Patent Publication Number: US-2021168692-A1

Title: Relay apparatus, program, communication system, and communication method for handover connections

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Patent Application No. PCT/JP2019/014247 filed on Mar. 29, 2019, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a relay apparatus, a program, a communication system, and a communication method. 
     BACKGROUND 
     A movable relay apparatus which functions as a base station is known. 
     SUMMARY 
     A technology capable of appropriately supporting the operation of a relay apparatus is desired. 
     According to an aspect of the present disclosure a movable relay apparatus is provided for relay communication between a wireless base station and a communication terminal. The relay apparatus may include an information transmission part which transmits handover destination information (indicating a handover destination in which the communication terminal carries out handover without making a measurement report on the receiving radio waves) to the communication terminal (establishing a wireless communication connection with the relay apparatus). 
     The relay apparatus may include a movement determination part for determining whether or not the relay apparatus is moving, wherein the information transmission part may transmit the handover destination information to the communication terminal when the relay apparatus establishes a wireless communication connection with the communication terminal and it is determined that the relay apparatus has moved. The relay apparatus may include a movement speed determination part for determining whether or not the movement speed of the relay apparatus is faster than a predetermined speed, wherein the information transmission part may transmit the handover destination information to the communication terminal when the relay apparatus establishes a wireless communication connection with the communication terminal and it is determined that the movement speed of the relay apparatus is faster than the predetermined speed. The information transmission part may transmit, to the communication terminal, the handover destination information which indicates a wireless base station (with which the relay apparatus establishes the wireless communication connection) as the handover destination. 
     The relay apparatus may include a reception strength measurement part for measuring the radio wave reception strength from multiple movable relay apparatuses different from the relay apparatus, wherein the information transmission part may transmit, to the communication terminal, the handover destination information indicating a relay apparatus (having a stronger radio wave reception strength among the multiple movable relay apparatuses) as the handover destination. The relay apparatus may include a change determination part for determining temporal changes in the radio wave reception strength from multiple movable relay apparatuses different from the relay apparatus, wherein the information transmission part may transmit, to the communication terminal, the handover destination information indicating a relay apparatus (having a stronger radio wave reception strength and smaller temporal changes among the multiple movable relay apparatuses) as the handover destination. The relay apparatus may include a change determination part for determining temporal changes in the radio wave reception strength from multiple movable relay apparatuses different from the relay apparatus, wherein the information transmission part may transmit, to the communication terminal, the handover destination information indicating a relay apparatus (having smaller temporal changes among the multiple movable relay apparatuses) as the handover destination. 
     The relay apparatus may be installed in a vehicle. The information transmission part may transmit the handover destination information to the communication terminal in accordance with the state of the vehicle that is in a predetermined state. The vehicle may have an OFF state, a power ON state, and a drivable (or travelable) state, wherein the relay apparatus may execute a relay function for relaying communications between the wireless base station and the communication terminal when the vehicle is in the power ON state and the drivable state, and wherein the information transmission part may transmit the handover destination information to the communication terminal when the state of the vehicle switches from the power ON state to the drivable state. 
     According to an aspect of the present disclosure, a program is provided for allowing a computer to function as the relay apparatus. 
     According to an aspect of the disclosure, a communication system is provided. The communication system may include a movable relay part for relaying communications between a wireless base station and a communication terminal. The communication system may include an identification part for identifying a handover destination in which the communication terminal carries out handover without making a measurement report on the receiving radio waves. The communication system may include an information transmission part which notifies the communication terminal (establishing a wireless communication connection with the relay part) of handover destination information (indicating a handover destination identified by the identification part). 
     The communication system may include a state information acquisition part for acquiring state information of the relay part, wherein: the identification part may identify the handover destination when the relay part is in a first state, the information transmission part may notify the communication terminal of the handover destination information when the relay part is in a second state, the first state may be that in which the relay function of the relay part has been turned on, and the second state may be that in which the relay part is moving. The communication system may include a state information acquisition part for acquiring state information of the relay part, wherein: the identification part may update and identify the handover destination when the relay part is in a first state, the information transmission part may notify the communication terminal of the handover destination information when the relay part is in a second state, the first state may be that in which the current position of the relay part is a predetermined area, and the second state may be that in which the relay part moves beyond a predetermined speed. 
     According to an aspect of the disclosure, a communication method is provided. The communication method may include: identifying a handover destination in which the communication terminal (establishing movable wireless communication with a movable relay part for relaying communications between a wireless base station and a communication terminal) carries out handover from the relay part without making a measurement report on the receiving radio waves. The communication method may include: notifying the communication terminal (establishing a wireless communication connection with the relay part) of handover destination information (indicating a handover destination identified in the identification stage). 
     Note that the abovementioned summary of the present disclosure does not limit the present disclosure. Moreover, subcombinations of groups of these features may also be included in the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an exemplary communication system  10  in accordance with one aspect of the present disclosure. 
         FIG. 2  schematically illustrates an exemplary process flow in the communication system  10  in accordance with one aspect of the present disclosure. 
         FIG. 3  schematically illustrates an exemplary functional configuration of a relay apparatus  210  in accordance with one aspect of the present disclosure. 
         FIG. 4  schematically illustrates an exemplary process flow according to the relay apparatus  210  in accordance with one aspect of the present disclosure. 
         FIG. 5  schematically illustrates an exemplary process flow according to the relay apparatus  210  in accordance with one aspect of the present disclosure. 
         FIG. 6  schematically illustrates an exemplary functional configuration of the communication system  10  in accordance with one aspect of the present disclosure. 
         FIG. 7  schematically illustrates an exemplary process flow according to the communication system  10  in accordance with one aspect of the present disclosure. 
         FIG. 8  schematically illustrates an exemplary process flow according to the communication system  10  in accordance with one aspect of the present disclosure. 
         FIG. 9  schematically illustrates an exemplary hardware configuration of a computer  1200  functioning as the relay apparatus  210  in accordance with one aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Although the present disclosure will hereinafter be described with reference to the accompanying drawings, the following embodiments are not intended to limit the disclosure according to the claims. Moreover, not all of the combinations of features described in the embodiments are essential to the disclosure. Moreover, subcombinations of groups of these features may also be included in the present disclosure. 
       FIG. 1  schematically illustrates a non-limiting example of a communication system  10 . The communication system  10  includes a relay apparatus  210  for relaying communications between a wireless base station  100  and a communication terminal  300 . The relay apparatus  210  may be installed in a moving body. In the present embodiment, a case in which the relay apparatus  210  is installed in a vehicle  200  will be described as an example. The vehicle  200  equipped with the relay apparatus  210  may be referred to as a moving base station. The communication system  10  may include the vehicle  200 . The communication system  10  may include the wireless base station  100 . Other illustrative examples of the moving body include unmanned aircrafts such as drones. 
     The vehicle  200  may be an automobile. The vehicle  200  may be any type of automobile as long as it has a wireless communication function. For example, the vehicle  200  may be a gasoline powered vehicle or may also be a so-called eco-friendly vehicle. Types of eco-friendly cars include HVs (hybrid vehicles), PHEVs/PHVs (plug-in hybrid vehicles), EVs (electric vehicles), and FCVs (fuel cell vehicles). The vehicle  200  may be an automobile for any application. The vehicle  200  may be, for example, a private car or a vehicle for business such as a taxi or bus. 
     The wireless base station  100  may conform to any mobile communication system. The wireless base station  100  conforms, for example, to a 3G (3rd Generation) communication system. The wireless base station  100  conforms, for example, to a long term evolution (LTE) communication system. The wireless base station  100  may be an eNB (eNodeB). The wireless base station  100  may conform, for example, to a 5G (5th Generation) communication system. The wireless base station  100  may be an gNB (gNodeB). The wireless base station  100  may conform to a mobile communication system following a 6G (6th Generation) communication system. Here, the case in which the wireless base station  100  conforms to the LTE communication system will be mainly described as an example. 
     For example, the relay apparatus  210  is within the zone of a wireless communication area  102  generated by the wireless base station  100  so as to execute wireless communication with the wireless base station  100 . The fact that the relay apparatus  210  is within the zone of a wireless communication area  102  generated by the wireless base station  100  may mean that the relay apparatus  210  is located in the wireless communication area  102  so as to establish a wireless communication connection with the wireless base station  100 . 
     For example, the relay apparatus  210  generates a wireless communication area  202 , and then executes wireless communication with the communication terminal  300  which is within the zone of the wireless communication area  202 . The fact that the communication terminal  300  is within the zone of the wireless communication area  202  may mean that the communication terminal  300  is located in the wireless communication area  202  so as to establish a wireless communication connection with the relay apparatus  210 . Note that when the communication terminal  300  is within the zone of the wireless communication area  202  generated by the relay apparatus  210 , it may be described that the communication terminal  300  is within the zone of the relay apparatus  210 . 
     A movement communication system between the relay apparatus  210  and the communication terminal  300  may be the same as a moving body communication system between the relay apparatus  210  and the wireless base station  100 . Moreover, the moving body communication system between the relay apparatus  210  and the communication terminal  300  may be different from the moving body communication system between the relay apparatus  210  and the wireless base station  100 . 
     The communication terminal  300  may be any communication terminal as long as it has a wireless communication function. The communication terminal  300  is, for example, a mobile phone such as a smart phone, a tablet terminal, a wearable terminal, a PC (personal computer), etc. Moreover, the communication terminal  300  may be an IoT (Internet of thing) terminal. 
     When the vehicle  200  equipped with the relay apparatus  210  moves while the communication terminal  300  is within the zone of the relay apparatus  210 , the movement of the wireless communication area  202  may result in the communication terminal  300  falling outside of the wireless communication area  202 . If a handover of the communication terminal  300  is in time, the wireless communication connection of the communication terminal  300  is maintained; in contrast, if the handover is not in time, the wireless communication connection may be disconnected, likely deteriorating the user experience quality of the communication terminal  300 . 
     The relay apparatus  210  according to the present embodiment transmits handover destination information indicating a handover destination to the communication terminal  300 , which is within the zone of the relay apparatus  210 , without the communication terminal  300  making and sending in advanced a measurement report on the radio waves received by communication terminal  300 . The measurement report may be a so-called measurement report (also described as an MR). The case in which the communication terminal  300  carries out handover to the specified the handover destination, without making a measurement report on the received radio waves, may be described as an unmeasured handover. The case in which the communication terminal  300  receives handover destination information indicating a handover destination, without making a measurement report on the received radio waves, may be described as unmeasured handover destination information. 
     The relay apparatus  210  may transmit the unmeasured handover destination information to the communication terminal  300  when the likelihood that the communication terminal  300  will fall outside of the wireless communication area  202  of the relay apparatus increases. For example, when the vehicle  200  is stopped and the relay apparatus  210  is relaying communication between the wireless base station  100  and the communication terminal  300 , the relay apparatus  210  transmits the unmeasured handover destination information to the communication terminal  300  upon detecting the movement of the vehicle  200 . As a result, when the movement of the vehicle  200  increases the likelihood that the communication terminal  300  will fall outside of the wireless communication area  202 , the communication terminal  300  can quickly carry out handover to the handover destination (indicated by the unmeasured handover destination information) without making a measurement report, making it possible to reduce events in which the handover is not in time and the wireless communication connection thereby becomes disconnected. 
     In an unmeasured handover, the handover destination is specified without the terminal device  300  making a measurement report on radio waves received by the terminal device  300 . Therefore, it may be possible that a wireless base station in which the communication terminal  300  is not located in the wireless communication area is specified as the unmeasured handover destination. If this occurs, the communication terminal  300  may not be able to handover. 
     According to an exemplary embodiment, the relay apparatus  210  may transmit, to the communication terminal  300 , the unmeasured handover destination information indicating the wireless base station  100  in which the relay apparatus  210  is within the zone as the handover destination. When the relay apparatus  210  is located in the wireless communication area  102 , it is highly likely that the communication terminal  300  which is within the zone of the relay apparatus  210  is also located in the wireless communication area  102 . Therefore, the likelihood that the handover of the communication terminal  300  can be successful is very high. 
     The relay apparatus  210  may measure the radio wave reception strength of other multiple relay apparatuses  210 , and then transmit the unmeasured handover destination information, indicating a second relay apparatus  210  having stronger radio wave reception strength as the handover destination, to the communication terminal  300 . Moreover, the relay apparatus  210  may determine temporal changes in the radio wave reception strength from other multiple relay apparatuses  210 , and then transmit the unmeasured handover destination information, indicating the second relay apparatus  210  having less temporal changes in the radio wave reception strength among other multiple relay apparatuses  210  as the handover destination, to the communication terminal  300 . The relay apparatus  210  may transmit the unmeasured handover destination information, indicating the second relay apparatus  210  having stronger radio wave reception strength and less temporal changes in the radio wave reception strength among other multiple relay apparatuses  210  as the handover destination, to the communication terminal  300 . 
     When the radio wave reception strength from a second relay apparatus  210  is strong and the temporal changes in the radio wave reception strength are small, it is highly likely that this second relay apparatus  210  is located relatively close, stops, or is driving at a low speed. For example, when a first relay apparatus  210  installed in a first vehicle  200  measures the radio wave reception strength, it is highly likely that a second relay apparatus  210  (which is installed in a second vehicle  200  having strong radio wave reception strength and less temporal changes in the radio wave reception strength) is located relatively close to the first vehicle  200 , stops, or is driving at a low speed. It is highly likely that the communication terminal  300  which is within the zone of a first relay apparatus  210  is located in the wireless communication area  202  of the second relay apparatus  210 , wherein, even after the first relay apparatus  210  has moved, it is highly likely that it is located in the wireless communication area  202  of the second relay apparatus  210 . Consequently, by transmitting the unmeasured handover destination information, indicating a second relay apparatus  210  as the handover destination, to the communication terminal  300 , the likelihood that the handover of the communication terminal  300  can be successful is very high. 
       FIG. 2  schematically illustrates one example of the process flow in the communication system  10 . Here, a state in which the vehicle  200  stops and the communication terminal  300  is within the zone of the relay apparatus  210  will be described as the start state. 
     In Step  102  (the step may be abbreviated and described as S), the vehicle  200  starts moving. In S 104 , in accordance with the relay apparatus  210  which has detected the start of movement of the vehicle  200 , the relay apparatus  210  transmits, to the communication terminal  300 , the unmeasured handover destination information indicating the wireless base station  100 , in which the relay apparatus  210  is within the zone, as the handover destination. 
     In S 106 , the communication terminal  300  measures the radio wave reception strength from the relay apparatus  210 . At this point, the description continues as the radio wave reception strength from the relay apparatus  210  is higher than the handover threshold. 
     In S 108 , the communication terminal  300  measures the radio wave reception strength from the relay apparatus  210 . At this point, the description continues with the radio wave reception strength from the relay apparatus  210  lower than the handover threshold. 
     In S 110 , the handover process is executed, leading to the handover of the communication terminal  300 . In the example illustrated in  FIG. 2 , the communication terminal  300  carries out handover to the wireless base station  100  in which the relay apparatus  210  is within the zone. 
     The handover process system may be any system. For example, the handover process may be an X2 handover. In this case, in S 104 , after transmitting the unmeasured handover destination information to the communication terminal  300 , the relay apparatus  210  may transmit, to the handover destination, a request for the handover along with the terminal information of the communication terminal  300 . This request for the handover may be a request indicating that the communication terminal  300  may carry out handover to the wireless base station  100 . The wireless base station  100  stores the received request for the handover, and then waits for the request from the communication terminal  300 . In S 110 , the communication terminal  300  transmits the request for the handover to the wireless base station  100 , after which synchronous processing is carried out between the communication terminal  300  and the wireless base station  100 . Moreover, a request for switching a path is transmitted from the wireless base station  100  to an MME (mobility management entity)  22  in a core network  20 , wherein the MME  22  notifies the core side of the handover destination. In addition, the path is switched on the core side, completing the handover. Note that the handover process may be the S1 handover. 
       FIG. 3  schematically illustrates one non-limiting example of the functional configuration of a relay apparatus  210 . The relay apparatus  210  includes a base station communication part  212 , a terminal communication part  220 , a movement determination part  230 , a movement speed determination part  232 , a reception strength measurement part  234 , and a change determination part  236 . Note that it is not necessary for the relay apparatus  210  to include all of these configurations. 
     The base station communication part  212  wirelessly communicates with the wireless base station  100 . The terminal communication part  220  wirelessly communicates with the communication terminal  300 . The terminal communication part  220  has an identification part  221  and an information transmission part  222 . 
     The identification part  221  identifies the handover destination in which the communication terminal  300  (which is within the zone of the relay apparatus  210 ) carries out handover from the relay apparatus  210  without making a measurement report on the received radio waves. That is, the identification part  221  identifies the unmeasured handover destination of the communication terminal  300  which is within the zone of the relay apparatus  210 . 
     For example, the identification part  221  identifies the wireless base station  100  (in which the relay apparatus  210  is within the zone) as the handover destination. For example, the identification part  221  acquires the cell ID of the wireless base  100  (in which the relay apparatus  210  is within the zone) as information indicating the handover destination. The cell ID of the wireless base station  100  (in which the relay apparatus  210  is within the zone) may be managed by the base station communication part  212 , wherein the identification part  221  may acquire the cell ID from the base station communication part  212 . When the relay apparatus  210  is within a zone of a second wireless base station  100  different from the wireless base station  100  which has been within the zone, the identification part  221  may re-identify the second wireless base station  100  (which is newly within the zone) as the updated handover destination of the communication terminal  300 . 
     The information transmission part  222  transmits the unmeasured handover destination information to the communication terminal  300  which is within the zone of the relay apparatus  210 . For example, the information transmission part  222  transmits, to the communication terminal  300 , the unmeasured handover destination information, indicating the handover destination identified by the identification part  221 , as the handover destination. For example, the information transmission part  222  transmits a message (for example, RRC connection reconfiguration), including the specification of the handover destination as the unmeasured handover destination information, to the communication terminal  300 . 
     The relay apparatus  210  need not have the identification part  221 ; alternatively, the wireless base station  100  may have the identification part. The identification part possessed by the wireless base station  100  may identify the handover destination of the communication terminal  300  which is within the zone of the relay apparatus  210  (which is within the zone of the wireless base station  100 ). For example, this identification part identifies the wireless base station  100  (having this identification part) as the handover destination of the communication terminal  300  which is within the zone of the relay apparatus  210 . Note that another apparatus in a core network  20 , not the wireless base station  100 , may have the identification part. 
     The movement determination part  230  determines whether or not the relay apparatus  210  is moving. If the movement determination part  230  detects that a moving body equipped with the relay apparatus  210  is moving, it may determine that the relay apparatus  210  is moving; in contrast, if the movement determination part  230  detects that a moving body equipped with the relay apparatus  210  is not moving, it may determine that the relay apparatus  210  is not moving. 
     The information transmission part  222  may transmit the unmeasured handover destination information to the communication terminal  300  when the communication terminal  300  is within the zone of the relay apparatus  210  and the movement determination part  230  determines that the relay apparatus  210  is moving. 
     The movement speed determination part  232  determines whether or not a movement speed of the relay apparatus  210  is faster than a predetermined speed. If the movement speed of the moving body equipped with the relay apparatus  210  is faster than the predetermined speed, the movement speed determination part  232  may determine that the movement speed of the relay apparatus  210  is faster than the predetermined speed. If the movement speed of the moving body equipped with the relay apparatus  210  is slower than the predetermined speed, the movement speed determination part  232  may determine that the movement speed of the relay apparatus  210  is slower than the predetermined speed. 
     The information transmission part  222  may transmit the unmeasured handover destination information to the communication terminal  300  when the communication terminal  300  is within the zone of the relay apparatus  210  and the movement speed determination part  232  determines that the movement speed of the relay apparatus  210  is, for example, faster than the predetermined speed. 
     The reception strength measurement part  234  measures the radio wave reception strength from other multiple relay apparatuses  210 . The identification part  221  may identify a second relay apparatus  210  (having stronger radio wave reception strength among multiple relay apparatuses  210 ) as the handover destination. For example, the identification part  221  identifies the second relay apparatus  210  having the strongest radio wave reception strength among multiple relay apparatuses  210  as the handover destination. The information transmission part  222  may transmit the unmeasured handover destination information indicating the second relay apparatus  210  having stronger radio wave reception strength among multiple relay apparatuses  210  as the handover destination to the communication terminal  300 . For example, the information transmission part  222  transmits the unmeasured handover destination information indicating the second relay apparatus  210  having the strongest radio wave reception strength among multiple relay apparatuses  210  as the handover destination to the communication terminal  300 . For example, the relay apparatus  210  transmits a message (for example, RRC connection reconfiguration) including identification information for identifying the second relay apparatus  210  having a stronger radio wave reception strength as the handover destination to the communication terminal  300 . The identification information of the second relay apparatus  210  may be any information which may be able to identify the second relay apparatus  210  as the handover destination. 
     The change determination part  236  determines the temporal changes in the radio wave reception strength from the other multiple relay apparatuses  210 . The change determination part  236  may identify a second relay apparatus  210  having less or smaller temporal changes in the radio wave reception strength among the other multiple relay apparatuses  210 . 
     The identification part  221  may identify the second relay apparatus  210  having less or smaller temporal changes in the radio wave reception strength among multiple relay apparatuses  210  as the handover destination. For example, the identification part  221  may identify the second relay apparatus  210  having the smallest temporal changes in the radio wave reception strength as the handover destination. For example, the information transmission part  222  transmits the unmeasured handover destination information indicating the second relay apparatus  210  having the smaller temporal change in the radio wave reception strength among multiple relay apparatuses  210  as the handover destination to the communication terminal  300 . For example, the information transmission part  222  transmits the unmeasured handover destination information indicating the second relay apparatus  210  having the smallest temporal change in the radio wave reception strength as the handover destination to the communication terminal  300 . For example, the identification part  221  identifies the second relay apparatus  210  having a stronger radio wave reception strength and a smaller temporal change in the radio wave reception strength as the handover destination. For example, the information transmission part  222  transmits the unmeasured handover destination information indicating the second relay apparatus  210  having a stronger radio wave reception strength and a smaller temporal change in the radio wave reception strength as the handover destination to the communication terminal  300 . 
       FIG. 4  schematically illustrates one example of the process flow according to the relay apparatus  210 . Here, the state in which the communication terminal  300  is within the zone of the relay apparatus  210  and the relay apparatus  210  is stopped is regarded as the start state, and the process flow from the start state until the relay apparatus  210  transmits the unmeasured handover destination information to the communication terminal  300  will be schematically described. 
     In S 202 , the movement determination part  230  determines whether or not the relay apparatus  210  has started moving. If it is determined that it has started, the process proceeds to S 204 . 
     In S 204 , the information transmission part  222  acquires the cell ID of the wireless base station  100  in which the relay apparatus  210  is within the zone. For example, the information transmission part  222  determines that the relay apparatus  210  has started moving in S 202 , and then acquires the cell ID (identified by the identification part  221 ) from the identification part  221 . Before determining that the relay apparatus  210  has started moving in S 202 , the information transmission part  222  may acquire the cell ID (identified by the identification part  221 ) from the identification part  221 . The information transmission part  222  may acquire the cell ID (identified by the identification part possessed by the wireless base station  100 ) from this identification part. 
     In S 206 , the information transmission part  222  transmits, to the communication terminal  300 , the unmeasured handover destination information (including the cell ID acquired in S 204 , as the handover destination). The process is then finished. 
     Although  FIG. 4  describes an example in S 202  in which the movement determination part  230  determines whether or not the relay apparatus  210  has started moving, the movement speed determination part  232  may alternatively determine whether or not the movement speed of the relay apparatus  210  is faster than a predetermined speed. 
       FIG. 5  schematically illustrates one example of the process flow according to the relay apparatus  210 . Here, the points different from  FIG. 4  will mainly be described. 
     In S 302 , the movement determination part  230  determines whether or not the relay apparatus  210  has started moving. If it is determined that it has started, the process proceeds to S 304 . 
     In S 304 , the reception strength measurement part  234  measures the radio wave reception strength from other multiple relay apparatuses  210 . In S 306 , the change determination part  236  determines the temporal changes in the radio wave reception strength from the other multiple relay apparatuses  210 . 
     In S 308 , the information transmission part  222  identifies a second relay apparatus  210  having the smallest temporal change in the radio wave reception strength among the relay apparatuses  210  whose radio wave reception strength is stronger than a specific strength, and then transmits the unmeasured handover destination information indicating the identified second relay apparatus  210  as the handover destination to the communication terminal  300 . Note that the information transmission part  222  may identify a predetermined number of relay apparatuses  210  in the order of increasing radio wave reception strength, and from among the predetermined number identify the second relay apparatus  210  having the smallest temporal change in the radio wave reception strength, and transmit the unmeasured handover destination information indicating this second relay apparatus  210  as the handover destination to the communication terminal  300 . The process is then finished. 
       FIG. 6  schematically illustrates one example of the functional configuration of the communication system  10 . The communication system  10  includes a relay part  402 , a state information acquisition part  404 , an identification part  406 , and an information transmission part  408 . 
     The relay part  402  relays the communication between the wireless base station  100  and the communication terminal  300 . For example, the relay part  402  establishes a wireless communication connection with the wireless base station  100 , establishes a wireless communication connection with the communication terminal  300 , and relays communications between the wireless base station  100  and the communication terminal  300 . The relay part  402  is movable. The relay part  402  may be installed in the moving body. The relay part  402  is disposed, for example, in the relay apparatus  210 . 
     The state information acquisition part  404  acquires state information indicating the state of the relay part  402 . The state information acquisition part  404  is disposed, for example, in the relay apparatus  210  so as to acquire the state information of the relay part  402 . Moreover, for example, the state information acquisition part  404  may be disposed in the wireless base station  100  so as to receive the state information of the relay part  402  in the relay apparatus  210  (in which the wireless base station  100  is within the zone) from this relay apparatus  210 . 
     An identification part  406  identifies the handover destination (from communication with the relay part  402 ) of the communication terminal  300 , which carries out handover without making a measurement report on the received radio waves. That is, the identification part  406  identifies the unmeasured handover destination of the communication terminal  300  in which the relay part  402  relays the communication. For example, the identification part  406  identifies the wireless base station  100  (in which the relay part  402  is within the zone) as the unmeasured handover destination of the communication terminal  300 . The identification part  406  is disposed, for example, in the relay apparatus  210 . The identification part  406  is disposed, for example, in the wireless base station  100 . 
     An information transmission part  408  notifies the communication terminal  300 , which has established a wireless communication connection with the relay part  402 , of the handover destination information indicating the handover destination identified by the identification part  406 . The information transmission part  408  may transmit the unmeasured handover destination information indicating the unmeasured handover destination identified by the identification part  406  to the communication terminal  300  that has established a wireless communication connection with the relay part  402 . The information transmission part  408  is disposed, for example, in the relay apparatus  210 . 
     The identification part  406  may identify the handover destination of the communication terminal  300  that has established a wireless communication connection with the relay part  402  when the relay part  402  is in a first state. The information transmission part  408  may notify the communication terminal  300  of the handover destination information (indicating the handover destination identified by the identification part  406 ) when the relay part  402  is in a second state. The first state may be that in which the relay function of the relay part  402  has been turned on, while the second state may be that in which the relay part  402  is moving. That is, when the relay function of the relay part  402  has been turned on, the identification part  406  identifies the handover destination of the communication terminal  300  that has established a wireless communication connection with the relay part  402 . When the relay part  402  is moving, the information transmission part  408  transmits the handover destination information (indicating the handover destination identified by the identification part  406 ) to the communication terminal  300 . As a result, as the relay function has been turned on with the relay part  402  stopped, the identification part  406  identifies the handover destination. When the relay part  402  starts moving, the likelihood that the communication terminal  300  which has been within the zone of the relay part  402  will fall outside of the wireless communication area of the relay part  402  increases. Therefore, the information transmission part  408  can transmit the handover destination information to the communication terminal  300  while it is still within the zone of the relay part  402 . 
     The identification part  406  may update and identify the handover destination of the communication terminal  300  when the relay part  402  is in the first state, and the information transmission part  408  may notify the communication terminal  300  of the handover destination information (indicating the handover destination updated and identified by the identification part  406 ) when the relay part  402  is in the second state. The first state may be that in which the current position of the relay part  402  is in a predetermined area, while the second state may be that in which the relay part  402  has moved beyond a predetermined speed. The predetermined area may be an area outside the wireless communication area in which the relay part  402  was previously located. That is, if the current position of the relay part  402  is outside the wireless communication area which the relay part  402  was previously located, the identification part  406  updates and identifies the handover destination. For example, when the relay part  402  is located in the wireless communication area of a first wireless base station  100 , the identification part  406  identifies the first wireless base station  100  as the handover destination. When the relay part  402  moves to the wireless communication area of a second wireless base station  100 , the identification part  406  updates the handover destination, and then identifies the second wireless base station  100  as the handover destination. Then, if the relay part  402  moves beyond a predetermined speed, the information transmission part  408  transmits the handover destination information (indicating the handover destination updated and identified by the relay part  402 ) to the communication terminal  300  (which is within the zone of the relay part  402 ). As a result, for example, when the relay part  402  located in the wireless communication area of the second wireless base station  100  starts moving beyond the predetermined speed, and the likelihood that the communication terminal  300  (which is within the zone of the relay part  402 ) will fall outside of the wireless communication area of the relay part  402  increases, the information transmission part  408  can transmit the handover destination information indicating the second wireless base station  100  as the handover destination to the communication terminal  300  (which is within the zone of the relay part  402 ). Note that the predetermined speed at this time may be set to 0 (zero) kilometers per hour, or may be set to a faster speed. 
       FIG. 7  schematically illustrates one example of the process flow according to the communication system  10 . Here, the process ranging from the state of monitoring the state of the relay part  402  in which the relay function has been turned off, to the transmission of the handover destination information indicating the handover destination from the relay part  402  of the communication terminal  300  to the communication terminal  300  (which is within the zone of the relay part  402 ) will be described. 
     In S 402 , the state information acquisition part  404  acquires the state information of the relay part  402 . In S 404 , the state information acquisition part  404  determines whether or not the relay function of the relay part  402  has been turned on. If it is determined that it has been turned on, the process proceeds to S 406 . If it is determined that it has not been turned on, the process returns to S 402 . 
     In S 406 , the identification part  406  identifies the handover destination (from the relay part  402 ) of the communication terminal  300  which is within the zone of the relay part  402 . For example, the identification part  406  identifies (updates) the wireless base station  100  (in which the relay part  402  is within the zone) as the handover destination. 
     In S 408 , the state information acquisition part  404  acquires the state information of the relay part  402 . In S 410 , the state information acquisition part  404  determines whether or not the relay part  402  is moving. If it is determined that it is moving, the process proceeds to S 412 . If it is determined that it is not moving, the process returns to S 408 . 
     In S 412 , an information communication part  408  transmits the handover destination information (indicating the handover destination identified by the identification part  406  in S 406 ) to the communication terminal  300  which is within the zone of the relay part  402 . The process is then finished. 
       FIG. 8  schematically illustrates one example of the process flow according to the communication system  10 . Here, the process from the state of monitoring the state of the relay part  402  until the transmission of the handover destination information to the communication terminal  300  by the information transmission part  408  (when the relay part  402  is within the zone of the wireless communication area of a first wireless base station  100  and after this first wireless base station is identified as the unmeasured handover destination by identification part  406 ) will be described. 
     In S 502 , the state information acquisition part  404  acquires the state information of the relay part  402 . In S 504 , the state information acquisition part  404  determines whether or not the relay part  402  has moved to an area outside the wireless communication area of a first wireless base station  100  in which the relay part  402  was located. If it is determined that it has moved, the process proceeds to S 506 . If it is determined that it has not moved, the process returns to S 502 . Here, the description continues as the relay part  402  has moved into the wireless communication area of a second wireless base station  100 . 
     In S 506 , the identification part  406  identifies the handover destination (from the relay part  402 ) of the communication terminal  300  which is within the zone of the relay part  402 . For example, the identification part  406  identifies (updates) the second wireless base station  100  in which the relay part  402  is located within the zone as the handover destination. 
     In S 508 , the state information acquisition part  404  acquires the state information of the relay part  402 . In S 510 , the state information acquisition part  404  determines whether or not the relay part  402  is moving beyond a predetermined speed. If it is determined that it has moved beyond a predetermined speed, the process proceeds to S 512 . If it is determined that has not moved beyond a predetermined speed, the process returns to S 508 . 
     In S 512 , the information transmission part  408  transmits the handover destination information (indicating the handover destination identified (updated) by the identification part  406  in S 506 ) to the communication terminal  300  which is located within the zone of the relay part  402 . The process is then finished. 
       FIG. 9  schematically illustrates one example of a hardware configuration of a computer  1200  functioning as the relay apparatus  210 . A program installed in the computer  1200  can allow the computer  1200  to function as one or more “parts” of the apparatus according to the abovementioned embodiment, or allow the computer  1200  to execute an operation associated with the apparatus according to the abovementioned embodiment or the abovementioned one or more “parts,” and/or allow the computer  1200  to execute a process according to the abovementioned embodiment or stages of this process. Such a program may be executed by a central processing unit (CPU)  1212  in order for the computer  1200  to execute the specific operation associated with some or all of blocks of the flowchart and block diagram described in the present specification. 
     The computer  1200  according to this embodiment includes the CPU  1212 , a RAM  1214 , and a graphic controller  1216 , which are connected to each other by a host controller  1210 . The computer  1200  also includes input/output units such as a communication interface  1222 , a storage apparatus  1224 , a DVD drive  1226 , and IC card drive, wherein these are connected to a host controller  1210  via an input/output controller  1220 . The DVD drive  1226  may be a DVD-ROM drive, a DVD-RAM drive, etc. The storage apparatus  1224  may be a hard disk drive, a solid state drive, etc. The computer  1200  also includes the input/output unit of a legacy such as a ROM  1230  and a touch panel, with these connected to the input/output controller  1220  via an input/output chip  1240 . 
     The CPU  1212  operates according to the programs stored in the ROM  1230  and the RAM  1214 , thereby controlling each part. The graphic controller  1216  acquires image data (generated by the CPU  1212 ) in a frame buffer, etc. (provided in the RAM  1214 ) or in itself, such that the image data is displayed on a display device  1218 . The computer  1200  need not include the display device  1218 , in which case the graphic controller  1216  causes the image data to be displayed on an external display device. 
     The communication interface  1222  communicates with other electronic devices via a wireless communication network. The storage apparatus  1224  stores a program and data used by the CPU  1212  in the computer  1200 . The DVD drive  1226  reads a program or data from a DVD-ROM  1227 , etc. and provides it to the storage apparatus  1224 . The IC card drive reads a program and data from an IC card and/or writes the program and data in the IC card. 
     The ROM  1230  stores therein, a boot program, etc. (executed by the computer  1200  upon activation) and/or a program (dependent on the hardware of the computer  1200 ). The input/output chip  1240  may also connect various input/output units to the input/output controller  1220  via a USB port, etc. 
     The program is provided by a computer readable storage medium such as a DVD-ROM  1227  or an IC card. The program is read from a computer readable storage medium, installed on the storage apparatus  1224 , the RAM  1214 , or the ROM  1230  (which is also an example of a computer readable storage medium), and executed by the CPU  1212 . The information processing described in these programs is read by the computer  1200  so as to cause a linkage between a program and the abovementioned various types of hardware resources. The apparatus or method may be configured by implementing an operation or the processing of information in accordance with the use of the computer  1200 . 
     For example, if communication is executed between the computer  1200  and an external device, the CPU  1212  may execute a communication program loaded on the RAM  1214 , and then instruct the communication interface  1222  on communication processing based on the processing described in the communication program. The communication interface  1222  reads transmission data stored in a buffer region provided in a storage medium (such as the RAM  1214 , the storage apparatus  1224 , the DVD-ROM  1227 , or the IC card) under the control of the CPU  1212 , transmits the read transmission data to a network, or writes data (received from the network) in a reception buffer region, etc. (provided on the storage medium). 
     Moreover, the CPU  1212  may allow all or necessary parts of files or databases (stored on external storage media such as the storage apparatus  1224 , the DVD drive  1226  (DVD-ROM  1227 ), and the IC card) to be read by the RAM  1214 , and then execute various types of processing to data on the RAM  1214 . The CPU  1212  may then write back the processed data to the external recording medium. 
     Various types of information such as various types of programs, data, tables, and databases may be stored in a recording medium and undergo information processing. The CPU  1212  may execute various types of processing (including various types of operations, information processing, condition determination, conditional branching, unconditional branching, information retrieval/substitution, etc. which are described throughout the present disclosure and specified by the program instruction sequence) on data read from the RAM  1214 , and then write back the results to the RAM  1214 . Moreover, the CPU  1212  may retrieve information in a file, database, etc. in the recording medium. For example, if multiple entries, each having the attribute value of the first attribute associated with the attribute value of the second attribute, are stored in the storage medium, the CPU  1212  may retrieve an entry matching the conditions under which the attribute value of the first attribute is specified among the multiple entries, and then read the attribute value of the second attribute stored in the entry, thereby acquiring the attribute value of the second attribute associated with the first attribute satisfying predetermined conditions. 
     The programs or software modules described above may be stored on the computer  1200  or in a computer readable storage medium in the vicinity of the computer  1200 . Moreover, a recording medium such as a hard disk or RAM provided in a server system (which is connected to a dedicated communication network or the Internet) can be used as a computer readable storage medium, thereby providing the program to the computer  1200  via a network. 
     The blocks in the flowcharts and block diagrams in the abovementioned disclosure may represent “parts” of the apparatus having the stage of the process for executing an operation or the role of executing the operation. The specific stages and “parts” may be implemented by a programmable circuit (which is supplied along with computer readable instructions stored on a dedicated circuit and a computer readable storage medium) and/or a processor (which is supplied along with the computer readable instruction stored on the computer readable storage medium). The dedicated circuit may include digital and/or analog hardware circuits and may also include integrated circuits (ICs) and/or discrete circuits. The programmable circuit may include, for example, reconfigurable hardware circuits including a logical product, logical sum, exclusive logical sum, negative logical product, negative logical sum, other logical operations, flip-flops, registers, and memory elements (such as a field programmable gate array (FPGA) and a programmable logic array (PLA)). 
     The computer readable storage medium may include any tangible device capable of storing instructions executed by an appropriate device, so that the computer readable storage medium having the instructions stored therein includes products including the instruction which may be executed in order to create a mechanism for executing operations specified in the flowchart or block diagram. Exemplary computer readable storage media may include electronic storage media, magnetic storage media, optical storage media, electromagnetic storage media, semiconductor storage media, etc. More specific examples of computer readable storage media include floppy (registered trademark) disks, diskettes, hard disks, random access memories (RAMs), read-only memories (ROM), erasable programmable read-only memories (EPROMs or flash memories), electrical erasable programmable read-only memories (EEPROMs), static random access memories (SRAMs), compact disk read-only memories (CD-ROMs), digital versatile disks (DVDs), Blue-Ray (registered trademark) disks, memory sticks, integrated circuit cards, etc. 
     The computer readable instructions may include either a source code or object code described in any combination of one or more programming languages which include assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, status setting data, or object oriented programming languages (such as Smalltalk, JAVA (registered trademark), or C++), and conventional procedural programming languages (such as “C” programming language or similar programming language). 
     In order for processors or programmable circuits (of general purpose computers, special purpose computers, or other programmable data processing apparatuses) to execute computer readable instructions to create a mechanism for executing operations specified in flowcharts or block diagrams, the computer readable instructions may be provided locally or via a local area network (LAN), and a wide area network (WAN) such as the Internet, to processors or programmable circuits (of general purpose computers, special purpose computers, or other programmable data processing apparatuses). Exemplary processors include computer processors, processing units, microprocessors, digital signal processors, controllers, microcontrollers, etc. 
     Although the present disclosure has been described with reference to the embodiments, the technical scope of the present disclosure is not limited to the scope described in the abovementioned embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the abovementioned embodiments. It is apparent from the description of the claims that such modified or improved embodiments may also be included in the technical scope of the disclosure. 
     Note that the execution order of each process of operations, procedures, steps, stages, etc. in the apparatuses, systems, programs, and methods indicated in the Claims, Specification, and drawings is not particularly explicitly stated by “prior to,” “in advance,” etc.; moreover, unless the output of the previous processing is used in the following process, it may be achieved in any order. Although the operation flows in the Claims, Specification, and drawings are described using “first,” “next,” etc. for convenience, this does not require that the operation flows be carried out in this order.