Sidelink communication device, control method, program, and sidelink communication system

Abstract

The sidelink communication device comprises: a receiving unit (105) that receives detection signals transmitted from a plurality of communication devices (10A, 10B, 10C) and allowing the communication devices to be detected as sidelink devices; and a selection unit (101) that selects a target device to be connected as a relay device from among the plurality of communication devices (10A, 10B, 10C) detected by receiving the detection signal. Before establishing a connection with a target device, a receiving unit (105) receives values of relay time parameters transmitted from a plurality of communication devices. The relay time parameter is associated with a time at which each of the plurality of communication devices may function as a relay device. A selection unit (101) selects a target device on the basis of a value of a relay time parameter relating to each of a plurality of communication devices.

Description

Technical Field

[0001] The present disclosure relates to a sidelink communication device. Background Art

[0002] The third generation of the partnership program has recently been developed The development of the Long Term Evolution (LTE) and 5G New Radio (NR) specifications for 5G has been completed. Among these specifications, a standard specification called sidelink communication (hereinafter referred to as sidelink) has been developed. This specification enables direct wireless communication between terminals (user equipment (UE)) using an interface called PC5 without involving a mobile communication network (core network).

[0003] Furthermore, 3GPP has been developing formulation of specifications for extending the side link communication range through a side link relay function for relaying the side link communication via a relay device (relay UE).

[0004] Patent Document 1 discusses a technology in which a terminal (UE) located outside the coverage of a base station is connected to a relay device installed within the coverage of the base station via side link communication, thereby making it possible to establish communication with the base station.

[0005] Citation List

[0006] Patent Literature

[0007] PTL1: Japanese Patent Application Publication No. 2021-078140 Summary of the invention

[0008] Technical issues

[0009] However, in the case where one communication device selects another communication device from among multiple communication devices as a relay device and connects to the selected relay device via side link communication to communicate with a base station, it is difficult to select an appropriate relay device from among the multiple communication devices because the time at which each communication device can be used as a relay device may be different.

[0010] The present invention is made in view of at least one of the above problems. One aspect of the present disclosure is to be able to select an appropriate relay device from a plurality of communication devices.

[0011] Solution to the problem

[0012] According to an aspect of the present invention, a side-link communication device comprises: a receiving unit configured to receive a detection signal for detecting each of a plurality of communication devices as a side-link device, the detection signal being sent from the plurality of communication devices; and a selecting unit configured to select a target device to be connected as a relay device from the plurality of communication devices detected upon reception of the detection signal, wherein before establishing a connection with the target device, the receiving unit receives a relay time parameter value sent from each of the plurality of communication devices, wherein the relay time parameter is associated with a time during which each of the plurality of communication devices is capable of being used as a relay device, and wherein the selecting unit selects the target device based on the relay time parameter value corresponding to each of the plurality of communication devices.

[0013] Advantageous Effects of the Invention

[0014] According to one aspect of the present disclosure, an appropriate relay device may be selected from a plurality of communication devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] [ Figure 1 ] Figure 1 is a diagram illustrating a configuration example of a communication system according to the first exemplary embodiment.

[0016] [ Figure 2 ] Figure 2 is a block diagram illustrating a functional configuration example of a communication device.

[0017] [ Figure 3 ] Figure 3 is a diagram illustrating an example of the format of a discovery response message according to the first exemplary embodiment.

[0018] [ Figure 4 ] Figure 4 is a flowchart illustrating a discovery process in terminal 10 according to the first exemplary embodiment.

[0019] [ Figure 5 ] Figure 5 : is a flowchart illustrating a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C according to the first exemplary embodiment.

[0020] [ Figure 6 ] Figure 6 is a sequence chart illustrating an operation example of the communication system according to the first exemplary embodiment.

[0021] [ Figure 7 ] Figure 7 is a diagram illustrating an example of the format of a discovery request message in the case of including battery information.

[0022] [ Figure 8 ] Figure 8 is a diagram illustrating an example of the format of a discovery response message according to the second exemplary embodiment.

[0023] [ Fig. 9 ] Fig. 9 is a flowchart illustrating a discovery process in terminal 10 according to the second exemplary embodiment.

[0024] [ Fig.10 ] Fig.10 : is a flowchart illustrating a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C according to the second exemplary embodiment.

[0025] [ Fig.11 ] Fig.11 is a sequence chart illustrating an operation example of the communication system according to the second exemplary embodiment.

[0026] [ Fig.12 ] Fig.12 is a diagram illustrating an example of the format of a discovery response message according to the third exemplary embodiment.

[0027] [ Fig.13 ] Fig.13 is a flowchart illustrating a discovery process in terminal 10 according to the third exemplary embodiment.

[0028] [ Fig.14 ] Fig.14 : is a flowchart illustrating a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C according to the third exemplary embodiment.

[0029] [ Fig.15 ] Fig.15 is a sequence chart illustrating an operation example of the communication system according to the third exemplary embodiment. DETAILED DESCRIPTION

[0030] The exemplary embodiments will be described in detail below with reference to the accompanying drawings. Note that the following exemplary embodiments are not intended to limit the scope of the claimed invention. In the exemplary embodiments, multiple features are described, but no limitation is imposed on the invention requiring all such features, and multiple such features may be appropriately combined. In addition, in the accompanying drawings, the same reference numerals are given to the same or similar configurations, and redundant descriptions thereof are omitted.

[0031] The sidelink communication is based on the premise that the sidelink function of the terminal is always turned on and power consumption is not considered. Therefore, the sidelink communication can be established even with a user equipment (UE) with a low battery remaining amount, so that long-term sidelink communication cannot be ensured.

[0032] In the above case, when the user equipment (UE) having the side link relay function is driven by a battery, the power supply is limited, and therefore the available time is limited. Therefore, for example, if the UE (remote UE) intended to use the side link relay is intended to establish long-term communication, the UE (relay UE) providing the side link relay requires sufficient battery remaining to drive the UE for a long period of time.

[0033] There are some problems: if the battery remaining amount of the relay UE is low, the available time of the relay UE is reduced, and if the battery of the relay UE is exhausted, the remote UE is disconnected from the network until communication can be established with another relay UE.

[0034] A communication system and the like that take the above-mentioned problems into consideration are disclosed below.

[0035] <First Exemplary Embodiment>

[0036] [System Configuration]

[0037] Figure 1 is a diagram illustrating a configuration example of a side link communication system.

[0038] exist Figure 1 In the example, the terminal 10 (an example of a sidelink device) serving as a remote UE is located outside the range of the communication area 20A of the base station 20. The terminal 10 searches for a device (UE) to connect to so that the sidelink relay communication can be established.

[0039] exist Figure 1 In the example, the terminals 10A, 10B, and 10C (examples of multiple communication devices) used as relay UEs (examples of side link devices and target devices) are terminals that support side link relay communication. These terminals are located within the range of the communication area 20A of the base station 20 and are configured to respond to searches from the terminal 10. Although this exemplary embodiment assumes the case where a smartphone or the like is used as a terminal that supports side link relay communication, the terminal is not limited to a smartphone or the like. For example, communication terminals such as tablet terminals and personal computers (PCs), wearable terminals such as smart watches and head-mounted displays, car navigation devices installed in cars, and the like can be used.

[0040] Each of the terminals 10A, 10B, and 10C holds a parameter (hereinafter referred to as a "relay time parameter") associated with the time during which the corresponding terminal (its own terminal) can be used as a relay device. The relay time parameter indicates, for example, the power source type (whether a battery is used), the battery type, the remaining battery level, the service available time based on the remaining battery level, and the like.

[0041] [Functional configuration of the device]

[0042] Next, the functional configuration of the communication device 100 according to the present exemplary embodiment will be described. Note that the configuration of the functional blocks to be described below is only an example. Some (or all in some cases) of the functional blocks to be described below may be replaced with other functional blocks having similar functions, some functional blocks may be omitted, or additional functional blocks may be added. One of the functional blocks to be described below may be divided into a plurality of functional blocks, or a plurality of functional blocks may be integrated into one functional block.

[0043] Figure 2 is a block diagram illustrating an example of a functional configuration of a communication device.

[0044] The communication device 100 composed of each of the terminal 10, the terminal 10A, the terminal 10B, and the terminal 10C includes Figure 2 Specifically, the communication device 100 includes a control unit 101 (an example of a selection unit), 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 unit and a reception unit).

[0045] The control unit 101 controls the operation of the communication device 100. The control unit 101 is composed of one or more processors such as a central processing unit (CPU) or a microprocessing unit (MPU), for example, and executes a computer program loaded into a random access memory (RAM) as a storage unit 102, thereby controlling the overall operation of the communication device. Note that the reception control and transmission control performed by the terminal 10 based on the flowchart to be described below are implemented so that the processor such as the CPU or the MPU of the control unit 101 and the hardware such as the communication unit 105 operate in cooperation.

[0046] The storage unit 102 is a RAM or a nonvolatile storage area that stores a control program, other information, and information related to communication to be used by the control unit 101 to perform control processing. The control program stored in the nonvolatile storage area is loaded into the RAM and executed by the processor constituting the control unit 101. Therefore, the control unit 101 and the storage unit 102 function as a so-called computer.

[0047] The message generating unit 103 generates a discovery message to be transmitted to detect a UE and other messages.

[0048] The message analysis processing unit 104 analyzes a discovery message and other messages received from another communication device. Note that functions corresponding to the generation unit 103 and the analysis processing unit 104 may be implemented as software modules to be implemented by the control unit 101 .

[0049] The communication unit 105 complies with the 3GPP Standard base station 20 ( Figure 1 ) performs cellular network communication such as Long Term Evolution (LTE) or 5G. In addition, the communication unit 105 sends information to and receives information from another communication terminal supporting sidelink communication via sidelink communication. The communication unit 105 performs a process of sending a message generated by the message generation unit 203 and a process of receiving a message from another terminal (UE).

[0050] As described above, the operation of the communication device 100 can be implemented such that the control unit 101 executes the control program stored in the storage unit 102 , thereby performing calculation and processing of information and performing control of each hardware.

[0051] [Processing example]

[0052] Figure 3 is a diagram illustrating an example of the format of a discovery response message.

[0053] exist Figure 3 In the message, the layer-2ID indicating the destination of the information is stored as "destination layer-2ID". The layer-2ID indicating the source of the information is stored as "source layer-2ID". Information indicating the type of this message is stored as "type of discovery message". Identification information about the UE that has sent the discovery response message is stored as "discovery information". Identification information about the connection service provided by the UE that has sent the discovery response message is stored as "relay service code (RSC)".

[0054] exist Figure 3 In the , information indicating whether the corresponding terminal is receiving power fed from the power source is stored as "power feeding flag (Flg)". Specifically, if the corresponding terminal is receiving power fed from another power source, "ON" is stored as "power feeding Flg", and if the corresponding terminal is driven by the battery of the corresponding terminal, "OFF" is stored as "power feeding Flg". In addition, in Figure 3 In the example embodiment, the battery remaining amount of the corresponding terminal is stored as “battery remaining amount.” In the present exemplary embodiment, “power feeding Flg” and “battery remaining amount” correspond to the relay time parameter.

[0055] Figure 4 is a flowchart illustrating a discovery process in the terminal 10 .

[0056] exist Figure 4 In step S102, the communication device 100 ( Figure 2) The control unit 101 activates the message generation unit 103 to generate a discovery request message, and the communication unit 105 performs broadcast transmission of the discovery request message. The discovery signal used as the discovery request message may be a Soliciation message. Specifically, the discovery signal may be a Soliciation message for 5G ProSe direct discovery or 5G ProSe UE to network relay discovery. Note that ProSe stands for Proximity-based Service.

[0057] In step S104, the control unit 101 causes the communication unit 105 to wait for a discovery response message as a detection signal to be transmitted from another terminal. If the discovery response message is received, the process proceeds to step S106. The discovery response signal used as the discovery response message may be a response message of the above-mentioned Soliciation message.

[0058] In step S106 , the control unit 101 stores the discovery response message whose reception is confirmed in step S104 in the storage unit 102 .

[0059] In step S108, the control unit 101 determines whether a predetermined period of time has passed after the transmission of the discovery request message. If the determination result indicates yes, the process proceeds to step S110. If the determination result indicates no, the process proceeds to step S104.

[0060] In step S110, the control unit 101 activates the message analysis processing unit 204 to analyze the content of the discovery response message stored in step S106. In addition, the control unit 101 determines through the message analysis processing unit 104 whether the discovery response message stored in step S106 includes "ON" stored as "power feed Flg" ( Figure 3 ) discovery response information. If the determination result of the control unit 101 indicates yes, the process proceeds to step S112. If the determination result indicates no, the process proceeds to step S114.

[0061] In step S112, the control unit 101 selects a connection destination from the terminal (UE) that has returned a discovery response message in which "ON" is stored as "power feeding Flg". In addition, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the process. Thus, communication for a side link connection is established between the terminal 10 and the selected terminal (UE). In other words, communication using the selected terminal (UE) as a relay device can be established.

[0062] In step S114, the message analysis processing unit 204 checks the "battery remaining amount" ( Figure 3), and selects the terminal (UE) with the largest battery remaining amount as the connection destination. In this case, the terminal with a battery remaining amount greater than or equal to the threshold value can be selected as the connection destination. In addition, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the processing. Therefore, communication for the side link connection is established between the terminal 10 and the selected terminal (UE). In other words, communication using the selected terminal (UE) as a relay device can be established.

[0063] Figure 5 is a flowchart illustrating the discovery response processing in the terminal 10A, the terminal 10B, and the terminal 10C. Figure 5 In step S202 of , the control unit 101 of the communication device 100 composed of each of the terminal 10A, the terminal 10B, and the terminal 10C makes the communication unit 105 wait for a discovery request message. If the control unit 101 has received the discovery request message, the process proceeds to step S204.

[0064] In step S204, the control unit 101 activates the message generation unit 103 to generate a discovery response message ( Figure 3 ). In this case, the message generation unit 103 checks the battery status of the corresponding terminal, and stores parameters corresponding to “power feeding Flg” and “battery remaining amount” in the discovery response message.

[0065] In step S206 , the control unit 101 causes the communication unit 105 to transmit the discovery response message generated in step S204 to the transmission source (UE) that has transmitted the discovery request message, and terminates the processing.

[0066] Figure 6 is a sequence diagram illustrating an operation example of the communication system according to the present exemplary embodiment. Figure 6 The step numbers in correspond to Figure 4 and Figure 5 The corresponding processing shown in .

[0067] exist Figure 6 In the example of , the terminal 10A is receiving power fed from another power source instead of receiving power from its own battery. The terminal 10B and the terminal 10C are each driven by the battery of the corresponding terminal (their own terminal) and have battery remaining amounts of 100 mAh and 10 mAh, respectively.

[0068] like Figure 6 As shown in , the terminal 10 causes the message generation unit 103 to generate a discovery request message, and performs broadcast transmission of the discovery request message (step S102).

[0069] After receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10A generates a discovery response message (step S204) and returns the discovery response message to the terminal 10 (step S206). In this case, since the terminal 10A is receiving power fed from another power source, "ON" is set to "power feeding Flg" in the discovery response message.

[0070] Similarly, upon receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10B generates a discovery response message (step S204) and returns the discovery response message to the terminal 10 (step S206). In this case, the terminal 10A operates using power from its own battery, so "OFF" is set as "Power Feed Flg" in the discovery response message. In addition, "100mAh" is set as "Battery Remaining Amount" in the discovery response message.

[0071] Similarly, upon receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10C generates a discovery response message (step S204) and returns the discovery response message to the terminal 10 (step S206). In this case, the terminal 10A operates using power from its own battery, so "OFF" is set as "Power Feed Flg" in the discovery response message. In addition, "10mAh" is set as "Battery Remaining Amount" in the discovery response message.

[0072] Next, the terminal 10 selects the terminal 10A as the connection destination UE based on the “power feeding Flg” and the “battery remaining amount” in the received discovery response message, and establishes a side link connection with the terminal 10A (step S112 ).

[0073] Note that if terminal 10A is powered by its own battery like terminal 10B and terminal 10C, then Figure 4 As shown in , terminal 10 selects the terminal with the largest "battery remaining amount" in the discovery response message. Then, terminal 10 establishes a side link connection with the selected terminal (step S114). Alternatively, terminal 10 can establish a side link connection with one of the terminals with a battery remaining amount greater than or equal to a threshold value based on the "battery remaining amount" in the discovery response message. In this case, if there are multiple terminals with a battery remaining amount greater than or equal to the threshold, the terminal with the largest "battery remaining amount" can be selected, or a terminal other than the terminal with the largest "battery remaining amount" can be selected based on a combination with other factors.

[0074] As described above, the terminal 10 selects a UE that can provide a side link function for a longer period of time based on the relay time parameter, thereby making it possible to establish a connection with the UE.

[0075] In the above exemplary embodiments, the relay time parameter is always stored in the discovery response message. However, the discovery request message to be sent may include battery information (information requesting a reply of the relay time parameter).

[0076] Figure 7 is a diagram illustrating an example of the format of a discovery request message in the case of including battery information.

[0077] exist Figure 7 In the message, the layer-2ID indicating the destination of the information is stored as "destination layer-2ID". The layer-2ID indicating the source of the information is stored as "source layer-2ID". Information indicating the type of this message is stored as "type of discovery message". Identification information about the UE that has sent the discovery response message is stored as "discovery information". Identification information about the connection service provided by the UE that has sent the discovery response message is stored as "relay service code (RSC)". Identification information about the discovery target UE is stored as "target information". When the discovery target UE has been identified, the "target information" can be stored. In the case of a reply requesting a relay time parameter, "ON" is stored as "battery information".

[0078] If the request message contains "battery information", then Figure 4 In step S102, the message generating unit 103 generates Figure 7 , and the communication unit 105 performs broadcast transmission of the discovery request message.

[0079] exist Figure 5 In step S204, the message generating unit 103 may store the relay time parameter in the discovery response message only when the battery information is included in the discovery request message.

[0080] With this configuration, for example, in an emergency, a connection destination UE can be selected based on the relay time parameter included in the discovery response message. Therefore, a flexible operation depending on a situation such as the presence or absence of an emergency can be performed.

[0081] Note that this exemplary embodiment illustrates 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). However, the same process can also be applied to a case where a relay UE sends a discovery signal without receiving any discovery request ("Model A" in TR23.752 6.19.1.1). In the latter case, a relay time parameter may be included in the discovery signal, and the terminal 10 may 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 the connection target terminal. This is also true for the second exemplary embodiment and the third exemplary embodiment to be described below. The discovery request message is an example of a discovery request signal.

[0082] <Second Exemplary Embodiment>

[0083] The above-mentioned first exemplary embodiment illustrates an example of selecting and connecting a relay UE that can be connected for a longer period of time based on the "power feed Flg" and "battery remaining amount" stored in the discovery response message. The second exemplary embodiment illustrates an example of selecting and connecting a relay UE that can be connected for a longer period of time based on the "service available time" stored in the discovery response message.

[0084] System configuration of the communication device 100 according to the second exemplary embodiment ( Figure 1 ) and function configuration ( Figure 2 ) are similar to those of the first exemplary embodiment. Differences from the first exemplary embodiment will be described below.

[0085] [Processing example]

[0086] Figure 8 is a diagram illustrating an example of the format of a discovery response message according to the second exemplary embodiment.

[0087] exist Figure 8 In the message, the layer-2ID indicating the destination of the information is stored as "destination layer-2ID". The layer-2ID indicating the source of the information is stored as "source layer-2ID". Information indicating the type of this message is stored as "type of discovery message". Identification information about the UE that has sent the discovery response message is stored as "discovery information". Identification information about the connection service provided by the UE that has sent the discovery response message is stored as "relay service code (RSC)".

[0088] exist Figure 8In the example, a time period during which a sidelink relay function included in a corresponding terminal serving as a relay UE can be provided is stored as a relay time parameter "service available time". If there is no restriction on the time period during which the sidelink relay function can be provided, "0" is stored as the service available time. If there is a restriction on the time period during which the sidelink relay function can be provided, the time period during which the sidelink relay function can be provided is stored as a time in minutes, for example.

[0089] Fig. 9 is a flowchart illustrating a discovery process in the terminal 10 .

[0090] exist Fig. 9 In step S102, the communication device 100 ( Figure 2 )'s control unit 101 activates the message generation unit 103 to generate a discovery request message, and the communication unit 105 performs broadcast transmission of the discovery request message.

[0091] In step S104, the control unit 101 causes the communication unit 105 to wait for a discovery response message to be transmitted from another terminal. If the discovery response message is received, the process proceeds to step S106.

[0092] In step S106 , the control unit 101 stores the discovery response message whose reception is confirmed in step S104 in the storage unit 102 .

[0093] In step S108, the control unit 101 determines whether a predetermined period of time has passed after the transmission of the discovery request message. If the determination result indicates yes, the process proceeds to step S120. If the determination result indicates no, the process proceeds to step S104.

[0094] In step S120, the control unit 101 activates the message analysis processing unit 204. In addition, the control unit 101 analyzes the content of the discovery response message stored in step S106. In addition, the control unit 101 determines whether the discovery response message stored in step S106 includes discovery response information in which "0" is stored as "service available time" based on the analysis result. If the determination result of the control unit 101 indicates yes, the process proceeds to step S122. If the determination result indicates no, the process proceeds to step S124.

[0095] In step S122, the control unit 101 selects a connection destination from the terminals (UEs) that have returned a discovery response message in which "0" is stored as the "service available time." Furthermore, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the process.

[0096] In step S124, the message analysis processing unit 204 checks the "service available time" in the discovery response message stored in step S106, and selects the terminal (UE) with the longest "service available time" as the connection destination. In addition, the control unit 101 starts a side link connection with the selected connection destination and terminates the processing.

[0097] Fig.10 is a flowchart illustrating a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C.

[0098] exist Figure 5 In step S202 of , the control unit 101 of the communication device 100 composed of each of the terminal 10A, the terminal 10B, and the terminal 10C makes the communication unit 105 wait for a discovery request message. If the control unit 101 has received a discovery request message, the process proceeds to step S210.

[0099] In step S210, the control unit 101 determines whether to use an external power source as the power source of the corresponding terminal. If the determination result indicates yes, the process proceeds to step S220. If the determination result indicates no, the process proceeds to step S212. Note that if the determination result in step S210 indicates no, the power source of the corresponding terminal is the battery of the corresponding terminal.

[0100] In step S212, the control unit 101 calculates the transmission radio field strength of the base station 20 based on the distance between the corresponding terminal and the base station 20. In this case, the storage unit 102 stores the position information (coordinates) of the base station 20. The position information (coordinates) of the corresponding terminal can be obtained by a global positioning system (GPS) or the like included in the corresponding terminal. In step S212, the control unit 101 calculates the distance between the corresponding terminal and the base station 20 based on the coordinates of the base station 20 and the position information (coordinates) of the corresponding terminal, and also calculates the transmission radio field strength based on the calculated distance.

[0101] In step S214, the control unit 101 calculates the transmission radio field strength between the corresponding terminal and the remote UE based on the distance from the UE (remote UE) that has sent the discovery request. For example, the terminal 10 used as the remote UE can send the coordinates of the remote UE in the discovery request. In this case, the control unit 101 can calculate the transmission radio field strength between the corresponding terminal and the remote UE based on the coordinates of the remote UE.

[0102] In step S216, the control unit 101 obtains the remaining battery level in the corresponding terminal. In addition, the control unit 101 calculates the "service available time" based on the transmission radio field strength calculated in step S212, the transmission radio field strength calculated in step S214, and the obtained battery remaining level. The "service available time" corresponds to the time during which the corresponding terminal can be continuously used as a relay UE (relay device).

[0103] In step S218, the control unit 101 causes the message generation unit 103 to generate a discovery response message. The "service available time" calculated in step S216 is stored in the discovery response message.

[0104] On the other hand, in step S220, the control unit 101 causes the message generation unit 103 to generate a discovery response message. In this discovery response message, "0" is stored as the "service available time".

[0105] In step S222, the discovery response message generated in step S218 or step S220 is sent to the UE that has sent the discovery request message, and the process is terminated.

[0106] In the above steps S212 to S216, the "service available time" is calculated based on the transmission radio field strength. Alternatively, the "service available time" may be calculated based on the hourly power usage required for the relay UE to use the relay function.

[0107] Specifically, in step S212, the control unit 101 may calculate the hourly power usage of all functions being used by the relay UE, and in step S214, the control unit 101 may calculate the hourly power usage required for the side link relay. In this case, in step 216, the control unit 101 may calculate the "service available time" based on the hourly power usage calculated in steps S212 and S214 and the remaining battery power.

[0108] Fig.11 is a sequence diagram illustrating an operation example of the communication system according to the present exemplary embodiment. Fig.11 The step numbers in correspond to Fig. 9 and Fig.10 in the processing.

[0109] exist Fig.11In the example of , terminal 10A is receiving power fed from another power source instead of receiving power from its own battery, and there is no limit on the "service available time". Terminal 10B and terminal 10C are each driven by their own batteries. The "service available time" calculated for terminal 10B in steps S212 to S216 and the "service available time" calculated for terminal 10C in steps S212 to S216 are 20 minutes and 30 minutes, respectively.

[0110] like Fig.11 As shown in FIG. 1 , the terminal 10 causes the message generation unit 103 to generate a discovery request message and perform broadcast transmission of the discovery request message (step S102 ).

[0111] After receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10A generates a discovery response message (step S220) and returns the discovery response message to the terminal 10 (step S222). In this case, the terminal 10A is receiving power fed from another power source and has no restrictions on the service available time. Therefore, "0" is set as the service available time in the discovery response message (step S220).

[0112] Similarly, after receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10B generates a discovery response message (step S218) and returns the discovery response message to the terminal 10 (step S222). In this case, the terminal 10B operates using the power from its own battery, so the calculation result "20 minutes" is set as the service available time in the discovery response message (step S218).

[0113] Similarly, after receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10C generates a discovery response message (step S218) and returns the discovery response message to the terminal 10 (step S222). In this case, the terminal 10C operates using power from its own battery, so the calculation result "30 minutes" is set as the service available time in the discovery response message (step S218).

[0114] Next, the terminal 10 selects the terminal 10A as the connection destination UE based on the “service available time” in the received discovery response message, and establishes a side link connection with the terminal 10A (step S122 ).

[0115] Note that if terminal 10A is powered by its own battery like terminal 10B and terminal 10C, then Fig. 9 As shown in , the terminal 10 selects a terminal having the largest "service available time" in the discovery response message. Then, the terminal 10 establishes a side link connection with the selected terminal (step S124).

[0116] As described above, the terminal 10 selects a UE that can provide a side link function for a longer period of time based on the relay time parameter, thereby making it possible to establish a connection with the UE.

[0117] <Third Exemplary Embodiment>

[0118] The third exemplary embodiment illustrates an example in which a relay UE that can be connected for a longer period of time is selected and connected based on the “power source type” and the “remaining power” stored in the discovery response message.

[0119] System configuration of the communication device 100 according to the third exemplary embodiment ( Figure 1 ) and function configuration ( Figure 2 ) are similar to those of the first exemplary embodiment. Differences from the first exemplary embodiment will be described below.

[0120] [Processing example]

[0121] Fig.12 is a diagram illustrating an example of the format of a discovery response message according to the third exemplary embodiment.

[0122] exist Fig.12 In the , the layer-2ID indicating the destination of the information is stored as "destination layer-2ID". The layer-2ID indicating the source of the information transmission is stored as "source layer-2ID". Information indicating the type of this message is stored as "type of discovery message".

[0123] Identification information about the UE that has transmitted the discovery response message is stored as “discovery information.” Identification information about a connection service provided by the UE that has transmitted the discovery response message is stored as “Relay Service Code (RSC).”

[0124] exist Fig.12 , the type of power supply that feeds power to the terminal is stored as "power supply type". The battery types that can be set include "commercial power supply", "uninterruptible power supply (UPS)", "secondary battery" and "primary battery". In addition, the remaining amount of the battery is stored as "remaining power". If "commercial power supply" or "UPS" is set as the power supply type, "0" is stored as the remaining power. In the present exemplary embodiment, "power supply type" and "remaining power" correspond to the relay time parameter.

[0125] Fig.13 is a flowchart illustrating a discovery process in the terminal 10 .

[0126] exist Fig.13 In step S102, the communication device 100 ( Figure 2)'s control unit 101 activates the message generation unit 103 to generate a discovery request message, and the communication unit 105 performs broadcast transmission of the discovery request message.

[0127] In step S104, the control unit 101 causes the communication unit 105 to wait for a discovery response message to be transmitted from another terminal. If the discovery response message is received, the process proceeds to step S106.

[0128] In step S106 , the control unit 101 stores the discovery response message whose reception is confirmed in step S104 in the storage unit 102 .

[0129] In step S108, the control unit 101 determines whether a predetermined period of time has passed after the transmission of the discovery request message. If the determination result indicates yes, the process proceeds to step S130. If the determination result indicates no, the process proceeds to step S104.

[0130] In step S130, the control unit 101 activates the message analysis processing unit 204 to determine whether the discovery response message stored in step S106 includes discovery response information that "UPS" is stored as the "power source type". If the determination result of the control unit 101 indicates yes, the process proceeds to step S132. If the determination result indicates no, the process proceeds to step S134.

[0131] In step S132, the control unit 101 selects a connection destination from the terminals (UEs) that have returned a discovery response message in which “UPS” is stored as the “power source type.” Furthermore, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the process.

[0132] In step S134, the control unit 101 determines whether a disaster notification has been issued from the gNB while ensuring the connection between the corresponding terminal (terminal 10) and the gNB. If the determination result of the control unit 101 indicates yes, the process proceeds to step S136. If the determination result indicates no, the process proceeds to step S138.

[0133] In step S136, the control unit 101 causes the message analysis processing unit 204 to determine whether "secondary battery" or "primary battery" is stored as the "power source type" in the discovery response message stored in step S106. If the determination result of the control unit 101 indicates yes, the process proceeds to step S140. If the determination result indicates no, the process proceeds to step S142.

[0134] In step S140, the control unit 101 causes the message analysis processing unit 204 to check the "remaining power" in the discovery response message stored in step S106, and selects the UE with the largest "remaining power" as the connection destination UE. The control unit 101 starts the side link connection with the selected connection destination UE and terminates the processing.

[0135] In step S142, the control unit 101 selects a connection destination from the terminals (UEs) that have returned a discovery response message in which "commercial power" is stored as the power type. Furthermore, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the process.

[0136] In step S138, the control unit 101 causes the message analysis processing unit 204 to determine whether the discovery response message stored in step S106 includes a discovery response message in which "commercial power" is stored as the "power type". If the determination result of the control unit 101 indicates yes, the process proceeds to step S144. If the determination result indicates no, the process proceeds to step S146.

[0137] In step S144, the control unit 101 selects a connection destination from the terminals (UEs) that have returned a discovery response message in which "commercial power" is stored as the power type. Furthermore, the control unit 101 starts a side link connection with the selected terminal (UE) and terminates the process.

[0138] In step S146, the control unit 101 causes the message analysis processing unit 204 to check the "remaining power" in the discovery response message stored in step S106, and selects the UE with the largest "remaining power" as the connection destination UE. The control unit 101 starts the side link connection with the selected connection destination UE and terminates the processing.

[0139] Fig.14 is a flowchart illustrating a discovery response process in the terminal 10A, the terminal 10B, and the terminal 10C.

[0140] exist Fig.14 In step S202, the control unit 101 of the communication device 100 composed of each of the terminal 10A, the terminal 10B, and the terminal 10C makes the communication unit 105 wait for a discovery request message. If the control unit 101 has received the discovery request message, the process proceeds to step S230.

[0141] In step S230, the control unit 101 activates the message generation unit 103 to generate a discovery response message ( Figure 3 ). In this case, the control unit 101 checks the power state of the corresponding terminal and stores information corresponding to the "power type" and the "remaining power" in the discovery response message.

[0142] In step S232 , the control unit 101 causes the communication unit 105 to transmit the discovery response message generated in step S230 to the transmission source (UE) that has transmitted the discovery request message, and terminates the process.

[0143] Fig.15 is a sequence diagram illustrating an operation example of the communication system according to the present exemplary embodiment. Fig.15 The step numbers in correspond to Fig.13 and Fig.14 The processing shown in .

[0144] exist Fig.15 In the example of , the terminal 10A is receiving power fed from the UPS. The terminal 10B is receiving power fed from the commercial power supply, and the terminal 10C is operating using power from its own secondary battery. The battery remaining amount in the terminal 10C is 100 mAh.

[0145] like Fig.15 As shown in FIG. 1 , the terminal 10 causes the message generation unit 103 to generate a discovery request message and perform broadcast transmission of the discovery request message (step S102 ).

[0146] After receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10A generates a discovery response message (step S230) and returns the discovery response message to the terminal 10 (step S232). In this case, since the terminal 10A is receiving power fed from the UPS, "UPS" is set as the "power type" and "0" is set as the "remaining power" in the discovery response message.

[0147] Similarly, after receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10B generates a discovery response message (step S230) and returns the discovery response message to the terminal 10 (step S232). In this case, since the terminal 10B is receiving power fed from the commercial power supply, "commercial power supply" is set as the "power supply type" and "0" is set as the "remaining power" in the discovery response message.

[0148] Similarly, after receiving the discovery request message from the terminal 10 (step S202; yes), the terminal 10C generates a discovery response message (step S230) and returns the discovery response message to the terminal 10 (step S232). In this case, the terminal 10C operates using power from a secondary battery, and the remaining battery capacity of the secondary battery is 100 mAh. Therefore, in the discovery response message, "secondary battery" is set as "power type" and "100 mAh" is set as "remaining power".

[0149] Next, the terminal 10 selects the terminal 10A as the connection destination UE based on the power source type (“UPS”) in the received discovery response message, and establishes a side link connection with the terminal 10A (step S132 ).

[0150] Therefore, the terminal 10 can select and connect to a UE that can provide a side link function for a longer period of time based on the relay time parameter.

[0151] Note that, as mentioned above, Fig.13 In step S134, the terminal 10 determines whether a disaster notification has been issued from the gNB before the terminal 10 is disconnected from the gNB, assuming that in the event of a disaster, a connection cannot be established with the gNB of the terminal that is the connection destination of the terminal 10 due to a power outage, and the terminal 10 aims to search for a terminal serving as a relay UE in an out-of-coverage situation. For example, in a case where a disaster has already occurred, if a relay UE that is receiving power fed from a commercial power source is selected, the connection with the relay UE may be disconnected due to a power outage. On the other hand, in the third exemplary embodiment, in the event of a disaster, the above situation can be avoided by selecting a UE to be driven by a UPS or a battery. Therefore, the communication system can cope with the occurrence of a disaster, so that flexible operations can be performed depending on the situation.

[0152] The above-mentioned first to third exemplary embodiments illustrate an example in which a parameter associated with a power source is used as a relay time parameter. However, the relay time parameter is not limited to a parameter associated with a power source.

[0153] For example, the time during which each communication device can be used as a relay device can be estimated based on the position and speed of the communication device used as a relay device. In this case, the time period during which communication between the communication device and the base station 20 can be maintained can be indicated by a relay time parameter.

[0154] In addition, the communication device may be allowed to determine whether to act as a relay device. In this case, the relay time parameter for the communication device not allowed to act as a relay device may indicate that the communication device is not allowed to act as a relay device, and the communication device may ignore the received discovery request message.

[0155] Furthermore, if a time period or the like during which a communication device is allowed to function as a relay device is determined, the time period or the like may be indicated by a relay time parameter.

[0156] The emergency situation indicated in the discovery request message or the type of each provided service (the purpose of relay) can be reflected in the conditions for allowing the communication device to be used as a relay device. For example, in special communications with a high emergency level, a larger number of terminals (relay UEs) can be used as relay devices, so that the connection state can be more reliably ensured.

[0157] The first exemplary embodiment to the third exemplary embodiment described above illustrate an example in which the relay time parameter is included in the discovery response message. However, the terminal that can be used as a relay device can send a notification about the relay time parameter as a message (parameter notification signal) different from the discovery response message to the transmission source that has sent the discovery request message. In this case, the terminal that can be used as a relay device can return the parameter notification signal in response to the request signal for requesting the parameter notification signal from the transmission source that has sent the discovery request message.

[0158] Although the present exemplary embodiment illustrates an example in which a UE having a maximum "relay time parameter" (such as "remaining power" or a "time period" in which the relay function can be used) is selected as a connection destination UE, the present exemplary embodiment is not limited to this example. For example, the following configuration may also be adopted: a screen showing a list of UEs that support the side link function and have been found in the search is displayed on a display unit such as a touch panel included in the terminal 10, and the user is caused to select the connection destination UE via the touch panel. In this case, the control unit may display a connection destination list on the touch panel, in which display items indicating "remaining power" and "relay time parameter" are associated with display items indicating identification information about each UE (e.g., a label indicating a layer-2 ID). Instead of displaying display items such as "remaining power" and "relay time parameter", a display item such as an indicator icon indicating the remaining power or possible relay time in several levels may be displayed. As described above, if the connection destination list is displayed, the control unit 101 determines the connection destination UE based on the user operation on the touch panel.

[0159] Therefore, in the case of receiving an operation to select a UE that supports the side link function, "relay time parameters" such as "remaining power" or "time period" in which the relay function can be used are presented to the user, thereby assisting the user in performing the operation of selecting a connection destination.

[0160] As described above, according to the first to third exemplary embodiments, a terminal to be used as a relay UE can be selected based on the relay time parameter, so that the time when each terminal can be used as a relay device can be reflected in the selection result. Therefore, stable side link communication can be ensured.

[0161] For example, the following inconvenience can be avoided: the side link communication is unexpectedly established with the terminal (UE) with a small amount of battery remaining and the long-term side link communication cannot be ensured. The following problem can also be avoided: as a result of selecting a terminal (UE) with a small amount of battery remaining, the connection with the network is disconnected during communication, so that it takes a long time to establish communication with another relay UE.

[0162] <Other embodiments>

[0163] Although the above exemplary embodiments assume the case of device discovery in the sidelink operation of 5G New Radio (NR), the present invention is not limited to this case. Basically, the present invention can be applied to all subsequent standards for the specification of the sidelink operation of 5G NR assuming direct wireless communication between UEs.

[0164] The present disclosure may also be implemented by the following processing. That is, a program for implementing one or more functions according to the above exemplary embodiments is supplied to a system or device via a network or storage medium. One or more processors in a computer of a system or device may read out and execute the program. The present disclosure may also be implemented by a circuit (e.g., an application specific integrated circuit (ASIC)) for implementing one or more functions.

[0165] The present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention. Therefore, the claims are attached to disclose the scope of the present invention.

[0166] The present invention is not limited to the above-described embodiments, and various modifications and changes may be made without departing from the spirit and scope of the present invention. Therefore, the following claims are attached to disclose the scope of the present invention.

[0167] This application is based upon and claims the benefit of priority of Japanese patent application No. 2022-142811 filed on September 8, 2022, the disclosure of which is incorporated herein by reference.

[0168] Reference Symbols List

[0169] 10Terminal (second communication device)

[0170] 10A terminal (first communication device)

[0171] 10B terminal (first communication device)

[0172] 10C terminal (first communication device)

[0173] 20 Base Stations

[0174] 100 Communication equipment

[0175] 101 control unit (optional unit)

[0176] 102 Storage Unit

[0177] 103 Message generation unit

[0178] 104 Message analysis and processing unit

[0179] 105 communication unit (sending unit)

Claims

1. A sidelink communication device, comprising: a receiving unit configured to receive a detection signal for detecting each of a plurality of communication devices as a side-link device, the detection signal being transmitted from the plurality of communication devices; as well as a selection unit configured to select a target device to be connected as a relay device from among the plurality of communication devices detected at the time of reception of the detection signal, Before establishing a connection with the target device, the receiving unit receives a relay time parameter value sent from each of the plurality of communication devices. wherein the relay time parameter is associated with a time during which each of the plurality of communication devices can function as a relay device, and The selection unit selects the target device based on the relay time parameter value corresponding to each of the plurality of communication devices.

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

3. The sidelink communication device according to claim 1 or 2, further comprising a sending unit, wherein the sending unit is configured to send a discovery request signal to the outside, The detection signal is a discovery response signal that is a response to the discovery request signal sent by the sending unit.

4. The sidelink communication device according to claim 3, wherein the discovery request signal sent by the sending unit is a Soliciation message for 5G ProSe direct discovery.

5. The side link communication device according to any one of claims 1 to 4, wherein the relay time parameter value to be transmitted is included in a parameter notification signal different from the detection signal.

6. The side link communication device according to any one of claims 1 to 5, wherein the relay time parameter indicates whether each of the plurality of communication devices is receiving power fed from a power source other than a battery of its own communication device, and wherein the selection unit selects, from among the plurality of communication devices, a communication device that is receiving power fed from a power source other than a battery of its own communication device as the target device.

7. The side link communication device according to any one of claims 1 to 5, wherein the relay time parameter indicates a remaining amount of a battery serving as a power source for the target device, and The selection unit selects a communication device whose remaining battery power is the largest or is greater than or equal to a threshold value from among the plurality of communication devices as the target device.

8. The side link communication device according to any one of claims 1 to 5, wherein the relay time parameter indicates the remaining amount of a battery as a power source of the target device and the hourly power usage of the target device, and The selection unit selects the target device based on the remaining amount of the battery and the power usage.

9. The side link communication device according to any one of claims 1 to 5, wherein the relay time parameter indicates whether the target device is receiving power fed from a commercial power source, and wherein the selection unit selects, from among the plurality of communication devices, a communication device that is receiving power fed from a power source other than the commercial power source as the target device.

10. A sidelink communication device, comprising: a sending unit configured to send a detection signal for causing another side link device to detect the side link communication device as a side link device, Wherein before establishing a connection with the other side-link device, the sending unit sends to the other side-link device a relay time parameter value associated with a time during which the side-link communication device can function as a relay device.

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

12. The sidelink communication device according to claim 10 or 11, further comprising a receiving unit configured to receive a discovery request signal sent from another sidelink device, The discovery request signal received by the receiving unit is a Soliciation message for 5G ProSe direct discovery, the detection signal is a response to the Soliciation message, and the response includes the relay time parameter value.

13. A sidelink communication device, comprising: a sending unit configured to send a detection signal for causing another side link device to detect the side link communication device as a side link device, Wherein before establishing the connection with the other side-link device, the sending unit sends information indicating the remaining amount of the battery of the side-link communication device to the other side-link device.

14. A control method for a communication device, comprising: performing reception control of receiving a detection signal for detecting the communication device as a side-link device, the detection signal being transmitted from each of a plurality of communication devices; obtaining a value of a relay time parameter transmitted from each of the plurality of communication devices before establishing a connection with a target device to be connected as a relay device; and selecting the target device from among the plurality of communication devices detected upon reception of the detection signal, wherein the relay time parameter is associated with a time during which each of the plurality of communication devices can function as a relay device, and Wherein in the selecting, the target device is selected based on a value of the relay time parameter corresponding to each of the plurality of communication devices. 15 . The control method according to claim 14 , wherein in the obtaining, the value of the relay time parameter is obtained from the detection signal.

16. A control method for a communication device, comprising: performing transmission control of transmitting a detection signal for causing the other side-link device to detect the communication device as a side-link device, Wherein in the transmission control, before establishing a connection with the other side link device, a relay time parameter value associated with a time during which the communication device can function as a relay device is transmitted to the other side link device.

17. A control method for a communication device, comprising: performing transmission control of transmitting a detection signal for causing the other side-link device to detect the communication device as a side-link device, Wherein in the transmission control, before establishing a connection with the other-side link device, the communication device transmits information indicating a remaining amount of a battery of the communication device to the other-side link device. 18 . A program for causing a computer to execute the control method for a communication device according to claim 14 .

19. A sidelink communication system, comprising: one or more first communication devices; as well as a second communication device, wherein each of the one or more first communication devices comprises a sending unit configured to send a detection signal for detecting the one or more first communication devices as a side link device, The second communication device comprises: a receiving unit, configured to receive the detection signal sent from the one or more first communication devices; as well as a selection unit configured to, in a case where a plurality of first communication devices are detected as a result of the reception unit receiving the detection signal, select a target device to be connected as a relay device from among the plurality of first communication devices detected by the detection signal, Before establishing a connection with the target device, the receiving unit receives a value of a relay time parameter sent from the one or more first communication devices. wherein the relay time parameter is associated with a time during which each of the one or more first communication devices can function as a relay device, and The selection unit selects the target device based on a value of the relay time parameter corresponding to each of the plurality of first communication devices.

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