Patent Publication Number: US-2016242067-A1

Title: Radio communication system, radio communication terminal, control method of radio communication system, and storage medium

Description:
TECHNICAL FIELD 
     The disclosure of the present description relates to a radio communication system, a radio communication terminal, a control method of a radio communication system, and a storage medium. 
     BACKGROUND ART 
     With development of mobile communication systems in recent years, in particular, improvement in a transmission speed of communication or an increase in data capacity, the number of mobile multimedia services utilizing the system has a tendency to increase. However, when traffic used by the services exceeds permissible traffic of a system, congestion often occurs in a network in the system. The same thing can be said of a radio communication section between a radio communication terminal and a radio base station. 
     In order to suppress such congestion in a radio communication section, related mobile communication systems utilize a congestion control technique. Among them, PTL 1 discloses a radio communication system which performs autonomous congestion control of a radio terminal using congestion information based on a random access trial frequency and assignment conditions of radio channels, and the radio terminal. 
     Incidentally, with respect to mobile multimedia services, providers who provide OTT (Over The Top) services are gaining power with the standardization to IP (Internet Protocol) model in mobile communication systems in recent years. 
     OTT indicates a generic name for video or voice services or the like provided on an existing broadband network, with no participation by carriers in management or distribution of contents themselves. In case of mobile communication systems, the OTT is often provided to a radio communication terminal by an application. 
     Generally, when a video or voice service or the like requires, in particular, a real time communication, it is preferable to guarantee a constant communication speed. However, in mobile communication systems, a carrier providing a core network or radio base stations does not participate in management or distribution of the application even when the application especially requires a real time communication, and therefore is unable to judge only as a mere Internet access service. 
     With respect to a mere Internet access service, the carriers provide the service through a best-effort type communication that does not guarantee a communication speed. Therefore, in a best-effort type communication, resources on the network are insufficient when a resource required for the real time communication exceeds an available resource on a communication network, and this causes congestion. 
     Also in a radio communication section between a radio communication terminal and a radio base station, radio resources are insufficient upon execution of the communication when a radio resource required for the real time communication exceeds an available radio resource of a radio base station, and this causes congestion in the radio communication section. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Laid-open Patent Publication No. 2009-147592 
     SUMMARY OF INVENTION 
     Technical Problem 
     Autonomous control with a radio communication terminal is effective against such a problem. This is because a radio communication terminal executes an application, and therefore the radio communication terminal easily grasps whether or not a real time communication is required when executing the application. 
     However, a radio terminal in PTL 1 does not perform control in consideration of an available radio resource of a radio base station and a radio resource required for radio communication at the time of application execution. 
     Therefore, the radio terminal in PTL 1 connects to a base station and requests a radio resource required for desired radio communication even in a situation in which a radio resource required for radio communication at the time of the application execution exceeds an available radio resource of the radio base station. As a result, radio resources of a radio base station are insufficient, and congestion occurs in the radio communication section. 
     In view of the above, one of the objects of exemplary embodiments is to provide a radio communication system which can control congestion in a radio communication section. It is to be noted that this object is merely one of a plurality of objects which exemplary embodiments disclosed herein tries to achieve. Other objects or problems, and new features will be disclosed from description of the present description or accompanying drawings. 
     Solution to Problem 
     A radio communication system in an exemplary embodiment includes a radio communication terminal and a radio base station that performs radio communication with the radio communication terminal. The radio base station includes a transmission means for transmitting available radio resource information which is information on an available radio resource of the radio base station to the radio communication terminal, and the radio communication terminal includes a reception means for receiving the available radio resource information from the radio base station, a holding means for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal, and a control means for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     A radio communication terminal in an exemplary embodiment performs radio communication with a radio base station, and includes: a reception means for receiving available radio resource information which is information on an available radio resource of the radio base station from the radio base station; a holding means for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and a control means for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     A control method of a radio communication system in an exemplary embodiment includes, in a radio communication system including a radio communication terminal and a radio base station that performs radio communication with the radio communication terminal: a reception step for receiving available radio resource information which is information on a available radio resource of the radio base station; a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     A storage medium in an exemplary embodiment stores a program for causing a computer to execute a control method in a radio communication system that includes a radio communication terminal and a radio base station which performs radio communication with the radio communication terminal. The storage medium stores the program for causing a computer to execute: a reception step for receiving available radio resource information which is information on an available radio resource of the radio base station; a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     Advantageous Effects of Invention 
     According to exemplary embodiments of the present invention, it is possible to provide a radio communication system which can control congestion in a radio communication section. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a drawing illustrating a configuration according to a first exemplary embodiment. 
         FIG. 2  is a sequence chart illustrating an operation according to the first exemplary embodiment. 
         FIG. 3  is a sequence chart illustrating an operation according to a second exemplary embodiment. 
         FIG. 4  is a drawing illustrating a configuration according to a third exemplary embodiment. 
         FIG. 5  is a sequence chart illustrating an operation according to the third exemplary embodiment. 
         FIG. 6  is a drawing illustrating a configuration according to a fourth exemplary embodiment. 
         FIG. 7  is a sequence chart illustrating an operation according to the fourth exemplary embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, specific exemplary embodiments are described in detail with reference to drawings. In each drawing, the same signs are given to the same elements or elements corresponding to each other, and descriptions which overlap each other are omitted as needed for the sake of clarification of description. 
     A plurality of exemplary embodiments described below can be implemented independently or in combination, as appropriate, with each other. A plurality of these exemplary embodiments have new features which are different from each other. Therefore, a plurality of these exemplary embodiments contribute to solving different objects or problems each other, and contribute to achieving different effects each other. 
     First Exemplary Embodiment 
       FIG. 1  is a drawing illustrating an example of a configuration of a radio communication system according to a first exemplary embodiment. In the drawing, a radio communication system includes a radio base station  10  and a radio communication terminal  20 , and the radio base station  10  can perform radio communication with the radio communication terminal  20 . The radio base station  10  is communicatively connected with a core network (not illustrated). 
     The radio base station  10  includes a transmission unit  11  as a transmission means. The radio communication terminal  20  includes a reception unit  21  as a reception means, a required radio resource information holding unit  22  as a holding means, and a control unit  23  as a control means. 
     Note that  FIG. 1  illustrates, in particular, components relevant to the present exemplary embodiment among functional blocks included in the radio base station  10  and the radio communication terminal  20 . In other words, the radio base station  10  includes functional blocks (not illustrated) for causing the radio base station  10  to function as a radio base station. Similarly, the radio communication terminal  20  includes functional blocks (not illustrated) for causing the radio communication terminal  20  to function as a radio communication terminal. 
     The transmission unit  11  of the radio base station  10  transmits available radio resource information which is information on an available radio resource of the radio base station  10  to the radio communication terminal  20 . The reception unit  21  receives the available radio resource information transmitted from the transmission unit  11 . The required radio resource information holding unit  22  holds required radio resource information which is information on a radio resource required for the radio communication at the time of application execution of the radio communication terminal  20 . The control unit  23  determines whether or not the radio communication at the time of application execution is to be started on the basis of the available radio resource information and the required radio resource information when executing an application. 
     In the present exemplary embodiment, the application includes web browsing, download or streaming reproduction of a voice, an image, and a video, a voice communication service utilizing VoIP (Voice over IP), and an online game, for example. 
     The available radio resource information is, more specifically, information on a radio resource of the radio communication section between the radio base station and the radio communication terminal, and the radio resource not assigned by the radio base station at a certain point in time. 
     On the other hand, the required radio resource information is, more specifically, information on a radio resource required to ensure the desired communication speed of data communication used in an application execution. 
     The radio resource is, when the radio communication system is based on an LTE (Long Term Evolution) system, a resource block which is a minimum unit of radio resource assignment in a frequency direction, a subframe which is a minimum unit of radio resource assignment in a time direction, a resource element which is an element constituting the resource block and which is a fundamental unit to be modulated individually, or the like. 
     In other words, the information on the radio resource is, for example, the number of resource blocks, a position in the frequency direction, or the like when the radio resource is a resource block. 
       FIG. 2  is a sequence chart illustrating an example of an operation of the radio communication system according to the first exemplary embodiment. Hereinafter, operations of the radio base station  10  and the radio communication terminal  20  will be described with reference to  FIG. 2 . 
     The required radio resource information holding unit  22  of the radio communication terminal  20  holds the required radio resource information which is information on a radio resource required for the radio communication at the time of application execution (step S 101 ). 
     Here, the required radio resource information holding unit  22  may determine and hold the required radio resource information on the basis of the information on a radio resource used in previous radio communication by an application. 
     More specifically, the required radio resource information holding unit  22  holds, at the time of application installation, the required radio resource information i 0  which is information on a radio resource required for the radio communication at the time of application execution, as an initial value. Then, the control unit  23  performs below-described control using required radio resource information i n-1  at the time of the n-th application execution after the installation (n&gt;0 and n is an integer). When radio communication at the time of the n-th application execution is finished, the required radio resource information holding unit  22  may hold the information on the radio resource used in the actual radio communication as the required radio resource information i n . 
     In  FIG. 2 , the transmission unit  11  of the radio base station  10  transmits the available radio resource information of the radio base station  10  to the radio communication terminal  20  (step S 102 ). The reception unit  21  of the radio communication terminal  20  receives the available radio resource information (step S 103 ). Note that, for example, the available radio resource information may be transmitted in the notification information for notifying to the radio communication terminal  20  which is under the control of the radio base station  10 . 
     Note that the operations of steps S 102  and S 103  may be executed a plurality of times at arbitrary timings. The interval of the executions may be constant or random. 
     The radio communication terminal  20  activates an application in response to operation by a user (step S 104 ). 
     After activating the application, the control unit  23  determines whether or not radio communication at the time of application execution is to be started on the basis of the available radio resource information received by the reception unit  21  and the required radio resource information held by the required radio resource information holding unit  22  (step S 105 ). 
     Specifically, the control unit  23  acquires the available radio resource information and the required radio resource information from the reception unit  21  and the required radio resource information holding unit  22 , respectively. After that, the control unit  23  determines whether or not a radio resource of the radio base station  10  has a sufficient available radio resource required for the radio communication at the time of application execution, on the basis of the acquired available radio resource information and required radio resource information. 
     When the radio resource of the radio base station  10  has the sufficient available radio resource, the control unit  23  starts the radio communication to the radio base station  10 . When the radio resource does not have the sufficient available radio resource, the control unit  23  does not start the radio communication to the radio base station  10 . Note that, when the radio communication at the time of application execution is not to be started, the control unit  23  may notify to the application that the radio communication is not to be started, or may notify that the application is terminated. 
     When executing the application, the radio communication system according to the present exemplary embodiment determines whether or not the radio communication at the time of application execution is to be started on the basis of the available radio resource information and the required radio resource information. When the radio communication at the time of application execution is not started on the basis of the determination, the radio communication terminal does not request a radio resource to the radio base station, and therefore it is possible to avoid a radio resource insufficiency in the radio base station. Accordingly, congestion in the radio communication section is controllable. 
     As described above, according to the present invention, it is possible to provide the radio communication system which can control the congestion in the radio communication section. 
     Second Exemplary Embodiment 
     In a radio communication system according to a second exemplary embodiment, when the control unit  23  in the first exemplary embodiment determines that radio communication at the time of application execution is not to be started, a determination is performed again after the elapse of a predetermined period of time. 
     The radio communication system according to the second exemplary embodiment has a configuration that is the same as or similar to the system in the first exemplary embodiment illustrated in  FIG. 1 . 
       FIG. 3  is a sequence chart illustrating an example of an operation of the radio communication system according to the second exemplary embodiment. Hereinafter, operations of the radio base station  10  and the radio communication terminal  20  will be described with reference to  FIG. 3 . Note that the operations from steps S 201  to S 205  in  FIG. 3  are the same as or similar to the operations from steps S 101  to S 105  in the first exemplary embodiment, and therefore the description is omitted. 
     When it is determined that the radio communication at the time of application execution is not to be started by the operation of S 205  of the control unit  23  (NO in step S 206 ), the control unit  23  stops the operation of the control unit  23  for a predetermined period of time in a state that the radio communication is not started (step S 207 ). After the elapse of the predetermined period of time, the control unit  23  repeats the operations of steps S 205  and S 206 . Here, the control unit  23  may include a timer therein and may measure the predetermined period of time by the timer. 
     When it is determined that the radio communication at the time of application execution is to be started by the operation of S 205  of the control unit  23  (YES in step S 206 ), the control unit  23  starts the radio communication to the radio base station  10 . 
     Note that, the present exemplary embodiment may be made into an embodiment in which the control unit  23  performs the determination again at predetermined timing when it is determined that the radio communication at the time of application execution is not to be started. The predetermined timing is timing at which the reception unit  21  of the radio communication terminal  20  receives the available radio resource information of the radio base station, for example. 
     In the radio communication system according to the present exemplary embodiment, the control unit  23  performs the determination again after the elapse of a predetermined period of time when it is determined that the radio communication is not to be started. Therefore, in the radio communication system in the present exemplary embodiment, an opportunity to start the radio communication at the time of application execution is quickly provided by the radio communication terminal  20 . 
     Third Exemplary Embodiment 
     Due to acceptance of a massive update of an application provided by an OTT provider, there is a possibility that a big change in information on a radio resource required for radio communication at the time of the application execution may occur. 
     For example, when a faster communication speed is required for the data communication used at the time of the application execution due to the acceptance of an update, the radio resource required for ensuring the communication speed increases compared to the resource before the update. 
     Therefore, it is preferable to perform the determination by the control unit in the first exemplary embodiment on the basis of the latest information on the radio resource required for the radio communication at the time of the application execution, the information being stored in an application server which manages or distributes the application. 
     Thereupon, in the third exemplary embodiment, a required radio resource information holding unit  22  holds required radio resource information transmitted by an application server  40 . 
       FIG. 4  is a drawing illustrating an example of a configuration of a radio communication system according to the third exemplary embodiment. In the drawing, the radio communication system is communicatively connected with the application server  40  additionally through a network  30 , to the radio communication system in the first exemplary embodiment. 
     The network  30  is the Internet, for example, but it is not limited thereto. 
     To a radio base station  10  and a radio communication terminal  20  in the first exemplary embodiment, the radio base station  10  of  FIG. 4  further includes a reception unit  12 , and a communication unit  13 , and the radio communication terminal  20  further includes a transmission unit  24 . 
     The transmission unit  11 , the reception unit  12 , and the communication unit  13  of the radio base station  10  are communicatively connected one another. The reception unit  21 , the required radio resource information holding unit  22 , the control unit  23 , and the transmission unit  24  of the radio communication terminal  20  are communicatively connected one another. 
     Note that the radio base station  10  and the network  30  are connected directly in the radio communication system illustrated in  FIG. 4 . The radio base station  10  may be connected with the network  30  through a core network and a packet gateway node, like a general radio communication system. 
       FIG. 4  illustrates components particularly relevant to the present exemplary embodiment among functional blocks included in the radio base station  10  and the radio communication terminal  20 . In other words, the radio base station  10  includes functional blocks (not illustrated) for causing the radio base station  10  to function as a radio base station. Similarly, the radio communication terminal  20  includes functional blocks (not illustrated) for causing the radio communication terminal  20  to function as a radio communication terminal. 
     The control unit  23  instructs the transmission unit  24  to transmit a request message to the radio base station  10  when the radio communication at the time of application execution is started according to the determination by the control unit  23 . The transmission unit  24  transmits the request message to the radio base station  10 . The request message is a message for requesting the application server  40  to transmit the required radio resource information to the radio communication terminal  20 . 
     The reception unit  12  of the radio base station  10  receives the request message from the radio communication terminal  20 . The communication unit  13  transmits to and receives from the application server  40 , the request message and the required radio resource information through the network  30 . The transmission unit  11  transmits the required radio resource information to the radio communication terminal  20 . 
     The reception unit  21  of the radio communication terminal  20  receives the required radio resource information from the radio base station  10 , and notifies the required radio resource information holding unit  22  of the required radio resource information. The required radio resource information holding unit  22  holds the required radio resource information notified from the reception unit  21  as new required radio resource information. 
     The application server  40  receives the request message and transmits the required radio resource information corresponding to the message to the radio base station  10  through the network  30 . Note that, in present exemplary embodiment, the application server  40  distributes the application or performs management of information on the application including information on a radio resource required for the radio communication at the time of the application execution. The application server  40  updates the required radio resource information at arbitrary timing. 
       FIG. 5  illustrates a part of operations of the radio communication system and the application server  40  according to the third exemplary embodiment.  FIG. 5  is a sequential chart illustrating an example of the operations when the control unit  23  determines that the radio communication at the time of application execution is to be started. In  FIG. 5 , operations until it is determined that the radio communication at the time of application execution is to be started are the same as or similar to the operations of the radio communication system according to the first or second exemplary embodiments, and therefore the operations are not illustrated. 
     Hereinafter, operations of the radio base station  10 , the radio communication terminal  20 , and the application server  40  will be described with reference to  FIG. 5 . 
     The control unit  23  of the radio communication terminal  20  instructs the transmission unit  24  to transmit a request message to the radio base station  10  when it is determined that the radio communication at the time of application execution is to be started. The transmission unit  24  transmits the request message to the radio base station  10  (step S 301 ). 
     The reception unit  12  of the radio base station  10  receives the request message, and notifies the communication unit  13  of the message. The communication unit  13  transmits the request message to the application server  40  through the network  30  (step S 302 ). 
     The application server  40  receives the request message and transmits the required radio resource information corresponding to the message to the radio base station  10  through the network  30  (step S 303 ). 
     The communication unit  13  of the radio base station  10  receives the required radio resource information, and notifies the transmission unit  11  of the information. The transmission unit  11  transmits the required radio resource information to the radio communication terminal  20  (step S 304 ). 
     The reception unit  21  of the radio communication terminal  20  notifies the required radio resource information holding unit  22  of the required radio resource information. The required radio resource information holding unit  22  holds the required radio resource information, which is notified, as new required radio resource information (step S 305 ). 
     When newly executing an application, the radio communication terminal  20  performs the determination by the control unit  23  on the basis of the required radio resource information newly held in step S 305  (step S 306 ). 
     Note that, when the control unit  23  determines that the radio communication at the time of application execution is to be started, the application server  40  may transmit the required radio resource information to the radio communication terminal  20  using the start of radio communication at the time of application execution as a trigger, and the radio communication terminal  20  may receive and hold the required radio resource information. 
     In the radio communication system according to the present exemplary embodiment, when communication is started according to the control by the radio communication terminal, the required radio resource information holding unit  22  holds the required radio resource information transmitted from the application server as new required radio resource information. Therefore, the radio communication terminal can grasp more accurate and latest required radio resource information. As a result, it is possible to perform congestion control in the radio communication section with higher accuracy. 
     Fourth Exemplary Embodiment 
     In a radio communication system according to a fourth exemplary embodiment, a radio communication terminal  50  receives available radio resource information and required radio resource information after establishing a radio link with a radio base station  10 , and performs control of whether or not the radio communication is to be continued. 
       FIG. 6  is a drawing illustrating an example of the radio communication system according to the fourth exemplary embodiment. In the drawing, the radio communication system is basically the same as the radio communication system ( FIG. 4 ) in the third exemplary embodiment, but includes the radio communication terminal  50  instead of the radio communication terminal  20  illustrated in  FIG. 4 . Note that the radio base station  10  can perform radio communication with the radio communication terminal  50 , as is the case in the third exemplary embodiment. 
     The radio communication terminal  50  includes a transmission unit  51 , a reception unit  52 , and a control unit  53 . The transmission unit  51 , the reception unit  52 , and the control unit  53  are communicatively connected one another. 
       FIG. 6  illustrates components particularly relevant to the present exemplary embodiment among functional blocks included in the radio base station  10  and the radio communication terminal  50 , as is the case in  FIG. 4 . In other words, the radio base station  10  includes functional blocks (not illustrated) for causing the radio base station  10  to function as a radio base station. Similarly, the radio communication terminal  50  includes functional blocks (not illustrated) for causing the radio communication terminal  50  to function as a radio communication terminal. 
     The transmission unit  51  of the radio communication terminal  50  transmits at least one request message to the radio base station  10 . The request message is a message to request to transmit available radio resource information from the radio base station  10  to the radio communication terminal  50 , and a message to request to transmit required radio resource information from the application server  40  to the radio communication terminal  50 . 
     The reception unit  52  receives the available radio resource information and the required radio resource information from the radio base station  10 . The control unit  53  determines whether or not the radio communication at the time of application execution is to be continued, on the basis of the available radio resource information and the required radio resource information. 
       FIG. 7  is a sequence chart illustrating an example of an operation of the radio communication system according to the fourth exemplary embodiment. Note that, in  FIG. 7 , some of operations of the radio communication terminal  50  can be operated by an application installed in the radio communication terminal. Hereinafter, operations of the radio base station  10 , the radio communication terminal  50 , and the application server  40  will be described with reference to  FIG. 7 . 
     The radio communication terminal  50  activates an application in response to an operation by a user (step S 401 ). The radio communication terminal  50  also performs a predetermined operation for establishing a communication link with the radio base station  10 , the network  30 , and the application server  40 . The predetermined operation is, for example, a random access request, a channel allocation request, a call connection request, or the like. 
     According to an instruction by the application, the transmission unit  51  transmits a request message to the radio base station  10  (step S 402 ). 
     The reception unit  12  of the radio base station  10  receives the request message from the radio communication terminal  50 . The transmission unit  11  transmits the available radio resource information of the radio base station  10  to the radio communication terminal  50  in response to the message (step S 403 ). 
     The reception unit  52  of the radio communication terminal  50  receives the available radio resource information from the radio base station  10  (step S 404 ). 
     The reception unit  12  of the radio base station  10  notifies the communication unit  13  of the request message received from the radio communication terminal  50 , and the communication unit  13  transmits the message to the application server  40  through the network  30  (step S 405 ). 
     The application server  40  receives the request message from the communication unit  13 , and transmits the required radio resource information to the radio base station  10  through the network  30  in response to the message (step S 406 ). 
     The communication unit  13  of the radio base station  10  receives the required radio resource information from the application server, and notifies the transmission unit  11  of the required radio resource information. The transmission unit  11  transmits the required radio resource information, which is notified, to the radio communication terminal  50  (step S 407 ). 
     The reception unit  52  of the radio communication terminal  50  receives the required radio resource information from the radio base station  10  (step S 408 ). 
     Note that, in the present exemplary embodiment, the timing of transmission of the available radio resource information and the required radio resource information by the radio base station  10  is not a big issue, and therefore either one may be transmitted first or simultaneously. 
     The reception unit  52  notifies the control unit  53  of the received available radio resource information and required radio resource information. 
     The control unit  53  performs the determination whether or not the radio resource of the radio base station  10  has a sufficient available radio resource required for the radio communication at the time of application execution, on the basis of the acquired available radio resource information and required radio resource information (step S 409 ). 
     When the radio resource of the radio base station  10  has the sufficient available radio resource (Yes in step S 410 ), the radio communication to the radio base station  10  is continued (step S 411 ), and when not (No in step S 410 ), the radio communication to the radio base station  10  is stopped. 
     Note that, when the radio base station  10  does not have the sufficient available radio resource (No in step S 410 ), it may be notified to the application that the radio communication is to be stopped, or it may be notified that the application is to be terminated. The operations of steps S 402  to S 410  may be performed again after the elapse of a predetermined period of time or at predetermined timing. 
     In the radio communication system according to the present exemplary embodiment, the radio communication terminal requires the available radio resource information and the required radio resource information after establishing the radio link between the radio base station and the radio communication terminal, and performs the determination on the basis of the information. Therefore, it is not necessary to define a new sequence in a radio communication system, and it is possible to easily apply this system to existing systems. 
     Modification of Exemplary Embodiments 
     Various modifications can be considered in implementing the present invention, and the present invention is not limited to the above-described exemplary embodiments. 
     In the radio communication system of the first and second exemplary embodiments, the radio communication terminal  20  may further include a table storing at least one or more pieces of required radio resource information. 
     In that case, when the radio communication at the time of application execution is terminated, the radio communication terminal  20  stores information on the radio resource actually used for the radio communication by the application into the table. The required radio resource information holding unit  22  may hold a value determined on the basis of at least one or more pieces of stored information on the radio resource actually used, as the required radio resource information. 
     An example of a determination method is a method of calculating an average of radio resource quantities used in radio communication at the time of the past ten application executions, for example. 
     The required radio resource information is estimated using at least one or more pieces of information on the radio resources actually used, and therefore it becomes possible to perform more detailed congestion control. 
     Note that the radio communication system in which any of the exemplary embodiments mentioned above may be applicable to 3GPP LTE (Long Term Evolution), 3GPP W-CDMA (Wideband Code Division Multiple Access), GSM (registered trademark) (Global System for Mobile communications), WiMAX (Worldwide interoperability for Microwave Access), and the like, but not limited to these systems. 
     The radio communication system and the radio communication terminal described above can be realized by hardware, software, or a combination thereof. The control method of the radio communication system described above can be also realized by hardware, software, or a combination thereof. Here, “realized by software” means “realized by a computer that reads and executes a program”. 
     The program can be stored using various types of non-transitory computer readable medium to be provided into a computer. The non-transitory computer readable medium includes various types of tangible storage medium. 
     Examples of the non-transitory computer readable medium include a magnetic recording medium (such as a flexible disk, a magnetic tape, and a hard disk drive), an magneto-optical recording medium (such as a magneto-optical disc), a CD-ROM (Compact Disc-Read Only Memory), a CD-R (Compact Disc-Recordable), a CD-R/W (Compact Disc-Rewritable), a DVD-ROM (Digital Versatile Disc-ROM), a DVD-R (Digital Versatile Disc-Recordable), a DVD-R/W (Digital Versatile Disc-Rewritable), and a semiconductor memory (such as a mask ROM, a PROM (Programmable ROM), an EPROM (Erasable PROM), a flash ROM, and a RAM (Random Access Memory)). 
     In addition, the program may be provided to a computer by various types of transitory computer readable medium. Examples of the transitory computer readable medium include an electrical signal, an optical signal, and an electromagnetic wave. The transitory computer readable medium can provide a program to a computer through a wired communication path, such as an electric wire and an optical fiber, or a radio communication path. 
     The exemplary embodiments described above can be combined as appropriate to be implemented. The present invention is not limited to each exemplary embodiment described above, and can be implemented in various embodiments. 
     Note that some or all of the above-described exemplary embodiments can be described as the following supplementary notes, but not limited thereto. 
     (Supplementary Note 1) 
     A radio communication system comprising: 
     a radio communication terminal; and
 
a radio base station configured to perform radio communication with the radio communication terminal,
 
wherein the radio base station includes
 
     a transmission means for transmitting, to the radio communication terminal, available radio resource information which comprises information on an available radio resource of the radio base station, and 
     the radio communication terminal includes 
     a reception means for receiving the available radio resource information from the radio base station, 
     a holding means for holding required radio resource information which comprises information on a radio resource required for radio communication at application execution in the radio communication terminal, and 
     a control means for determining whether the radio communication at the application execution is to be started, based on the available radio resource information and the required radio resource information, at the application execution. 
     (Supplementary Note 2) 
     The radio communication system according to Supplementary Note 1, 
     wherein the transmission means notifies the available radio resource information to the radio communication terminal under the radio base station. 
     (Supplementary Note 3) 
     The radio communication system according to Supplementary Note 1 or 2, 
     wherein the holding means determines and holds the required radio resource information based on information on a radio resource used for previous radio communication by the application. 
     (Supplementary Note 4) 
     The radio communication system according to any one of Supplementary Notes 1 to 3, 
     wherein the control means determines again, when determined that the radio communication at the application execution is not to be started, whether the radio communication at the application execution is to be started after a predetermined time has elapsed. 
     (Supplementary Note 5) 
     The radio communication system according to any one of Supplementary Notes 1 to 3, 
     wherein the control means determines again, when determining that the radio communication at the application execution is not to be started, whether the radio communication at the application execution is to be started after reception of the available radio resource information by the reception means. 
     (Supplementary Note 6) 
     The radio communication system according to any one of Supplementary Notes 1 to 3, 
     wherein the radio communication system is connected with an application server through a network, and 
     wherein the holding means holds the required radio resource information transmitted from the application server. 
     (Supplementary Note 7) 
     A radio communication terminal configured to perform radio communication with a radio base station, the radio communication terminal comprising: 
     a reception means for receiving available radio resource information which comprises information on an available radio resource of the radio base station from the radio base station; 
     a holding means for holding required radio resource information which comprises information on a radio resource required for radio communication at application execution in the radio communication terminal; and 
     a control means for determining whether the radio communication at the application execution is to be started, based on the available radio resource information and the required radio resource information, at the application execution. 
     (Supplementary Note 8) 
     The radio communication terminal according to Supplementary Note 7, 
     wherein the holding means determines and holds the required radio resource information based on information on a radio resource used in previous radio communication by the application. 
     (Supplementary Note 9) 
     The radio communication terminal according to Supplementary Note 7 or 8, wherein the control means determines again, when it is determined that the radio communication at the time of the application execution is not to be started, whether or not the radio communication at the time of the application execution is to be started after the elapse of a predetermined period of time. 
     (Supplementary Note 10) 
     A control method of a radio communication system including a radio communication terminal and a radio base station that performs radio communication with the radio communication terminal, the control method including: 
     a reception step for receiving available radio resource information which is information on an available radio resource of the radio base station; 
     a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and 
     a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     (Supplementary Note 11) 
     The control method of the radio communication system according to Supplementary Note 10, wherein the reception step receives the available radio resource information notified to the radio communication terminal under the radio base station. 
     (Supplementary Note 12) 
     The control method of the radio communication system according to Supplementary Note 10 or 11, wherein the holding step determines and holds the required radio resource information on the basis of information on a radio resource used in previous radio communication by the application. 
     (Supplementary Note 13) 
     The control method of the radio communication system according to any one of Supplementary Notes 10 to 12, wherein the control step determines again, when it is determined that the radio communication at the time of the application execution is not to be started, whether or not the radio communication at the time of the application execution is to be started after the elapse of a predetermined period of time. 
     (Supplementary Note 14) 
     The control method of the radio communication system according to any one of Supplementary Notes 10 to 12, wherein the control step determines again, when it is determined that the radio communication at the time of the application execution is not to be started, whether or not the radio communication at the time of the application execution is to be started after reception of the available radio resource information by the receiving step. 
     (Supplementary Note 15) 
     The control method of the radio communication system according to any one of Supplementary Notes 10 to 12, wherein the radio communication system is connected with an application server through a network, and the holding step holds the required radio resource information transmitted from the application server. 
     (Supplementary Note 16) 
     A control method of a radio communication terminal performing radio communication with a radio base station, the control method including: 
     a reception step for receiving available radio resource information which is information on an available radio resource of the radio base station; 
     a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and 
     a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     (Supplementary Note 17) 
     The control method of the radio communication terminal according to Supplementary Note 16, wherein the holding step determines and holds the required radio resource information on the basis of information on a radio resource used in previous radio communication by the application. 
     (Supplementary Note 18) 
     The control method of the radio communication terminal according to Supplementary Note 16 or 17, wherein the control step determines again, when it is determined that the radio communication at the time of the application execution is not to be started, whether or not the radio communication at the time of the application execution is to be started after the elapse of a predetermined period of time. 
     (Supplementary Note 19) 
     A program causing a computer to implement a control method in a radio communication system including a radio communication terminal and a radio base station that performs radio communication with the radio communication terminal, the program causing a computer to execute: 
     a reception step for receiving available radio resource information which is information on an available radio resource of the radio base station, 
     a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal, and 
     a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     (Supplementary Note 20) 
     A program causing a computer to implement a control method of a radio communication terminal performing radio communication with a radio base station, the program causing a computer to execute: 
     a reception step for receiving available radio resource information which is information on an available radio resource of the radio base station; 
     a holding step for holding required radio resource information which is information on a radio resource required for radio communication at the time of application execution with the radio communication terminal; and 
     a control step for determining whether or not the radio communication at the time of the application execution is to be started, on the basis of the available radio resource information and the required radio resource information when executing the application. 
     (Supplementary Note 21) 
     A radio communication system including a radio communication terminal and a radio base station that performs radio communication with the radio communication terminal, and connecting with an application server through a network, wherein 
     the radio communication terminal includes 
     a transmission means for transmitting a transmission request to request available radio resource information which is information on an available radio resource of the radio base station and required radio resource information which is information on a radio resource required for radio communication at the time of application execution, 
     a reception means for receiving the available radio resource information transmitted from the radio base station in response to the transmission request, and the required radio resource information transmitted from the application server, 
     a control means for determining whether or not the radio communication at the time of the application execution is to be stopped, on the basis of the available radio resource information and the required radio resource information when executing the application which are received. 
     (Supplementary Note 22) 
     The radio communication system according to Supplementary Note 21, wherein the control means determines again, when it is determined that the radio communication at the time of the application execution is to be stopped, whether or not the radio communication at the time of the application execution is to be stopped after the elapse of a predetermined period of time. 
     The present application claims priority based on Japanese Patent Application No. 2013-201992, filed on Sep. 27, 2013, the entire disclosure of which is incorporated herein. 
     REFERENCE SIGNS LIST 
     
         
           10  Radio base station 
           11  Transmission unit 
           12  Reception unit 
           13  Communication unit 
           20 ,  50  Radio communication terminal 
           21 ,  52  Reception unit 
           22  Required radio resource information holding unit 
           23 ,  53  Control unit 
           24 ,  51  Transmission unit 
           30  Network 
           40  Application server