Communication device, base station, control method, and program

Abstract

To reduce the possibility that a terminal intended to be connected to a public radio communication network designed for congestion detection, is erroneously connected to a network not designed for congestion detection via relay UE.SOLUTION: A communication device is disclosed, which comprises: relay means that connects to remote user equipment (UE) through sidelink communication to relay communication with a base station carried out by the remote UE; and transmission means that transmits, to the remote UE, congestion detection capability information related to the ability of the base station to detect network congestion.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] BACKGROUND ART A technique is known for detecting congestion in an IP (Internet Protocol) data communication device by notifying congestion capability information of the communication device using an ECN (Explicit Congestion Notification) field (Patent Document 1).

[0003] In addition, in a public wireless communication network system, when a terminal connects to the network, a wireless connection is established by a control message on the C (Control) plane. After the wireless connection is established, communication of user data such as IP data becomes possible via the U (User) plane (Patent Document 2).

[0004] Furthermore, the 3GPP (3rd Generation Partnership Project) (registered trademark) is planning the following specifications: That is, specifications are being formulated to extend the communication range of a terminal (remote UE) by using a function (sidelink relay function) that relays sidelink communication via a relay device (relay UE: User Equipment).

[0005] Patent Document 3 proposes an improvement to the problem that occurs when a remote UE selects a relay UE. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2008-507204 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-227815 [Patent Document 3] Patent No. 6933225 Summary of the Invention [Problem to be solved by the invention]

[0007] Conventionally, wireless communication networks have not been able to notify terminals that they support ECN. As a result, a terminal (remote UE) that wants to connect to a public wireless communication network that supports congestion detection via a Sidelink relay UE may mistakenly connect to a relay UE that relays to a public wireless communication network that does not support congestion detection.

[0008] The present invention has been made in consideration of at least one of the above-mentioned problems, and an object of the present invention is to provide a mechanism that can reduce the possibility that a terminal that wants to connect to a public wireless communication network that supports congestion detection will mistakenly connect to a public wireless communication network that does not support congestion detection via a relay UE. [Means for solving the problem]

[0009] According to one aspect of the present invention, a communication device includes: a relay unit that connects to a remote UE (User Equipment) via sidelink communication and relays communication between the remote UE and a base station; The base station is characterized by comprising a transmitting means for transmitting congestion detection capability information regarding a congestion detection capability of a network of the base station to the remote UE. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to reduce the possibility that a terminal that wants to connect to a public wireless communication network that supports congestion detection will mistakenly connect to a public wireless communication network that does not support congestion detection via a relay UE. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention. [Figure 2]FIG. 2 is a diagram illustrating a functional configuration of a remote UE according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram illustrating a functional configuration of a relay UE according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the functional configuration of a base station according to an embodiment of the present invention. [Figure 5] FIG. 1 is a sequence diagram illustrating a connection between a remote UE and a base station via a relay UE according to a first embodiment of the present invention. [Figure 6] Format for including ECN support information in a discovery response message transmitted by a relay UE according to the first embodiment of the present invention [Figure 7] FIG. 10 is a sequence diagram illustrating a connection between a remote UE and a base station via a relay UE according to a second embodiment of the present invention. [Figure 8] Format for including ECN support information in RRCSetup according to the second embodiment of the present invention DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] [First embodiment]

[0014] (System Configuration) FIG. 1 is a diagram showing an example of the configuration of a system according to this embodiment.

[0015] In FIG. 1, a remote UE-A 101 is a terminal having a sidelink communication function.

[0016] The relay UE-B 102 and the relay UE-C 103 are terminals that are connected to the remote UE-A 101 via sidelink communication and have the function of relaying communication of the remote UE-A 101.

[0017] Base station gNB-D104 and base station gNB-E105 are base stations for cellular communications.

[0018] The 5G core network-F106 and the 5G core network-G107 are core networks for cellular communication. Note that the 5G core network-F106 and the 5G core network-G107 are the same core network, but may be core networks with different network slices.

[0019] In the system shown in Figure 1, the base station gNB-D 104 and relay UE-B 102 are connected via Uu communication, which is communication between a base station and a cellular device. The base station gNB-E 105 and relay UE-C 103 are also connected via Uu communication. The relay UE-B 102 has a Sidelink Relay function and can relay communication between the device (remote UE-A 101) connected via Sidelink communication and the base station gNB-D 104. Similarly, the relay UE-C 103 has a Sidelink Relay function and can relay communication between the device (remote UE-A 101) connected via Sidelink communication and the base station gNB-E 105.

[0020] In Figure 1, the public wireless communication network consisting of base station gNB-D 104 and 5G core network-F 106 supports ECN. That is, if congestion occurs, it has the ability to notify a terminal or application server of congestion in the public wireless communication network using ECN. On the other hand, the public wireless communication network consisting of base station gNB-E 105 and 5G core network-G 107 does not support ECN. That is, it does not have the ability to notify a terminal or application server of congestion in the public wireless communication network using ECN. When remote UE-A 101 wants to connect to the Internet, it performs Sidelink relay discovery. Then, it selects and connects to the desired relay UE from the discovered relay UEs, and connects to the base station via the relay function of the relay UE, thereby connecting to the Internet.

[0021] In this embodiment, 5G cellular communication is assumed, but it is also applicable to cellular network communication other than 5G (for example, 5G Advanced, 6G, etc.). When this embodiment is applied to 6G, the base station may be a 6gNB / 6GNB.

[0022] (Functional configuration of the device) Next, the functional configuration of the communication device according to this embodiment will be described. Note that the functional block configuration described below is merely an example.

[0023] Some (or in some cases all) of the functional blocks described may be replaced with other functional blocks that perform similar functions, some functional blocks may be omitted, or additional functional blocks may 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. Furthermore, only some of the functional blocks may be configured in hardware, with the remaining functions configured in software. When a functional block is configured in software, a processor constituting the control units 201, 301, and 401 described below executes a control program for realizing the functions stored in the storage units 202, 302, and 402 described below. This provides the function of the functional block.

[0024] FIG. 2 is a block diagram showing an example of the functional configuration of the remote UE-A 101 in this embodiment.

[0025] In FIG. 2, reference numeral 201 denotes a control unit that controls the operation of the remote UE-A101.

[0026] Reference numeral 202 denotes a storage unit that stores information used by the control unit 201 for control and information related to communication.

[0027] An ECN compatibility information acquisition unit 203 acquires ECN compatibility information from a relay UE or a base station. The ECN compatibility information will be described in detail later.

[0028] Reference numeral 204 denotes a sidelink relay processing unit that performs processing related to communication with the base station via the relay UE.

[0029] Reference numeral 205 denotes a message generation unit that generates control messages and response messages for acquiring ECN support information and disconnecting the relay UE and the base station.

[0030] 206 is a message analysis processing unit that analyzes messages received from the relay UE and the base station.

[0031] Reference numeral 207 denotes a wireless communication unit that transmits and receives information via wireless communication with a relay UE or a base station via a relay UE. The wireless communication unit 207 performs a transmission process of the message generated by the message generation processing unit 205. Furthermore, a message analysis processing unit 206 performs an analysis process of the message received by the wireless communication unit 207.

[0032] FIG. 3 is a block diagram showing an example of the functional configuration of the relay UE-B 102 and the relay UE-C 103 in this embodiment.

[0033] In FIG. 3, reference numeral 301 denotes a control unit that controls the operations of the relay UE-B 102 and the relay UE-C 103 .

[0034] Reference numeral 302 denotes a storage unit that stores information used by the control unit 301 for control and information related to communication.

[0035] 303 is an ECN compatibility information storage unit that stores ECN compatibility information obtained from base stations and 5G core networks.

[0036] Reference numeral 304 denotes a Sidelink Relay processing unit that performs processing to relay communication between the remote UE and the base station. Reference numeral 305 denotes a message generation unit that generates control messages and response messages related to acquisition and transmission of ECN compatibility information, connection disconnection processing with the remote UE and the base station, relay processing, etc.

[0037] A message analysis processing unit 306 analyzes messages received from the remote UE or the base station. The message analysis processing unit 306 also analyzes messages received by the wireless communication unit 307.

[0038] A wireless communication unit 307 transmits and receives information to and from the remote UE and the base station via wireless communication. The wireless communication unit 307 transmits the message generated by the message generation processing unit 305.

[0039] FIG. 4 is a block diagram showing an example of the functional configuration of base station gNB-D104 and base station gNB-E105 in this embodiment.

[0040] In FIG. 4, 401 is a control unit that controls the operation of base station gNB-D104 and base station gNB-E105.

[0041] Reference numeral 402 denotes a storage unit that stores information used by the control unit 401 for control and information related to communication.

[0042] Reference numeral 403 denotes an ECN compatibility information detection unit that detects (acquires) whether the public wireless communication network supports ECN compatibility information transmission. In this embodiment, the ECN compatibility information is information indicating whether the public wireless communication network to which the terminal is connected supports ECN (Explicit Congestion Notification). That is, the ECN compatibility information is information indicating whether the public wireless communication network has congestion detection capability and, when congestion occurs, indicates the following: That is, it is information indicating whether the public wireless communication network has detection capability to notify the terminal or application server of congestion using ECN (i.e., whether the public wireless communication network detects and notifies congestion). The ECN compatibility information may also be called ECN Capable Transport information. The ECN compatibility information is an example of congestion detection capability information related to congestion detection capability. Note that ECN is a technology defined in RFC8311 for notifying that congestion has occurred in a communication network. When congestion occurs in a communication network, a bit in the ECN field in the IP header is set to "1." This allows an IP communication device that receives the IP header to recognize that congestion has occurred in the communication network.

[0043] Reference numeral 404 denotes a Sidelink Relay processing unit that processes communication with a remote UE via a relay UE.

[0044] Reference numeral 405 denotes a message generation unit that generates control messages and response messages related to the transmission of ECN support information and the processing of disconnecting connections with relay UEs and remote UEs.

[0045] A message analysis processing unit 406 analyzes messages received from relay UEs and remote UEs. The message analysis processing unit 406 also analyzes messages received by a wireless communication unit 407.

[0046] A wireless communication unit 407 transmits and receives information to and from the relay UE and the remote UE via wireless communication. The wireless communication unit 407 transmits the message generated by the message generation processing unit 405.

[0047] (Processing example) The operation of this embodiment will be described using the operation sequence diagram shown in Fig. 5. Also, Fig. 6 shows an example of a message format in this embodiment.

[0048] Fig. 5 shows an example of a sequence in which a remote UE connects to a base station via a relay UE having a UE-to-Network Sidelink relay function in this embodiment. Fig. 6 shows an example of a message format of information included in a discovery response message from a relay UE in this embodiment.

[0049] Message transmission and reception, decision processing, and the like shown in the sequences are realized by the execution of control programs stored in the storage units by the respective control units shown in Figures 2, 3, and 4. Note that some of the processing is realized in cooperation with the functional blocks described in Figures 2, 3, and 4.

[0050] 5, relay UE-B 102 is connected to base station gNB-D 104 and is ready to communicate (F501). Similarly, relay UE-C 103 is connected to base station gNB-E 105 and is ready to communicate (F502). Base station gNB-D 104 supports ECN, but base station gNB-E 105 does not support ECN.

[0051] First, the remote UE-A101 sends a UE-to-Network Relay Discovery message to discover a relay UE having a UE-to-Network Sidelink relay function (F503).

[0052] Upon receiving the UE-to-Network Sidelink Relay Discovery message, the relay UE-B 102 sends a discovery response message including ECN support information (F504).

[0053] Similarly, when the relay UE-C 103 receives the UE-to-Network Sidelink Relay Discovery message, it sends out a discovery response message that does not include ECN support information (F505).

[0054] Next, the remote UE-A 101 determines whether or not the discovery response message received at F504 and F505 contains ECN support information, and then selects a sidelink connection to the relay UE-B 102 connected to the ECN-supporting base station gNB-D 104 (F506).

[0055] The remote UE-A 101 establishes a PC5 (Sidelink) connection with the selected relay UE-B 102 (F507).

[0056] An RRCSetupRequest message is sent via the relay UE-B102 to initiate a connection with the base station gNB-D104 (F508).

[0057] The base station gNB-D104 sends an RRC Setup message to the remote UE-A101 (F509).

[0058] The gNB-D104 and relay UE-B102 set up a relay channel on Uu, and the remote UE-A101 and relay UE-B102 establish a PC5 relay RLC channel (F510).

[0059] The remote UE-A101 transmits an RRCSetupComplete message using the configured relay channel (F511).

[0060] The remote UE-A101 and base station gNB-D104 establish security according to the Uu security mode procedure (F512, F513).

[0061] The remote UE sends an RRCReconfiguration message to set up an SRB (Signaling Radio Bearer) and a DRB (Data Radio Bearer) (F514, F515).

[0062] The base station gNB-D104 sets up an RLC (Radio Link Control) channel for relay traffic (F516).

[0063] Through the processing up to this point, the remote UE-A101 can connect to the base station gNB-D104 that supports ECN and can perform data communication.

[0064] FIG. 6 shows an example of a message format when ECN support information is included in a response message (F504, F505) to the UE-to-Network Relay Discovery message in FIG.

[0065] [Second embodiment] The operation of the second embodiment will be described using the operation sequence diagram shown in Fig. 7. An example of a message format in the second embodiment is shown in Fig. 8. The system configuration and functional configuration of the device in the second embodiment are the same as those in the first embodiment.

[0066] Fig. 7 shows an example of a sequence in which a remote UE connects to a base station via a relay UE having a UE-to-Network Sidelink relay function in the second embodiment. Fig. 8 shows an example of a message format of information included in a control message from a base station in the second embodiment.

[0067] Message transmission and reception, decision processing, and the like shown in the sequences are realized by the execution of control programs stored in the storage units by the respective control units shown in Figures 2, 3, and 4. Note that some of the processing is realized in cooperation with the functional blocks described in Figures 2, 3, and 4.

[0068] In FIG. 7, relay UE-B102 is connected to base station gNB-D104 and is in a communication-enabled state (F501).

[0069] Similarly, relay UE-C 103 is connected to base station gNB-E 105 and is in a communication enabled state (F502). Base station gNB-D 104 supports ECN, but base station gNB-E 105 does not support ECN.

[0070] First, the remote UE-A101 sends a UE-to-Network Relay Discovery message to discover a relay UE having a UE-to-Network Sidelink relay function (F503).

[0071] Upon receiving the UE-to-Network Sidelink Relay Discovery message, the relay UE-B 102 sends a discovery response message (F704).

[0072] Similarly, upon receiving the UE-to-Network Sidelink Relay Discovery message, the relay UE-C 103 also transmits a discovery response message (F705).

[0073] When the remote UE-A 101 receives the discovery response message from the relay UE-B 102, it establishes a PC5 (Sidelink) connection with the relay UE-B 102 (F706).

[0074] The remote UE-A101 sends an RRCSetupRequest message to the base station gNB-D104 via the relay UE-B102 (F707).

[0075] The base station gNB-D104 sends an RRC Setup message including ECN support information to the remote UE-A101 (F708).

[0076] On the other hand, when the remote UE-A101 receives the discovery response message from the relay UE-C103, it establishes a PC5 (Sidelink) connection with the relay UE-C103 (F709).

[0077] The remote UE-A101 sends an RRCSetupRequest message to the base station gNB-E105 via the relay UE-C103 (F710).

[0078] The base station gNB-D104 sends an RRC Setup message that does not include ECN support information to the remote UE-A101 (F711).

[0079] The remote UE-A101 determines whether or not the RRCSetup message received in F708 and F711 contains ECN support information, and selects to connect to the base station gNB-D104 that supports ECN (F712).

[0080] The base station gNB-D104 and relay UE-B102 set up a relay channel on Uu, and the remote UE-A101 and relay UE-B102 establish a PC5 relay RLC channel (F713).

[0081] The remote UE-A101 transmits an RRCSetupComplete message using the configured relay channel (F714).

[0082] The remote UE-A101 and base station gNB-D104 establish security according to the Uu security mode procedure (F715, F716).

[0083] The remote UE sends an RRCReconfiguration message to configure an SRB (Signaling Radio Bearer) and a DRB (Data Radio Bearer) (F717, F718).

[0084] The base station gNB-D104 sets up an RLC (Radio Link Control) channel for relay traffic (F719).

[0085] Through the processing up to this point, the remote UE-A101 can connect to the base station gNB-D104 that supports ECN and can perform data communication.

[0086] FIG. 8 shows an example of a message format when ECN support information is included in the RRC Setup message (F708, F711) in FIG.

[0087] [Other embodiments] In this embodiment, a recording medium storing software program code for implementing the above-described functions may be supplied to a system or device, and the computer (CPU, MPU) of the system or device may read and execute the program code stored on the recording medium. Note that CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes this embodiment. The functions can also be implemented by a circuit (e.g., an ASIC or FPGA) that implements one or more functions. Note that ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. Furthermore, some or all of the various processes described in the above flowcharts can be implemented by a hardware circuit cooperating with a processor such as a CPU or MPU.

[0088] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD (Compact Disc)-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, etc. Also usable are ROMs (Read Only Memory), DVDs (Digital Versatile Discs), HDDs (Hard Disk Drives), SSDs (Solid State Drives), etc.

[0089] In addition, the above-mentioned functions may be realized not only by the computer executing the read program code, but also by the operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of the program code. OS is an abbreviation for Operating System.

[0090] Furthermore, the program code read from the storage medium may be written to a memory provided on a function expansion board inserted into a computer or a function expansion unit connected to the computer, and a CPU provided on the function expansion board or function expansion unit may then perform some or all of the actual processing based on the instructions of the program code to realize the above-mentioned functions.

[0091] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0092] For example, in the above-described embodiment, ECN support information is used as congestion detection capability information regarding the congestion detection capability of the network, but this is not limited to this.Instead of the ECN support information, information indicating a binary value indicating whether or not a function for notifying the occurrence of congestion using ECN is supported may be used as the congestion detection capability information.

[0093] In addition, the following supplementary notes are disclosed regarding the above-described embodiment.

[0094] [Appendix 1] a relay means for connecting to a remote UE (User Equipment) via sidelink communication and relaying communication between the remote UE and a base station; a transmitting means for transmitting congestion detection capability information regarding a congestion detection capability of a network of the base station to the remote UE. [Appendix 2] 2. The communication device according to claim 1, wherein the transmitting means transmits the congestion detection capability information in a control message. [Appendix 3] 2. The communication device according to claim 1, wherein the transmitting means transmits the congestion detection capability information in a response message to a Sidelink Relay Discovery message. [Appendix 4] The communication device according to claim 1 or 2, wherein the congestion detection capability information is information indicating that the communication device is compatible with a function for notifying that congestion has occurred using ECN (Explicit Congestion Notification). [Appendix 5] A base station characterized in that it notifies a remote UE (User Equipment) connected thereto via a relay UE of congestion detection capability information relating to the congestion detection capability of the base station's network. [Appendix 6] The base station according to Supplementary Note 5, wherein the congestion detection capability information is notified by an RRC (Radio Resource Control) message. [Appendix 7] The base station according to claim 5 or 6, wherein the congestion detection capability information is information indicating that the base station is compatible with a function for notifying that congestion has occurred using ECN (Explicit Congestion Notification). [Appendix 8] a communication means for connecting with a relay UE (User Equipment) via sidelink communication and communicating with a base station via the relay UE; an acquisition means for acquiring congestion detection capability information relating to the congestion detection capability of the base station network; a selection means for selecting a relay UE to be connected by the communication means based on the congestion detection capability information. [Appendix 9] The communication device according to claim 8, wherein the acquisition means acquires the congestion detection capability information from a control message transmitted from a relay UE. [Appendix 10] The communication device according to claim 8 or 9, wherein the acquisition means acquires the congestion detection capability information from a message transmitted from a relay UE, the message being a response message to a Sidelink Relay Discovery message. [Appendix 11] The communication device according to any one of appendices 8 to 10, wherein the acquisition means acquires the congestion detection capability information from an RRC (Radio Resource Control) message transmitted from the base station. [Appendix 12] The communication device described in any one of Appendices 8 to 11, characterized in that the congestion detection capability information is information indicating that the device is compatible with a function to notify that congestion has occurred using ECN (Explicit Congestion Notification). [Appendix 13] The communication device described in Supplementary Note 12, characterized in that the selection means selects relay UEs connected to networks that support the function with priority over relay UEs connected to networks that do not support the function. [Appendix 14] A control method for controlling communication of a communication device, comprising: a step of connecting to a remote UE (User Equipment) via sidelink communication and relaying communication between the remote UE and a base station; and transmitting congestion detection capability information regarding congestion detection capability of the base station's network to the remote UE. [Appendix 15] The computer of the communication device a step of connecting to a remote UE (User Equipment) via sidelink communication and relaying communication between the remote UE and a base station; and transmitting congestion detection capability information regarding the congestion detection capability of the base station's network to the remote UE. [Appendix 16] A control method for controlling communication of a base station, comprising: A control method characterized by notifying a remote UE connected via a relay UE (User Equipment) of congestion detection capability information relating to the congestion detection capability of the local station's network. [Appendix 17] A program that causes a base station computer to execute a process of notifying a remote UE connected via a relay UE (User Equipment) of congestion detection capability information about the congestion detection capability of the base station's network. [Appendix 18] A control method for controlling communication of a communication device, comprising: a communication step of connecting with a relay UE (User Equipment) via sidelink communication and communicating with a base station via the relay UE; obtaining congestion detection capability information relating to congestion detection capability of a network of the base station; and selecting a relay UE to connect in the communication step based on the congestion detection capability information. [Appendix 19] The computer of the communication device a communication step of connecting with a relay UE (User Equipment) via sidelink communication and communicating with a base station via the relay UE; obtaining congestion detection capability information relating to congestion detection capability of a network of the base station; and a step of selecting a relay UE to connect to in the communication step based on the congestion detection capability information. [Explanation of symbols]

[0095] 101 Remote UE-A 102 Relay UE-B 103 Relay UE-C 104 Base station gNB-D 105 Base station gNB-E 106 5G Core Network-F 107 5G Core Network-G

Claims

1. A relay means for connecting to a remote UE (User Equipment) via Sidelink communication and relaying communication between the remote UE and a base station; and transmitting means for transmitting congestion detection capability information relating to a congestion detection capability of a network of the base station to the remote UE.

2. 2. The communication device according to claim 1, wherein said transmission means transmits said congestion detection capability information in a control message.

3. 2. The communication device according to claim 1, wherein the transmitting means transmits the congestion detection capability information in a response message to a Sidelink relay discovery message.

4. 2. The communication device according to claim 1, wherein the congestion detection capability information is information indicating that the communication device is compatible with a function of notifying the occurrence of congestion using ECN (Explicit Congestion Notification).

5. A base station notifies a remote UE connected thereto via a relay UE (User Equipment), of congestion detection capability information relating to congestion detection capability of the base station's network.

6. The base station according to claim 5, wherein the congestion detection capability information is notified by an RRC (Radio Resource Control) message.

7. 7. The base station according to claim 6, wherein the congestion detection capability information is information indicating that the base station is compatible with a function of notifying the occurrence of congestion using ECN (Explicit Congestion Notification).

8. A communication means for connecting with a relay UE (User Equipment) via Sidelink communication and communicating with a base station via the relay UE; an acquisition means for acquiring congestion detection capability information relating to the congestion detection capability of the base station network; a selection unit that selects a relay UE to be connected by the communication unit based on the congestion detection capability information.

9. The communication device according to claim 8 , wherein the acquisition unit acquires the congestion detection capability information from a control message transmitted from a relay UE.

10. The communication device according to claim 8 , wherein the acquisition unit acquires the congestion detection capability information from a response message to a Sidelink Relay Discovery message, the response message being a message transmitted from a relay UE.

11. 9. The communication device according to claim 8, wherein the acquisition means acquires the congestion detection capability information from an RRC (Radio Resource Control) message transmitted from the base station.

12. 9. The communication device according to claim 8, wherein the congestion detection capability information is information indicating that the communication device is compatible with a function of notifying the occurrence of congestion using ECN (Explicit Congestion Notification).

13. 13. The communication device according to claim 12, wherein the selection means selects a relay UE connected to a network that supports the function with priority over a relay UE connected to a network that does not support the function.

14. A control method for controlling communication of a communication device, comprising: A step of connecting with a remote UE (User Equipment) via Sidelink communication and relaying communication between the remote UE and a base station; transmitting congestion detection capability information relating to a congestion detection capability of a network of the base station to the remote UE.

15. The computer of the communication device A step of connecting with a remote UE (User Equipment) via Sidelink communication and relaying communication between the remote UE and a base station; and transmitting congestion detection capability information regarding the congestion detection capability of the network of the base station to the remote UE.

16. A control method for controlling communication of a base station, comprising: A control method characterized in that congestion detection capability information relating to the congestion detection capability of the own station's network is notified to a remote UE connected via a relay UE (User Equipment).

17. A program for causing a base station computer to execute a process of notifying a remote UE connected via a relay UE (User Equipment) of congestion detection capability information regarding the congestion detection capability of the base station's network.

18. A control method for controlling communication of a communication device, comprising: a communication step of connecting with a relay UE (User Equipment) via Sidelink communication and communicating with a base station via the relay UE; obtaining congestion detection capability information relating to congestion detection capability of a network of the base station; and selecting a relay UE to be connected in the communication step based on the congestion detection capability information.

19. The computer of the communication device a communication step of connecting with a relay UE (User Equipment) via Sidelink communication and communicating with a base station via the relay UE; obtaining congestion detection capability information relating to congestion detection capability of a network of the base station; and a step of selecting a relay UE to connect to in the communication step based on the congestion detection capability information.

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