Patent Publication Number: US-2015087283-A1

Title: Radio communication system, communication control apparatus, radio communication terminal, and communication control method

Description:
TECHNICAL FIELD 
     The present invention relates to a radio communication system including multiple radio communication terminals and a communication control apparatus which controls direct communication between the radio communication terminals, and also relates to a communication control apparatus, a radio communication terminal, and a communication control method. 
     BACKGROUND ART 
     Conventionally, Bluetooth (registered trademark) and ad-hoc mode of a wireless LAN are known as so-called Device-to-Device (D2D) communication that is a radio communication method in which multiple radio communication terminals (sometimes referred to simply as terminals hereinbelow) perform radio communication with each other directly without involving a radio base station or an access point. Such a radio method achieves short-range radio communication by using relatively-low radio transmission power. For this reason, it is difficult to use this radiocommunication method when the inter-terminal distance is long. In addition, in such a radio communication method, the radio transmission capacity is limited compared to a radio access network (e.g., UTRA (3G), E-UTRA (LTE), or GERAN (2G)) managed by a telecommunications carrier. 
     Against this background, it is being discussed to achieve the D2D communication by using a radio access network provided by a telecommunications carrier (e.g., Non-patent document 1). 
     In the case of using a radio access technology employed in such a radio access network, the terminals uses a frequency band which the telecommunications carrier is licensed to use by supervisory authorities, and therefore are enabled to output higher radio transmission power and achieve long-distance, large-capacity D2D communication without using resources on the network side such as a radio base station. Such a characteristic is considered particularly effective when the network side such as the radio base station is devastated by an earthquake or the like. In addition, when the D2D communication is achieved using the frequency band used in a radio access network (such as 2G, 3G, or LTE) managed by a telecommunications carrier, the terminals can perform the D2D communication without being equipped with a module for another type of radio communication (e.g., Bluetooth (registered trademark)), which offers advantages such as cost and size reductions for the terminals. 
     PRIOR ART DOCUMENT 
     Non-Patent Document 
     
         
         Non-patent document 1: “Key drivers for LTE success: Services Evolution,” September 2011, 3GPP, Internet URL: http://www.3gpp.org/ftp/Information/presentations/presentations — 2011/2011 — 09_LTE_Asia/2011_LTE-Asia — 3GPP_Service_evolution.pdf 
       
    
     SUMMARY OF THE INVENTION 
     However, performing D2D communication by using the radio access network provided by the telecommunications carrier has the following problem. Specifically, since such a radio access technology is on the assumption that radio communication is performed via a radio base station, the network side cannot control terminals at all when the terminals perform D2D communication. D2D communication uses a frequency band used in the radio access network managed by a telecommunications carrier. Hence, if D2D communication is permitted without control by the telecommunications carrier (network) side, there might be a risk of untoward influence such as interference to the radio access network managed by the telecommunications carrier. 
     Thus, the present invention has been made in view of such circumstances, and has an objective of providing a radio communication system, a communication control apparatus, a radio communication terminal, and a communication control method allowing direct communication between radio communication terminals (D2D communication) to be provided by using a radio access network such as LTE while controlling the radio communication terminals from the network side. 
     A first feature of the present invention is summarized as a radio communication system including: multiple radio communication terminals; and a communication control apparatus configured to control direct communication between the multiple radio communication terminals. Here, the communication control apparatus includes a broadcast information transmission unit configured to broadcast broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted, the multiple radio communication terminals each include a direct communication execution unit configured to start the direct communication based on the broadcast information received from the communication control apparatus, when the direct communication is permitted, the broadcast information transmission unit further sends configuration information on a communication environment necessary for the direct communication, to the predetermined communication area, and the direct communication execution unit establishes the communication environment necessary for the direct communication based on the configuration information received from the communication control apparatus. 
     A second feature of the present invention is summarized as a communication control apparatus which controls direct communication between multiple radio communication terminals, the communication control apparatus including a broadcast information transmission unit configured to broadcast broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted. Here, when the direct communication is permitted, the broadcast information transmission unit further sends configuration information on a communication environment necessary for the direct communication, to the predetermined communication area. 
     A third feature of the present invention is summarized as a radio communication terminal which executes direct communication with another radio communication terminal without involving a radio access network, the radio communication terminal including a direct communication execution unit configured to start the direct communication based on broadcast information received from a communication control apparatus, the broadcast information indicating whether or not the direct communication is permitted. Here, the direct communication execution unit establishes a communication environment necessary for the direct communication based on configuration information on the communication environment necessary for the direct communication, the configuration information being received from the communication control apparatus. 
     A fourth feature of the present invention is summarized as a communication control method for controlling direct communication between multiple radio communication terminals, the method including the steps of: a radio communication system broadcasting broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted; when the direct communication is permitted, the radio communication system sending configuration information on a communication environment necessary for direct communication, to the predetermined communication area; the radio communication terminals establishing the communication environment necessary for the direct communication based on the configuration information received from the radio communication system; and the radio communication terminals starting the direct communication based on the broadcast information and the configuration information received from the radio communication system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall schematic configuration diagram of a radio communication system  10  according to an embodiment of the present invention. 
         FIG. 2  is a functional block configuration diagram of a radio base station  100  according to the embodiment of the present invention. 
         FIG. 3  is a functional block configuration diagram of a terminal  400 A according to the embodiment of the present invention. 
         FIG. 4  is a diagram showing a communication sequence in which the terminal  400 A and a terminal  400 B execute direct communication based on broadcast information according to the embodiment of the present invention. 
         FIG. 5  is a functional block configuration diagram of a communication control apparatus  300  according to a modification of the present invention. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Next, an embodiment of the present invention will be described. Note that, in the following description of the drawings, same or similar reference signs denote same or similar elements and portions. In addition, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. 
     Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, the drawings also include portions having different dimensional relationships and ratios from each other. 
     (1) Overall Schematic Configuration of the Radio Communication System 
       FIG. 1  is an overall schematic configuration diagram of a radio communication system  10  according to this embodiment. As shown in  FIG. 1 , the radio communication system  10  includes a radio base station  100 , a billing system  200 , a communication control apparatus  300 , and multiple radio communication terminals  400 A,  400 B (terminals  400 A,  400 B hereinbelow). 
     The radio base station  100  performs operation conforming to a radio access technology (RAT) standardized by 3GPP, e.g., Long Term Evolution (LTE). In this embodiment, the radio base station  100  controls direct communication between the terminals  400 A,  400 B. More specifically, the radio base station  100  controls the direct communication by causing the radio base station  100  to transmit broadcast information indicating whether or not to permit communication between the terminal  400 A and the terminal  400 B without involving the radio base station  100 , i.e., without involving a radio access network. Note that the broadcast information for controlling direct communication between the terminal  400 A and the terminal  400 B may be broadcasted separately from multiple radio base stations, e.g., the radio base station  100  and another radio base station (not shown). 
     In this way, in the radio communication system  10 , direct communication between the terminal  400 A and the terminal  400 B is permitted based on the broadcast information from the radio access network side. In addition, when it is based on broadcast information from another radio base station (not shown), for example, direct communication may be permitted based on the broadcast information from the other radio base station even in an area not covered by the radio base station  100 . 
     The billing system  200  manages billing according to a communication application executed by the terminals  400 A,  400 B. In this embodiment in particular, the billing system  200  manages billing for device-to-device direct communication (D2D communication) executed between the terminals  400 A,  400 B. 
     The communication control apparatus  300  controls communication executed by the terminals  400 A,  400 B. Specifically, the communication control apparatus  300  controls communication executed by the terminals  400 A,  400 B by responding to the broadcast information sent from the radio base station  100  or a communication request sent from the terminals  400 A,  400 B. 
     The terminal  400 A and the terminal  400 B are each a User Equipment (UE) configured to execute radio communication conforming to a radio access technology such as LTE. The terminal  400 A ( 400 B) can perform communication with the terminal  400 B ( 400 A) via the radio base station  100 , and can perform direct communication with the terminal  400 B ( 400 A) without involving the radio base station  100 . Specifically, the terminal  400 A,  400 B determines whether direct communication is executable or not based on the broadcast information broadcasted from the radio base station  100 , and executes direct communication at a predetermined timing or any timing. Note that, for this determination, information notified of by the communication control apparatus  300  (e.g., a direct-communication permission notification) may be added as an element of determination. 
     (2) Functional Block Configuration of the Radio Communication System 
     Next, a functional block configuration of the radio communication system  10  is described. Specifically, functional block configurations of the radio base station  100  and the terminal  400 A ( 400 B) are described.  FIG. 2  is a functional block configuration diagram of the radio base station  100 , and  FIG. 3  is a functional block configuration diagram of the terminal  400 A. 
     (2.1) Radio Base Station  100   
     As shown in  FIG. 2 , the radio base station  100  includes a broadcast information setting unit  101  and a broadcast information transmission unit  103 . Note that in an example described in this embodiment, the radio base station  100  includes the functionality of a communication control apparatus which controls direct communication between the terminal  400 A and the terminal  400 B. 
     The broadcast information setting unit  101  sets various kinds of broadcast information to be sent to a cell C 1  formed by the radio base station  100 . In this embodiment, the broadcast information setting unit  101  includes information indicating direct communication is possible, in the broadcast information sent periodically. 
     The broadcast information setting unit  101  defines an area, in terms of distance, in which direct communication is executable (e.g., the cell C 1 ), and causes the broadcast information transmission unit  103  to send broadcast information indicating that direct communication is possible, toward that area. Note that the area (a predetermined radio communication area) is not limited to a unit of a cell, but may be set based on a unit of a sector, a tracking area, or a network. In addition, the broadcast information setting unit  101  can also include, in the broadcast information, timings for commanding start and end of direct communication by the terminals  400 A,  400 B. 
     The broadcast information transmission unit  103  sends broadcast information toward the predetermined radio communication area (e.g., the cell C 1 ). As the broadcast information, for example, SIB (System Information Block) can be used. In this embodiment, the broadcast information transmission unit  103  broadcasts the broadcast information indicating whether direct communication is permitted or not, to the cell C 1 . 
     When direct communication is permitted, the broadcast information transmission unit  103  also sends the cell C 1  configuration information on a communication environment necessary for direct communication. The configuration information contains a frequency band allowed for direct communication, the radio field intensity of radio signals, timing of origination by the terminal  400 A,  400 B (timing at which the direct communication is allowed to be performed), and the like. Note that the radio field intensity is desirably of a degree not causing interference to the radio communication between the radio base station  100  and the terminals  400 A,  400 B. The radio field intensity may be changed according to the distance between the terminal  400 A and the terminal  400 B. 
     As described, the broadcast information transmission unit  103  can send the predetermined radio communication area the configuration information containing a timing (time slot) at which direct communication can be executed, and the configuration information can contain a radio frequency band used for direct communication or the intensity of transmitted radio signals used for direct communication, an identifier (a telephone number, a terminal identifier, and a subscriber identifier) of a counterpart (terminating) terminal, and the like. 
     (2.2) Terminal  400 A 
     As shown in  FIG. 3 , the terminal  400 A includes a broadcast information reception unit  401 , a broadcast information retention unit  403 , and a direct communication execution unit  405 . Note that the terminal  400 B has a similar functional block configuration. 
     The broadcast information reception unit  401  receives broadcast information sent from the radio base station  100 . Specifically, the broadcast information reception unit  401  receives the broadcast information when the terminal  400 A performs position registration periodically via the radio base station  100 , is handed over, or roams into a new network. Alternatively, the broadcast information reception unit  401  can receive the broadcast information which is sent from the radio base station  100  in response to a request for starting direct communication sent from the direct communication execution unit  405 . 
     The broadcast information retention unit  403  retains the broadcast information received by the broadcast information reception unit  401 . Specifically, the broadcast information retention unit  403  retains the configuration information on direct communication contained in the broadcast information. 
     The direct communication execution unit  405  starts direct communication with the terminal  400 B based on the broadcast information received from the radio base station  100 . Specifically, the direct communication execution unit  405  establishes a communication environment necessary for direct communication, based on the broadcast information retained by the broadcast information retention unit  403  or on the configuration information on direct communication contained in the newest broadcast information received by the broadcast information reception unit  401 . Alternatively, the direct communication execution unit  405  may establish the communication environment necessary for direct communication based on configuration information received and accumulated in the broadcast information retention unit  403 . 
     Further, the direct communication execution unit  405  executes direct communication by sending radio signals at a predetermined timing based on the timing (time slot) at which direct communication is executable, which is contained in the configuration information. 
     (3) Operation of the Radio Communication System 
     Next, operation of the above-described radio communication system  10  is described.  FIG. 4  shows a communication sequence in which the terminals  400 A,  400 B execute direct communication based on broadcast information. 
     As shown in  FIG. 4 , the radio base station  100  sets an area where the terminals  400 A,  400 B can execute direct communication (S 10 ). Specifically, as described above, the radio base station  100  can set the area where direct communication is executable on a cell basis, a sector basis, a tracking area basis, or a network basis. Herein, direct communication is executable in the cell C 1 . 
     The radio base station  100  sends broadcast information toward the cell C 1 , the broadcast information containing configuration information on direct communication (such as a frequency band, the radio field intensity of radio signals, and the like) (S 20 ). 
     The terminals  400 A,  400 B stores therein the configuration information contained in the received broadcast information (S 30 ), and establishes a communication environment necessary for direct communication based on the configuration information (S 40 ). 
     Further, the terminal  400 A sends the radio base station  100  a request for staring direct communication with the terminal  400 B (S 50 ). The radio base station  100  determines whether or not the terminals  400 A,  400 B camp in the area where direct communication is possible (S 60 ). Herein, the radio base station  100  determines that direct communication is possible. The radio base station  100  transfers the request for staring direct communication to the communication control apparatus  300  (S 65 ). 
     The communication control apparatus  300  sends a direct communication permission notification (containing a timing for executing direct communication) to the terminal  400 A via the radio base station  100  (S 70 ). Based on the permission notification, the terminal  400 A starts direct communication with the terminal  400 B (S 80 ). 
     Meanwhile, for management of billing to the terminal  400 A (or the terminal  400 B) for the direct communication, the radio base station  100  notifies the billing system  200 , via the communication control apparatus  300 , that the terminal  400 A has started direct communication with the terminal  400 B (S 90 ). 
     When the direct communication with the terminal  400 B ends, the terminal  400 A notifies the radio base station  100  that the direct communication has ended (S 100 ). For management of billing to the terminal  400 A (or the terminal  400 B) for the direct communication, the radio base station  100  notifies the billing system  200 , via the communication control apparatus  300 , that the terminal  400 A has ended direct communication with the terminal  400 B (S 110 ). 
     (4) Advantageous Effects 
     According to the radio communication system  10 , broadcast information indicating whether direct communication is permitted or not is broadcasted from the radio base station  100  to the terminals  400 A,  400 B. Further, when direct communication is permitted, configuration information on a communication environment necessary for direct communication is broadcasted to terminals  400 A,  400 B. Then, the terminals  400 A,  400 B establish a communication environment necessary for direct communication based on the configuration information received from the radio base station  100 . 
     Hence, device-to-device direct communication (D2D communication) can be provided by using a radio access network such as LTE while controlling the terminals  400 A,  400 B from the network side. In other words, since direct communication can be executed while the terminals  400 A,  400 B are controlled from the network side, communication between the radio base station  100  and the terminals  400 A,  400 B is surely prevented from being affected (by interference or the like), enabling stable device-to-device direct communication. 
     (5) Other Embodiment 
     As described above, the details of the present invention have been disclosed by using the embodiment of the present invention. However, it should not be understood that the description and drawings which constitute part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be easily found by those skilled in the art. 
     For example, in the example described in the above embodiment of the present invention, the radio base station  100  includes the functionality of the communication control apparatus. Instead, this functionality may be included by an apparatus besides the radio base station  100 , e.g., the communication control apparatus  300  placed on the network (e.g., a Serving Gateway (SGW), a Packet Data Network Gateway (PGW), a Mobility Management Entity (MME), or a GGSN (Gateway GPRS Serving Node)). 
       FIG. 5  is a functional block configuration diagram of the communication control apparatus  300  according to a modification of the present invention. As shown in  FIG. 5 , the communication control apparatus  300  includes a broadcast information setting unit  301  and a broadcast information transmission unit  303 . The broadcast information setting unit  301  and the broadcast information transmission unit  303  correspond to the broadcast information setting unit  101  and the broadcast information transmission unit  103  of the radio base station  100 , respectively. To be specific, the broadcast information setting unit  301 , like the broadcast information setting unit  101 , sets broadcast information to be sent to the terminals  400 A,  400 B. The broadcast information transmission unit  103  sends the broadcast information to the terminals  400 A,  400 B. 
     The above-described processing in Steps S 60  and S 70  shown in  FIG. 4  is not essential, and the terminal  400 A may start direct communication with the terminal  400 B without notifying the radio base station  100  of the start of the direct communication with the terminal  400 B. 
     In case the radio access network is damaged by disaster or the like, the terminals  400 A,  400 B may start direct communication autonomously based on broadcast information (configuration information) stored in the terminals  400 A,  400 B in advance. 
     As described above, the present invention naturally includes various embodiments which are not described herein. Accordingly, the technical scope of the present invention should be determined only by the matters to define the invention in the scope of claims regarded as appropriate based on the description. 
     The features of the present invention may also be expressed as follows. A first feature of the present invention is summarized as a radio communication system  10  including: multiple terminals  400 A,  400 B; and a communication control apparatus (a radio base station  100 ) configured to control direct communication between the multiple radio communication terminals. Here, the communication control apparatus includes a broadcast information transmission unit  103  configured to broadcast broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted, the multiple radio communication terminals each include a direct communication execution unit  405  configured to start the direct communication based on the broadcast information received from the communication control apparatus, when the direct communication is permitted, the broadcast information transmission unit further sends configuration information on a communication environment necessary for the direct communication, to the predetermined communication area, and the direct communication execution unit establishes the communication environment necessary for the direct communication based on the configuration information received from the communication control apparatus. 
     In the first feature of the present invention, the broadcast information transmission unit may send the configuration information containing a time slot at which the direct communication is executable, to the predetermined radio communication area, and the direct communication execution unit may execute the direct communication based on the time slot contained in the configuration information received from the communication control apparatus. 
     In the first feature of the present invention, the configuration information may contain at least one of a radio frequency band and a radio field intensity of radio signals, which are to be used for the direct communication. 
     A second feature of the present invention is summarized as a communication control apparatus  300  which controls direct communication between multiple radio communication terminals, the communication control apparatus  300  including a broadcast information transmission unit  303  configured to broadcast broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted. Here, when the direct communication is permitted, the broadcast information transmission unit further sends configuration information on a communication environment necessary for the direct communication, to the predetermined communication area. 
     A third feature of the present invention is summarized as a radio communication terminal  400 A ( 400 B) which executes direct communication with another radio communication terminal without involving a radio access network, the radio communication terminal including a direct communication execution unit  405  configured to start the direct communication based on broadcast information received from a communication control apparatus (for example, a radio base station  100 ), the broadcast information indicating whether or not the direct communication is permitted. Here, the direct communication execution unit establishes a communication environment necessary for the direct communication based on configuration information on the communication environment necessary for the direct communication, the configuration information being received from the communication control apparatus. 
     A fourth feature of the present invention is summarized as a communication control method for controlling direct communication between multiple radio communication terminals, the method including the steps of: a radio communication system broadcasting broadcast information to a predetermined radio communication area, the broadcast information indicating whether or not the direct communication is permitted; when the direct communication is permitted, the radio communication system sending configuration information on a communication environment necessary for direct communication, to the predetermined communication area; the radio communication terminals establishing the communication environment necessary for the direct communication based on the configuration information received from the radio communication system; and the radio communication terminals starting the direct communication based on the broadcast information and the configuration information received from the radio communication system. 
     Note that the entire content of Japanese Patent Application No. 2012-095077 (filed on Apr. 18, 2012) is incorporated by reference in the present specification. 
     INDUSTRIAL APPLICABILITY 
     According to the aspects of the present invention, what can be provided are a radio communication system, a communication control apparatus, a radio communication terminal, and a communication control method allowing direct communication between radio communication terminals (D2D communication) to be provided by using a radio access network such as LTE with while controlling the radio communication terminals from the network side. 
     EXPLANATION OF THE REFERENCE NUMERALS 
     
         
         
           
               10  radio communication system 
               100  radio base station 
               101  broadcast information setting unit 
               103  broadcast information transmission unit 
               200  billing system 
               300  communication control apparatus 
               400 A,  400 B radio communication terminal 
               401  broadcast information reception unit 
               403  broadcast information retention unit 
               405  direct communication execution unit