COMMUNICATION METHOD, COMMUNICATION DEVICE, AND COMMUNICATION SYSTEM

Abstract

The present application provides a communication method, a communication device, and a communication system. In this method, when a relay terminal device is configured for a remote terminal device, the remote terminal device receives information about the relay terminal device through an interface between the remote terminal device and an access network device, and then sends instruction information to the relay terminal device. The instruction information can trigger the relay terminal device to enter an RRC connected state, so that the relay terminal device can provide relay services for the remote terminal device, thereby ensuring that multiple routes are successfully configured between the remote terminal device and the access network device for the remote terminal device. This can improve the reliability of communication between the remote terminal device and the access network device, and improve service quality and user experience.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to Chinese Patent Application No. 202210920848.0, filed with the State Intellectual Property Office of the People's Republic of China on August 2, 2022, for an invention entitled "Communication Method, Communication Device, and Communication System," which is incorporated herein by reference in its entirety. [Technical field] The present application relates to the field of wireless communication technology, and in particular to a communication method, a communication device, and a communication system. [Background technology]

[0002] In some application scenarios, it is necessary to use relay technology. Specifically, a terminal device can help another terminal device communicate with an access network device. Specifically, a remote terminal device communicates with an access network device by cooperating with a relay terminal device.

[0003] In addition, in some other application scenarios, it may be necessary to configure multiple routes for a terminal device. Specifically, a remote terminal device may communicate with an access network device directly, or may communicate with an access network device by cooperating with an intermediate terminal device.

[0004] In a scenario where multiple paths are configured for an end device, it is necessary to solve how to ensure the success of the multi-path configuration. Summary of the Invention [Means for solving the problem]

[0005] To ensure that multiple paths are successfully configured for a terminal device between the terminal device and an access network device, the present application provides a communication method, a communication apparatus, and a communication system.

[0006] According to a first aspect, an embodiment of the present application provides a communication method. The method may be performed by a remote terminal device or by a module (e.g., a chip) used in the remote terminal device. An example in which the remote terminal device performs the method is used. The method includes the step of the remote terminal device receiving a configuration message from the access network device through an interface between the remote terminal device and the access network device, the configuration message including information about a relay terminal device, and the configuration message being used for RRC reconfiguration. The remote terminal device sends indication information to the relay terminal device based on the information about the relay terminal device, and the indication information triggers the relay terminal device to enter an RRC connected state.

[0007] In the above solution, there is a direct path between the access network device and the remote terminal device. When a relay terminal device is configured for the remote terminal device, the remote terminal device receives information about the relay terminal device through the interface between the remote terminal device and the access network device, and then sends instruction information to the relay terminal device. The instruction information can trigger the relay terminal device to enter an RRC connected state, so that the relay terminal device can provide relay services for the remote terminal device. This ensures that multiple paths are successfully configured between the remote terminal device and the access network device for the remote terminal device. This can improve the reliability of communication between the remote terminal device and the access network device, and improve service quality and user experience.

[0008] In one possible implementation, the remote terminal device determines, based on the RRC status of the relay terminal device, that the relay terminal device needs to be triggered to enter an RRC connected state.

[0009] In this solution, the remote terminal device determines whether the relay terminal device needs to be triggered to enter the RRC connected state based on the RRC status of the relay terminal device. If the relay terminal device does not need to be triggered to enter the RRC connected state, the remote terminal device does not need to send indication information to trigger the relay terminal device to enter the RRC connected state, in order to reduce signaling overhead. If the relay terminal device needs to be triggered to enter the RRC connected state, indication information is sent to ensure that the relay terminal device can be triggered to enter the RRC connected state, thereby ensuring that multiple paths are successfully configured between the remote terminal device and the access network device for the remote terminal device. This can improve the reliability of communication between the remote terminal device and the access network device, and improve service quality and user experience.

[0010] In one possible implementation, the configuration message further includes status information, where the status information indicates an RRC status of the relay terminal device. The remote terminal device determines the RRC status of the relay terminal device based on the status information.

[0011] In this solution, the remote terminal device can accurately know the RRC status of the relay terminal device based on the status information, and the base station includes the status information in the configuration message and does not need to include the status information in an additional message, thereby reducing signaling overhead.

[0012] In another implementation, the status information is carried in a separate message, different from the configuration message described above, and sent to the remote terminal device. The specific manner in which the access network device sends the status information to the remote terminal device is not limited by this application.

[0013] In one possible implementation, the indication information is a configuration complete message in response to the configuration message.

[0014] In this solution, the configuration complete message is used to trigger the relay terminal device to enter the RRC connected state, and no further message needs to be sent to trigger the relay terminal device to enter the RRC connected state, thereby reducing signaling overhead.

[0015] In one possible implementation, the remote terminal device sends a configuration complete message to the access network device through an interface between the remote terminal device and the access network device, which may be a Uu air interface.

[0016] In one possible implementation, the remote terminal device sending the indication information to the relay terminal device includes a step of the remote terminal device sending a request message to the relay terminal device, the request message including the indication information, the request message for requesting to set up a unicast connection, and the indication information indicating that the unicast connection is to be set up to obtain the relay service of the relay terminal device. The request message may be a unicast connection setup request message or a unicast connection setup response message.

[0017] In this solution, the signaling overhead can be reduced because the request message carries the indication information and there is no need to send an additional message to carry the indication information.

[0018] In one possible implementation, the indication information is a request message for requesting the setup of a unicast connection associated with the relay service.

[0019] In one possible implementation, the indication information is PC5-S signaling, a PC5 RRC message, or a sidelink medium access control control element SL MAC CE signaling.

[0020] In one possible implementation, the remote terminal device determines that a link failure or connection failure has occurred between the remote terminal device and the relay terminal device and sends first failure indication information to the access network device, the first failure indication information indicating that a link failure or connection failure has occurred between the remote terminal device and the relay terminal device.

[0021] In this solution, after a multipath configuration process is performed for a remote terminal device or after the multipath configuration is completed, a connection is set up between the remote terminal device and the relay terminal device, but later, when a link failure or connection failure occurs between the remote terminal device and the relay terminal device, the access network device is notified to help avoid improper multipath configuration. Thereafter, the access network device can reselect a relay terminal device for the remote terminal and configure a link between the access network device, the new relay terminal device, and the remote terminal device.

[0022] In one possible implementation, the remote terminal device determines that a link failure or connection failure has occurred between the remote terminal device and the access network device, and sends second failure indication information to the access network device via the relay terminal device, where the second failure indication information indicates that a link failure or connection failure has occurred between the remote terminal device and the access network device.

[0023] In this solution, after a multipath configuration process is performed for a remote terminal device or after the multipath configuration is completed, a connection is set up between the remote terminal device and the access network device, but later, if a link failure or connection failure occurs between the remote terminal device and the access network device, the access network device is notified so that the access network device can perform subsequent processing. For example, the access network device can select an appropriate cell for the remote terminal device and configure a link between the remote terminal device and the access network device.

[0024] In one possible implementation, the remote terminal device receives third fault indication information from the relay terminal device, the third fault indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device, and the remote terminal device sends fourth fault indication information to the access network device, the fourth fault indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device.

[0025] In this solution, after a multipath configuration process is performed for a remote terminal device or after the multipath configuration is completed, a connection is set up between the relay terminal device and the access network device, but later, if a link failure or connection failure occurs between the relay terminal device and the access network device, the access network device is notified, so that the access network device can detect in a timely manner that the link between the relay terminal device and the access network device is unavailable, reselect a relay terminal device, and configure a link for the remote terminal device.

[0026] In one possible implementation, the remote terminal device transmits information about at least one candidate terminal device to the access network device through an interface between the remote terminal device and the access network device, where the at least one candidate terminal device includes a relay terminal device, and the information about the at least one candidate terminal device includes information indicating the signal quality of the candidate terminal device and / or whether the candidate terminal device supports multipath relaying.

[0027] The information indicating whether the candidate terminal device supports multi-path relaying may be indication information or capability information of the candidate terminal device. The capability information indicates that the candidate terminal device supports multi-path relaying or does not support multi-path relaying.

[0028] In the above solution, a remote terminal device provides one or more candidate terminal devices for an access network device, and then the access network device selects one terminal device from the one or more candidate terminal devices as an intermediate terminal device for the remote terminal device, which helps to configure an appropriate intermediate terminal device for the remote terminal device.

[0029] In one possible implementation, the remote terminal device receives a discovery message from a candidate terminal device, the discovery message including information indicating whether the candidate terminal device supports multi-path relaying.

[0030] In one possible implementation, the remote terminal device receives a discovery message from a candidate terminal device, and the identification information of the candidate terminal device corresponding to the discovery message indicates whether the candidate terminal device supports multi-path relaying.

[0031] According to a second aspect, an embodiment of the present application provides a communication method. The method may be performed by a relay terminal device or by a module (e.g., a chip) used in the relay terminal device. An example in which the relay terminal device performs the method is taken as follows. The method includes a step in which the relay terminal device receives indication information from a remote terminal device, where the indication information triggers the relay terminal device to enter an RRC connected state. The relay terminal device transmits sidelink UE information to an access network device, where the sidelink UE information includes information about the remote terminal device and / or information about the relay terminal device.

[0032] In the above solution, the relay terminal device receives indication information from the remote terminal device, and the indication information can trigger the relay terminal device to enter an RRC connected state, so that the relay terminal device can provide a relay service for the remote terminal device, thereby ensuring that multiple paths are successfully configured for the remote terminal device between the remote terminal device and the access network device, thereby improving the reliability of communication between the remote terminal device and the access network device, and improving service quality and user experience.

[0033] In one possible implementation, the relay terminal device enters the RRC connected state based on the indication information.

[0034] In one possible implementation, the indication information is PC5-S signaling, a PC5 RRC message, a SL MAC CE signaling, or a configuration complete message from the relay terminal device.

[0035] In one possible implementation, the relay terminal device receiving the indication information from the remote terminal device includes the relay terminal device receiving a request message from the remote terminal device, the request message including the indication information, the request message being for requesting that a unicast connection be set up, and the indication information indicating that the unicast connection be set up to obtain the relay service of the relay terminal device.

[0036] In this solution, the signaling overhead can be reduced because the request message carries the indication information and there is no need to send an additional message to carry the indication information.

[0037] In one possible implementation, the indication information is a request message for requesting the setup of a unicast connection associated with the relay service.

[0038] In one possible implementation, the relay terminal device receives notification information from the access network device, the notification information being for determining whether the relay terminal device needs to forward control plane signaling for the remote terminal device, and determines based on the notification information that the control plane signaling needs to be forwarded for the remote terminal device or that the control plane signaling does not need to be forwarded for the remote terminal device.

[0039] In this solution, if the remote terminal device can receive the control plane signaling of the access network device through the interface between the remote terminal device and the access network device, the relay terminal device does not need to monitor the control plane signaling sent by the access network device and forward it to the relay terminal device, thereby reducing the signaling overhead of the relay terminal device.

[0040] In one possible implementation, the relay terminal device determines that a link failure or connection failure has occurred between the relay terminal device and the access network device and sends failure indication information to the remote terminal device, the failure indication information indicating that a link failure or connection failure has occurred between the relay terminal device and the access network device.

[0041] In one possible implementation, the relay terminal device transmits a discovery message to the remote terminal device, the discovery message including information indicating that the relay terminal device supports multi-path relaying.

[0042] In one possible implementation, the relay terminal device sends a discovery message to the remote terminal device, and the identification information of the relay terminal device corresponding to the discovery message indicates that the relay terminal device supports multi-path relaying.

[0043] According to a third aspect, an embodiment of the present application provides a communication method. The method may be performed by an access network device or by a module (e.g., a chip) used in the access network device. An example in which the access network device performs the method is used. The method includes a step in which the access network device sends a configuration message to the remote terminal device through an interface between the remote terminal device and the access network device, the configuration message including information and status information related to the relay terminal device, the configuration message being used for RRC reconfiguration, and the status information indicating the RRC status of the relay terminal device. The access network device receives a configuration complete message in response to the configuration message from the remote terminal device through the interface between the remote terminal device and the access network device. The access network device receives sidelink UE information from the relay terminal device, the sidelink UE information including information related to the relay terminal device and information related to the remote terminal device.

[0044] To ensure that multiple paths are successfully configured between the remote terminal device and the access network device for the remote terminal device, in the above solution, when the access network device configures a relay terminal device for the remote terminal device, the access network device sends status information indicating the RRC status of the relay terminal device to the remote terminal device, so that the remote terminal device can know the RRC status of the relay terminal device, and can determine whether to trigger the relay terminal device to enter an RRC connected state, and the relay terminal device can provide relay service for the remote terminal device, thereby improving the reliability of communication between the remote terminal device and the access network device and improving service quality and user experience.

[0045] In one possible implementation, the access network device receives a configuration complete message in response to the configuration message from the remote terminal device through an interface between the remote terminal device and the access network device.

[0046] In one possible implementation, the access network device receives a configuration completion message in response to the configuration message from the remote terminal device via the relay terminal device. In one possible implementation, the access network device sends notification information to the relay terminal device, and the notification information is for the relay terminal device to determine whether it needs to forward control plane signaling for the remote terminal device.

[0047] In this solution, if the remote terminal device can receive control plane signaling from the access network device through the interface between the remote terminal device and the access network device, the relay terminal device does not need to monitor and forward control plane signaling sent by the access network device to the relay terminal device, thereby reducing the signaling overhead of the relay terminal device.

[0048] In one possible implementation, the access network device receives information about at least one candidate terminal device from the remote terminal device through an interface between the remote terminal device and the access network device, the information about the at least one candidate terminal device including information indicating a signal quality of the candidate terminal device and / or whether the candidate terminal device supports multipath relaying. The access network device selects a relay terminal device from the at least one candidate terminal device based on the information about the at least one candidate terminal device.

[0049] In the above solution, a remote terminal device provides one or more candidate terminal devices for an access network device, and then the access network device selects one terminal device from the one or more candidate terminal devices as an intermediate terminal device for the remote terminal device, which helps to configure an appropriate intermediate terminal device for the remote terminal device.

[0050] According to a fourth aspect, an embodiment of the present application provides a communication method. The method may be performed by a remote terminal device or by a module (e.g., a chip) used in the remote terminal device. An example in which the remote terminal device performs the method is used. The method includes the steps of the remote terminal device selecting a relay terminal device, the remote terminal device sending an RRC re-setup request message to an access network device, the remote terminal device receiving an RRC re-setup message from the access network device, and the remote terminal device sending an RRC re-setup complete message to the access network device, where the RRC re-setup complete message includes information about the relay terminal device and / or information about the remote terminal device.

[0051] The information about the relay terminal device may include a destination Layer 2 identifier (L2 ID) of the relay terminal device. The information about the remote terminal device may include a source Layer 2 identifier (L2 ID) of the remote terminal device.

[0052] In the above solution, after the re-setup procedure of the remote terminal device is completed, the access network device can configure multiple routes for the remote terminal device based on the information about the intermediate terminal device selected by the remote terminal device, which helps to realize quick multi-route configuration of the remote terminal device.

[0053] In one possible implementation, before the remote terminal device sends an RRC re-setup complete message to the access network device, the remote terminal device sets up a unicast connection between the relay terminal device and triggers the relay terminal device to report the identification information of the relay terminal device and / or the identification information of the remote terminal device.

[0054] In the above solution, the access network device configures multi-path relaying for the remote terminal device based on the information about the relay terminal device and / or the information about the remote terminal device in the RRC re-setup complete message and the identification information of the relay terminal device and / or the identification information of the remote terminal device received from the relay terminal device, so that the remote terminal device can set up multi-path relaying with the access network device via the relay terminal device.

[0055] In one possible implementation, the remote terminal device selecting the relay terminal device specifically includes the step of the remote terminal device selecting a terminal device from the cell in which the remote terminal device is located as the relay terminal device, which may be the terminal device with the largest reference signal received power in the cell, or any terminal device in the cell.

[0056] Of course, the relay terminal device selected by the remote terminal device and the remote terminal device do not have to be in the same cell, but the cell in which the remote terminal device is located and the cell in which the relay terminal device is located belong to the same access network device.

[0057] According to a fifth aspect, an embodiment of the present application provides a communication method. The method may be performed by a remote terminal device or by a module (e.g., a chip) used in the remote terminal device. An example in which the remote terminal device performs the method is taken as follows. The method includes: determining, by the remote terminal device, that a link failure or connection failure has occurred between the remote terminal device and an intermediate terminal device; and transmitting first failure indication information to an access network device, the first failure indication information indicating that a link failure or connection failure has occurred between the remote terminal device and the intermediate terminal device.

[0058] In this solution, a connection is set up between a remote terminal device and an intermediate terminal device, and later, if a link failure or connection failure occurs between the remote terminal device and the intermediate terminal device, the access network device is notified, so that the access network device can quickly re-setup the link between the remote terminal device and the intermediate terminal device, or the access network device re-selects an intermediate terminal device and sets up a corresponding multi-path relay, which helps to provide high-quality service guarantee to the remote terminal device.

[0059] In one possible implementation, the remote terminal device determines that a link failure or connection failure has occurred between the remote terminal device and the access network device, and sends second failure indication information to the access network device via the relay terminal device, where the second failure indication information indicates that a link failure or connection failure has occurred between the remote terminal device and the access network device.

[0060] In this solution, a connection is set up between a remote terminal device and an access network device, and later, if a link or connection failure occurs between the remote terminal device and the access network device, the access network device is notified, so that the access network device can quickly re-setup the link between the remote terminal device and the access network device, which helps to provide a high quality service guarantee to the remote terminal device.

[0061] In one possible implementation, the remote terminal device receives third fault indication information from the relay terminal device, the third fault indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device, and the remote terminal device sends fourth fault indication information to the access network device, the fourth fault indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device.

[0062] In this solution, a connection is set up between an intermediate terminal device and an access network device, and later, if a link failure or connection failure occurs between the intermediate terminal device and the access network device, the access network device is notified, so that the access network device can quickly re-setup the link between the intermediate terminal device and the access network device, or the access network device reselects an intermediate terminal device and sets up a corresponding multi-path relay, which helps to provide high-quality service guarantee to the remote terminal device.

[0063] According to a sixth aspect, an embodiment of the present application provides a communication method. The method may be performed by an intermediate terminal device or by a module (e.g., a chip) used in the intermediate terminal device. An example in which the intermediate terminal device performs the method is taken as follows. The method includes: determining, by the intermediate terminal device, that a link failure or connection failure has occurred between the intermediate terminal device and an access network device; and transmitting failure indication information to a remote terminal device, wherein the failure indication information indicates that a link failure or connection failure has occurred between the intermediate terminal device and the access network device.

[0064] According to a seventh aspect, an embodiment of the present application provides a communication method. The method may be performed by an access network device or by a module (e.g., a chip) used in the access network device. An example in which the access network device performs the method is taken. The method includes a step in which the access network device determines whether an intermediate terminal device needs to forward control plane signaling for a remote terminal device. The access network device sends notification information to the intermediate terminal device, and the notification information is for determining whether the intermediate terminal device needs to forward control plane signaling for the remote terminal device.

[0065] In this solution, if the remote terminal device can receive the control plane signaling of the access network device through the interface between the remote terminal device and the access network device, the relay terminal device does not need to monitor the control plane signaling sent by the access network device and forward it to the relay terminal device, thereby reducing the signaling overhead of the relay terminal device.

[0066] In one possible implementation, the access network device determining whether the intermediate terminal device needs to forward control plane signaling for the remote terminal device includes the access network device determining that the intermediate terminal device does not need to forward control plane signaling for the remote terminal device if the remote terminal device can receive control plane signaling from the access network device through an interface between the remote terminal device and the access network device. If the remote terminal device cannot receive control plane signaling from the access network device through the interface between the remote terminal device and the access network device, the access network device determines that the intermediate terminal device needs to forward control plane signaling for the remote terminal device.

[0067] In one possible implementation, the access network device sends a configuration message to the remote terminal device through an interface between the remote terminal device and the access network device, the configuration message including information and status information about the relay terminal device, the configuration message is used for RRC reconfiguration, and the status information indicates an RRC status of the relay terminal device. The access network device receives a configuration complete message in response to the configuration message from the remote terminal device through the interface between the remote terminal device and the access network device. The access network device receives sidelink UE information from the relay terminal device, the sidelink UE information including information about the relay terminal device and information about the remote terminal device.

[0068] According to an eighth aspect, an embodiment of the present application provides a communication method. The method may be performed by a relay terminal device or by a module (e.g., a chip) used in the relay terminal device. An example of performing the method by a relay terminal device includes receiving notification information from an access network device by the relay terminal device, the notification information being for determining whether the relay terminal device needs to forward control plane signaling for a remote terminal device. Based on the notification information, the relay terminal device determines whether control plane signaling needs to be forwarded for the remote terminal device or whether control plane signaling does not need to be forwarded for the relay terminal device.

[0069] In this solution, if the remote terminal device can receive the control plane signaling of the access network device through the interface between the remote terminal device and the access network device, the relay terminal device does not need to monitor the control plane signaling sent by the access network device and forward it to the relay terminal device, thereby reducing the signaling overhead of the relay terminal device.

[0070] In one possible implementation, the notification information indicates a relay service type provided by the relay terminal device. The relay terminal device determining, based on the notification information, that control plane signaling needs to be forwarded for the remote terminal device or that control plane signaling does not need to be forwarded for the relay terminal device includes determining, based on the relay service type provided by the relay terminal device, that control plane signaling needs to be forwarded for the remote terminal device or that control plane signaling does not need to be forwarded for the relay terminal device.

[0071] In one possible implementation, the relay terminal device receives indication information from the remote terminal device, where the indication information triggers the relay terminal device to enter an RRC connected state. The relay terminal device transmits sidelink UE information to the access network device, where the sidelink UE information includes information about the remote terminal device and / or information about the relay terminal device.

[0072] According to a ninth aspect, an embodiment of the present application provides a communication device. The device may be a remote terminal device, or may be a chip or module used in a remote terminal device. The device has a function for implementing any of the first, fourth, or fifth aspects. The function may be realized by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned functions.

[0073] According to a tenth aspect, an embodiment of the present application provides a communication device. The device may be a relay terminal device or a chip used in the relay terminal device. The device has a function for implementing any of the second, sixth, or eighth aspects. The function may be realized by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned functions.

[0074] According to an eleventh aspect, an embodiment of the present application provides a communication device. The device may be an access network device or a chip used in the access network device. The device has a function for implementing either the third aspect or the seventh aspect. The function may be realized by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned functions.

[0075] According to a twelfth aspect, an embodiment of the present application provides a communication device including a processor and an interface circuit, wherein the processor is configured to communicate with another device via the interface circuit and to perform an implementation of any of the first to sixth aspects, and wherein there are one or more processors.

[0076] According to a thirteenth aspect, an embodiment of the present application provides a communication device including a processor coupled to a memory. The processor is configured to invoke a program stored in the memory to execute an implementation of any of the first to sixth aspects. The memory may be located internal or external to the device. Additionally, there may be one or more processors.

[0077] According to a fourteenth aspect, an embodiment of the present application provides a communications device including a processor and a memory, the memory configured to store computer instructions, the processor executing the computer instructions stored in the memory when the device is operating to enable the device to perform an implementation of any of the first to sixth aspects.

[0078] According to a fifteenth aspect, an embodiment of the present application provides a communication device including a unit or means for performing the steps of any of the implementations of the first to sixth aspects.

[0079] According to a sixteenth aspect, an embodiment of the present application further provides a computer-readable storage medium storing instructions that, when executed in a communication device, implement any of the first to sixth aspects.

[0080] According to a seventeenth aspect, an embodiment of the present application further provides a computer program product, the computer program product including computer programs or instructions, which, when executed by a communication device, implement any of the first to sixth aspects.

[0081] According to an eighteenth aspect, an embodiment of the present application further provides a chip system including a processor, the processor configured to execute an implementation of any of the first to sixth aspects.

[0082] According to a nineteenth aspect, an embodiment of the present application further provides a communication system including: a remote terminal device configured to perform the method of any implementation of the first aspect; and a relay terminal device configured to perform the method of any implementation of the second aspect.

[0083] In one possible implementation, the communication system further includes an access network device configured to perform any implementation of the third aspect.

[0084] According to a twentieth aspect, an embodiment of the present application further provides a communication system including: an access network device configured to perform any implementation of the seventh aspect; and a relay terminal device configured to perform any implementation of the eighth aspect. [Brief explanation of the drawings]

[0085] [Figure 1] 1 is a diagram of the architecture of a communication system to which an embodiment of the present application applies; [Figure 2] A diagram of the communication architecture of the SL U2N Relay. [Figure 3] This is a diagram of the protocol stack for L2SL U2N Relay. [Figure 4] This is a diagram of the communication architecture of multi-path relay. [Figure 5] This is a diagram of the protocol stack architecture of multi-path relay. [Figure 6(a)] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6(b)]1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6(c)] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6(d)] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6(e)] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6(f)] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 7] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 8(a)] FIG. 1 is a diagram of a PC5 RLF occurring between a remote UE and a relay UE. [Figure 8(b)] FIG. 1 is a diagram of a link failure occurring between a remote UE and a relay UE. [Figure 8(c)] 1 is a diagram of a Uu RLF occurring between a relay UE and a base station. [Figure 8(d)] FIG. 1 is a diagram of an RRC setup failure occurring between a relay UE and a base station. [Figure 8(e)] FIG. 1 is a diagram of an RRC setup failure occurring between a relay UE and a base station. [Figure 9] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 10] 1 is a diagram of a communication device according to an embodiment of the present application; [Figure 11] 1 is a diagram of a communication device according to an embodiment of the present application; [Figure 12] FIG. 1 is a diagram of the structure of a terminal device. DETAILED DESCRIPTION OF THE INVENTION

[0086] FIG. 1 is a diagram of the architecture of a communication system to which an embodiment of the present application is applied. The communication system 1000 includes a radio access network 100 and a core network 200. Optionally, the communication system 1000 may further include the Internet 300. The radio access network 100 includes at least one access network device, e.g., 110a and 110b in FIG. 1 , and at least one terminal device, e.g., 120a to 120j in FIG. 1 . 110a is a base station, 110b is a micro base station, 120a, 120e, 120f, and 120j are mobile phones, 120b is a vehicle, 120c is a fuel dispenser, 120d is a home access point (HAP) deployed indoors or outdoors, 120g is a notebook computer, 120h is a printer, and 120i is an unmanned aerial vehicle. The same terminal device or access network device may provide different functions in different application scenarios. For example, the mobile phones in FIG. 1 include 120a, 120e, 120f, and 120j. Mobile phone 120a can access base station 110a, connect to vehicle 120b, communicate directly with mobile phone 120e, and access the HAP. Mobile phone 120b can access the HAP and communicate directly with mobile phone 120a. Mobile phone 120f can access micro base station 110b, connect to notebook computer 120g, and connect to printer 120h. Mobile phone 120j can control unmanned aerial vehicle 120i.

[0087] Terminal devices are connected to access network devices, and the access network devices are connected to a core network. The core network device and the access network device may be separate physical devices independent of each other, or the functions of the core network device and the logical functions of the access network device may be integrated into the same physical device, or some functions of the core network device and some functions of the access network device may be integrated into one physical device. The terminal devices may be connected to each other in a wired or wireless manner, and the access network devices may be connected to each other in a wired or wireless manner. Figure 1 is merely a diagram. The communication system may further include other network devices, for example, wireless relay devices and wireless backhaul devices not shown in Figure 1.

[0088] The access network device may be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) of a fifth generation (5G) mobile communication system, a base station of a sixth generation (6G) mobile communication system, a base station of a future mobile communication system, an access node of a wireless fidelity (WiFi) system, etc. Alternatively, the access network device may be a module or unit that performs some functions of a base station, for example, a central unit (CU) or a distributed unit (DU). The access network device may be a macro base station (e.g., 110a in FIG. 1), a micro base station or an indoor base station (e.g., 110b in FIG. 1), or a relay node, a donor node, etc. The specific technology and specific device form adopted by the access network device are not limited by the embodiments of the present application. In this embodiment of the present application, an example in which a base station is used as an access network device is used for illustration.

[0089] A terminal device may also be referred to as a terminal, user equipment (UE), mobile station, mobile terminal, etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D) scenarios, vehicle-to-everything (V2X) communication scenarios, machine-type communication (MTC) scenarios, Internet of Things (IoT) scenarios, virtual reality scenarios, augmented reality scenarios, industrial control scenarios, autonomous driving scenarios, telemedicine scenarios, smart grid scenarios, smart furniture scenarios, smart office scenarios, smart clothing scenarios, smart transportation scenarios, and smart city scenarios. Terminal devices may be mobile phones, tablet computers, computers with wireless transceiver capabilities, wearable devices, vehicles, unmanned aerial vehicles, helicopters, airplanes, ships, robots, mechanical arms, smart home devices, etc. The specific technologies and specific device forms adopted by the terminal devices are not limited by the embodiments of this application.

[0090] The base station and the UE may be fixed or mobile. The base station and the UE may be deployed on land, including indoor or outdoor scenarios, and handheld or vehicle-mounted scenarios, or on water, or on airborne aircraft, balloons, and satellites. The application scenarios of the base station and the UE are not limited by the embodiments of the present application.

[0091] The roles of a base station and a UE may be relative. For example, helicopter or unmanned aerial vehicle 120i in FIG. 1 may be configured as a mobile base station. If 120j accesses the wireless access network 100 through 120i, then 120i is a base station. However, from the perspective of base station 110a, 120i is a UE, and specifically, communication between 110a and 120i is performed according to a wireless air interface protocol. Of course, communication between 110a and 120i may instead be performed according to an interface protocol between base stations. In this case, 120i is also a base station from the perspective of 110a. Therefore, the base station and UE may be collectively referred to as communication devices, and 110a and 110b in FIG. 1 may each be referred to as communication devices having base station functionality, and 120a to 120j in FIG. 1 may each be referred to as communication devices having UE functionality.

[0092] Communications between base stations and UEs, between base stations, and between UEs may be performed using licensed spectrum, or may be performed using unlicensed spectrum, or may be performed using both licensed and unlicensed spectrum. Communications may be performed using spectrum below 6 gigahertz (GHz), or may be performed using spectrum above 6 GHz, or may be performed using spectrum below 6 GHz and spectrum above 6 GHz. Spectral resources for wireless communications are not limited in the embodiments of the present application.

[0093] To facilitate understanding of the solutions of the embodiments of the present application, the terms or terms in the embodiments of the present application are first explained below.

[0094] 1. Sidelink communication In a wireless communication system, data communication between UEs may be performed using a network, or may be performed directly between UEs without using a network. Similar to the Uu interface between a UE and a base station, the interface between UEs is called a PC5 interface. The link between UEs is called a sidelink. A typical application scenario for sidelink communication is vehicle-to-everything (V2X). In vehicle-to-everything, each vehicle is a UE, and data transmission may be performed directly between UEs via the sidelink without going through a network. In this way, communication latency can be effectively reduced. It should be understood that the sidelink may also be called a sidelink, sidelink, sidelink, or the like.

[0095] 2. Broadcast, unicast, and multicast in sidelink The broadcast communication in the sidelink is similar to the broadcasting of system information by the base station. Specifically, the UE transmits the broadcast service data to the outside without encryption, and any other UEs within the effective reception range that are interested in the broadcast service can receive the broadcast service data.

[0096] Unicast communication in sidelink is similar to data communication performed after a radio resource control (RRC) connection is set up between a UE and a base station, and a unicast connection must first be set up between two UEs. After the unicast connection is set up, the two UEs can perform data communication based on the agreed-upon identifiers, and the data may be encrypted or unencrypted.

[0097] Multicast communication in sidelink means communication between all UEs in a communication group, and any UE in the group can send or receive data for the multicast service.

[0098] The embodiments of this application mainly focus on unicast communication in the sidelink. One unicast communication in the sidelink corresponds to a pair: a source layer-2 identifier (source L2 ID) and a destination layer-2 identifier (destination L2 ID). The subheader of each media access control layer data protocol unit (MAC PDU) in the sidelink usually includes the source L2 ID and the destination L2 ID, so that the sender can send data to the correct receiver.

[0099] 3. Radio Bearer (RB) A radio bearer is a collective term for a set of protocol entities and configurations allocated to a UE by a base station. This includes a packet data convergence protocol (PDCP) entity, a radio link control (RLC) protocol entity, a medium access control (MAC) protocol entity, and a set of resources allocated by the physical layer (PHY). Radio bearers include data radio bearers (DRBs) and signaling radio bearers (SRBs). The former are used to carry data, and the latter are used to carry signaling messages. In sidelink communication scenarios, communication between UEs is carried out via sidelink radio bearers (SLRBs), which include sidelink DRBs and sidelink SRBs. In protocol text, radio bearer configuration generally includes only the configurations of the PDCP layer and the service data adaptation protocol (SDAP) layer. The protocol entities below the RLC layer are called RLC bearers and the corresponding configuration is provided in RLC bearer configuration.

[0100] 4. RLC bearer An RLC bearer is a protocol entity and structure below the RLC layer. It is a lower-layer part of a radio bearer and includes a set of resources such as RLC protocol entities and logical channels. One RLC bearer is associated with one logical channel. Generally, one RLC bearer is associated with one PDCP entity, i.e., one RLC serves one radio bearer (RB).

[0101] 5. Discovery Procedure A UE supporting proximity services uses a discovery procedure to search for nearby UEs and sets up a unicast connection to the nearby UE for subsequent sidelink communication. The discovery protocol layer of the UE generates a discovery message, delivers the discovery message to the PDCP layer, and transmits the discovery message to peer UEs via lower layers.

[0102] The discovery procedure has two models, Model A and Model B. In Model A, UEs may include announcing UEs and monitoring UEs. Announcing UEs broadcast discovery messages, also called announcement messages. The announcement messages may carry specific information about the announcing UE, such as a relay service code (RSC) indicating the service types that can be provided. The relay service code is used by surrounding UEs to determine whether the service types that can be provided by the announcing UE are required. After monitoring and receiving the announcement message, nearby monitoring UEs determine whether to use the announcing UE as a peer UE for sidelink communication based on the content carried in the announcement message. In Model B, UEs may include a discoverer UE and a discoveree UE. The discoverer UE broadcasts a discovery message, which is also called a solicitation message, and the solicitation message carries information about the service type that the discoverer UE is interested in. After monitoring and receiving the solicitation message, if the discoveree UE finds that the discoveree UE meets the service requirements of the discoverer UE, the discoveree UE responds to the discoverer UE with another discovery message, which is also called a response message.

[0103] Similar to sidelink communication, the discovery message carries a source L2 ID and a destination L2 ID used by the UE to send or receive the discovery message. The source L2 ID is assigned by the sending UE, and the destination L2 ID is a pre-set or pre-configured default destination L2 ID.

[0104] 6. Setting up a unicast connection After the discovery procedure, a unicast connection is set up between UEs using a unicast connection setup procedure. The UE that initiates the unicast connection setup procedure is called the initiating UE, and the peer UE of the initiating UE is called the target UE. After the discovery procedure, the initiating UE sends a unicast connection setup request (direct communication request, DCR) message to the target UE. This message carries the initiating UE's L2 ID, the target UE's L2 ID, and user information. The user information includes information about the upper application layer. After receiving the unicast connection setup request message, the target UE determines whether it can accept the unicast connection setup request based on the user information in the unicast connection setup request message. If the unicast connection setup request can be accepted, a direct communication accept (DCA) message is returned to the initiating UE. If the unicast connection setup request cannot be accepted, a direct communication reject (DCR) message is returned to the initiating UE.

[0105] In the above model A, the monitoring UE can actively initiate the unicast connection setup process after finding a suitable peer UE. In the above model B, the discoverer UE can initiate the unicast setup procedure after receiving a response message from a suitable discoveree UE.

[0106] 7. Sidelink UE-to-Network Relay (also called sidelink UE-to-Network Relay, SL UE-to-Network Relay, or SL U2N Relay) SL U2N Relay is a technology in which one UE helps another UE communicate with a base station, and is also called relay technology. Figure 2 shows the communication architecture of SL U2N Relay. A remote UE communicates with a base station through the cooperation of a relay UE. The remote UE communicates with the relay UE via a sidelink, and the corresponding interface is called PC5. The relay UE and the base station are directly connected to each other, i.e., they communicate with each other through the Uu interface.

[0107] Embodiments of the present application may be applied to a Layer 2 (L2) scenario of SL U2N Relay, hereinafter referred to as L2 SL U2N Relay for short. FIG. 3 is a protocol stack diagram of L2SL U2N Relay. Data packets of a Remote UE are relayed and forwarded under the PDCP layer of a Relay UE. Specifically, the Relay UE maintains only the RLC bearer of the relay, including an RLC layer, a MAC layer, and a PHY layer. Therefore, there are an end-to-end PDCP layer, an end-to-end SDAP layer, and an end-to-end RRC layer between the Remote UE and the base station, but there are no end-to-end RLC layer, an end-to-end MAC layer, or an end-to-end PHY layer between the Remote UE and the base station.

[0108] In the protocol architecture, a sidelink relay adaptation protocol (SRAP) layer is added between the RLC layer and the PDCP layer. The SRAP layer is mainly used for radio bearer multiplexing and demultiplexing. In other words, multiplexing of different radio bearers onto one RLC bearer and the corresponding demultiplexing process are supported. The RLC bearer between the Remote UE and the Relay UE is called the PC5 Relay RLC channel / bearer, and the RLC bearer between the Relay UE and the base station is called the Uu Relay RLC channel / bearer. The base station performs SRAP configuration for the Remote UE and the Relay UE. The SRAP configuration may include a mapping relationship between the SRB ID / DRB ID of the Remote UE and the Uu Relay RLC channel / PC5 ​​Relay RLC channel, so that data from the Remote UE can be correctly relayed and forwarded via the Relay UE. Specifically, the base station configures a mapping relationship between the radio bearer (SRB or DRB) and the PC5 Relay RLC channel for the Remote UE, and configures a mapping relationship between the radio bearer of the Remote UE and the Uu / PC5 Relay RLC channel for the Relay UE. During the data transmission process (using uplink transmission as an example), after receiving a PDCP PDU from the PDCP layer, the SRAP layer of the Remote UE adds the ID information of the Remote UE and the ID information of the radio bearer (SRB or DRB) to the SRAP header. After receiving a data packet from the PC5 Relay RLC channel, the adaptation layer of the Relay UE can deliver the data packet to the correct Uu Relay RLC channel based on the mapping relationship configured by the base station. After receiving the data packet from the Uu Relay RLC channel, the base station delivers the data packet to the corresponding PDCP layer for processing based on the ID information of the Remote UE and the ID information of the radio bearer in the SRAP header.The data transmission process in the downlink direction is similar to that in the uplink direction, and the details will not be described again here. The ID information of the remote UE may be the local ID of the remote UE. The local ID is a UE identifier assigned to the remote UE by the base station. The local ID is used to transmit uplink and downlink data of the remote UE. The identifier is added to the SRAR header so that the relay UE and the base station can identify the remote UE to which the data packet belongs.

[0109] 8. Multi-path Relay A "path" in the embodiments of the present application is a communication path or a communication link.

[0110] The 3rd Generation Partnership Project (3GPP (registered trademark, hereinafter referred to as "3GPP")) is researching a multi-path relay solution that evolves from SL U2N Relay. Figure 4 shows the communication architecture of multi-path relay. A remote UE communicates with a base station via both a direct link and an indirect link. The remote UE and relay UE are located within the cell coverage of the same base station. In a direct link, the remote UE communicates directly with the base station through the Uu interface. In an indirect link, the remote UE communicates with the base station via the relay UE. The remote UE can be connected to and communicate with the relay UE via a sidelink, or the remote UE can communicate with the relay UE via a non-3GPP link. To improve the throughput and reliability of data transmission and reception, the remote UE can simultaneously transmit and receive the same or different data over the two links.

[0111] FIG. 5 is a diagram of a protocol stack architecture for multi-path relay. (a) of FIG. 5 is a diagram of a protocol stack architecture based on L2 SL U2N relay. The remote UE and the relay UE are pre-connected via a sidelink. Therefore, based on the protocol stack architecture for L2 SL U2N relay, a protocol stack for direct communication between the remote UE and the base station is added to the architecture. (b) of FIG. 5 is a protocol stack architecture used when the remote UE and the relay UE are connected using a non-3GPP protocol. There is an adaptation layer between the remote UE and the relay UE and between the remote UE and the base station. However, an SRAP layer may or may not be present. The specific selection is made based on the bearer multiplexing requirements of the remote UE.

[0112] 6(a) is a schematic flowchart of a communication method according to an embodiment of the present application. The method is used to configure multiple routes between a remote UE and a base station for the remote UE. Before the multiple routes are configured, there is a direct route between the remote UE and the base station. In other words, the remote UE can communicate with the base station through the Uu air interface between the remote UE and the base station. Then, in view of this, a relay UE is configured for the remote UE, and the remote UE can communicate with the base station through the relay UE.

[0113] The method includes the following steps.

[0114] Step 601a: The base station sends an RRC reconfiguration message to the remote UE through an interface between the remote UE and the base station, and the remote UE correspondingly receives the RRC reconfiguration message through the interface.

[0115] It should be noted that in this embodiment of the present application, the RRC reconfiguration message may also be referred to as an RRC configuration message, an RRC message, a reconfiguration message, or a configuration message. The names of the messages are not limited in this embodiment of the present application and are collectively described here.

[0116] The RRC reconfiguration message includes information about the relay UE, such as the source L2 ID of the relay UE, the source address of the relay UE, etc.

[0117] Optionally, the RRC reconfiguration message may further include at least one of SRAP configuration information, end-to-end bearer configuration information between the remote UE and the base station, or PC5 relay RLC channel / bearer configuration information between the remote UE and the relay UE, where the SRAP configuration information includes a mapping relationship between the SRB ID / DRB ID of the remote UE and the PC5 relay RLC channel / bearer.

[0118] Step 602a: The remote UE sends indication information to the relay UE based on the information about the relay UE, where the indication information triggers the relay UE to enter an RRC connected state.

[0119] In one implementation, the remote UE does not detect the RRC status of the relay UE. When the remote UE receives an RRC reconfiguration message, it sends indication information to the relay UE. After the relay UE receives the indication information, if the relay UE is already in an RRC connected state, the relay UE ignores the indication information, or if the relay UE is in an RRC idle state (RRC_IDLE) or an RRC inactive state (RRC INACTIVE), the relay UE enters the RRC connected state from the RRC idle state or the RRC inactive state. Detection in this embodiment of the present application can be understood as determination, judgment, or check. The description is provided here collectively and will not be described in detail below.

[0120] In another implementation, the remote UE detects the RRC status of the relay UE. For example, the RRC reconfiguration message in the aforementioned step 601a includes status information, which indicates the RRC status of the relay UE. If the remote UE determines that the RRC status of the relay UE is in the RRC connected state, the relay UE does not send indication information to the relay UE. If the RRC status of the relay UE is in the RRC idle state or the RRC inactive state, the remote UE determines that the relay UE needs to be triggered to enter the RRC connected state, and the remote UE sends indication information to the relay UE. Therefore, when the relay UE receives the indication information, the relay UE enters the RRC connected state from the RRC idle state or the RRC inactive state based on the indication information.

[0121] In another implementation, the remote UE detects the RRC status of the relay UE, but sends the indication information to the relay UE after receiving the RRC reconfiguration message regardless of the RRC status of the relay UE. In other words, the RRC reconfiguration message triggers the remote UE to send the indication information to the relay UE, and the specific RRC status of the relay UE does not affect the sending of the indication information by the remote UE.

[0122] Step 603a: The relay UE in an RRC connected state sends sidelink UE information (SUI) to the base station, and the base station receives the SUI in response.

[0123] The SUI includes information about the remote UE and / or information about the relay UE.

[0124] The information about the relay UE may be the source L2 ID or source address of the relay UE, etc.

[0125] The information about the remote UE may be the destination L2 ID or destination address of the remote UE, etc.

[0126] It should be noted that step 603a is performed when the indication information triggers the relay UE to enter the RRC connected state from the RRC idle state or the RRC inactive state. If the relay UE is already in the RRC connected state before receiving the indication information, the relay UE may have first reported information about itself to the base station. Therefore, step 603a may be performed or may be omitted (i.e., step 603a is not performed).

[0127] Step 604a: After receiving the SUI from the relay UE, the base station sends an RRC reconfiguration message to the relay UE, and in response, the relay UE receives the RRC reconfiguration message.

[0128] The RRC reconfiguration message includes at least one of SRAP configuration information, Uu relay RLC channel / bearer configuration information between the relay UE and the base station, or PC5 relay RLC channel / bearer configuration information between the remote UE and the relay UE. The SRAP configuration information includes a mapping relationship between the SRB ID / DRB ID of the remote UE and the PC5 relay RLC channel / bearer, and a mapping relationship between the SRB ID / DRB ID of the remote UE and the Uu relay RLC channel / bearer.

[0129] According to the above solution, a relay UE can be configured for the remote UE, and when the relay UE is in an RRC idle state or an RRC inactive state, the relay UE becomes active, so that the relay UE enters an RRC connected state, thereby ensuring that multiple paths between the remote UE and the base station are successfully configured for the remote UE, thereby improving the reliability of communication between the remote UE and the base station and improving service quality and user experience.

[0130] In one implementation, in a scenario in which multiple paths are configured for a remote UE, for example, during the procedure in which multiple paths are configured for the remote UE or after the multi-path configuration is completed, the base station can send notification information to the relay UE, which is used by the relay UE to determine whether control plane signaling for the remote UE needs to be forwarded. Based on the notification information, the relay UE determines whether the control plane signaling of the base station needs to be forwarded for the remote UE or whether the control plane signaling sent by the base station does not need to be forwarded for the remote UE. The control plane signaling may be a system message, a paging message, etc. It should be understood that multiple paths may be configured for the remote UE in the manner shown in FIG. 6(a) or in another manner. This is not limited to this embodiment of the present application. In other words, the procedure in which the base station sends notification information to the relay UE may be independent of or combined with the procedure shown in FIG. 6(a).

[0131] If the solution in which the base station sends notification information to the relay UE is implemented in combination with the embodiment of Figure 6(a), the notification information may be carried within the RRC reconfiguration message of step 604a, or the notification information may be sent using another independent message (e.g., RRC signaling or MAC CE signaling).

[0132] In a specific implementation, the notification information may indicate that the type of relay service provided by the relay UE is a 3GPP R17 relay service or a 3GPP R18 relay service. If the notification information indicates that the type of relay service provided by the relay UE is a 3GPP R17 relay service, the relay UE is configured to provide SL U2N Relay for the remote UE. If the notification information indicates that the type of relay service provided by the relay UE is a 3GPP R18 relay service, the relay UE is configured to provide multi-path Relay, i.e., to provide a multi-path relay service, for the remote UE.

[0133] In yet another specific implementation, the notification information indicates that the relay UE needs to forward the base station's control plane signaling for the remote UE, or that the relay UE does not need to forward the base station's control plane signaling for the remote UE.

[0134] For example, if the notification information indicates that the relay service type is a 3GPP R17 relay service or that the relay UE needs to forward control plane signaling for the remote UE, the relay UE can determine based on the notification information that the remote UE can only communicate with the base station via an indirect link, or that the remote UE and the base station cannot directly receive or transmit control plane signaling. Therefore, the remote UE cannot directly receive control plane signaling from the base station, and the relay UE forwards control plane signaling for the remote UE. For example, the relay UE forwards a system message to the remote UE. Alternatively, the relay UE calculates a paging slot for the remote UE and monitors the paging slot for the remote UE for a paging message. If the relay UE monitors a paging message that needs to be sent by the base station to the remote UE, the relay UE transmits the paging message to the remote UE based on the identification information of the remote UE in the paging message. This method can improve communication reliability for the remote UE.

[0135] As another example, if the notification information indicates that the relay service type provided by the relay UE is a 3GPP R18 relay service or indicates that control plane signaling does not need to be forwarded for the remote UE, the relay UE determines, based on the notification information, that the remote UE can communicate with the base station via an indirect link or via a direct link. Thus, the remote UE can directly receive control plane signaling from the base station. Thus, the relay UE does not need to forward control plane signaling transmitted by the base station to the remote UE for the remote UE, and the remote UE directly receives control plane signaling from the base station. This method can reduce the signaling overhead of the relay UE.

[0136] Optionally, the base station may send notification information to the relay UE when the relay UE does not need to provide relay-forwarding of control plane signaling, so if the relay UE does not receive the notification information sent by the base station, it is assumed by default that the relay UE needs to provide relay-forwarding service of control plane for the remote UE.

[0137] Optionally, the base station may send notification information to the relay UE when the relay UE needs to provide relay-forwarding of control plane signaling. Therefore, if the relay UE does not receive the notification information sent by the base station, it is considered by default that the relay UE does not need to provide relay-forwarding service of control plane for the remote UE.

[0138] In the following, with reference to the embodiment of FIG. 6(a), several different implementations of the indication information and corresponding procedures in the corresponding implementations will be described.

[0139] Method 1: The indication information is an RRC reconfiguration complete message, in other words, the indication information is carried within the RRC reconfiguration complete message.

[0140] It should be noted that in this embodiment of the present application, the RRC reconfiguration complete message is a response to the RRC reconfiguration message and indicates that the RRC reconfiguration is complete. The RRC reconfiguration complete message may also be referred to as an RRC configuration complete message, an RRC completion message, a reconfiguration complete message, a configuration complete message, a completion message, a response message, etc. The names of the messages are not limited in this embodiment of the present application and are collectively described here.

[0141] Fig. 6(b) is a schematic flowchart of a communication method according to an embodiment of the present application. This method is obtained by extension based on the embodiment of Fig. 6(a), and the embodiment of Fig. 6(b) is a specific implementation of the embodiment of Fig. 6(a). The indication information in Fig. 6(a) is specifically the RRC reconfiguration complete message in Fig. 6(b).

[0142] The remote UE can determine a manner of sending an RRC reconfiguration complete message based on the RRC status of the relay UE. The manner of sending the RRC reconfiguration complete message can be as follows: the remote UE sends the RRC reconfiguration complete message to the base station through the interface between the remote UE and the base station, or the remote UE sends the RRC reconfiguration complete message to the base station via the relay UE. Specifically, the remote UE sends the RRC reconfiguration complete message to the relay UE, and then the relay UE forwards the RRC reconfiguration complete message to the base station.

[0143] For example, if the remote UE detects that the RRC status of the relay UE is in the RRC idle state or the RRC inactive state, the remote UE determines that the relay UE needs to be triggered to enter the RRC connected state, and the relay UE needs to be triggered to enter the RRC connected state through an RRC reconfiguration complete message. In other words, the remote UE sends an RRC reconfiguration complete message to the relay UE, and the relay UE forwards the RRC reconfiguration complete message to the base station. The RRC reconfiguration complete message can trigger the relay UE to enter the RRC connected state. If the remote UE detects that the RRC status of the relay UE is in the RRC connected state, the remote UE can respond with an RRC reconfiguration complete message via a direct link between the remote UE and the base station, or the remote UE can send an RRC reconfiguration complete message to the relay UE, and the relay UE then sends the RRC reconfiguration complete message to the base station.

[0144] In another example, the remote UE does not detect the RRC status of the relay UE and directly sends an RRC reconfiguration complete message to the relay UE. After the relay UE receives the RRC reconfiguration complete message, if the relay UE is currently in an RRC idle state or an RRC inactive state, the relay UE needs to enter an RRC connected state. Then, the relay UE forwards the RRC reconfiguration complete message to the base station (i.e., step b). The order of step b and step 603a is not limited.

[0145] Optionally, if a unicast connection has not been set up between the remote UE and the relay UE before step 602a, the remote UE first sets up a unicast connection to the relay UE (i.e., step a). For example, the remote UE sends a unicast connection setup request message to the relay UE to request that a unicast connection be set up.

[0146] Method 2: Indication information is carried in a request message, where the request message is for requesting to set up a unicast connection, and the indication information indicates that the unicast connection is set up to obtain relay service for the relay UE. The request message may be a unicast connection setup request message or a unicast connection setup response message.

[0147] Figure 6(c) is a schematic flowchart of a communication method according to an embodiment of the present application. The method is obtained by an extension based on the embodiment of Figure 6(a), and the embodiment of Figure 6(c) is a specific implementation of the embodiment of Figure 6(a). The indication information of Figure 6(a) is sent to the relay UE using the unicast connection setup procedure of Figure 6(c). Specifically, the indication information is carried in a request message for requesting to set up a unicast connection, and the indication information indicates that the unicast connection is to be set up to obtain relay service for the relay UE.

[0148] Specifically, no unicast connection has been set up between the remote UE and the relay UE. Therefore, after step 601a, the remote UE sends the aforementioned request message to the relay UE, and the request message carries indication information (i.e., step 602a).

[0149] In one implementation, when the remote UE detects that the RRC status of the relay UE is in the RRC idle state or the RRC inactive state, the remote UE determines that the relay UE needs to be triggered to enter the RRC connected state, and then includes indication information in the request message to trigger the relay UE to enter the RRC connected state. After receiving the request message, the relay UE sets up a unicast connection to the remote UE. In addition, the relay UE enters the RRC connected state based on the indication information.

[0150] In another implementation, the relay UE does not detect the RRC status of the relay UE and directly includes the indication information in the request message. After receiving the request message, the relay UE sets up a unicast connection to the remote UE. In addition, if the relay UE is currently in RRC idle state or RRC inactive state, the relay UE also needs to enter RRC connected state.

[0151] It should be noted that the indication information in the request message may be explicit indication information, for example, binary indication information or enumerated indication information. The indication information explicitly indicates that a unicast connection is to be set up to obtain the relay service of the relay UE. Alternatively, the indication information may be implicit indication information. For example, the indication information may be a relay service code or user information of the relay UE, which implicitly indicates that a unicast connection is to be set up to obtain the relay service of the relay UE.

[0152] In the above implementation, the relay UE is triggered to enter the RRC connected state through the indication information carried in the request message.

[0153] In yet another implementation, the relay UE may instead be triggered to enter the RRC connected state through indication information corresponding to the request message, i.e., the indication information is not carried in the request message. For example, the indication information is a special L2 ID corresponding to the request message, the service type corresponding to the special L2 ID is a relay service type, and the special L2 ID is a special L2 ID of the relay UE or a special L2 ID used by the remote UE to set up multi-path relay. If the special L2 ID is the special L2 ID of the relay UE, the special L2 ID is a destination L2 ID corresponding to the request message sent by the remote UE. In addition, the special L2 ID may be a source L2 ID corresponding to the discovery message sent by the relay UE. If the special L2 ID is the special L2 ID of the remote UE, the special L2 ID is a source L2 ID corresponding to the request message sent by the remote UE. If the relay UE determines that the L2 ID corresponding to the request message is the special L2 ID, the relay UE determines that it needs to provide relay service for the remote UE based on the special L2 ID and knows that the relay UE needs to enter the RRC connected state. If the relay UE determines that the L2 ID corresponding to the request message is a general L2 ID other than a special L2 ID and that the service type corresponding to the general L2 ID is a device-to-device (D2D) service type, the relay UE determines that it needs to provide a D2D communication service for the remote UE based on the general L2 ID.

[0154] In the embodiment of Figure 6(c), the remote UE may further send an RRC reconfiguration complete message to the base station through the interface between the remote UE and the base station (i.e., step c) to notify the base station that the reconfiguration of the remote UE is completed. The order of step 602a and step c in Figure 6(c) is not limited.

[0155] Alternatively, in the embodiment of FIG. 6(c), the remote UE may forward the RRC reconfiguration complete message via the relay UE.

[0156] For Method 2, in a specific implementation, to trigger the relay UE to enter the RRC connected state, the indication information in the request message may indicate that a unicast connection is to be set up to obtain relay service for the relay UE.

[0157] Alternatively, the request message may not carry the aforementioned indication information, and the request message indicates that a unicast connection is to be set up to obtain relay service for the relay UE. In this case, the request message can be understood as indication information. Therefore, the request message is for requesting to set up a unicast connection and also triggers the relay UE to enter the RRC connected state.

[0158] Method 3: The indication information is PC5-S signaling, a PC5 RRC message, or a sidelink medium access control element (SL MAC CE) signaling.

[0159] Fig. 6(d) is a schematic flowchart of a communication method according to an embodiment of the present application. The method is obtained by an extension based on the embodiment of Fig. 6(a), and the embodiment of Fig. 6(d) is a specific implementation of the embodiment of Fig. 6(a). The indication information in Fig. 6(d) is not carried in a unicast connection setup request message or a unicast connection setup response message, and the indication information is not an RRC reconfiguration complete message but a unicast message or signaling.

[0160] In the embodiment of Figure 6(d), the remote UE may further need to send an RRC reconfiguration complete message to the base station through the interface between the remote UE and the base station (i.e., step e) to notify the base station that the reconfiguration of the remote UE is complete. The order of step 602a and step e in Figure 6(d) is not limited. Alternatively, in the embodiment of Figure 6(d), the remote UE may forward the RRC reconfiguration complete message via a relay UE.

[0161] Optionally, in the embodiment of Figure 6(e), if a unicast connection has not been set up between the remote UE and the relay UE before step 602a, the remote UE first sets up a unicast connection to the relay UE (i.e., step d). Specifically, the remote UE sends a unicast connection setup request message or a unicast connection setup response message to the relay UE to request the unicast connection to be set up.

[0162] In the above, several different implementations are presented for triggering the relay UE to enter the RRC connected state by the remote UE. Of course, in practical applications, the implementation is not limited to the above methods, and other methods may be used instead.

[0163] 6(e) is a schematic flowchart of a communication method according to an embodiment of the present application. In this method, after step 601a, the remote UE determines the RRC status of the relay UE (i.e., step f). For example, the remote UE includes indication information indicating the RRC status of the relay UE in the RRC reconfiguration message of step 601a, or the remote UE receives a discovery message of the relay UE, which carries the RRC status of the relay UE. In case 1, the RRC status of the relay UE is RRC connected. Therefore, the base station can know information about the relay UE, and the relay UE does not need to report sidelink UE information to the base station. Therefore, only steps g and h need to be performed. Specifically, the remote UE sends an RRC reconfiguration complete message to the base station through the interface between the remote UE and the base station, and the base station sends an RRC reconfiguration message to the relay UE. For the content carried in the RRC reconfiguration message, please refer to the description of step 604a. Optionally, in case 1, if a unicast connection has not been set up between the relay UE and the remote UE, the remote UE needs to further set up a unicast connection to the relay UE. In case 2, if the RRC status of the relay UE is in an RRC idle state or an RRC inactive state, steps 602a, 603a, and 604a need to be performed. For details, please refer to the embodiment of FIG. 6(a). In other words, case 2 is a specific implementation of the embodiment of FIG. 6(a). For different implementations of the indication information in case 2, please refer to the aforementioned embodiments of FIG. 6(b), FIG. 6(c), and FIG. 6(d). The details will not be described again.

[0164] Please note that for steps 601a, 602a, 603a, and 604a in Figures 6(b), 6(c), 6(d), and 6(e), reference may be made to the corresponding descriptions of the embodiment in Figure 6(a).

[0165] In one implementation, in the process of configuring multiple paths for a remote UE, if a link or connection failure occurs between the remote UE and a relay UE, or if a link or connection failure occurs between the remote UE and a base station, or if a link or connection failure occurs between the base station and a relay UE, the remote UE needs to report the link or connection failure to the base station. The following describes various types of link or connection failures that may occur and corresponding reporting modes.

[0166] In one implementation, when the remote UE determines that a link failure or connection failure has occurred between the remote UE and the relay UE, the remote UE sends first failure indication information to the base station, where the first failure indication information indicates that a link failure or connection failure has occurred between the remote UE and the relay UE. The link failure may be a PC5 RLF, and the connection failure may be a Bluetooth connection failure, a WiFi connection failure, etc. RLF means radio link failure.

[0167] In another implementation, when the remote UE determines that a link failure or connection failure has occurred between the remote UE and the base station, the remote UE sends second failure indication information to the base station via the relay UE, where the second failure indication information indicates that a link failure or connection failure has occurred between the remote UE and the base station. The link failure may be a Uu RLF, and the connection failure may be a non-3GPP connection failure, etc.

[0168] In another implementation, when the relay UE determines that a link failure or connection failure has occurred between the relay UE and the base station, the relay UE sends third failure indication information to the remote UE, where the third failure indication information indicates that a link failure or connection failure has occurred between the relay UE and the base station. Then, the remote UE sends fourth failure indication information to the base station, where the fourth failure indication information indicates that a link failure or connection failure has occurred between the relay UE and the base station. The link failure may be a Uu RLF, and the connection failure may be a non-3GPP connection failure, etc.

[0169] If a link or connection failure occurs between the remote UE and the relay UE, or if a link or connection failure occurs between the relay UE and the base station, the remote UE or the base station can reselect a relay UE and then reconfigure multiple paths for the remote UE using the newly selected relay UE. If a link or connection failure occurs between the remote UE and the base station, the remote UE can perform an RRC re-setup procedure and perform multi-path configuration for the remote UE during the procedure.

[0170] It should be noted that the aforementioned reporting solutions described above after a link or connection failure may be implemented in combination with the embodiments of Figure 6(a), Figure 6(b), Figure 6(c), Figure 6(d), or Figure 6(e), or may be implemented separately, and this is not a limitation of the present application.

[0171] 6(f) is a schematic flowchart of another communication method according to an embodiment of the present application, in which the multipath configuration of the remote UE is completed during the RRC re-setup procedure of the remote UE. The method includes the following steps:

[0172] Step 601f: The remote UE selects a relay UE.

[0173] In one implementation, the remote UE selects a UE from the cell in which the remote UE is located as a relay UE. The relay UE may be the UE with the highest reference signal received power in the cell, or any UE in the cell. The remote UE can obtain the reference signal received power of UEs in the cell through the discovery procedure described above.

[0174] Step 602f: The remote UE sends an RRC re-setup request message to the base station, and in response, the base station receives the RRC re-setup request message.

[0175] Step 603f: The remote UE sets up a unicast connection to the relay UE.

[0176] Step 603f is an optional step. If the remote UE has already set up a unicast connection to the relay UE, step 603f does not need to be performed. If a unicast connection has not been set up between the remote UE and the relay UE, step 603f needs to be performed.

[0177] The order of steps 602f and 603f is not limited.

[0178] Step 604f: The relay UE sends the SUI to the base station, and the base station receives the SUI in response.

[0179] The SUI includes information about the remote UE, or includes information about the relay UE and information about the remote UE.

[0180] Step 605f: The base station sends an RRC re-setup message to the remote UE, and in response, the remote UE receives the RRC re-setup message.

[0181] Step 606f: The remote UE sends an RRC re-setup complete message to the base station, and in response, the base station receives the RRC re-setup complete message.

[0182] The RRC re-setup complete message includes information about the relay UE, or includes information about the relay UE and information about the remote UE.

[0183] The information about the relay UE may include a destination L2 ID of the relay UE, and the information about the remote UE may include a source L2 ID of the remote UE.

[0184] The base station determines that the remote UE selects a relay UE to set up a multipath connection for the remote UE based on the content of the RRC re-setup complete message and the content of the SUI in step 604f. Specifically, the base station determines that both the relay UE and the remote UE support the setup of a multipath connection for the remote UE by the relay UE based on the content of the SUI reported by the relay UE and the content of the RRC re-setup complete message reported by the remote UE. For example, the SUI in step 604f includes information about the relay UE and the remote UE, and the RRC re-setup complete message in step 606f includes information about the relay UE and the remote UE. As another example, the SUI in step 604f includes information about the relay UE and the remote UE, and the RRC re-setup complete message in step 606f includes information about the relay UE. As another example, the SUI in step 604f includes information about the remote UE, and the RRC re-setup complete message in step 606f includes information about the relay UE and the remote UE. As another example, the SUI in step 604f includes information about the remote UE, and the RRC re-setup complete message in step 606f includes information about the relay UE.

[0185] After that, the base station further needs to send RRC reconfiguration messages to the remote UE and the relay UE separately to accomplish RRC configuration of the relay UE and the remote UE. For the content of the RRC reconfiguration message, please refer to the description of the embodiment in Figure 6(a).

[0186] In the above solution, in order to facilitate the remote UE to quickly implement multi-path configuration, after the remote UE's reset procedure is completed, the base station can configure multiple paths for the remote UE based on information about the relay UE selected by the remote UE.

[0187] The aforementioned embodiments will be described below with reference to specific examples: the embodiment of Fig. 7 is a specific example of the embodiment of Fig. 6(a) or Fig. 6(e), and the embodiment of Fig. 9 is a specific example of the embodiment of Fig. 6(f).

[0188] 7 is a schematic flowchart of a communication method according to an embodiment of the present application. The method includes the following steps:

[0189] Step 701: A remote UE searches for available UEs around it using a discovery procedure.

[0190] A remote UE can search for available UEs around it using the method of the aforementioned Model A or the method of the aforementioned Model B. An available UE is a UE that can provide relay services to the remote UE.

[0191] Step 702a: The base station sends measurement configuration information to the remote UE.

[0192] Step 702b: The remote UE performs measurement based on the measurement configuration information to obtain the measurement result, and sends the measurement result to the base station.

[0193] The measurement results include source L2 IDs of one or more UEs, RSRPs of one or more UEs, and identifiers of serving cells of one or more UEs.

[0194] Note that step 701 may alternatively be performed after step 702a. Thus, the remote UE can simultaneously discover and measure UEs in its surroundings. For example, the remote UE can receive discovery messages from surrounding UEs and measure the discovery messages to obtain the signal quality of the UEs.

[0195] Step 703: The base station determines, based on the measurement result, to configure multiple routes for the remote UE, and selects, for the remote UE, a relay UE configured to set up an indirect link.

[0196] For the implementation of selecting relay UEs by the base station, please refer to the description of the embodiment in FIG. 6(a).

[0197] Step 704: The base station sends an RRC reconfiguration message to the remote UE.

[0198] For the contents of the RRC reconfiguration message, see the description of step 601a.

[0199] Step 705: The remote UE sets up a unicast connection to the relay UE.

[0200] After step 705, the following steps 706a to 708a and step 709 are executed, or the following steps 706b to 708b and step 709 are executed. In other words, either steps 706a to 708a or steps 706b to 708b are executed. The following steps 706a to 708a are called method 1, and the following steps 706b to 708b are called method 2.

[0201] In one implementation, a manner of presetting or preconfiguring for the remote UE allows the remote UE and the relay UE to perform either method 1 or method 2. In another implementation, the remote UE may decide to perform method 1 or method 2 instead.

[0202] In addition, it should be noted that in Method 1, if the remote UE can know that the RRC status of the relay UE is in the RRC connected state, the remote UE can send an RRC reconfiguration complete message to the base station through the interface between the remote UE and the base station, and there is no need to trigger the relay UE to enter the RRC connected state, i.e., only step 706a needs to be performed, and step 707a and step 708a do not need to be performed.

[0203] Step 706a: The remote UE sends an RRC reconfiguration complete message to the base station via the Uu link.

[0204] The RRC reconfiguration complete message indicates that the remote UE successfully receives the multipath configuration information, which is information included in the RRC reconfiguration message.

[0205] Step 707a: The remote UE sends indication information to the relay UE, which triggers the relay UE to enter an RRC connected state.

[0206] For the implementation of using the indication information to trigger the relay UE to enter the RRC connected state, please refer to the description of the previous embodiment in Figures 6(a) to 6(e).

[0207] Step 708a: The relay UE is triggered to enter an RRC connected state and send Sidelink UE information (SUI) to the base station.

[0208] The SUI includes one or more of the source L2 ID of the relay UE, the destination L2 ID of the remote UE, or instruction information, which is for requesting the base station to assign a local ID to the remote UE.

[0209] Step 706b: The remote UE sends an RRC reconfiguration complete message to the relay UE.

[0210] For the implementation of the RRC reconfiguration complete message, please refer to the description of the previous embodiment of Figures 6(a) to 6(e).

[0211] Step 707b: The relay UE is triggered to enter an RRC connected state and sends an SUI to the base station.

[0212] The SUI includes a source L2 ID of the relay UE, a destination L2 ID of the remote UE, and instruction information, which requests the base station to assign a local ID to the remote UE.

[0213] Step 708b: The relay UE forwards the RRC reconfiguration complete message from the remote UE to the base station.

[0214] In the above method, when configuring multiple paths for a remote UE, the base station can define Method 1 (including steps 706a to 708a) to trigger the relay UE to enter an RRC connected state. In this case, an SRB bearer is configured in the Uu link between the remote UE and the base station. In another possible implementation, the case in which the base station configures the SRB is not limited. Therefore, there are three possible cases:

[0215] Case 1: The base station configures an SRB only in the direct link. In this case, using Method 1 (including steps 706a to 708a), the remote UE responds with an RRC reconfiguration complete message to trigger the relay UE to enter the RRC connected state.

[0216] Case 2: The base station configures SRB split / duplication, i.e., the same SRB message can be communicated over both the direct link and the indirect link. In this case, the remote UE can respond with an RRC reconfiguration complete message using Method 1 (including steps 706a to 708a) and / or Method 2 (including steps 706b to 708b). The selection of the specific method may be left to the UE for implementation.

[0217] If the remote UE responds with an RRC reconfiguration complete message on both the direct link and the indirect link, the relay UE may not be triggered to enter the RRC connected state using step 707a above, and the relay UE is triggered to enter the RRC connected state using the RRC reconfiguration complete message.

[0218] Case 3: The base station configures an SRB only on the indirect link. In this case, using Method 2 (including steps 706b to 708b), the remote UE responds with an RRC reconfiguration complete message to trigger the relay UE to enter the RRC connected state.

[0219] The description of the three cases also applies to the previously described embodiment of Figures 6(a) to 6(e), and the details will not be described again.

[0220] Step 709: The base station sends an RRC reconfiguration message to the relay UE.

[0221] For the implementation of the RRC reconfiguration message, please refer to the description of step 604a in FIG. 6(a).

[0222] In order to promote the improvement of the communication quality of the remote UE, in the above solution, in order to ensure that multiple paths are successfully configured for the remote UE, when the relay UE selected by the base station for the remote UE is in an RRC idle state or an RRC inactive state, the remote UE can respond to the base station with an RRC reconfiguration complete message via the Uu link between the remote UE and the base station, and the remote UE further triggers the relay UE to enter an RRC connected state.

[0223] In one implementation, during the procedure in which the base station configures multiple paths for the remote UE or after the multi-path configuration is completed, the base station can send notification information to the relay UE, where the notification information is for the relay UE to determine whether it needs to forward control plane signaling for the remote UE. The relay UE can determine whether it needs to forward control plane signaling for the remote UE based on the notification information. For a detailed description of the notification information, please refer to the relevant description of the embodiment in FIG. 6(a). The details will not be described again.

[0224] In one implementation, if the solution in which the base station sends notification information to the relay UE is combined with the embodiment of Figure 7, the RRC reconfiguration message of step 709 may include the notification information, or the notification information may be sent using a separate message between the base station and the relay UE.

[0225] In the above process of configuring multiple routes for the remote UE, a link failure or connection failure may occur. If a link failure or connection failure occurs, corresponding processing must be performed to ensure that multiple routes are successfully configured for the remote UE. The following provides an explanation of various cases.

[0226] Example 1: In the process of a remote UE setting up a unicast connection to a relay UE, or after the unicast connection has been set up, the remote UE detects that a PC5 RLF has occurred between the remote UE and the relay UE.

[0227] FIG. 8(a) illustrates a PC5 RLF occurring between a remote UE and a relay UE. A PC5 RLF occurs between the remote UE and the relay UE, resulting in the remote UE being unable to use the relay service of the relay UE. In this case, if an SRB bearer is configured in the direct link between the remote UE and the base station when the remote UE detects the occurrence of a PC5 RLF between the remote UE and the relay UE, the remote UE can send indication information to the base station via the SRB bearer, indicating that a PC5 RLF has occurred between the remote UE and the relay UE, to trigger relay UE reselection and perform multipath configuration for the remote UE. For specific procedures, see the embodiment of FIG. 7. Alternatively, multipath configuration for the remote UE may be performed based on another method. If an SRB bearer is not configured in the direct link between the remote UE and the base station, the remote UE cannot notify the base station that a PC5 RLF has occurred between the remote UE and the relay UE. Therefore, the remote UE can trigger a re-setup procedure and perform multipath configuration for the remote UE during the re-setup procedure. For a description of the re-setup procedure, see the embodiment of FIG. 9.

[0228] Example 2: When the remote UE responds to the base station with an RRC reconfiguration complete message via a direct link, the remote UE cannot respond to the base station with an RRC reconfiguration complete message, i.e., a link failure occurs between the remote UE and the base station due to poor link quality between the remote UE and the relay UE.

[0229] Figure 8(b) illustrates a link failure occurring between a remote UE and a relay UE. In this case, when a remote UE detects that a link failure has occurred between the remote UE and the relay UE, if an SRB bearer is configured in the indirect link between the remote UE and the base station, the remote UE can send an indication to the base station via the SRB bearer, indicating that a link failure has occurred between the remote UE and the relay UE, to trigger the base station to perform a re-setup of the connection to the remote UE. If an SRB bearer is not configured in the indirect link between the remote UE and the base station, the remote UE cannot notify the base station via the indirect link that a link failure has occurred between the remote UE and the relay UE. Therefore, the remote UE can trigger a re-setup procedure and perform multipath configuration for the remote UE during the re-setup procedure. For a description of the re-setup procedure, please refer to the embodiment of Figure 9.

[0230] Example 3: Uu RLF occurs between a relay UE and a base station.

[0231] FIG. 8(c) illustrates a Uu RLF occurring between a relay UE and a base station. After the relay UE establishes a radio connection to the base station, the Uu RLF occurs again, resulting in the remote UE being unable to use the relay service of the relay UE. In this case, upon detecting the Uu RLF between the relay UE and the base station, the relay UE sends an indication to the remote UE, indicating that a Uu RLF has occurred between the relay UE and the base station. After the remote UE receives the indication, if an SRB bearer is configured in the direct link between the remote UE and the base station, the remote UE can send an indication to the base station via the SRB bearer, indicating that a Uu RLF has occurred between the relay UE and the base station, to trigger relay UE reselection and perform multipath configuration for the remote UE. For specific procedures, see the embodiment of FIG. 7. Alternatively, multipath configuration for the remote UE may be performed based on another method. If an SRB bearer is not configured in the direct link between the remote UE and the base station, the remote UE cannot notify the base station that a Uu RLF has occurred between the relay UE and the base station. Therefore, the remote UE can trigger a re-setup procedure and perform multipath configuration for the remote UE in the re-setup procedure. For a description of the re-setup procedure, please refer to the embodiment of Figure 9.

[0232] Optionally, after receiving indication information from the relay UE indicating that a Uu RLF has occurred between the relay UE and the base station, the remote UE may release the unicast connection to the relay UE.

[0233] Case 4: An RRC setup failure occurs between the relay UE and the base station.

[0234] 8(d) and 8(e) illustrate an RRC setup failure occurring between a relay UE and a base station. The RRC setup failure occurs during the process in which the relay UE sets up a radio connection to the base station, resulting in the remote UE being unable to use the relay service of the relay UE. In this case, when the relay UE detects an RRC setup failure between the relay UE and the base station, it sends an indication to the remote UE, indicating that an RRC setup failure has occurred between the relay UE and the base station. This indication may be a PC5 RRC message. After the remote UE receives the indication, if an SRB bearer is configured on the direct link between the remote UE and the base station, the remote UE can send an indication to the base station via the SRB bearer, indicating that an RRC setup failure has occurred between the relay UE and the base station, to trigger relay UE reselection and perform multipath configuration for the remote UE. For specific procedures, please refer to the embodiment of FIG. 7. Alternatively, multipath configuration for the remote UE may be performed based on another method. If an SRB bearer is not configured in the direct link between the remote UE and the base station, the remote UE cannot notify the base station that an RRC setup failure has occurred between the relay UE and the base station. Therefore, the remote UE can trigger a re-setup procedure and perform multipath configuration for the remote UE during the re-setup procedure. For a description of the re-setup procedure, please refer to the embodiment of Figure 9.

[0235] Optionally, after receiving indication information from the relay UE indicating that an RRC setup failure has occurred between the relay UE and the base station, the remote UE may release the unicast connection to the relay UE.

[0236] 9 is a schematic flowchart of a communication method according to an embodiment of the present application. The method is a remote UE re-setup procedure, in which multiple routes are configured for the remote UE. The method includes the following steps:

[0237] Step 901: A remote UE selects a suitable cell and a relay UE within the cell.

[0238] For the method of selecting a relay UE by a remote UE, please refer to the description of step 601f in FIG. 6(f).

[0239] Step 902: The remote UE sends an RRC re-setup request message to the base station over the Uu interface.

[0240] This base station is the base station in which the suitable cell selected by the remote UE is located, which may or may not be the same as the base station accessed by the remote UE before sending the RRC re-setup request message.

[0241] If the base station (hereinafter referred to as base station 1) is different from the base station (hereinafter referred to as base station 2) that the remote UE accesses before sending the RRC re-setup request message, the base station 1 can obtain the context information of the remote UE from the base station 2.

[0242] Step 903: If there is no unicast connection between the remote UE and the selected relay UE, the remote UE sets up a unicast connection to the relay UE.

[0243] Step 904: The relay UE sends the SUI to the base station.

[0244] For the contents of the SUI, see the description of step 604f in FIG. 6(f).

[0245] Step 905: The base station sends an RRC re-setup message to the remote UE.

[0246] For the contents of the RRC re-setup message, please refer to the description of step 605f in Figure 6(f).

[0247] Step 906a: The base station sends an RRC reconfiguration message to the relay UE.

[0248] For the contents of the RRC reconfiguration message, please refer to the description of the embodiment in FIG. 6(f).

[0249] Step 906b: The relay UE sends an RRC reconfiguration complete message to the base station.

[0250] Step 907: The remote UE sends an RRC re-setup complete message to the base station.

[0251] For the contents of the RRC reconfiguration message, please refer to the description of step 606f in Figure 6(f).

[0252] Step 908: The base station sends an RRC reconfiguration message to the remote UE.

[0253] For the contents of the RRC reconfiguration message, please refer to the description of the embodiment in FIG. 6(f).

[0254] Step 909: The remote UE sends an RRC reconfiguration complete message to the base station.

[0255] To facilitate the rapid implementation of multipath configuration for the remote UE, in the above solution, in the remote UE re-setup procedure, re-setup and multipath configuration are performed simultaneously for the remote UE.

[0256] In the embodiment of Figure 9, the relay UE selected by the remote UE and the remote UE are in the same cell. In practical applications, a relay UE that is not in the same cell as the remote UE may be selected instead, which is not limited in this application.

[0257] In the embodiment of Figure 9, the remote UE selects a relay UE. In practical application, the remote UE may instead use an RRC re-setup complete message to report information about multiple UEs obtained by measurement to the base station, and the base station selects one UE from the multiple UEs as a relay UE. After completing the re-setup procedure for the remote UE, the base station configures multiple routes for the remote UE based on the selected relay UE.

[0258] It should be understood that, to realize the functions of the foregoing embodiments, a remote terminal device, a relay terminal device, or an access network device includes corresponding hardware structures and / or software modules for performing various functions. Those skilled in the art should easily realize that the present application can be implemented by hardware or a combination of hardware and computer software based on the example units and method steps described in the embodiments disclosed in the present application. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application scenario and design constraints of the technical solutions.

[0259] 10 and 11 are diagrams of possible communication device structures according to embodiments of the present application. These communication devices may be configured to implement the functions of a remote terminal device, a relay terminal device, or an access network device in the method embodiments of FIGS. 6(a), 6(b), 6(c), 6(d), 6(e), 6(f), 7, and 9. Thus, the beneficial effects of the aforementioned method embodiments can also be achieved. In embodiments of the present application, the communication device may be a remote terminal device, a relay terminal device, or an access network device, or may be a module (e.g., a chip) used in a remote terminal device, a relay terminal device, or an access network device.

[0260] 10 includes a processing unit 1010 and a transceiver unit 1020. The communication device 1000 is configured to implement the functions of a remote terminal device, a relay terminal device, or an access network device in the embodiments of the aforementioned method.

[0261] When the communication apparatus is configured to perform the functions of the remote terminal device in the embodiment of the aforementioned method, the transceiver unit 1020 is configured to receive a configuration message from the access network device through an interface between the remote terminal device and the access network device, the configuration message including information about the relay terminal device, and the configuration message being used for RRC reconfiguration. The remote terminal device sends indication information to the relay terminal device based on the information about the relay terminal device, and the indication information triggers the relay terminal device to enter an RRC connected state.

[0262] In one possible implementation, the processing unit 1010 is configured to determine, based on the RRC status of the relay terminal device, that the relay terminal device needs to be triggered to enter an RRC connected state.

[0263] In one possible implementation, the configuration message further includes status information, where the status information indicates an RRC status of the relay terminal device. The remote terminal device determines the RRC status of the relay terminal device based on the status information.

[0264] In one possible implementation, the indication information is a configuration complete message.

[0265] In one possible implementation, the transceiver unit 1020 is configured to send a configuration complete message to the access network device through an interface between the remote terminal device and the access network device.

[0266] In one possible implementation, the transceiver unit 1020 is configured to send a request message to the relay terminal device, the request message being for requesting that a unicast connection be set up, the request message including indication information, the indication information indicating that the unicast connection be set up to obtain the relay service of the relay terminal device.

[0267] In one possible implementation, the indication information is PC5-S signaling, a PC5 RRC message, or SL MAC CE signaling.

[0268] In one possible implementation, the processing unit 1010 is configured to determine that a link or connection failure has occurred between the remote terminal device and the relay terminal device, and the transceiver unit 1020 is configured to send first failure indication information to the access network device, where the first failure indication information indicates that a link or connection failure has occurred between the remote terminal device and the relay terminal device.

[0269] In one possible implementation, the processing unit 1010 is configured to determine that a link failure or connection failure has occurred between the remote terminal device and the access network device, and the transceiver unit 1020 is configured to send second failure indication information to the access network device via the intermediate terminal device, where the second failure indication information indicates that a link failure or connection failure has occurred between the remote terminal device and the access network device.

[0270] In one possible implementation, the transceiver unit 1020 is configured to receive third fault indication information from the relay terminal device, where the third fault indication information indicates that a link failure or connection failure has occurred between the relay terminal device and the access network device, and to send fourth fault indication information to the access network device, where the fourth fault indication information indicates that a link failure or connection failure has occurred between the relay terminal device and the access network device.

[0271] In one possible implementation, the transceiver unit 1020 is further configured to transmit information regarding at least one candidate terminal device to the access network device through an interface between the remote terminal device and the access network device, wherein the at least one candidate terminal device includes a relay terminal device, and the information regarding the at least one candidate terminal device includes information indicating a signal quality of the candidate terminal device and / or whether the candidate terminal device supports multipath relaying.

[0272] In one possible implementation, the transceiver unit 1020 is further configured to receive a discovery message from a candidate terminal device, the discovery message including information indicating whether the candidate terminal device supports multi-path relaying.

[0273] In one possible implementation, the transceiver unit 1020 is further configured to receive a discovery message from a candidate terminal device, and the identification information of the candidate terminal device corresponding to the discovery message indicates whether the candidate terminal device supports multi-path relaying.

[0274] When the communications apparatus is configured to perform the functions of a relay terminal device in the aforementioned method embodiments, the transceiver unit 1020 is configured to receive indication information from the remote terminal device, the indication information being configured to trigger the access network device to enter an RRC connected state, and to send sidelink UE information to the access network device, the sidelink UE information including information about the remote terminal device and / or information about the relay terminal device.

[0275] In one possible implementation, the processing unit 1010 is configured to enter an RRC connected state based on the indication information.

[0276] In one possible implementation, the indication information is PC5-S signaling, a PC5 RRC message, a SL MAC CE signaling, or a configuration complete message from the relay terminal device.

[0277] In one possible implementation, the transceiver unit 1020 is configured to receive a request message from a remote terminal device, the request message being for requesting that a unicast connection be set up, the request message including indication information, the indication information indicating that the unicast connection be set up to obtain relay services of the relay terminal device.

[0278] In one possible implementation, the transceiver unit 1020 is configured to receive notification information from the access network device, and the notification information is configured to be used by the relay terminal device to determine whether control plane signaling needs to be forwarded for the remote terminal device. The processing unit 1010 is configured to determine, based on the notification information, whether control plane signaling needs to be forwarded for the remote terminal device or whether control plane signaling does not need to be forwarded for the remote terminal device.

[0279] In one possible implementation, the processing unit 1010 is configured to determine that a link or connection failure has occurred between the relay terminal device and the access network device, and the transceiver unit 1020 is configured to send failure indication information to the remote terminal device, the failure indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device.

[0280] In one possible implementation, the transceiver unit 1020 is further configured to transmit a discovery message to the remote terminal device, the discovery message including information indicating that the relay terminal device supports multi-path relaying.

[0281] In one possible implementation, the transceiver unit 1020 is further configured to send a discovery message to the remote terminal device, and the identification information of the relay terminal device corresponding to the discovery message indicates that the relay terminal device supports multi-path relaying.

[0282] When the communications apparatus is configured to perform the functions of an access network device in an embodiment of the aforementioned method, the transceiver unit 1020 sends a configuration message to the remote terminal device through an interface between the remote terminal device and the access network device, the configuration message including information and status information about the relay terminal device, the status information indicating an RRC status of the relay terminal device, the configuration message being configured to be used for RRC reconfiguration, and receives sidelink UE information from the relay terminal device, the sidelink UE information being configured to include information about the relay terminal device and information about the relay terminal device.

[0283] In one possible implementation, the transceiver unit 1020 is configured to receive a configuration complete message in response to a configuration message from the remote terminal device through an interface between the remote terminal device and the access network device.

[0284] In one possible implementation, the transceiver unit 1020 is configured to receive a configuration complete message in response to the configuration message from the remote terminal device via the relay terminal device.

[0285] In one possible implementation, the transceiver unit 1020 sends notification information to the relay terminal device, and the notification information is used by the relay terminal device to determine whether control plane signaling needs to be forwarded for the remote terminal device, and the second configuration message is configured to be used for RRC reconfiguration.

[0286] When the communication apparatus is configured to perform the functions of the remote terminal device in the aforementioned method embodiments, the processing unit 1010 is configured to select a relay terminal device. The transceiver unit 1020 is configured to send an RRC re-setup request message to the access network device, receive an RRC re-setup message from the access network device, and send an RRC re-setup complete message to the access network device, where the RRC re-setup complete message includes information about the relay terminal device and / or information about the remote terminal device.

[0287] In one possible implementation, the processing unit 1010 is configured to set up a unicast connection between the relay terminal devices before the transceiver unit 1020 sends an RRC re-setup complete message to the access network device.

[0288] For more detailed descriptions of the processing unit 1010 and the transceiver unit 1020, please directly refer to the relevant descriptions of the aforementioned method embodiments, and details will not be described here.

[0289] 11 includes a processor 1110 and an interface circuit 1120. The processor 1110 and the interface circuit 1120 are coupled to each other. It will be understood that the interface circuit 1120 may be a transceiver or an input / output interface. Optionally, the communication device 1100 may further include a memory 1130 configured to store instructions executed by the processor 1110, input data required by the processor 1110 to execute the instructions, or data generated after the processor 1110 executes the instructions.

[0290] The communication device 1100 may be a remote terminal device, a relay terminal device, or an access network device in the embodiments of the above-mentioned methods, or may be a module (e.g., a chip) used in a remote terminal device, a relay terminal device, or an access network device.

[0291] When the communication device 1100 is configured to perform embodiments of the above-described methods, the processor 1110 is configured to implement the functions of the processing unit 1010, and the interface circuit 1120 is configured to implement the functions of the transceiver unit 1020.

[0292] It will be understood that the processor in this embodiment of the present application may be a central processing unit (CPU), or may be another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0293] FIG. 12 is a diagram of the structure of a terminal device. The terminal device is applicable to the operations performed by a remote terminal device or a relay terminal device in any one of the above-described method embodiments. For ease of explanation, FIG. 12 shows only the main components of the terminal device. The terminal device 1200 shown in FIG. 12 includes a processor, a memory, a control circuit, an antenna, and an input / output device. The processor is primarily configured to process communication protocols and communication data, control the entire terminal device, execute software programs, and process data of the software programs. The memory is primarily configured to store software programs and data. The control circuit is primarily configured to convert between baseband signals and radio frequency signals and process radio frequency signals. The antenna is primarily configured to receive and transmit radio frequency signals in the form of electromagnetic waves. The input / output device, for example, a touch screen, a display screen, or a keyboard, is primarily configured to receive data input by a user and output data to the user.

[0294] After the terminal device is powered on, the processor can read the software program in the memory, parse and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor performs baseband processing on the data to be transmitted and outputs the baseband signal to the control circuit. The control circuit processes the baseband signal to obtain a radio frequency signal, and transmits the radio frequency signal in the form of an electromagnetic wave via an antenna. When the data is transmitted to the terminal device, the control circuit receives the radio frequency signal via the antenna. The radio frequency signal is further converted into a baseband signal, and the baseband signal is output to the processor. The processor converts the baseband signal into data and processes the data.

[0295] For simplicity of explanation, FIG. 12 shows only one memory and one processor. In an actual terminal device, there may be multiple processors and memories. The memory may also be referred to as a storage medium or a storage device. This is not limited to the embodiment of the present application.

[0296] In one optional implementation, the processor may include a baseband processor and a central processing unit. The baseband processor is primarily configured to process communication protocols and communication data. The central processing unit is primarily configured to control the entire terminal device, execute software programs, and process data from the software programs. The functions of the baseband processor and the central processing unit are integrated into the processor in FIG. 12. Those skilled in the art will understand that the baseband processor and the central processing unit may each be independent processors and interconnected using technology such as a bus. Those skilled in the art will understand that a terminal device may include multiple baseband processors to accommodate various network standards, may include multiple central processing units to increase the processing capabilities of the terminal device, and components of the terminal device may be connected using various buses. The baseband processor may alternatively be referred to as a baseband processing circuit or a baseband processing chip. The central processing unit may alternatively be referred to as a central processing circuit or a central processing chip. The function of processing communication protocols and communication data may be built into the processor or stored in memory in the form of a software program, and the processor executes the software program to implement the baseband processing function.

[0297] In one example, an antenna and a control circuit having transceiver functionality can be considered as a transceiver unit 1211 of the terminal device 1200, and a processor having processing functionality can be considered as a processing unit 1212 of the terminal device 1200. As shown in FIG. 12, the terminal device 1200 includes a transceiver unit 1211 and a processing unit 1212. The transceiver unit may also be referred to as a transceiver, a transceiver machine, a transceiver device, or the like. Optionally, a component within the transceiver unit 1211 configured to realize a receiving functionality can be considered as a receiving unit, and a component within the transceiver unit 1211 configured to realize a transmitting functionality can be considered as a transmitting unit. In other words, the transceiver unit 1211 includes a receiving unit and a transmitting unit. For example, the receiving unit may also be referred to as a receiver, a receiving circuit, or the like, and the transmitting unit may also be referred to as a transmitter, a transmitter, a transmitting circuit, or the like. Optionally, the receiving unit and the transmitting unit may be integrated into one unit or may be multiple separate units, and the receiving unit and the transmitting unit may be located in one geographic location or may be distributed across multiple geographic locations.

[0298] An embodiment of the present application further provides a communications device including a processor coupled to a memory. The processor is configured to invoke a program stored in the memory to perform the operations performed by a remote terminal device, a relay terminal device, or an access network device in the aforementioned method embodiments. The memory may be located internal or external to the device. In addition, there may be one or more processors.

[0299] One embodiment of the present application provides a communications device including a processor and a memory, the memory configured to store computer instructions, and when the device is operated, the processor executes the computer instructions stored in the memory to perform operations performed by a remote terminal device, a relay terminal device, or an access network device in the aforementioned method embodiments.

[0300] An embodiment of the present application further provides a chip system including a processor, the processor being configured to perform the operations performed by a remote terminal device, a relay terminal device, or an access network device in the aforementioned method embodiments.

[0301] An embodiment of the present application further provides a communication system, including the remote terminal device and the relay terminal device in the aforementioned method embodiment. Optionally, the communication system further includes an access network device in the method embodiment.

[0302] An embodiment of the present application further provides a computer-readable storage medium, which stores instructions that, when executed in a communication device, cause the operations performed by a remote terminal device, a relay terminal device, or an access network device in the aforementioned method embodiments to be performed.

[0303] An embodiment of the present application further provides a computer program product, which includes computer programs or instructions that, when executed by a communication device, cause the operations performed by a remote terminal device, a relay terminal device, or an access network device in the aforementioned method embodiments to be performed.

[0304] The steps of the method in the embodiments of the present application may be implemented in a hardware manner or by a processor executing software instructions. The software instructions may include corresponding software modules. The software modules may be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disk, removable hard disk, CD-ROM, or any other form of storage medium well known in the art. For example, the storage medium may be coupled to the processor such that the processor can read information from and write information to the storage medium. Of course, the storage medium may instead be a component of the processor. The processor and the storage medium may be located in an ASIC. In addition, the ASIC may be located in a base station or a terminal. Of course, the processor and the storage medium may instead reside in the base station or the terminal as separate components.

[0305] All or part of the above-described embodiments may be implemented by software, hardware, firmware, or any combination thereof. When software is used to implement the above-described embodiments, all or part of the above-described embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer programs or instructions are loaded and executed on a computer, all or part of the procedures or functions of the embodiments of the present application are performed. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a base station, user equipment, or another programmable device. The computer program or instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired or wireless manner. The computer-readable storage medium may be any available medium that can be accessed by a computer, or may be a data storage device, such as a server or data center, that integrates one or more available media. The available media may be magnetic media such as floppy disks, hard disks, or magnetic tapes, or optical media such as digital video disks, or semiconductor media such as solid-state drives. The computer-readable storage media may be volatile or non-volatile storage media, or may include two types of storage media: volatile and non-volatile storage media.

[0306] In the embodiments of the present application, unless otherwise stated or there is no logical contradiction, the terms and / or descriptions of various embodiments are consistent and can be cross-referenced, and the technical features of various embodiments can be combined based on their internal logical relationships to form new embodiments.

[0307] In this application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes an association relationship between related objects and indicates that three relationships may exist. For example, A and / or B can indicate that only A is present, that both A and B are present, or that only B is present, and A and B may be singular or plural. In the text description of this application, the character " / " indicates an "or" relationship between related objects. In the formulae of this application, the character " / " indicates a "divide by" relationship between related objects.

[0308] It should be understood that various numbers in the embodiments of the present application are used only for distinction to facilitate description, and are not used to limit the scope of the embodiments of the present application. The sequential numbers of the above processes do not imply an execution order, and the execution order of the processes should be determined based on the functions and internal logic of the processes. [Explanation of symbols]

[0309] 1000 Communication Systems 100 Wireless Access Network 200 Core Network 300 Internet 110a base station 110b Micro Base Station 120a, 120e, 120f, and 120j mobile phones 120b vehicle 120c fuel dispenser 120d Home Access Node 120g notebook computer 120h printer 120i unmanned aerial vehicle 1000 Communication Equipment 1010 Processing Unit 1020 Transceiver Unit 1100 Communication equipment 1110 processor 1120 Interface Circuit 1130 memory 1200 Terminal Devices 1211 Transceiver Unit 1212 Processing Unit

Claims

1. 1. A communication method comprising: receiving a configuration message from an access network device through an interface between the remote terminal device and the access network device, the configuration message including information about a relay terminal device; sending indication information to the relay terminal device based on the information about the relay terminal device, the indication information triggering the relay terminal device to enter an RRC connected state; A method comprising:

2. The method comprises: The method of claim 1 , further comprising: determining, based on an RRC status of the relay terminal device, that the relay terminal device needs to be triggered to enter the RRC connected state.

3. The configuration message further includes status information, and the status information indicates the RRC status of the relay terminal device; The method comprises: The method of claim 2 , further comprising determining the RRC status of the relay terminal device based on the status information.

4. The method according to claim 2 or 3, wherein the instruction information is a configuration completion message in response to the configuration message.

5. The method comprises: The method according to claim 1 , further comprising the step of sending a configuration completion message in response to the configuration message to the access network device through the interface between the remote terminal device and the access network device.

6. the step of sending indication information to the relay terminal device is a step of sending a request message to the relay terminal device, the request message including the indication information, the request message for requesting to set up a unicast connection, and the indication information indicating that the unicast connection is set up to obtain a relay service of the relay terminal device; or The method according to any one of claims 1 to 3 and 5, comprising a step in which the indication information is a request message for requesting to set up a unicast connection related to a relay service.

7. 6. The method according to claim 1, wherein the indication information is a PC5-S signaling, a PC5 RRC message, or a sidelink medium access control element (SL MAC CE) signaling.

8. The method comprises:

8. The method of claim 1, further comprising: determining that a link or connection failure has occurred between the remote terminal device and the relay terminal device; and transmitting first failure indication information to the access network device, wherein the first failure indication information indicates that a link or connection failure has occurred between the remote terminal device and the relay terminal device.

9. The method comprises:

8. The method of claim 1, further comprising: determining that a link failure or connection failure has occurred between the remote terminal device and the access network device; and transmitting second failure indication information to the access network device via the intermediate terminal device, wherein the second failure indication information indicates that a link failure or connection failure has occurred between the remote terminal device and the access network device.

10. The method comprises: receiving third fault indication information from the relay terminal device, the third fault indication information indicating that a link failure or connection failure has occurred between the relay terminal device and the access network device; sending fourth fault indication information to the access network device, the fourth fault indication information indicating that a link failure or a connection failure has occurred between the relay terminal device and the access network device; 8. The method of claim 1, further comprising:

11. The method comprises:

11. The method of claim 1, further comprising the step of transmitting information about at least one candidate terminal device to the access network device through the interface between the remote terminal device and the access network device, wherein the at least one candidate terminal device includes the relay terminal device, and the information about the at least one candidate terminal device includes information indicating a signal quality of the candidate terminal device and / or whether the candidate terminal device supports multipath relaying.

12. The method comprises: The method of claim 11 , further comprising receiving a discovery message from the candidate terminal device, the discovery message including the information indicating whether the candidate terminal device supports multi-path relaying.

13. The method comprises:

12. The method of claim 11, further comprising: receiving a discovery message from the candidate terminal device, wherein identification information of the candidate terminal device corresponding to the discovery message indicates whether the candidate terminal device supports multi-path relay.

14. 1. A communication method comprising: receiving indication information from a remote terminal device, the indication information triggering the access network device to enter an RRC connected state; sending sidelink UE information to the access network device, the sidelink UE information including information about the remote terminal device and / or information about a relay terminal device; A method comprising:

15. The method comprises: The method of claim 14 , further comprising entering the RRC connected state based on the indication information.

16. The method according to claim 14 or 15, wherein the indication information is a PC5-S signaling, a PC5 RRC message, a sidelink medium access control control element (SL MAC CE) signaling, or a configuration complete message from the relay terminal device.

17. the step of receiving indication information from a remote terminal device is a step of receiving a request message from the remote terminal device, the request message including the indication information, the request message for requesting to set up a unicast connection, and the indication information indicating that the unicast connection is to be set up to obtain a relay service of the relay terminal device; or 16. The method according to claim 14, comprising the step of: the indication information being a request message for requesting the setting up of a unicast connection associated with a relay service.

18. The method comprises:

18. The method of claim 14, further comprising: determining that a link or connection failure has occurred between the relay terminal device and the access network device; and transmitting fault indication information to the remote terminal device, the fault indication information indicating that a link or connection failure has occurred between the relay terminal device and the access network device.

19. The method comprises:

19. The method according to claim 14, further comprising the step of sending a discovery message to the remote terminal device, the discovery message including information indicating that the relay terminal device supports multi-path relaying.

20. The method comprises:

19. The method according to claim 14, further comprising the step of sending a discovery message to the remote terminal device, wherein identification information of the relay terminal device corresponding to the discovery message indicates that the relay terminal device supports multi-path relaying.

21. 1. A communication method comprising: sending a configuration message to the remote terminal device through an interface between the remote terminal device and an access network device, the configuration message including information about a relay terminal device and status information, the status information indicating an RRC status of the relay terminal device; receiving sidelink UE information from the relay terminal device, the sidelink UE information including the information about the relay terminal device and information about the remote terminal device; A method comprising:

22. The method comprises: receiving a configuration complete message from the remote terminal device over the interface between the remote terminal device and the access network device in response to the configuration message; or 22. The method of claim 21, further comprising receiving a configuration completion message from the remote terminal device via the relay terminal device in response to the configuration message.

23. The method comprises: receiving information about at least one candidate terminal device from the remote terminal device through the interface between the remote terminal device and the access network device, the information about the at least one candidate terminal device including information indicating a signal quality of the candidate terminal device and / or whether the candidate terminal device supports multipath relaying; selecting the relay terminal device from the at least one candidate terminal device based on the information about the at least one candidate terminal device; 23. The method of claim 21 or 22, further comprising:

24. 1. A communication method comprising: determining whether the intermediate terminal device needs to forward control plane signaling for the remote terminal device; sending notification information to the relay terminal device, the notification information being for the relay terminal device to determine whether it is necessary for the relay terminal device to forward the control plane signaling for the remote terminal device; A method comprising:

25. The step of determining whether the intermediate terminal device needs to forward control plane signaling for the remote terminal device includes: determining that the intermediate terminal device does not need to forward the control plane signaling for the remote terminal device if the remote terminal device can receive the control plane signaling from the access network device through an interface between the remote terminal device and an access network device; or determining that the relay terminal device needs to forward the control plane signaling for the remote terminal device when the remote terminal device cannot receive the control plane signaling from the access network device through an interface between the remote terminal device and the access network device; 25. The method of claim 24, comprising:

26. 1. A communication method comprising: receiving notification information from an access network device, the notification information being for determining whether an intermediate terminal device needs to forward control plane signaling for a remote terminal device; determining, based on the notification information, that the control plane signaling needs to be forwarded for the remote terminal device, or that the control plane signaling does not need to be forwarded for the relay terminal device; A method comprising:

27. The notification information indicates a relay service type provided by the relay terminal device; The step of determining, based on the notification information, that the control plane signaling needs to be forwarded for the remote terminal device or that the control plane signaling does not need to be forwarded for the relay terminal device, comprises:

27. The method of claim 26, comprising determining, based on the relay service type provided by the relay terminal device, that the control plane signaling needs to be forwarded for the remote terminal device or that the control plane signaling does not need to be forwarded for the relay terminal device.

28. 13. A communication device comprising a module configured to perform the method according to any one of claims 1 to 13, a module configured to perform the method according to any one of claims 14 to 20, a module configured to perform the method according to any one of claims 21 to 23, a module configured to perform the method according to claim 24 or 25, or a module configured to perform the method according to claim 26 or 27.

29. A communications device comprising a processor and an interface circuit, wherein the interface circuit is configured to receive signals from a communications device other than the communications device and to transmit the signals to the processor or to transmit signals from the processor to a communications device other than the communications device, and wherein the processor is configured to perform, by logic circuits or by executing code instructions, a method according to any one of claims 1 to 13, a method according to any one of claims 14 to 20, a method according to any one of claims 21 to 23, a method according to claim 24 or 25, or a method according to claim 26 or 27.

30. 28. A computer program product, the computer program product comprising a computer program which, when executed by a communications device, performs the method of any one of claims 1 to 27.

31. 28. A computer-readable storage medium having stored thereon a computer program or instructions which, when executed by a communications device, perform the method of any one of claims 1 to 27.

32. 1. A communication system comprising: A system comprising a remote terminal device configured to perform the method of any one of claims 1 to 13 and a relay terminal device configured to perform the method of any one of claims 14 to 20.

33. The system of claim 32, further comprising an access network device configured to perform the method of any one of claims 21 to 23.

34. A communication system comprising an access network device configured to perform the method of claim 24 or 25, and a relay terminal device configured to perform the method of claim 26 or 27.

35. A chip system comprising a processor, the processor configured to perform the method of any one of claims 1 to 27.

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