Communication apparatus, communication method, control circuit, and storage medium

Abstract

A communication device (1) has a function of performing direct communication with a communication terminal, which is another communication device, and is provided with: a base station search unit (31) that searches for a base station capable of direct communication; a communication control unit (33) that constructs a communication path having a redundant structure by performing a connection process with the base station searched by the base station search unit (31); and a communication terminal search unit (32) that searches for a communication terminal that has been connected to the base station, the communication control unit (33) establishing indirect communication with the base station via the communication terminal searched by the communication terminal search unit (32) when the number of established direct communication with the base station does not satisfy the number required to establish a communication path having a redundant structure, and the communication control unit (33) establishing communication with the base station via the communication terminal searched by the communication terminal search unit (32) when the number of established direct communication with the base station does not satisfy the number required to establish a communication path having a redundant structure. And thus, a communication path with a redundant structure is constructed.

Description

Technical Field

[0001] The present disclosure relates to a communication device, a communication method, a control circuit, and a storage medium. Background Art

[0002] As a means for achieving fully autonomous driving (autonomous driving Level 4) of a car in a specific environment, dynamic mapping is considered to superimpose dynamic information including the status of surrounding moving objects on a three-dimensional map as static information. The communication required for the implementation of dynamic mapping requires highly reliable communication compared to normal communication. Therefore, in 3GPP (registered trademark) (3rd Generation Partnership Project: Third Generation Partnership Project), a redundant structure for a communication device installed in a car to communicate with multiple base stations is studied, which can achieve highly reliable communication by sending dynamic information through multiple paths.

[0003] On the other hand, if a redundant structure with multiple base stations cannot be implemented due to communication environment, number of hosts, geographical issues, etc., in this case, communication interruption and degraded operation must be considered. When operating under communication interruption and degraded operation, sufficient reliability cannot be ensured, so alternative redundant means are required.

[0004] As a technique for solving this problem, Non-Patent Document 1 discloses a redundant structure that combines direct communication with a base station and indirect communication with a base station using relays by other mobile stations.

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-patent document 1: 3GPP TR 23.700-33, "Study on system enhancement for Proximity based Services (ProSe) in the 5G System (5GS); Phase 2" Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, the technology described in non-patent document 1 can only realize indirect communication via a mobile station designated by a base station, and a method for selecting a mobile station for relay processing for realizing indirect communication from a mobile station side for realizing a redundant structure is not described in non-patent document 1. In the case of a car using dynamic mapping, if a mobile station for realizing indirect communication is not directly selected on the communication device side mounted on the car, the provision of dynamic information is delayed due to the influence of communication delay, and the delay required by dynamic mapping cannot be realized.

[0010] The present disclosure is completed in view of the above situation, and its purpose is to obtain a communication device that realizes the following communication system: when a redundant structure of a communication path is realized by combining direct communication and indirect communication, a relay station that implements relay processing of indirect communication can be selected on the mobile station side that wishes to realize the redundant structure.

[0011] Means used to solve problems

[0012] In order to solve the above problems and achieve the purpose, the present disclosure provides a communication device having a function of directly communicating with a communication terminal as another communication device, the communication device comprising: a base station search unit, which searches for a base station that can directly communicate; a communication control unit, which implements a connection process with the base station searched by the base station search unit, thereby constructing a communication path of a redundant structure; and a communication terminal search unit, which searches for a communication terminal that has been connected to the base station. When the number of direct communications established with the base station does not meet the number required to construct a communication path of a redundant structure, the communication control unit establishes indirect communication with the base station via the communication terminal searched by the communication terminal search unit to construct a communication path of a redundant structure.

[0013] Effects of the Invention

[0014] The communication device of the present disclosure has an effect of realizing a communication system in which, when a redundant structure of a communication path is realized by combining direct communication and indirect communication, a relay station that performs relay processing of indirect communication can be selected on the mobile station side that wishes to realize the redundant structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing a configuration example of a communication system according to Embodiment 1.

[0016] Figure 2 This is a diagram showing an example of a functional block configuration of a communication device according to Embodiment 1 that realizes a mobile station.

[0017] Figure 3 This is a diagram showing an example of the operation flow of the communication system according to the first embodiment.

[0018] Figure 4This is a flowchart showing an example of the operation of the mobile station according to the first embodiment.

[0019] Figure 5 This is a diagram showing a configuration example of a communication system according to the second embodiment.

[0020] Figure 6 This is a diagram showing an example of the operation flow of the communication system according to the second embodiment.

[0021] Figure 7 This is a diagram showing an example of the operation flow of the communication system according to the third embodiment.

[0022] Figure 8 This is a flowchart showing an example of the operation of the mobile station according to the third embodiment.

[0023] Fig. 9 This is a diagram showing a configuration example of a communication system according to a fourth embodiment.

[0024] Fig.10 This is a diagram showing an example of the operation flow of the communication system according to the fourth embodiment.

[0025] Fig.11 This is a flowchart showing an example of the operation of the mobile station according to the fourth embodiment.

[0026] Fig.12 This is a diagram showing a configuration example of a processing circuit in which a communication unit of a communication device is realized by a processor and a memory. DETAILED DESCRIPTION

[0027] Hereinafter, a communication device, a communication method, a control circuit, and a storage medium according to an embodiment of the present disclosure will be described in detail based on the drawings.

[0028] Implementation method 1.

[0029] Figure 1 1 is a diagram showing a configuration example of a communication system 101 according to Embodiment 1. The communication system 101 is a 5G communication system, and more specifically, is a 5G communication system that is equipped with the indirect communication function described in the above-mentioned non-patent document 1 and is capable of constructing a redundant configuration using the indirect communication function.

[0030] The communication system 101 includes base stations 11-1 and 11-2 and mobile stations 12 and 13. The mobile stations 12 and 13 have a function of directly communicating without going through the base station, and can act as relay stations that relay signals between the base station in connection and the other station in direct communication. Figure 1Among the components of the communication system 101, only the components necessary for describing the first embodiment are described. For example, descriptions of base stations other than the base stations 11-1 and 11-2, mobile stations other than the mobile stations 12 and 13, and a core network connected to the base stations 11-1 and 11-2 are omitted.

[0031] The base station 11-1 is a base station that directly communicates with the mobile station 12. The base station 11-2 is a base station that directly communicates with the mobile station 13, but is in a state where it cannot directly communicate with the mobile station 12.

[0032] Mobile station 12 is a mobile station that wishes to implement a redundant structure of a communication path, and is a mobile body such as a car equipped with a communication device of embodiment 1. That is, mobile station 12 is composed of a mobile body and a communication device mounted on the mobile body. Mobile station 12 is a mobile station that is required to perform mission-critical communications such as dynamic mapping. Mobile station 12 wants to implement a redundant structure, but cannot implement direct communication with multiple base stations, so it wants to implement a redundant structure that uses indirect communication via surrounding mobile stations. In this embodiment, mobile station 12 is in a state where direct communication with base station 11-1 can be implemented but direct communication with base station 11-2 cannot be implemented. Therefore, mobile station 12 implements indirect communication with base station 11-2 via mobile station 13 that can implement direct communication with base station 11-2.

[0033] Mobile station 13 is composed of a mobile body and a communication device mounted on the mobile body, similarly to mobile station 12. Mobile station 13 performs direct communication with base station 11-2, and operates as a relay station that performs relay processing when mobile station 12 performs indirect communication with base station 11-2.

[0034] Figure 2 This is a diagram showing an example of a functional block configuration of the communication device 1 according to the first embodiment that realizes the mobile stations 12 and 13 .

[0035] like Figure 2 As shown, the communication device 1 of Embodiment 1 includes a wireless unit 20 for transmitting and receiving wireless signals with other communication devices, and a communication unit 30 for transmitting and receiving control signals and data signals with other communication devices via the wireless unit 20. The communication device 1 is configured to be able to communicate with multiple other communication devices at the same time. That is, the wireless unit 20 can transmit wireless signals to multiple other communication devices at the same time, and the communication unit 30 can communicate with multiple other communication devices at the same time. The communication unit 30 includes: a base station search unit 31 for searching for base stations that can communicate directly, a communication terminal search unit 32 for searching for communication terminals such as mobile bodies equipped with other communication devices that can communicate directly, and a communication control unit 33 for controlling communication operations with base stations and communication terminals.

[0036] In addition, in mobile stations 12 and 13, communication processing is performed between the communication device 1 and base stations 11-1, 11-2, etc. having communication functions. However, in order to prevent the description from becoming complicated, in the following description, mobile stations 12 and 13 are described as the execution subjects of the communication processing.

[0037] Next, the operation of the communication system 101 will be described. Specifically, a direct communication between the mobile station 12 and the base station 11-1 and an indirect communication between the mobile station 12 and the base station 11-2 via the mobile station 13 are combined to form a communication system. Figure 1 The operation of the redundant structure shown is described below.

[0038] Figure 3 1 is a diagram showing an example of the operation flow of the communication system 101 according to the first embodiment. Figure 3 This is a sequence diagram showing an example of an operation in which, when a redundant communication path is constructed between the mobile station 12 and the base station, the mobile station 12 takes the lead in starting indirect communication with the base station 11-2 to make the communication path redundant.

[0039] exist Figure 3 In the redundant operation of the communication path shown, first, in order to realize a redundant structure by direct communication, the mobile station 12 transmits a direct communication request to the base stations 11 - 1 and 11 - 2 (step S11 ).

[0040] At this time, it is assumed that in response to the direct communication request from the mobile station 12, only the base station 11-1 accepts the request and sends a direct communication approval back to the mobile station 12, and the direct communication is established (step S12). In addition, it is assumed that there are no base stations other than the base stations 11-1 and 11-2 within the range in which the mobile station 12 can directly communicate. Figure 3 In the above, the base station 11-2 does not send a response signal to the mobile station 12, but may send a response signal rejecting the direct communication request. If no response signal rejecting the direct communication request is sent from the base station 11-2, the mobile station 12 determines that the direct communication request is rejected at a point in time when a fixed time has passed since the direct communication request was sent in step S11.

[0041] Since the mobile station 12 cannot establish direct communication with the base station 11-2, it switches to establish a redundant structure that also uses indirect communication. Then, the mobile station 12 searches for surrounding mobile stations and selects a mobile station that requests indirect communication from the found mobile stations (step S13). When searching for surrounding mobile stations, the mobile station 12 also collects information about base stations connected to the mobile station. That is, the mobile station 12 obtains information about base stations that have established direct communication with the found mobile station from each mobile station found by the search.

[0042] Here, the mobile station 12 selects the mobile station 13 connected to the base station 11-2. The mobile station 12 transmits a direct communication request including an indirect communication request with the base station 11-2 to the selected mobile station 13 (step S14). In step S14, the direct communication request transmitted by the mobile station 12 is a request for direct communication with the mobile station 13.

[0043] The mobile station 13 receives the direct communication request received from the mobile station 12, and sends a relay communication request for the data of the mobile station 12 to the base station 11-2 that performs direct communication (step S15). In addition, there may be a case where the mobile station 13 rejects the direct communication request from the mobile station 12, but the action when rejecting is beyond the scope of this disclosure, so the description is omitted. Similarly, there may be a case where the base station 11-2 rejects the relay communication request from the mobile station 13, but the action when rejecting is beyond the scope of this disclosure, so the description is omitted.

[0044] The base station 11-2 receives the relay communication request received from the mobile station 13 and returns a relay communication approval (step S16). When the mobile station 13 receives the relay communication approval from the base station 11-2, it sends a direct communication approval to the mobile station 12 in response to the direct communication request from the mobile station 12 (step S17). At this time, the mobile station 13 also sends an approval to the indirect communication request with the base station 11-2. That is, in step S17, the mobile station 13 sends a direct communication approval including an approval to the indirect communication request with the base station 11-2 to the mobile station 12. As a result, indirect communication is established between the base station 11-2 and the mobile station 12 via the mobile station 13.

[0045] By operating as described above, the mobile station 12 that cannot realize a redundant structure based on direct communication with the base station 11 - 2 can select an appropriate mobile station 13 from the surrounding mobile stations and establish indirect communication with the base station 11 - 2 via the selected mobile station 13 .

[0046] Here, if the operation of the mobile station 12 of the communication system 101 according to the first embodiment is shown in a flowchart, Figure 4 Like that. Figure 4 This is a flowchart showing an example of the operation of the mobile station 12 according to the first embodiment.

[0047] When establishing a redundant communication path with a base station, the mobile station 12 first searches for a base station within a range where direct communication is possible (step S1). Specifically, the base station search unit 31 sends a signal for base station search and finds a base station with which direct communication is possible by receiving a response signal to the signal.

[0048] The mobile station 12 then performs a connection process with the base station (step S2). Specifically, the communication control unit 33 selects two base stations for constructing a redundant communication path from the base stations found by the base station search unit 31, and performs a process for connecting to the selected two base stations. When the base station search unit 31 finds three or more base stations, the communication control unit 33 selects, for example, two base stations with good wireless communication quality, for example, two base stations with high power of received signals. In addition, the selection method is not limited to this.

[0049] When the mobile station 12 successfully connects to the two base stations (step S3: Yes), a redundant structure based on the communication path of direct communication with the two base stations can be constructed, and thus the operation is terminated.

[0050] When the mobile station 12 fails to connect to the two base stations, that is, when the connection to at least one of the two selected base stations fails (step S3: No), the mobile station 12 searches for a communication terminal (step S4). Specifically, the communication terminal search unit 32 searches for a communication terminal such as a surrounding mobile station that can directly communicate. In addition, the communication terminal does not need to be a mobile station, and may be, for example, a roadside machine installed on a road. When searching for a communication terminal, the communication terminal search unit 32 collects information on a base station that has established direct communication with the searched communication terminal.

[0051] The mobile station 12 selects a communication terminal to be entrusted with the action of a relay station for implementing relay processing from the communication terminals found in step S4, and implements the connection processing to the base station via the selected communication terminal (step S5). In detail, the communication control unit 33 selects a communication terminal directly connected to the base station that failed to connect in step S2, and entrusts the selected communication terminal with the action of a relay station for implementing indirect communication with the base station. When there are multiple communication terminals directly connected to the base station that failed to connect in step S2, the communication control unit 33 selects any one of the communication terminals. In this case, the communication control unit 33 selects a communication terminal that can implement indirect communication with good communication quality, for example, based on the wireless communication quality between the mobile station 12 and each communication terminal and the wireless communication quality between each communication terminal and the base station. The mobile station 12 ends the action when the connection with the selected communication terminal is completed and indirect communication with the base station via the selected communication terminal can be carried out.

[0052] In addition, when the mobile station 12 finds more than three base stations in the above-mentioned step S1 and fails to connect to the two selected base stations in step S2, it may reselect a base station as a connection destination and perform the connection process again. When the mobile station 12 attempts to connect to all the base stations found in step S1 but the number of base stations successfully connected is less than one, it executes step S4. In addition, when the mobile station 12 fails to connect to all the base stations attempted to connect to in step S2, that is, when there is no base station that can communicate directly, it may establish two communication paths using indirect communication with the base stations in step S5.

[0053] In addition, in the above-mentioned step S5, the mobile station 12 selects a communication terminal directly connected to the base station that failed to connect in step S2 and entrusts the operation as a relay station, but may select a communication terminal directly connected to a base station different from the base station that failed to connect in step S2. For example, the mobile station 12 may preferentially select a communication terminal that can achieve indirect communication with good communication quality without considering whether it is a communication terminal directly connected to the base station that failed to connect in step S2.

[0054] As described above, in the communication system 101 of the present embodiment, when the mobile station 12 that wishes to make the communication path redundant cannot establish direct communication with each of the multiple base stations to achieve a redundant structure, it searches for a communication terminal that has established direct communication with the base station, establishes direct communication with the found communication terminal, and thereby establishes indirect communication with the base station via the communication terminal to build a redundant structure. Thus, when the redundant structure of the communication path is achieved using indirect communication, the mobile station 12 can select a communication terminal that acts as a relay station that performs relay processing for indirect communication.

[0055] Implementation method 2.

[0056] Figure 5 1 is a diagram showing a configuration example of a communication system 102 according to Embodiment 2. The communication system 102 has the same configuration as the communication system 101 according to Embodiment 1, but the base station with which the mobile station 12 performs indirect communication is different from that in Embodiment 1. Specifically, in the communication system 102 according to Embodiment 2, the mobile station 12 performs indirect communication with the base station 11-1 via the mobile station 13. That is, the mobile station 12 performs indirect communication with the base station 11-1 via the mobile station 13 while performing direct communication with the base station 11-1.

[0057] Figure 6 1 is a diagram showing an example of the operation flow of the communication system 102 according to Embodiment 2. Figure 61 is a sequence diagram showing an example of an operation of making the communication path redundant by starting indirect communication with the base station 11-1 with the mobile station 12 as the lead when a redundant communication path is constructed between the mobile station 12 and the base station. Figure 6 In the Figure 3 The same processing as that described in the operation flow of the communication system 101 according to the first embodiment is marked with the same step number. Figure 3 Description of the processes with the same step numbers is omitted.

[0058] In the communication system 102, the mobile station 13 that has received the direct communication request including the indirect communication request from the mobile station 12 is connected to the base station 11-1, and therefore transmits a relay communication request for data of the mobile station 12 to the base station 11-1 (step S15a). The base station 11-1 accepts the relay communication request received from the mobile station 13 and returns a relay communication approval (step S16a).

[0059] The operation of the mobile station 12 is the same as that of the first embodiment, and therefore the description thereof is omitted.

[0060] By performing the actions as described above, when a mobile station 12 that cannot implement a redundant structure based on direct communication selects an appropriate mobile station from surrounding mobile stations, it is possible to prepare multiple communication paths even when another mobile station 13 connected to the same base station as the mobile station 12 is selected, thereby implementing a redundant structure.

[0061] Implementation method 3.

[0062] The structure of the communication system of Embodiment 3 is the same as that of Embodiment 1. In the communication system of Embodiment 3, after a redundant structure based on direct communication and indirect communication between a mobile station and a base station is implemented, the establishment of direct communication is attempted again with the base station with which direct communication cannot be established, and when direct communication can be established, the indirect communication is terminated and the system is transferred to a redundant structure based on two direct communications.

[0063] Figure 7 FIG. 1 is a diagram showing an example of the operation flow of the communication system according to Embodiment 3. Figure 7 In the example shown, base station #1, base station #2, mobile station, and relay station constitute a communication system. Figure 7 In the embodiment, base station #1 corresponds to base station 11-1 in Embodiment 1, and base station #2 corresponds to base station 11-2 in Embodiment 1. The mobile station corresponds to mobile station 12 in Embodiment 1, and the relay station corresponds to mobile station 13 in Embodiment 1. The mobile station communicates directly with base station #1 and communicates indirectly with base station #2 via the relay station.

[0064] like Figure 7As shown in FIG. 1 , the mobile station sends a direct communication request to the base station #2 at a predetermined timing while communicating indirectly with the base station #2 via the relay station (step S31). The mobile station, for example, periodically sends a direct communication request to the base station #2 until the direct communication with the base station #2 is established. This step S31 is similar to the step S41 of FIG. Figure 3 The same processing as step S11 is performed.

[0065] When the base station #2 is able to accept the direct communication request, it returns a direct communication approval to the mobile station (step S32). Thus, direct communication between the mobile station and the base station #2 is established. After establishing direct communication with the base station #2, the mobile station decides to stop the indirect communication with the base station #2, and sends a direct communication stop request including the indirect communication stop request with the base station #2 to the relay station (step S33). The relay station sends a relay communication stop request to the base station #2 that is in indirect communication with the mobile station (step S34). The base station #2 that receives the relay communication stop request accepts the request and returns a relay communication stop approval to the relay station (step S35). When the relay station receives the relay communication stop approval from the base station #2, it sends a direct communication stop approval to the mobile station in response to the direct communication stop request from the mobile station (step S36). At this time, the relay station also sends an indirect communication stop approval with the base station #2. That is, in step S36, the relay station sends a direct communication stop approval including the indirect communication stop approval with the base station #2 to the mobile station. As a result, the indirect communication between the mobile station and the base station #2 via the relay station is completed.

[0066] If the operation of the mobile station according to this embodiment is shown in a flowchart, Figure 8 Like that. Figure 8 is a flowchart showing an example of the operation of the mobile station according to the third embodiment. Figure 8 In the example shown in FIG. 1 , the operation of the mobile station 12 according to the first embodiment is described. Figure 4 The common processing annotations of the flowchart are Figure 4 Same step number. Figure 4 Description of the processes with the same step numbers (processes of steps S1 to S5 ) will be omitted.

[0067] After executing the process of step S5, the mobile station of the third embodiment performs the connection process with the base station (step S6). In step S6, the mobile station performs the connection process for the base station with which direct communication could not be established through the connection process performed in step S2. When the mobile station successfully connects with the base station, that is, when direct communication with the base station is established (step S7: yes), the indirect communication with the base station via the communication terminal operating as a relay station is terminated (step S8), and the operation is terminated. When the mobile station fails to connect with the base station (step S7: no), the mobile station returns to step S6 and performs the connection process with the base station again.

[0068] As described above, after the mobile station of this embodiment realizes the redundant structure using indirect communication, it performs the direct communication establishment process again for the base station that failed to establish direct communication at a predetermined timing, and terminates the indirect communication when the direct communication can be established. In this way, it is possible to shift from the redundant structure based on the combination of direct communication and indirect communication to the redundant structure based only on direct communication.

[0069] In addition, in this embodiment, the direct communication establishment process is executed again for the base station that failed to establish direct communication, but the mobile station can also search for surrounding base stations, and when a base station with which direct communication cannot be established is found, the direct communication establishment process is executed again for the found base station.

[0070] Implementation method 4.

[0071] Fig. 9 1 is a diagram showing a configuration example of a communication system 103 according to Embodiment 4. The communication system 103 is Figure 1 The communication system 101 of the embodiment 1 shown is the same as the 5G communication system. Fig. 9 In the present invention, the same reference numerals are used for the structural elements common to the communication system 101 according to the first embodiment.

[0072] The communication system 103 includes base stations 11 - 1 and 11 - 2 , a mobile station 12 that constructs a redundant communication path, and mobile stations 13 - 1 and 13 - 2 that operate as relay stations in the redundant communication path constructed by the mobile station 12 .

[0073] In the communication system 103, the mobile station 12 establishes communication paths with the base stations 11-1 and 11-2 respectively, but cannot establish direct communication with the base station 11-2. Therefore, the mobile station 12 establishes indirect communication with the base station 11-2 via the mobile stations 13-1 and 13-2 respectively. The difference between the communication system 103 and the communication system 101 of the first embodiment is that the path of the indirect communication is duplicated.

[0074] Fig.10FIG. 1 is a diagram showing an example of the operation flow of the communication system 103 according to Embodiment 4. Fig.10 In the Figure 3 The same processing as that described in the operation flow of the communication system 101 according to the first embodiment is marked with the same step number. Figure 3 Description of the processes with the same step numbers is omitted.

[0075] After receiving the direct communication approval from the base station 11-1 in step S12, the mobile station 12 selects a plurality of mobile stations that request indirect communication (step S13a). Specifically, the mobile station 12 selects two mobile stations, the mobile stations 13-1 and 13-2, as mobile stations that request indirect communication. In addition, in a state where only one mobile station that requests indirect communication can be selected, the mobile station 12 selects one mobile station that requests indirect communication. In this case, the same operation as in the first embodiment is performed.

[0076] The mobile station 12 transmits a direct communication request including an indirect communication request with the base station 11 - 2 to the selected mobile stations 13 - 1 and 13 - 2 (step S14 a ).

[0077] The mobile stations 13 - 1 and 13 - 2 receive the direct communication request received from the mobile station 12 , and transmit a relay communication request for the data of the mobile station 12 to the base station 11 - 2 performing direct communication (steps S15 - 1 , S15 - 2 ).

[0078] The base station 11-2 receives the relay communication request received from the mobile stations 13-1 and 13-2, and returns the relay communication approval (steps S16-1, S16-2). When the mobile stations 13-1 and 13-2 receive the relay communication approval from the base station 11-2, they send a direct communication approval to the direct communication request from the mobile station 12 to the mobile station 12 (steps S17-1, S17-2). At this time, the mobile stations 13-1 and 13-2 also send approvals to the indirect communication request with the base station 11-2. That is, in step S17-1, the mobile station 13-1 sends a direct communication approval including approval to the indirect communication request with the base station 11-2 to the mobile station 12. In step S17-2, the mobile station 13-2 sends a direct communication approval including approval to the indirect communication request with the base station 11-2 to the mobile station 12. As a result, indirect communication via the mobile station 13 - 1 and indirect communication via the mobile station 13 - 2 are established between the base station 11 - 2 and the mobile station 12 .

[0079] By operating as described above, the mobile station 12 that cannot realize the redundant structure based on direct communication selects a plurality of appropriate mobile stations from the surrounding mobile stations to establish indirect communication, thereby realizing a redundant structure stronger than that of the first embodiment.

[0080] If the operation of the mobile station 12 according to this embodiment is shown in a flowchart, Fig.11 Like that. Fig.11 1 is a flowchart showing an example of the operation of the mobile station 12 according to the fourth embodiment. Fig.11 In the example shown in FIG. 1 , the operation of the mobile station 12 according to the first embodiment is described. Figure 4 The common processing annotations of the flowchart are Figure 4 Same step number. Figure 4 Description of the processes with the same step numbers is omitted.

[0081] After searching for communication terminals in step S4, the mobile station 12 of the fourth embodiment selects a plurality of communication terminals to be entrusted with the operation of a relay station for performing relay processing from the communication terminals found in step S4, and performs connection processing to the base station 11-2 via the communication terminals for the selected plurality of communication terminals (step S5a). Specifically, the mobile station 12 selects the mobile stations 13-1 and 13-2, and performs connection processing to the base station 11-2.

[0082] As described above, in the communication system 103 of the present embodiment, when the mobile station 12 cannot establish direct communication with the base station and establishes indirect communication, it searches and selects a plurality of mobile stations from the found mobile stations, and establishes a plurality of indirect communications via the selected mobile stations. Thus, compared with the communication system 101 of the first embodiment in which a redundant structure is realized by using a single indirect communication instead of direct communication, it is possible to realize highly reliable communication.

[0083] In addition, Fig. 9 In the communication system 103 shown, both the mobile station 13-1 and the mobile station 13-2 acting as relay stations are connected to the base station 11-2, but the connection method is not limited to this. At least one of the mobile station 13-1 and the mobile station 13-2 may be connected to the base station 11-1. That is, the mobile station 13-1 and the mobile station 13-2 acting as relay stations may be connected to the same base station as the mobile station 12 that is the request source for indirect communication, or may be connected to different base stations. In addition, the base station to which the mobile station 13-1 is connected may be different from the base station to which the mobile station 13-2 is connected.

[0084] Next, the hardware structure of the communication device 1 constituting the mobile station 12 described in each embodiment is described. The wireless unit 20 of the communication device 1 is implemented by a transceiver. In addition, the communication unit 30 of the communication device 1 is implemented by a processing circuit as dedicated hardware, specifically, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a processing circuit composed of a combination thereof.

[0085] Furthermore, the processing circuit that realizes the communication unit 30 of the communication device 1 may be a control circuit composed of a processor that executes a program stored in a memory and a memory. Fig.12 1 is a diagram showing a configuration example of a processing circuit in which the communication unit 30 of the communication device 1 is implemented by a processor and a memory. The processor 91 is a CPU (also called a Central Processing Unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor). The memory 92 is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (registered trademark) (Electrically EPROM), or the like.

[0086] The communication unit 30 of the communication device 1, that is, the base station search unit 31, the communication terminal search unit 32, and the communication control unit 33 are implemented by the processor 91 and the memory 92. That is, a program for operating as the base station search unit 31, the communication terminal search unit 32, and the communication control unit 33 is stored in the memory 92 in advance, and the processor 91 reads and executes the program, thereby realizing the communication unit 30 of the communication device 1.

[0087] Alternatively, some components of the communication unit 30 of the communication device 1 may be implemented by dedicated hardware, and the remaining components may be implemented by dedicated hardware. Fig.12In the case where part or all of the components of the communication unit 30 of the communication device 1 are implemented by the processor 91 and the memory 92, the program stored in the memory 92 may be provided to the user, etc. in a state of being written to a storage medium such as a CD (Compact Disc)-ROM or a DVD (Digital Versatile Disc)-ROM, or may be provided via a network.

[0088] The structure shown in the above embodiments is an example, and can be combined with other known technologies, and the embodiments can be combined with each other. It is also possible to omit or change a part of the structure within the scope of the main purpose. For example, in each embodiment, the number of base stations with which the mobile station 12 establishes direct communication is set to 2, but the number of base stations with which the direct communication is established can also be set to 3 or more.

[0089] Description of Reference Numerals

[0090] 1 communication device, 11-1, 11-2 base station, 12, 13, 13-1, 13-2 mobile station, 20 wireless unit, 30 communication unit, 31 base station search unit, 32 communication terminal search unit, 33 communication control unit, 101, 102, 103 communication system.

Claims

1. A communication device having a function of directly communicating with a communication terminal as another communication device, It is characterized in that The communication device comprises: A base station search unit that searches for a base station with which direct communication is possible; a communication control unit that performs connection processing with the base station searched by the base station search unit, thereby constructing a communication path of a redundant structure; as well as a communication terminal search unit that searches for the communication terminal that has been connected to the base station, When the number of direct communications established with the base station does not meet the number required to construct the redundant communication path, the communication control unit establishes indirect communication with the base station via the communication terminal searched by the communication terminal search unit, thereby constructing the redundant communication path.

2. The communication device according to claim 1, It is characterized in that The communication terminal search unit collects information of base stations connected to the searched communication terminal, The communication control unit selects a communication terminal that performs relay processing of the indirect communication based on the information of the base station collected by the communication terminal search unit.

3. The communication device according to claim 2, It is characterized in that The communication control unit selects a communication terminal directly connected to the base station for which establishment of direct communication has failed from among the communication terminals searched by the communication terminal search unit, and establishes indirect communication via the selected communication terminal.

4. The communication device according to any one of claims 1 to 3, It is characterized in that The communication control unit executes a connection process for establishing direct communication with a base station after establishing the indirect communication, and terminates the indirect communication when the establishment of the direct communication with the base station is successful.

5. The communication device according to any one of claims 1 to 4, It is characterized in that The communication control unit selects a plurality of communication terminals from the communication terminals searched by the communication terminal search unit, and establishes a plurality of indirect communications respectively via the selected plurality of communication terminals.

6. A communication method, which is performed by a communication device having a function of directly communicating with a communication terminal as another communication device, It is characterized in that The communication method comprises: A base station search step, searching for a base station with which direct communication is possible; a communication control step of executing connection processing with the base station searched in the base station search step, thereby constructing a communication path of a redundant structure; and a communication terminal searching step, searching for the communication terminal that has been connected to the base station, In the communication control step, when the number of direct communications established with the base station does not meet the number required to construct the communication path of the redundant structure, indirect communication is established with the base station via the communication terminal searched in the communication terminal search step, thereby constructing the communication path of the redundant structure.

7. A control circuit for controlling a communication device having a function of directly communicating with a communication terminal as another communication device, It is characterized in that The control circuit enables the communication device to execute: A base station search step, searching for a base station with which direct communication is possible; a communication control step of executing connection processing with the base station searched in the base station search step, thereby constructing a communication path of a redundant structure; and a communication terminal searching step, searching for the communication terminal that has been connected to the base station, The communication control step includes the following processing: when the number of direct communications established with the base station does not meet the number required to build the communication path of the redundant structure, indirect communication is established with the base station via the communication terminal searched in the communication terminal search step, thereby building the communication path of the redundant structure.

8. A storage medium storing a program for controlling a communication device having a function of directly communicating with a communication terminal as another communication device, It is characterized in that The program causes the communication device to execute: A base station search step, searching for a base station with which direct communication is possible; a communication control step of executing connection processing with the base station searched in the base station search step, thereby constructing a communication path of a redundant structure; and a communication terminal searching step, searching for the communication terminal that has been connected to the base station, The communication control step includes the following processing: when the number of direct communications established with the base station does not meet the number required to build the communication path of the redundant structure, indirect communication is established with the base station via the communication terminal searched in the communication terminal search step, thereby building the communication path of the redundant structure.

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