Multicast feedback configuration method and apparatus

Abstract

To provide a multicast feedback configuration method and device that guarantee reliable data transmission and improve resource utilization.SOLUTION: In a method applied to a multicast transmission process, a first terminal transmits to a second terminal first information including information indicating a feedback method for first data, which is a data packet to be transmitted to the second terminal. The feedback method is a first or second feedback method. In the first feedback method, the second terminal feeds back to the first terminal only confirmation information indicating that it has failed to receive the data packet. In the second feedback method, the second terminal feeds back to the first terminal confirmation information indicating that it has succeeded in receiving the data packet or that it has failed to receive the data packet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] [Cross-reference to Related Applications] This application claims priority based on Chinese Patent Application No. 201910364623.X, titled "Multicast Feedback Configuration Method and Apparatus", filed with the China National Intellectual Property Administration on May 1, 2019, the content of which is hereby incorporated by reference in its entirety into this specification.

[0002] [Technical Field] This application relates to the field of communication technologies, specifically to V2X, intelligent driving, and intelligent and connected vehicles, etc., and particularly to a multicast feedback configuration method and apparatus.

Background Art

[0003] In wireless communication systems, hybrid automatic repeat request (HARQ) technology is typically used between the receiving and transmitting terminals to improve the reliability of data transmission. After the first terminal sends a data packet to the second terminal, the first terminal receives HARQ feedback status from the second terminal to know the data packet reception status of the second terminal. This HARQ feedback status includes positive acknowledgement (ACK) status, negative acknowledgement (NACK) status, and discontinuous transmission (DTX) status where neither ACK nor NACK is fed back. Specifically, if the second terminal successfully receives the data packet from the first terminal, the second terminal feeds back an ACK to the first terminal. If the second terminal fails to receive the data packet, the second terminal feeds back a NACK to the first terminal, and the first terminal retransmits the data packet after receiving the NACK. If the second terminal loses a data packet transmitted by the first terminal, the second terminal is in a DTX state, meaning it does not provide ACK feedback or NACK feedback. In this case, the first terminal retransmits the data packet.

[0004] Currently, there are two feedback methods for new radio vehicle to everything (NR V2X) multicast from a vehicle to anything. Furthermore, once a feedback method is determined, it remains unchanged. The NR V2X multicast feedback methods include either the second terminal feeding back only a NACK, or the second terminal feeding back an ACK / NACK.

[0005] In a feedback scheme where the second terminal only feeds back a NACK, each second terminal in multicast feeds back only a NACK, and all second terminals share one common feedback resource. A second terminal that fails to receive a data packet feeds back a NACK using that common feedback resource. The advantage of this feedback scheme is that all second terminals share one feedback resource, thereby avoiding resource waste. The disadvantage is that it is impossible for the first terminal to distinguish between a DTX feedback state and an ACK feedback state. Specifically, there are two possible cases in which a second terminal has successfully received a data packet when it does not feed back a NACK. The second terminal loses control information transmitted via the physical sidelink control channel (PSCCH) and is unable to receive the data packet. When the first terminal does not receive a NACK feedback, it assumes the feedback state is ACK and no longer retransmits the data packet. Thus, it becomes impossible to guarantee the reliability of data transmission between the first terminal and the second terminal.

[0006] In a feedback scheme where a second terminal provides ACK / NACK feedback, each second terminal has its own dedicated resources for providing ACK / NACK feedback; that is, the resources for ACK / NACK feedback by the second terminals can only be used by those second terminals and cannot be used by other second terminals. The advantage of this feedback scheme is that the first terminal can recognize the DTX state. The disadvantage is that when there are many multicast second terminals, it is necessary to configure resources for providing ACK / NACK feedback for each second terminal, which leads to resource waste.

[0007] Therefore, these two feedback schemes are applicable to multiple different scenarios. On the other hand, in the case of an NR V2X multicast process, the number of second terminals and the channel state change continuously. When the feedback scheme used by the second terminal remains unchanged, it reduces system operational efficiency and resource utilization. [Overview of the project]

[0008] Multiple embodiments of this application provide multicast feedback configuration methods and apparatus to ensure reliable data transmission and improve resource utilization.

[0009] To achieve the above objectives, the following technical solutions are used in some of the embodiments of this application.

[0010] According to a first aspect, the application provides a multicast feedback configuration method, which may be performed by a first terminal. The first terminal device may be a terminal device or a component (e.g., a chip system) within a terminal device. The method includes the step of transmitting first information from the first terminal to a second terminal, wherein the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted by the first terminal to the second terminal, the feedback scheme is a first feedback scheme or a second feedback scheme, the first feedback scheme is a feedback scheme in which the second terminal feeds back only acknowledgment to the first terminal that it has failed to receive the data packet, and the second feedback scheme is a feedback scheme in which the second terminal feeds back acknowledgment to the first terminal that it has succeeded in receiving the data packet or that it has failed to receive the data packet.

[0011] According to the multicast feedback configuration method provided in this application, a first terminal transmits first information to a second terminal, the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted by the first terminal to the second terminal, the feedback scheme is either a first feedback scheme or a second feedback scheme, the first feedback scheme is one in which the second terminal only provides confirmation information to the first terminal indicating that it has failed to receive the data packet, and the second feedback scheme is one in which the second terminal provides confirmation information to the first terminal indicating that it has successfully received the data packet or has failed to receive the data packet. With current technology, the feedback scheme used by the second terminal is kept in an unchanging state and cannot be applied to channel states that change in real time, resulting in low system operational efficiency and low resource utilization. In addition, the size of resources required for multiple different feedback schemes also differs when the number of second terminals is different. If the feedback scheme used by the second terminal is kept unchanged, it will also result in low resource utilization. According to the multicast feedback configuration method provided by this embodiment of the application, the first terminal may indicate the first data feedback scheme by transmitting first information to the second terminal. The first terminal can dynamically indicate the feedback scheme to be used by the second terminal, and it is possible to understand that the feedback scheme used by the second terminal is no longer kept unchanged, and that the feedback scheme is adapted to the dynamically changing state of the channel. For example, when a relatively large amount of resources are occupied, the first terminal can instruct the second terminal to use the first feedback scheme to avoid wasting resources. When a relatively small amount of resources are occupied, the first terminal can instruct the second terminal to use the second feedback scheme to ensure the reliability of data transmission.Similarly, the first terminal may further consider the resource overhead required when the number of second terminals varies in order to dynamically adjust the feedback scheme. For example, when there are a relatively large number of second terminals, the first terminal may instruct the second terminals to use the first feedback scheme to avoid wasting resources. When there are a relatively small number of second terminals, the first terminal may instruct the second terminals to use the second feedback scheme to ensure the reliability of data transmission.

[0012] In one possible design, the multicast feedback configuration method provided by this application further includes the step of obtaining second information by the first terminal, the second information including resource congestion control information and / or the number of second terminals, and the second information being used to determine the feedback scheme. In this way, the first terminal can determine the feedback scheme based on the second information to ensure reliable data transmission and improve resource utilization.

[0013] In one possible design, the second information includes the resource congestion control information, which includes the channel busy ratio CBR, and the feedback method is the first feedback method when the CBR is greater than a preset critical CBR value, or the feedback method is the second feedback method when the CBR is less than or equal to a preset critical CBR value.

[0014] In one possible design, the CBR is a first CBR which indicates the channel busy ratio of the physical sidelink feedback channel PSFCH, the physical sidelink sharing channel PSSCH, and the physical sidelink control channel PSCCH in a preset measurement cycle, or the CBR is a second CBR which indicates the channel busy ratio of PSFCH in a preset measurement cycle, or the CBR is determined based on the second and third CBRs, where the second CBR indicates the channel busy ratio of PSFCH in a preset measurement cycle and the third CBR indicates the channel busy ratio of PSSCH and PSCCH in the preset measurement cycle.

[0015] In one possible design, the second information includes the resource congestion control information, the resource congestion control information includes the channel occupancy ratio CR, and the feedback method is the first feedback method when the CR is greater than a preset critical value for CR.

[0016] In one possible design, the second information includes the number of second terminals, and the feedback method is the first feedback method if the number of second terminals is greater than a preset critical number value.

[0017] In one possible design, the second information includes the resource congestion control information and the number of second terminals, the resource congestion control information includes the channel busy ratio CBR, and the feedback method is the first feedback method when the number of second terminals is in a first number interval and the CBR is greater than a first CBR critical value, or the feedback method is the second feedback method when the number of second terminals is in a first number interval and the CBR is less than or equal to a first CBR critical value, and there exists at least one number interval of second terminals, a plurality of different number intervals corresponding to a plurality of different CBR critical values, and the CBR critical value corresponding to the first number interval is the first CBR critical value.

[0018] In one possible design, a multicast feedback configuration method provided by this application further includes the steps of: determining by the first terminal how many times the data packet is retransmitted, the number of times the data packet is retransmitted by the first terminal using the first feedback scheme; and determining by the first terminal, based on the number of times the data packet is retransmitted, that the feedback scheme is the second feedback scheme.

[0019] In one possible design, the first information is sidelink control information SCI, the SCI includes a preset field, the preset field is used to indicate the feedback scheme used by the second terminal, and a plurality of different values ​​of the preset field indicate a plurality of different feedback schemes used by the second terminal, or the preset field includes a first preset field and a second preset field, the first preset field is used to indicate the resources used by the PSFCH to transmit the acknowledgment information by the first feedback scheme, and the second preset field is used to indicate the resources used by the PSFCH to transmit the acknowledgment information by the second feedback scheme.

[0020] In one possible design, the first information is SCI, the format of the SCI includes a first format and a second format, the SCI in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme, and the SCI in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

[0021] In one possible design, the first information is an SCI, the SCI includes format information for a PSFCH, the format information for the PSFCH includes a first format and a second format, the PSFCH in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme, and the PSFCH in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

[0022] In one possible design, according to the multicast feedback configuration method provided by this application, prior to the step of transmitting first information by a first terminal to a second terminal, the method further includes the step of the first terminal receiving third information from an access network device, wherein the third information includes the information indicating the feedback scheme of the first data.

[0023] In one possible design, the third information is system information, wherein the master information block MIB of the system information includes the information indicating the feedback scheme used by the second terminal, or the system information block SIB of the system information includes the information indicating the feedback scheme used by the second terminal, or the third information is radio resource control RRC signaling, wherein the RRC signaling includes the information indicating the feedback scheme used by the second terminal, or the third information is media access control MAC signaling, wherein the MAC signaling includes the information indicating the feedback scheme used by the second terminal, or the third information is downlink control information DCI, wherein the DCI includes the information indicating the feedback scheme used by the second terminal.

[0024] According to a second aspect, this application provides a multicast feedback configuration device. The device may be the first terminal of the first aspect. The device includes a processor, a receiver, and a transmitter. Specifically, the transmitter is configured to transmit first information to a second terminal, the first information including information indicating a feedback method for first data, the first data being data packets transmitted by the first terminal to the second terminal, the feedback method being a first feedback method or a second feedback method, the first feedback method being a feedback method in which the second terminal feeds back only confirmation information indicating that the reception of the data packet has failed to the first terminal, and the second feedback method being a feedback method in which the second terminal feeds back confirmation information indicating that the reception of the data packet has been successful or that the reception of the data packet has failed to the first terminal.

[0025] In one possible design, the receiver is configured to obtain second information, the second information including resource congestion control information and / or the number of second terminals, and the second information is used to determine the feedback method.

[0026] In one possible design, the second information includes the resource congestion control information, the resource congestion control information including a channel busy ratio CBR, and when the CBR is greater than a preset CBR threshold, the feedback method is the first feedback method, or when the CBR is less than or equal to the preset CBR threshold, the feedback method is the second feedback method.

[0027] In one possible design, the CBR is the first CBR, and the first CBR indicates the channel busy ratio of the physical sidelink feedback channel PSFCH, the physical sidelink shared channel PSSCH, and the physical sidelink control channel PSCCH in a preset measurement period. Or, the CBR is the second CBR, and the second CBR indicates the channel busy ratio of the PSFCH in a preset measurement period. Or, the CBR is determined based on the second CBR and the third CBR. The second CBR indicates the channel busy ratio of the PSFCH in a preset measurement period, and the third CBR indicates the channel busy ratio of the PSSCH and the PSCCH in the preset measurement period.

[0028] In one possible design, the second information includes the resource congestion control information. The resource congestion control information includes the channel occupancy ratio CR. When the CR is greater than a preset CR threshold, the feedback method is the first feedback method.

[0029] In one possible design, the second information includes the number of the second terminals. When the number of the second terminals is greater than a preset number threshold, the feedback method is the first feedback method.

[0030] In one possible design, the second information includes the resource congestion control information and the number of second terminals, the resource congestion control information includes the channel busy ratio CBR, and the feedback method is the first feedback method when the number of second terminals is in a first number interval and the CBR is greater than a first CBR critical value, or the feedback method is the second feedback method when the number of second terminals is in a first number interval and the CBR is less than or equal to a first CBR critical value, and there exists at least one number interval of second terminals, a plurality of different number intervals corresponding to a plurality of different CBR critical values, and the CBR critical value corresponding to the first number interval is the first CBR critical value.

[0031] In one possible design, the processor is configured to determine the number of times the data packet is retransmitted, the number of times the first terminal retransmits the data packet using the first feedback scheme, and the processor is further configured to determine, based on the number of times the data packet is retransmitted, that the feedback scheme is the second feedback scheme.

[0032] In one possible design, the first information is sidelink control information SCI, the SCI includes a preset field, the preset field is used to indicate the feedback scheme used by the second terminal, and a plurality of different values ​​of the preset field indicate a plurality of different feedback schemes used by the second terminal, or the preset field includes a first preset field and a second preset field, the first preset field is used to indicate the resources used by the PSFCH to transmit the acknowledgment information by the first feedback scheme, and the second preset field is used to indicate the resources used by the PSFCH to transmit the acknowledgment information by the second feedback scheme.

[0033] In one possible design, the first information is SCI, The SCI format includes a first format and a second format, The SCI in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme. The SCI in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

[0034] In one possible design, the first information is an SCI, the SCI includes format information for a PSFCH, the format information for the PSFCH includes a first format and a second format, the PSFCH in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme, and the PSFCH in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

[0035] In one possible design, the receiver is configured to receive third information from an access network device before transmitting the first information to the second terminal, the third information including the information indicating the feedback scheme for the first data.

[0036] In one possible design, the third information is system information, wherein the master information block MIB of the system information includes the information indicating the feedback scheme used by the second terminal, or the system information block SIB of the system information includes the information indicating the feedback scheme used by the second terminal, or the third information is radio resource control RRC signaling, wherein the RRC signaling includes the information indicating the feedback scheme used by the second terminal, or the third information is media access control MAC signaling, wherein the MAC signaling includes the information indicating the feedback scheme used by the second terminal, or the third information is downlink control information DCI, wherein the DCI includes the information indicating the feedback scheme used by the second terminal.

[0037] According to a third aspect, the application provides a multicast feedback configuration device configured to implement the functions of the first terminal in the first aspect.

[0038] According to a fourth aspect, one embodiment of the present application provides a multicast feedback configuration device having the function of implementing a multicast feedback configuration method according to the first aspect or any one of several possible designs thereof. The function may be implemented by hardware or by hardware running corresponding software. The hardware or software includes one or more modules corresponding to the function.

[0039] According to a fifth aspect, a multicast feedback configuration device is provided, which includes a processor and memory. The memory is configured to store computer-executable instructions. When the multicast feedback configuration device is operating, the processor executes computer-executable instructions stored in the memory, thereby the multicast feedback configuration device performs a multicast feedback configuration method according to the first aspect or any one of several possible designs of the first aspect.

[0040] According to a sixth aspect, a multicast feedback configuration device is provided, which includes a processor, which is coupled to memory and configured to read instructions from memory and to perform a multicast feedback configuration method according to the first aspect or any one of a plurality of possible designs of the first aspect.

[0041] According to the seventh aspect, a computer-readable storage medium is provided, which stores instructions. When those instructions are executed by a computer, the computer is enabled to perform a multicast feedback configuration method according to the first aspect or any one of several possible designs thereof.

[0042] According to the eighth aspect, a computer program product including instructions is provided. When the computer program product is executed by a computer, the computer is enabled to perform a multicast feedback configuration method according to the first aspect or any one of several possible designs of the first aspect.

[0043] According to the ninth aspect, a circuit system is provided, which includes a processing circuit, which is configured to perform a multicast feedback configuration method according to the first aspect or any one of a plurality of possible designs of the first aspect.

[0044] According to a tenth aspect, the application provides a chip, the chip including a processor, the processor being coupled to memory, the memory storing program instructions, and when the program instructions stored in memory are executed by the processor, a multicast feedback configuration method according to a first aspect or any one of several possible designs thereof is implemented.

[0045] According to the eleventh embodiment, a communication system is provided. The communication system includes a first terminal device in any one of the above-described embodiments and a second terminal device in any one of the above-described embodiments.

[0046] For the technical effects of the possible designs from the second to the eleventh embodiment, refer to the technical effects of the various different design methods in the first embodiment. Details are not repeated in this specification. [Brief explanation of the drawing]

[0047] [Figure 1] This is a schematic diagram of a communication system according to one embodiment of this application. [Figure 2] This is another schematic diagram of a communication system according to one embodiment of this application. [Figure 3] This is a first flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 4] This is a second flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 5] This is a third flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 6] This is a fourth flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 7] This is a fifth flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 8] This is a sixth flowchart of a multicast feedback configuration method according to one embodiment of this application. [Figure 9] This is a schematic diagram of a signaling configuration for side link control information according to one embodiment of this application. [Figure 10] This is a schematic diagram of a signaling configuration for side link control information according to one embodiment of this application. [Figure 11] This is a schematic diagram of a signaling configuration for side link control information according to one embodiment of this application. [Figure 12] This is a schematic diagram of a signaling configuration for side link control information according to one embodiment of this application. [Figure 13] This is a schematic diagram of a multicast feedback configuration device according to one embodiment of this application. [Figure 14] This is a schematic diagram of a multicast feedback configuration device according to one embodiment of this application. [Modes for carrying out the invention]

[0048] In the specification and accompanying drawings of this application, terms such as “first” and “second” are intended to distinguish multiple different objects or multiple different processes of the same object, but not to indicate a particular order of those multiple objects. In addition, “includes,” “has,” or other variations of those terms in the description of this application are also intended to include non-exclusive inclusion. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the steps or units described therein, but optionally further includes other undescribed steps or units, or optionally further includes other inherent steps or units of the process, method, product, or device. In some embodiments of this application, it should be noted that terms such as “example” or “for example” are used to present a particular example, explanation, or description. No embodiment or design scheme described as “example” or “for example” among some of the embodiments of this application should be described as being preferable or having more advantages than the other embodiments or design schemes. More precisely, the use of words such as "example" or "for example" is intended to present a relative concept in a particular manner.

[0049] First, we will explain the technical terms used in those embodiments of this application.

[0050] The channel busy ratio (CBR) is the ratio of the number of subchannels whose sidelink-received signal strength indicator (S-RSSI) exceeds a preset critical value to the total number of subchannels, over a preset measurement period (e.g., 100 ms). CBR is an indicator for measuring interference. A higher CBR indicates higher channel busyness, greater system load, and stronger interference between multiple different terminals. If the S-RSSI of a subchannel is greater than the preset critical value, it indicates that the subchannel is occupied; if the S-RSSI of a subchannel is less than or equal to the preset critical value, it indicates that the subchannel is not occupied. CBRs obtained using multiple different CBR measurement methods may represent multiple different types of channel busyness. For example, if the first terminal performs CBR measurements on three channels, PSFCH, PSSCH, and PSCCH, within a preset measurement cycle of 100 ms, the resulting CBR will indicate the overall channel busyness of PSFCH, PSSCH, and PSCCH within that preset measurement cycle. If the first terminal performs a CBR measurement on the PSFCH channel, the resulting CBR will indicate the busyness of that PSFCH channel within that preset measurement cycle. Or, if the first terminal performs CBR measurements on two channels, PSSCH and PSCCH, the resulting CBR will indicate the overall channel busyness of PSSCH and PSCCH within that preset measurement cycle. For detailed procedures on how the first terminal can perform CBR measurements on multiple different channels and obtain multiple CBRs, refer to the current art. Details are not described herein.

[0051] The channel occupancy ratio (CR) represents the ratio of the number of subchannels actually occupied by a terminal to the total number of subchannels in a pre-set measurement period (e.g., 1000 ms). CR is an indicator used to measure terminal characteristics. A higher CR indicates that the terminal is occupying more resources.

[0052] The first feedback scheme is one in which the second terminal only feeds back acknowledgment to the first terminal that it has failed to receive the packet, i.e., it only feeds back negative acknowledgment (NACK only). In a multicast scenario, when using the first feedback scheme, the first terminal sends data packets to the second terminals, and all second terminals share the same feedback resources.

[0053] The second feedback scheme involves the second terminal providing feedback to the first terminal indicating whether it has successfully received the data packet or failed to receive it, i.e., providing positive / negative acknowledgment (ACK / NACK). In a multicast scenario, when using the second feedback scheme, the first terminal sends data packets to the second terminals, and each second terminal has its own dedicated feedback resource.

[0054] The feedback resource is a hybrid automatic repeat request. HARQ technology is a time-frequency resource occupied to transmit HARQ information.

[0055] Multiple embodiments of this application may be applied to systems for communication between multiple terminals, such as a V2X communication system or a device-to-device (D2D) system. Referring to Figure 1, the communication system includes at least two terminals, which are capable of communicating directly with each other via a sidelink (SL). Optionally, referring to Figure 2, the communication system further includes an access network device. The terminals may further communicate with the access network device (Figures 1 and 2 show only two terminals).

[0056] A terminal is primarily configured to transmit and receive data. Optionally, a terminal in some of the embodiments of this application may be a device or component within a device that implements the functions of the terminal. For example, the terminal may include, but is not limited to, various handheld devices, in-vehicle devices, wearable devices, or computing devices having wireless communication capabilities, or other processing devices connected to a wireless modem. A terminal may further include a subscriber unit, a cellular phone, a smartphone, a wireless data card, a personal digital assistant (PDA) computer, a tablet computer, a handheld device, a laptop computer, a machine-type communication (MTC) terminal, user equipment (UE), and a mobile terminal. In other examples, a terminal may be a component within any one of the above devices (for example, the terminal may be a chip system within any one of the above devices). The terminals in those embodiments of this application may alternatively be on-board modules, on-board modules, on-board components, on-board chips, or on-board units incorporated into a vehicle as one or more components or units. A vehicle may implement the methods of this application by using on-board modules, on-board modules, on-board components, on-board chips, or on-board units incorporated into a vehicle. In some of the embodiments of this application, the terminals may also be referred to as terminals. A general description is provided herein, and details are not described below.

[0057] An access network device is a device located within a radio access network and configured to provide radio communication functionality. Optionally, an access network device may be a device that communicates with radio terminals by using one or more cells via the access network's radio interface. The device for implementing the functionality of the access network device may be the access network device itself, or a device (e.g., a chip within the access network device) that assists the access network device in implementing that functionality. Optionally, the access network device may perform attribute management on the radio interface. A base station device may further coordinate attribute management on the radio interface. Access network devices include macro base stations and micro base stations (which may also be called small cells) in various forms, such as relay devices or chips in relay stations, transmission reception points (TRPs), evolved Node B (eNBs), next-generation network nodes (g Node B (gNBs)), and evolved Node B connected to next-generation core networks (ng evolved Node B (ng-eNBs)). Alternatively, in a distributed base station scenario, the access network devices may consist of a baseband unit (BBU) and a remote radio unit (RRU). In a cloud radio access network (CRAN) scenario, the access network devices may consist of a baseband pool (BBU pool) and RRUs.

[0058] The communication systems shown in Figures 1 and 2 may be used in existing Long Term Evolution (LTE) systems or Long Term Evolution Advanced (LTE-A) systems, or in currently formulated 5G networks or other future networks. Of course, the communication systems may also be used in LTE and 5G hybrid networking systems or other systems. This is not particularly limited in those embodiments of this application. In multiple different networks, the access network devices and terminals in the above communication systems may correspond to multiple different names. Those skilled in the art will understand that these names do not constitute a limitation on those devices.

[0059] Multicast services are introduced to a new radio vehicle to everything (NR V2X) system that provides communication from vehicles to all objects, supporting hybrid automatic repeat request (HARQ) technology. In NR V2X, HARQ information is carried by the physical sidelink feedback channel (PSFCH), data is transmitted by the physical sidelink shared channel (PSSCH), and control information is carried by the physical sidelink control channel (PSCCH).

[0060] The NR V2X system has two resource allocation modes.

[0061] Mode 1: The access network device schedules sidelink resources. Specifically, the base station configures a resource pool for use by the terminal. When transmitting data, the terminal needs to request resources from the access network device to use for transmitting the data. The access network device schedules the resources to be used in the sidelink and assigns a specific resource location in the configured resource pool to the terminal's sidelink.

[0062] Mode 2: The terminal independently selects sidelink resources. Specifically, the terminal independently selects sidelink resources from the resource pool configured on the network device side or from a pre-configured resource pool.

[0063] Referring to Figures 3 and 4, the multicast feedback configuration method provided by the embodiments of this application will be described below by using one example in which the first terminal demonstrates a multicast feedback scheme in an NR V2X system.

[0064] S300: The first terminal retrieves the second piece of information.

[0065] The second piece of information includes resource congestion control information and / or the number of second terminals.

[0066] Resource congestion control information indicates the congestion status of resources. For example, resource congestion control information may include CBR or CR. Both CBR and CR may be measured by the first terminal.

[0067] The number of second terminals may be obtained by the first terminal during the multicast establishment process. During the multicast establishment process, the first terminal may further obtain information about each second terminal, such as the identification information of each second terminal.

[0068] The use of the second information to determine the feedback method may specifically include the following: The first terminal may determine the feedback method for the first data based on resource congestion control information. Alternatively, the first terminal may determine the feedback method for the first data based on the number of second terminals. Alternatively, the first terminal may determine the feedback method for the first data based on resource congestion control information and the number of second terminals.

[0069] The feedback method is either the first feedback method or the second feedback method.

[0070] In this way, the first terminal can determine the feedback method based on the second information. When the resource congestion control information and the number of second terminals change, the feedback method for the first data also changes accordingly. For example, when resources are insufficient or the number of second terminals is relatively large, the feedback method may be the first feedback method, and all second terminals share the same feedback resources to avoid resource waste. When the number of idle resources is relatively large and the number of second terminals is relatively small, the feedback method may be the second feedback method, and all second terminals each have their own dedicated feedback resources to ensure reliable data transmission. With current technology, the feedback method used by second terminals is kept unchanged and cannot be applied to channel conditions that change in real time, resulting in low system efficiency and low resource utilization. Similarly, when different numbers of second terminals use the second feedback method, the required resource overhead will differ. Keeping the feedback method unchanged also leads to low system efficiency and low resource utilization. According to the multicast feedback configuration method provided by this embodiment of this application, a first terminal can configure a multicast feedback scheme for a second terminal based on resource congestion control information and the number of second terminals to ensure reliable data transmission and improve resource utilization.

[0071] There are several specific implementations in which the first terminal can determine the feedback method for the first data based on resource congestion control information. Several examples are used below for illustrative purposes.

[0072] In the first possible implementation, the resource congestion control information includes the CBR, and the feedback method is the first feedback method when the CBR is greater than a preset critical CBR value, or the feedback method is the second feedback method when the CBR is less than or equal to a preset critical CBR value.

[0073] The pre-configured CBR critical value may be a value pre-stored in the first terminal or a value pre-configured by the access network device.

[0074] For example, the preset critical value for CBR is 85%. At a given time, if the CBR measured by the first terminal is greater than 85% (90%), this CBR indicates that the current channel is busy, the system is under heavy load, and the second terminal needs to share the same feedback resources to improve resource utilization. In this case, the feedback method used is the first feedback method. At another time, if the CBR measured by the first terminal is less than 85% (80%), this CBR indicates that the current channel is relatively idle, and each second terminal can have its own dedicated feedback resources to ensure the reliability of data transmission. In this case, the feedback method used is the second feedback method. In this way, the first terminal determines the feedback method based on the channel busy ratio to improve resource utilization, avoid resource waste, and ensure the reliability of data transmission.

[0075] The CBR may represent multiple different types of channel busyness. Therefore, when the CBR represents multiple different types of channel busyness, the corresponding CBR critical values ​​are independently pre-configured. The following description explains that "when the CBR represents multiple different types of channel busyness, the first terminal determines multiple different feedback schemes."

[0076] In the first possible design, the first terminal performs CBR measurements on the PSFCH, PSSCH, and PSCCH to obtain the first CBR. Under these circumstances, if the first CBR is greater than a preset first critical value, the CBR indicates a high channel busyness, and each second terminal's dedicated feedback resource increases channel congestion and reduces HARQ feedback efficiency. As a result, all second terminals share the same feedback resource to mitigate channel congestion, and the feedback scheme becomes the first feedback scheme. If the first CBR is less than or equal to the preset first critical value, the CBR indicates a low channel busyness, and as a result, each second terminal can have its own dedicated feedback resource. As a feedback scheme becomes the second feedback scheme, ensuring the reliability of data transmission and avoiding the occurrence of DTX feedback conditions.

[0077] For example, a predetermined first critical value for CBR is 90%. At a certain point in time, the first CBR measured by the first terminal is 92%, which is greater than 90%. In this case, the first terminal determines that the feedback scheme is the first feedback scheme. At another point in time, the first CBR measured by the first terminal is 80%, which is less than 90%. In this case, the first terminal determines that the feedback scheme is the second feedback scheme.

[0078] In this way, the feedback scheme is determined by the first terminal based on the overall channel busyness of PSFCH, PSSCH, and PSCCH, thereby adapting the feedback scheme to the overall channel busyness of the three channels. When the overall channel busyness of the three channels changes, the feedback scheme also changes, resulting in improved system operation efficiency and resource utilization.

[0079] In the second possible design, the first terminal performs a CBR measurement on the PSFCH to obtain a second CBR. In this case, if the second CBR is greater than a preset second CBR critical value, the CBR indicates that the PSFCH channel is busy and resources are insufficient, making it impossible to configure dedicated feedback resources for each second terminal. To improve resource utilization, all second terminals must share the same feedback resources, and the feedback scheme becomes the first feedback scheme. If the second CBR is less than or equal to a preset second CBR critical value, the CBR indicates that the PSFCH channel is busy, a relatively large number of idle resources are available, and it is possible to configure dedicated feedback resources for each second terminal. To ensure the reliability of data transmission, each second terminal may have its own dedicated feedback resources, and the feedback scheme becomes the second feedback scheme.

[0080] For example, the pre-set second critical value for CBR is 87%. At a certain point in time, the second CBR measured by the first terminal is 92%, which is greater than 87%. In this case, the first terminal determines that the feedback scheme is the first feedback scheme. At another point in time, the second CBR measured by the first terminal is 80%, which is less than 87%. In this case, the first terminal determines that the feedback scheme is the second feedback scheme.

[0081] In this way, the feedback scheme is determined by the first terminal based on the channel busyness of the PSFCH, thereby adapting the feedback scheme to the PSFCH's channel busyness. When the PSFCH's channel busyness changes, the feedback scheme also changes, resulting in improved system operation efficiency and resource utilization.

[0082] In a third possible design, the first terminal performs a CBR measurement on the PSFCH to obtain a second CBR. The first terminal performs a CBR measurement on the PSSCH and PSCCH to obtain a third CBR. In this case, a certain implementation process by which the first terminal determines the feedback scheme further includes the fact that the CBR is determined based on the second and third CBRs, and the corresponding CBR critical value is shown as the third CBR critical value. If the CBR determined based on the second and third CBRs is greater than the preset third CBR critical value, the CBR indicates that the overall channel busyness of those three channels is high and resources are insufficient, and as a result, a dedicated feedback resource is no longer configured for each second terminal. To improve resource utilization, all second terminals must share the same feedback resource, and the feedback scheme becomes the first feedback scheme. If the CBR determined based on the second and third CBRs is less than or equal to a preset third CBR critical value, then the CBR indicates that the overall channel busyness of those three channels is low, and that a relatively large number of idle resources exist, thereby allowing for the configuration of dedicated feedback resources for each second terminal. To ensure the reliability of data transmission, each second terminal may have its own dedicated feedback resources, and the feedback scheme will be the second feedback scheme.

[0083] The CBR is determined based on the second CBR and the third CBR. The CBR, the second CBR, and the third CBR are given by the formula CBR = α × CBR² + (1 - α) × CBR³ (1) It satisfies the condition.

[0084] CBR represents a value determined based on the second and third CBRs, where CBR2 represents the second CBR, CBR3 represents the third CBR, and α represents the weighting coefficient. The weighting coefficient α is a value pre-set within the first terminal.

[0085] For example, a pre-set third critical value for CBR is 85%. At some point in time, the first terminal measures the second and third CBRs. The CBR obtained based on the second and third CBRs is 87%, which is greater than 85%. In this case, the first terminal determines that the feedback scheme is the first feedback scheme. At another point in time, the first terminal measures the second and third CBRs. The CBR obtained based on the second and third CBRs is 80%, which is less than 85%. In this case, the first terminal determines that the feedback scheme is the second feedback scheme.

[0086] In this way, the feedback scheme is determined by the first terminal based on the overall channel busyness of those three channels, thereby adapting the feedback scheme to the overall channel busyness of those three channels. When the overall channel busyness of those three channels changes, the feedback scheme also changes, resulting in improved system operation efficiency and resource utilization.

[0087] It should be noted that there may be multiple scenarios in which an access network device configures a resource pool. For example, a base station may configure the same resource pool for three channels, PSSCH, PSCCH, and PSFCH; that is, one resource pool provides the time-frequency resources for the three channels, PSSCH, PSCCH, and PSFCH. As another example, a base station may configure the same resource pool for PSSCH and PSCCH, and a separate resource pool for PSFCH. When the three channels, PSSCH, PSCCH, and PSFCH, share the same resource pool, the first terminal may determine the feedback scheme by any one of the three possible designs described above. When two channels, PSSCH and PSCCH, share the same resource pool, the first terminal may determine the feedback scheme by using the second or third possible design described above.

[0088] It should be noted that the first terminal may perform CBR measurements for multiple different types of channels individually. Specifically, the first terminal determines the corresponding CBR measurement method based on the multiplexing scheme of the PSCCH and the corresponding PSSCH, and on whether the PSSCH is capable of occupying pre-configured PSFCH resources. For example, the multiplexing scheme of the PSCCH and the corresponding PSSCH is one in which overlapping time-domain resources in non-overlapping frequency-domain resources are used to transmit one part of the PSCCH and the associated PSSCH, and non-overlapping time-domain resources are used to transmit the other part of the associated PSSCH. In this case, the first terminal needs to perform CBR measurements for both the PSCCH and the PSSCH. As another example, in the above multiplexing scheme of the PSCCH and the corresponding PSSCH, the pre-configured PSFCH occupies a relatively small number of time-frequency resources, for example, occupying only one or more subcarriers in a certain subchannel, and occupying only a few time-domain symbols, with the remaining pre-configured PSFCH resources still existing. To avoid wasting resources, PSSCH may occupy the remaining PSFCH resources for transmission. In this case, the first terminal may perform a signal strength measurement on all three channels, PSSCH, PSSCH, and PSFCH, to obtain the overall channel busyness of the three channels, and the first terminal does not need to perform a CBR measurement on the PSFCH channel individually. In other examples, if it is possible to use pre-configured PSFCH resources to transmit only PSFCH, but it is not possible to use pre-configured PSFCH resources to transmit PSCCH or PSSCH, the first terminal needs to perform a CBR measurement on PSFCH within the range of subchannel and time-domain symbol size to obtain the channel busyness of PSFCH.

[0089] In a second possible implementation, the resource congestion control information includes CR, and the feedback scheme is determined based on CR, specifically, if the CR is greater than a preset critical value for CR, then the feedback scheme is the first feedback scheme.

[0090] CR represents the ratio of the number of subchannels actually occupied by the first terminal to the total number of subchannels in a pre-configured measurement period (e.g., 1000 ms).

[0091] The pre-set critical CR value may be a value pre-stored in the first terminal, or it may be a value obtained by the first terminal from an access network device.

[0092] For example, the preset critical value for CR is 90%. If, at some point in time, the CR measured by the first terminal is greater than 90% (97%), that CR indicates that the first terminal is occupying an excessively large number of resources. To avoid the same terminal occupying an excessive number of resources, dedicated feedback resources are no longer configured for each second terminal; all second terminals share the same feedback resources, and the feedback scheme is the same as the first feedback scheme.

[0093] Thus, the feedback mechanism is determined based on CR, which prevents terminals from occupying an excessively large number of resources and ensures fairness in resource allocation among all terminals.

[0094] In the third possible implementation, the resource congestion control information includes CBR and CR. If CR is greater than a preset critical value for CR, the feedback method is the first feedback method; if CR is less than or equal to a preset critical value for CR and CBR is greater than a preset critical value for CBR, the feedback method is the first feedback method; or if CR is less than or equal to a preset critical value for CR and CBR is less than or equal to a preset critical value for CBR, the feedback method is the second feedback method.

[0095] For example, the preset critical value for CR is 90%, and the preset critical value for CBR is 87%. If, at some point in time, the CR measured by the first terminal is 92%, which is greater than 90%, then that CR indicates that the first terminal is occupying an excessively large number of resources. To avoid the same terminal occupying an excessive number of resources, dedicated feedback resources are no longer configured for each second terminal, all second terminals share the same feedback resources, and the feedback scheme is determined to be the same as the first feedback scheme. At another point in time, the CR measured by the first terminal is 70%, and the CBR measured by the first terminal is 90%. That is, the CR measured by the first terminal is less than the preset critical value of CR (90%), and the CBR measured by the first terminal is greater than the preset critical value of CBR (87%). These CR and CBR values ​​indicate that the first terminal is not occupying an excessively large number of resources, but the current channel is busy and the second terminal needs to share the same feedback resources. In this case, the feedback scheme used is the first feedback scheme. At a later point in time, if the CR measured by the first terminal is 70% and the CBR measured by the first terminal is 80%, that is, if the CR measured by the first terminal is less than the preset critical value of CR (90%) and the CBR measured by the first terminal is less than the preset critical value of CBR (87%), then these CR and CBR values ​​indicate that the first terminal is not occupying an excessively large number of resources, the current channel is idle, and each second terminal has its own dedicated feedback resources to ensure the reliability of data transmission. In this case, the feedback method used is the second feedback method. In addition, the CBR can indicate the busyness of multiple different types of channels. For specific implementation processes, refer to the three possible designs described above. Details are not repeated in this specification.

[0096] The following describes a specific implementation process in which the first terminal can, alternatively, determine the first data feedback scheme based on the number of second terminals.

[0097] If the number of second terminals is greater than a predetermined critical number, the feedback scheme is the first feedback scheme.

[0098] The number of the second terminal is obtained by the first terminal in the multicast establishment process. The pre-configured critical number may be a value pre-configured within the first terminal, or a value received by the first terminal from the access network device.

[0099] For example, the number of second terminals is 150, and the preset critical number is 100. In this case, the number of second terminals is greater than the preset critical number, and a dedicated feedback resource is allocated to each second terminal, resulting in high resource overhead and low resource utilization. Therefore, all second terminals must share the same feedback resource, and the feedback scheme is configured as the first feedback scheme, that is, the second terminals only feed back acknowledgment to the first terminals indicating that they have failed to receive the data packet.

[0100] In this way, when the number of second terminals is greater than a predetermined critical number, the first terminal determines that the feedback method is the first feedback method, thereby reducing time-frequency resources and improving the utilization of time-frequency resources.

[0101] The following describes a specific implementation process in which the first terminal can, alternatively, determine the feedback method for the first data based on resource congestion control information and the number of second terminals.

[0102] If the number of second terminals is greater than a predetermined critical number, the feedback method is the first feedback method.

[0103] If the number of second terminals is less than or equal to a predetermined critical number, the feedback method may be the first feedback method or the second feedback method. Details are as follows.

[0104] The feedback method is the first feedback method if the number of second terminals is within the first number interval and the CBR is greater than the first critical CBR value, or the feedback method is the second feedback method if the number of second terminals is within the first number interval and the CBR is less than or equal to the first critical CBR value.

[0105] For example, the preset numerical critical value is 100, and there may be a numerical interval of [0,100] for the second terminal, and the CBR critical value corresponding to the numerical interval [0,100] is N1. When the number of second terminals acquired by the first terminal is 150, the number of second terminals is greater than the preset numerical critical value. In this case, the feedback method is the first feedback method, which reduces time-frequency resources and improves the utilization of time-frequency resources. For example, at the present time, the number of second terminals acquired by the first terminal is 75, and the CBR acquired by the first terminal is N0. The number of second terminals is less than the preset numerical critical value and belongs to the numerical interval [0,100]. That interval is shown as the first numerical interval. When N0 > N1, the feedback method is the first feedback method. When N0 ≤ N1, the feedback method is the second feedback method.

[0106] For example, the predetermined critical number is 100, and there is at least one number interval for the second terminal. When there are two number intervals, [0,50) and [50,100], the critical number of CBR corresponding to the number interval [0,50) is N 2-1 Therefore, the critical value of CBR corresponding to the interval [50,100] is N 2-2 This is the case. At a certain point in time, if the number of second terminals acquired by the first terminal is 150, the number of second terminals is greater than the predetermined critical number value. In this case, the feedback method is the first feedback method, which reduces time-frequency resources and improves the utilization of time-frequency resources. For example, at the present time, the number of second terminals acquired by the first terminal is 75, and the CBR acquired by the first terminal is N0. The number of second terminals is less than the predetermined critical number value and belongs to the number interval [50, 100]. This interval is shown as the first number interval. N0 > N 2-2 In this case, the feedback scheme is the first feedback scheme. N0 ≤ N 2-2 In this case, the feedback method is the second feedback method. For example, at the present time, the number of second terminals acquired by the first terminal is 25, and the CBR acquired by the first terminal is N0. The number of second terminals is smaller than a predetermined critical number value and belongs to the number interval [0, 50). This interval is shown as the first number interval. N0 > N 2-1 In this case, the feedback scheme is the first feedback scheme. N0 ≤ N 2-1 In this case, the feedback mechanism is a second feedback mechanism.

[0107] In this way, the first terminal may determine a feedback scheme based on resource congestion control information and the number of second terminals, thereby ensuring that the feedback scheme used by the second terminals adapts to the dynamically changing channel state. In addition, when the feedback scheme is the second feedback scheme, different numbers of second terminals need to occupy resources of different sizes, and the first terminal can further determine a corresponding feedback scheme based on the number of second terminals to improve resource utilization and avoid resource waste.

[0108] S301: The first terminal transmits the first information to the second terminal, and in response, the second terminal receives the first information from the first terminal.

[0109] The first information includes information indicating the first data feedback scheme. For example, the first information may be sidelink control information (SCI). The SCI may indicate the resource location of the PSSCH and may further indicate the first data feedback scheme. For example, referring to Table 1, the SCI includes at least two fields, such as field 1 and field 2. Field 1 is used to indicate the resource location of the PSSCH, and field 2 is used to indicate the first data feedback scheme. The SCI may further include other fields, such as a field indicating the modulation and demodulation scheme. For example, referring to Figure 9, field 1 includes 8 bits, which are used to indicate the resource location of the PSSCH. Field 2 includes 1 bit, which is used to indicate the first data feedback scheme. [Table 1]

[0110] An SCI may indicate the first data feedback scheme in multiple formats. For example, an SCI may include a pre-set field. If that pre-set field is set to a first pre-set value, the field indicates that the feedback scheme is the first feedback scheme; or if the pre-set field is set to a second pre-set value, the field indicates that the feedback scheme is the second feedback scheme. In another example, the SCI format may include a first format and a second format, with the first format of the SCI used to indicate that the feedback scheme is the first feedback scheme, and the second format of the SCI used to indicate that the feedback scheme is the second feedback scheme.

[0111] The first data is a data packet that the first terminal sends to the second terminal, for example, a data packet that the first terminal sends to the second terminal via multicast.

[0112] The feedback method is either the first feedback method or the second feedback method.

[0113] The first piece of information is sidelink control information (SCI). Several specific implementations exist that demonstrate the feedback mechanism using this SCI. The following description will explain this using several examples.

[0114] In a first possible implementation, the SCI includes a pre-configured field used to carry information indicating a first data feedback scheme. The location of the pre-configured field within the SCI may be determined based on actual application requirements. For example, referring to Figure 10, the SCI is divided into a first part and a second part. The first part may include information about the resource location (i.e., PSSCH) occupied for transmitting data packets and feedback scheme indication information, while the second part may include several configuration parameters, such as configuration parameters required to decode data packets. The pre-configured field may be the last field in the first part of the SCI.

[0115] Multiple different values ​​in a pre-configured field indicate multiple different feedback schemes to be used by the second terminal. For example, the pre-configured field is specifically implemented as a single bit. When that bit is 1, it indicates that the feedback scheme is the first feedback scheme. When that bit is 0, it indicates that the feedback scheme is the second feedback scheme. In this way, the second terminal may obtain the feedback scheme based on the value of the pre-configured field.

[0116] Multiple different values ​​in a pre-configured field indicate that the feedback scheme used by the second terminal is different. In this case, the SCI may also explicitly indicate the resource location of the PSFCH. For example, a field indicating the PSFCH resource may be set. There may be one field indicating the PSFCH resource. When a bit (i.e., a bit in the pre-configured field indicating the feedback scheme used by the second terminal) is 1, the second terminal can know that its feedback scheme is the first feedback scheme, and then, by referring to the PSFCH resource location indicated by the field indicating the PSFCH resource, the second terminal can know the time-frequency resource used to transmit confirmation information in the first feedback scheme. Accordingly, when a bit (i.e., a bit in a pre-configured field indicating the feedback scheme used by the second terminal) is 0, the second terminal can know that the feedback scheme is the second feedback scheme, and then, by referring to the resource location of the PSFCH indicated by the field indicating the PSFCH resource, the second terminal can know the time-frequency resources used to transmit confirmation information by the second feedback scheme. In addition, when the resource locations of the PSFCH and the PSCCH are implicitly related, it is not necessary to set a field indicating the resource location of the PSFCH in the SCI. The second terminal performs blind detection to obtain the resource location occupied by the SCI. Since the resource location of the PSCCH for transmitting the SCI is implicitly related to the resource location of the PSFCH, the second terminal may obtain the resource location of the PSFCH based on the pre-configured mapping rules and the resource location of the PSCCH for transmitting the SCI, thereby not needing to set a field indicating the PSFCH resource in the SCI. In this way, the resources consumed during the transmission of the SCI are reduced.Accordingly, when the resource locations of the PSFCH and PSSCH are implicitly related, it is not necessary to set a field in the SCI indicating the resource location of the PSFCH. The SCI indicates the resources occupied for transmitting data packets; that is, the SCI indicates the resource location of the PSSCH. Therefore, the second terminal can also obtain the resource location of the PSFCH based on the pre-configured mapping rules and the resource location of the PSSCH indicated in the SCI. For specific procedures on which the second terminal performs blind detection to obtain the resource locations occupied by the SCI and then obtains the resource location of the PSFCH based on the pre-configured mapping rules and the resource locations of the PSCCH for transmitting the SCI, refer to the current technology, which is not described in detail herein.

[0117] The pre-configured fields included in the SCI may also explicitly indicate the resource locations of the PSFCH for transmitting confirmation information by multiple different feedback schemes. The pre-configured fields include a first pre-configured field and a second pre-configured field. The first pre-configured field is used to indicate the resources that the PSFCH uses to transmit confirmation information by a first feedback scheme, and the second pre-configured field is used to indicate the resources that the PSFCH uses to transmit confirmation information by a second feedback scheme. For example, Figure 11 shows the locations of the first and second pre-configured fields in the SCI. The locations of both the first and second pre-configured fields in the SCI follow pre-configured rules, which are pre-stored in both the first and second terminals. For example, the first pre-configured field is located before the second pre-configured field. In this case, the first terminal cannot indicate only the feedback scheme used by the second terminal, and may further indicate the time-frequency resources used by the second terminal to transmit feedback information by either the first or second feedback scheme.

[0118] In a second possible implementation, the SCI format includes a first format and a second format, where the first format of the SCI is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme, and the second format of the SCI is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme. For example, in the first format of the SCI, as shown in Figure 9, the first 8 bits of the 9 adjacent bits indicate the resource location of the PSSCH, and the last bit indicates the feedback scheme of the first data. In the second format of the SCI, as shown in Figure 12, the first bit of the 9 adjacent bits indicates the feedback scheme of the first data, and the last 8 bits indicate the resource location of the PSSCH.

[0119] In this way, the first terminal indicates multiple different feedback schemes to be used by the second terminal by using multiple different SCI formats, thereby allowing the second terminal to feed back the reception status of the first data.

[0120] In a third possible implementation, the SCI includes format information for the PSFCH, the PSFCH format information includes a first format and a second format, the PSFCH in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme, and the PSFCH in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

[0121] The format information of PSFCH may specifically be a format index. For example, when the resource location of PSFCH is implicitly related to the resource locations of PSCCH and PSSCH, each format index corresponds to the time-domain resource location and frequency-domain resource location occupied by PSFCH and the format of PSFCH. For example, referring to Table 2, when the format index (index) is 1, it indicates that the time-domain resource location occupied by PSFCH is a1, the frequency-domain resource location is b1, and the format information of PSFCH is the first format. When the format index (index) is 2, it indicates that the time-domain resource location occupied by PSFCH is a2, the frequency-domain resource location is b2, and the format information of PSFCH is the second format. When determining that the feedback scheme is the first feedback scheme, the first terminal may transmit an SCI to the second terminal. In this case, the format information of PSFCH carried in the SCI is the first format. After receiving the SCI, the second terminal may refer to Table 2 to determine the resource location and feedback method of the PSFCH. [Table 2]

[0122] For example, when the resource location of PSFCH and the resource location of PSCCH or PSSCH are implicitly related, each format index corresponds to one format of PSFCH. For example, referring to Table 3, when the format index (index) is 1, that format index indicates that the format information of PSFCH is in the first format. When the format index (index) is 2, that format index indicates that the format information of PSFCH is in the second format. When determining that the feedback scheme is the first feedback scheme, the first terminal may send an SCI to the second terminal. In this case, the format information of PSFCH carried in the SCI is in the first format. After receiving the SCI, the second terminal may refer to Table 3 to determine the feedback scheme. When the resource location of PSFCH and the resource location of PSCCH are implicitly related, the second terminal may determine the resource location of PSFCH based on the resource location of PSCCH. Similarly, when the resource locations of PSFCH and PSSCH are implicitly related, the second terminal may determine the resource location of PSFCH based on the resource location of PSSCH. For details of the process by which the second terminal can determine the resource location of PSFCH based on the resource location of PSCCH, and for details of the process by which the second terminal can determine the resource location of PSFCH based on the resource location of PSSCH, please refer to the current art. Details are not described herein. [Table 3]

[0123] In this way, the first terminal indicates multiple different feedback schemes to be used by the second terminal by carrying different format information of PSFCH, thereby allowing the second terminal to feed back the reception status of the first data.

[0124] It should be noted that, when data packets have a relatively high priority, the first terminal may directly configure a feedback mechanism as a second feedback mechanism to ensure the reliability of data transmission.

[0125] S302: The second terminal provides confirmation information of the first data to the first terminal using the feedback method indicated by the first information.

[0126] In response, the first terminal receives confirmation information for the first data from the second terminal and decides whether or not to retransmit the first data.

[0127] For example, the first feedback method is as follows: Specifically, the second terminal only feeds back acknowledgment to the first terminal indicating that it failed to receive the packet, and all second terminals share the same feedback resources. For example, if the first terminal sends a data packet to the second terminal via multicast and the second terminal successfully receives the data packet, the second terminal does not need to feed back any acknowledgment to the first terminal. Alternatively, if the second terminal fails to receive the data packet, the second terminal feeds back acknowledgment to the first terminal indicating that it failed to receive the data packet, i.e., a NACK. After the first terminal receives the feedback from the second terminal and the acknowledgment indicating that it failed to receive the data packet, the first terminal retransmits the data packet, thereby allowing the second terminal to successfully receive the data packet, improving the use of time-frequency resources and avoiding the waste of time-frequency resources.

[0128] For example, the feedback scheme is a second feedback scheme. Specifically, the second terminal feeds back acknowledgment to the first terminal indicating whether it has successfully received the data packet or failed to receive it, and each second terminal has a dedicated resource for feeding back ACK / NACK. For example, after the first terminal sends a data packet to the second terminal via multicast, if the second terminal successfully receives the data packet, the second terminal feeds back acknowledgment, i.e., an ACK, to the first terminal. Alternatively, if the second terminal fails to receive the data packet, the second terminal feeds back acknowledgment, i.e., a NACK, indicating that it failed to receive the data packet. After the first terminal receives feedback from the second terminal and acknowledgment indicating that it failed to receive the data packet, the first terminal retransmits the data packet, thereby allowing the second terminal to successfully receive the data packet and thus guaranteeing the reliability of data transmission.

[0129] Before step S301, in which the first terminal transmits the first information to the second terminal, it should be noted that the feedback method used by the second terminal by default is the first feedback method. After receiving the first information from the first terminal, the second terminal feeds back confirmation information of the first data to the first terminal using the feedback method indicated by the first information. Specifically, when the feedback method indicated by the first information is the first feedback method, the second terminal still feeds back confirmation information of the first data to the first terminal using the first feedback method, or when the feedback method indicated by the first information is the second feedback method, the second terminal switches the feedback method from the first feedback method to the second feedback method and feeds back confirmation information of the first data to the first terminal using the second feedback method.

[0130] According to the multicast feedback configuration method provided by multiple embodiments of this application, a first terminal transmits first information to a second terminal, the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted by the first terminal to the second terminal, the feedback scheme is either a first feedback scheme or a second feedback scheme, the first feedback scheme is one in which the second terminal only provides confirmation to the first terminal that it has failed to receive the data packet, and the second feedback scheme is one in which the second terminal provides confirmation to the first terminal that it has successfully received the data packet or has failed to receive the data packet. With current technology, the feedback scheme used by the second terminal is kept in an unchanging state and cannot be applied to channel states that change in real time, resulting in low system operational efficiency and low resource utilization. In addition, the size of resources required for multiple different feedback schemes also differs when the number of second terminals is different. If the feedback scheme used by the second terminal is kept unchanged, it will also result in low resource utilization. According to the multicast feedback configuration method provided by this embodiment of the application, the first terminal may indicate the first data feedback scheme by transmitting first information to the second terminal. The first terminal can dynamically indicate the feedback scheme to be used by the second terminal, and it is possible to understand that the feedback scheme used by the second terminal is no longer kept unchanged, and that the feedback scheme is adapted to the dynamically changing state of the channel. For example, when a relatively large amount of resources are occupied, the first terminal can instruct the second terminal to use the first feedback scheme to avoid wasting resources. When a relatively small amount of resources are occupied, the first terminal can instruct the second terminal to use the second feedback scheme to ensure the reliability of data transmission.Similarly, the first terminal may further consider the resource overhead required when the number of second terminals varies in order to dynamically adjust the feedback scheme. For example, when there are a relatively large number of second terminals, the first terminal may instruct the second terminals to use the first feedback scheme to avoid wasting resources. When there are a relatively small number of second terminals, the first terminal may instruct the second terminals to use the second feedback scheme to ensure the reliability of data transmission.

[0131] In addition, referring to Figure 5, when the second terminal uses the first feedback scheme, as long as the first terminal receives the NACK that the second terminal feeds back, the first terminal will retransmit the data packet once, thereby allowing the second terminal to successfully receive the data packet. If the first terminal retransmits the data packet an excessive number of times, the feedback scheme is switched. Specifically, the second terminal is instructed to switch from the first feedback scheme to the second feedback scheme, thereby allowing the first terminal to identify the second terminal that has failed to receive the data packet. The specific implementation process is as follows.

[0132] S303: The first terminal determines the number of times the data packet will be retransmitted.

[0133] The number of data packet retransmissions is the number of times the first terminal retransmits the data packet using the first feedback scheme.

[0134] For example, if the feedback scheme is the first feedback scheme, and one or more second terminals fail to receive a data packet, those second terminals that have failed to receive the data packet feed back to the first terminal an acknowledgment (i.e., a NACK) indicating that they have failed to receive the data packet, the first terminal retransmits the data packet, and records the number of times the data packet has been retransmitted.

[0135] S304: The first terminal determines that the feedback scheme is the second feedback scheme based on the number of times the data packet is retransmitted.

[0136] If the number of data packet retransmissions is greater than the number of retransmissions pre-configured, the first terminal determines that the feedback method is the second feedback method.

[0137] For example, the number of retransmissions is pre-set to be 10, and the first terminal counts that the number of data packet retransmissions is 11. In this case, the number of data packet retransmissions is greater than the pre-set number of retransmissions, and the first terminal determines that the feedback method is the second feedback method.

[0138] Thus, since the second feedback scheme is a feedback scheme in which each second terminal has its own dedicated feedback resource, the first terminal can determine which second terminal is failing to receive data packets based on the feedback information of each second terminal, and easily adjust the transmission method used by the second terminal that is failing to receive data packets. For example, the reliability of data transmission can be guaranteed by sending data packets by unicast to the second terminal that is failing to receive data packets. For detailed procedures on which the first terminal sends data packets by unicast to the second terminal that is failing to receive data packets, please refer to the current technology. Details are not described herein.

[0139] It should be noted that if the number of retransmissions of a data packet exceeds a preset number of retransmissions, the first terminal may, as an alternative, send the data packet to the second terminal by blind retransmission. Certain implementation processes may include the first terminal sending the data packet to the second terminal a specified number of times if the number of retransmissions exceeds a preset number of retransmissions, and the HARQ mechanism being disabled. That is, the second terminal does not need to provide confirmation to the first terminal that it has successfully received or failed to receive the data packet. For detailed procedures on how the first terminal sends the data packet to the second terminal by blind retransmission, refer to the current technology, which is not described herein.

[0140] Alternatively, if the number of retransmissions of a data packet is greater than a preset number of retransmissions, the first terminal may, as an alternative, determine a forwarding terminal and send the data packet to the second terminal that has failed to receive the data packet via that forwarding terminal. A particular implementation process may include the following: The first terminal selects one terminal from all of the second terminals to function as a forwarding terminal based on the geographic location or signal strength information of all of those second terminals, and that forwarding terminal is a terminal whose geographic location or signal strength information falls between the value of the second terminal that has failed to receive the data packet and the first terminal. The first terminal sends the data packet to the forwarding terminal. After receiving the data packet from the first terminal, the forwarding terminal sends the data packet to the second terminal that has failed to receive the data packet to ensure that each second terminal is able to successfully receive the data packet. For detailed procedures regarding how the first terminal determines the forwarding terminal and transmits the data packet to the second terminal that has failed to receive the data packet via that forwarding terminal, refer to current technology. Details are not described herein.

[0141] For example, the first terminal sends a data packet, information indicating that the data packet is to be forwarded, and destination identifier information for the second terminal that failed to receive the data packet to the forwarding terminal. After receiving the data packet from the first terminal, the forwarding terminal sends the data packet to the second terminal that failed to receive it. In this case, the HARQ mechanism is disabled, and the number of times the forwarding terminal retransmits the data packet to the second terminal that failed to receive it through blind retransmission may be a fixed, pre-configured number to guarantee the reliability of data reception by the second terminal.

[0142] Alternatively, the first terminal transmits the data packet, information indicating that the data packet is to be forwarded, and the number of blind retransmissions to the forwarding terminal. After receiving the packet from the first terminal, the forwarding terminal blind retransmits the data packet by multicast or broadcast.

[0143] Similarly, the feedback scheme used by the second terminal is the second feedback scheme. If the second terminal fails to receive a data packet from the first terminal, the second terminal feeds back a NACK to the first terminal, and the first terminal retransmits the data packet. If the number of retransmissions of the data packet is greater than the number of retransmissions pre-configured, the first terminal may, as an alternative, adjust the transmission scheme used by the second terminal that has failed to receive the data packet, for example, by having the second terminal use a unicast or blind retransmission scheme, in order to ensure the reliability of data transmission.

[0144] It should be noted that there are two resource allocation modes in the NR V2X system. A particular implementation process in which the first terminal indicates the feedback scheme used by the second terminal in the NR V2X system is applicable to resource allocation mode 2, i.e., the scenario in which the first terminal autonomously selects sidelink resources.

[0145] Referring to Figure 6 or Figure 7, in an NR V2X system, a first terminal transmits data packets to a second terminal by multicast, and an access network device uses one example that demonstrates a multicast feedback scheme to describe below a multicast feedback configuration method provided by one embodiment of this application.

[0146] S600: The access network device obtains the second piece of information.

[0147] The second piece of information includes resource congestion control information and / or the number of second terminals, and the second piece of information is used to determine the feedback scheme, which is either the first feedback scheme or the second feedback scheme.

[0148] The first terminal may transmit resource congestion control information to an access network device, and the access network device may receive resource congestion control information measured by the first terminal. Specifically, the resource congestion control information may include CBR or CR.

[0149] The number of second terminals changes dynamically and is obtained from the first terminal by the access network device.

[0150] For the specific implementation process of S600, please refer to S300. Details are not repeated in this specification.

[0151] S601: The access network device may transmit third information to the first terminal and the second terminal, and in response, both the first terminal and the second terminal may receive third information from the access network device.

[0152] The third piece of information includes information indicating the first data feedback scheme. For example, the third piece of information may specifically be downlink control information (DCI). Here, DCI is control information that an access network device sends to a first terminal when the first terminal requests resources from the access network device to be used to transmit data packets, and this control information indicates to the first terminal the location of the resources for transmitting the data packets. In addition, the DCI further carries information indicating the first data feedback scheme.

[0153] The first data is a data packet that the first terminal sends to the second terminal, for example, a data packet that the first terminal sends to the second terminal via multicast.

[0154] The feedback method is either the first feedback method or the second feedback method.

[0155] S602: The second terminal provides confirmation information of the first data to the first terminal using the feedback method indicated by the third information.

[0156] In response, the first terminal receives confirmation information for the first data from the second terminal and decides whether or not to retransmit the first data.

[0157] For the specific implementation process of S602, please refer to S302. Details are not repeated in this specification.

[0158] According to the multicast feedback configuration method provided by this embodiment of this application, an access network device transmits third information to a first terminal and a second terminal. The third information includes information indicating a first data feedback scheme, the first data being a data packet transmitted by the first terminal to the second terminal, the feedback scheme being either a first feedback scheme or a second feedback scheme, the first feedback scheme being one in which the second terminal only provides confirmation to the first terminal that it has failed to receive the data packet, and the second feedback scheme being one in which the second terminal provides confirmation to the first terminal that it has successfully received the data packet or has failed to receive the data packet. In current technology, the feedback scheme used by the second terminal is kept in an unchanging state and cannot be applied to channel states that change in real time, resulting in low system operational efficiency and low resource utilization. In addition, the size of resources required for multiple different feedback schemes also differs when the number of second terminals is different. If the feedback scheme used by the second terminal is kept unchanged, it will also result in low resource utilization. According to the multicast feedback configuration method provided by this embodiment of the application, the access network device may indicate the first data feedback scheme by transmitting third information to the first and second terminals. The access network device can dynamically indicate the feedback scheme used by the second terminal, and it is possible to understand that the feedback scheme used by the second terminal is no longer kept unchanged, and that the feedback scheme is adapted to the dynamically changing state of the channel. For example, when a relatively large amount of resources are occupied, the access network device can instruct the second terminal to use the first feedback scheme to avoid wasting resources.When relatively few resources are occupied, the access network device can instruct the second terminal to use a second feedback scheme to ensure the reliability of data transmission. Similarly, the access network device may further consider the resource overhead required when the number of second terminals varies in order to dynamically adjust the feedback scheme. For example, when there are a relatively large number of second terminals, the access network device may instruct the second terminal to use a first feedback scheme to avoid wasting resources. When there are a relatively small number of second terminals, the access network device may instruct the second terminal to use a second feedback scheme to ensure the reliability of data transmission.

[0159] In addition, referring to Figure 7, when the second terminal uses the first feedback scheme, as long as the first terminal receives the NACK that the second terminal feeds back, the first terminal will retransmit the data packet once, thereby allowing the second terminal to successfully receive the data packet. If the first terminal retransmits the data packet an excessive number of times, the feedback scheme is switched. Specifically, the second terminal is instructed to switch from the first feedback scheme to the second feedback scheme, thereby allowing the first terminal to identify the second terminal that has failed to receive the data packet. The specific implementation process is as follows.

[0160] S603: The access network device determines the number of times the first terminal retransmits data packets.

[0161] The number of data packet retransmissions is determined by the access network device based on the number of data packet retransmission resources, and is the number of times the first terminal retransmits the data packet using the first feedback scheme.

[0162] For example, a first feedback scheme is one such scheme. When one or more second terminals fail to receive a data packet, the second terminals that have failed to receive the data packet feed back acknowledgment to the first terminal indicating that they have failed to receive the data packet, the first terminal retransmits the data packet, records the number of retransmissions, or the access network device determines the number of retransmissions of the data packet based on the number of times it constitutes a data packet retransmission resource.

[0163] S604: The access network device determines that the feedback scheme is a second feedback scheme based on the number of times the data packet is retransmitted.

[0164] If the number of data packet retransmissions is greater than the number of pre-configured retransmissions, the access network device determines that the feedback scheme is the second feedback scheme.

[0165] For example, the number of retransmissions is pre-configured to be 10, and the access network device determines that the first terminal will retransmit the data packet 11 times. In this case, the number of data packet retransmissions is greater than the pre-configured number of retransmissions, and the access network device determines that the feedback scheme is the second feedback scheme.

[0166] Thus, since the second feedback scheme is a feedback scheme in which each second terminal has its own dedicated feedback resource, the access network device determines that the feedback scheme used by the second terminal is the second feedback scheme, and thereby the first terminal can determine which second terminal is failing to receive data packets based on the feedback information of each second terminal, and easily adjust the transmission scheme used by the second terminal that is failing to receive data packets. For example, the reliability of data transmission can be guaranteed by sending data packets by unicast to the second terminal that is failing to receive data packets. For detailed procedures on how the first terminal sends data packets by unicast to the second terminal that is failing to receive data packets, refer to the current technology. Details are not described herein.

[0167] In addition, referring to Figure 8, the step S601 in which "the access network device transmits third information to the first terminal and the second terminal" may be replaced by S801 and S802. The specific implementation process is as follows.

[0168] S801: The access network device transmits the fourth piece of information to the first terminal, and in response, the first terminal receives the fourth piece of information from the access network device.

[0169] The fourth piece of information includes information indicating the feedback mechanism for the first piece of data. For example, the fourth piece of information may be DCI, SIB of system information, MIB of system information, RRC signaling, or MAC signaling.

[0170] The first data is a data packet that the first terminal sends to the second terminal, for example, a data packet that the first terminal sends to the second terminal via multicast.

[0171] The feedback method is either the first feedback method or the second feedback method.

[0172] The fourth piece of information may be in multiple formats. The following description explains the specific implementation formats of the fourth piece of information.

[0173] In the first possible implementation, the fourth piece of information may be downlink control information (DCI). The DCI may indicate not only the resource location used during multicast data packet transmission, but also the multicast feedback scheme. In this way, the access network device dynamically indicates the multicast feedback scheme by transmitting the DCI to the first and second terminals.

[0174] In a second possible implementation, the fourth information may be system information. The master information block MIB of the system information includes information indicating the feedback scheme used by the second terminal, or the system information block SIB of the system information includes information indicating the feedback scheme used by the second terminal. In this way, the access network device dynamically indicates the multicast feedback scheme by transmitting the system information to the first terminal.

[0175] In a third possible implementation, the fourth information may be radio resource control (RRC) signaling, which includes information indicating the feedback scheme used by the second terminal. For example, the RRC signaling includes multiple information elements (IEs), and information regarding the feedback scheme used by the second terminal is carried by using these information elements. Alternatively, the activation and deactivation of information regarding the second feedback scheme is carried by using these information elements. If the information elements indicate that the second feedback scheme is activated, the second feedback scheme is used for multicast; otherwise, the first feedback scheme is used. Alternatively, the fourth information may be medium access control (MAC) signaling, which includes information indicating the feedback scheme used by the second terminal. For example, the MAC signaling includes multiple control elements (CEs), and information regarding the feedback scheme used by the second terminal is carried by using these control elements. In this way, the access network device notifies the first terminal of the multicast feedback scheme using MAC signaling or RRC signaling, thereby dynamically indicating the multicast feedback scheme.

[0176] S802: The first terminal transmits the first information to the second terminal, and in response, the second terminal receives the first information from the first terminal.

[0177] The first information includes information indicating the feedback mechanism for the first data. For example, the first information may be SCI. There are several specific implementations that indicate the feedback mechanism by using SCI. For details, see the relevant description in S301. Details are not repeated in this specification.

[0178] Thus, the access network device transmits the fourth information to the first terminal via the downlink, and the first terminal then transmits the first information to the second terminal via the sidelink. Both the first and fourth information include information indicating the first data feedback scheme, thereby allowing the second terminal to obtain the first data feedback scheme.

[0179] It should be noted that there are two resource allocation modes in an NR V2X system. A specific implementation process in which an access network device indicates the feedback scheme used by the second terminal in an NR V2X system is applicable to resource allocation mode 1, i.e., a scenario in which the access network device schedules sidelink resources.

[0180] The solutions provided by the multiple embodiments of this application are described above primarily in terms of interaction between multiple different network elements. To implement the multiple functions described above, it is possible to understand that the first terminal device and the second terminal device include corresponding hardware structures and / or software units for performing those multiple functions. Those multiple embodiments of this application may be implemented in hardware form or in the form of a combination of hardware and computer software, with reference to the steps of units and algorithms described in the multiple embodiments disclosed in this application. Whether a function is performed by hardware driven by computer software or by hardware depends on the specific application and design constraints of those multiple technical solutions. A person skilled in the art may implement the multiple described functions for each specific application using multiple different methods, but such implementation should not be construed as exceeding the scope of the technical solutions of those multiple embodiments of this application.

[0181] In some embodiments of this application, the multicast feedback configuration device may be divided into several functional units based on the examples of the above method. For example, each functional unit may be obtained by division based on a corresponding function, or two or more functions may be integrated into a single processing unit. The integrated unit may be implemented in hardware form or in the form of a software functional unit. It should be noted that in some embodiments of this application, the division of units is just one example and merely a logical division of functions. Other division methods may be used in actual implementations.

[0182] Figure 13 is a schematic block diagram of a multicast feedback configuration according to one embodiment of this application. The multicast feedback configuration 1300 may exist in the form of software, a device, or a component within a device (e.g., a chip system). The multicast feedback configuration 1300 includes a processing unit 1302 and a communication unit 1303.

[0183] The communication unit 1303 may be further divided into a transmitting unit (not shown in Figure 13) and a receiving unit (not shown in Figure 13). The transmitting unit is configured to assist the communication device 1300 in transmitting information to other network elements. The receiving unit is configured to assist the communication device 1300 in receiving information from other network elements.

[0184] When the multicast feedback configurator 1300 is configured to implement the functions of the first terminal described above, for example, the processing unit 1302 may be configured to assist the multicast feedback configurator 1300 in performing S303 and S304 in Figure 5 and / or other processes used for the solution described in this specification. The communication unit 1303 is configured to assist the configurator 1300 in communicating with other network elements (e.g., a second terminal device). For example, the communication unit is configured to assist the configurator 1300 in performing S301 shown in Figure 3 and / or other processes used for the solution described in this specification.

[0185] Selectively, the multicast feedback configuration device 1300 may further include a storage unit 1301 configured to store the program code and data of the device 1300. The data may include, but is not limited to, original data or intermediate data.

[0186] The processing unit 1302 may be a processor or controller, such as a CPU, general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, transistor logic device, hardware component, or any combination thereof. The processing unit 1302 may implement or execute various exemplary logic blocks, modules, and circuits described with reference to the content disclosed in this application. Alternatively, the processor may be a combination of one or more microprocessors or a combination of DSPs and microprocessors that implement computing functions.

[0187] The communication unit 1303 may be a communication interface, a transceiver, or a transceiver circuit, etc. "Communication interface" is a general term. In a particular implementation, the communication interface may include multiple interfaces, such as interfaces between multiple terminals and / or other interfaces.

[0188] The memory unit 1301 may be a memory device.

[0189] When the processing unit 1302 is a processor, the communication unit 1303 is a communication interface, and the storage unit 1301 is memory, the multicast feedback configuration device 1400 in this embodiment of the application may be shown in Figure 14.

[0190] Referring to Figure 14, the device 1400 includes a processor 1402, a transceiver 1403, and a memory 1401.

[0191] The transceiver 1403 may be a separately located transmitter, which may be configured to transmit information to another device. Alternatively, the transceiver may be a separately located receiver, which may be configured to receive information from another device. Alternatively, the transceiver may be a component that integrates the functions of transmitting and receiving information. Specific implementations of the transceiver are not limited to the multiple embodiments of this application.

[0192] Selectively, the device 1400 may further include a bus 1404. The transceiver 1403, processor 1402, and memory 1401 may be connected to each other via the bus 1404. The bus 1404 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus 1404 may be classified into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used to represent the bus in Figure 14, but this does not mean that only one bus exists or only one type of bus exists.

[0193] Those skilled in the art will understand that all or some of the above embodiments may be implemented by using software, hardware, firmware, or a combination thereof. When software is used to implement those embodiments, those embodiments may be implemented whole or in part in the form of a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded into a computer and executed by the computer, they produce, whole or in part, procedures or functions according to those embodiments of this application. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, those computer instructions may be transmitted by a wired method (e.g., coaxial cable, optical fiber, or Digital Subscriber Line, DSL) or by a wireless method (e.g., infrared, radio, or microwave) from one website, computer, server, or data center to another. Computer-readable storage media may be any available media accessible by a computer, or a data storage device such as a server or data center that integrates one or more available media. Available media may be magnetic media (e.g., floppy disks, hard disks, or magnetic tapes), optical media (e.g., digital video discs (DVDs)), or semiconductor media (e.g., solid-state drives (SSDs)).

[0194] It should be understood that in some of the multiple embodiments provided by this application, the disclosed systems, devices, and methods may be implemented in other ways. For example, the embodiments of the devices described are merely examples. For example, the division into units is merely a logical division of function, and other divisions may be used in actual implementations. For example, multiple units or components may be combined or integrated to form other systems, or some features may be ignored or not performed. In addition, the shown or described coupling, direct coupling, or communication connections may be implemented by some interfaces. Indirect coupling or communication connections between multiple devices or multiple units may be implemented electronically or in other forms.

[0195] Units described as individual parts may or may not be physically separated, and parts shown as multiple units may or may not be physical units, may be located in one place, or may be distributed among multiple network devices (e.g., terminals). Some or all of these multiple units may be selected based on actual requirements to achieve the objectives of the solutions of the multiple embodiments.

[0196] In addition, the multiple functional units in those multiple embodiments of this application may be integrated into a single processing unit, and each of the multiple functional units may exist independently, or two or more units may be integrated into a single unit. The integrated unit may be implemented in the form of hardware, or in the form of a hardware and software functional unit.

[0197] Based on the above description of those multiple implementations, a person skilled in the art can clearly understand that this application may be implemented by software and necessary general-purpose hardware, or by hardware alone. In most situations, the former is the preferred implementation. Based on this understanding, the technical solution of this application may be implemented, essentially or in part, by a software product. The computer software product may be stored on a readable storage medium such as a floppy disk, hard disk, or computer optical disk, and may include several instructions for instructing a computer device (which may be a personal computer, server, or network device) to perform the methods described in some embodiments of this application.

Claims

1. A multicast feedback configuration method, A step of obtaining second information by a first terminal, wherein the second information includes resource congestion control information, the first terminal is associated with a plurality of channels of different types, and the resource congestion control information includes an overall channel busyness level for the plurality of channels. The step of transmitting first information from the first terminal to a second terminal, wherein the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted by the first terminal to the second terminal, the feedback scheme is determined to be either a first or second feedback scheme based on the overall channel busyness, the first feedback scheme is a feedback scheme that feeds back acknowledgment information to the first terminal if the second terminal fails to receive the data packet rather than succeeding in receiving the data packet, the second feedback scheme is a feedback scheme that feeds back acknowledgment information to the first terminal indicating that the second terminal has succeeded in receiving the data packet or has failed to receive the data packet, the first information is sidelink control information (SCI), and the feedback scheme is indicated by the format of the SCI, The multicast feedback configuration method includes the step of determining the number of times the data packet is retransmitted by the first terminal, wherein the number of times the data packet is retransmitted is the number of times the first terminal retransmits the data packet using the first feedback scheme. The first terminal further includes the step of determining that the feedback method is the second feedback method if the number of retransmissions of the data packet is greater than a preset number of retransmissions. Multicast feedback configuration method.

2. The overall channel busyness is determined based on the channel busy ratio (CBR) of the multiple channels. If the CBR is greater than a preset critical value for the CBR, the feedback method is either the first feedback method or The multicast feedback configuration method according to claim 1, wherein the feedback method is the second feedback method when the CBR is below a preset critical value of the CBR.

3. The multicast feedback configuration method according to claim 2, wherein the CBR is a first CBR, and the first CBR indicates the channel busy ratio of the physical sidelink feedback channel (PSFCH), the physical sidelink shared channel (PSSCH), and the physical sidelink control channel (PSCCH) in a preset measurement cycle.

4. The second information includes the resource congestion control information, and the resource congestion control information includes the channel occupancy ratio (CR). The multicast feedback configuration method according to claim 1, wherein when the CR is greater than a preset critical value of CR, the feedback method is the first feedback method.

5. The second information includes the resource congestion control information and the number of second terminals, and the resource congestion control information includes the channel busy ratio (CBR). When the number of the second terminals falls within the first number interval and the CBR is greater than the first CBR critical value, the feedback method is either the first feedback method or When the number of the second terminals falls within the first number interval and the CBR is less than or equal to the first CBR critical value, the feedback method is the second feedback method. The multicast feedback configuration method according to claim 1, wherein there exists at least one number interval of the second terminal, and a plurality of different number intervals correspond to a plurality of different CBR critical values, and the CBR critical value corresponding to the first number interval is the first CBR critical value.

6. The SCI includes a pre-configured field, the pre-configured field is used to indicate the feedback scheme used by the second terminal, and multiple different values ​​of the pre-configured field indicate multiple different feedback schemes used by the second terminal, or The aforementioned pre-configured field includes a first pre-configured field and a second pre-configured field. The first pre-configured field is used to indicate the resources used by the PSFCH to transmit the confirmation information by the first feedback method, The multicast feedback configuration method according to any one of claims 1 to 5, wherein the second pre-configured field is used to indicate a resource used by the PSFCH to transmit the confirmation information by the second feedback method.

7. The SCI format includes a first format and a second format, The SCI in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme. The multicast feedback configuration method according to any one of claims 1 to 5, wherein the SCI in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

8. The SCI includes format information of the PSFCH, and the format information of the PSFCH includes a first format and a second format. The PSFCH in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme. The multicast feedback configuration method according to any one of claims 1 to 5, wherein the PSFCH in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

9. Prior to the step of transmitting the first information from the first terminal to the second terminal, the multicast feedback configuration method, A multicast feedback configuration method according to any one of claims 1 to 8, further comprising the step of receiving third information from an access network device by the first terminal, wherein the third information includes information indicating the feedback method for the first data.

10. The third information is system information, and the master information block (MIB) of the system information includes the information indicating the feedback method used by the second terminal, or The system information block (SIB) of the system information includes the information indicating the feedback method used by the second terminal, or The third information is a radio resource control (RRC) signaling, and the RRC signaling includes the information indicating the feedback scheme used by the second terminal, or The third information is media access control (MAC) signaling, and the MAC signaling includes the information indicating the feedback scheme used by the second terminal, or The multicast feedback configuration method according to claim 9, wherein the third information is downlink control information (DCI), and the DCI includes the information indicating the feedback scheme used by the second terminal.

11. A multicast feedback configuration device, A receiver configured to acquire second information, wherein the second information includes resource congestion control information, the receiver is associated with a plurality of channels, each of a different type, and the resource congestion control information includes an overall channel busyness level for the plurality of channels. A transmitter configured to transmit first information to a second terminal, wherein the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted to the second terminal, the feedback scheme is determined to be either a first or second feedback scheme based on the overall channel busyness, the first feedback scheme is a feedback scheme that feeds back acknowledgment information to the second terminal if it fails to receive the data packet rather than if it has successfully received the data packet, the second feedback scheme is a feedback scheme that feeds back acknowledgment information to the second terminal indicating that it has successfully received the data packet or has failed to receive the data packet, the first information is sidelink control information (SCI), and the feedback scheme is indicated by the format of the SCI, The multicast feedback configuration device further includes a processor, the processor configured to determine the number of times the data packet is retransmitted, the number of times the data packet is retransmitted by the first feedback scheme, The processor is further configured to determine that the feedback scheme is the second feedback scheme if the number of retransmissions of the data packet is greater than a preset number of retransmissions. Multicast feedback configuration device.

12. The overall channel busyness is determined based on the channel busy ratio (CBR) of the multiple channels. If the CBR is greater than a preset critical value for the CBR, the feedback method is either the first feedback method or The multicast feedback device according to claim 11, wherein the feedback method is the second feedback method when the CBR is less than or equal to a preset critical value of the CBR.

13. The multicast feedback configuration device according to claim 12, wherein the CBR is a first CBR, and the first CBR indicates the channel busy ratio of the physical sidelink feedback channel (PSFCH), the physical sidelink shared channel (PSSCH), and the physical sidelink control channel (PSCCH) in a preset measurement cycle.

14. The second information includes the resource congestion control information, and the resource congestion control information includes the channel occupancy ratio (CR). The multicast feedback device according to claim 11, wherein when the CR is greater than a preset critical value of CR, the feedback method is the first feedback method.

15. The second information includes the resource congestion control information and the number of second terminals, and the resource congestion control information includes the channel busy ratio (CBR). When the number of the second terminals falls within the first number interval and the CBR is greater than the first CBR critical value, the feedback method is either the first feedback method or When the number of the second terminals falls within the first number interval and the CBR is less than or equal to the first CBR critical value, the feedback method is the second feedback method. Multicast feedback configuration device according to claim 11, wherein there exists at least one number interval of the second terminal, and a plurality of different number intervals correspond to a plurality of different CBR critical values, and the CBR critical value corresponding to the first number interval is the first CBR critical value.

16. The SCI includes a pre-configured field, the pre-configured field is used to indicate the feedback scheme used by the second terminal, and multiple different values ​​of the pre-configured field indicate multiple different feedback schemes used by the second terminal, or The aforementioned pre-configured field includes a first pre-configured field and a second pre-configured field. The first pre-configured field is used to indicate the resources used by the PSFCH to transmit the confirmation information by the first feedback method, The multicast feedback configuration device according to any one of claims 11 to 15, wherein the second pre-configured field is used to indicate a resource used by the PSFCH to transmit the confirmation information by the second feedback method.

17. The SCI format includes a first format and a second format, The SCI in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme. The multicast feedback configuration device according to any one of claims 11 to 15, wherein the SCI in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

18. The SCI includes format information of the PSFCH, and the format information of the PSFCH includes a first format and a second format. The PSFCH in the first format is used to indicate that the feedback scheme used by the second terminal is the first feedback scheme. The multicast feedback configuration device according to any one of claims 11 to 15, wherein the PSFCH in the second format is used to indicate that the feedback scheme used by the second terminal is the second feedback scheme.

19. The multicast feedback configuration device according to any one of claims 11 to 18, further comprising a receiver configured to receive third information from an access network device before transmitting the first information to the second terminal, wherein the third information includes information indicating the feedback scheme of the first data.

20. The third information is system information, and the master information block (MIB) of the system information includes the information indicating the feedback method used by the second terminal, or The system information block (SIB) of the system information includes the information indicating the feedback method used by the second terminal, or The third information is a radio resource control (RRC) signaling, and the RRC signaling includes the information indicating the feedback scheme used by the second terminal, or The third information is media access control (MAC) signaling, and the MAC signaling includes the information indicating the feedback scheme used by the second terminal, or The multicast feedback configuration device according to claim 19, wherein the third information is downlink control information (DCI), and the DCI includes the information indicating the feedback scheme used by the second terminal.

21. A multicast feedback configuration method, A step of receiving first information from a first terminal by a second terminal, wherein the first terminal obtains second information, the second information includes resource congestion control information, the first terminal is associated with a plurality of channels of different types, the resource congestion control information includes an overall channel busyness for the plurality of channels, the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted by the first terminal to the second terminal, the feedback scheme is determined to be either a first feedback scheme or a second feedback scheme based on the overall channel busyness, and the first feedback scheme provides feedback to the first terminal with acknowledgment information if the second terminal fails to receive the data packet rather than succeeding in receiving it. The feedback method is a second feedback method in which the second terminal provides feedback to the first terminal with confirmation information indicating that it has successfully received the data packet or has failed to receive the data packet, the first information being sidelink control information (SCI), the feedback method including steps, as shown in the format of the SCI, the first terminal determining the number of times to retransmit the data packet, the number of times to retransmit the data packet being the number of times the first terminal retransmits the data packet using the first feedback method, and the first terminal determining that the feedback method is the second feedback method if the number of times to retransmit the data packet is greater than a preset number of retransmissions. Multicast feedback configuration method.

22. A multicast feedback configuration device, A receiver configured to receive first information from a first terminal, wherein the first terminal acquires second information, the second information includes resource congestion control information, the first terminal is associated with a plurality of channels of different types, the resource congestion control information includes an overall channel busyness level for the plurality of channels, the first information includes information indicating a first data feedback scheme, the first data is a data packet transmitted to a second terminal, the feedback scheme is determined to be either a first feedback scheme or a second feedback scheme based on the overall channel busyness level, and the first feedback scheme provides feedback to the second terminal if it fails to receive the data packet rather than if it succeeds in receiving the data packet. The first information is sidelink control information (SCI), and the feedback method includes a receiver, as shown in the format of the SCI, wherein the first terminal determines the number of times to retransmit the data packet, the number of times the first terminal retransmits the data packet using the first feedback method, and the first terminal determines that the feedback method is the second feedback method if the number of times to retransmit the data packet is greater than a preset number of retransmissions. Multicast feedback configuration device.

23. A program that causes a computer to perform the method described in any one of claims 1 to 10 or claim 21.

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