Communication device, base station, and control method

Abstract

To provide a mechanism that makes available, on a base station side, information related to stoppage of a relay function of relay UE.SOLUTION: Relay user equipment (UE) 102 comprises: a side link relay processing unit that relays communication between a base station and remote UE; a SRAP PUD generation processing unit that generates a SRAP control PDU that is a PDU of a side link adaptation protocol (SRAP); and a radio communication unit that transmits the SRAP control PDU generated by the SRAP PDU generation processing unit. When a predetermined condition is satisfied in a situation where a relay is performed by side link relay means, the SRAP PDU generation processing unit stores stoppage related information related to stoppage of the relay performed by the side link relay processing unit in the SRAP control PDU.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a communication device, a base station, a control method, and a program. [Background technology]

[0002] In recent years, the 3GPP (3rd Generation Partnership Project) (registered trademark) has been formulating specifications for LTE (Long Term Evolution) and next-generation (NR: New Radio) standards. Among these, a standard specification called Sidelink communication has been formulated. This specification realizes direct wireless communication between devices using an interface called PC5, without going through a mobile communication network (core network).

[0003] Furthermore, 3GPP is currently formulating specifications to expand the communication range of Sidelink by using a Sidelink relay function that relays Sidelink communication via a relay device (relay UE). A means is specified for a communication terminal (remote UE) that has the function of connecting to a base station through the Sidelink relay function to switch from an indirect path. In other words, a means is specified for switching from communication connecting to a base station via a relay UE (indirect path) to direct communication with a base station (direct path) without disconnecting the service, and a means is specified for switching from a direct path to an indirect path without disconnecting the service.

[0004] Patent Document 1 proposes a means for a remote UE to switch from an indirect path to a direct path without disconnecting the service. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2022 / 0377822 Summary of the Invention [Problem to be solved by the invention]

[0006] The decision to switch paths is made mainly based on the signal strength between the remote UE and the relay UE, and between the remote UE and the base station, and does not take into account the internal circumstances of the relay UE. Examples of internal circumstances of the relay UE include the remaining battery level of the relay UE and a fail-soft function due to the loss of some processes. Currently, there is no mechanism to inform the base station that the relay function cannot continue due to internal circumstances of the relay UE. In this case, if the relay function of the relay UE suddenly stops, a sequence of reconnection to the base station will be run, which may reduce service continuity.

[0007] The present invention has been made in consideration of at least one of the above problems. As one aspect of the present invention, an object of the present invention is to provide a mechanism for enabling a base station to use information regarding the suspension of a relay function of a relay UE. [Means for solving the problem]

[0008] According to one aspect of the present invention, a base station includes a communication means for communicating with a remote UE via a relay UE (User Equipment); A receiving means for receiving a SRAP control PDU, which is a PDU of a Sidelink Adaptation Protocol (SRAP), from the relay UE; and a control means for executing communication control related to the communication means based on the stop-related information when the receiving means receives an SRAP control PDU storing stop-related information regarding the stop of relaying via the relay UE. Effect of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a mechanism that enables the base station to use information regarding the suspension of the relay function of a relay UE. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a communication device according to an embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an example of a functional configuration of a base station according to the present embodiment. FIG. [Diagram 3] 2 is a block diagram showing an example of a functional configuration of a relay UE in the present embodiment. FIG. [Figure 4] FIG. 11 is a diagram illustrating an example of a configuration of a relay function continuance disable notification according to the first embodiment. [Diagram 5] FIG. 11 is a diagram illustrating an example of a configuration of a relay function continuance disable notification according to the first embodiment. [Figure 6] 4 is a flowchart between communication devices according to the first embodiment. [Figure 7] FIG. 11 is a diagram illustrating an example of the configuration of a relay function continuance disable notification in the second embodiment. [Figure 8] 10 is a flowchart between communication devices according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are used to designate the same or similar components, and duplicated descriptions may be omitted. <Embodiment 1> 1 is a diagram showing an example of the configuration of a system according to this embodiment. In FIG. 1, UE A (101) and UE B (102) are within a communication area 104 of a base station 103.

[0012] In this embodiment, the UE (User Equipment) is assumed to be a terminal compatible with Sidelink relay communication. Specifically, the UE is assumed to be a smartphone or the like, but is not limited thereto. For example, the UE may be a communication terminal such as a tablet terminal or a PC, a wearable terminal such as a smart watch or a head-mounted display, or a car navigation device installed in an automobile.

[0013] In Fig. 1, UE A (101) operates as a remote UE and communicates with a base station 103 using sidelink relay communication. UE B (102) operates as a relay UE and relays communication between UE A (101) and the base station 103 using a sidelink relay function. In other words, UE A (101) is transmitting and receiving data to and from the base station on an indirect path with UE B (102).

[0014] FIG. 2 is a block diagram showing an example of the functional configuration of the base station 103 in this embodiment.

[0015] Note that some or all of the functional blocks described in FIG. 2 (as well as FIG. 3 described later) may be replaced with other functional blocks performing similar functions, or some functional blocks may be omitted. New functional blocks may also be added. Furthermore, one functional block described below may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block.

[0016] In the example shown in FIG. 2, the base station 103 includes a control unit 201, a storage unit 202, a UE management unit 203, a path switching processing unit 204, a SRAP PDU generation processing unit 205, a SRAP PDU analysis processing unit 206, and a wireless communication unit 207.

[0017] The control unit 201 controls the operation of the base station 103. The control unit 201 is configured with one or more processors such as a CPU or an MPU, and controls the entire communication device by executing a control program read into a RAM, which is a storage unit 202. Note that each process performed by the control unit 201, which will be described in the flowcharts below, can also be realized using a hardware circuit such as an ASIC or an FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit, and FPGA is an abbreviation for Field Programmable Gate Array. Also, the hardware circuit and a processor such as a CPU or an MPU can cooperate to realize the process described in the flowcharts below.

[0018] The storage unit 202 stores information used by the control unit 201 for control and information related to communication. The storage unit 202 may include a main storage unit and an auxiliary storage unit. The main storage unit may be, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory). The main storage unit may store or temporarily store programs and data such as an OS (Operating System) that is basic software executed by the control unit 201 and application software. The auxiliary storage unit may be, for example, a HDD (Hard Disk Drive) or an SSD (Solid State Drive), and may store data related to application software. For example, a control program stored in a non-volatile storage area is expanded in a RAM (Random Access Memory) and executed by a processor constituting the control unit 201. In this manner, the control unit 201 and the storage unit 202 may function as a so-called computer.

[0019] The storage unit 202 may include a recording medium for storing a predetermined program. The program stored in this recording medium may be installed via a drive device or the like, and the installed predetermined program may be executable by the control unit 201. The recording medium may be of various types. For example, the recording medium may be a recording medium that records information optically, electrically, or magnetically, such as a CD (Compact Disc)-ROM, a flexible disk, or a magneto-optical disk. The recording medium may also be a semiconductor memory that records information electrically, such as a ROM or a flash memory. Note that the recording medium does not include a carrier wave.

[0020] The UE management unit 203 manages UE information within the base station area, including the IDs of the UEs under its control and measurement results (such as the signal strength of a Uu link, which will be described later) reported from the UEs under its control.

[0021] Based on the UE information managed by the UE management unit 203, the path switching processing unit 204 determines whether the UE under its management should be connected via an indirect path or a direct path.

[0022] The SRAP PDU generation processor 205 generates a message used to instruct a path switch. In this embodiment, the SRAP PDU generation processor 205 generates a PDU (SRAP PDU) used in a Sidelink Adaptation Protocol (SRAP). SRAP is a protocol used in a New Radio (NR) Sidelink relay function.

[0023] The SRAP PDU analysis processor 206 analyzes the SRAP PDU received from a subordinate relay UE (hereinafter also referred to as a "subordinate relay UE").

[0024] The functions corresponding to the UE management unit 203, the path switching processing unit 204, and / or the SRAP PDU generation processing unit 205 may be realized as software modules implemented by the control unit 201.

[0025] The wireless communication unit 207 transmits and receives information to and from the subordinate UEs via wireless communication. For example, the wireless communication unit 207 performs a transmission process of a message generated by the SRAP PDU generation processing unit 205, a reception process of a SRAP PDU from the subordinate UEs, and a reception process of other necessary wireless signals.

[0026] FIG. 3 is a block diagram showing an example of a functional configuration of the relay UE (102) in this embodiment.

[0027] In the example shown in FIG. 3, the relay UE (102) includes a control unit 301, a storage unit 302, a signal strength measurement unit 303, a sidelink relay processing unit 304, a SRAP PDU generation processing unit 305, a SRAP PDU analysis processing unit 306, and a wireless communication unit 307.

[0028] The control unit 301 controls the operation of the relay UE (102). The control unit 301 is configured with one or more processors such as a CPU or an MPU, and controls the entire communication device by executing a control program read into a RAM, which is a storage unit 302. Note that each process performed by the control unit 301, which will be described in the flowcharts below, can also be realized using a hardware circuit such as an ASIC or an FPGA. Also, the hardware circuit and a processor such as a CPU or an MPU can cooperate to realize the process described in the flowcharts below.

[0029] The memory unit 302 stores information used by the control unit 301 for control and information related to communication.

[0030] The signal strength measurement unit 303 measures the "signal strength between remote UEs (PC5 link)" and the "signal strength between base stations (Uu link)" as viewed from the relay UE (102).

[0031] The Sidelink Relay processing unit 304 establishes a Sidelink connection with the remote UE. This enables the Sidelink Relay processing unit 304 to relay communication between the remote UE and the base station 103 via the NR Sidelink relay function of the relay UE (i.e., an indirect path). In the following, the NR Sidelink relay function is also simply referred to as the Sidelink relay function.

[0032] The SRAP PDU generation processor 305 is a SRAP PDU generation unit, similar to the SRAP PDU generation processor 205 of the base station 103 described above. In this embodiment, when the relay UE determines that its NR Sidelink relay function cannot be continued, the SRAP PDU generation processor 305 generates a PDU (an example of stop-related information) for notifying the base station 103 that the relay function cannot be continued. Details of the PDU for notifying the base station 103 that the relay function cannot be continued will be described later with reference to FIG. 4.

[0033] The SRAP PDU analysis processing unit 306 analyzes the SRAP PDU received from the remote UE and the base station 103.

[0034] The wireless communication unit 307 transmits and receives information via wireless communication with the remote UE and the base station 103. The wireless communication unit 307 performs a transmission process of the SRAP PDU generated by the SRAP PDU generation processing unit 305, a reception process of the SRAP PDU from the remote UE and the base station 103, and other necessary wireless communication reception processes.

[0035] FIG. 4 shows an example of the configuration of a PDU indicating that the relay function cannot be continued.

[0036] When a bit of the D / C field 401 of a PDU in an SRAP has a value of 0, this indicates that the PDU is data (i.e., a SRAP DATA PDU). When a bit of the D / C field 401 of a PDU in an SRAP has a value of 1, this indicates that the PDU is a control message (i.e., a SRAP Control PDU). In a PDU indicating that the relay function cannot be continued, a value of 1 is set in the D / C field 401. In this embodiment, when the D / C field 401 has a value indicating a SRAP Control PDU, a configuration is adopted in which 4 bits are added to the PDU type field 402 and 3 bits are added to the Reserved field 403. When the D / C field 401 has a value indicating a SRAP Control PDU, the fields following the Reserved field 403 are configured as optional fields.

[0037] The PDU type field 402 indicates whether the relay function cannot be continued when the PDU is a SRAP Control PDU. In this embodiment, when the PDU type field 402 has a value of 0000, this indicates "relay function cannot be continued." Note that the value of 0000 is only an example, and any other value may be used as long as it does not overlap with values ​​of other PDU types.

[0038] In this embodiment, the SRAP Control PDU including a value corresponding to "relay function cannot be continued" is illustrated as an example of the stop-related information, but is not limited thereto. Any value indicating that the relay cannot be continued / operation as a relay will not be continued may be used as the stop-related information. In addition, for example, a value corresponding to a relay RLF (Radio Link Failure) indicating that a problem has occurred regarding a radio link for relaying may be used as the stop-related information. In other words, the stop-related information of this embodiment can be modified in any way as long as it is information that causes an action such as being able to inform the base station that communication may be interrupted. That is, the above specific example is merely one example of the stop-related information, and it is noted for the sake of clarity that the actual name and the specific format for notifying the information are not limited to the above specific example.

[0039] The Reserved field 403 is an unused field.

[0040] Option field 1 (indicated by reference numeral 404) is a field for storing additional information, and uses the fields from the second octet onwards of the PDU. In this embodiment, the remaining time that the relay UE can continue the relay function is stored as the additional information. Note that this is only an example, and other appropriate configurations may be used. For example, in addition to the remaining relay function continuation time described above, a field indicating the reason why the relay UE cannot continue the relay function may be added.

[0041] Fig. 5 is a diagram showing an example of the configuration of a PDU indicating that the relay function cannot be continued, which adds the reason why the relay UE cannot continue the relay function. In Fig. 5, an option field 2 (indicated by reference numeral 504) is added to the format shown in Fig. 4. A value indicating the reason why the relay function cannot be continued is stored in the option field 2. The reason why the relay function cannot be continued will be described later.

[0042] Next, the operation of this embodiment will be described with reference to FIG.

[0043] 6 is an example of a flowchart in this embodiment, in which a relay UE notifies the base station 103 that the relay function cannot be continued, and the base station 103 receives the notification and determines whether to switch from an indirect path to a direct path. The process shown in the flowchart can be realized in the base station 103 by the control unit 201 executing a control program stored in the storage unit 202 to perform calculations and processing of information and control of each piece of hardware. Also, in the UE B (102), the process can be realized by the control unit 301 executing a control program stored in the storage unit 302 to perform calculations and processing of information and control of each piece of hardware.

[0044] In this embodiment, UE B (102), which is a relay UE, performs relaying using the Sidelink Relay processing unit 304. That is, UE B (102) relays communication of user data (such as streaming data) between UE A (101), which is a remote UE, and the base station 103 via an indirect path (S601).

[0045] The control unit 301 of the UE B (102) determines whether or not the relay function of the own terminal cannot be continued (S602). Then, when the control unit 301 of the UE B (102) determines that the relay function of the own terminal cannot be continued, it notifies the sidelink relay processing unit 304 that the relay function cannot be continued. Here, the control unit 301 may determine that the relay function of the own terminal cannot be continued when a predetermined condition is satisfied. In this case, the predetermined condition may be a condition related to the state (device state or communication state) of the relay UE. For example, when any one of the following conditions (1) to (7) is satisfied, it may determine that the relay function of the own terminal cannot be continued. Condition (1) The remaining battery power of the device falls below a threshold. Condition (2): A hardware failure is detected. Condition (3): Some processes (for example, processes operating to implement the signal strength measurement unit 303) are lost. Condition (4) When the user or user application controls the NR Sidelink Relay function to be turned off. Condition (5): The user turns off the power or resets the power. Condition (6): The signal strength of the PC5 link falls below the threshold. Condition (7): When the signal strength of the Uu link falls below a threshold.

[0046] Alternatively, the control unit 301 may determine that the relay function of the own terminal cannot be continued when any combination of two or more of the above conditions (1) to (7) is satisfied. Furthermore, among the above conditions (1) to (7), the condition (1) and the like may be determined in a manner including prediction. For example, regarding the condition (1), it may be determined that the condition (1) is not satisfied when the battery remaining amount of the own terminal falls below a threshold but is currently being charged or is scheduled to be charged in a short time. Furthermore, regarding the condition (1), the battery remaining amount of the own terminal may relate only to the battery remaining amount available for communication when the battery is also used for purposes other than communication (e.g., for transportation).

[0047] In another embodiment, in addition to the above conditions (1) to (7), the following condition (8) may be determined. Condition (8): The temperature of the device (your device) exceeds the upper limit temperature.

[0048] Upon receiving the notification from the control unit 301, the Sidelink Relay processing unit 304 creates a SRAP control PDU indicating that the relay function cannot be continued through the SRAP PDU generation processing unit 305 (S603). Hereinafter, the SRAP control PDU indicating that the relay function cannot be continued may be referred to as a relay function continuation disable notification. Herein, the SRAP PDU generation processing unit 305 stores the time until the relay function is stopped, calculated by the control unit 301, in the option field 1 (404). In this embodiment, the option field is 2 bytes, and 0 to 65535 are stored. The unit is seconds, and 0 is stored when the calculation is impossible (N / A) (S604). In addition, as an option, an option field 2 504 may be added and values ​​corresponding to the above-mentioned conditions (1) to (8) may be stored. In this embodiment, the following values ​​can be set. In this case, the base station 103 side can grasp the reason for stopping the relay function in the relay UE. 0 Low battery (set when condition (1) is met) 1. Failure (hardware cause) (set when condition (2) is met) 2. Fault (software cause) (set when condition (3) is met) 3 Sidelink relay function off (set when condition (4) is met) 4 Power off or power reset (set if condition (5) is met) 5 PC5 link signal strength degraded (set if condition (6) is met) 6 Uu link signal strength degraded (set if condition (7) is met) 7 Terminal temperature rise (set if condition (8) is met) The Sidelink Relay processing unit 304 sends a notification that the relay function cannot be continued to the base station 103 through the wireless communication unit 307 (S605). When the time until the relay function is stopped calculated in S604 has elapsed, the control unit 301 stops the function of the Sidelink Relay processing unit 304. When the calculation is impossible, the function of the Sidelink Relay processing unit 304 is stopped when the time set as an initial value (for example, 60 seconds) has elapsed (S606). Note that in a modified example, the function of the Sidelink Relay processing unit 304 may be stopped before the predetermined time has elapsed.

[0049] When the wireless communication unit 207 in the base station 103 receives the SRAP PDU, the SRAP PDU analysis unit 206 analyzes the contents of the received SRAP PDU (S607). The analysis determines whether the D / C field 401 has a value indicating "SRAP Control PDU" and the PDU type field 402 has a value indicating "relay function cannot be continued" (S608). If the D / C field 401 has a value indicating "SRAP Control PDU" and the PDU type field 402 has a value indicating "relay function cannot be continued" (i.e., the above-mentioned "relay function cannot be continued notification"), the process proceeds to S609. In S609, the SRAP PDU analysis unit 206 determines that the SRAP PDU is a relay function cannot be continued notification. Then, the SRAP PDU analysis unit 206 interprets the value stored in the option field 1 (404) as the time until the relay function is stopped, and acquires the value. Based on the analysis result by the SRAP PDU analysis processing unit 206, the control unit 201 determines that it is difficult for UE B (102) to continue the relay function. In this case, the control unit 201 requests the path switching processing unit 204 to switch the path of UE A (101) within the time until the relay function is stopped (immediately if N / A). The path switching processing unit 204 switches UE A (101) from the indirect path to the direct path. If the received SRAP PDU is not a notification that the relay function cannot be continued, the process corresponding to the other SRAP PDU is performed (S610).

[0050] Through the above flow, when UE B (102) is unable to continue relaying, UE B (102) and the base station 103 can switch from an indirect path to a direct path in UE A (101) without interrupting the service.

[0051] In this way, according to the present embodiment, it is possible to provide a mechanism that allows the base station 103 to acquire information (notification that relay function cannot be continued) regarding the stop of the relay function of the relay UE (102). As a result, based on the notification that relay function cannot be continued, the base station 103 can switch from an indirect path to a direct path in the UE A (101) while maintaining the service in the UE A (101).

[0052] According to the present embodiment, the relay UE (102) can include information about the time until the relay function is stopped in the relay function continuation disable notification. In this case, the base station 103 can realize the switching from the indirect path to the direct path in the UE A (101) at an appropriate timing based on the time information. Second Embodiment The configuration of the communication device (FIG. 1) and the functional configuration of the communication device (FIGS. 2 and 3) in the second embodiment are similar to those in the first embodiment.

[0053] In the first embodiment, an example is described in which the base station 103 can perform path switching for the remote UE without disconnecting the service when the NR Sidelink Relay function in the relay UE cannot be continued. In the second embodiment, an example is described in which the NR Sidelink Relay function of the relay UE is interrupted. For example, when a program that occupies the CPU utilization rate or the network bandwidth is executed in the relay UE, the NR Sidelink Relay function is not available until the program is completed. Such a program is, for example, an application for measuring throughput, but is not limited thereto.

[0054] In this embodiment, when the relay UE suspends its own NR Sidelink relay function as the second predetermined condition, the NR Sidelink relay function is suspended and stopped. Specifically, when the relay UE suspends its own NR Sidelink relay function, the SRAP PDU generation processor 305 generates a PDU for notifying the base station of the suspension of the relay function. An example of the configuration of a PDU (an example of suspension-related information) indicating suspension of the relay function is shown in FIG. 7.

[0055] The D / C field 401 has a value of 1, i.e., a value indicating an SRAP Control PDU, followed by a 4-bit PDU type field 402 and a 3-bit Reserved field 403. The configuration followed by an option field is the same as in FIGS.

[0056] In this embodiment, if the PDU type field 402 has a value of 0001, it indicates "relay function interruption". This SRAP Control PDU is hereinafter referred to as a "relay function interruption notification". The relay function interruption notification sets option field 1 704 to 4 bytes and option field 2 705 to 2 bytes.

[0057] Option field 1 704 stores the planned time for relay interruption. As shown in 706 in FIG. 7, the values ​​that can be set in the 4 bytes are as follows: the 0th to 6th MSB bits represent the year, with 2023 being 0 and up to 127 (2150) being able to be stored. The 7th to 10th bits represent the month, and may store values ​​1 to 12. The 11th to 15th bits represent the day, and may store values ​​1 to 31. The 16th to 20th bits represent the hour, and may store values ​​0-23. The 21st to 26th bits represent the minute, and may store values ​​0 to 59. Finally, the 27th to 31st bits represent the second, and may specify values ​​0 to 29 in 2-second increments.

[0058] The recovery time of the relay function after interruption is stored in the option field 2 705. In this embodiment, the recovery time can be set to 1 to 65535 seconds.

[0059] Next, the operation of this embodiment will be described with reference to FIG.

[0060] FIG. 8 is an example of a flowchart showing a process of notifying a relay function interruption notification by a relay UE and a process of determining switching from an indirect path to a direct path by a base station that has received the notification, in this embodiment.

[0061] In the second embodiment, UE B (102), which is a relay UE, performs relay using the Sidelink Relay processing unit 304. That is, UE B (102) relays communication of user data (such as streaming data) between UE A (101), which is a remote UE, and the base station 103 via an indirect path (S801).

[0062] The control unit 301 of the UE B (102) determines whether or not it is necessary to suspend the relay function of the own terminal (S802). If it is determined that it is necessary to suspend the relay function of the own terminal, the control unit 301 proceeds to the process of S803 and subsequent steps to notify the sidelink relay processing unit 304 of the suspension of the relay function.

[0063] Upon receiving the notification from the control unit 301, the Sidelink Relay processing unit 304 creates a PDU indicating the interruption of the relay function (hereinafter, referred to as a relay function interruption notification) through the SRAP PDU generation processing unit 305 (S803). Here, the SRAP PDU generation processing unit 305 stores the time until the relay function is interrupted, calculated by the control unit 301, in the option field 1 704. Also, the SRAP PDU generation processing unit 305 stores the recovery time of the relay function, calculated by the control unit 301, in the option field 2 705 (S804).

[0064] The Sidelink Relay processing unit 304 sends a relay function interruption notification to the base station 103 through the wireless communication unit 307 (S805).

[0065] When the relay interruption time calculated in S804 is reached, the control unit 301 stops the function of the sidelink relay processing unit 304. When the recovery time calculated in S804 has elapsed from the interruption time, the control unit 301 resumes the sidelink relay processing unit 304 (S806).

[0066] When the wireless communication unit 207 in the base station 103 receives the SRAP PDU, the SRAP PDU analysis processing unit 206 analyzes the contents of the received SRAP PDU (S807).

[0067] Next, the SRAP PDU analysis processor 206 judges whether the D / C field 401 has a value indicating "SRAP Control PDU" and the PDU type field 402 indicates "relay function cannot be continued" (S808). If the D / C field 401 has a value indicating "SRAP Control PDU" and the PDU type field 402 indicates "relay function cannot be continued" (i.e., the above-mentioned "relay function cannot be continued notification"), the following occurs. The SRAP PDU analysis processor 206 judges that the SRAP PDU is a relay function cannot be continued notification (FIGS. 4 and 5), and proceeds to S609 according to STEP 1 in FIG. 6 in the first embodiment (S809).

[0068] When the D / C field 401 has a value indicating "SRAP Control PDU" and the PDU type field 402 indicates "relay function interruption" (i.e., the above-mentioned "relay function interruption notification"), the procedure is as follows: The SRAP PDU analysis processing unit 206 determines that the SRAP PDU is a relay function interruption notification, interprets the value stored in option field 1 704 as the time until the relay function is interrupted, and obtains the value. Also, it interprets the value stored in option field 2 705 as the time from interruption of the relay function until recovery, and obtains the value.

[0069] Based on the analysis result by the SRAP PDU analysis processing unit 206, the control unit 201 recognizes that UE B (102) will suspend the relay function, and requests the path switching processing unit 204 to switch the path of UE A (101) within the time until the relay function is suspended. The path switching processing unit 204 switches UE A (101) from the indirect path to the direct path (S811, S812). If the received SRAP PDU is not a relay function suspension notification, the processing corresponding to other SRAP PDUs is performed (S813).

[0070] After the relay function recovery time of UE B (102) acquired in S810 has elapsed, the control unit 201 acquires the signal strength with UE A (101) switched in S812 and the signal strength with UE B (102) from the UE management unit 203 and compares them. If the signal strength with UE B (102) is greater than the signal strength with UE A, it determines to switch to the original indirect path (i.e., the system configuration shown in FIG. 1) and causes the path switching processing unit 204 to execute path switching (S814, S815, S816).

[0071] With the above flow, when UE B (102) discontinues relaying, UE B (102) and base station 103 can switch UE A (101) from an indirect path to a direct path without interrupting the service.

[0072] In this embodiment, the base station 103 takes into consideration the possibility of receiving both the relay function non-continuance notification and the relay function interruption notification. However, it is also possible to configure the base station 103 so that only the relay function interruption notification is used out of the relay function non-continuance notification and the relay function interruption notification. In this case, steps S808 and S809 may be omitted from the flow shown in FIG. 8.

[0073] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments.

[0074] For example, in the above-described embodiment, switching from an indirect path to a direct path is performed based on a notification that the relay function cannot be continued or a notification that the relay function is interrupted, but this is not limited to the above. For example, switching from an indirect path to another indirect path using another relay UE may be realized based on a notification that the relay function cannot be continued or a notification that the relay function is interrupted. For example, when the signal strength between UE A (101) and the base station 103 is lower than the signal strength between UE A (101) and another UE (UE other than UE B (102)), switching to an indirect path via the other UE may be realized.

[0075] In addition, in the above-described embodiment, instead of SRAP, a method may be used to notify the gNB that the relay function cannot be continued and that the relay function cannot be interrupted, using an RRC connection between the base station and the relay UE.

[0076] In addition, the following supplementary notes are disclosed regarding the above embodiment.

[0077] [Appendix 1] A sidelink relay means for relaying communication between a base station and a remote UE (User Equipment); A generating means for generating an SRAP control PDU, which is a PDU (Protocol Data Unit) of a Sidelink Adaptation Protocol (SRAP); A transmitting means for transmitting the SRAP control PDU generated by the generating means, The generation means stores stop-related information regarding stop of relaying by the Sidelink relay means in the SRAP control PDU when a predetermined condition is satisfied in a situation in which relaying by the Sidelink relay means is being performed.

[0078] [Appendix 2] The communication device according to claim 1, wherein the predetermined condition relates to a state of the communication device itself.

[0079] [Appendix 3] The device further includes a first detection means for detecting a remaining capacity of a battery that supplies power to the device itself; 3. The communication device according to claim 1, wherein the predetermined condition is satisfied when the remaining charge of the battery detected by the first detection means falls below a threshold.

[0080] [Appendix 4] Further comprising a second detection means for detecting a predetermined abnormality in the device itself, 4. The communication device according to claim 1, wherein the predetermined condition is satisfied when the second detection means detects the predetermined abnormality.

[0081] [Appendix 5] The communication device according to claim 4, wherein the specified abnormality includes at least one of a hardware failure of the device itself and a loss of a process in software implemented in the device itself.

[0082] [Appendix 6] The communication device according to any one of appendices 1 to 5, wherein the predetermined condition is satisfied when a function related to the SideLink relay means is turned off.

[0083] [Appendix 7] 7. The communication device according to claim 1, wherein the predetermined condition is satisfied when the power of the communication device is turned off or reset.

[0084] [Appendix 8] a first measuring means for measuring a signal strength of a signal received from the remote UE; 8. The communication device of claim 1, wherein the predetermined condition is met when the signal strength is below a threshold.

[0085] [Appendix 9] A second measuring means for measuring a signal strength of a signal received from the base station, 9. The communication device of claim 1, wherein the predetermined condition is met when the signal strength is below a threshold.

[0086] [Appendix 10] 10. The communication device according to claim 1, wherein the generating means stores a value meaning "SRAP control PDU" in a D / C field of the SRAP control PDU.

[0087] [Appendix 11] 11. The communication device according to claim 1, wherein the generating means stores the stop-related information in a PDU type field of the SRAP control PDU.

[0088] [Appendix 12] The communication device according to any one of appendices 1 to 11, wherein the stop-related information includes at least one of information indicating a stop of a function related to the Sidelink relay means, information indicating a time until the stop, information indicating a cause of the stop, and information indicating a time until resumption after the stop.

[0089] [Appendix 13] A communication means for communicating with a remote UE via a relay UE (User Equipment); A receiving means for receiving a SRAP control PDU, which is a PDU of a Sidelink Adaptation Protocol (SRAP), from the relay UE; a control means for executing communication control related to the communication means based on stoppage-related information when the receiving means receives an SRAP control PDU storing stoppage-related information related to stoppage of relaying via the relay UE.

[0090] [Appendix 14] The base station according to claim 13, wherein the control means executes the communication control based on the stop-related information stored in a PDU type field of the SRAP control PDU when a value meaning "SRAP control PDU" is stored in a D / C field of the SRAP control PDU.

[0091] [Appendix 15] 14. The base station as described in claim 13, wherein the communication control includes instructing the remote UE to switch from an indirect path via the relay UE to another path based on the outage-related information.

[0092] [Appendix 16] The base station according to claim 15, wherein the suspension-related information includes at least one of information indicating suspension of a function related to the Sidelink relay means, information indicating a time until the suspension, information indicating a cause of the suspension, and information indicating a time until resumption after the suspension.

[0093] [Appendix 17] 17. The base station according to claim 16, wherein the communication control includes instructing the switching within a time until the stop based on information indicating a time until the stop.

[0094] [Appendix 18] 18. The base station according to claim 16, wherein the communication control includes instructing switching from the another path after switching to the indirect path based on information indicating a time until resumption after the suspension. [Explanation of symbols]

[0095] 101 UE A 102 UE B (an example of a communication device) 103 Base station 104 Base Station Communication Area 201 Control unit (an example of a control means) 202 Storage section 203 UE Management Department 204 Path switching processing unit (an example of a control means) 205 PDU generation processing unit 206 PDU analysis processing unit 207 Wireless communication unit (an example of a communication means and a receiving means) 301 Control unit (an example of the first detection means and the second detection means) 302 Storage section 303 Signal strength measurement unit (an example of the first measurement means and the second measurement means) 304 Sidelink Relay processing unit (an example of a Sidelink relay means) 305 PDU generation processing unit (an example of a generation means) 306 PDU Analysis Processing Unit 307 Wireless communication unit (an example of a transmission means)

Claims

1. Sidelink relay means for relaying communication between a base station and a remote UE (User Equipment), A generation means for generating an SRAP control PDU, which is a PDU (Protocol Data Unit) of the Sidelink Relay Adaptation Protocol (SRAP), The system comprises a transmission means for transmitting the SRAP control PDU generated by the generation means, The generation means is a communication device that stores stop-related information regarding the cessation of relay by the Sidelink relay means in the SRAP control PDU when predetermined conditions are met while relaying by the Sidelink relay means is in progress.

2. The aforementioned predetermined conditions relate to the state of the device itself, as described in claim 1.

3. The device further includes a first detection means for detecting the remaining charge of the battery that supplies power to the device, The communication device according to claim 1, wherein the predetermined condition is met when the remaining battery level detected by the first detection means falls below a threshold.

4. The device further includes a second detection means for detecting a predetermined abnormality in the device itself. The communication device according to claim 1, wherein the predetermined condition is satisfied when the predetermined abnormality is detected by the second detection means.

5. The communication device according to claim 4, wherein the predetermined abnormality includes at least one of the following: a hardware failure of the device and the loss of a process in the software implemented in the device.

6. The communication device according to claim 1, wherein the predetermined condition is satisfied when the function relating to the Sidelink relay means is turned off.

7. The communication device according to claim 1, wherein the predetermined conditions are met when the power of the device is turned off or reset.

8. The system further comprises a first measuring means for measuring the signal strength of the signal received from the remote UE, The communication device according to claim 1, wherein the predetermined condition is met when the signal strength falls below a threshold.

9. The system further comprises a second measuring means for measuring the signal strength of the signal received from the aforementioned base station, The communication device according to claim 1, wherein the predetermined condition is met when the signal strength falls below a threshold.

10. The communication device according to claim 1, wherein the generation means stores a value meaning "SRAP control PDU" in the D / C field of the SRAP control PDU.

11. The communication device according to claim 1, wherein the generation means stores the stop-related information in the PDU type field of the SRAP control PDU.

12. The communication device according to claim 1, wherein the stop-related information includes at least one of the following: information indicating the stop of a function related to the Sidelink relay means, information indicating the time until the stop, information indicating the cause of the stop, and information indicating the time until restart after the stop.

13. A communication means for communicating with a remote UE via a relay UE (User Equipment), A receiving means that receives an SRAP control PDU, which is a PDU of the Sidelink Relay Adaptation Protocol (SRAP), from the relay UE, A base station comprising: a control means that, when the receiving means receives an SRAP control PDU containing stop-related information regarding the cessation of relaying via the relay UE, executes communication control related to the communication means based on the stop-related information.

14. The base station according to claim 13, wherein the control means performs the communication control based on the stop-related information stored in the PDU type field of the SRAP control PDU when a value meaning "SRAP control PDU" is stored in the D / C field of the SRAP control PDU.

15. The base station according to claim 13, wherein the communication control includes instructing the remote UE to switch from the indirect path via the relay UE to another path based on the stop-related information.

16. The base station according to claim 15, wherein the stop-related information includes at least one of the following: information indicating the stop of the function of relaying to a remote UE via the relay UE; information indicating the time until the stop; information indicating the cause of the stop; and information indicating the time until restart after the stop.

17. The base station according to claim 16, wherein the communication control includes instructing the switching to occur within the time until the stop, based on information representing the time until the stop.

18. The base station according to claim 16, wherein the communication control includes instructing a switch from the other path after the switch to the indirect path based on information representing the time until restart after the stop.

19. A control method for controlling communication, A relay process that relays communication between the base station and the remote UE (User Equipment), The generation process for generating the SRAP control PDU, which is a PDU for Sidelink Relay Adaptation Protocol (SRAP), The process includes a transmission step for transmitting the SRAP control PDU generated by the generation step, The generation step is a control method that includes storing stop-related information regarding the cessation of relaying by the relay step in the SRAP control PDU when predetermined conditions are met while relaying by the relay step is in progress.

20. A communication process that communicates with a remote UE via a relay UE (User Equipment), A receiving step which receives an SRAP control PDU, which is a PDU of the Sidelink Relay Adaptation Protocol (SRAP), from the relay UE, A control method comprising: a control step which, when the receiving step receives an SRAP control PDU containing stop-related information regarding the stopping of relaying via the relay UE, executes communication control related to the communication step based on the stop-related information.

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