquisition section  122  has a function of acquiring position information indicating the position of the mobile station device. As described above, there is no limitation on the way in which the position information is acquired. For example, the position information acquisition section  122  may acquire position information by mounting thereon a device such as a GPS receiver, or may also estimate the position of the mobile station  100  by a method of specifying a position by using a signal of a cellular radio communication system, a method of specifying the position by using base station identification information included in a radio signal transmitted from the base station  200 , or by a combination of those methods. The transmission section  130  transmits the position information acquired by the position information acquisition section  122  and the communication information acquired by the communication information acquisition section  121  to the base station  200  using a radio signal. 
     In the case where it is determined that the communication quality information is higher than a threshold, the communication information acquisition section  121  may not acquire the communication quality information as the communication information, and the transmission section  130  may not transmit the position information and the communication information to the base station  200  using a radio signal. 
     It is assumed that there are various communication qualities. For example, the communication information acquisition section  121  may measure, as the communication quality, a received power strength of a radio signal which is received from the base station  200  by the reception section  110  or a signal-to-interference-noise ratio of the radio signal. Further, the communication information acquisition section  121  may also acquire a data amount contained in a radio signal received from the base station  200  by the reception section  110  and a time at which the radio signal is received, may calculate, based on the acquired data amount and the time, a data amount every predetermined hour as a reception average throughput, and may measure the calculated reception average throughput as the communication quality. 
     The communication quality information may be input by the user who actually talks on the phone. The input section  140  has a function of accepting input of the communication quality information from the user. The communication information acquisition section  121  may acquire the communication quality information as the communication information, the input of the communication quality information from the user being accepted by the input section  140 . 
     There may be a case where it is difficult for the transmission section  130  to transmit the position information and the communication information by using a radio signal. In this case, the retransmission control section  123  causes the storage section  150  to store the position information and the communication information, and, when it is detected that the communication with the base station  200  becomes possible, the retransmission control section  123  may acquire the position information and the communication information from the storage section  150 . The transmission section  130  transmits the position information and the communication information acquired by the retransmission control section  123  to the base station  200  using a radio signal. 
     The communication information acquisition section  121  may measure, as the communication quality, the received power strength of a radio signal which is received from the base station  200  by the reception section  110  or the signal-to-interference-noise ratio of the radio signal, and may further acquire communication quality information indicating the measured communication quality. In this case, the transmission section  130  may further transmit the communication quality information to the base station  200  using a radio signal. 
     The position information and the communication quality information transmitted to the base station  200  by the transmission section  130  may also be transmitted to a data management device  400  by the base station  200  via a network  40 . In this case, for example, the position information and the communication quality information may be used for the data management device  400  to specify a position at which the communication quality is poor based on pieces of the position information and pieces of the communication quality information transmitted from multiple base stations  200 . 
     In the case where the mobile station  100  adds mobile station identification information, which is information for identifying the mobile station  100 , to at least one of the position information and the communication information and transmits the position information and the communication information to the base station  200 , the mobile station identification information may be deleted by the base station  200  and then the position information and the communication information may be transmitted to the data management device  400 . 
     Further, as will be described later, the service provider can encourage the users to provide information by giving incentive such as discounting communication charge to the user who carries the mobile station  100  from which communication information is reported. That is, in the case where the transmission section  130  transmits the position information and the communication information to the base station  200  using a radio signal, a charge imposed on a user of the mobile station  100  for the communication between the mobile station  100  and the base station  200  using a radio signal may be reduced. Further, the calculation and reduction of the charge may be performed by a charge calculation device. 
     The position information and the communication quality information transmitted to the base station  200  by the transmission section  130  may also be transmitted by the base station  200  to the data management device  400  via the network  40 . In this case, the data management device  400  may specify, based on pieces of position information and pieces of frequency channel information transmitted from multiple base stations  200 , a position at which a radio signal transmitted from the base station  200  is received for each of the pieces of frequency channel information. 
     1-5. Hardware Configuration of Base Station 
       FIG. 7  is a diagram showing a hardware configuration of the base station according to the embodiment. With reference to  FIG. 7 , the hardware configuration of the base station according to the present embodiment will be described. The base station  200  includes a radio signal processing section  830 . The radio signal processing section  830  is a module for performing signal processing for communicating with the mobile station  100 . The signal processed by the module is transmitted to/received from the mobile station  100 , which is a communication partner, via an antenna  810 . 
     The base station  200  includes a RAM  850 , a non-volatile memory  860 , and the like. The base station  200  further includes a CPU  840 , and the CPU  840  can develop a program stored in the non-volatile memory  860  in a RAM  850  and execute the program. 
     The base station  200  further includes a communication device  890 . The communication device  890  is connected to a network  40 , and the communication device  890  is capable of communicating with the data management device  400  via the network  40 . In addition, the communication device  890  can communicate with another device which is connected to the network  40  via the network  40 . 
     1-6. Functional Configuration of Base Station 
       FIG. 8  is a diagram showing a functional configuration of the base station according to the embodiment. With reference to  FIG. 8 , the functional configuration of the base station according to the embodiment will be described. As shown in  FIG. 8 , the base station  200  includes a reception section  210 , a control section  220 , a transmission section  230 , a storage section  250 , a communication section  270 , and the like. 
     The reception section  210  has a function of receiving the position information and the communication information from the mobile station  100  using a radio signal. The reception section  210  has an antenna, for example, and the antenna included in the reception section  210  may be identical to or different from an antenna included in the transmission section  230 . 
     The control section  220  has functions of acquiring the position information and the communication information from the radio signal received by the reception section  210  and outputting the acquired position information and communication information to the communication section  270 . The control section  220  has a function of controlling operation of each functional block that the base station  200  has. The control section  220  includes a CPU, for example, and the function thereof can be realized by developing a program stored in a non-volatile memory in a RAM by the CPU and executing the program developed in the RAM by the CPU. 
     The transmission section  230  has a function of transmitting a radio signal to the mobile station  100 . The transmission section  230  has an antenna, for example, and the antenna included in the transmission section  230  may be identical to or different from the antenna included in the reception section  210 . 
     The storage section  250  has a function of storing data. The storage section  250  has a non-volatile memory, for example. 
     The communication section  270  has a function of communicating with another device which is connected to the network  40  via the network  40 . The communication section  270  transmits the position information and the communication information output from the control section  220  to the data management device  400  via a network. The communication section  270  has a communication device, for example. 
     1-7. Processing in Mobile Station (Measurement and Notification of Communication Quality) 
       FIG. 9  is a flowchart showing a flow of processing executed by the mobile station according to the embodiment. With reference to  FIG. 9 , the flow of processing executed by the mobile station  100  will be described. When the mobile station  100  activates an application or the like and communication is attempted, monitoring of a communication status of the application is started (Step S 101 ). The monitoring may be performed by a radio communication procedure or the CPU  740 . As items of the communication qualities to be monitored, there can be considered the following items (1) to (7): 
     (1) a reception strength or reception SINR of a transmission signal from the base station  200 ; 
     (2) a transmission rate used for communication with the base station  200 ; 
     (3) a transmission buffer amount (transmission-queue data amount) of the mobile station  100 ; 
     (4) a flow rate of data transmitted from the mobile station  100  (average transmission throughput); 
     (5) a flow rate of data transmitted from the base station  200  (average reception throughput); 
     (6) a time period during which a waiting state of an application task corresponds to communication waiting state (corresponding to a time period during which data transmission being a bottleneck; and 
     (7) a number of times which buffer underflow occurs in the application (corresponding to the number of times a trouble is caused in the application). 
     When the application is activated, the measurements of the communication qualities are performed (monitoring of the communication status is continued), and when the communication is terminated by the application being terminated or the like, the quality of the communication is aggregated and communication quality information is acquired (Step S 102 ). Note that there is also a case where the application is terminated by force-quit command performed by a user. The session disconnection becomes a trigger for the aggregate of the communication quality, for example. 
     After that, the mobile station  100  compares the acquired communication quality information (aggregated communication quality) with a predetermined threshold, and in the case where the communication quality is less than the threshold (“Yes” in Step S 103 ), the mobile station  100  determines that the communication quality at that location is inadequate and acquires position information (Step S 104 ); acquires time information at the present moment (Step S 105 ); and gathers measurement results of the measured communication qualities as data, adds the measurement results to the position information and the time information, and notifies the base station  200  of the results as the measurement results (Step S 106 ). Here, although there is described an example in which the notification of the communication quality information is performed only when the communication quality is inadequate, there is also a case where the notification of the communication quality information is performed every session regardless of whether or not the communication quality is adequate. There is a case where the start time and the end time of the session is recorded in the time information. The time information is used when the data is aggregated in the data management device  400 , for example. 
     In the description above, it is considered the case where the mobile station  100  can communicate with the base station  200  when the mobile station  100  activates the application, but there can be also considered a case where the mobile station  100  is at a location where it cannot capture the radio wave of the base station  200 . In that case, the information cannot be passed on to the base station  200  immediately. In this way, in the case where the mobile station  100  cannot establish a communication link with the base station  200  even though the mobile station  100  attempts to notify measurement results to the base station  200 , the mobile station  100  may record the measurement results and, when the state thereof moves to the one that can establish the communication link with the base station  200 , may notify the base station  200  of the recorded measurement results. 
     In this manner, by notifying the base station  200  side of the communication quality information measured in the mobile station  100 , it becomes possible for the base station  200  side to automatically obtain the information about which location it is recognized that the communication quality is poor. 
     1-8. Other Example of Processing in Mobile Station 
     In the description above, whether or not the communication quality is adequate is determined by the result of comparison between one of the parameters shown in items (1) to (7) and a predetermined threshold (Step S 103 ). In addition, a determination criterion to determine whether or not a desired communication quality is satisfied may be that based on input from the user in response to the question from the mobile station  100  to the user of whether or not the communication quality is satisfactory. In this case, at the end of a session, the mobile station  100  performs display or the like for inquiring the user whether or not the session was satisfactory from the output device  780 . In response thereto, a satisfaction level of the communication quality considered by the user is input by the user from the input device  770 . The satisfaction level may be adopted as communication quality information, and may be notified to the base station  200  as a measurement result in the same manner as described above. 
     Still further, the communication quality information may be transmitted to the base station  200 , not the result of comparing the communication quality information with the threshold, and not based on whether or not the measured quality is good. In that case, the processing of comparing the communication quality information and the threshold can be omitted. The base station  200  may be capable of instructing, to the mobile station  100 , which of the following is to be transmitted to the base station  200 : the result of comparing the communication quality information with the threshold; the communication quality information input by the user; and the communication quality information obtained as a measurement result. 
     1-9. Description on Session 
       FIG. 10  is a flowchart showing a flow of processing from the start to the end of a session. With reference to  FIG. 10 , the flow of processing from the start to the end of a session will be described. 
     The session shown in the description above starts by the activation or restart of an application and terminates by the completion or interruption of the application. When the application is activated, first, the session related to the application is started (established) (Step S 201 ). In the established session, transmission/reception of desired application data is performed (Step S 202 ), and the application operates based on the obtained data (Step S 203 ). 
     When the operation of the application is already completed here (“Yes” in Step S 204 ), the session related to the application is closed and terminated (Step S 206 ). On the other hand, in the case where the operation of the application is not completed (“No” in Step S 204 ), as long as interruption or timeout of the application does not occur (“No” in Step S 205 ), the transfer of data (Step  5202 ) and the operation of the application (Step S 203 ) are repeated. On the other hand, in the case where interruption or timeout of the application occurs (“Yes” in Step S 205 ), the session is once closed and terminated, even though the application itself is not terminated (Step S 206 ). 
     1-10. Processing in Mobile Station (Measurement and Notification of Frequency Channel in Use) 
     When the mobile station  100  activates monitoring a communication status of an application, there may be a case where, in addition to the processing described above, the mobile station  100  extracts information on a frequency resource which is used at that location and performs the notification thereof as a part of the communication quality information. 
     As described above with reference to  FIG. 2  and the like, in a cellular system, base stations  200  placed adjacently to each other use different frequency channels, but there is a case where intercell interference occurs because the base station  200  can sometimes receive a signal of a base station  200  of farther away. In the present embodiment, with the monitoring of the communication status, whether or not the intercell interference occurs is also determined. 
     While maintaining the communication state with a base station  200 , which is a communication partner, the mobile station  100  attempts to receive a synchronization signal of another base station  200  and confirms the presence of a nearby base station  200 . Each base station  200  transmits a synchronization signal for notifying timing information of the base station  200 , and hence, in the case where the base station  200  is present within an area that the mobile station  100  can receive the signal, the mobile station  100  can discover the base station  200 . In the case where the mobile station  100  could receive the synchronization signal of the nearby base station  200 , the mobile station  100  decodes various control signals transmitted at a predetermined time on the basis of the synchronization signal and obtains frequency channel information that the base station  200  uses. Further, the mobile station  100  extracts a signal (e.g., a synchronization signal or a control signal) that can be specified to be transmitted from a specific nearby base station  200  from among reception signals, and measures the received power strength of the signal transmitted from the base station  200 . 
     When the mobile station  100  transmits the communication quality information to the base station  200  based on the procedure shown in  FIG. 9 , the mobile station  100  notifies the base station  200  of the communication quality information by adding thereto the frequency channel information that the nearby base station  200  uses and the received power strength from the base station  200  which are obtained by the procedure described above. By transmitting the information to the base station  200 , it becomes possible for the base station  200  side to automatically obtain information on which location a signal of the nearby base station  200  (or a relay station  300  to be described later) is received at and which location may become an interference source. 
     1-11. Processing in Network Side (Aggregate of Communication Quality) 
     When the communication quality information is transmitted from the mobile station  100  to the base station  200  by the procedure described above, the base station  200  processes the data in order to aggregate the pieces of information notified by multiple mobile stations  100 . 
     As shown in  FIG. 11 , the base station  200  is connected to the data management device  400  which gathers communication quality information, and the data management device  400  aggregates the pieces of communication quality information which are gathered from multiple base stations  200  and are notified by an unspecified number of mobile stations  100 . The aggregate is performed by using the location information included in the communication quality information as an index, and brings together mainly at which location the communication quality of the user tends to be poor. Based on the information, a service provider determines where to place hereafter a new base station  200  (or the relay station  300  to be described later, which may be referred to as base station  200  for the purpose of simplifying the description, but includes the relay station  300 ), and a base station  200  is newly installed as necessary. 
     Note that, in the case where a new base station  200  is installed or in the case where transmission power in the base station  200  or a frequency bandwidth used in the base station  200  is changed, the aggregate of the communication quality information at the location belonging to the area which the base station  200  is responsible for is reset, and then the aggregate of communication quality in a new cell configuration is newly started. 
     As shown in  FIG. 12 , in the case where the communication quality information exchanged between the mobile station  100  and the base station  200  is packetized, a first header portion is added to a data portion (communication quality information), and in the header there is included a code for identifying the mobile station  100  (mobile station identification information). Before transferring the information to the data management device  400 , the base station  200  generates new header information (second header portion) by eliminating the mobile station identification information from the first header portion. The base station  200  transfers, to the data management device  400 , the information in the state in which the second header portion is added to the data portion (communication quality information). In this manner, it becomes difficult to identify a mobile station  100  or a user from the communication quality information transferred to the data management device  400 , and hence, it is prevented from being identified that which mobile station  100  was at which place and at what time. 
     1-12. Processing in Network Side (Measurement and Notification of Frequency Channel in Use) 
     In the case where the frequency channel information that the nearby base station  200  uses and the received power strength information from the base station  200  are included in the communication quality information reported by the mobile station  100 , the data management device  400  similarly aggregates the utilization status of the frequency channel notified by the unspecified number of mobile stations  100  and gathers information about at which location the frequency channel in use is recognized by the mobile station  100 . Based on the information, which frequency channel is to be used for which base station  200  can be determined, and the frequency channel to be used for the base station  200  may be changed as necessary. 
     Note that, in the case where a new base station  200  is installed or in the case where transmission power in the base station  200  or a frequency bandwidth used in the base station  200  is changed, the aggregate information at the location belonging to the area which the base station  200  is responsible for is reset, and then the aggregate of communication quality in a new cell configuration is newly started. 
     1-13. Link with Charging 
     The report of the communication quality information (or frequency channel information) is very important information for a service provider, and the service provider hopes to collect information from the mobile stations  100  as widely as possible. However, depending on the user of the mobile station  100 , there may be someone who does not want to perform the report. Accordingly, the service provider can encourage the users to provide the information by giving incentive such as discounting communication charge to the user carrying the mobile station  100  that reports the communication quality information (or frequency channel information). That is, depending on the mobile stations  100 , there are those which perform notification of the communication quality information (or frequency channel information) and those which do not, and for the mobile station  100  which performs notification of the communication quality information (or frequency channel information), the charge for the connection to the base station  200  is discounted. There should be considered a form in which the discount is applicable for each notification. Further, it is also possible to provide a charge calculation device for calculating the charge. 
     In addition, there is also a case where multiple thresholds, which are used for the determination in Step S 103  shown in  FIG. 9 , are prepared, and the threshold used for the determination is changed depending on a user&#39;s price plan. In this case, it is biased in such a manner that the more expensive the price plan, the higher the threshold is set, and the quality is determined to be insufficient when the communication is not performed with higher throughput. 
     2. Modified Example 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. 
     For example, although the description is made of the case where the mobile station  100  of the radio communication system  1  only communicates with the base station  200 , a radio communication system  1  considered in the present embodiment is not limited thereto, and the similar method is used in the case where a relay station  300  is installed for the purpose of extending a service area  20  covered by the base station  200 . With reference to  FIG. 13 , a configuration in which the relay station  300  is present will be described. 
     A base station  200 A connects to and provides a communication path to any mobile station  100 A, and at the same time, the base station  200 A also connects to and provides a communication path to a relay station  300 A. The relay station  300 A may operate as an endpoint of a communication session, and in addition thereto, connects to and provides a communication path to a mobile station  100 B which is another mobile station from the mobile station  100 A. In such configuration, the mobile station  100 B can communicate with the base station  200 A via the relay station  300 A. In this case, the relay station  300 A behaves as if itself is the base station  200 A with respect to the mobile station  100 B, and transmits a synchronization signal, a control signal, and the like that the base station  200 A transits. By receiving the signal, the mobile station  100 B recognizes the relay station  300 A as the base station  200  and establishes a communication path. 
     Therefore, in the radio communication system  1  in which the relay station  300  is mediated, the similar effect can be expected even when the “base station  200 ” described in the present embodiment is replaced with the “relay station  300 ”. 
     3. Summary 
     According to the present embodiment, it becomes possible to extract efficiently and automatically information on a location where a user carrying a mobile station device is dissatisfied with a service. In addition, by aggregating the information, it enables a service provider to investigate with less effort where to arrange a new base station for improving service quality. 
     The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-210990 filed in the Japan Patent Office on Sep. 11, 2009, the entire content of which is hereby incorporated by reference.