Communication device, control method, and program

Abstract

To select appropriate one of a plurality of communication devices as a relay device.SOLUTION: A side link communication device has receiving means (105) that receives detection signals transmitted from a plurality of communication devices (10A, 10B, 10C) for detecting the communication devices as side link devices; and selection means (101) that selects a target device to be connected as a relay device from the plurality of communication devices (10A, 10B, 10C) detected by the reception of the detection signals. The receiving means (105) receives values of relay time parameters transmitted from the plurality of communication devices before the connection with the target device is established. The relay time parameter relates to the time during which each of the plurality of communication devices can function as the relay device. The selection means (101) selects the target device based on the value of the relay time parameter related to each of the plurality of communication devices.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a Sidelink communication device. [Background technology]

[0002] In recent years, the 3GPP (3rd Generation Partnership Project) has been formulating specifications for LTE (Long Term Evolution) and 5G (NR; New Radio). Among these, a standard specification called Sidelink communication (hereinafter, Sidelink) has been formulated. This specification realizes direct wireless communication between terminals (UE; User Equipment) using an interface called PC5, without going through a mobile communication network (core network).

[0003] Furthermore, 3GPP is currently developing specifications for expanding the communication range of Sidelink by using a Sidelink relay function that relays Sidelink communication via a relay device (relay UE).

[0004] Patent Document 1 proposes a technique for connecting a terminal (UE) outside the coverage of a base station to a relay device installed within the coverage of the base station via sidelink communication, thereby enabling communication with the base station. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-078140 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when one communication device selects one communication device as a relay device from among multiple communication devices, connects to the selected relay device via sidelink communication, and communicates with a base station, it is difficult to select an appropriate one of the multiple communication devices as a relay device, because the time during which each communication device can function as a relay device may differ.

[0007] The present invention has been made in consideration of at least one of the above problems. One aspect of the present disclosure has an object to enable a suitable one of a plurality of communication devices to be selected as a relay device. [Means for solving the problem]

[0008] Therefore, a sidelink communication device according to one aspect of the present disclosure includes: A receiving means for receiving detection signals transmitted from a plurality of communication devices for detecting the communication devices as sidelink devices; a selection means for selecting a target device to be connected as a relay device from among the plurality of communication devices detected by receiving the detection signal; having The receiving means receives values ​​of relay time parameters transmitted from the plurality of communication devices before a connection with the target device is established; the relay time parameter relates to a time during which each of the plurality of communication devices is capable of functioning as a relay device; The selection means selects the target device based on a value of the relay time parameter associated with each of the plurality of communication devices. Effect of the Invention

[0009] According to one aspect of the present disclosure, it is possible to select an appropriate one of a plurality of communication devices as a relay device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a communication system according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of a communication device. [Diagram 3] 4 is a diagram illustrating an example of a format of a discovery response message in the first embodiment. FIG. [Figure 4] FIG. 2 is a diagram illustrating a discovery process in the terminal 10 of the first embodiment. [Diagram 5] 11 is a flowchart showing a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C in the first embodiment. [Figure 6] FIG. 4 is a sequence diagram showing an example of the operation of the communication system according to the first embodiment. [Figure 7] FIG. 13 is a diagram illustrating an example of the format of a discovery request message when battery information is included. [Figure 8] FIG. 11 is a diagram illustrating an example of a format of a discovery response message in the second embodiment. [Figure 9] FIG. 11 is a diagram illustrating a discovery process in the terminal 10 of the second embodiment. [Figure 10] 13 is a flowchart showing a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C in the second embodiment. [Figure 11] FIG. 11 is a sequence diagram showing an example of the operation of the communication system according to the second embodiment. [Figure 12] FIG. 13 is a diagram illustrating an example of a format of a discovery response message in the third embodiment. [Figure 13] 13 is a flowchart showing a discovery process in the terminal 10 of the third embodiment. [Figure 14] 13 is a flowchart showing discovery response processing in the terminal 10A, the terminal 10B, and the terminal 10C in the third embodiment. [Figure 15] FIG. 11 is a sequence diagram showing an example of the operation of a communication system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0012] Sidelink communication is based on the assumption that the Sidelink function of the terminal is always ON, and does not take power consumption into consideration. For this reason, Sidelink communication is established even for UEs with low battery levels, and long-term Sidelink communication is not guaranteed.

[0013] Under the above circumstances, if a UE (User Equipment) equipped with a Sidelink relay function is battery-powered, the power supply is limited, and the usage time is therefore restricted. Therefore, for example, if a UE (remote UE) that wants to use the Sidelink relay wants to communicate for a long time, the battery of the UE that provides the Sidelink relay (relay UE) needs to have enough power remaining to operate for a long time.

[0014] When the battery of a relay UE is low, not only does the usage time of the relay UE decrease, but also, for remote UEs, when the battery of the relay UE runs out, the remote UE is disconnected from the network until communication with another relay UE can be established, which is an issue.

[0015] A communication system and the like that takes the above-mentioned problems into consideration are disclosed below.

[0016] <First embodiment>

[0017] [System configuration] FIG. 1 is a diagram illustrating an example of the configuration of a Sidelink communication system.

[0018] 1, a terminal 10 (an example of a sidelink device) serving as a remote UE is outside a communication area 20A of a base station 20. The terminal 10 searches for a device (UE) to which it will be connected in order to realize sidelink relay communication.

[0019] In Fig. 1, a terminal 10A, a terminal 10B, and a terminal 10C (an example of a plurality of communication devices) serving as a relay UE (a sidelink device, an example of a target device) are terminals compatible with sidelink relay communication. These terminals are located within a communication area 20A of a base station 20 and can respond to a search from the terminal 10. In this embodiment, a smartphone or the like is assumed as a terminal compatible with sidelink relay communication, but the present invention is not limited to this. For example, the terminal may be a communication terminal such as a tablet terminal or a PC, a wearable terminal such as a smartwatch or a head-mounted display, or a car navigation device installed in an automobile.

[0020] Furthermore, each of the terminals 10A, 10B, and 10C holds a parameter (hereinafter, referred to as a "relay time parameter") related to the time during which the terminal can function as a relay device. The relay time parameter indicates, for example, the type of power source (whether or not a battery is used), the battery type, the remaining battery capacity, the service available time based on the remaining battery capacity, and the like.

[0021] [Functional configuration of the device] Next, the functional configuration of the communication device 100 according to this embodiment will be described. Note that the configuration of the functional blocks described below is merely an example. Some (in some cases, all) of the functional blocks described may be replaced with other functional blocks that perform similar functions, some functional blocks may be omitted, or further functional blocks may be added. Also, one functional block shown in the following description may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block.

[0022] FIG. 2 is a block diagram illustrating an example of a functional configuration of the communication device.

[0023] A communication device 100 constituted by each of the terminals 10, 10A, 10B, and 10C has the configuration shown in Fig. 2. That is, the communication device 100 has a control unit 101 (an example of a selection means), a storage unit 102, a message generation unit 103, a message analysis processing unit 104, and a communication unit 105 (an example of a transmission means and a reception means).

[0024] The control unit 101 controls the operation of the communication device 100. The control unit 101 is configured with one or more processors such as a CPU or an MPU, and controls the entire communication device by executing a computer program deployed in a RAM that is a storage unit 102. Note that the reception control and transmission control performed by the terminal 10, which will be described in a flowchart later, are realized by the processor such as a CPU or an MPU of the control unit 101 working in cooperation with hardware such as a communication unit 105.

[0025] The storage unit 102 is a RAM or a non-volatile storage area that stores the control program used by the control unit 101 for control, other information, and information related to communication. The control program stored in the non-volatile storage area is expanded in the RAM and executed by the processor constituting the control unit 101. In this way, the control unit 101 and the storage unit 102 function as a so-called computer.

[0026] The message generating unit 103 generates a discovery message and other messages to be transmitted for UE detection.

[0027] The message analysis processing unit 104 analyzes discovery messages and other messages received from other communication devices. Note that the functions corresponding to the generation unit 103 and the analysis processing unit 104 may be realized as software modules realized by the control unit 101.

[0028] The communication unit 105 performs cellular network communication such as LTE and 5G with the base station 20 (FIG. 1) conforming to the 3GPP standard. The communication unit 105 also transmits and receives information via Sidelink communication with other communication terminals that support Sidelink communication. The communication unit 105 performs a process of transmitting messages generated by the message generation unit 203 and a process of receiving messages from other terminals (UE).

[0029] As described above, the operation of communication device 100 can be realized by control unit 101 executing a control program stored in storage unit 102, and performing calculations and processing of information and control of each piece of hardware.

[0030] [Processing example] FIG. 3 is a diagram illustrating an example of a format of the discovery response message.

[0031] In FIG. 3, "Destination Layer-2 ID" stores the Layer-2 ID indicating the destination of the information. "Source Layer-2 ID" stores the Layer-2 ID indicating the source of the information. "Type of Discovery Message" stores information indicating the type of this message. "Discover Info" stores identification information of the UE that sent the discovery response message. "Relay Service Code (RSC)" stores identification information of the connection service provided by the UE that sent the discovery response message.

[0032] In Fig. 3, "Power Supply Flg (flag)" stores information on whether the terminal itself is receiving power from a power source. That is, "Power Supply Flg" stores "ON" when the terminal itself is receiving power from another power source, and stores "OFF" when the terminal itself is powered by its own battery. Also, in Fig. 3, "Battery Remaining" stores the remaining battery capacity of the terminal itself. In this embodiment, "Power Supply Flg (flag)" and "Battery Remaining" correspond to relay time parameters.

[0033] FIG. 4 is a diagram showing a discovery process in the terminal 10. As shown in FIG.

[0034] In step S102 in Fig. 4, the control unit 101 of the communication device 100 (Fig. 2) configured by the terminal 10 activates the message generating unit 103 to generate a discovery request message, and broadcasts the message from the communication unit 105. The discovery signal as the discovery request message may be a Soliciation Message. That is, the discovery signal may be a Soliciation Message for 5G ProSe direct discovery or 5G ProSe UE-to-Network Relay Discovery. Note that ProSe is an abbreviation for (Proximity based Services).

[0035] In step S104, the control unit 101 waits for a discovery response message as a detection signal transmitted from another terminal by the communication unit 105, and if a discovery response message is received, the process proceeds to step S106. The discovery response signal as the discovery response message may be a Response Message of the above-mentioned Soliciation Message.

[0036] In step S106, the control unit 101 stores in the storage unit 102 the discovery response message that has been confirmed as having been received in step S104.

[0037] In step S108, the control unit 101 determines whether or not a predetermined time has elapsed since transmitting the discovery request message, and if the determination is affirmative, the process proceeds to step S110, whereas if the determination is negative, the process proceeds to step S104.

[0038] In step S110, the control unit 101 activates the message analysis processing unit 204 to analyze the contents of the discovery response message saved in step S106. The control unit 101 also causes the message analysis processing unit 104 to determine whether or not any discovery response message in which "ON" is stored in the "Power Supply Flg" (FIG. 3) is present among the discovery response messages saved in step S106. If the determination is affirmative, the control unit 101 advances the process to step S112, and if the determination is negative, the control unit 101 advances the process to step S114.

[0039] In step S112, the control unit 101 selects a connection destination from among the terminals (UE) that have returned a discovery response message in which "ON" is stored in the "Power Supply Flg". The control unit 101 also starts a Sidelink connection with the selected terminal (UE) and ends the process. This establishes communication between the terminal 10 and the selected terminal (UE) via a Sidelink connection. That is, communication is enabled using the selected terminal (UE) as a relay device.

[0040] In step S114, the message analysis processing unit 204 checks the "battery remaining amount" (FIG. 3) in the received discovery response message, and selects the terminal (UE) with the largest remaining battery amount as the connection destination. Here, a terminal with a remaining battery amount equal to or greater than a threshold may be selected as the connection destination. Furthermore, the control unit 101 starts a sidelink connection with the selected terminal (UE) and ends the process. This establishes communication between the terminal 10 and the selected terminal (UE) via a sidelink connection. That is, communication becomes possible using the selected terminal (UE) as a relay device.

[0041] Fig. 5 is a flowchart showing discovery response processing in terminal 10A, terminal 10B, and terminal 10C. In step S202 in Fig. 5, control unit 101 of communication device 100 configured by terminal 10A, terminal 10B, and terminal 10C waits for a discovery request message via communication unit 105. If a discovery request message is received, control unit 101 advances the process to step S204.

[0042] In step S204, the control unit 101 starts the message generating unit 103 to generate a discovery response message (FIG. 3). Here, the message generating unit 103 checks the battery state of its own terminal, and stores corresponding parameters in the "power supply flag" and "battery remaining capacity" of the discovery response message.

[0043] In step S206, the control unit 101 causes the communication unit 105 to transmit the discovery response message generated in step S204 to the source (UE) of the discovery request message, and ends the process.

[0044] Fig. 6 is a sequence diagram showing an example of the operation of the communication system according to this embodiment. The step numbers in Fig. 6 correspond to the processes shown in Figs.

[0045] 6, the terminal 10A is powered not by its own battery but by another power source, while the terminals 10B and 10C are driven by their own batteries, with the remaining battery capacities of the terminals being 100 mAh and 10 mAh, respectively.

[0046] As shown in FIG. 6, the terminal 10 generates a discovery request message in the message generating unit 103 and broadcasts the message (step S102).

[0047] When the terminal 10A receives the discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S204) and returns the message to the terminal 10 (step S206). Since the terminal 10A is powered by another power source, the "Power Supply Flg" in the discovery response message is set to "ON."

[0048] Similarly, when the terminal 10B receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S204) and returns it to the terminal 10 (step S206). Since the terminal 10A is operating on its own battery, the "Power Supply Flg" in the discovery response message is set to "OFF." Also, the "Remaining Battery Amount" in the discovery response message is set to "100 mAh."

[0049] Similarly, when the terminal 10C receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S204) and returns it to the terminal 10 (step S206). Since the terminal 10A is operating on its own battery, the "Power Supply Flg" in the discovery response message is set to "OFF." Also, the "Remaining Battery Amount" in the discovery response message is set to "10 mAh."

[0050] Next, the terminal 10 selects the terminal 10A as a connection destination UE based on the "power supply Flg" and "remaining battery level" in the received discovery response message, and establishes a sidelink connection with the terminal 10A (step S112).

[0051] If terminal 10A is driven by its own battery, like terminals 10B and 10C, terminal 10 selects a terminal with the largest "remaining battery power" in the discovery response message, as shown in FIG. 4. Then, terminal 10 establishes a sidelink connection with the selected terminal (step S114). Alternatively, terminal 10 may establish a sidelink connection with one of the terminals whose remaining battery power is equal to or greater than a threshold, based on the "remaining battery power" in the discovery response message. In this case, if there are multiple terminals whose remaining battery power is equal to or greater than a threshold, the terminal with the largest "remaining battery power" may be selected, or a terminal other than the terminal with the largest "remaining battery power" may be selected based on a combination with other factors.

[0052] As described above, the terminal 10 is able to select a UE that can provide the sidelink function for a long period of time based on the relay time parameter, and connect to that UE.

[0053] In the above description, the relay time parameter is always stored in the discovery response message, but the discovery request message may be transmitted including battery information (information requesting the return of the relay time parameter).

[0054] FIG. 7 is a diagram showing an example of the format of a discovery request message when battery information is included.

[0055] In FIG. 7, "Destination Layer-2 ID" stores a Layer-2 ID indicating the destination of the information. "Source Layer-2 ID" stores a Layer-2 ID indicating the source of the information. "Type of Discovery Message" stores information indicating the type of this message. "Discoverer Info" stores identification information of the UE that sent the discovery request message. "Relay Service Code (RSC)" stores identification information of the connection service provided by the UE that sent the discovery response message. "Target Info" stores identification information of the UE that is the target of discovery. "Target Info" may be stored when the UE that is the target of discovery has already been identified. When requesting a return of relay time parameters, "ON" is stored in "Battery Information".

[0056] When the discovery request message includes “battery information”, in step S102 in FIG. 4, the message generating unit 103 generates a discovery request message shown in FIG.

[0057] Furthermore, in step S204 in FIG. 5, the message generator 103 may store a relay time parameter in the discovery response message only when battery information is included in the discovery request message.

[0058] As a result, for example, in the case of an emergency, a destination UE can be selected based on a relay time parameter included in a discovery response message. In this way, flexible operation according to the situation, such as the presence or absence of an emergency, becomes possible.

[0059] In this embodiment, a case where a discovery response message is returned in response to a discovery request message ("Model B" in TR23.752 6.19.1.1) is described. However, the same process can be applied to a case where a relay UE unilaterally transmits a discovery signal without receiving a discovery request ("Model A" in TR23.752 6.19.1.1). In the latter case, a relay time parameter can be included in the discovery signal, and the terminal 10 can select a terminal to be used as a relay device based on the relay time parameter included in the discovery signal. This process makes it possible to determine a terminal to be connected. The same applies to the second and third embodiments described later. The discovery request message is an example of a discovery request signal. <Second embodiment> In the first embodiment, an example is described in which a relay UE that can be connected for a longer period of time is selected and connected based on the "power supply Flg" and "remaining battery level" stored in a discovery response message. In the second embodiment, an example is described in which a relay UE that can be connected for a longer period of time is selected and connected based on the "serviceable time" stored in a discovery response message.

[0060] The system configuration (FIG. 1) and the functional configuration of the communication device 100 (FIG. 2) in the second embodiment are similar to those in the first embodiment. Below, differences from the first embodiment will be described.

[0061] [Processing example] FIG. 8 is a diagram illustrating an example of a format of a discovery response message in the second embodiment.

[0062] In FIG. 8, "Destination Layer-2 ID" stores the Layer-2 ID indicating the destination of the information. "Source Layer-2 ID" stores the Layer-2 ID indicating the source of the information. "Type of Discovery Message" stores information indicating the type of this message. "Discover Info" stores identification information of the UE that sent the discovery response message. "Relay Service Code (RSC)" stores identification information of the connection service provided by the UE that sent the discovery response message.

[0063] 8, the "available service time" as a relay time parameter stores the available time of the sidelink relay function provided by the own terminal as a relay UE. If there is no limit to the available time of the sidelink relay function, "0" is stored in the available service time. If there is a limit to the available time of the sidelink relay function, the available time is stored as, for example, a time in minutes.

[0064] FIG. 9 is a diagram showing the discovery process in the terminal 10. As shown in FIG.

[0065] In step S102 in FIG. 9, the control unit 101 of the communication device 100 (FIG. 2) constituted by the terminal 10 starts the message generating unit 103 to generate a discovery request message, and transmits the message from the communication unit 105 by broadcast.

[0066] In step S104, the control unit 101 waits for a discovery response message transmitted from another terminal via the communication unit 105, and if a discovery response message is received, the process proceeds to step S106.

[0067] In step S106, the control unit 101 stores in the storage unit 102 the discovery response message that has been confirmed as having been received in step S104.

[0068] In step S108, the control unit 101 determines whether or not a predetermined time has elapsed since transmitting the discovery request message, and if the determination is affirmative, the process proceeds to step S120, whereas if the determination is negative, the process proceeds to step S104.

[0069] In step S120, the control unit 101 starts the message analysis processing unit 204. The control unit 101 also analyzes the contents of the discovery response message stored in step S106. The control unit 101 also determines, based on the analysis result, whether or not any discovery response message in which "0" is stored in the "service available time" field is present among the discovery response messages stored in step S106. If the determination is affirmative, the control unit 101 advances the process to step S122, and if the determination is negative, the control unit 101 advances the process to step S124.

[0070] In step S122, the control unit 101 selects a connection destination from among terminals (UE) that have returned discovery response messages in which "0" is stored in the "service available time". The control unit 101 also starts a Sidelink connection with the selected terminal (UE) and ends the process.

[0071] In step S124, the message analysis processing unit 204 checks the "available service time" of the discovery response message stored in step S106, and selects the terminal (UE) with the longest "available service time" as the connection destination. Furthermore, the control unit 101 starts a sidelink connection with the selected connection destination, and ends the process.

[0072] FIG. 10 is a flowchart showing the discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C. 5, the control unit 101 of the communication device 100 including the terminals 10A, 10B, and 10C waits for a discovery request message via the communication unit 105. If the discovery request message is received, the control unit 101 advances the process to step S210.

[0073] In step S210, the control unit 101 determines whether the power source of the terminal itself is an external power source, and if the determination is affirmative, the process proceeds to step S220, whereas if the determination is negative, the process proceeds to step S212. Note that if the determination in step S210 is negative, the power source of the terminal itself is its own battery.

[0074] In step S212, the control unit 101 calculates the intensity of the radio wave transmitted to the base station 20 based on the distance between the terminal and the base station 20. Here, the storage unit 102 stores the position information (coordinates) of the base station 20. The position information (coordinates) of the terminal can be acquired by a GPS or the like provided in the terminal. In step S212, the control unit 101 calculates the distance between the terminal and the base station 20 based on the coordinates of the base station 20 and the position information (coordinates) of the terminal, and calculates the intensity of the radio wave transmitted based on the calculated distance.

[0075] In step S214, the control unit 101 calculates the transmission signal strength between the remote UEs based on the distance from the discovery request transmission source UE (remote UE). For example, the terminal 10 as the remote UE may transmit the coordinates of the remote UE in the discovery request. In this case, the control unit 101 may calculate the transmission signal strength between the remote UEs based on the coordinates of the remote UE.

[0076] In step S216, the control unit 101 acquires the remaining battery power of the terminal itself. In addition, the control unit 101 calculates a "service available time" based on the transmission signal strength calculated in step S212, the transmission signal strength calculated in step S214, and the acquired remaining battery power. The "service available time" corresponds to the time during which the terminal itself can continuously function as a relay UE (relay device).

[0077] In step S218, the control unit 101 generates a discovery response message by the message generating unit 103. In this discovery response message, the "service available time" calculated in step S216 is stored.

[0078] On the other hand, in step S220, control unit 101 generates a discovery response message by message generation unit 103. "0" is stored in the "service available time" field of this discovery response message.

[0079] In step S222, the discovery response message generated in step S218 or step S220 is transmitted to the UE that transmitted the discovery request message, and the process ends.

[0080] In the above steps S212 to S216, the "available service time" is calculated based on the transmitted radio wave intensity. However, the "available service time" may be calculated based on the power consumption per hour required for the relay UE to use the relay function.

[0081] That is, in step S212, the control unit 101 may calculate the power usage per hour of all functions being used by the relay UE, and in step S214, the control unit 101 may calculate the power usage per hour required for the sidelink relay. In this case, in step 216, the control unit 101 can calculate the "service available time" based on the power usage per hour calculated in steps S212 and S214 and the remaining battery level.

[0082] Fig. 11 is a sequence diagram showing an example of the operation of the communication system according to this embodiment. The step numbers in Fig. 11 correspond to the processes shown in Figs.

[0083] 11, the terminal 10A is powered by another power source, not by its own battery, and has no limit to its "available service time." The terminals 10B and 10C are driven by their own batteries, and the "available service times" calculated in steps S212 to S216 are 20 minutes and 30 minutes, respectively.

[0084] As shown in FIG. 11, the terminal 10 generates a discovery request message in the message generating unit 103 and broadcasts the message (step S102).

[0085] When the terminal 10A receives the discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S220) and returns it to the terminal 10 (step S222). Here, since the terminal 10A is powered by another power source and has no limit on the available service time, the available service time in the discovery response message is set to "0" (step S220).

[0086] Similarly, when the terminal 10B receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S218) and returns it to the terminal 10 (step S222). Here, since the terminal 10B is operating on its own battery, the service available time in the discovery response message is set to the calculated result of "20 minutes" (step S218).

[0087] Similarly, when the terminal 10C receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S218) and returns it to the terminal 10 (step S222). Here, since the terminal 10C is operating on its own battery, the service available time in the discovery response message is set to the calculated result of "30 minutes" (step S218).

[0088] Next, the terminal 10 selects the terminal 10A as a connection destination UE based on the "service available time" in the received discovery response message, and establishes a sidelink connection with the terminal 10A (step S122).

[0089] If the terminal 10A is powered by its own battery, like the terminals 10B and 10C, the terminal 10 selects the terminal with the longest "service available time" in the discovery response message, as shown in Fig. 9. Then, the terminal 10 establishes a sidelink connection with the selected terminal (step S124).

[0090] As described above, the terminal 10 is able to select a UE that can provide the sidelink function for a long period of time based on the relay time parameter, and connect to that UE.

[0091] <Third embodiment> In the third embodiment, an example will be described in which a relay UE that can be connected for a longer period of time is selected and connected based on the "power supply type" and "remaining power" stored in a discovery response message.

[0092] The system configuration (FIG. 1) and the functional configuration of the communication device 100 (FIG. 2) in the third embodiment are similar to those in the first embodiment. Below, differences from the first embodiment will be described.

[0093] [Processing example] FIG. 12 is a diagram illustrating an example of a format of a discovery response message in the third embodiment.

[0094] In FIG. 12, "Destination Layer-2 ID" stores the Layer-2 ID indicating the destination of the information. "Source Layer-2 ID" stores the Layer-2 ID indicating the source of the information. "Type of Discovery Message" stores information indicating the type of this message. "Discover Info" stores identification information of the UE that transmitted the discovery response message. "Relay Service Code (RSC)" stores identification information of the connection service provided by the UE that transmitted the discovery response message.

[0095] In FIG. 12, "power supply type" stores the type of power supply that supplies power to the terminal. The types of battery that can be set are "commercial power supply," "UPS (uninterruptible power supply)," "secondary battery," and "primary battery." Additionally, "remaining power" stores the remaining battery charge. If the power supply type is "commercial power supply" or "UPS," "0" is stored in the remaining power. In this embodiment, "power supply type" and "remaining power" correspond to relay time parameters.

[0096] FIG. 13 is a diagram showing a discovery process in the terminal 10. As shown in FIG.

[0097] In step S102 in FIG. 13, the control unit 101 of the communication device 100 (FIG. 2) constituted by the terminal 10 activates the message generating unit 103 to generate a discovery request message, and transmits the message from the communication unit 105 by broadcast.

[0098] In step S104, the control unit 101 waits for a discovery response message transmitted from another terminal via the communication unit 105, and if a discovery response message is received, the process proceeds to step S106.

[0099] In step S106, the control unit 101 stores in the storage unit 102 the discovery response message that has been confirmed as having been received in step S104.

[0100] In step S108, the control unit 101 determines whether or not a predetermined time has elapsed since transmitting the discovery request message, and if the determination is affirmative, the process proceeds to step S130, whereas if the determination is negative, the process proceeds to step S104.

[0101] In step S130, the control unit 101 starts the message analysis processing unit 204, and determines whether or not a discovery response message in which "UPS" is stored in the "power supply type" field is present among the discovery response messages stored in step S106. If the determination is affirmative, the control unit 101 advances the process to step S132, and if the determination is negative, the control unit 101 advances the process to step S134.

[0102] In step S132, the control unit 101 selects a connection destination from among terminals (UE) that have returned discovery response messages in which "UPS" is stored in the "power supply type". The control unit 101 also starts a Sidelink connection with the selected terminal (UE) and ends the process.

[0103] In step S134, the control unit 101 determines whether or not a disaster notification was sent from the gNB while the terminal (terminal 10) was connected to the gNB. If the determination is affirmative, the control unit 101 advances the process to step S136, and if the determination is negative, the control unit 101 advances the process to step S138.

[0104] In step S136, the control unit 101 determines whether or not "secondary battery" or "primary battery" is stored in the "power source type" of the discovery response message stored in step S106 by the message analysis processing unit 204. If the determination is affirmative, the control unit 101 proceeds to step S140, and if the determination is negative, the control unit 101 proceeds to step S142.

[0105] In step S140, the control unit 101 checks the "remaining power" in the discovery response message stored in step S106 by the message analysis processing unit 204, and selects the UE with the largest "remaining power" as the connection destination UE. The control unit 101 starts a sidelink connection with the selected connection destination UE, and ends the process.

[0106] In step S142, the control unit 101 selects a connection destination from among terminals (UE) that have returned discovery response messages in which "commercial power source" is stored as the power source type. The control unit 101 also starts a Sidelink connection with the selected terminal (UE) and ends the process.

[0107] In step S138, the control unit 101 determines whether or not "commercial power source" is stored in the "power source type" of the discovery response message stored in step S106 by the message analysis processing unit 204. If the determination is affirmative, the control unit 101 proceeds to step S144, and if the determination is negative, the control unit 101 proceeds to step S146.

[0108] In step S144, the control unit 101 selects a connection destination from among terminals (UE) that have returned discovery response messages in which "commercial power source" is stored in the power source type. The control unit 101 also starts a Sidelink connection with the selected terminal (UE) and ends the process.

[0109] In step S146, the control unit 101 checks the "remaining power" in the discovery response message stored in step S106 by the message analysis processing unit 204, and selects the UE with the largest "remaining power" as the connection destination UE. The control unit 101 starts a Sidelink connection with the selected connection destination UE, and ends the process.

[0110] FIG. 14 is a flowchart showing the discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C.

[0111] 14, the control unit 101 of the communication device 100 constituted by the terminal 10A, the terminal 10B, and the terminal 10C waits for a discovery request message via the communication unit 105. If the discovery request message is received, the control unit 101 advances the process to step S230.

[0112] In step S230, the control unit 101 activates the message generating unit 103 to generate a discovery response message (FIG. 3). Here, the control unit 101 checks the power state of its own terminal, and stores information corresponding to the "power type" and "remaining power" in the discovery response message.

[0113] In step S232, the control unit 101 causes the communication unit 105 to transmit the discovery response message generated in step S230 to the source (UE) of the discovery request message, and ends the process.

[0114] Fig. 15 is a sequence diagram showing an example of the operation of the communication system according to this embodiment. The step numbers in Fig. 15 correspond to the processes shown in Figs.

[0115] 15, the terminal 10A is powered by a UPS. The terminal 10B is powered by a commercial power source, and the terminal 10C is operating on its own secondary battery. The remaining battery charge of the terminal 10C is 100 mAh.

[0116] As shown in FIG. 15, the terminal 10 generates a discovery request message in the message generating unit 103 and broadcasts the message (step S102).

[0117] When the terminal 10A receives the discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S230) and returns it to the terminal 10 (step S232). Since the terminal 10A receives power from a UPS, the terminal 10A sets the "power supply type" of the discovery response message to "UPS" and the "remaining power" to "0".

[0118] Similarly, when the terminal 10B receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S230) and returns it to the terminal 10 (step S232). Here, since the terminal 10B is powered from a commercial power source, the "power source type" of the discovery response message is set to "commercial power source" and the "remaining power" is set to "0".

[0119] Similarly, when the terminal 10C receives a discovery request message from the terminal 10 (step S202; YES), it generates a discovery response message (step S230) and returns it to the terminal 10 (step S232). Here, since the terminal 10C is powered by a secondary battery and the remaining battery power is 100 mAh, the "power supply type" of the discovery response message is set to "secondary battery" and the "remaining power" is set to "100 mAh".

[0120] Next, the terminal 10 selects the terminal 10A as a connection destination UE based on the power supply type ("UPS") in the received discovery response message, and establishes a sidelink connection with the terminal 10A (step S132).

[0121] In this way, the terminal 10 can select and connect to a UE that can provide the sidelink function for a long period of time based on the relay time parameter.

[0122] As described above, in step S134 of FIG. 13, the terminal 10 determines whether a disaster notification has been received before the gNB is disconnected. This is in consideration of a case where a terminal that can become a relay UE is searched for in a situation where the gNB of the terminal to which the terminal 10 is connected becomes inaccessible due to a power outage during a disaster and the terminal is out of coverage. For example, when a disaster occurs, if a relay UE that is powered by a commercial power source is selected, the connection with the relay UE may also be cut off due to a power outage. In contrast, in the third embodiment, such a situation can be avoided by selecting a UE that is powered by a UPS or a battery when a disaster occurs. This makes it possible to respond to the occurrence of a disaster and perform flexible operation according to the situation.

[0123] In the first to third embodiments, the relay time parameters are exemplified as parameters related to the power source, but the relay time parameters are not limited to those related to the power source.

[0124] For example, the relay time parameter may be a time during which the communication device can function as a relay device, estimated from the location and speed of the communication device that can function as a relay device. In this case, the relay time parameter may indicate a time during which communication between the communication device and the base station 20 is likely to be maintained.

[0125] Also, the decision as to whether or not to allow a communication device to function as a relay device may be left to the communication device itself. In this case, for a communication device that is not permitted to function as a relay device, this may be indicated by a relay time parameter, and the communication device may ignore a received discovery request message.

[0126] Furthermore, when a time during which the device is permitted to function as a relay device is determined, the time may be indicated by a relay time parameter.

[0127] The conditions for allowing a terminal to function as a relay device may reflect the urgency indicated in the discovery request message or the type of service provided (purpose of relaying). For example, for special communications with high urgency, a connection state can be more reliably ensured by having many terminals (relay UEs) function as relay devices.

[0128] In the above first to third embodiments, an example is shown in which the relay time parameter is included in the discovery response message. However, the relay time parameter may be notified to the source of the discovery request message from a terminal capable of functioning as a relay device by a message (parameter notification signal) different from the discovery response message. In this case, the parameter notification signal may be returned from the terminal capable of functioning as a relay device in response to a request signal from the source of the discovery request message requesting the parameter notification signal.

[0129] Furthermore, in the present embodiment, the UE having the largest "relay time parameter" such as "remaining power" or "time" available for relaying is selected as the connection destination UE, but the present invention is not limited to this. For example, a list screen of UEs that support the Sidelink function found by the search can be displayed on a display unit such as a touch panel provided in the terminal 10, and the user can select a connection destination UE via the touch panel. In this case, the control unit may display a connection destination list in which display items indicating "remaining power" or "relay time parameter" are associated with display items indicating UE identification information (e.g., a label indicating Layer-2 ID) on the touch panel. Note that instead of the display items indicating "remaining power" or "relay time parameter", display items such as indicator icons indicating the remaining power or the relay possible time in several levels can also be displayed. When displaying the connection destination list as described above, the control unit 101 determines the connection destination UE based on a user operation on the touch panel.

[0130] In this way, when accepting an operation to select a UE that supports the sidelink function, it is possible to assist the user in selecting a connection destination by presenting the user with “relay time parameters” such as “remaining power” and the “time” during which relaying is possible.

[0131] As described above, according to the first to third embodiments, a terminal to be used as a relay UE is selected based on the relay time parameter, so that the time during which each terminal can function as a relay device can be reflected in the selection result, thereby ensuring stable sidelink communication.

[0132] For example, it is possible to avoid the inconvenience of establishing sidelink communication for a terminal (UE) with a low remaining battery power, which means that long-term sidelink communication is not guaranteed. It is also possible to avoid the problem of a terminal (UE) with a low remaining battery power being selected, which results in the terminal (UE) being disconnected from the network midway through communication, which means that it takes time to establish communication with another relay UE.

[0133] <Other embodiments> In the above-described embodiment, device discovery in sidelink operations for 5G New Radio (NR) is assumed, but is not limited thereto. Essentially, it is a successor specification to sidelink operations for 5G NR and is applicable to all successor standards that assume direct wireless communication between UEs.

[0134] The disclosure of this embodiment also includes the following configuration.

[0135] (Configuration 1) A receiving means for receiving detection signals transmitted from a plurality of communication devices for detecting the communication devices as sidelink devices, and a selecting means for selecting a target device to be connected as a relay device from among the plurality of communication devices detected by receiving the detection signals; the receiving means receives values ​​of relay time parameters transmitted from the plurality of communication devices before a connection with the target device is established, the relay time parameter relates to a time during which each of the plurality of communication devices is capable of functioning as a relay device, and the selecting means selects the target device based on the value of the relay time parameter associated with each of the plurality of communication devices.

[0136] (Configuration 2) 2. The sidelink communication device according to claim 1, wherein the value of the relay time parameter is included in the detection signal.

[0137] (Configuration 3) 3. The sidelink communications device according to configuration 1 or 2, further comprising a transmitting means for transmitting a discovery request signal to the outside, wherein the detection signal is a discovery response signal in response to the discovery request signal transmitted by the transmitting means.

[0138] (Configuration 4) The sidelink communication device according to configuration 3, wherein the discovery request signal transmitted by the transmission means is a Solicitation Message of 5G ProSe direct discovery.

[0139] (Configuration 5) The sidelink communication device according to any one of configurations 1 to 4, wherein the value of the relay time parameter is transmitted in a parameter notification signal separate from the detection signal.

[0140] (Configuration 6) A sidelink communication device described in any one of configurations 1 to 5, wherein the relay time parameter indicates whether the multiple communication devices are powered from a power source other than their own batteries, and the selection means selects, among the multiple communication devices, a communication device that is powered from a power source other than its own battery as the target device.

[0141] (Configuration 7) A sidelink communication device described in any one of configurations 1 to 5, wherein the relay time parameter indicates the remaining charge of a battery which is the power source of the target device, and the selection means selects as the target device a communication device among the multiple communication devices which has the maximum remaining battery charge or which is equal to or greater than a threshold value.

[0142] (Configuration 8) A sidelink communication device described in any one of configurations 1 to 5, wherein the relay time parameter indicates the remaining charge of a battery which is the power source of the target device and the power usage per hour of the target device, and the selection means selects the target device based on the remaining charge of the battery and the power usage.

[0143] (Configuration 9) The relay time parameter indicates whether the target device is powered from a commercial power source, A sidelink communication device according to any one of configurations 1 to 5, wherein the selection means selects, as the target device, a communication device among the plurality of communication devices that is powered from a power source other than a commercial power source.

[0144] (Configuration 10) A sidelink communication device having a transmission means for transmitting a detection signal to cause another sidelink device to detect the sidelink device as a sidelink device, the transmission means transmitting a value of a relay time parameter related to a time during which the sidelink device can function as a relay device to the other sidelink device before a connection with the other sidelink device is established.

[0145] (Configuration 11) 11. The sidelink communication device according to configuration 10, wherein the value of the relay time parameter is included in the detection signal.

[0146] (Configuration 12) The sidelink device further includes a receiving means for receiving a discovery request signal transmitted by another sidelink device, The discovery request signal received by the receiving means is a Soliciation Message of 5G ProSe direct discovery, the detection signal is a response to the Soliciation Message, and the response includes a value of the relay time parameter. The sidelink communication device according to configuration 10 or 11.

[0147] (Configuration 13) A sidelink communication device having a transmission means for transmitting a detection signal for causing another sidelink device to detect the sidelink device as a sidelink device, the transmission means transmitting information indicating a remaining battery charge of the sidelink communication device to the other sidelink device before a connection with the other sidelink device is established.

[0148] (Configuration 14) A control method for a communication device, comprising: a receiving control step of receiving detection signals transmitted from a plurality of communication devices for detecting the communication devices as sidelink devices; an acquisition step of acquiring values ​​of relay time parameters transmitted from the plurality of communication devices before a connection with the target device is established; and a selection step of selecting a target device to be connected as a relay device from among the plurality of communication devices detected by receiving the detection signals, wherein the relay time parameter is related to the time during which each of the plurality of communication devices is capable of functioning as a relay device, and in the selection step, the target device is selected based on the value of the relay time parameter for each of the plurality of communication devices.

[0149] (Configuration 15) 15. The control method according to claim 14, wherein the acquiring step acquires the value of the relay time parameter from the detection signal.

[0150] (Configuration 16) A method for controlling a communication device, comprising: a transmission control step of transmitting a detection signal for causing another sidelink device to detect the own device as a sidelink device, A control method characterized in that, before a connection with the other Sidelink device is established, the transmission control step transmits to the other Sidelink device a value of a relay time parameter related to a time during which the device can function as a relay device.

[0151] (Configuration 17) A method for controlling a communication device, comprising: a transmission control step of transmitting a detection signal for causing another sidelink device to detect the own device as a sidelink device, A control method, comprising the step of: before a connection with the other Sidelink device is established, the transmission control step transmitting information indicating a remaining battery level of the own device to the other Sidelink device.

[0152] (Configuration 18) 18. A program for causing a computer to execute the method for controlling a communication device according to any one of configurations 14 to 17.

[0153] (Configuration 19) A sidelink communication system including one or more first communication devices and a second communication device, each of the one or more first communication devices having a transmitting means for transmitting a detection signal for detecting the first communication device as a sidelink device, the second communication device having a receiving means for receiving the detection signal transmitted from the one or more first communication devices, and a selecting means for selecting a target device to be connected as a relay device from among the multiple first communication devices detected by the detection signal when multiple first communication devices are detected as a result of receiving the detection signal by the receiving means, the receiving means receiving a value of a relay time parameter transmitted from the one or more first communication devices before a connection with the target device is established, the relay time parameter being related to a time during which each of the one or more first communication devices is capable of functioning as a relay device, and the selecting means selecting the target device based on the value of the relay time parameter for each of the multiple first communication devices.

[0154] In addition, the present disclosure provides a program for implementing one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium. It can also be implemented by a process in which one or more processors in a computer of the system or device read and execute the program. It can also be implemented by a circuit (e.g., ASIC) that implements one or more of the functions.

[0155] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0156] 10 Terminal (second communication device) 10A Terminal (first communication device) 10B Terminal (first communication device) 10C Terminal (first communication device) 20 base station 100 Communication equipment 101 Control unit (selection means) 102 Storage section 103 Message Generation Unit 104 Message analysis processing unit 105 Communication unit (transmission means)

Claims

1. A communication device capable of Sidelink communication as defined by the 3GPP (3rd Generation Partnership Project) standard, a transmitting means for transmitting a request signal; a receiving means for receiving, from a plurality of communication devices, response signals in response to the request signals transmitted by the transmitting means; a selection means for selecting a target device to be connected as a relay device from among the plurality of communication devices that have received the response signal; and the receiving means receives, before a connection with the target device is established, values ​​of relay time parameters transmitted from the plurality of communication devices and relating to a time during which the terminal itself can function as a relay device; The communication device, wherein the selection means selects the target device based on the value of the relay time parameter associated with each of the plurality of communication devices.

2. 2. The communication device according to claim 1, wherein the value of the relay time parameter is included in the response signal.

3. the request signal is a discovery request signal for searching for a relay device, 2. The communication device according to claim 1, wherein the response signal is a discovery response signal that responds to the discovery request signal transmitted by the transmitting means.

4. The communication device according to claim 3 , wherein the discovery request signal transmitted by the transmission means is a Solicitation Message of 5G ProSe direct discovery.

5. 2. The communication device according to claim 1, wherein the value of the relay time parameter is transmitted as part of a parameter notification signal separate from the response signal.

6. the relay time parameter indicates whether the plurality of communication devices are powered by a power source other than their own batteries; 2. The communication device according to claim 1, wherein the selection means selects, as the target device, a communication device among the plurality of communication devices that is powered by a power source other than its own battery.

7. the relay time parameter indicates the remaining capacity of a battery that is a power source of the target device; 2. The communication device according to claim 1, wherein the selection unit selects, as the target device, a communication device from among the plurality of communication devices whose remaining battery power is the maximum or equal to or greater than a threshold value.

8. the relay time parameter indicates a remaining capacity of a battery that is a power source of the target device and an hourly power consumption of the target device; 2. The communication device according to claim 1, wherein the selection means selects the target device based on the remaining amount of the battery and the power consumption.

9. the relay time parameter indicates whether the target device is powered by a commercial power source; 2. The communication device according to claim 1, wherein the selection means selects, as the target device, a communication device among the plurality of communication devices that is powered by a power source other than a commercial power source.

10. A communication device capable of Sidelink communication as defined in the 3GPP (3rd Generation Partnership Project) standard, a transmitting means for transmitting a detection signal to cause another communication device to detect the device as a device capable of Sidelink communication; The communication device is characterized in that the transmitting means transmits to the other communication device a value of a relay time parameter related to the time during which the device can function as a relay device before a connection with the other communication device is established.

11. 11. The communication device according to claim 10, wherein the value of the relay time parameter is included in the detection signal.

12. The communication device further includes a receiving means for receiving a discovery request signal transmitted by another communication device, 11. The communication device according to claim 10, wherein the discovery request signal received by the receiving means is a Solicitation Message of 5G ProSe direct discovery, the detection signal is a response to the Solicitation Message, and the response includes the value of the relay time parameter.

13. A communication device capable of Sidelink communication as defined in the 3GPP (3rd Generation Partnership Project) standard, a transmitting means for transmitting a detection signal to cause another communication device to detect the device as a device capable of Sidelink communication; The communication device, wherein the transmitting means transmits information indicating a remaining battery level of the own device to the other communication device before a connection with the other communication device is established.

14. A control method for a communication device capable of Sidelink communication as defined in the 3GPP (3rd Generation Partnership Project) standard, comprising: a transmission control step of transmitting a request signal; a reception control step of receiving, from a plurality of communication devices, response signals in response to the request signals transmitted in the transmission control step; an acquisition step of acquiring values ​​of relay time parameters related to a time during which the communication devices can function as a relay device, the values ​​being transmitted from the plurality of communication devices, before a connection is established with a target device to be connected as a relay device; a selection step of selecting the target device from the plurality of communication devices that have received the response signal; and A control method, wherein in the selecting step, the target device is selected based on the value of the relay time parameter associated with each of the plurality of communication devices.

15. 15. The control method according to claim 14, wherein the acquisition step acquires the value of the relay time parameter from the response signal.

16. A control method for a communication device capable of Sidelink communication as defined in the 3GPP (3rd Generation Partnership Project) standard, comprising: a transmission control step of transmitting a detection signal to cause another communication device to detect the device as a device capable of Sidelink communication; A control method characterized in that, before a connection with the other communication device is established, the transmission control step transmits to the other communication device a value of a relay time parameter related to the time during which the device can function as a relay device.

17. A program for causing a computer to execute the method for controlling a communication device according to any one of claims 14 to 16.

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