Sidelink communication method and apparatus, and storage medium

Abstract

The present application provides a sidelink communication method and apparatus, and a storage medium, capable of enabling an intermediate relay UE to provide multi-hop relay services for remote UEs, thereby improving the flexibility of multi-hop relay services. The method comprises: a third terminal device acquires information of a first multi-hop relay link; the third terminal device sends first information to a first terminal device, the first information being used for indicating that the third terminal device is connected to a network via the first multi-hop relay link; and the first terminal device performs path change on the basis of the first information.

Description

Sidelink communication method, device and storage medium

[0001] This application claims priority to Chinese Patent Application No. 202411918081.3, filed on December 20, 2024, entitled "Side Link Communication Method, Apparatus and Storage Medium", and to Chinese Patent Application No. 202411918081.3, filed on March 27, 2025, entitled "Side Link Communication Method, Apparatus and Storage Medium", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communications, and more particularly to a sidelink communication method, apparatus and storage medium. Background Technology

[0003] In wireless communication, user equipment (UE) can communicate with each other via network devices, or they can communicate directly with each other without the aid of network devices. The communication interface between UEs is called the PC5 interface, similar to the Uu interface between a UE and a network device. The link between UEs is called a sidelink (SL).

[0004] User Equipment-to-Network (UE-to-network, U2N) relay functionality refers to a technology where one UE helps another UE communicate with network devices; it's also called relay technology. The U2N relay communication architecture includes a remote UE and a relay UE. The remote UE is located at the edge of network coverage or has no network coverage. The remote UE and the relay UE communicate via the PC5 interface. The relay UE is directly connected to the network device via the Uu interface, allowing the remote UE to communicate with the network device through the relay UE.

[0005] In the U2N relay communication architecture, remote UEs and relay UEs can execute a discovery process under certain conditions. The remote UE can search for available relay UEs in the vicinity based on this discovery process and select one to access the network. As an evolution of U2N relay, multi-hop relay allows remote UEs to communicate with network devices through multiple relay UEs. For example, the remote UE is connected to relay UE#1 via the PC5 interface, relay UE#1 is connected to relay UE#2 via the PC5 interface, and relay UE#2 is connected to the network device via the Uu interface. Relay UE#2, which is directly connected to the network device, can be called a U2N relay UE. Relay UE#1, located between the remote UE and relay UE#2, can be called an intermediate relay UE.

[0006] If the intermediate relay UE supports multi-hop relay, but the relay UE currently connected to the intermediate relay UE does not support multi-hop relay, or the network device currently connected to the intermediate relay UE does not support multi-hop relay, then how the intermediate relay UE can provide multi-hop relay service to the remote UE is an urgent problem to be solved. Summary of the Invention

[0007] This application provides a sidelink communication method, apparatus, and storage medium, which enables an intermediate relay UE to provide multi-hop relay services to a remote UE, thereby improving the flexibility of multi-hop relay services.

[0008] Firstly, a sidelink communication method is provided. This method can be applied to the terminal side, such as a terminal device or a communication module within the terminal device, or a circuit or chip within the terminal device responsible for communication functions. The following description uses the application of this method to a first terminal device as an example. The method includes: receiving first information from a third terminal device, the first information indicating that the third terminal device connects to the network via a first multi-hop relay link; and, based on the first information, performing a path change.

[0009] The first terminal device supports multi-hop relay. The first terminal device communicates with the first network device through the second terminal device. The second terminal device does not support multi-hop relay and / or the first network device does not support multi-hop relay. The terminal devices and network devices on the first multi-hop relay link support multi-hop relay and can provide multi-hop relay services for the third terminal device.

[0010] Based on the technical solution of this application, the first terminal device can still support the multi-hop relay process even when the currently connected second terminal device and / or the first network device does not support multi-hop relay. Furthermore, when the third terminal device chooses to connect to the network through the first multi-hop relay link, the first terminal device changes the path, thereby providing multi-hop relay service to the third terminal device and improving the flexibility of the multi-hop relay service.

[0011] In conjunction with the first aspect, in certain implementations of the first aspect, path modification is performed based on the first information, including: releasing the connection between the first terminal device and the second terminal device; and establishing a connection between the first terminal device and the fourth terminal device. The fourth terminal device is a relay node on the first multi-hop relay link.

[0012] The fourth terminal device is a relay node adjacent to the first terminal device on the first multi-hop relay link, the network device on the first multi-hop relay link is the second network device, and the fourth terminal device is connected to the second network device.

[0013] Optionally, the fourth terminal device can be directly connected to the second network device, that is, the connection between the fourth terminal device and the second network device does not go through a relay node.

[0014] Optionally, the fourth terminal device is not directly connected to the second network device; that is, the fourth terminal device is connected to the second network device through a relay node.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the first terminal device is in a radio resource control (RRC) idle state or an RRC inactive state. In this case, the first terminal device can reselect the relay node to connect to, that is, select a relay node that can provide multi-hop relay services to the third terminal device and establish a connection with it.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: sending second information to a fourth terminal device, the second information being used to request the establishment of a connection between the first terminal device and a second network device, the second network device being the network device to which the fourth terminal device is connected.

[0017] Specifically, when the first terminal device is in RRC connected state, it can release the connection between itself and the second terminal device and establish a connection between itself and the fourth terminal device. Then, the first terminal device sends second information to the fourth terminal device to request the establishment of a connection between itself and the second network device. In other words, if the first terminal device is in RRC connected state, it can trigger an RRC re-establishment to perform a path change.

[0018] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: sending second information to a fourth terminal device, including: sending second information to the fourth terminal device when a first condition is met, the first condition including: the number of relay hops between the first terminal device and the first network device is greater than or equal to a first threshold, and / or, the fourth terminal device is connected to the second network device through a relay node.

[0019] In this application, since the first network device can only support a limited number of handover scenarios, such as supporting single-hop link handover but not multi-hop link handover, when the first terminal device is in RRC connection state, the first terminal device can determine whether to perform path change by triggering RRC re-establishment based on the first condition. This helps to avoid path change failure.

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the second information is an RRC re-establishment request message.

[0021] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: sending first indication information related to multi-hop relay to the first network device; and receiving third information from the first network device, the third information being used to instruct the first terminal device to make a path change.

[0022] Optionally, the first terminal device releases the connection between the first terminal device and the second terminal device based on the third information, and establishes a connection between the first terminal device and the fourth terminal device.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, the first indication information related to multi-hop relay also includes one or more of the following: the layer 2 identifier of the fourth terminal device, the identifier of the serving cell of the fourth terminal device, or the link signal quality between the fourth terminal device and the first terminal device.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the first indication information related to multi-hop relay is used to indicate that the fourth terminal device supports multi-hop relay.

[0025] In conjunction with the first aspect, in some implementations of the first aspect, the first indication information related to multi-hop relay is also used to indicate the need for multi-hop relay.

[0026] In conjunction with the first aspect, in some implementations of the first aspect, sending multi-hop relay-related first indication information to the first network device includes: sending multi-hop relay-related first indication information to the first network device when a second condition is met; the second condition includes: the number of relay hops between the first terminal device and the first network device is less than or equal to a first threshold, and / or, the connection between the fourth terminal device and the second network device does not pass through a relay node.

[0027] In this application, since the first network device can only support a limited number of handover scenarios, such as supporting single-hop link handover but not multi-hop link handover, when the first terminal device is in RRC connection state, the first terminal device can determine whether to change the path by triggering the handover path through the first network device according to the second condition. This helps to avoid the occurrence of path change failure.

[0028] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: receiving fourth information from a fourth terminal device, the fourth information indicating that the fourth terminal device supports multi-hop relay, the fourth terminal device being a relay node on the first multi-hop relay link; and sending fifth information, the fifth information including information about the first multi-hop relay link.

[0029] In this application, the first terminal device can obtain information about the first multi-hop relay link through a discovery process. The fourth terminal device is a terminal device located near the first terminal device. The first terminal device can obtain multi-hop relay-related information about nearby terminal devices through the discovery process.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the fourth information also includes link information between the fourth terminal device and the second network device.

[0031] In conjunction with the first aspect, in some implementations of the first aspect, the fourth information also includes a relay service code (RSC), which indicates the maximum number of relay hops that the fourth terminal device can support.

[0032] This RSC is a multi-hop trunk-related RSC, indicating that the maximum number of trunk hops that can be supported can be greater than or equal to 2, which can implicitly indicate that the fourth terminal device supports multi-hop trunk links.

[0033] In conjunction with the first aspect, in some implementations of the first aspect, the information of the first multi-hop relay link includes one or more of the following:

[0034] The identifier of each terminal device on the first multi-hop trunk link; the link signal quality between adjacent terminal devices on the first multi-hop trunk link; the path information of the first multi-hop trunk link; the maximum number of hops that each terminal device on the first multi-hop trunk link can support; or, the number of hops of the first multi-hop trunk link.

[0035] In conjunction with the first aspect, in some implementations of the first aspect, the fifth information also includes second indication information related to multi-hop relay, which is used to indicate that the first terminal device has not established a connection with the fourth terminal device, or that the first multi-hop relay link has not been established.

[0036] In this application, the first terminal device can indicate that the multi-hop relay link has not been established. In this way, after the third terminal device receives information about multiple multi-hop relay links sent by nearby terminal devices, it can preferentially choose to connect to the network through the established multi-hop relay links, which helps to reduce the latency of the third terminal device accessing the network.

[0037] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: receiving sixth information from a third terminal device, the sixth information being used to request multi-hop relay service; and sending seventh information, the seventh information being used to request multi-hop relay service.

[0038] In this application, the first terminal device can obtain information about the first multi-hop relay link based on the discovery process. During the discovery process, the third terminal device broadcasts a request for multi-hop relay service. After receiving the request, the first terminal device broadcasts a request for multi-hop relay service to obtain a multi-hop relay link that can provide multi-hop relay service to the third terminal device.

[0039] In conjunction with the first aspect, in some implementations of the first aspect, the fifth information includes information on at least one multi-hop trunk link, each of which can be used to provide trunk services, wherein the first multi-hop trunk link is one of the at least one multi-hop trunk links.

[0040] In this application, the first terminal device can broadcast information about at least one multi-hop relay link, so that the third terminal device can select one of the multi-hop relay links to connect to the network. This gives the third terminal device more choices and allows it to access the network more flexibly.

[0041] In conjunction with the first aspect, in some implementations of the first aspect, the signal quality between the first terminal device and the fourth terminal device is greater than or equal to the second threshold.

[0042] It should be understood that the first terminal device can determine whether to broadcast information about a certain multi-hop relay link using a second threshold. If the link signal quality between adjacent terminal devices on a multi-hop relay link is greater than or equal to the second threshold, the first terminal device can broadcast information about that multi-hop relay link, which helps improve the reliability of data transmission. In this application, the link signal quality between the first terminal device and the fourth terminal device on the first multi-hop relay link is greater than or equal to the second threshold; therefore, the first terminal device can broadcast information about the first multi-hop relay link.

[0043] In conjunction with the first aspect, in some implementations of the first aspect, the first network device supports multi-hop relay, and the method further includes: receiving eighth information from the first network device, the eighth information including a second threshold. That is, the second threshold is indicated by the first network device.

[0044] In conjunction with the first aspect, in some implementations of the first aspect, the first network device does not support multi-hop relay, and the second threshold is pre-configured, for example, pre-configured by the first terminal device.

[0045] Secondly, a sidelink communication method is provided. This method can be applied to the terminal side, such as a terminal device or a communication module within the terminal device, or a circuit or chip within the terminal device responsible for communication functions. The following description uses the application of this method to a third terminal device as an example. The method includes: acquiring information about a first multi-hop relay link; and sending first information to the first terminal device, the first information instructing the third terminal device to establish a connection with the network through the first multi-hop relay link.

[0046] The first terminal device supports multi-hop relay. The first terminal device communicates with the first network device through the second terminal device. The second terminal device does not support multi-hop relay and / or the first network device does not support multi-hop relay. The terminal devices and network devices on the first multi-hop relay link support multi-hop relay and can provide multi-hop relay services for the third terminal device.

[0047] Based on the technical solution of this application, when the second terminal device and / or the first network device currently connected to the first terminal device do not support multi-hop relay, the third terminal device can instruct the first terminal device to connect to the network through the first multi-hop relay link. Then, the first terminal device can change the path based on the instruction of the first information to provide multi-hop relay service for the third terminal device, thereby improving the flexibility of multi-hop relay service.

[0048] In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: receiving fifth information from the first terminal device, the fifth information including information of the first multi-hop relay link.

[0049] In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: sending a sixth message, which is used to request a multi-hop relay service.

[0050] In conjunction with the second aspect, in some implementations of the second aspect, the fifth information includes information on at least one multi-hop trunk link, each of which can be used to provide trunk services, and the first multi-hop trunk link is one of the at least one multi-hop trunk links.

[0051] In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: sending a ninth message to the first terminal device, the ninth message being used to request the establishment of a connection with the first terminal device.

[0052] In conjunction with the second aspect, in some implementations of the second aspect, the ninth information may also include one or more of the following: the identifier of each terminal device on the first multi-hop trunk link; the link signal quality between adjacent terminal devices on the first multi-hop trunk link; the path information of the first multi-hop trunk link; the maximum number of trunk hops that each terminal device on the first multi-hop trunk link can support; or, the number of trunk hops of the first multi-hop trunk link.

[0053] It should be understood that the second aspect of this application corresponds to the technical solution of the first aspect of this application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, and will not be repeated here.

[0054] Thirdly, a sidelink communication method is provided. This method can be applied to the terminal side, such as a terminal device or a communication module within the terminal device, or a circuit or chip within the terminal device responsible for communication functions. The following description uses the application of this method to a fourth terminal device as an example. The method includes: sending fourth information, which indicates that the fourth terminal device supports multi-hop relay, and the fourth terminal device is a relay node on the first multi-hop relay link.

[0055] In this application, a fourth terminal device is connected to a second network device, both of which support multi-hop relay. The fourth terminal device can broadcast discovery messages during the discovery process, including information related to multi-hop relay, such as support for multi-hop relay links. This allows nearby terminal devices to determine available multi-hop relay links based on the discovery messages broadcast by the fourth terminal device, thereby providing multi-hop relay services to remote UEs.

[0056] In conjunction with the third aspect, in some implementations of the third aspect, the fourth information also includes link information between the fourth terminal device and the second network device.

[0057] In conjunction with the third aspect, in some implementations of the third aspect, the fourth information also includes an RSC, which indicates the maximum number of relay hops that the fourth terminal device can support.

[0058] In conjunction with the third aspect, in some implementations of the third aspect, the signal quality between the first terminal device and the fourth terminal device is greater than or equal to the second threshold. The first terminal device is a relay node on the first multi-hop relay link.

[0059] The first terminal device is a relay node adjacent to the fourth terminal device on the first multi-hop relay link, and the first terminal device supports multi-hop relay.

[0060] In conjunction with the third aspect, in some implementations of the third aspect, the method further includes: receiving second information from the first terminal device, the second information being used to request the establishment of a connection between the first terminal device and the second network device.

[0061] It should be understood that the third aspect of this application corresponds to the technical solution of the first aspect of this application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, so they will not be repeated here.

[0062] Fourthly, a sidelink communication method is provided. This method can be applied to the network side, such as a network device or a communication module within a network device, or a circuit or chip within a network device responsible for communication functions. The following description uses the application of this method to a first network device as an example. The method includes: receiving first indication information related to multi-hop relay from a first terminal device; and sending third information to the first terminal device, the third information being used to instruct the first terminal device to perform a path change. The first terminal device communicates with the first network device through a second terminal device.

[0063] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first indication information related to multi-hop relay also includes one or more of the following: the layer 2 identifier of the fourth terminal device, the identifier of the serving cell of the fourth terminal device, or the link signal quality between the fourth terminal device and the first terminal device.

[0064] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first indication information related to multi-hop relay is used to indicate that the fourth terminal device supports multi-hop relay.

[0065] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first indication information related to multi-hop relay is also used to indicate the need for multi-hop relay.

[0066] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the link signal quality between the first terminal device and the fourth terminal device is greater than or equal to the second threshold.

[0067] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first network device supports multi-hop relay, and the method further includes: sending an eighth message to the first terminal device, the eighth message including a second threshold.

[0068] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first network device does not support multi-hop relay, and the second threshold is pre-configured.

[0069] It should be understood that the fourth aspect of this application corresponds to the technical solution of the first aspect of this application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, so they will not be repeated here.

[0070] Fifthly, a communication apparatus is provided for executing the method in any possible implementation of any of the above aspects. Specifically, the apparatus includes a module for executing the method in any possible implementation of any of the above aspects.

[0071] In one design, the device may include modules that perform the methods / operations / steps / actions described in any of the above aspects. These modules may be hardware circuits, software, or a combination of hardware circuits and software.

[0072] In another design, the device is a communication chip, which may include input circuitry or interface for transmitting information or data, and output circuitry or interface for receiving information or data.

[0073] In another design, the device is a terminal device or a network device, which may include a transmitter for sending information or data and a receiver for receiving information or data.

[0074] In another design, the device is used to perform the method in any of the possible implementations of any of the above aspects, and the device can be configured in a terminal device or a network device.

[0075] A sixth aspect provides a communication device, including a processor for retrieving and running a computer program from a memory, such that the device performs the method in any possible implementation of any of the preceding aspects.

[0076] Optionally, the device further includes a memory for storing instructions and data. The memory is coupled to the processor, which, when executing the instructions stored in the memory, can implement the methods described in the foregoing aspects.

[0077] Optionally, the device may also include a transmitter and a receiver, which may be separate or integrated together and referred to as a transceiver.

[0078] In a seventh aspect, a computer program product is provided, the computer program product comprising: a computer program (also referred to as code or instructions), which, when the computer program is run, causes a computer to perform a method in any possible implementation of any of the above aspects.

[0079] In a sixth aspect, a computer-readable storage medium is provided that stores a computer program (also referred to as code or instructions) that, when executed on a computer, causes the computer to perform the methods in any possible implementation of any of the above aspects.

[0080] Eighthly, this application provides a communication system including a first terminal device for implementing the method described in the first aspect and any possible implementation of the first aspect, and a third terminal device for implementing the method described in the second aspect and any possible implementation of the second aspect.

[0081] Optionally, the communication system further includes a fourth terminal device for implementing the method described in the third aspect and any possible implementation of the third aspect, and a first network device for implementing the method described in the fourth aspect and any possible implementation of the fourth aspect.

[0082] Ninthly, this application provides a chip system including at least one processor for supporting the implementation of the functions involved in any of the above aspects, such as receiving or processing data involved in the above methods.

[0083] In one possible design, the chip system also includes a memory for storing program instructions and data, which may be located within or outside the processor.

[0084] Optionally, the chip system may consist of chips or may include chips and other discrete components. Attached Figure Description

[0085] Figure 1 is a schematic diagram of the architecture of a communication system according to an embodiment of this application;

[0086] Figure 2 is a schematic diagram of a side link communication;

[0087] Figure 3A is a flowchart illustrating the discovery process based on Model A under a side-link communication architecture;

[0088] Figure 3B is a flowchart illustrating the discovery process based on Model B under a side-link communication architecture;

[0089] Figure 4 is a schematic flowchart of a side-link communication method provided in an embodiment of this application;

[0090] Figure 5 is a schematic diagram of a multi-hop relay architecture provided in an embodiment of this application;

[0091] Figures 6 and 7 are schematic block diagrams of the communication device provided in the embodiments of this application. Detailed Implementation

[0092] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0093] Before introducing the technical solutions provided in the embodiments of this application, the following points should be made.

[0094] First, in the embodiments shown below, the terms and English abbreviations, such as multi-hop relay, sidelink, and Radio Resource Control (RRC), are merely exemplary examples given for ease of description and should not constitute any limitation on this application. This application does not preclude the possibility of defining other terms that can achieve the same or similar functions in existing or future protocols.

[0095] Second, in the embodiments shown below, the terms "first," "second," and various numerical designations are merely for descriptive convenience to distinguish identical or similar items with substantially the same function and purpose. For example, "first information" and "second information" are only used to distinguish different information and do not limit their order, nor are they used to limit the scope of the embodiments of this application. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., are not necessarily different.

[0096] Third, "at least one" means one or more, while "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0097] Fourth, in this application, "instruction" can include direct and indirect instructions, explicit and implicit instructions, and instructions used for determination. When describing certain instruction information to indicate A, it can be understood that the instruction information carries A, directly indicates A, or indirectly indicates A. In this application, the information indicated by the instruction information is called the information to be instructed. In specific implementation, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index. It can also indirectly indicate the information to be instructed by indicating other information, where there is a correlation between the other information and the information to be instructed. It can also indicate only a part of the information to be instructed, while the other parts are known or pre-agreed upon. For example, the instruction of specific information can be achieved by using a pre-agreed (e.g., protocol-defined) arrangement of various information, thereby reducing instruction overhead to some extent. Furthermore, the information to be instructed can be sent as a whole or divided into multiple sub-information to be sent separately, and the sending period and / or timing of these sub-information can be the same or different. This application does not limit the specific method of instruction. It is understood that, for the sender of the instruction information, the instruction information can be used to indicate the information to be indicated, and for the receiver of the instruction information, the instruction information can be used to determine the information to be indicated.

[0098] The information in this application is used to indicate one or more contents, or it may be replaced with the information indicating one or more contents, or the information including one or more contents.

[0099] Fifth, in this application, "when," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, not to a time limit, nor do they require the device to perform a judgment action, nor do they imply any other limitations. Unless otherwise specified, "if" and "if" are interchangeable, and "when" and "under the circumstances" are interchangeable. "When" is interchangeable with "if" / "if."

[0100] Sixth, in this application, the words "exemplarily" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplarily" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0101] Seventh, "Sending information / data" only indicates the direction of information / data transmission, including direct transmission via the device's communication interface (such as an air interface). "Sending" can also be understood as the "output" of the module interface. "Sending" can include indirect transmission by the processing unit through the communication interface, that is, after the processing unit outputs information / data through the module interface, it is transmitted to the device's communication interface and then sent out. "Receiving information / data" only indicates the direction of information / data transmission, including direct reception via the communication interface. "Receiving" can also be understood as the "input" of the module interface. "Receiving information / data" can include indirect reception by the processing unit through the communication interface, that is, after the communication interface receives information / data, it is transmitted to the module interface of the processing unit and then input to the processing unit. "Sending information / data to… (such as a terminal device)" can be understood as the destination of the information being the terminal device. It can include sending information / data directly or indirectly to the terminal device. "Receiving information / data from… (such as a terminal device)" can be understood as the source of the information being the terminal device, and can include receiving information / data directly or indirectly from the terminal device. Information / data may undergo necessary processing, such as format changes, between the source and destination, but the destination can understand the valid information / data from the source. Similar statements in this application can be understood in a similar way, and will not be repeated here.

[0102] In other words, sending and receiving can occur between devices, such as between terminal devices and network devices; or they can occur within a device, such as between components, modules, chips, software modules, or hardware modules within a device via a bus, wiring, or interface.

[0103] Eighth, in this application, the solutions in each embodiment can be used in a reasonable combination, and the explanations or descriptions of various terms, similar operations, or steps appearing in the embodiments can be referenced or explained to each other in the various embodiments, without limitation.

[0104] The technical solution of this application can be applied to various communication systems, such as: 4th generation mobile communication technology (4G) system (also known as long term evolution (LTE) system), 5th generation mobile communication technology (5G) system (also known as new radio (NR) system), or it can also be applied to future mobile communication systems or other similar communication systems, etc., without any specific limitations. Examples include: Wireless Fidelity (WiFi), Device-to-Device (D2D) communication systems, Vehicle-to-Everything (V2X) communication systems, Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microware Access (WiMAX) communication systems, Machine-to-Machine (M2M) communication systems, Machine-Type Communication (MTC) systems, Internet to Machine (IoT) communication systems, Non-Terrestrial Network (NTN) communication systems, High Altitude Platform Station (HAPS) communication networks, Integrated Access and Backhaul (IAB) communication networks, and Reconfigurable Intelligent Surface (RIS) communication networks. The technical solution of this application can be applied to communication systems that integrate two or more of the above systems.

[0105] To facilitate understanding of the technical solution of this application, a schematic diagram of the architecture of a communication system 100 according to an embodiment of this application is first briefly described with reference to Figure 1. As shown in Figure 1, the communication system 100 includes a terminal device 10, a terminal device 20, a terminal device 30, and a network device 40. When the terminal device 10 sends data to the network device 40, it needs to go through three paths, including the path between the terminal device 10 and the terminal device 20, the path between the terminal device 20 and the terminal device 30, and the path between the terminal device 30 and the network device 40. These three paths form a multi-hop path, that is, the multi-hop path is: terminal device 10 ←→ terminal device 20 ←→ terminal device 30 ←→ network device 40.

[0106] As an example, terminal device 10 can be referred to as a remote UE, and terminal devices 20 and 30 can be referred to as relay UEs. The relay UE can assist the remote UE in data transmission with the network device. The remote UE and the relay UE can communicate directly, for example, via SL connection, WiFi, Bluetooth, or wired connection, where unicast, multicast, or broadcast communication is supported on the SL. It should be understood that Figure 1 illustrates an example where two relay UEs are involved between the remote UE and the network device; this application does not limit the number of relay UEs between the remote UE and the network device.

[0107] For communication system 100, in one possible scenario, the remote UE is located at the edge of network coverage or outside the network coverage area, and coverage enhancement can be achieved through a relay UE. In another possible scenario, the relay UE has stronger capabilities; for example, the relay UE is equipped with more receiving and transmitting antennas, thereby increasing system capacity.

[0108] It should be understood that Figure 1 is a simplified schematic diagram for ease of understanding only, and the communication system may also include other network devices or terminal devices, which are not shown in Figure 1.

[0109] It should also be understood that Figure 1 is only one application scenario of this application, and this application does not limit the scenario in which the method is applied. In the embodiments shown below, the technical solutions of the embodiments of this application are described in detail for ease of understanding and explanation, taking the interaction between terminal devices and between terminal devices and network devices in the relay communication scenario as examples.

[0110] In one possible scenario, the network equipment in this application embodiment can be a base station, an evolved NodeB (eNodeB), a transmitting and receiving point (TRP), a transmitting point (TP), a next-generation NodeB (gNB), a next-generation base station in a 6G mobile communication system, a base station in a future mobile communication system, an access point (AP) in a satellite, an integrated access and backhaul (IAB) node, or an access network device in a mobile switching center non-terrestrial network (NTN) communication system. That is, it can be deployed on a high-altitude platform or satellite, etc. The access network equipment can be a macro base station (as shown in Figure 1, 110a), a micro base station or indoor station (as shown in Figure 1, 110b), a relay node or donor node, or a radio controller in a CRAN scenario. The access network equipment can also be a device that functions as a base station in device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, drone communication, or machine-to-machine (M2M) communication. Optionally, the access network equipment can also be a server, a wearable device, a vehicle, or an in-vehicle device, etc. For example, the access network equipment in vehicle-to-everything (V2X) technology can be a roadside unit (RSU).

[0111] In another possible scenario, the network device in this application embodiment can be multiple radio access network (RAN) nodes constituting a base station or transmission point. For example, the RAN node can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU and DU can be set up separately or included in the same network element, such as a baseband unit (BBU). The RU can be included in radio equipment or radio units, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH). It is understood that the RAN node can be a CU node, a DU node, or a device including both CU and DU nodes. Furthermore, the CU can be classified as an access network device in the RAN or as an access network device in the core network; no limitation is made here.

[0112] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an O-RAN system, CU can also be called O-CU (Open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0113] The terminal device in this embodiment is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from network devices. The terminal device can also be referred to as a terminal apparatus, terminal, user equipment, mobile station, mobile terminal, etc. For example, terminal devices include handheld devices and vehicle-mounted devices with wireless connectivity. Terminal devices can be widely used in various scenarios, such as D2D, V2X communication, MTC, IoT, virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. Terminal devices can be: mobile phones, tablets, laptops, PDAs, mobile internet devices (MIDs), wearable devices (such as smartwatches, smart bracelets, pedometers, smart glasses, etc.), in-vehicle equipment (such as cars, bicycles, electric vehicles, airplanes, ships, trains, high-speed trains, etc.), satellite terminals, virtual reality (VR) devices, augmented reality (AR) devices, smart point of sale (POS) machines, customer-premises equipment (CPE), light user equipment (UE), reduced capability user equipment (REDCAP UE), wireless terminals in industrial control, smart home devices (such as refrigerators, televisions, air conditioners, electricity meters, etc.), smart robots, robotic arms, workshop equipment, wireless terminals in autonomous driving, wireless terminals in telemedicine, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, or wireless terminals in smart homes, and flying equipment (such as smart robots, hot air balloons, drones, airplanes), etc. Terminal devices can also be vehicle devices, such as vehicle devices, vehicle modules, vehicle chips, on-board units (OBUs) or telematics boxes (T-BOXs). Terminal devices can also be other devices with terminal functions. For example, a terminal device can also be a device that performs terminal functions in D2D communication.

[0114] This application does not limit the form of the terminal device. The device used to implement the functions of the terminal device can be the terminal device itself, or it can be a device that supports the terminal device in implementing the functions, such as a chip system. The device can be installed in the terminal device or used in conjunction with the terminal device. In this application, the chip system can be composed of chips or can include chips and other discrete devices. All or part of the functions of the terminal device in this application can also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (e.g., a cloud platform).

[0115] Communication between network devices and terminal devices, between network devices and connecting network devices, and between terminal devices can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can be conducted using spectrum below 6 GHz, spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0116] In the embodiments of this application, the functions of the network device can be executed by modules (such as chips) within the network device, or by a control subsystem that includes network device functions. This control subsystem, including network device functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal can be executed by modules (such as chips or modems) within the terminal device, or by a device that includes terminal functions.

[0117] For ease of understanding, the relevant technologies and concepts involved in this application are introduced below.

[0118] 1. Side link communication

[0119] In wireless communication systems, terminal devices can communicate with each other via network devices or directly without network devices. As shown in Figure 2, the interface between terminal device 21 and terminal device 22 is called the PC5 interface, similar to the Uu interface between a terminal device and a network device. The link between terminal device 21 and terminal device 22 is called a sidelink. Terminal devices 21 and 22 can transmit data directly through the sidelink without going through network devices, which can effectively reduce communication latency.

[0120] The side link can support broadcast, unicast, and multicast communication.

[0121] Broadcast communication is similar to network equipment broadcasting system information, meaning that terminal devices send broadcast service data to the outside world without encryption, and any other terminal devices within the effective reception range that are interested in the broadcast service can receive the broadcast service data.

[0122] Multicast communication refers to communication between all terminal devices within a communication group, where any terminal device in the group can receive and send multicast service data.

[0123] Unicast communication is similar to data communication between a terminal device and a network device after establishing an RRC connection; it requires the two terminal devices to first establish a unicast connection. After establishing a unicast connection, the two terminal devices can communicate data based on a negotiated identifier. This data can be encrypted or unencrypted. Unlike broadcast communication, in unicast communication, only two terminal devices that have established a unicast connection can engage in unicast communication.

[0124] This application primarily relates to unicast communication. A single unicast communication on a sidelink corresponds to a pair of source layer 2 (L2) identifiers (IDs) and a destination L2 ID. Each sidelink media access control (MAC) layer protocol data unit (PDU) header will include a pair of source L2 IDs and a destination L2 ID to ensure data can be correctly transmitted from the sender to the receiver.

[0125] 2. Radio bearer (RB)

[0126] Radio bearers are a collective term for a series of protocol entities and configurations allocated by network devices to terminal devices. They are services provided by Layer 2 (L2) for transmitting user data between terminal devices and network devices. These include Packet Data Convergence Protocol (PDCP) entities, Radio Link Control (RLC) protocol entities, MAC protocol entities, and resources allocated by the physical layer (PHY). Radio bearers are divided into data radio bearers (DRBs) and signaling radio bearers (SRBs). DRBs carry data, while SRBs carry signaling messages. In the sidelink, communication between terminal devices is conducted through sidelink radio bearers (SLRBs), which include sidelink data radio bearers (SL DRBs) and sidelink signaling radio bearers (SL SRBs).

[0127] Radio bearer configuration typically includes the configuration of the PDCP layer and the Service Data Adaptation Protocol (SDAP) layer. Protocol entities below the RLC layer are called RLC bearers, and their configurations are given in the RLC bearer configuration. An RLC bearer includes a series of resources such as RLC protocol entities and logical channels. An RLC bearer is associated with a logical channel at the MAC layer. An RLC bearer is associated with a PDCP entity; that is, one RLC serves one radio bearer.

[0128] 3. Discovery procedure

[0129] A terminal device supporting proximity services searches for nearby terminal devices through a discovery process and establishes a unicast connection with them for subsequent sidelink communication. The discovery process includes two discovery models: Model A and Model B.

[0130] In Model A, terminal devices can be divided into two categories: announcing UEs and monitoring UEs, as shown in Figure 3A. Announcing UEs (Terminal Device 1 in Figure 3A) broadcast a discovery message, also known as an announcement message. This announcement message can carry specific information about the announcing UE, such as the types of services it can provide, which nearby terminal devices use to determine whether they need the services offered by the announcing UE. After receiving the discovery message, nearby monitoring UEs (Terminal Devices 2, 3, and 4 in Figure 3A) determine whether to use the announcing UE as the peer for sidelink communication based on the content carried in the discovery message.

[0131] In Model B, terminal devices can be divided into two categories: discoverer UEs and discoveree UEs, as shown in Figure 3B. The discoverer UE (Terminal Device 1 in Figure 3B) broadcasts a discovery message, also known as a solicitation message. This solicitation message carries information about the service types that the discoverer UE is interested in. After the discovered UEs (Terminal Devices 2, 3, and 4 in Figure 3B) monitor and receive the solicitation message, if they find that they meet the service requirements of the discoverer UE, they will reply with another discovery message, defined as a response message.

[0132] Similar to sidelink communication, the source L2 ID and destination L2 ID are used by the terminal device to send or receive discovery messages. The source L2 ID is assigned by the sender, and the destination L2 ID is a predefined or pre-configured default destination L2 ID. It is important to note that this default destination L2 ID is different from the default destination L2 ID used in sidelink communication; it is specifically used for discovery messages.

[0133] 4. Establishment of unicast connection

[0134] Unicast connections are established between terminal devices through a unicast connection establishment procedure. The terminal device initiating the unicast connection establishment procedure is called the initiating UE, and the peer of the initiating UE is called the target UE. During the unicast connection establishment process, the initiating UE sends a unicast connection establishment request (direct communication request, DCR) message to the target UE, along with the L2 IDs of both the initiating and target UEs, and user information (such as application layer related information). After receiving the DCR message, the target UE determines whether it can accept the unicast connection establishment request based on the user information in the DCR message. If yes, the target UE sends a unicast connection establishment acceptance (direct communication accept, DCA) message to the initiating UE; otherwise, the target UE sends a unicast connection establishment rejection (direct communication reject) message to the initiating UE.

[0135] 5. Multi-hop relay technology

[0136] As an evolution of U2N relay, the 3rd Generation Partnership Project (3GPP) was conducting research on multi-hop relay before initiating the project. This means that a remote UE can communicate with network devices through multiple relay UEs. As shown in Figure 1 above, terminal device 10 is the remote UE, and terminal devices 20 and 30 are relay UEs. Terminal device 30 is directly connected to network device 40 and can also be called a U2N relay UE. Terminal device 20 is a relay UE between the remote UE and the U2N relay UE, and can also be called an intermediate relay UE.

[0137] The existing U2N trunk architecture includes remote UEs and trunk UEs, and restricts the conditions under which the remote UE and trunk UE execute the discovery process. In contrast, in a multi-hop trunk architecture (as shown in Figure 1), one or more intermediate trunk UEs can be connected between the remote UE and the U2N trunk UE. The conditions for executing the discovery process in the existing U2N trunk communication architecture apply to both the remote UE and the U2N trunk UE, but not to the intermediate trunk UEs.

[0138] This application mainly considers the behavior of an intermediate relay UE performing a multi-hop relay procedure in the following scenario. Referring to Figure 1, terminal device 10 is a remote UE, terminal device 20 is an intermediate relay UE, and terminal device 30 is a U2N relay UE. Terminal device 20 establishes a connection with network device 40 through terminal device 30.

[0139] In one possible scenario, terminal device 30 supports single-hop relay but not multi-hop relay. Terminal device 20 can act as an intermediate relay UE to provide relay services to terminal device 10. However, since terminal device 30 does not support multi-hop relay, the path currently occupied by terminal device 20 cannot provide multi-hop relay services to terminal device 10. In this case, whether terminal device 20 can support establishing multi-hop relay links for terminal device 10, and how to establish multi-hop relay links for terminal device 10, is an unresolved issue.

[0140] In another possible scenario, terminal device 30 supports multi-hop relay, and terminal device 20 can act as an intermediate relay UE to provide relay services to terminal device 10. However, the network device 40 currently connected to terminal device 20 does not support multi-hop relay. Therefore, the path currently in which terminal device 20 is located cannot provide multi-hop relay services to terminal device 10. In this case, whether terminal device 20 can support establishing a multi-hop relay link for terminal device 10, and how to establish a multi-hop relay link for terminal device 10, is an unresolved issue.

[0141] In view of this, embodiments of this application provide a side-link communication method. When an intermediate relay UE that supports multi-hop relay is connected to a relay UE or network device that does not support multi-hop relay, the intermediate relay UE can still indicate the available multi-hop relay links to the remote UE based on the discovery process. After the remote UE selects a multi-hop relay link, the intermediate relay UE performs path change to provide multi-hop relay services to the remote UE.

[0142] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below through specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0143] Figure 4 is a schematic flowchart of a side-link communication method 400 provided in an embodiment of this application. The steps of method 400 can be executed by a terminal device (such as a first terminal device and a third terminal device). The steps executed by the terminal device can also be executed by a communication module in the terminal device, or by a circuit or chip in the terminal device that is responsible for communication functions. The following description takes the execution by the terminal device as an example.

[0144] In method 400, the first terminal device is an intermediate relay UE that supports multi-hop relay; in other words, the first terminal device supports providing multi-hop relay services to the remote UE as an intermediate relay UE. The first terminal device is, for example, terminal device 20 in Figure 1. The first terminal device communicates with the first network device through a second terminal device, for example, terminal device 30 in Figure 1, and the first network device is, for example, network device 40 in Figure 1. The third terminal device is the remote UE, requiring data transmission between the relay UE and the network device; the third terminal device is, for example, terminal device 10 in Figure 1.

[0145] In this application embodiment, a U2N relay UE refers to a relay UE connected to a network device, and an intermediate relay UE refers to a relay UE not directly connected to a network device, or a relay UE between a remote UE and a U2N relay UE.

[0146] In this embodiment, scenario one is considered: the second terminal device does not support multi-hop relay, and / or the first network device does not support multi-hop relay. The first terminal device can determine whether the first network device supports multi-hop relay based on system messages forwarded by the second terminal device.

[0147] Method 400 includes, but is not limited to, S401 to S403. Optionally, method 400 also includes S404 to S408. Each step is described in detail below.

[0148] S401, the third terminal device obtains information about the first multi-hop relay link.

[0149] In one possible scenario, the third terminal device is outside the network coverage area, or it is located at the edge of the cell with weak signal quality. Therefore, when the third terminal device has data transmission needs, it can use a relay node (or relay UE) to transmit data with the network device.

[0150] The first multi-hop trunk link is a multi-hop trunk link that provides multi-hop trunk services for third terminal devices. Information about the first multi-hop trunk link can be used to indicate the first multi-hop trunk link.

[0151] In one possible implementation, the third terminal device can obtain information about at least one multi-hop relay link, where the first multi-hop relay link is one of the at least one relay links. That is, the third terminal device selects the first multi-hop relay link from the at least one multi-hop relay link to provide multi-hop relay services.

[0152] The first multi-hop relay link may include multiple relay nodes, including a first terminal device and a fourth terminal device, with the fourth terminal device connected to a second network device.

[0153] The first terminal device and the fourth terminal device support multi-hop relay. The first terminal device and the fourth terminal device are adjacent relay nodes on the first multi-hop relay link. For example, from the uplink direction (i.e. from the first terminal device to the second network device), the fourth terminal device is the next-hop relay node of the first terminal device, while from the downlink direction (i.e. from the second network device to the first terminal device), the fourth terminal device is the previous-hop relay node of the first terminal device.

[0154] In one possible scenario, the fourth terminal device directly connects to the second network device, meaning the connection between the fourth terminal device and the second network device does not pass through other relay nodes, or in other words, it does not rely on other relay nodes. For example, in the schematic diagram of the multi-hop relay architecture shown in Figure 5, the first multi-hop relay link is: first terminal device ←→ fourth terminal device ←→ second network device. The third terminal device can communicate with the second network device through the first terminal device and the fourth terminal device. The first terminal device and the fourth terminal device are adjacent relay nodes on the first multi-hop relay link.

[0155] It should be understood that Figure 5 is illustrated by taking the second terminal device connected to the first network device and the fourth terminal device connected to the second network device as an example. When the second terminal device does not support multi-hop relay, but the first network device does support multi-hop relay, the first network device and the second network device can be the same network device, that is, the second terminal device and the fourth terminal device can be connected to the same network device that supports multi-hop relay.

[0156] In another possible scenario, the fourth terminal device connects to the second network device via other relay nodes. For example, the first multi-hop relay link is: first terminal device ←→ fourth terminal device ←→ fifth terminal device ←→ second network device. The third terminal device can communicate with the second network device through the first terminal device, the fourth terminal device, and the fifth terminal device. The first terminal device and the fourth terminal device are adjacent relay nodes on the first multi-hop relay link.

[0157] S402, the third terminal device sends first information to the first terminal device, the first information instructing the third terminal device to establish a connection with the network through the first multi-hop relay link. Accordingly, the first terminal device receives the first information.

[0158] In one possible implementation, the first information may include one or more of the following: the identifier of the first multi-hop relay link, the identifier of each terminal device on the first multi-hop link, or the path information of the first multi-hop link. In this way, the first terminal device can determine the first multi-hop relay link based on the first information, and then determine that the third terminal device expects to connect to the network through the first multi-hop relay link.

[0159] The path information of the first multi-hop link is, for example, the first terminal device ←→ the fourth terminal device ←→ the second network device, and the third terminal device can establish a connection with the second network device through the first multi-hop relay link.

[0160] S403, the first terminal device changes the path based on the first information.

[0161] It should be noted that the first terminal device is currently communicating with the first network device through the second terminal device. After receiving the first information, the first terminal device determines that the third terminal device expects to connect to the network through the first multi-hop relay link. Therefore, the first terminal device changes the path based on the first information.

[0162] Based on the technical solution of this application, the first terminal device can still support the multi-hop relay process even when the currently connected second terminal device and / or the first network device does not support multi-hop relay. Furthermore, when the third terminal device chooses to connect to the network through the first multi-hop relay link, the first terminal device changes the path, thereby providing multi-hop relay service to the third terminal device and improving the flexibility of the multi-hop relay service.

[0163] The following is a detailed description of how the first terminal device changes the path based on the first information.

[0164] When the first terminal device is in the RRC idle state or RRC inactive state, the first terminal device performs path changes based on the first information, including: the first terminal device releasing the connection with the second terminal device and establishing a connection between the first terminal device and the fourth terminal device.

[0165] When the first terminal device is in RRC connection state, as an example, there are two ways to implement path change for the first terminal device, as follows.

[0166] In one implementation method, the first terminal device performs a path change based on the first information, including: the first terminal device releasing the connection with the second terminal device, establishing a connection between the first terminal device and the fourth terminal device, and then sending second information to the fourth terminal device. This second information requests the establishment of a connection between the first terminal device and the second network device, where the second network device is the network device to which the fourth terminal device is connected. Subsequently, the fourth terminal device sends the second information to the second network device. After receiving the second information, if the AS security of the first terminal device has been activated through SRB2 and at least one DRB setting, and the second network device can find and verify the validity of the UE context of the first terminal device, then the second network device can initiate a reconstruction procedure and send a connection establishment completion message to the fourth terminal device. The fourth terminal device then sends this connection establishment completion message to the first terminal device.

[0167] As an example, the second message is an RRC re-establishment request message (RRCReestabilishmentRequest), and the second network device sends an RRC re-establishment completion message to the first terminal device through the fourth terminal device.

[0168] In the second implementation method, the first terminal device performs a path change based on the first information, including: the first terminal device sending first indication information related to multi-hop relay to the first network device, which is used to determine the path change for the first terminal device; and the first network device sending third information to the first terminal device based on the first indication information, which is used to instruct the first terminal device to perform the path change. Changing the path of the first terminal device can also be understood as changing the peer of the first terminal device's sidelink communication. In this application, the peer of the first terminal device's sidelink communication is changed from the second terminal device to the fourth terminal device. After receiving the third information, the first terminal device releases the connection with the second terminal device and establishes a connection between the first terminal device and the fourth terminal device based on the third information.

[0169] In one possible implementation, the first indication information is used to instruct the fourth terminal device to support multi-hop relay.

[0170] In one possible implementation, the first indication information is also used to indicate the need for multi-hop relay.

[0171] In one possible implementation, the first indication information may also include information about the fourth terminal device, such as one or more of the following: the L2 ID of the fourth terminal device, the identifier of the serving cell of the fourth terminal device, or the link signal quality between the fourth terminal device and the first terminal device.

[0172] As an example, if the number of terminal devices currently served by the serving cell of the fourth terminal device is small, the first network device determines that it can change the path of the first terminal device, that is, allow the first terminal device to establish a connection with the fourth terminal device; otherwise, the first network device determines that it will not change the path of the first terminal device. As an example, if the link signal quality between the fourth terminal device and the first terminal device is good, the first network device determines that it can change the path of the first terminal device, that is, allow the first terminal device to establish a connection with the fourth terminal device; otherwise, the first network device determines that it will not change the path of the first terminal device.

[0173] Since the first network device can only support a limited number of handover scenarios, such as supporting single-hop link handover but not multi-hop link handover, when the first terminal device is in RRC connection state, the first terminal device can determine whether to change the path through the above-mentioned implementation method two based on preset conditions.

[0174] In one possible implementation, if the first condition is met, the first terminal device performs a path change through the above-described implementation method one. The first condition includes: the number of relay hops between the first terminal device and the first network device is greater than or equal to a first threshold, and / or, the fourth terminal device is connected to the second network device through a relay node.

[0175] In one possible implementation, if the second condition is met, the first terminal device performs a path change through the above-described implementation method two. The second condition includes: the number of relay hops between the first terminal device and the first network device is less than a first threshold, and / or, the connection between the fourth terminal device and the second network device does not pass through a relay node.

[0176] As an example, with a first threshold of 2, in a multi-hop link switching scenario, the first terminal device can choose the above implementation method one to change the path, and in a single-hop link switching scenario, the first terminal device can choose the above implementation method two to change the path.

[0177] As an example, the first threshold is 3, meaning that the first network device supports the handover of multi-hop trunk links with a maximum trunk hop count of 3. If the trunk hop count exceeds 3, the first terminal device will use the RRC re-establishment method described in Implementation Method 1 to change the path.

[0178] The first terminal device can obtain information about the first multi-hop relay link through a discovery process. This discovery process includes two models: Model A and Model B. Further details about Model A and Model B can be found in the descriptions above and will not be elaborated upon here. The following section provides a detailed explanation of how the first terminal device obtains information about the first multi-hop relay link through the discovery process.

[0179] In the discovery process based on Model A, method 400 may further include S404: a fourth terminal device sends fourth information, the fourth information indicating that the fourth terminal device supports multi-hop relay, wherein the fourth terminal device is a relay node on the first multi-hop relay link. Correspondingly, the first terminal device receives the fourth information. Optionally, method 400 further includes S405: the first terminal device sends fifth information, the fifth information including information about the first multi-hop relay link, and correspondingly, the third terminal device receives the fifth information.

[0180] As an example, the fourth terminal device sends the fourth information via broadcast, and the first terminal device sends the fifth information via broadcast.

[0181] It should be understood that the fourth information is the information carried in the discovery message broadcast by the fourth terminal device, and the fifth information is the information carried in the discovery message broadcast by the first terminal device.

[0182] In one possible implementation, the fourth information also includes link information between the fourth terminal device and the second network device. As an example, the link information includes one or more of the following: the number of relay hops on the path from the fourth terminal device to the second network device, the link signal quality between adjacent terminal devices on the path from the fourth terminal device to the second network device, and the identifier of each terminal device on the path from the fourth terminal device to the second network device.

[0183] In one possible implementation, the fourth information also includes an RSC (Reference Scheme), which indicates the maximum number of trunk hops that the fourth terminal device can support. It should be understood that this RSC is a multi-hop trunk-related RSC, and the indicated maximum number of trunk hops can be greater than or equal to 2, that is, it can implicitly indicate that the fourth terminal device supports multi-hop trunk links. Alternatively, the fourth information includes a first field with a length of 1 bit, where 1 bit information can indicate that the fourth terminal device supports multi-hop trunks. For example, a bit state of "1" indicates support for multi-hop trunks, and a bit state of "0" indicates no support for multi-hop trunks.

[0184] The fourth terminal device can directly connect to the second network device, meaning the connection between the fourth terminal device and the second network device does not go through a relay node. For example, the path from the fourth terminal device to the second network device is: fourth terminal device ←→ second network device. The fourth terminal device can also connect to the second network device through a relay node (e.g., the fifth terminal device). For example, the path from the fourth terminal device to the second network device is: fourth terminal device ←→ fifth terminal device ←→ second network device.

[0185] After receiving the fourth information, the first terminal device sends the information of the first multi-hop relay link, wherein the first terminal device can determine the information of the first multi-hop relay link based on the fourth information.

[0186] In one possible implementation, the information of the first multi-hop trunk link includes one or more of the following: the identifier of each terminal device on the first multi-hop trunk link, the link signal quality between adjacent terminal devices on the first multi-hop trunk link, the path information of the first multi-hop trunk link, the maximum number of trunk hops that each terminal device on the first multi-hop trunk link can support, or the number of trunk hops of the first multi-hop trunk link.

[0187] It should be understood that, in one counting method, the number of relay hops in the first multi-hop relay link can be regarded as the number of relay nodes that need to be passed from the first terminal device to the second network device. As an example, the first multi-hop relay link is: first terminal device ←→ fourth terminal device ←→ second network device. The relay node that needs to be passed from the first terminal device to the second network device is the fourth terminal device. Therefore, the number of relay hops in the first multi-hop relay link is 1 hop.

[0188] It's also important to understand that different terminal devices may support different maximum number of relay hops. For example, the first terminal device can support a maximum of 3 relay hops, while the fourth terminal device can support a maximum of 2 relay hops.

[0189] In the discovery process based on Model B, method 400 may further include S406: the third terminal device sends a sixth message, the sixth message being used to request multi-hop relay service, wherein the sixth message may include the L2 ID of the third terminal device, and correspondingly, the first terminal device receives the sixth message. Further, method 400 may further include S407: the first terminal device sends a seventh message, the seventh message being used to request multi-hop relay service, wherein the seventh message may include the L2 ID of the first terminal device. In one possible approach, when the relay device (the second terminal device in Figure 5) or network device (the first network device in Figure 5) currently connected to the first terminal device does not support multi-hop relay, the first terminal device triggers the seventh message, which is used to request an available multi-hop relay path. Correspondingly, the fourth terminal device receives the seventh message. Subsequently, if the fourth terminal device supports multi-hop relay service, the fourth terminal device sends a fourth message, the fourth message being used to indicate that the fourth terminal device supports multi-hop relay, and correspondingly, the first terminal device receives the fourth message. Optionally, when the link signal quality between the first terminal device and the fourth terminal device exceeds or meets a certain threshold, a fourth message is triggered. The link signal quality between the first terminal device and the fourth terminal device can be measured by the fourth terminal device based on the seventh message. Then, the first terminal device obtains information about the first multi-hop relay link based on the fourth message and sends a fifth message, which includes the information about the first multi-hop relay link. Correspondingly, the third terminal device receives the fifth message. Optionally, when the link signal quality between the first terminal device and the fourth terminal device exceeds or meets a certain threshold, a fifth message is triggered. The link signal quality between the first terminal device and the fourth terminal device can be measured by the first terminal device based on the fourth message.

[0190] As an example, the third terminal device sends the sixth message via broadcast, and the first terminal device sends the seventh message via broadcast.

[0191] In one possible implementation, the fifth information includes information about at least one multi-hop trunk link, each of which can be used to provide trunk services, and the first multi-hop trunk link is one of these at least one multi-hop trunk links. For ease of description, the set including the at least one multi-hop trunk link will be referred to as the first multi-hop trunk link set below.

[0192] Before the first terminal device sends the fifth message, it can obtain information about at least one multi-hop relay link (hereinafter referred to as the second multi-hop relay link set) from discovery messages sent by at least one nearby terminal device. Then, the first terminal device sends information about the first multi-hop relay link set. After receiving the information about the first multi-hop relay link set, the third terminal device determines that it is connected to the network through the first multi-hop relay link in the first multi-hop relay link set.

[0193] In one possible implementation, the first terminal device determines the first multi-hop relay link set from the second multi-hop relay link set and sends the information of the first multi-hop relay link set to the third terminal device. That is, the second multi-hop relay link set contains the first multi-hop relay link set, which helps to reduce signaling overhead.

[0194] As an example, the first terminal device determines the first multi-hop trunk link set from the second multi-hop trunk link set, including: the first terminal device determines the first multi-hop trunk link set based on the link signal quality between adjacent terminal devices on each multi-hop trunk link in the second multi-hop trunk link set.

[0195] As an example, the first terminal device determines the first multi-hop relay link set based on the link signal quality between adjacent terminal devices on each multi-hop relay link in the second multi-hop relay link set, including: if the link signal quality between adjacent terminal devices on any multi-hop relay link in the second multi-hop relay link set is greater than or equal to a second threshold, then that multi-hop relay link is determined as a multi-hop relay link in the first multi-hop relay link set.

[0196] It should be understood that the first multi-hop trunk link is one of the multi-hop trunk links in the first multi-hop trunk link set. Therefore, the link signal quality between the first terminal device and the fourth terminal device on the first multi-hop trunk link is greater than or equal to the second threshold.

[0197] For example, the second set of multi-hop relay links includes multi-hop relay link #1, multi-hop relay link #2, and multi-hop relay link #3. Multi-hop relay link #1 is: Terminal device #1 ←→ Terminal device #2 ←→ Network device #1; multi-hop relay link #2 is: Terminal device #1 ←→ Terminal device #3 ←→ Terminal device #4 ←→ Network device #1; and multi-hop relay link #3 is: Terminal device #1 ←→ Terminal device #5 ←→ Network device #1. For multi-hop relay link #1, the link signal between terminal device #1 and terminal device #2... The quality is R1. For multi-hop trunk link #2, the link signal quality between terminal device #1 and terminal device #3 is R2, and the link signal quality between terminal device #3 and terminal device #4 is R3. For multi-hop trunk link #3, the link signal quality between terminal device #1 and terminal device #5 is R4. If R1 is greater than or equal to the second threshold, R2 and / or R3 are greater than or equal to the second threshold, and R3 is less than the second threshold, then the first multi-hop trunk link set includes multi-hop trunk link #1 and multi-hop trunk link #2, but does not include multi-hop trunk link #3.

[0198] It should be understood that, for the multi-hop relay link #2 in the above example, in one possible implementation, if at least one of R2 and R3 is greater than or equal to the second threshold, then the first multi-hop relay link set includes multi-hop relay link #2; conversely, if both R2 and R3 are less than the second threshold, then the first multi-hop relay link set does not include multi-hop relay link #2. In another possible implementation, if the average of R2 and R3 is greater than or equal to the second threshold, then the first multi-hop relay link set includes multi-hop relay link #2; conversely, if the average of R2 and R3 is less than the second threshold, then the first multi-hop relay link set does not include multi-hop relay link #2.

[0199] As an example, the link signal quality between adjacent terminal devices on a multi-hop relay link can be either the sidelink discovery reference signal received power (SD-RSRP) or the sidelink reference signal received power (SL-RSRP).

[0200] In one possible implementation, if the first network device currently connected to the first terminal device supports multi-hop relay, then before S405, the first network device sends an eighth message to the first terminal device. The eighth message includes a second threshold. Accordingly, the first terminal device receives the eighth message. Then, the first terminal device can determine the first multi-hop relay link set based on the eighth message and the link signal quality between adjacent terminal devices on each multi-hop relay link in the second multi-hop relay link set.

[0201] As an example, the eighth message is either a system message or an RRC configuration message.

[0202] In another possible implementation, if the first network device currently connected to the first terminal device does not support multi-hop relay, then the second threshold is pre-configured. Furthermore, the first terminal device can determine the first multi-hop relay link set based on the pre-configured second threshold and the link signal quality between adjacent terminal devices on each multi-hop relay link in the second multi-hop relay link set.

[0203] After determining the first set of multi-hop relay links, the first terminal device sends the fifth information, and correspondingly, the third terminal device receives the fifth information. Then, the third terminal device can choose to establish a connection with the second network device through one of the multi-hop relay links in the first set of multi-hop relay links. In this embodiment, the first multi-hop relay link is the multi-hop relay link selected by the third terminal device.

[0204] In one possible implementation, the first multi-hop relay link is the multi-hop relay link with the smallest number of relay hops in the first multi-hop relay link set. This results in a smaller transmission delay between the third terminal device and the second network device, and helps to avoid data loss.

[0205] For example, the first multi-hop relay link set includes multi-hop relay link #1 and multi-hop relay link #2. The path information of multi-hop relay link #1 is: terminal device #1 ←→ terminal device #2 ←→ network device #1, and the path information of multi-hop relay link #2 is: terminal device #1 ←→ terminal device #3 ←→ terminal device #4 ←→ network device #1. The number of relay hops in multi-hop relay link #1 is 1, and the number of relay hops in multi-hop relay link #2 is 2. The number of relay hops in multi-hop relay link #1 is less than the number of relay hops in multi-hop relay link #2. Therefore, the first multi-hop relay link is multi-hop relay link #1.

[0206] In another possible implementation, the first multi-hop relay link is the multi-hop relay link with the highest average link signal quality between adjacent terminal devices in the first multi-hop relay link set, which helps to improve the reliability of data transmission.

[0207] For example, the first multi-hop relay link set includes multi-hop relay link #1 and multi-hop relay link #2. The path information of multi-hop relay link #1 is: terminal device #1 ←→ terminal device #2 ←→ terminal device #3 ←→ network device #1. The path information of multi-hop relay link #2 is: terminal device #1 ←→ terminal device #4 ←→ terminal device #5 ←→ network device #1. The link signal quality between terminal device #1 and terminal device #2 is X1, the link signal quality between terminal device #2 and terminal device #3 is X2, and the average of X1 and X2 is X. The link signal quality between terminal device #1 and terminal device #4 is Y1, and the link signal quality between terminal device #4 and terminal device #5 is Y2, and the average of Y1 and Y2 is Y. If X is less than Y, then the first multi-hop relay link is multi-hop relay link #2.

[0208] After the third terminal device determines the first multi-hop relay link, it can establish a PC5 connection with the first terminal device. The specific process of establishing a PC5 connection can be found in the description of the unicast connection establishment process above, and will not be repeated here.

[0209] In one possible implementation, method 400 further includes S408: the third terminal device sends a ninth message to the first terminal device, the ninth message being used to request the establishment of a connection with the first terminal device. The ninth message can also be described as a connection establishment request message. S408 can be executed after S401.

[0210] In one possible implementation, the ninth information may also include one or more of the following: the identifier of each terminal device on the first multi-hop trunk link, the link signal quality between adjacent terminal devices on the first multi-hop trunk link, the path information of the first multi-hop trunk link, the maximum number of trunk hops that each terminal device on the first multi-hop trunk link can support, or the number of trunk hops of the first multi-hop trunk link.

[0211] It should be noted that the third terminal device may instruct the first terminal device to connect to the network via the first multi-hop relay link during the connection establishment process; that is, the ninth information may be the same as the first information. Alternatively, the third terminal device may send the first information to the first terminal device after the connection with the first terminal device is established; that is, the ninth information may be sent before the first information.

[0212] Referring to the description of the discovery process based on Model B above, the third terminal device sends a sixth message, which requests multi-hop relay service. This sixth message may include the third terminal device's L2 ID. Based on this, in one possible implementation, the ninth message may also include the third terminal device's L2 ID. After receiving the ninth message, the first terminal device, combining it with the L2 ID in the sixth message, can determine that the L2 ID in the ninth message indicates that the currently established PC5 connection is used to provide multi-hop relay service for the third terminal device.

[0213] The above describes how a first terminal device provides multi-hop relay service to a third terminal device in Scenario 1. Scenario 1 involves the third terminal device communicating with a first network device via a second terminal device, where the second terminal device and / or the first network device do not support multi-hop relay. In Scenario 1, the link from the first terminal device to the second terminal device and then to the first network device cannot provide multi-hop relay service to the third terminal device. Therefore, the first terminal device can obtain information about at least one available multi-hop relay link through a discovery process and broadcast this information. Each of these at least one multi-hop relay links can be used to provide relay service.

[0214] As described above, after the third terminal device sends the first information, it will trigger the first terminal device to make path changes, including reselection of the relay UE or re-establishment of RRC. This will bring additional overhead to the first terminal device, especially when the first terminal device is in RRC connection state, which may cause service interruption of the first terminal device. Therefore, it is advisable to reduce unnecessary overhead through constraints.

[0215] In one possible implementation, when the first terminal device is in RRC connected state, if the relay UE connected to the first terminal device (such as the second terminal device mentioned above) does not support multi-hop relay, the first terminal device may not execute the multi-hop relay-related procedures (including the discovery procedure), including not executing the above-mentioned technical solutions. For example, it may not broadcast multi-hop link information or respond to the solicitation message from the third terminal device. That is, when the first terminal device is in RRC disconnected state (such as RRC idle state or RRC inactive state), if the relay UE connected to the first terminal device (such as the second terminal device mentioned above) does not support multi-hop relay, the first terminal device may execute the multi-hop relay-related procedures (including the discovery procedure), including executing the above-mentioned technical solutions.

[0216] In another possible implementation, regardless of whether the first terminal device is in RRC connected state or RRC disconnected state, if the relay UE connected to the first terminal device (such as the second terminal device mentioned above) does not support multi-hop relay, then the first terminal device does not support the multi-hop relay related process. That is to say, the first terminal device only executes the multi-hop relay related process when the relay UE connected to the first terminal device supports multi-hop relay, and indicates the current path in the discovery message.

[0217] Consider scenario two: A first terminal device communicates with a first network device via a second terminal device, where the second terminal device and the first network device support multi-hop relay. In scenario two, the link from the first terminal device to the second terminal device to the first network device can provide multi-hop relay service for a third terminal device. The following describes how the first terminal device provides multi-hop relay service to the third terminal device in scenario two.

[0218] In one possible implementation, the first terminal device can send indication information (e.g., a discovery message) to the third terminal device to indicate that the first terminal device supports multi-hop relay, that is, to indicate that the third terminal device can establish a multi-hop relay path through the first terminal device and the network. The indication information may include hop count information between the first terminal device and the network device. Alternatively, the first terminal device can send information about the currently connected multi-hop relay link to the third terminal device, designating this link as the second multi-hop relay link. For example, the second multi-hop relay link might be: first terminal device ←→ second terminal device ←→ first network device. After receiving the information about the second multi-hop relay link, the third terminal device can determine that it is connected to the network through the second multi-hop relay link. This implementation has less indication overhead, and since the second multi-hop relay link has already been established, the latency for the third terminal device to access the network can be reduced. In this implementation, when the first terminal device receives the sixth message from the third terminal device, it does not trigger the seventh message but directly replies with the fifth message, which indicates the information about the second multi-hop relay link. Based on the fifth piece of information, the third terminal device triggers the establishment of a connection with the first terminal device and triggers the access process with the network, meaning that steps S402 and S403 are no longer needed.

[0219] In another possible implementation, the first terminal device can send information about the second multi-hop relay link and information about at least one multi-hop relay link (such as the first multi-hop relay link set mentioned above) obtained based on the discovery process to the third terminal device. This provides the third terminal device with more options, making the selection of multi-hop relay links more flexible. The following description uses the third multi-hop relay link obtained by the first terminal device based on the discovery process as an example. As an example, the third multi-hop relay link is: First terminal device ←→ Sixth terminal device ←→ First network device.

[0220] After receiving the second and third multi-hop relay links, the third terminal device can choose to establish a connection with the first network device through one of the multi-hop relay links.

[0221] Since the reselection or RRC re-establishment of relay UEs can affect the services of third-party terminal devices and increase the latency of third-party terminal devices accessing the network, third-party terminal devices can give priority to selecting pre-established multi-hop relay links.

[0222] In one possible implementation, when the first terminal device discovers information about the second and third multi-hop relay links in the discovery message, it can also indicate that the second multi-hop relay link has been established but the third multi-hop relay link has not been established. Therefore, the third terminal device can preferentially choose to connect to the network through the already established second multi-hop relay link, which helps reduce the latency of the third terminal device accessing the network. Similarly, in the above scenario one, when the first terminal device carries the information about the first multi-hop relay link in the fifth message, it can also carry second indication information related to multi-hop relays. This second indication information is used to indicate that the first terminal device has not established a connection with the fourth terminal device, or that the first multi-hop relay link has not been established. In this way, after receiving multiple multi-hop relay link information sent by multiple nearby terminal devices, the third terminal device can choose to connect to the network through one of the established multi-hop relay links.

[0223] In one possible implementation, the first terminal device can also indicate its RRC status in the discovery message. When the first terminal device is in the RRC connected state, the third terminal device can select an established multi-hop trunk link. When the first terminal device is in the RRC disconnected state, the third terminal device can select an unestablished trunk link. This has a smaller impact on the services of the first terminal device.

[0224] The information on the second and third multi-hop relay links sent by the first terminal device contains similar content to the information on the first multi-hop relay link described above, such as the number of relay hops and the link signal quality between adjacent terminal devices, etc., which will not be repeated here.

[0225] After receiving information about multiple multi-hop relay links from the first terminal device, the third terminal device can select one of the multi-hop relay links and instruct the first terminal device to connect to the network through the selected multi-hop relay link. If the first terminal device does not establish the selected multi-hop relay link, the path change step as in Scenario 1 is triggered. For example, the path change can be performed by triggering the reselection of the relay UE, or by triggering RRC re-establishment, or by instructing the network device to switch paths. For details, please refer to the description of Scenario 1 above, which will not be repeated here.

[0226] It should be understood that the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0227] The side link communication method according to an embodiment of the present application has been described in detail above with reference to FIG4. The communication device according to an embodiment of the present application will be described in detail below with reference to FIG6 and FIG7.

[0228] As shown in Figure 6, the communication device 600 includes a transceiver module 610 and a processing module 620. The processing module 620 is used for data processing, and the transceiver module 610 can also be referred to as a communication interface or a communication module.

[0229] The device 600 can be used to perform the actions performed by the terminal device (e.g., the first terminal device, the third terminal device, the fourth terminal device) or the network device (e.g., the first network device or the second network device) in the above method embodiments. Alternatively, the device 600 can be a component (e.g., a chip) configured in the terminal device or the network device. The processing module 620 is used to perform processing-related operations of the terminal device or the network device in the above method embodiments. The transceiver module 610 is used to perform receiving and transmitting-related operations of the terminal device or the network device in the above method embodiments.

[0230] Optionally, the transceiver module 610 may include a sending module and a receiving module. The sending module is used to perform the sending operation in the above method embodiments. The receiving module is used to perform the receiving operation in the above method embodiments.

[0231] It should be noted that device 600 may include a transmitting module but not a receiving module. Alternatively, device 600 may include a receiving module but not a transmitting module. Specifically, it depends on whether the above-described scheme executed by device 600 includes both transmitting and receiving actions.

[0232] Optionally, the device 600 is used to perform the actions performed by the terminal device or network device in the above embodiments. For details, please refer to the relevant descriptions in the above embodiments; they will not be repeated here.

[0233] Optionally, the device 600 may further include a storage module, which can be used to store data and / or to store computer programs or instructions. The processing module 620 can read the computer programs / instructions and / or data in the storage module so that the device 600 can implement the above-described method embodiments.

[0234] When device 600 is used to implement the function of the first terminal device in the method embodiment shown in FIG4, transceiver module 610 is used to: receive first information from third terminal device, the first information being used to instruct the third terminal device to connect to the network through a first multi-hop relay link; processing module 620 is used to: perform path modification based on the first information.

[0235] Optionally, the transceiver module 610 is configured to: send second information to the fourth terminal device, the second information being used to request the establishment of a connection between the first terminal device and the second network device.

[0236] Optionally, the transceiver module 610 is configured to: send the second information to the fourth terminal device when a first condition is met, the first condition including: the number of relay hops between the first terminal device and the first network device is greater than or equal to a first threshold, and / or, the fourth terminal device is connected to the second network device through a relay node.

[0237] Optionally, the transceiver module 610 is configured to: send first indication information related to multi-hop relay to the first network device; and receive third information from the first network device, the third information being used to instruct the first terminal device to make a path change.

[0238] Optionally, the transceiver module 610 is configured to: send first indication information related to multi-hop relay to the first network device when a second condition is met, the second condition including: the number of relay hops between the first terminal device and the first network device is less than or equal to a first threshold, and / or, the connection between the fourth terminal device and the second network device does not pass through a relay node.

[0239] Optionally, the transceiver module 610 is configured to: receive fourth information from the fourth terminal device, the fourth information indicating that the fourth terminal device supports multi-hop relay, the fourth terminal device being a relay node on the first multi-hop relay link; and send information about the first multi-hop relay link.

[0240] Optionally, the transceiver module 610 is configured to: receive a sixth message from a third terminal device, the sixth message being used to request multi-hop relay service; and send a seventh message, the seventh message being used to request multi-hop relay service.

[0241] Optionally, the transceiver module 610 is configured to: receive eighth information from the first network device, the eighth information including a second threshold.

[0242] When device 600 is used to implement the function of the third terminal device in the method embodiment shown in FIG4, processing module 620 is used to: obtain information of the first multi-hop relay link; transceiver module 610 is used to: send first information to the first terminal device, the first information being used to instruct the third terminal device to connect to the network through the first multi-hop relay link.

[0243] Optionally, the transceiver module 610 is used to: receive information from the first multi-hop relay link.

[0244] Optionally, the transceiver module 610 is used to: send a ninth message, which is used to request the establishment of a connection with the first terminal device.

[0245] For a more detailed description of the transceiver module 610 and the processing module 620, please refer to the relevant description in the method embodiment shown in Figure 4, which will not be repeated here.

[0246] Figure 7 is a schematic block diagram of another communication device 700 provided in an embodiment of this application. As shown in Figure 7, the device 700 includes one or more processors 710 and an interface circuit 720. The one or more processors 710 and the interface circuit 720 are coupled to each other. It is understood that the interface circuit 720 can be a transceiver or an input / output interface. Optionally, the device 700 may also include a memory 730 for storing instructions executed by the processor 710, or for storing input data required by the processor 710 to execute instructions, or for storing data generated after the processor 710 executes instructions. Sometimes, the interface circuit 720 can also be understood as part of the one or more processors 710, in which case the device 700 includes the one or more processors 710.

[0247] The one or more processors 710 and memory 730 can be configured separately or integrated, and this application does not limit this.

[0248] When the device 700 is used to implement the method shown in FIG4, the one or more processors 710 are used to implement the functions of the processing module 620, and the interface circuit 720 is used to implement the functions of the transceiver module 610.

[0249] When the aforementioned device 700 is a chip applied to a terminal device, the chip of the terminal device implements the functions of the terminal device in the above method embodiments. The chip of the terminal device receives information from the network device, which can be understood as the information being first received by other modules (such as an RF module or antenna) in the terminal device, and then sent to the chip of the terminal device by these modules. The chip of the terminal device sends information to the network device, which can be understood as the information being first sent to other modules (such as an RF module or antenna) in the terminal device, and then sent to the network device by these modules.

[0250] When the aforementioned device 700 is a chip applied to a network device, the chip of the network device implements the functions of the network device in the above method embodiments. The chip of the network device receives information from the terminal device, which can be understood as the information being first received by other modules (such as radio frequency modules or antennas) in the network device, and then sent to the chip of the network device by these modules. The chip of the network device sends information to the terminal device, which can be understood as the information being first sent to other modules (such as radio frequency modules or antennas) in the network device, and then sent to the terminal device by these modules.

[0251] This application also provides a computer-readable storage medium for storing a computer program that, when run on a computer, causes the computer to perform the methods described in the above embodiments. Alternatively, the computer program includes instructions for implementing the methods described in the above embodiments.

[0252] This application also provides a computer program product, including: a computer program or instructions that, when run on a computer, cause the computer to perform the methods described above.

[0253] This application also provides an apparatus, which can be a chip, including at least one processor for supporting the implementation of the methods in the above embodiments, such as receiving or processing data involved in the methods in the above embodiments.

[0254] It should be understood that, in the embodiments of this application, the processor can be a central processing unit, or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0255] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly manifested as execution by a hardware processor, or as a combination of hardware and software modules within the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor executes the instructions in the memory, combining them with its hardware to complete the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0256] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0257] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0258] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0259] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0260] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0261] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, external hard drives, ROM, RAM, magnetic disks, or optical disks.

[0262] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of sidelink communication, comprising: The method, applied to a first terminal device that supports multi-hop relay, and which communicates with a first network device via a second terminal device, includes: Receive first information from a third terminal device, the first information being used to instruct the third terminal device to connect to the network through a first multi-hop relay link; Based on the first information, the path is changed.

2. The method as described in claim 1, characterized in that, The path change based on the first information includes: Release the connection between the first terminal device and the second terminal device; A connection is established between the first terminal device and the fourth terminal device, wherein the fourth terminal device is a relay node on the first multi-hop relay link.

3. The method as described in claim 2, characterized in that, The method further includes: Send a second message to the fourth terminal device. The second message is used to request the establishment of a connection between the first terminal device and the second network device, where the second network device is the network device to which the fourth terminal device is connected.

4. The method as described in claim 3, characterized in that, Sending the second information to the fourth terminal device includes: If the first condition is met, the second information is sent to the fourth terminal device. The first condition includes: the number of relay hops between the first terminal device and the first network device is greater than or equal to a first threshold, and / or the fourth terminal device is connected to the second network device through a relay node.

5. The method as described in claim 2, characterized in that, The method further includes: Send first indication information related to multi-hop relay to the first network device; The device receives third information from the first network device, the third information being used to instruct the first terminal device to make a path change.

6. The method as described in claim 5, characterized in that, The first indication information related to the multi-hop relay also includes one or more of the following: The layer 2 identifier of the fourth terminal device, the identifier of the serving cell of the fourth terminal device, or the link signal quality between the fourth terminal device and the first terminal device.

7. The method as described in claim 5 or 6, characterized in that, The first indication information related to multi-hop relay is used to indicate that the fourth terminal device supports multi-hop relay.

8. The method according to any one of claims 5 to 7, characterized in that, The first indication information related to the multi-hop relay is also used to indicate the need for multi-hop relay.

9. The method according to any one of claims 5 to 8, characterized in that, Sending the first indication information related to multi-hop relay to the first network device includes: If the second condition is met, send the first indication information related to the multi-hop relay to the first network device; The second condition includes: the number of relay hops between the first terminal device and the first network device is less than or equal to the first threshold, and / or the connection between the fourth terminal device and the second network device does not pass through a relay node.

10. The method according to any one of claims 1 to 9, characterized in that, The method further includes: Receive fourth information from a fourth terminal device, the fourth information being used to indicate that the fourth terminal device supports multi-hop relay, the fourth terminal device being a relay node on the first multi-hop relay link; Send a fifth message, which includes information about the first multi-hop relay link.

11. The method as described in claim 10, characterized in that, The fourth information also includes link information between the fourth terminal device and the second network device.

12. The method as described in claim 10 or 11, characterized in that, The fourth information also includes a relay service code (RSC), which indicates the maximum number of relay hops that the fourth terminal device can support.

13. The method according to any one of claims 10 to 12, characterized in that, The information of the first multi-hop relay link includes one or more of the following: The identifier of each terminal device on the first multi-hop relay link; The link signal quality between adjacent terminal devices on the first multi-hop relay link; The path information of the first multi-hop relay link; The maximum number of hops that each terminal device on the first multi-hop relay link can support; or, The number of hops in the first multi-hop relay link.

14. The method according to any one of claims 10 to 13, characterized in that, The fifth information also includes second indication information, which is used to indicate that the first terminal device has not established a connection with the fourth terminal device, or that the first multi-hop relay link has not been established.

15. The method according to any one of claims 10 to 14, characterized in that, The method further includes: Receive sixth information from the third terminal device, the sixth information being used to request multi-hop relay service; Send a seventh message, which is used to request multi-hop relay service.

16. The method according to any one of claims 10 to 15, characterized in that, The fifth piece of information includes information about at least one multi-hop relay link, each of which can be used to provide relay services, and the first multi-hop relay link is one of the at least one multi-hop relay links.

17. The method according to any one of claims 10 to 16, characterized in that, The link signal quality between the first terminal device and the fourth terminal device is greater than or equal to the second threshold.

18. The method as described in claim 17, characterized in that, The first network device supports multi-hop relay, and the method further includes: Receive eighth information from the first network device, the eighth information including the second threshold.

19. The method as described in claim 17, characterized in that, The first network device does not support multi-hop relay, and the second threshold is pre-configured.

20. The method as described in claim 1 or 2, characterized in that, The first terminal device is in the Radio Resource Control (RRC) idle state or the RRC inactive state.

21. A side-link communication method, characterized in that, Applied to a third terminal device, the method includes: Obtain information about the first multi-hop relay link; Send first information to the first terminal device, the first information being used to instruct the third terminal device to establish a connection with the network through the first multi-hop relay link.

22. The method as described in claim 21, characterized in that, The method further includes: The system receives fifth information from the first terminal device, the fifth information including information about the first multi-hop relay link.

23. The method as described in claim 22, characterized in that, The method further includes: Send a sixth message, which is used to request multi-hop relay service.

24. The method as described in claim 22 or 23, characterized in that, The fifth piece of information includes information about at least one multi-hop relay link, each of which can be used to provide relay services for the third terminal device, and the first multi-hop relay link is one of the at least one multi-hop relay links.

25. The method according to any one of claims 21 to 24, characterized in that, The method further includes: A ninth message is sent to the first terminal device, the ninth message being used to request the establishment of a connection with the first terminal device.

26. The method as described in claim 25, characterized in that, The ninth piece of information also includes one or more of the following: The identifier of each terminal device on the first multi-hop relay link; The link signal quality between adjacent terminal devices on the first multi-hop relay link; The path information of the first multi-hop relay link; The maximum number of relay hops that each terminal device on the first multi-hop relay link can support; or, The number of relay hops in the first multi-hop relay link.

27. A communication device, characterized in that, It includes modules for implementing the method as described in any one of claims 1 to 20, or modules for implementing the method as described in any one of claims 21 to 26.

28. A communication device, characterized in that, The device includes a processor coupled to a memory for storing programs or instructions that, when executed by the processor, cause the method as claimed in any one of claims 1 to 20 to be performed, or cause the method as claimed in any one of claims 21 to 26 to be performed.

29. A computer-readable storage medium, characterized in that, Used to store a computer program that, when run on a computer, causes the method as described in any one of claims 1 to 20 to be performed, or causes the method as described in any one of claims 21 to 26 to be performed.

30. A computer program product, characterized in that, include: A computer program or instruction that, when executed, causes the method as claimed in any one of claims 1 to 20 to be performed, or causes the method as claimed in any one of claims 21 to 26 to be performed.

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