COMMUNICATION METHOD AND COMMUNICATION DEVICE

Abstract

A communication method and a communication device are provided. The method includes: a first terminal device sends data to a second terminal device on multiple carriers through a side link SL; the first terminal device determines a feedback reception status of the data at a feedback reception occasion on the multiple carriers, the feedback reception occasion being a feedback reception occasion for the data; the first terminal device determines whether a SL radio link failure RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. According to the present application, the SL RLF can be handled when a transmission using one PC5-RRC connection is performed on multiple carriers. This helps to improve communication reliability.

Description

[Technical field]

[0001] The present application relates to the field of communication technologies, and in particular to communication methods and devices. [Background technology]

[0002] This application claims priority to Chinese Patent Application No. 202210147397.1, entitled "SL RLF PROCESSING METHOD", filed with the China National Intellectual Property Office on February 17, 2022, and Chinese Patent Application No. 202210460362.3, entitled "COMMUNICATION METHOD AND COMMUNICATION APPARATUS", filed with the China National Intellectual Property Office on April 28, 2022, both of which are incorporated by reference herein in their entireties.

[0003] The 3rd generation partnership project (3GPP) has been developing standards for sidelink (SL) as a tool for user equipment (UE)-to-UE direct communication required in various use cases beyond long term evolution (LTE). Sidelink communication includes unicast communication mode. In particular, in unicast communication mode, a PC5 radio resource control (RRC) connection usually needs to be established between a source UE and a target UE. One UE may have multiple PC5-RRC connections for one or multiple UEs. Currently, transmission using one PC5-RRC connection is performed on only one carrier. If a SL radio link failure (RLF) is caused by a carrier, the terminal device releases the PC5-RRC connection. However, no solution has been proposed for how to handle SL RLF when transmission using one PC5-RRC connection is performed on multiple carriers, reducing communication reliability. Summary of the Invention

[0004] The present application provides a communication method and a communication device such that SL RLF can be handled when transmissions using one PC5-RRC connection are performed on multiple carriers, which helps to improve communication reliability.

[0005] According to a first aspect, the present application provides a communication method, the method being applied to a first terminal device, the method comprising: Side Link ( SL ) sending data over a plurality of carriers to a second terminal device via the determining a feedback reception status of data at a feedback reception occasion on a plurality of carriers, the feedback reception occasion being a feedback reception occasion for data; Based on the feedback reception status, SL radio link failure ( RLF ) determining whether a communication occurs between the first terminal device and the second terminal device; Includes.

[0006] In the present application, when transmissions using one PC5-RRC connection are performed on multiple carriers, HARQ-based SL RLF detection can be performed on multiple carriers, and thus, when transmissions using one PC5-RRC connection are performed on multiple carriers, SL radio link failure detection can be performed on multiple carriers. ( RLF ) It may be determined whether a feedback occurs between the first terminal device and the second terminal device. The data may be a PSSCH or a MAC PDU, the feedback of the data may be a HARQ feedback or a PSFCH, and the feedback reception occasion may be understood as a PSFCH feedback reception occasion.

[0007] In a possible implementation, the step of determining a feedback reception status of data at a feedback reception occasion on a plurality of carriers comprises: sequentially determining whether feedback of data is received at each of the feedback reception occasions on each of a plurality of carriers; The step of determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: The method includes determining that a SL RLF occurs between the first terminal device and the second terminal device if a first amount of continuous time during which no data feedback is received on the multiple carriers is greater than or equal to a first threshold.

[0008] In this implementation, when transmissions using one PC5-RRC connection are performed on multiple carriers, statistics regarding PSFCH reception occasions related to each transmission of a PSSCH / MAC PDU on each of the carriers may be collected together to determine whether a SL RLF occurs in the PC5-RRC connection.

[0009] In a possible implementation, after the step of sequentially determining whether feedback of data is received at each of the feedback reception occasions on each of the multiple carriers, the method further comprises: setting the first amount to zero if a first amount of continuous time during which no feedback of data is received on the multiple carriers is less than a first threshold and feedback of data is received at a next feedback receiving occasion; or if a first amount of continuous time during which no data feedback is received on the multiple carriers is less than a first threshold and no data feedback is received at a next feedback receiving occasion, adding one to the first amount. Further includes:

[0010] In a possible implementation, the step of determining a feedback reception status of data at a feedback reception occasion on a plurality of carriers comprises: sequentially determining whether feedback of data is received on a first carrier at each of the feedback receiving occasions, the first carrier being any one of a plurality of carriers; The step of determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: The method includes determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a second amount of continuous time during which no data feedback is received on the first carrier is greater than or equal to a second threshold.

[0011] In this implementation, when transmissions using one PC5-RRC connection are performed on multiple carriers, statistics on PSFCH reception occasions related to transmissions of PSSCH / MAC PDUs on different carriers may be collected separately to determine whether a SL RLF occurs on a particular carrier in a PC5-RRC connection. It should be noted that in this implementation, when statistics on PSFCH reception occasions on any carrier are collected, the PSFCH reception occasions may include PSFCH reception occasions corresponding to data sent on that carrier and / or the PSFCH reception occasions may include PSFCH reception occasions corresponding to data sent on another carrier.

[0012] In a possible implementation, after the step of sequentially determining whether feedback of data is received on the first carrier in each of the feedback receiving occasions, the method further comprises: if a second amount of continuous time during which no feedback of data is received on the first carrier is less than a second threshold and feedback of data is received at a next feedback receiving occasion, setting the second amount to zero; or if a second amount of continuous time during which no data feedback is received on the first carrier is less than a second threshold and no data feedback is received at the next feedback receiving occasion, adding one to the second amount. Further includes:

[0013] In a possible implementation, the step of determining a feedback reception status of data at a feedback reception occasion on a plurality of carriers comprises: sequentially determining whether feedback of first data sent on a first carrier is received at each of feedback receiving occasions for the first data, the first carrier being any one of a plurality of carriers; The step of determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: The method includes determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a third amount of continuous time during which no feedback of the first data is received is greater than or equal to a third threshold.

[0014] In this implementation, when transmissions using one PC5-RRC connection are performed on multiple carriers, statistics on PSFCH reception occasions related to transmissions of PSSCH / MAC PDUs on different carriers may be collected separately to determine whether a SL RLF occurs on a particular carrier in a PC5-RRC connection. Note that in this implementation, when statistics on PSFCH reception occasions on any carrier are collected, the PSFCH reception occasions include only those PSFCH reception occasions that correspond to data sent on that carrier.

[0015] In a possible implementation, after the step of sequentially determining whether feedback of the first data sent on the first carrier is received in each of the feedback receiving occasions for the first data, the method includes: setting the third amount to zero if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is received at a next feedback receiving occasion for the first data; or if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is not received at a next feedback receiving occasion for the first data, adding one to the third amount. Further includes:

[0016] In a possible implementation, the method comprises: The method further includes sending first indication information to the second terminal device, where the first indication information indicates that a SL RLF occurs on the first carrier, or the first indication information indicates that the first carrier should be deleted or released.

[0017] In this implementation, when the first terminal device determines that the SL RLF occurs on the first carrier, the first terminal device sends a first indication information to the second terminal device to inform the second terminal device that the first carrier on which the SL RLF occurs should be deleted or released. This reduces unnecessary communication interruption caused by directly releasing the PC5-RRC connection in the prior art when the SL RLF is found. In other words, in the embodiment of the present application, the first carrier on which the SL RLF specifically occurs may be determined, and when the first carrier on which the SL RLF specifically occurs is determined, only the first carrier is deleted or released, and another carrier on which the SL RLF does not occur can still be used for normal communication between the first terminal device and the second terminal device. This improves communication reliability.

[0018] In a possible implementation, the method comprises: Removing or releasing the first carrier Further includes:

[0019] In this implementation, when the first terminal device determines that the SL RLF occurs on the first carrier, the first terminal device may also delete or release the first carrier on which the SL RLF occurs to save storage resources and thus improve communication reliability.

[0020] In a possible implementation, the method comprises: The method further includes sending second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0021] In this implementation, when the first terminal device determines that the SL RLF occurs on the first carrier, if there is an RRC connection between the first terminal device and the access network device, the first terminal device may further send second indication information to the access network device through the RRC connection to inform the access network device of the specific carrier on which the SL RLF occurs. Thus, the access network device may no longer schedule the first terminal device to send data to the second terminal device by using the first carrier, thereby improving communication reliability.

[0022] According to a second aspect, the present application provides a communication method, the method being applied to a first terminal device, the method comprising: Side Link ( SL ) Radio Link Failure ( RLF ) occurs on a first carrier, the first carrier being any one or more of a plurality of carriers used by the first terminal device to send data to a second terminal device; Sending first indication information to a second terminal device, the first indication information indicating the first carrier or the first indication information indicating that the first carrier should be deleted or released; Includes.

[0023] In the present application, when the first terminal device determines that the SL RLF occurs on the first carrier, the first terminal device sends a first indication information to the second terminal device to inform the second terminal device that the first carrier on which the SL RLF occurs should be deleted or released. This reduces unnecessary communication interruption caused in the conventional technology in which the PC5-RRC connection is directly released when the SL RLF is found. In other words, in the embodiment of the present application, the first carrier on which the SL RLF specifically occurs may be determined, and when the first carrier on which the SL RLF specifically occurs is determined, only the first carrier is deleted or released, and another carrier on which the SL RLF does not occur can still be used for normal communication between the first terminal device and the second terminal device. This improves communication reliability.

[0024] In a possible implementation, the step of determining that a SL RLF occurs on a first carrier includes: First Radio Link Control ( RLC ) The method includes determining that a SL RLF occurs on a first carrier associated with a first RLC entity if an amount of data retransmissions determined based on the entity reaches a maximum amount of retransmissions, and the first terminal device sends data to a second terminal device through the first RLC entity.

[0025] In this implementation, if the first terminal device determines an RLC SDU transmitted by an RLC entity whose amount of transmission reaches a maximum amount of retransmissions (including those initially transmitted or retransmitted) on one or more carriers, the first terminal device may determine that the carrier(s) causing the SL RLF are the one or more carriers associated with the RLC entity. In other words, the first carrier is the one or more carriers associated with the first RLC entity.

[0026] In a possible implementation, the step of determining that a SL RLF occurs on a first carrier associated with a first RLC entity includes: First Radio Link Control ( RLC ) The amount of data retransmission determined based on the entity reaches a maximum amount of retransmission, and the first RLC entity performs a packet data convergence protocol using packet duplication. ( PDCP ) determining that a SL RLF occurs on a first carrier associated with the first RLC entity if the RLC entity corresponds to the first RLC entity; Includes.

[0027] In this implementation, if the RLC entity that causes the SL RLF is an RLC entity corresponding to a PDCP entity that uses packet duplication, and the transmission performed by the RLC entity is mapped to a carrier set (which may also be understood as a carrier set corresponding to a logical channel corresponding to the RLC entity), the first terminal device may determine that a carrier in the carrier set causes the SL RLF. In other words, the first carrier is one or more carriers in the carrier set.

[0028] In a possible implementation, the first carrier includes multiple carriers, and after the step of determining that the SL RLF occurs on the first carrier, the method further comprises: sending first information to a second terminal device on each of the carriers in the first carrier, the first information being used to trigger the second terminal device to feed back second information; determining that the SL RLF occurs on a second carrier if the second information sent by the second terminal device is not received on the second carrier, the second carrier being any carrier among the first carriers; Further includes:

[0029] In this implementation, once a SL RLF occurs, the first terminal device sends first information to a peer UE (i.e., a second terminal device) on each of the carriers in the first carriers and receives second information from the second terminal device. The first information and the second information may be used to determine a particular carrier or a plurality of particular carriers in the first carriers that cause the SL RLF.

[0030] In a possible implementation, the method comprises: Removing or releasing the first carrier Further includes:

[0031] In this implementation, when the first terminal device determines that the SL RLF occurs on the first carrier, the first terminal device may also delete or release the first carrier on which the SL RLF occurs to save storage resources and thus improve communication reliability.

[0032] In a possible implementation, the method comprises: The method further includes sending second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0033] In this implementation, when the first terminal device determines that the SL RLF occurs on the first carrier, if there is an RRC connection between the first terminal device and the access network device, the first terminal device may further send second indication information to the access network device through the RRC connection to inform the access network device of the specific carrier on which the SL RLF occurs. Thus, the access network device may no longer schedule the first terminal device to send data to the second terminal device by using the first carrier, thereby improving communication reliability.

[0034] According to a third aspect, the present application provides a communication apparatus, the apparatus being a first terminal device, the apparatus comprising: Side Link ( SL ) a transceiver unit configured to transmit data over a plurality of carriers to a second terminal device via the a processing unit configured to determine a feedback reception status of data at a feedback reception occasion on a plurality of carriers, the feedback reception occasion being a feedback reception occasion for data; Includes.

[0035] The processing unit detects an SL radio link failure based on the feedback receiving situation. ( RLF ) occurs between the first terminal device and the second terminal device.

[0036] In a possible implementation, the processing unit comprises: sequentially determining whether feedback of data is received at each of the feedback reception occasions on each of a plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device when a first amount of continuous time during which no data feedback is received on the plurality of carriers is greater than or equal to a first threshold; The present invention is configured to perform the following steps.

[0037] In a possible implementation, after the processing unit sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit: setting the first amount to zero if a first amount of continuous time during which no feedback of data is received on the multiple carriers is less than a first threshold and feedback of data is received at a next feedback receiving occasion; or if a first amount of continuous time during which no data feedback is received on the multiple carriers is less than a first threshold and no data feedback is received at a next feedback receiving occasion, adding one to the first amount. The device is further configured to:

[0038] In a possible implementation, the processing unit comprises: sequentially determining whether feedback of data is received at each of the feedback receiving occasions on a first carrier, the first carrier being any one of the plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier when a second amount of continuous time during which no data feedback is received on the first carrier is greater than or equal to a second threshold; The present invention is configured to:

[0039] In a possible implementation, after the processing unit sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit: setting the second amount to zero if a second amount of continuous time during which no feedback of data is received on the first carrier is less than a second threshold and feedback of data is received at a next feedback receiving occasion; or if a second amount of continuous time during which no data feedback is received on the first carrier is less than a second threshold and no data feedback is received at a next feedback receiving occasion, adding one to the second amount. The device is further configured to:

[0040] In a possible implementation, the processing unit comprises: sequentially determining whether feedback of first data sent on a first carrier is received at each of feedback receiving occasions for the first data, the first carrier being any one of a plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a third amount of continuous time during which no first data feedback is received is equal to or greater than a third threshold; The present invention is configured to:

[0041] In a possible implementation, after the processing unit sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit: setting the third amount to zero if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is received at a next feedback receiving occasion for the first data; or if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is not received at a next feedback receiving occasion for the first data, adding one to the third amount. The device is further configured to:

[0042] In a possible implementation, the transceiver unit comprises: and further configured to send first indication information to the second terminal device, the first indication information indicating that a SL RLF occurs on the first carrier, or the first indication information indicating that the first carrier should be deleted or released.

[0043] In a possible implementation, the processing unit comprises: Remove or release the first carrier The method is further configured as follows.

[0044] In a possible implementation, the transceiver unit comprises: The access network device is further configured to send second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0045] According to a fourth aspect, the present application provides a communication apparatus, the apparatus being a first terminal device, the apparatus comprising: Side Link ( SL ) Radio Link Failure ( RLF ) occurs on a first carrier, the first carrier being any one or more of a plurality of carriers used by the first terminal device to send data to a second terminal device; and a transceiver unit configured to send first indication information to a second terminal device, the first indication information indicating a first carrier or indicating that the first carrier should be deleted or released; Includes.

[0046] In a possible implementation, the processing unit comprises: First Radio Link Control ( RLC ) The system is configured to determine that if an amount of data retransmissions determined based on the entity reaches a maximum amount of retransmissions, a SL RLF occurs on a first carrier associated with the first RLC entity, and the first terminal device sends data to a second terminal device through the first RLC entity.

[0047] In a possible implementation, the processing unit comprises: First Radio Link Control ( RLC )The amount of data retransmission determined based on the entity reaches a maximum amount of retransmission, and the first RLC entity performs a packet data convergence protocol using packet duplication. ( PDCP ) If the RLC entity corresponds to the first RLC entity, determine that the SL RLF occurs on a first carrier associated with the first RLC entity. It is configured as follows.

[0048] In a possible implementation, the first carrier includes multiple carriers, and after the processing unit determines that the SL RLF occurs on the first carrier, the processing unit: sending first information to a second terminal device on each of the carriers in the first carriers, the first information being used to trigger the second terminal device to feed back second information; determining that a SL RLF occurs on a second carrier if second information sent by a second terminal device is not received on the second carrier, the second carrier being any carrier among the first carriers; The device is further configured to:

[0049] In a possible implementation, the processing unit comprises: Remove or release the first carrier The method is further configured as follows.

[0050] In a possible implementation, the transceiver unit comprises: The access network device is further configured to send second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0051] According to a fifth aspect, the present application provides a communication device. The device may be a terminal device (e.g., a first terminal device or a second terminal device), may be a device in a terminal device, or may be a device capable of being used in a compatible manner with a terminal device. The communication device may alternatively be a chip system. The communication device may implement the method according to the first aspect and / or the second aspect. The functions of the communication device may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the above functions. The units or modules may be software and / or hardware. For the operations implemented by the communication device and the beneficial effects thereof, please refer to the methods according to the first aspect and / or the second aspect, and their beneficial effects. Repeated contents will not be described again.

[0052] According to a sixth aspect, the present application provides a communication apparatus. The apparatus may be a terminal device (e.g., a first terminal device or a second terminal device). The communication apparatus includes a processor and a transceiver. The processor and the transceiver are configured to execute computer programs or instructions stored in at least one memory, whereby the apparatus implements a method according to any one of the first and / or second aspects.

[0053] According to a seventh aspect, the present application provides a communication apparatus. The apparatus may be a terminal device (e.g., a first terminal device or a second terminal device). The communication apparatus includes a processor, a transceiver, and a memory. The processor, the transceiver, and the memory are coupled. The processor and the transceiver are configured to implement a method according to any one of the first aspect and / or the second aspect.

[0054] According to an eighth aspect, the present application provides a computer-readable storage medium, the storage medium storing a computer program or instructions which, when executed by a computer, implements a method according to any one of the first to fourth aspects.

[0055] According to a ninth aspect, the present application provides a computer program product comprising instructions, the computer program product comprising computer program code, which when executed on a computer implements a method according to any one of the first to fourth aspects. [Brief description of the drawings]

[0056] [Figure 1] FIG. 1 is a diagram of the architecture of a communication system according to an embodiment of the present application. [Diagram 2] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Diagram 3] FIG. 1 is an illustration of a scenario for determining a SL RLF according to an embodiment of the present application. [Figure 4] FIG. 13 is an illustration of another scenario for determining the SL RLF according to an embodiment of the present application. [Diagram 5] FIG. 13 is an illustration of another scenario for determining the SL RLF according to an embodiment of the present application. [Figure 6] FIG. 13 is an illustration of another scenario for determining the SL RLF according to an embodiment of the present application. [Figure 7a] FIG. 13 is an illustration of another scenario for determining the SL RLF according to an embodiment of the present application. [Figure 7b] FIG. 13 is an illustration of another scenario for determining the SL RLF according to an embodiment of the present application. [Figure 8] 4 is another schematic flowchart of a communication method according to an embodiment of the present application. [Figure 9] 1 is a diagram of a structure of a communication device according to an embodiment of the present application; [Figure 10] FIG. 2 is a structural diagram of another communication device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] Below, the technical solutions in the embodiments of the present application are described with reference to the accompanying drawings in the embodiments of the present application.

[0058] The terms "system" and "network" may be used interchangeably in the embodiments of this application. Unless otherwise specified, " / " represents an "or" relationship between related objects. For example, A / B may represent A or B. The term "and / or" in this application is merely an association relationship to describe related objects, and represents that three relationships may exist. For example, A and / or B may represent three cases: only A exists, both A and B exist, and only B exists, and A and B may be singular or plural. In addition, in the description of this application, unless otherwise specified, "multiple" means two or more. "At least one of the following items (parts)" or similar expressions thereof refers to any combination of these items, including any combination of singular items (parts) or plural items (parts). For example, at least one of a, b, or c may represent a, b, c, ab, ac, bc, or abc, and a, b, and c may be singular or plural. In addition, in order to clearly describe the technical solutions in the embodiments of the present application, terms such as "first" and "second" are used in the embodiments of the present application to distinguish between the same or similar items that provide essentially the same function or purpose. Those skilled in the art may understand that terms such as "first" and "second" do not limit the quantity or execution sequence, and terms such as "first" and "second" do not indicate clear differences.

[0059] References to "embodiments," "some embodiments," and the like in the embodiments of this application indicate that one or more embodiments of this application include the particular feature, structure, or characteristic described with respect to the embodiment. Thus, statements such as "in an embodiment," "in some embodiments," "in some other embodiments," and "in yet some other embodiments" appearing in various parts of this specification do not necessarily mean to refer to the same embodiment. Instead, these statements mean "one or more, but not all, of the embodiments," unless otherwise specifically emphasized in another manner. The terms "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized in another manner.

[0060] It should be understood that the technical solutions in the embodiments of the present application may be applied to long term evolution (LTE) architecture, 5th generation mobile networks (5G), wireless local area network (WLAN) systems, V2X communication systems, etc. The technical solutions in the embodiments of the present application may further be applied to another future communication system, for example, a 6G communication system. In the future communication system, the same functions may be maintained, but the names may be changed.

[0061] The basic architecture of the communication system provided in the embodiment of the present application is described below.

[0062] Figure 1 is a diagram of an architecture of a communication system according to an embodiment of the present application. As shown in Figure 1, the communication system may include a first terminal device 10 and a second terminal device 20 that implements SL communication with the first terminal device 10. Figure 1 is only a diagram and does not constitute a limitation on a scenario in which the technical solution provided in the present application is applicable.

[0063] The first terminal device 10 and the second terminal device 20 are user side entities configured to receive signals, or send signals, or receive and send signals. The first terminal device 10 and the second terminal device 20 are configured to provide one or more of voice services and data connectivity services to a user. The first terminal device 10 and the second terminal device 20 may be devices that include wireless transceiver functions and can operate with an access network device to provide communication services to a user. In particular, the first terminal device 10 and the second terminal device 20 may be user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, terminal, wireless communication device, user agent, user equipment, or roadside unit (RSU).The first terminal device 10 and the second terminal device 20 may alternatively be an unmanned aerial vehicle, an internet of things (IoT) device, a station (ST) in a WLAN, a cellular phone, a smartphone, a cordless phone, a wireless data card, a tablet computer, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA) device, a laptop computer, a machine-type communication (MTC) terminal, 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 (also called a wearable intelligent device), a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in telemedicine, a smart grid (Smart Grid), a wireless terminal in self driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid (Smart Grid), ... The first terminal device 10 and the second terminal device 20 may alternatively be devices in device to device (D2D) communication, such as electric meters and water meters. The first terminal device 10 and the second terminal device 20 may alternatively be terminals in a 5G system, or terminals in a next-generation communication system. This is not limited in this embodiment of the present application.

[0064] It may be understood that the first terminal device 10 may further perform SL communication with a terminal device other than the second terminal device 20, and the second terminal device 20 may further perform SL communication with a terminal device other than the first terminal device 10. This is not limited herein.

[0065] The communication system may further include one or more access network devices 30 (only one is shown). In the present application, the first terminal device 10 and the second terminal device 20 may be located within the coverage of the same access network device, or the first terminal device 10 and the second terminal device 20 may be located within the coverage of different access network devices, or the first terminal device 10 is located within the coverage of the access network device and the second terminal device 20 is located out of coverage of the access network device, or the first terminal device 10 is located out of coverage of the access network device and the second terminal device 20 is located within the coverage of the access network device. This is not limited in the present specification.

[0066] The access network device 30 is a network side entity configured to transmit a signal, receive a signal, or transmit and receive a signal. The access network device 30 may be an apparatus deployed in a radio access network (RAN) and providing wireless communication functions to the first terminal device 10 and the second terminal device 20, and may be, for example, a transmission reception point (TRP), a base station, or a control node having various forms, for example, a network controller, a radio controller, or a radio controller in a cloud radio access network (CRAN) scenario. In particular, the access network device may be a macro base station having various forms, a micro base station (also called a small cell), a relay station, an access point (AP), a radio network controller (RNC), a NodeB (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved NodeB or a home NodeB, HNB), a baseBand unit (BBU), a transmitting reception point (TRP), a transmitting point (TP), a mobile switching center, etc., or may be an antenna panel of a base station. A control node may be connected to multiple base stations and configure resources for multiple terminals covered by the multiple base stations. In systems using different radio access technologies, the names of devices having base station functionality may be different.For example, the access network device 30 may be an evolved NodeB (eNB or eNodeB) in an LTE system, or may be a radio controller in a cloud radio access network (CRAN) scenario, or may be a gNB in ​​5G. Alternatively, the access network device 30 may be a relay station, an access point, a vehicle-mounted device, a wearable device, a network side device in a post-5G network, or an access network device in a future evolved PLMN network. The specific name of the access network device is not limited in this application.

[0067] It should be noted that the technical solutions provided in this embodiment of the present application are applicable to multiple system architectures. The network architectures and service scenarios described in this embodiment of the present application are intended to more clearly describe the technical solutions in this embodiment of the present application, and do not constitute limitations on the technical solutions provided in this embodiment of the present application. Those skilled in the art may know that with the development of network architectures and the emergence of new service scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0068] In order to facilitate the understanding of the relevant contents in the embodiments of the present application, some knowledge required in the solution of the present application is described below. Please note that these descriptions are intended to facilitate the understanding of the embodiments of the present application, and should not be considered as limitations on the scope of protection described in the claims of the present application.

[0069] 1. Sidelink (SL)

[0070] An SL is defined for direct communication between terminal devices. Specifically, an SL is a link over which terminal devices communicate directly with each other without forwarding by a base station.

[0071] Sidelink transmissions are performed between a source and destination pair. The source may be identified by a source layer-2 ID and the destination may be identified by a destination layer-2 ID. The source layer-2 ID identifies the sender UE of the data in the sidelink communication and the destination layer-2 ID identifies the target or receiver UE of the data in the sidelink communication. The sender is the source of the sidelink communication (or MAC PDU) and the receiver is the destination of the sidelink communication (or MAC PDU).

[0072] A UE in the following description includes, but is not limited to, a UE identified by a Layer 2 ID, and the UE uses the Layer 2 ID in sidelink communications.

[0073] Sidelink communication includes a unicast communication mode. For sidelink unicast communication, a PC5-RRC connection is a logical connection between two UEs identified by a source Layer 2 ID and a destination Layer 2 ID pair. The connection is considered to be established after a corresponding PC5 unicast link is established. One UE may have multiple PC5-RRC connections to one or more UEs, where the multiple PC5-RRC connections relate to different source-destination Layer 2 ID pairs.

[0074] 2.PC5 Reference Points / Interfaces

[0075] The PC5 reference point / interface is a reference point / interface between UEs.

[0076] 3.Uu Reference Points / Interfaces

[0077] The Uu reference point / interface is the reference point / interface between the UE and the radio access network (eg, NG-RAN or E-UTRAN).

[0078] 4. Packet Duplication

[0079] NR sidelink communication may support sidelink packet duplication, which is implemented in the PDCP layer of the UE. For sidelink packet duplication for transmission, PDCP PDUs are duplicated in a PDCP entity. The duplicated PDCP PDUs of the same PDCP entity are submitted to two different RLC entities and associated with two different sidelink logical channels, respectively. The duplicated PDCP PDUs of the same PDCP entity are only allowed to be transmitted on different sidelink carriers. Different sidelink logical channels corresponding to the same PDCP entity may be mapped to carriers in different carrier sets. For example, a PDCP entity corresponds to logical channel 1 and logical channel 2, where logical channel 1 is mapped to carriers in carrier set 1 and logical channel 2 is mapped to carriers in carrier set 2. Each of the carrier sets may include one or more carriers.

[0080] It should be noted that the 3rd generation partnership project (3GPP) is developing a standard for sidelink (SL) as a tool for user equipment (UE)-to-UE direct communication required in various use cases since long term evolution (LTE). Sidelink communication includes a unicast communication mode. In particular, in the unicast communication mode, a PC5 radio resource control (RRC) connection usually needs to be established between the source UE and the target UE. One UE may have multiple PC5-RRC connections for one or multiple UEs. Currently, transmission using one PC5-RRC connection is performed on only one carrier. If a SL radio link failure (RLF) is caused by a carrier, the terminal device releases the PC5-RRC connection. However, no solution has been proposed on how to handle SL RLF when transmission using one PC5-RRC connection is performed on multiple carriers.

[0081] Based on this, an embodiment of the present application provides a communication method such that the SL RLF can be processed when transmission using one PC5-RRC connection is performed on multiple carriers.

[0082] Please note that "feedback of data" in this embodiment of the present application may also be described as "feedback associated with data," and "receiving feedback on a carrier" in this embodiment of the present application may also be described as "receiving feedback at a carrier," without any limitation herein.

[0083] It should be noted that the "data" sent by the first terminal device to the second terminal device in this embodiment of the present application may be understood as a physical sidelink shared channel (PSSCH) or a medium access control (MAC) protocol data unit (PDU). In other words, the data in this embodiment of the present application may be carried in a PSSCH for transmission.

[0084] It should be noted that in this embodiment of the present application, "data feedback" may be understood as "physical sidelink feedback channel (PSFCH), hybrid automatic repeat request (HARQ) acknowledgement (ACK) information, etc." HARQ ACK information may be positive acknowledgement information, negative acknowledgement (NACK) information, etc. This is not limited herein. Alternatively, data feedback in this embodiment of the present application may be understood to be carried in the PSFCH for transmission.

[0085] Please note that the "feedback receiving occasion" in this embodiment of the present application may also be understood as a "PSFCH receiving occasion".

[0086] Please note that "no data feedback is received on the carrier at the feedback reception occasion" as described in this embodiment of the present application may also be described as "no PSFCH reception is present on the carrier at the PSFCH reception occasion".

[0087] In this embodiment of the present application, it should be noted that for data (e.g., data 1 sent on carrier 1) sent on a carrier (e.g., carrier 1), its feedback may have the following three cases:

[0088] Case 1: Feedback (eg, Feedback 1 for Data 1) may be sent entirely on the carrier on which the data was sent (ie, Carrier 1).

[0089] Case 2: Feedback (e.g., Feedback 1 for Data 1) may be all transmitted on another carrier other than Carrier 1, for example, all transmitted on Carrier 2, and in another example, all transmitted on Carrier 3.

[0090] Case 3: Feedback (e.g., feedback 1 of data 1) may be transmitted on multiple carriers (two or more carriers). For example, a part of the feedback is transmitted on carrier 1, and another part of the feedback is transmitted on another one or more carriers. For another example, a part of the feedback is transmitted on carrier 2, and another part of the feedback is transmitted on carrier 3, or another one or more carriers other than carrier 1. This is specifically determined based on the actual scenario and is not limited herein. For ease of explanation, in the following embodiments of the present application, it is used as an example for exemplary explanation that the feedback of data sent on one carrier may be all transmitted on the carrier on which the data was sent. Alternatively, it is used as an example for exemplary explanation that the feedback of data is all transmitted on another carrier.

[0091] It should be noted that the feedback receiving occasion on a carrier (eg, carrier 1 is still used as an example) in this embodiment of the present application may have the following three cases:

[0092] Case 1: Feedback receiving occasions on carrier 1 may only include feedback receiving occasions corresponding to data sent on carrier 1.

[0093] Case 2: Feedback receiving occasions on carrier 1 may only include feedback receiving occasions corresponding to data sent on another carrier (ie, a carrier other than carrier 1, e.g., carrier 2 or carrier 3).

[0094] Case 3: Feedback receiving occasions on carrier 1 may include feedback receiving occasions corresponding to data sent on carrier 1 and feedback receiving occasions corresponding to data sent on another carrier.

[0095] It should be noted that in this embodiment of the present application, the sidelink HARQ entity corresponding to a carrier may also be described as a sidelink HARQ entity corresponding to a PSSCH / MAC PDU transmission or as a sidelink HARQ entity corresponding to a PSFCH reception occasion, which is not limited herein.

[0096] It should be noted that the RLC bearer described in this embodiment of the present application may be replaced with a logical channel, or the RLC bearer described in this embodiment of the present application may be replaced with an RLC entity.

[0097] It should be noted that in this embodiment of the present application, the first terminal device may be understood as a source terminal device or a data sender, and the second terminal device may be described as a peer terminal device of the first terminal device, or may be understood as a destination terminal device or a data receiver.

[0098] Please note that initializing to 0 in this embodiment of the present application may also be described as setting to 0, and reinitializing to 0 in this embodiment of the present application may also be described as (re)setting to 0.

[0099] It should be noted that HARQ discontinuous transmission (DTX) in this embodiment of the present application may be understood as feedback of data not being received in a feedback receiving occasion for data.

[0100] It should be noted that in this embodiment of the present application, data sent on one carrier at different moments may be the same data or different data. This is not limited herein. Data sent on different carriers at the same moment may be the same data or different data. This is not limited herein. Data sent on different carriers at different moments may be the same data or different data. This is not limited herein. Data corresponding to feedback reception occasions at different moments on a carrier may be the same data (e.g., the same PSSCH or the same MAC PDU) or different data (e.g., different PSSCH or different MAC PDU). Data corresponding to feedback reception occasions at the same moment on different carriers may be the same data (e.g., the same PSSCH or the same MAC PDU) or different data (e.g., different PSSCH or different MAC PDU). Data corresponding to feedback reception occasions at different moments on different carriers may be the same data (e.g., the same PSSCH or the same MAC PDU) or different data (e.g., different PSSCH or different MAC PDU).

[0101] The communication method and the communication device provided in the present application are described in detail below.

[0102] Fig. 2 is a schematic flowchart of a communication method according to an embodiment of the present application. The method may be implemented by a first terminal device or may be implemented by a chip in the first terminal device. For ease of explanation, in the following, the first terminal device and the chip in the first terminal device are collectively referred to as the first terminal device. The method shown in Fig. 2 may include the following operations.

[0103] S201: A first terminal device establishes a sidelink ( SL ) and transmitting data over the multiple carriers to a second terminal device via the second terminal device.

[0104] In some implementations, the first terminal device may send data to the second terminal device on multiple carriers through a sidelink (SL). In particular, the first terminal device may send data to the second terminal device on multiple carriers through a PC5-RRC connection. Correspondingly, the second terminal device may receive data from the first terminal device on multiple carriers. The data sent by the first terminal device on the multiple carriers may be different data, or the data sent by the first terminal device on the multiple carriers may be the same data. This is not limited herein. For example, it is assumed that the multiple carriers include carrier 1, carrier 2, carrier 3, and carrier 4. Data 1 may be sent on carrier 1, data 2 may be sent on carrier 2, data 3 may be sent on carrier 3, and data 4 may be sent on carrier 4. Data 1, data 2, data 3, and data 4 are different. Alternatively, carrier 1, carrier 2, carrier 3, and carrier 4 may all be used to send data 1. It should be noted that the following embodiments of the present application are mainly described by using an example in which data 1 is sent on carrier 1, data 2 is sent on carrier 2, data 3 is sent on carrier 3, and data 4 is sent on carrier 4. In other words, all data sent on carrier 1 may be described as data 1, all data sent on carrier 2 may be described as data 2, all data sent on carrier 3 may be described as data 3, and all data sent on carrier 4 may be described as data 4. Data 1 sent on carrier 1 at different moments may be the same data or different data. Data 2 sent on carrier 2 at different moments may be the same data or different data. Data 3 sent on carrier 3 at different moments may be the same data or different data. Data 4 sent on carrier 4 at different moments may be the same data or different data. This is not limited in this specification.

[0105] S202: The first terminal device determines a feedback reception status of data at a feedback reception occasion on a plurality of carriers, and determines a SL radio link failure based on the feedback reception status. ( RLF ) occurs between the first terminal device and the second terminal device.

[0106] In some implementations, the first terminal device may determine a feedback reception status of data at a feedback reception occasion on multiple carriers. In particular, the first terminal device may determine a feedback reception status of data at a feedback reception occasion on multiple carriers based on a MAC layer entity. Furthermore, the first terminal device (or described as a MAC layer entity of the first terminal device) may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, whether a SL RLF occurs between the first terminal device and the second terminal device may also be described as whether a SL RLF of the second terminal device occurs. It should be noted that when it is determined that a SL RLF occurs between the first terminal device and the second terminal device, the MAC layer entity of the first terminal device may further indicate to an upper layer (e.g., an RRC layer of the first terminal device) that a SL RLF is detected.

[0107] It should be noted that in implementation (1), determining the feedback reception status of data at feedback reception occasions on multiple carriers may be understood as sequentially determining whether the feedback of data is received at each of the feedback reception occasions on each of the multiple carriers. Specifically, when the transmission using one PC5-RRC connection is performed on multiple carriers, the statistics on the PSFCH reception occasions related to each transmission of the PSSCH / MAC PDU on each of the carriers may be collected together, and the carrier in which the PSFCH reception occasion is included is not distinguished. The statistical manner may be that the processing is performed in a sequence of the PSFCH reception occasions on the multiple carriers in the time domain. Optionally, the processing in each of the feedback reception occasions on the multiple carriers may not be limited to being performed in a sequence in the time domain. This is specifically determined based on the actual application scenario, and is not limited in this specification. For ease of understanding, the following mainly uses an example in which the processing is performed in a sequence in the time domain for exemplary explanation.

[0108] Furthermore, the first terminal device may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status may be understood as maintaining a first amount (or the first amount may also be understood as a counter) for one PC5-RRC connection and initializing the first amount to 0. Once the PC5-RRC connection is established or the first threshold is (re)configured, the first amount is (re)initialized to 0. Furthermore, for all feedback reception occasions on multiple carriers, the feedback reception occasions are processed in sequence in the time domain. When the first amount of consecutive times during which no feedback of data is received on multiple carriers is smaller than the first threshold and feedback of data is received in the next feedback reception occasion, the first amount is set to 0. When the first amount of continuous time during which no data feedback is received on the multiple carriers is less than a first threshold and no data feedback is received in the next feedback receiving occasion, the first amount is incremented by 1. By analogy, when the first amount of continuous time during which no data feedback is received on the multiple carriers is equal to or greater than a first threshold, it is determined that a SL RLF occurs between the first terminal device and the second terminal device. The first threshold may be configured by the network device (base station) or may be pre-configured (pre-configured). This is not limited in this specification.

[0109] For example, Figure 3 is a diagram of a scenario for determining a SL RLF according to an embodiment of the present application. As shown in Figure 3, transmissions using one PC5-RRC connection are performed on carrier 1, carrier 2, and carrier 3. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, and data 3 is sent on carrier 3. Data 1 sent on carrier 1 at different moments may be the same data or different data. Data 2 sent on carrier 2 at different moments may be the same data or different data. Data 3 sent on carrier 3 at different moments may be the same data or different data. This is not limited herein. In Figure 3, an example in which feedback of data 1 may be all sent on carrier 1, feedback of data 2 may be all sent on carrier 2, and feedback of data 3 may be all sent on carrier 3 is mainly used for illustrative explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in Figure 3. This is specifically determined based on the actual scenario and is not limited herein. For a PC5-RRC connection, a variable a (i.e., a first quantity) is maintained and variable a is initialized to 0. Once a PC5-RRC connection is established or the first threshold is (re)configured, variable a is (re)initialized to 0. The first threshold is assumed to be 4.

[0110] Therefore, the process of collecting statistics on the PSFCH reception occasions without distinguishing the carrier on which the PSFCH reception occasions are included is as follows.

[0111] If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 1, variable a is initialized to 0; If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 3, variable a is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 1 corresponding to data 2, the variable a is incremented by 1 and the variable a is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 1, variable a is incremented by 1 and variable a is equal to 2; If a PSFCH reception occurs at PSFCH reception occasion 2 corresponding to data 3, variable a is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 2, the variable a is incremented by 1 and the variable a is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 1, variable a is incremented by 1 and variable a is equal to 2; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 3, the variable a is incremented by 1 and the variable a is equal to 3; If there is no PSFCH reception at PSFCH reception occasion 4 corresponding to data 1, variable a is incremented by 1 and variable a is equal to 4.

[0112] In this case, if the variable a (ie, variable a=4) reaches a first threshold (ie, 4), then a SL RLF is considered to be detected between the first terminal device and the second terminal device.

[0113] It should be noted that when multiple PSFCH receiving occasions overlap in the time domain, the PSFCH receiving occasion that is processed first may not be limited or a specific rule may be specified. For example, the PSFCH receiving occasion with an earlier start time is processed first, or the PSFCH receiving occasion with an earlier end time is processed first. This is not limited in this specification. For ease of understanding, the following mainly uses an example in which the PSFCH receiving occasion with an earlier end time is processed first for exemplary explanation.

[0114] For example, FIG. 4 is a diagram of another scenario of determining a SL RLF according to an embodiment of the present application. As shown in FIG. 4, the first PSFCH receiving occasion on carrier 1 overlaps with the first PSFCH receiving occasion on carrier 3 in the time domain. The processing rule of the two PSFCH receiving occasions may be that the processing is performed in a sequence that processes the PSFCH receiving occasion with an earlier end time first. As shown in FIG. 4, the transmission using one PC5-RRC connection is performed on carrier 1, carrier 2, and carrier 3. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, and data 3 is sent on carrier 3. Data 1 sent on carrier 1 at different moments may be the same data or different data, data 2 sent on carrier 2 at different moments may be the same data or different data, and data 3 sent on carrier 3 at different moments may be the same data or different data. This is not limited herein. The feedback of data 1 is all transmitted on carrier 1, and the feedback of data 2 is all transmitted on carrier 2. In FIG. 4, an example in which the feedback of data 3 may be all transmitted on carrier 3 is mainly used for exemplary explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in FIG. 4. This is specifically determined based on the actual scenario and is not limited herein. For the PC5-RRC connection, a variable b (i.e., a first amount) is maintained, and the variable b is initialized to 0. Once the PC5-RRC connection is established or the first threshold is (re)configured, the variable b is (re)initialized to 0. The first threshold is assumed to be 4.

[0115] Therefore, the statistical step of first processing the PSFCH reception occasions with earlier end times without distinguishing the carrier on which the PSFCH reception occasion is contained is as follows:

[0116] If a PSFCH reception is present at the PSFCH reception occasion corresponding to the instant T0, the variable b is initialized to 0; If a PSFCH reception is present at the PSFCH reception occasion corresponding to the instant T1, the variable b is reinitialized to 0; If there is no PSFCH reception at the PSFCH reception occasion corresponding to the instant T2, the variable b is increased by 1 so that the variable b is equal to 1; If there is no PSFCH reception at the PSFCH reception occasion corresponding to the instant T3, the variable b is increased by 1 and the variable b is equal to 2; If a PSFCH reception is present at the PSFCH reception occasion corresponding to the instant T4, the variable b is reinitialized to 0; If there is no PSFCH reception at the PSFCH reception occasion corresponding to the instant T5, the variable b is increased by 1 so that the variable b is equal to 1; If there is no PSFCH reception at the PSFCH reception occasion corresponding to the instant T6, the variable b is increased by 1 and the variable b is equal to 2; If no PSFCH reception is present at the PSFCH reception occasion corresponding to the instant T7, the variable b is incremented by 1 and the variable b is equal to 3; If there is no PSFCH reception at the PSFCH reception occasion corresponding to the instant T8, the variable b is increased by 1 and the variable b is equal to 4.

[0117] In this case, if the variable b (ie, variable b=4) reaches a first threshold, then a SL RLF is considered to be detected between the first terminal device and the second terminal device.

[0118] Typically, one carrier may correspond to one sidelink HARQ entity. For example, carrier 1 corresponds to sidelink HARQ entity 1, carrier 2 corresponds to sidelink HARQ entity 2, and carrier 3 corresponds to sidelink HARQ entity 3. In implementation (1), a logical entity that performs the addition or (re)initialization of the variable corresponding to the multiple carriers (i.e., the first amount) may be any one of the multiple sidelink HARQ entities corresponding to the multiple carriers, e.g., sidelink HARQ entity 1, sidelink HARQ entity 2, or sidelink HARQ entity 3.

[0119] In another implementation (2), determining the feedback reception status of data in feedback reception occasions on multiple carriers may alternatively be understood as sequentially determining whether the feedback of data is received in each of the feedback reception occasions on a first carrier, and the first carrier is any one of the multiple carriers. The determination manner may be that the processing is performed in the sequence of all PSFCH reception occasions on each of the carriers in the time domain, or may not be performed in the sequence in the time domain. This is not limited in this specification. For easy understanding, the following mainly uses an example in which the processing is performed in the sequence in the time domain for exemplary explanation.

[0120] In particular, the following uses an example in which the feedback receiving occasion on a carrier is case 3 for explanation. Specifically, sequentially determining whether feedback of data is received in each of the feedback receiving occasions on the first carrier may be understood as sequentially determining whether feedback of data is received in all feedback receiving occasions on the first carrier. All feedback receiving occasions in this specification include feedback receiving occasions corresponding to the first data sent on the first carrier and feedback receiving occasions corresponding to the data sent on another carrier.

[0121] Furthermore, the first terminal device may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status may be understood as maintaining a second amount (or the second amount may also be understood as a counter) for each of the carriers in one PC5-RRC connection and initializing the second amount to 0. Once the PC5-RRC connection is established or the second threshold is (re)configured, or the first carrier is configured, or the first carrier is activated, the second amount is (re)initialized to 0. Furthermore, for all feedback reception occasions on the first carrier, the feedback reception occasions are processed in sequence in the time domain. When the second amount of continuous time during which no feedback of data is received on the first carrier is smaller than the second threshold and feedback of data is received in the next feedback reception occasion, the second amount is set to 0. When the second amount of continuous time during which no data feedback is received on the first carrier is less than a second threshold and no data feedback is received in the next feedback receiving occasion, the second amount is incremented by 1. By analogy, when the second amount of continuous time during which no data feedback is received on the first carrier is equal to or greater than a second threshold, it is determined that an SL RLF occurs between the first terminal device and the second terminal device on the first carrier. In this specification, the occurrence of an SL RLF between the first terminal device and the second terminal device on the first carrier may also be understood as the amount of continuous HARQ DTX of the second terminal device on the first carrier reaching a maximum amount.

[0122] Optionally, in the implementation, a SL RLF is considered to occur between the first terminal device and the second terminal device when an amount of continuous HARQ DTX on each of all carriers used by the first terminal device to send data to the second terminal device reaches a maximum amount.

[0123] Optionally, in the implementation, it is considered that no SL RLF occurs between the first terminal device and the second terminal device when the amount of consecutive HARQ DTX on some carriers used by the first terminal device to send data to the second terminal device does not reach a maximum amount.

[0124] The second threshold may be configured by the network device (base station) or may be pre-configured (pre-configured). This is not limited herein. Note that in this embodiment of the present application, the second threshold may be configured for each of the different carriers. In another implementation, the different carriers may alternatively use the same second threshold. Note that the first threshold may be the same as the second threshold, or the first threshold may be different from the second threshold. This is not limited herein.

[0125] For example, FIG. 5 is a diagram of another scenario of determining SL RLF according to an embodiment of the present application. As shown in FIG. 5, data may be sent on carrier 1, carrier 2, and carrier 3 using one PC5-RRC connection. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, and data 3 is sent on carrier 3. Data 1 sent on carrier 1 at different moments may be the same data or different data, data 2 sent on carrier 2 at different moments may be the same data or different data, and data 3 sent on carrier 3 at different moments may be the same data or different data. This is not limited herein. In FIG. 5, an example in which feedback of data 1 is all sent on carrier 1, feedback of data 2 may also be all sent on carrier 1, and feedback of data 3 may all sent on carrier 3 is mainly used for illustrative explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in FIG. 5. This is specifically determined based on the actual scenario and is not limited herein. Thus, a variable may be maintained for each of carrier 1, carrier 2, and carrier 3. Specifically, a variable c is maintained for carrier 1, a variable d is maintained for carrier 2, and a variable e is maintained for carrier 3. The variables c, d, and e are initialized to 0. In this specification, the variables c, d, and e may be understood as a second quantity, respectively. The second threshold is assumed to be 5. The details are as follows.

[0126] 1. On carrier 1, carrier 1 includes PSFCH reception occasions corresponding to data 1 and data 2. Therefore, the process of collecting statistics for all feedback reception occasions on carrier 1 is as follows:

[0127] If a PSFCH reception occurs at PSFCH reception occasion 1 corresponding to data 1, variable c is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 1 corresponding to data 2, variable c is incremented by 1 and variable c is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 1, variable c is incremented by 1 and variable c is equal to 2; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 2, variable c is incremented by 1 and variable c is equal to 3; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 1, variable c is incremented by 1 and variable c is equal to 4; If there is no PSFCH reception at PSFCH reception occasion 4 corresponding to data 1, variable c is incremented by 1 and variable c is equal to 5.

[0128] In this case, if the variable c (ie, variable c=5) reaches a second threshold, it is determined that a SL RLF occurs on carrier 1 between the first terminal device and the second terminal device.

[0129] 2. There is no PSFCH reception occasion for any data on carrier 2. Therefore, the statistical result of all feedback reception occasions on carrier 2 is that the variable d is 0.

[0130] In this case, if the variable d (ie, variable d=0) does not reach the second threshold, it is determined that a SL RLF does not occur on carrier 2 between the first terminal device and the second terminal device.

[0131] 3. On carrier 3, carrier 3 only contains PSFCH reception occasions corresponding to data 3. Therefore, the process of collecting statistics for all feedback reception occasions on carrier 3 is as follows:

[0132] If a PSFCH reception occurs at PSFCH reception occasion 1 corresponding to data 3, variable e is reinitialized to 0; If a PSFCH reception occurs at PSFCH reception occasion 2 corresponding to data 3, variable e is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 3, variable e is incremented by 1 and variable e is equal to 1.

[0133] In this case, if the variable e (i.e., variable e=1) does not reach the second threshold, it is determined that a SL RLF does not occur between the first terminal device and the second terminal device on carrier 3. A SL RLF does not occur between the first terminal device and the second terminal device on carrier 3 may also be understood as an amount of continuous HARQ DTX of the second terminal device on carrier 3 not reaching a maximum amount.

[0134] Note that if there are no feedback receiving occasions on a carrier, statistics for the carrier need not be collected. In other words, in the above example, variable d does not need to be maintained for carrier 2.

[0135] Typically, one carrier may correspond to one sidelink HARQ entity. For example, carrier 1 corresponds to sidelink HARQ entity 1, carrier 2 corresponds to sidelink HARQ entity 2, and carrier 3 corresponds to sidelink HARQ entity 3. In implementation (2), the logical entity performing the increment or (re)initialization of the variables corresponding to the carrier may be the sidelink HARQ entity corresponding to the carrier. The logical entity performing the increment or (re)initialization of the variables corresponding to the carrier may include the sidelink HARQ entity corresponding to the data related to the feedback reception occasion on that carrier (the data may be data sent on another carrier). In other words, the logical entity collecting statistics regarding the feedback reception status on the carrier may be the sidelink HARQ entity corresponding to the carrier. For example, the logical entity collecting statistics regarding the feedback reception status on carrier 1 may be the sidelink HARQ entity 1, the logical entity collecting statistics regarding the feedback reception status on carrier 2 may be the sidelink HARQ entity 2, and the logical entity collecting statistics regarding the feedback reception status on carrier 3 may be the sidelink HARQ entity 3. A sidelink HARQ entity corresponding to a carrier may be understood as a sidelink HARQ entity corresponding to data sent on that carrier or, alternatively, as a sidelink HARQ entity corresponding to feedback reception occasions on that carrier.

[0136] A logical entity performing the incrementation or (re)initialization of variables corresponding to a carrier may further include a sidelink HARQ entity corresponding to data related to feedback reception occasions on that carrier (which may be data sent on another carrier). For example, a logical entity collecting statistics regarding feedback reception status on carrier 1 may be sidelink HARQ entity 1 and a sidelink HARQ entity corresponding to data sent on carrier 2.

[0137] In another implementation (3), determining the feedback reception status of data at feedback reception occasions on multiple carriers may alternatively be understood as sequentially determining whether the feedback of the first data sent on the first carrier is received at each of the feedback reception occasions for the first data, and the first carrier is any one of the multiple carriers. The first data in this specification is the data sent on the first carrier. The determination manner may be that the processing is performed in the sequence of the PSFCH reception occasions for the PSSCH / MAC PDU sent on each of the carriers in the time domain, or may not be performed in the sequence in the time domain. This is not limited in this specification. For ease of understanding, the following mainly uses an example in which the processing is performed in the sequence in the time domain for exemplary explanation.

[0138] It should be noted that each of the feedback receiving occasions for the first data sent on the first carrier may be on one or more carriers, and the one or more carriers may include the first carrier or may not include the first carrier. This is not limited in this specification. Alternatively, each of the feedback receiving occasions for the first data sent on the first carrier may include only feedback receiving occasions on the first carrier. In the following, for the purpose of explanation, an example is used in which each of the feedback receiving occasions for the first data sent on the first carrier may be on one or more carriers.

[0139] Furthermore, the first terminal device may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status may be understood as maintaining a third amount (or the third amount may also be understood as a counter) for each of the carriers in one PC5-RRC connection and initializing the third amount to 0. Once the PC5-RRC connection is established or the third threshold is (re)configured, or the first carrier is configured, or the first carrier is activated, the third amount is (re)initialized to 0. Furthermore, for all feedback reception occasions for the first data sent on the first carrier, the feedback reception occasions for the first data are processed in a sequence in the time domain. When the third amount of continuous time during which the feedback of the first data is not received on the first carrier is smaller than the third threshold and the feedback of the first data is received at the next feedback receiving occasion for the first data, the third amount is set to 0. When the third amount of continuous time during which the feedback of the first data is not received on the first carrier is smaller than the third threshold and the feedback of the first data is not received at the next feedback receiving occasion for the first data, the third amount is incremented by 1. By analogy, when the third amount of continuous time during which the feedback of the first data is not received is equal to or greater than the third threshold, it is determined that the SL RLF occurs between the first terminal device and the second terminal device on the first carrier. In this specification, the occurrence of the SL RLF between the first terminal device and the second terminal device on the first carrier may also be understood as the amount of continuous HARQ DTX of the second terminal device on the first carrier reaching a maximum amount.

[0140] Optionally, in the implementation, a SL RLF is considered to occur between the first terminal device and the second terminal device when an amount of continuous HARQ DTX on each of all carriers used by the first terminal device to send data to the second terminal device reaches a maximum amount.

[0141] Optionally, in the implementation, it is considered that no SL RLF occurs between the first terminal device and the second terminal device when the amount of consecutive HARQ DTX on some carriers used by the first terminal device to send data to the second terminal device does not reach a maximum amount.

[0142] The third threshold may be configured by the network device (base station) or may be pre-configured (pre-configured). This is not limited herein. Please note that in this embodiment of the present application, the third threshold may be configured for each of the different carriers. In another implementation, the different carriers may alternatively use the same third threshold. Please note that the first threshold, the second threshold, and the third threshold may be in different forms from each other, or the first threshold, the second threshold, and the third threshold may be partially the same, for example, the first threshold and the second threshold may be the same, the third threshold and the first threshold (or the second threshold) may be different, or the first threshold, the second threshold, and the third threshold may all be the same. This is not limited herein.

[0143] For example, Figure 6 is a diagram of another scenario of determining SL RLF according to an embodiment of the present application. As shown in Figure 6, data may be sent on carrier 1, carrier 2, and carrier 3 using one PC5-RRC connection. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, and data 3 is sent on carrier 3. Data 1 sent on carrier 1 at different moments may be the same data or different data, data 2 sent on carrier 2 at different moments may be the same data or different data, and data 3 sent on carrier 3 at different moments may be the same data or different data. This is not limited herein. In Figure 6, an example in which feedback of data 1 is all sent on carrier 1, feedback of data 2 may also be all sent on carrier 1, and feedback of data 3 is all sent on carrier 3 is mainly used for illustrative explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in Figure 6. This is specifically determined based on the actual scenario and is not limited herein. Thus, a variable may be maintained for each of carrier 1, carrier 2, and carrier 3. Specifically, a variable f is maintained for carrier 1, a variable g is maintained for carrier 2, and a variable h is maintained for carrier 3. The variables f, g, and h are initialized to 0. In this specification, the variables f, g, and h may be understood as a third quantity, respectively. The third threshold is assumed to be 3. The details are as follows.

[0144] 1. The process of collecting statistics for PSFCH reception occasions corresponding to Data 1 sent on Carrier 1 is as follows.

[0145] If there is a PSFCH reception on carrier 1 at PSFCH reception occasion 1 corresponding to data 1, then the variable f is 0; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 1, variable f is incremented by 1 and variable f is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 1, variable f is incremented by 1 and variable f is equal to 2; If there is no PSFCH reception at PSFCH reception occasion 4 corresponding to data 1, variable f is incremented by 1 and variable f is equal to 3.

[0146] In this case, if the variable f (ie, variable f=3) reaches a third threshold, it is determined that a SL RLF occurs on carrier 1 between the first terminal device and the second terminal device.

[0147] 2. The process of collecting statistics for PSFCH reception occasions corresponding to Data 2 sent on Carrier 2 is as follows.

[0148] If there is no PSFCH reception on carrier 2 in PSFCH reception occasion 1 corresponding to data 2, variable g is incremented by 1 so that variable g is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 2, variable g is incremented by 1 and variable g is equal to 2.

[0149] In this case, if the variable g (i.e., variable g=2) does not reach the third threshold, it is determined that a SL RLF does not occur between the first terminal device and the second terminal device on carrier 2. A SL RLF does not occur between the first terminal device and the second terminal device on carrier 2 may also be understood as an amount of continuous HARQ DTX of the second terminal device on carrier 2 not reaching a maximum amount.

[0150] 3. The process of collecting statistics regarding PSFCH reception occasions corresponding to Data 3 sent on Carrier 3 is as follows.

[0151] If there is a PSFCH reception on carrier 3 at PSFCH reception occasion 1 corresponding to data 3, the variable h is reinitialized to 0; If a PSFCH reception occurs at PSFCH reception occasion 2 corresponding to data 3, variable h is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 3, variable h is incremented by 1 and variable h is equal to 1.

[0152] In this case, if the variable h (i.e., the variable h=1) does not reach the third threshold, it is determined that a SL RLF does not occur between the first terminal device and the second terminal device on carrier 3. A SL RLF does not occur between the first terminal device and the second terminal device on carrier 3 may also be understood as the amount of continuous HARQ DTX of the second terminal device on carrier 3 not reaching a maximum amount.

[0153] Typically, one carrier may correspond to one sidelink HARQ entity. For example, carrier 1 corresponds to sidelink HARQ entity 1, carrier 2 corresponds to sidelink HARQ entity 2, and carrier 3 corresponds to sidelink HARQ entity 3. In implementation (3), a logical entity that performs addition or (re)initialization on a variable corresponding to a carrier may be a sidelink HARQ entity corresponding to the carrier. In other words, a logical entity that collects statistics on feedback reception status on a carrier may be a sidelink HARQ entity corresponding to the carrier. For example, a logical entity that collects statistics on feedback reception status on carrier 1 may be sidelink HARQ entity 1, a logical entity that collects statistics on feedback reception status on carrier 2 may be sidelink HARQ entity 2, and a logical entity that collects statistics on feedback reception status on carrier 3 may be sidelink HARQ entity 3. A sidelink HARQ entity corresponding to a carrier may be understood as a sidelink HARQ entity corresponding to data sent on that carrier. Alternatively, a sidelink HARQ entity corresponding to a carrier may be understood as a sidelink HARQ entity corresponding to a feedback reception occasion on that carrier.

[0154] In another implementation (4), the multiple carriers used for data transmission may be grouped for statistics collection, in other words, the multiple carriers used for data transmission may be divided into multiple carrier groups, whereby statistics are collected for each of the carrier groups. Different carrier groups may include different carriers. The first carrier group may be any one of the multiple carrier groups. For example, the multiple carriers are assumed to include carrier 1, carrier 2, carrier 3, and carrier 4, where carrier 1 and carrier 2 may form carrier group 1, and carrier 3 and carrier 4 may form carrier group 2.

[0155] In particular, in the above implementation (4), there are two possible statistical methods:

[0156] In the first statistical manner, statistics on feedback reception status in all feedback receiving occasions on the first carrier group are collected. In other words, determining the feedback reception status of data in feedback receiving occasions on multiple carriers may alternatively be understood as sequentially determining whether feedback of data is received in each of the feedback receiving occasions on each of the carriers in the first carrier group. The first carrier group may include two or more carriers, and the two or more carriers in the first carrier group are included in the multiple carriers. Sequentially determining whether feedback of data is received in each of the feedback receiving occasions on the first carrier group may be understood as sequentially determining whether feedback of data is received in all feedback receiving occasions on the first carrier group. All feedback receiving occasions in this specification include feedback receiving occasions corresponding to data sent on the first carrier group and feedback receiving occasions corresponding to data sent on another carrier group.

[0157] Further, the first terminal device may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, determining whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status may be understood as maintaining a fourth amount for each of the different carrier groups in one PC5-RRC connection and initializing the fourth amount to 0. Once the PC5-RRC connection is established, or the fourth threshold is (re)configured, or the fourth carrier group is (re)configured, or the fourth carrier group is activated, or any carrier in the fourth carrier group is (re)configured, or any carrier in the fourth carrier group is (re)activated, the fourth amount is (re)initialized to 0. For all feedback reception occasions on the first carrier group, the feedback reception occasions are processed in sequence in the time domain. When the fourth amount of continuous time during which data feedback is not received on the first carrier group is less than a fourth threshold and data feedback is received at the next feedback receiving occasion, the fourth amount is set to 0. When the fourth amount of continuous time during which data feedback is not received on the first carrier group is less than a fourth threshold and data feedback is not received at the next feedback receiving occasion, the fourth amount is incremented by 1. By analogy, when the fourth amount of continuous time during which data feedback is not received on the first carrier group is equal to or greater than the fourth threshold, it is determined that a SL RLF occurs on the first carrier group between the first terminal device and the second terminal device.

[0158] In this specification, the occurrence of an SL RLF on a first carrier group between a first terminal device and a second terminal device may also be understood as the amount of continuous HARQ DTX of the second terminal device on the first carrier group reaching a maximum amount.

[0159] In the implementation, an SL RLF is considered to occur between the first terminal device and the second terminal device when the amount of continuous HARQ DTX on each of all carrier groups used by the first terminal device to send data to the second terminal device reaches a maximum amount.

[0160] In the implementation, it is considered that no SL RLF occurs between the first terminal device and the second terminal device when the amount of consecutive HARQ DTX on some carrier groups used by the first terminal device to send data to the second terminal device does not reach a maximum amount.

[0161] The fourth threshold may be configured by the network device (base station) or may be pre-configured (pre-configured). This is not limited herein. Please note that in this embodiment of the present application, the fourth threshold may be configured for each of the different carrier groups. In another implementation, the different carrier groups may alternatively use the same fourth threshold. Please note that the first threshold, the second threshold, the third threshold, and the fourth threshold may be different from each other, or the first threshold, the second threshold, the third threshold, and the fourth threshold may be partially the same, for example, the first threshold and the second threshold may be the same, and the third threshold, the fourth threshold, and the first threshold (or the second threshold) may be different, or the first threshold, the second threshold, the third threshold, and the fourth threshold may all be the same. This is not limited herein.

[0162] For example, Figure 7a is a diagram of another scenario of determining SL RLF according to an embodiment of the present application. As shown in Figure 7a, data may be sent on carrier 1, carrier 2, carrier 3, and carrier 4 using one PC5-RRC connection. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, data 3 is sent on carrier 3, and data 4 is sent on carrier 4. Data 1 sent on carrier 1 at different moments may be the same data or different data, data 2 sent on carrier 2 at different moments may be the same data or different data, data 3 sent on carrier 3 at different moments may be the same data or different data, and data 4 sent on carrier 4 at different moments may be the same data or different data. This is not limited herein. In Figure 7a, an example in which feedback of data 1 is all sent on carrier 1, feedback of data 2 is all sent on carrier 2, feedback of data 3 is all sent on carrier 2, and feedback of data 4 is all sent on carrier 4 is mainly used for exemplary explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in FIG. 7a. This is specifically determined based on the actual scenario and is not limited herein. A variable i may be maintained for a carrier group 1 formed by carrier 1 and carrier 2, and a variable j may be maintained for a carrier group 2 formed by carrier 3 and carrier 4. The variables i and j are initialized to 0. The variables i and j in this specification may be understood as a fourth quantity. Specifically, in order to collect statistics on the feedback situation, carrier 1 and carrier 2 may be grouped into carrier group 1, and carrier 3 and carrier 4 may be grouped into carrier group 2. The fourth threshold is assumed to be 4. The details are as follows.

[0163] 1. On carrier group 1, carrier 1 in carrier group 1 includes PSFCH receiving occasions corresponding to data 1, and carrier 2 in carrier group 1 includes PSFCH receiving occasions corresponding to data 2 and data 3. Thus, the process of collecting statistics for all feedback receiving occasions on carrier group 1 is as follows:

[0164] If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 1, variable i is initialized to 0; If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 3, variable i is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 1 corresponding to data 2, variable i is incremented by 1 and variable i is equal to 1; If a PSFCH reception is present at PSFCH reception occasion 2 corresponding to data 1, variable i is reinitialized to 0; If a PSFCH reception is present at PSFCH reception occasion 2 corresponding to data 3, variable i is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 2, variable i is incremented by 1 and variable i is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 1, variable i is incremented by 1 and variable i is equal to 2; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 3, variable i is incremented by 1 and variable i is equal to 3; If there is no PSFCH reception in PSFCH reception occasion 4 corresponding to data 1, variable i is incremented by 1 and variable i is equal to 4;

[0165] In this case, if the variable i (ie, variable i=4) reaches a fourth threshold, it is determined that a SL RLF occurs on carrier group 1 between the first terminal device and the second terminal device.

[0166] 2. On carrier group 2, carrier 3 in carrier group 2 does not include a PSFCH receiving occasion corresponding to any data, and carrier 4 in carrier group 2 includes a PSFCH receiving occasion corresponding to data 4. Therefore, the process of collecting statistics for all feedback receiving occasions on carrier group 2 is as follows:

[0167] If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 4, variable j is initialized to 0; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 4, variable j is incremented by 1 and variable j is equal to 1;

[0168] If a PSFCH reception occurs at PSFCH reception occasion 3 corresponding to data 4, then the variable j is reinitialized to 0.

[0169] In this case, if the variable j (i.e., variable j=0) does not reach the fourth threshold, it is determined that a SL RLF does not occur between the first terminal device and the second terminal device on carrier group 2. A SL RLF does not occur between the first terminal device and the second terminal device on carrier group 2 may also be understood as the amount of continuous HARQ DTX of the second terminal device on carrier group 2 not reaching a maximum amount.

[0170] In the second statistical manner, statistics on feedback reception status at feedback reception occasions corresponding to the first carrier group data sent on the first carrier group are collected. In other words, determining the feedback reception status of data at feedback reception occasions on multiple carriers may alternatively be understood as sequentially determining whether feedback of the first carrier group data is received at each of the feedback reception occasions for the first carrier group data sent on the first carrier group, the first carrier group being any one of the multiple carrier groups. In this specification, the first carrier group data is the data sent on the first carrier group. In other words, all data sent on the first carrier group is described as the first carrier group data. Furthermore, the first terminal device may determine whether a SL RLF occurs between the first terminal device and the second terminal device based on the feedback reception status. In this specification, determining whether a SL RLF occurs between a first terminal device and a second terminal device based on the feedback reception status may be understood as maintaining a fifth amount (or the fifth amount may also be understood as a counter) for each of the carrier groups in one PC5-RRC connection and initializing the fifth amount to 0. Once the PC5-RRC connection is established or the fifth threshold is (re)configured, the fifth amount is (re)initialized to 0.

[0171] Further, for all feedback receiving occasions for the first carrier group data sent on the first carrier group, the feedback receiving occasions for the first carrier group data are processed in sequence in the time domain. When a fifth amount of consecutive time during which feedback of the first carrier group data is not received on the first carrier group is smaller than a fifth threshold and feedback of the first carrier group data is received at a next feedback receiving occasion for the first carrier group data, the fifth amount is set to 0. When a fifth amount of consecutive time during which feedback of the first carrier group data is not received on the first carrier group is smaller than a fifth threshold and feedback of the first carrier group data is not received at a next feedback receiving occasion for the first carrier group data, the fifth amount is incremented by 1. By analogy, when a fifth amount of consecutive time during which feedback of the first carrier group data is not received on the first carrier group is equal to or greater than a fifth threshold, it is determined that a SL RLF occurs on the first carrier group between the first terminal device and the second terminal device.

[0172] In this specification, the occurrence of an SL RLF on a first carrier group between a first terminal device and a second terminal device may also be understood as the amount of continuous HARQ DTX of the second terminal device on the first carrier group reaching a maximum amount.

[0173] In the implementation, an SL RLF is considered to occur between the first terminal device and the second terminal device when the amount of continuous HARQ DTX on each of all carrier groups used by the first terminal device to send data to the second terminal device reaches a maximum amount.

[0174] In the implementation, it is considered that no SL RLF occurs between the first terminal device and the second terminal device when the amount of consecutive HARQ DTX on some carrier groups used by the first terminal device to send data to the second terminal device does not reach a maximum amount.

[0175] The fifth threshold may be configured by the network device (base station) or may be pre-configured (pre-configured). This is not limited in this specification. Please note that in this embodiment of the present application, the fifth threshold may be configured for each of the different carrier groups. Please note that the first threshold, the second threshold, the third threshold, the fourth threshold, and the fifth threshold may be different from each other, or the first threshold, the second threshold, the third threshold, the fourth threshold, and the fifth threshold may be partially the same or all the same, etc. This is not limited in this specification.

[0176] For example, Figure 7b is a diagram of another scenario of determining SL RLF according to an embodiment of the present application. As shown in Figure 7b, data may be sent on carrier 1, carrier 2, carrier 3, and carrier 4 using one PC5-RRC connection. In particular, data 1 is sent on carrier 1, data 2 is sent on carrier 2, data 3 is sent on carrier 3, and data 4 is sent on carrier 4. Data 1 sent on carrier 1 at different moments may be the same data or different data, data 2 sent on carrier 2 at different moments may be the same data or different data, data 3 sent on carrier 3 at different moments may be the same data or different data, and data 4 sent on carrier 4 at different moments may be the same data or different data. This is not limited herein. In Figure 7b, an example in which feedback of data 1 is all sent on carrier 1, feedback of data 2 is all sent on carrier 2, feedback of data 3 is all sent on carrier 2, and feedback of data 4 is all sent on carrier 4 is mainly used for exemplary explanation. It may be understood that the feedback situation may not be limited to the feedback situation shown in FIG. 7b. This is specifically determined based on the actual scenario and is not limited herein. A variable k may be maintained for a carrier group 1 formed by carrier 1 and carrier 2, and a variable l may be maintained for a carrier group 2 formed by carrier 3 and carrier 4. The variables k and l are initialized to 0. The variables k and l may be understood as a fifth quantity. Specifically, in order to collect statistics on the feedback situation, carrier 1 and carrier 2 may be grouped into carrier group 1, and carrier 3 and carrier 4 may be grouped into carrier group 2. The fifth threshold is assumed to be 3. The details are as follows.

[0177] 1. The process of collecting statistics regarding feedback reception occasions corresponding to data sent on carrier group 1 is as follows.

[0178] If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 1, variable k is initialized to 0; If there is no PSFCH reception in PSFCH reception occasion 1 corresponding to data 2, the variable k is incremented by 1, and the variable k is equal to 1; If a PSFCH reception occurs at PSFCH reception occasion 2 corresponding to data 1, variable k is reinitialized to 0; If there is no PSFCH reception in the PSFCH reception occasion 3 corresponding to the data 2, the variable k is incremented by 1, and the variable k is equal to 1; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 1, the variable k is incremented by 1, and the variable k is equal to 2; If there is no PSFCH reception at PSFCH reception occasion 4 corresponding to data 1, then variable k is incremented by 1 and variable k is equal to 3.

[0179] In this case, if the variable k (ie, variable k=3) reaches a fifth threshold, it is determined that a SL RLF occurs on carrier group 1 between the first terminal device and the second terminal device.

[0180] 2. The process of collecting statistics regarding feedback reception occasions corresponding to data sent on carrier group 2 is as follows.

[0181] If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 3, variable l is initialized to 0; If a PSFCH reception is present at PSFCH reception occasion 1 corresponding to data 4, variable l is reinitialized to 0; If a PSFCH reception is present at PSFCH reception occasion 2 corresponding to data 3, variable l is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 2 corresponding to data 4, variable l is incremented by 1 and variable l is equal to 1; If a PSFCH reception occurs at PSFCH reception occasion 3 corresponding to data 4, variable l is reinitialized to 0; If there is no PSFCH reception in PSFCH reception occasion 3 corresponding to data 3, variable l is incremented by 1 and variable l is equal to 1.

[0182] In this case, if the variable l (i.e., variable l=1) does not reach the fifth threshold, it is determined that a SL RLF does not occur between the first terminal device and the second terminal device on carrier group 2. In this specification, a SL RLF does not occur between the first terminal device and the second terminal device on carrier group 2 may also be understood as an amount of continuous HARQ DTX of the second terminal device on carrier group 2 not reaching a maximum amount.

[0183] Typically, one carrier may correspond to one sidelink HARQ entity. For example, carrier 1 corresponds to sidelink HARQ entity 1, carrier 2 corresponds to sidelink HARQ entity 2, carrier 3 corresponds to sidelink HARQ entity 3, and carrier 4 corresponds to sidelink HARQ entity 4. In implementation (4), a logical entity that performs an increment or (re)initialization on the variable k for a carrier group should be a sidelink HARQ entity corresponding to any carrier in the carrier group. For example, it is assumed that carrier 1 and carrier 2 form carrier group 1, and carrier 3 and carrier 4 form carrier group 2. In this case, a logical entity that collects statistics on feedback reception status on carrier group 1 may be sidelink HARQ entity 1 or sidelink HARQ entity 2, and a logical entity that collects statistics on feedback reception status on carrier group 2 may be sidelink HARQ entity 3 or sidelink HARQ entity 4.

[0184] Optionally, in some implementations, when the first terminal device cannot determine the particular carrier on which the SL RLF occurs, but can only determine that the SL RLF occurs in the PC5-RRC connection, the first terminal device releases the PC5-RRC connection. In this specification, releasing the PC5-RRC connection may be understood as releasing the data radio bearer (DRB) and the signaling radio bearer (SRB) of the second terminal device, discarding the configuration of the NR sidelink communication relationship of the second terminal device, resetting the sidelink specific MAC of the second terminal device, and indicating to higher layers that the PC5-RRC connection of the second terminal device is released (in other words, PC5 is unavailable). In other words, when the first terminal device cannot determine a specific carrier on which the amount of continuous HARQ DTX reaches a maximum amount and cannot determine a specific carrier on which the amount of RLC entity retransmission reaches a maximum amount, the first terminal device can only determine that a SL RLF occurs in the PC5-RRC connection, and the first terminal device releases the PC5-RRC connection, releases the data radio bearer and the signaling radio bearer of the second terminal device, discards the configuration of the NR sidelink communication relationship of the second terminal device, resets the sidelink specific MAC of the second terminal device, and indicates to higher layers that the PC5-RRC connection of the second terminal device is released (in other words, PC5 is unavailable).

[0185] Optionally, in some implementations, when the first terminal device may determine the first carrier on which the SL RLF occurs, the first terminal device may delete or release the first carrier. The first terminal device deleting and / or releasing the first carrier may be understood as at least one of the following: the first terminal device deleting the first carrier from the carriers used by the first terminal device to send data to the second terminal device, the first terminal device deleting the first carrier from the carriers used by the first terminal device to receive data sent by the second terminal device, the first terminal device clearing an SL grant allocated to the second terminal device on the first carrier, and the first terminal device refreshing a HARQ buffer associated with the first carrier of the second terminal device.

[0186] In this implementation of the present application, the first terminal device may determine the first carrier on which the SL RLF occurs may also be understood as the first terminal device may determine the first carrier on which the amount of continuous HARQ DTX reaches a maximum amount, or the first terminal device may determine the first carrier on which the amount of RLC entity retransmissions reaches a maximum amount.

[0187] Optionally, in an implementation, an SL RLF is considered to occur between a first terminal device and a second terminal device when an SL RLF occurs on each of all carriers used by the first terminal device to send data to the second terminal device.

[0188] Optionally, in an implementation, an SL RLF is considered to not occur between a first terminal device and a second terminal device when an SL RLF does not occur on some carriers used by the first terminal device to send data to the second terminal device.

[0189] Optionally, in some implementations, when the first terminal device determines the first carrier on which the SL RLF occurs, the first terminal device may further send first indication information to the second terminal device. Correspondingly, the second terminal device receives the first indication information from the first terminal device. The first indication information indicates that the SL RLF occurs on the first carrier, or the first indication information indicates that the first carrier should be deleted or released. In other words, the second terminal device may delete or release the first carrier based on the first indication information. The second terminal device deleting or releasing the first carrier may be understood as the second terminal device deleting the first carrier from the carriers used by the second terminal device to receive data from the first terminal device, and / or the second terminal device deleting the first carrier from the carriers used by the second terminal device to send feedback to the first terminal device, and / or the second terminal device clearing an SL grant allocated to the first terminal device on the first carrier, and / or the second terminal device refreshing a HARQ buffer associated with the first carrier of the first terminal device.

[0190] Optionally, in some implementations, when the first terminal device is in an RRC connected mode, specifically, when there is an RRC connection between the first terminal device and an access network device (e.g., a base station), the first terminal device may further send second indication information to the access network device, where the second indication information indicates the first carrier on which the SL RLF occurs. Implementations in which the second indication information indicates the first carrier on which the SL RLF specifically occurs include the following: 1. The second indication information may directly include carrier information of the first carrier on which the SL RLF occurs, and may be information such as, for example, an identifier of the first carrier, an index of the first carrier, or a frequency channel number of the first carrier. This is not limited herein. Thus, after receiving the second indication information from the first terminal device, the access network device may determine the first carrier on which the SL RLF occurs based on the carrier information of the first carrier in the second indication information. 2. The second indication information may alternatively include carrier information of the available carrier currently used by the first terminal device to send data to the second terminal device. Thus, the access network device determines that the available carrier does not include the first carrier based on the second indication information received from the first terminal device. The access network device may alternatively determine the first carrier on which the SL RLF occurs based on the second indication information received from the first terminal device and with reference to the carrier information in the second indication information previously received by the access network device and about the available carrier used by the first terminal device to send data to the second terminal device. For example, it is assumed that the second indication information previously received by the access network device includes carrier 1, carrier 2, and carrier 3, and the second indication information currently received by the access network device includes carrier 1 and carrier 2.Therefore, the access network device may determine that carrier 3 is the carrier on which the SL RLF occurs.

[0191] Optionally, in some implementations, in addition to sending the second indication information to the access network device, the first terminal device may further send information about the second terminal device to the access network device, for example, a Layer 2 identifier (i.e., a Layer 2 ID) of the second terminal device, which is not limited in this specification.

[0192] It should be noted that the second indication information and / or the information about the second terminal device may be carried in a sidelinkUEInformationNR message such as 3GPP TS 38.331, which is not limited in this specification.

[0193] It should be noted that after receiving the second indication information and / or the information about the second terminal device, the access network device may send third indication information to the first access network device, where the third indication information indicates to the first terminal device that the first carrier on which the SL RLF occurs should be deleted or released. Therefore, the first terminal device deleting or releasing the first carrier may be understood as the first terminal device deleting or releasing the first carrier in response to the third indication information.

[0194] Optionally, in some implementations, after the first terminal device deletes or releases the first carrier, the access network device then no longer schedules the first terminal device to send data to the second terminal device on the first carrier.

[0195] In this embodiment of the present application, when transmissions using one PC5-RRC connection are performed on multiple carriers, statistics related to PSFCH reception occasions related to respective transmissions of PSSCH / MAC PDUs on each of the carriers may be collected together to determine whether a SL RLF occurs in the PC5-RRC connection. Alternatively, when transmissions using one PC5-RRC connection are performed on multiple carriers, statistics related to PSFCH reception occasions related to respective transmissions of PSSCH / MAC PDUs on different carriers may be collected separately to determine whether a SL RLF occurs on a particular carrier in the PC5-RRC connection. In other words, in this embodiment of the present application, it is possible to determine whether a SL RLF occurs when transmissions using one PC5-RRC connection are performed on multiple carriers.

[0196] Furthermore, when the first terminal device determines that the SL RLF occurs on the first carrier, the first terminal device sends a first indication information to the second terminal device to inform the second terminal device that the first carrier on which the SL RLF occurs should be deleted or released. This reduces unnecessary communication interruption caused in the conventional technology in which the PC5-RRC connection is directly released when the SL RLF is found. In other words, in the embodiment of the present application, the first carrier on which the SL RLF specifically occurs may be determined, and when the first carrier on which the SL RLF specifically occurs is determined, only the first carrier is deleted or released, and another carrier on which the SL RLF does not occur can still be used for normal communication between the first terminal device and the second terminal device. This improves communication reliability.

[0197] Figure 8 is another schematic flowchart of a communication method according to an embodiment of the present application. The method may be implemented by a first terminal device or may be implemented by a chip in the first terminal device. For ease of explanation, in the following, the first terminal device and the chip in the first terminal device are collectively referred to as the first terminal device. The method shown in Figure 8 may include the following operations.

[0198] S801: A first terminal device establishes a sidelink ( SL ) Radio Link Failure ( RLF ) occurs on the first carrier.

[0199] In some implementations, the first terminal device ( SL ) Radio Link Failure ( RLF ) occurs on a first carrier, the first carrier being any one or more of a plurality of carriers used by the first terminal device to send data to the second terminal device.

[0200] In particular, the first terminal device determining that a SL RLF occurs on a first carrier may be understood as the first terminal device determining that a SL RLF occurs on a first carrier associated with a first RLC entity when the first terminal device determines, based on a first radio link control (RLC) entity, that an amount of data retransmissions reaches a maximum amount of retransmissions, and the first RLC entity is used by the first terminal device to send data to a second terminal device. It should be noted that the data transmitted by the first RLC entity may also be described as an RLC service data unit (SDU). In other words, when the first RLC entity of the first terminal device determines that an amount of RLC SDU retransmissions to a second RLC entity of a second terminal device reaches a maximum amount of retransmissions, it means that the first RLC entity causes / incurs a SL RLF, or it means that the carrier associated with the first RLC entity (i.e., the first carrier) causes / incurs a SL RLF. It should be noted that there may be one or more first carriers associated with the first RLC entity.

[0201] Furthermore, the first terminal device determining that the SL RLF occurs on the first carrier associated with the first RLC entity may be determined by the first terminal device in accordance with a first radio link control ( RLC )If the amount of data retransmissions based on the entity reaches a maximum amount of retransmissions and the first RLC entity is determined to be an RLC entity corresponding to a packet data convergence protocol (PDCP) entity using packet duplication, the first terminal device may be understood as determining that a SL RLF occurs on a first carrier associated with the first RLC entity. In a packet duplication scenario, the transmission performed by the first RLC entity may be mapped to a carrier set (which may also be understood as the transmission performed by the first RLC entity being mapped to a carrier set corresponding to a logical channel corresponding to the first RLC entity), and it should be noted that one carrier set includes one or more carriers. Thus, the first terminal device may determine one or more carriers in the carrier set associated with the first RLC entity as the first carrier, i.e., as the one or more carriers on which the SL RLF occurs.

[0202] In a scenario in which the first carrier associated with the first RLC entity may be understood as a scenario in which the first carrier includes multiple carriers, or the carrier set associated with the first RLC entity may be understood as a scenario in which the first carrier includes multiple carriers, it should be noted that after the first terminal device determines that the SL RLF occurs on the first carrier (which may be understood as the first carrier associated with the first RLC entity, or the carrier set associated with the first RLC entity), the first terminal device may further send first information to the second terminal device on each of the carriers in the first carrier, and the first information is used to trigger the second terminal device to feed back the second information. If the first terminal device does not receive the second information sent by the second terminal device on the second carrier, or if the first terminal device does not receive the second information sent by the second terminal device on the second carrier within a preset time after sending the first information, the first terminal device determines that the SL RLF occurs on the second carrier, and the second carrier is any carrier among the first carriers. The first information may be information that triggers channel state information (CSI) feedback, or the first information may be a medium access control control element (MAC CE), etc. This is not limited herein. Correspondingly, the second information may be a CSI report, or the second information may be a MAC CE, etc. This is not limited herein. In other words, in a scenario in which a SL RLF is determined to occur, or in a scenario in which a SL RLF is determined to occur on multiple carriers, the first information and the second information may be further used to determine which carrier or carriers cause the SL RLF.

[0203] It should be noted that if it is possible to specifically determine from a first carrier which carrier or carriers (i.e., second carriers) on which a SL RLF occurs, then it may be specifically indicated which carrier or carriers among the first carrier (i.e., second carriers) need to be released when it is later indicated that a carrier should be released, such that carriers in the first carrier on which a SL RLF does not occur are not released.

[0204] S802: A first terminal device sends first indication information to a second terminal device.

[0205] In some implementations, the first terminal device sends first indication information to the second terminal device. Correspondingly, the second terminal device receives the first indication information from the first terminal device. The first indication information indicates that a SL RLF occurs on the first carrier, or the first indication information indicates that the first carrier should be deleted or released. In other words, the second terminal device may delete or release the first carrier based on the first indication information. The second terminal device deleting or releasing the first carrier may be understood as at least one of the following: The second terminal device removing the first carrier from carriers used by the second terminal device to receive data from the first terminal device, the second terminal device removing the first carrier from carriers used by the second terminal device to send feedback to the first terminal device, the second terminal device clearing an SL grant allocated to the first terminal device on the first carrier, and the second terminal device refreshing a HARQ buffer associated with the first carrier of the first terminal device.

[0206] Optionally, in some implementations, when the first terminal device determines the first carrier on which the SL RLF occurs, the first terminal device may further delete or release the first carrier. The first terminal device deleting and / or releasing the first carrier may be understood as at least one of the following: the first terminal device deleting the first carrier from the carriers used by the first terminal device to send data to the second terminal device, the first terminal device deleting the first carrier from the carriers used by the first terminal device to receive feedback from the second terminal device, the first terminal device clearing an SL grant allocated to the second terminal device on the first carrier, and the first terminal device refreshing a HARQ buffer associated with the first carrier of the second terminal device.

[0207] Optionally, in some implementations, when the first carrier includes multiple carriers, if the multiple carriers in the first carrier are all carriers corresponding to one RLC bearer, the first terminal device may suspend transmission performed by an RLC entity in the RLC bearer and the corresponding logical channel, or may release the RLC entity in the RLC bearer and the corresponding logical channel, or may map the logical channel corresponding to the RLC bearer to another carrier (or another new carrier or carriers), and may re-establish the RLC entity in the RLC bearer and the corresponding logical channel.

[0208] It should be noted that the new carrier among the one or more new carriers may be a carrier that was originally mapped to another RLC entity that corresponds to the same PDCP entity as the RLC entity, and this other RLC entity is no longer mapped to the new carrier. For example, if the carriers to which the other RLC entity was originally mapped include carrier 1 and carrier 2, the RLC entity is now mapped to carrier 1, and the other RLC entity is no longer mapped to carrier 1. The new carrier among the one or more new carriers may alternatively be a carrier other than the carrier that was mapped to another RLC entity that corresponds to the same PDCP entity as the RLC entity. This is not limited herein.

[0209] Optionally, in some implementations, when the first terminal device is in an RRC connected mode and the multiple carriers in the first carrier are all carriers corresponding to one RLC bearer, the first terminal device may further send a fourth indication information to the access network device. The fourth indication information may indicate information about the RLC bearer. For example, the fourth indication information may include an RLC bearer configuration index, etc. This is not limited herein. Alternatively, the fourth indication information may indicate information about the RLC configuration, or the fourth indication information may indicate information about the logical channel, etc. This is not limited herein. Thus, after receiving the fourth indication information from the first terminal device, the access network device may determine that all carriers corresponding to the RLC bearer or logical channel are the first carriers on which the SL RLF occurs based on the information about the RLC bearer, the information about the RLC configuration, or the information about the logical channel in the fourth indication information.

[0210] Optionally, in some implementations, in addition to sending the fourth indication information to the access network device, the first terminal device may further send information about the second terminal device to the access network device, for example, a Layer 2 identifier (i.e., a Layer 2 ID) of the second terminal device, which is not limited in this specification.

[0211] It should be noted that the fourth indication information and / or the information about the second terminal device may be carried in a sidelinkUEInformationNR message, which is not limited in this specification.

[0212] It should be noted that after receiving the fourth indication information and / or the information regarding the second terminal device, the access network device may further send fifth indication information to the first access network device, where the fifth indication information indicates to the first terminal device that it should suspend transmission performed by the RLC entity in the RLC bearer and the corresponding logical channel, or the fifth indication information indicates to the first terminal device that it should release the RLC entity in the RLC bearer and the corresponding logical channel, or the fifth indication information indicates to the first terminal device that it should map the logical channel corresponding to the RLC bearer to another carrier and re-establish the RLC entity in the RLC bearer and the corresponding logical channel. Therefore, the first terminal device may suspend transmissions performed by the RLC entities on the RLC bearers and corresponding logical channels, or release the RLC entities on the RLC bearers and corresponding logical channels, or map the logical channels corresponding to the RLC bearers to another carrier and re-establish the RLC entities on the RLC bearers and corresponding logical channels, which may be understood as the first terminal device suspending transmissions performed by the RLC entities on the RLC bearers and corresponding logical channels in response to the fifth indication information, or the first terminal device releasing the RLC entities on the RLC bearers and corresponding logical channels in response to the fifth indication information, or the first terminal device mapping the logical channels corresponding to the RLC bearers to another carrier and re-establishing the RLC entities on the RLC bearers and corresponding logical channels.

[0213] Optionally, the access network device may further send information to the first terminal device indicating that the packet duplication should be reconfigured, and / or the access network device may further send information to the first terminal device indicating that two carrier sets should be configured.

[0214] Optionally, the first terminal device may further send sixth indication information to the second terminal device. Correspondingly, the second terminal device receives sixth indication information from the first terminal device. The sixth indication information indicates information about the RLC bearer / RLC configuration / logical channel that causes the SL RLF. After receiving the sixth indication information, the second terminal device may delete / release the carrier corresponding to the RLC bearer / RLC configuration / logical channel indicated by the sixth indication information. The correspondence / mapping between the RLC bearer / RLC configuration / logical channel and the carrier may be obtained in advance by the second terminal device. For example, the first terminal device configures the correspondence / mapping between the RLC bearer / RLC configuration / logical channel and the carrier for the second terminal device.

[0215] Optionally, the first terminal device may further send seventh indication information to the second terminal device. Correspondingly, the second terminal device receives seventh indication information from the first terminal device. The seventh indication information indicates that the correspondence / mapping between the RLC bearer / RLC configuration / logical channel and the carrier should be configured / modified / updated. The RLC bearer / RLC configuration / logical channel is an RLC that causes / incurs the SL RLF. The RLC bearer / RLC configuration / logical channel includes an RLC that causes / incurs the SL RLF and another RLC that corresponds to the same PDCP entity as the RLC that causes / incurs the SL RLF.

[0216] Optionally, the first terminal device may further delete / release the RLC bearer / RLC configuration / logical channel that causes / incurs the SL RLF. Optionally, the first terminal device may further send eighth indication information to the second terminal device. Correspondingly, the second terminal device receives eighth indication information from the first terminal device. The eighth indication information indicates that the RLC bearer / RLC configuration / logical channel corresponding to the PDCP entity / sidelink radio bearer SLRB should be configured / modified / updated and / or the RLC bearer / RLC configuration / logical channel that causes / incurs the SL RLF should be deleted / released.

[0217] Optionally, in some implementations, packet duplication is no longer used for the PDCP entity corresponding to the RLC bearer that causes / incurs the SL RLF.

[0218] Optionally, in some implementations, after the first terminal device deletes or releases the first carrier, the access network device then no longer schedules the first terminal device to send data to the second terminal device on the first carrier.

[0219] In this embodiment of the present application, when transmission using one PC5-RRC connection is performed on multiple carriers, the first terminal device can determine one specific carrier or multiple specific carriers (i.e., the first carrier) that cause the SL RLF. In addition, when it is determined that the SL RLF is caused by the first carrier, the PC5-RRC connection is not released, but only the first carrier is deleted or released, and another carrier in which the SL RLF does not occur can still be used for normal communication between the first terminal device and the second terminal device. This reduces unnecessary communication interruptions caused when a SL RLF is detected, thereby improving communication reliability.

[0220] Hereinafter, the communication device according to the present application will be described in detail with reference to FIG. 9 and FIG.

[0221] FIG. 9 is a diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 9 may be configured to implement some or all of the functions of the terminal device in the method embodiments described in FIG. 2 to FIG. 8. The device may be a terminal device, an apparatus in a terminal device, or an apparatus that can be used with a terminal device. The communication device may alternatively be a chip system. The communication device shown in FIG. 9 may include a transceiver unit 901 and a processing unit 902. The processing unit 902 is configured to implement data processing. The transceiver unit 901 is integrated with a receiving unit and a transmitting unit. The transceiver unit 901 may also be referred to as a communication unit. Alternatively, the transceiver unit 901 may be split into a receiving unit and a transmitting unit. The description of the processing unit 902 is similar to that of the transceiver unit 901, and the details will not be described again below. The details are as follows.

[0222] The first implementation is as follows:

[0223] The transceiver unit 901 is a side link ( SL ) The second terminal device is configured to transmit data over the multiple carriers via the second terminal device.

[0224] The processing unit 902 is configured to determine a feedback reception status of data at a feedback reception occasion on a plurality of carriers, where the feedback reception occasion is a feedback reception occasion for the data.

[0225] The processing unit 902 detects an SL radio link failure based on the feedback reception status. ( RLF ) occurs between the first terminal device and the second terminal device.

[0226] In a possible implementation, the processing unit 902 may include: sequentially determining whether feedback of data is received at each of the feedback reception occasions on each of a plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device when a first amount of continuous time during which no data feedback is received on the plurality of carriers is greater than or equal to a first threshold; The present invention is configured to:

[0227] In a possible implementation, after the processing unit 902 sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit 902: setting the first amount to zero if a first amount of continuous time during which no feedback of data is received on the multiple carriers is less than a first threshold and feedback of data is received at a next feedback receiving occasion; or if a first amount of continuous time during which no data feedback is received on the multiple carriers is less than a first threshold and no data feedback is received at a next feedback receiving occasion, adding one to the first amount. The device is further configured to:

[0228] In a possible implementation, the processing unit 902 may include: sequentially determining whether feedback of data is received at each of the feedback receiving occasions on a first carrier, the first carrier being any one of the plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier when a second amount of continuous time during which no data feedback is received on the first carrier is greater than or equal to a second threshold; The present invention is configured to:

[0229] In a possible implementation, after the processing unit 902 sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit 902: setting the second amount to zero if the second amount of continuous time during which no feedback of data is received on the first carrier is less than a second threshold and feedback of data is received at the next feedback receiving occasion; or if a second amount of continuous time during which no data feedback is received on the first carrier is less than a second threshold and no data feedback is received at a next feedback receiving occasion, adding one to the second amount. The device is further configured to:

[0230] In a possible implementation, the processing unit 902 may include: sequentially determining whether feedback of first data sent on a first carrier is received at each of feedback receiving occasions for the first data, the first carrier being any one of a plurality of carriers; determining that a SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a third amount of continuous time during which no first data feedback is received is greater than or equal to a third threshold; The present invention is configured to perform the following steps.

[0231] In a possible implementation, after the processing unit 902 sequentially determines whether feedback of data is received at each of the feedback receiving occasions on each of the multiple carriers, the processing unit 902: setting the third amount to zero if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is received at a next feedback receiving occasion for the first data; or if a third amount of continuous time during which feedback of the first data is not received on the first carrier is less than a third threshold and feedback of the first data is not received at a next feedback receiving occasion for the first data, adding one to the third amount. The device is further configured to:

[0232] In a possible implementation, the transceiver unit 901 comprises: The method is further configured to send first indication information to the second terminal device, the first indication information indicating that a SL RLF occurs on the first carrier, or the first indication information indicating that the first carrier should be deleted or released.

[0233] In a possible implementation, the processing unit 902 may include: Remove or release the first carrier The method is further configured as follows.

[0234] In a possible implementation, the transceiver unit 901 comprises: The access network device is further configured to send second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0235] In the second implementation,

[0236] The processing unit 902 is a side link ( SL ) Radio Link Failure ( RLF ) occurs on a first carrier, the first carrier being any one or more of a plurality of carriers used by the first terminal device to send data to the second terminal device.

[0237] The transceiver unit 901 is configured to send first indication information to the second terminal device, where the first indication information indicates the first carrier or the first indication information indicates that the first carrier should be deleted or released.

[0238] In a possible implementation, the processing unit 902 may include: First Radio Link Control ( RLC ) The system is configured to determine that if an amount of data retransmissions determined based on the entity reaches a maximum amount of retransmissions, a SL RLF occurs on a first carrier associated with the first RLC entity, and the first terminal device sends data to a second terminal device through the first RLC entity.

[0239] In a possible implementation, the processing unit 902 may include: First Radio Link Control ( RLC ) The amount of data retransmission determined based on the entity reaches a maximum amount of retransmission, and the first RLC entity performs a packet data convergence protocol using packet duplication. ( PDCP ) If the RLC entity corresponds to the first RLC entity, determine that the SL RLF occurs on a first carrier associated with the first RLC entity. It is configured as follows.

[0240] In a possible implementation, the first carrier includes multiple carriers, and after the processing unit 902 determines that the SL RLF occurs on the first carrier, the processing unit 902: sending first information to a second terminal device on each of the carriers in the first carriers, the first information being used to trigger the second terminal device to feed back second information; determining that a SL RLF occurs on a second carrier when second information sent by a second terminal device is not received on the second carrier, the second carrier being any carrier among the first carriers; The device is further configured to:

[0241] In a possible implementation, the processing unit 902 may include: Remove or release the first carrier The method is further configured as follows.

[0242] In a possible implementation, the transceiver unit 901 comprises: The access network device is further configured to send second indication information to the access network device, the second indication information indicating that the SL RLF occurs on the first carrier.

[0243] For another possible implementation of the communication device, please refer to the relevant descriptions of the functions of the terminal device in the method embodiments corresponding to Figures 2 to 8. Details will not be described again in this specification.

[0244] FIG. 10 is a diagram of the structure of another communication device according to an embodiment of the present application. As shown in FIG. 10, the communication device may be a terminal device (e.g., a first terminal device or a second terminal device) described in the embodiment of the present application, and is configured to implement the functions of the terminal device in FIG. 2 to FIG. 8. For ease of explanation, FIG. 10 shows only the main components of the terminal device 1000. As shown in FIG. 10, the terminal device 1000 includes a processor, a memory, a control circuit, an antenna, and an input / output device. The processor is mainly configured to process communication protocols and communication data, control the entire terminal device 1000, execute software programs, and process data of the software programs. The memory is mainly configured to store software programs and data. The control circuit is mainly configured to convert baseband signals and radio frequency signals, and process radio frequency signals. The antenna is mainly configured to receive and send radio frequency signals in the form of electromagnetic waves. The input / output device, for example, a touch screen, a display, a microphone, or a keyboard, is mainly configured to receive data input by a user and output data to a user.

[0245] For example, the terminal device 1000 is a mobile phone. After the terminal device 1000 is powered on, the processor can read the software program in the storage unit, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be sent wirelessly, after performing baseband processing on the data to be sent, the processor outputs the baseband signal to the control circuit, and after performing radio frequency processing on the baseband signal, the control circuit sends the radio frequency signal in the form of electromagnetic waves through the antenna. When data is sent to the terminal device 1000, the control circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, and the processor converts the baseband signal into data and processes the data.

[0246] Those skilled in the art may understand that for ease of explanation, FIG. 10 shows only one memory and only one processor. In some embodiments, the terminal device 1000 may include multiple processors and multiple memories. The memory may also be referred to as a storage medium, a storage device, etc. This is not limited in this embodiment of the present invention.

[0247] In an optional implementation, the processor may include a baseband processor and a central processing unit. The baseband processor is mainly configured to process communication protocols and communication data, and the central processing unit is mainly configured to control the entire terminal device 1000, execute software programs, and process data of the software programs. The processor of FIG. 10 incorporates the functions of the baseband processor and the central processing unit. Those skilled in the art may understand that the baseband processor and the central processing unit may alternatively be processors independent of each other and are connected to each other by using a technology such as a bus. The terminal device 1000 may include multiple baseband processors to accommodate different network standards, the terminal device 1000 may include multiple central processing units to improve the processing capabilities of the terminal device, and the components of the terminal device 1000 may be connected through various buses. The baseband processor may also be represented as a baseband processing circuit or a baseband processing chip. The central processing unit may also be represented as a central processing circuit or a central processing chip. The functions of processing the communication protocol and communication data may be built into the processor or may be stored in a storage unit in the form of a software program, and the processor executes the software program to implement the baseband processing functions.

[0248] In an example, an antenna and a control circuit having receiving and transmitting capabilities may be considered as a transceiver unit 1010 of the terminal device 1000, and a processor having processing capabilities may be considered as a processing unit 1020 of the terminal device 1000. As shown in FIG. 10, the terminal device 1000 includes a transceiver unit 1010 and a processing unit 1020. The transceiver unit may also be referred to as a transceiver, a transceiver machine, a transceiver device, etc. Optionally, a component present in the transceiver unit 1010 and configured to implement a receiving capability may be considered as a receiving unit, and a component present in the transceiver unit 1010 and configured to implement a transmitting capability may be considered as a transmitting unit. In other words, the transceiver unit 1010 includes a receiving unit and a transmitting unit. For example, the receiving unit may also be referred to as a receiving machine, a receiver, a receiving circuit, etc., and the transmitting unit may also be referred to as a transmitting machine, a transmitter, a transmitting circuit, etc.

[0249] An embodiment of the present application further provides a computer-readable storage medium, which stores instructions, which, when executed on a processor, implement the method steps in the above method embodiments.

[0250] An embodiment of the present application further provides a computer program product, which, when run on a processor, implements the method steps in the above method embodiments.

[0251] Those skilled in the art may realize that the units and steps may be implemented by electronic hardware or a combination of computer software and electronic hardware in combination with the examples described in the embodiments disclosed herein. Whether a function is implemented by hardware or software depends on the design constraints of a specific application and technical solution. Those skilled in the art may use different methods to implement the functions described for each specific application, but the implementation should not be considered to go beyond the scope of this application.

[0252] In some embodiments provided in the present application, it should be understood that the disclosed system, device, and method may be implemented in another manner. For example, the described device embodiment is only an example. For example, the division into units is only a logical functional division. The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, and may be located in one location or distributed over multiple network units. Some or all of the units may be selected based on actual requirements to achieve the purpose of the solution of the embodiment.

[0253] When the function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application essentially, or a part that contributes to the prior art, or a part of the technical solution may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes some instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or part of the steps of the method described in the embodiments of the present application. The computer-readable storage medium may be any available medium that can be accessed by a computer. For example, a computer-readable medium may include, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), universal serial bus flash disk, a removable hard disk, another optical disk memory, a magnetic disk storage medium, or another magnetic storage device, or any other medium that can be used to carry or store the anticipated program code in the form of instructions or data structures and that can be accessed by a computer.Additionally, many forms of RAM may be used, such as, by way of example and not limitation, static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchronous link dynamic random access memory (synchlink DRAM, SLDRAM), and direct rambus random access memory (direct rambus RAM, DR RAM).

[0254] The above description is merely a specific implementation of the present application and is not intended to limit the scope of protection of the embodiments of the present application. Any variations or replacements that are easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present application shall fall within the scope of protection of the embodiments of the present application. Therefore, the scope of protection of the embodiments of the present application shall be subject to the scope of protection of the claims.

Claims

1. 1. A communication method, the method being applied to a first terminal device, sending data over a side link (SL) to a second terminal device on multiple carriers; determining a feedback reception status of the data at a feedback reception occasion on the plurality of carriers, the feedback reception occasion being a feedback reception occasion for the data; determining whether an SL radio link failure (RLF) occurs between the first terminal device and the second terminal device based on the feedback receiving status; A communication method comprising:

2. The step of determining a feedback reception status of the data at a feedback reception occasion on the plurality of carriers comprises: determining sequentially whether feedback of the data is received at each of the feedback reception occasions on each of the plurality of carriers; The step of determining whether an SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: determining that the SL RLF occurs between the first terminal device and the second terminal device when a first amount of continuous time during which the data feedback is not received on the multiple carriers is equal to or greater than a first threshold; The method of claim 1.

3. After the step of sequentially determining whether feedback of the data is received at each of the feedback reception occasions on each of the plurality of carriers, the method further comprises: setting the first amount to zero if the first amount of continuous time during which feedback of the data is not received on the multiple carriers is less than the first threshold and feedback of the data is received at a next feedback receiving occasion; or if the first amount of continuous time during which feedback of the data is not received on the multiple carriers is less than the first threshold and feedback of the data is not received at a next feedback receiving occasion, adding one to the first amount. The method of claim 2 further comprising:

4. The step of determining a feedback reception status of the data at a feedback reception occasion on the plurality of carriers comprises: determining sequentially whether the feedback of the data is received at each of the feedback receiving occasions on a first carrier, the first carrier being any one of the plurality of carriers; The step of determining whether an SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: determining that the SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a second amount of continuous time during which the data feedback is not received on the first carrier is equal to or greater than a second threshold; The method of claim 1.

5. After the step of sequentially determining whether feedback of the data is received on a first carrier at each of the feedback reception occasions, the method further comprises: setting the second amount to zero if the second amount of continuous time during which feedback of the data is not received on the first carrier is less than the second threshold and feedback of the data is received at the next feedback receiving occasion; or if the second amount of continuous time during which feedback of the data is not received on the first carrier is less than the second threshold and feedback of the data is not received at a next feedback receiving occasion, adding one to the second amount. The method of claim 4 further comprising:

6. The step of determining a feedback reception status of the data at a feedback reception occasion on the plurality of carriers comprises: determining sequentially whether feedback of first data sent on a first carrier is received at each of feedback receiving occasions for the first data, the first carrier being any one of the plurality of carriers; The step of determining whether an SL RLF occurs between the first terminal device and the second terminal device based on the feedback receiving status includes: determining that the SL RLF occurs between the first terminal device and the second terminal device on the first carrier if a third amount of continuous time during which feedback of the first data is not received is equal to or greater than a third threshold; The method of claim 1.

7. After the step of sequentially determining whether feedback of first data sent on a first carrier is received at each of feedback receiving occasions for the first data, the method further comprises: setting the third amount to zero if the third amount of continuous time during which feedback of the first data is not received on the first carrier is less than the third threshold and feedback of the first data is received at a next feedback receiving occasion for the first data; or if the third amount of continuous time during which feedback of the first data is not received on the first carrier is less than the third threshold and feedback of the first data is not received at a next feedback receiving occasion for the first data, adding one to the third amount. The method of claim 6 further comprising:

8. The method comprises: Further comprising the step of sending first indication information to the second terminal device, the first indication information indicating that the SL RLF occurs on the first carrier, or the first indication information indicating that the first carrier should be deleted or released.

8. The method according to any one of claims 4 to 7.

9. The method comprises: Removing or releasing the first carrier. The method of any one of claims 4 to 8, further comprising:

10. The method comprises: and sending a second indication to an access network device, the second indication indicating that the SL RLF occurs on the first carrier.

10. The method according to any one of claims 4 to 9.

11. 1. A communication method, the method being applied to a first terminal device, determining that a sidelink (SL) Radio Link Failure (RLF) occurs on a first carrier, the first carrier being any one or more of a plurality of carriers used by the first terminal device to send data to a second terminal device; sending a first indication information to the second terminal device, the first indication information indicating the first carrier or the first indication information indicating that the first carrier should be deleted or released; A communication method comprising:

12. The step of determining that a SL RLF occurs on a first carrier comprises: determining that the SL RLF occurs on the first carrier associated with the first RLC entity when an amount of data retransmission determined based on a first radio link control (RLC) entity reaches a maximum amount of retransmission, and the first terminal device sends the data to the second terminal device through the first RLC entity; The method of claim 11.

13. The step of determining that the SL RLF occurs on the first carrier associated with the first RLC entity comprises: determining that the SL RLF occurs on the first carrier associated with the first RLC entity if the amount of data retransmissions determined based on the first radio link control (RLC) entity reaches the maximum amount of retransmissions and the first RLC entity is an RLC entity corresponding to a Packet Data Convergence Protocol (PDCP) entity that uses packet duplication.

13. The method of claim 12, comprising:

14. The first carrier includes a plurality of carriers, and after the step of determining that a SL RLF occurs on the first carrier, the method further comprises: sending first information to the second terminal device on each of the first carriers, the first information being used to trigger the second terminal device to feed back second information; determining that the SL RLF occurs on the second carrier if the second information sent by the second terminal device is not received on the second carrier, the second carrier being any carrier among the first carriers; 14. The method of any one of claims 11 to 13, further comprising:

15. The method comprises: Removing or releasing the first carrier.

15. The method of any one of claims 11 to 14, further comprising:

16. The method comprises: and sending a second indication to an access network device, the second indication indicating that the SL RLF occurs on the first carrier.

16. The method according to any one of claims 11 to 15.

17. A communication device comprising a unit or module configured to implement a method according to any one of claims 1 to 10 or comprising a unit or module configured to implement a method according to any one of claims 11 to 16.

18. A communication device comprising a processor and a communication interface, the communication interface configured to receive signals from a communication device other than the communication device and to transmit the signals to the processor or to send signals from the processor to a communication device other than the communication device, the processor configured to enable the communication device to implement a method according to any one of claims 1 to 10 or claims 11 to 16 by using logic circuits or by executing code instructions.

19. A non-transitory computer readable storage medium, the non-transitory storage medium storing a computer program or instructions, the computer program or the instructions, when executed by a computer, implementing a method according to any one of claims 1 to 10 or claims 11 to 16.

20. A computer program product comprising computer program code, which when executed on a computer implements the method of any one of claims 1 to 10 or claims 11 to 16.

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