Channel Access Priority

Abstract

The present disclosure provides a method for determining a channel access priority for a transmission. Some examples of the present disclosure relate to an apparatus, a method, and a computer program for determining a channel access priority. Some examples provide an apparatus (10) including: means (11) for determining information indicative of a channel access priority (p) for a physical sidelink feedback channel (PSFCH) transmission (205) based at least in part on information indicative of at least one status of at least one immediately preceding PSFCH transmission (204) or information indicative of a cast type of a sidelink (SL) transmission (202) associated with the PSFCH transmission (205).

Description

[Technical Field]

[0001] Various examples of the present disclosure relate to the field of data communications, and in particular to an apparatus, method, and computer program for determining channel access priority. Without prejudice to the foregoing, some examples relate to a user equipment (UE) for determining a channel access priority class for transmission via a physical sidelink feedback channel. [Background technology]

[0002] Conventional methods of determining channel access priority for transmissions (such as physical sidelink feedback channel (PSFCH) transmissions) are not always optimal.

[0003] In some situations, it may be desirable to provide improved apparatus, methods, and computer programs for determining channel access priority for transmissions, such as PSFCH transmissions.

[0004] The listing or discussion of any prior-published document or any background in this specification should not necessarily be construed as an acknowledgement that the document or background is part of the state of the art or is common general knowledge. One or more aspects / embodiments of the present disclosure may or may not address one or more of the background issues. Summary of the Invention

[0005] The scope of protection sought for various embodiments of the invention is defined by the claims that follow.

[0006] In accordance with various, but not necessarily all, examples of the present disclosure, examples are provided as claimed in the appended claims. Any examples and features described herein that do not fall within the scope of an independent claim should be construed as examples useful for understanding various embodiments of the present invention.

[0007] According to at least some examples of the present disclosure, means for determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, the means comprising: information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; An apparatus is provided that includes means for determining, based at least in part on:

[0008] According to various, but not necessarily all, examples of the present disclosure: determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; The present invention provides a method that includes determining, based at least in part on:

[0009] In accordance with various, but not necessarily all, examples of the present disclosure, a chipset is provided that includes processing circuitry configured to perform the methods described above.

[0010] According to various, but not necessarily all, examples of the present disclosure, there are provided modules, circuits, devices, user equipment and / or systems comprising means for performing the methods described above.

[0011] According to various, but not necessarily all, examples of the present disclosure, when performed by an apparatus, determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; A computer program product is provided that includes instructions for causing an apparatus to perform the step of determining based at least in part on the

[0012] According to various, but not necessarily all, examples of the present disclosure: at least one processor; and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to perform at least: determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; An apparatus is provided for performing the determining step based at least in part on the

[0013] According to various, but not necessarily all, examples of the present disclosure, when executed by at least one processor, determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; A non-transitory computer-readable medium is provided that is encoded with instructions to cause a determining step based at least in part on the

[0014] In some instances, but not necessarily all, the PSFCH transmission is in an unlicensed spectrum.

[0015] In some, but not necessarily all, examples, the information indicative of channel access priority may be: Priority classes for use in Listen Before Talk (LBT) procedures, Priority classes for use within unlicensed bands; Channel Access Priority Class (CAPC), Contention Window (CW), and Channel Occupancy Time (COT), At least one selected from the group:

[0016] In some, but not necessarily all, examples, the information indicative of at least one state of the at least one immediately preceding PSFCH transmission may include: the channel access state of at least one immediately preceding PSFCH transmission; whether at least one immediately preceding PSFCH transmission failed or succeeded; whether the LBT procedure failed or succeeded for transmitting at least one immediately preceding PSFCH transmission; the LBT success rate for the immediately preceding one or more PSFCH transmissions; the number of successful LBTs for the immediately preceding one or more PSFCH transmissions; whether the PSFCH transmission includes a retransmission of information that was not successfully transmitted via at least one immediately preceding PSFCH transmission; Allocation of resources for PSFCH transmissions, the resources being allocated for retransmitting information that was not successfully transmitted via at least one immediately preceding PSFCH transmission; and whether the PSFCH transmission is within the channel occupation time (COT) shared by the UE; The information includes information indicating at least one selected from the group of:

[0017] In some, but not necessarily all, examples, the means for determining the information indicative of channel access priority for the PSFCH transmission may include: means for determining a first candidate priority class for PSFCH transmission; means for determining a second candidate priority class for PSFCH transmission; and means for selecting at least one of the first candidate priority class and the second candidate priority class.

[0018] In some instances, but not necessarily all, the first candidate priority class and / or the second candidate priority class are predefined; the first candidate priority class and / or the second candidate priority class are configured in the device; the first candidate priority class is configured to have a lower channel access priority than the second candidate priority class; the first candidate priority class is determined based at least in part on channel access priorities of one or more SL transmissions associated with the transmission; the second candidate priority class is determined based at least in part on channel access priorities of one or more SL transmissions associated with the transmission; The second candidate priority class is determined based at least in part on the first candidate priority class; and the second candidate priority class is determined based at least in part on the first candidate priority class and the priority class offset. At least one selected from the group:

[0019] In some, but not necessarily all, examples, the means for selecting one of the first and second candidate priority classes comprises means for selecting one of the first and second candidate priority classes according to at least one selection criterion.

[0020] In some, but not necessarily all, examples, at least one selection criterion includes selecting the first candidate priority class by default.

[0021] In some, but not necessarily all, instances, at least one selection criterion is: determining whether the PSFCH transmission is a retransmission of at least a portion of a previously attempted PSFCH transmission; determining whether the PSFCH transmission is a retransmission of feedback that was previously attempted to be transmitted; determining whether the PSFCH transmission is a Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) or a retransmission of a Negative Acknowledgement (NACK) of a previous transmission attempt; determining a type of resource for PSFCH transmission; determining whether the resources allocated for the PSFCH transmission are resources allocated for retransmitting information that was not successfully transmitted via at least one immediately preceding PSFCH transmission; determining whether a HARQ-ACK for at least one immediately preceding PSFCH transmission or PSFCH transmissions cannot be transmitted via an earlier allocated resource due to an LBT failure; selecting a second candidate priority class in response to at least one of

[0022] In some, but not necessarily all, instances, at least one selection criterion is: Selecting the second candidate priority class in response to determining whether an LBT success rate among a number of previous PSFCH transmissions is less than a threshold.

[0023] In some, but not necessarily all, instances, at least one selection criterion is: Selecting a second candidate priority class in response to determining whether the number of LBT successes among the immediately preceding number of PSFCH transmissions is less than a threshold.

[0024] In some, but not necessarily all, instances, at least one selection criterion is: Selecting a second candidate priority class in response to determining whether the SL transmission is a unicast transmission.

[0025] In some, but not necessarily all, examples, the device further comprises: The apparatus includes means for receiving configuration information to enable the apparatus to determine at least one selection criterion to apply to select one of the first candidate priority class and the second candidate priority class.

[0026] In some, but not necessarily all, examples, the device further comprises: The method includes determining at least one selection criterion to apply based at least in part on a cast type of the SL transmission associated with the PSFCH transmission.

[0027] In some, but not necessarily all, examples, the device further comprises: The apparatus includes means for receiving configuration information to enable the apparatus to determine information indicative of channel access priority for PSFCH transmission.

[0028] In some, but not necessarily all, instances, the configuration information is the first candidate priority class, a second candidate priority class, an offset between the first candidate priority class and the second candidate priority class; the number of previous PSFCH transmissions, Threshold of transmission success rate, a threshold for the number of successful transmissions, the cast type of the SL transmission associated with the PSFCH transmission, and one or more selection criteria to which the device is applied; The method includes at least one instruction selected from the group consisting of:

[0029] In some, but not necessarily all, examples, the cast type includes at least one of groupcast and unicast.

[0030] In some, but not necessarily all, examples, the SL transmission associated with the PSFCH transmission includes a physical sidelink shared channel (PSSCH) transmission.

[0031] In some, but not necessarily all, instances, the device: Means for performing a channel access procedure for transmitting a transmission based at least in part on the determined information indicative of channel access priority are included.

[0032] Although the above example and optional features of the present disclosure are described separately, it is understood that providing them in all possible combinations and permutations is included within the present disclosure. It is understood that various examples of the present disclosure can include any or all of the features described with respect to other examples of the present disclosure, and vice versa. It is also understood that any one or more or all of the features can be implemented by, be executable by, or be executable by apparatus, methods, and / or computer program instructions, in any combination, as desired and needed.

[0033] Some examples will now be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0034] [Figure 1] 1 illustrates an example of the subject matter described herein. [Figure 2] 10 illustrates another example of the subject matter described herein. [Figure 3] 1 illustrates another example of the subject matter described herein. [Figure 4] 1 illustrates another example of the subject matter described herein. [Figure 5] 10 illustrates another example of the subject matter described herein. [Figure 6] 1 illustrates another example of the subject matter described herein. [Figure 7] 1 illustrates another example of the subject matter described herein. [Figure 8] 1 illustrates another example of the subject matter described herein. [Figure 9] 1 illustrates another example of the subject matter described herein. [Figure 10] 1 illustrates another example of the subject matter described herein. [Figure 11] 1 illustrates another example of the subject matter described herein. [Figure 12] 1 illustrates another example of the subject matter described herein. DETAILED DESCRIPTION OF THE INVENTION

[0035] The drawings are not necessarily to scale. Certain features and views of the drawings may be shown diagrammatically or exaggerated in scale for clarity and conciseness. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to aid in illustration. Like reference numbers are used in the drawings to denote like features. For clarity, not all reference numbers necessarily appear in every figure.

[0036] In the drawings (and description), similar features may be referenced by the same three-digit number. In the drawings (and description), an optional suffix to the three-digit number may be used to distinguish between different instances of similar features. Thus, a three-digit number without a suffix is ​​used as a general reference, and a three-digit number with a suffix is ​​used as a specific reference. A suffix may include a single digit that labels different instances. A suffix may include two digits, with the first digit labeling a group of instances and the second digit labeling different instances within the group.

[0037] [Abbreviation / Definition] 5G: Fifth Generation ACK: Acknowledgement CAPC: Channel Access Priority Class CCA: Clear Channel Assessment CG: Setting Grant COT: Channel Occupancy Time CSI: Channel State Information CW: Contention Wind DL: Downlink gNB: gNodeB HARQ: Hybrid Automatic Repeat Request LBT: Listen Before Talk NR:New Radio PSCCH: Physical Sidelink Control Channel PSFCH: Physical Sidelink Feedback Channel PSSCH: Physical Sidelink Shared Channel PUCCH: Physical uplink control channel RAN: Radio Access Network Rx: Receiver SCI: Sidelink Control Information SL: Side link TB: Transfer Block Tx: Transmitter U: No license required UE: User Equipment UL: Uplink

[0038] 1 illustrates schematically an example of a network 100 comprising multiple network nodes, including terminal nodes 110 (also referred to as user equipment, UE), access nodes 120, and one or more core nodes 130. The terminal nodes 110 and access nodes 120 communicate with each other. The access nodes 120 communicate with one or more core nodes 130. The one or more core nodes 130 may communicate with each other in some, but not necessarily all, examples. The one or more access nodes 120 may communicate with each other in some, but not necessarily all, examples.

[0039] Network 100, in this example, is a wireless communication network, or Radio Access Network (RAN), in which at least some of the end nodes 110 and access nodes 120 communicate with each other using the transmission / reception of radio waves.

[0040] The RAN 100 may be a cellular network comprising multiple cells 122 each served by an access node 120. The access node 120 comprises a cellular radio transceiver. The end node 110 comprises a cellular radio transceiver.

[0041] In the particular example shown, network 100 is a Next Generation (NG) or New Radio (NR) network, where NR is the 3rd Generation Partnership Project (3GPP®) name for fifth generation (5G) technology.

[0042] The interface between the end node 110 and the access node 120 is a radio interface 124 (e.g., a Uu interface). The interface between the access node 120 and one or more core nodes 130 is a backhaul interface 128 (e.g., an S1 interface and / or an NG interface).

[0043] Depending on the exact deployment scenario, the access nodes 120 may be RAN nodes, such as NG-RAN nodes. The NG-RAN node may be a gNodeB (gNB) providing NR user plane and control plane protocol terminations towards the UE. The NG-RAN node may be a New Generation Evolved Universal Terrestrial Radio Access Network (E-UTRAN) NodeB (NG-eNB) providing E-UTRA user plane and control plane protocol terminations towards the UE. The gNB and ng-eNB may be interconnected with each other by an Xn interface. The gNB and NG-eNB are also connected to the 5G Core (5GC) by an NG interface, more specifically to the AMF (Access and Mobility Management Function) by an NG-C interface and to the UPF (User Plane Function) by an NG-U interface. The access nodes 120 may be interconnected with each other by an Xn interface 126. The cellular network 100 may be configured to operate in licensed or unlicensed frequency bands, particularly the 60 GHz unlicensed band, where beamforming is mandatory to achieve the required coverage.

[0044] The access node 120 may be deployed in NR standalone operation / scenario. The access node 120 may be deployed in NR non-standalone operation / scenario. The access node may be deployed in Carrier Aggregation (CA) operation / scenario. The access node 120 may be deployed in Dual Connectivity operation / scenario, i.e., Multi-Radio Access Technology - Dual Connectivity (MR-DC), in particular, e.g. New Radio-Evolved Universal Terrestrial Radio Access Dual Connectivity (NR-EUTRA-DC, also known as NE-DC), Next Generation Radio Access Network Evolved Universal Terrestrial Radio Access - New Radio Dual Connectivity (NG-RAN E-UTRA-NR Dual Connectivity, also known as NGEN-DC), or New Wireless Dual Connectivity (also known as NR-DC), It can be expanded in

[0045] In such a non-standalone / dual connectivity deployment, the access nodes 120 may be interconnected to each other by X2 or Xn interfaces, connected to the evolved packet core (EPC) by S1 interfaces, or connected to the 5GC by NG interfaces.

[0046] Terminal nodes 110 are network elements in a network that terminate the user side of a wireless link. They are devices that enable access to network services. Terminal nodes 110 may be referred to as user equipment (UE), mobile terminals, or mobile stations. The term "user equipment" may be used to designate a mobile device that includes a smart card or the like for authentication / encryption, such as a subscriber identity module (SIM). In other examples, the term "user equipment" is used to designate a mobile device that includes circuitry embedded as part of the user equipment for authentication / encryption, such as a software SIM.

[0047] The access node 120 is a network element in the network responsible for radio transmission and reception in one or more cells 122 to and from the end nodes 110. Such an access node may also be called a transmission / reception point (TRP) or base station. The access node 120 is the network termination of a radio link. The access node 120 may be implemented as a single network device or may be separated / distributed across two or more RAN nodes, such as a central unit (CU), a distributed unit (DU), a remote radio headend (RRH), etc., using different functional division architectures and different interfaces.

[0048] In the following description, the access node will be referred to as gNB120 and the terminal node 110 will be referred to as UE110.

[0049] In sub-7 GHz unlicensed bands / unlicensed spectrum, New Radio (NR), coexistence with other systems (e.g., IEEE 802.11) is ensured via the Listen-Before-Talk (LBT) channel access procedure / mechanism, where a user equipment intending to perform a sidelink (SL) transmission must first successfully complete an LBT check before it can begin transmission.

[0050] For a UE to pass the LBT check, the UE must observe that the transmission channel is available for several consecutive Clear Channel Assessment (CCA) slots. In sub-7 GHz, these slots are 9 μs in duration. The UE considers the channel available in a CCA slot if the measured power (i.e., the energy collected during the CCA slot) is below a regulatory specified threshold (which may depend on the operating band and geographic region).

[0051] When a UE initiates communication (i.e., the UE is responsible for initiating the device), the UE must gain the "right" to access the channel for a period of time, denoted as the Channel Occupancy Time (COT), by applying an "extended" LBT procedure. In this case, the channel must be considered free for the entire duration of the backoff procedure, which is determined by the Contention Window (CW). This "extended" LBT procedure is commonly known as LBT Type 1, as specified in TS 37.213.

[0052] The duration of both the COT and the CW depends on the Channel Access Priority Class (CAPC) associated with the UE's traffic, as shown in Table 1 below: Control plane traffic is transmitted with p=1 and user plane traffic has p>1. Table 1 (from TS37.213 "Table 4.2.1-1 Channel Access Priority Class (CAPC) for UL"). The contention window length in the CCA slot associated with each CAPC is the minimum (CW min,p ) and Max (CW max,p ) The duration of COT is T ulm cot,p is given by [Table 1]

[0053] Figures 2(a)-(f) show details of LBT Type 1 for the Uu uplink (UL). It should be understood that for the downlink (DL), LBT Type 1 parameters can also be adopted in principle in the downlink (SL). These figures show the allowed gaps where the LBT Type 2 variant is applicable. Figure 2(a) and (d) - LBT type 2C, Figure 2(b) and (e) - LBT type 2B, Figure 2(c) and (f) - LBT type 2A.

[0054] 2(a), (b), and (c) show the case where the gaps are both between two transmissions from the initiating UE, while (d), (e), and (f) correspondingly show the case where the gaps are between two different transmissions from the initiating and responding UEs.

[0055] A UE (initiating device) initiating a transmission successfully completes LBT Type 1 and, upon performing the transmission, obtains a COT with a duration associated with the corresponding CAPC for the transmission. The obtained COT remains valid even if the initiating device pauses its transmission, but if the initiating device wants to perform a new transmission (within the COT), it must still perform a "reduced" LBT procedure. This "reduced" LBT procedure is commonly known as LBT Type 2 [TS37.213] and has the following variations: Type 2A (25 μs LBT)—The obtained COT of an SL transmission in the initiating device, as shown in Figures 2(c) and (f) (similarly for an SL transmission that follows another SL transmission if the gap between the two SL transmissions is ≥ 25 μs). Type 2B (16 μs LBT)—The obtained COT for SL transmission within the initiating device, as shown in Figures 2(b) and (e) (can only be used for SL transmissions following another SL with a gap exactly equal to 16 μs). Type 2C (no LBT) - may only be used for SL transmission following another SL, with a gap of 16 μs or less and an allowed duration of the SL transmission of 584 μs or less, as shown in Figures 2(a) and (d).

[0056] The initiating device can share its acquired COT with its intended receiver (responding device). For this purpose, the initiating device must inform the responding device (e.g., via control signaling) about the duration of this COT. The responding device uses this information to determine which type of LBT to apply when performing a transmission where the intended receiver is the initiating device. If the responding device's transmission is outside the range of the COT, the responding device must acquire a new COT using LBT Type 1 with the appropriate CAPC.

[0057] Here, we will provide an overview of the sidelink (SL) in New Radio (NR).

[0058] NR SL is designed in 3GPP Rel-16 to facilitate UEs communicating with other nearby UEs via direct / SL communication. Two resource allocation modes are specified, one of which the SL transmitter (Tx) of a UE is configured with to perform its NR SL transmissions. These modes are denoted as NR SL Mode 1 and NR SL Mode 2.

[0059] In NL SR mode 1, sidelink transmission resources are allocated (scheduled) to SL Tx UEs by the network NW, whereas SL Tx UEs in mode 2 autonomously select their own SL transmission resources.

[0060] In NL SR mode 1, where the gNB is responsible for SL resource allocation, the configuration and operation is similar to that performed over the Uu interface (shown in Figure 3). MAC level details of this procedure are given in section 5.8.3 of TS38.321.

[0061] In NL SR Mode 2, as shown in Figure 4, SL UEs autonomously perform resource selection using a sensing procedure. More specifically, an SL Tx UE in NR SL Mode 2 first performs a sensing procedure on the configured SL transmission resource pool to gain knowledge of resources reserved by other nearby SL Tx UEs. Based on the knowledge gained from sensing, the SL Tx UE can select resources from the available SL resources accordingly. For an SL UE to perform sensing and obtain the information necessary to receive SL transmissions, the SL UE needs to decode sidelink control information (SCI). In Release 16, SCIs related to data transmission include first-stage SCIs and second-stage SCIs, the contents of which are standardized in 3GPP TS38.212.

[0062] The SCI follows the second-stage SCI structure, the main motivation of which is to support size differences between SCIs for various NR-V2X (NR Vehicle-to-Everything) SL service types (e.g., broadcast, groupcast, and unicast).

[0063] The first stage SCI, SCI format 1-A, is carried by the physical sidelink shared channel PSSCH and includes: Information to enable sensing operations; and Information needed to determine resource allocation for the PSSCH and decode the second stage SCI. According to Rel-16, the contents of the first stage SCI are as follows: [Table 2]

[0064] The second stage SCI, SCI formats 2-A and 2-B, carried by the PSSCH (multiplexed with the SL-SCH), includes: Source and destination identities. · Information to identify and decode the associated SL-SCH Transport Block (TB). · Control of Hybrid Automatic Repeat Request (HARQ) feedback in unicast / groupcast. · Triggering CSI feedback in unicast.

[0065] In accordance with Rel-16, the contents of the second stage SCI are provided in Table 2 below. [Table 3]

[0066] Next, an overview of the SL physical layer structure will be explained.

[0067] The configuration of resources in the sidelink resource pool defines the minimum information needed for an RX UE to be able to decode a transmission, including the number of subchannels, the number of physical resource blocks (PRBs) per subchannel, the number of symbols in the physical sidelink control channel (PSCCH), which slots have a PSFCH, as well as other configuration aspects not relevant to this disclosure.

[0068] Details of the actual sidelink transmission (i.e., payload) are provided in the PSCCH (first stage SCI) for each individual transmission, including time and frequency resources, demodulation reference signal (DMRS) configuration of the PSSCH, MCS, PSFCH, etc.

[0069] Figure 5(a) shows an example of an SL slot structure comprising a slot with PSCCH / PSSCH. Figure 5(b) shows an example of an SL slot structure comprising a slot with PSCCH / PSSCH, with the immediately preceding symbol being used for PSFCH.

[0070] The configuration of the PSCCH (e.g., DMRS, MCS, number of symbols used) is part of the resource pool configuration. Additionally, an indication of which slots have PSFCH symbols is also part of the resource pool configuration. However, the configuration of the PSSCH (e.g., number of symbols used, DMRS pattern, and MCS) is provided by the first stage SCI, which is the payload transmitted within the PSCCH, and follows the configuration shown above and described in Section 8.3.1.1 of Rel-16 TS38.212.

[0071] Here, an overview of SL HARQ operation will be given.

[0072] The PSFCH was introduced during Rel-16 to enable HARQ feedback over the sidelink from the UE that is the intended recipient of a PSSCH transmission (i.e., the RX UE) to the UE that performed the transmission (i.e., the Tx UE). Within the PSFCH, a Zadoff-Chu sequence within one PRB is repeated across two OFDM symbols near the end of the sidelink resources within the slot, one of which may be used for AGC. Exemplary slot formats for the PSCCH, PSSCH, and PSFCH are provided in Figure 5(b). The Zadoff-Chu sequence as a base sequence is (pre-)configured for each sidelink resource pool.

[0073] The time resource for PSFCH is (pre)configured to occur once every 0, 1, 2 or 4 slots according to 38.331. The HARQ feedback resource (PSFCH) is derived from the resource position of the PSCCH / PSSCH.

[0074] For PSSCH-to-HARQ timing, there is a configuration parameter K with units of slots. The time opportunity for the PSFCH is determined from K. For a PSSCH transmission with the immediately preceding symbol in slot n, the HARQ feedback is in slot n+a, where a is the smallest integer greater than or equal to K, provided that slot n+a includes a PSFCH resource. A time gap of at least K slots allows for the processing delay of RX UEs in decoding the PSCCH and generating HARQ feedback to be taken into account. K can be equal to 2 or 3, and a single value of K can be (pre-)configured per resource pool. This allows several RX UEs using the same resource pool to utilize the same mapping of PSFCH resources for HARQ feedback. The parameter K can be used to determine the N PSSCH slots associated with a slot with a PSFCH.

[0075] As an example, as shown in Figure 6, the PSFCH resource duration is configured as N = 4 (i.e., there are 4 PSSCH slots associated with the PSFCH), and K (sl-MinTimeGapPSFCH, the minimum time gap between the PSFCH and the associated PSSCH in slots) is configured as 2. With L subchannels in the resource pool and N PSSCH slots associated with the slot containing the PSFCH, there are N*L subchannels associated with the PSFCH symbol. With M PRBs available for the PSFCH in the PSFCH symbol, there are M PRBs available for HARQ feedback for transmission over the N*L subchannels.

[0076] If M is configured to be a multiple of N*L, then a separate set of M=M / (N*L) PRBs may be associated with HARQ feedback for each subchannel within the PSFCH period. The first set of M PRBs among the M PRBs available in the PSFCH are associated with HARQ feedback for the first subchannel's transmission in the first slot. The second set of M PRBs are associated with HARQ feedback for the first subchannel's transmission in the second slot, etc.

[0077] This is shown in Figure 6, with N=4, L=3, and all PRBs in the PSFCH symbols available for the PSFCH. In this example, HARQ feedback for transmission on PSSCH x is transmitted on a set x of Mset PRBs in the corresponding PSFCH symbol, using x=1,...,12.

[0078] The set of Mset PRBs associated with a subchannel is shared among multiple RX UEs in case of ACK / NACK feedback for groupcast communication (option 2) or in case of different PSSCH transmissions within the same subchannel.

[0079] For each PRB available in the PSFCH, there are Q cycle-shifted pairs available to support ACK or NACK feedback for the Q RX UEs within the PRB. For resource pooling, the number of cycle-shifted pairs, Q, is (pre-)configured and can be equal to 1, 2, 3, or 6.

[0080] The number of PSFCH resources F available to support HARQ feedback for a given transmission may be calculated (in TS38.213, F is

number

[0081] The F PSFCH resources available for multiplexing HARQ feedback for the PSSCH may be determined based on two options. a) Based on the L PSSCH subchannels used by the PSSCH, F may be calculated as follows: ○ F = L PSSCH * Mset * Q PSFCH (associated with L PSSCH subchannels of PSSCH) ○Here, ·L PSSCH subchannel of PSSCH. ·Mset PRBs of the PSFCH associated with each subchannel. · Q-cycle shift pairs available for each PRB. b) Or based only on the starting subchannel used by the PSSCH (ie, based on only one subchannel if L PSSCH>1). ○ F = Mset*Q PSFCH (relative to the starting subchannel of the PSSCH) ○Here, ·Mset PRBs of the PSFCH associated with each subchannel. · Q-cycle shift pairs available for each PRB.

[0082] In Rel.15 NR Uu, similar to the Physical Uplink Control Channel (PUCCH), the available F PSFCH resources are indexed based on the PRB index (frequency domain) and cycle shift pair index (code domain).

[0083] The mapping of PRBs of PSFCH index i (i=1, 2, ..., F) to Q cycle-shifted pairs is such that PSFCH index i first increases with the PRB index until it reaches the number of PRBs available in the PSFCH, then increases with the cycle-shifted pair index, and then increases again with the PRB index, etc.

[0084] Among the F PSFCHs available for HARQ feedback for a given transmission, the RX UE selects the PSFCH with index i for its HARQ feedback, given by:

number

[0085] For groupcast ACK / NACK feedback (option 2), it is equal to the RX UE identifier in the group and is indicated by higher layers. For X, the number of RX UEs in the group, the RX UE identifier is an integer between 0 and X-1. The RX UE determines the PRB and cycle shift pair to use for transmitting HARQ feedback based on the PSFCH index i. To transmit a NACK or an ACK, respectively, the RX UE uses the first or second cycle shift from the cycle shift pair associated with the selected PSFCH index i.

[0086] Depending on which RX UE selects the PSFCH with index i, the Tx UE can distinguish between the HARQ feedback of different RX UEs (via the RX UE identifier, e.g., groupcast option 2) and the HARQ feedback for the Tx UE (via the Layer 1 ID of the Tx UE, e.g., unicast). ID For =0, the RX UE uses the Layer 1 ID Tx UE identifier T ID , select the same PSFCH index i for the NACK-only feedback based only on the PSFCH index i.

[0087] The prioritization of simultaneous PSFCH transmission / reception is specified in TS38.213.

[0088] In the case of PSFCH transmission or reception with HARQ-ACK information, the priority value of the PSFCH is equal to the priority value indicated by the SCI format 1-A associated with the PSFCH.

[0089] For PSFCH transmissions with contention information, the priority value of the PSFCH is equal to the minimum priority value determined by the corresponding SCI format 1-A for the conflicting resource.

[0090] In case of PSFCH reception with contention information, the priority value for the PSFCH is equal to the priority value determined by the corresponding SCI format 1-A for the conflicting resource.

[0091] Currently, in the SL-U design, it is still open how to associate channel access priorities for transmissions on each SL channel.

[0092] The fundamental question to be addressed for PSFCH transmission by SL-U UE without initiated COT is: Which CAPC should be used for LBT of PSFCH transmission?

[0093] Various examples of the present disclosure seek to enable a CAPC decision for a PSFCH that considers both coexistence fairness with other devices and channel access opportunity to transmit the PSFCH.

[0094] In various examples of the present disclosure, the SL Rx UE may select an appropriate CAPC for the PSFCH transmission from the first CAPC and the second CAPC, taking into account the result of the LBT for at least one recent PSFCH transmission.

[0095] The SL Rx UE may determine the first and second CAPCs using at least any combination of the following: A first CAPC may be predefined or configured with a higher p-value for channel access to transmit the PSFCH than a second CAPC. In one example, a first CAPC may be predefined / configured with a high p-value (e.g., p=4) and a second CAPC may be predefined / configured with a low p-value (e.g., p=1). The first / second CAPC may be determined based on the priority of the SL transmission associated with the PSFCH for the SL Rx UE. In one example, the first and second CAPC may be determined based on the lowest and highest priority of the SL transmissions associated with the PSFCH, respectively.

[0096] Optionally, if the p-value of the second CAPC is not lower than the first CAPC or is not lower than the offset amount for the first CAPC, the second CAPC is selected as the lower p-value, i.e., p 2nd =max{1,p 1st -p offset}, and the offset p offset may be predefined during standardization or configured for the SL Rx UE.

[0097] In another example, the first CAPC may be determined based on the highest priority (or lowest priority) of the SL transmissions associated with the PSFCH, while the second CAPC may be configured with a lower p value than the first CAPC, and the p value of the second CAPC may be set to a default value (i.e., p=1), or may be set to an offset lower than the offset of the first CAPC (but not less than the minimum p value), i.e., p 2nd =max{1,p 1st -p offset}, where the offset p offset may be predefined during standardization and may be configured in the SL Rx UE.

[0098] In some examples, an SL UE may obtain the priority of an SL transmission by detecting the first stage SCI of the SL transmission and associate a PSFCH with the SL transmission based on the (pre-)configured PSSCH to PSFCH timing.

[0099] The SL UE may select either the first CAPC or the second CAPC for PSFCH transmission based on a specific selection criterion / metric, and each selection criterion / metric may be designed based on the channel access status of the immediately preceding PSFCH transmission. For example, by default, the SL UE may use the first CAPC for PSFCH transmission, but shall select the second CAPC for PSFCH transmission if at least one of the following conditions is met: The resources allocated for PSFCH transmission are secondary PSFCH resources for retransmission of HARQ-ACKs that cannot be transmitted on the primary PSFCH resources if intended for a failed LBT (see, for example, FIG. 12). Here, it is assumed that if a HARQ-ACK on the PSFCH cannot be transmitted on the primary PSFCH resources if intended for a failed LBT, the secondary PSFCH resources will be configured to retransmit the HARQ-ACK. · The LBT success rate of the immediately preceding xPSFCH transmission is lower than y%. The number of LBT successes for the immediately preceding xPSFCH transmissions is less than the yLBT successes (see, for example, FIG. 11). o Alternatively, the xPSFCH transmissions may correspond to the same HARQ process, which means that SL Rx UEs may increase the channel access priority for the retransmission PSFCH. Note that the values ​​of x and y may be predefined in the specification or may be preconfigured by the network.

[0100] Advantageously, examples of the present disclosure may enable CAPC selection for a PSFCH based on the channel access status of recent PSFCH transmissions to make a better trade-off between channel access opportunities for the PSFCH and coexistence fairness with other devices. Examples may enable upgrading to a CAPC with higher channel access priority to improve channel access chances for a PSFCH transmission when HARQ-ACK feedback is blocked due to an LBT failure in a previous PSFCH transmission.

[0101] In some examples of the present disclosure, an SL Rx UE may generally select an appropriate channel access priority based on the lowest priority of its associated SL transmission, such as a legacy NR-U UE for PDSCH / PUSCH transmission, instead of the highest priority (of the associated SL transmission), to ensure coexistence fairness with other devices. Only if the channel access success rate is low or an LBT failure occurs for a PSFCH transmission, the SL Rx UE upgrades its CAPC for HARQ ACK / NACK (re)transmissions to improve channel access opportunities for the SL Rx UE.

[0102] Examples of the present disclosure may enable SL Rx UEs to conditionally upgrade CAPC for PSFCH transmission, thereby making a better trade-off between channel access opportunities for PSFCH and coexistence fairness with other devices.

[0103] Figure 7 illustrates generally one example of a method 700 of the present disclosure. One or more of the features described in connection with Figure 7 may also be found in one or more of the other figures. During the discussion of Figure 7, for purposes of explanation, reference numerals of features shown in other figures (at least not Figures 11 and 12) will be used.

[0104] 7 and functions described below may represent actions in a method, functions performed by an apparatus, and / or sections of instructions / code in a computer program. It will be appreciated that the functions described below may be implemented by various means, such as hardware, firmware, and / or software including one or more computer program instructions. For example, one or more of the functions described below may be performed by a suitably configured apparatus (such as a UE, e.g., an SL Rx UE, comprising means for performing the functions described below). One or more of the functions described below may be implemented by a suitably configured computer program (such as a computer program including computer program instructions that embody the functions described below and that can be stored by a memory storage device and executed by a processor).

[0105] The method of Figure 7 as well as the functions described below may be performed by / in a single physical entity, such as an apparatus as described with reference to Figure 8. The functions described may also be implemented by a computer program as described with reference to Figure 9.

[0106] In block 701, information indicative of a channel access priority (p) for a transmission (205) over a transmission channel (203) is determined based at least in part on at least one of the following: information indicative of the status of at least one previous transmission (204) over the transmission channel (203); and Information indicating the cast type of the received transmission (202) associated with the transmission (205).

[0107] For purposes of discussion of various examples of the present disclosure below, and for ease of explanation. The transmission channel may be referred to as the Physical Sidelink Feedback Channel (PSFCH). A transmission may be referred to as a PSFCH transmission, eg, a current / next PSFCH transmission or a PSFCH occurrence. The at least one previous transmission may be referred to as the at least one previous or most recent PSFCH transmission, or the at least one previous PSFCH occurrence. This may also be referred to as the x number of times immediately preceding the PSFCH transmission, where x is an integer > 0. As used herein, the term "immediately preceding" may refer to "immediately preceding" or immediately recent, for example, the x immediately preceding PSFCH transmissions may refer to the two PSFCH opportunities immediately preceding the current / next PSFCH opportunity (where the channel access priority is to be determined relative to the current / next PSFCH transmission, which is the PSFCH transmission for which the channel access priority is to be determined).

[0108] It should be understood that the basic concepts of this disclosure may be applicable to transmission channels other than the PSFCH, transmissions other than the PSFCH transmission, and at least one previous transmission other than the at least one previous PSFCH transmission. For example, in some examples, the transmission channel is at least one selected from the following group: Physical Sidelink Shared Channel (PSSCH), and Synchronous Signal Block (SSB).

[0109] In some examples, the transmission channel is in an unlicensed spectrum.

[0110] In some examples, the information indicative of channel access priority indicates at least one selected from the group consisting of: Priority classes for use in procedures for determining whether a transmitting device (e.g., SL Rx UE) is allowed to transmit over a transmission channel, in particular in Listen Before Talk (LBT) procedures, etc.; Priority classes for use in unlicensed bands; Channel Access Priority Class (CAPC) a contention window (CW) (e.g., determined at least in part based on the determined CAPC and Table 1); and Channel Occupancy Time (COT) (eg, determined based at least in part on the determined CAPC and Table 1).

[0111] In some examples, the transmission of information indicative of at least one previous state of the information is selected from at least one group. a channel access status of at least one previous transmission, such status may indicate whether the at least one previous transmission failed or succeeded; whether the LBT procedure for transmitting at least one previous transmission failed or succeeded; the LBT success rate for one or more previous transmissions; the number of LBT successes for one or more previous transmissions; whether the transmission includes a retransmission of information that was not successfully transmitted via at least one previous transmission; allocation of resources for transmission (e.g., PSFCH resources for PSFCH transmissions such as HARQ feedback), where resources are allocated for retransmitting information that was not successfully transmitted via at least one previous transmission (such resources correspond to "secondary" resources allocated to, e.g., SL Rx UEs, to effect a transmission, following a previously allocated "primary" resource for attempting to transmit a transmission, where the previous transmission was not successful and "secondary" resources need to be allocated for retransmitting the previously failed transmission); and Whether the PSFCH transmission is within a channel occupation time (COT) shared by the UE (i.e., another UE). For example, if an SL Rx UE may detect a COT shared by an SL Tx UE, but the SL Rx UE is not a responder in the COT, it may be allowed to upgrade its CAPC for the PSFCH transmission.

[0112] In some examples, information indicative of the status of at least one previous transmission is determined.

[0113] In some examples, determining the information indicative of a channel access priority for the transmission includes: The first candidate priority class for transmission (p 1st ) and The second candidate priority class for transmission (p 2nd ), and Selecting at least one of the first candidate priority class and the second candidate priority class.

[0114] For example, the information indicating the determined channel access priority may be a priority class (p), and the determined priority class is the selected first or second candidate priority class, i.e., p=p 1st or p 2nd , where one of the first or second candidate priority classes is selected according to one or more selection criteria / metrics as described below.

[0115] In some examples, the first and / or second candidate priority classes are predefined, eg, they may be set in a standard such as a 3GPP Technical Specification (TS).

[0116] In some examples, the first candidate priority class and / or the second candidate priority class are configured in the device. For example, the gNB can determine the first candidate priority class and / or the second candidate priority class, e.g., based on traffic information. The gNB can configure the SL Rx UE with the first and / or second candidate priority class. By configuring the SL Rx UE with the first and / or second candidate priority class, this reduces implementation complexity by avoiding the SL Rx UE having to determine the first and / or second candidate priority class for itself.

[0117] In some examples, the first candidate priority class is configured to have a lower priority (i.e., a higher p value / CAPC value) than the priority of the second candidate priority class, i.e., p 1st >p2nd is.

[0118] In some examples, the first candidate priority class is determined based at least in part on the lowest channel access priority of one or more received SL transmissions associated with the transmission. For example, the transmission may be a PSFCH transmission, and the one or more received SL transmissions may be one or more PSCCH+PSSCH transmissions (e.g., PSCCH+PSSCH A and PSCCH+PSSCH B) received by the SL Rx UE, each of the one or more PSCCH+PSSCH transmissions having its own channel access priority value (e.g., p A and p B ), and as such is indicated by SCI format 1-A carried by the PSCCH. It should be understood that a PSCCH+PSSCH transmission is associated with a PSFCH transmission by the PSFCH transmission providing feedback (e.g., HARQ feedback) for the PSCCH+PSSCH transmission. The first candidate priority class is p 1st =min(p A ,p B ) can be.

[0119] In some examples, the second candidate priority class is determined based at least in part on the highest channel access priority of one or more received SL transmissions associated with the transmission, i.e., p 2nd =max(p A ,p B ) is determined to be

[0120] In some examples, the second candidate priority class is determined based at least in part on the first candidate priority class. For example, 2nd =max{1,p 1st -p offset} and p offsetis a property class offset parameter. The value of the offset parameter may be predefined during standardization or configured in the SL Rx UE. For example, the priority class offset parameter value may be determined by the gNB based on, for example, the channel access requirements or traffic type of the SL Rx UE, and the gNB may provide the priority class offset parameter value to the SL Rx UE so that the SL Rx UE may determine the second candidate priority class. For example, p 1st After determining p 2nd =max{1,p 1st -p offset} based on p 2nd can be determined.

[0121] In some examples, at least one of the first and second candidate priority classes is selected according to at least one selection criterion.

[0122] In some examples, the at least one selection criterion includes selecting the first candidate priority class by default.

[0123] In some examples, the at least one selection criterion includes selecting the second candidate priority class in response to at least one of the following: determining whether the transmission (e.g., a PSFCH transmission) is a retransmission of at least a portion of a previously attempted transmission (e.g., a previous attempt to transmit the same PSFCH transmission or at least a portion thereof); determining whether the transmission (e.g., a PSFCH transmission) is a retransmission of a previously attempted transmission of feedback (e.g., a Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK) or a Negative Acknowledgement (NACK)); determining a type of resource for the transmission (e.g., determining whether the transmission will use one or more "secondary" PSFCH resources to retransmit a PSFCH transmission that was previously attempted to be transmitted via a "primary" PSFCH resource); determining whether the resources allocated for the transmission are resources allocated for retransmitting information that was not successfully transmitted via at least one previous transmission; and Determining whether a HARQ-ACK of one or more previous transmissions cannot be transmitted via the allocated resources earlier due to an LBT failure.

[0124] In some examples, the at least one selection criterion comprises selecting the second candidate priority class in response to determining whether an LBT success rate for a number (x) of previous transmissions is less than a threshold LBT success rate value (y%). The LBT success rate may be determined by a transmitting device (e.g., an SL Rx UE) performing the LBT procedure and each of the following may be predefined or configured in the SL Rx UE:

[0125] In some examples, the at least one selection criterion comprises selecting the second candidate priority class in response to determining whether a number of LBT successes (x) for some previous transmissions is less than a threshold (y). The threshold number of LBT successes (y) and the number of previous transmissions (x) may each be predefined or configured in the SL Rx UE such that the SL Rx UE may evaluate whether the number of LBT successes in the immediately preceding x previous transmissions is less than the threshold number of LBT successes (y).

[0126] In some examples, the at least one selection criterion comprises selecting the second candidate priority class in response to determining whether the received transmission is unicast.

[0127] In some examples, configuration information and / or parameters are received to enable the device to determine information indicative of channel access priority for transmission. For example, a SL Rx UE may comprise one or more of the following: The value p of the first candidate priority class 1st , The value p of the second candidate priority class 2nd, The value of the priority class offset parameter p offset , LBT success rate threshold (y%), Threshold for the number of successful LBTs (y), The value of the number of previous transmissions (x), and An indication as to the cast type of the received transmission associated with the transmission (e.g., whether it is unicast or groupcast).

[0128] In some examples, configuration information is received to enable determination of at least one selection criterion to be applied (i.e., for selecting one of the first candidate priority class and the second candidate priority class).

[0129] In some examples, a decision on at least one selection criterion to apply is made based at least in part on the cast type of the received transmission associated with the transmission (e.g., whether the received SL transmission / PSSCH transmission associated with the PSFCH transmission is a unicast transmission to a single UE or a groupcast transmission to multiple UEs).

[0130] In some examples, the received transmission associated with the transmission comprises a received PSSCH transmission associated with the PSFCH transmission.

[0131] In some examples, a channel access procedure for transmitting a transmission (e.g., an LBT) is performed based at least in part on determined information indicative of channel access priority. For example, the determined information indicative of channel access priority may be a CAPC to be used in the LBT procedure for accessing the PSFCH to transmit the PSFCH transmission, and the CAPC is used to determine values ​​of COT and CW to be used in the LBT procedure.

[0132] The functionality described above, particularly following the description of FIG. 7, as well as the functionality described below with respect to FIGS. 10-12, may be implemented in hardware, software, or a combination of hardware and software.

[0133] Various, but not necessarily all, examples of the present disclosure provide both methods and corresponding apparatuses that include various modules, means, or circuits that provide functionality for performing / applying the operations of the methods. The modules, means, or circuits may be implemented as hardware, or as software or firmware executed by a computer processor. In the case of firmware or software, examples of the present disclosure may be provided as a computer program product that includes a computer-readable storage structure embodying computer program instructions (i.e., software or firmware) for execution by a computer processor.

[0134] FIG. 8 schematically shows a block diagram of an apparatus 10 for performing the methods, processes, procedures, and signaling described in this disclosure, i.e., at least the functionality described above following the description of FIG. 7, and the functionality described below with respect to FIGS. 10-12.

[0135] The component blocks of FIG. 8 are functional and the functions described may be performed by a single physical entity.

[0136] The apparatus comprises a controller 11 which may be provided in a device such as a UE 110, for example an SL Rx UE configured to receive SL transmissions initiated by an SL Tx UE configured to initiate SL communication / transmissions.

[0137] The controller 11 may be embodied by a computing device, particularly as described above. In some, but not necessarily all, embodiments, the device may be embodied as a chip, chipset, circuit, or module, i.e., for use in any of the foregoing. As used herein, "module" refers to a unit or device that excludes specific parts / components that would be added by an end manufacturer or user.

[0138] The implementation of the controller 11 may be as a controller circuit, may be implemented solely in hardware, may have certain aspects in software including solely in firmware, or may be a combination of hardware and software (including firmware).

[0139] The controller 11 may be implemented using instructions that enable hardware functions, for example by using executable instructions of a computer program 14 in a general-purpose or special-purpose processor 12, which executable instructions may be stored in a computer-readable storage medium 13, such as a memory or a disk, and executed by such processor 12.

[0140] The processor 12 is configured to read from and write to memory 13. The processor 12 may also comprise an output interface through which data and / or commands are output by the processor 12 and an input interface through which data and / or commands are input to the processor 12. The apparatus may be coupled to or comprise one or more other components 15 (e.g., wireless transceivers, sensors, input / output user interface elements, and / or other modules / devices / components for inputting and outputting data / commands, among others).

[0141] Memory 13 stores computer program 14, which includes instructions (computer program instructions / code) that, when loaded into processor 12, control the operation of device 10. The instructions in computer program 14 provide logic and routines that enable the device to perform the methods, processes, and procedures described in this disclosure and illustrated in Figures 7 and 10-12. Processor 12 can load and execute computer program 14 by reading memory 13.

[0142] The computer program instructions may be included in a computer program, a non-transitory computer-readable medium, a computer program product, or a machine-readable medium. As used herein, the term "non-transitory" is a limitation of the medium itself (i.e., tangible as opposed to a signal) as opposed to a limitation to data storage persistence (e.g., RAM vs. ROM). In some, but not necessarily all, examples, the computer program instructions may be distributed across multiple computer programs.

[0143] Although memory 13 is illustrated as a single component / circuit, it may be implemented as one or more separate components / circuits, some or all of which may be integrated / removable and / or provide permanent / semi-permanent / dynamic / cache storage.

[0144] Although processor 12 is illustrated as a single component / circuit, it may be implemented as one or more separate components / circuits, some or all of which may be integrated / removable. Processor 12 may be a single-core or multi-core processor.

[0145] An apparatus may include one or more components for implementing the methods, processes, and procedures described in this disclosure and illustrated in Figures 7 and 10-12. It is contemplated that the functions of these components may be combined in one or more components or performed by other components of equivalent functionality. A description of a function should also be considered to disclose any means suitable for performing that function. Where a structural feature is described, it may be replaced by a means for performing one or more of the structural feature's functions, regardless of whether that function or functions are explicitly or implicitly described.

[0146] While example apparatuses are described above with respect to comprising various components, it should be understood that the components may be embodied as or controlled by one or more processing elements or corresponding controllers or circuits, such as processors, of the apparatus. In this regard, each of the above-described components may be one or more of any device, means, or circuit embodied in hardware, software, or a combination of hardware and software configured to perform the corresponding function of the respective above-described component.

[0147] An apparatus may be, for example, a client device, a server device, a mobile cellular telephone, a base station in a mobile cellular telecommunications system, a wireless communication device, a hand-portable electronic device, a location / position tag, a hypertag, etc. An apparatus may be embodied by a computing device, particularly as described above. However, in some examples, an apparatus may be embodied as a chip, chipset, circuit, or module, i.e., for use in any of the foregoing.

[0148] In one example, the apparatus is embodied on a handheld portable electronic device such as a mobile phone, mobile communication device, wearable computing device, or personal digital assistant, which may further provide one or more audio / text / video communication functions (e.g., telecommunication, video communication, and / or text transmission (Short Message Service (SMS) / Multimedia Message Service (MMS) / email transmission) functions), interactive / non-interactive viewing functions (e.g., web browsing, navigation, TV / program viewing functions), music recording / playback functions (e.g., Moving Picture Experts Group-1 Audio Layer 3 (MP3) or other format and / or (frequency modulation / amplitude modulation) radio broadcast recording / playback), download / transmit data functions, image capture functions (e.g., using a (e.g., built-in) digital camera), and gaming functions, or any combination thereof.

[0149] In some instances, at least one processor 12; and at least one memory 13 storing instructions that, when executed by the at least one processor 12, cause the apparatus to at least: determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, at least, information indicating at least one status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; determining, based in part on the

[0150] The above-described devices may find application as enabling components of telecommunications devices, telecommunications systems, tracking systems, automotive systems, electronic systems including consumer electronic products, distributed computing systems, media systems for generating or rendering media content including audio content, visual content, and audiovisual content, and mixed reality, mediated reality, virtual reality, and / or augmented reality, personal systems including personal health systems or personal fitness systems, navigation systems, user interfaces also known as human-machine interfaces, networks including cellular, non-cellular, and optical networks, ad hoc networks, the Internet, the Internet of Things (IoT), Vehicle-to-Everything (V2X), virtual networks, and related software and services.

[0151] The apparatus may be provided in an electronic device, such as a mobile terminal, according to examples of the present disclosure. However, it should be understood that a mobile terminal is merely an example of an electronic device that would benefit from example implementations of the present disclosure and therefore should not be construed as limiting the scope of the present disclosure thereto. In some example implementations, the apparatus may be provided in a mobile terminal, other types of electronic devices such as, but not limited to, mobile communication devices, location tags, hand-portable electronic devices, wearable computing devices, personal digital assistants (PDAs), pagers, mobile computers, desktop computers, televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices, and other types of electronic systems may readily use examples of the present disclosure. Furthermore, devices may readily use examples of the present disclosure regardless of whether they are intended to provide mobility.

[0152] Various examples of the present disclosure may take the form of computer program instructions. Such computer program instructions may be provided to one or more processors, processing circuits, or controllers, such that the instructions, when executed on the one or more processors, processing circuits, or controllers, generate means for implementing the functions described above, such that the methods may be computer-implemented.

[0153] 9 illustrates a computer program 14 that may be transmitted via a delivery mechanism 20. The delivery mechanism 20 may be any suitable delivery mechanism, such as a machine-readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a solid-state memory, a recording medium such as a Compact Disc Read Only Memory (CD-ROM) or a Digital Versatile Disc (DVD), or an article of manufacture embodying the computer program 14. The delivery mechanism may also be a signal configured to reliably transfer the computer program. A device may receive, propagate, or transmit the computer program as a computer data signal.

[0154] In some examples of the present disclosure, a computer program is provided comprising instructions that, when executed by an apparatus (e.g., apparatus 10, which may be implemented in UE 110), cause the apparatus to perform at least the following, or to perform at least the following: determining information indicative of channel access priority for a physical sidelink feedback channel (PSFCH) transmission, the information comprising at least information indicating the status of at least one immediately preceding PSFCH transmission; or information indicating a cast type of a sidelink (SL) transmission associated with the PSFCH transmission; determining, based in part on

[0155] References to a "computer program," "computer-readable storage medium," "computer program product," "tangibly embodied computer program," etc., or to a "controller," "computer," "processor," etc., should be understood to encompass computers having different architectures, such as single / multi-processor architectures and sequential (von Neumann) / parallel architectures, as well as special purpose circuitry, such as field programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices, and other devices. References to a computer program, instructions, code, etc., should be understood to encompass software or firmware for a programmable processor, such as the programmable contents of a hardware device, or configuration settings for a fixed function device, gate array, or programmable logic device, etc., whether or not the instructions for the processor.

[0156] As used in this application, the term "circuit" may refer to one or more or all of the following: (a) Hardware-only circuit implementation (e.g., implementation in analog and / or digital circuits only). (b) Combinations of hardware circuits and software, e.g. (where applicable) (i) a combination of analog and / or digital hardware circuitry and software / firmware; (ii) Any portion of a hardware processor with software (including a digital signal processor), software, and memory that cooperate to cause a device such as a mobile phone or server to perform various functions. (c) A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (e.g., firmware) to operate; however, the software may be absent when not required for operation.

[0157] This definition of circuit applies to all uses of the term in this application, including any claims. As a further example, as used in this application, the term circuit also encompasses simply a hardware circuit or processor and its (or their) accompanying software and / or firmware implementations. The term circuit also encompasses, for example, a baseband integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to certain claim elements.

[0158] 10 shows a flowchart of a method 1100 for selecting a CAPC for a PSFCH transmission. The method may be performed by a UE such as an SL-U Rx UE (i.e., a UE acting as a receiver for sidelink transmissions in the unlicensed spectrum from an SL-U Tx UE).

[0159] In block 1101, the SL Rx UE obtains parameter configuration information for CAPC selection. Such parameter configuration information may comprise one or more of the aforementioned parameters used in determining and applying the selection criteria / metrics to apply and evaluate the selection criteria / metrics. In this regard, the parameter configuration information may include: First candidate CAPC p 1st , Second candidate CAPC p 2nd , Offset p offset , LBT success rate threshold (y%), Threshold for the number of successful LBTs (y), The value of the previous send count (x).

[0160] The network 100 and / or the gNB 120 may provide configuration information for CPAC selection (e.g., first and / or second CAPC or offset p offset) and configure the SL Rx UE with it. The configuration information may be determined taking into consideration, for example, implementation complexity, channel access opportunities, and / or coexistence fairness between different RATs / devices.

[0161] In one implementation, to reduce the complexity of UE implementation, the first CAPC and / or the second CAPC may be configured by the network, and thus the SL Rx UE does not need to determine the CAPC (e.g., based on traffic information).

[0162] In another implementation, the first CAPC may be configured with the highest CAPC (i.e., the lowest channel access priority, p=4) to ensure coexistence fairness with other devices, while the second CAPC may be configured with the lowest CAPC (i.e., the highest channel access priority, p=1) to increase channel access opportunities, such as in cases of HARQ-ACK / NACK retransmissions or low channel access success rates.

[0163] In a further implementation, the offset p between the second CAPC and the first CAPC offset may be determined based on the channel access requirements or traffic type of the UE, for example, the offset p offset may be set to a high / large value (e.g., 2) in the case of Ultra Reliable Low Latency Communication (URLLC), and may be set to a low / small value (e.g., 1) otherwise.

[0164] As described below with respect to block 1108, the parameter values ​​(e.g., x and y) may be used in section criteria / metrics to determine whether the first CAPC or the second CAPC is selected for PSFCH transmission. The parameter values ​​may be determined based on channel access requirements, e.g., the larger the value of y, the higher the channel access requirement, the larger the value of x, the longer the decision observation time.

[0165] One or more selection metrics may also be configured in the SL-U Rx UE for PSFCH transmission in block 1101. The selection metric applied by the SL-U Rx EU may be based at least in part on the channel access status (e.g., whether the previous PSFCH transmission failed / did not fail) or the UE type (e.g., URLLC UE) or traffic type.

[0166] In some implementations, the parameter configuration information may be predefined in a specification or may be configured in the SL-U Rx UE by the network or via another SL UE.

[0167] In block 1102, the SL-U Rx UE monitors the PSCCH to determine priority and resource allocation for SL transmissions from the SL-U Tx UE.

[0168] Priority may be determined based on traffic type and Quality of Service (QoS) as defined in Section 5.4.3.3 of [12, TS 23.287]. The SL-U Rx UE can discover the priority and resource allocation via the first stage SCI as described above.

[0169] In some implementations, SL transmissions may be limited to unicast or groupcast transmissions towards SL-U Rx UEs. Determining such a cast type may be identified by detecting the cast type and destination ID in the second stage SCI provided in Table 2.

[0170] In block 1103, the SL-U Rx UE determines the PSFCH opportunity per SL transmission (i.e., PSSCH) based on the configured PSSCH to PSFCH timing by detecting the HARQ feedback enable / disable indicator in the second stage SCI provided in Table 2 if HARQ-ACK feedback is expected for the PSSCH.

[0171] In some implementations, the SL-U RX UE may determine the frequency-domain location of the PSFCH transmission for HARQ feedback of the SL transmission based on the lowest physical resource block (PRB) index of the resource allocation for the SL transmission. The SL-U RX UE may also determine the time-domain location of the HARQ feedback based on the predefined PSSCH-to-PSCCH timing for the SL transmission discussed above in the overview of SL HARQ operation.

[0172] In some implementations, the primary and secondary PSFCH opportunities may be configured for HARQ-ACK feedback associated with SL transmissions. If the HARQ-ACK cannot be transmitted on the primary PSFCH opportunity when intended, e.g., due to a failure of the LBT channel access procedure, the SL-U Rx UE may then attempt to transmit (i.e., retransmit) the HARQ-ACK on the secondary PSFCH opportunity.

[0173] In block 1104, the SL Rx UE selects a first candidate CAPC p for PSFCH transmission. 1st and the second candidate CAPC p 2nd Determine.

[0174] In this regard, in block 1105, if the first and second candidate CAPCs are predefined or configured in the SL-U Rx UE, the SL-U Rx UE uses the predefined / configured first and second candidate CAPCs. Otherwise, in block 1106, the SL-U Rx UE determines the first and / or second CAPCs for the PSFCH transmission at a given opportunity based on the priority of the associated SL transmission, such as in the manner discussed above.

[0175] In block 1107, the SL-U Rx UE selects the first candidate CAPC(p) for use as the CAPC(p) for the PSFCH transmission. 1st ) and the second candidate CAPC(p2nd ) The selection is based on one or more selection criteria / metrics.

[0176] In some implementations, the selection metric to be applied by the SL-U Rx UE may be predefined or configured in the SL Rx UE.

[0177] In block 1108, the SL-U Rx UE evaluates the selection metric to determine in block 1109 whether the selection metric is met and therefore whether to select. Either the first candidate CAPC to use for PSFCH transmission, as in block 1110, or the second candidate CAPC to use for PSFCH transmission, as in block 1111.

[0178] In one implementation, the selection metric may be implemented taking into account the channel access status of the last x PSFCH transmissions.

[0179] By default, the SL-U Rx UE selects the first candidate CAPC for PSFCH transmission if a second CAPC is not selected based on any of the selection metrics configured below.

[0180] The selection metrics may include: Metric 1-M1: If the PSFCH resource is a "secondary" PSFCH resource (i.e., a PSFCH resource assigned to an SL-U Rx UE for retransmission of at least one HARQ-ACK on the PSFCH for which a previous transmission via the "primary" PSFCH resource was attempted but was unsuccessful (e.g., due to a failed LBT)), the SL Rx UE selects the second candidate CAPC. In some cases, the first / primary PSFCH resource may use a Type 2 channel access procedure if there is an available COT, but for the second / secondary PSFCH resource, the UE may have to select a CAPC to initiate a Type 1 LBT procedure, e.g., a second candidate CPAC if there is no available COT. Metric 2-M2: If the LBT success rate of the last x PSFCH transmissions is lower than a threshold success rate (y%), the SL-U Rx UE selects the second candidate CAPC. In one example, the values ​​of x and y may be set to 2 and 50, respectively. Metric 3-M3: If the number of LBT successes for the last x PSFCH transmissions is less than y, the SL Rx UE selects the second candidate CAPC. In one example, the values ​​of x and y may be set to 2 and 1, respectively. Metric 4-M4: If the PSFCH transmission is within the COT initiated by another UE while the SL Rx UE is not a COT responder, the SL Rx UE selects the second candidate CAPC. The SL Rx UE can detect the COT information by monitoring the SCI of another UE.

[0181] Following the selection of either the first or second candidate CAPC to be used as the CAPC for the PSFCH transmission, the SL-U Rx UE determines channel access parameters based on the selected CAPC for the PSFCH transmission. The channel access parameters may include CW and / or COT, which may be determined based on the selected CAPC and the information provided in Table 1.

[0182] Then, in block 1112, the Rx UE performs an LBT (e.g., a Type 1 LBT) using the determined channel access parameters, i.e., attempts to gain the “right” to access the channel to send a PSFCH transmission.

[0183] FIG. 11 illustrates an example of determining CAPC for PSFCH transmission according to the present disclosure.

[0184] In this example, sidelink resource 2011 is allocated for sidelink transmission 2021 PSCCH / PSSCH A in slot #(n-3) destined for the SL Rx UE. Sidelink resource 2012 is allocated for sidelink transmission 2022 PSCCH / PSSCH B in slot #(n-4) destined for the SL Rx UE.

[0185] Based on the configured PSSCH to PSFCH timing, HARQ feedbacks 2051 and 2052 of two PSSCHs 2021 and 2022, respectively, are required for the SL Rx UE on the PSFCH 203 in slot #n.

[0186] The first and second candidate CAPC values ​​p for PSFCH transmission 1st and p 2nd If the CAPCs (referred to as the first and second CAPCs) are not pre-determined or configured in the SL Rx UE, the SL Rx UE may determine the priority of the SL transmissions 2021 and 2022 relative to the PSFCH transmissions 2051 and 2052 on the PSFCH 203. 1st and p 2nd , i.e., the SL Rx UE determines the PSSCH A(=p A ) and PSSCH B(p B ) to determine the priority.

[0187] In this example, the first candidate CAPC p 1st is the lowest priority of PSSCH A / B, i.e., p 1st =min(p A ,p B ) is determined based on the second candidate CAPC p 2nd is the highest priority of PSSCH A / B, i.e., p 2nd =max(p A ,p B ) is determined based on

[0188] In this example, selection metric M3 is applied, i.e., the SL Rx UE selects p=p for PSFCH transmission based on selection metric M3. n Select a CAPC with p n is the first candidate CAPC p 1st The second candidate, CAPC p 2nd and the LBT status of the previous PSFCH transmission is LBTP in slot #(n-4) and slot #(n-8). SFCH 2041 and 2042, i.e.:

number

[0189] In this particular example, for selection metric M3, the value of x (the number of previous PSFCH transmissions) is set to 2 and the value of y (the threshold number of LBT successes) is set to 1.

[0190] Therefore, if the LBT fails for the previous PSFCH transmissions 2041 and 2042 in both slot #(n-4) and slot #(n-8), the SL Rx UE will select the second candidate CAPC for the channel access procedure of the PSFCH transmission in slot #n, i.e., the SL Rx UE will select p=p 2nd Otherwise, the SL Rx UE selects the first candidate CAPC for the channel access procedure of the PSFCH transmission in slot #n. In other words, the SL Rx UE will select p=p if the LBT fails the PSFCH transmission in only one of the previous PSFCH transmissions 2041 and 2042, or if the LBT fails neither of the previous PSFCH transmissions 2041 and 2042. 1st Select .

[0191] According to the evaluation of the selection metric, p 1st or p 2ndFollowing the selection of either CAPC or PSFCH, the SL Rx UE uses the determined CAPC (i.e., the selected p 1st or p 2nd ) to perform the LBT procedure.

[0192] FIG. 12 illustrates a further example of determining a CAPC for a PSFCH according to the present disclosure. In this embodiment, it is as follows. First candidate CAPC p 1st (called the first CAPC) is the lowest priority of the associated PSSCH A / B 2021 and 2022, i.e., p 1st =min(p A , p B ) is determined based on Second candidate CAPC p 2nd (called the second CAPC) is the lowest possible p-value, i.e., p 2nd = 1, and The selection metric M1 is applied to the CAPC selection.

[0193] By default, the first candidate CAPC p 1st is selected for channel access to transmit PSFCH transmissions 2051 and 2052 on PSFCH 2031 in slot #n, i.e., p=p 1stHowever, in this particular example, since a previous transmission of HARQ feedback 2041 on the PSFCH 2032 for PSCCH / PSSCH A 2021 was blocked in slot #(n-4) due to an LBT failure (where such previous PSFCH transmission 2041 was assigned the "primary" PSFCH resource 2061), the secondary PSFCH resource 2062 in slot #n is configured to retransmit HARQ feedback 2051 for PSCCH / PSSCH A 2021 on the PSFCH 2031. In this scenario, based on the selection metric M1, the SL Rx UE selects a second candidate CAPC for transmitting the PSFCH transmission 2051 on the PSFCH 2031 in slot #n, i.e., the SL Rx UE selects p=p 2nd Therefore, the PSFCH (i.e., in this example, p=p 2nd Upon determining the CAPC for the PSFCH 2051, the SL Rx UE performs the LBT procedure based on the determined CAPC and attempts to transmit the PSFCH transmission 2051 on the PSFCH 2031.

[0194] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0195] Features set out in the preceding description may be used in combinations other than those explicitly set out.

[0196] Although functions are described with reference to particular features, these functions may be performed by other features, whether or not described.

[0197] Although features have been described with reference to particular examples, these features may also be present in other examples, whether or not described. Thus, a feature described in connection with one example / aspect of the present disclosure may include any or all of the features described in connection with another example / aspect of the present disclosure, and vice versa, to the extent not mutually inconsistent.

[0198] While various embodiments of the present disclosure have been described in the preceding paragraphs, it should be understood that modifications to the given embodiments may be made without departing from the scope of the present invention as defined in the claims. For example, various examples in the above examples are disclosed with respect to methods performed by an SL-U Rx UE (e.g., a UE configured for SL communication in an unlicensed band that functions as a receiver for SL transmissions initiated by an SL-U Tx UE), and the transmission for which information indicative of channel access priority is determined is a PSFCH transmission (e.g., HARQ feedback) transmitted on the PSFCH. However, it should be understood that examples of the present disclosure are not limited to determining a priority for a PSFCH transmission, and indeed examples are not limited to SL communication and operation in unlicensed bands, in which the transmission (for which information indicative of channel access priority is determined) is a PSFCH transmission. In some examples, the transmission channel may be a PSSCH or a synchronization signal block (SSB).

[0199] Although various of the above examples have been disclosed with reference to determining a first candidate CPAC value and a second candidate CPAC value and selecting one of the first and second CPAC values, it should be appreciated that in some examples, one or more additional candidate CPAC values ​​may be determined and one or more of the plurality of candidate CPAC values ​​may be selected.

[0200] The term "comprise" is used herein in an inclusive rather than exclusive sense, i.e., any reference to X containing Y indicates that X may contain only one Y or may contain multiple Ys. Where it is intended to use "comprise" in the exclusive sense, this will be clear in context by reference to "comprising only one" or by use of "consisting."

[0201] In this description, the terms "connect," "couple," and "communicate," along with their derivatives, mean operatively connected / coupled / communicating. It is understood that any number or combination of intervening components may be present (including no intervening components), i.e., may be present to provide a direct or indirect connection / coupling / communication. Any such intervening components may include hardware and / or software components.

[0202] As used herein, the term "determine / determining" (and grammatical variations thereof) may include at least: calculate, computing, process, derive, measure, investigate, identify, look up (e.g., searching a table, database, or another data structure), ascertain, etc. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), obtaining, etc. Also, "determining / determining" may include resolving, selecting, choosing, establishing, etc.

[0203] parameters (e.g.:p 1st ,p 2nd ,p offset ,x,y,y%) can be replaced with "data indicating," "data defining," or "data representing" the relevant parameter, unless explicitly stated otherwise.

[0204] In this description, reference is made to various examples. The description of features or functions with respect to an example indicates that those features or functions are present in that example. Use of the terms "example" or "for example," "may," or "may" in the text, whether explicitly stated or not, indicates that such features or functions are present in at least the described example, whether or not they are described as an example, and that they may, but not necessarily, be present in some or all other examples. Thus, an "example," "for example," "may," or "may" refers to a particular instance in a class of examples. A property of an instance may be a property of only that instance, or a property of the class, or a property of a subclass of the class that includes some but not all of the instances in the class.

[0205] In this description, references to "a / an / the" [feature, element, component, means...] are used in an inclusive, not exclusive sense, and should be interpreted as "at least one" [feature, element, component, means...] unless otherwise specified. That is, any reference to an X containing a / the Y indicates that X may contain only one Y or may contain more than one Y, unless the context clearly indicates the contrary. If the use of "a" or "the" in an exclusive sense is intended, this will be clear in the context. In some situations, the use of "at least one" or "one or more" may be used to emphasize an inclusive sense, but the absence of these terms should not be interpreted as inferring any exclusive sense. As used herein, "at least one of " and "at least one of " and similar phrases, when a list of two or more elements is connected by "and" or "or," mean at least one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0206] The presence of a feature (or combination of features) in a claim refers to the feature (or combination of features) itself and to features that achieve substantially the same technical effect (equivalent features). Equivalent features include, for example, features that are modifications and achieve substantially the same result in substantially the same way. Equivalent features include, for example, features that perform substantially the same function in substantially the same way to achieve substantially the same result.

[0207] This description refers to various examples that use adjectives or adjective phrases to describe features of the examples. Such description of a property with respect to the examples indicates that the property is present in some examples exactly as described and in other examples substantially as described.

[0208] In the above description, the described devices may alternatively or additionally comprise devices that, in some other examples, comprise a distributed system of devices, e.g., a client / server device system. In examples where the provided devices form (or the method is implemented as) a distributed system, each device forming components and / or portions of the system provides (or implements) one or more features that collectively implement examples of the present disclosure. In some examples, a device may be reconfigured by an entity other than its initial manufacturer and provided with additional software, e.g., by a user downloading such software, that, when executed, causes the device to implement examples of the present disclosure (such implementation being either entirely by the device or as part of a system of devices as noted above).

[0209] While the above description describes several examples of the present disclosure, those skilled in the art will know of possible alternative structures and method features that provide equivalent functionality to the specific examples of such structures and features described herein above, and that have been omitted from the above description for brevity and clarity. Nevertheless, the above description should be read as implicitly including references to such alternative structures and method features that provide equivalent functionality, unless such alternative structures or method features are expressly excluded in the above description of examples of the present disclosure.

[0210] Although the foregoing specification has sought to draw attention to those features of the examples of the present disclosure which are considered to be particularly important, it should be understood that applicants claim protection for any patentable feature or combination of features referred to hereinabove and / or shown in the drawings, whether or not specific emphasis is given to them.

[0211] The examples of the present disclosure and the appended claims may be appropriately combined in any manner apparent to one skilled in the art. Separate references in the description to "examples," "in some examples," etc. do not necessarily refer to the same examples and are not mutually exclusive unless so stated and / or otherwise readily apparent to one skilled in the art from the description. For example, features, structures, processes, blocks, steps, actions, etc. described in one example may also be included in other examples, but are not necessarily included.

[0212] Each and every claim is incorporated herein as further disclosure, and the claims are embodiments of the present disclosure. Furthermore, although the claims herein are provided as including certain dependent claims, any claim may be dependent on any other claim, and to the extent that any alternative embodiment may result from combining, combining, and / or omitting features of various claims and / or modifying dependent claims, any such alternative embodiments and their equivalents are also contemplated within the scope of the present disclosure.

Claims

1. 1. A means for determining information indicative of channel access priority for a Physical Sidelink Feedback Channel (PSFCH) transmission, the means comprising at least Information indicating at least one status of at least one immediately preceding PSFCH transmission, or information indicating a cast type of a side link (SL) transmission associated with the PSFCH transmission in an unlicensed spectrum; 10. An apparatus comprising: means for determining, based in part on:

2. The information indicating the channel access priority is Priority classes for use in listen-before-talk (LBT) procedures; Priority classes for use within unlicensed bands; Channel Access Priority Class (CAPC), Contention Window (CW), and Channel Occupancy Time (COT), 2. The apparatus of claim 1, wherein the at least one selected from the group consisting of:

3. the information indicative of at least one status of the at least one immediately preceding PSFCH transmission, a channel access state of the immediately preceding at least one PSFCH transmission; whether the immediately preceding at least one PSFCH transmission failed or succeeded; whether an LBT procedure for transmitting the immediately preceding at least one PSFCH transmission failed or succeeded; an LBT success rate for the immediately preceding one or more PSFCH transmissions; the number of LBT successes for the immediately preceding one or more PSFCH transmissions; whether the PSFCH transmission includes a retransmission of information that was not successfully transmitted via the at least one immediately preceding PSFCH transmission; Allocating resources for the PSFCH transmission, the resources being allocated for retransmitting information that was not successfully transmitted via the immediately preceding at least one PSFCH transmission; and whether the PSFCH transmission is within a channel occupation time (COT) shared by UEs; 2. The apparatus of claim 1, further comprising information indicating at least one selected from the group consisting of:

4. The means for determining information indicating the channel access priority for the PSFCH transmission further comprises: means for determining a first candidate priority class for the PSFCH transmission; means for determining a second candidate priority class for the PSFCH transmission; and means for selecting at least one of the first candidate priority class and the second candidate priority class.

5. the first candidate priority class and / or the second candidate priority class are predefined; the first candidate priority class and / or the second candidate priority class are configured in the device; the first candidate priority class is configured to have a lower channel access priority than the second candidate priority class; the first candidate priority class is determined based at least in part on a channel access priority of one or more SL transmissions associated with the transmission; the second candidate priority class is determined based at least in part on a channel access priority of one or more SL transmissions associated with the transmission; the second candidate priority class is determined based at least in part on the first candidate priority class; and The second candidate priority class is determined based at least in part on the first candidate priority class and a priority class offset.

5. The apparatus of claim 4, wherein the at least one is selected from the group consisting of:

6. 5. The apparatus of claim 4, wherein the means for selecting one of the first candidate priority class and the second candidate priority class comprises means for selecting one of the first candidate priority class and the second candidate priority class according to at least one selection criterion.

7. 7. The apparatus of claim 6, wherein the at least one selection criterion includes selecting the first candidate priority class by default.

8. The at least one selection criterion is: determining whether the PSFCH transmission is a retransmission of at least a portion of a previously attempted PSFCH transmission; determining whether the PSFCH transmission is a retransmission of feedback that was previously attempted to be transmitted; determining whether the PSFCH transmission is a Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) or a retransmission of a Negative Acknowledgement (NACK) of a previous transmission attempt; determining a type of resource for the PSFCH transmission; determining whether the resources allocated for the PSFCH transmission are resources allocated for retransmitting information that was not successfully transmitted via the immediately preceding at least one PSFCH transmission; determining whether a HARQ-ACK of at least one immediately preceding PSFCH transmission is not transmitted via an earlier allocated resource due to an LBT failure; 7. The apparatus of claim 6, further comprising selecting the second candidate priority class in response to at least one of:

9. The at least one selection criterion is:

7. The apparatus of claim 6, further comprising: selecting the second candidate priority class in response to determining whether an LBT success rate of a number of previous PSFCH transmissions is less than a threshold.

10. The at least one selection criterion is:

7. The apparatus of claim 6, further comprising: selecting the second candidate priority class in response to determining whether a number of successful LBTs among the number of immediately preceding PSFCH transmissions is less than a threshold.

11. The at least one selection criterion is:

7. The apparatus of claim 6, further comprising the step of selecting the second candidate priority class in response to determining whether the SL transmission is a unicast transmission.

12. 7. The apparatus of claim 6, further comprising: means for receiving configuration information to enable the apparatus to determine the at least one selection criterion to apply to select one of the first candidate priority class and the second candidate priority class.

13. 7. The apparatus of claim 6, further comprising: means for determining at least one selection criterion to apply based at least in part on a cast type of the SL transmission associated with the PSFCH transmission.

14. 2. The apparatus of claim 1, further comprising: means for receiving configuration information to enable the apparatus to determine the information indicative of the channel access priority for the PSFCH transmission.

15. The configuration information is a first candidate priority class, a second candidate priority class, an offset between the first candidate priority class and the second candidate priority class; the number of immediately preceding PSFCH transmissions; Threshold of transmission success rate, a threshold for the number of successful transmissions, The cast type of the SL transmission associated with the PSFCH transmission; and one or more selection criteria to which the device is applied; 15. The apparatus of claim 14, further comprising at least one instruction selected from the group consisting of:

16. 16. The apparatus of claim 1, further comprising: means for causing a channel access procedure to be performed for transmitting the transmission based at least in part on the determined information indicative of the channel access priority.

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