Relay communication method and device

Abstract

The invention relates to a relay communication method and device, and the method comprises the steps: a first terminal selects a relay terminal meeting the demands of the first terminal based on a first triggering condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to a link state. According to the embodiment of the invention, the relay selection can be triggered based on the triggering condition, so that a multi-hop relay link can be formed, and the communication reliability and the communication range can be improved.

Description

Relay communication method and device Technical Field

[0001] The present application relates to the field of communications, and more specifically, to a relay communication method and device. Background Art

[0002] With the development of wireless communication technology, the 3rd Generation Partnership Project (3GPP) introduced relays. Remote terminals can connect to the network through relays, such as a User Equipment (UE) to Network (U2N) relay. Source and destination terminals can also connect through relays, such as a User Equipment (UE) to User Equipment (U2U) relay. Communication based on relays can extend communication distance and improve reliability.

[0003] Summary of the Invention

[0004] The embodiments of the present application provide a relay communication method and device, which can improve communication reliability and communication range.

[0005] An embodiment of the present application provides a relay communication method, including: a first terminal selects a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

[0006] An embodiment of the present application provides a relay communication method, including: a second terminal sends a link status; wherein the link status is related to a first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

[0007] An embodiment of the present application provides a first terminal, comprising: a processing unit, configured to select a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

[0008] An embodiment of the present application provides a second terminal, including: a sending unit, used to send a link status; wherein the link status is related to a first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

[0009] An embodiment of the present application provides a terminal device, comprising a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory, so that the terminal device executes the above-mentioned relay communication method.

[0010] The embodiment of the present application provides a chip for implementing the above-mentioned relay communication method. Specifically, the chip includes: a processor for calling and running a computer program from a memory, so that a device equipped with the chip executes the above-mentioned relay communication method.

[0011] An embodiment of the present application provides a computer-readable storage medium for storing a computer program. When the computer program is executed by a device, the device executes the above-mentioned relay communication method.

[0012] An embodiment of the present application provides a computer program product, including computer program instructions, which enable a computer to execute the above-mentioned relay communication method.

[0013] An embodiment of the present application provides a computer program, which, when executed on a computer, enables the computer to execute the above-mentioned relay communication method.

[0014] In the embodiment of the present application, the selection of the relay triggered based on the trigger condition can form a multi-hop relay link, which can improve the communication reliability and communication range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic diagram of an application scenario according to an embodiment of the present application.

[0016] FIG2A is a schematic diagram of 3GPP transmission mode 3. FIG.

[0017] FIG2B is a schematic diagram of 3GPP transmission mode 4. FIG.

[0018] FIG3 is a schematic diagram of UE-to-UE relay.

[0019] FIG4 is a schematic diagram of a flow chart of establishing a UE-to-UE relay connection.

[0020] FIG5 is a schematic diagram of a UE architecture in a UE-to-UE relay.

[0021] FIG6 is a schematic flowchart of a relay communication method according to an embodiment of the present application.

[0022] FIG7 is a schematic flowchart of a relay communication method according to another embodiment of the present application.

[0023] FIG8 is a schematic flowchart of a relay communication method according to another embodiment of the present application.

[0024] FIG9 is a schematic flowchart of a relay communication method according to an embodiment of the present application.

[0025] FIG10 is a schematic flowchart of centralized relay selection / reselection according to the second embodiment of the present application.

[0026] Figure 11 is a schematic flowchart of distributed relay selection / reselection according to embodiment 3 of the present application.

[0027] FIG12 is a schematic block diagram of a first terminal according to an embodiment of the present application.

[0028] FIG13 is a schematic block diagram of a first terminal according to another embodiment of the present application.

[0029] FIG14 is a schematic block diagram of a second terminal according to an embodiment of the present application.

[0030] FIG15 is a schematic structural diagram of a communication device according to an embodiment of the present application.

[0031] FIG16 is a schematic block diagram of a chip according to an embodiment of the present application.

[0032] FIG17 is a schematic block diagram of a communication system according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0034] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: Global System of Mobile communication (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, Advanced Long Term Evolution (LTE-A) system, New Radio (NR) system, NR system evolution system, LTE on unlicensed spectrum (LTE-U) system, NR on unlicensed spectrum (NR-U) system, Non-Terrestrial Networks (NTN) system, Universal Mobile Telecommunication System (UMTS), Wireless Local Area Networks (WLAN), Wireless Fidelity (Wireless Fidelity) system. Fidelity, WiFi), fifth-generation communication (5th-Generation, 5G) system or other communication systems, etc.

[0035] Generally speaking, traditional communication systems support a limited number of connections and are easy to implement. However, with the development of communication technology, mobile communication systems will not only support traditional communications, but will also support, for example, device-to-device (D2D) communication, machine-to-machine (M2M) communication, machine-type communication (MTC), vehicle-to-vehicle (V2V) communication, or vehicle-to-everything (V2X) communication, etc. The embodiments of the present application can also be applied to these communication systems.

[0036] In one embodiment, the communication system in the embodiment of the present application can be applied to a carrier aggregation (CA) scenario, a dual connectivity (DC) scenario, and a standalone (SA) networking scenario.

[0037] In one embodiment, the communication system in the embodiment of the present application can be applied to an unlicensed spectrum, wherein the unlicensed spectrum can also be considered as a shared spectrum; or, the communication system in the embodiment of the present application can also be applied to an authorized spectrum, wherein the authorized spectrum can also be considered as an unshared spectrum.

[0038] The embodiments of the present application describe various embodiments in conjunction with network devices and terminal devices, wherein the terminal device may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, etc.

[0039] The terminal device can be a station (STAION, ST) in a WLAN, a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA) device, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a next-generation communication system such as an NR network, or a terminal device in a future evolved Public Land Mobile Network (PLMN) network, etc.

[0040] In an embodiment of the present application, the terminal device can be deployed on land, including indoors or outdoors, handheld, wearable or vehicle-mounted; it can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (such as airplanes, balloons and satellites, etc.).

[0041] In an embodiment of the present application, the terminal device may be a mobile phone, a tablet computer, a computer with wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in industrial control, a wireless terminal device in self-driving, a wireless terminal device in remote medical, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, or a wireless terminal device in a smart home, etc.

[0042] As an example and not a limitation, in the embodiment of the present application, the terminal device may also be a wearable device. Wearable devices may also be called wearable smart devices, which are a general term for wearable devices that are intelligently designed and developed using wearable technology for daily wear, such as glasses, gloves, watches, clothing, and shoes. A wearable device is a portable device that is worn directly on the body or integrated into the user's clothes or accessories. Wearable devices are not only hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those that are fully functional, large in size, and can achieve complete or partial functions without relying on smartphones, such as smart watches or smart glasses, as well as those that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0043] In an embodiment of the present application, the network device may be a device for communicating with a mobile device. The network device may be an access point (AP) in WLAN, a base station (BTS) in GSM or CDMA, a base station (NodeB, NB) in WCDMA, an evolved base station (eNB or eNodeB) in LTE, or a relay station or access point, or a vehicle-mounted device, a wearable device, and a network device (gNB) in an NR network, or a network device in a future evolved PLMN network or a network device in an NTN network, etc.

[0044] As an example and not a limitation, in an embodiment of the present application, the network device may have a mobile feature, for example, the network device may be a mobile device. Alternatively, the network device may be a satellite or a balloon station. For example, the satellite may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, etc. Optionally, the network device may also be a base station set up in a location such as land or water.

[0045] In an embodiment of the present application, the network device can provide services for a cell, and the terminal device communicates with the network device through the transmission resources used by the cell (for example, frequency domain resources, or spectrum resources). The cell can be a cell corresponding to the network device (for example, a base station). The cell can belong to a macro base station or a base station corresponding to a small cell. The small cells here may include: metro cells, micro cells, pico cells, femto cells, etc. These small cells have the characteristics of small coverage and low transmission power, and are suitable for providing high-speed data transmission services.

[0046] FIG1 exemplarily illustrates a communication system 100. The communication system includes a network device 110 and two terminal devices 120. In one embodiment, the communication system 100 may include multiple network devices 110, and each network device 110 may include a different number of terminal devices 120 within its coverage area, which is not limited in this embodiment of the present application.

[0047] In one embodiment, the communication system 100 may further include other network entities such as a Mobility Management Entity (MME) and an Access and Mobility Management Function (AMF), which is not limited in this embodiment of the present application.

[0048] Among them, the network equipment may include access network equipment and core network equipment. That is, the wireless communication system also includes multiple core networks for communicating with the access network equipment. The access network equipment can be an evolutionary base station (evolutional node B, abbreviated as eNB or e-NodeB) macro base station, micro base station (also called "small base station"), pico base station, access point (AP), transmission point (TP) or new generation base station (new generation Node B, gNodeB), etc. in a long-term evolution (LTE) system, a next-generation (mobile communication system) (next radio, NR) system or an authorized auxiliary access long-term evolution (LAA-LTE) system.

[0049] It should be understood that in the embodiments of the present application, a device having a communication function in a network / system may be referred to as a communication device. Taking the communication system shown in Figure 1 as an example, the communication device may include a network device and a terminal device having a communication function. The network device and the terminal device may be specific devices in the embodiments of the present application and will not be described in detail here. The communication device may also include other devices in the communication system, such as a network controller, a mobility management entity, and other network entities, which are not limited in the embodiments of the present application.

[0050] It should be understood that the terms "system" and "network" are often used interchangeably herein. The term "and / or" is simply a description of an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " generally indicates that the related objects are in an "or" relationship.

[0051] It should be understood that the "indication" mentioned in the embodiments of this application can be a direct indication, an indirect indication, or an indication of an association. For example, "A indicates B" can mean that A directly indicates B, for example, B can be obtained through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can be obtained through C; it can also mean that there is an association between A and B.

[0052] In the description of the embodiments of the present application, the term "corresponding" may indicate a direct or indirect correspondence between the two, or an association relationship between the two, or a relationship between indication and indication, configuration and configuration, etc.

[0053] To facilitate understanding of the technical solutions of the embodiments of the present application, the relevant technologies of the embodiments of the present application are described below. The following relevant technologies can be arbitrarily combined with the technical solutions of the embodiments of the present application as optional solutions, and they all fall within the protection scope of the embodiments of the present application.

[0054] 1. Long Term Evolution (LTE) Device to Device (D2D) / V2X

[0055] Device-to-device communication is a sidelink (SL) transmission technology based on D2D. Unlike traditional cellular systems where communication data is received or sent through base stations, the Internet of Vehicles system uses direct terminal-to-terminal communication, resulting in higher spectrum efficiency and lower transmission latency.

[0056] 3GPP includes two transmission modes: Mode 3 and Mode 4.

[0057] Mode 3: As shown in Figure 2A, the terminal's transmission resources are allocated by the base station, and the terminal transmits data on the sidelink based on the allocated resources. The base station can allocate resources for a single transmission or for semi-static transmission.

[0058] Mode 4: As shown in FIG2B , the vehicle terminal selects a resource in the resource pool for data transmission.

[0059] In 3GPP, D2D includes different phases:

[0060] (1) Proximity-based Service (ProSe): In Rel-12 / 13, device-to-device communication is studied for ProSe scenarios, mainly targeting public safety services.

[0061] In proximity services, by configuring the location of resource pools in the time domain, for example, the resource pools are discontinuous in the time domain, the UE can transmit / receive data discontinuously on the sidelink, thereby achieving power saving.

[0062] (2) Internet of Vehicles: In Rel-14 / 15, the Internet of Vehicles system was studied for vehicle-to-vehicle communication scenarios, mainly for relatively high-speed vehicle-to-vehicle and vehicle-to-person communication services;

[0063] In V2X, since the on-board system has continuous power supply, power efficiency is not the main issue, but the delay of data transmission is the main issue. Therefore, the system design requires the terminal equipment to perform continuous transmission and reception.

[0064] (3) Wearable devices, further enhanced device-to-device (FeD2D): In Rel-14, this topic studies the scenario of wearable devices accessing the network through mobile phones, mainly targeting scenarios with low mobile speed and low power access.

[0065] In FeD2D, during the pre-research phase, 3GPP concluded that a base station could configure the discontinuous reception (DRX) parameters of a remote terminal through a relay terminal. However, because the topic did not enter the standardization phase, the specific details of how to perform DRX configuration have not been finalized.

[0066] NR V2X

[0067] Based on LTE V2X, NR V2X is not limited to broadcast scenarios, but has been further expanded to unicast and multicast scenarios, and the application of V2X is studied in these scenarios.

[0068] Similar to LTE V2X, NR V2X also includes two resource authorization modes: Mode-1 and Mode-2. Furthermore, a user may be in a mixed mode, that is, they can use Mode-1 to acquire resources and Mode-2 to acquire resources at the same time. The resource acquisition is indicated by the sidelink grant, that is, the sidelink grant indicates the time-frequency position of the corresponding Physical Sidelink Control Channel (PSCCH) and Physical Sidelink Shared Channel (PSSCH) resources.

[0069] Unlike LTE V2X, in addition to the feedback-free, UE-initiated Hybrid Automatic Repeat-reQuest (HARQ) retransmission, NR V2X introduces feedback-based HARQ retransmission, which is not limited to unicast communication but also includes multicast communication.

[0070] 3. Side-by-side UE-2-UE relay technology

[0071] As shown in Figure 3, in Rel-17 ProSe, 3GPP includes a U2U (UE-to-UE) relay function based on Layer 2 and Layer 3 relays. That is, the source UE connects to the target UE through the relay UE, and the relay UE transfers data between the source UE and the target UE.

[0072] Figure 4 shows the specific connection establishment steps. The source UE, relay UE, and target UE discover each other through discovery messages or direct communication request (DCR) messages. The relay UE can help the source UE forward discovery messages or DCR messages. After discovering each other, the source UE and target UE select a relay and establish a connection with the appropriate relay. The relay then acts as a relay to establish an end-to-end direct communication interface (PC5) connection.

[0073] 3GPP Rel-17 includes Layer 2 end-to-end relay. As shown in Figure 5, the adaptation layer (e.g., the Sidelink Relay Adaptation Protocol (SRAP) layer) is placed above the control plane and user plane Radio Link Control (RLC) sublayers between the relay UE and the source UE / target UE. The PC5 Service Data Adaptation Protocol (SDAP) / Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) terminate between the source terminal and the target. The RLC, Medium Access Control (MAC), and Physical layer (PHY) terminate in each link (i.e., the link between the source terminal and the relay terminal and the link between the relay terminal and the target). There is currently no conclusion on whether the adaptation layer is also supported at the PC5 interface between the source UE and the relay UE.

[0074] An example of L2UE to UE relay is as follows:

[0075] (1) The adaptation layer of the relay terminal supports sidelink bearer mapping between access PC5 RLC channels. For sidelink relay services, different end-to-end bearers, such as signaling radio bearers (SRBs) and data radio bearers (DRBs), of the same remote UE and / or different remote UEs can be mapped N:1 and multiplexed on a single PC5 RLC channel.

[0076] (2) The adaptation layer is used to support terminal identification for sideline services (multiplexing data from multiple terminals). The terminal PC5 radio bearer and terminal identification information are included in the adaptation layer so that the target can associate received data packets with a specific PDCP entity associated with the source terminal's radio bearer.

[0077] 4. UE to network relay

[0078] The remote terminal performs measurement reporting, and includes information such as the relay terminal identifier, serving cell identifier, and reference signal received power (RSRP) measurement results in the measurement reporting information. When the remote terminal performs a link switch from a non-direct path to a direct path, for the serving relay terminal, SL-RSRP can be used to perform measurements on the side link. When the remote terminal performs a link switch from a direct path to a non-direct path, Sidelink Discovery (SD)-RSRP can be used to perform measurements on the side link. In addition, when performing measurement reporting, two new measurement reporting triggering events are defined for terminal-to-network relay switching. Event 1 When the link quality of the serving relay terminal is lower than the configured threshold value, and optionally, the link quality of the adjacent cell is higher than the configured threshold value, the remote terminal performs measurement reporting. Event 2 When the link quality of the serving cell is lower than the configured threshold value, and optionally, the link quality of the relay terminal is higher than the configured threshold value, the remote terminal performs measurement reporting. In addition, a new timer is introduced to assist the remote terminal in performing a direct-to-indirect link handover. When the remote terminal receives an RRC reconfiguration message indicating a direct-to-indirect link handover, it starts the timer. When the timer expires, the remote terminal performs an RRC re-establishment.

[0079] Related U2U / U2N relays are primarily used in single-hop scenarios. For example, from a source UE via a relay UE to a target UE or gNB. Embodiments of the present application can further enhance coverage through multi-hop relays. For example, from a source UE via relay UE1, relay UE2, and so on, to a target UE or gNB via multiple relay UEs. In multi-hop relay scenarios, this may impact the sidelink multi-hop relay selection process. The relay communication method provided in embodiments of the present application may include a multi-hop relay selection process for this scenario.

[0080] FIG6 is a schematic flow chart of a relay communication method 600 according to an embodiment of the present application. The method 600 may optionally be applied to the systems shown in FIG1 to FIG5 , but is not limited thereto. The method includes at least part of the following contents.

[0081] S610: The first terminal selects a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

[0082] In an embodiment of the present application, in a wireless communication scenario, a multi-hop relay link may include two or more relay terminals. The role of the relay in the multi-hop relay link of the embodiment of the present application may be a terminal. The wireless communication scenario of the embodiment of the present application may include a scenario that supports sideline communication. The first terminal may be a terminal in a multi-hop relay link. The multi-hop relay link may be a U2U relay link or a U2N relay link. In a U2U relay link, the first terminal may be a source terminal or a target terminal. In a U2N relay link, the first terminal may be a remote terminal. The first terminal may also be a relay terminal in a U2U or U2N relay link. The first trigger condition may include one or more conditions for triggering the first terminal to perform relay selection or reselection. The first trigger condition may be determined based on the link state associated with the first terminal.

[0083] In the embodiments of the present application, the first trigger condition may include a relay selection trigger condition and / or a subsequent relay reselection trigger condition. For example, the relay selection trigger condition may be used in a scenario where the first terminal currently has no serving relay link and is selecting a relay for the first time. The relay reselection trigger condition may be used in a scenario where the first terminal has already selected a relay, i.e., currently has a serving relay link, but may reselect a relay.

[0084] In one embodiment, the first terminal is a remote terminal, a source terminal, a target terminal, or a relay terminal in the multi-hop relay link. The remote terminal, the source terminal, and the target terminal may also be referred to as end terminals.

[0085] In one embodiment, the first trigger condition includes at least one of the following relay selection trigger conditions:

[0086] An upper layer trigger of the first terminal;

[0087] The link quality of the direct link of the first terminal is lower than a configured threshold;

[0088] A wireless link failure occurs in the direct link of the first terminal;

[0089] The link quality between the first terminal and one or more candidate relay terminals is higher than a configured threshold;

[0090] A difference between the link quality between the first terminal and one or more candidate relay terminals and the link quality of the direct link of the first terminal is higher than a configured threshold.

[0091] In the embodiment of the present application, the upper layer of the first terminal may include a V2X layer and / or a ProSe layer, etc. The V2X layer and / or the ProSe layer, etc. of the first terminal may trigger the first terminal to perform initial selection of relay in some cases.

[0092] In an embodiment of the present application, the direct link of the first terminal may include a direct link between the first terminal and other terminals, and may also include a direct link between the first terminal and a network device. There may be multiple parameters for characterizing link quality, such as SL-RSRP, SD-RSRP, Uu-RSRP, etc. Various parameters may have corresponding configuration thresholds. The configuration threshold may be pre-configured or dynamically configured by the network device. For example, if the SL-RSRP is lower than or equal to the RSRP threshold, it may be determined that the relay selection trigger condition is met.

[0093] In embodiments of the present application, a radio link failure in a directly connected link of a first terminal may include a radio link failure between the first terminal and a directly connected terminal. The directly connected terminal of the first terminal may include a source terminal, a target terminal, or a remote terminal directly connected to the first terminal in a multi-hop relay link. For example, the first terminal is the source terminal, and the directly connected terminal is the target terminal. If the link between the source terminal and the target terminal fails, the source terminal may trigger relay selection. For another example, the first terminal is the target terminal, and the directly connected terminal is the source terminal. If the link between the source terminal and the target terminal fails, the target terminal may trigger relay selection. For another example, the first terminal is the remote terminal, and the directly connected link of the first terminal includes a link between the remote terminal and a network device. If the link between the remote terminal and the network device fails, the remote terminal may trigger relay selection. For another example, the source terminal, the target terminal, or the remote terminal may select one or more relay terminals. If the source terminal, the target terminal, or the remote terminal first selects a relay terminal, the relay terminal may act as the first terminal and continue to select other relay terminals until a multi-hop relay link is established. If the source terminal, the target terminal or the remote terminal selects multiple relay terminals, a multi-hop relay link can be formed based on the selected multiple relay terminals.

[0094] In an embodiment of the present application, a radio link failure in the direct link of the first terminal may include a radio link failure between the first terminal and the network device. If a radio link failure occurs between the first terminal and the directly connected network device, the first terminal may trigger the selection of a relay terminal. The first terminal may be a remote terminal or a relay terminal that has been selected by other terminals. For example, the remote UE first selects UE1 as the relay UE between the remote UE and the network device, and UE1 selects UE2 as the relay UE between UE1 and the network device. For another example, the remote UE first selects UE1, UE2, and UE3 as relay UEs between the remote UE and the network device.

[0095] In an embodiment of the present application, the configuration threshold of the link quality between the first terminal and one or more candidate relay terminals (e.g., referred to as the first configuration threshold) and the configuration threshold of the link quality of the direct link of the first terminal (e.g., referred to as the second configuration threshold) may be the same or different. For example, the first configuration threshold of the SL-RSRP of the direct link of the first terminal is Thr1, and the first configuration threshold of the SD-RSRP is Thr2. The second configuration threshold of the SL-RSRP between the first terminal and the candidate relay terminal is Thr3, and the second configuration threshold of the SD-RSRP is Thr4. Among them, Thr1 is the same as Thr3, and Thr2 is different from Thr4.

[0096] In this embodiment of the present application, the configuration threshold (hereinafter referred to as the third configuration threshold) for the difference between the link quality between the first terminal and one or more candidate relay terminals and the link quality of the first terminal's direct link may be the same as or different from the first configuration threshold and / or the second configuration threshold described above. For example, the third configuration threshold for the SL-RSRP difference is Thr5, and the second configuration threshold for the SD-RSRP difference is Thr6. Thr5 is the same as Thr3, and Thr6 is different from Thr4.

[0097] In the embodiment of the present application, there may be one or more candidate relay terminals. Relay selection of any terminal may be triggered based on all candidate relay terminals. Relay selection of a corresponding terminal may also be triggered based on some candidate relay terminals.

[0098] For example, there are three candidate relay terminals: UE1, UE2, and UE3. The first terminal is the source UE. If the SL-RSRP between the source UE and at least one of UE1, UE2, and UE3 is higher than the configured threshold, the source UE triggers relay selection, for example, selecting UE1 as the relay UE between the source UE and UE1. In this case, UE1 can become the first terminal and continue to determine whether the SL-RSRP between it and UE2 and / or UE3 is higher than the configured threshold. If so, UE1 triggers the selection of UE2 or UE3 as the relay UE between UE1 and the target UE.

[0099] For another example, there are 4 candidate relay terminals, among which UE1 and UE2 are candidate relay terminals corresponding to the first terminal, and UE3 and UE4 are candidate relay terminals corresponding to the first-hop relay UE selected by the first terminal. If the first terminal is the target UE, and the SL-RSRP between the target UE and UE1 and / or UE2 is higher than the configured threshold, the target UE triggers the selection of UE1 or UE2 as the relay UE between the source UE and UE1. If UE1 is selected as the relay UE between the source UE and UE1. UE1 can become the first terminal and continue to determine whether the SL-RSRP between it and UE3 and / or UE4 is higher than the configured threshold. If so, UE1 triggers the selection of UE3 or UE4 as the relay UE between UE1 and the target UE.

[0100] In an embodiment of the present application, after one or more first terminals initially select a relay terminal based on a trigger condition, a multi-hop relay link may be formed, thereby obtaining a longer communication distance than a single-hop relay network and improving communication reliability and communication range.

[0101] In one embodiment, the link quality of the direct link of the first terminal is lower than a configured threshold, including at least one of the following:

[0102] The PC5 link quality between the first terminal and the directly connected terminal is lower than a configured threshold;

[0103] The Uu link quality between the first terminal and the directly connected network device is lower than a configured threshold.

[0104] For example, the first terminal may be the source UE, and its directly connected terminal may be UE1. If the PC5 link quality between the source UE and UE1 is lower than the configured threshold, the source UE1 may trigger relay selection. For another example, the first terminal may be the target UE, and its directly connected terminal may be UE2. If the PC5 link quality between the target UE and UE2 is lower than the configured threshold, the target UE may trigger relay selection. For another example, the first terminal may be UE1, and its directly connected terminals may be the source UE and UE2. If the PC5 link quality between the source UE and UE1 is lower than the configured threshold, UE1 may trigger relay selection. If the PC5 link quality between UE1 and UE2 is lower than the configured threshold, UE1 may also trigger relay selection.

[0105] In one embodiment, the configuration threshold of the PC5 link and / or the Uu link is configured through RRC configuration, system information block (SIB) configuration or pre-configuration.

[0106] In one embodiment, the first trigger condition includes at least one of the following relay reselection trigger conditions:

[0107] An upper layer trigger of the first terminal;

[0108] The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold;

[0109] A radio link failure occurs in one or more hops of the multi-hop relay link where the first terminal is located;

[0110] One or more hops of the multi-hop relay link where the first terminal is located are released;

[0111] A cell reselection, handover (HO), or radio resource control (RRC) connection establishment failure occurs in one or more relay terminals in the multi-hop relay link where the first terminal is located;

[0112] Indication information of one or more relay terminals in the multi-hop relay link where the first terminal is located.

[0113] In an embodiment of the present application, if a multi-hop relay link has been formed. The configuration threshold of the link quality of one or more hops in the multi-hop relay link may be the same as or different from the configuration threshold of the link quality used for the initial selection of the relay. The first terminal may determine whether to trigger relay reselection based on one or more of the link quality of one or more hops in the multi-hop relay link, whether the link fails, whether the link is released, whether a mobility change occurs (cell reselection, HO or RRC connection establishment), and relay terminal indication. The first terminal may be a source terminal, a target terminal, a remote terminal, or a relay terminal.

[0114] For example, in a multi-hop relay link, the first hop (hop1) is between the source UE and the relay UE1, the second hop (hop2) is between the relay UE1 and the relay UE2, and the third hop (hop3) is between the relay UE2 and the target UE.

[0115] If the first terminal is the source UE and the link quality of hop1 is lower than the configured threshold or the link is released, the source UE can trigger relay reselection and may select UE3 as the new relay UE between the source UE and UE2. In this case, the link between the source UE and UE3 becomes hop1.

[0116] If the first terminal is relay UE1, and the link quality of hop2 falls below the configured threshold or the link is released, relay UE1 can trigger relay reselection and may select UE4 as the new relay UE between UE1 and the target UE. In this case, the link between UE1 and UE4 becomes hop2, and the link between UE4 and the target UE becomes hop3.

[0117] If the first terminal is relay UE1, and UE2 associated with hop2 and hop3 experiences one or more events such as cell reselection, HO, or RRC connection establishment failure, UE1 can trigger relay reselection, for example, selecting relay UE5 as the new relay UE between UE1 and the target UE. In this case, the connection between UE1 and UE5 becomes hop2, and the connection between UE5 and the target UE becomes hop3.

[0118] For another example, in a multi-hop relay link, the first hop (hop1) is between the network device and relay UE1, the second hop (hop2) is between relay UE1 and relay UE2, and the third hop (hop3) is between relay UE2 and the remote UE.

[0119] If the first terminal is relay UE1, and the link quality of hop1 is lower than the configured threshold or the link is released, relay UE1 can trigger relay reselection and may select UE6 as the relay UE between the network device and UE1. In this case, the connection between the network device and relay UE6 becomes hop1, and the connection between relay UE6 and relay UE1 becomes hop2.

[0120] If the first terminal is relay UE2, and the link quality between hop1 and hop2 falls below the configured threshold or the link is released, relay UE2 can trigger relay reselection and may select UE7 as the relay UE between the network device and UE2. In this case, the connection between the network device and relay UE7 becomes hop1, and the connection between relay UE7 and relay UE2 becomes hop2.

[0121] If the first terminal is a remote UE and UE2 associated with hop3 experiences one or more events such as cell reselection, HO, or RRC connection establishment failure, the remote UE can trigger relay reselection, for example, selecting relay UE8 as the relay UE between the remote UE and UE1. In this case, the connection between UE1 and relay UE8 becomes hop2, and the connection between relay UE8 and the remote UE becomes hop3.

[0122] In one embodiment, the indication information of the relay terminal of one or more hops in the multi-hop relay link where the first terminal is located can be used to indicate that the hop where the relay terminal is located has experienced at least one of link failure, link release, link quality lower than a configured threshold, cell reselection, HO, and RRC connection establishment failure. If the first terminal receives the indication information, it can determine whether to perform relay reselection based on the specific content indicated by the indication information. For example, if the indication information indicates that the hop where the relay terminal is located has experienced link failure, link release, or link quality lower than a configured threshold, the first terminal can perform relay reselection. If the indication information indicates that the relay terminal has experienced cell reselection, HO, or RRC connection establishment failure, the first terminal can perform relay reselection.

[0123] In one embodiment, the link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold, including at least one of the following:

[0124] The PC5 link quality of one or more hops in the link between the first terminal and the second terminal is lower than the configured threshold;

[0125] The PC5 link quality of one or more hops in the link between the first terminal and the network device is lower than the configured threshold;

[0126] The Uu link quality from the first hop or the last hop relay terminal to the network of the link between the first terminal and the network device is lower than the configured threshold.

[0127] For example, if the first terminal is a source terminal, the second terminal can be a target terminal or a relay terminal. If the first terminal is a target terminal, the second terminal can be a source terminal or a relay terminal. If the first terminal is a remote terminal, the second terminal can be a relay terminal. If the first terminal is a relay terminal, the second terminal can be a source terminal, a target terminal, a remote terminal, or a relay terminal other than the first terminal.

[0128] For example, the first hop or the last hop of the link between the first terminal and the network device can be understood as a hop between the relay terminal and the network device, such as hop 1 between UE1 and the network device in the above example.

[0129] In one embodiment, the configuration threshold of the PC5 link and / or Uu link is configured by at least one of the following: RRC configuration, SIB configuration, pre-configuration, relay configuration, network configuration to which the relay belongs, source terminal configuration, and network configuration to which the source terminal belongs. In an embodiment of the present application, the networks to which the terminals belong may be the same or different. The network to which the terminal belongs can send configurations about the terminal to the terminal, and can also send configurations of other terminals in the multi-hop relay link where the terminal is located to the terminal. For example, relay UE1 belongs to network 1, and relay UE2 belongs to network 2. The configuration threshold of the PC5 link and / or Uu link of relay UE1 can be received from network 1, and the configuration threshold of the PC5 link and / or Uu link of relay UE2 can be received from network 2. For another example, the source UE belongs to network 3, and the configuration threshold of the PC5 link of one or more of the source UE, relay UE and target UE is received from network 3.

[0130] In one embodiment, the thresholds of different hops of the multi-hop relay link where the first terminal is located are configured to be the same or different. For example, the multi-hop relay link where the first terminal is located includes multi-hop links hop1, hop2, and hop3. Among them, the configuration threshold of the SL-RSRP corresponding to hop1 is Thr1, the configuration threshold of the SL-RSRP corresponding to hop2 is Thr2, and the configuration threshold of the SL-RSRP corresponding to hop3 is Thr3.

[0131] The embodiment of the present application can form a multi-hop relay link based on the selection of the triggering condition to trigger the relay, which can further extend the communication distance and improve the communication reliability and communication range.

[0132] FIG7 is a schematic flow chart of a relay communication method 700 according to another embodiment of the present application. The method may include one or more features of the above method. In one embodiment, the method further includes:

[0133] S710: The first terminal monitors the link status of its related link.

[0134] In one embodiment, the relevant links of the first terminal include the direct link of the first terminal and / or one or more hops of the multi-hop relay link where the first terminal is located. For example, in the scenario where the relay is initially selected, the relevant links of the first terminal may include the direct link of the first terminal. If the source terminal and the target terminal are initially directly connected, the source terminal or the target terminal may monitor the link status of the link. For another example, in the scenario where the relay is reselected, the relevant links of the first terminal may include one or more hops of the multi-hop relay link where the first terminal is located. If the multi-hop links of the multi-hop relay link where the first terminal is located are hop1, hop2 and hop3 respectively, hop2 and hop3 are associated with the first terminal. For example, if hop2 is the link between relay UE1 and the first terminal, such as relay UE2, and hop3 is the link from relay UE2 to the target UE, then the first terminal, such as relay UE2, is associated with hop2 and hop3. The first terminal may monitor the link status of hop2 and / or hop3.

[0135] In an embodiment of the present application, the link status of the first terminal's related link may be monitored (also referred to as measured, detected, etc.), and then a determination may be made based on the link status whether a first trigger condition is met. If the first trigger condition is met, the first terminal triggers initial relay selection or reselection.

[0136] In one embodiment, the link status of the link related to the first terminal includes at least one of the following:

[0137] link quality of a related link of the first terminal;

[0138] link availability of a relevant link of the first terminal;

[0139] The mobility of the relay terminal of the link related to the first terminal changes.

[0140] In one embodiment, the link quality of the relevant link of the first terminal includes at least one of the following:

[0141] Whether the PC5 link quality of the relevant link of the first terminal is lower than the configured threshold;

[0142] Whether the Uu link quality of the relevant link of the first terminal is lower than the configured threshold.

[0143] For example, if the link quality of the PC5 link between the first terminal and the relay UE1 is lower than or equal to the configured threshold, it may indicate that the link quality is poor; if the link quality is higher than the configured threshold, it may indicate that the link quality is good.

[0144] For another example, if the link quality of the Uu link between the first terminal and the network device is lower than or equal to the configured threshold, it may indicate that the link quality is poor; if the link quality is higher than the configured threshold, it may indicate that the link quality is good.

[0145] In one embodiment, the link availability of the relevant link of the first terminal includes at least one of the following:

[0146] Whether a radio link failure (RLF) occurs in a link related to the first terminal;

[0147] Whether the relevant link of the first terminal is released;

[0148] Whether the relevant link of the first terminal is successfully established.

[0149] For example, if an RLF occurs in the direct link of the first terminal, the direct link becomes unavailable. For another example, if the first and second hops of a multi-hop relay link where the first terminal is located are released, the links between the first and second hops become unavailable; if the third hop is not released, the third hop becomes available. For another example, if the third hop of a multi-hop relay link where the first terminal is located is not successfully established, the third hop becomes unavailable; if the second hop is successfully established, the second hop becomes available.

[0150] In one embodiment, the mobility change of the relay terminal of the link related to the first terminal includes at least one of the following:

[0151] Whether the relay terminal has reselected a cell;

[0152] Whether the relay terminal has HO.

[0153] For example, if a relay terminal on a direct link of the first terminal reselects a cell, the first terminal may trigger the selection or reselection of the relay terminal. If a HO occurs on one or more hop relay terminals on a multi-hop relay link where the first terminal is located, the first terminal may trigger the selection or reselection of the relay terminal.

[0154] In one embodiment, the first terminal can transmit the link status it monitors to other terminals or network devices to assist them in relay selection or reselection. The second triggering condition for the first terminal to transmit the link status can be found in the following description of the relay communication method embodiment executed by the second terminal, with the second terminal replaced by the first terminal.

[0155] Figure 8 is a schematic flow chart of a relay communication method 800 according to another embodiment of the present application. The method may include one or more features of the above method. In one embodiment, the method further includes: S810, the first terminal receives a link status sent by the second terminal.

[0156] In one embodiment, the second terminal is a relay terminal, a source terminal, a target terminal, or a remote terminal.

[0157] In an embodiment of the present application, the second terminal may monitor the link status of its related link.

[0158] In one embodiment, the link status of the link related to the second terminal includes at least one of the following:

[0159] link quality of a related link of the second terminal;

[0160] link availability of the relevant link of the second terminal;

[0161] The mobility of the relay terminal of the link related to the second terminal changes.

[0162] In one embodiment, the link quality of the relevant link of the second terminal includes at least one of the following:

[0163] Whether the PC5 link quality of the relevant link of the second terminal is lower than the configured threshold;

[0164] Whether the Uu link quality of the relevant link of the second terminal is lower than the configured threshold.

[0165] In one embodiment, the link availability of the relevant link of the second terminal includes at least one of the following:

[0166] Whether a radio link failure RLF occurs in a related link of the second terminal;

[0167] Whether the relevant link of the second terminal is released;

[0168] Whether the relevant link of the second terminal is successfully established.

[0169] In one embodiment, the mobility change of the relay terminal of the link related to the second terminal includes at least one of the following:

[0170] Whether the relay terminal has reselected a cell;

[0171] Whether the relay terminal has HO.

[0172] In one embodiment, the link state is carried by at least one of the following: PC5 non-access stratum signaling; discovery message; direct communication request (DCR) message; direct communication accept (DCA) message; PC5 radio resource control layer (PC5-RRC) signaling; media access control element (MAC CE) signaling. For example, the PC5 non-access stratum may include a proximity based services (ProSe) layer and / or a V2X layer.

[0173] In one implementation, the PCS-RRC signaling includes at least one of the following: a measurement report, a notification message.

[0174] In one embodiment, the link status includes at least one of the following information:

[0175] a connection status of a service hop, where the service hop is the hop where the second terminal currently connects to another terminal or network device;

[0176] The connection status of the candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

[0177] For example, a multi-hop relay link includes a source UE, relay UE1, relay UE2, and a target UE. The first hop is between the source UE and relay UE1, the second hop is between relay UE1 and relay UE2, and the third hop is between relay UE2 and the target UE. The source UE's serving hop may include the first hop, and relay UE1's serving hop may include the first hop and / or the second hop. Relay UE2's serving hop may include the second hop and / or the third hop. The target UE's serving hop may include the third hop.

[0178] For another example, a multi-hop relay link includes a remote UE, relay UE1, relay UE2, and a network device. The first hop is between the remote UE and relay UE1, the second hop is between relay UE1 and relay UE2, and the third hop is between relay UE2 and the network device. The remote UE's service hops may include the first hop, and relay UE1's service hops may include the first hop and / or the second hop. Relay UE2's service hops may include the second hop and / or the third hop.

[0179] In one embodiment, the connection status includes at least one of the following: relay terminal identification, measurement results, hop count, and serving cell information. For example, in the above example, the hop count of relay UE1 may be 1, and the hop count of relay UE2 may be 2.

[0180] In one embodiment, the second terminal that sends the link status is a relay terminal, and the first terminal that receives the link status includes at least one of the following: a source terminal and / or target terminal with a normal link to the second terminal; a source terminal or target terminal that is closer to the second terminal; a source terminal and / or target terminal implemented based on the second terminal; or a source terminal that triggers the establishment of a connection between terminals. For example, the second terminal is the transmitter of the link status, and the transmitter is a relay terminal. The first terminal is the receiver of the link status, and the receiver can be the source terminal and / or target terminal. For example, the receiver includes a source terminal and / or target terminal with a normal link to the transmitter, a source terminal or target terminal that is closer to the transmitter, a source terminal and / or target terminal implemented based on the transmitter, or a source terminal that triggers the establishment of a connection between terminals.

[0181] In an embodiment of the present application, in a U2U relay, after one or more relay terminals monitor their associated link status, they may send the link status to a source terminal and / or a target terminal.

[0182] For example, a multi-hop relay link includes a source UE, relay UE1, relay UE2, and a target UE. If the link between relay UE2 and the target UE is abnormal, such as being released or having poor link quality, and the link between the source UE and relay UE1 is intact, relay UE1 can send the link status to the source UE. Relay UE1 can be the transmitter of the link status, and the source UE can be the receiver of the link status.

[0183] For another example, a multi-hop relay link includes a source UE, relay UE1, relay UE2, and a target UE. Relay UE1 can send link status to the source UE, which is closer to it. Relay UE2 can send link status to the target UE, which is closer to it.

[0184] For another example, the end implemented based on the transmitting end may be determined based on the transmitting end capability. For example, the relay UE2 selects to send the link status to the source UE based on its own capability.

[0185] For another example, if in a multi-hop relay link, one end that triggers establishment of a terminal connection is a source UE, relay UE1 and relay UE2 may send a link status to the source UE.

[0186] In one embodiment, the second terminal that sends the link status is a relay terminal, and the first terminal that receives the link status is a remote terminal.

[0187] In one embodiment, when the second terminal that sends the link status is a connected relay terminal, the receiving end of the link status may be a remote terminal and / or a network device.

[0188] For example, in a case where the sending end of the link state is a connected relay terminal, the receiving end of the link state is a remote terminal and / or a network device.

[0189] For another example, when the transmitting end of the link state is a non-connected relay terminal, the receiving end of the link state is a remote terminal.

[0190] In an embodiment of the present application, in a U2N relay, after one or more relay terminals detect the status of their associated link, they can send the link status to a network device and / or a remote terminal. For example, a multi-hop relay link includes a remote UE, relay UE1, relay UE2, and a network device. If a connection has been established between relay UE2 and the network device, relay UE2 can send the link status to the network device. If a connection has not been established between relay UE2 and the network device, the link status can be sent to the remote terminal via relay UE1.

[0191] In one embodiment, the first terminal selects the relay terminal based on at least one of the following:

[0192] PC5 link quality between the first terminal and the candidate relay terminal;

[0193] Meet high-level standards;

[0194] Comply with the relay hop limit experienced;

[0195] Meet the cache capacity requirements of relay terminals;

[0196] The relay terminal is a relay supporting multi-hop;

[0197] The serving cell and / or public land mobile network (PLMN) of the relay terminal meets the requirements;

[0198] The link quality of the next hop or multiple hops of the relay terminal is higher than the configured threshold, and the threshold configuration of each hop can be the same or different.

[0199] For example, the first terminal is a source UE, and among the links between the source UE and UE1, UE2, and UE3, the PC5 link between the source UE and UE2 has the best link quality. In this case, the source UE may select UE2 as the relay UE.

[0200] For another example, the high-level criteria include relay service code (RSC) indication information, and the first terminal, such as the target UE, may select the relay UE based on the RSC in the indication information.

[0201] For another example, if the current service relay hop count experienced by the first terminal, such as the target UE, is 3, the target UE can only select relay links that can reach the target UE within 3 hops. This restriction may be configured by the network or related to QoS / service.

[0202] For another example, if the buffer capacity of UE3 is higher than a set value, the first terminal, for example, relay UE2, may select UE3 as the relay UE.

[0203] For another example, if UE1 supports multi-hop relay and UE2 does not support multi-hop relay, the first terminal, such as a remote UE, may select UE1 as a relay UE.

[0204] For another example, the network can configure requirements for the serving cell and / or PLMN to which relay UEs belong. Assume that UEs belonging to serving cell 1, serving cell 2, and PLMN 1 can serve as relay UEs. If UE1 belongs to serving cell 1, UE2 belongs to serving cell 3, and UE3 belongs to PLMN 1, then UE1's serving cell and UE3's PLMN meet the requirements and UE1 and UE3 can be selected as relay UEs. However, if UE2's serving cell does not meet the requirements, UE2 will not be selected as a relay UE.

[0205] For example, the next hop of UE1 is UE2, and the next hop is UE3. The link quality between UE1 and UE2 is higher than the configured threshold 1, and the link quality between UE2 and UE3 is higher than the configured threshold 2. In this case, the first terminal, such as the source terminal, can select UE1 as the relay UE.

[0206] FIG9 is a schematic flow chart of a relay communication method 900 according to an embodiment of the present application. The method can optionally be applied to the systems shown in FIG1 to FIG5 , but is not limited thereto. The method includes at least part of the following contents.

[0207] S910. The second terminal sends a link status; wherein the link status is related to a first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

[0208] In one embodiment, the step S910 of the second terminal sending the link status includes: the second terminal periodically sending the link status. For example, after monitoring the link status or receiving the link status from other terminals, the second terminal may periodically send the link status to the first terminal.

[0209] In one implementation, the step S910 of the second terminal sending the link status includes: the second terminal sending the link status based on a second trigger condition.

[0210] In one embodiment, the second trigger condition includes at least one of the following events:

[0211] A measurement result of the reference signal by the second terminal is greater than or equal to a configured threshold;

[0212] A difference between a current measurement result of the reference signal by the second terminal and a previous measurement result exceeds a configured threshold;

[0213] A radio link failure (RLF) occurs in the second terminal;

[0214] The relevant link of the second terminal is released;

[0215] The relevant link of the second terminal fails to establish a connection;

[0216] The relay terminal of the link related to the second terminal has a mobility change;

[0217] The second terminal receives the measurement result or monitoring result of the relay terminal;

[0218] The second terminal receives a request from its previous hop terminal;

[0219] The relevant links of the second terminal include the direct link of the second terminal and / or one or more hops of the multi-hop relay link where the second terminal is located.

[0220] In the embodiment of the present application, the relevant link of the second terminal may include a direct link of the second terminal, and may also include one or more hops of a multi-hop relay link where the second terminal is located.

[0221] In the embodiment of the present application, according to the data transmission direction of the multi-hop relay link, the previous hop terminal of the second terminal can send data to the second terminal, and the second terminal can send data to its next hop terminal.

[0222] In one embodiment, the link state is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; DCR message; DCA message; PC5-RRC signaling; MAC CE signaling.

[0223] In one implementation, the PC5-RRC signaling includes at least one of the following: a measurement report, a notification message.

[0224] In one embodiment, the link status includes at least one of the following information:

[0225] a connection status of a service hop, where the service hop is the hop where the second terminal currently connects to another terminal or network device;

[0226] The connection status of the candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

[0227] In one implementation, the connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

[0228] In one embodiment, the second terminal sending the link status is a relay terminal, and the first terminal receiving the link status includes at least one of the following: a source terminal and / or target terminal with a normal link with the second terminal; a source terminal or target terminal that is closer to the second terminal; a source terminal and / or target terminal implemented based on the second terminal; and a source terminal that triggers the establishment of a connection between terminals.

[0229] In one embodiment, the second terminal that sends the link status is a relay terminal, and the first terminal that receives the link status is a remote terminal.

[0230] In one embodiment, when the second terminal sending the link status is a connected relay terminal, the receiving end of the link status further includes a network device.

[0231] For a specific example of the second terminal executing the relay communication method 900 in this embodiment, reference may be made to the relevant descriptions about the second terminal in the relay communication methods 600, 700, and 800 executed by the first terminal, which will not be repeated here for the sake of brevity.

[0232] The relay communication method of the embodiments of the present application may include a relay selection and / or reselection mechanism in sidelink multi-hop relay technology. For example, based on the relay selection and reselection in single-hop U2U / U2N relay technology, a multi-hop relay selection and reselection mechanism may be further provided, for example, including at least one of the following schemes: multi-hop relay selection and reselection triggering conditions; multi-hop relay selection and reselection process; and determination of qualified relays. The following are several specific examples.

[0233] Example 1: Multi-hop relay selection / reselection trigger conditions.

[0234] 1. The relay selection triggering condition may include at least one of the following:

[0235] (1) Upper layer (e.g., V2X / Prose layer) triggering;

[0236] (2) The link quality is lower than a certain threshold. Examples are as follows:

[0237] For example, in a U2U relay, the PC5 link quality (SL-RSRP / SD-RSRP) between the relay and the other UE is lower than the configured threshold 1.

[0238] For example, the U2N relay: the Uu link quality with the network is lower than the configured threshold 2;

[0239] The above configuration threshold may be derived from one or more of RRC configuration, SIB configuration or pre-configuration.

[0240] (3) A wireless link failure occurs between the other UE / network.

[0241] 2. The relay reselection triggering condition may include at least one of the following:

[0242] (1) Upper layer (V2X / Prose layer) triggering;

[0243] (2) The link quality of any hop of the current link is lower than the threshold, including at least one of the following examples:

[0244] For example, in a U2U MH (multi-hop) relay, the link quality (SL-RSRP / SD-RSRP) of any hop PC5 is lower than the configured threshold 1.

[0245] For another example, in U2N MH relay, the link quality (SL-RSRP / SD-RSRP) of any hop PC5 is lower than the configured threshold 2 or the link quality from the last hop relay to the network Uu is lower than the configured threshold 3.

[0246] The above configuration thresholds are derived from RRC configuration / SIB configuration / pre-configuration / relay configuration (or relay network) / source UE configuration (or source network). The threshold configurations of different hops can be the same or different.

[0247] (3) A wireless link failure occurs at any hop (PC5 / Uu);

[0248] (4) Any hop link is released;

[0249] (5) A relay UE at any hop in the U2N MH relay experiences cell reselection, handover (HO), or RRC connection establishment failure;

[0250] (6) The relay UE at any hop sends an indication message. The indication message may indicate that the link at the hop where the relay UE is located has experienced link failure, link release, poor link quality, or that the relay has experienced cell reselection, HO, or RRC connection establishment failure.

[0251] Example 2: Multi-hop relay selection / reselection process - centralized relay selection and reselection

[0252] FIG10 is a schematic flow chart of centralized relay selection / reselection according to Example 2 of the present application, and the steps are as follows:

[0253] 1. Each UE monitors / measures its own egress-hop status (i.e., an example of link status). The monitoring includes at least one of the following:

[0254] Link quality of the PC5 / Uu link of one or more hops (e.g., a hop may be marked as an egress-hop), such as SL-RSRP, SD-RSRP, or Uu-RSRP;

[0255] Availability of one-hop or multi-hop PC5 / Uu links: whether a radio link failure (RLF) occurs, whether it is released, and whether it is successfully established;

[0256] For U2N relay, whether the relay UE has mobility changes such as HO / cell reselection.

[0257] For example, the one hop or the multiple hops may include a hop away from the source UE, such as a hop away from the source UE / target UE (end UE).

[0258] 2. Each relay UE can monitor / measure its own one or more hops and send them to the remote / source UE:

[0259] 2-1. The sending method may include at least one of the following:

[0260] (1) U2U relay sends data to both UEs, or only to one UE. The UE at one end is the one with a good link, the one that is closer, the one based on UE implementation, or the one that triggers the establishment of the U2U connection.

[0261] (2) U2N relay sends to the UE and the network, or only to the UE. For example, in a connected state, the relay sends to the network and / or the remote UE. In another example, in a non-connected state, the relay sends to the remote UE.

[0262] 2-2. This transmission can be triggered by a condition or periodically, as shown below:

[0263] (1) The period of periodic triggering can be configured by the upper layer (V2X / Prose layer) or the access layer (Access Stratum, AS) (base station or source UE);

[0264] (2) The event triggered by the event can be at least one of the following:

[0265] The measured RSRP is greater than and / or less than a certain threshold, which is configured by the relay UE (or relay UE network) / remote UE (remote UE network) / the network to which the current U2N is connected;

[0266] The measured RSRP differs (is better or worse than) from the previous measurement result by more than a certain threshold (or within a certain time). The threshold and time length are configured by the relay UE (or relay UE network) / remote UE (remote UE network) / the network to which the current U2N is connected;

[0267] An RLF occurs, the link is released, and a connection establishment failure occurs;

[0268] Mobility changes such as HO / cell reselection occur;

[0269] Receive (forward) measurement / monitoring results from other relays;

[0270] A request from a source UE (may be referred to as a source UE, source terminal, etc.) is received.

[0271] 2-3. This information (i.e., one-hop or multi-hop) can be carried in at least one of the following ways:

[0272] PC5 access layer signaling: discovery message (Model-A / B), DCR message, DCA message, or others;

[0273] PC5-RRC signaling: measurement report, notification message, or other signaling;

[0274] MAC CE signaling.

[0275] 2-4. This information (i.e., one-hop or multi-hop) may include at least one of the following:

[0276] For example, the current (if any) connection status of the serving hop, such as Relay UE ID (L2ID), measurement results, hop level, and serving cell information.

[0277] For another example, the candidate hop information may include: Relay UE ID (L2ID), measurement results, hop level, and serving cell information.

[0278] The serving hops may include established hops in a multi-hop relay link connected to the terminal. For example, the serving hops for relay 1 include hop 2, and the serving hops for relay 2 include hop 3. The terminal's candidate hops may include hops with which the terminal can establish a connection. For example, if the candidate hops between relay 1 and candidate relay 3 include hop 4, the candidate hops between candidate relay 3 and the target UE include hop 5. Hop 4 and hop 5 are hops with which no connection has yet been established.

[0279] 3. The source / remote UE selects or reselects a relay UE that meets the requirements of the upper layer and the AS layer. Examples of selection methods include: selecting or reselecting a relay UE based on the detected status of the current hop; and / or selecting or reselecting a relay UE based on the content of information received from other hops.

[0280] Example 3: Multi-hop relay selection / reselection process - distributed relay selection and reselection

[0281] FIG11 is a schematic flow chart of distributed relay selection / reselection according to Example 3 of the present application, the steps are as follows:

[0282] 1. Each UE monitors / measures its own egress-hop status. This monitoring includes at least one of the following:

[0283] Link quality (SL-RSRP / SD-RSRP / Uu-RSRP) of the PC5 / Uu link at the egress hop;

[0284] Availability of the PC5 / Uu link on the egress hop: whether a RLF occurs, whether the link is released, and whether the link is successfully established.

[0285] For U2N relay, whether the relay UE has mobility changes such as HO / cell reselection.

[0286] 2. Each hop UE will monitor / measure its own egress-hop status and send it to the previous hop UE (if any):

[0287] 2-1. This transmission can be triggered by a condition or periodically, as shown below:

[0288] (1) The period of periodic triggering can be configured by the upper layer (V2X / Prose layer configuration) or the AS layer (base station or source UE);

[0289] (2) The event triggered by the event can be at least one of the following:

[0290] The measured RSRP is greater than and / or less than a certain threshold, which is configured by the relay UE (or relay UE network) / remote UE (remote UE network) / the network to which the current U2N is connected;

[0291] The measured RSRP differs (is better or worse than) from the previous measurement result by more than a certain threshold (or within a certain time). The threshold and time length are configured by the relay UE (or relay UE network) / remote UE (remote UE network) / the network to which the current U2N is connected;

[0292] An RLF occurs, the link is released, and a connection establishment failure occurs;

[0293] Mobility changes such as HO / cell reselection occur;

[0294] Receive (forward) measurement / monitoring results from other relays;

[0295] Receive a request from the previous hop UE.

[0296] 2-3. This information can be carried in at least one of the following ways:

[0297] PC5-S signaling: discovery message (Model-A / B), DCR message, DCA message, or others;

[0298] PC5-RRC signaling: measurement reports, notification messages, or other signaling;

[0299] MAC CE signaling.

[0300] 2-4. This information may include at least one of the following:

[0301] For example, the current (if any) connection status of the serving hop, such as: Relay UE ID (L2 ID), measurement results, hop level, and serving cell information.

[0302] For another example, the candidate hop situation can be selected: for example, Relay UE ID (L2 ID), measurement results, hop level, and serving cell information.

[0303] 3. Each hop UE performs relay selection and reselection, and selects the relay UE that meets the requirements of the upper layer and AS layer:

[0304] It can be based on the situation of the current hop detected by itself; and / or based on the content of the information received from the next hop.

[0305] Example 4: Multi-hop relay selection criteria.

[0306] For example, relay selection meeting the following criteria may include at least one of:

[0307] The PC5 link quality with the relay, including SL-RSRP and / or SD-RSRP values ​​above a certain threshold (higher than a certain threshold of the current serving relay);

[0308] Comply with high-level criteria, such as RSC instructions;

[0309] Meets the relay hop limit experienced (less than the current service relay hop limit);

[0310] Meet the relay's buffer capacity requirements;

[0311] This relay supports multi-hop;

[0312] The serving cell and / or PLMN of the relay meets the requirements;

[0313] The quality of the next hop or multi-hop link of the relay is higher than a certain threshold. The threshold configuration of each hop can be the same or different.

[0314] In the above example, a multi-hop U2U / U2N relay selection and reselection process is provided, which can extend the communication distance and improve the communication reliability and communication range.

[0315] FIG12 is a schematic block diagram of a first terminal 1200 according to an embodiment of the present application. The first terminal 1200 may include:

[0316] The processing unit 1201 is configured to select a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

[0317] In one embodiment, the first trigger condition includes at least one of the following relay selection trigger conditions:

[0318] An upper layer trigger of the first terminal;

[0319] The link quality of the direct link of the first terminal is lower than a configured threshold;

[0320] A wireless link failure occurs in the direct link of the first terminal;

[0321] The link quality between the first terminal and one or more candidate relay terminals is higher than a configured threshold;

[0322] A difference between the link quality between the first terminal and one or more candidate relay terminals and the link quality of the direct link of the first terminal is higher than a configured threshold.

[0323] In one embodiment, the link quality of the direct link of the first terminal is lower than a configured threshold, including at least one of the following:

[0324] The PC5 link quality between the first terminal and the directly connected terminal is lower than a configured threshold;

[0325] The Uu link quality between the first terminal and the directly connected network device is lower than a configured threshold.

[0326] In one embodiment, the configuration threshold of the PC5 link and / or Uu link is configured through RRC configuration, system information block SIB configuration, or pre-configuration.

[0327] In one embodiment, the first trigger condition includes at least one of the following relay reselection trigger conditions:

[0328] An upper layer trigger of the first terminal;

[0329] The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold;

[0330] A radio link failure occurs in one or more hops of the multi-hop relay link where the first terminal is located;

[0331] One or more hops of the multi-hop relay link where the first terminal is located are released;

[0332] A cell reselection, handover HO, or radio resource control RRC connection establishment failure occurs in one or more relay terminals in the multi-hop relay link where the first terminal is located;

[0333] Indication information of one or more relay terminals in the multi-hop relay link where the first terminal is located.

[0334] In one embodiment, the link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold, including at least one of the following:

[0335] The PC5 link quality of one or more hops in the link between the first terminal and the second terminal is lower than a configured threshold;

[0336] The PC5 link quality of one or more hops in the link between the first terminal and the network device is lower than a configured threshold;

[0337] The Uu link quality from the first hop or the last hop relay terminal to the network of the link between the first terminal and the network device is lower than the configured threshold.

[0338] For example, if the first terminal is a source terminal, the second terminal can be a target terminal or a relay terminal. If the first terminal is a target terminal, the second terminal can be a source terminal or a relay terminal. If the first terminal is a remote terminal, the second terminal can be a relay terminal. If the first terminal is a relay terminal, the second terminal can be a source terminal, a target terminal, a remote terminal, or a relay terminal other than the first terminal.

[0339] In one embodiment, the configuration threshold of the PC5 link and / or Uu link is configured by at least one of the following: RRC configuration, SIB configuration, pre-configuration, relay configuration, network configuration of the relay, source terminal configuration, and network configuration of the source terminal.

[0340] In one embodiment, the thresholds of different hops of the multi-hop relay link where the first terminal is located are configured to be the same or different.

[0341] In one embodiment, the indication information is used to indicate that the hop where the relay terminal is located has at least one of link failure, link release, link quality lower than a configured threshold, cell reselection, HO, and RRC connection establishment failure.

[0342] In one embodiment, the first terminal is a remote terminal, a source terminal, a destination terminal, or a relay terminal in the multi-hop relay link.

[0343] In one embodiment, the processing unit is further configured to monitor the link status of its associated link;

[0344] The relevant links of the first terminal include the direct link of the first terminal and / or one or more hops of the multi-hop relay link where the first terminal is located.

[0345] In one embodiment, the link status of the link related to the first terminal includes at least one of the following:

[0346] link quality of a related link of the first terminal;

[0347] link availability of a relevant link of the first terminal;

[0348] The mobility of the relay terminal of the link related to the first terminal changes.

[0349] In one embodiment, the link quality of the relevant link of the first terminal includes at least one of the following:

[0350] Whether the PC5 link quality of the relevant link of the first terminal is lower than the configured threshold;

[0351] Whether the Uu link quality of the relevant link of the first terminal is lower than the configured threshold.

[0352] In one embodiment, the link availability of the relevant link of the first terminal includes at least one of the following:

[0353] Whether a radio link failure RLF occurs in a related link of the first terminal;

[0354] Whether the relevant link of the first terminal is released;

[0355] Whether the relevant link of the first terminal is successfully established.

[0356] In one embodiment, the mobility change of the relay terminal of the link related to the first terminal includes at least one of the following:

[0357] Whether the relay terminal has reselected a cell;

[0358] Whether the relay terminal has HO.

[0359] In one embodiment, as shown in FIG13 , the first terminal 1300 further includes:

[0360] The receiving unit 1301 is configured to receive a link status sent by a second terminal, where the second terminal is a relay terminal, a source terminal, a destination terminal, or a remote terminal.

[0361] In one embodiment, the link state is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; direct communication request DCR message; direct communication accept DCA message; PC5 radio resource control layer PC5-RRC signaling; MAC CE signaling.

[0362] In one implementation, the PC5-RRC signaling includes at least one of the following: a measurement report, a notification message.

[0363] In one embodiment, the link status includes at least one of the following information:

[0364] a connection status of a service hop, where the service hop is the hop where the second terminal currently connects to another terminal or network device;

[0365] The connection status of the candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

[0366] In one implementation, the connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

[0367] In one embodiment, the second terminal sending the link status is a relay terminal, and the first terminal receiving the link status includes at least one of the following: a source terminal and / or target terminal with a normal link with the second terminal; a source terminal or target terminal that is closer to the second terminal; a source terminal and / or target terminal implemented based on the second terminal; and a source terminal that triggers the establishment of a connection between terminals.

[0368] In one embodiment, the second terminal that sends the link status is a relay terminal, and the first terminal that receives the link status is a remote terminal.

[0369] In one embodiment, when the second terminal sending the link status is a connected relay terminal, the receiving end of the link status further includes a network device.

[0370] In one embodiment, the first terminal selects the relay terminal based on at least one of the following:

[0371] PC5 link quality between the first terminal and the candidate relay terminal;

[0372] Meet high-level standards;

[0373] Comply with the relay hop limit experienced;

[0374] Meet the cache capacity requirements of relay terminals;

[0375] The relay terminal is a relay supporting multi-hop;

[0376] The serving cell and / or public land mobile network (PLMN) of the relay terminal meets the requirements;

[0377] The link quality of the next hop or multiple hops of the relay terminal is higher than the configured threshold, and the threshold configuration of each hop can be the same or different.

[0378] The second terminals 1200 and 1300 of the embodiments of the present application can implement the corresponding functions of the first terminal in the aforementioned method embodiment. The processes, functions, implementation methods, and beneficial effects corresponding to the various modules (sub-modules, units, or components, etc.) in the first terminals 1200 and 1300 can be found in the corresponding descriptions in the aforementioned method embodiments and will not be repeated here. It should be noted that the functions described in the various modules (sub-modules, units, or components, etc.) in the first terminals 1200 and 1300 of the embodiment of the application can be implemented by different modules (sub-modules, units, or components, etc.) or by the same module (sub-module, unit, or component, etc.).

[0379] FIG14 is a schematic block diagram of a second terminal 1400 according to an embodiment of the present application. The second terminal 1400 may include:

[0380] The sending unit 1401 is used to send the link status; wherein the link status is related to the first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

[0381] In one implementation, the sending unit is configured to periodically send the link status.

[0382] In one implementation, the sending unit is configured to send the link status based on a second trigger condition.

[0383] In one embodiment, the second trigger condition includes at least one of the following events:

[0384] A measurement result of the reference signal by the second terminal is greater than or equal to a configured threshold;

[0385] A difference between a current measurement result of the reference signal by the second terminal and a previous measurement result exceeds a configured threshold;

[0386] A radio link failure RLF occurs on the second terminal;

[0387] The relevant link of the second terminal is released;

[0388] The relevant link of the second terminal fails to establish a connection;

[0389] The relay terminal of the link related to the second terminal has a mobility change;

[0390] The second terminal receives the measurement result or monitoring result of the relay terminal;

[0391] The second terminal receives a request from its previous hop terminal;

[0392] The relevant links of the second terminal include the direct link of the second terminal and / or one or more hops of the multi-hop relay link where the second terminal is located.

[0393] In one embodiment, the link state is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; DCR message; DCA message; PC5-RRC signaling; MAC CE signaling.

[0394] In one implementation, the PC5-RRC signaling includes at least one of the following: a measurement report, a notification message.

[0395] In one embodiment, the link status includes at least one of the following information:

[0396] a connection status of a service hop, where the service hop is the hop where the second terminal currently connects to another terminal or network device;

[0397] The connection status of the candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

[0398] In one implementation, the connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

[0399] In one embodiment, the second terminal sending the link status is a relay terminal, and the first terminal receiving the link status includes at least one of the following: a source terminal and / or target terminal with a normal link with the second terminal; a source terminal or target terminal that is closer to the second terminal; a source terminal and / or target terminal implemented based on the second terminal; and a source terminal that triggers the establishment of a connection between terminals.

[0400] In one embodiment, the second terminal that sends the link status is a relay terminal, and the first terminal that receives the link status is a remote terminal.

[0401] In one embodiment, when the second terminal sending the link status is a connected relay terminal, the receiving end of the link status further includes a network device.

[0402] The second terminal 1400 in the embodiment of the present application can implement the corresponding functions of the second terminal in the aforementioned method embodiment. The processes, functions, implementation methods and beneficial effects corresponding to the various modules (sub-modules, units or components, etc.) in the second terminal 1400 can be found in the corresponding descriptions in the aforementioned method embodiment and will not be repeated here. It should be noted that the functions described in the various modules (sub-modules, units or components, etc.) in the second terminal 1400 of the embodiment of the application can be implemented by different modules (sub-modules, units or components, etc.) or by the same module (sub-module, unit or component, etc.).

[0403] Figure 15 is a schematic structural diagram of a communication device 1500 according to an embodiment of the present application. The communication device 1500 includes a processor 1510, which can call and execute a computer program from a memory to enable the communication device 1500 to implement the method in the embodiment of the present application.

[0404] In one embodiment, the communication device 1500 may further include a memory 1520. The processor 1510 may call and execute a computer program from the memory 1520 to enable the communication device 1500 to implement the method in the embodiment of the present application.

[0405] The memory 1520 may be a separate device independent of the processor 1510 , or may be integrated into the processor 1510 .

[0406] In one embodiment, the communication device 1500 may further include a transceiver 1530 , and the processor 1510 may control the transceiver 1530 to communicate with other devices. Specifically, the transceiver 1530 may send information or data to other devices, or receive information or data sent by other devices.

[0407] The transceiver 1530 may include a transmitter and a receiver. The transceiver 1530 may further include an antenna, and the number of antennas may be one or more.

[0408] In one embodiment, the communication device 1500 may be the first terminal of the embodiment of the present application, and the communication device 1500 may implement the corresponding processes implemented by the first terminal in each method of the embodiment of the present application. For the sake of brevity, they will not be repeated here.

[0409] In one embodiment, the communication device 1500 may be the second terminal of the embodiment of the present application, and the communication device 1500 may implement the corresponding processes implemented by the second terminal in each method of the embodiment of the present application. For the sake of brevity, they will not be repeated here.

[0410] 16 is a schematic structural diagram of a chip 1600 according to an embodiment of the present application. The chip 1600 includes a processor 1610, which can call and execute a computer program from a memory to implement the method according to the embodiment of the present application.

[0411] In one embodiment, the chip 1600 may further include a memory 1620. The processor 1610 may call and execute a computer program from the memory 1620 to implement the method executed by the first terminal or the second terminal in the embodiment of the present application.

[0412] The memory 1620 may be a separate device independent of the processor 1610 , or may be integrated into the processor 1610 .

[0413] In one embodiment, the chip 1600 may further include an input interface 1630. The processor 1610 may control the input interface 1630 to communicate with other devices or chips, and specifically, may obtain information or data sent by other devices or chips.

[0414] In one embodiment, the chip 1600 may further include an output interface 1640. The processor 1610 may control the output interface 1640 to communicate with other devices or chips, and specifically, may output information or data to other devices or chips.

[0415] In one embodiment, the chip can be applied to the first terminal in the embodiment of the present application, and the chip can implement the corresponding processes implemented by the first terminal in each method of the embodiment of the present application. For the sake of brevity, it will not be repeated here.

[0416] In one embodiment, the chip can be applied to the second terminal in the embodiment of the present application, and the chip can implement the corresponding processes implemented by the second terminal in each method of the embodiment of the present application. For the sake of brevity, it will not be repeated here.

[0417] The chip used in the first terminal and the second terminal may be the same chip or different chips.

[0418] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0419] The processor mentioned above may be a general-purpose processor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or other programmable logic devices, transistor logic devices, discrete hardware components, etc. The general-purpose processor mentioned above may be a microprocessor or any conventional processor, etc.

[0420] The memory mentioned above may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. The non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM).

[0421] It should be understood that the above-mentioned memories are exemplary but not restrictive. For example, the memories in the embodiments of the present application may also be static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM bus random access memory (DRRAM). In other words, the memories in the embodiments of the present application are intended to include, but are not limited to, these and any other suitable types of memories.

[0422] FIG17 is a schematic block diagram of a communication system 1700 according to an embodiment of the present application. The communication system 1700 includes a first terminal 1710 and a second terminal 1720 .

[0423] The first terminal 1710 is configured to select a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

[0424] The second terminal 1720 is used to send a link status. The first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal. The first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

[0425] The first terminal 1710 can be used to implement the corresponding functions implemented by the first terminal in the above method, and the second terminal 1720 can be used to implement the corresponding functions implemented by the second terminal in the above method. For the sake of brevity, they are not described here in detail.

[0426] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function in accordance with the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode to another website, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

[0427] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean 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 the present application.

[0428] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0429] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A relay communication method, comprising: The first terminal selects a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

2. The method according to claim 1, wherein: The first trigger condition includes at least one of the following relay selection trigger conditions: An upper layer trigger of the first terminal; The link quality of the direct link of the first terminal is lower than a configured threshold; A wireless link failure occurs between the first terminal and the direct link; The link quality between the first terminal and one or more candidate relay terminals is higher than a configured threshold; A difference between a link quality between the first terminal and one or more candidate relay terminals and a link quality of a direct link of the first terminal is higher than a configured threshold.

3. The method according to claim 2, wherein: The link quality of the direct link of the first terminal is lower than a configured threshold, including at least one of the following: The link quality of the direct communication interface PC5 between the first terminal and the directly connected terminal is lower than the configured threshold; The Uu link quality between the first terminal and the directly connected network device is lower than the configured threshold.

4. The method according to claim 3, wherein: The configuration threshold of the PC5 link and / or Uu link is configured through unlimited resource control RRC configuration, system information block SIB configuration or pre-configuration.

5. The method according to any one of claims 1 to 4, wherein: The first trigger condition includes at least one of the following relay reselection trigger conditions: An upper layer trigger of the first terminal; The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold; A wireless link failure occurs in one or more hops of the multi-hop relay link where the first terminal is located; One or more hops of the multi-hop relay link where the first terminal is located are released; A cell reselection, HO or RRC connection establishment failure occurs in one or more relay terminals in the multi-hop relay link where the first terminal is located; Indication information of one or more relay terminals in the multi-hop relay link where the first terminal is located.

6. The method according to claim 5, wherein: The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configuration threshold, including at least one of the following: The PC5 link quality of one or more hops in the link between the first terminal and the second terminal is lower than a configured threshold; The PC5 link quality of one or more hops in the link between the first terminal and the network device is lower than a configured threshold; The Uu link quality from the first hop or the last hop relay terminal to the network of the link between the first terminal and the network device is lower than the configured threshold.

7. The method according to claim 6, wherein: The configuration threshold of the PC5 link and / or Uu link is configured by at least one of the following: RRC configuration, SIB configuration, pre-configuration, relay configuration, network configuration to which the relay belongs, source terminal configuration, and network configuration to which the source terminal belongs.

8. The method according to any one of claims 5 to 7, wherein: The thresholds of different hops of the multi-hop relay link where the first terminal is located are configured to be the same or different.

9. The method according to any one of claims 5 to 8, wherein: The indication information is used to indicate at least one of link failure, link release, link quality lower than a configuration threshold, cell reselection, HO, and RRC connection establishment failure at the hop where the relay terminal is located.

10. The method according to any one of claims 1 to 9, wherein: The first terminal is a remote terminal, a source terminal, a target terminal or a relay terminal in the multi-hop relay link.

11. The method according to any one of claims 1 to 10, wherein: The method further comprises: The first terminal monitors the link status of its related link; The related links of the first terminal include a direct link of the first terminal and / or one or more hops of a multi-hop relay link where the first terminal is located.

12. The method according to claim 11, wherein: The link status of the first terminal related link includes at least one of the following: link quality of a relevant link of the first terminal; link availability of a link associated with the first terminal; The mobility of the relay terminal of the relevant link of the first terminal changes.

13. The method according to claim 12, wherein: The link quality of the relevant link of the first terminal includes at least one of the following: Whether the PC5 link quality of the relevant link of the first terminal is lower than the configured threshold; Whether the Uu link quality of the relevant link of the first terminal is lower than the configured threshold.

14. The method according to claim 12 or 13, wherein: The link availability of the relevant link of the first terminal includes at least one of the following: Whether a radio link failure RLF occurs in a relevant link of the first terminal; Whether the relevant link of the first terminal is released; Whether the relevant link of the first terminal is successfully established.

15. The method according to any one of claims 12 to 14, wherein: The mobility change of the relay terminal of the link related to the first terminal includes at least one of the following: Whether the relay terminal reselects a cell; Whether HO occurs to the relay terminal.

16. The method according to any one of claims 1 to 15, wherein: The method further comprises: The first terminal receives a link status sent by a second terminal, where the second terminal is a relay terminal, a source terminal, a target terminal or a remote terminal.

17. The method according to claim 16, wherein: The link status is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; direct communication request DCR message; direct communication acceptance DCA message; PC5 radio resource control layer PC5-RRC signaling; media access control MAC control element CE signaling.

18. The method according to claim 17, wherein: The PC5-RRC signaling includes at least one of the following: a measurement report and a notification message.

19. The method according to any one of claims 16 to 18, wherein: The link status includes at least one of the following information: a connection status of a service hop, where the service hop is a hop where the second terminal currently connects to other terminals or network devices; The connection status of a candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

20. The method according to claim 19, wherein: The connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

21. The method according to any one of claims 16 to 20, wherein: The second terminal is a relay terminal, and the first terminal includes at least one of the following: a source terminal and / or a target terminal with a normal link with the second terminal; a source terminal or a target terminal that is closer to the second terminal; a source terminal and / or a target terminal implemented based on the second terminal; a source terminal that triggers the establishment of a connection between terminals.

22. The method according to any one of claims 16 to 20, wherein: The second terminal is a relay terminal, and the first terminal is a remote terminal; or In the case where the second terminal is a connected relay terminal, the receiving end of the link state further includes a network device.

23. The method according to any one of claims 1 to 22, wherein: The first terminal selects a relay terminal based on at least one of the following: PC5 link quality between the first terminal and the candidate relay terminal; Meet high-level standards; Comply with the relay hop limit experienced; Meet the cache capacity requirements of relay terminals; The relay terminal is a relay supporting multi-hop; The serving cell and / or public land mobile network PLMN of the relay terminal meets the requirements; The link quality of the next hop or multiple hops of the relay terminal is higher than the configured threshold, and the threshold configuration of each hop can be the same or different.

24. A relay communication method, comprising: The second terminal sends a link status; The link state is related to a first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

25. The method according to claim 24, wherein: The second terminal sends a link status, including: The second terminal periodically sends the link status.

26. The method according to claim 24 or 25, wherein: The second terminal sends a link status, including: The second terminal sends the link status based on a second trigger condition.

27. The method according to claim 26, wherein: The second trigger condition includes at least one of the following events: A measurement result of the reference signal by the second terminal is greater than or equal to a configured threshold; A difference between a current measurement result and a previous measurement result of the reference signal by the second terminal exceeds a configured threshold; A radio link failure RLF occurs in the second terminal; The relevant link of the second terminal is released; A connection establishment failure occurs on a link related to the second terminal; A relay terminal of a link related to the second terminal undergoes a mobility change; The second terminal receives the measurement result or monitoring result of the relay terminal; The second terminal receives a request from its previous hop terminal; The related links of the second terminal include a direct link of the second terminal and / or one or more hops of a multi-hop relay link where the second terminal is located.

28. The method according to any one of claims 24 to 27, wherein: The link status is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; DCR message; DCA message; PC5-RRC signaling; MAC CE signaling.

29. The method according to claim 28, wherein: The PC5-RRC signaling includes at least one of the following: a measurement report and a notification message.

30. The method according to any one of claims 24 to 29, wherein: The link status includes at least one of the following information: a connection status of a service hop, where the service hop is a hop where the second terminal currently connects to other terminals or network devices; The connection status of a candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

31. The method according to claim 30, wherein: The connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

32. The method according to any one of claims 24 to 31, wherein: The second terminal is a relay terminal, and the first terminal includes at least one of the following: a source terminal and / or a target terminal with a normal link with the second terminal; a source terminal or a target terminal that is closer to the second terminal; a source terminal and / or a target terminal implemented based on the second terminal; a source terminal that triggers the establishment of a connection between terminals.

33. The method according to any one of claims 24 to 31, wherein: The second terminal is a relay terminal, and the first terminal is a remote terminal; or In the case where the second terminal is a connected relay terminal, the receiving end of the link state further includes a network device.

34. A first terminal, comprising: A processing unit, configured to select a relay terminal that meets the requirements of the first terminal based on a first trigger condition; wherein the first terminal and the relay terminal are in a multi-hop relay link, and the first trigger condition is related to the link state.

35. The first terminal according to claim 34, wherein: The first trigger condition includes at least one of the following relay selection trigger conditions: An upper layer trigger of the first terminal; The link quality of the direct link of the first terminal is lower than a configured threshold; A wireless link failure occurs in the direct link of the first terminal; The link quality between the first terminal and one or more candidate relay terminals is higher than a configured threshold; A difference between a link quality between the first terminal and one or more candidate relay terminals and a link quality of a direct link of the first terminal is higher than a configured threshold.

36. The first terminal according to claim 35, wherein: The link quality of the direct link of the first terminal is lower than a configured threshold, including at least one of the following: The PC5 link quality between the first terminal and the directly connected terminal is lower than the configured threshold; The Uu link quality between the first terminal and the directly connected network device is lower than the configured threshold.

37. The first terminal according to claim 36, wherein: The configuration threshold of the PC5 link and / or Uu link is configured through RRC configuration, SIB configuration or pre-configuration.

38. The first terminal according to any one of claims 34 to 37, wherein: The first trigger condition includes at least one of the following relay reselection trigger conditions: An upper layer trigger of the first terminal; The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configured threshold; A wireless link failure occurs in one or more hops of the multi-hop relay link where the first terminal is located; One or more hops of the multi-hop relay link where the first terminal is located are released; A cell reselection, HO or RRC connection establishment failure occurs in one or more relay terminals in the multi-hop relay link where the first terminal is located; Indication information of one or more relay terminals in the multi-hop relay link where the first terminal is located.

39. The first terminal according to claim 38, wherein: The link quality of one or more hops in the multi-hop relay link where the first terminal is located is lower than a configuration threshold, including at least one of the following: The PC5 link quality of one or more hops in the link between the first terminal and the second terminal is lower than a configured threshold; The PC5 link quality of one or more hops in the link between the first terminal and the network device is lower than a configured threshold; The Uu link quality from the first hop or the last hop relay terminal to the network of the link between the first terminal and the network device is lower than the configured threshold.

40. The first terminal according to claim 39, wherein: The configuration threshold of the PC5 link and / or Uu link is configured by at least one of the following: RRC configuration, SIB configuration, pre-configuration, relay configuration, network configuration to which the relay belongs, source terminal configuration, and network configuration to which the source terminal belongs.

41. The first terminal according to any one of claims 38 to 40, wherein: The thresholds of different hops of the multi-hop relay link where the first terminal is located are configured to be the same or different.

42. The first terminal according to any one of claims 38 to 41, wherein: The indication information is used to indicate at least one of link failure, link release, link quality lower than a configuration threshold, cell reselection, HO, and RRC connection establishment failure at the hop where the relay terminal is located.

43. The first terminal according to any one of claims 34 to 42, wherein: The first terminal is a remote terminal, a source terminal, a target terminal or a relay terminal in the multi-hop relay link.

44. The first terminal according to any one of claims 34 to 43, wherein: The processing unit is also used to monitor the link status of its related link; The related links of the first terminal include a direct link of the first terminal and / or one or more hops of a multi-hop relay link where the first terminal is located.

45. The first terminal according to claim 44, wherein: The link status of the first terminal related link includes at least one of the following: link quality of a relevant link of the first terminal; link availability of a link associated with the first terminal; The mobility of the relay terminal of the relevant link of the first terminal changes.

46. ​​The first terminal according to claim 45, wherein: The link quality of the relevant link of the first terminal includes at least one of the following: Whether the PC5 link quality of the relevant link of the first terminal is lower than the configured threshold; Whether the Uu link quality of the relevant link of the first terminal is lower than the configured threshold.

47. The first terminal according to claim 45 or 46, wherein: The link availability of the relevant link of the first terminal includes at least one of the following: Whether a radio link failure RLF occurs in a relevant link of the first terminal; Whether the relevant link of the first terminal is released; Whether the relevant link of the first terminal is successfully established.

48. The first terminal according to any one of claims 45 to 47, wherein: The mobility change of the relay terminal of the link related to the first terminal includes at least one of the following: Whether the relay terminal reselects a cell; Whether HO occurs to the relay terminal.

49. The first terminal according to any one of claims 34 to 48, wherein: The first terminal further includes: The receiving unit is used to receive the link status sent by the second terminal, where the second terminal is a relay terminal, a source terminal, a target terminal or a remote terminal.

50. The first terminal according to claim 49, wherein: The link status is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; DCR message; DCA message; PC5-RRC signaling; MACCE signaling.

51. The first terminal according to claim 50, wherein: The PC5-RRC signaling includes at least one of the following: a measurement report and a notification message.

52. The first terminal according to any one of claims 49 to 51, wherein: The link status includes at least one of the following information: a connection status of a service hop, where the service hop is a hop where the second terminal currently connects to other terminals or network devices; The connection status of a candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

53. The first terminal according to claim 52, wherein: The connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

54. The first terminal according to any one of claims 49 to 53, wherein: The second terminal is a relay terminal, and the first terminal includes at least one of the following: a source terminal and / or a target terminal with a normal link with the second terminal; a source terminal or a target terminal that is closer to the second terminal; a source terminal and / or a target terminal implemented based on the second terminal; a source terminal that triggers the establishment of a connection between terminals.

55. The first terminal according to any one of claims 49 to 53, wherein: The second terminal is a relay terminal, and the first terminal is a remote terminal; or In the case where the second terminal is a connected relay terminal, the receiving end of the link state further includes a network device.

56. The first terminal according to any one of claims 34 to 55, wherein: The first terminal selects a relay terminal based on at least one of the following: PC5 link quality between the first terminal and the candidate relay terminal; Meet high-level standards; Comply with the relay hop limit experienced; Meet the cache capacity requirements of relay terminals; The relay terminal is a relay supporting multi-hop; The serving cell and / or public land mobile network PLMN of the relay terminal meets the requirements; The link quality of the next hop or multiple hops of the relay terminal is higher than the configured threshold, and the threshold configuration of each hop can be the same or different.

57. A second terminal, comprising: A sending unit, used for sending a link status; The link state is related to a first trigger condition, and the first trigger condition is used to trigger the first terminal to select a relay terminal that meets the requirements of the first terminal, and the first terminal, the second terminal and the relay terminal are in a multi-hop relay link.

58. The second terminal according to claim 57, wherein: The sending unit is used to periodically send the link status.

59. The second terminal according to claim 57 or 58, wherein: The sending unit is used to send the link status based on a second trigger condition.

60. The second terminal according to claim 59, wherein: The second trigger condition includes at least one of the following events: A measurement result of the reference signal by the second terminal is greater than or equal to a configured threshold; A difference between a current measurement result and a previous measurement result of the reference signal by the second terminal exceeds a configured threshold; RLF occurs in the second terminal; The relevant link of the second terminal is released; A connection establishment failure occurs on a link related to the second terminal; A relay terminal of a link related to the second terminal undergoes a mobility change; The second terminal receives the measurement result or monitoring result of the relay terminal; The second terminal receives a request from its previous hop terminal; The related links of the second terminal include a direct link of the second terminal and / or one or more hops of a multi-hop relay link where the second terminal is located.

61. The second terminal according to any one of claims 57 to 60, wherein: The link status is carried by at least one of the following means: PC5 non-access layer signaling; discovery message; DCR message; DCA message; PC5-RRC signaling; MAC CE signaling.

62. The second terminal according to claim 61, wherein: The PC5-RRC signaling includes at least one of the following: a measurement report and a notification message.

63. The second terminal according to any one of claims 57 to 62, wherein: The link status includes at least one of the following information: a connection status of a service hop, where the service hop is a hop where the second terminal currently connects to other terminals or network devices; The connection status of a candidate hop, where the candidate hop is a hop through which the second terminal may connect to other terminals or network devices.

64. The second terminal according to claim 63, wherein: The connection status includes at least one of the following: a relay terminal identifier, a measurement result, a hop count, and serving cell information.

65. The second terminal according to any one of claims 57 to 64, wherein: The second terminal is a relay terminal, and the first terminal includes at least one of the following: a source terminal and / or a target terminal with a normal link with the second terminal; a source terminal or a target terminal that is closer to the second terminal; a source terminal and / or a target terminal implemented based on the second terminal; a source terminal that triggers the establishment of a connection between terminals.

66. The second terminal according to any one of claims 57 to 64, wherein: The second terminal is a relay terminal, and the first terminal is a remote terminal; or In the case where the second terminal is a connected relay terminal, the receiving end of the link state further includes a network device.

67. A terminal device, comprising: A processor and a memory, the memory being used to store a computer program, the processor being used to call and run the computer program stored in the memory so that the terminal device executes the method as claimed in any one of claims 1 to 23 or any one of claims 24 to 33.

68. A chip, comprising: A processor, configured to call and run a computer program from a memory so that a device equipped with the chip executes a method as claimed in any one of claims 1 to 23 or any one of claims 24 to 33.

69. A computer-readable storage medium for storing a computer program, which, when executed by a device, causes the device to perform the method as claimed in any one of claims 1 to 23 or any one of claims 24 to 33.

70. A computer program product comprising computer program instructions for causing a computer to perform the method of any one of claims 1 to 23 or any one of claims 24 to 33.

71. A computer program causing a computer to perform a method as claimed in any one of claims 1 to 23 or any one of claims 24 to 33.

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