Support for multiple feedback occasions in sidelink

Abstract

Methods, systems, and devices for wireless communication are described. A first UE may receive an indication of a capability of a second UE to monitor multiple feedback transmission occasions for a feedback message associated with a sidelink message. The first UE may monitor a bandwidth as part of a first channel access procedure associated with a first feedback transmission occasion of a set of feedback transmission occasions. In some examples, the first UE may monitor the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions based on the capability of the second UE and the first channel access procedure being unsuccessful. The first UE may transmit a feedback message via a second feedback transmission occasion based on the second channel access procedure being successful.

Description

SUPPORT FOR MULTIPLE FEEDBACK OCCASIONS IN SIDELINKCROSS REFERENCE

[0001] The present Application for Patent claims priority to Greek Patent Application No. 20230100670 by SARKIS et al., entitled “SUPPORT FOR MULTIPLE FEEDBACK OCCASIONS IN SIDELINK” and filed August 10, 2023, which is assigned to the assignee hereof and expressly incorporated by reference in its entirety herein.FIELD OF TECHNOLOGY

[0002] The following relates to wireless communication, including support for multiple feedback occasions for sidelink communications.BACKGROUND

[0003] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g.. time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM).

[0004] A wireless multiple-access communications system may include one or more base stations, each supporting wireless communication for communication devices, which may be known as user equipment (UE). In some examples, a UE may communicate directly with one or more other UEs via sidelink communications.SUMMARY

[0005] The described techniques relate to improved methods, systems, devices, and apparatuses that support multiple feedback occasions for sidelink communications. For example, the described techniques provide for a user equipment (UE) to receive an indication that another UE has a capability to monitor multiple feedback transmission occasions for a feedback message (e.g., a positive or negative acknowledgement) associated with a sidelink message. Thus, the UE may be able to transmit the feedback message to the other UE via a second or other subsequent feedback transmission occasion, including if the UE is unable to transmit the feedback message via a first or other earlier feedback transmission occasion — e.g., due to a first channel access procedure, such as a listen-before-talk (LET) procedure being unsuccessful for the first feedback transmission occasion but a second channel access procedure being successful for the second first feedback transmission occasion.

[0006] For example, a first UE may receive an indication that a second UE has a capability to monitor multiple feedback transmission occasions for a feedback message associated with a sidelink message. The first UE may monitor a bandwidth as part of a first channel access procedure associated with a first feedback transmission occasion of a set of feedback transmission occasion. In some examples, the first UE may monitor the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions based on the capability of the second UE and the first channel access procedure being unsuccessful. The first UE may transmit a feedback message via a second feedback transmission occasion based on the second channel access procedure being successful. Accordingly, the first UE and the second UE may support communicating feedback messages corresponding to a sidelink message on multiple feedback transmission occasions based on the capability of the second UE.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows an example of a wireless communications system that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0008] FIGs. 2A and 2B shows examples of wireless communications systems that support multiple feedback occasions in sidelink in accordance with one or more aspects of the present disclosure.

[0009] FIG. 3 shows an example of a diagram that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0010] FIG. 4 shows an example of a process flow that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0011] FIGs. 5 and 6 show block diagrams of devices that support multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0012] FIG. 7 shows a block diagram of a communications manager that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0013] FIG. 8 shows a diagram of a system including a device that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure.

[0014] FIGs. 9 through 12 show flowcharts illustrating methods that support multiple feedback occasions in accordance with one or more aspects of the present disclosure.DETAILED DESCRIPTION

[0015] Some wireless communications systems may support sidelink communications between user equipments (UEs), which may be operating in an unlicensed spectrum. For example, the UEs may perform a channel access procedure prior to performing a transmission to determine if the unlicensed spectrum is clear for transmission. In some examples, a first UE may transmit a feedback transmission to a second UE following a data transmission by the second UE. In some cases, the data transmission may be associated with a single feedback transmission occasion. In these cases, if a channel access procedure for the feedback transmission by the first UE fails, the first UE may not transmit the feedback, transmission during the single feedback transmission occasion. In cases where the first UE was to indicate a positive acknowledgment, this may cause a retransmissions of a message already received by thefirst UE, which may increase system congestion. Alternatively, if the first UE was to indicate a negative acknowledgment, the second UE may not perform a retransmission due to not receiving the feedback message indicating the negative acknowledgment, causing the first UE to miss the data transmission.

[0016] To avoid missed feedback transmissions due to failed channel access procedures, multiple feedback transmission occasions may be configured in accordance with the techniques described herein. Further, because multiple feedback transmissions may place an increased burden on the second UE, as the second UE may be configured to perform monitoring on the multiple feedback transmission occasions, techniques enabling the second UE to indicate support of reception of feedback messages on multiple feedback transmission occasions may also be used in accordance with the techniques described herein.

[0017] In accordance with examples as described herein, the second UE may be configured to transmit an indication of a capability to receive feedback transmissions on multiple feedback transmission occasions. For example, the second UE may include an indication of a capability to support reception of feedback transmissions on multiple feedback transmission occasions as a field in sidelink control information (SCI) (e.g., of a sidelink data message or a sidelink control message) or in a medium access control (MAC) header of a message. In some examples, the indication of the capability may be or include one or more bits that indicate a quantity of supported feedback transmission occasions. As such, the first UE may attempt transmissions of feedback messages up to the quantity of supported feedback transmission occasions, or until a feedback message is transmitted successfully. Additionally, or alternatively, the indication of the capability may be or include a bitmap that indicates which feedback transmission occasions are supported of a set of feedback transmission occasions.

[0018] Accordingly, by implementing the techniques described herein, a first UE may transmit a feedback message on one or more of multiple feedback transmission occasions in accordance with a capability of a second UE, which may reduce a quantity of missed feedback messages by the first UE. As such, the techniques described herein may result in one or more of the following advantages. In some examples, network congestion may be reduced by reducing the quantity of retransmissions transmitted by the second UE due to a missed feedback message by the first UE. Further, the quantityof missed sidelink data messages by the first UE may be reduced. Additionally, or alternatively, the techniques described herein may support capability indications by the second UE without requiring a unicast connection between the first UE and the second UE, which may increase flexibility and allow for multiple feedback transmission occasions to be implemented for unicast communications and for other communication types.

[0019] Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are additionally described in the context of diagrams and process flows. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to support for multiple feedback occasions in sidelink communications.

[0020] FIG. 1 shows an example of a wireless communications system 100 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The wireless communications system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE- A Pro network, a New Radio (NR) network, or a network operating in accordance with other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

[0021] The network entities 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may include devices in different forms or having different capabilities. In various examples, a network entity 105 may be referred to as a network element, a mobility element, a radio access network (RAN) node, or network equipment, among other nomenclature. In some examples, network entities 105 and UEs 115 may wirelessly communicate via one or more communication links 125 (e.g., a radio frequency (RF) access link). For example, a network entity 105 may support a coverage area 110 (e.g.. a geographic coverage area) over which the UEs 115 and the network entity 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a network entity 105 and a UE 115 may support the communication of signals according to one or more radio access technologies (RATs).

[0022] The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of supporting communications with various types of devices, such as other UEs 115 or network entities 105, as shown in FIG. 1.

[0023] As described herein, a node of the wireless communications system 100, which may be referred to as a network node, or a wireless node, may be a network entity 105 (e.g., any network entity described herein), a UE 115 (e.g., any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, a node may be a UE 115. As another example, a node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In yet other aspects of this example, the first, second, and third nodes may be different relative to these examples. Similarly, reference to a UE 115, network entity 105, apparatus, device, computing system, or the like may include disclosure of the UE 115, network entity 105, apparatus, device, computing system, or the like being anode. For example, disclosure that a UE 115 is configured to receive information from a network entity 105 also discloses that a first node is configured to receive information from a second node.

[0024] In some examples, network entities 105 may communicate with the core network 130, or with one another, or both. For example, network entities 105 may communicate with the core network 130 via one or more backhaul communication links120 (e.g., in accordance with an S1, N2, N3, or other interface protocol). In some examples, network entities 105 may communicate with one another via a backhaul communication link 120 (e.g., in accordance with an X2, Xn, or other interface protocol) either directly (e.g., directly between network entities 105) or indirectly (e.g., via a core network 130). In some examples, network entities 105 may communicatewith one another via a midhaul communication link 162 (e.g., in accordance with a midhaul interface protocol) or a fronthaul communication link 168 (e.g., in accordance with a fronthaul interface protocol), or any combination thereof. The backhaul communication links 120, midhaul communication links 162, or fronthaul communication links 168 may be or include one or more wired links (e.g., an electrical link, an optical fiber link), one or more wireless links (e.g., a radio link, a wireless optical link), among other examples or various combinations thereof. A UE 115 may communicate with the core network 130 via a communication link 155.

[0025] One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., a base transceiver station, a radio base station, an NR base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB), a 5G NB, a next-generation eNB (ng-eNB), a Home NodeB, a Home eNodeB, or other suitable terminology). In some examples, a network entity 105 (e.g., a base station 140) may be implemented in an aggregated (e.g., monolithic, standalone) base station architecture, which may be configured to utilize a protocol stack that is physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as a base station 140).

[0026] In some examples, a network entity 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture), which may be configured to utilize a protocol stack that is physically or logically distributed among two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN)). For example, a network entity 105 may include one or more of a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN Intelligent Controller (RIC) 175 (e.g., a Near-Real Time RIC (Near-RT RIC), a Non-Real Time RIC (Non-RT RIC)), a Service Management and Orchestration (SMO) 180 system, or any combination thereof. An RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmission reception point (TRP). One or more components of the network entities 105 in a disaggregated RAN architecture may be co-located, or one or morecomponents of the network entities 105 may be located in distributed locations (e.g., separate physical locations). In some examples, one or more network entities 105 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU), a virtual DU (VDU), a virtual RU (VRU)).

[0027] The split of functionality between a CU 160, a DU 165, and an RU 170 is flexible and may support different functionalities depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combinations thereof) are performed at a CU 160, a DU 165, or an RU 170. For example, a functional split of a protocol stack may be employed between a CU 160 and a DU 165 such that the CU 160 may support one or more layers of the protocol stack and the DU 165 may support one or more different layers of the protocol stack. In some examples, the CU 160 may host upper protocol layer (e.g., layer 3 (L3), layer 2 (L2)) functionality and signaling (e.g., Radio Resource Control (RRC), service data adaption protocol (SDAP), Packet Data Convergence Protocol (PDCP)). The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, MAC layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU 165 and an RU 170 such that the DU 165 may support one or more layers of tire protocol stack and the RU 170 may support one or more different layers of the protocol stack. The DU 165 may support one or multiple different cells (e.g., via one or more RUs 170). In some cases, a functional split between a CU 160 and a DU 165, or between a DU 165 and an RU 170 may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU 160, a DU 165, or an RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, the DU 165, or the RU 170). A CU 160 may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU 160 may be connected to one or more DUs 165 via amidhaul communication link 162 (e.g., F1, F1-c, F1-u), and a DU 165 may be connected to one or more RUs 170 via a fronthaul communication link 168 (e.g., open fronthaul (FH) interface). In some examples, a midhaul communication link 162 or a fronthaul communication link 168 may be implemented in accordance with an interface(e.g., a channel) between layers of a protocol stack supported by respective network entities 105 that are in communication via such communication links.

[0028] In wireless communications systems (e.g., wireless communications system 100), infrastructure and spectral resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, providing an IAB network architecture (e g., to a core network 130). In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as a donor entity or an IAB donor. One or more DUs 165 or one or more RUs 170 may be partially controlled by one or more CUs 160 associated with a donor network entity 105 (e.g., a donor base station 140). The one or more donor network entities 105 (e.g., IAB donors) may be in communication with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access and backhaul links (e.g., backhaul communication links 120). IAB nodes 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by DUs 165 of a coupled IAB donor. An IAB-MT may include an independent set of antennas for relay of communications with UEs 115, or may share the same antennas (e.g., of an RU 170) of an IAB node 104 used for access via the DU 165 of the IAB node 104 (e.g., referred to as virtual IAB-MT (vIAB-MT)). In some examples, the IAB nodes 104 may include DUs 165 that support communication links with additional entities (e.g., IAB nodes 104, UEs 115) within the relay chain or configuration of the access network (e.g., downstream). In such cases, one or more components of the disaggregated RAN architecture (e.g., one or more IAB nodes 104 or components of IAB nodes 104) may be configured to operate according to the techniques described herein.

[0029] In the case of the techniques described herein applied in the context of a disaggregated RAN architecture, one or more components of the disaggregated RAN architecture may be configured to support multiple feedback occasions as described herein. For example, some operations described as being performed by a UE 115 or a network entity 105 (e.g., a base station 140) may additionally, or alternatively, be performed by one or more components of the disaggregated RAN architecture (e.g., IAB nodes 104, DUs 165, CUs 160, RUs 170, RIC 175, SMO 180).

[0030] A UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (lol) device, an Internet of Everything (loE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

[0031] The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the network entities 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in FIG. 1.

[0032] The UEs 115 and the network entities 105 may wirelessly communicate with one another via one or more communication links 125 (e.g., an access link) using resources associated with one or more carriers. The term “carrier” may refer to a set of RF spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a RF spectrum band (e.g., a bandwidth part (BWP)) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers. Communication between a network entity 105 and other devices may refer to communication between the devices and any portion (e.g., entity, sub-entity) of a network entity 105. For example, the terms “transmitting,” “receiving,” or “communicating,” when referring to a network entity 105, may refer to any portion of a network entity 105 (e.g., a base station 140, a CU 160, a DU 165, a RU 170) of a RAN communicating with another device (e.g., directly or via one or more other network entities 105).

[0033] Signal waveforms transmitted via a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may refer to resources of one symbol period (e.g„ a duration of one modulation symbol) and one subcarrier, in which case the symbol period and subcarrier spacing may be inversely related. The quantity of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both), such that a relatively higher quantity of resource elements (e.g., in a transmission duration) and a relatively higher order of a modulation scheme may correspond to a relatively higher rate of communication. A wireless communications resource may refer to a combination of an RF spectrum resource, a time resource, and a spatial resource (e.g., a spatial layer, a beam), and the use of multiple spatial resources may increase the data rate or data integrity for communications with a UE 115.

[0034] The time intervals for the network entities 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of Ts= 1 / (Δfmax· Nf) seconds, for which Δfmaxmay represent a supported subcarrier spacing, and Nfmay represent a supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0035] Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a quantity of slots. Alternatively, each frame may include a variablequantity of slots, and the quantity of slots may depend on subcarrier spacing. Each slot may include a quantity of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). In some wireless communications systems 100, a slot may further be divided into multiple mini-slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (e.g., Nf) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

[0036] A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the lime domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., a quantity of symbol periods in a TTI) may be variable. Additionally, or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0037] Physical channels may be multiplexed for communication using a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed for signaling via a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a set of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) may be configured for a set of the UEs 115. For example, one or more of the UEs 115 may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to an amount of control channel resources (e.g., control channel elements (CCEs)) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets for sending control information to a specific UE 115.

[0038] In some examples, a network entity 105 (e.g. , a base station 140, an RU 170) may be movable and therefore provide communication coverage for a moving coverage area 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, the overlapping coverage areas 110 associated with different technologies may be supported by different network entities 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

[0039] The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC). The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communications may include private communication or group communication and may be supported by one or more services such as push-to-talk, video, or data. Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably herein.

[0040] In some examples, a UE 115 may be configured to support communicating directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., in accordance with a peer-to-peer (P2P), D2D, or sidelink protocol). In some examples, one or more UEs 115 of a group that are performing D2D communications may be within the coverage area 110 of a network entity 105 (e.g., a base station 140, an RU 170), which may support aspects of such D2D communications being configured by (e.g., scheduled by) the network entity 105. In some examples, one or more UEs 115 of such a group may be outside the coverage area 110 of a network entity 105 or may be otherwise unable to or not configured to receive transmissions from a network entity 105. In some examples, groups of the UEs 115 communicating via D2D communications may support a one-to-many (1:M) system in which each UE 115transmits to each of the other UEs 115 in the group. Tn some examples, a network entity 105 may facilitate the scheduling of resources for D2D communications. In some other examples, D2D communications may be carried out between the UEs 115 without an involvement of a network entity 105.

[0041] In some systems, a D2D communication link 135 may be an example of a communication channel, such as a sidelink, communication channel, between vehicles (e.g., UEs 115). In some examples, vehicles may communicate using vehicle-to- everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., network entities 105, base stations 140, RUs 170) using vehicle-to- network (V2N) communications, or with both.

[0042] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or 5G core (5GC), which may include at least one control plane entity that manages access and mobility (e.g„ a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the network entities 105 (e.g., base stations 140) associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or a Packet-Switched Streaming Service.

[0043] The wireless communications system 100 may operate using one or more frequency bands, which may be in the range of 300 megahertz (MHz) to 300 gigahertz(GHz). Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, which may be referred to as clusters, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to communications using the smaller frequencies and longer waves of the high frequency (HF) or veiy high frequency (VHF) portion of the spectrum below 300 MHz.

[0044] The wireless communications system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology using an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. While operating using unlicensed RF spectrum bands, devices such as the net-work entities 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations using unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating using a licensed band (e.g., LAA). Operations using unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0045] A network entity 105 (e.g., a base station 140, an RU 170) or a UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a network entity 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a network entity 105 may be located at diverse geographic locations. A network entity 105 may include an antenna array with a set of rows and columns of antenna ports that the network entity 105 may use to support beamforming of communications with a UE 115.Likewise, a UE 115 may include one or more antenna arrays that may support various MIMO or beamforming operations. Additionally, or alternatively, an antenna panel may support RF beamforming for a signal transmitted via an antenna port.

[0046] Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a network entity 105, a UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that some signals propagating along particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude offsets, phase offsets, or both to signals carried via the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation).

[0047] The UEs 115 and the network entities 105 may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly via a communication link (e.g., a communication link 125, a D2D communication link 135). HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, in which case the device may provide HARQ feedback in a specific slot for data received via a previous symbol in the slot. In some other examples, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

[0048] In some examples, UEs 115 may also support transmission of feedback messages and retransmissions while communicating with other UEs 115 in sidelinkcommunications. In some cases, a UE 115 may be configured to transmit a feedback message, for example, on a physical sidelink feedback channel (PSFCH). For example, the UE 115 may transmit a PSFCH message that indicates feedback associated with a data transmission, such as a physical sidelink shared channel (PSSCH) message. In some examples, the PSFCH message may be or include a positive acknowledgment (e.g., an ACK), which may indicate a receiving UE 115 that a corresponding PSSCH message was successfully received. As such, the receiving UE 115 may refrain from performing a retransmission of the PSSCH. In some other examples, the PSFCH message may be or include a negative acknowledgment (e.g., a NACK), which may indicate the receiving UE 115 to perform a retransmission of the corresponding PSSCH message.

[0049] In some examples, there may be a mapping between a data transmission on a PSSCH and feedback resources on a PSFCH. For instance, one or more occasions for a PSSCH message may be associated with one or more occasions for a corresponding PSFCH transmission. In some cases, PSFCH occasions may repeat periodically (e.g., with a periodicity configured or preconfigured to the UE 115), such as every 1 slot, every 2 slots, every 4 slots, or a different quantity of slots. In some cases, PSFCH occasions may be disabled (e.g., configured or preconfigured as disabled to the UE 115, indicated as disabled by a network entity), and these occasions may be used for transmission of data messages (e.g., PSSCH messages).

[0050] In some examples, a UE 115 may operate in an unlicensed spectrum In these examples, the UE 115 may perform a channel access procedure, such as a listen- before-talk procedure, prior to performing a transmission in the unlicensed spectrum. For example, the UE 115 may monitor for transmissions by other UEs 115 and may perform the transmission if the UE 115 determines that the unlicensed channel is clear and the channel access procedure is successful (e.g., measurements by the UE 115 are below a threshold value). In some cases, if the channel access procedure is unsuccessful (e.g., measurements by the UE 115 are above a threshold value), the UE 115 may not perform the transmission, and the UE 115 may perform another channel access procedure (e.g., at a later time).

[0051] In some examples, for sidelink communications in an unlicensed spectrum, the UE 115 may be configured with multiple channel access types. For example, the UE115 may be configured with a Type I channel access procedure, which may be associated with a random contention window. The UE 115 may also be configured with a Type 2A channel access procedure, which may apply when transmissions by the UE 115 follow transmissions by another UE 115 with a gap period greater than a first threshold duration (e.g., 25 microseconds) in a shared channel occupancy. Additionally, or alternatively, the UE 115 may be configured with a Type 2B channel access procedures, which may apply when transmissions by the UE 115 follow transmissions by another UE 115 with a gap period greater than a second threshold duration (e.g., 16 microseconds), and a Type 2C channel access procedure, which may apply when transmissions by the UE 115 follow transmissions by another UE 115 with a gap period less than the second threshold duration in the shared channel occupancy and if a duration of the transmission by the UE 115 is no greater than a third threshold duration (e.g., 584 microseconds).

[0052] In some cases, a single PSFCH transmission occasion may be associated with a corresponding PSSCH. In these cases, if a channel access procedure for the PSFCH transmission by a UE 115 operating in an unlicensed spectrum fails, the UE 115 may not transmit the PSFCH transmission during the single PSFCH transmission occasion. In some cases, if the UE 115 was to indicate a positive acknowledgment (e.g., an ACK) in the PSFCH transmission, the failed PSFCH transmission may cause a retransmissions of the PSSCH message already received by the UE 115, which may increase system congestion. Alternatively, if the UE 115 was to indicate a negative acknowledgment (e.g., aNACK) in the PSFCH transmission, a UE 115 that was monitoring for the failed feedback message may not perform a retransmission, which may cause the UE 115 to miss the PSSCH message. For example, the UE 115 may be operating in a NACK-only scenario, where the UE 115 transmits a NACK on a PSFCH message if the UE 115 does not receive the PSSCH message to trigger a retransmission.

[0053] To avoid missed PSFCH transmissions, multiple PSFCH transmission occasions may be configured. As such, a transmitting UE 115 may perform additional channel access procedures to attempt transmission of the PSFCH message. However, the multiple PSFCH transmissions may place a burden on a receiving UE 115, as the receiving UE 115 may be configured to perform monitoring for PSFCH messages on the multiple PSFCH transmission occasions. As such, techniques for the receiving UE115 to indicate support of reception of PSFCH on multiple PSFCH transmission occasions may be desired.

[0054] In some examples, the receiving UE 115 may be configured to report capability signaling to a network entity or to the transmitting UE 115 via sidelink communications. To report capability signaling to the transmitting UE 115, the receiving UE 115 may be configured to send an RRC message (e.g., a PC5-RRC message), which may be transmitted if the two UEs 115 are communicating using a unicast connection. As such, the receiving UE 115 may be configured to transmit a capability to support reception of PSFCH on multiple PSFCH transmission occasions to the transmitting UE 115 on an RRC message (e.g., a PC5-RRC message). In some cases, however, capability signaling on an RRC message may be limited to unicast connections. Accordingly, techniques for the receiving UE 115 to indicate support reception of PSFCH on multiple PSFCH transmission occasions to the transmitting UE 115 when operating without a unicast connection may be desired.

[0055] In accordance with examples as described herein, a first UE 115 may be configured to receive an indication of a capability of a second UE 115 associated with monitoring a set of feedback transmission occasions for a feedback message associated with a sidelink message. For example, the second UE 115 may include an indication of a capability to support reception of feedback transmissions on multiple feedback transmission occasions as a field in SCI included within a sidelink data message or a sidelink control message. Additionally, or alternatively, an indication of the capability may be included in a MAC header of a message. In some examples, the indication of the capability may be or include one or more bits that indicate a quantity of supported feedback transmission occasions. As such, the first UE 115 may attempt transmissions of feedback messages up to the quantity of supported feedback transmission occasions, or until a feedback message is transmitted successfully. Additionally, or alternatively, the indication of the capability may be or include a bitmap that indicates which feedback transmission occasions are supported of a set of configured feedback transmission occasions. Accordingly, the first UE 115 and the second UE 115 may support communication of feedback messages on multiple feedback transmission occasions in accordance with the capability of the second UE 115.

[0056] FIGs. 2A and 2B show examples of a wireless communications system 200-a and a wireless communications system 200-b that support multiple feedback occasions in accordance with one or more aspects of the present disclosure. The wireless communications system 200-a and the wireless communications system 200-b may implement or be implemented by the wireless communications system 100. For example, the wireless communications system 200-a and the wireless communications system 200-b illustrate communications between a UE 115-a and a UE 115-b, which may be examples of UEs 115 as described herein with reference to FIG. 1.

[0057] In some examples, the UE 115-b may transmit a control message 210 to the UE 115-a. For example, the control message 210 (e.g., a PSCCH message) may be transmitted via a PSCCH occasion, and the control message 210 may include control information, such as 1st-stage SCI (e.g., SCI-1) associated with a data message 215 to be transmitted by the UE 115-b. The UE 115-b may then transmit the data message 215 (e.g., a PSSCH message) via a PSSCH occasion to the UE 115-a. In some examples, the UE 115-a may be configured to provide feedback associated with the data message 215. For example, the UE 115-a may transmit a positive acknowledgment (e.g., an ACK) if the UE 115-a received the data message 215. Alternatively, the UE 115-a may transmit a negative acknowledgment (e.g., a NACK) if the UE 115-a did not receive the data message 215 during a corresponding PSSCH occasion (e.g., a PSSCH occasion indicated by the control message 210).

[0058] In some examples, the UE 115-a (e.g., and the UE 115-b) may be operating on a bandwidth of an unlicensed spectrum. In these examples, the UE 115-a may perform a channel access procedure (e.g., a listen-before-talk procedure), prior to performing a transmission in the bandwidth unlicensed spectrum. For example, the UE 115-a may monitor for transmissions by other UEs 115 and may perform the transmission if the UE 115 determines that the unlicensed channel is clear and the channel access procedure is successful (e.g.. a value associated with measurements by the UE 115-a are below a threshold value). In some cases, if the channel access procedure is unsuccessful (e.g., a value associated with measurements by the UE 115-a are above a threshold value), the UE 115-a may not perform the transmission, and the UE 115-a may perform another channel access procedure (e.g., at a later time).

[0059] In some cases, the UE 115-a may be configured with a single feedback transmission occasion for transmission of the feedback message 220. In these cases, if a channel access procedure associated with the feedback message 220 is unsuccessful, the UE 115-a may refrain from transmitting the feedback message 220, as there may not be other feedback transmission occasions for the UE 115-a to attempt transmission of the feedback message 220. In cases where the UE 115-a was to indicate a positive acknowledgment in the feedback message 220, the UE 115-b may retransmit the data message 215, even if the UE 115-a had previously received the data message successfully. Alternatively, if the UE 115-a was to indicate a negative acknowledgment in the feedback message 220, the UE 115-b may not perform a retransmission due to not receiving the feedback message 220, which may cause the UE 115-a to not receive the data message 215 at all.

[0060] To avoid failed transmissions of the feedback message 220 due to failed channel access procedures, the UE 115-a and the UE 115-b may be configured with multiple feedback transmission occasions. However, the UE 115-b may not always be capable of receiving feedback messages 220 on the multiple feedback, transmission occasions. For example, the UE 115-b may not be able to monitor for feedback messages 220 on multiple feedback transmission occasions per data message 215 due to power constraints, monitoring capabilities of the UE 115-b, or other reasons. As such, techniques that may allow the UE 115-b to indicate a capability to support reception of feedback messages 220 on multiple feedback transmission occasions per data message 215 may be desired.

[0061] In accordance with examples as described herein, the UE 115-b may transmit a message containing a capability indication 205. The capability indication 205 may indicate a capability of the UE 115-b to support reception of feedback messages 220 on multiple feedback transmission occasions per data message 215. The wireless communication system 200-a in FIG. 2A illustrates an example in which the capability indication 205 is transmitted (e.g., as a field) within the control message 210. For example, the control message 210 may include one or more reserved bits within 1st- stage SCI (e.g., SCI-1) included in the control message 210, and the reserved bits may be used for the capability indication 205.

[0062] The wireless communication system 200-b in FIG. 2B illustrates an example in which the capability indication 205 is transmitted within the data message 215. For example, the capability indication 205 may be included as a field within 2nd-stage SCI (e.g., SCI-2) within the data message 215. For example, the 2nd-stage SCI may include a dedicated portion (e.g., one or more bits) for the capability indication 205. Additionally, or alternatively, the capability indication 205 may be included as a field in a MAC header (e.g., a MAC subheader) of the data message 215. In some cases, the capability indication 205 may be induded within a field in a MAC-control element (MAC-CE), such as a MAC-CE element. In some examples, the capability indication 205 may be multiplexed with data of the data message 215. For example, a MAC-CE element including the capability indication may be multiplexed with data of the data message 215.

[0063] In some examples, the capability indication 205 may be or indude a single bit. For example, a first value of the bit (e.g., a value of one) may indicate that the UE 115-b supports reception of feedback messages 220 on multiple feedback transmission occasions (e.g., PSFCH occasions) per data message 215, while a second value of the bit (e.g., a value of zero) may indicate that the UE 115-b does not support reception of the feedback messages 220 on multiple feedback transmission occasions per data message 215. As such, the UE 115-a may attempt transmission of the feedback message 220 on multiple feedback transmission occasions if the capability indication 205 indicates that multiple feedback transmission occasions are supported by the UE 115-b, and, in some examples, the UE 115-a may stop attempting channel access procedures if the feedback message 220 is transmitted successfully. Meanwhile, if the capability indication 205 indicates that multiple feedback transmission occasions are not supported by the UE 115-b, the UE 115-a may attempt to transmit the feedback message 220 and performing a channel access procedure associated with only one feedback transmission occasion (e.g., a first configured feedback transmission occasion).

[0064] Additionally, or alternatively, the capability indication 205 may include a multiple bits that indicate a quantity of feedback transmission occasions supported by the UE 115-b per data message 215. For example, the capability indication 205 may indicate that the UE 115-b supports reception of feedback messages 220 on three feedback transmission occasions, and the UE 115-a may attempt up to three channelaccess procedures for transmissions via a first three feedback transmission occasions from a group of potential feedback transmission occasions for the data message 215. Alternatively, the capability indication 205 may include multiple bits (e.g., as a bitmap) that indicate which feedback transmission occasions are supported by the UE 115-b from the group of potential feedback transmission occasions. The group of potential feedback transmission occasions may be previously configured to the UE 115-b and the UE 115-b, such as by a resource pool configuration. As such, the UE 115-a may perform feedback message 220 transmission in accordance with the indicated feedback transmission occasions supported by the UE 115-b, as described in more detail herein, with reference to FIG. 3.

[0065] In some examples, signaling of the capability indication 205 may be enabled or disabled. For example, the UE 115-a and the UE 115-b may be configured (e.g., by receiving a message from a network entity 105) or preconfigured with a resource pool for sidelink communications. The resource pool configuration (e.g., or preconfiguration) may include an explicit indication of whether signaling of the capability indication 205 is enabled (e.g., as a field, one or more bits). Alternatively, the resource pool configuration may implicitly indicate whether signaling of the capability indication 205 is enabled. For example, the resource pool configuration may indicate that a single feedback transmission occasion (e g., PSFCH occasion) is configured per each data message 215 (e.g., PSSCH), which may indicate the UE 115-a and the UE 115-b that signaling of the capability indication 205 is disabled. Alternatively, if the resource pool configuration indicates multiple feedback transmission occasions per data message, the UE 115-a and the UE 115-b may determine (e.g., assume) that signaling of the capability indication 205 is enabled.

[0066] In some cases, communication of feedback messages 220 may be based on a capability of the UE 115-a. For example, if the UE 115-a supports transmission of feedback messages 220 on a single feedback transmission occasion, the UE 115-a may refrain from attempting transmission of feedback messages 220 on the additional feedback transmission occasions. In some examples, the UE 115-a may transmit an indication of the capability of the UE 115-a to support transmission of feedbackmessages 220 on multiple feedback transmission occasions to the UE 115-b, for example, in a similar manner as the capability indication 205 is transmitted. As such,the UE 115-b may monitor for feedback messages 220 on multiple feedback transmission occasions based on the capability of the UE 115-ato transmit feedback messages 220 on multiple feedback transmission occasions per data message 215, and the UE 115-b may refrain from monitoring more than one feedback transmission occasion the UE 115-a does not have the capability to transmit on multiple feedback transmission occasions per data message 215.

[0067] Accordingly, the UE 115-a and the UE 115-b may support communication of feedback messages 220 on multiple feedback transmission occasions in accordance with the capability of the UE 115-b, which may improve successful transmission of feedback messages 220.

[0068] FIG. 3 shows an example of a diagram 300 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The diagram 300 may include a bandwidth 305, which may represent a frequency bandwidth within an unlicensed spectrum. The bandwidth 305 may be used for sidelink communications between a first UE 115 and a second UE 115, as described herein with reference to FIGs. 1 and 2.

[0069] The bandwidth 305 may include a control message occasion 310 (e.g., a PSCCH occasion) which may be used for transmission of a control message by the second UE 115 to the first UE 115. In some examples, the control message may include control information, such as 1st-stage SCI (e.g., SCI-1) associated with a data message to be transmitted by the second UE 115. The bandwidth 305 may also include data message occasions 315, which may be used for transmission of the data message by the second UE 115. In some cases, the bandwidth 305 may include a data message occasion with control information 325, which may be a data message occasion 315 for transmission of a data message containing control information, such as 2nd-stage SCI (e.g., SCI-2).

[0070] In accordance with examples as described herein, the bandwidth 305 may include multiple feedback message occasions 320 (e.g., PSFCH occasions), such as the feedback message occasion 320-a, the feedback message occasion 320-b, and the feedback message occasion 320-c. The feedback message occasions 320 may be used for transmission of a feedback message (e.g., a PSFCH message) by the first UE 115. Insome examples, the bandwidth 305 may include one or more gap periods 330. For example, the bandwidth 305 may include a gap period 330 before a first feedback message occasion 320 (e.g., the feedback message occasion 320-a) and after a last feedback message occasion 320 (e.g., the feedback message occasion 320-c). While FIG. 3 illustrates three feedback message occasions 320, a different quantity of feedback message occasions 320 may be configured for the bandwidth 305 per data message. Similarly, though FIG. 3 illustrates the feedback message occasions 320 as being within a same slot, in other examples, the feedback message occasions 320 corresponding to (e.g., available for) a same feedback message may be distributed across multiple slots.

[0071] The first UE 115 may transmit attempt transmission of a feedback message in response to a data message from the second UE 115 based on a capability of the second UE 115 to support reception of feedback messages on multiple feedback message occasions 320 per data message, as described herein with reference to FIGs. 1 and 2. For example, the first UE 115 may receive an indication of the capability of the second UE 115 that indicates that the second UE 115 supports reception of feedback messages on multiple feedback message occasions 320 per data message.

[0072] In some examples, the first UE 115 may perform a channel access procedure (e.g., a listen-before-talk procedure) for transmission of the feedback message via the feedback message occasion 320-a. In some cases, if the channel access procedure succeeds, the first UE 115 may transmit the feedback message via the feedback message occasion 320-a and refrain from performing channel access procedures on other feedback message occasions 320. Alternatively, the first UE 115 may still perform channel access procedures for transmission of the feedback message via the feedback message occasion 320-b and the feedback message occasion 320-c, and the first UE 115 may transmit the feedback message on these feedback message occasions 320 if the respective channel access procedures are successful.

[0073] In some examples, the capability indication from the second UE 115 may indicate a quantity (e.g., N) of feedback message occasions 320 supported by the second UE 115, and the first UE may attempt transmission of the feedback message on feedback message occasions 320 up to the indicated quantity (e.g., N). For example, the capability indication from the second UE 115 may indicate that two feedback messageoccasions 320 are supported by the second UE 115. The first UE 115 may perform a first channel access procedure for transmission of the feedback message via the feedback message occasion 320-a. If the first channel access procedure is unsuccessful, the first UE 115 may perform a second channel access procedure for transmission of the feedback message via the feedback message occasion 320-b. If the second channel access procedure is successful, the first UE 115 may transmit the feedback message via the feedback message occasion 320-b. In some examples, the first UE 115 may perform the second channel access procedure regardless of whether the first channel access procedure is successful. For example, the first UE 115 may attempt transmission of the channel access procedure the indicated quantity of times (e.g., N times), and perform repetitions of the feedback message if multiple channel access procedures are successful. Alternatively, the first UE 115 may refrain from performing additional channel access procedures and attempting feedback message transmissions after a successful transmission is performed or until the indicated quantity of times is reached.

[0074] In some examples, the capability indication from the second UE 115 may indicate which feedback message occasions 320 are supported by the second UE 115 (e.g., using a bitmap), which may be a subset of the feedback message occasions 320 configured for the bandwidth 305. The first UE 115 may attempt transmission of the feedback message via the feedback message occasion 320 supported by the second UE 115. In some examples, the first UE 115 may refrain from performing additional channel access procedures after successfully transmitting the feedback message (e.g., after a successful channel access procedure). Alternatively, the first UE 115 may attempt transmission of the feedback message on each of the supported feedback message occasions 320. For example, the capability indication may indicate that the second UE 115 supports reception of the feedback message via the feedback message occasion 320-a and the feedback message occasion 320-c. The first UE 115 may perform a first channel access procedure for transmission via the feedback message occasion 320-a. If the first channel access procedure is unsuccessful, the first UE 115 may perform a second channel access procedure for transmission via the feedback message occasion 320-c. If the second channel access procedure is successful, the first UE 115 may transmit the feedback message to the second UE 115 via the feedback message occasion 320-c.

[0075] Accordingly, the first UE 115 may attempt transmission of feedback messages on one or more feedback message occasions 320 in accordance with a capability of the second UE 115, thereby improving the reliability of feedback messages in sidelink communications (e.g., via an unlicensed spectrum).

[0076] FIG. 4 shows an example of a process flow 400 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The process flow 400 may implement aspects of or be implemented by the wireless communications system 100 and the wireless communications system 200. For example, the process flow 400 illustrates communications between a UE 115-c and a UE 115-d, which may be examples of UEs 115 as described herein, with reference to FIGs. 1 through 3. In some examples, some steps may be added to the process flow 400, and some steps may be omitted.

[0077] At 405, the UE 115-d may transmit a message including a capabilityindication associated with a capability of the UE 115-d to monitor a set of feedback transmission occasions for a feedback message associated with a data message transmitted by the UE 115-d. In some examples, the message transmitted at 405 may be a sidelink control message that schedules the data message (which may be transmitted separately from the UE 115-d to the UE 115-c), and the sidelink control message transmitted at 405 may include one or more reserved bits within 1st-stage SCI (e.g., SCI- 1) included in the control message for the capability indication. In some other examples, the message transmitted at 405 may be the data message (e.g., a sidelink data message) with which the feedback message is associated, and the capability indication may be included as a field within 2nd-stage SCI (e.g., SCI-2) within the sidelink data message transmitted at 405. Additionally, or alternatively, the capability indication may be included as a field in a MAC header (e.g., a MAC subheader) of the sidelink data message, or within a field in a MAC-CE element that may be multiplexed with the sidelink data message transmitted at 405.

[0078] At 410, the UE 115-c may perform a first channel access procedure for potential transmission of the feedback message via a first feedback transmission occasion of the set of feedback transmission occasions. In some examples, the channel access procedure may involve monitoring a bandwidth (e.g., of an unlicensed spectrum) for transmissions by other UEs 115. In some cases, the UE 115-c may determine that achannel for the first feedback transmission occasion (e.g., a PSFCH) is busy based on the monitoring, resulting in the first channel access procedure being unsuccessful. As such, the UE 115-c may refrain from transmitting the feedback message via the first feedback transmission occasion. If, however, the channel access procedure were successful, then the UE 115-c may have transmitted the feedback message via the first feedback transmission occasion.

[0079] At 415, the UE 115-c may perform a second channel access procedure for potential transmission of the feedback message via a second feedback transmission occasion of the set of feedback transmission occasions. For example, the UE 115-c may monitor the bandwidth for transmissions by other UEs 115 based on the capability of the UE 115-d to support reception of feedback messages on the set of feedback transmission occasions.

[0080] In some examples, the UE 115-c may perform the second channel access procedure based on the first channel access procedure being unsuccessful. For example, if the first channel access procedure were instead successful, and the UE 115-c had thus transmitted the feedback message via the first feedback transmission occasion, then the UE 115-c may refrain from performing any further channel access procedures in connection with the feedback message (e.g., to conserve resources). In some other examples, the UE 115-c may perform the second channel access procedure regardless of whether the first channel access procedure is successful or unsuccessful . For example, the UE 115-c may seek to transmit the feedback message via as many feedback transmission occasions of the set of feedback transmission occasions as possible, even if the feedback message has already been transmitted via a prior feedback transmission occasion associated with a prior channel access procedure (e.g., to improve the reliability of reception of the feedback message by the UE 115-d).

[0081] At 420, the UE 115-c may transmit the feedback message via the second feedback transmission occasion based on the second channel access procedure being successful and on the capability of the UE 115-d. In some examples, to reduce redundancy and channel congestion or otherwise conserve resources, the UE 115-c may refrain from performing additional channel access procedures and feedback message transmissions associated with the data message based on the second channel access procedure being successful (e.g., and on transmitting the feedback message), consistentwith some of the examples discussed above in connection with 415, among other aspects of the present disclosure. Alternatively, at 425, the UE 115-c may perform a third channel access procedure for transmission of the feedback message via a third feedback transmission occasion of the set of feedback transmission occasions consistent with some of the other examples discussed above in connection with 415, among other aspects of the present disclosure.

[0082] At 430, if the third channel access procedure was successful, the UE 115-c may transmit a repetition the feedback message via the third feedback transmission occasion. For example, to increase reliability of the feedback message, the UE 115-c may be configured to attempt transmission of the feedback message on each feedback transmission occasion supported by the UE 115-d for reception of the feedback message, regardless of whether the feedback message has been priorly transmitted.

[0083] Accordingly, the UE 115-c and the UE 115-d may attempt communication of feedback messages via multiple feedback transmission occasions per data message, which may increase the reliability of feedback message transmissions.

[0084] FIG. 5 shows a block diagram 500 of a device 505 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a transmitter 515, and a communications manager 520. The device 505, or one or more components of the device 505 (e.g., the receiver 510, the transmitter 515, and the communications manager 520), may include at least one processor, which may be coupled with at least one memory, to, individually or collectively, support or enable the described techniques. Each of these components may be in communication with one another (e.g., via one or more buses).

[0085] The receiver 510 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to supporting multiple feedback occasions for sidelink communications). Information may be passed on to other components of the device 505. The receiver 510 may utilize a single antenna or a set of multiple antennas.

[0086] The transmitter 515 may provide a means for transmitting signals generated by other components of the device 505. For example, the transmitter 515 may transmit information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to supporting multiple feedback occasions for sidelink communications). In some examples, the transmitter 515 may be co-located with a receiver 510 in a transceiver module. The transmitter 515 may utilize a single antenna or a set of multiple antennas.

[0087] The communications manager 520, the receiver 510, the transmitter 515, or various combinations thereof or various components thereof may be examples of means for performing various aspects of support for multiple feedback occasions in sidelink as described herein. For example, the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be capable of performing one or more of the functions described herein.

[0088] In some examples, the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry). The hardware may include at least one of a processor, a digital signal processor (DSP), a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting, individually or collectively, a means for performing the functions described in the present disclosure. In some examples, at least one processor and at least one memory coupled with the at least one processor may be configured to perform one or more of the functions described herein (e.g., by one or more processors, individually or collectively, executing instructions stored in the at least one memory).

[0089] Additionally, or alternatively, the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented in code (e.g., as communications management software or firmware) executed by at least one processor. If implemented in code executed by at least one processor, the functions of the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be performed by ageneral-purpose processor, a DSP, a CPU, an ASIC, an FPGA, a microcontroller, or any combination of these or other programmable logic devices (e.g., configured as or otherwise supporting, individually or collectively, a means for performing the functions described in the present disclosure).

[0090] In some examples, the communications manager 520 may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver 510, the transmitter 515, or both. For example, the communications manager 520 may receive information from the receiver 510, send information to the transmitter 515, or be integrated in combination with the receiver 510, the transmitter 515, or both to obtain information, output information, or perform various other operations as described herein.

[0091] The communications manager 520 may support wireless communications in accordance with examples as disclosed herein. For example, the communications manager 520 is capable of, configured to, or operable to support a means for receiving an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message. The communications manager 520 is capable of, configured to, or operable to support a means for monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. The communications manager 520 is capable of, configured to, or operable to support a means for monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The communications manager 520 is capable of, configured to, or operable to support a means for transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based on the indicated capability of the second UE and the second channel access procedure being successful.

[0092] Additionally, or alternatively, the communications manager 520 may support wireless communications in accordance with examples as disclosed herein. Forexample, the communications manager 520 is capable of, configured to, or operable to support a means for transmitting an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The communications manager 520 is capable of, configured to, or operable to support a means for monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The communications manager 520 is capable of, configured to, or operable to support a means for monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The communications manager 520 is capable of, configured to, or operable to support a means for receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

[0093] By including or configuring the communications manager 520 in accordance with examples as described herein, the device 505 (e.g., at least one processor controlling or otherwise coupled with the receiver 510, the transmitter 515, the communications manager 520, or a combination thereof) may support techniques for supporting multiple feedback transmission occasions, which may improve communications between devices and reduce unnecessary retransmissions, which may further reduce power consumption and network congestion.

[0094] FIG. 6 shows a block diagram 600 of a device 605 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The device 605 may be an example of aspects of a device 505 or a UE 115 as described herein. The device 605 may include a receiver 610, a transmitter 615, and a communications manager 620. The device 605, or one or more components of the device 605 (e.g., the receiver 610, the transmitter 615, and the communications manager 620), may include at least one processor, which may be coupled with at least one memory, to support the described techniques. Each of these components may be in communication with one another (e.g., via one or more buses).

[0095] The receiver 610 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to supporting multiple feedback occasions for sidelink communications). Information may be passed on to other components of the device 605. The receiver 610 may utilize a single antenna or a set of multiple antennas.

[0096] The transmitter 615 may provide a means for transmitting signals generated by other components of the device 605. For example, the transmitter 615 may transmit information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to supporting multiple feedback occasions for sidelink communications). In some examples, the transmitter 615 may be co-located with a receiver 610 in a transceiver module. The transmitter 615 may utilize a single antenna or a set of multiple antennas.

[0097] The deuce 605, or various components thereof, may be an example of means for performing various aspects of support for multiple feedback occasions in sidelink as described herein. For example, the communications manager 620 may include a capability manager 625, a channel access component 630, a feedback message component 635, a capability component 640, a feedback message manager 645, or any combination thereof. The communications manager 620 may be an example of aspects of a communications manager 520 as described herein. In some examples, the communications manager 620, or various components thereof, may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver 610, the transmitter 615, or both. For example, the communications manager 620 may receive information from the receiver 610, send information to the transmitter 615, or be integrated in combination with the receiver 610, the transmitter 615, or both to obtain information, output information, or perform various other operations as described herein.

[0098] The communications manager 620 may support wireless communications in accordance with examples as disclosed herein. The capability manager 625 is capable of, configured to, or operable to support a means for receiving, via a message, an indication of a capability of a second UE to monitor a set of feedback transmissionoccasions for a feedback message associated with a sidelink message. The channel access component 630 is capable of, configured to, or operable to support a means for monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. The channel access component 630 is capable of, configured to, or operable to support a means for monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The feedback message component 635 is capable of, configured to, or operable to support a means for transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based on the indicated capability of the second UE and the second channel access procedure being successful.

[0099] Additionally, or alternatively, the communications manager 620 may support wireless communications in accordance with examples as disclosed herein. The capability component 640 is capable of, configured to, or operable to support a means for transmitting, via a message, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The feedback message manager 645 is capable of, configured to, or operable to support a means for monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The feedback message manager 645 is capable of, configured to, or operable to support a means for monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The feedback message manager 645 is capable of, configured to, or operable to support a means for receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

[0100] FIG. 7 shows a block diagram 700 of a communications manager 720 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The communications manager 720 may be an example of aspects of a communications manager 520, a communications manager 620, or both, as described herein. The communications manager 720, or various components thereof, may be an example of means for performing various aspects of support for multiple feedback occasions in sidelink as described herein. For example, the communications manager 720 may include a capability manager 725, a channel access component 730, a feedback message component 735, a capability component 740, a feedback message manager 745, a sidelink message manager 750, a control message manager 755, a sidelink message component 760, a control message component 765, a feedback message component 770, or any combination thereof. Each of these components, or components or subcomponents thereof (e.g., one or more processors, one or more memories), may communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0101] The communications manager 720 may support wireless communications in accordance with examples as disclosed herein. The capability manager 725 is capable of, configured to, or operable to support a means for receiving, via a message, an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message. The channel access component 730 is capable of, configured to, or operable to support a means for monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. In some examples, the channel access component 730 is capable of, configured to, or operable to support a means for monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The feedback message component 735 is capable of, configured to, or operable to support a means for transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedbacktransmission occasions based on the indicated capability of the second UE and the second channel access procedure being successfill.

[0102] In some examples, to support receiving the indication of the capability, the sidelink message manager 750 is capable of, configured to, or operable to support a means for receiving the sidelink message from the second UE, the sidelink message including the indication of the capability.

[0103] In some examples, a value of a field within sidelink control information of the sidelink message indicates the capability. In some examples, a value of a field within a medium access control header of the sidelink message indicates the capability. In some examples, a value within a medium access control-control element indicates the capability, the medium access control-control element multiplexed with data that is included in the sidelink message.

[0104] In some examples, to support receiving the indication of the capability, the control message manager 755 is capable of, configured to, or operable to support a means for receiving a control message from the second UE that schedules the sidelink message for reception by the first UE, the control message including the indication of the capability.

[0105] In some examples, a value of a field within sidelink control information of the control message indicates the capability. In some examples, the field includes one or more reserved bits within the control message. In some examples, the indication of the capability indicates that the second UE is able to monitor multiple feedback transmission occasions per sidelink feedback message. In some examples, the indication of the capability indicates a quantity of feedback transmission occasions that the second UE is able to monitor per sidelink feedback message.

[0106] In some examples, the indication of the capability includes a bitmap that indicates the set of feedback transmission occasions that the second UE is able to monitor, the indicated set of feedback transmission occasions including some or all feedback transmission occasions from a group of potential feedback transmission occasions.

[0107] In some examples, to support receiving the indication of the capability, the channel access component 730 is capable of, configured to, or operable to support a means for monitoring the bandwidth as part of a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions. In some examples, to support receiving the indication of the capability, the feedback message component 770 is capable of, configured to, or operable to support a means for transmitting a repetition of the feedback message via the third feedback transmission occasion based on the capability of the second UE and the third channel access procedure being successfill.

[0108] In some examples, the channel access component 730 is capable of, configured to, or operable to support a means for refraining from performing a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions based on the second channel access procedure being successful.

[0109] In some examples, receiving the indication of the capability is based on a resource pool configuration, the resource pool configuration indicating that capability signaling associated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled. In some examples, the resource pool configuration indicates that the capability signaling is enabled based on a quantity of feedback transmission occasions enabled in the resource pool configuration.

[0110] In some examples, transmitting the feedback message via the second feedback transmission occasion is further based on a capability of the first UE to transmit feedback messages via the set of feedback transmission occasions.

[0111] Additionally, or alternatively, the communications manager 720 may support wireless communications in accordance with examples as disclosed herein. The capability component 740 is capable of, configured to, or operable to support a means for transmitting, via a message, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The feedback message manager 745 is capable of, configured to, or operable to support a means for monitoring a first feedback transmission occasion ofthe set of feedback transmission occasions for the feedback message from a first UE. Tn some examples, the feedback message manager 745 is capable of, configured to, or operable to support a means for monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. In some examples, the feedback message manager 745 is capable of, configured to, or operable to support a means for receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

[0112] In some examples, to support transmitting the indication of the capability, the sidelink message component 760 is capable of, configured to, or operable to support a means for transmitting the sidelink message to the first UE, the sidelink message including the indication of the capability.

[0113] In some examples, a value of a field within sidelink control information of the sidelink message indicates the capability. In some examples, a value of a field within a medium access control header of the sidelink message indicates the capability. In some examples, a value within a medium access control-control element indicates the capability, the medium access control-control element multiplexed with data that is included in the sidelink message.

[0114] In some examples, to support transmitting the indication of the capability, the control message component 765 is capable of, configured to, or operable to support a means for transmitting a control message to the first UE that schedules the sidelink message for reception by the first UE, the control message including the indication of the capability.

[0115] In some examples, a value of a field within sidelink control information of the control message indicates the capability. In some examples, the field includes one or more reserved bits within the control message.

[0116] In some examples, the indication of the capability indicates that the second UE is able to monitor multiple feedback transmission occasions per sidelink feedback message. In some examples, the indication of the capability indicates a quantity offeedback transmission occasions that the second UE is able to monitor per sidelink feedback message.

[0117] In some examples, the indication of the capability includes a bitmap that indicates the set of feedback transmission occasions that the second UE is able to monitor, the indicated set of feedback transmission occasions including some or all feedback transmission occasions from a group of potential feedback transmission occasions.

[0118] In some examples, transmitting the indication of the capability is based on a resource pool configuration, the resource pool configuration indicating that capability signaling associated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled. In some examples, the resource pool configuration indicates that the capability signaling is enabled based on a quantity of feedback transmission occasions enabled in the resource pool configuration.

[0119] In some examples, receiving the feedback message is further based on a capability of the first UE to transmit feedback messages via the set of feedback transmission occasions.

[0120] FIG. 8 shows a diagram of a system 800 including a device 805 that supports multiple feedback occasions in accordance with one or more aspects of the present disclosure. The device 805 may be an example of or include the components of a device 505, a device 605, or a UE 115 as described herein. The device 805 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. The device 805 may include components for bidirectional voice and data communications including components for transmitting and receiving communications, such as a communications manager 820, an input / output (I / O) controller 810, a transceiver 815, an antenna 825, at least one memory 830, code 835, and at least one processor 840. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus 845).

[0121] The I / O controller 810 may manage input and output signals for the device805. The I / O controller 810 may also manage peripherals not integrated into the device805. In some cases, the I / O controller 810 may represent a physical connection or portto an external peripheral. Tn some cases, the I / O controller 810 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. Additionally, or alternatively, the I / O controller 810 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I / O controller 810 may be implemented as part of one or more processors, such as the at least one processor 840. In some cases, a user may interact with the device 805 via the I / O controller 810 or via hardware components controlled by the I / O controller 810.

[0122] In some cases, the device 805 may include a single antenna 825. However, in some other cases, the device 805 may have more than one antenna 825, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 815 may communicate bi-directionally, via the one or more antennas 825, wired, or wireless links as described herein. For example, the transceiver 815 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 815 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 825 for transmission, and to demodulate packets received from the one or more antennas 825. The transceiver 815, or the transceiver 815 and one or more antennas 825, may be an example of a transmitter 515, a transmitter 615, a receiver 510, a receiver 610, or any combination thereof or component thereof, as described herein.

[0123] The at least one memory 830 may include random access memory (RAM) and read-only memory (ROM). The at least one memory 830 may store computer- readable, computer-executable code 835 (e.g., processor-executable code) including instructions that, when executed by the at least one processor 840, cause the device 805 to perform various functions described herein. The code 835 may be stored in a non- transitory computer-readable medium such as system memory or another type of memory. In some cases, the code 835 may not be directly executable by the at least one processor 840 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, tire at least one memory 830 may contain, among other things, a basic I / O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

[0124] The at least one processor 840 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the at least one processor 840 may be configured to operate a memory array using a memory controller. In some other cases, a memory controller may be integrated into the at least one processor 840. The at least one processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., the at least one memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks supporting support for multiple feedback occasions in sidelink). For example, the device 805 or a component of the device 805 may include at least one processor 840 and at least one memory 830 coupled with or to the at least one processor 840, the at least one processor 840 and at least one memory 830 configured to perform various functions described herein. In some examples, the at least one processor 840 may include multiple processors and the at least one memory 830 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein. In some examples, the at least one processor 840 may be a component of a processing system, which may refer to a system (such as a series) of machines, circuitry (including, for example, one or both of processor circuitry (which may include the at least one processor 840) and memory circuitry (which may include the at least one memory 830)), or components, that receives or obtains inputs and processes the inputs to produce, generate, or obtain a set of outputs. The processing system may be configured to perform one or more of the functions described herein. As such, the at least one processor 840 or a processing system including the at least one processor 840 may be configured to, configurable to, or operable to cause the device 805 to perform one or more of the functions described herein. Further, as described herein, being “configured to,” being “configurable to,” and being “operable to” may be used interchangeably and may be associated with a capability, when executing code stored in the at least one memory 830 or otherwise, to perform one or more of the functions described herein.

[0125] The communications manager 820 may support wireless communications in accordance with examples as disclosed herein. For example, the communications manager 820 is capable of, configured to, or operable to support a means for receiving, via a message, an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message. The communications manager 820 is capable of, configured to, or operable to support a means for monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. The communications manager 820 is capable of, configured to, or operable to support a means for monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The communications manager 820 is capable of, configured to, or operable to support a means for transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based on the indicated capability of the second UE and the second channel access procedure being successful.

[0126] Additionally, or alternatively, the communications manager 820 may support wireless communications in accordance with examples as disclosed herein. For example, the communications manager 820 is capable of, configured to, or operable to support a means for transmitting, via a message, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The communications manager 820 is capable of, configured to, or operable to support a means for monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The communications manager 820 is capable of, configured to, or operable to support a means for monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions forthe feedback message from a first UE. The communications manager 820 is capable of, configured to, or operable to support a means for receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

[0127] By including or configuring the communications manager 820 in accordance with examples as described herein, the device 805 may support techniques for supporting multiple feedback transmission occasions, which may improve communications between devices and reduce unnecessary retransmissions, which may further reduce power cansumptian and network congestion.

[0128] In some examples, the communications manager 820 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise in cooperation with the transceiver 815, the one or more antennas 825, or any combination thereof. Although the communications manager 820 is illustrated as a separate component, in some examples, one or more functions described with reference to the communications manager 820 may be supported by or performed by the at least one processor 840, the at least one memory 830, the code 835, or any combination thereof. For example, the code 835 may include instructions executable by the at least one processor 840 to cause the device 805 to perform various aspects of support for multiple feedback occasions in sidelink as described herein, or the at least one processor 840 and the at least one memory 830 may be otherwise configured to, individually or collectively, perform or support such operations.

[0129] FIG. 9 shows a flowchart illustrating a method 900 that supports multiple feedback occasions in accordance with aspects of the present disclosure. The operations of the method 900 may be implemented by a UE or its components as described herein. For example, the operations of the method 900 may be performed by a UE 115 as described with reference to FIGs. 1 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

[0130] At 905, the method may include receiving an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback messageassociated with a sidelink message. The operations of block 905 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 905 may be performed by a capability manager 725 as described with reference to FIG. 7.

[0131] At 910, the method may include monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. The operations of block 910 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 910 may be performed by a channel access component 730 as described with reference to FIG. 7.

[0132] At 915, the method may include monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The operations of block 915 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 915 may be performed by a channel access component 730 as described with reference to FIG. 7.

[0133] At 920, the method may include transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based on the indicated capability of the second UE and the second channel access procedure being successful. The operations of block 920 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 920 may be performed by a feedback message component 735 as described with reference to FIG. 7.

[0134] FIG. 10 shows a flowchart illustrating a method 1000 that supports multiple feedback occasions in accordance with aspects of the present disclosure. The operations of the method 1000 may be implemented by a UE or its components as described herein. For example, the operations of the method 1000 may be performed by a UE 115 as described with reference to FIGs. 1 through 8. In some examples, a UE may executea set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

[0135] At 1005, the method may include receiving, via a sidelink message from a second UE, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with the sidelink message. The operations of block 1005 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1005 may be performed by a capability manager 725 as described with reference to FIG. 7.

[0136] At 1010, the method may include monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, where the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based on the first channel access procedure being unsuccessful. The operations of block 1010 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1010 may be performed by a channel access component 730 as described with reference to FIG. 7.

[0137] At 1015, the method may include monitoring, based on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions. The operations of block 1015 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1015 may be performed by a channel access component 730 as described with reference to FIG. 7.

[0138] At 1020, the method may include transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based on the indicated capability of the second UE and the second channel access procedure being successful. The operations of block 1020 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1020 may be performed by a feedback message component 735 as described with reference to FIG. 7.

[0139] FIG. 11 shows a flowchart illustrating a method 1100 that supports multiple feedback occasions in accordance with aspects of the present disclosure. The operations of the method 1100 may be implemented by a UE or its components as described herein. For example, the operations of the method 1100 may be performed by a UE 115 as described with reference to FIGs. 1 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

[0140] At 1105, the method may include transmitting an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The operations of block 1 105 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1105 may be performed by a capability component 740 as described with reference to FIG. 7.

[0141] At 1110, the method may include monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE. The operations of block 1110 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1110 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0142] At 1115, the method may include monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from the first UE. The operations of block 1115 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1115 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0143] At 1120, the method may include receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion. The operations of block 1120 may be performed in accordance with examples as disclosed herein. In some examples, aspects of theoperations of 1120 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0144] FIG. 12 shows a flowchart illustrating a method 1200 that supports multiple feedback occasions in accordance with aspects of the present disclosure. The operations of the method 1200 may be implemented by a UE or its components as described herein. For example, the operations of the method 1200 may be performed by a UE 115 as described with reference to FIGs. 1 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

[0145] At 1205, the method may include transmitting, to a first UE and via a sidelink message, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with the sidelink message, the set of feedback transmission occasions within an unlicensed spectrum. The operations of block 1205 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1205 may be performed by a capability component 740 as described with reference to FIG. 7.

[0146] At 1210, the method may include monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from the first UE. The operations of block 1210 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1210 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0147] At 1215, the method may include monitoring, based on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from the first UE. The operations of block 1215 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1215 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0148] At 1220, the method may include receiving, based on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion. The operations of block 1220 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1220 may be performed by a feedback message manager 745 as described with reference to FIG. 7.

[0149] The following provides an overview of aspects of the present disclosure:

[0150] Aspect 1: A method for wireless communications at a first UE, comprising: receiving, via a message, an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message; monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, wherein the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based at least in part on the first channel access procedure being unsuccessful; monitoring, based at least in part on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions; and transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based at least in part on the indicated capability of the second UE and the second channel access procedure being successful.

[0151] Aspect 2: The method of aspect 1, wherein receiving the indication of the capability further comprises: receiving the sidelink message from the second UE, the sidelink message including the indication of the capability.

[0152] Aspect 3: The method of aspect 2, wherein a value of a field within sidelink control information of the sidelink message indicates the capability.

[0153] Aspect 4: The method of any of aspects 2 through 3, wherein a value of a field within a medium access control header of the sidelink message indicates the capability.

[0154] Aspect 5: The method of any of aspects 2 through 4, wherein a value within a medium access control-control element indicates the capability, the medium access control-control element multiplexed with data that is included in the sidelink message.

[0155] Aspect 6: The method of aspect 1, wherein receiving the indication of the capability further comprises: receiving a control message from the second UE that schedules the sidelink, message for reception by the first UE, the control message including the indication of the capability.

[0156] Aspect 7 : The method of aspect 6, wherein a value of a field within sidelink control information of the control message indicates the capability, and the field comprises one or more reserved bits within the control message.

[0157] Aspect 8: The method of any of aspects 1 through 7, wherein the indication of the capability indicates that the second UE is able to monitor multiple feedback transmission occasions per sidelink feedback message.

[0158] Aspect 9: The method of any of aspects 1 through 8, wherein the indication of the capability indicates a quantity of feedback transmission occasions that the second UE is able to monitor per sidelink feedback message.

[0159] Aspect 10: The method of any of aspects 1 through 9, wherein the indication of the capability comprises a bitmap that indicates the set of feedback transmission occasions that the second UE is able to monitor, the indicated set of feedback transmission occasions comprising some or all feedback transmission occasions from a group of potential feedback transmission occasions.

[0160] Aspect 11: The method of aspect 10, wherein receiving the indication of the capability further comprises: monitoring the bandwidth as part of a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions; and transmitting a repetition of the feedback message via the third feedback transmission occasion based at least in part on the capability of the second UE and the third channel access procedure being successful.

[0161] Aspect 12: The method of aspect 10, wherein monitoring the bandwidth as part of the second channel access procedure associated with the second feedback transmission occasion is further based at least in part on the first channel accessprocedure being successful, and wherein the method further comprises: refraining from performing a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions based at least in part on the second channel access procedure being successful.

[0162] Aspect 13: The method of any of aspects 1 through 12, wherein receiving the indication of the capability is based at least in part on a resource pool configuration, the resource pool configuration indicating that capability signaling associated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled.

[0163] Aspect 14: The method of aspect 13, wherein the resource pool configuration indicates that the capability signaling is enabled based at least in part on a quantity of feedback transmission occasions enabled in the resource pool configuration.

[0164] Aspect 15: The method of any of aspects 1 through 14, wherein transmitting the feedback message via the second feedback transmission occasion is further based at least in part on a capability of the first UE to transmit feedback messages via the set of feedback transmission occasions.

[0165] Aspect 16: A method for wireless communications at a second UE, comprising: transmitting, via a message, an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum; monitoring a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE; monitoring, based at least in part on transmitting the message indicating the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE; and receiving, based at least in part on monitoring the second feedback transmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

[0166] Aspect 17: The method of aspect 16, wherein transmitting the message indicating the capability further comprises: transmitting the sidelink message to the first UE, the sidelink message including the indication of the capability.

[0167] Aspect 18: The method of aspect 17, wherein a value of a field within sidelink control information of the sidelink message indicates the capability.

[0168] Aspect 19: The method of any of aspects 17 through 18, wherein a value of a field within a medium access control header of the sidelink message indicates the capability.

[0169] Aspect 20: The method of any of aspects 17 through 19, wherein a value within a medium access control-control element indicates the capability, the medium access control-control element multiplexed with data that is included in the sidelink message.

[0170] Aspect 21 : The method of any of aspect 16, wherein transmitting the indication of the capability further comprises: transmitting a control message to the first UE that schedules the sidelink message for reception by the first UE, the control message including the indication of the capability.

[0171] Aspect 22: The method of aspect 21, wherein a value of a field within sidelink control information of the control message indicates the capability, and the field comprises one or more reserved bits within the control message.

[0172] Aspect 23: The method of any of aspects 16 through 22, wherein the indication of the capability indicates that the second UE is able to monitor multiple feedback transmission occasions per sidelink feedback message.

[0173] Aspect 24: The method of any of aspects 16 through 23, wherein the indication of the capability indicates a quantity of feedback transmission occasions that the second UE is able to monitor per sidelink feedback message.

[0174] Aspect 25: The method of any of aspects 16 through 24, wherein the indication of the capability comprises a bitmap that indicates the set of feedback transmission occasions that the second UE is able to monitor, the indicated set of feedback transmission occasions comprising some or all feedback transmission occasions from a group of potential feedback transmission occasions.

[0175] Aspect 26: The method of any of aspects 16 through 25, wherein transmitting the message indicating the capability is based at least in part on a resource pool configuration, the resource pool configuration indicating that capability signalingassociated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled.

[0176] Aspect 27: The method of aspect 26, wherein the resource pool configuration indicates that the capability signaling is enabled based at least in part on a quantity of feedback transmission occasions enabled in the resource pool configuration.

[0177] Aspect 28: The method of any of aspects 16 through 27, wherein receiving the feedback message is further based at least in part on a capability of the first UE to transmit feedback messages via the set of feedback transmission occasions.

[0178] Aspect 29: A first UE for wireless communications, comprising one or more memories storing processor-executable code, and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the first UE to perform a method of any of aspects 1 through 15.

[0179] Aspect 30: A first UE for wireless communications, comprising at least one means for performing a method of any of aspects 1 through 15.

[0180] Aspect 31 : A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method of any of aspects 1 through 15.

[0181] Aspect 32: A second UE for wireless communications, comprising one or more memories storing processor-executable code, and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the second UE to perform a method of any of aspects 16 through 28.

[0182] Aspect 33: A second UE for wireless communications, comprising at least one means for performing a method of any of aspects 16 through 28.

[0183] Aspect 34: A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method of any of aspects 16 through 28.

[0184] It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwisemodified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

[0185] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein.

[0186] Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0187] The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed using a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gale 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 the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., 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). Any functions or operations described herein as being capable of being performed by a processor may be performed by multiple processors that, individually or collectively, are capable of performing the described functions or operations.

[0188] The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implementedusing software executed by a processor, the functions may be stored as or transmitted using one or more instructions or code of a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0189] Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one location to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc. Disks may reproduce data magnetically, and discs may reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media. Any functions or operations described herein as being capable of being performed by a memory may be performed by multiple memories that, individually or collectively, are capable of performing the described functions or operations.

[0190] As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive list such 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). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.”

[0191] As used herein, including in the claims, the article “a” before a noun is open- ended and understood to refer to “at least one” of those nouns or “one or more” of those nouns. Thus, the terms “a,” “at least one,” “one or more,” “at least one of one or more” max’ be interchangeable. For example, if a claim recites “a component” that performs one or more functions, each of the individual functions may be performed by a single component or by any combination of multiple components. Thus, the term “a component” having characteristics or performing functions may refer to “at least one of one or more components” having a particular characteristic or performing a particular function. Subsequent reference to a component introduced with the article “a” using the terms “the” or “said” may refer to any or all of the one or more components. For example, a component introduced with the article “a” may be understood to mean “one or more components,” and referring to “the component” subsequently in the claims may be understood to be equivalent to referring to “at least one of the one or more components.” Similarly, subsequent reference to a component introduced as “one or more components” using the terms “the” or “said” may refer to any or all of the one or more components. For example, referring to “the one or more components” subsequently in the claims may be understood to be equivalent to referring to “al least one of the one or more components.”

[0192] The term “determine” or “determining” encompasses a variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (such as via looking up in a table, a database, or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data stored in memory) and the like.Also, “determining” can include resolving, obtaining, selecting, choosing, establishing, and other such similar actions.

[0193] In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

[0194] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0195] The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

CLAIMSWhat is claimed is:

1. A first user equipment (UE), comprising: one or more memories storing processor-executable code; and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the first UE to: receive an indication of a capability' of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message; monitor a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, wherein the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based at least in part on the first channel access procedure being unsuccessful; monitor, based at least in part on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions; and transmit, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based at least in part on the indicated capability of the second UE and the second channel access procedure being successful.

2. The first UE of claim 1, wherein, to receive the indication of the capability, the one or more processors are individually or collectively operable to execute the code to cause the first UE to: receive the sidelink message from the second UE, the sidelink message including the indication of the capability.

3. The first UE of claim 2, wherein a value of a field within sidelink control information of the sidelink message indicates the capability.

4. The first UE of claim 2, wherein a value of a field within a medium access control header of the sidelink message indicates the capability.

5. The first UE of claim 2, wherein a value within a medium access control-control element indicates the capability, the medium access control-control element multiplexed with data that is included in the sidelink message.

6. The first UE of claim 1, wherein, to receive the indication of the capability, the one or more processors are individually or collectively operable to execute the code to cause the first UE to: receive a control message from the second UE that schedules the sidelink message for reception by the first UE, the control message including the indication of the capability.

7. The first UE of claim 6, wherein: a value of a field within sidelink control information of the control message indicates the capability, and the field comprises one or more reserved bits within the control message.

8. The first UE of claim 1, wherein the indication of the capability indicates that the second UE is able to monitor multiple feedback transmission occasions per sidelink feedback message.

9. The first UE of claim 1, wherein the indication of the capability indicates a quantity of feedback transmission occasions that the second UE is able to monitor per sidelink feedback message.

10. The first UE of claim 1, wherein the indication of the capability comprises a bitmap that indicates the set of feedback transmission occasions that the second UE is able to monitor, the indicated set of feedback transmission occasions comprising some or all feedback transmission occasions from a group of potential feedback transmission occasions.

11. The first UE of claim 10, wherein, to receive the indication of the capability, the one or more processors are individually or collectively operable to execute the code to cause the first UE to:monitor the bandwidth as part of a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions; and transmit a repetition of the feedback message via the third feedback transmission occasion based at least in part on the capability of the second UE and the third channel access procedure being successful.

12. The first UE of claim 10, wherein the one or more processors are individually or collectively operable to execute the code to cause the first UE to monitor the bandwidth as part of the second channel access procedure associated with the second feedback transmission occasion based at least in part on the first channel access procedure being successful, and wherein the one or more processors are individually or collectively further operable to execute the code to cause the first UE to: refrain from performing a third channel access procedure associated with a third feedback transmission occasion of the set of feedback transmission occasions based at least in part on the second channel access procedure being successful.

13. The first UE of claim 1 , wherein the one or more processors are individually or collectively operable to execute the code to cause the first UE to receive the indication of the capability based at least in part on a resource pool configuration, the resource pool configuration indicating that capability signaling associated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled.

14. The first UE of claim 13, wherein the resource pool configuration indicates that the capability signaling is enabled based at least in part on a quantity of feedback transmission occasions enabled in the resource pool configuration.

15. The first UE of claim 1, wherein the one or more processors are individually or collectively operable to execute the code to cause the first UE to transmit the feedback message via the second feedback transmission occasion based at least in part on a capability of the first UE to transmit feedback messages via the set of feedback transmission occasions.

16. A second user equipment (UE), comprising:one or more memories storing processor-executable code; and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the second UE to: transmit an indication of a capability of the second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message, the set of feedback transmission occasions within an unlicensed spectrum; monitor a first feedback transmission occasion of the set of feedback transmission occasions for the feedback message from a first UE; monitor, based at least in part on transmitting the indication of the capability and an absence of the feedback message during the first feedback transmission occasion, a second feedback transmission occasion of the set of feedback transmission occasions for the feedback message from the first UE; and receive, based at least in part on monitoring the second feedbacktransmission occasion, the feedback message from the first UE via the second feedback transmission occasion.

17. The second UE of claim 16, wherein, to transmit the indication of the capability, the one or more processors are individually or collectively operable to execute the code to cause the second UE to: transmit the sidelink message to the first UE, the sidelink message including the indication of the capability.

18. The second UE of claim 16, wherein, to transmit the indication of the capability, the one or more processors are individually or collectively operable to execute the code to cause the second UE to: transmit a control message to the first UE that schedules the sidelink message for reception by the first UE, the control message including the indication of the capability.

19. The second UE of claim 16, wherein the one or more processors are individually or collectively operable to execute the code to cause the first UE to transmit the indication of the capability based at least in part on a resource poolconfiguration, the resource pool configuration indicating that capability signaling associated with monitoring multiple feedback transmission occasions per sidelink feedback message is enabled.

20. A method for wireless communications at a first user equipment(UE), comprising: receiving an indication of a capability of a second UE to monitor a set of feedback transmission occasions for a feedback message associated with a sidelink message; monitoring a bandwidth within an unlicensed spectrum as part of a first channel access procedure associated with a first feedback transmission occasion of the set of feedback transmission occasions, wherein the first UE refrains from transmitting the feedback message during the first feedback transmission occasion based at least in part on the first channel access procedure being unsuccessful; monitoring, based at least in part on the indicated capability of the second UE, the bandwidth as part of a second channel access procedure associated with a second feedback transmission occasion of the set of feedback transmission occasions; and transmitting, to the second UE, the feedback message via the second feedback transmission occasion of the set of feedback transmission occasions based at least in part on the indicated capability of the second UE and the second channel access procedure being successfill.

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