WO2024174208A1

WO2024174208A1 - Priority handling for feedback channels in sidelink

Info

Publication number: WO2024174208A1
Application number: PCT/CN2023/078063
Authority: WO
Inventors: Shaozhen GUO; Changlong Xu; Xiaoxia Zhang; Jing Sun; Chih-Hao Liu; Siyi Chen; Luanxia YANG; Giovanni Chisci; Hao Xu
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2023-02-24
Filing date: 2023-02-24
Publication date: 2024-08-29
Anticipated expiration: 2025-08-24
Also published as: CN120693965A

Abstract

Methods, systems, and devices for wireless communication are described. In some systems, a sidelink user equipment (UE) may prioritize multiple sidelink feedback channels for transmission via at least partially overlapping time resources. The UE may prioritize the sidelink feedback channels in accordance with prioritization parameters, where each prioritization parameter may be associated with a respective likelihood of success of a listen-before-talk (LBT) procedure for a respective sidelink feedback channel. The UE select a subset of the sidelink feedback channels based on the prioritization and may perform one or more LBT procedures to access a shared radio frequency spectrum band for transmission of the subset of sidelink feedback channels. The UE may transmit the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

Description

PRIORITY HANDLING FOR FEEDBACK CHANNELS IN SIDELINK

FIELD OF TECHNOLOGY

The following relates to wireless communication, including priority handling for feedback channels in sidelink.

BACKGROUND

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) . 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 systems, a UE may receive sidelink messages from one or more other sidelink UEs. The UE may generate feedback based on the sidelink messages and may transmit a physical sidelink feedback channel (PSFCH) to convey the feedback in response to one or more of the sidelink messages.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support priority handling for feedback channels in sidelink. For example, the described techniques enable a sidelink user equipment (UE) to select which sidelink feedback channels to transmit in a given transmission occasion of a shared or unlicensed band based on a prioritization of the sidelink feedback channels. The UE may have multiple sidelink feedback channels for transmission in at least partially overlapping time resources. The UE may prioritize the feedback channels according to a set of prioritization parameters, where each prioritization parameter may be associated with a respective likelihood of success of a listen-before-talk (LBT) procedure for a respective sidelink feedback channel. The UE may select a subset of the sidelink feedback channels based on the prioritization. The UE may perform one or more LBT procedures for the selected subset of sidelink feedback channels. The LBT procedures may be, for example, type-1 channel access procedures, or some other type of channel access procedure to gain access to a shared radio frequency spectrum band for transmission of the subset of sidelink communications. The UE may transmit the subset of sidelink feedback channels during one or more channel occupancy time (COT) intervals of one or more successful LBT procedures based on performing the LBT procedures and selecting the subset of sidelink feedback channels.

A method for wireless communication at a UE is described. The method may include prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing, and transmitting the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

An apparatus for wireless communication at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to prioritize, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, perform one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing, and transmit the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

Another apparatus for wireless communication at a UE is described. The apparatus may include means for prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, means for performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing, and means for transmitting the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor to prioritize, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, perform one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing, and transmit the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, prioritizing the set of multiple sidelink feedback channels may include operations, features, means, or instructions for prioritizing, based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, where the respective sidelink feedback priority values may be indicated via sidelink control information (SCI) associated with the at least two sidelink feedback channels.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, prioritizing the set of multiple sidelink feedback channels may include operations, features, means, or instructions for prioritizing the set of multiple sidelink feedback channels according to respective sidelink feedback priority values associated with each of the set of multiple sidelink feedback channels, where prioritizing the set of multiple sidelink feedback channels according to the set of multiple prioritization parameters may be based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same sidelink feedback priority value.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, prioritizing the set of multiple sidelink feedback channels may include operations, features, means, or instructions for prioritizing the set of multiple sidelink feedback channels according to one or more resource block loads, each resource block load of the one or more resource block loads associated with a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, where each sidelink feedback channel of the set of multiple sidelink feedback channels may be scheduled for transmission via a respective resource block set of the one or more resource block sets.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving SCI within a window associated with a first resource block set of the one or more resource block sets, where a first resource block load of the first resource block set may be based on the SCI received within the window, and where the window corresponds to a LBT window for the first resource block set.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for measuring a received signal strength indicator (RSSI) within a measurement window associated with a first resource block set of the one or more resource block sets, where a first resource block load of the first resource block set may be based on the measured RSSI, and where the measurement window corresponds to a LBT window for the first resource block set.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a likelihood of success of a LBT procedure associated with a sidelink feedback channel for transmission via a resource block set may be inversely related to a resource block load associated with the resource block set.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, prioritizing the set of multiple sidelink feedback channels may include operations, features, means, or instructions for prioritizing the set of multiple sidelink feedback channels according to a set of multiple LBT window sizes, each LBT window size of the set of multiple LBT window sizes associated with a respective sidelink feedback channel of the set of multiple sidelink feedback channels, where a likelihood of success of a LBT procedure for a sidelink feedback channel may be inversely related to a LBT window size associated with the sidelink feedback channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a LBT window size of the set of multiple LBT window sizes for a sidelink feedback channel of the set of multiple sidelink feedback channels based on a count-down number associated with the sidelink feedback channel and a channel access priority class (CAPC) associated with the sidelink feedback channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, prioritizing the set of multiple sidelink feedback channels may include operations, features, means, or instructions for prioritizing the set of multiple sidelink feedback channels according to one or more reference LBT window sizes, each reference LBT window size of the one or more reference LBT window sizes for a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, where each sidelink feedback channel of the set of multiple sidelink feedback channels may be for transmission via a respective resource block set of the one or more resource block sets, and where the respective likelihood of success of the LBT procedure for the respective sidelink feedback channel may be inversely related to a respective reference LBT window size associated with the respective sidelink feedback channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a reference LBT window size for a resource block set of the one or more resource block sets includes a maximum window size of a set of window sizes associated with a set of sidelink feedback channels in the resource block set or a minimum window size of the set of window sizes associated with the set of sidelink feedback channels in the resource block set.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for selecting, for each resource block set of the one or more resource block sets, a respective reference CAPC value and selecting, for each resource block set of the one or more resource block sets, a respective random count-down number based on the respective reference CAPC value, where a reference LBT window size for a resource block set of the one or more resource block sets may be based on the respective reference CAPC value and the respective random count-down number selected for the resource block set.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, selecting the respective reference CAPC value may include operations, features, means, or instructions for selecting a maximum CAPC value of a set of CAPC values associated with a set of sidelink feedback channels in a respective resource block set and selecting a minimum CAPC value of the set of CAPC values associated with the set of sidelink feedback channels in the respective resource block set.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for selecting, for each resource block set of the one or more resource block sets, a respective random count-down number, where the selecting may be based on sidelink feedback channels in the resource block set being associated with a same CAPC, and where a reference LBT window size for a resource block set of the one or more resource block sets may be based on the respective random count-down number selected for the resource block set.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more LBT procedures include type-1 channel access procedures.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a set of multiple sidelink messages, where each sidelink feedback channel of the set of multiple sidelink feedback channels corresponds to a respective sidelink message of the set of multiple sidelink messages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIG. 3 illustrates an example of a feedback timing diagram that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIG. 4 illustrates an example of a process flow that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIGs. 5 and 6 illustrate block diagrams of devices that support priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIG. 7 illustrates a block diagram of a communications manager that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIG. 8 illustrates a diagram of a system including a device that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

FIGs. 9 through 12 illustrate flowcharts showing methods that support priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure.

DETAILED DESCRIPTION

In some systems, a sidelink user equipment (UE) may receive multiple sidelink message (e.g., physical sidelink shared channels (PSSCHs) ) from one or more sidelink UEs. Each sidelink message may be associated with a respective feedback symbol or slot (e.g., a physical sidelink feedback channel (PSFCH) symbol or slot) . For example, sidelink control information (SCI) that schedules a sidelink message may indicate one or more resources in a feedback symbol or slot that are allocated for feedback in response to the sidelink message. In some examples, multiple sidelink messages received by the UE may be associated with the same sidelink feedback symbol or slot, such that the UE may have multiple sidelink feedback messages for transmission in a single sidelink feedback symbol or slot (e.g., a same transmission occasion or in at least partially overlapping time resources) .

Some sidelink UEs may support up to a maximum quantity of sidelink feedback transmissions in a same feedback symbol or transmission occasion. If a quantity of the sidelink feedback messages for transmission by the UE in the same sidelink feedback symbol or slot exceeds the maximum quantity supported by the UE, the UE may not be able to transmit all of the feedback messages in the same feedback symbol or slot. In some cases, the UE may prioritize the feedback transmissions based on a type of information conveyed via the feedback transmissions, priority values assigned to the feedback transmissions, or whether the feedback transmission is within a shared channel occupancy time (COT) interval. If the UE performs a listen-before-talk (LBT) procedure before the feedback transmissions, and there is no COT sharing, the feedback transmissions may be associated with different likelihoods of success of an LBT procedure.

Techniques, systems, and devices described herein enable a UE to prioritize sidelink feedback messages for transmission within a same transmission occasion when the UE performs type-1 channel access (e.g., when there is no COT sharing) for the sidelink feedback occasion. The UE may prioritize the sidelink feedback transmissions based on one or more prioritization parameters. Each prioritization parameter may be associated with or may indicate a likelihood that an LBT procedure for a respective sidelink feedback transmission will succeed. The one or more prioritization parameters for determining the likelihood of LBT success for a respective feedback transmission may include a load of a set of resource blocks in which the feedback is transmitted, an LBT window associated with the feedback transmission, a reference LBT window for the resource block set, a random count-down number for the resource block set, or any combination thereof. The UE may calculate the prioritization parameters based on a random count-down number for the feedback transmissions, a channel access priority class (CAPC) associated with the feedback transmissions, a received signal strength indicator (RSSI) measurement (or other channel quality measurement) , SCI associated with the feedback transmissions, or any combination thereof.

In some examples, the UE may additionally prioritize the sidelink feedback transmissions based on one or more other parameters, such as sidelink priority values associated with the sidelink feedback transmissions, before or after prioritizing the sidelink feedback transmissions in accordance with the prioritization parameters. The UE may select a subset of feedback transmissions from among the multiple feedback transmissions in the overlapping time resources based on the prioritization. The UE may perform LBT procedures to access a shared radio frequency spectrum band for transmission of the selected subset of feedback transmissions. The LBT procedures may be associated with one or more COT intervals. The UE may transmit the subset of sidelink feedback transmissions during the one or more COT intervals based on the LBT procedures succeeding.

Aspects of the disclosure are initially described in the context of wireless communications systems. Additional aspects of the disclosure are described with reference to a feedback timing diagram and a process flow. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to priority handling for feedback channels in sidelink.

FIG. 1 illustrates an example of a wireless communications system 100 that supports priority handling for feedback channels in sidelink 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.

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) .

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.

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 a node. 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.

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 links 120 (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 communicate with 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.

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) .

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 more components 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) ) .

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, medium access control (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 the 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 a midhaul 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.

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.

For instance, an access network (AN) or RAN may include communications between access nodes (e.g., an IAB donor) , IAB nodes 104, and one or more UEs 115. The IAB donor may facilitate connection between the core network 130 and the AN (e.g., via a wired or wireless connection to the core network 130) . That is, an IAB donor may refer to a RAN node with a wired or wireless connection to core network 130. The IAB donor may include a CU 160 and at least one DU 165 (e.g., and RU 170) , in which case the CU 160 may communicate with the core network 130 via an interface (e.g., a backhaul link) . IAB donor and IAB nodes 104 may communicate via an F1 interface according to a protocol that defines signaling messages (e.g., an F1 AP protocol) . Additionally, or alternatively, the CU 160 may communicate with the core network via an interface, which may be an example of a portion of backhaul link, and may communicate with other CUs 160 (e.g., a CU 160 associated with an alternative IAB donor) via an Xn-C interface, which may be an example of a portion of a backhaul link.

An IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access for UEs 115, wireless self-backhauling capabilities) . A DU 165 may act as a distributed scheduling node towards child nodes associated with the IAB node 104, and the IAB-MT may act as a scheduled node towards parent nodes associated with the IAB node 104. That is, an IAB donor may be referred to as a parent node in communication with one or more child nodes (e.g., an IAB donor may relay transmissions for UEs through one or more other IAB nodes 104) . Additionally, or alternatively, an IAB node 104 may also be referred to as a parent node or a child node to other IAB nodes 104, depending on the relay chain or configuration of the AN. Therefore, the IAB-MT entity of IAB nodes 104 may provide a Uu interface for a child IAB node 104 to receive signaling from a parent IAB node 104, and the DU interface (e.g., DUs 165) may provide a Uu interface for a parent IAB node 104 to signal to a child IAB node 104 or UE 115.

For example, IAB node 104 may be referred to as a parent node that supports communications for a child IAB node, or referred to as a child IAB node associated with an IAB donor, or both. The IAB donor may include a CU 160 with a wired or wireless connection (e.g., a backhaul communication link 120) to the core network 130 and may act as parent node to IAB nodes 104. For example, the DU 165 of IAB donor may relay transmissions to UEs 115 through IAB nodes 104, or may directly signal transmissions to a UE 115, or both. The CU 160 of IAB donor may signal communication link establishment via an F1 interface to IAB nodes 104, and the IAB nodes 104 may schedule transmissions (e.g., transmissions to the UEs 115 relayed from the IAB donor) through the DUs 165. That is, data may be relayed to and from IAB nodes 104 via signaling via an NR Uu interface to MT of the IAB node 104. Communications with IAB node 104 may be scheduled by a DU 165 of IAB donor and communications with IAB node 104 may be scheduled by DU 165 of IAB node 104.

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 priority handling for feedback channels in sidelink 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) .

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 (IoT) device, an Internet of Everything (IoE) 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.

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.

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) .

In some examples, such as in a carrier aggregation configuration, a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute RF channel number (EARFCN) ) and may be identified according to a channel raster for discovery by the UEs 115. A carrier may be operated in a standalone mode, in which case initial acquisition and connection may be conducted by the UEs 115 via the carrier, or the carrier may be operated in a non-standalone mode, in which case a connection is anchored using a different carrier (e.g., of the same or a different radio access technology) .

The communication links 125 shown in the wireless communications system 100 may include downlink transmissions (e.g., forward link transmissions) from a network entity 105 to a UE 115, uplink transmissions (e.g., return link transmissions) from a UE 115 to a network entity 105, or both, among other configurations of transmissions. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode) .

A carrier may be associated with a particular bandwidth of the RF spectrum and, in some examples, the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a set of bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz) ) . Devices of the wireless communications system 100 (e.g., the network entities 105, the UEs 115, or both) may have hardware configurations that support communications using a particular carrier bandwidth or may be configurable to support communications using one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include network entities 105 or UEs 115 that support concurrent communications using carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured for operating using portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

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.

One or more numerologies for a carrier may be supported, and a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time and communications for the UE 115 may be restricted to one or more active BWPs.

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 T_s=1/ (Δf_max·N_f) seconds, for which Δf_max may represent a supported subcarrier spacing, and N_f may 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) .

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 variable quantity 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., N_f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time 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) ) .

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.

A network entity 105 may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a network entity 105 (e.g., using a carrier) and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) , or others) . In some examples, a cell also may refer to a coverage area 110 or a portion of a coverage area 110 (e.g., a sector) over which the logical communication entity operates. Such cells may range from smaller areas (e.g., a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the network entity 105. For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with coverage areas 110, among other examples.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs 115 with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered network entity 105 (e.g., a lower-powered base station 140) , as compared with a macro cell, and a small cell may operate using the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to the UEs 115 with service subscriptions with the network provider or may provide restricted access to the UEs 115 having an association with the small cell (e.g., the UEs 115 in a closed subscriber group (CSG) , the UEs 115 associated with users in a home or office) . A network entity 105 may support one or multiple cells and may also support communications via the one or more cells using one or multiple component carriers.

In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT) , enhanced mobile broadband (eMBB) ) that may provide access for different types of devices.

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.

The wireless communications system 100 may support synchronous or asynchronous operation. For synchronous operation, network entities 105 (e.g., base stations 140) may have similar frame timings, and transmissions from different network entities 105 may be approximately aligned in time. For asynchronous operation, network entities 105 may have different frame timings, and transmissions from different network entities 105 may, in some examples, not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a network entity 105 (e.g., a base station 140) without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that uses the information or presents the information to humans interacting with the application program. Some UEs 115 may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception concurrently) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for the UEs 115 include entering a power saving deep sleep mode when not engaging in active communications, operating using a limited bandwidth (e.g., according to narrowband communications) , or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a defined portion or range (e.g., set of subcarriers or resource blocks (RBs) ) within a carrier, within a guard-band of a carrier, or outside of a carrier.

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.

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 115 transmits to each of the other UEs 115 in the group. In 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.

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.

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.

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 very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may also operate using a super high frequency (SHF) region, which may be in the range of 3 GHz to 30 GHz, also known as the centimeter band, or using an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, the wireless communications system 100 may support millimeter wave (mmW) communications between the UEs 115 and the network entities 105 (e.g., base stations 140, RUs 170) , and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, such techniques may facilitate using antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

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 network 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.

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.

The network entities 105 or the UEs 115 may use MIMO communications to exploit multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry information associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords) . Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) , for which multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) , for which multiple spatial layers are transmitted to multiple devices.

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) .

A network entity 105 or a UE 115 may use beam sweeping techniques as part of beamforming operations. For example, a network entity 105 (e.g., a base station 140, an RU 170) may use multiple antennas or antenna arrays (e.g., antenna panels) to conduct beamforming operations for directional communications with a UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a network entity 105 multiple times along different directions. For example, the network entity 105 may transmit a signal according to different beamforming weight sets associated with different directions of transmission. Transmissions along different beam directions may be used to identify (e.g., by a transmitting device, such as a network entity 105, or by a receiving device, such as a UE 115) a beam direction for later transmission or reception by the network entity 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by transmitting device (e.g., a transmitting network entity 105, a transmitting UE 115) along a single beam direction (e.g., a direction associated with the receiving device, such as a receiving network entity 105 or a receiving UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based on a signal that was transmitted along one or more beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the network entity 105 along different directions and may report to the network entity 105 an indication of the signal that the UE 115 received with a highest signal quality or an otherwise acceptable signal quality.

In some examples, transmissions by a device (e.g., by a network entity 105 or a UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or beamforming to generate a combined beam for transmission (e.g., from a network entity 105 to a UE 115) . The UE 115 may report feedback that indicates precoding weights for one or more beam directions, and the feedback may correspond to a configured set of beams across a system bandwidth or one or more sub-bands. The network entity 105 may transmit a reference signal (e.g., a cell-specific reference signal (CRS) , a channel state information reference signal (CSI-RS) ) , which may be precoded or unprecoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook) . Although these techniques are described with reference to signals transmitted along one or more directions by a network entity 105 (e.g., a base station 140, an RU 170) , a UE 115 may employ similar techniques for transmitting signals multiple times along different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) or for transmitting a signal along a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115) may perform reception operations in accordance with multiple receive configurations (e.g., directional listening) when receiving various signals from a receiving device (e.g., a network entity 105) , such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may perform reception in accordance with multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive configurations or receive directions. In some examples, a receiving device may use a single receive configuration to receive along a single beam direction (e.g., when receiving a data signal) . The single receive configuration may be aligned along a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR) , or otherwise acceptable signal quality based on listening according to multiple beam directions) .

The wireless communications system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or PDCP layer may be IP-based. An RLC layer may perform packet segmentation and reassembly to communicate via logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer also may implement error detection techniques, error correction techniques, or both to support retransmissions to improve link efficiency. In the control plane, an RRC layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a network entity 105 or a core network 130 supporting radio bearers for user plane data. A PHY layer may map transport channels to physical channels.

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.

A UE 115 may transmit sidelink feedback via a PSFCH in response to one or more sidelink messages received via PSSCH resources. The sidelink messages may be transmitted via one or more slots and corresponding resource block sets each associated with (e.g., mapped to) a same PSFCH symbol. As such, the UE 115 may be scheduled to transmit multiple feedback messages via a same PSFCH symbol (e.g., at least partially overlapping time resources) .

The UE 115 may calculate a transmission power for transmitting a feedback message based on an initial transmit power parameter (e.g., dl-P0-PSFCH) received via a control message. If the UE 115 receives the initial transmit power parameter, the UE 115 may calculate the transmission power for PSFCH based on Equation 1.
P_PSFCH, _one=P_O, _PSFCH+10log₁₀ (2^μ) +α_PSFCH·Pl [dBm] (1)

In the example of Equation 1, P_O, _PSFCH may be a value of the initial transmit power parameter, dl-P0-PSFCH, α_PSFCH may be a value of a second PSFCH parameter (e.g., dl-Alpha-PSFCH) , if the second PSFCH parameter is provided or indicated via control signaling; else, α_PFSCH may be equal to one. Further, PL=PL_b, _f, _c (q_d) when the active sidelink bandwidth part (BWP) is on a serving cell c, except that the reference signal resource may be one the UE 115 uses for determining a power of a physical uplink shared channel (PUSCH) transmission scheduled by a downlink control information (DCI) (e.g., DCI format 0_0) in serving cell c when the UE 115 is configured to monitor a physical downlink control channel (PDCCH) for detection of DCI (e.g., DCI format 0_0) in serving cell c, and the reference signal resource is one corresponding to the synchronization signal or physical broadcast channel (PBCH) the UE 115 may use to obtain a master information block (MIB) when the UE 115 is not configured to monitor PDCCH for detection of DCI (e.g., DCI format 0_0) in serving cell c.

A UE 115 may be capable of transmitting up to a threshold or maximum quantity of feedback transmissions in a same feedback transmission occasion (e.g., up to N_max, _PSFCH simultaneous PSFCH transmissions in a PSFCH transmission occasion) . In some cases, the UE 115 may be scheduled to transmit a first quantity (N_sch, _Tx, _PSFCH) of feedback transmissions in a given feedback transmission occasion (e.g., based on the UE 115 receiving that quantity of sidelink messages) . The UE 115 may select a second quantity (N_Tx, _PSFCH) of feedback transmissions for transmission with ascending order of priority in a feedback transmission occasion based on one or more protocols or rules.

For example, in a first case (Case 1) , if the first quantity of feedback transmissions is less than or equal to the maximum quantity of feedback transmissions (e.g., N_sch, _Tx, _PSFCH≤N_max, _PSFCH) and the initial transmit power parameter, dl-P0-PSFCH, is configured, the UE 115 may select feedback transmissions based on a total transmission power of the first quantity of scheduled feedback transmissions. If the total transmission power of N_sch, _Tx, _PSFCH feedback transmissions is equal to or less than a maximum transmission power, P_CMAX (e.g., P_PSFCH, _one+10log₁₀ (N_sch, _Tx, _PSFCH) ≤P_CMAX) , the UE 115 may select all of the scheduled feedback transmissions (e.g., N_Tx, _PSFCH= N_sch, _Tx, _PSFCH) and the transmit power for each feedback transmission, P_PSFCH, _k (i) , may be determined according to Equation 1 (e.g., P_PSFCH, _k (i) = P_PSFCH, _one [dBm] ) . Otherwise, if the total transmission power of N_sch, _Tx, _PSFCH feedback transmissions is greater than the maximum transmission power, P_CMAX (e.g., P_PSFCH, _one+10log₁₀ (N_sch, _Tx, _PSFCH) ＞P_CMAX) , the UE 115 may autonomously determine the second quantity, N_Tx, _PSFCH, of feedback transmissions with ascending order of corresponding priority field values over the feedback transmissions with HARQ-ACK information, if any, and then with ascending order of priority value over the feedback transmissions with conflict information, if any, such that where M_i, for 1≤i≤ 8, may represent a quantity of PSFCHs with priority value i for PSFCH with HARQ-ACK information and M_i, for i＞8, may represent a quantity of PSFCHs with priority value i-8 for PSFCH with conflict information and K may be defined as a largest value satisfying Equation 2 for transmission of all PSFCHs inif any, and zero, otherwise.

In a second case (Case 2) , if the first quantity of feedback transmissions is greater than the maximum quantity of feedback transmissions (e.g., N_sch, _Tx, _PSFCH＞N_max, _PSFCH) and the initial transmit power parameter, dl-P0-PSFCH, is configured, the UE 115 may select the maximum quantity, N_max, _PSFCH, of feedback transmissions first in ascending order of corresponding priority field values over the feedback transmissions with HARQ-ACK information, if any, and then with ascending order of priority values over the feedback transmissions with conflict information, if any. If the total transmission power of N_max, _PSFCH feedback transmissions is equal to or less than a maximum transmission power, P_CMAX (e.g., P_PSFCH, _one+10log₁₀ (N_max, _PSFCH) ≤ P_CMAX) , the UE 115 may select up to the maximum quantity of the scheduled feedback transmissions (e.g., N_Tx, _PSFCH= N_max, _PSFCH) and the transmit power for each feedback transmission, P_PSFCH, _k (i) , may be determined according to Equation 1 (e.g., P_PSFCH, _k (i) =P_PSFCH, _one [dBm] ) . Otherwise, if the total transmission power of N_max, _PSFCH feedback transmissions is greater than the maximum transmission power, P_CMAX (e.g., P_PSFCH, _one+10log₁₀ (N_max, _PSFCH) ＞P_CMAX) , the UE 115 may autonomously select the second quantity, N_Tx, _PSFCH, of feedback transmissions in ascending order of corresponding priority field values over the feedback transmissions with HARQ-ACK information, if any, and then with ascending order of priority value over the feedback transmissions with conflict information, if any, such that where M_i, for 1≤i≤ 8, may represent a quantity of PSFCHs with priority value i for PSFCH with HARQ-ACK information and M_i, for i＞8, may represent a quantity of PSFCHs with priority value i-8 for PSFCH with conflict information and K may be defined as a largest value satisfying Equation 2 for transmission of all PSFCHs inif any, and zero, otherwise.

In a third case (Case 3) , if the initial transmit power parameter, dl-P0-PSFCH, is not configured, the UE 115 may autonomously determine a quantity, N_Tx, _PSFCH, of feedback transmissions with ascending order of corresponding priority field values over the feedback transmissions with HARQ-ACK information, if any, and then with ascending order of priority values over the feedback transmissions with conflict information, if any, such that N_Tx, _PSFCH≥1. A maximum transmission power, P_CMAX, may be determined for the quantity of feedback transmissions.

In some examples, the wireless communications system 100 may support sidelink communications via an unlicensed band. In such cases, a sidelink UE 115 may perform LBT before PSFCH transmission. The likelihood of the LBT procedure succeeding may be related to one or more factors including, for example, whether the PSFCH is in a shared COT or out-COT. If COT sharing is not supported or used, the likelihood of LBT success may be related to a random count-down number for the PSFCH, a CAPC for the PSFCH, a load of a resource block set that includes the PSFCH, or any combination thereof.

Techniques described herein provide for a sidelink UE 115 to select which sidelink feedback channels to transmit in a given transmission occasion based on a prioritization of the sidelink feedback channels. The UE 115 may have multiple sidelink feedback channels for transmission in at least partially overlapping time resources (e.g., in a same symbol or a same set of symbols) . The UE 115 may prioritize the feedback channels according to a set of prioritization parameters, where each prioritization parameter may be associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel. The UE 115 may select a subset of the sidelink feedback channels based on the prioritization. The UE 115 may perform one or more LBT procedures for the selected subset of sidelink feedback channels. The LBT procedures may be, for example, type-1 channel access procedures (e.g., Cat4 LBT) , or some other type of channel access procedure to gain access to a shared radio frequency spectrum band for transmission of the subset of sidelink communications. The UE 115 may transmit the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the LBT procedures and selecting the subset of sidelink feedback channels.

FIG. 2 illustrates an example of a wireless communications system 200 that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure. The wireless communications system 200 may include multiple UEs 115 (e.g., UEs 115-a, 115-b, 115-c, and 115-d, among other UEs 115) , which may each represent an example of a UE 115 as described with reference to FIG. 1. The UEs 115 may communicate within geographic coverage area 110-a and via sidelink communication links 210 (e.g., 210-a, 210-b, and 210-c) . In some examples, one or more of the UEs 115 in the wireless communications system 200 may be configured with a sidelink PSFCH prioritization protocol 220 for prioritizing sidelink feedback transmissions.

The UEs 115 may perform sidelink communications using mode 1 sidelink resource allocation or mode 2 sidelink resource allocation. For example, if the UE 115-a has data to transmit, the UE 115-a may autonomously perform sensing and resource selection to select resources for transmission of the message (e.g., mode 2) . Alternatively, in some examples, the UE 115-a may receive control signaling from a network entity 105 (not shown in FIG. 2) that may allocate sidelink resources for the transmission by the UE 115-a.

The UE 115-a may receive sidelink messages 225 from multiple other sidelink UEs 115 (e.g., UEs 115-b, 115-c, and 115-d) . The sidelink messages 225 may be received via PSSCH resources via the respective sidelink communication links 210. In some examples, the sidelink messages 225 may be associated with a same set of time resources allocated for feedback transmissions (e.g., a same PSFCH occasion) , such that the UE 115-a may transmit sidelink feedback messages 230 (e.g., PSFCHs) for each of the sidelink messages 225 in a same transmission occasion (e.g., via at least partially overlapping time resources) . If a quantity of sidelink feedback messages 230 for transmission in a single transmission occasion exceeds a threshold quantity supported by the UE 115-a, the UE 115-a may select a subset of the sidelink feedback messages 230 to transmit. The UE 115-a may select the subset of the sidelink feedback messages 230 to include a quantity of sidelink feedback messages 230 that is equal to or less than the threshold quantity (e.g., N_sch, _Tx, _PSFCH≤N_max, _PSFCH) . In some cases, the UE 115-a may select the subset of sidelink feedback messages 230 based on feedback priority values assigned to the sidelink feedback messages 230, contents of the sidelink feedback messages 230 transmission power of the sidelink messages 230, or any combination thereof, as described with reference to FIG. 1.

For example, each sidelink message 225 may be scheduled via SCI, and the SCI may indicate a sidelink priority value for the sidelink message 225 and a corresponding sidelink feedback message 230. The UE 115-a may sort the sidelink feedback messages 230 in order of priority values by first ordering sidelink feedback messages 230 that include HARQ-ACK information, if any of the sidelink feedback messages 230 include HARQ-ACK information, and subsequently ordering sidelink feedback messages 230 that include conflict information, if any of the sidelink feedback messages 230 include conflict information. That is, the UE 115-a may sort or order the sidelink feedback messages 230 in ascending order of priority values for a given type of information carried by the sidelink feedback messages 230. The UE 115-a may select the subset of sidelink feedback messages 230 for transmission based on the order (e.g., the UE 115-a may select the highest sidelink feedback messages 230 in an ordered list) .

In the wireless communications system 200, the UEs 115-a, 115-b, 115-c, and 115-d may perform sidelink communications via an unlicensed band (e.g., a shared RF spectrum band, a contention-based spectrum band or channel) . In such cases, a UE 115 may perform LBT before transmitting a sidelink feedback message 230. If the UEs 115 support COT sharing, the UEs 115 may perform one or more different types of LBT procedures to gain access to the shared COT. The different LBT types may be associated with different likelihoods of LBT success, and the LBT type that is performed may be based on whether the corresponding PSFCH is in-COT or out-COT. In some cases, if COT sharing is supported and used, a UE 115 may order or prioritize sidelink transmissions based on in-COT and out-COT information associated with the transmissions. However, for out-COT or in cases where no COT sharing is used, type-1 channel access procedures may be performed, and the likelihood of LBT success may impact resource utilization. In such cases, it may be beneficial to consider the likelihood of LBT success when defining the PSFCH priority.

Techniques, systems, and devices described herein provide for a protocol, such as the sidelink PSFCH prioritization protocol 220, for a UE 115 to prioritize PSFCHs based, at least partially, on likelihood of LBT success. The sidelink PSFCH prioritization protocol 220 may be configured at the UE 115 or indicated via control signaling. The sidelink PSFCH prioritization protocol 220 may be used by a UE 115 based on one or more parameters or conditions. For example, the UE 115-a may use the sidelink PSFCH prioritization protocol 220 if the UE 115-a has more than a threshold quantity of sidelink feedback messages 230 for transmission in a same PSFCH occasion and the UE 115-a does not support or use COT sharing (e.g., the UE 115-a performs CAT-4 LBT for accessing the PSFCH resource) .

In accordance with the sidelink PSFCH prioritization protocol 220, the UE 115-a may prioritize the sidelink feedback messages 230 (also referred to as PSFCHs, sidelink feedback channels, or sidelink feedback transmissions herein) based on one or more prioritization parameters. Each prioritization parameter may be associated with or may indicate a likelihood that an LBT procedure for a respective sidelink feedback message 230 will succeed. The one or more prioritization parameters for determining the likelihood of LBT success for a respective feedback transmission may include a load of a set of resource blocks in which the feedback is transmitted, an LBT window associated with the feedback transmission, a reference LBT window for the resource block set, a random count-down number for the resource block set, or any combination thereof. The UE 115-a may calculate the prioritization parameters based on a random count-down number for the feedback transmissions, a CAPC associated with the feedback transmissions, an RSSI measurement, SCI associated with the feedback transmissions, or any combination thereof, as described in further detail elsewhere herein, including with reference to FIG. 3.

In some examples, the UE 115-a may additionally prioritize the sidelink feedback messages 230 based on one or more other parameters, such as sidelink priority values associated with the sidelink feedback messages 230, before or after prioritizing the sidelink feedback messages 230 in accordance with the prioritization parameters. The UE 115-a may select a subset of feedback messages 230 from among the multiple feedback messages 230 in the overlapping time resources based on the prioritization. The UE 115-a may perform LBT procedures to access a shared radio frequency spectrum band for transmission of the selected subset of sidelink feedback messages 230. The LBT procedures may be associated with one or more COT intervals. The UE 115-a may transmit the subset of sidelink feedback messages 230 during the one or more COT intervals based on the LBT procedures succeeding.

In the example of FIG. 2, the UE 115-a may receive sidelink messages 225 from each of the UEs 115-b, 115-c, and 115-d, and each of the sidelink messages 225 may be associated with a same PSFCH symbol. The UE 115-a may be capable of supporting up to two sidelink feedback transmissions in a same transmission occasion. As such, the UE 115-a may prioritize the sidelink feedback messages 230 in accordance with the sidelink PSFCH prioritization protocol 220, and the UE 115-a may select the top two sidelink feedback messages 230 based on the prioritization. The UE 115-a may perform LBT for the selected two sidelink feedback messages 230 and transmit the messages accordingly.

The described techniques may thereby enable a UE 115 to account for likelihood of LBT success when selecting a subset of sidelink feedback messages 230 for transmission. By accounting for likelihood of LBT success, the UE 115 may reduce a probability that an LBT procedure for a selected sidelink feedback message 230 will fail, which may improve throughput, communication reliability, and coordination between sidelink devices.

FIG. 3 illustrates an example of a feedback timing diagram 300 that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure. In some examples, the feedback timing diagram 300 may implement or be implemented by aspects of the wireless communications systems 100 and 200 as described with reference to FIGs. 1 and 2. For example, the feedback timing diagram 300 illustrates a configuration of time and frequency resources allocated for sidelink messages and corresponding feedback transmissions by one or more sidelink UEs, which may represent examples of a UE 115, as described with reference to FIGs. 1 and 2. In this example, a sidelink UE may have multiple PSFCHs 340 for transmission in a same transmission occasion (e.g., a same PSFCH symbol 330-b) , and the UE may be configured with a PSFCH prioritization protocol for selecting a subset of the PSFCHs 340 for transmission based on a likelihood of LBT for the PSFCHs 340 succeeding, based on a priority value assigned to the PSFCHs 340, or both.

The feedback timing diagram 300 illustrates a set of slots 335 in a time domain and resource blocks in a frequency domain. The resource blocks may be organized or grouped into one or more resource block sets 305-a and 305-b (e.g., RB set #1 and RB set #2) . A resource block set 305 may represent a frequency band or subband that includes one or more resource blocks. The time and frequency resources in the feedback timing diagram 300 may be allocated as PSSCH resources 310, PSCCH resources 315, PSFCH resources 320, or some other type of resources. In the example of FIG. 3, a sidelink UE (e.g., UE0) may receive sidelink messages 325 from one or more other UEs (e.g., UE1 through UE6) via the PSSCH resources 310. The sidelink messages 325 may be received via respective symbols and slots 335 in the time domain and resource blocks in the frequency domain. In some examples, the sidelink messages 325 may be received via or associated with a resource block set 305. For example, the UE may receive a sidelink message 325-d from a UE4 and a sidelink message 325-e from a UE5 via slots 335 in the resource block set 305-a. The UE may receive a sidelink message 325-a from a UE1, a sidelink message 325-b from a UE2, a sidelink message 325-d from a UE3, and a sidelink message 325-f from a UE6 in respective slots 335 of the resource block set 305-b. Each sidelink message 325 illustrated in FIG. 3 may be labeled by a source UE or node that transmits the sidelink message 325. A target UE or node of each of the illustrated sidelink messages 325 may be the UE0, in this example (e.g., the UE0 may receive each of the sidelink messages 325-a through 325-f) .

The sidelink messages 325 may be associated with or may include SCI, which may be received via the PSCCH resources 315. In some examples, the PSCCH resources 315 illustrated in FIG. 3 may convey SCI-2 associated with the sidelink messages 325, and SCI-1 may be transmitted via other PSCCH resources not pictured in FIG. 3. Additionally, or alternatively, the PSCCH resources 315 may convey SCI-1, SCI-2, or both. The SCI may indicate one or more parameters associated with the sidelink messages 325. For example, the SCI for the sidelink message 325-a may indicate the time and frequency resources allocated for the sidelink message 325-a, a sidelink feedback priority value of the sidelink message 325-a, a CAPC of the sidelink message 325-a, one or more time and frequency resources allocated for a feedback message (e.g., the PSFCH 340-a) in response to the sidelink message 325-a, or any combination thereof.

One or more PSFCH symbols 330 may be allocated for sidelink feedback transmissions across the slots 335. In the example of FIG. 3, the PSFCH symbol 330-a may be associated with sidelink messages 325 received via a first set of slots 335, and the PSFCH symbol 330-b may be associated with the sidelink messages 325-a through 325-f received via a second set of slots 335 that are between the PSFCH symbol 330-a and the PSFCH symbol 330-b in time. That is, sidelink feedback for each of the sidelink messages 325-a through 325-f may be transmitted via the PSFCH symbol 330-b, which may be referred to as a transmission occasion in some examples herein. The PSFCH symbol 330-b may represent a set of time and frequency resources allocated across resource blocks of the resource block set 305-a and the resource block set 305-b. Although illustrated as a single symbol, it is to be understood that, in some examples, the PSFCH symbol 330-b may represent a set of symbols or a slot and may include a respective symbol in each resource block.

The UE (e.g., UE0) may determine a respective set of frequency PSFCH resources 320 within the PSFCH symbol 330-b that are used for feedback in response to the sidelink message 325 based on some mapping rule. The mapping rule may be defined (e.g., predefined or configured at the UE) for mapping sidelink messages 325 to PSFCH resources 320. For example, the UE may determine that the PSFCH 340-a (e.g., PSFCH1) is used for a sidelink feedback transmission in response to the sidelink message 325-a. Similarly, the UE may determine that the PSFCH 340-b (e.g., PSFCH2) may be used for a feedback transmission responsive to the sidelink message 325-b from the UE2, the PSFCH 340-c (e.g., PSFCH3) may be used for a feedback transmission responsive to the sidelink message 325-c from the UE3, the PSFCH 340-d (e.g., PSFCH4) may be used for a feedback transmission responsive to the sidelink message 325-d from the UE4, the PSFCH 340-e (e.g., PSFCH5) may be used for a feedback transmission responsive to the sidelink message 325-e from the UE5, and the PSFCH 340-f (e.g., PSFCH6) may be used for a feedback transmission responsive to the sidelink message 325-f from the UE6.

The UE in this example may thereby have multiple sidelink feedback transmissions (e.g., PSFCHs 340-a through 340-f) for transmission via different frequency resources and at least partially overlapping time resources within a same PSFCH symbol 330-b or transmission occasion. As described with reference to FIGs. 1 and 2, the UE may support no more than a maximum quantity of PSFCH transmissions at a same time. In this example, the maximum quantity may be less than six, such that the UE may not be able to transmit all of the PSFCHs 340-a through 340-f in the PSFCH symbol 330-b. The UE may not support or utilize a shared COT. Accordingly, the UE may perform a type-1 channel access procedure (e.g., category 4 LBT) prior to transmitting any feedback via the PSFCH symbol 330-b.

Techniques, systems, and devices described herein provide for the UE to prioritize the PSFCHs 340 based at least in part on a likelihood of the LBT procedures for the PSFCHs 340 succeeding. The UE may select a subset of the PSFCHs 340 for transmission via the PSFCH symbol 330-b based on the prioritization. The UE may thereby account for a probability of LBT success when performing feedback transmissions, which may improve throughput and reliability of the sidelink communications. The UE may utilize a sidelink feedback prioritization protocol to prioritize the PSFCHs 340, such as the sidelink PSFCH prioritization protocol 220 described with reference to FIG. 2. The sidelink feedback prioritization protocol may instruct the UE to perform prioritization of the PSFCHs 340 based on a likelihood of LBT success for each PSFCH 340, based on a priority value associated with each PSFCH 340, or both.

The likelihood of LBT success may be defined based on one or more prioritization parameters associated with the PSFCH 340, with a resource block set 305 that includes the PSFCH 340, or both, because the LBT may be performed per subband or per resource block set 305. In some examples, the UE may determine (e.g., calculate, estimate, or predict) the likelihood of LBT success for each PSFCH 340 based on a load of a resource block set 305 where the PSFCH 340 is located. The load may be a parameter or value that represents an amount of usage of the resource block set 305. The likelihood of LBT success may be inversely related to the load of a corresponding resource block set 305. For example, a higher load of a resource block set 305 may correspond to a lower likelihood of LBT success.

The UE may determine (e.g., measure, calculate, or estimate) the load of a resource block set 305 based on an RSSI measurement or SCI detection. For example, the UE may measure an RSSI within a measurement window associated with a resource block set 305. A duration of the measurement window may be determined based on an LBT window for the resource block set 305. The UE may determine the load of the resource block set 305 based on the RSSI measurement. Additionally, or alternatively, the UE may detect one or more SCI associated with a resource block set 305 within a window associated with a resource block set 305, and the UE may determine the load of the resource block set 305 based on the detected SCI within the window. The window may be determined based on an LBT window for the resource block set 305.

If the prioritization parameters for prioritizing PSFCHs 340 based on likelihood of LBT success include the load of the resource block set 305, PSFCHs 340 that are within a same resource block set 305 may be associated with a same likelihood of LBT success and therefor a same prioritization, but PSFCHs 340 across different resource block sets 305 may be associated with different priorities. For example, the PSFCH 340-d and the PSFCH 340-e may be for transmission in the resource block set 305-a in response to sidelink messages 325-d and 325-e. The PSFCH 340-a, the PSFCH 340-b, the PSFCH 340-c, and the PSFCH 340-f may be for transmission in the resource block set 305-b in response to sidelink messages 325-a, 325-b, 325-c, and 325-f. Accordingly, in this example, the PSFCH 340-d may be associated with a first likelihood of LBT success that is the same as the PSFCH 340-e, and the PSFCHs 340-a, 340-b, 340-c, and 340-f may each be associated with a second likelihood of LBT success. The resource block set 305-a may be associated with a lower load than the resource block set 305-b. Accordingly, the PSFCHs 340-d and 340-e may be prioritized over the PSFCHs 340-a, 340-b, 340-c, and 340-f in a prioritization order (e.g., the prioritization order may be PSFCH1=PSFCH2=PSFCH3=PSFCH6 ＜PSFCH4=PSFCH5) .

In some examples, the UE may determine (e.g., calculate, estimate, or predict) the likelihood of LBT success for each PSFCH 340 based on an LBT window size for each PSFCH 340. The LBT window size may be based on a random count-down number associated with the PSFCH 340 and a CAPC associated with the PSFCH 340. The CAPC value for a PSFCH 340 may be based on a CAPC value of an associated sidelink message 325 received via PSSCH resources 310. For example, SCI that schedules a sidelink message 325 may indicate the CAPC for the sidelink message 325 and a corresponding PSFCH 340. The UE may select the random count-down number for each PSFCH 340. The UE may determine or calculate an LBT window size for each PSFCH 340 in accordance with Equation 3, or some other equation for LBT window size calculation.
LBT Window Size=16+m_p*9+N*9 (3)

In the Example of Equation 3, m_p may be associated with the CAPC value of the PSFCH 340 having index p, and N may represent the random count-down number for the PSFCH 340. The other numbers in Equation 3 may be constant values. In some examples, the value of nine may be based on a granularity of a sensing slot (e.g., a 9 microsecond granularity) . It is understood that the values shown in Equation 3 are examples, and any other constant values may be used in the equation for calculating LBT window size. The LBT window size may be in units of microseconds or some other unit of time.

The UE may prioritize the PSFCHs 340 based on the LBT window sizes calculated for each PSFCH. The likelihood of LBT success may be inversely related to the LBT window size. For example, a larger LBT window may correspond to a lower likelihood of LBT success. Accordingly, the UE may prioritize PSFCHs 340 in ascending order of LBT window sizes. That is, the UE may prioritize PSFCHs 340 that are associated with smaller LBT windows over PSFCHs 340 that are associated with larger window sizes.

Table 1 includes example parameters for the sidelink messages 325-a through 325-f and corresponding PSFCHs 340-a through 340-f illustrated in FIG. 3. The parameters may be indexed by PSSCH source nodes, which may represent the source UE that transmits the sidelink messages 325, as labeled in FIG. 3. For example, sidelink message 325-a may be associated with source node UE1, sidelink message 325-b may be associated with source node UE2, and so on.

Table 1–Example PSFCH Parameters

Table 1 includes the CAPC value and random count-down number for each PSFCH 340 and the LBT window sizes for each PSFCH 340-a through 340-f, which are calculated based on Equation 3. In this example, the PSFCHs 340-a and 340-f (e.g., PSFCH1 and PSFCH6) may be associated with a largest LBT window size of 106, and the PSFCHs 340-b and 340-c (e.g., PSFCH2 and PSFCH3) may be associated with the smallest window size of 61. The UE may prioritize the PSFCHs 340-a through 340-f based on the calculated LBT window sizes, and the order of prioritization may be PSFCH6=PSFCH1＜PSFCH5＜PSFCH4＜PSFCH3=PSFCH2. That is, the PSFCHs 340-b and 340-c may be associated with a higher priority than all other PSFCHs 340 based on the LBT window size of the PSFCHs 340-b and 340-c being the smallest, which may indicate the PSFCHs 340-b and 340-c are associated with highest likelihoods of LBT success.

In some examples, the UE may determine (e.g., calculate, estimate, or predict) the likelihood of LBT success for each PSFCH 340 based on a reference LBT window size for a resource block set 305 where the PSFCH 340 is located. The reference LBT window size for each resource block set 305 may be a maximum LBT window size or a minimum LBT window size of all LBT window sizes for all PSFCHs 340 included in the resource block set 305. If the prioritization parameters for prioritizing PSFCHs 340 based on likelihood of LBT success include the reference LBT window size for the resource block set 305, PSFCHs 340 that are within a same resource block set 305 may be associated with a same likelihood of LBT success and therefor a same prioritization, but PSFCHs 340 across different resource block sets 305 may be associated with different priorities.

If the reference LBT window size is the minimum LBT window size (e.g., corresponding to a PSFCH 340 with a smallest CAPC value of all the PSFCHs 340 in the resource block set 305) , the resource block set 305-a may be associated with a reference LBT window size of 61 and the resource block set 305-b may be associated with a reference LBT window size of 79. For example, the resource block set 305-a may include the PSFCHs 340-d and 340-e. As shown in Table 1, the PSFCH 340-d is associated with a smaller LBT window size (79) than the LBT window size of the PSFCH 340-e (88) . Thus, the reference LBT window size for the resource block set 305-a may be 79. The resource block set 305-b may include the PSFCHs 340-a, 340-b, 340-c, and 340-f. As shown in Table 1, the PSFCHs 340-b and 340-c are associated with a smallest LBT window size (61) of all of the PSFCHs 340-a, 340-b, 340-c, and 340-f. Thus, the reference LBT window size for the resource block set 305-b may be 61. The UE may prioritize the PSFCHs 340-a through 340-f based on the reference LBT window sizes for the respective resource block sets 305. In this example, the order of prioritization may be PSFCH4=PSFCH5 ＜ PSFCH1=PSFCH2=PSFCH3=PSFCH6. That is, the PSFCHs 340 of the resource block set 305-b may be associated with a higher priority than the PSFCHs 340 of the resource block set 305-a based on the reference LBT window size for the resource block set 305-b being smaller than the reference LBT window size for the resource block set 305-a, which may indicate the PSFCHs 340 in the resource block set 305-b are associated with highest likelihoods of LBT success.

If the reference LBT window size is the maximum LBT window size (e.g., corresponding to a PSFCH 340 with a largest CAPC value of all the PSFCHs 340 in the resource block set 305) , the resource block set 305-a may be associated with a reference LBT window size of 88 and the resource block set 305-b may be associated with a reference LBT window size of 106. For example, the resource block set 305-a may include the PSFCHs 340-d and 340-e. As shown in Table 1, the PSFCH 340-e is associated with a larger LBT window size (88) than the LBT window size of the PSFCH 340-d (79) . Thus, the reference LBT window size for the resource block set 305-a may be 88. The resource block set 305-b may include the PSFCHs 340-a, 340-b, 340-c, and 340-f. As shown in Table 1, the PSFCHs 340-a and 340-f are associated with a largest LBT window size (106) of all of the PSFCHs 340-a, 340-b, 340-c, and 340-f. Thus, the reference LBT window size for the resource block set 305-b may be 106. The UE may prioritize the PSFCHs 340-a through 340-f based on the reference LBT window sizes for the respective resource block sets 305. In this example, the order of prioritization may be PSFCH1=PSFCH2=PSFCH3=PSFCH6 ＜ PSFCH4=PSFCH5. That is, the PSFCHs 340 of the resource block set 305-a may be associated with a higher priority than the PSFCHs 340 of the resource block set 305-b based on the reference LBT window size for the resource block set 305-a being smaller than the reference LBT window size for the resource block set 305-b, which may indicate the PSFCHs 340 in the resource block set 305-a are associated with highest likelihoods of LBT success.

In some examples, the UE may determine (e.g., calculate, estimate, or predict) the likelihood of LBT success for each PSFCH 340 based on an LBT window size for a resource block set 305 where the PSFCH 340 is located. The LBT window size may be a reference LBT window size for the resource block set 305, but, in this example, the reference LBT window size may be determined based on a reference CAPC value for the resource block set 305 and a random count-down number selected based on the reference CAPC value. For each resource block set 305, the UE may select a reference CAPC value. The reference CAPC value may be a maximum CAPC value from among a set of CAPC values for PSFCHs 340 in the resource block set 305 or a minimum CPAC value from among the set of CAPC values. Additionally, or alternatively, the reference CAPC value may be a defined or configured CAPC value for each resource block set 305. If the prioritization parameters for prioritizing PSFCHs 340 based on likelihood of LBT success include the reference LBT window size for the resource block set 305 based on the reference CAPC, PSFCHs 340 that are within a same resource block set 305 may be associated with a same likelihood of LBT success and therefor a same prioritization, but PSFCHs 340 across different resource block sets 305 may be associated with different priorities.

In the example of FIG. 3, if the reference CAPC value is a minimum CAPC value for each resource block set, the UE may select a reference CAPC value of one for both the resource block set 305-a and the resource block set 305-b. The UE may select a first random count-down number for the resource block set 305-a based on the reference CAPC value. The first random count-down number may be three, in this example (e.g., N=3) . The UE may select a second random count-down number for the resource block set 305-b based on the reference CAPC value. The second random count-down number may be five, in this example (e.g., N=5) . The random count-down numbers selected for each resource block set 305 may be different than the random count-down numbers for each PSFCH 340 shown in Table 1. The UE may calculate a reference LBT window size for the resource block set 305-a based on the reference CAPC value and the selected random count-down number. In this example, the value of m_p for a CAPC value of one may be two (e.g., assuming m_p=2 is used for CAPC value of 1) , and the reference LBT window size for the resource block set 305-a may be 61 (e.g., 16+2*9+3*9=61) . The UE may calculate a reference LBT window size for the resource block set 305-b based on the reference CAPC value and the selected random count-down number. Assuming m_p=2 is used for CAPC value of 1, the reference LBT window size for the resource block set 305-b may be 79 (e.g., 16+2*9+5*9=79) . The UE may prioritize the PSFCHs 340-a through 340-f based on the reference LBT window sizes for the respective resource block sets 305. In this example, the order of prioritization may be PSFCH1=PSFCH2=PSFCH3=PSFCH6 ＜ PSFCH4=PSFCH5. That is, the PSFCHs 340 of the resource block set 305-a may be associated with a higher priority than the PSFCHs 340 of the resource block set 305-b based on the reference LBT window size for the resource block set 305-a being smaller than the reference LBT window size for the resource block set 305-b, which may indicate the PSFCHs 340 in the resource block set 305-a are associated with highest likelihoods of LBT success.

In some examples, a CAPC value may be fixed or constant across PSFCH transmissions based on a type of the PSFCH (e.g., a control channel, or some other channel type associated with a fixed CAPC) and may not be indicated via SCI, as described with reference to Table 1. In such cases, the UE may determine or select a single random count-down number for each resource block set 305 based on the fixed CAPC value (e.g., p=1) . Accordingly, m_p may be equal to one for p=1. In this example, the UE may determine (e.g., calculate, estimate, or predict) the likelihood of LBT success for each PSFCH 340 based on a reference LBT window size for a resource block set 305 where the PSFCH 340 is located, where the reference LBT window size may be determined based on the random count-down number selected for each resource block set 305.

In the example of FIG. 3, a first random count-down number selected for the first resource block set 305-a may be five (e.g., N=5) . A second random count-down number selected for the second resource block set 305-b may be three, in this example (e.g., N=3) . The UE may select the first and second random count-down numbers based on the fixed CAPC value, which may be one, in this example. The random count-down numbers selected for each resource block set 305 may be different than the random count-down numbers for each PSFCH 340 shown in Table 1. The UE may calculate a reference LBT window size for the resource block set 305-a based on the fixed CAPC value and the selected random count-down number. The reference LBT window size for the resource block set 305-a may be 79 (e.g., 16+2*9+5*9=79) . The UE may calculate a reference LBT window size for the resource block set 305-b based on the fixed CAPC value and the selected random count-down number. The reference LBT window size for the resource block set 305-b may be 61 (e.g., 16+2*9+3*9=61) . The UE may prioritize the PSFCHs 340-a through 340-f based on the reference LBT window sizes for the respective resource block sets 305. In this example, the order of prioritization may be PSFCH4=PSFCH5 ＜ PSFCH1=PSFCH2=PSFCH3=PSFCH6. That is, the PSFCHs 340 of the resource block set 305-b may be associated with a higher priority than the PSFCHs 340 of the resource block set 305-a based on the reference LBT window size for the resource block set 305-b being smaller than the reference LBT window size for the resource block set 305-a, which may indicate the PSFCHs 340 in the resource block set 305-b are associated with highest likelihoods of LBT success.

The UE may thereby utilize one or more parameters associated with the PSFCHs 340, the resource block sets 305, or both to prioritize or order the PSFCHs 340 in ascending order from least likely to succeed LBT to most likely to succeed LBT. The UE may utilize any combination of the described parameters to perform the PSFCH prioritization. For example, the UE may prioritize the PSFCHs 340 based on both the load of the resource block sets 305 and the LBT window sizes associated with the PSFCH 340, or based on both the load of the resource block sets 305 and a reference LBT window size for the resource block sets 305, or any combination of the described prioritization parameters.

The UE may additionally or alternatively prioritize the PSFCHs 340 based on one or more other parameters different than the prioritization parameters. For example, the UE may prioritize the PSFCHs 340 based on a sidelink priority value of each PSFCH 340, based on a type of information conveyed via the PSFCH 340, based on one or more other parameters, or any combination thereof. The sidelink priority value for each PSFCH 340 may be based on a sidelink message 325 associated with the PSFCH. For example, the SCI that schedules a sidelink message 325 may indicate a sidelink priority value for the sidelink message 325. The SCI may additionally schedule the PSFCH 340, and the sidelink priority value may be based on the priority value indicated via the SCI. Example sidelink priority values (e.g., values of one through eight) for the sidelink messages 325-a through 325-f and corresponding PSFCHs 340-a through 340-f are shown in Table 1. The sidelink priority values may indicate increasing priority in descending order. For example, the sidelink priority value of one may represent a highest priority value and may be prioritized over a sidelink priority value of three, for example.

In some examples, the sidelink PSFCH prioritization protocol may indicate that the UE is to determine PSFCH priority based on the likelihood of LBT success (e.g., the prioritization parameters) first, and then based on the sidelink priority value associated with each PSFCH 340 having a same LBT success rate. For example, if, after the UE prioritizes the PSFCHs 340 by likelihood of LBT success, two or more of the PSFCHs 340 are at a same priority level (e.g., have the same likelihood of LBT success) , the UE may further prioritize the two or more PSFCHs 340 based on sidelink priority values.

In one example, if the UE prioritizes the PSFCHs 340 based on loads of the resource block sets 305, the prioritization order may be PSFCH1/2/3/6 ＜ PSFCH4/5. That is, the PSFCHs 340 in the resource block set 305-b may be associated with a first likelihood of LBT success that is less than a second likelihood of LBT success associated with the PSFCHs 340 in the resource block set 340-a. In such cases, the UE may subsequently prioritize the PSFCHs 340 in each resource block set 305 based on sidelink priority values. Using the example sidelink priority values shown in Table 1, such prioritization by LBT success rate first followed by sidelink priority values may result in a final prioritization order of PSFCH1 ＜ PSFCH6 ＜ PSFCH3 ＜ PSFCH2 ＜PSFCH4 ＜ PSFCH5. In another example, if the UE prioritizes the PSFCHs 340 based on LBT window sizes associated with each of the PSFCHs 340, the prioritization order may be PSFCH6 = PSFCH1 ＜ PSFCH5 ＜ PSFCH4 ＜ PSFCH3 = PSFCH2, where the PSFCH 340-f and the PSFCH 340-a (e.g., PSFCH6 and PSFCH1, respectively) may be associated with a same likelihood of LBT success and corresponding priority level and the PSFCH 340-c and the PSFCH 340-b (e.g., PSFCH3 and PSFCH2, respectively) may be associated with a same likelihood of LBT success and corresponding priority level. To differentiate the priorities of these two pairs of PSFCHs 340, the UE may subsequently prioritize the PSFCHs 340 based on sidelink priority values. Using the example sidelink priority values illustrated in Table 1, the UE may ultimately prioritize the PSFCH 340-b (PSFCH2) above the PSFCH 340-c (PSFCH3) because the sidelink priority value of one associated with the PSFCH 340-b may indicate a higher priority than the sidelink priority value of three associated with the PSFCH 340-b. The UE may prioritize the PSFCH 340-f (PSFCH6) above the PSFCH 340-a (PSFCH1) because the sidelink priority value of four associated with the PSFCH 340-f may indicate a higher priority than the sidelink priority value of five associated with the PSFCH 340-a. The final prioritization order may be PSFCH1 ＜ PSFCH6 ＜ PSFCH5 ＜ PSFCH4 ＜ PSFCH3 ＜ PSFCH2.

In some examples, the sidelink PSFCH prioritization protocol may indicate that the UE is to determine PSFCH priority based on the sidelink priority value associated with each PSFCH 340 first, and then based on the likelihood of LBT success (e.g., the prioritization parameters) for PSFCHs 340 with a same priority value. For example, if, after the UE prioritizes the PSFCHs 340 by sidelink priority value, two or more of the PSFCHs 340 are at a same priority level (e.g., have the same priority value) , the UE may further prioritize the two or more PSFCHs 340 based on likelihood of LBT success. Using the example sidelink priority values shown in Table 1, the UE may prioritize the PSFCHs 340-a through 340-f in a prioritization order of PSFCH1 ＜PSFCH6 ＜ PSFCH3 ＜ PSFCH4 ＜ PSFCH2 = PSFCH5, where the PSFCH 340-b (PSFCH2) and the PSFCH 340-e (PSFCH5) may have a same priority level. The UE may subsequently prioritize the PSFCH 340-b and the PSFCH 340-e based on a likelihood of LBT success using one or more of the described prioritization parameters. If the UE prioritizes the two PSFCHs 340 based on resource block set loads, the UE may prioritize the PSFCH 340-e above the PSFCH 340-b based on the resource block set 305-a of the PSFCH 340-e being associated with a lower load and thus a higher likelihood of LBT success than the resource block set 305-b of the PSFCH 340-b. In another example, if the UE prioritizes the two PSFCHs 340 based on LBT window sizes of each PSFCH 340, the UE may prioritize the PSFCH 340-b above the PSFCH 340-e based on the LBT window size (e.g., 61) of the PSFCH 340-b being smaller than and thus associated with a higher likelihood of LBT success than the LBT window size (88) of the PSFCH 340-e.

The UE may generate a prioritization order or list of the PSFCHs 340 based on the described techniques. The UE may subsequently select up to a threshold quantity of the PSFCHs 340 for transmission in the PSFCH symbol 330-b. For example, if the UE is capable of transmitting four or less PSFCHs 340 at a same time, the UE may select the four PSFCHs 340 that are prioritized highest in the prioritization order. In an example, if the threshold quantity is four and if the prioritization order is PSFCH1 ＜PSFCH6 ＜ PSFCH5 ＜ PSFCH4 ＜ PSFCH3 ＜ PSFCH2, the UE may select the PSFCHs 340-b, 340-c, 340-d, and 340-e (e.g., PSFCH2, PSFCH3, PSFCH4, and PSFCH5) for transmission. The UE may perform LBT procedures for the selected PSFCHs 340. The UE may perform the LBT procedures before the PSFCH symbol 330-b to gain access to a shared radio frequency spectrum band for transmission of the selected subset of PSFCHs 340. Each LBT procedure may be associated with a respective COT interval within the PSFCH symbol 330-b. The LBT procedures may be type-1 channel access procedures.

The UE may transmit the selected subset of PSFCHs 340 via respective frequency resources in the PSFCH symbol 330-b (e.g., in overlapping time resources) based on the LBT procedures succeeding. The UE may refrain from transmitting any of the PSFCHs 340 for which a corresponding LBT procedure fails. By prioritizing the PSFCHs 340 at least in part based on the LBT success rate, the UE may account for LBT success when performing type-1 channel access procedures (e.g., without shared COT) , which may improve reliability and throughput of the communications.

FIG. 4 illustrates an example of a process flow 400 that supports priority handling for feedback channels in sidelink in accordance with one or more aspects of the present disclosure. The process flow 400 may implement or be implemented by aspects of the wireless communications systems 100 and 200 or the feedback timing diagram 300. For example, the process flow 400 illustrates communications between a UE 115-e and one or more other UEs, including at least UE 115-f and UE 115-g, which may represent aspects of corresponding devices as described with reference to FIGs. 1–3. In some aspects, the UE 115-e may prioritize multiple sidelink feedback channels based on a likelihood of LBT success for the sidelink feedback channels. The UE 115-e may select a subset of the channels for transmission based on the prioritizing, which may improve throughput and communication reliability.

In the following description of the process flow 400, the operations between the UEs 115-e, 115-f, and 115-g may be performed in different orders or at different times. Some operations may also be left out of the process flow 400, or other operations may be added. Although the UEs 115-e, 115-f, and 115-g are shown performing the operations of the process flow 400, some aspects of some operations may also be performed by one or more other wireless devices.

At 405, the UE 115-e may receive multiple sidelink messages from one or more other UEs 115, including the UE 115-f, the UE 115-g, and/or other UEs 115. The sidelink messages may be received via PSSCH resources and may be associated with a same sidelink feedback symbol, as described with reference to FIG. 3.

At 410, the UE 115-e may prioritize multiple sidelink feedback channels according to one or more prioritization parameters. Each sidelink feedback channel may be associated with a respective sidelink message of the multiple sidelink messages received at 405, and the multiple sidelink feedback channels may be scheduled for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band (e.g., via a same PSFCH symbol) . The UE 115-e may perform the prioritization based on or because the sidelink feedback channels are scheduled for transmission via overlapping time resources, because LBT procedures for the sidelink feedback channels are a certain type of LBT, or both. Each prioritization parameter may be associated with or indicative of a likelihood of success of an LBT procedure for a respective sidelink feedback channel of the multiple sidelink feedback channels.

At 415, the UE 115-e may perform one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels. The UE 115-e may select the subset of sidelink feedback channels from the multiple sidelink feedback channels based on the prioritization. In some examples, the UE 115-e may select a quantity of sidelink feedback channels that is the same as or less than a threshold quantity of sidelink feedback channels supported by the UE 115-a for simultaneous transmission. The one or more LBT procedures may be type-1 channel access procedures or category 4 LBT procedures based on the UE 115-e not supporting a shared COT. Some or all of the LBT procedures may succeed and be associated with or permit the UE 115-e to access a respective COT interval.

At 420, the UE 115-e may transmit the subset of the of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based on performing the LBT procedures at 415. The one or more COT intervals may be within a same feedback symbol or transmission occasion and may be at least partially overlapping in time. UE 115-e may transmit the subset of the sidelink feedback channels to the one or more other UEs 115, such as the UE 115-f and the UE 115-g, that transmitted the sidelink messages to which the sidelink feedback channels are responsive.

FIG. 5 illustrates a block diagram 500 of a device 505 that supports priority handling for feedback channels in sidelink 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 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

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 priority handling for feedback channels in sidelink) . 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.

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 priority handling for feedback channels in sidelink) . 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.

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 priority handling for feedback channels in sidelink as described herein. For example, the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

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 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 a means for performing the functions described in the present disclosure. In some examples, a processor and memory coupled with the processor may be configured to perform one or more of the functions described herein (e.g., by executing, by the processor, instructions stored in the memory) .

Additionally, or alternatively, in some examples, 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 a processor. If implemented in code executed by a processor, the functions of the communications manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be performed by a general-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 a means for performing the functions described in the present disclosure) .

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.

Additionally, or alternatively, the communications manager 520 may support wireless communication at a UE in accordance with examples as disclosed herein. For example, the communications manager 520 may be configured as or otherwise support a means for prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The communications manager 520 may be configured as or otherwise support a means for performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The communications manager 520 may be configured as or otherwise support a means for transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

By including or configuring the communications manager 520 in accordance with examples as described herein, the device 505 (e.g., a processor controlling or otherwise coupled with the receiver 510, the transmitter 515, the communications manager 520, or a combination thereof) may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communication resources.

FIG. 6 illustrates a block diagram 600 of a device 605 that supports priority handling for feedback channels in sidelink 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 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

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 priority handling for feedback channels in sidelink) . 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.

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 priority handling for feedback channels in sidelink) . 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.

The device 605, or various components thereof, may be an example of means for performing various aspects of priority handling for feedback channels in sidelink as described herein. For example, the communications manager 620 may include a prioritization component 625, an LBT component 630, an PSFCH component 635, 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.

The communications manager 620 may support wireless communication at a UE in accordance with examples as disclosed herein. The prioritization component 625 may be configured as or otherwise support a means for prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The LBT component 630 may be configured as or otherwise support a means for performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The PSFCH component 635 may be configured as or otherwise support a means for transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

FIG. 7 illustrates a block diagram 700 of a communications manager 720 that supports priority handling for feedback channels in sidelink 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 priority handling for feedback channels in sidelink as described herein. For example, the communications manager 720 may include a prioritization component 725, an LBT component 730, an PSFCH component 735, a resource block load component 740, an LBT window component 745, an SCI component 750, an RSSI component 755, a CAPC component 760, a random count-down number component 765, or any combination thereof. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

Additionally, or alternatively, the communications manager 720 may support wireless communication at a UE in accordance with examples as disclosed herein. The prioritization component 725 may be configured as or otherwise support a means for prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The LBT component 730 may be configured as or otherwise support a means for performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The PSFCH component 735 may be configured as or otherwise support a means for transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

In some examples, to support prioritizing the set of multiple sidelink feedback channels, the prioritization component 725 may be configured as or otherwise support a means for prioritizing, based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, where the respective sidelink feedback priority values are indicated via SCI associated with the at least two sidelink feedback channels.

In some examples, to support prioritizing the set of multiple sidelink feedback channels, the prioritization component 725 may be configured as or otherwise support a means for prioritizing the set of multiple sidelink feedback channels according to respective sidelink feedback priority values associated with each of the set of multiple sidelink feedback channels, where prioritizing the set of multiple sidelink feedback channels according to the set of multiple prioritization parameters is based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same sidelink feedback priority value.

In some examples, to support prioritizing the set of multiple sidelink feedback channels, the resource block load component 740 may be configured as or otherwise support a means for prioritizing the set of multiple sidelink feedback channels according to one or more resource block loads, each resource block load of the one or more resource block loads associated with a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, where each sidelink feedback channel of the set of multiple sidelink feedback channels is scheduled for transmission via a respective resource block set of the one or more resource block sets.

In some examples, the SCI component 750 may be configured as or otherwise support a means for receiving SCI within a window associated with a first resource block set of the one or more resource block sets, where a first resource block load of the first resource block set is based on the SCI received within the window, and where the window corresponds to an LBT window for the first resource block set.

In some examples, the RSSI component 755 may be configured as or otherwise support a means for measuring an RSSI within a measurement window associated with a first resource block set of the one or more resource block sets, where a first resource block load of the first resource block set is based on the measured RSSI, and where the measurement window corresponds to an LBT window for the first resource block set.

In some examples, a likelihood of success of an LBT procedure associated with a sidelink feedback channel for transmission via a resource block set is inversely related to a resource block load associated with the resource block set.

In some examples, to support prioritizing the set of multiple sidelink feedback channels, the LBT window component 745 may be configured as or otherwise support a means for prioritizing the set of multiple sidelink feedback channels according to a set of multiple LBT window sizes, each LBT window size of the set of multiple LBT window sizes associated with a respective sidelink feedback channel of the set of multiple sidelink feedback channels, where a likelihood of success of an LBT procedure for a sidelink feedback channel is inversely related to an LBT window size associated with the sidelink feedback channel.

In some examples, the LBT window component 745 may be configured as or otherwise support a means for determining an LBT window size of the set of multiple LBT window sizes for a sidelink feedback channel of the set of multiple sidelink feedback channels based on a count-down number associated with the sidelink feedback channel and a CAPC associated with the sidelink feedback channel.

In some examples, to support prioritizing the set of multiple sidelink feedback channels, the LBT window component 745 may be configured as or otherwise support a means for prioritizing the set of multiple sidelink feedback channels according to one or more reference LBT window sizes, each reference LBT window size of the one or more reference LBT window sizes for a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, where each sidelink feedback channel of the set of multiple sidelink feedback channels is for transmission via a respective resource block set of the one or more resource block sets, and where the respective likelihood of success of the LBT procedure for the respective sidelink feedback channel is inversely related to a respective reference LBT window size associated with the respective sidelink feedback channel.

In some examples, a reference LBT window size for a resource block set of the one or more resource block sets includes a maximum window size of a set of window sizes associated with a set of sidelink feedback channels in the resource block set or a minimum window size of the set of window sizes associated with the set of sidelink feedback channels in the resource block set.

In some examples, the CAPC component 760 may be configured as or otherwise support a means for selecting, for each resource block set of the one or more resource block sets, a respective reference CAPC value. In some examples, the random count-down number component 765 may be configured as or otherwise support a means for selecting, for each resource block set of the one or more resource block sets, a respective random count-down number based on the respective reference CAPC value, where a reference LBT window size for a resource block set of the one or more resource block sets is based on the respective reference CAPC value and the respective random count-down number selected for the resource block set.

In some examples, to support selecting the respective reference CAPC value, the CAPC component 760 may be configured as or otherwise support a means for selecting a maximum CAPC value of a set of CAPC values associated with a set of sidelink feedback channels in a respective resource block set. Additionally, or alternatively, to support selecting the respective reference CAPC value, the CAPC component 760 may be configured as or otherwise support a means for selecting a minimum CAPC value of the set of CAPC values associated with the set of sidelink feedback channels in the respective resource block set.

In some examples, the random count-down number component 765 may be configured as or otherwise support a means for selecting, for each resource block set of the one or more resource block sets, a respective random count-down number, where the selecting is based on sidelink feedback channels in the resource block set being associated with a same CAPC, and where a reference LBT window size for a resource block set of the one or more resource block sets is based on the respective random count-down number selected for the resource block set.

In some examples, the one or more LBT procedures include type-1 channel access procedures. In some examples, the PSFCH component 735 may be configured as or otherwise support a means for receiving a set of multiple sidelink messages, where each sidelink feedback channel of the set of multiple sidelink feedback channels corresponds to a respective sidelink message of the set of multiple sidelink messages.

FIG. 8 illustrates a diagram of a system 800 including a device 805 that supports priority handling for feedback channels in sidelink 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 bi-directional 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, a memory 830, code 835, and a 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) .

The I/O controller 810 may manage input and output signals for the device 805. The I/O controller 810 may also manage peripherals not integrated into the device 805. In some cases, the I/O controller 810 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 810 may utilize an operating system such as 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 a processor, such as the 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.

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.

The memory 830 may include random access memory (RAM) and read-only memory (ROM) . The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed by the 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 processor 840 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the 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.

The 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 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 processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks supporting priority handling for feedback channels in sidelink) . For example, the device 805 or a component of the device 805 may include a processor 840 and memory 830 coupled with or to the processor 840, the processor 840 and memory 830 configured to perform various functions described herein.

Additionally, or alternatively, the communications manager 820 may support wireless communication at a UE in accordance with examples as disclosed herein. For example, the communications manager 820 may be configured as or otherwise support a means for prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The communications manager 820 may be configured as or otherwise support a means for performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The communications manager 820 may be configured as or otherwise support a means for transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures.

By including or configuring the communications manager 820 in accordance with examples as described herein, the device 805 may support techniques for improved communication reliability, reduced latency, more efficient utilization of communication resources, and improved coordination between devices.

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 processor 840, the memory 830, the code 835, or any combination thereof. For example, the code 835 may include instructions executable by the processor 840 to cause the device 805 to perform various aspects of priority handling for feedback channels in sidelink as described herein, or the processor 840 and the memory 830 may be otherwise configured to perform or support such operations.

FIG. 9 illustrates a flowchart showing a method 900 that supports priority handling for feedback channels in sidelink in accordance with one or more 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.

At 905, the method may include prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The operations of 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 prioritization component 725 as described with reference to FIG. 7.

At 910, the method may include performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The operations of 910 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 910 may be performed by an LBT component 730 as described with reference to FIG. 7.

At 915, the method may include transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures. The operations of 915 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 915 may be performed by an PSFCH component 735 as described with reference to FIG. 7.

FIG. 10 illustrates a flowchart showing a method 1000 that supports priority handling for feedback channels in sidelink in accordance with one or more 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 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.

At 1005, the method may include prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels. The operations of 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 prioritization component 725 as described with reference to FIG. 7.

At 1010, the method may include prioritizing, based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, where the respective sidelink feedback priority values are indicated via SCI associated with the at least two sidelink feedback channels. The operations of 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 prioritization component 725 as described with reference to FIG. 7.

At 1015, the method may include performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The operations of 1015 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1015 may be performed by an LBT component 730 as described with reference to FIG. 7.

At 1020, the method may include transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures. The operations of 1020 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1020 may be performed by an PSFCH component 735 as described with reference to FIG. 7.

FIG. 11 illustrates a flowchart showing a method 1100 that supports priority handling for feedback channels in sidelink in accordance with one or more 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.

At 1105, the method may include prioritizing a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band according to respective sidelink feedback priority values associated with each of the set of multiple sidelink feedback channels. The operations of 1105 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1105 may be performed by a prioritization component 725 as described with reference to FIG. 7.

At 1110, the method may include prioritizing, according to a set of multiple prioritization parameters, the set of multiple sidelink feedback channels, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, and where prioritizing the set of multiple sidelink feedback channels according to the set of multiple prioritization parameters is based on at least two sidelink feedback channels of the set of multiple sidelink feedback channels being associated with a same sidelink feedback priority value. The operations of 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 prioritization component 725 as described with reference to FIG. 7.

At 1115, the method may include performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The operations of 1115 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1115 may be performed by an LBT component 730 as described with reference to FIG. 7.

At 1120, the method may include transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures. The operations of 1120 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1120 may be performed by an PSFCH component 735 as described with reference to FIG. 7.

FIG. 12 illustrates a flowchart showing a method 1200 that supports priority handling for feedback channels in sidelink in accordance with one or more 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.

At 1205, the method may include receiving a set of multiple sidelink messages. The operations of 1205 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1205 may be performed by an PSFCH component 735 as described with reference to FIG. 7.

At 1210, the method may include prioritizing, according to a set of multiple prioritization parameters, a set of multiple sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, where each prioritization parameter of the set of multiple prioritization parameters is associated with a respective likelihood of success of an LBT procedure for a respective sidelink feedback channel of the set of multiple sidelink feedback channels, and where each sidelink feedback channel of the set of multiple sidelink feedback channels corresponds to a respective sidelink message of the set of multiple sidelink messages. The operations of 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 prioritization component 725 as described with reference to FIG. 7.

At 1215, the method may include performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the set of multiple sidelink feedback channels, the subset of sidelink feedback channels selected from among the set of multiple sidelink feedback channels based on the prioritizing. The operations of 1215 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1215 may be performed by an LBT component 730 as described with reference to FIG. 7.

At 1220, the method may include transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful LBT procedures based on performing the one or more LBT procedures. The operations of 1220 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1220 may be performed by an PSFCH component 735 as described with reference to FIG. 7.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method for wireless communication at a UE, comprising: prioritizing, according to a plurality of prioritization parameters, a plurality of sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, wherein each prioritization parameter of the plurality of prioritization parameters is associated with a respective likelihood of success of a LBT procedure for a respective sidelink feedback channel of the plurality of sidelink feedback channels; performing one or more LBT procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the plurality of sidelink feedback channels, the subset of sidelink feedback channels selected from among the plurality of sidelink feedback channels based at least in part on the prioritizing; and transmitting the subset of sidelink feedback channels during one or more COT intervals of one or more successful LBT procedures based at least in part on performing the one or more LBT procedures.

Aspect 2: The method of aspect 1, wherein prioritizing the plurality of sidelink feedback channels further comprises: prioritizing, based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, wherein the respective sidelink feedback priority values are indicated via sidelink control information associated with the at least two sidelink feedback channels.

Aspect 3: The method of aspect 1, wherein prioritizing the plurality of sidelink feedback channels further comprises: prioritizing the plurality of sidelink feedback channels according to respective sidelink feedback priority values associated with each of the plurality of sidelink feedback channels, wherein prioritizing the plurality of sidelink feedback channels according to the plurality of prioritization parameters is based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same sidelink feedback priority value.

Aspect 4: The method of any of aspects 1 through 3, wherein prioritizing the plurality of sidelink feedback channels comprises: prioritizing the plurality of sidelink feedback channels according to one or more resource block loads, each resource block load of the one or more resource block loads associated with a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is scheduled for transmission via a respective resource block set of the one or more resource block sets.

Aspect 5: The method of aspect 4, further comprising: receiving SCI within a window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the SCI received within the window, and wherein the window corresponds to a LBT window for the first resource block set.

Aspect 6: The method of aspect 4, further comprising: measuring a RSSI within a measurement window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the measured RSSI, and wherein the measurement window corresponds to a LBT window for the first resource block set.

Aspect 7: The method of any of aspects 4 through 6, wherein a likelihood of success of a LBT procedure associated with a sidelink feedback channel for transmission via a resource block set is inversely related to a resource block load associated with the resource block set.

Aspect 8: The method of any of aspects 1 through 7, wherein prioritizing the plurality of sidelink feedback channels comprises: prioritizing the plurality of sidelink feedback channels according to a plurality of LBT window sizes, each LBT window size of the plurality of LBT window sizes associated with a respective sidelink feedback channel of the plurality of sidelink feedback channels, wherein a likelihood of success of a LBT procedure for a sidelink feedback channel is inversely related to a LBT window size associated with the sidelink feedback channel.

Aspect 9: The method of aspect 8, further comprising: determining a LBT window size of the plurality of LBT window sizes for a sidelink feedback channel of the plurality of sidelink feedback channels based at least in part on a count-down number associated with the sidelink feedback channel and a CAPC associated with the sidelink feedback channel.

Aspect 10: The method of any of aspects 1 through 9, wherein prioritizing the plurality of sidelink feedback channels comprises: prioritizing the plurality of sidelink feedback channels according to one or more reference LBT window sizes, each reference LBT window size of the one or more reference LBT window sizes for a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is for transmission via a respective resource block set of the one or more resource block sets, and wherein the respective likelihood of success of the LBT procedure for the respective sidelink feedback channel is inversely related to a respective reference LBT window size associated with the respective sidelink feedback channel.

Aspect 11: The method of aspect 10, wherein a reference LBT window size for a resource block set of the one or more resource block sets comprises a maximum window size of a set of window sizes associated with a set of sidelink feedback channels in the resource block set or a minimum window size of the set of window sizes associated with the set of sidelink feedback channels in the resource block set.

Aspect 12: The method of aspect 10, further comprising: selecting, for each resource block set of the one or more resource block sets, a respective reference CAPC value; and selecting, for each resource block set of the one or more resource block sets, a respective random count-down number based at least in part on the respective reference CAPC value, wherein a reference LBT window size for a resource block set of the one or more resource block sets is based at least in part on the respective reference CAPC value and the respective random count-down number selected for the resource block set.

Aspect 13: The method of aspect 12, wherein selecting the respective reference CAPC value comprises: selecting a maximum CAPC value of a set of CAPC values associated with a set of sidelink feedback channels in a respective resource block set; or selecting a minimum CAPC value of the set of CAPC values associated with the set of sidelink feedback channels in the respective resource block set.

Aspect 14: The method of aspect 10, further comprising: selecting, for each resource block set of the one or more resource block sets, a respective random count-down number, wherein the selecting is based at least in part on sidelink feedback channels in the resource block set being associated with a same channel access priority class, and wherein a reference LBT window size for a resource block set of the one or more resource block sets is based at least in part on the respective random count-down number selected for the resource block set.

Aspect 15: The method of any of aspects 1 through 14, wherein the one or more LBT procedures comprise type-1 channel access procedures.

Aspect 16: The method of any of aspects 1 through 15, further comprising: receiving a plurality of sidelink messages, wherein each sidelink feedback channel of the plurality of sidelink feedback channels corresponds to a respective sidelink message of the plurality of sidelink messages.

Aspect 17: An apparatus for wireless communication at a UE, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of aspects 1 through 16.

Aspect 18: An apparatus for wireless communication at a UE, comprising at least one means for performing a method of any of aspects 1 through 16.

Aspect 19: A non-transitory computer-readable medium storing code for wireless communication at a UE, the code comprising instructions executable by a processor to perform a method of any of aspects 1 through 16.

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

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.

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.

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 gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor but, in 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) .

The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using 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.

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.

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. ”

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.

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.

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.

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

An apparatus for wireless communication at a user equipment (UE) , comprising:

a processor;

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

prioritize, according to a plurality of prioritization parameters, a plurality of sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, wherein each prioritization parameter of the plurality of prioritization parameters is associated with a respective likelihood of success of a listen-before-talk procedure for a respective sidelink feedback channel of the plurality of sidelink feedback channels;

perform one or more listen-before-talk procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the plurality of sidelink feedback channels, the subset of sidelink feedback channels selected from among the plurality of sidelink feedback channels based at least in part on the prioritizing; and

transmit the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful listen-before-talk procedures based at least in part on performing the one or more listen-before-talk procedures.
The apparatus of claim 1, wherein the instructions to prioritize the plurality of sidelink feedback channels are further executable by the processor to cause the apparatus to:

prioritize, based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, wherein the respective sidelink feedback priority values are indicated via sidelink control information associated with the at least two sidelink feedback channels.
The apparatus of claim 1, wherein the instructions to prioritize the plurality of sidelink feedback channels are further executable by the processor to cause the apparatus to:

prioritize the plurality of sidelink feedback channels according to respective sidelink feedback priority values associated with each of the plurality of sidelink feedback channels, wherein prioritizing the plurality of sidelink feedback channels according to the plurality of prioritization parameters is based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same sidelink feedback priority value.
The apparatus of claim 1, wherein the instructions to prioritize the plurality of sidelink feedback channels are executable by the processor to cause the apparatus to:

prioritize the plurality of sidelink feedback channels according to one or more resource block loads, each resource block load of the one or more resource block loads associated with a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is scheduled for transmission via a respective resource block set of the one or more resource block sets.
The apparatus of claim 4, wherein the instructions are further executable by the processor to cause the apparatus to:

receive sidelink control information within a window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the sidelink control information received within the window, and wherein the window corresponds to a listen-before-talk window for the first resource block set.
The apparatus of claim 4, wherein the instructions are further executable by the processor to cause the apparatus to:

measure a received signal strength indicator within a measurement window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the measured received signal strength indicator, and wherein the measurement window corresponds to a listen-before-talk window for the first resource block set.
The apparatus of claim 4, wherein a likelihood of success of a listen-before-talk procedure associated with a sidelink feedback channel for transmission via a resource block set is inversely related to a resource block load associated with the resource block set.
The apparatus of claim 1, wherein the instructions to prioritize the plurality of sidelink feedback channels are executable by the processor to cause the apparatus to:

prioritize the plurality of sidelink feedback channels according to a plurality of listen-before-talk window sizes, each listen-before-talk window size of the plurality of listen-before-talk window sizes associated with a respective sidelink feedback channel of the plurality of sidelink feedback channels, wherein a likelihood of success of a listen-before-talk procedure for a sidelink feedback channel is inversely related to a listen-before-talk window size associated with the sidelink feedback channel.
The apparatus of claim 8, wherein the instructions are further executable by the processor to cause the apparatus to:

determine a listen-before-talk window size of the plurality of listen-before-talk window sizes for a sidelink feedback channel of the plurality of sidelink feedback channels based at least in part on a count-down number associated with the sidelink feedback channel and a channel access priority class associated with the sidelink feedback channel.
The apparatus of claim 1, wherein the instructions to prioritize the plurality of sidelink feedback channels are executable by the processor to cause the apparatus to:

prioritize the plurality of sidelink feedback channels according to one or more reference listen-before-talk window sizes, each reference listen-before-talk window size of the one or more reference listen-before-talk window sizes for a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is for transmission via a respective resource block set of the one or more resource block sets, and wherein the respective likelihood of success of the listen-before-talk procedure for the respective sidelink feedback channel is inversely related to a respective reference listen-before-talk window size associated with the respective sidelink feedback channel.
The apparatus of claim 10, wherein a reference listen-before-talk window size for a resource block set of the one or more resource block sets comprises a maximum window size of a set of window sizes associated with a set of sidelink feedback channels in the resource block set or a minimum window size of the set of window sizes associated with the set of sidelink feedback channels in the resource block set.
The apparatus of claim 10, wherein the instructions are further executable by the processor to cause the apparatus to:

select, for each resource block set of the one or more resource block sets, a respective reference channel access priority class value; and

select, for each resource block set of the one or more resource block sets, a respective random count-down number based at least in part on the respective reference channel access priority class value, wherein a reference listen-before-talk window size for a resource block set of the one or more resource block sets is based at least in part on the respective reference channel access priority class value and the respective random count-down number selected for the resource block set.
The apparatus of claim 12, wherein the instructions to select the respective reference channel access priority class value are executable by the processor to cause the apparatus to:

select a maximum channel access priority class value of a set of channel access priority class values associated with a set of sidelink feedback channels in a respective resource block set; or

select a minimum channel access priority class value of the set of channel access priority class values associated with the set of sidelink feedback channels in the respective resource block set.
The apparatus of claim 10, wherein the instructions are further executable by the processor to cause the apparatus to:

select, for each resource block set of the one or more resource block sets, a respective random count-down number, wherein the selecting is based at least in part on sidelink feedback channels in the resource block set being associated with a same channel access priority class, and wherein a reference listen-before-talk window size for a resource block set of the one or more resource block sets is based at least in part on the respective random count-down number selected for the resource block set.
The apparatus of claim 1, wherein the one or more listen-before-talk procedures comprise type-1 channel access procedures.
The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

receive a plurality of sidelink messages, wherein each sidelink feedback channel of the plurality of sidelink feedback channels corresponds to a respective sidelink message of the plurality of sidelink messages.
A method for wireless communication at a user equipment (UE) , comprising:

prioritizing, according to a plurality of prioritization parameters, a plurality of sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, wherein each prioritization parameter of the plurality of prioritization parameters is associated with a respective likelihood of success of a listen-before-talk procedure for a respective sidelink feedback channel of the plurality of sidelink feedback channels;

performing one or more listen-before-talk procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the plurality of sidelink feedback channels, the subset of sidelink feedback channels selected from among the plurality of sidelink feedback channels based at least in part on the prioritizing; and

transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful listen-before-talk procedures based at least in part on performing the one or more listen-before-talk procedures.
The method of claim 17, wherein prioritizing the plurality of sidelink feedback channels further comprises:

prioritizing, based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, wherein the respective sidelink feedback priority values are indicated via sidelink control information associated with the at least two sidelink feedback channels.
The method of claim 17, wherein prioritizing the plurality of sidelink feedback channels further comprises:

prioritizing the plurality of sidelink feedback channels according to respective sidelink feedback priority values associated with each of the plurality of sidelink feedback channels, wherein prioritizing the plurality of sidelink feedback channels according to the plurality of prioritization parameters is based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same sidelink feedback priority value.
The method of claim 17, wherein prioritizing the plurality of sidelink feedback channels comprises:

prioritizing the plurality of sidelink feedback channels according to one or more resource block loads, each resource block load of the one or more resource block loads associated with a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is scheduled for transmission via a respective resource block set of the one or more resource block sets.
The method of claim 20, further comprising:

receiving sidelink control information within a window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the sidelink control information received within the window, and wherein the window corresponds to a listen-before-talk window for the first resource block set.
The method of claim 20, further comprising:

measuring a received signal strength indicator within a measurement window associated with a first resource block set of the one or more resource block sets, wherein a first resource block load of the first resource block set is based at least in part on the measured received signal strength indicator, and wherein the measurement window corresponds to a listen-before-talk window for the first resource block set.
The method of claim 20, wherein a likelihood of success of a listen-before-talk procedure associated with a sidelink feedback channel for transmission via a resource block set is inversely related to a resource block load associated with the resource block set.
The method of claim 17, wherein prioritizing the plurality of sidelink feedback channels comprises:

prioritizing the plurality of sidelink feedback channels according to a plurality of listen-before-talk window sizes, each listen-before-talk window size of the plurality of listen-before-talk window sizes associated with a respective sidelink feedback channel of the plurality of sidelink feedback channels, wherein a likelihood of success of a listen-before-talk procedure for a sidelink feedback channel is inversely related to a listen-before-talk window size associated with the sidelink feedback channel.
The method of claim 17, wherein prioritizing the plurality of sidelink feedback channels comprises:

prioritizing the plurality of sidelink feedback channels according to one or more reference listen-before-talk window sizes, each reference listen-before-talk window size of the one or more reference listen-before-talk window sizes for a respective resource block set of one or more resource block sets of the shared radio frequency spectrum band, wherein each sidelink feedback channel of the plurality of sidelink feedback channels is for transmission via a respective resource block set of the one or more resource block sets, and wherein the respective likelihood of success of the listen-before-talk procedure for the respective sidelink feedback channel is inversely related to a respective reference listen-before-talk window size associated with the respective sidelink feedback channel.
An apparatus for wireless communication at a user equipment (UE) , comprising:

means for prioritizing, according to a plurality of prioritization parameters, a plurality of sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, wherein each prioritization parameter of the plurality of prioritization parameters is associated with a respective likelihood of success of a listen-before-talk procedure for a respective sidelink feedback channel of the plurality of sidelink feedback channels;

means for performing one or more listen-before-talk procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the plurality of sidelink feedback channels, the subset of sidelink feedback channels selected from among the plurality of sidelink feedback channels based at least in part on the prioritizing; and

means for transmitting the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful listen-before-talk procedures based at least in part on performing the one or more listen-before-talk procedures.
The apparatus of claim 26, wherein the means for prioritizing the plurality of sidelink feedback channels further comprise:

means for prioritizing, based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, wherein the respective sidelink feedback priority values are indicated via sidelink control information associated with the at least two sidelink feedback channels.
The apparatus of claim 26, wherein the means for prioritizing the plurality of sidelink feedback channels further comprise:

means for prioritizing the plurality of sidelink feedback channels according to respective sidelink feedback priority values associated with each of the plurality of sidelink feedback channels, wherein prioritizing the plurality of sidelink feedback channels according to the plurality of prioritization parameters is based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same sidelink feedback priority value.
A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE) , the code comprising instructions executable by a processor to:

prioritize, according to a plurality of prioritization parameters, a plurality of sidelink feedback channels for transmission via at least partially overlapping time resources of a shared radio frequency spectrum band, wherein each prioritization parameter of the plurality of prioritization parameters is associated with a respective likelihood of success of a listen-before-talk procedure for a respective sidelink feedback channel of the plurality of sidelink feedback channels;

perform one or more listen-before-talk procedures to access the shared radio frequency spectrum band for transmission of a subset of sidelink feedback channels of the plurality of sidelink feedback channels, the subset of sidelink feedback channels selected from among the plurality of sidelink feedback channels based at least in part on the prioritizing; and

transmit the subset of sidelink feedback channels during one or more channel occupancy time intervals of one or more successful listen-before-talk procedures based at least in part on performing the one or more listen-before-talk procedures.
The non-transitory computer-readable medium of claim 29, wherein the instructions to prioritize the plurality of sidelink feedback channels are further executable by the processor to:

prioritize, based at least in part on at least two sidelink feedback channels of the plurality of sidelink feedback channels being associated with a same prioritization parameter, the at least two sidelink feedback channels according to respective sidelink feedback priority values associated with the at least two sidelink feedback channels, wherein the respective sidelink feedback priority values are indicated via sidelink control information associated with the at least two sidelink feedback channels.