Channel access selection for physical sidelink feedback channel (PSFCH) communication in unlicensed bands

Abstract

A method of wireless communication performed in a shared frequency band at a user equipment (UE) includes receiving a sidelink (SL) communication; selecting a channel access configuration for a physical sidelink feedback channel (PSFCH) occasion in the shared frequency band; and transmitting the PSFCH communication in the PSFCH occasion in the shared frequency band based on the channel access configuration and the SL communication.

Description

[0001] introduction

[0002] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, etc. These systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). A wireless multiple-access communication system may include multiple base stations (BSs), each of which simultaneously supports communication for multiple communication devices, which may be otherwise referred to as user equipment (UE).

[0003] In order to meet the growing demand for extended mobile broadband connections, wireless communication technology is evolving from long term evolution (LTE) technology to next generation new radio (NR) technology, which may be referred to as the fifth generation (5G). For example, NR is designed to provide lower latency, higher bandwidth or higher throughput, and higher reliability compared to LTE. NR is designed to operate on a wide spectrum band array, for example, from low frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz to high frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed spectrum and shared spectrum. Spectrum sharing enables operators to have the opportunity to aggregate spectrum to dynamically support high bandwidth services. Spectrum sharing can extend the benefits of NR technology to operating entities that may not have access to licensed spectrum.

[0004] In a wireless communication network, a BS can communicate with a UE in both the uplink and downlink directions. Sidelinks were introduced in LTE to allow a UE to transmit data to another UE without tunneling through the BS and / or associated core network. LTE sidelink technology has been extended to provide device-to-device (D2D) communications, vehicle-to-everything (V2X) communications, and / or cellular vehicle-to-everything (C-V2X) communications. Similarly, NR can be extended to support sidelink communications of D2D, V2X, and / or C-V2X on dedicated spectrum, licensed spectrum, and / or unlicensed spectrum. Summary of the invention

[0005] The following summarizes some aspects of the disclosure to provide a basic understanding of the technology discussed. This summary is not an exhaustive overview of all expected features of the disclosure, and is neither intended to identify key elements or important elements of all aspects of the disclosure, nor to delineate the scope of any or all aspects of the disclosure. The sole purpose of this summary is to present some concepts of one or more aspects of the disclosure in a summarized form as a prelude to a more detailed description presented later.

[0006] According to various aspects of the present disclosure, a user equipment (UE) may select a channel access configuration for a physical sidelink feedback channel (PSFCH) communication in a shared frequency band. The channel access configuration may correspond to a channel access type, such as a type 1 channel access, a type 2A channel access, a type 2B channel access, or a type 2C channel access. In some aspects, the UE may select a channel access configuration based on an indication of channel occupancy time (COT) sharing or an indication that the acquired COT cannot be used for sharing. In other aspects, the UE may be configured to select a channel access configuration based on a PSFCH configuration. For example, in some aspects, the UE may select a channel access configuration that does not include sensing based on a PSFCH configuration that satisfies one or more criteria for short control signaling. On the other hand, the UE may select a channel access configuration based on a channel access type indication provided by another UE. In some aspects, the UE may receive multiple indications of conflicting channel access types or configurations. In some aspects, the UE may be configured with one or more rules for selecting a channel access configuration in response to receiving a conflict indication. Another aspect of the present disclosure describes selecting or determining a channel access parameter based on one or more sidelink (SL) communications received from one or more other UEs.

[0007] According to one aspect of the present disclosure, a method for wireless communication performed in a shared frequency band at a user equipment (UE) includes: receiving side link (SL) communication; selecting a channel access configuration for a physical side link feedback channel (PSFCH) opportunity in the shared frequency band; and sending PSFCH communication in a PSFCH opportunity in the shared frequency band based on the channel access configuration and the SL communication.

[0008] According to another aspect of the present disclosure, a user equipment (UE) includes: a memory device; a transceiver; and a processor that communicates with the memory device and the transceiver, wherein the UE is configured to: receive side link (SL) communications; select a channel access configuration for a physical side link feedback channel (PSFCH) opportunity in a shared frequency band; and send PSFCH communications in a PSFCH opportunity in the shared frequency band based on the channel access configuration and the SL communications.

[0009] According to another aspect of the present disclosure, a non-transitory computer-readable medium includes a program code recorded thereon, wherein the program code includes instructions that can be executed by a processor of a user equipment (UE) to enable the UE to: receive side link (SL) communications; select a channel access configuration for a physical side link feedback channel (PSFCH) opportunity in a shared frequency band; and send PSFCH communications in a PSFCH opportunity in the shared frequency band based on the channel access configuration and the SL communications.

[0010] According to another aspect of the present disclosure, a user equipment (UE) includes: a component for receiving sidelink (SL) communication; a component for selecting a channel access configuration for a physical sidelink feedback channel (PSFCH) opportunity in a shared frequency band; and a component for sending PSFCH communication in a PSFCH opportunity in a shared frequency band based on the channel access configuration and the SL communication.

[0011] After reviewing the following description of specific, exemplary embodiments of the present invention in conjunction with the accompanying drawings, other aspects, features, and embodiments of the present invention will become apparent to those of ordinary skill in the art. Although the various features of the present invention may be discussed with respect to certain embodiments and drawings below, all embodiments of the present invention may include one or more of the advantageous features discussed herein. In other words, although one or more embodiments may be discussed as having certain advantageous features, one or more of these features may also be used according to the various embodiments of the present invention discussed herein. In a similar manner, although the exemplary embodiments may be discussed below as device, system, or method embodiments, it should be understood that these exemplary embodiments may be implemented in various devices, systems, and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A wireless communication network according to some aspects of the present disclosure is illustrated.

[0013] Figure 2 A wireless communication network providing sidelink communications according to some aspects of the present disclosure is illustrated.

[0014] Figure 3 A sidelink communication scheme in a wireless communication network according to some aspects of the present disclosure is illustrated.

[0015] Figure 4 is a timing diagram illustrating a sidelink communication scenario according to some aspects of the present disclosure.

[0016] Figure 5 is a timing diagram illustrating a scheme for transmitting a physical sidelink feedback channel (PSFCH) in a shared frequency band in accordance with aspects of the present disclosure.

[0017] Figure 6 is a signaling diagram illustrating a method for selecting a channel access configuration for PSFCH communications in a shared frequency band according to aspects of the present disclosure.

[0018] Fig. 7A is a diagram illustrating a scheme for conveying PSFCH communications according to aspects of the present disclosure.

[0019] Figure 7Bis a diagram illustrating a scheme for conveying PSFCH communications according to aspects of the present disclosure.

[0020] Figure 7C is a diagram illustrating a scheme for conveying PSFCH communications according to aspects of the present disclosure.

[0021] Fig. 8A is a diagram illustrating a PSFCH configuration according to various aspects of the present disclosure.

[0022] Figure 8B is a diagram illustrating a PSFCH configuration according to various aspects of the present disclosure.

[0023] Figure 8C is a diagram illustrating a PSFCH configuration according to various aspects of the present disclosure.

[0024] Fig. 9 is a signaling diagram illustrating a method for selecting a channel access configuration for PSFCH communications in a shared frequency band according to aspects of the present disclosure.

[0025] Fig.10 is a block diagram of a user equipment (UE) according to some aspects of the present disclosure.

[0026] Fig.11 is a block diagram of an exemplary base station (BS) according to some aspects of the present disclosure.

[0027] Fig.12 is a flow chart of a sidelink communication method according to some aspects of the present disclosure. DETAILED DESCRIPTION

[0028] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. In order to provide a comprehensive understanding of the various concepts, the detailed description includes specific details. However, it is apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring these concepts.

[0029] The present disclosure as a whole relates to wireless communication systems, which are also referred to as wireless communication networks. In various aspects, various technologies and devices can be used for wireless communication networks, such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, LTE networks, global mobile communication systems (GSM) networks, fifth generation (5G) or new radio (NR) networks, and other communication networks. As described herein, the terms "network" and "system" can be used interchangeably.

[0030] OFDMA network can implement radio technology such as Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM, etc. UTRA, E-UTRA and GSM are part of Universal Mobile Telecommunications System (UMTS). Specifically, Long Term Evolution (LTE) is a version of UMTS using E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided by an organization named "3rd Generation Partnership Project" (3GPP), and cdma2000 is described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). These various radio technologies and standards are known or under development. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between telecommunication association groups with the goal of defining globally applicable third generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP plan to improve UMTS mobile phone standards. 3GPP may define specifications for next generation mobile networks, mobile systems, and mobile devices. The present disclosure relates to the evolution from LTE, 4G, 5G, NR and beyond wireless technologies, where access to wireless spectrum is shared between networks using a range of new and different radio access technologies or radio air interfaces.

[0031] 5G networks are expected to have diverse deployments, diverse spectrum, and diverse services and devices that can be implemented using a unified air interface based on OFDM. To achieve these goals, in addition to developing new radio technologies for 5G NR networks, further enhancements to LTE and LTE-A are also being considered. 5G NR will be able to scale to (1) ultra-high density (e.g., about 1M nodes / km) 2 (1) provide coverage for the massive Internet of Things (IoT) with ultra-low complexity (e.g., on the order of tens of bits / second), ultra-low energy (e.g., on the order of 10+ years of battery life), and deep coverage with the ability to reach challenging locations; (2) provide coverage including mission-critical control with strong security to protect sensitive personal, financial, or classified information, ultra-high reliability (e.g., on the order of 99.9999% reliability), ultra-low latency (e.g., on the order of 1 ms), and for users with extensive mobility or lack of mobility; and (3) provide coverage with enhanced mobile broadband (including very high capacity (e.g., on the order of 10 Tbps / km 2 ), coverage of extremely high data rates (e.g., multi-Gbps rates, 100+Mbps user experience rates), and deep awareness with advanced discovery and optimization).

[0032] 5G NR can be implemented using an optimized OFDM-based waveform with scalable parameter sets and transmission time intervals (TTIs); with a common, flexible framework to efficiently multiplex services and features using dynamic low-latency time division duplex (TDD) / frequency division duplex (FDD) designs; and with advanced wireless technologies such as massive multiple-input multiple-output (MIMO), robust millimeter wave (mmWave) transmission, advanced channel decoding, and device-centric mobility. The scalability of parameter sets in 5G NR and the scaling of subcarrier spacing can effectively address the operation of various services across different spectrums and different deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD / TDD implementations, the subcarrier spacing may appear at 15kHz on bandwidths (BW) such as 5MHz, 10MHz, 20MHz, etc. For other various outdoor and small cell coverage deployments of TDD greater than 3GHz, the subcarrier spacing may appear at 30kHz on 80 / 100MHz BW. For various other indoor broadband implementations, using TDD on the unlicensed portion of the 5 GHz band, subcarrier spacing may occur at 60 kHz over 160 MHz BW. Finally, for various deployments transmitting with the mmWave component at 28 GHz TDD, subcarrier spacing may occur at 120 kHz over 500 MHz BW.

[0033] 5G NR's scalable parameter sets facilitate scalable TTIs for different latency and quality of service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmission to start on symbol boundaries. 5G NR also envisions a self-contained integrated subframe design with UL / downlink scheduling information, data, and acknowledgment in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL / downlink (which can be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet current business needs).

[0034] The various other aspects and features of the present disclosure are further described below. It should be apparent that the teachings herein can be embodied in various forms, and any specific structure, function, or both disclosed herein are merely representative and not restrictive. Based on the teachings herein, it should be understood by those of ordinary skill in the art that the aspects disclosed herein can be implemented independently of any other aspects, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement a device or practice method. In addition, such a device can be implemented, or such a method can be implemented, using other structures, functionality, or structures and functionality other than or different from one or more of the aspects set forth herein. For example, the method can be implemented as a part of a system, device, device, and / or as instructions stored on a computer-readable medium for execution on a processor or computer. In addition, an aspect may include at least one element of a claim.

[0035] Sidelink communication refers to communication between user equipment devices (UE) without tunneling base stations (BS) and / or core networks. Sidelink communication can be communicated on physical sidelink control channels (PSCCH) and physical sidelink shared channels (PSSCH). PSCCH and PSSCH are similar to physical downlink control channels (PDCCH) and physical downlink shared channels (PDSCH) in downlink (DL) communication between BS and UE. For example, PSCCH may carry sidelink control information (SCI) and PSSCH may carry sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, wherein the SCI in the PSCCH may carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. Use cases for sidelink communication may include vehicle-to-everything (V2X), industrial IoT (IIoT), and / or NR-lightweight.

[0036] A UE communicating using a side link interface may be configured to respond to side link communications from other UEs using a hybrid automatic repeat request (HARQ) feedback indicating whether one or more side link transport blocks (TBs) have been successfully received. In some aspects, the UE may be configured with a side link feedback resource mapped to one or more SL data resources. For example, the UE may be configured with a physical side link feedback channel (PSFCH) resource. The PSFCH resource may include one or more periodic PSFCH instances. Each PSFCH instance may be associated with a PSFCH period including one or more time slots. In some aspects, the UE may convey at least one PSSCH communication in each time slot. In addition, the UE may be configured to communicate using shared or unlicensed frequency resources. These communications may be referred to as side link unlicensed (SL-U). In order to communicate in a shared or unlicensed frequency resource, one or more UEs may perform a clear channel assessment (CCA) or a channel access process based on a channel access type or configuration. For example, the UE may perform a listen-before-talk (LBT) process by obtaining a channel measurement of a fixed or variable amount of time. If the channel measurement is below a configured threshold, the UE may initiate or acquire a channel occupation time (COT) to communicate with one or more other UEs. In some aspects, communication from one UE to another specific UE may be referred to as unicast communication. Communication from one or more UEs to one or more other UEs may be referred to as groupcast or multicast communication.

[0037] In some aspects, a UE that initiates or acquires a COT may share at least a portion of the COT with another UE. For example, a first UE may perform a channel access procedure to acquire a COT, send a SL communication to a second UE in a first portion of the COT, and receive a SL communication from the second UE in a second shared portion of the COT. In some aspects, the first UE may indicate COT sharing information (COT-SI) in the first SL communication. In some aspects, the second UE may send a PSFCH communication indicating feedback information associated with the first SL communication in the shared portion of the COT. For example, the feedback information may indicate one or more confirmations or negative confirmations (ACK / NACK) for one or more corresponding PSSCH communications. In some cases, the second UE may have scheduled a PSFCH communication in which no COT sharing indication was received. Therefore, in some instances, the second UE may perform a channel access procedure to obtain a COT and send a PSFCH communication in the COT.

[0038] Channel access configurations differ in duration and power consumption. For example, a type 1 channel access procedure may involve or include a relatively longer channel sensing period than a type 2A or type 2B channel access procedure. Subject to channel access requirements and / or criteria, it may be desirable to use an available shorter channel access configuration. In addition, a UE communicating in a side link (SL) network may be configured to send and / or receive communications from multiple UEs. In some aspects, a PSFCH opportunity may occur during a COT acquired by a first UE, but the PSFCH communication may be scheduled for transmission to a different second UE. In addition, a COT sharing indication or other indications associated with a channel access type or configuration for a PSFCH opportunity may conflict.

[0039] The present disclosure provides systems, schemes and mechanisms for selecting and executing channel access procedures for PSFCH communications in a shared frequency band. In some aspects, a channel access configuration may correspond to a channel access type, such as type 1 channel access, type 2A channel access, type 2B channel access or type 2C channel access. In some aspects, a UE may select a channel access configuration based on an indication of channel occupancy time (COT) sharing or an indication that the acquired COT cannot be used for sharing. In other aspects, a UE may be configured to select a channel access configuration based on a PSFCH configuration. For example, in some aspects, a UE may select a channel access configuration that does not include sensing based on a PSFCH configuration that satisfies one or more criteria for short control signaling. On the other hand, a UE may select a channel access configuration based on a channel access type indication provided by another UE. In some aspects, a UE may receive multiple indications of conflicting channel access types or configurations. In some aspects, a UE may be configured with one or more rules for selecting a channel access configuration in response to receiving a conflict indication. Another aspect of the present disclosure describes selecting or determining a channel access parameter based on one or more sidelink (SL) communications received from one or more other UEs. In some aspects, a UE may be configured with one or more rules or hard-coded configurations for selecting a channel access configuration in accordance with the schemes, methods, and mechanisms described herein.

[0040] Various aspects of the present disclosure may provide several benefits. For example, by providing a coordination mechanism for selecting a channel access type, a UE may be able to select a channel access type that is more suitable for a scenario. For example, a UE may select a channel access type or configuration involving a shorter sensing period, thereby reducing latency and reducing power consumption. In addition, the methods and mechanisms described herein may allow fewer channel access procedures to be performed and COT to be utilized more efficiently. In addition, by facilitating more continuous sidelink communications in shared frequency resources, the chance of conflicts and / or interference may be reduced. Therefore, error rates may also be reduced, which may increase network speeds and reduce overhead, thereby improving user experience. Although the present disclosure is described in the context of deploying autonomous sidelink communications on a 2.4 GHz unlicensed band, the disclosed aspects may be applicable to any suitable shared or unlicensed band.

[0041] Figure 1 A wireless communication network 100 according to some aspects of the present disclosure is illustrated. The network 100 may be a 5G network. The network 100 includes a plurality of base stations (BSs) 105 (labeled 105a, 105b, 105c, 105d, 105e, and 105f, respectively) and other network entities. The BS 105 may be a station that communicates with the UE 115, and may also be referred to as an evolved Node B (eNB), a next generation eNB (gNB), an access point, and the like. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to the particular geographic coverage area of ​​the BS 105 and / or the BS subsystem serving the coverage area, depending on the context in which the term is used.

[0042] BS105 may provide communication coverage for macro cells or small cells (such as pico cells or femto cells), and / or other types of cells. Macro cells generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with a network provider. Small cells (such as pico cells) will generally cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions with a network provider. Small cells (such as femto cells) will generally also cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs associated with the femto cells (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS, or a home BS. In Figure 1In the example shown, BS105d and 105e may be conventional macro BSs, while BS105a to 105c may be macro BSs with one of three-dimensional (3D), full-dimensional (FD) or massive MIMO capabilities. BS 105a to 105c may utilize their higher dimensional MIMO capabilities to utilize 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. BS105f may be a small cell BS, which may be a home node or a portable access point. BS105 may support one or more (e.g., two, three, four, etc.) cells.

[0043] Network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time.

[0044] UE 115 is dispersed throughout the wireless network 100, and each UE 115 can be stationary or mobile. UE 115 may also be referred to as a terminal, a mobile station, a user unit, a station, etc. UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, etc. In one aspect, UE 115 may be a device including a universal integrated circuit card (UICC). On the other hand, UE may be a device that does not include a UICC. In some aspects, UE 115 that does not include a UICC may also be referred to as an IoT device or an Internet of Everything (IoE) device. UE 115a to 115d are examples of mobile smart phone type devices that access the network 100. UE 115 may also be a machine that is specifically configured for connected communications (including machine type communications (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT), etc.). UEs 115e to 115h are examples of various machines configured for communication to access network 100. UEs 115i to 115k are examples of vehicles equipped with wireless communication devices configured for communication to access network 100. UE 115 may be able to communicate with any type of BS, whether macro BS, small cell, etc. Figure 1 , lightning (e.g., communication link) indicates wireless transmission between UE 115 and serving BS 105 (which is a BS designated to serve UE 115 on downlink (DL) and / or uplink (UL), desired transmission between BS 105, backhaul transmission between BSs, or sidelink transmission between UE 115.

[0045] In operation, BSs 105a to 105c may use 3D beamforming and cooperative spatial techniques such as coordinated multipoint (CoMP) or multiple connections to serve UEs 115a and 115b. Macro BS 105d may perform backhaul communications with BSs 105a to 105c and small cell BS 105f. Macro BS 105d may also transmit multicast services that are subscribed to and received by UEs 115c and 115d. Such multicast services may include mobile TV or streaming video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

[0046] The BSs 105 may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which may be examples of gNBs or access node controllers (ANCs)) may interface with the core network via a backhaul link (e.g., NG-C, NG-U, etc.) and may perform radio configuration and scheduling for communications with the UE 115. In various examples, the BSs 105 may communicate with each other directly or indirectly (e.g., through the core network) over a backhaul link (e.g., X1, X2, etc.), which may be a wired or wireless communication link.

[0047] The network 100 may also support mission-critical communications using ultra-reliable and redundant links for mission-critical devices such as UE 115e, which may be a drone. The redundant communication links with UE 115e may include links from macro BSs 105d and 105e, and links from small cell BS 105f. Other machine-type devices such as UE 115f (e.g., a thermometer), UE 115g (e.g., a smart meter), and UE 115h (e.g., a wearable device) may communicate directly with BSs such as small cell BS 105f and macro BS 105e through the network 100, or communicate through the network in a multi-step configuration by communicating with another user device such as UE 115f that communicates temperature measurement information to a smart meter (UE 115g), which then reports to the network through the small cell BS 105f, which relays its information to the network. The network 100 may also provide additional network efficiency through dynamic low latency TDD / FDD communications, such as V2V, V2X, C-V2X communications between UE 115i, 115j, or 115k and other UEs 115 and / or vehicle-to-infrastructure (V2I) communications between UE 115i, 115j, or 115k and BS 105.

[0048] In some implementations, the network 100 utilizes an OFDM-based waveform for communication. An OFDM-based system may divide the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, frequency modulations, frequency bins, etc. Each subcarrier may be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may depend on the system BW. The system BW may also be divided into subbands. In other instances, the subcarrier spacing and / or the duration of the TTI may be scalable.

[0049] In some aspects, BS 105 may assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RBs)) for downlink (DL) and uplink (UL) transmissions in network 100. DL refers to the transmission direction from BS 105 to UE 115, and UL refers to the transmission direction from UE 115 to BS 105. The communication may be in the form of a radio frame. A radio frame may be divided into a plurality of subframes or time slots, for example, about 10. Each time slot may also be divided into micro-time slots. In FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In TDD mode, UL and DL transmissions occur in different time periods using the same frequency band. For example, a subframe subset (e.g., a DL subframe) in a radio frame may be used for DL ​​transmission, and another subframe subset (e.g., an UL subframe) in a radio frame may be used for UL transmission.

[0050] DL subframes and UL subframes may be further divided into several zones. For example, each DL or UL subframe may have a predefined zone for the transmission of reference signals, control information, and data. Reference signals are predetermined signals that facilitate communication between BS105 and UE 115. For example, a reference signal may have a specific pilot pattern or structure, wherein a pilot tone may span an operational BW or frequency band, and each pilot tone is positioned at a predefined time and a predefined frequency. For example, BS105 may send a cell-specific reference signal (CRS) and / or a channel state information-reference signal (CSI-RS) to enable UE 115 to estimate a DL channel. Similarly, UE 115 may send a sounding reference signal (SRS) to enable BS105 to estimate an UL channel. Control information may include resource assignments and protocol control. Data may include protocol data and / or operational data. In some aspects, BS105 and UE115 may communicate using self-contained subframes. Self-contained subframes may include a portion for DL ​​communication and a portion for UL communication. A self-contained subframe may be DL-centric or UL-centric. A DL-centric subframe may include a DL communication duration that is longer than a UL communication duration. A UL-centric subframe may include a UL communication duration that is longer than a UL communication duration.

[0051] In some aspects, the network 100 may be an NR network deployed on a licensed spectrum. The BS 105 may send synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) in the network 100 to facilitate synchronization. The BS 105 may broadcast system information associated with the network 100 (e.g., including a master information block (MIB), remaining system information (RMSI), and other system information (OSI)) to facilitate initial network access. In some cases, the BS 105 may broadcast the PSS, SSS, and / or MIB in the form of a synchronization signal block (SSB) over a physical broadcast channel (PBCH), and may broadcast the RMSI and / or OSI over a physical downlink shared channel (PDSCH).

[0052] In some aspects, a UE 115 attempting to access the network 100 may perform an initial cell search by detecting a PSS from the BS 105. The PSS may enable synchronization of period timing and may indicate a physical layer identification value. The UE 115 may then receive the SSS. The SSS may enable radio frame synchronization and may provide a cell identification value, which may be combined with the physical layer identification value to identify a cell. The PSS and SSS may be located in the center portion of a carrier or at any suitable frequency within a carrier.

[0053] After receiving the PSS and SSS, the UE 115 may receive the MIB. The MIB may include system information for initial network access and scheduling information for RMSI and / or OSI. After decoding the MIB, the UE 115 may receive the RMSI and / or OSI. The RMSI and / or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource sets (CORESET) for physical downlink control channel (PDCCH) monitoring, physical UL control channel (PUCCH), physical UL shared channel (PUSCH), power control, and SRS.

[0054] After obtaining the MIB, RMSI and / or OSI, the UE 115 may perform a random access procedure to establish a connection with the BS 105. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE 115 may send a random access preamble, and the BS 105 may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, UL grant, temporary cell radio network temporary identifier (C-RNTI), and / or a backoff indicator. Upon receiving the random access response, the UE 115 may send a connection request to the BS 105 and the BS 105 may respond with a connection response. The connection response may indicate contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response may be referred to as message 1 (MSG1), message 2 (MSG2), message 3 (MSG3), and message 4 (MSG4), respectively. In some examples, the random access procedure may be a two-step random access procedure, where the UE 115 may send a random access preamble and a connection request in a single transmission, and the BS 105 may respond by sending a random access response and a connection response in a single transmission.

[0055] After establishing the connection, the UE 115 and the BS 105 may enter a normal operation phase, in which operation data may be exchanged. For example, the BS 105 may schedule the UE 115 for UL and / or DL ​​communications. The BS 105 may send an UL and / or DL ​​scheduling grant to the UE 115 via the PDCCH. The scheduling grant may be sent in the form of DL control information (DCI). The BS 105 may send a DL communication signal (e.g., carrying data) to the UE 115 via the PDSCH according to the DL scheduling grant. The UE 115 may send an UL communication signal to the BS 105 via the PUSCH and / or PUCCH according to the UL scheduling grant.

[0056] In some aspects, BS105 may communicate with UE 115 using HARQ technology to improve communication reliability, for example, to provide URLLC services. BS105 may schedule UE 115 to perform PDSCH communication by sending DL grants in PDCCH. BS105 may send DL data packets to UE 115 according to the scheduling in PDSCH. DL data packets may be sent in the form of transport blocks (TBs). If UE 115 successfully receives the DL data packet, UE 115 may send HARQ ACK to BS105. On the contrary, if UE115 fails to successfully receive the DL transmission, UE 115 may send HARQ NACK to BS105. Upon receiving HARQ NACK from UE 115, BS105 may retransmit the DL data packet to UE 115. The retransmission may include a decoding version of the DL data that is the same as the initial transmission. Alternatively, the retransmission may include a decoding version of the DL data that is different from the initial transmission. The UE 115 may apply soft combining to combine the decoded data received from the initial transmission and the retransmission for decoding. The BS 105 and the UE 115 may also apply HARQ to UL communications using a substantially similar mechanism as DL HARQ.

[0057] In some aspects, the network 100 may operate on a system BW or a component carrier (CC) BW. The network 100 may divide the system BW into multiple BWPs (e.g., parts). The BS 105 may dynamically assign the UE 115 to operate on a specific BWP (e.g., a specific part of the system BW). The assigned BWP may be referred to as an active BWP. The UE 115 may monitor the active BWP to find signaling information from the BS 105. The BS 105 may schedule the UE 115 to perform UL or DL ​​communications in the active BWP. In some aspects, the BS 105 may assign a pair of BWPs within the CC to the UE 115 for UL and DL communications. For example, the BWP pair may include a BWP for UL communication and a BWP for DL ​​communication.

[0058] In some aspects, network 100 may operate on a shared channel, which may include a shared frequency band and / or an unlicensed frequency band. For example, network 100 may be an NR-U network operating on an unlicensed frequency band. In such aspects, BS105 and UE115 may be operated by multiple network operation entities. In order to avoid conflicts, BS105 and UE 115 may use a listen-before-talk (LBT) process to monitor a transmit opportunity (TXOP) in a shared channel. TXOP may also be referred to as COT. For example, a transmitting node (e.g., BS105 or UE 115) may perform LBT before transmitting in a channel. When LBT passes, the transmitting node may continue to transmit. When LBT fails, the transmitting node may prohibit transmitting in the channel.

[0059] LBT may be based on energy detection (ED) or signal detection. For LBT based on energy detection, when the signal energy measured from the channel is lower than a threshold, the LBT result is passed. Conversely, when the signal energy measured from the channel exceeds a threshold, the LBT result is failed. For LBT based on signal detection, when a channel reservation signal (e.g., a predetermined preamble signal) is not detected in the channel, the LBT result is passed. In addition, LBT may be in a variety of modes. The LBT mode may be, for example, type 4 (CAT4) LBT, type 2 (CAT2) LBT, or type 1 (CAT1) LBT. CAT1 LBT is referred to as a no LBT mode, in which no LBT is performed before transmission. In some aspects, CAT1 LBT may be referred to as type 2C channel access. CAT2 LBT refers to LBT without a random backoff period. For example, a transmitting node may determine a channel measurement in a time interval and determine whether a channel is available based on a comparison of the channel measurement with an ED threshold. In some aspects, CAT2 LBT may be referred to as type 2A channel access or type 2B channel access. In some aspects, whether CAT2 LBT is type 2A or type 2B may depend on the gap or idle period. The sensing period or interval for type 2A channel access may be 25 microseconds. The sensing period or interval for type 2B channel access may be 16 microseconds. CAT4 LBT refers to LBT with random backoff and variable contention window (CW). For example, the sending node may extract a random number and backoff a certain duration in a certain time unit based on the extracted random number. In some aspects, CAT4 LBT may be referred to as type 1 channel access.

[0060] In some aspects, the network 100 may support sidelink communications between UEs 115 on a shared radio frequency band (e.g., in a shared spectrum or an unlicensed spectrum). In some aspects, the UEs 115 may communicate with each other on a 2.4 GHz unlicensed band that may be shared by multiple network operating entities using various radio access technologies (RATs), such as NR-U, WiFi, and / or License Assisted Access (LAA). Figure 2 shown.

[0061] Figure 2 An example of a wireless communication network 200 providing side link communication according to aspects of the present disclosure is illustrated. The network 200 may correspond to a portion of the network 100. To simplify the discussion, Figure 2Two BS205 (shown as 205a and 205b) and six UE 215 (shown as 215a1, 215a2, 215a3, 215a4, 215b1, and 215b2) are illustrated, but it should be appreciated that aspects of the present disclosure can be extended to any suitable number of UE 215 (e.g., about 2, 3, 4, 5, 7, or more) and / or BS205 (e.g., about 1, 3, or more). BS205 and UE 215 may be similar to BS105 and UE 115, respectively. BS205 and UE 215 may share the same radio band for communication. In some instances, the radio band may be a 2.4 GHz unlicensed band, a 5 GHz unlicensed band, or a 6 GHz unlicensed band. Generally speaking, the shared radio band may be at any suitable frequency.

[0062] BS205a and UE 215a1-215a4 may be operated by a first network operating entity. BS205b and UE 215b1-215b2 may be operated by a second network operating entity. In some aspects, the first network operating entity may use the same RAT as the second network operating entity. For example, BS205a and UE 215a1-215a4 of the first network operating entity and BS205b and UE 215b1-215b2 of the second network operating entity are NR-U devices. In some other aspects, the first network operating entity may use a different RAT from the second network operating entity. For example, BS205a and UE 215a1-215a4 of the first network operating entity may utilize NR-U technology, while BS205b and UE 215b1-215b2 of the second network operating entity may utilize WiFi or LAA technology.

[0063] In network 200, some UEs in UE 215a1-215a4 can communicate with each other in peer-to-peer communication. For example, UE 215a1 can communicate with UE 215a2 through side link 252, UE 215a3 can communicate with UE 215a4 through another side link 251, and UE 215b1 can communicate with UE 215b2 through another side link 254. Side links 251, 252 and 254 are unicast bidirectional links. Some UEs in UE 215 can also communicate with BS 205a or BS 205b in UL direction and / or DL ​​direction via communication link 253. For example, UE 215a1, 215a3 and 215a4 are in the coverage area 210 of BS 205a, and therefore can communicate with BS 205a. UE 215a2 is outside the coverage area 210, and therefore can not communicate directly with BS 205a. In some instances, UE 215a1 may operate as a repeater for UE 215a2 to reach BS 205a. Similarly, UE 215b1 is within the coverage area 212 of BS 205b, and therefore may communicate with BS 205b, and may operate as a repeater for UE 215b2 to reach BS 205b. In some aspects, some of UEs 215 are associated with vehicles (e.g., similar to UEs 115i-115k), and the communications conducted through side links 251, 252, and 254 may be C-V2X communications. C-V2X communications may refer to communications between a vehicle and any other wireless communication device in a cellular network.

[0064] Figure 3 A sidelink communication scheme 300 in a wireless communication network according to some aspects of the present disclosure is illustrated. A UE (such as UE 115 and / or 215) in a network (such as network 100 and / or 200) may employ scheme 300. Specifically, a sidelink UE may employ scheme 300 to contend for access in a shared radio band (e.g., in a shared spectrum or an unlicensed spectrum) for sidelink communication. A shared radio band may be shared by multiple RATs, such as Figure 2 As discussed in Figure 3 , the x-axis represents time in some arbitrary units, and the y-axis represents frequency in some arbitrary units.

[0065] In the scheme 300, a shared radio frequency band 301 is divided into a plurality of sub-channels or frequency sub-bands 302 (shown as 302 S0 ,302 S1 ,302 S2, ...) for side link communication. Frequency band 301 can be at any suitable frequency. In some instances, frequency band 301 is a 2.4 GHz unlicensed band. In some instances, frequency band 301 is a 5 GHz unlicensed band. In some instances, frequency band 301 is a 6 GHz unlicensed band. Frequency band 301 can have any suitable BW and can be divided into any suitable number of frequency sub-bands 302. The number of frequency sub-bands 302 can depend on the side link communication BW requirements. In some aspects, frequency band 301 is a 2.4 GHz unlicensed band and can have a bandwidth of approximately 80 MHz divided into approximately fifteen 5 megahertz (MHz) frequency sub-bands 302.

[0066] A sidelink UE (eg, UE 115 and / or 215) may be equipped with a wideband receiver and a narrowband transmitter. For example, the UE may utilize a narrowband transmitter to access frequency subband 302. S2 , to utilize the frame structure 304 for sidelink transmission. The frame structure 304 is repeated in each frequency subband 302. In some examples, such as Figure 3 As shown in , there may be frequency gaps or guard bands between adjacent frequency sub-bands 302, for example, to mitigate adjacent frequency band interference. Thus, multiple sidelink data may be communicated simultaneously in different frequency sub-bands 302 (e.g., FDM). The frame structure 304 also repeats in time. For example, the frequency sub-bands 302 S2 The time may be divided into multiple frames with a frame structure 304. The frame structure 304 includes an LBT gap duration 310 followed by a sidelink resource 306. The LBT gap duration 310 is used for channel contention between devices of the same RAT or between devices of different RATs. When winning the contention, the sidelink UE may utilize the sidelink resource 306 to send control data and user data.

[0067] The sidelink resources 306 may have a substantially similar structure to the NR sidelink resources. For example, the sidelink resources 306 may include multiple subcarriers or RBs in frequency and multiple symbols in time. In some instances, the sidelink resources 306 may have a duration between about one millisecond (ms) and about 20 ms. The sidelink resources 306 may include a PSCCH 320, a PSSCH 330, and / or a physical sidelink feedback channel (PSFCH) 340. The PSCCH 320, the PSSCH 330, and the PSFCH 340 may be multiplexed in time and / or frequency. Figure 3 In the illustrated example, the PSCCH 320 is located during the beginning symbol (eg, about 1 symbol or about 2 symbols) of the side link resource 306 and occupies the frequency subband 302. S2PSFCH 340 is located at the end symbol of sidelink resource 306. PSSCH 330 occupies the remaining time-frequency resources in sidelink resource 306. In general, PSCCH 320, PSSCH 330 and PSFCH 340 can be multiplexed in sidelink resource 306 in any suitable configuration.

[0068] A sidelink UE (e.g., UE 115 and / or 215) that intends to transmit in frequency band 301 may perform narrowband LBT in one or more frequency subbands 302. For example, the sidelink UE may transmit in frequency subband 302 during LBT gap duration 310. S2 The LBT can be as described above. Figure 1 CAT4 LBT based on energy detection is discussed. If LBT passes (e.g., when the measured channel signal energy is below the energy detection threshold), the sidelink UE may continue to send SCI and sidelink data to the peer sidelink UE in the sidelink resource 306. If LBT fails (e.g., when the channel signal energy is above the energy detection threshold), the sidelink UE may refrain from transmitting in the sidelink resource 306. Thus, LBT may operate to detect the frequency subband 302. S2 access or occupancy in the frequency band 301 and promote coexistence with other technologies sharing the frequency band 301.

[0069] The sidelink UE may send SCI in PSCCH 320 and send sidelink data (e.g., user information data) in PSSCH 330. Depending on the sidelink application, the sidelink data may have various forms and types. For example, when the sidelink application is a V2X application, the sidelink data may carry V2X data (e.g., vehicle location information, travel speed and / or direction, vehicle sensing measurements, etc.). Alternatively, when the sidelink application is an IIoT application, the sidelink data may carry IIoT data (e.g., sensor measurements, device measurements, temperature readings, etc.). The sidelink UE may also send HARQ ACK / NACK in PSFCH 340. HARQ ACK / NACK may be feedback for sidelink data received by the sidelink UE in an earlier sidelink resource 306. SCI may indicate a reservation for the next sidelink resource 306. Therefore, an intra-NR sidelink UE (e.g., a UE in the same NR-U sidelink system) may perform SCI sensing to determine whether the sidelink resource 306 can be used or occupied for intra-NR sharing. For example, if the NR intra-sidelink UE detects an SCI indicating a reservation for the sidelink resources 306, the NR intra-sidelink UE may refrain from transmitting in the reserved sidelink resources 306. If the NR intra-sidelink UE determines that a reservation for the sidelink resources 306 is not detected, the NR intra-sidelink UE may transmit in the sidelink resources 306. Thus, SCI sensing may help the UE identify the target frequency subband 302 to reserve for sidelink communication and avoid a conflict (e.g., an intra-NR conflict) with another sidelink UE in the NR sidelink system. In some aspects, the intra-RAT sidelink UE may be configured with a sensing window for SCI sensing or monitoring to reduce intra-NR conflicts.

[0070] The SCI may also indicate scheduling information and / or a destination identifier (ID) of a target receiving sidelink UE for the next sidelink resource 306. Thus, the sidelink UE may monitor the SCI sent by other sidelink UEs. After detecting the SCI in the sidelink resource 306, the sidelink UE may determine whether the sidelink UE is the target receiver based on the destination ID. If the sidelink UE is the target receiver, the sidelink UE may continue to receive and decode the sidelink data indicated by the SCI.

[0071] In some aspects, the scheme 300 is used to synchronize sidelink communications. In other words, the sidelink UEs are synchronized in time and aligned in terms of symbol boundaries, sidelink resource boundaries (e.g., the start time of the sidelink resource 306), and LBT gap duration boundaries (e.g., the start time of the LBT gap duration 310). For example, the sidelink UE can perform synchronization in various forms based on the sidelink SSB received from the sidelink UE and / or the NR-U SSB received from the BS (e.g., BS105 and / or 205) when within the coverage of the BS. In some aspects, for example, when within the coverage of the serving BS, the sidelink UEs in the system can be preconfigured with a resource pool 308 in the frequency band 301. The resource pool 308 may include a plurality of sidelink resources 306 arranged as shown in the frame structure 304. The BS may configure the sidelink UE using a resource pool configuration indicating resources in the frequency band 301 and / or sub-band 302, a frame structure 304 (e.g., LBT gap duration 310 and / or side link resources 306), and / or timing information (e.g., LBT gap duration 310 start and end boundaries).

[0072] Figure 4 A sidelink communication scenario 400 in a shared frequency band according to aspects of the present disclosure is illustrated. Scenario 400 may involve a UE (such as UE 115 and / or 215) in a network (such as network 100 and / or 200). Specifically, the sidelink UE may communicate and / or operate according to scenario 400 to contend for access in a shared radio frequency band (e.g., in a shared spectrum or an unlicensed spectrum) for sidelink communication. The shared radio frequency band may be shared by multiple RATs, such as Figure 2 As discussed in Figure 4 , the x-axis represents time in some arbitrary units, and the y-axis represents frequency in some arbitrary units.

[0073] In scenario 400, a UE may communicate using multiple sidelink resources, as discussed similarly above with respect to scheme 300. The sidelink resources may include PSCCH 420, PSSCH 430, and PSFCH 440. Scenario 400 includes sidelink communications in a shared frequency band during a time period including multiple time slots (e.g., 414, 416). The time domain configuration of scenario 400 may include periodic and / or semi-persistent PSFCH resources 440, which include PSFCH instances 442, 444. In some aspects, PSFCH resources 440 may be a global or common configuration for multiple UEs communicating in a cell and / or network. PSFCH resources 440 may be used to send SL feedback information and / or receive SL feedback information. In some aspects, the SL feedback information may include a hybrid automatic repeat request (HARQ) confirmation / negative confirmation (ACK / NACK) for one or more PSSCH instances (such as a first PSSCH 432 and / or a second PSSCH 434). The periodicity of the PSFCH resources 440 may be referred to as a PSFCH period 412. The PSFCH period 412 may be one or more time slots, such as 1, 2, 4, 6, 8 time slots, and / or any other suitable number of time slots. In the illustrated example, the PSFCH period 412 is four time slots. In some aspects, the UE may determine whether there is SL feedback information to be received in the PSFCH resources, or whether there is SL feedback information to be sent in the PSFCH resources.

[0074] The side link resources may be associated with or acquired by the LBT 460. For example, the UE may perform an LBT to acquire a channel occupancy time (COT). If the LBT result is passed, the UE acquires a COT during which the UE communicates in a first PSCCH 422 and a first PSSCH 432. After the first PSSCH 432, the UE may be configured with periodic and / or semi-persistent PSFCH resources or instances 442. In some aspects, the PSFCH instance 442 may result in a link switch and / or communication gap during the first COT. In some aspects, the communication gap may exceed the COT maintenance threshold configured above. Therefore, the UE may suppress transmission and / or reception during a subsequent time slot 414. The UE may then perform a second LBT 462 during a second time slot 416. Based on the second LBT 462, the UE may obtain a COT 464 during which the UE may communicate in the second PSCCH 424, the second PSSCH 434, the third PSCCH 426, and the third PSSCH 436. If the gap between the PSSCH 434 and the PSSCH 436 is equal to or lower than the configured COT maintenance threshold, the UE may continue the COT 464 between the PSSCH 434 and the PSSCH 436 without performing additional LBT. For example, if the gap between the sidelink communications is less than 25 μs, the UE may continue to communicate during the COT 464. In another example, if the gap between the sidelink communications is equal to or less than 16 μs, the UE may continue to communicate during the COT 464.

[0075] The PSFCH resource 440 includes a second PSFCH instance 444 after the third PSSCH 436. In some aspects, there may be a gap between the third PSSCH 436 and the second PSFCH instance 444. In some aspects, the gap may be greater than 16 μs, or greater than 25 μs. If the gap exceeds 25 μs, the UE may be instructed or configured to perform additional LBT to continue communicating during the COT 464. On the other hand, the UE may perform additional LBT to acquire or initiate a new COT before the sidelink communication can be resumed. In addition, in some aspects, the UE may not have PSFCH communications to send or receive. However, the additional LBT will result in undesirable overhead and reduced throughput. Therefore, the efficiency of the sidelink communication in the shared frequency band may be reduced.

[0076] Figure 5 5 is a diagram illustrating a SL communication scheme 500 for a shared frequency band. Various aspects of the present disclosure may be performed by a first wireless communication device and / or a second wireless communication device. For example, in one aspect, one or more actions of the scheme 500 may be performed by a first user equipment communicating with a second user equipment. Figure 5 5 shows a plurality of side link resources configured for side link communication between a first wireless communication device and a second wireless communication device, the side link resources being distributed over a time slot 510, the time slot 510 including a plurality of symbols 512. Figure 4 , the time slot 510 may be part of a COT obtained by performing LBT in a shared frequency band. The communication within the time slot 510 includes side link control information (SCI) 520, PSSCH data 530, PSFCH data 540, automatic gain control symbol (AGC) 550, and gap symbol 560. For example, the first symbol of the time slot 510 includes a first AGC 552. The first AGC 552 may include or be based on a copy of the signal, waveform, and / or data in the symbol immediately following it. The SCI 520 communicated during the time slot 510 includes a first SCI 522 and a second SCI 524. In some aspects, the first SCI 522 includes SCI-1. On the other hand, the second SCI 524 includes SCI-2. In some aspects, the first SCI 522 is communicated using PSCCH resources, and the second SCI 524 is communicated using PSSCH resources. The time slot also includes PSSCH communication 532. The PSSCH communication 532 may include SL data, RRC information elements (IEs), medium access control (MAC) IEs, and / or control elements (CEs). The SL data may be communicated in one or more transport blocks (TBs).

[0077] In some aspects, the resources for each SL communication in the SL communication may be configured for the SL resource pool. In some aspects, the SL resource pool may indicate the time and / or frequency resources for each of a plurality of channels (such as PSCCH, PSSCH, and PSFCH). In some aspects, the allocation of frequency resources may include one or more sets of resource blocks (RBs), one or more interleavings of RBs, one or more subchannels, and / or one or more partial RBs. In some aspects, the frequency resources may be different for different channels. For example, the SL resource pool may indicate a first subset of frequency resources for SCI 520, a second subset of frequency resources for PSSCH communication 530, and a third subset of frequency resources for PSFCH communication 540. In some aspects, the SL resource pool may include or indicate a first interleaving of RBs for PSSCH communication 530 and a second interleaving of RBs for PSFCH communication 540. In addition, the UE may be configured with a mapping scheme or configuration for mapping PSSCH resources to PSFCH resources. For example, the PSFCH resources may be divided into subsets or portions, with each subset allocated for PSSCH communications 530 in a given PSSCH resource and / or time slot.

[0078] For PSFCH communications, the UE may be configured with a dynamic HARQ timeline or a fixed HARQ timeline. For a dynamic HARQ timeline, the SCI in each time slot may include a value of K1, which indicates which PSFCH instance carries SL feedback information for the associated PSSCH in a later time slot. For example, a K1 value of 5 may indicate that SL feedback information (e.g., ACK, NACK) for the associated PSSCH communication may be provided in a future PSFCH resource 5 time slot. For a fixed HARQ timeline, the UE may be configured with a MinTimeGapPSFCH value, which indicates the minimum number of time slots after the last time slot of PSSCH communication before the UE sends PSFCH.

[0079] The time slot 510 includes a PSFCH instance 542. For example, a UE may be configured with a periodic PSFCH resource that occurs once every n time slots. In some aspects, n may be 1, 2, 3, 4, 5, 6, 8, and / or any other suitable number of time slots. In some aspects, the value of n may be referred to as a PSFCH period, as explained above. There is at least one gap symbol 562 and an AGC symbol 554 between the PSSCH communication 532 and the PSFCH resource 542.

[0080] In some instances, the PSFCH communication in the PSFCH instance 542 may include a SL ACK / NACK sent by the second wireless communication device to confirm the receipt or non-reception of one or more PSSCH communications sent by the first wireless communication device. For example, in some aspects, the PSFCH communication may indicate a SL ACK / NACK for one or more PSSCH instances before the PSFCH resource. In some aspects, the PSFCH communication in the PSFCH instance 542 may indicate an ACK / NACK for each PSSCH communication in the PSFCH period. In some aspects, the PSFCH communication in the PSFCH instance 542 may indicate an ACK / NACK for PSSCH communications within multiple PSFCH periods. On the other hand, the PSFCH communication in the PSFCH instance 542 may indicate an ACK / NACK or other SL feedback information associated with the SCI 520. For example, the first wireless communication device may instruct the second wireless communication device to send SL feedback information based on decoding at least one of the first SCI 522 or the second SCI 524. Therefore, if the second wireless communication device does not have PSFCH information to send in the PSFCH instance 542, the second wireless communication device can send SL feedback information in the PSFCH instance 542 based on decoding the SCI 522, 524.

[0081] In scheme 500, the UE may be configured to send both PSSCH and PSFCH in the same time slot. However, it should be understood that the UE may not have PSCCH and / or PSSCH for sending in a time slot with PSFCH opportunity. Therefore, in some aspects, the UE may only send AGC symbol 554 and PSFCH symbol 542. In some aspects, the UE may perform a channel access process to access PSFCH resources in a shared frequency band. For example, in the absence of a COT sharing indication from a UE that obtains COT, the UE may perform a type 1 channel access process (CAT4 LBT) to obtain COT and send PSFCH communications in a scheduled PSFCH opportunity. Channel access types may differ in duration and power consumption. For example, a type 1 channel access process may involve or include a relatively longer channel sensing period than a type 2A or type 2B channel access process. In the case of meeting channel access requirements and / or criteria, it may be desirable to use an available shorter channel access configuration. In addition, a UE communicating in a side link (SL) network may be configured to send and / or receive communications from multiple UEs. In some aspects, a PSFCH opportunity may occur during a COT acquired by a first UE, but the PSFCH communication may be scheduled for transmission to a different second UE. Additionally, a COT sharing indication or other indications associated with a channel access type or configuration for a PSFCH opportunity may conflict. The present disclosure provides systems, schemes, and mechanisms for selecting and performing a channel access procedure for PSFCH communications in a shared frequency band.

[0082] Figure 6 6 is a signaling diagram of a method 600 for wireless communication performed by a first UE (UE A) and a second UE (UE B). The UE may be UE 115 in network 100 and / or UE 215 in network 200. The method 600 may include Figure 5 . The method 600 may include UE A and UE B communicating via a sidelink interface in a shared frequency band. For example, the method 600 may include communicating using a sidelink unlicensed (SL-U) protocol. In some aspects, UE A and UE B may communicate using a PC5 interface. As described above, in order to communicate in a shared or unlicensed frequency resource, one or both of UE A and UE B may perform a channel access procedure (such as listen before talk (LBT)) to acquire a set of time resources in a frequency band or sub-band. The time resource may be referred to as a channel occupancy time (COT).

[0083] Out of Figure 6For purposes of the present disclosure, optional or alternative actions are illustrated with dashed lines and dashed boxes in the example method 600. However, it should be understood that dashed lines and dashed boxes are not the only available options or alternatives, and one or more of the other actions of the method 600 may be removed, duplicated, replaced, switched, or otherwise modified within the scope of the present disclosure.

[0084] At action 602, UE A performs a channel access procedure. The channel access procedure may correspond to a channel access type. For example, the channel access procedure may be a type 1 channel access procedure, a type 2A channel access procedure, a type 2B channel access procedure, or a type 2C channel access procedure. Based on the channel access procedure, UE A may initiate or acquire COT 607. In some aspects, UE B may share a portion of COT 607 to send PSFCH to UE A, as further explained below. In other aspects, UE B may not share COT 607 with UE A. For example, UE A may indicate to UE B that UE A will not share COT 607 with UE B. In some aspects, one or more PSFCH opportunities configured for UE B may be within or during COT 607.

[0085] At action 604, UE B obtains a PSFCH configuration. In some aspects, obtaining the PSFCH configuration may include receiving a signal indicating the configuration from another wireless communication device. For example, in some aspects, action 604 may include UE B receiving a PSFCH configuration from a network device or network entity. For example, UE B may receive the PSFCH configuration from a BS. In other aspects, UE B may receive the PSFCH configuration from another UE. For example, UE B may receive the PSFCH configuration from UE A or from a different UE. In some aspects, UE B may receive a signal with an indicator. The indicator in the signal may indicate or identify one or more PSFCH parameters of the configuration preconfigured at UE B. On the other hand, action 604 may include UE B retrieving the PSFCH from a memory device of UE B. For example, in some aspects, the PSFCH configuration may be hard-coded at UE B. In some aspects, multiple PSFCH configurations may be hard-coded at UE B and UE B may select the PSFCH configuration based on the received signal.

[0086] The PSFCH configuration may include or indicate time and / or frequency resources for the PSFCH opportunity. In some aspects, the PSFCH configuration may include or indicate at least one of the PSFCH periodicity, the total duration of PSFCH transmissions within the observation period, the number of PSFCH transmissions within the observation period, the duration of each PSFCH opportunity or communication, and / or any other suitable parameters. In some aspects, the above parameters may be indicated for SCS or associated with the SCS. For example, a PSFCH configuration with an SCS of 15kHz and a PSFCH periodicity of 1 may indicate 50 PSFCH transmissions within a 50ms observation period. A PSFCH configuration with an SCS of 30kHz and a PSFCH periodicity of 1 may indicate 100 PSFCH transmissions within a 50ms observation period. Tables 4 and 5 include exemplary PSFCH configurations and associated parameters as further explained below.

[0087] At action 606, UE A sends and UE B receives a side link (SL) communication including at least one of a PSCCH or PSSCH communication. In some aspects, action 606 may include UE B receiving and decoding the SCI in the PSCCH and / or PSSCH, and determining the location of at least one associated PSSCH based on the SCI. In some aspects, UE B may receive SL communication in a SL resource pool or SL resource allocation. In some aspects, the SL resource pool may include a set of time and frequency resources. The SL resource pool may be semi-statically configured, dynamically configured, statically configured, and / or any other suitable type of resource configuration. In some aspects, UE B may receive SL communication in a shared frequency band or an unlicensed frequency band. In some aspects, UE B may receive SL communication in a COT associated with a channel access configuration. For example, UE B may receive SL communication from UE A within a COT 607 initiated by UE A. In some aspects, COT 607 may be initiated by UE A based on a channel access process performed at action 602. The channel access process may correspond to a channel access type. For example, the channel access procedure may be a type 1 channel access procedure, a type 2A channel access procedure, a type 2B channel access procedure, or a type 2C channel access procedure. In some aspects, UE B may share a portion of the COT to send the PSFCH to UE A, as further explained below. In other aspects, UE B may not share the COT.

[0088] In some aspects, UE B may receive SL communications within or during a PSFCH period. In some aspects, a PSFCH period may include or extend one or more time slots. In this regard, UE B may be configured with a PSFCH resource configuration indicating a PSFCH periodicity. The PSFCH periodicity may indicate the number of time slots. In some aspects, the PSFCH periodicity may be one time slot, two time slots, four time slots, eight time slots, and / or any other suitable number of time slots. SL communications such as PSSCH received during a PSFCH period may be associated with a PSFCH opportunity of the PSFCH period.

[0089] At action 608, UE B selects a channel access configuration for a PSFCH opportunity in a shared frequency band. In some aspects, selecting a channel access configuration may include selecting or determining a channel access type. In some aspects, UE B may select a channel access type based on SL communication. For example, UE B may select a channel access type based on COT sharing information. In some aspects, COT sharing information may be provided in the SL communication received at action 606. In other aspects, COT sharing information may be provided in different SL communications from different UEs. In some aspects, COT sharing information may include COT sharing information associated with multiple COTs and / or multiple other UEs. In some aspects, COT sharing information may indicate to UE B that a COT associated with a PSFCH opportunity may be shared with UE B. On the other hand, COT sharing information may indicate to UE B that a COT associated with a PSFCH opportunity may not be shared with UE B. In some aspects, COT sharing information may indicate to UE B that a PSFCH opportunity is not within a shared portion of a COT.

[0090] In some aspects, based on the COT not being in the shared portion of the COT, UE B may determine or select a type 1 channel access procedure. In some aspects, the type 1 channel access procedure may include a CAT4 LBT. In some aspects, action 608 may include selecting one or more channel access parameters based on a minimum UL channel access priority category value. In this regard, UL channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 1. In this regard, UE B may select or determine one or more of a contention window size, a maximum COT length, and / or any other suitable parameters associated with a minimum UL channel access priority category value (e.g., 1) shown in Table 1. In some aspects, action 608 may include selecting one or more channel access parameters based on a minimum DL channel access priority category value. In this regard, DL channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 2. In this regard, UE B may select or determine one or more of a contention window size, a maximum COT length, and / or any other suitable parameters associated with a minimum DL channel access priority category value (e.g., 1) shown in Table 2. In another aspect, action 608 may include selecting one or more channel access parameters based on a minimum PSFCH channel access priority category value. In this regard, exemplary PSFCH channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 3. In another aspect, the SL communication may indicate or be associated with a channel access priority category. In some aspects, action 608 may include selecting one or more channel access parameters based on the indicated channel access priority category.

[0091] In this regard, Fig. 7A A PSFCH communication scheme 700a is illustrated, wherein a channel access priority category (CAPC) value for a PSFCH opportunity is indicated in a SL communication. For example, aspects of scheme 700a may be performed by UE A and / or UE B. In scheme 700a, UE A may send a first SL communication including an SCI carried in a PSCCH 722 and SL data carried in a PSSCH 732. The communication may occur during a time period 710 including a plurality of time slots. In this regard, the SL communication may occur during a first time slot of the time period 710, and a PSFCH opportunity 742 may occur within a third time slot 716. In some aspects, the SCI in the PSCCH 722 may indicate a CAPC value for a PSFCH opportunity 742. Thus, UE B may determine the CAPC and corresponding type 1 channel access parameters based on the indicated CAPC value.

[0092] On the other hand, UE B may be scheduled to send a second SL communication immediately after the transmission of the PSFCH in the PSFCH opportunity. For example, UE B may be scheduled to send a second SL communication in a time slot after the PSFCH opportunity. The second SL communication may include PSCCH communication, PSSCH communication, reference signals and / or combinations thereof. In some aspects, the second SL communication may be associated with a channel access priority category. Therefore, in some examples, UE B may select a channel access configuration based on the channel access priority category associated with the second SL communication. In some aspects, UE B may perform a type 1 channel access procedure (further described below) before sending a PSFCH communication in a PSFCH opportunity, and may continue to send a second SL communication after the PSFCH communication without performing additional channel sensing and / or without performing additional channel access procedures for the second SL communication.

[0093] In this regard, Figure 7B A PSFCH communication scheme 700b is illustrated, in which a CAPC value for a PSFCH opportunity may be indicated and / or determined based on the scheduled SL communication. For example, aspects of scheme 700b may be performed by UE A and / or UE B. In scheme 700b, UE A may send a first SL communication including an SCI carried in a PSCCH 722 and SL data carried in a PSSCH 732. The communication may occur during a time period 710 including a plurality of time slots. In this regard, a first SL communication may occur during a first time slot of the time period 710, and a PSFCH opportunity 742 may occur within a third time slot 716. UE B may be scheduled to send a second SL communication including a second PSCCH 724 and a second PSSCH 734 in a time slot immediately following the PSFCH opportunity 742.

[0094] In some aspects, UE B may send a second SL communication with a cyclic prefix extension to at least partially fill at least one gap symbol between a PSFCH opportunity and the start of the second SL communication. In some aspects, if a channel access priority category value associated with the PSFCH communication is determined based on a channel access priority category value associated with the second SL communication, UE B may send the second SL communication without performing additional channel access procedures.

[0095] Figure 7CA PSFCH communication scheme 700c is illustrated, in which the UE may send SL communication after sending the PSFCH communication without additional channel sensing. Similar to schemes 700a and 700b, in scheme 700c, UE A sends in the first time slot within the period 710 and UE B receives the first SL communication including the first PSCCH 722 and the first PSSCH 732 in the first time slot within the period. UE A may send PSFCH in the PSFCH opportunity 742 in the third time slot 716 of the period 710 based on the first SL communication. In some aspects, UE B may perform a channel access procedure before sending the PSFCH. In some aspects, UE B may perform a type 1 channel access procedure before sending the PSFCH. On the other hand, UE A may share a portion of the COT with UE B so that UE B may perform a type 2 channel access procedure instead of a type 1 channel access procedure. In some aspects, the period 710 represents the COT acquired by UE A. In some aspects, UE B may perform a type 1 channel access procedure based on the CAPC value, as explained above. For example, the CAPC value may be indicated in the SCI carried in the first PSCCH 722. In another aspect, the CAPC value may be based on the PSFCH configuration for UE B.

[0096] The second SL communication including the second PSCCH 724 and the second PSSCH 734 may be associated with a CAPC value. The CAPC value of the second SL communication may be the same as or different from the CAPC value of the PSFCH opportunity 742. In some aspects, if the CAPC value of the PSFCH opportunity 742 is equal to or greater than the CAPC value of the second SL communication, UE B may be configured to send the second SL communication without additional channel sensing or channel access procedures. In other aspects, UE B may be configured to send a second SL communication for any combination of CAPC values ​​for the PSFCH opportunity 742 and the second SL communication by closing the gap between the PSFCH opportunity 742 and the second SL communication. In this regard, UE B may be configured to attach a CP extension 772 before the second SL communication to at least partially close at least one gap symbol between the PSFCH opportunity 742 and the second SL communication.

[0097] Reference again Figure 6, on the other hand, action 608 may include UE B selecting a channel access procedure based on a PSFCH configuration. In some aspects, method 600 may include UE B receiving an information element, a control element, and / or any other suitable configuration including or indicating a PSFCH configuration. The PSFCH configuration may include or indicate time and / or frequency resources for a PSFCH opportunity. In some aspects, the PSFCH configuration may include or indicate at least one of a PSFCH periodicity, a total duration of PSFCH transmissions within an observation period, a number of PSFCH transmissions within an observation period, a duration of each PSFCH opportunity or communication, and / or any other suitable parameter. In some aspects, the parameters indicated above may be indicated for or associated with an SCS. For example, a PSFCH configuration with an SCS of 15kHz and a PSFCH periodicity of 1 may indicate 50 PSFCH transmissions within a 50ms observation period. A PSFCH configuration with an SCS of 30kHz and a PSFCH periodicity of 1 may indicate 100 PSFCH transmissions within a 50ms observation period. In some aspects, action 608 may include UE B selecting a channel access configuration based on the PSFCH configuration. In some aspects, UE B may select the channel access configuration based on one or more of the above-described PSFCH parameters, including PSFCH periodicity, total duration of PSFCH transmissions within the observation period, number of PSFCH transmissions within the observation period, duration of each PSFCH opportunity or communication, and / or any other suitable parameter.

[0098] In some aspects, action 608 may include UE B selecting a channel access configuration without channel sensing based on the PSFCH configuration. For example, UE B may select a type 2C channel access configuration or a non-sensing channel access configuration based on the configured PSFCH periodicity reaching or exceeding a configured threshold. In this regard, Fig. 8AA PSFCH configuration 800a is illustrated, wherein a plurality of PSFCH opportunities 808 occur within an observation period 802. In some aspects, the observation period 802 may have a duration of 50ms. In other aspects, the observation period 802 may have a duration of 100ms. However, the present disclosure also contemplates other durations of the observation period 802. In the illustrated example, the PSFCH configuration 800a has a PSFCH periodicity of 2 slots. Therefore, there is one PSFCH opportunity 808 for every two slots in the observation period 802. As explained above, UE B may be configured with a short control signaling configuration that allows some short signals that meet one or more thresholds or other short control signaling criteria to be sent. In some aspects, the configuration 800a may meet the short control signaling criteria for the first portion 804 of the observation period 802, but not for the second portion 806. Therefore, UE B may be configured to send the PSFCH of the opportunity 808 in the first portion 804 of the observation period 802 without performing an additional channel access process. However, UE B may not rely on the short control signaling configuration for the second portion 806 of the observation period 802. For example, UE B may be configured to perform type 1 channel access of the PSFCH opportunity 808 in the second portion 806 of the observation period 802. In one example, if the PSFCH configuration 800a indicates a PSFCH periodicity of four time slots, UE B may be allowed to send PSFCH communications in each PSFCH opportunity 808 of the observation period 802 without performing additional channel access procedures or channel sensing (e.g., type 2C channel access).

[0099] In some aspects, UE B may select a type 2C channel access configuration based on one or more short control signaling conditions, thresholds, or other parameters being satisfied. In another aspect, UE B may select type 2C channel access based on the number of PSFCH transmissions within the observation period satisfying a threshold. In other aspects, UE B may select type 2C channel access based on the total duration of PSFCH transmissions within the observation period satisfying a threshold. For example, UE B may select type 2C channel access for FR1 based on the number of PSFCH transmissions within the observation period being equal to or less than 50 and the total duration of PSFCH transmissions in the observation period being less than 2.5 ms. In another example, UE B may select type 2C channel access for FR2 based on the total duration of PSFCH transmissions in the observation period being less than 10 ms.

[0100] In some aspects, UE B may select type 2C channel access for one or more PSFCH opportunities within the observation period based on the PSFCH configuration, but may select type 1, type 2A, or type 2B channel access for one or more other PSFCH opportunities during the observation period, as described above with respect to Fig. 8A Described. For example, method 600 may include selecting a type 2C channel access procedure for a PSFCH opportunity; and selecting a type 1 channel access procedure, a type 2A channel access procedure, or a type 2B channel access procedure for a second PSFCH opportunity different from the PSFCH opportunity. In some aspects, UE B may be configured to determine or identify a first portion of an observation period in which type 2C channel access is selected and a second portion in which different types of channel access are selected. For example, the first portion of the observation period may be determined or identified based on the PSFCH opportunity or the communication satisfying one or more short control signaling conditions in the first portion. UE B may select type 1, type 2A, or type 2B channel access for PSFCH opportunities in the remaining second portion of the observation period. Table 4 in the Appendix shows the duration and other parameters of the observation window in FR1 for which sensing (e.g., type 2C channel access) may not be used. As shown in Table 4, UE B may select the first portion or the second (last) portion of the observation period for no sensing (type 2C channel access) or for other channel access types.

[0101] On the other hand, the PSFCH configuration may indicate a partial automatic gain control (AGC) symbol for one or more PSFCH opportunities in the observation window. In some aspects, the PSFCH configuration may indicate a partial AGC symbol for each PSFCH opportunity in the observation period. In other aspects, the PSFCH configuration may indicate a partial AGC symbol only for a portion of the observation period. In this regard, Table 5 in the Appendix shows that if a partial AGC symbol is used for PSFCH transmission, other periodicities other than 4 may be eligible for non-sensing channel access (e.g., type 2C channel access). In this regard, if a partial AGC symbol is used, the PSFCH configuration may indicate that UE B uses type 2C channel access for a PSFCH periodicity of 4 or 2 for SCS values ​​of 15kHz and 30kHz. On the other hand, the PSFCH configuration may indicate that UE B uses type 2C channel access for the first portion of the observation period, and uses different types of channel access procedures with sensing (e.g., type 1, type 2A) for the second portion of the observation period. In this regard, the use of partial AGC symbols may increase the duration of the portion of the observation period for which type 2C channel access may be used. In addition, the AGC symbol length may be long enough to ensure AGC training performance. For example, in some aspects, the PSFCH configuration may instruct UE B to use 2 / 3 of the OFDM symbol for AGC with one or more PSFCH transmissions. In other aspects, the PSFCH configuration may instruct UE B to use 1 / 2 of the OFDM symbol for AGC with one or more PSFCH transmissions. The PSFCH configuration may instruct UE B to use a portion of the AGC symbols for all PSFCH opportunities during the observation period or for only a portion of the observation period.

[0102] Figure 8B and 8C PSFCH configurations 800b and 800c with partial AGC symbols are illustrated. Figure 8B , configuration 800b includes multiple PSFCH opportunities, which include resources for PSFCH symbols 809 and AGC symbols 807, 811 within the observation period 802. In some aspects, the first portion 804 of the observation period 802 includes PSFCH opportunities in which partial AGC symbols 807 are used. The second portion 806 of the observation period 802 includes PSFCH opportunities in which full AGC symbols 811 are used. In some aspects, relative to configuration 800a in which full AGC symbols can be used for all PSFCH opportunities 808, the use of partial AGC symbols 807 can increase the number of PSFCH communications that can be sent within the observation period 802 without additional channel access procedures or channel sensing. As described above, the partial AGC symbol 807 can occupy 2 / 3, 1 / 2, or any other suitable portion of the full OFDM symbol. Reference Figure 8C , PSFCH configuration 800c involves using partial AGC symbols 807 for all PSFCH opportunities in observation period 802. In some aspects, using partial AGC symbols 807 for the entire observation period 802 may increase the number of PSFCHs that may be communicated based on short control signaling criteria and without additional channel access procedures.

[0103] At action 610, UE B performs a channel access procedure based on the channel access type or configuration selected at action 608. In some aspects, the channel access procedure may include or involve channel sensing. In other aspects, the channel access procedure may not include or involve channel sensing (e.g., type 2C channel access). In some aspects, action 610 may include UE B performing a channel access procedure based on a type 1 channel access parameter, which is selected based on at least one of the lowest UL CAPC value, the lowest DL CAPC value, or the lowest PSFCH CAPC value, as explained above. In some aspects, UE B may not perform channel sensing at action 610. For example, UE B may select a type 2C channel access procedure for a PSFCH opportunity at action 608. In other aspects, UE B may perform a channel access procedure based on an indication of a channel access type sent by UE A. On the other hand, UE B may perform a channel access procedure based on an indication of a channel access type sent by the network via a network entity.

[0104] At action 612, UE B sends PSFCH communications in a PSFCH opportunity in a shared frequency band based on the channel access configuration selected at action 608 and the SL communication received at action 606. In some aspects, sending PSFCH communications may include sending AGC symbols and PSFCH symbols during the PSFCH opportunity and based on the PSFCH configuration. In some aspects, multiple PSFCH communications may be sent simultaneously at action 612. Each PSFCH may be mapped to a corresponding PSSCH received from UE A and / or other UEs. In some aspects, the PSFCH may be sent in one or more resource blocks (RBs). In some aspects, the PSFCH may be sent in one or more RB interlaces, wherein each interlace includes multiple RBs separated from each other by at least one other RB corresponding to different RB interlaces.

[0105] At action 614, UE B sends a second SL communication after sending the PSFCH communication. In some aspects, UE B may send the second SL communication after sending the PSFCH communication without performing additional channel sensing. For example, UE B may perform a type 1 channel access procedure before sending the PSFCH communication, and may send the second SL communication based on the type 1 channel access procedure performed for the PSFCH communication. In some aspects, sending the second SL communication may include sending the second SL communication with a cyclic prefix (CP) extension in at least one gap symbol between the PSFCH communication and the second SL communication. In some aspects, sending the second SL communication may be based on at least one of the first CAPC value of the PSFCH communication and the second CAPC value of the second SL communication. In some aspects, if the first CAPC value of the PSFCH communication is equal to or greater than the second CAPC value of the second SL communication, UE B may send the second SL communication without additional sensing.

[0106] In some aspects, sending a PSFCH communication may include sending the PSFCH communication using a portion of the AGC symbol before the PSFCH symbol. In some aspects, sending a PSFCH communication may include sending 2 / 3 of the AGC symbol, 1 / 2 of the AGC symbol, or any other suitable portion of the AGC symbol together with the PSFCH symbol. In other aspects, sending a PSFCH communication may include sending a full AGC symbol together with the PSFCH symbol. In some aspects, UE B may send a PSFCH communication without channel sensing based on one or more short control signaling configurations or parameters, as explained above.

[0107] In some aspects, a UE may initiate a COT and share the COT with a receiving UE. A receiving UE may use a shared portion of the COT to send a PSFCH. In some aspects, a UE that initiates or acquires a COT may indicate a channel access type to a receiving UE. A UE that initiates a COT may also indicate whether CP extension should be used for PSFCH communication, a CAPC value for PSFCH communication, and / or any other associated parameters for PSFCH communication. For example, a UE that initiates a COT may indicate that a receiving UE uses type 2 channel access for PSFCH communication. In some aspects, a UE that initiates a COT may indicate COT sharing information and / or channel access type and other parameters in an SCI. However, there may be challenges and problems in indicating channel access types and sharing COTs. For example, a UE that sends a PSCCH / PSSCH with a channel access type indication may not be able to determine or correctly predict whether a PSFCH communication from a receiving UE will be sent in a shared portion of the COT. For example, a sending UE may not be a UE that initiates a COT or shares a COT. In addition, a receiving UE may receive conflicting and / or contradictory COT sharing indications or channel access indications for PSFCH opportunities. In addition, the transmitting UE may indicate type 1 channel access to the receiving UE based on the transmitting UE determining that the PSFCH opportunity is not within the shared portion of the COT of the transmitting UE. However, the receiving UE may subsequently receive COT sharing information indicating that the PSFCH opportunity is within the shared portion of the COT from a different transmitting UE. Therefore, the type 1 channel access procedure indicated by the first transmitting UE may be unnecessary.

[0108] The present disclosure also describes systems and methods for determining and communicating PSFCH based on a channel access type indicated by an indication conveyed from one or more UEs. For example, in some aspects, a UE initiating a COT may be configured to send COT sharing information in an SCI to one or more UEs indicating that the UE initiating the COT will share a portion of the COT with one or more UEs. Thus, the UE sending the PSSCH may determine that the PSFCH of the receiving UE may be in a portion of the shared COT from the UE initiating the COT, and indicate the channel access type based on the COT sharing information. In other examples, the UE initiating the COT may indicate that the COT cannot be used for sharing with one or more other UEs. In another example, the UE initiating the COT may indicate that at least one UE may share the COT, and at least one other UE may not share the COT.

[0109] Fig. 9 9 is a signaling diagram of a method 900 for wireless communication performed by a first UE (UE A), a second UE (UE B), and a third UE (UE C). UE A, B, and / or C may be UE 115 in network 100 and / or UE 215 in network 200. Method 900 may include Figures 6 to 8C. Method 900 may include UE A, B, and C communicating via a side link interface in a shared frequency band. For example, method 900 may include communicating using an SL-U protocol. In some aspects, UE A, B, and / or C may communicate using a PC5 interface. As described above, in order to communicate in a shared or unlicensed frequency resource, one or more of UE A, B, and / or C may perform a clear channel assessment (CCA) (such as listen before talk (LBT)) to obtain a set of time resources in a frequency band or sub-band. The time resource may be referred to as a channel occupancy time (COT).

[0110] At action 902, UE A sends and UE B receives a SL communication including at least one of a PSCCH or a PSSCH. In some aspects, the SL communication includes a PSCCH carrying an SCI and a PSSCH carrying additional SCI and / or SL data. In some aspects, the SCI may indicate to UE B the COT sharing information of the COT 909 acquired by UE A. The dashed brackets of COT 909 may indicate that COT 909 is optional in method 900. On the other hand, the SCI sent at action 902 may indicate to UE B a channel access type for at least one PSFCH opportunity associated with the PSSCH. For example, in some aspects, UE A may indicate to UE B that COT 909 cannot be used for sharing with UE B. On the other hand, the SCI may instruct UE B to perform a type 1 channel access procedure at least for the PSFCH associated with the PSSCH communicated at action 902.

[0111] At action 904, UE C performs a channel access procedure to initiate or acquire a COT. In some aspects, the channel access procedure may be a type 1 channel access procedure. For example, UE C may perform a CAT4 LBT with a random backoff period. Based on the channel access procedure, UE C initiates a COT 907. COT 907 may include a time period during which UE C may communicate with one or more UEs in the network (including UE A and / or UE B). In some aspects, the time period may be configured as a value in an absolute time unit (such as ms or μs). On the other hand, the time period may be configured as a value in a frame, a subframe, and / or a time slot.

[0112] At action 906, UE C communicates COT sharing information (SI) and / or a channel access type indication to at least one of UE B and / or UE A. In some aspects, UE C may indicate that COT 907 can be used for sharing with at least one of UE A and / or UE B. In other aspects, COT-SI may indicate that COT-SI cannot be used for sharing with at least one of UE A and / or UE B. In some aspects, action 906 includes UE C indicating to at least one of UE A and / or UE B the channel access type for PSFCH communication within COT 907. For example, UE C may instruct UE A and / or UE B to perform a type 2 channel access procedure, such as a type 2A or type 2B channel access. On the other hand, UE C may instruct UE A and / or UE B to perform a type 2C channel access procedure so that no additional channel sensing is performed before sending the PSFCH.

[0113] At action 908, UE B selects or determines a channel access configuration or type for a PSFCH opportunity based on at least one of the COT-SI or the channel access type indication received at action 906 or the PSCCH / PSSCH received at action 902. In some aspects, UE B may select a channel access type based on the COT-SI provided by UE C. For example, UE B may select channel access type 2 based on UE C indicating that COT 907 will be shared with UE B, wherein the PSFCH opportunity is within the shared portion of COT 907. On the other hand, UE B may select channel access type 1 based on UE C indicating that COT 907 will not be shared with UE B. On the other hand, UE B may select a channel access type based on the indication provided by UE C at action 906. On the other hand, UE B may select a channel access type based on the indication provided by UE A in action 902. In other aspects, UE B may select a channel access type based on the COT-SI provided by UE A in the PSCCH communicated at action 902.

[0114] In some aspects, the COT-SI may include or indicate at least one of the COT duration and the available RB set for sharing. In some aspects, the COT duration may indicate the length starting from the time slot in which the COT sharing information is received. On the other hand, the available RB set indicated in the COT-SI may be available or valid until the end of the COT. Similarly, if the COT-SI indicates that COT sharing is unavailable, or at least a portion of the COT cannot be used for sharing, the COT-SI may indicate at least one of the duration or time domain position of the unavailable portion of the COT and / or the unavailable RB set. In some aspects, if the available / unavailable RB set is not indicated in the COT-SI, UE B may assume that all RB sets within the COT are not shareable. In addition, in some aspects, the COT-SI may indicate a combination of COT sharing information and COT sharing unavailability information. For example, the COT sharing information may indicate both the shareable portion of the COT and the unavailable portion of the COT. In some aspects, the COT sharing information may indicate one or more UEs that can share a portion of the COT, and one or more other UEs that may not share a portion of the COT.

[0115] COT sharing information or unavailability information may be indicated in the SCI. For example, COT sharing information may be indicated in the SCI 2 format. In some aspects, COT sharing information may be provided in the SCI-2C format. In other aspects, a new SCI format may be defined and / or configured to indicate COT sharing and / or unavailability information. If SCI-2C is used, UE B may be configured to distinguish whether SCI-2C indicates inter-UE coordination information or indicates COT sharing and / or unavailability information. In some aspects, SCI-2C may indicate that the SCI includes COT sharing information based on the bit value of at least one of the SCI-2C fields. For example, SCI-2C may include a reference slot field. In some aspects, if the reference slot field is set to all 0s or all 1s, SCI-2C may indicate that the SCI includes COT sharing information. In some aspects, the TRIV field of SCI-2C may be used to indicate the duration of the COT duration or the duration of the shared portion of the COT. In another aspect, at least one of the FRIV field and / or the first subchannel field of the SCI-2C may indicate an available or unavailable RB set for COT sharing. In another aspect, the set type field of the SCI-2C may be used to indicate whether the SCI-2C is a COT sharing indication or a COT unavailability indication. In other aspects, different time resource indicator values ​​(TRIV), frequency resource indicator values ​​(FRIV), and / or the first subchannel field may be defined in the SCI to indicate a combination of COT sharing and COT unavailability information.

[0116] On the other hand, the SCI format may be provided to include at least one of a COT sharing indication field, a COT unavailability field, a COT duration field, an RB set field, and / or any other suitable field. In some aspects, the COT duration field may be configured by RRC or PC5-RRC. On the other hand, a set of COT duration values ​​of the COT duration field may be configured by RRC or PC5-RRC. For example, the COT duration field may indicate one of the configured values. On the other hand, an additional field may be included in the SCI to indicate whether the SCI is a COT sharing indication or a COT unavailability indication.

[0117] In some aspects, action 908 may include UE B selecting a type 2A channel access type in response to receiving a COT sharing indication indicating that a PSFCH opportunity is scheduled for a shared portion of a COT from at least one of UE A or UE C. In other aspects, action 908 may include UE B selecting a type 1 channel access type in response to receiving a COT unavailability indication from at least one of UE A or UE C, or based on the PSFCH opportunity being scheduled outside the shared portion of the COT. In some aspects, UE B may receive multiple COT sharing information indications from different UEs (such as UE A and UE C). In some aspects, the COT duration may occur in overlapping time periods. In other aspects, the shared COTs may not overlap. In some aspects, only one of the shared COTs occurs during the PSFCH opportunity. In other aspects, both of the shared COTs occur during or do not occur during the PSFCH opportunity. Action 908 may include UE B selecting or following one of the multiple COT sharing indications. In some aspects, UE B may select a COT-SI indication received in the most recent or latest SCI. On the other hand, UE B may select or follow the joint COT sharing information. For example, UE B may select the channel access type based on a combination of COT sharing information provided by UE A and UE C. In this regard, if the first shared COT occurs entirely within a longer second shared COT, UE B may select the channel access type based on the COT sharing information associated with the longer second shared COT. On the other hand, UE B may regard a scenario where multiple COT sharing indications are provided by the same UE and the multiple COT sharing indications indicate different COT sharing information as an error condition.

[0118] According to another aspect, action 908 may include UE B selecting a channel access type based on two or more channel access type indications provided by at least one of UE A or UE C. In some aspects, UE B may select the indicated channel access type associated with the shortest sensing duration for the PSFCH opportunity. For example, if UE B receives a channel access type indication of both type 2B channel access and type 2A channel access for the same PSFCH opportunity, UE B may select type 2B channel access. In another example, if UE B receives a channel access type indication of both type 1 channel access and type 2A channel access for the same PSFCH opportunity, UE B may select type 2A channel access. In another example, if UE B receives a channel access type indication of both type 2B channel access and type 2C channel access for the same PSFCH opportunity, UE B may select type 2C channel access. On the other hand, UE B may select the channel access type indicated in the most recently received SCI to perform PSFCH communication in the same time slot and the same channel access bandwidth. In another example, action 908 may include UE B treating the conflicting channel access type indication as an error condition. Thus, for example, if UE B receives a different channel access type indication associated with the same PSFCH opportunity, UE B may be configured to select type 1 channel access. In another aspect, UE B may be configured to select a channel access type for a PSFCH opportunity based on an indication from at least one of UE A or UE C indicating a request to share a COT acquired by UE B for PSFCH transmission. Thus, UE B may select type 1 channel access in response to receiving the indication, and may indicate to UE A and / or UE C that a remaining portion of the acquired COT can be used for sharing for other communications from UE A and / or UE C.

[0119] In another aspect, UE B may select a channel access type based on an indication from UE A and / or UE C that enables or disables UE B to use a channel access type indication from another UE. For example, UE C may send a signal to UE B indicating that UE B may use the channel access type indicated by UE C for PSFCH transmission to another UE (e.g., UE A). In some aspects, the signal may include an SCI. For example, the SCI may include a field indicating whether UE B is enabled or disabled to use the channel access indication from UE C to send PSFCH communications to UE A.

[0120] On the other hand, UE B may receive COT sharing information from UE A that conflicts with the channel access type indication from UE C. For example, UE A may send COT sharing information indicating that UE B shares a portion of UE A's COT to transmit a PSFCH. UE B may be configured to use type 2A channel access for PSFCH communications in the shared portion of the COT. However, UE C may send an SCI to UE B indicating that UE B uses a different channel access type for PSFCH opportunities occurring within the shared portion of UE A's COT. For example, UE C may instruct UE B to use type 1 channel access or type 2B channel access. According to aspects of the present disclosure, action 908 may include UE B selecting a channel access type based on one or both of the conflicting indications.

[0121] For example, action 908 may include UE B receiving COT sharing information associated with a first channel access type for a PSFCH opportunity from UE A, and receiving a channel access type indication indicating a second channel access type different from the first channel access type from UE C. In some aspects, action 908 may include UE B selecting a channel access type with a shorter sensing duration for PSFCH transmission. On the other hand, UE B may select a channel access type associated with a most recently received SCI. For example, if the most recently received SCI includes COT sharing information for a COT in which a PSFCH opportunity is scheduled, UE B may select type 2A channel access based on an indication of a shared COT. In another example, if the most recently received SCI includes an indication of type 1 channel access, UE B may select type 1 channel access even if the PSFCH opportunity occurs during a shared portion of the COT. On the other hand, UE B may treat conflicting indications of COT sharing and channel access as an error condition. For example, UE B may be configured to select type 1 channel access if UE B receives a conflicting indication of a channel access type. In another aspect, UE B may be configured to select a channel access type for a PSFCH opportunity based on an indication from at least one of UE A or UE C indicating a request to share a COT acquired by UE B for PSFCH transmission. Thus, UE B may select type 1 channel access in response to receiving the indication, and may indicate to UE A and / or UE C that the remaining portion of the acquired COT can be used for sharing for other communications from UE A and / or UE C. In other words, if UE B receives an indication from UE A to use type 2A channel access for a PSFCH opportunity, and UE C indicates to UE B a request to share the COT acquired for PSFCH transmission, UE B may select type 1 channel access based on the indication from UE C, and share a portion of the COT with UE C.

[0122] At action 910, UE B performs a channel access procedure based on the channel access configuration or channel access type selected at action 908. In some aspects, action 910 may include UE B performing channel sensing. For example, action 908 may include UE B performing a type 1, type 2A, or type 2B channel access procedure. On the other hand, action 908 may not include channel sensing. For example, action 908 may include UE B performing a type 2C channel access procedure. In another example, method 900 may not include the channel access procedure at action 910. For example, UE B may be configured to send PSFCH communications based on a short control signaling configuration so that channel sensing is not performed. In this regard, action 910 is shown as a dotted box. The dotted box may indicate that channel sensing or a channel access procedure is not performed before sending the PSFCH.

[0123] At action 912, UE B sends PSFCH communication in the PSFCH opportunity in the shared frequency band based on the channel access configuration selected at action 908 and the SL communication received at action 902. In some aspects, sending PSFCH communication may include sending AGC symbols and PSFCH symbols during the PSFCH opportunity and based on the PSFCH configuration. In some aspects, multiple PSFCH communications may be sent simultaneously at action 912. Each PSFCH may be mapped to a corresponding PSSCH received from UE A, UE C and / or other UEs. In some aspects, PSFCH may be sent in one or more resource blocks (RBs). In some aspects, PSFCH may be sent in one or more RB interlaces, wherein each interlace includes multiple RBs separated from each other by at least one other RB corresponding to different RB interlaces.

[0124] At action 914, UE B may communicate PSCCH and PSSCH with UE A immediately after the transmission of the PSFCH communication at action 912. In some aspects, action 914 includes UE B sending PSCCH / PSSCH to UE A. For example, in some aspects, UE B may perform a type 1 channel access procedure to obtain a COT for a PSFCH opportunity. UE B may send PSCCH / PSSCH communication immediately after PSFCH communication. In some aspects, UE B may send PSCCH / PSSCH without performing additional channel sensing between PSFCH and PSCCH / PSSCH. For example, UE B may attach a CP extension to at least partially fill the gap between PSFCH and PSCCH / PSSCH. In other aspects, action 914 may include UE A sending PSCCH / PSSCH to UE B. For example, as described above, method 900 may include UE A instructing UE B to obtain a COT for PSFCH and share the COT with UE A to receive PSCCH / PSSCH from UE A.

[0125] Fig.10 1 is a block diagram of an exemplary UE 1000 according to some aspects of the present disclosure. UE 1000 may be the Figure 1 UE 115 discussed in or above in Figure 2 215 discussed in . As shown, UE 1000 may include a processor 1002, a memory 1004, a sidelink communication module 1008, a transceiver 1010 (including a modem subsystem 1012 and a radio frequency (RF) unit 1014), and one or more antennas 1016. These elements may communicate with each other directly or indirectly, for example, via one or more buses.

[0126] The processor 1002 may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1002 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0127] The memory 1004 may include cache memory (e.g., cache memory of the processor 1002), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In one aspect, the memory 1004 includes a non-transitory computer-readable medium. The memory 1004 may store or have recorded thereon instructions 1006. The instructions 1006 may include instructions that, when executed by the processor 1002, cause the processor 1002 to perform the various aspects of the present disclosure (e.g., Figures 6 to 9 Instructions 1006 may also be referred to as program code. Program code may be used to cause the wireless communication device to perform these operations, for example, by causing one or more processors (such as processor 1002) to control or command the wireless communication device to do so. The terms "instructions" and "code" should be broadly interpreted to include any type of computer-readable statements. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, processes, etc. "Instructions" and "code" may include a single computer-readable statement or many computer-readable statements.

[0128] The sidelink communication module 1008 may be implemented via hardware, software, or a combination thereof. For example, the sidelink communication module 1008 may be implemented as a processor, circuit, and / or instructions 1006 stored in the memory 1004 and executed by the processor 1002. In some examples, the sidelink communication module 1008 may be integrated within the modem subsystem 1012. For example, the sidelink communication module 1008 may be implemented by a combination of software components (e.g., executed by a DSP or general purpose processor) and hardware components (e.g., logic gates and circuits) within the modem subsystem 1012.

[0129] The side link communication module 1008 may be used in various aspects of the present disclosure, such as Figures 6 to 9Aspects of the invention. For example, the sidelink communication module 1008 may be configured to: receive SL communications; select a channel access configuration for a PSFCH opportunity in a shared frequency band; and send PSFCH communications in a PSFCH opportunity in a shared frequency band based on the selected channel access configuration and the SL communication. In some aspects, the sidelink communication module 1008 may be configured to: receive SL communications from a second UE; and select a type 1 channel access procedure based on COT shared information. For example, the sidelink communication module 1008 may be configured to: select a type 1 channel access procedure based on a determination that the PSFCH opportunity is not within a shared portion of the COT. In other aspects, the sidelink communication module 1008 may be configured to: select a channel access procedure based on an indication that the PSFCH opportunity is within a shared portion of the COT or based on a channel access type indication provided by another UE. In some aspects, the sidelink communication module 1008 may be configured to: determine or select one or more parameters of the channel access configuration based on an indication of a channel access priority category (CAPC) value.

[0130] In other aspects, the sidelink communication module 1008 may be configured to use a short control signaling configuration to send PSFCH communications without additional channel sensing. For example, the sidelink communication module 1008 may be configured to select a type 2C channel access configuration based on determining that the PSCH configuration satisfies one or more short control signaling criteria. In other aspects, the sidelink communication module 1008 may be configured to select a channel access configuration in response to receiving multiple conflict indications for channel access, as described above with respect to Fig. 9 described.

[0131] As shown, the transceiver 1010 may include a modem subsystem 1012 and an RF unit 1014. The transceiver 1010 may be configured to communicate bidirectionally with other devices, such as BS 105. The modem subsystem 1012 may be configured to modulate and / or encode data from the memory 1004 and / or the sidelink communication module 1008 according to a modulation and coding scheme (MCS) (e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a polarization coding scheme, a digital beamforming scheme, etc.). The RF unit 1014 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) the modulated / encoded data (e.g., SCI, sidelink data, RRC IE) from the modem subsystem 1012 (for outbound transmission) or from another source (such as UE 115 or BS 105). The RF unit 1014 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in the transceiver 1010, the modem subsystem 1012 and the RF unit 1014 may be separate devices that are coupled together at the UE 115 to enable the UE 115 to communicate with other devices.

[0132] The RF unit 1014 may provide modulated and / or processed data (e.g., data packets (or more generally, data messages that may include one or more data packets and other information)) to the antenna 1016 for transmission to one or more other devices. The antenna 1016 may further receive data messages sent from other devices. The antenna 1016 may provide the received data messages for processing and / or demodulation at the transceiver 1010. The transceiver 1010 may provide the demodulated and decoded data (e.g., side link configuration, resource pool configuration) to the side link communication module 1008 for processing. The antenna 1016 may include multiple antennas of similar or different designs to maintain multiple transmit links. The RF unit 1014 may configure the antenna 1016.

[0133] In some aspects, the transceiver 1010 is configured to perform LBT in a shared radio band based on a first starting point among multiple starting points within the LBT gap duration, and to send a first side link communication to a second UE (e.g., UE 115, 215 and / or 1000) in the shared radio band based on the LBT, for example by coordinating with the side link communication module 1008, the first side link communication comprising a first SCI and first side link data.

[0134] In one aspect, the UE 1000 may include multiple transceivers 1010 that implement different RATs (e.g., NR and LTE). In one aspect, the UE 1000 may include a single transceiver 1010 that implements multiple RATs (e.g., NR and LTE). In one aspect, the transceiver 1010 may include various components, where different combinations of components may implement different RATs.

[0135] Fig.11 is a block diagram of an exemplary BS 1100 according to some aspects of the present disclosure. BS 1100 may be as described above in Figure 1 BS 105 in network 100 discussed in or as described above in Figure 2 1. As shown, BS 1100 may include a processor 1102, a memory 1104, a side link configuration module 1108, a transceiver 1110 (including a modem subsystem 1112 and an RF unit 1114), and one or more antennas 1116. These elements may communicate with each other directly or indirectly, for example, via one or more buses.

[0136] The processor 1102 may have various features as a particular type of processor. For example, these features may include a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1102 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0137] Memory 1104 may include cache memory (e.g., cache memory of processor 1102), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory devices, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, memory 1104 may include non-transitory computer-readable media. Memory 1104 may store instructions 1106. Instructions 1106 may include instructions that, when executed by processor 1102, cause processor 1102 to perform the instructions described herein (e.g., Figures 6 to 9 Instructions 1106 may also be referred to as code, which may be broadly interpreted to include any type of computer-readable statements, such as those described above. Fig.10 discussed.

[0138] The sidelink configuration module 1108 may be implemented via hardware, software, or a combination thereof. For example, the sidelink configuration module 1108 may be implemented as a processor, circuit, and / or instructions 1106 stored in the memory 1104 and executed by the processor 1102. In some examples, the sidelink configuration module 1108 may be integrated within the modem subsystem 1112. For example, the sidelink configuration module 1108 may be implemented by a combination of software components (e.g., executed by a DSP or general purpose processor) and hardware components (e.g., logic gates and circuits) within the modem subsystem 1112.

[0139] The side link configuration module 1108 may be used in various aspects of the present disclosure, such as Figures 6 to 9 For example, the sidelink configuration module 1108 may be configured to send one or more information elements and / or control elements indicating SL resource pool configuration, PSFCH configuration, channel access priority configuration, and / or any other suitable type of configuration. For example, the sidelink configuration module 1108 may be configured to send one or more RRC IEs, MAC CEs, and / or any other suitable communications including or indicating these configurations.

[0140] As shown, the transceiver 1110 may include a modem subsystem 1112 and an RF unit 1114. The transceiver 1110 may be configured to communicate bidirectionally with other devices (such as UE 115 and / or 1000 and / or another core network element). The modem subsystem 1112 may be configured to modulate and / or encode data according to an MCS (e.g., an LDPC decoding scheme, a turbo decoding scheme, a convolutional decoding scheme, a polarization decoding scheme, a digital beamforming scheme, etc.). The RF unit 1114 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / encoded data (e.g., PDCCH, PDSCH, SSB, sidelink configuration, sidelink resource pool configuration, etc.) from the modem subsystem 1112 (for outbound transmission) or from another source (such as UE 115 and / or UE 1000). The RF unit 1114 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in the transceiver 1110 , the modem subsystem 1112 and / or the RF unit 1114 may be separate devices that are coupled together at the BS 105 to enable the BS 105 to communicate with other devices.

[0141] The RF unit 1114 may provide modulated and / or processed data (e.g., data packets (or more generally, data messages that may include one or more data packets and other information)) to the antenna 1116 for transmission to one or more other devices. For example, according to some aspects of the present disclosure, this may include the transmission of information to complete attachment to the network and communication with the pre-occupied UE 115 or 1000. The antenna 1116 may also receive data messages sent from other devices and provide the received data messages for processing and / or demodulation at the transceiver 1110. The transceiver 1110 may provide the demodulated and decoded data to the sidelink configuration module 1108 for processing. The antenna 1116 may include multiple antennas of similar or different designs to maintain multiple transmit links.

[0142] In one aspect, the BS 1100 may include multiple transceivers 1110 that implement different RATs (e.g., NR and LTE). In one aspect, the BS 1100 may include a single transceiver 1110 that implements multiple RATs (e.g., NR and LTE). In one aspect, the transceiver 1110 may include various components, where different combinations of components may implement different RATs.

[0143] Fig.12 1000 , a sidelink communication method 1200 according to some aspects of the present disclosure. Aspects of the method 1200 may be performed by a computing device (e.g., a processor, a processing circuit, and / or other suitable components) of a wireless communication device or other suitable means for performing steps. For example, a wireless communication device (such as UE 115, 215, and / or 1000) may utilize one or more components (such as processor 1002, memory 1004, sidelink communication module 1008, transceiver 1010, modem 1012, and one or more antennas 1016) to perform the steps of the method 1200. The method 1200 may be implemented in the same manner as described above with respect to Figures 6 to 9 The method 1200 includes a plurality of steps listed, but aspects of the method 1200 may include additional steps before, after, and between the steps listed. In some aspects, one or more of the steps listed may be omitted or performed in a different order.

[0144] At block 1210, the UE receives a sidelink (SL) communication. In some aspects, the SL communication may include SL control information, SL data, a reference signal, and / or a combination thereof. For example, the SL communication may include an SCI carried in a PSCCH. In some aspects, the SL communication includes SL data carried in a PSSCH. In some aspects, block 1210 may include the UE receiving and decoding the SCI in the PSCCH and / or PSSCH, and determining the location of at least one associated PSSCH based on the SCI. In some aspects, the UE may receive the SL communication in a SL resource pool or a SL resource allocation. In some aspects, the SL resource pool may include a set of time and frequency resources. The SL resource pool may be semi-statically configured, dynamically configured, statically configured, and / or any other suitable type of resource configuration. In some aspects, the UE may receive the SL communication in a shared band or an unlicensed band. In some aspects, the UE may receive the SL communication in a channel occupancy time (COT) associated with a channel access configuration. For example, the UE may receive the SL communication from the second UE within a COT initiated by the second UE. In some aspects, the COT may be initiated by the second UE by performing a channel access procedure. The channel access procedure may correspond to a channel access type. For example, the channel access procedure may be a type 1 channel access procedure, a type 2A channel access procedure, a type 2B channel access procedure, or a type 2C channel access procedure. In some aspects, the UE may share a portion of the COT to send the PSFCH to the second UE, as further explained below. In other aspects, the UE may not share the COT.

[0145] In some aspects, the UE may receive SL communications within or during a PSFCH period. In some aspects, the PSFCH period may include or extend one or more time slots. In this regard, the UE may be configured with a PSFCH resource configuration indicating a PSFCH periodicity. The PSFCH periodicity may indicate the number of time slots. In some aspects, the PSFCH periodicity may be one time slot, two time slots, four time slots, eight time slots, and / or any other suitable number of time slots. SL communications such as PSSCH received during the PSFCH period may be associated with the PSFCH timing of the PSFCH period.

[0146] At block 1220, the UE selects a channel access configuration for a PSFCH opportunity in a shared frequency band. In some aspects, selecting a channel access configuration may include selecting or determining a channel access type. In some aspects, the UE may select a channel access type based on SL communications. For example, the UE may select a channel access type based on COT sharing information. In some aspects, COT sharing information may be provided in a SL communication received at block 1210. In other aspects, COT sharing information may be provided in different SL communications from different UEs. In some aspects, the COT sharing information may include COT sharing information associated with multiple COTs and / or multiple other UEs. In some aspects, the COT sharing information may indicate to the UE that a COT associated with a PSFCH opportunity may be shared with the UE. On the other hand, the COT sharing information may indicate to the UE that a COT associated with a PSFCH opportunity may not be shared with the UE. In some aspects, the COT sharing information may indicate to the UE that the PSFCH opportunity is not within a shared portion of the COT.

[0147] In some aspects, based on the COT not being in the shared portion of the COT, the UE may determine or select a type 1 channel access procedure. In some aspects, the type 1 channel access procedure may include a CAT4 LBT. In some aspects, block 1220 may include selecting one or more channel access parameters based on a minimum UL channel access priority category value. In this regard, UL channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 1. In this regard, the UE may select or determine one or more of a contention window size, a maximum COT length, and / or any other suitable parameters associated with a minimum UL channel access priority category value (e.g., 1) shown in Table 1. In some aspects, block 1220 may include selecting one or more channel access parameters based on a minimum DL channel access priority category value. In this regard, DL channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 2. In this regard, the UE may select or determine one or more of a contention window size, a maximum COT length, and / or any other suitable parameters associated with a minimum DL channel access priority category value (e.g., 1) shown in Table 2. In another aspect, block 1220 may include selecting one or more channel access parameters based on a minimum PSFCH channel access priority category value. In this regard, exemplary PSFCH channel access priority category values ​​and their associated parameters are provided in the Appendix, as shown in Table 3. In another aspect, the SL communication may indicate or be associated with a channel access priority category. In some aspects, block 1220 may include selecting one or more channel access parameters based on the indicated channel access priority category.

[0148] On the other hand, the UE may be scheduled to send a second SL communication immediately after the transmission of the PSFCH in the PSFCH opportunity. For example, the UE may be scheduled to send a second SL communication in a time slot after the PSFCH opportunity. The second SL communication may include a PSCCH communication, a PSSCH communication, a reference signal and / or a combination thereof. In some aspects, the second SL communication may be associated with a channel access priority category. Therefore, in some examples, the UE may select a channel access configuration based on the channel access priority category associated with the second SL communication. In some aspects, the UE may perform a type 1 channel access procedure (further described below) before sending a PSFCH communication in a PSFCH opportunity, and may continue to send a second SL communication after the PSFCH communication without performing additional channel sensing and / or without performing an additional channel access procedure for the second SL communication. In some aspects, the UE may send a second SL communication with a cyclic prefix extension to at least partially fill at least one gap symbol between the PSFCH opportunity and the start of the second SL communication. In some aspects, if the channel access priority category value associated with the PSFCH communication is equal to or less than the channel access priority category value associated with the second SL communication, the UE may send the second SL communication without performing additional channel access procedures.

[0149] On the other hand, block 1220 may include the UE selecting a channel access procedure based on a PSFCH configuration. In some aspects, method 1200 may include the UE receiving an information element, a control element, and / or any other suitable configuration including or indicating a PSFCH configuration. The PSFCH configuration may include or indicate time and / or frequency resources for a PSFCH opportunity. In some aspects, the PSFCH configuration may include or indicate at least one of a PSFCH periodicity, a total duration of PSFCH transmissions within an observation period, a number of PSFCH transmissions within an observation period, a duration of each PSFCH opportunity or communication, and / or any other suitable parameter. In some aspects, the parameters indicated above may be indicated for or associated with an SCS. For example, a PSFCH configuration with an SCS of 15kHz and a PSFCH periodicity of 1 may indicate 50 PSFCH transmissions within a 50ms observation period. A PSFCH configuration with an SCS of 30kHz and a PSFCH periodicity of 1 may indicate 100 PSFCH transmissions within a 50ms observation period. In some aspects, block 1220 may include the UE selecting a channel access configuration based on a PSFCH configuration. In some aspects, the UE may select a channel access configuration based on one or more of the above-mentioned PSFCH parameters, including the PSFCH periodicity, the total duration of PSFCH transmissions during the observation period, the number of PSFCH transmissions during the observation period, the duration of each PSFCH opportunity or communication, and / or any other suitable parameters.

[0150] In some aspects, block 1220 may include the UE selecting a channel access configuration without channel sensing based on the PSFCH configuration. For example, the UE may select a type 2C channel access configuration or a non-sensing channel access configuration based on a configured PSFCH periodicity reaching or exceeding a configured threshold. In some aspects, the UE may select a type 2C channel access configuration based on one or more short control signaling conditions, thresholds, or other parameters being satisfied. In some aspects, if the PSFCH periodicity is 4 or higher, the UE may select a type 2C channel access. On the other hand, the UE may select a type 2C channel access based on the number of PSFCH transmissions within the observation period satisfying a threshold. In other aspects, the UE may select a type 2C channel access based on the total duration of PSFCH transmissions within the observation period satisfying a threshold. For example, the UE may select a type 2C channel access for FR1 based on the number of PSFCH transmissions within the observation period being equal to or less than 50 and / or the total duration of PSFCH transmissions in the observation period being less than 2.5 ms. In another example, the UE may select a type 2C channel access for FR2 based on the total duration of PSFCH transmissions in the observation period being less than 10 ms.

[0151] In some aspects, the UE may select type 2C channel access for one or more PSFCH opportunities within the observation period based on the PSFCH configuration, but may select type 1, type 2A, or type 2B channel access for one or more other PSFCH opportunities during the observation period. For example, method 1200 may include selecting a type 2C channel access procedure for a PSFCH opportunity; and selecting a type 1 channel access procedure, a type 2A channel access procedure, or a type 2B channel access procedure for a second PSFCH opportunity different from the PSFCH opportunity. In some aspects, the UE may be configured to determine or identify a first portion of the observation period in which type 2C channel access is selected and a second portion in which a different type of channel access is selected. For example, the first portion of the observation period may be determined or identified based on the PSFCH opportunity or the communication satisfying one or more short control signaling conditions in the first portion. The UE may select type 1, type 2A, or type 2B channel access for PSFCH opportunities in the remaining second portion of the observation period. Table 4 in the Appendix shows the duration and other parameters of the observation window in FR1 for which sensing (e.g., type 2C channel access) may not be used. As shown in Table 4, the UE may select the first part or the second (last) part of the observation period for no sensing (Type 2C channel access) or for other channel access types.

[0152] On the other hand, the PSFCH configuration may indicate a partial automatic gain control (AGC) symbol for one or more PSFCH opportunities in the observation window. In some aspects, the PSFCH configuration may indicate a partial AGC symbol for each PSFCH opportunity in the observation period. In other aspects, the PSFCH configuration may indicate a partial AGC symbol only for a portion of the observation period. In some aspects, in this regard, Table 5 in the Appendix shows that if a partial AGC symbol is used for PSFCH transmission, other periodicities other than 4 may be eligible for non-sensing channel access (e.g., type 2C channel access). In this regard, if a partial AGC symbol is used, the PSFCH configuration may indicate that the UE uses a type 2C channel access for a PSFCH periodicity of 4 or 2 for SCS values ​​of 15kHz and 30kHz. On the other hand, the PSFCH configuration may indicate that the UE uses a type 2C channel access for the first portion of the observation period, and uses a different type of channel access process with sensing (e.g., type 1, type 2A) for the second portion of the observation period. In this regard, the use of partial AGC symbols may increase the duration of the portion of the observation period for which type 2C channel access may be used. In some aspects, the PSFCH configuration may instruct the UE to use 2 / 3 of the OFDM symbol for AGC with one or more PSFCH transmissions. In other aspects, the PSFCH configuration may instruct the UE to use 1 / 2 of the OFDM symbol for AGC with one or more PSFCH transmissions. The PSFCH configuration may instruct the UE to use a portion of the AGC symbols for all PSFCH opportunities during the observation period or for only a portion of the observation period.

[0153] At block 1230, the UE sends a PSFCH communication in a PSFCH opportunity in a shared frequency band based on the channel access configuration selected at block 1220 and the SL communication received at block 1210. In some aspects, the method 1200 also includes performing a channel access procedure based on the channel access configuration selected at block 1220. In some aspects, the channel access procedure may include or involve channel sensing. In other aspects, the channel access procedure may not include or involve channel sensing (e.g., type 2C channel access). In some aspects, block 1230 may include the UE sending a PSFCH communication based on a type 1 channel access parameter, the type 1 channel access parameter being selected based on at least one of a minimum UL CAPC value, a minimum DL CAPC value, or a minimum PSFCH CAPC value, as explained above.

[0154] In some aspects, method 1200 also includes the UE sending a second SL communication after sending the PSFCH communication. In some aspects, the UE may send the second SL communication after sending the PSFCH communication without performing additional channel sensing. For example, the UE may perform a type 1 channel access procedure before sending the PSFCH communication, and may send the second SL communication based on the type 1 channel access procedure performed for the PSFCH communication. In some aspects, sending the second SL communication may include sending the second SL communication with a cyclic prefix (CP) extension in at least one gap symbol between the PSFCH communication and the second SL communication. In some aspects, sending the second SL communication may be based on at least one of a first CAPC value for the PSFCH communication and a second CAPC value for the second SL communication. In some aspects, if the first CAPC value for the PSFCH communication is greater than the second CAPC value for the second SL communication, the UE may send the second SL communication without additional sensing.

[0155] In some aspects, sending a PSFCH communication may include sending the PSFCH communication using a portion of the AGC symbol before the PSFCH symbol. In some aspects, sending a PSFCH communication may include sending 2 / 3 of the AGC symbol, 1 / 2 of the AGC symbol, or any other suitable portion of the AGC symbol together with the PSFCH symbol. In other aspects, sending a PSFCH communication may include sending a full AGC symbol together with the PSFCH symbol. In some aspects, the UE may send a PSFCH communication without channel sensing based on one or more short control signaling configurations or parameters, as explained above.

[0156] Exemplary Aspects of the Disclosure

[0157] Aspect 1. A method for wireless communication performed in a shared frequency band at a user equipment (UE), the method comprising: receiving side link (SL) communication; selecting a channel access configuration for a physical side link feedback channel (PSFCH) opportunity in the shared frequency band; and sending PSFCH communication in the PSFCH opportunity in the shared frequency band based on the channel access configuration and the SL communication.

[0158] Aspect 2. A method according to Aspect 1, wherein receiving the SL communication includes receiving the SL communication from a second UE, and wherein selecting the channel access configuration includes selecting a type 1 channel access configuration for the PSFCH opportunity based on the PSFCH opportunity not being in a shared part of a channel occupancy time (COT).

[0159] Aspect 3. The method according to aspect 2, wherein selecting the channel access configuration includes selecting one or more type 1 channel access parameters based on a minimum uplink (UL) channel access priority category value.

[0160] Aspect 4. A method according to any one of Aspects 2 to 3, wherein selecting the channel access configuration comprises selecting one or more type 1 channel access parameters based on a minimum downlink (DL) channel access priority category value.

[0161] Aspect 5. A method according to any one of Aspects 2 to 4, wherein selecting the channel access configuration comprises selecting one or more type 1 channel access parameters based on a minimum PSFCH channel access priority category value.

[0162] Aspect 6. A method according to any one of Aspects 2 to 5, wherein the SL communication indicates a channel access priority category associated with the PSFCH opportunity, and wherein the channel access configuration is selected based on the indicated channel access priority category.

[0163] Aspect 7. According to any one of Aspects 2 to 6, the method further includes: sending a second SL communication associated with a channel access priority category after sending the PSFCH communication, wherein the channel access configuration is selected based on the channel access priority category.

[0164] Aspect 8. A method according to any one of Aspects 2 to 7, wherein: sending the PSFCH communication includes performing channel access sensing based on the type 1 channel access configuration and the first channel access priority category; and wherein the method further includes: after sending the PSFCH communication and based on the channel access sensing, sending a second SL communication associated with a second channel access priority category, wherein the second channel access priority category value is equal to or less than the first channel access priority category value.

[0165] Aspect 9. The method according to any one of aspects 1 to 8, wherein selecting the channel access configuration comprises selecting the channel access configuration based on a PSFCH configuration, wherein the PSFCH configuration indicates a time resource for the PSFCH opportunity.

[0166] Aspect 10. The method according to aspect 9, wherein the PSFCH configuration indicates a PSFCH opportunity periodicity, and wherein selecting the channel access configuration is based on the PSFCH periodicity.

[0167] Aspect 11. The method of aspect 10, wherein sending the PSFCH communication comprises refraining from performing channel access sensing for the PSFCH opportunity based on the PSFCH periodicity reaching or exceeding a configured threshold.

[0168] Aspect 12. A method according to any one of Aspects 10 to 11, wherein: sending the PSFCH communication includes sending the PSFCH communication in a first part of an observation window without performing channel access sensing, and the method further includes: selecting a second channel access configuration associated with a second PSFCH opportunity based on the PSFCH configuration, wherein the second PSFCH opportunity is in a second part of the observation window that is different from the first part; and sending a second PSFCH communication in the second PSFCH opportunity based on the second channel access configuration; and selecting the second channel access configuration is based on the number of PSFCH opportunities in the first part of the observation window.

[0169] Aspect 13. A method according to Aspect 12, wherein: the PSFCH configuration indicates a portion of automatic gain control (AGC) symbols used for PSFCH communication; and selecting the channel access configuration and selecting the second channel access configuration are based on the portion of AGC symbols.

[0170] Aspect 14. A user equipment (UE), comprising: a memory device; a transceiver; and a processor, the processor communicating with the memory device and the transceiver, wherein the UE is configured to perform the actions according to any one of aspects 1 to 13.

[0171] Aspect 15. A non-transitory computer-readable medium having program instructions recorded thereon, wherein the program instructions are executable by a processor of a user equipment (UE) to cause the UE to perform actions according to any one of aspects 1 to 13.

[0172] Aspect 16: A user equipment (UE), comprising means for performing the actions according to any one of aspects 1 to 13.

[0173] Information and signals may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0174] The various illustrative blocks and modules described in conjunction with the present disclosure may be implemented or executed using a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0175] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium, or sent via a computer-readable medium. Other examples and specific implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software, hardware, firmware, hardware wiring, or any combination thereof executed by a processor. The features of the implementation functions may also be physically located at different locations, including being distributed so that the various parts of the functions are implemented at different physical locations. In addition, as used herein (including in the claims), "or" as used in a list of items (e.g., "or" used in a list of items ending with "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of [at least one of A, B, or C] means: A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0176] As those skilled in the art will understand by now and depending on the specific application at hand, many modifications, substitutions and changes may be made to the materials, devices, configurations and methods of use of the apparatus of the present disclosure without departing from the spirit and scope of the present disclosure. In view of this, the scope of the present disclosure should not be limited to the specific aspects illustrated and described herein (as they are only some examples of the present disclosure), but should be fully equivalent to the attached claims and their functional equivalents.

[0177] appendix

[0178]

[0179] Table 1. CAPC values ​​and associated channel access parameters for UL

[0180]

[0181] Table 2. CAPC values ​​and associated channel access parameters for DL

[0182]

[0183] Table 3. CAPC values ​​and associated channel access parameters for PSFCH

[0184]

[0185]

Claims

1. A method of wireless communication performed at a user equipment (UE) in a shared frequency band, the method comprising: Receive side link (SL) communication; Channel access configuration for Physical Sidelink Feedback Channel (PSFCH) opportunity selection in a shared frequency band; as well as PSFCH communications are sent in the PSFCH opportunities in the shared frequency band based on the channel access configuration and the SL communications.

2. The method of claim 1, wherein receiving the SL communication comprises receiving the SL communication from a second UE, and wherein selecting the channel access configuration comprises selecting a type 1 channel access configuration for the PSFCH opportunity based on the PSFCH opportunity not being in a shared portion of a channel occupancy time (COT).

3. The method of claim 2, wherein selecting the channel access configuration comprises selecting one or more type 1 channel access parameters based on a minimum uplink (UL) channel access priority category value.

4. The method of claim 2, wherein selecting the channel access configuration comprises selecting one or more type 1 channel access parameters based on a minimum downlink (DL) channel access priority category value.

5. The method of claim 2, wherein selecting the channel access configuration comprises selecting one or more Type 1 channel access parameters based on a minimum PSFCH channel access priority category value.

6. The method of claim 2, wherein the SL communication indicates a channel access priority category associated with the PSFCH opportunity, and wherein selecting the channel access configuration is based on the indicated channel access priority category.

7. The method according to claim 2, further comprising: sending a second SL communication associated with a channel access priority class after sending the PSFCH communication, Wherein selecting the channel access configuration is based on the channel access priority category.

8. The method according to claim 2, wherein: Transmitting the PSFCH communication comprises performing channel access sensing based on the type 1 channel access configuration and the first channel access priority category; and The method further comprises: A second SL communication associated with a second channel access priority category is sent after sending the PSFCH communication and based on the channel access sensing, wherein the second channel access priority category value is equal to or less than the first channel access priority category value.

9. The method of claim 1, wherein selecting the channel access configuration comprises selecting the channel access configuration based on a PSFCH configuration, wherein the PSFCH configuration indicates a time resource for the PSFCH opportunity.

10. The method of claim 9, wherein the PSFCH configuration indicates a PSFCH opportunity periodicity, and wherein selecting the channel access configuration is based on the PSFCH periodicity.

11. The method of claim 10, wherein sending the PSFCH communication comprises refraining from performing channel access sensing for the PSFCH opportunity based on the PSFCH periodicity being at or above a configured threshold.

12. The method according to claim 10, wherein: sending the PSFCH communication comprises sending the PSFCH communication in a first portion of an observation window without performing channel access sensing, The method further comprises: selecting a second channel access configuration associated with a second PSFCH opportunity based on the PSFCH configuration, wherein the second PSFCH opportunity is in a second portion of the observation window different from the first portion; and sending a second PSFCH communication in the second PSFCH opportunity based on the second channel access configuration; and Selecting the second channel access configuration is based on a number of PSFCH opportunities in the first portion of the observation window.

13. The method according to claim 12, wherein: The PSFCH configuration indicates a portion of automatic gain control (AGC) symbols used for PSFCH communications; and Selecting the channel access configuration and selecting the second channel access configuration are based on the partial AGC symbols.

14. The method of claim 10, wherein: The PSFCH configuration indicates a portion of automatic gain control (AGC) symbols used for PSFCH communications; and Selecting the channel access configuration is based on the portion of AGC symbols.

15. A user equipment (UE), the user equipment (UE) comprising: Memory devices; Transceiver; and a processor in communication with the memory device and the transceiver, wherein the UE is configured to: Receive side link (SL) communication; selecting a channel access configuration for a physical sidelink feedback channel (PSFCH) opportunity in a shared frequency band; and PSFCH communications are sent in the PSFCH opportunities in the shared frequency band based on the channel access configuration and the SL communications.

16. A UE according to claim 15, wherein the UE is configured to receive the SL communication from a second UE, and wherein the UE configured to select the channel access configuration includes the UE configured to select a type 1 channel access configuration for the PSFCH opportunity based on the PSFCH opportunity not being in a shared part of a channel occupancy time (COT).

17. The UE of claim 16, wherein the UE configured to select the channel access configuration comprises the UE configured to select one or more type 1 channel access parameters based on a minimum uplink (UL) channel access priority category value.

18. The UE of claim 16, wherein the UE configured to select the channel access configuration comprises the UE configured to select one or more type 1 channel access parameters based on a minimum downlink (DL) channel access priority category value.

19. The UE of claim 16, wherein the UE configured to select the channel access configuration comprises the UE configured to select one or more Type 1 channel access parameters based on a minimum PSFCH channel access priority category value.

20. The UE of claim 16, wherein the SL communication indicates a channel access priority category associated with the PSFCH opportunity, and wherein the UE is configured to select the channel access configuration based on the indicated channel access priority category.

21. The UE according to claim 16, wherein the UE is further configured to: sending a second SL communication associated with a channel access priority class after sending the PSFCH communication, The UE is configured to select the channel access configuration based on the channel access priority category.

22. The UE according to claim 16, wherein: The UE configured to send the PSFCH communication includes the UE configured to perform channel access sensing based on the type 1 channel access configuration and a first channel access priority category; and The UE is further configured as follows: A second SL communication associated with a second channel access priority category is sent after sending the PSFCH communication and based on the channel access sensing, wherein the second channel access priority category value is equal to or less than the first channel access priority category value.

23. The UE of claim 15, wherein the UE configured to select the channel access configuration comprises the UE configured to select the channel access configuration based on a PSFCH configuration, wherein the PSFCH configuration indicates a time resource for the PSFCH opportunity.

24. The UE of claim 23, wherein the PSFCH configuration indicates a PSFCH opportunity periodicity, and wherein the UE is configured to select the channel access configuration based on the PSFCH periodicity.

25. The UE of claim 24, wherein the UE configured to send the PSFCH communication comprises the UE configured to refrain from performing channel access sensing for the PSFCH opportunity based on the PSFCH periodicity reaching or exceeding a configured threshold.

26. The UE according to claim 24, wherein: The UE is configured to transmit the PSFCH in a first part of an observation window without performing channel access sensing, The UE is further configured to: selecting a second channel access configuration associated with a second PSFCH opportunity based on the PSFCH configuration, wherein the second PSFCH opportunity is in a second portion of the observation window different from the first portion; and sending a second PSFCH communication in the second PSFCH opportunity based on the second channel access configuration; and The UE is configured to select the second channel access configuration based on a number of PSFCH opportunities in the first portion of the observation window.

27. The UE according to claim 26, wherein: The PSFCH configuration indicates a portion of automatic gain control (AGC) symbols used for PSFCH communications; and The UE is configured to select the channel access configuration and the second channel access configuration based on the partial AGC symbols.

28. The UE according to claim 24, wherein: The PSFCH configuration indicates a portion of automatic gain control (AGC) symbols used for PSFCH communications; and The UE is configured to select the channel access configuration based on the partial AGC symbols.

29. A non-transitory computer readable medium having program code recorded thereon, wherein the program code comprises instructions executable by a processor of a user equipment (UE) to cause the UE to: Receive side link (SL) communication; selecting a channel access configuration for a physical sidelink feedback channel (PSFCH) opportunity in a shared frequency band; and PSFCH communications are sent in the PSFCH opportunities in the shared frequency band based on the channel access configuration and the SL communications.

30. A user equipment (UE), the user equipment (UE) comprising: means for receiving side link (SL) communications; means for selecting a channel access configuration for a physical sidelink feedback channel (PSFCH) opportunity in a shared frequency band; and Means for sending PSFCH communications in the PSFCH opportunities in the shared frequency band based on the channel access configuration and the SL communications.

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