Conflict window value determination method and apparatus

Abstract

An embodiment of the present application provides a contention window value determination method and apparatus. According to the present application, even if the cast type of a TB in a COT to which a reference period belongs is different from the cast type of a TB to be transmitted, even if the TB in the COT to which the reference period belongs corresponds to at least two cast types, or even if the TB to be transmitted corresponds to at least two cast types, a terminal device can determine a reference period, where the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted, and determine a target contention window value based on the transmission status of at least one TB in the reference period, thereby determining an appropriate target contention window value. When the terminal device preempts the channel of the TB to be transmitted based on the target contention window value, interference between different devices is avoided and system transmission efficiency is improved.

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202211379032.8, entitled "Method and Apparatus for Determining Competitive Window Values," filed with the State Intellectual Property Office of China on November 4, 2022, and Chinese Patent Application No. 202310154106.6, entitled "Method and Apparatus for Determining Competitive Window Values," filed with the State Intellectual Property Office of China on February 17, 2023, both of which are incorporated herein by reference in their entireties.

[0002] TECHNICAL FIELD Embodiments of the present application relate to the field of communications, and more particularly to a contention window value determination method and apparatus. [Background technology]

[0003] In a sidelink (SL) system, the method by which a terminal device preempts a channel is Type 1 Listen-Before-Talk (Type 1 LBT).

[0004] In the Type 1 transmission process, each transmitting device is located in a distributed system, so each transmitting device performs the Type 1 LBT procedure independently. Therefore, the following case may occur: multiple devices with the same channel access priority class (CAPC) use the same contention window value, and the number of sensing slots (Ninit) randomly acquired by the multiple devices based on the same contention window value is also the same. When the Ninit values ​​randomly acquired by multiple devices are the same, the multiple devices may simultaneously transmit data in the event of Type 1 LBT success, causing data conflicts (specifically, signals are mixed with each other). As a result, the receiving end cannot demodulate the received signal, and data transmission fails. Summary of the Invention

[0005] The embodiment of the present application provides a contention window value determination method to avoid mutual collisions between different devices and improve system transmission efficiency. [Means for solving the problem]

[0006] According to a first aspect, a conflict window value determination method is provided. The method may be performed by a terminal device, or may be performed by a component (e.g., a chip or a circuit) of the terminal device. This is not limited here. For ease of explanation, the following uses an example in which the method is performed by a terminal device for explanation.

[0007] The method may include: a terminal device determining a reference period, wherein the priority of a channel occupancy time (COT) to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted; and a terminal device determining a target contention window value based on the transmission status of at least one TB in the reference period, wherein the target contention window value is for preempting the channel of the TB to be transmitted, wherein the cast type of the TB in the COT to which the reference period belongs is different from the cast type of the TB to be transmitted, and the TB in the COT to which the reference period belongs corresponds to at least two cast types, or the TB to be transmitted corresponds to at least two cast types.

[0008] Based on the aforementioned technical solution, the terminal device may determine an appropriate contention window value based on the transmission status of at least one TB within a reference period to avoid mutual collisions between different devices and improve system transmission efficiency. For example, if at least one TB within the reference period is successfully transmitted, the terminal device may determine a small contention window value to shorten the listen before talk (LBT) period and improve channel access efficiency. If at least one TB within the reference period fails to transmit, the terminal device may determine a large contention window value to extend the LBT period and reduce the possibility of the terminal device colliding with another surrounding device.

[0009] In addition, even if the cast type of a TB in the COT to which the reference period belongs is different from the cast type of the TB to be transmitted, even if the TB in the COT to which the reference period belongs corresponds to at least two cast types, or even if the TB to be transmitted corresponds to at least two cast types, the terminal device can determine the reference period based on the above-mentioned technical solution and determine the contention window value based on the transmission status of at least one TB in the reference period.

[0010] In relation to the first aspect, in some implementations of the first aspect, the cast type of at least one TB within the COT or reference period to which the reference period belongs is the same as the cast type of at least one TB within the TB to be transmitted.

[0011] Based on the above technical solution, if the cast type of at least one TB in the COT or reference period to which the reference period belongs is the same as the cast type of at least one TB in the TB to be transmitted, a target contention window value that is more suitable for preempting the channel of the TB to be transmitted can be determined.

[0012] In relation to the first aspect, in some implementations of the first aspect, the reference period includes at least one transmitted TB, or the COT to which the reference period belongs is the COT closest to the current time.

[0013] The reference period includes one transmitted TB, which includes the following cases: the reference period includes the initial transmission of the TB and all retransmissions, the reference period includes the last retransmission of the TB, the reference period includes the initial transmission of the TB and the feedback information for the initial transmission of the TB is an acknowledgement (ACK), or the reference period includes the retransmission of the TB and the feedback information for the retransmission of the TB is an ACK.

[0014] Based on the above technical solution, if the reference period includes at least one transmitted TB or the COT to which the reference period belongs is the COT closest to the current time, a target contention window value that is more suitable for preempting the channel of the TB to be transmitted can be determined.

[0015] In relation to the first aspect, in some embodiments of the first aspect, the start point of the reference period is any one of the following: the start point of the COT to which the reference period belongs; the start point of transmission of a transmitted TB within the COT to which the reference period belongs; the start point of transmission of a TB corresponding to the lowest transmission priority among the TBs within the COT to which the reference period belongs; the start point of transmission of a first TB within the COT to which the reference period belongs, wherein the cast type of the first TB is the same as the cast type of at least one TB within the TBs to be transmitted; or the start point of transmission of a TB within the TBs corresponding to feedback information received by the terminal device that is first transmitted within the COT to which the reference period belongs.

[0016] In relation to the first aspect, in some embodiments of the first aspect, the end point of the reference period is any one of the following: the end point of the COT to which the reference period belongs; the end point of transmission of a transmitted TB within the COT to which the reference period belongs; the end point of transmission of a TB corresponding to the lowest transmission priority among the TBs within the COT to which the reference period belongs; the end point of transmission of a first TB within the COT to which the reference period belongs, wherein the cast type of the first TB is the same as the cast type of at least one TB within the TB to be transmitted; or the end point of transmission of a TB within the TB corresponding to feedback information received by the terminal device that was last transmitted within the COT to which the reference period belongs.

[0017] In relation to the first aspect, in some embodiments of the first aspect, before the terminal device determines the reference period, the method further includes the terminal device determining that the cast type of a TB in the transmitted COT after the last updated contention window value is different from the cast type of the TB to be transmitted, or that the TB in the transmitted COT corresponds to at least two cast types, the terminal device determining that the TB to be transmitted corresponds to at least two cast types, or the terminal device determining that there is no transmitted TB whose cast type is the same as the cast type of the TB to be transmitted after the last updated contention window value.

[0018] In relation to the first aspect, in some implementations of the first aspect, the terminal device determining the target contention window value based on the transmission status of at least one TB within the reference period may include determining the target contention window value based on the transmission status of a second TB within the reference period, the second TB meeting one or more of the following conditions: both the initial transmission and the retransmission of the second TB are completed, and the feedback information of the last retransmission of the second TB is a negative acknowledgment. the feedback information for the initial transmission or retransmission of the second TB is a Not Accepted ACK (Not Accepted ACK), the feedback information for the initial transmission or retransmission of the second TB is an ACK, the cast type of the second TB is ranked before the cast types of the remaining TBs in the reference period according to a predefined cast type order, the cast type of the second TB is the same as the cast type of at least one TB in the TBs to be transmitted, the second TB is a TB in the TBs corresponding to the feedback information received by the terminal device and is the TB that was last transmitted in the reference period, the transmission priority corresponding to the second TB is the same as the transmission priority corresponding to the TB to be transmitted, the contention window value determined based on the transmission status of the second TB is larger than the contention window value determined based on the transmission status of the remaining TBs in the reference period, the contention window value determined based on the transmission status of the second TB is smaller than the contention window value determined based on the transmission status of the remaining TBs in the reference period, the transmission priority corresponding to the second TB is higher than the transmission priority corresponding to the remaining TBs in the reference period, or the second TB is a TB in the TBs in the reference period for which the terminal device has received feedback information corresponding to the TB.

[0019] The above technical solutions provide multiple flexible methods for determining the target conflict window value, such that these methods can be applied to multiple different scenarios.

[0020] The predefined cast type ordering is as follows, where the front to back ordering of different cast types is multicast 2, multicast 1, unicast, and hybrid automatic repeat request (HARQ) disabled, or the front to back ordering of different cast types is multicast 2, unicast, multicast 1, and HARQ disabled, or the front to back ordering of different cast types is unicast, multicast 2, multicast 1, and HARQ disabled.

[0021] In relation to the first aspect, in some implementations of the first aspect, when the TBs in the reference period include M second TBs, where M is an integer greater than 1, the terminal device determining a target conflict window value based on the transmission statuses of the second TBs in the reference period includes: the terminal device determining N candidate conflict window values ​​based on the transmission statuses of the M second TBs, where N is a positive integer and N≦M; and the terminal device determining a target conflict window value based on the N candidate conflict window values, wherein the target conflict window value is the smallest among the N candidate conflict window values, or the target conflict window value is the largest among the N candidate conflict window values, or the target conflict window value is the candidate conflict window value among the N candidate conflict window values ​​that is greater than an average value of the plurality of candidate conflict window values ​​and has the smallest difference from the average value, or the target conflict window value is the candidate conflict window value among the N candidate conflict window values ​​that has the smallest absolute value of the difference between the candidate conflict window value and the average value of the N candidate conflict window values.

[0022] The plurality of second TBs may correspond to one cast type, or the plurality of second TBs may correspond to at least two cast types, which is not limited in this application.

[0023] Based on the aforementioned technical solution, even if the terminal device determines multiple second TBs, the terminal device may determine a target contention window value based on the transmission statuses of the multiple second TBs.

[0024] In relation to the first aspect, in some implementations of the first aspect, when the TBs in the reference period include M second TBs, where M is a positive integer greater than 1, the terminal device determining a target contention window value based on the transmission status of the second TBs in the reference period includes the terminal device collecting statistics on feedback information of the M second TBs, and the terminal device determining the target contention window value based on the feedback information of the M second TBs.

[0025] The terminal device collects statistics on the feedback information of the M second TBs in the following manner: if the cast type of the TB is unicast, collect statistics on the feedback information of the initial transmission of the TB and the feedback information of each retransmission, collect statistics on the ACK feedback information of the TB, or collect statistics on the feedback information of the last retransmission of the TB; if the cast type of the TB is multicast 1 and the feedback information of the TB is NACK, indicate the number of feedback information of the TB as 1; if the cast type of the TB is multicast 1 and the feedback information of the TB is not NACK, indicate the feedback information of the TB as ACK, and also indicate the number of feedback information of the TB as 1, or indicate the number of feedback information of the TB as L, or indicate the number of feedback information of the TB as L-1, where L is the number of terminal devices included in the terminal device group configured to receive the TB; or if the cast type of the TB is multicast 2, collect statistics on each of the feedback information of the TB.

[0026] Based on the aforementioned technical solution, even if the terminal device determines multiple second TBs, the terminal device may determine a target contention window value based on the transmission statuses of the multiple second TBs.

[0027] In relation to the first aspect, in some implementations of the first aspect, when the TBs in the reference period include M second TBs, where M is a positive integer greater than 1, the terminal device determining a target contention window value based on the transmission status of the second TBs in the reference period includes the terminal device determining the target contention window value based on the transmission status of one of the M second TBs, or the terminal device sequentially updating the contention window value based on the transmission status of the M second TBs in accordance with a transmission sequence of the M second TBs or a sequence of receiving feedback information for the M second TBs until the target contention window value is determined.

[0028] Based on the aforementioned technical solution, even if the terminal device determines multiple second TBs, the terminal device may determine a target contention window value based on the transmission statuses of the multiple second TBs.

[0029] In relation to the first aspect, in some implementations of the first aspect, the terminal device determining a target conflict window value based on a transmission status of at least one TB within a reference period includes the terminal device determining at least one candidate conflict window value based on the transmission status of the at least one TB, and the terminal device determining a target conflict window value based on the at least one candidate conflict window value, wherein the target conflict window value is the minimum value among the at least one candidate conflict window value, the target conflict window value is the maximum value among the at least one candidate conflict window value, the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that is greater than an average value of the at least one candidate conflict window value and has the smallest difference from the average value, or the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that has the smallest absolute value of the difference between the candidate conflict window value and the average value of the at least one candidate conflict window value.

[0030] Based on the aforementioned technical solution, the terminal device may determine a target contention window value based on the transmission status of one or more TBs within a reference period.

[0031] In relation to the first aspect, in some implementations of the first aspect, the terminal device determining a target contention window value based on a transmission status of at least one TB within a reference period includes the terminal device collecting statistics regarding feedback information of the at least one TB, and the terminal device determining the target contention window value based on the feedback information of the at least one TB.

[0032] The terminal device may collect statistics regarding the feedback information of at least one TB in the following manner: if the cast type of the TB is unicast, collect statistics regarding the feedback information of the initial transmission of the TB and the feedback information of each retransmission, collect statistics regarding the ACK feedback information of the TB, or collect statistics regarding the feedback information of the last retransmission of the TB; if the cast type of the TB is multicast 1 and the feedback information of the TB is NACK, indicate the number of feedback information of the TB as 1; if the cast type of the TB is multicast 1 and the feedback information of the TB is not NACK, indicate the feedback information of the TB as ACK, and also indicate the number of feedback information of the TB as 1, or indicate the number of feedback information of the TB as L, or indicate the number of feedback information of the TB as L-1, where L is the number of terminal devices included in the terminal device group configured to receive the TB; or if the cast type of the TB is multicast 2, collect statistics regarding each of the feedback information of the TB.

[0033] Based on the above technical solution, the terminal device can collect statistics on feedback information of one or more TBs within a reference period, so that an appropriate target contention window value can be determined based on the feedback information of one or more TBs.

[0034] In relation to the first aspect, in some implementations of the first aspect, when the reference period includes at least one transmitted TB, and the at least one transmitted TB is the last transmitted TB after the last updated contention window value, the terminal device determining a target contention window value based on the transmission status of the at least one TB in the reference period includes the terminal device determining the target contention window value based on the transmission status of the last transmitted TB.

[0035] Based on the above technical solution, the channel status corresponding to the last transmitted TB is close to the current channel status, so that an appropriate target contention window value can be determined based on the transmission status of the last transmitted TB.

[0036] For example, if the cast type of the last transmitted TB is hybrid automatic repeat request (HARQ) enabled, the terminal device determines the target contention window value based on the feedback information of the last transmitted TB, or if the cast type of the last transmitted TB is HARQ disabled, the terminal device determines the target contention window value based on the number of blind transmissions or the proportion of blind transmissions of the last transmitted TB.

[0037] In relation to the first aspect, in some implementations of the first aspect, when the COT to which the reference period belongs is the COT closest to the current time, the terminal device determining the target contention window value based on the transmission status of at least one TB within the reference period includes the terminal device determining the target contention window value based on the transmission status of the last transmitted TB within the reference period.

[0038] Based on the above technical solution, the channel status corresponding to the last transmitted TB is close to the current channel status, so that an appropriate target contention window value can be determined based on the transmission status of the last transmitted TB.

[0039] For example, the terminal device determining the target contention window value based on the transmission status of the last transmitted TB within the reference period includes: if the terminal device does not receive feedback information of the last transmitted TB, the terminal device determining that the target contention window value is kept unchanged; or if the terminal device receives feedback information of the last transmitted TB, the terminal device determining the target contention window value based on the feedback information of the last transmitted TB.

[0040] According to a second aspect, a conflict window value determination method is provided. The method may be performed by a terminal device, or may be performed by a component (for example, a chip or a circuit) of the terminal device. This is not limited here. For ease of explanation, the following uses an example in which the method is performed by a terminal device for explanation.

[0041] The method may include: a terminal device determining a reference period corresponding to each of at least one cast type, where the at least one cast type is a cast type of at least one TB in the TB to be transmitted, where the priority of a channel occupancy time (COT) to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted, and where the cast type of the TB in the reference period is the same as the cast type corresponding to the reference period; and a terminal device determining a target contention window value based on the transmission status of the TB in the reference period corresponding to each cast type, where the target contention window value is for preempting the channel of the TB to be transmitted, and where the TB transmitted in the COT to which the reference period belongs corresponds to at least two cast types, or where the TB to be transmitted corresponds to at least two cast types.

[0042] Based on the above technical solution, even if the TBs in the COT to which the reference period belongs correspond to at least two cast types, or even if the TBs to be transmitted correspond to at least two cast types, the terminal device can determine a reference period corresponding to each of at least one cast type and determine a contention window value based on the transmission status of the TBs in the reference period, which helps to determine an appropriate contention window value to avoid mutual collisions between different devices and improve system transmission efficiency.

[0043] With respect to the second aspect, in some implementations of the second aspect, the at least one TB is a TB corresponding to the lowest transmission priority among the TBs to be transmitted.

[0044] In relation to the second aspect, in some embodiments of the second aspect, the at least one cast type includes a plurality of cast types, and the terminal device determining a target conflict window value based on a transmission status of a TB within a reference period corresponding to each cast type includes the terminal device determining at least one candidate conflict window value based on a transmission status of a TB within a reference period corresponding to each of the at least one cast type, and the terminal device determining a target conflict window value based on the at least one candidate conflict window value, wherein the target conflict window value is a minimum value among the at least one candidate conflict window value, the target conflict window value is a maximum value among the at least one candidate conflict window value, the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that is greater than an average value of the at least one candidate conflict window value and has a smallest difference from the average value, or the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that has a smallest absolute value of a difference between the candidate conflict window value and the average value of the at least one candidate conflict window value.

[0045] Based on the aforementioned technical solution, even if the terminal device determines multiple reference periods, the terminal device may determine a target contention window value based on the transmission status of the TB within the multiple reference periods.

[0046] According to a third aspect, a conflict window value determination method is provided. The method may be performed by a terminal device, or may be performed by a component (for example, a chip or a circuit) of the terminal device. This is not limited here. For ease of explanation, the following uses an example in which the method is performed by a terminal device for explanation.

[0047] The terminal device determines a target contention window value based on a transmission status of at least one physical sidelink shared channel (PSSCH) within a reference period, the target contention window value is for preempting a channel of the PSSCH to be transmitted, the reference period is within a COT, the reference period includes a first PSSCH, the first PSSCH is a HARQ-enabled PSSCH, and a HARQ corresponding to the first PSSCH is detected by the terminal device, and the terminal device is the terminal device that initializes the COT.

[0048] Based on the above technical solution, the reference period determined by the terminal device includes a first PSSCH, and the terminal device detects a HARQ corresponding to the first PSSCH. Therefore, when the terminal device determines a target contention window value based on the transmission status of at least one PSSCH within the reference period, the terminal device can determine the target contention window value based on the HARQ of at least the first PSSCH, thereby avoiding the following problem: the terminal device does not have enough information to determine how to determine the target contention window value because it did not detect a HARQ corresponding to a PSSCH within the reference period. In addition, the following problem can also be avoided: when the terminal device does not detect a HARQ, the terminal device mistakenly considers a transmission-transmission conflict / transmission-reception conflict of the PSSCH as a PSSCH collision, thereby blindly increasing the contention window value, further reducing the probability of the terminal device accessing the channel.

[0049] In relation to the third aspect, in some implementations of the third aspect, the HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, a HARQ-enabled multicast 1 PSSCH, or a HARQ-enabled multicast 2 PSSCH.

[0050] The HARQ enabled PSSCH may also be referred to as a HARQ-ACK enabled PSSCH.

[0051] In relation to the third aspect, in some implementations of the third aspect, the HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, or a HARQ-enabled multicast 2 PSSCH.

[0052] The HARQ-enabled PSSCH may also be referred to as an ACK / NACK HARQ-ACK enabled PSSCH.

[0053] With respect to the third aspect, in some embodiments of the third aspect, the start of the reference period is the start of the COT.

[0054] In relation to the third aspect, in some implementations of the third aspect, the end point of the reference period is the end point of the time unit in which the first PSSCH is located, and the first PSSCH is the first HARQ-enabled PSSCH whose corresponding HARQ is detected by the terminal device within the COT.

[0055] According to a fourth aspect, a conflict window value determination method is provided. The method may be performed by a terminal device, or may be performed by a component (for example, a chip or a circuit) of the terminal device. This is not limited here. For ease of explanation, the following uses an example in which the method is performed by a terminal device for explanation.

[0056] The terminal device determines a target contention window value based on a transmission status of at least one PSSCH within a reference period, the target contention window value is for preempting a channel of the PSSCH to be transmitted, the reference period is within a COT, and the reference period includes at least one HARQ-enabled PSSCH, and when the terminal device does not detect HARQs corresponding to all the HARQ-enabled PSSCHs within the reference period, the terminal device keeps the contention window value unchanged, or the terminal device determines the target contention window value based on a proportion of the PSSCH to be retransmitted within the PSSCH to be transmitted.

[0057] The terminal device's keeping the contention window value unchanged may include the following two cases: the terminal device keeps the contention window value unchanged based on the contention window value of the COT that is closest to the current PSSCH to be transmitted and that is initialized by the terminal device, or the terminal device keeps the contention window value unchanged based on the contention window value of the COT to which the reference period belongs. In other words, when the terminal device keeps the contention window value unchanged, the terminal device may determine the contention window value of the COT that is closest to the current PSSCH to be transmitted and that is initialized by the terminal device as the target contention window value, or the terminal device may determine the contention window value of the COT to which the reference period belongs as the target contention window value. The terminal device's keeping the contention window value unchanged may be understood as the terminal device not adjusting the contention window value or not performing an action to adjust the contention window value.

[0058] Based on the above technical solution, if the terminal device does not detect HARQs corresponding to all HARQ-enabled PSSCHs within the reference period, the terminal device no longer blindly increases the contention window value, but instead keeps the contention window value unchanged, or determines a target contention window value based on the proportion of retransmitted PSSCHs within the PSSCHs to be transmitted, which can avoid the problem of the terminal device blindly increasing the contention window value and thereby reducing the probability of the terminal device accessing the channel.

[0059] In relation to the fourth aspect, in some implementations of the fourth aspect, the HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, a HARQ-enabled multicast 1 PSSCH, or a HARQ-enabled multicast 2 PSSCH.

[0060] The HARQ-enabled PSSCH may also be referred to as a HARQ-ACK enabled PSSCH.

[0061] In relation to the fourth aspect, in some implementations of the fourth aspect, the HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, or a HARQ-enabled multicast 2 PSSCH.

[0062] The HARQ-enabled PSSCH may also be referred to as an ACK / NACK HARQ-ACK enabled PSSCH.

[0063] According to a fifth aspect, there is provided a communications device configured to perform a method according to any one of the first to fourth aspects. Specifically, the device may include a unit and / or module configured to perform the method according to the first aspect or any one of the possible implementations thereof, a unit and / or module, such as a processing unit and / or a communication unit, configured to perform the method according to the second aspect or any one of the possible implementations thereof, a unit and / or module, such as a processing unit and / or a communication unit, configured to perform the method according to the third aspect or any one of the possible implementations thereof, or a unit and / or module, such as a processing unit and / or a communication unit, configured to perform the method according to the fourth aspect or any one of the possible implementations thereof.

[0064] In one embodiment, the apparatus is a terminal device. When the apparatus is a terminal device, the communication unit may be a transceiver or an input / output interface, and the processing unit may be at least one processor. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0065] In another embodiment, the apparatus is a chip, chip system, or circuit used in a terminal device. When the apparatus is a chip, chip system, or circuit used in a terminal device, the communication unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip, chip system, or circuit, and the processing unit may be at least one processor, processing circuit, logic circuit, or the like.

[0066] According to a sixth aspect, there is provided a communications apparatus. The apparatus includes at least one processor configured to execute a computer program or instructions stored in a memory to perform a method according to the first aspect or any one of possible implementations thereof, a method according to the second aspect or any one of possible implementations thereof, a method according to the third aspect or any one of possible implementations thereof, or a method according to the fourth aspect or any one of possible implementations thereof. Optionally, the apparatus further includes a memory configured to store the computer program or instructions. Optionally, the apparatus further includes a communications interface, and the processor reads the computer program or instructions stored in the memory via the communications interface.

[0067] In one embodiment, the apparatus is a terminal device.

[0068] In another embodiment, the apparatus is a chip, chip system, or circuit for use in a terminal device.

[0069] According to a seventh aspect, the present application provides a processor configured to perform the method provided in the first aspect, configured to perform the method provided in the second aspect, configured to perform the method provided in the third aspect, or configured to perform the method provided in the fourth aspect.

[0070] Unless otherwise specified, or unless the operations such as transmitting and acquiring / receiving related to the processor are inconsistent with the actual functions or internal logic of the processor in the relevant description, the operations may be understood as operations such as output, reception, and input of the processor, or as transmitting and receiving operations performed by the radio frequency circuit and antenna, which is not limited in this application.

[0071] According to an eighth aspect, there is provided a computer-readable storage medium storing program code for execution by a device, the program code being used to perform a method according to the first aspect or any one of possible implementations thereof, a method according to the second aspect or any one of possible implementations thereof, a method according to the third aspect or any one of possible implementations thereof, or a method according to the fourth aspect or any one of possible implementations thereof.

[0072] According to a ninth aspect, there is provided a computer program product comprising instructions which, when running on a computer, enable the computer to perform a method according to the first aspect or any one of possible implementations of the first aspect, enable the computer to perform a method according to the second aspect or any one of possible implementations of the second aspect, enable the computer to perform a method according to the third aspect or any one of possible implementations of the third aspect, or enable the computer to perform a method according to the fourth aspect or any one of possible implementations of the fourth aspect.

[0073] According to a tenth aspect, there is provided a communication system, comprising at least one terminal device as described above, the terminal device being used to perform a method according to the first aspect or any one of possible implementation forms of the first aspect, to perform a method according to the second aspect or any one of possible implementation forms of the second aspect, to perform a method according to the third aspect or any one of possible implementation forms of the third aspect, or to perform a method according to the fourth aspect or any one of possible implementation forms of the fourth aspect. [Brief explanation of the drawings]

[0074] [Figure 1] 1 is a diagram of a communication system in which a method according to an embodiment of the present application is applicable; [Figure 2]1 is a schematic flow chart of a method according to an embodiment of the present application; [Figure 3] This is a diagram showing the relationship between the cast type corresponding to the TB in the COT to which the reference period belongs and the cast type corresponding to the TB to be transmitted. [Figure 4] FIG. 2 is a diagram of a method for determining a reference period according to an embodiment of the present application. [Figure 5] FIG. 1 is a diagram of a method according to an embodiment of the present application. [Figure 6] FIG. 1 is a diagram of a method according to an embodiment of the present application. [Figure 7] FIG. 1 is a diagram of a method according to an embodiment of the present application. [Figure 8] 1 is a schematic flow chart of a method according to an embodiment of the present application; [Figure 9] FIG. 1 is a diagram of a method according to an embodiment of the present application. [Figure 10] FIG. 1 is a diagram of a communication mechanism according to the present application. [Figure 11] 1 is a schematic flow chart of a method according to an embodiment of the present application; [Figure 12] FIG. 2 is a diagram of a method for determining a reference period according to an embodiment of the present application. [Figure 13] 1 is a schematic flow chart of a method according to an embodiment of the present application; [Figure 14] 1 is a diagram of a communication device according to an embodiment of the present application; [Figure 15] FIG. 2 is a block diagram of a communication device according to another embodiment of the present application. [Figure 16] FIG. 1 is a diagram of a chip system according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0075] The following describes the technical solutions in the embodiments of the present application with reference to the accompanying drawings.

[0076] The technical solutions provided in this application may be applied to various communication systems, such as 5th generation (5G) or new radio (NR) systems, long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, and LTE time division duplex (TDD) systems. The technical solutions provided in this application may further be applied to future communication systems such as 6th generation mobile communication systems. The technical solutions provided in this application may further be applied to sidelink (SL) communication, vehicle-to-everything (V2X) communication, machine-to-machine (M2M) communication, machine type communication (MTC), internet of things (IoT) communication systems, or other communication systems. As examples, V2X may include vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P), and vehicle-to-infrastructure (V2I), where the infrastructure is, for example, a road side unit (RSU) or a network device.

[0077] The terminal device in the embodiments of the present application includes various devices having wireless communication capabilities, and the terminal device may be configured to be connected to people, objects, machines, etc. The terminal device may be widely used in various scenarios, such as cellular communication, SL, V2X, peer-to-peer (P2P), M2M, MTC, IoT, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, unmanned aerial vehicles, robots, remote sensing, passive sensing, positioning, navigation and tracking, and autonomous delivery. The terminal device may be a terminal in any one of the aforementioned scenarios, such as an MTC terminal or an IoT terminal.The terminal device may be a user equipment (UE), terminal, fixed device, or mobile station device of the 3rd generation partnership project (3GPP (registered trademark)) standard, i.e., a mobile device, subscriber unit, handheld device, in-vehicle device, wearable device, cellular phone, smart phone, SIP phone, wireless data card, personal digital assistant (PDA), computer, tablet computer, notebook computer, wireless modem, handheld device, laptop computer, computer with wireless transceiver function, smart book, vehicle, satellite, global positioning system (GPS), etc. The device may be a GPS (Global Positioning System, GPS) device, a target tracking device, a flight device (e.g., a drone, a helicopter, a multi-copter, a quad-copter, or an airplane), a watercraft, a remote control device, a smart home device, or an industrial device, or may be a unit built into the device (e.g., a communications module, modem, or chip within the device), or may be a separate processing device connected to a wireless modem.

[0078] It should be understood that in some scenarios, the terminal device may be further configured to function as a base station, for example, the terminal device may function as a scheduling entity and provide sidelink signals between terminal devices in scenarios such as V2X, SL, or P2P.

[0079] In an embodiment of the present application, an apparatus configured to perform the functions of a terminal device, i.e., a terminal device, may be the terminal device or an apparatus capable of supporting the terminal device in performing its functions, such as a chip system or a chip. This apparatus may be mounted on the terminal device. In an embodiment of the present application, the chip system may include a chip, or may include a chip and other discrete components.

[0080] The terminal device may be deployed on land, including indoors or outdoors and handheld or vehicle-mounted devices, on water, or in the air on airplanes, balloons, and satellites. The scenario in which the terminal device is deployed is not limited in the embodiments of the present application.

[0081] The following describes the technical solutions of the embodiments of the present application with reference to the accompanying drawings of the embodiments of the present application. In the description of the present application, unless otherwise specified, " / " indicates that associated objects are in an "or" relationship. For example, A / B may represent A or B. In the present application, "and / or" only describes the associated relationship between associated objects and indicates that three relationships may exist. For example, A and / or B may indicate that only A is present, that both A and B are present, and that only B is present, and A and B may be singular or plural. In addition, in the description of the present application, "plurality" means two or more than two unless otherwise specified. "At least one of the following (elements)" or similar expressions means any combination of these, including any combination of a single element or multiple elements. For example, at least one (element) of a, b, or c may represent a, b, c, ab, ac, bc, or abc, and a, b, and c may be singular or plural. In addition, to clearly describe the technical solutions of the embodiments of the present application, terms such as "first" and "second" are used in the embodiments of the present application to distinguish between the same or similar items that basically provide the same function or purpose. Those skilled in the art can understand that terms such as "first" and "second" do not limit the number or execution order, and terms such as "first" and "second" do not indicate clear differences. In addition, in the embodiments of the present application, terms such as "example" or "for example" are used to represent providing an example, illustration, or explanation. Any embodiment or design solution described as an "example" or "for example" in the embodiments of the present application is not described as being more preferred or having more advantages than another embodiment or design solution. Rather, the use of terms such as "example" or "for example" is intended to present related concepts in a specific way for ease of understanding.

[0082] In addition, the network architectures and service scenarios described in the embodiments of the present application are intended to more clearly explain the technical solutions in the embodiments of the present application, and do not constitute limitations on the technical solutions provided in the embodiments of the present application. Those skilled in the art may know that with the evolution of network architectures and the emergence of new service scenarios, the technical solutions provided in the embodiments of the present application can also be applied to similar technical problems.

[0083] FIG. 1 is a diagram of a communication system 100 to which an embodiment of the present application is applicable.

[0084] The communication system 100 shown in FIG. 1(a) includes a network device 10, a terminal device 20, and a terminal device 21. Both the terminal device 20 and the terminal device 21 are within the coverage area of ​​the network device 10. The network device 10 communicates with the terminal device via a Uu air interface, and the terminal device 20 communicates with the terminal device 21 via a PC5 interface. The communication system 100 shown in FIG. 1(b) includes the network device 10, the terminal device 20, and the terminal device 21. The terminal device 20 is within the coverage area of ​​the network device 10, and the terminal device 21 is outside the coverage area of ​​the network device 10. The communication system 100 shown in FIG. 1(c) includes the network device 10, the terminal device 20, the terminal device 21, and the terminal device 22. Neither terminal device 20 nor terminal device 21 is within the coverage area of ​​network device 10, and terminal device 22 is within the coverage area of ​​network device 10.

[0085] 1(a) and 1(b), the terminal device 20 may communicate with the terminal device 21 using resources scheduled by a network device, which may be referred to as licensed resources or licensed frequency bands, or the terminal device 20 may select resources by itself, specifically, select resources from a resource pool, which may be referred to as unlicensed resources or unlicensed frequency bands, to communicate with the terminal device 21. In the scenario shown in FIG. 1(c), because both the terminal device 20 and the terminal device 21 are in areas outside of network coverage, the terminal device 20 and the terminal device 21 may communicate in a self-resource selection manner.

[0086] It should be understood that the number of terminal devices and the number of network devices shown in FIG. 1 are merely examples, and the number of terminal devices and the number of network devices in a communication system are not limited in this application.

[0087] To more clearly understand the present application, the following describes concepts used in unlicensed spectrum communications.

[0088] 1. Licensed and Unlicensed Spectrum The spectrum used in wireless communication systems is classified into two types: licensed spectrum and unlicensed spectrum. In the licensed spectrum, UEs may use spectrum resources based on scheduling performed by network devices. The following mainly describes the unlicensed spectrum.

[0089] In unlicensed spectrum, transmitting devices may use spectrum resources through contention. In one possible method, transmitting devices compete for the channel through listen-before-talk (LBT) to use the channel resources.

[0090] 2. Resource Pool NR SL communication is performed based on a resource pool. A resource pool is a block of time-frequency resources used for SL communication. The frequency domain resources included in a resource pool are contiguous. The time domain resources included in a resource pool can be contiguous or non-contiguous. Different resource pools are distinguished by an SL resource pool identifier (e.g., SL-ResourcePoolID). If different resource pools have the same resource pool index, the time-frequency resources in the different resource pools can be considered to completely overlap.

[0091] In an SL-unlicensed (SL-U) communication scenario, a frequency band is shared by multiple UEs, such that, for example, UEs using SL technology (referred to as SL UEs), UEs using Wi-Fi technology, and UEs using Bluetooth technology transmit in the same frequency band. Therefore, an SL resource pool may also be understood as a set of resources that can be used for SL transmission.

[0092] 3. Resources A resource is a time-frequency resource within a resource pool. The time-domain resource may be represented by a symbol, a slot, a mini-slot, a partial slot, a sub-frame, a radio frame, a sensing slot, or the like.

[0093] The frequency domain resource may be represented by a resource element (RE), a resource block (RB), a subchannel, a bandwidth, a bandwidth part (BWP), a carrier, a channel, or an interlace.

[0094] 4.LBT The LBT mechanism is a channel access rule based on a random backoff. Specifically, before accessing a channel and starting data transmission, a terminal needs to sense whether the channel is idle. If the terminal senses that the channel has been idle for a certain period of time, the terminal can occupy the channel. If the terminal senses that the channel is not idle, the terminal needs to wait and can occupy the channel only after the channel has returned to idle again. Because there are regulatory requirements for using unlicensed frequency bands in various regions around the world, the LBT mechanism is a mandatory function for using unlicensed spectrum. Various types of terminals operating with different communication protocols can use unlicensed spectrum only when regulations are met, in order to use spectrum resources fairly and efficiently.

[0095] For unlicensed spectrum in the frequency range (frequency 1, FR1), before transmission, the UE needs to perform LBT on each 20 MHz channel, which may be referred to as an LBT channel. To avoid interference between different channels, the UE cannot transmit data across the entire 20 MHz bandwidth, but reserves a portion of the frequency domain resources as a guard band and transmits data only in the remaining portion of the frequency domain resources. This portion of the available resources is referred to as a resource block set (RB set). When the UE performs LBT operations on multiple contiguous 20 MHz channels and successfully accesses the channels, the guard band between two RB sets may be reserved for data transmission, thereby improving resource utilization.

[0096] To comply with regulations, the 3GPP organization classifies LBT mechanisms for NR systems into the following four types:

[0097] Category 1 LBT: After obtaining the channel occupancy time (COT), the communication device immediately transmits data after a short switching gap from the receiving status. Category 1 LBT is abbreviated as Cat 1 LBT. COT refers to the time period during which the communication device is allowed to occupy the channel after successfully accessing it. The switching gap must not exceed 16 μs.

[0098] Category 2 LBT is LBT without random backoff, abbreviated as Cat 2 LBT. Specifically, after sensing that the channel is idle for a certain period of time, a communication device can transmit data without performing random backoff.

[0099] Category 3 LBT is a random backoff LBT with a fixed contention window (CW) value, and is abbreviated as Cat 3 LBT. Specifically, a communication device may generate a random number N based on the fixed contention window value and transmit data after sensing that the channel is idle and continues for a time period determined based on the random number N. The contention window value is related to the minimum and maximum values ​​of N. The contention window value indicates the size of the contention window.

[0100] Category 4 LBT is a random backoff LBT with a variable contention window value, and is abbreviated as Cat 4 LBT. Specifically, a communication device may generate a random number N based on the variable contention window value and transmit data after sensing that the channel is idle for a period of time determined based on the random number N. The contention window value is related to the minimum and maximum values ​​of N, and the communication device may change the contention window value.

[0101] The SL-U device complies with the 3GPP protocol and uses the LBT mechanism as a channel access method. Specifically, the SL-U device uses the following types of LBT:

[0102] Type 1 LBT: The Cat 4 LBT described above. An SL-U device can access the channel and transmit data only after performing a random backoff. Specifically, a network device or a terminal device can perform a deferred sensing sensing slot duration (time is T d , the channel may start transmitting after sensing the channel to be idle for the first time and after counter N in step 4 below reaches zero. Specifically, according to the following steps, counter N is adjusted by sensing the channel to obtain an additional sensing slot period.

[0103] Step 1: N=N init Set N and then perform step 4. init is the value from 0 to CW p is a random number in the range of CW p is the contention window value.

[0104] Step 2: If N>0, the network device or the terminal device chooses to decrease the counter value, for example, set N=N−1, and then executes step 3.

[0105] Step 3: Sense the channel to obtain an additional sensing slot period, and if the channel is idle during the additional sensing slot period, perform step 4; otherwise, perform step 5.

[0106] Step 4: If N=0, stop and transmit data; otherwise, perform step 2.

[0107] Step 5: Another T d In the d , listens to the channel until it senses that the channel is found to be idle in all sensing slots, and then executes step 6.

[0108] Step 6: Another T d If it is detected that the channel is idle in all sensing slots in , execute step 4; otherwise, execute step 5.

[0109] T d is T f = 16 μs and subsequent m p The continuous sensing slot period (T sl m p See Table 1 for values ​​of CW min,p is the minimum contention window value, and CW max,p is the maximum contention window value, and CW min,p ≦CW p ≦CW max,p T mcot,p is the maximum length of the COT. Specifically, the COT transmitted by a network device or terminal device on a channel is T mcot,p does not exceed.

[0110] [Table 1]

[0111] Type 2A LBT: Cat 2 LBT with a 25 μs gap. After sensing the channel is idle for 25 μs, the SL-U device may access the channel and transmit data.

[0112] Type 2B LBT: Cat 2 LBT with a 16 μs gap. After sensing the channel is idle for 16 μs, the SL-U device may access the channel and transmit data.

[0113] Type 2C LBT: Cat 1 LBT with a maximum gap of 16 μs. SL-U devices do not need to sense the channel and can directly access the channel to transmit data after the maximum switching gap of 16 μs in COT.

[0114] 5. Channel occupancy (CO) and channel occupancy time (COT) A channel is a group of contiguous resource blocks (RBs) over which a channel access process is performed in the unlicensed spectrum. A channel may be understood to be a bandwidth used by a UE to perform channel access.

[0115] Channel occupancy refers to transmissions performed by a UE on one or more channels after the UE has performed a channel access process.

[0116] After performing Type 1 channel access, the UE occupies the channel for a continuous time period to transmit information, and this continuous time period is called channel occupation time. The frequency domain unit of COT is the channel, and the time domain unit of COT is ms or slot. In the embodiments of the present application, COT may be a time concept, specifically the time of SL transmission, or a resource concept, specifically the time domain resource occupied for SL transmission.

[0117] The time period for the UE to transmit information is T cot,pThe maximum channel occupancy time (MCOT) for different channel access priority classes (CAPC) must not exceed T cot,p When one UE accesses the channel and transmits information within the COT, the transmission time is equal to the maximum channel occupancy time T cot,p When multiple UEs transmit information in the COT, the transmission time of the UE initializing the COT and the UEs sharing the COT is equal to or longer than the maximum channel occupancy time T cot,p , where p is the CAPC of the UE initializing the COT, or p is the minimum CAPC among the CAPC values ​​of the UEs performing transmission within the COT.

[0118] 6. Physical sidelink feedback channel (PSFCH) resources The PSFCH resource represents a resource for transmitting information carried on the PSFCH, e.g., one PSFCH resource occupies two consecutive orthogonal frequency division multiplexing (OFDM) symbols in the time domain and one physical resource block (PRB) in the frequency domain.

[0119] If available, the PSFCH resource may be used to transmit feedback information. For example, in one physical sidelink shared channel (PSSCH) transmission, if the transmitting end uses control information to carry hybrid automatic repeat request acknowledgment (HARQ-ACK) feedback enabling information, the receiving end may feedback acknowledgement (ACK) or negative acknowledgement (NACK) information based on the decoding result of the data information carried on the PSSCH. The ACK or NACK information is transmitted via the PSFCH. PSSCH transmission refers to transmission performed via the PSSCH.

[0120] 7. Service scenarios supporting PSFCH feedback V2X is used as an example. V2X supports three scenarios: unicast, multicast, and broadcast. HARQ feedback is supported for unicast and multicast. There are two multicast scenarios: multicast1 and multicast2.

[0121] In a unicast scenario, one transmitting terminal and one receiving terminal form one unicast connection pair. After correctly receiving control information from the transmitting terminal, if the data information received via the PSSCH is correctly decoded, the receiving terminal transmits a PSFCH sequence corresponding to ACK information to the transmitting terminal based on the HARQ enable indication information in the control information. Otherwise, the receiving terminal feeds back a PSFCH sequence corresponding to NACK information. The receiving terminal receives control information from the transmitting terminal via the PSCCH. The receiving terminal transmits the PSFCH sequence to the transmitting terminal via the PSFCH.

[0122] In the multicast 1 (negative acknowledgment-only, NACK-only) scenario, after correctly receiving control information from the transmitting terminal, if the terminals in the group fail to decode the received data information, they feed back a PSFCH sequence corresponding to the NACK information based on the HARQ enable indication information in the control information. Otherwise, the terminals in the group do not feed back any information.

[0123] In the multicast 2 (NACK / ACK) scenario, after correctly receiving the control information from the transmitting terminal, if the terminals in the group correctly decode the received data information, they will feed back the PSFCH sequence corresponding to the ACK information according to the HARQ enable indication information in the control information. Otherwise, the terminals in the group will feed back the PSFCH sequence corresponding to the NACK information.

[0124] In the Type 1 transmission process, each transmitting UE is located in a distributed system, so each transmitting UE independently performs the Type 1 LBT procedure. Therefore, in the following cases: multiple UEs with the same CAPC use the same contention window value, and N packets are randomly acquired by multiple UEs based on the same contention window value. init The same can occur when N is randomly acquired by multiple UEs. init When the LBT is successful, multiple UEs may transmit data simultaneously, causing data conflicts (specifically, the signals are mixed together). As a result, the receiving end cannot demodulate the received signal, and the data transmission fails.

[0125] In consideration of this, an embodiment of the present application provides a contention window value determination method so that an appropriate contention window value can be determined based on the transmission status of a transport block (TB) to avoid mutual collisions between different UEs and improve system transmission efficiency.

[0126] 2 is a schematic flowchart of a conflict window value determination method 200 according to an embodiment of the present application. The method 200 may include the following steps:

[0127] S210: The terminal device determines a reference period, and the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted.

[0128] The COT to which a reference duration belongs is the COT that includes the reference duration. When the time length of the reference duration is equal to or less than one COT, the reference duration includes part or all of the COT to which the reference duration belongs. For ease of explanation, the COT to which a reference duration belongs is hereinafter referred to as the first COT.

[0129] The priority of the first COT is the priority of the transmission with the lowest priority among one or more transmissions corresponding to TBs in the first COT. The transmission priority refers to a channel access priority class (CAPC). A TB in the first COT is a TB transmitted in the first COT, and the TB transmitted in the first COT may include one or more TBs. For example, if the TBs in the first COT include a TB corresponding to a transmission whose CAPC is 1, a TB corresponding to a transmission whose CAPC is 2, and a TB corresponding to a transmission whose CAPC is 3, the priority value of the first COT is 3, or the CAPC of the first COT is 3.

[0130] The transmission priority corresponding to a TB to be transmitted is the priority of the transmission with the lowest priority among one or more transmissions corresponding to the TB to be transmitted. For example, if the TB to be transmitted includes a TB corresponding to a transmission whose CAPC is 2 and a TB corresponding to a transmission whose CAPC is 3, the priority value of the TB to be transmitted is 3, or the CAPC of the TB to be transmitted is 3. The TB to be transmitted may include one or more TBs.

[0131] For example, the cast type of the TB in the first COT is different from the cast type of the TB to be transmitted, the TB in the first COT corresponds to at least two cast types, or the TB to be transmitted corresponds to at least two cast types.

[0132] The cast type of the TB may include the following four types: multicast 1, multicast 2, unicast, and hybrid automatic repeat request (HARQ) disabled.

[0133] If the cast type of the TB is multicast 1, the transmitting device transmits the TB to the terminal device group in a multicast manner. Correspondingly, when a receiving device in the terminal device group fails to decode the received TB, the receiving device feeds back a PSFCH sequence corresponding to NACK information to the transmitting device; otherwise, the receiving device feeds back no information or feeds back other information different from the NACK information.

[0134] If the cast type of the TB is multicast 2, the transmitting device transmits the TB to the terminal device group in a multicast manner. Correspondingly, when the received TB is successfully decoded, the receiving devices in the terminal device group feed back a PSFCH sequence corresponding to ACK information to the transmitting device; otherwise, the receiving devices feed back a PSFCH sequence corresponding to NACK information.

[0135] If the cast type of the TB is unicast, the transmitting device transmits the TB in a unicast manner. Correspondingly, when the received TB is successfully decoded, the receiving device feeds back a PSFCH sequence carrying ACK information to the transmitting device; otherwise, the receiving device feeds back a PSFCH sequence carrying NACK information.

[0136] If the cast type of the TB is HARQ disabled, the transmitting device transmits the TB in a unicast manner or a multicast or broadcast manner, and correspondingly, the receiving device does not feedback any information regardless of whether the receiving device successfully decodes the received TB.

[0137] FIG. 3 is a diagram of the relationship between the cast type of the TB in the first COT and the cast type of the TB to be transmitted according to one embodiment of the present application.

[0138] The TBs in the first COT may correspond to at least any two cast types. In this case, the TBs to be transmitted may correspond to any cast type, or the TBs to be transmitted may correspond to at least any two cast types. As shown in (a) and (b) of FIG. 3, the TBs in the first COT include a TB whose cast type is HARQ disabled, a TB whose cast type is unicast, and a TB whose cast type is multicast 2. In other words, the TBs in the first COT correspond to three cast types. As shown in (a) of FIG. 3, the TBs to be transmitted include a TB whose cast type is HARQ disabled and a TB whose cast type is unicast. In other words, the TBs to be transmitted correspond to two cast types. Furthermore, as shown in (b) of FIG. 3, the TBs to be transmitted include a TB whose cast type is HARQ disabled. In other words, the TBs to be transmitted correspond to one cast type.

[0139] The TBs to be transmitted may correspond to any two cast types. In this case, the TBs in the first COT may correspond to any one cast type, or the TBs in the first COT may correspond to at least any two cast types. As shown in (c) and (d) of FIG. 3, the TBs to be transmitted include TBs whose cast type is HARQ disabled and TBs whose cast type is unicast. As shown in (c) of FIG. 3, the TBs in the first COT include TBs whose cast type is multicast 2. In other words, the TBs in the first COT correspond to one cast type. Furthermore, as shown in (d) of FIG. 3, the TBs in the first COT include TBs whose cast type is HARQ disabled and TBs whose cast type is unicast. In other words, the TBs in the first COT correspond to two cast types.

[0140] Both the TB to be transmitted and the TB in the first COT include only one cast type. This embodiment of the present application is applicable to the case where the cast type included in the TB to be transmitted is different from the cast type included in the TB in the first COT. As shown in (e) of Figure 3, the TB in the first COT includes a TB whose cast type is multicast 2, and the TB to be transmitted includes a TB whose cast type is unicast. In other words, the cast type of the TB in the first COT is different from the cast type of the TB to be transmitted.

[0141] The following describes the reference period determined by the terminal device.

[0142] For example, the reference period includes at least one transmitted TB.

[0143] The reference period includes one transmitted TB, which includes the following cases: the reference period includes the initial transmission of the TB and all retransmissions, the reference period includes the last retransmission of the TB, the reference period includes the initial transmission of the TB and the feedback information for the initial transmission of the TB is an ACK, or the reference period includes the retransmission of the TB and the feedback information for the retransmission of the TB is an ACK.

[0144] When the reference period includes the initial transmission of the TB and all retransmissions, it means that the initial transmission of the TB and all retransmissions were performed within the reference period. When the reference period includes the last retransmission of the TB, it means that the last retransmission of the TB was performed within the reference period, and the time points of the initial transmission of the TB and other retransmissions are not limited. When the reference period includes the last retransmission of the TB, it may include other retransmissions and the initial transmission of the TB, or it may not include other retransmissions or the initial transmission of the TB. When the reference period includes the initial transmission of the TB, it means that the initial transmission of the TB was performed within the reference period. When the reference period includes retransmissions of the TB, it means that retransmissions of the TB were performed within the reference period.

[0145] Optionally, if after the last updated contention window value, the terminal device may determine multiple candidate reference periods that include at least one transmitted TB, the reference period finally determined by the terminal device may be the candidate reference period among the multiple candidate reference periods that is closest to the current time, and the priority of the COT to which the candidate reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted.

[0146] As explained above, if a reference period includes part or all of the COT to which the reference period belongs, then when the reference period includes at least one transmitted TB, the COT to which the reference period belongs also includes at least one transmitted TB.

[0147] It can be further understood that if the reference period is closest to the current time, contains at least one transmitted TB, and the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted, the COT to which the reference period belongs is the COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted within the transmitted COT after the last updated contention window value, and the COT contains at least one transmitted TB and is closest to the current time.

[0148] Optionally, if there are no transmitted TBs after the last updated contention window value, the reference period determined by the terminal device may be part or all of the COT that is closest to the current time, and whose priority is the same as the transmission priority corresponding to the TB to be transmitted. In other words, if there are no transmitted TBs after the last updated contention window value, the COT to which the reference period belongs is the COT that is closest to the current time within the transmitted COT, and whose priority is the same as the transmission priority corresponding to the TB to be transmitted. Furthermore, the reference period determined by the terminal device is part or all of the COT to which the reference period belongs.

[0149] For example, the cast type of at least one TB in the reference period is the same as the cast type of at least one TB in the TB to be transmitted.

[0150] For example, if the TBs to be transmitted include TBs whose cast type is unicast and TBs whose cast type is HARQ disabled, the reference period determined by the terminal device may include TBs whose cast type is unicast and / or TBs whose cast type is HARQ disabled.

[0151] Optionally, after the last updated contention window value, the terminal device may determine multiple candidate reference periods, and if the cast type of at least one TB in each of the multiple candidate reference periods is the same as the cast type of at least one TB in the TB to be transmitted, the reference period finally determined by the terminal device may be the candidate reference period among the multiple candidate reference periods that is closest to the current time, and the priority of the COT to which the candidate reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted.

[0152] As explained above, when a reference period includes part or all of the COT to which the reference period belongs, the cast type of at least one TB in the reference period is the same as the cast type of at least one TB in the TB to be transmitted, and the cast type of at least one TB in the COT to which the reference period belongs is the same as the cast type of at least one TB in the TB to be transmitted.

[0153] It can be further understood that if the reference period is closest to the current time, the cast type of at least one TB in the reference period is the same as the cast type of at least one TB in the TB to be transmitted, the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted, the COT to which the reference period belongs is the COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted in the transmitted COT after the last updated contention window value, the COT is closest to the current time, and the cast type of at least one TB in the COT is the same as the cast type of at least one TB in the TB to be transmitted.

[0154] Optionally, the terminal device may first determine the COT to which the reference period belongs, and then determine the reference period based on the COT to which the reference period belongs. For ease of explanation, the COT to which the reference period belongs is hereinafter referred to as the first COT. The following describes how the terminal device determines the first COT.

[0155] For example, the first COT is a COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted. In other words, the terminal device may determine the first COT as a COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted in the transmitted COT after the last updated contention window value. In this way, the terminal device may determine the reference period based on the first COT.

[0156] Optionally, the transmitted COT after the last updated contention window value includes a plurality of COTs whose priority is the same as the transmission priority corresponding to the TB to be transmitted. In this case, the first COT is the COT closest to the current time among the plurality of COTs. In other words, the terminal device may determine the COT closest to the current time among the transmitted COT after the last updated contention window value, whose priority is the same as the transmission priority corresponding to the TB to be transmitted, as the first COT. In this way, the terminal device may determine the reference period based on the first COT.

[0157] Optionally, the first COT includes at least one first TB, and the cast type of the first TB is the same as the cast type of at least one TB in the TB to be transmitted. In other words, a TB whose cast type in the first COT is the same as the cast type of at least one TB in the TB to be transmitted may be referred to as the first TB. In other words, the terminal device may determine as the first COT a COT that includes at least one first TB in the transmitted COT after the last updated contention window value and whose priority is the same as the transmission priority corresponding to the TB to be transmitted.

[0158] For example, the TBs to be transmitted include a TB whose cast type is unicast and a TB whose cast type is HARQ disabled. The transmitted COT after the last updated contention window value includes two COTs, namely COT#1 and COT#2, whose priorities are the same as the transmission priorities corresponding to the TBs to be transmitted. COT#1 includes a TB whose cast type is multicast#2, and COT#2 includes a TB whose cast type is multicast#2 and a TB whose cast type is unicast. Because both COT#2 and the TBs to be transmitted include TBs whose cast type is unicast, the terminal device determines COT#2 as the first COT.

[0159] Optionally, the transmitted COT after the last updated contention window value includes a plurality of COTs whose priority is the same as the transmission priority corresponding to the TB to be transmitted, and the plurality of COTs include at least one first TB. In this case, the first COT is the COT closest to the current time among the plurality of COTs. In other words, the terminal device may determine as the first COT the COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted among the transmitted COT after the last updated contention window value, the COT including at least one first TB and closest to the current time. In this way, the terminal device may determine the reference period based on the first COT.

[0160] Optionally, the transmitted COT after the last updated contention window value does not include at least one first TB, in which case the first COT is the COT in the transmitted COT that is closest to the current time and whose priority is the same as the transmission priority corresponding to the TB to be transmitted.

[0161] Optionally, the first COT includes at least one transmitted TB. In other words, the terminal device may determine as the first COT a COT that includes at least one transmitted TB in the transmitted COT after the last updated contention window value, and whose priority is the same as the transmission priority corresponding to the TB to be transmitted.

[0162] The COT includes one transmitted TB, which includes the following cases: the COT includes the initial transmission of the TB and all retransmissions, the COT includes the last retransmission of the TB, the COT includes the initial transmission of the TB, and the feedback information for the initial transmission of the TB is an ACK, or the COT includes the retransmission of the TB, and the feedback information for the retransmission of the TB is an ACK.

[0163] Optionally, the transmitted COT after the last updated contention window value includes a plurality of COTs whose priority is the same as the transmission priority corresponding to the TB to be transmitted, and the plurality of COTs include at least one transmitted TB. In this case, the first COT is the COT closest to the current time among the plurality of COTs. In other words, the terminal device may determine as the first COT the COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted among the transmitted COT after the last updated contention window value, the COT including at least one transmitted TB and closest to the current time. In this way, the terminal device may determine the reference period based on the first COT.

[0164] Optionally, the transmitted COT after the last updated contention window value does not include at least one transmitted TB, in which case the first COT is the COT in the transmitted COT that is closest to the current time and whose priority is the same as the transmission priority corresponding to the TB to be transmitted.

[0165] Optionally, the priority of the first COT is the same as the transmission priority corresponding to the TB to be transmitted, and the first COT includes at least one first TB and at least one transmitted TB.

[0166] Optionally, the transmitted COT after the last updated contention window value includes a COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted, the COT including at least one first TB, and the COT including at least one transmitted TB, where the first COT is the COT closest to the current time among the multiple COTs.

[0167] The following describes the start and end points of the reference period: For ease of explanation, the COT to which the reference period belongs is referred to as the first COT below.

[0168] Optionally, the start time of the reference period is any one of the following: the start time of the first COT; the start time of transmission of a transmitted TB in the first COT; the start time of transmission of a TB corresponding to the lowest transmission priority among the TBs in the first COT; the start time of transmission of a first TB in the first COT, where the cast type of the first TB is the same as the cast type of at least one TB among the TBs to be transmitted; or the start time of transmission of a TB among the TBs corresponding to feedback information received by the terminal device that is first transmitted within the first COT.

[0169] Optionally, if the start point of the reference period is the transmission start point of a transmitted TB in the first COT and the first COT includes multiple transmitted TBs, the start point of the reference period may be the transmission start point of any one of the multiple transmitted TBs, the transmission start point of a TB corresponding to the lowest transmission priority among the multiple transmitted TBs, the transmission start point of a TB among the multiple transmitted TBs whose cast type is the same as the cast type of at least one TB to be transmitted, or the transmission start point of the first transmitted TB among the multiple transmitted TBs.

[0170] Optionally, when the start point of the reference period is the start point of transmission of the first TB and the first COT includes multiple first TBs, the start point of the reference period may be the start point of transmission of any one of the multiple first TBs, the start point of transmission of the first TB corresponding to the lowest transmission priority among the multiple first TBs, or the start point of transmission of the first transmitted TB among the multiple first TBs.

[0171] FIG. 4 is a diagram for determining the start point of the reference period in the first COT. As shown in FIG. 4, the first COT includes slots 1 to 7. Slot 1 is for transmitting the first blind transmission of TB#1, slot 4 is for transmitting the second blind transmission of TB#1, the CAPC of the transmission corresponding to TB#1 is 2, and the cast type of TB#1 is HARQ disabled. Slot 2 is for transmitting the initial transmission of TB#2, slot 3 is for transmitting the first retransmission of TB#2, the CAPC of the transmission corresponding to TB#2 is 3, and the cast type of TB#2 is unicast. Slot 5 is for transmitting the initial transmission of TB#3, the CAPC of the transmission corresponding to TB#3 is 2, and the cast type of TB#3 is unicast. Slot 6 is for transmitting the initial transmission of TB#4, and slot 7 is for transmitting the first retransmission of TB#4, the CAPC of the transmission corresponding to TB#4 is 2, and the cast type of TB#4 is multicast 2. The terminal device receives feedback information of the initial transmission of TB#2, feedback information of the first retransmission of TB#2, and feedback information of the initial transmission of TB#3 in slot 7. Assuming that the feedback information of the first retransmission of TB#2 is an ACK, TB#2 is a transmitted TB included in the first COT. Assuming that TB#4 includes only one retransmission, TB#4 is also a transmitted TB included in the first COT.

[0172] If the start of the reference period is the start of the first COT, then the start of the reference period is the start of slot 1.

[0173] If the start of the reference period is the start of transmission of a transmitted TB in the first COT, the start of the reference period may be the start of transmission of TB#2, i.e., the start of slot 2, or the start of transmission of TB#4, i.e., the start of slot 6. For example, since the cast type of TB#2 is the same as the cast type of at least one TB to be transmitted, the start of slot 2 may be determined as the start of the reference period.

[0174] If the start of the reference period is the start of transmission of the TB corresponding to the lowest transmission priority among the TBs in the first COT, the start of the reference period is the start of transmission of TB#2, i.e., the start of the reference period is the start of slot 2.

[0175] If the start of the reference period is the start of transmission of the first TB, the start of the reference period may be the start of transmission of TB#1, i.e., the start of slot 1, the start of transmission of TB#2, i.e., the start of slot 2, or the start of transmission of TB#3, i.e., the start of slot 5. For example, if the start of transmission of the first TB, which has the lowest transmission priority, is selected as the start of the reference period, the start of the reference period is the start of slot 2.

[0176] If the start of the reference period is the start of transmission of the TB within the TB corresponding to the feedback information received by the terminal device and that is the first TB transmitted within the first COT, the start of the reference period is the start of transmission of TB#2, i.e., the start of slot 2.

[0177] It should be noted that FIG. 4 is described using an example in which the terminal device receives feedback information within the first COT. The terminal device may receive feedback information for the TB in the first COT within the first COT, or the terminal device may receive feedback information for the TB in the first COT after the first COT. This is not limited in this embodiment of the present application. For example, the terminal device may receive feedback information for the initial transmission of TB#4 and feedback information for the first retransmission of TB#4 in slot 8 after the first COT.

[0178] Optionally, the end point of the reference period is any one of the following: the end point of the first COT; the end point of transmission of a TB transmitted in the first COT; the end point of transmission of a TB corresponding to the lowest transmission priority among the TBs in the first COT; the end point of transmission of a first TB in the first COT, the cast type of which is the same as the cast type of at least one TB among the TBs to be transmitted; the end point of transmission of a TB that is last transmitted in the first COT among the TBs corresponding to the feedback information received by the terminal device; or the end point of the first transmission slot of a TB that is first transmitted in the first COT among the TBs corresponding to the feedback information received by the terminal device.

[0179] Optionally, if the end point of the reference period is the transmission end point of a transmitted TB in the first COT and the first COT includes multiple transmitted TBs, the end point of the reference period may be the transmission end point of any one of the multiple transmitted TBs, the transmission end point of a TB corresponding to the lowest transmission priority among the multiple transmitted TBs, the transmission end point of a TB among the multiple transmitted TBs whose cast type is the same as the cast type of at least one TB to be transmitted, or the transmission end point of the last transmitted TB among the multiple transmitted TBs.

[0180] Optionally, when the end point of the reference period is the end point of transmission of the first TB and the first COT includes multiple first TBs, the end point of the reference period may be the end point of transmission of any one of the multiple first TBs, the end point of transmission of the first TB corresponding to the lowest transmission priority among the multiple first TBs, or the end point of transmission of the TB that was last transmitted among the multiple first TBs.

[0181] Optionally, the end point of the reference period may be the end point of transmission of the TB corresponding to the lowest transmission priority among the TBs in the first COT, and if the reference period includes multiple TBs corresponding to the lowest transmission priorities, the end point of the reference period may be the end point of transmission of any one of the multiple TBs corresponding to the lowest transmission priority, or the end point of transmission of the first transmitted TB among the multiple TBs corresponding to the lowest transmission priority.

[0182] As shown in FIG. 4, if the end of the reference period is the end of the first COT, then the end of the reference period is the end of slot 7.

[0183] If the end of the reference period is the end of transmission of a transmitted TB in the first COT, the end of the reference period may be the end of transmission of TB#2, i.e., the end of slot 3, or the end of transmission of TB#4, i.e., the end of slot 7. For example, since the cast type of TB#2 is the same as the cast type of at least one TB to be transmitted, the end of slot 3 may be determined as the end of the reference period.

[0184] If the end point of the reference period is the end point of transmission of the TB corresponding to the lowest transmission priority among the TBs in the first COT, the end point of the reference period is the end point of transmission of TB#2, i.e., the end point of slot 3.

[0185] If the end of the reference period is the end of the transmission of the first TB, the end of the reference period may be the end of the transmission of TB#1, i.e., the end of slot 4, the end of the transmission of TB#2, i.e., the end of slot 3, or the end of the transmission of TB#3, i.e., the end of slot 5. For example, if the end of the transmission of the first TB, which has the lowest transmission priority, is selected as the end of the reference period, the end of the reference period is the end of slot 3.

[0186] If the end point of the reference period is the end point of transmission of the TB within the TB corresponding to the feedback information received by the terminal device and that was last transmitted within the first COT, the end point of the reference period is the end point of transmission of TB#3, i.e., the end point of slot 5.

[0187] If the end point of the reference period is the end point of the first transmission slot of the TB within the TB corresponding to the feedback information received by the terminal device and transmitted first within the first COT, the end point of the reference period is the end point of the first transmission slot of TB#2, i.e., the end point of slot 2.

[0188] 4, an example in which the feedback information of the initial transmission of TB#2 is NACK is used for explanation. If the feedback information of the initial transmission of TB#2 is ACK, the end time of the transmission of TB#2 is the end time of slot 2.

[0189] As explained above, the reference period may include part or all of the first COT. If the reference period includes the entire first COT, the start of the reference period is the start of the first COT and the end of the reference period is the end of the first COT. If the reference period includes part of the first COT, the start of the reference period is later than the start of the first COT and / or the end of the reference period is earlier than the end of the first COT.

[0190] Optionally, the cast type of at least one TB in the reference period is the same as the cast type of at least one TB in the TB to be transmitted. In other words, when the first COT includes at least one first TB, if the cast type of at least one TB in the reference period must be the same as the cast type of at least one TB in the TB to be transmitted, the start time of the reference period determined by the terminal device is not later than the transmission start time of the first TB, the end time of the reference period determined is not earlier than the transmission end time of the first TB, and the cast type of the first TB is the same as the cast type of at least one TB in the TB to be transmitted. As shown in FIG. 4, if the reference period needs to include TB#1, the start time of the reference period determined by the terminal device is the transmission start time of TB#1 (i.e., the start time of slot 1), and the end time of the reference period determined is not earlier than the transmission end time of TB#1 (i.e., the end time of slot 4). Alternatively, if the reference period needs to include TB#2, the start of the reference period determined by the terminal device is not later than the start of transmission of TB#2 (i.e., the start of slot 2), and the end of the reference period determined is not earlier than the end of slot 2 or slot 3. If the feedback information for the initial transmission of TB#2 in slot 2 is ACK, the end of the reference period determined by the terminal device is not earlier than the end of slot 2. If the feedback information for the initial transmission of TB#2 in slot 2 is NACK, the end of the reference period determined by the terminal device is not earlier than the end of slot 3.

[0191] Optionally, the reference period includes at least one transmitted TB. In other words, when the first COT includes at least one transmitted TB, if the reference period must include at least one transmitted TB, the start time of the reference period determined by the terminal device is not later than the start time of the transmission of a transmitted TB in the first COT, and the end time of the reference period determined by the terminal device is not earlier than the end time of the transmission of a transmitted TB in the first COT. As shown in FIG. 4, if the reference period must include TB#2, the start time of the reference period determined by the terminal device is not later than the start time of slot 2, and the end time of the reference period determined by the terminal device is not earlier than the end time of slot 2 or slot 3. If the feedback information of the initial transmission of TB#2 in slot 2 is ACK, the end time of the reference period determined by the terminal device is not earlier than the end time of slot 2. If the feedback information of the initial transmission of TB#2 in slot 2 is NACK, the end time of the reference period determined by the terminal device is not earlier than the end time of slot 3.

[0192] The reference period includes one transmitted TB, which includes the following cases: the reference period includes the initial transmission of the TB and all retransmissions, the reference period includes the last retransmission of the TB, the reference period includes the initial transmission of the TB and the feedback information for the initial transmission of the TB is an ACK, or the reference period includes the retransmission of the TB and the feedback information for the retransmission of the TB is an ACK.

[0193] Optionally, before S210, method 200 further includes the terminal device determining that the cast type of the TB in the transmitted COT after the last updated contention window value is different from the cast type of the TB to be transmitted, or that the TB in the transmitted COT corresponds to at least two cast types.

[0194] In other words, if the terminal device determines that the cast type of the TB in the transmitted COT after the last updated contention window value is different from the cast type of the TB to be transmitted, or that the TB in the transmitted COT corresponds to at least two cast types, the terminal device determines the reference period according to the method described in S210.

[0195] Optionally, before S210, the method 200 further includes: the terminal device determining that the TB to be transmitted corresponds to at least two cast types.

[0196] In other words, if the terminal device determines that the TB to be transmitted corresponds to at least two cast types, the terminal device determines the reference period according to the method described in S210.

[0197] Optionally, before S210, method 200 further includes the terminal device determining that there is no transmitted TB whose cast type is the same as the cast type of the TB to be transmitted after the last updated contention window value.

[0198] In other words, if the terminal device determines that there is no transmitted TB whose cast type is the same as the cast type of the TB to be transmitted after the last updated contention window value, the terminal device determines the reference period according to the method described in S210.

[0199] The transmitted TB includes the following two cases: both the initial transmission and all retransmissions of the TB are completed, and the feedback information of the initial transmission of the TB is an ACK, or the feedback information of the retransmission of the TB is an ACK.

[0200] S220: The terminal device determines a target contention window value based on a transmission status of at least one TB in a reference period, where the target contention window value is for preempting a channel of the TB to be transmitted.

[0201] After determining the reference period, the terminal device determines a target contention window value based on the transmission status of at least one TB within the reference period.

[0202] In a possible implementation, the terminal device may determine the target contention window value based on the transmission status of the second TB within the reference period.

[0203] For example, the second TB satisfies Condition #A: both the initial transmission and the retransmission of the second TB are completed, and the feedback information of the last retransmission of the second TB is NACK.

[0204] According to the definition of a transmitted TB in the preceding description, if both the initial transmission and the retransmission of the second TB are completed, it indicates that the second TB is a transmitted TB. Therefore, condition #A may also be understood as the second TB being a TB among the transmitted TBs included in the reference period, about which feedback information is received by the terminal device.

[0205] As shown in FIG. 5, the reference period includes slots 1 to 7. Slot 1 is for transmitting the first blind transmission of TB#1, slot 4 is for transmitting the second blind transmission of TB#1, the CAPC of the transmission corresponding to TB#1 is 2, and the cast type of TB#1 is HARQ disabled. Slot 2 is for transmitting the initial transmission of TB#2, slot 3 is for transmitting the first retransmission of TB#2, and slot 5 is for transmitting the last retransmission of TB#2, the CAPC of the transmission corresponding to TB#2 is 3, and the cast type of TB#2 is unicast. Slot 6 is for transmitting the initial transmission of TB#3, the CAPC of the transmission corresponding to TB#3 is 2, and the cast type of TB#3 is multicast 2. Slot 7 is for transmitting the initial transmission of TB#4, the CAPC of the transmission corresponding to TB#4 is 2, and the cast type of TB#4 is multicast 2. The terminal device receives feedback information of the initial transmission of TB#2, i.e., NACK, feedback information of the first retransmission of TB#2, i.e., NACK, and feedback information of the last retransmission of TB#2, i.e., NACK, in slot 7. The terminal device receives feedback information of the initial transmission of TB#3, i.e., ACK, in slot 8.

[0206] In the TB included in the reference period, both the initial transmission and retransmission of TB#2 have been completed, and the feedback information of the last retransmission of TB#2 is NACK. Therefore, the terminal device can determine TB#2 as the second TB.

[0207] For example, the second TB satisfies condition #B: the feedback information of the initial transmission or retransmission of the second TB is an ACK.

[0208] According to the definition of a transmitted TB in the preceding description, if the feedback information of the initial transmission or retransmission of the second TB is an ACK, it indicates that the second TB is a transmitted TB. Therefore, condition #B may also be understood as the second TB being a TB among the transmitted TBs included in the reference period, for which feedback information is received by the terminal device.

[0209] 5, among the TBs included in the reference period, the feedback information of the initial transmission of TB#3 is ACK. Therefore, the terminal device may determine TB#3 as the second TB.

[0210] Based on the above description, condition #A and condition #B may be combined into one condition, and the second TB is a TB among the transmitted TBs included in the reference period, regarding which feedback information is received by the terminal device.

[0211] For example, the second TB satisfies condition #C: according to the cast type order, the cast type of the second TB is ranked before the cast types of the remaining TBs in the reference period.

[0212] The cast type order is not limited in this embodiment of the present application.

[0213] For example, the cast type order is predefined, and the order of different cast types from front to back is multicast 2, multicast 1, unicast, and HARQ disabled. Based on this order, the terminal device may determine TB#3 in the reference period shown in FIG. 5 as the second TB.

[0214] In another example, the cast type order is predefined, and the order of different cast types from front to back is multicast 2, unicast, multicast 1, and HARQ disabled. Based on this order, the terminal device may determine TB#3 in the reference period shown in FIG. 5 as the second TB.

[0215] In another example, the cast type order is predefined, and the order of different cast types from front to back is unicast, multicast 2, multicast 1, and HARQ disabled. Based on this order, the terminal device may determine TB#2 in the reference period shown in FIG. 5 as the second TB.

[0216] In another example, the order of different cast types is determined based on a predefined cast type order and the cast type corresponding to the TB to be transmitted. Specifically, the cast type corresponding to the TB to be transmitted is ranked before other cast types. If the TB to be transmitted corresponds to multiple cast types, the multiple cast types corresponding to the TB to be transmitted are ranked according to a predefined cast type order. If there are multiple remaining cast types different from the cast type corresponding to the TB to be transmitted, the remaining cast types are ranked according to a predefined cast type order. Alternatively, among the cast types corresponding to the TB to be transmitted, cast types other than HARQ disabled are ranked before other cast types different from the cast type corresponding to the TB to be transmitted, with HARQ disabled coming last.

[0217] For example, if the predefined cast type order is multicast 2, multicast 1, unicast, and HARQ disabled, and the cast type corresponding to the TB to be transmitted is unicast, the cast type order from front to back determined by the terminal device based on the predefined cast type order and the cast type corresponding to the TB to be transmitted is unicast, multicast 2, multicast 1, and HARQ disabled. Based on this order, the terminal device may determine TB#2 in the reference period shown in FIG. 5 as the second TB.

[0218] For example, if the predefined cast type order is multicast 2, multicast 1, unicast, and HARQ disabled, and the cast types of the TBs to be transmitted include unicast and HARQ disabled, the cast type order obtained by the terminal device by ranking the cast types corresponding to the TBs to be transmitted based on the predefined cast type order is unicast and HARQ disabled. Therefore, the terminal device sorts the cast types other than the cast type corresponding to the TBs to be transmitted based on the predefined cast type order to obtain the cast type order: multicast 2 and multicast 1. Furthermore, the terminal device sorts the cast type corresponding to the TBs to be transmitted before the remaining cast types, so that the determined order of the cast types from front to back is unicast, HARQ disabled, multicast 2, and multicast 1. Based on this order, the terminal device may determine TB#2 in the reference period shown in FIG. 5 as the second TB.

[0219] Alternatively, the terminal device sorts the cast types corresponding to the TBs to be transmitted, except for the HARQ disabled type, first. Specifically, the terminal device sorts the unicast type first. Then, the terminal device sorts the cast types other than the cast type corresponding to the TBs to be transmitted after the unicast type based on the preset cast type order, so that the HARQ disabled type finally comes last. Therefore, the cast type order determined by the terminal device is unicast, multicast 2, multicast 1, and HARQ disabled.

[0220] For example, if the predefined cast type order is multicast 2, multicast 1, unicast, and HARQ disabled, and the cast types of the TBs to be transmitted include unicast and multicast 2, the order of cast types from front to back determined by the terminal device based on the predefined cast type order and the cast types corresponding to the TBs to be transmitted is multicast 2, unicast, multicast 1, and HARQ disabled. Based on this order, the terminal device may determine TB#3 in the reference period shown in FIG. 5 as the second TB.

[0221] For example, the second TB satisfies condition #D: the cast type of the second TB is the same as the cast type of at least one TB in the TB to be transmitted.

[0222] It can be understood that when the second TB satisfies condition #D, the second TB is the same as the first TB described above.

[0223] In the above description of Figure 5, the cast type of TB#1 within the reference period is the same as the cast type of at least one TB to be transmitted, and the cast type of TB#2 within the reference period is the same as the cast type of at least one TB to be transmitted, so the terminal device may determine TB#1 and / or TB#2 as the second TB.

[0224] Optionally, if the reference period does not include a TB whose cast type is the same as the cast type of at least one TB in the TB to be transmitted, the terminal device selects a TB that satisfies condition #C.

[0225] For example, the second TB satisfies condition #E: the second TB is the last or first transmitted TB within the reference period and is a TB within the TB corresponding to the feedback information received by the terminal device.

[0226] In the above description of Figure 5, the terminal device receives feedback information for TB#2 and feedback information for TB#3, and since TB#3 is the last TB transmitted within the reference period, the terminal device may determine TB#3 as the second TB. Alternatively, since TB#2 is the first TB transmitted within the reference period, the terminal device may determine TB#2 as the second TB.

[0227] For example, the second TB satisfies condition #F: the transmission priority corresponding to the second TB is the same as the transmission priority corresponding to the TB to be transmitted.

[0228] In the TBs to be transmitted shown in Figure 5, it is assumed that the CAPC of the transmission corresponding to the first TB is 3 and the CAPC of the transmission corresponding to the second TB is 1. Referring to the above description of Figure 5, since the CAPC of the transmission corresponding to TB#2 in the reference period is 3, the terminal device may determine TB#2 as the second TB.

[0229] For example, the second TB satisfies condition #G: the contention window value determined based on the transmission status of the second TB is greater than the contention window value determined based on the transmission status of the remaining TBs in the reference period.

[0230] In other words, the terminal device may determine a candidate contention window value based on the transmission status of each TB within the reference period, and then determine the maximum value among the at least one candidate contention window value as the target contention window value.

[0231] In the above description of FIG. 5, the TBs in the reference period include TB#1, TB#2, and TB#3. The terminal device may determine a candidate contention window value CWp1 based on the transmission status of TB#1, determine a candidate contention window value CWp2 based on the transmission status of TB#2, and determine a candidate contention window value CWp3 based on the transmission status of TB#3. Furthermore, the terminal device may determine the maximum value among CWp1, CWp2, and CWp3 as the target contention window value. It may be understood that the TB corresponding to the maximum candidate contention window value is the second TB. For example, if CWp2 is the maximum value among CWp1, CWp2, and CWp3, the second TB is TB#2.

[0232] For example, the second TB satisfies condition #H: the contention window value determined based on the transmission status of the second TB is smaller than the contention window values ​​determined based on the transmission status of the remaining TBs in the reference period.

[0233] In other words, the terminal device may determine a candidate contention window value based on the transmission status of each TB within the reference period, and then determine the minimum value among the at least one candidate contention window value as the target contention window value.

[0234] In the above description of FIG. 5, the TBs in the reference period include TB#1, TB#2, and TB#3. The terminal device may determine a candidate contention window value CWp1 based on the transmission status of TB#1, determine a candidate contention window value CWp2 based on the transmission status of TB#2, and determine a candidate contention window value CWp3 based on the transmission status of TB#3. Furthermore, the terminal device may determine the minimum value among CWp1, CWp2, and CWp3 as the target contention window value. It may be understood that the TB corresponding to the minimum candidate contention window value is the second TB. For example, if CWp3 is the minimum value among CWp1, CWp2, and CWp3, the second TB is TB#3.

[0235] For example, the second TB satisfies condition #I: the transmission priority corresponding to the second TB is higher than the transmission priority corresponding to the remaining TBs in the reference period.

[0236] In the above description of Figure 5, the CAPC of the transmission corresponding to TB#1 and the CAPC of the transmission corresponding to TB#3 are both 2, so the priority of the transmission corresponding to TB#1 and the transmission corresponding to TB#3 is higher than the priority of the transmission corresponding to TB#2. That is, the terminal device may determine TB#1 and TB#3 as the second TB.

[0237] For example, the second TB satisfies condition #J: the second TB is a TB within the TBs in the reference period, for which the terminal device has received feedback information corresponding to the TB.

[0238] Condition #J may also be understood as follows: if the reference period includes a TB whose cast type is HARQ enabled, the terminal device preferentially determines the target contention window value based on the transmission status of a TB having feedback information within the TB whose cast type is HARQ enabled. Alternatively, Condition #J may also be understood as follows: if the reference period includes a TB whose cast type is HARQ enabled and a TB whose cast type is HARQ disabled, the terminal device preferentially determines the target contention window value based on the transmission status of a TB having feedback information within the TB whose cast type is HARQ enabled. The cast type of a TB being HARQ enabled is equivalent to the cast type of the TB being one of multicast 2, multicast 1, and unicast.

[0239] In the above description of FIG. 5, the terminal device receives feedback information of TB#2 and feedback information of TB#3, so the terminal device may determine TB#2 and TB#3 as the second TB.

[0240] Optionally, the second TB satisfies multiple conditions among Condition #A to Condition #J.

[0241] For example, the second TB satisfies condition #A and condition #D. In the above description of Figure 5, both the initial transmission and retransmission of TB #2 within the reference period are completed, the feedback information of the last retransmission of TB #2 is NACK, and the cast type of TB #2 is the same as the cast type of one TB among the TBs to be transmitted. Therefore, TB #2 satisfies condition #A and condition #D, and the terminal device may determine TB #2 as the second TB.

[0242] In another example, the second TB satisfies condition #C and condition #D. When the second TB satisfies condition #C and condition #D, the second TB is a TB among the TBs in the reference period whose cast type is ranked first and is the same as the cast type of at least one TB to be transmitted. In the above description of FIG. 5, the cast type of TB #1 in the reference period is the same as the cast type of the TB among the TBs to be transmitted, and the cast type of TB #2 is the same as the cast type of the TB among the TBs to be transmitted. If unicast is ranked before HARQ disabled, the terminal device determines TB #2 as the second TB.

[0243] In another example, the second TB satisfies condition #D and condition #F. When the second TB satisfies condition #D and condition #F, the second TB is a TB among the TBs in the reference period, whose corresponding transmission priority is the same as the transmission priority corresponding to the TB to be transmitted, and whose cast type is the same as the cast type of at least one TB among the TBs to be transmitted. In the above description of Figure 5, if the CAPC of the transmission corresponding to the TB to be transmitted is 3, the CAPC of the transmission corresponding to TB#2 in the reference period is 3, and the cast type of TB#2 is the same as the cast type of the TB among the TBs to be transmitted, the terminal device may determine TB#2 as the second TB.

[0244] In another example, the second TB satisfies condition #E and condition #J. When the second TB satisfies condition #E and condition #I, the second TB is a TB within the TBs in the reference period for which feedback information is received by the terminal device and whose corresponding transmission priority is the same as the transmission priority corresponding to the TB to be transmitted. In the above description of Figure 5, the CAPC corresponding to the TB to be transmitted is 3, the CAPC of the transmission corresponding to TB#2 in the reference period is 3, and the terminal device receives feedback information for TB#2. Therefore, the terminal device may determine TB#2 as the second TB.

[0245] Please note that the above only lists some examples in which the second TB satisfies two of conditions #A to #J. The specific conditions and the number of conditions that the second TB satisfies are not limited in this embodiment of the present application. For example, the second TB may satisfy conditions #A, #D, and #E.

[0246] If the cast type of the second TB determined by the terminal device is the same as the cast type of at least one TB in the TB to be transmitted, it can be understood that the second TB is the same as the first TB described above.

[0247] After the terminal device determines the second TB based on one or more of conditions #A to #J, the terminal device may determine a target contention window value based on the transmission status of the second TB.

[0248] For example, if the terminal device determines one second TB, the terminal device determines the target contention window value based on the transmission status of the second TB.

[0249] For example, if the cast type of the second TB is HARQ enabled and the terminal device receives feedback information for the second TB, the terminal device may determine a target contention window value based on the feedback information for the second TB. For example, if the feedback information for the second TB is an ACK, the terminal device may determine the target contention window value as the minimum value within the target value range. If the feedback information for the second TB is a NACK, the terminal device may determine the target contention window value as a value within the target value range that is greater than the contention window value of the first COT. The target value range is a value range of the contention window value corresponding to the transmission priority corresponding to the TB to be transmitted. For example, if the CAPC of the transmission corresponding to the TB to be transmitted is 2, the target value range is {7, 15} according to Table 1. The contention window value of the first COT is a contention window value used when the terminal device acquires the first COT.

[0250] For example, if the contention window value of the first COT is 4 and the CAPC of the transmission corresponding to the TB to be transmitted is 2, when the feedback information of the second TB is ACK, the terminal device may determine the target contention window value as 7, and when the feedback information of the second TB is NACK, the terminal device may determine the target contention window value as 15.

[0251] In another example, if the cast type of the second TB is HARQ enabled and the terminal device has not received feedback information for the second TB, the terminal device may determine that the contention window value is kept unchanged, i.e., the terminal device determines the contention window value of the first COT as the target contention window value. Alternatively, if the cast type of the second TB is HARQ enabled and the terminal device has not received feedback information for the second TB, the terminal device may determine the target contention window value based on the proportion of retransmitted TBs within the TBs to be transmitted.

[0252] The terminal device not receiving the feedback information of the second TB includes the following two cases: the terminal device not receiving the feedback information of the second TB in a slot in which the terminal device is expected to receive the feedback information of the second TB; and the terminal device not receiving the feedback information of the second TB at the time when the terminal device determines the target contention window value, i.e., the time when the terminal device determines the target contention window value is earlier than the time when the terminal device receives or processes the feedback information of the second TB.

[0253] In another example, if the cast type of the second TB is HARQ disabled, the terminal device determines the target contention window value based on the number or percentage of blind transmissions of the second TB. For example, if the number or percentage of blind transmissions of the second TB exceeds preset threshold #1, the terminal device may determine the target contention window value as a value within the target value range that is greater than the contention window value of the first COT. If the number or percentage of blind transmissions of the second TB is less than preset threshold #1, the terminal device may determine the target contention window value as the minimum value within the target value range.

[0254] It should be noted that the above describes, using an example, how the terminal device determines the target contention window value based on the transmission status of one second TB. This is not limited to this embodiment of the present application. The method by which the terminal device determines the target contention window value based on the transmission status of one second TB may be another method. For example, if the cast type of the second TB is HARQ disabled, the terminal device may determine the contention window value of the first COT as the target contention window value.

[0255] For example, if the terminal device determines M second TBs, the terminal device may determine the target contention window value based on the transmission status of one of the M second TBs, where M is an integer greater than 1.

[0256] For example, the terminal device may determine the target contention window value based on the transmission status of the last-transmitted second TB among the M second TBs, or alternatively, the terminal device may determine the target contention window value based on the transmission status of the first-transmitted second TB among the M second TBs.

[0257] For example, if the terminal device determines M second TBs, the terminal device may determine a target contention window value based on the transmission statuses of the M second TBs. Methods for the terminal device to determine a target contention window value based on the transmission statuses of the M second TBs include the following methods.

[0258] Method 1: The terminal device determines N candidate conflict window values ​​based on the transmission statuses of the M second TBs, and further determines a target conflict window value based on the N candidate conflict window values. The target conflict window value is the maximum value among the N candidate conflict window values, the target conflict window value is the minimum value among the N candidate conflict window values, the target conflict window value is the candidate conflict window value among the N candidate conflict window values ​​that is greater than the average value of the N candidate conflict window values ​​and has the smallest difference from the average value, or the target conflict window value is the candidate conflict window value among the N candidate conflict window values ​​that has the smallest absolute difference from the average value of the N candidate conflict window values, where N is a positive integer and N≦M.

[0259] The method for the terminal device to determine the N candidate contention window values ​​based on the transmission statuses of the M second TBs includes the following several methods.

[0260] Method A: The terminal device determines one candidate contention window value based on the transmission status of each of the M second TBs, thereby allowing the terminal device to determine a total of M candidate contention window values. For example, if the M second TBs include TB#A and TB#B, the terminal device may determine a candidate contention window value based on the transmission status of TB#A, and then determine a candidate contention window value based on the transmission status of TB#B.

[0261] Method B: The terminal device determines candidate contention window values ​​based on the transmission statuses of second TBs having the same cast type among the M second TBs, so that the number of candidate contention window values ​​determined by the terminal device is the same as the number of cast types corresponding to the M second TBs. For example, the M second TBs include TB#A, TB#B, and TB#C, where TB#A and TB#B have the same cast type and TB#C has a different cast type from TB#A and TB#B. In this case, the terminal device may determine candidate contention window values ​​based on the transmission statuses of TB#A and TB#B, and then determine candidate contention window values ​​based on the transmission status of TB#C.

[0262] If the M second TBs include multiple second TBs having the same cast type, for a method in which a terminal device determines a candidate contention window value based on multiple second TBs having the same cast type, see Method 1 above, or see Method 2 or Method 3 below.

[0263] Method 2: The terminal device collects statistics on the feedback information of the M second TBs, and further, the terminal device determines a target contention window value based on the feedback information of the M second TBs.

[0264] For example, the terminal device collects statistics on the feedback information of M second TBs in the following manner: if the cast type of the TB is unicast, collect statistics on the feedback information of the initial transmission of the TB and the feedback information of each retransmission, collect statistics on the ACK feedback information of the TB, or collect statistics on the feedback information of the last retransmission of the TB; if the cast type of the TB is multicast 1 and the feedback information of the TB is NACK, indicate the number of feedback information of the TB as 1; if the cast type of the TB is multicast 2 and the feedback information of the TB is not NACK, indicate the feedback information of the TB as ACK; and indicate the number of feedback information of the TB as 1, L, or L-1, where L is the number of terminal devices included in the terminal device group configured to receive the TB, or if the cast type of the TB is multicast 2, collect statistics on each of the feedback information of the TB.

[0265] It should be noted that if the cast type of the TB is HARQ disabled, the terminal device does not receive feedback information of the TB, and the terminal device does not collect statistics on the feedback information of the TB whose cast type is HARQ disabled.

[0266] It is further noted that if the cast type of the TB is multicast 1 or multicast 2, the terminal device may collect statistics regarding feedback information of the initial transmission of the TB and / or feedback information of each retransmission of the TB, collect statistics regarding feedback information of the last retransmission of the TB, collect statistics regarding feedback information that is not a NACK regarding the TB, or collect statistics regarding feedback information that is not an ACK regarding the TB.

[0267] For example, assume that the M second TBs include TB#A, TB#B, and TB#C. The cast type of TB#A is unicast, the reference period includes the initial transmission and first retransmission of TB#A, the feedback information of TB#A's initial transmission is a NACK, and the feedback information of TB#A's retransmission is an ACK. The cast type of TB#B is multicast 1, the reference period includes TB#B's initial transmission, and the feedback information of TB#B's initial transmission is not a NACK. The cast type of TB#C is multicast 2, the reference period includes TB#C's initial transmission, and the feedback information of TB#C's initial transmission includes S ACKs and T NACKs, where both S and T are integers greater than or equal to 0.

[0268] When the terminal device collects statistics on feedback information for each transmission of TB#A, the terminal device collects statistics on two pieces of feedback information for TB#A in total, one piece of feedback information is an ACK and the other piece of feedback information is a NACK. Regarding TB#B, if the number of terminal devices included in the terminal device group configured to receive TB#B is L1, the terminal device may indicate the feedback information of TB#B as an ACK and the number of ACKs as L1-1. Regarding TB#C, the terminal device counts the number of ACKs of TB#C as S and the number of NACKs of TB#C as T. Furthermore, the terminal device counts the number of feedback information of M second TBs as (S+T+L1+1), where the number of ACKs is (L1+S) and the number of NACKs is (T+1).

[0269] It should be noted that in the above example, the terminal device collects statistics on feedback information for each transmission of TB#A. In a specific embodiment, the terminal device may collect statistics on feedback information for each transmission of a TB whose cast type is unicast, or the terminal device may collect statistics on ACK feedback information for a TB whose cast type is unicast, or may collect statistics on feedback information for the last retransmission. This is not limited to this embodiment of the present application. In other words, the terminal device collects statistics on feedback information for a TB whose cast type is unicast once.

[0270] After collecting statistics on the feedback information of the M second TBs, the terminal device may determine a target contention window value based on the statistical results. For example, if the proportion of ACKs in the feedback information of the M second TBs exceeds preset threshold #2, the terminal device may determine that the target contention window value is the minimum value within the target value range. If the proportion of ACKs in the feedback information of the M second TBs is less than preset threshold #2, the terminal device may determine that the target contention window value is a value within the target value range that is greater than the contention window value of the first COT. In another example, if the proportion of NACKs in the feedback information of the M second TBs exceeds preset threshold #3, the terminal device may determine that the target contention window value is a value within the target value range that is greater than the contention window value of the first COT. If the proportion of NACKs in the feedback information of the M second TBs is less than preset threshold #3, the terminal device may determine that the target contention window value is the minimum value within the target value range.

[0271] It should be noted that if the terminal device has not obtained feedback information of the M second TBs through statistics collection, in other words, if the terminal device has not received feedback information of a TB among the M second TBs whose cast type is HARQ-enabled, the terminal device may determine that the contention window value is maintained unchanged. That is, the terminal device determines the contention window value of the first COT as the target contention window value. Alternatively, if the terminal device has not obtained feedback information of the M second TBs through statistics collection, the terminal device may determine the target contention window value based on the proportion of retransmitted TBs among the TBs to be transmitted.

[0272] Method 3: The terminal device sequentially updates the contention window value based on the transmission statuses of the M second TBs according to the transmission sequence of the M second TBs or the sequence of receiving feedback information of the M second TBs until a target contention window value is determined.

[0273] Specifically, according to the transmission sequence of M second TBs or the sequence of receiving feedback information of the M second TBs, the terminal device determines a first intermediate contention window value based on the transmission status of the first second TB among the M second TBs, then determines a second intermediate contention window value based on the transmission status of the second second TB among the M second TBs and the first intermediate contention window value, ..., finally determines a target contention window value based on the transmission status of the Mth second TB among the M second TBs and the (M-1)th intermediate contention window value.

[0274] For example, the M second TBs include TB#A, TB#B, and TB#C, and TB#A to TB#C are ranked in the transmission sequence as follows: TB#A, TB#B, and TB#C. Assuming that the contention window value of the first COT is 31, the CAPC of the transmission corresponding to the TB to be transmitted is 3, and the feedback information of TB#A is ACK, the terminal device may determine the first intermediate contention window value as 15. Furthermore, if the feedback information of TB#B is NACK, the terminal device may determine the second intermediate contention window value as a value greater than 15, for example, 31. Furthermore, if the feedback information of TB#C is NACK, the terminal device may determine the target contention window value as a value greater than 31, for example, 63.

[0275] In another possible implementation, the terminal device may determine the target contention window value based on the transmission status of at least one TB within the reference period.

[0276] For example, the at least one TB may include one TB. For example, the terminal device may determine the target contention window value based on the transmission status of the last transmitted TB within the reference period. For how the terminal device determines the target contention window value based on the transmission status of at least one TB within the reference period, please refer to the above-described method in which the terminal device determines the target contention window value based on the transmission status of one second TB.

[0277] For example, the at least one TB may include multiple TBs. For example, the terminal device may determine the target contention window value based on the transmission statuses of all or multiple TBs within the reference period. When the at least one TB includes multiple TBs, for how the terminal device determines the target contention window value based on the transmission status of at least one TB within the reference period, please refer to the above-described method in which the terminal device determines the target contention window value based on the transmission statuses of M second TBs.

[0278] For example, see Method 1 above. The terminal device may determine at least one candidate conflict window value based on the transmission status of at least one TB, and the terminal device determines a target conflict window value based on the at least one candidate conflict window value. The target conflict window value is the maximum value among the at least one candidate conflict window value, the target conflict window value is the minimum value among the at least one candidate conflict window value, the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that is greater than the average value of the at least one candidate conflict window value and has the smallest difference from the average value, or the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value that has the smallest absolute difference from the average value of the at least one candidate conflict window value.

[0279] For example, see the above-mentioned Method 2. The terminal device may collect statistics regarding the feedback information of the at least one TB, and the terminal device determines a target contention window value based on the feedback information of the at least one TB.

[0280] 6, the reference period includes TB#A whose cast type is HARQ disabled, TB#B whose cast type is unicast, and TB#C whose cast type is multicast 2. In this case, the terminal device collects statistics on the feedback information of TB#B and TB#C and determines a target contention window value based on the feedback information of TB#B and TB#C. For example, the terminal device determines the target contention window value based on the ACK rate and / or NACK rate of the feedback information of TB#B and TB#C.

[0281] For the method in which the terminal device collects statistics on the feedback information of at least one TB, please refer to the above-mentioned method in which the terminal device collects statistics on the feedback information of M second TBs.

[0282] For example, see the above-mentioned Method 3. The terminal device sequentially updates the contention window value based on the transmission status of the at least one TB according to the transmission sequence of the at least one TB or the sequence of receiving feedback information of the at least one TB, until a target contention window value is determined.

[0283] In another possible embodiment, if the reference period includes at least one transmitted TB, and the at least one transmitted TB is the last transmitted TB after the last updated contention window value, the terminal device determines the target contention window value based on the transmission status of the last transmitted TB.

[0284] For example, if the cast type of the last transmitted TB is HARQ enabled, the terminal device determines the target contention window value based on the feedback information of the last transmitted TB. For example, if the reference period includes the last retransmission of the last transmitted TB and the feedback information of the last retransmission is a NACK, the terminal device may determine that the target contention window value is a value within the target value range that is greater than the contention window value of the first COT. For example, if the reference period includes the initial transmission of the last transmitted TB and the feedback information of the initial transmission is an ACK, the terminal device may determine that the target contention window value is the minimum value within the target value range.

[0285] For example, if the cast type of the last transmitted TB is HARQ disabled, the terminal device may determine the target contention window value based on the number or percentage of blind transmissions of the last transmitted TB. For example, if the number or percentage of blind transmissions of the last transmitted TB exceeds preset threshold #1, the terminal device may determine the target contention window value as a value within the target value range that is greater than the contention window value of the first COT. If the number or percentage of blind transmissions of the last transmitted TB is less than preset threshold #1, the terminal device may determine the target contention window value as the minimum value within the target value range.

[0286] In another possible implementation, if the first COT is the COT closest to the current time, the terminal device may determine the target contention window value based on the transmission status of the last transmitted TB within the reference period.

[0287] For example, if the terminal device has not received feedback information of the last transmitted TB, the terminal device may determine that the contention window value is kept unchanged, i.e., the terminal device may determine the contention window value of the first COT as the target contention window value. Alternatively, if the terminal device has not received feedback information of the last transmitted TB, the terminal device may determine the target contention window value based on the proportion of retransmitted TBs among the TBs to be transmitted.

[0288] The terminal device not receiving the feedback information of the last transmitted TB includes the following two cases: the terminal device does not receive the feedback information of the last transmitted TB in the slot in which the terminal device is expected to receive the feedback information of the last transmitted TB; and the terminal device does not receive the feedback information of the last transmitted TB at the time when the terminal device determines the target contention window value, i.e., the time when the terminal device determines the target contention window value is earlier than the time when the terminal device receives or processes the feedback information of the last transmitted TB.

[0289] It can be understood that when the terminal device does not receive feedback information of a TB, this TB may be considered as a TB whose transmission has not been completed.

[0290] For example, when the terminal device receives feedback information of the last transmitted TB, the terminal device determines the target contention window value based on the feedback information of the last transmitted TB.

[0291] For example, as shown in Figure 7, the reference period determined by the terminal device includes the last transmitted TB, i.e., the TB whose cast type is multicast 2 shown in Figure 7, and the terminal device receives feedback information of the TB whose cast type is multicast 2. In this case, the terminal device may determine the target contention window value based on the feedback information of the TB whose cast type is multicast 2.

[0292] After determining the target contention window value, the terminal device may preempt the channel of the TB to be transmitted based on the target contention window value. For example, the terminal device may generate a random number N based on the target contention window value. init Determine the random number N initThe value of ranges from 0 to (including) the target contention window value. The number of slots in which the end device senses the channel is idle is N. init , the terminal device preempts the channel of the TB to be transmitted, so that the terminal device can transmit the TB to be transmitted.

[0293] In this embodiment of the present application, the terminal device may determine an appropriate contention window value based on the transmission status of at least one TB within the reference period to avoid mutual collisions between different devices and improve system transmission efficiency. For example, if at least one TB within the reference period is successfully transmitted, the terminal device may determine a small contention window value to shorten the LBT period and improve channel access efficiency. If at least one TB within the reference period fails to transmit, the terminal device may determine a large contention window value to extend the LBT period and reduce the possibility of the terminal device colliding with another surrounding device.

[0294] In addition, even if the cast type of a TB in the COT to which the reference period belongs is different from the cast type of the TB to be transmitted, even if the TB in the COT to which the reference period belongs corresponds to at least two cast types, or even if the TB to be transmitted corresponds to at least two cast types, according to this embodiment of the present application, the reference period can be determined and a contention window value can be determined based on the transmission status of at least one TB in the reference period.

[0295] 8 is a schematic flowchart of a conflict window value determination method 800 according to an embodiment of the present application. The method 800 may include the following steps:

[0296] S810: The terminal device determines a reference period corresponding to each of the at least one cast type.

[0297] The at least one cast type is the cast type of at least one TB in the TB to be transmitted.

[0298] For example, the at least one cast type may be the cast type of the TB having the lowest transmission priority among the TBs to be transmitted.

[0299] In another example, the at least one cast type may include all cast types corresponding to the TB to be transmitted.

[0300] As shown in Figure 9, the TB to be transmitted includes two TBs, one of which has a cast type of unicast and the other of which has a cast type of multicast 2. The CAPC of the transmission corresponding to the TB whose cast type is unicast is 2, and the CAPC of the transmission corresponding to the TB whose cast type is multicast 2 is 3.

[0301] In a possible embodiment, the at least one cast type includes all possible cast types. For example, if the at least one cast type includes unicast, multicast 1, multicast 2, and HARQ disabled, the terminal device determines a reference period corresponding to unicast, a reference period corresponding to multicast 1, a reference period corresponding to multicast 2, and a reference period corresponding to HARQ disabled.

[0302] If the at least one cast type is the cast type of a TB corresponding to the lowest transmission priority among the TBs to be transmitted, the terminal device may determine that the at least one cast type is multicast 2. Further, in S810, the terminal device determines reference period #1 corresponding to multicast 2.

[0303] If the at least one cast type includes all cast types corresponding to the TB to be transmitted, the terminal device may determine that the at least one cast type includes multicast 2 and unicast. Further, in S810, the terminal device determines reference period #1 corresponding to unicast and determines reference period #2 corresponding to multicast 2.

[0304] The cast type of the TB in the reference period determined by the terminal device for each cast type is the same as the cast type corresponding to the reference period. For example, as shown in Figure 9, the cast type of the TB in reference period #2 determined by the terminal device for multicast 2 is multicast 2, and the cast type of the TB in reference period #1 determined by the terminal device for unicast is unicast.

[0305] Note that the reference periods determined by the terminal device for all cast types may be continuous or discontinuous. As shown in (a) of FIG. 9, the reference period #2 determined by the terminal device for multicast 2 is continuous, and the reference period #1 determined for unicast is discontinuous. Specifically, reference period #1 includes a TB whose cast type is unicast, but does not include a TB whose cast type is HARQ disabled between two TBs whose cast type is unicast. Furthermore, as shown in (b) of FIG. 9, the reference period #1 determined by the terminal device for unicast is continuous, and the reference period #2 determined for multicast 2 is also continuous.

[0306] The priority of the COT to which each reference period determined by the terminal device belongs is the same as the transmission priority corresponding to the TB to be transmitted. For the definition of the priority of the COT and the definition of the transmission priority corresponding to the TB to be transmitted, please refer to the above description of S210.

[0307] For example, the TBs in the COT to which each reference period belongs correspond to at least two cast types, or the TBs to be transmitted correspond to at least two cast types.

[0308] The following uses cast type #1 of at least one cast type as an example to explain other characteristics that may be of the reference period determined by the terminal device for cast type #1. For ease of explanation, the COT to which the reference period corresponding to cast type #1 belongs is denoted as the second COT.

[0309] For example, the reference period corresponding to cast type #1 includes TBs whose cast type is cast type #1.

[0310] Optionally, after the last updated contention window value, if the terminal device may determine multiple candidate reference periods including a TB whose cast type is cast type #1, the reference period finally determined by the terminal device may be the candidate reference period among the multiple candidate reference periods that is closest to the current time, and the priority of the COT to which the candidate reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted.

[0311] In other words, the second COT is the closest COT to the current time that contains a TB that has the same transmission priority as the TB to be transmitted and whose cast type is Cast Type #1.

[0312] It should be noted that a TB whose cast type is Cast Type #1 and that is included in the reference period may be a transmitted TB or a TB whose transmission has not been completed. This is not a limitation in this application. For example, a TB whose cast type is Cast Type #1 and that is included in the reference period is the last transmitted TB whose cast type is Cast Type #1.

[0313] For example, a reference period corresponding to cast type #1 includes at least one transmitted TB whose cast type is cast type #1.

[0314] Optionally, if, after the last updated contention window value, the terminal device may determine multiple candidate reference periods that include a transmitted TB whose cast type is cast type #1, the reference period finally determined by the terminal device may be the candidate reference period among the multiple candidate reference periods that is closest to the current time, and the priority of the COT to which the candidate reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted.

[0315] In other words, the second COT is the closest COT to the current time that contains at least one transmitted TB that has the same transmission priority as the TB to be transmitted and whose cast type is Cast Type #1.

[0316] Optionally, if there are no transmitted TBs whose cast type is cast type #1 after the last updated contention window value, the reference period corresponding to cast type #1 includes the last transmitted TB whose cast type is cast type #1.

[0317] Optionally, the terminal device may first determine the second COT, and then determine the reference period based on the second COT to which the reference period belongs. The following describes how the terminal device determines the first COT.

[0318] For example, the second COT is the COT that has the same transmission priority as the TB to be transmitted, includes a TB whose cast type is cast type #1, and is closest to the current time. In other words, the terminal device may determine as the second COT a COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted in the transmitted COT after the last updated contention window value, which COT includes a TB whose cast type is cast type #1 and is closest to the current time. In this way, the terminal device may determine the reference period corresponding to cast type #1 based on the second COT.

[0319] Optionally, the second COT is the COT closest to the current time, which has the same transmission priority as the TB to be transmitted and includes at least one transmitted TB whose cast type is cast type #1. In other words, the terminal device may determine as the second COT a COT whose priority is the same as the transmission priority corresponding to the TB to be transmitted in the transmitted COT after the last updated contention window value, the COT including at least one transmitted TB, and the cast type of the at least one transmitted TB is cast type #1. In this way, the terminal device may determine the reference period corresponding to cast type #1 based on the second COT.

[0320] For the definition that the reference period or second COT includes one transmitted TB, see the above description of S210.

[0321] The following describes the relationship between the reference period corresponding to Cast Type #1 and the second COT.

[0322] For example, the reference period corresponding to cast type #1 includes all TBs whose cast type is cast type #1 in the second COT. In other words, the start time of cast type #1 is the start time of the first transmitted TB whose cast type is cast type #1 in the second COT, and the end time of cast type #1 is the end time of the last transmitted TB whose cast type is cast type #1 in the second COT. As shown in Figure 9, reference period #1 includes all TBs whose cast type is unicast in the COT to which reference period #1 belongs, and reference period #2 includes all TBs whose cast type is multicast 2 in the COT to which reference period #2 belongs. As shown in (a) of Figure 9, reference period #1 includes slots 1 and 3 for transmitting TBs whose cast type is unicast, and reference period #2 includes slots 5 and 6 for transmitting TBs whose cast type is multicast 2. As shown in (b) of Figure 9, reference period #1 includes slots 1 and 2 for transmitting TBs whose cast type is unicast, and reference period #2 includes slots 5 and 6 for transmitting TBs whose cast type is multicast 2.

[0323] For example, the reference period corresponding to cast type #1 includes the last-transmitted TB in the second COT whose cast type is cast type #1. For example, if the second COT includes two TBs, namely TB#a and TB#b, whose cast type is cast type #1, TB#b is the last-transmitted TB, and the reference period corresponding to cast type #1 includes TB#b. In other words, the start of the reference period corresponding to cast type #1 is the start of the transmission of TB#b, and the end of the reference period corresponding to cast type #1 is the end of the transmission of TB#b. As shown in FIG. 9, reference period #1 is used as an example. Reference period #1 includes the second TB shown in FIG. 9 whose cast type is unicast. Specifically, reference period #1 includes slot 3 shown in FIG. 9(a) for transmitting a TB whose cast type is unicast, or reference period #1 includes slot 2 shown in FIG. 9(b) for transmitting a TB whose cast type is unicast.

[0324] For example, the reference period corresponding to cast type #1 includes the transmitted TB in the second COT whose cast type is cast type #1. For example, if the second COT includes two TBs, namely TB#a and TB#b, whose cast type is cast type #1, TB#b is a transmitted TB, and the reference period corresponding to cast type #1 includes TB#b. In other words, the start of the reference period corresponding to cast type #1 is the start of the transmission of TB#b, and the end of the reference period corresponding to cast type #1 is the end of the transmission of TB#b. As shown in Figure 9, reference period #1 is used as an example. If the second TB shown in Figure 9 whose cast type is unicast is the transmitted TB, reference period #1 includes the second TB shown in Figure 9 whose cast type is unicast. Specifically, reference period #1 includes slot 3 shown in (a) of Figure 9 for transmitting a TB whose cast type is unicast, or reference period #1 includes slot 2 shown in (b) of Figure 9 for transmitting a TB whose cast type is unicast.

[0325] For example, the reference period corresponding to cast type #1 includes a TB having feedback information and whose cast type is cast type #1 in the second COT. For example, if the second COT includes two TBs, namely TB#a and TB#b, whose cast type is cast type #1, and the terminal device receives feedback information for TB#a but not for TB#b, the reference period corresponding to cast type #1 includes TB#a. In other words, the start point of the reference period corresponding to cast type #1 is the start point of transmission of TB#a, and the end point of the reference period corresponding to cast type #1 is the end point of transmission of TB#a. As shown in FIG. 9, reference period #1 is used as an example. If the terminal device receives feedback information for the first TB shown in FIG. 9, whose cast type is unicast, reference period #1 includes the first TB shown in FIG. 9, whose cast type is unicast. Specifically, reference period #1 includes slot 1 shown in (a) of Figure 9 for transmitting a TB whose cast type is unicast, or reference period #1 includes slot 1 shown in (b) of Figure 9 for transmitting a TB whose cast type is unicast.

[0326] For example, the reference period corresponding to cast type #1 includes the first or last transmitted TB having feedback information in the second COT, whose cast type is cast type #1. For example, if the second COT includes two TBs, namely TB#a and TB#b, whose cast type is cast type #1, and the terminal device receives feedback information for TB#a and TB#b, the reference period corresponding to cast type #1 includes the first transmitted TB#a, or the reference period corresponding to cast type #1 includes the last transmitted TB#b.

[0327] For example, the reference period corresponding to cast type #1 includes the first transmission slot of the TB whose cast type is cast type #1 in the second COT that was transmitted first and has feedback information. For example, if the second COT includes two TBs, namely TB#a and TB#b, whose cast type is cast type #1, and the terminal device receives feedback information for TB#a and TB#b, the reference period corresponding to cast type #1 includes the first transmission slot of TB#a that was transmitted first. For example, the start of the reference period corresponding to cast type #1 is the start of the COT to which the reference period belongs, and the end of the reference period corresponding to cast type #1 is the end of the first transmission slot of TB#a.

[0328] It should be noted that when the terminal device determines a reference period corresponding to each of multiple cast types, the reference periods corresponding to different cast types may belong to the same COT or different COTs, which is not limited in this embodiment of the present application.

[0329] Optionally, before S810, the method 800 further includes the terminal device determining that the TBs in the transmitted COT after the last updated contention window value correspond to at least two cast types.

[0330] In other words, if the terminal device determines that the TBs in the transmitted COT after the last updated contention window value correspond to at least two cast types, the terminal device determines the reference period according to the method described in S810.

[0331] Optionally, before S810, the method 800 further includes: the terminal device determining that the TB to be transmitted corresponds to at least two cast types.

[0332] In other words, if the terminal device determines that the TB to be transmitted corresponds to at least two cast types, the terminal device determines the reference period according to the method described in S810.

[0333] It should be noted that if the terminal device determines that there is no TB whose cast type is the same as the cast type of the TB to be transmitted after the last updated contention window value, the terminal device may determine a reference period and determine a target contention window value according to the above-described method 200.

[0334] S820: The terminal device determines a target contention window value based on the transmission status of the TB within the reference period corresponding to each cast type.

[0335] The target contention window value is for preempting the channel for TBs to be transmitted.

[0336] In a possible embodiment, if the at least one cast type includes one cast type, the terminal device determines one reference period. Further, the terminal device may determine a target contention window value based on the transmission status of the TB within the reference period.

[0337] If the reference period includes one TB, for how the terminal device determines the target contention window value based on the transmission status of the TB within the reference period, please refer to the method for how the terminal device determines the target contention window value based on the transmission status of the second TB described in S220.

[0338] If the reference period includes multiple TBs, for how the terminal device determines the target contention window value based on the transmission status of the TBs within the reference period, please refer to the method for the terminal device determining the target contention window value based on the transmission status of M second TBs described in S220.

[0339] In another possible implementation, when the at least one cast type includes a plurality of cast types, a method for the terminal device to determine a target conflict window value based on a transmission status of a TB in a reference period corresponding to each cast type includes: the terminal device determining at least one candidate conflict window value based on a transmission status of a TB in a reference period corresponding to each of the at least one cast type; and then the terminal device determining a target conflict window value based on the at least one candidate conflict window value.

[0340] The target conflict window value is the maximum value among the at least one candidate conflict window value; the target conflict window value is the minimum value among the at least one candidate conflict window value; the target conflict window value is the candidate conflict window value among the at least one candidate conflict window value that is greater than the average value of the at least one candidate conflict window value and has the smallest difference from the average value; or the target conflict window value is the candidate conflict window value among the at least one candidate conflict window value that has the smallest absolute difference from the average value of the at least one candidate conflict window value.

[0341] 9, when the terminal device determines Reference Period #1 corresponding to unicast and Reference Period #2 corresponding to multicast 2, the terminal device determines a candidate contention window value based on the transmission status of the TB in Reference Period #1, and determines a candidate contention window value based on the transmission status of the TB in Reference Period #2. Furthermore, the terminal device determines a target contention window value based on the two candidate contention window values.

[0342] When the terminal device determines multiple reference periods, one of which includes one TB, for a method for the terminal device to determine a candidate contention window value based on the transmission status of the TB within the reference period, please refer to the method for the terminal device to determine a target contention window value based on the transmission status of one second TB described in S220.

[0343] When the terminal device determines one reference period and the one reference period includes multiple TBs, for how the terminal device determines a candidate contention window value based on the transmission status of the TBs within the reference period, please refer to the method for the terminal device determining a target contention window value based on the transmission status of M second TBs described in S220.

[0344] After determining the target contention window value, the terminal device may preempt the channel of the TB to be transmitted based on the target contention window value. For example, the terminal device may generate a random number N based on the target contention window value. init Determine the random number N init The value of ranges from 0 to (including) the target contention window value. The number of slots in which the end device senses the channel is idle is N. init , the terminal device preempts the channel of the TB to be transmitted, so that the terminal device can transmit the TB to be transmitted.

[0345] In this embodiment of the present application, even if the TB in the COT to which the reference period belongs corresponds to at least two cast types, or even if the TB to be transmitted corresponds to at least two cast types, the terminal device can determine the reference period corresponding to each of at least one cast type and determine the contention window value according to the transmission status of the TB in the reference period, which is helpful in determining an appropriate contention window value to avoid mutual collisions between different devices and improve system transmission efficiency.

[0346] In a possible embodiment, the reference period may be determined in the following manner, where the reference period is within the COT, the start of the reference period is the start of the COT to which the reference period belongs, and the end of the reference period is the end of the first slot in the COT to which the reference period belongs that satisfies the following condition: at least one hybrid automatic repeat request acknowledgment enabled (HARQ-ACK enabled) PSSCH is transmitted or at least one acknowledgment / negative acknowledgement hybrid automatic repeat request acknowledgment enabled (ACK / NACK HARQ-ACK enabled) PSSCH is transmitted. It should be understood that the at least one HARQ-ACK enabled PSSCH or ACK / NACK HARQ-ACK enabled PSSCH is a PSSCH transmitted by the terminal device that initializes the COT (the terminal device that is attempting to adjust the contention window value).

[0347] However, when the contention window value is adjusted based on the reference period, the following problem may exist: before the end of the reference period, if only one HARQ-ACK enabled PSSCH or ACK / NACK HARQ-ACK enabled PSSCH is transmitted, and the PSFCH of the PSSCH is not successfully transmitted by the receiving terminal device of the PSSCH due to a transmission-reception conflict or a transmission-transmission conflict of the PSFCH, the HARQ of the PSSCH cannot be detected by the transmitting terminal device of the PSSCH (i.e., the terminal device that initializes the COT). As a result, the transmitting terminal device does not have enough information to determine how to adjust the contention window value.

[0348] It should be understood that the PSFCH carries HARQ information indicating whether the corresponding PSSCH has been successfully received. Therefore, the receiving terminal device of the PSSCH is the transmitting terminal device of the PSFCH, and the transmitting terminal device of the PSSCH is the receiving terminal device of the PSFCH.

[0349] As shown in Figure 10, UE1 is expected to determine how to adjust the contention window value based on the HARQ of the PSSCH in the reference period. In the reference period determined by UE1, the PSSCH sent by UE1 to UE3 is a HARQ-ACK enabled PSSCH or an ACK / NACK HARQ-ACK enabled PSSCH. The following describes two possible cases in which UE3 does not send a PSSCH to UE1.

[0350] In Case 1, a transmission-transmission conflict occurs in the PSFCH. Specifically, as shown in (a) of FIG. 10, UE3 receives PSFCHs from UE1 and UE2, and UE3 needs to transmit PSFCHs to UE1 and UE2 simultaneously. However, based on factors such as UE3's ability to simultaneously transmit PSFCHs and power control, UE3 may not be able to transmit two PSFCHs simultaneously and must discard some PSFCHs and not transmit these PSFCHs. According to the description in 3GPP technical specification (TS) 38.213, UE3 discards some PSFCHs with lower priorities and does not transmit these PSFCHs. Assuming that the PSFCH transmitted by UE3 to UE1 has a lower priority, UE3 does not transmit the PSFCH to UE1. The above case is referred to as UE3 not transmitting the PSFCH to UE1 due to a transmission-transmission conflict.

[0351] It should be understood that due to factors such as the limited ability of UE1 to simultaneously transmit PSFCHs and power control, the number of PSFCHs that UE1 ultimately decides to simultaneously transmit may be less than the number of PSFCHs that need to be simultaneously transmitted. For this part, please refer to the explanation in TS38.213 of 3GPP. Details will not be described in this application.

[0352] In Case 2, a transmission-reception conflict occurs in the PSFCH. Specifically, as shown in (b) of FIG. 10, UE3 receives a PSFCH from UE1 and transmits a PSFCH to UE2. The resource for UE3 to transmit the PSFCH to UE1 and the resource for UE3 to receive the PSFCH from UE2 are arranged in the same slot (i.e., UE3 needs to receive and transmit the PSFCH simultaneously). Due to half-duplex limitations, it is usually difficult for a terminal device to receive and transmit simultaneously. In this case, according to the description in TS38.213 of 3GPP, the terminal device only receives or transmits a PSFCH with a high priority. Assuming that the PSFCH that UE3 needs to transmit to UE1 has a low priority, UE3 chooses to receive the PSFCH from UE2 instead of transmitting the PSFCH to UE1. This case is referred to as UE3 not transmitting the PSFCH to UE1 due to a transmission-reception conflict.

[0353] Furthermore, in some cases, when a transmitting terminal device of a PSSCH does not detect a HARQ due to a transmission-reception conflict or a transmission-transmission conflict of a PSFCH, the transmitting terminal device may mistakenly believe that the HARQ detection has failed due to a failure to receive the PSSCH caused by a PSSCH collision. As a result, the transmitting terminal device blindly increases the contention window value. Referring to the above description of Type 1 LBT, when performing Type 1 LBT, the terminal device determines the value of the counter N based on the contention window value. A larger contention window value determined by the terminal device may indicate a larger value of the counter N determined based on the contention window value. When the value of counter N is larger, the period during which the terminal device performs Type 1 LBT is longer, i.e., the terminal device requires a longer period to access the channel. Therefore, when the terminal device blindly increases the contention window value, the probability that the transmitting terminal device will access the channel decreases.

[0354] In view of this, an embodiment of the present application further provides a conflict window value determination method, to determine an appropriate conflict window value.

[0355] 11 is a schematic flowchart of a conflict window value determination method 1100 according to an embodiment of the present application. The method 1100 may include the following steps:

[0356] S1110: The terminal device determines a reference period.

[0357] The terminal device is the terminal device that initializes the COT.

[0358] The reference period is within the COT (hereinafter referred to as COT#3, where COT is a COT initialized by the terminal device), the reference period includes a first PSSCH, the first PSSCH is a HARQ enabled PSSCH, and the HARQ corresponding to the first PSSCH is detected by the terminal device. The reference period including the first PSSCH means that the terminal device has completed transmission of the first PSSCH within the reference period.

[0359] For example, a HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, a HARQ-enabled multicast 1 PSSCH, or a HARQ-enabled multicast 2 PSSCH. In other words, a HARQ-enabled PSSCH is a HARQ-ACK enabled PSSCH.

[0360] In another example, the HARQ-enabled PSSCH includes one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH or a HARQ-enabled multicast2 PSSCH. In other words, the HARQ-enabled PSSCH is an ACK / NACK HARQ-ACK enabled PSSCH.

[0361] A HARQ-enabled unicast PSSCH is a PSSCH that satisfies the following conditions: the cast type of the PSSCH is unicast, and the control information associated with the PSSCH (e.g., the control information is secondary sidelink control information (SCI), or referred to as SCI-2) includes HARQ enablement indication information.

[0362] A HARQ-enabled multicast 1 PSSCH is a PSSCH that satisfies the following conditions: the cast type of the PSSCH is multicast 1, and the control information associated with the PSSCH (e.g., the control information is a secondary SCI, or referred to as SCI-2) includes HARQ enablement indication information.

[0363] A HARQ-enabled multicast 2 PSSCH is a PSSCH that satisfies the following conditions: the cast type of the PSSCH is multicast 2, and the control information associated with the PSSCH (e.g., the control information is a secondary SCI, or referred to as SCI-2) includes HARQ enablement indication information.

[0364] When the control information associated with the PSSCH (e.g., the control information is a secondary SCI, or called SCI-2) includes HARQ enablement indication information, the control information of the PSSCH indicates to the receiving device of the PSSCH to feed back the HARQ information of the PSSCH to the terminal device.

[0365] In the case of a HARQ-enabled PSSCH whose cast type is unicast, when the PSSCH is correctly received, the receiving device of the PSSCH feeds back ACK information to the terminal device. When the control information associated with the PSSCH (for example, the control information is a primary SCI or called SCI-1) is correctly received or when the PSSCH is not correctly received, the receiving device of the PSSCH feeds back NACK information to the terminal device. Alternatively, when the control information associated with the PSSCH (for example, the control information is a primary SCI or called SCI-1) is not correctly received, the receiving device of the PSSCH does not feed back HARQ to the terminal device.

[0366] In the case of a HARQ-enabled PSSCH whose cast type is multicast 1, when the control information associated with the PSSCH (for example, the control information is a primary SCI or called SCI-1) is correctly received but the PSSCH is not correctly received, the receiving device of the PSSCH feeds back NACK information to the terminal device; otherwise, the receiving device of the PSSCH does not feed back HARQ information.

[0367] The method of feeding back HARQ information of an HARQ-enabled PSSCH whose cast type is multicast 2 is the same as the method of feeding back HARQ information of an HARQ-enabled PSSCH whose cast type is unicast, and the details will not be described again here.

[0368] When the terminal device detects the HARQ corresponding to the first PSSCH, the terminal device can determine the reception status of the first PSSCH. Specifically, the terminal device can determine whether the first PSSCH has been received successfully or not.

[0369] For example, a terminal device detecting a HARQ corresponding to a HARQ-enabled unicast PSSCH means that the terminal device detects a PSFCH (denoted as PSFCH#1) corresponding to the HARQ-enabled unicast PSSCH, where PSFCH#1 carries ACK information or NACK information. It can be understood that after the terminal device receives PSFCH#1, if PSFCH#1 carries ACK information, the terminal device may determine that the HARQ-enabled unicast PSSCH has been successfully received, or if PSFCH#1 carries NACK information, the terminal device may determine that the HARQ-enabled unicast PSSCH has not been successfully received.

[0370] For example, a terminal device detecting a HARQ corresponding to the HARQ-enabled multicast 1 PSSCH means that the terminal device detects a PSFCH (denoted as PSFCH#2) corresponding to the HARQ-enabled multicast 1 PSSCH, and the PSFCH#2 carries NACK information, or a terminal device detecting a HARQ corresponding to the HARQ-enabled multicast 1 PSSCH means that the terminal device does not detect PSFCH#2. It can be understood that if the terminal device detects PSFCH#2, the terminal device may determine that the HARQ-enabled multicast 1 PSSCH was not successfully received, or if the terminal device does not detect PSFCH#2, the terminal device may determine that the HARQ-enabled multicast 1 PSSCH was successfully received.

[0371] For example, a terminal device detecting a HARQ corresponding to a HARQ-enabled multicast 2 PSSCH means that the terminal device detects a PSFCH (denoted as PSFCH#3) corresponding to the HARQ-enabled multicast 2 PSSCH, and the PSFCH#3 carries ACK information or NACK information. It can be understood that after the terminal device receives the PSFCH#3, if the PSFCH#3 carries ACK information, the terminal device may determine that the HARQ-enabled multicast 2 PSSCH has been successfully received, or if the PSFCH#3 carries NACK information, the terminal device may determine that the HARQ-enabled multicast 2 PSSCH has not been successfully received.

[0372] The time when the terminal device detects the HARQ corresponding to the first PSSCH is not limited in this embodiment of the present application. If the terminal device detects the HARQ corresponding to the first PSSCH before determining the target contention window value, the terminal device may detect the HARQ corresponding to the first PSSCH within COT#3, or the terminal device may detect the HARQ corresponding to the first PSSCH after COT#3.

[0373] The start time of the reference period is not limited in this embodiment of the present application, for example, the start time of the reference period is the start time of COT#3.

[0374] FIG. 12 is a diagram for determining the start point of a reference period within COT#3. As shown in FIG. 12, COT#3 includes slots 1 to 3. Slot 1 is for transmitting PSSCH#a, slot 2 is for transmitting PSSCH#b, and slot 3 is for transmitting PSSCH#c. PSSCH#a to PSSCH#c are all HARQ-enabled PSSCHs, and the terminal device detects HARQ corresponding to PSSCH#b and PSSCH#c. Therefore, PSSCH#b and PSSCH#c may be examples of the first PSSCH. If the start point of the reference period is the start point of COT#3, the start point of the reference period is the start point of slot 1.

[0375] In this embodiment of the present application, the reference period must include the first PSSCH. Specifically, the end of the reference period is the end of the transmission of the first PSSCH. Alternatively, the end of the reference period is a time after the end of the transmission of the first PSSCH.

[0376] FIG. 12 is a diagram illustrating how to determine the end of a reference period within COT#3. As shown in FIG. 12, COT#3 includes slots 1 to 3. See the above description of FIG. 12. PSSCH#a to PSSCH#c are all HARQ-enabled PSSCHs, and the terminal device detects HARQ corresponding to PSSCH#b and PSSCH#c. Therefore, PSSCH#b and PSSCH#c may be examples of the first PSSCH. If the end of the reference period is the end of transmission of the first PSSCH and the first PSSCH is PSSCH#b, the end of the reference period is the end of slot 2. If the end of the reference period is the end of transmission of the first PSSCH and the first PSSCH is PSSCH#c, the end of the reference period is the end of slot 3. If the end of the reference period is the end of transmission of the PSSCH transmitted after the first PSSCH and the first PSSCH is PSSCH#b, then the end of the reference period is the end of slot 3. If the end of the reference period is the end of transmission of the PSSCH after the first PSSCH and the first PSSCH is PSSCH#c, then since PSSCH#c is the last PSSCH in COT#3, the end of transmission of the reference period is the end of transmission of PSSCH#c, i.e., the end of slot 3.

[0377] It should be understood that in a possible implementation, the PSSCH may occupy multiple consecutive time units. In this case, the transmission end point of the PSSCH is the end point of the last time unit occupied by the PSSCH. For example, if PSSCH#b in FIG. 12 occupies slot 2 and slot 3, the transmission end point of PSSCH#b is the end point of slot 3. The time unit referred to in this embodiment of the present application may be a slot, a symbol, a half slot, a slot group, etc.

[0378] In a possible embodiment, the end point of the reference period is the end point of transmission of the first PSSCH, which is the first HARQ-enabled PSSCH whose corresponding HARQ is detected by the terminal device within COT#3.

[0379] 12, both PSSCH#b and PSSCH#c are HARQ-enabled PSSCHs, and the HARQs corresponding to PSSCH#b and PSSCH#c are detected by the terminal device. Since PSSCH#b is transmitted before PSSCH#c, that is, PSSCH#b is the first HARQ-enabled PSSCH whose corresponding HARQ is detected by the terminal device within COT#3, the first PSSCH is PSSCH#b, and the end point of the reference period is the end point of transmission of PSSCH#b, that is, the end point of slot 2.

[0380] The end of the reference period is the end of transmission of the first PSSCH, which is the first HARQ-enabled PSSCH whose corresponding HARQ is detected by the terminal device within COT#3. In other words, the end of the reference period is the end of the first time unit that satisfies the following condition: the terminal device completes transmission of the first PSSCH. Alternatively, the end of the reference period is the end of the first time unit that satisfies the following condition: the terminal device completes transmission of at least one HARQ-ACK enabled PSSCH, and at least one PSSCH in the at least one HARQ-ACK enabled PSSCH is a PSSCH whose corresponding HARQ is detected by the terminal device. Alternatively, the end point of the reference period is the end point of the first time unit that satisfies the following condition: the terminal device completes transmission of at least one ACK / NACK HARQ-ACK enabled PSSCH, and at least one PSSCH within the at least one ACK / NACK HARQ-ACK enabled PSSCH is a PSSCH whose corresponding HARQ is detected by the terminal device.

[0381] COT#3 is not limited in this embodiment of the present application. For example, COT#3 is the COT closest to the PSSCH to be currently transmitted, or the priority of COT#3 is the same as the priority of the PSSCH to be currently transmitted. For how the terminal device determines COT#3, please refer to the description of method 200.

[0382] It should be noted that if COT#3 does not include the first PSSCH, i.e., if all PSSCHs in COT#3 are PSSCHs with their HARQ disabled, or if COT#3 includes a HARQ-enabled PSSCH but the terminal device does not detect a HARQ corresponding to the HARQ-enabled PSSCH in COT#3, the end point of the reference period determined by the terminal device may be the end point of COT#3, or the end point of the reference period may be the time when the terminal device determines the target contention window value.

[0383] S1120: The terminal device may determine a target contention window value based on a transmission status of at least one PSSCH within the reference period.

[0384] For a method in which the terminal device determines a target contention window value based on the transmission status of at least one PSSCH in the reference period, refer to the method in which the terminal device determines a target contention window value based on the transmission status of at least one TB in the reference period in S220.

[0385] In this embodiment of the present application, the reference period determined by the terminal device includes the first PSSCH. Therefore, when the terminal device determines the target contention window value based on the transmission status of at least one PSSCH within the reference period, the terminal device can determine the target contention window value based on the HARQ of at least the first PSSCH, thereby avoiding the following problem: the terminal device does not have enough information to determine how to determine the target contention window value because it did not detect the HARQ corresponding to the PSSCH within the reference period. In addition, the following problem can also be avoided: when the terminal device does not detect the HARQ, the terminal device mistakenly considers the transmission-transmission conflict / transmission-reception conflict of the PSFCH as a PSSCH collision, so that the contention window value is blindly increased, further reducing the probability of the transmitting terminal device accessing the channel.

[0386] 13 is a schematic flowchart of a conflict window value determination method 1300 according to an embodiment of the present application. The method 1300 may include the following steps:

[0387] S1310: The terminal device determines a reference period.

[0388] The terminal device is the terminal device that initializes the COT.

[0389] The reference period is within a COT (denoted as COT#3, where COT#3 is a COT initialized by the terminal device), and the reference period includes at least one HARQ-enabled PSSCH. For example, the terminal device may determine that the start of the reference period is the start of COT#3. The end of the reference period is not limited in this embodiment of the present application. For example, the terminal device may determine that the end of the reference period is the end of the first time unit that satisfies the following condition: the terminal device completes transmission of at least one HARQ-enabled PSSCH.

[0390] For a description of the HARQ-enabled PSSCH, see the description of S1110 of method 1100.

[0391] S1320: The terminal device may determine a target contention window value based on a transmission status of at least one PSSCH within the reference period.

[0392] When the terminal device does not detect HARQs corresponding to all HARQ-enabled PSSCHs within the reference period, the terminal device either keeps the contention window value unchanged, or determines a target contention window value based on the proportion of retransmitted PSSCHs within the PSSCHs to be transmitted.

[0393] If the terminal device does not detect the HARQ corresponding to the HARQ-enabled PSSCH, it means that the terminal device cannot determine the reception status of the HARQ-enabled PSSCH. It should be understood that when a PSSCH collision occurs, control information related to the PSSCH (e.g., the control information is the primary SCI, or referred to as SCI-1) also collides. As a result, the control information cannot be received successfully, the receiving device of the PSSCH does not transmit the HARQ, and the terminal device cannot detect the HARQ. Alternatively, when a transmission-reception conflict / transmission-transmission conflict occurs for the PSFCH, the receiving device of the PSSCH does not transmit the HARQ, and the terminal device cannot detect the HARQ corresponding to the HARQ-enabled PSSCH. In this case, the terminal device cannot determine whether a PSSCH collision has occurred, or whether the PSSCH has been successfully received but a transmission-reception conflict / transmission-transmission conflict for the PSFCH has occurred.

[0394] For example, if the terminal device does not detect a HARQ corresponding to a HARQ-enabled unicast PSSCH, it means that the terminal device does not detect a PSFCH corresponding to a HARQ-enabled unicast PSSCH.

[0395] For example, if the terminal device does not detect a HARQ corresponding to the HARQ-enabled multicast 2 PSSCH, it means that the terminal device does not detect a PSFCH corresponding to the HARQ-enabled multicast 2 PSSCH.

[0396] The terminal device not detecting the HARQ corresponding to the HARQ-enabled PSSCH includes several cases: the terminal device not detecting the HARQ corresponding to the HARQ-enabled PSSCH in a time unit in which the terminal device is expected to detect the HARQ corresponding to the HARQ-enabled PSSCH, or the terminal device not detecting the HARQ corresponding to the HARQ-enabled PSSCH by the time the target contention window value is determined.

[0397] The terminal device's keeping the contention window value unchanged may include the following two cases: the terminal device's keeping the contention window value unchanged based on the contention window value of the COT initialized by the terminal device and closest to the current PSSCH to be transmitted, or the terminal device's keeping the contention window value unchanged based on the contention window value of COT#3. In other words, when the terminal device keeps the contention window value unchanged, the terminal device may determine the contention window value of the COT initialized by the terminal device and closest to the current PSSCH to be transmitted as the target contention window value, or the terminal device may determine the contention window value of COT#3 as the target contention window value. The terminal device's keeping the contention window value unchanged may be understood as the terminal device not adjusting the contention window value or not performing an action to adjust the contention window value. It should be understood that COT#3 initializes the terminal device and may not be the COT closest to the current PSSCH to be transmitted. COT#3 is not limited in this embodiment.

[0398] Referring to the above description of Type 1 LBT, before the terminal device initializes the COT, the terminal device needs to generate a counter N based on the contention window value, so that the terminal device performs a counter rollback process in Type 1 LBT based on the counter N. The contention window value of the COT initialized by the terminal device may be understood as the contention window value used by the terminal device to perform Type 1 LBT to initialize the COT.

[0399] The method by which the terminal device determines the target contention window value based on the proportion of retransmitted PSSCHs in the PSSCH to be transmitted is not limited in this embodiment of the present application. For example, if the proportion of retransmitted PSSCHs in the PSSCH to be transmitted exceeds threshold #1, the terminal device may determine the target contention window value as a value within the target value range that is greater than the contention window value of COT #3. If the proportion of retransmitted PSSCHs in the PSSCH to be transmitted is less than threshold #1, the terminal device may determine the target contention window value as the minimum value within the target value range, or may keep the contention window value unchanged. The target value range is the value range of the contention window value corresponding to the channel access priority class (CAPC) corresponding to the PSSCH to be transmitted. For example, if the CAPC corresponding to the PSSCH to be transmitted is 2, the target value range is {7, 15} according to Table 1.

[0400] In this embodiment of the present application, if the terminal device does not detect HARQs corresponding to all HARQ-enabled PSSCHs within the reference period, the terminal device no longer blindly increases the contention window value, but instead keeps the contention window value unchanged, or determines a target contention window value based on the proportion of retransmitted PSSCHs within the PSSCHs to be transmitted, which can avoid the problem of the terminal device blindly increasing the contention window value, which reduces the probability of the terminal device accessing the channel.

[0401] It may be understood that some optional features in the embodiments of the present application may be independent of other features in some scenarios, or may be combined with other features in some scenarios. This is not limited thereto.

[0402] It can be further understood that the solutions in the embodiments of the present application can be appropriately combined for use, and the explanations or descriptions of terms in the embodiments can be mutually referenced or explained in the embodiments. This is not limited.

[0403] In the foregoing method embodiments, it may be further understood that the methods and operations performed by a communications device may alternatively be performed by components (eg, chips or circuits) of the communications device.

[0404] Corresponding to the methods provided in the above method embodiments, an embodiment of the present application further provides a corresponding apparatus. The apparatus includes corresponding modules configured to perform the above method embodiments. The modules may be software, hardware, or a combination of software and hardware. It can be understood that the technical features described in the method embodiments are also applicable to the following apparatus embodiments.

[0405] 14 is a block diagram of a communication device 2000 according to an embodiment of the present application. The device 2000 includes a processing unit 2010, which may be configured to perform data processing.

[0406] Optionally, the apparatus 2000 further includes a transceiver unit 2020. The transceiver unit 2020 may be configured to perform corresponding communication functions. The transceiver unit 2020 may also be referred to as a communication interface or a communication unit.

[0407] Optionally, the apparatus 2000 further includes a storage unit. The storage unit may be configured to store instructions and / or data. The processing unit 2010 may read the instructions and / or data in the storage unit so that the apparatus performs the actions of the terminal device in the aforementioned method embodiments.

[0408] In one design, the apparatus 2000 may be the terminal device in the aforementioned embodiments or a component (e.g., a chip) of the terminal device. The apparatus 2000 may perform steps or procedures performed by the terminal device in the aforementioned method embodiments. The processing unit 2010 may be configured to perform processing-related operations of the terminal device in the aforementioned method embodiments.

[0409] In a possible embodiment, the processing unit 2010 is configured to determine a reference period, where the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted. The processing unit 2010 is further configured to determine a target contention window value based on the transmission status of at least one TB in the reference period, where the target contention window value is for preempting the channel of the TB to be transmitted. The cast type of the TB in the COT to which the reference period belongs is different from the cast type of the TB to be transmitted, and the TB in the COT to which the reference period belongs corresponds to at least two cast types, or the TB to be transmitted corresponds to at least two cast types.

[0410] In another possible embodiment, the processing unit 2010 is configured to determine a reference period corresponding to each of at least one cast type, where the at least one cast type is a cast type of at least one TB in the TB to be transmitted, where the priority of the COT to which the reference period belongs is the same as the transmission priority corresponding to the TB to be transmitted, and where the cast type of the TB in the reference period is the same as the cast type corresponding to the reference period. The processing unit 2010 is further configured to determine a target contention window value based on the transmission status of the TB in the reference period corresponding to each cast type, where the target contention window value is for preempting the channel of the TB to be transmitted. The TB in the COT to which the reference period belongs corresponds to at least two cast types, or the TB to be transmitted corresponds to at least two cast types.

[0411] In yet another possible implementation, the processing unit 2010 is configured to determine a target contention window value based on a transmission status of at least one PSSCH within a reference period, the target contention window value being for preempting a channel of the PSSCH to be transmitted, the reference period being within the COT, the reference period including a first PSSCH, the first PSSCH being a HARQ-enabled PSSCH, the HARQ corresponding to the first PSSCH being detected by a terminal device, and the terminal device being the terminal device that initializes the COT.

[0412] In yet another possible embodiment, the processing unit 2010 is configured to determine a target contention window value based on a transmission status of at least one PSSCH within the reference period, the target contention window value being for preempting a channel of the PSSCH to be transmitted. The reference period is within the COT, the reference period includes at least one HARQ-enabled PSSCH, and when the terminal device does not detect HARQs corresponding to all HARQ-enabled PSSCHs within the reference period, the terminal device keeps the contention window value unchanged, or the terminal device determines the target contention window value based on a proportion of retransmitted PSSCHs within the PSSCH to be transmitted.

[0413] The apparatus 2000 may perform corresponding steps or procedures performed by a terminal device in a method embodiment according to an embodiment of the present application. The apparatus 2000 may include a unit configured to perform the method performed by the terminal device in the embodiment shown in Figure 2, Figure 8, Figure 11, or Figure 13.

[0414] Please refer to the relevant descriptions of the above method embodiments for a more detailed description of the apparatus 2000. The details will not be described again here.

[0415] It should be understood that the specific processes of performing the aforementioned corresponding steps by the units have been described in detail in the aforementioned method embodiments, and for the sake of brevity, the details will not be described again here.

[0416] It should be understood that the apparatus 2000 herein is embodied in the form of a functional unit. The term "unit" herein may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (e.g., a shared processor, a dedicated processor, or a group processor) configured to execute one or more software or firmware programs, a memory, a combinatorial logic circuit, and / or another appropriate component supporting the described functionality. In an optional example, those skilled in the art can understand that the apparatus 2000 may specifically be a terminal device in the aforementioned embodiments and may be configured to perform procedures and / or steps corresponding to the terminal device in the aforementioned method embodiments. To avoid repetition, details will not be described again here.

[0417] The apparatus 2000 in the above solution has functions to perform corresponding steps performed by a terminal device in the above method. The functions may be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver unit may be replaced by a transceiver machine (e.g., a transmitting unit in a transceiver unit may be replaced by a transmitter machine, and a receiving unit in a transceiver unit may be replaced by a receiver machine), and another unit, such as a processing unit, may be replaced by a processor to separately perform receive-transmit operations and related processing operations in the method embodiments.

[0418] Additionally, the transceiver unit 2020 may alternatively be a transceiver circuit (eg, a transceiver circuit may include a receiver circuit and a transmitter circuit), and the processing unit may be a processing circuit.

[0419] It should be noted that the apparatus in Fig. 14 may be the device of the aforementioned embodiment, or may be a chip or a chip system, such as a system on chip (SoC). The transceiver unit may be an input / output circuit or a communication interface. The processing unit is a processor, a microprocessor, or an integrated circuit integrated on a chip. This is not limited here.

[0420] 15 is a block diagram of a communication device 3000 according to an embodiment of the present application. The device 3000 includes a processor 3010, which is coupled to a memory 3020. Optionally, the device further includes the memory 3020 configured to store computer programs or instructions and / or data. The processor 3010 is configured to execute computer programs or instructions stored in the memory 3020 or read data stored in the memory 3020 in order to perform the methods in the aforementioned method embodiments.

[0421] Optionally, there are one or more processors 3010 .

[0422] Optionally, one or more memories 3020 are present.

[0423] Optionally, the memory 3020 and the processor 3010 are integrated with each other or located separately.

[0424] Optionally, as shown in Figure 15, the apparatus 3000 further includes a transceiver 3030. The transceiver 3030 is configured to receive and / or transmit signals. For example, the processor 3010 is configured to control the transceiver 3030 to receive and / or transmit signals.

[0425] In the solution, the apparatus 3000 is configured to perform the operations performed by the terminal device in the above-mentioned method embodiments.

[0426] For example, the processor 3010 is configured to execute computer programs or instructions stored in the memory 3020 to perform the relevant operations of the terminal device in the method embodiments described above.

[0427] In the implementation process, the steps in the aforementioned method can be implemented using a hardware integrated logic circuit in the processor 3010 or using instructions in the form of software. The methods disclosed with reference to the embodiments of the present application may be directly executed by a hardware processor, or may be executed using a combination of hardware and software modules in the processor. The software modules may be located in a storage medium mature in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, or a register. The storage medium is located in the memory 3020, and the processor 3010 reads information in the memory 3020 and completes the steps in the aforementioned method together with the hardware of the processor 3010. To avoid repetition, details will not be described again here.

[0428] It should be understood that in the embodiments of the present application, the processor may be one or more integrated circuits, configured to execute associated programs to perform the method embodiments of the present application.

[0429] A processor (e.g., processor 3010) may include one or more processors and may be implemented as a combination of computing devices. The processor may include one or more of the following: a microprocessor, a microcontroller, a digital signal processor (DSP), a digital signal processing device (DSPD), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device (PLD), gating logic, transistor logic, a discrete hardware circuit, a processing circuit, or another suitable combination of hardware and firmware and / or software, configured to perform various functions described in this disclosure. The processor may be a general-purpose processor or a special-purpose processor. For example, processor 3010 may be a baseband processor or a central processing unit. The baseband processor may be configured to process communication protocols and communication data. The central processing unit may be configured to enable the device to execute software programs and process data within the software programs. Portions of the processor may further include non-volatile random access memory. For example, the processor may further store device type information.

[0430] In this application, a program broadly refers to software. Non-limiting examples of software include program code, a program, a subprogram, an instruction, an instruction set, code, a code segment, a software module, an application program, or a software application program. The program may be run on a processor and / or a computer to enable the device to perform various functions and / or processes described in this application.

[0431] A memory (e.g., memory 3020) may store data needed by a processor (e.g., processor 3010) when executing software. The memory may be implemented using any suitable storage technology. For example, the memory may be any available storage medium that can be accessed by the processor and / or computer. Non-limiting examples of storage media include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EPROM, EEPROM), compact disc read-only memory (CD-ROM), static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchlink dynamic random access memory (synchlink DRAM, SLDRAM), and direct rambus random access memory (direct rambus RAM, DR RAM), removable media, optical disk memory, magnetic disk storage media, magnetic storage devices, flash memory, registers, state memory, remotely mounted memory, local or remote storage components, or any other medium capable of holding or storing software, data, or information and accessible by a processor / computer. It should be noted that memory as described herein is intended to include, but is not limited to, these and other suitable types of memory.

[0432] The memory (e.g., memory 3020) and the processor (e.g., processor 3010) may be located separately or integrated with each other. The memory may be configured to connect to the processor such that the processor can read information from, store information to, and / or write information to the memory. The memory may be integrated with the processor. The memory and the processor may be located within an integrated circuit (e.g., the integrated circuit may be located in a terminal device or another network node).

[0433] 16 is a block diagram of a chip system 4000 according to an embodiment of the present application. The chip system 4000 (which may also be called a processing system) includes a logic circuit 4010 and an input / output interface 4020.

[0434] The logic circuit 4010 may be a processing circuit in the chip system 4000. The logic circuit 4010 may be coupled and connected to a storage unit and may call instructions in the storage unit, thereby enabling the chip system 4000 to implement the methods and functions in the embodiments of the present application. The input / output interface 4020 may be an input / output circuit in the chip system 4000, and outputs information processed by the chip system 4000, or inputs data or signaling information to be processed into the chip system 4000 for processing.

[0435] In the solution, the chip system 4000 is configured to perform the operations performed by the terminal device in the above-described method embodiments.

[0436] For example, logic circuitry 4010 is configured to perform processing-related operations performed by the terminal device in the aforementioned method embodiments, e.g., the processing-related operations performed by the terminal device in the embodiments shown in Figure 2, Figure 8, Figure 11, or Figure 13. Input / output interface 4020 is configured to perform transmission and / or reception-related operations performed by the terminal device in the aforementioned method embodiments, e.g., the transmission and / or reception-related operations performed by the terminal device in the embodiments shown in Figure 2 or Figure 8.

[0437] An embodiment of the present application further provides a computer-readable storage medium, which stores computer instructions for implementing the method executed by the terminal device in the aforementioned method embodiment.

[0438] An embodiment of the present application further provides a computer program product including instructions, which, when executed by a computer, implement the methods performed by the terminal device in the aforementioned method embodiments.

[0439] An embodiment of the present application further provides a communication system, which includes at least one terminal device in the above embodiment.

[0440] For the description of the relevant contents and beneficial effects of any one of the above-provided devices, please refer to the corresponding method embodiments provided above, and the details will not be described again here.

[0441] In some embodiments provided in the present application, it should be understood that the disclosed devices and methods may be implemented in other ways. For example, the above-described device embodiments are merely examples. For example, the above-described division into units is merely a logical division of functions, and actual implementations may employ other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the shown or described mutual couplings or direct couplings or communication connections may be implemented via some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electrical, mechanical, or other forms.

[0442] The aforementioned units described as separate parts may or may not be physically separate, and parts presented as units may or may not be physical units, and may be located in one location or distributed across multiple network units. Some or all of the units may be selected based on actual requirements to implement the solutions provided in this application.

[0443] In addition, the functional units in the embodiments of the present application may be integrated into one unit, each of the units may exist physically alone, or two or more units may be integrated into one unit.

[0444] Those skilled in the art may recognize that, in combination with the examples described in the embodiments disclosed herein, the units and algorithm steps may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether a function is performed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but the implementation should not be considered to go beyond the scope of this application.

[0445] When software is used to implement the embodiments, all or part of the embodiments may be embodied in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. For example, the computer may be a personal computer, a server, or a network 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, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio, or microwave) methods. See the above description of computer-readable storage media.

[0446] The above description is merely a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. Any variations or replacements that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application shall fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the scope of protection of the claims. [Explanation of symbols]

[0447] 10 Network Devices 20 Terminal Devices 21 Terminal Devices 22 Terminal Devices 100 Communication Systems 200 Conflict Window Value Determination Method 2000 Communication Equipment 2010 Processing Unit 2020 Transceiver Unit 3000 Communication Equipment 3010 processor 3020 Memory 3030 transceiver 4000 Chip System 4010 Logic Circuit 4020 Input / Output Interface

Claims

1. determining, by a terminal device, a reference period, the priority of the channel occupation time COT to which said reference period belongs being the same as the transmission priority corresponding to the transport block TB to be transmitted; determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period, the target contention window value being for preempting a channel of the TB to be transmitted; Including, The cast type of the TB in the COT to which the reference period belongs is different from the cast type of the TB to be transmitted, The TB in the COT to which the reference period belongs corresponds to at least two cast types; or The TB to be transmitted corresponds to at least two cast types; Conflict window value determination method.

2. The method of claim 1 , wherein a cast type of the at least one TB in the COT or in the reference period to which the reference period belongs is the same as a cast type of at least one TB in the TB to be transmitted.

3. The reference period includes at least one transmitted TB; or The COT to which the reference period belongs is the COT closest to the current time; 3. The method according to claim 1 or 2.

4. The reference period begins at one of the following times: the start time of the COT to which the reference period belongs; the start time of transmission of the transmitted TB within the COT to which the reference period belongs; the transmission start time of the TB corresponding to the lowest transmission priority among the TBs in the COT to which the reference period belongs; a transmission start time of a first TB in the COT to which the reference period belongs, the cast type of which is the same as the cast type of the at least one TB in the TB to be transmitted; or A transmission start time of a TB among TBs corresponding to the feedback information received by the terminal device, the TB being the first transmitted within the COT to which the reference period belongs.

4. The method according to claim 1, wherein the method is any one of the following:

5. The end of the reference period is one of the following: the end of the COT to which the reference period belongs; the end time of the transmission of the transmitted TB within the COT to which the reference period belongs; the transmission end time of the TB corresponding to the lowest transmission priority among the TBs in the COT to which the reference period belongs; a transmission end time of a first TB in the COT to which the reference period belongs, the cast type of the first TB being the same as the cast type of the at least one TB in the TB to be transmitted; the end time of transmission of the TB in the TB corresponding to the feedback information received by the terminal device, which is the last TB transmitted within the COT to which the reference period belongs; or The end point of the first transmission slot of the TB among the TBs corresponding to the feedback information received by the terminal device, the TB being the first transmitted within the COT to which the reference period belongs.

5. The method according to claim 1, wherein the method is any one of the following:

6. Prior to the step of determining, by the terminal device, a reference period, the method further comprises: determining, by the terminal device, that a cast type of a TB in the transmitted COT after the last updated contention window value is different from the cast type of the TB to be transmitted, or that the TB in the transmitted COT corresponds to at least two cast types; determining, by the terminal device, that the TB to be transmitted corresponds to at least two cast types; or determining, by the terminal device, that there is no transmitted TB whose cast type is the same as the cast type of the TB to be transmitted after the last updated contention window value; 6. The method of claim 1, further comprising:

7. The reference period includes one transmitted TB, which may be one of the following cases: the reference period includes the initial transmission and all retransmissions of the TB; the reference period includes the last retransmission of the TB; The reference period includes an initial transmission of the TB, and the feedback information of the initial transmission of the TB is an ACK; or The reference period includes a retransmission of the TB, and the feedback information of the retransmission of the TB is an ACK.

7. The method of any one of claims 3 to 6, comprising:

8. The step of determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period includes: determining, by the terminal device, the target contention window value based on a transmission status of a second TB within the reference period, wherein the second TB satisfies one or more of the following conditions: Both the initial transmission and the retransmission of the second TB are completed, and the feedback information of the last retransmission of the second TB is a negative acknowledgement (NACK). The feedback information of the initial transmission or retransmission of the second TB is an ACK; the cast type of the second TB is ranked before the cast types of the remaining TBs in the reference period according to a predefined cast type order; the cast type of the second TB is the same as the cast type of the at least one TB in the TB to be transmitted; The second TB is a TB within the TBs corresponding to the feedback information received by the terminal device, and is the last TB transmitted within the reference period. the transmission priority corresponding to the second TB is the same as the transmission priority corresponding to the TB to be transmitted; a contention window value determined based on the transmission status of the second TB is greater than a contention window value determined based on the transmission status of the remaining TBs within the reference period; a contention window value determined based on the transmission status of the second TB is smaller than a contention window value determined based on the transmission status of the remaining TBs within the reference period; the transmission priority corresponding to the second TB is higher than the transmission priorities corresponding to the remaining TBs in the reference period; or The second TB is a TB within the TBs in the reference period, for which the terminal device has received feedback information corresponding to the TB; Steps that satisfy one or more of the following:

8. The method of any one of claims 1 to 7, comprising:

9. 9. The method of claim 8, wherein the predefined cast type order is as follows, and the order of different cast types from front to back is multicast 2, multicast 1, unicast, and hybrid automatic repeat request disabled.

10. When the TBs within the reference period include M second TBs, where M is an integer greater than 1, the step of determining, by the terminal device, the target contention window value based on transmission statuses of second TBs within the reference period includes: determining, by the terminal device, N candidate contention window values ​​based on transmission statuses of the M second TBs, where N is a positive integer and N≦M; determining, by the terminal device, the target conflict window value based on the N candidate conflict window values; the target conflict window value is the smallest value among the N candidate conflict window values, or the target conflict window value is the largest value among the N candidate conflict window values, or the target conflict window value is the candidate conflict window value among the N candidate conflict window values ​​that is greater than the average of the N candidate conflict window values ​​and has the smallest difference from the average; or the target conflict window value is a candidate conflict window value among the N candidate conflict window values, the candidate conflict window value having the smallest absolute value of the difference between the candidate conflict window value and an average value of the N candidate conflict window values; 10. The method of claim 8 or 9, comprising:

11. When the TBs within the reference period include M second TBs, where M is a positive integer greater than 1, the step of determining, by the terminal device, the target contention window value based on transmission statuses of second TBs within the reference period includes: collecting, by the terminal device, statistics on feedback information of the M second TBs; determining, by the terminal device, the target contention window value based on the feedback information of the M second TBs; 10. The method of claim 8 or 9, comprising:

12. When the TBs within the reference period include M second TBs, where M is a positive integer greater than 1, the step of determining, by the terminal device, the target contention window value based on transmission statuses of second TBs within the reference period includes: determining, by the terminal device, the target contention window value based on a transmission status of one of the M second TBs; or updating, by the terminal device, a contention window value sequentially based on the transmission statuses of the M second TBs according to a transmission sequence of the M second TBs or a sequence of receiving feedback information of the M second TBs until the target contention window value is determined.

10. The method of claim 8 or 9, comprising:

13. The step of determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period includes: determining, by the terminal device, at least one candidate contention window value based on the transmission status of the at least one TB; determining, by the terminal device, the target conflict window value based on the at least one candidate conflict window value; the target conflict window value is the smallest value among the at least one candidate conflict window value; the target conflict window value is the largest value among the at least one candidate conflict window value; the target conflict window value is the candidate conflict window value of the at least one candidate conflict window value that is greater than the average value of the at least one candidate conflict window value and has the smallest difference from the average value; or the target conflict window value is a candidate conflict window value among the at least one candidate conflict window value, the candidate conflict window value having the smallest absolute value of the difference between the candidate conflict window value and an average value of the at least one candidate conflict window value; 8. The method of any one of claims 1 to 7, comprising:

14. The step of determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period includes: collecting statistics on feedback information of the at least one TB by the terminal device; determining, by the terminal device, the target contention window value based on the feedback information of the at least one TB; 8. The method of any one of claims 1 to 7, comprising:

15. The statistics regarding the feedback information are collected in the following manner: If the cast type of the TB is unicast, collect statistics on feedback information of the initial transmission of the TB and feedback information of each retransmission, collect statistics on ACK feedback information of the TB, or collect statistics on feedback information of the last retransmission of the TB; If the cast type of the TB is multicast 1 and the feedback information of the TB is NACK, the number of feedback information of the TB is set to 1; If the cast type of the TB is multicast 1 and the feedback information of the TB is not NACK, indicate the feedback information of the TB as ACK, and indicate the number of feedback information of the TB as 1, or indicate the number of feedback information of the TB as L, or indicate the number of feedback information of the TB as L-1, where L is the number of terminal devices included in a terminal device group configured to receive the TB; or If the cast type of the TB is multicast 2, collect statistics about each of the feedback information of the TB; 15. The method according to any one of claims 11 to 14.

16. When the reference period includes the at least one transmitted TB, and the at least one transmitted TB is the last transmitted TB after the last updated contention window value, the step of determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period includes: determining, by the terminal device, the target contention window value based on a transmission status of the last transmitted TB; 4. The method of claim 3, comprising:

17. The step of determining, by the terminal device, the target contention window value based on the transmission status of the last transmitted TB, comprises: if the cast type of the last transmitted TB is hybrid automatic repeat request (HARQ) enabled, determining, by the terminal device, the target contention window value based on feedback information of the last transmitted TB; or If the cast type of the last transmitted TB is HARQ disabled, determining, by the terminal device, the target contention window value based on the number of blind transmissions or the proportion of blind transmissions of the last transmitted TB.

17. The method of claim 16, comprising:

18. When the COT to which the reference period belongs is the COT closest to the current time, the step of determining, by the terminal device, a target contention window value based on a transmission status of at least one TB within the reference period includes: determining, by the terminal device, the target contention window value based on a transmission status of a last transmitted TB within the reference period; 4. The method of claim 3, comprising:

19. The step of determining, by the terminal device, the target contention window value based on a transmission status of a last transmitted TB within the reference period, comprises: determining by the terminal device that the target contention window value is kept unchanged if the terminal device does not receive feedback information of the last transmitted TB; or determining, by the terminal device, the target contention window value based on the feedback information of the last transmitted TB when the terminal device receives the feedback information of the last transmitted TB; 20. The method of claim 18, comprising:

20. determining, by the terminal device, a target contention window value based on a transmission status of at least one physical sidelink shared channel (PSSCH) within a reference period, the target contention window value being for preempting a channel of the PSSCH to be transmitted; Including, The reference period is within a channel occupation time COT, the reference period includes a first PSSCH, the first PSSCH is a hybrid automatic repeat request (HARQ) enabled PSSCH, and a HARQ corresponding to the first PSSCH is detected by the terminal device; The terminal device is a terminal device that initializes the COT; Conflict window value determination method.

21. 21. The method of claim 20, wherein the HARQ-enabled PSSCH comprises one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, a HARQ-enabled multicast 1 PSSCH, or a HARQ-enabled multicast 2 PSSCH.

22. 21. The method of claim 20, wherein the HARQ-enabled PSSCH comprises one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, or a HARQ-enabled multicast 2 PSSCH.

23. 23. The method of any one of claims 20 to 22, wherein the start of the reference period is the start of the COT.

24. 24. The method according to claim 20, wherein the end point of the reference period is the end point of the time unit in which the first PSSCH is located, and the first PSSCH is a first HARQ-enabled PSSCH whose corresponding HARQ is detected by the terminal device within the COT.

25. determining, by the terminal device, a target contention window value based on a transmission status of at least one physical sidelink shared channel (PSSCH) in a reference period, the target contention window value being for preempting a channel of the PSSCH to be transmitted; the reference period is within a channel occupation time COT, and the reference period includes at least one hybrid automatic repeat request (HARQ)-enabled PSSCH; When the terminal device does not detect HARQs corresponding to all HARQ-enabled PSSCHs in the reference period, the terminal device keeps a contention window value unchanged, or determines the target contention window value based on a proportion of retransmitted PSSCHs in the PSSCHs to be transmitted. A method for determining a conflicting window value, comprising:

26. 26. The method of claim 25, wherein the HARQ-enabled PSSCH comprises one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, a HARQ-enabled multicast 1 PSSCH, or a HARQ-enabled multicast 2 PSSCH.

27. 26. The method of claim 25, wherein the HARQ-enabled PSSCH comprises one or more of the following PSSCHs: a HARQ-enabled unicast PSSCH, or a HARQ-enabled multicast 2 PSSCH.

28. A communication device comprising a module or unit configured to carry out the method of any one of claims 1 to 27.

29. 28. A communications device comprising a processor, the processor configured to execute computer programs or instructions stored in a memory to enable the device to perform a method according to any one of claims 1 to 27.

30. The apparatus further comprises the memory and / or a communication interface, the communication interface coupled to the processor; the communication interface is configured to input and / or output information; 30. The apparatus of claim 29.

31. 28. A computer-readable storage medium storing a computer program or instructions on a communication device, the computer program or instructions being run on the communication device to enable the communication device to perform the method of any one of claims 1 to 27.

32. 28. A computer program product, said computer program product comprising a computer program or instructions for carrying out the method of any one of claims 1 to 27.

33. 28. A chip coupled to a memory and configured to read and execute program instructions stored in the memory to perform the method of any one of claims 1 to 27.

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