WO2024173024A1

WO2024173024A1 - Releasing out-of-cot reservations in sidelink

Info

Publication number: WO2024173024A1
Application number: PCT/US2024/013229
Authority: WO
Inventors: Stelios STEFANATOS; Giovanni Chisci; Chih-Hao Liu; Qing Li
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2023-02-17
Filing date: 2024-01-26
Publication date: 2024-08-22
Anticipated expiration: 2025-08-17

Abstract

A method for wireless communication at a first user equipment (UE) and related apparatus are provided. In the method, the first UE detects whether a second UE is eligible for utilizing a channel occupancy time (COT). A transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication. The first UE further adjusts, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE, and perform sidelink communication based on the adjusted reservation status of the transmission resource.

Description

RELEASING OUT-OF-COT RESERVATIONS IN SIDELINK

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of Greece Patent Application Serial No. 20230100139, entitled “RELEASING OUT-OF-COT RESERVATIONS IN SIDELINK” and filed on February 17, 2023, which is expressly incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates generally to communication systems, and more particularly, to the release of out of channel occupancy time (COT) reservations in sidelink in wireless communication.

INTRODUCTION

[0003] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0004] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3 GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable low latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

BRIEF SUMMARY

[0005] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. This summary neither identifies key or critical elements of all aspects nor delineates the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a first user equipment (UE). The apparatus may include memory and at least one processor coupled to the memory. Based at least in part on information stored in the memory, the at least one processor may be configured to detect whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and perform sidelink communication based on the adjusted reservation status of the transmission resource.

[0007] In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a first UE. The apparatus may include memory and at least one processor coupled to the memory. Based at least in part on information stored in the memory, the at least one processor may be configured to reserve a transmission resource for communication; and utilize a COT located before the transmission resource for the communication, where the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE. [0008] To the accomplishment of the foregoing and related ends, the one or more aspects may include the features hereinafter fully described and particularly pointed out in the claims. The following description and the drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. l is a diagram illustrating an example of a wireless communication system and an access network.

[0010] FIG. 2A is a diagram illustrating an example of a first frame, in accordance with various aspects of the present disclosure.

[0011] FIG. 2B is a diagram illustrating an example of downlink (DL) channels within a subframe, in accordance with various aspects of the present disclosure.

[0012] FIG. 2C is a diagram illustrating an example of a second frame, in accordance with various aspects of the present disclosure.

[0013] FIG. 2D is a diagram illustrating an example of uplink (UL) channels within a subframe, in accordance with various aspects of the present disclosure.

[0014] FIG. 3 is a diagram illustrating an example of a base station and user equipment (UE) in an access network.

[0015] FIG. 4 is a diagram illustrating an example reservation mechanism for retransmissions of the same TB.

[0016] FIG. 5 is a diagram illustrating an example COT sharing among multiple UEs.

[0017] FIG. 6 is a diagram illustrating an example re-evaluation of out-of-COT resource reservations.

[0018] FIG. 7 is a diagram illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure.

[0019] FIG. 8 is a diagram illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure.

[0020] FIG. 9 is a diagram illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure.

[0021] FIG. 10 is a call flow diagram illustrating a method of wireless communication in accordance with various aspects of the present disclosure. [0022] FIG. 11 is a flowchart illustrating methods of wireless communication at a UE in accordance with various aspects of the present disclosure.

[0023] FIG. 12 is a flowchart illustrating methods of wireless communication at a UE in accordance with various aspects of the present disclosure.

[0024] FIG. 13 is a flowchart illustrating methods of wireless communication at a UE in accordance with various aspects of the present disclosure.

[0025] FIG. 14 is a flowchart illustrating methods of wireless communication at a UE in accordance with various aspects of the present disclosure.

[0026] FIG. 15 is a diagram illustrating an example of a hardware implementation for an example apparatus and/or network entity.

[0027] FIG. 16 is a diagram illustrating an example of a hardware implementation for an example network entity.

DETAILED DESCRIPTION

[0028] Various aspects relate generally to a communication system. Some aspects more specifically relate to the release of out of COT reservations in sidelink in wireless communication. In some examples, a first UE may detect whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and perform sidelink communication based on the adjusted reservation status of the transmission resource. In some examples, a first UE may reserve a transmission resource for communication; and utilize a COT located before the transmission resource for the communication, where the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE.

[0029] Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, by detecting whether a second UE is eligible for utilizing a COT and adjusting, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE, the described techniques can be used to enable one UE to use a transmission resource reserved by another UE based on another UE’s utilization of the COT. Hence, the described techniques enable more efficient utilization of transmission resources and improve the efficiency of wireless communication.

[0030] The detailed description set forth below in connection with the drawings describes various configurations and does not represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0031] Several aspects of telecommunication systems are presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0032] By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise, shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof. [0033] Accordingly, in one or more example aspects, implementations, and/or use cases, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, such computer-readable media can include a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the types of computer- readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0034] While aspects, implementations, and/or use cases are described in this application by illustration to some examples, additional or different aspects, implementations and/or use cases may come about in many different arrangements and scenarios. Aspects, implementations, and/or use cases described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, aspects, implementations, and/or use cases may come about via integrated chip implementations and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, artificial intelligence (Al)-enabled devices, etc.). While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described examples may occur. Aspects, implementations, and/or use cases may range a spectrum from chip-level or modular components to non-modular, non-chip- level implementations and further to aggregate, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more techniques herein. In some practical settings, devices incorporating described aspects and features may also include additional components and features for implementation and practice of claimed and described aspect. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor(s), interleaver, adders/summers, etc.). Techniques described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc. of varying sizes, shapes, and constitution.

[0035] Deployment of communication systems, such as 5G NR systems, may be arranged in multiple manners with various components or constituent parts. In a 5G NR system, or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element, or a network equipment, such as a base station (BS), or one or more units (or one or more components) performing base station functionality, may be implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB), evolved NB (eNB), NRBS, 5GNB, access point (AP), a transmission reception point (TRP), or a cell, etc.) may be implemented as an aggregated base station (also known as a standalone BS or a monolithic BS) or a disaggregated base station.

[0036] An aggregated base station may be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node. A disaggregated base station may be configured to utilize a protocol stack that is physically or logically distributed among two or more units (such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs)). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs may be implemented to communicate with one or more RUs. Each of the CU, DU and RU can be implemented as virtual units, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0037] Base station operation or network design may consider aggregation characteristics of base station functionality. For example, disaggregated base stations may be utilized in an integrated access backhaul (IAB) network, an open radio access network (O- RAN (such as the network configuration sponsored by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Disaggregation may include distributing functionality across two or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network design. The various units of the disaggregated base station, or disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit. [0038] FIG. 1 is a diagram 100 illustrating an example of a wireless communications system and an access network. The illustrated wireless communications system includes a disaggregated base station architecture. The disaggregated base station architecture may include one or more CUs 110 that can communicate directly with a core network 120 via a backhaul link, or indirectly with the core network 120 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 125 via an E2 link, or a Non-Real Time (Non-RT) RIC 115 associated with a Service Management and Orchestration (SMO) Framework 105, or both). A CU 110 may communicate with one or more DUs 130 via respective midhaul links, such as an Fl interface. The DUs 130 may communicate with one or more RUs 140 via respective fronthaul links. The RUs 140 may communicate with respective UEs 104 via one or more radio frequency (RF) access links. In some implementations, the UE 104 may be simultaneously served by multiple RUs 140.

[0039] Each of the units, i.e., the CUs 110, the DUs 130, the RUs 140, as well as the Near- RT RICs 125, the Non-RT RICs 115, and the SMO Framework 105, may include one or more interfaces or be coupled to one or more interfaces configured to receive or to transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communication interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or to transmit signals over a wired transmission medium to one or more of the other units. Additionally, the units can include a wireless interface, which may include a receiver, a transmitter, or a transceiver (such as an RF transceiver), configured to receive or to transmit signals, or both, over a wireless transmission medium to one or more of the other units.

[0040] In some aspects, the CU 110 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 110. The CU 110 may be configured to handle user plane functionality (i.e., Central Unit - User Plane (CU-UP)), control plane functionality (i.e., Central Unit - Control Plane (CU-CP)), or a combination thereof. In some implementations, the CU 110 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as an El interface when implemented in an O-RAN configuration. The CU 110 can be implemented to communicate with the DU 130, as necessary, for network control and signaling.

[0041] The DU 130 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 140. In some aspects, the DU 130 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation, demodulation, or the like) depending, at least in part, on a functional split, such as those defined by 3 GPP. In some aspects, the DU 130 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 130, or with the control functions hosted by the CU 110.

[0042] Lower-layer functionality can be implemented by one or more RUs 140. In some deployments, an RU 140, controlled by a DU 130, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like), or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU(s) 140 can be implemented to handle over the air (OTA) communication with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU(s) 140 can be controlled by the corresponding DU 130. In some scenarios, this configuration can enable the DU(s) 130 and the CU 110 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

[0043] The SMO Framework 105 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 105 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements that may be managed via an operations and maintenance interface (such as an 01 interface). For virtualized network elements, the SMO Framework 105 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 190) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an 02 interface). Such virtualized network elements can include, but are not limited to, CUs 110, DUs 130, RUs 140 andNear-RTRICs 125. In some implementations, the SMO Framework 105 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O- eNB) 111, via an 01 interface. Additionally, in some implementations, the SMO Framework 105 can communicate directly with one or more RUs 140 via an 01 interface. The SMO Framework 105 also may include a Non-RT RIC 115 configured to support functionality of the SMO Framework 105.

[0044] The Non-RT RIC 115 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, artificial intelligence (Al) / machine learning (ML) (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near- RT RIC 125. The Non-RT RIC 115 may be coupled to or communicate with (such as via an Al interface) the Near-RT RIC 125. The Near-RT RIC 125 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 110, one or more DUs 130, or both, as well as an O-eNB, with the Near-RT RIC 125.

[0045] In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 125, the Non-RT RIC 115 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 125 and may be received at the SMO Framework 105 or the Non-RT RIC 115 from non-network data sources or from network functions. In some examples, the Non-RT RIC 115 or the Near-RT RIC 125 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 115 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 105 (such as reconfiguration via 01) or via creation of RAN management policies (such as Al policies).

[0046] At least one of the CU 110, the DU 130, and the RU 140 may be referred to as a base station 102. Accordingly, a base station 102 may include one or more of the CU 110, the DU 130, and the RU 140 (each component indicated with dotted lines to signify that each component may or may not be included in the base station 102). The base station 102 provides an access point to the core network 120 for a UE 104. The base station 102 may include macrocells (high power cellular base station) and/or small cells (low power cellular base station). The small cells include femtocells, picocells, and microcells. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links between the RUs 140 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to an RU 140 and/or downlink (DL) (also referred to as forward link) transmissions from an RU 140 to a UE 104. The communication links may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base station 102 / UEs 104 may use spectrum up to X MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Ex MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).

[0047] Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL wireless wide area network (WWAN) spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, Bluetooth, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

[0048] The wireless communications system may further include a Wi-Fi AP 150 in communication with UEs 104 (also referred to as Wi-Fi stations (STAs)) via communication link 154, e.g., in a 5 GHz unlicensed frequency spectrum or the like. When communicating in an unlicensed frequency spectrum, the UEs 104 / AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

[0049] The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz - 300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band.

[0050] The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHz - 24.25 GHz). Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into midband frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR2-2 (52.6 GHz - 71 GHz), FR4 (71 GHz - 114.25 GHz), and FR5 (114.25 GHz - 300 GHz). Each of these higher frequency bands falls within the EHF band.

[0051] With the above aspects in mind, unless specifically stated otherwise, the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, FR4, FR2-2, and/or FR5, or may be within the EHF band.

[0052] The base station 102 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate beamforming. The base station 102 may transmit a beamformed signal 182 to the UE 104 in one or more transmit directions. The UE 104 may receive the beamformed signal from the base station 102 in one or more receive directions. The UE 104 may also transmit a beamformed signal 184 to the base station 102 in one or more transmit directions. The base station 102 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 102 / UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 102 / UE 104. The transmit and receive directions for the base station 102 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.

[0053] The base station 102 may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a TRP, network node, network entity, network equipment, or some other suitable terminology. The base station 102 can be implemented as an integrated access and backhaul (IAB) node, a relay node, a sidelink node, an aggregated (monolithic) base station with a baseband unit (BBU) (including a CU and a DU) and an RU, or as a disaggregated base station including one or more of a CU, a DU, and/or an RU. The set of base stations, which may include disaggregated base stations and/or aggregated base stations, may be referred to as next generation (NG) RAN (NG-RAN).

[0054] The core network 120 may include an Access and Mobility Management Function (AMF) 161, a Session Management Function (SMF) 162, a User Plane Function (UPF) 163, a Unified Data Management (UDM) 164, one or more location servers 168, and other functional entities. The AMF 161 is the control node that processes the signaling between the UEs 104 and the core network 120. The AMF 161 supports registration management, connection management, mobility management, and other functions. The SMF 162 supports session management and other functions. The UPF 163 supports packet routing, packet forwarding, and other functions. The UDM 164 supports the generation of authentication and key agreement (AKA) credentials, user identification handling, access authorization, and subscription management. The one or more location servers 168 are illustrated as including a Gateway Mobile Location Center (GMLC) 165 and a Location Management Function (LMF) 166. However, generally, the one or more location servers 168 may include one or more location/positioning servers, which may include one or more of the GMLC 165, the LMF 166, a position determination entity (PDE), a serving mobile location center (SMLC), a mobile positioning center (MPC), or the like. The GMLC 165 and the LMF 166 support UE location services. The GMLC 165 provides an interface for clients/applications (e.g., emergency services) for accessing UE positioning information. The LMF 166 receives measurements and assistance information from the NG-RAN and the UE 104 via the AMF 161 to compute the position of the UE 104. The NG-RAN may utilize one or more positioning methods in order to determine the position of the UE 104. Positioning the UE 104 may involve signal measurements, a position estimate, and an optional velocity computation based on the measurements. The signal measurements may be made by the UE 104 and/or the base station 102 serving the UE 104. The signals measured may be based on one or more of a satellite positioning system (SPS) 170 (e.g., one or more of a Global Navigation Satellite System (GNSS), global position system (GPS), non-terrestrial network (NTN), or other satellite position/location system), LTE signals, wireless local area network (WLAN) signals, Bluetooth signals, a terrestrial beacon system (TBS), sensor-based information (e.g., barometric pressure sensor, motion sensor), NR enhanced cell ID (NRE-CID) methods, NR signals (e.g., multi -round trip time (Multi -RTT), DL angle- of-departure (DL-AoD), DL time difference of arrival (DL-TDOA), UL time difference of arrival (UL-TDOA), and UL angle-of-arrival (UL-AoA) positioning), and/or other systems/signals/sensors.

[0055] Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as loT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. In some scenarios, the term UE may also apply to one or more companion devices such as in a device constellation arrangement. One or more of these devices may collectively access the network and/or individually access the network.

[0056] Referring again to FIG. 1, in certain aspects, the UE 104 may include a resource reservation management component 198. In some aspects, the resource reservation management component 198 may be configured to detect whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and perform sidelink communication based on the adjusted reservation status of the transmission resource. In certain aspects, the base station 102 may include a resource reservation management component 199. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0057] FIG. 2A is a diagram 200 illustrating an example of a first subframe within a 5GNR frame structure. FIG. 2B is a diagram 230 illustrating an example of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250 illustrating an example of a second subframe within a 5G NR frame structure. FIG. 2D is a diagram 280 illustrating an example of UL channels within a 5G NR subframe. The 5G NR frame structure may be frequency division duplexed (FDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for either DL or UL, or may be time division duplexed (TDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by FIGs. 2A, 2C, the 5G NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL), where D is DL, U is UL, and F is flexible for use between DL/UL, and subframe 3 being configured with slot format 1 (with all UL). While subframes 3, 4 are shown with slot formats 1, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI), or semi- statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI). Note that the description infra applies also to a 5G NR frame structure that is TDD.

[0058] FIGs. 2A-2D illustrate a frame structure, and the aspects of the present disclosure may be applicable to other wireless communication technologies, which may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 14 or 12 symbols, depending on whether the cyclic prefix (CP) is normal or extended. For normal CP, each slot may include 14 symbols, and for extended CP, each slot may include 12 symbols. The symbols on DL may be CP orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (for power limited scenarios; limited to a single stream transmission). The number of slots within a subframe is based on the CP and the numerology. The numerology defines the subcarrier spacing (SCS) (see Table 1). The symbol length/duration may scale with 1/SCS.

Table 1: Numerology, SCS, and CP

[0059] For normal CP (14 symbols/slot), different numerologies p 0 to 4 allow for 1, 2, 4, 8, and 16 slots, respectively, per subframe. For extended CP, the numerology 2 allows for 4 slots per subframe. Accordingly, for normal CP and numerology p, there are 14 symbols/slot and 2^ slots/subframe. The subcarrier spacing may be equal to 2 * 15 kHz, where g is the numerology 0 to 4. As such, the numerology p=0 has a subcarrier spacing of 15 kHz and the numerology p=4 has a subcarrier spacing of 240 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGs. 2A-2D provide an example of normal CP with 14 symbols per slot and numerology p=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 ps. Within a set of frames, there may be one or more different bandwidth parts (BWPs) (see FIG. 2B) that are frequency division multiplexed. Each BWP may have a particular numerology and CP (normal or extended).

[0060] A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0061] As illustrated in FIG. 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as R for one particular configuration, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and phase tracking RS (PT-RS).

[0062] FIG. 2B illustrates an example of various DL channels within a subframe of a frame.

The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or 16 CCEs), each CCE including six RE groups (REGs), each REG including 12 consecutive REs in an OFDM symbol of an RB. A PDCCH within one BWP may be referred to as a control resource set (CORESET). A UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., common search space, UE-specific search space) during PDCCH monitoring occasions on the CORESET, where the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at greater and/or lower frequencies across the channel bandwidth. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE 104 to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the DM-RS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block (also referred to as SS block (SSB)). The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

[0063] As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS). The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequencydependent scheduling on the UL.

[0064] FIG. 2D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and hybrid automatic repeat request (HARQ) acknowledgment (ACK) (HARQ-ACK) feedback (i.e., one or more HARQ ACK bits indicating one or more ACK and/or negative ACK (NACK)). The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

[0065] FIG. 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In the DL, Internet protocol (IP) packets may be provided to a controller/processor 375. The controller/processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (REC) layer, and a medium access control (MAC) layer. The controller/processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0066] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318Tx. Each transmitter 318Tx may modulate a radio frequency (RF) carrier with a respective spatial stream for transmission.

[0067] At the UE 350, each receiver 354Rx receives a signal through its respective antenna 352. Each receiver 354Rx recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.

[0068] The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

[0069] Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re- segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0070] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354Tx. Each transmitter 354Tx may modulate an RF carrier with a respective spatial stream for transmission.

[0071] The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318Rx receives a signal through its respective antenna 320. Each receiver 318Rx recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0072] The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

[0073] At least one of the TX processor 368, the RX processor 356, and the controller/processor 359 may be configured to perform aspects in connection with the resource reservation management component 198 of FIG. 1.

[0074] At least one of the TX processor 316, the RX processor 370, and the controller/processor 375 may be configured to perform aspects in connection with the resource reservation management component 199 of FIG. 1.

[0075] In wireless communication, Channel Occupancy Time (or COT) may refer to the amount of time a device (e.g., a UE) occupies a channel for transmitting data over the channel. A COT may be shared among multiple devices (e.g., multiple UEs), herein referred to as “COT sharing.” In COT sharing, each device may be allocated a portion of the total COT, in which the device is eligible to transmit data over the channel using a specific frequency spectrum (or frequency band) associated with the COT. COT sharing may apply to multiple UEs with sidelink connections. With COT sharing, for a UE eligible to transmit within a shared COT, the UE may schedule the transmissions within the shared COT as much as possible. For example, when a UE that has already selected and reserved future resources identifies a new shared COT that the UE is allowed to transmit in, the UE may perform future transmission that was originally scheduled outside the COT earlier so that the transmission may be located within the COT. However, this approach may leave the resources that were reserved outside of the COT (the “out-of-COT” resources) unutilized, resulting in a waste of out-of-COT resources. Example aspects presented herein provide methods and apparatus for releasing previously reserved out-of-COT resources that are not to be used due to, for example, the presence of an unexpected shared COT so that these out-of-COT resources become available for other UEs to utilize.

[0076] In sidelink communication, UEs may reserve future resources to be used for transmissions or retransmissions. The reservation of the future resources may be indicated in the sidelink control information (SCI)-l of a UE transmission. In one configuration, up to two future resources for retransmission of the same TB can be reserved per SCI-1. If the UE wants to perform more retransmissions of a TB, SCI- Is of the retransmissions will be used to reserve more resources. A reservation period may also be indicated to reserve resources for different TB transmissions occurring within the indicated period. FIG. 4 is a diagram 400 illustrating an example reservation mechanism for retransmissions of the same TB. As shown in FIG. 4, a UE that performs the first transmission (e.g., l^st TX 411 at slot l) may reserve one or more future resources (e.g., future slots) for one or more retransmissions (reTXs) (e.g., reserving slot 4 for 2^nd TX 412 (1^st reTX) and slot 9 for 3^rd TX 413 (2^nd reTX)). The UE that performs a reTX may also reserve future resources for following reTXs, which may or may not have been already reserved by previous transmissions. For example, a UE that performs the first reTX (1^st reTX) at slot 4 may reserve the 2^nd reTX at slot 9.

[0077] When a mode-2 sidelink (SL) UE is selecting resources from a resource selection window (RSW), it may exclude from selection all resources in the RSW indicated as reserved by other UEs (provided that the reference signal received power (RSRP) of the transmission that reserved the corresponding resource being above a threshold). This exclusion procedure is beneficial to avoid collisions among UEs, therefore, more efficiently sharing of the limited SL resources. As used herein, the “mode-2 SL” may refer to sidelink communication not involving a network entity (for example, at an area with no network coverage). [0078] In sidelink over unlicensed (shared) spectrum (SL-U), UEs may first perform Listen- Before-Talk (LBT), a procedure in which a UE ensures the transmission channel is free of congestion before transmitting data over the channel, and identify the channel as clear before initiating a transmission. This procedure ensures that no other device (e.g., a WiFi device) is currently transmitting data over the channel and avoid collisions. In order to improve channel access efficiency, multiple UEs may share a COT. For example, a UE that passes a long (type 1) LBT may start a transmission, effectively initiating a COT, throughout which it may keep continuously transmitting. The duration of the COT may not exceed a maximum COT (MCOT) duration corresponding to the Channel Access Priority Class (CAPC) of the transmission. In some examples, instead of transmitting for the whole MCOT duration, the UE may stop its transmission early (for example, when the UE does not have any more data to transmit), and other UE(s) may fill in the remainder of the COT. These other UE(s) may be referred to as the “responder UE(s)” of the COT. The responder UE(s) may use a short (type 2) LBT instead of a long (type 1) LBT to access the channel.

[0079] FIG. 5 is a diagram 500 illustrating an example COT sharing among multiple UEs. As shown in FIG. 5, a UE (UE 511) performing (type 1) LBT 510 and starting a transmission may initiate a COT 520 that is, for example, three slots long (e.g., from slot 1 to slot 3). The UE initiated the COT 520 (i.e., UE 511) may use the first slot (e.g., slot 1) of the COT 520, allowing “responder” UEs (e.g., UE 512 and UE 513) to transmit in the remaining slots (e.g., UE 512 using slot 2, and UE 513 using slot 3), each using a type 2 LBT.

[0080] As type 1 LBT may limit the performance in SL-U compared to type 2 LBT, UEs may try to leverage COT-sharing opportunities so as to perform type 2 LBT for their transmissions, which is more likely to be successful than an out-of-COT type 1 LBT. In one example, a UE may monitor the over-the-air (OTA) activity, and, when the UE identifies a shared COT is ongoing (which the UE is eligible to transmit in), it may select its future transmission resources to be contained within the COT. The COT- initiating transmission may include COT system information (COT-SI) which may indicate the COT “region” (in time and frequency domain) and the UEs that are eligible to transmit in the COT. In some cases, a UE that identifies the presence of a new shared COT may have already reserved resources for its future transmissions that are outside of this COT (or any other COT). In that case, this COT identification may trigger a re-evaluation of these out-of-COT reserved resources, and the UE may reselect them to lie within the currently active COT region.

[0081] FIG. 6 is a diagram 600 illustrating an example re-evaluation of out-of-COT resource reservations. As shown in FIG. 6, a UE may select, at slot n, two future resources (at slots n+2 and n+7) for the transmission of a new TB (e.g., select within the resource selection window 610). After the transmission at slot n+2, and while waiting for next resource at slot n+7, the UE may identify, at slot n+4, a shared COT 620 has initiated that lasts two slots. The identification of the shared COT 620 may trigger the reselection of future resources to occur within the COT 620 (e.g., at slot n+5).

[0082] In some examples, the re-evaluation and re-selection of resources may happen when a future selected (and possibly also reserved) resource is no longer available (e.g., when it was reserved by another UE’s SCI-1). In this case, abandoning the previously selected/reserved resource and selecting a new one is beneficial as it avoids collision, and the conflicting UEs end up using different resources for their transmissions. On the other hand, COT-aware re-evaluation and re-selection of resources is different in that it is not triggered to avoid collisions but to improve the chances of passing the LBT. Hence, when COT-aware re-selection is triggered for a resource that has already been reserved, that reserved resource is unlikely to be utilized by other UEs as the originally intended transmission will be performed over another resource (within the COT) and other UEs may not use the resource as it has been previously declared as reserved. For example, in the example of FIG. 6, when the UE re-selects the resource for the transmission to occur within the COT 620 (e.g., at slot n+5), the out-of-COT resource that was previously reserved by UE for the transmission at slot n+7 may not be utilized by other UEs. This results in inefficient use of resources which could possibly negate the benefits of COT-aware re-selection as it unnecessarily reduces the availability of out-of-COT resources and increases the chance of collisions as UEs content over unnecessarily limited resources. Example aspects presented herein provide methods and apparatus for future reserved resources that are “abandoned” due to COT-aware resource re-selection/re-evaluation to become available for other UEs to utilize.

[0083] In some aspects, a UE that detects a COT-initiating transmission (and corresponding COT-SI) may treat future reservations of resources occurring outside this COT from the responders UEs of this COT as released (e.g., the resources become available for this UE to utilize). The rationale is that the responder UEs may re-evaluate and re- select their resources within the COT, and the previous reservations of out-of-COT resources are no longer valid. FIG. 7 is a diagram 700 illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure. As shown in FIG. 7, the first UE (e.g., UE 711) may reserve a resource at slot 9 for future transmission. The second UE (e.g., UE 712) may initiate a COT 720. For example, the COT 720 may last three slots (from slot 5 to slot 7). The first UE (e.g., UE 711) may be a responder UE of the COT 720 and may transmit in the COT 720, and the first UE’s future reservation (at slot 9) may be released. The released resource (at slot 9) may become available for other UEs to utilize. The first UE (e.g., UE 711) may transmit over a non-reserved in-COT resource (e.g., slot 6) and abandon the previously reserved resource (slot 9). During this process, a UE may identify whether an out-of-COT reservation is made by a UE that is eligible to enter an ongoing COT through, for example, global IDs or device IDs that may be indicated in COT-SI and reservation sidelink control information (SCI).

[0084] In some aspects, instead of a complete release of the previously reserved out-of-COT resources (e.g., slot 9 in FIG. 7), the reservation characteristics of the reserved out-of- COT resources may be adjusted so that these out-of-COT resources become more accessible to other UEs (e.g., these resources become more likely to be utilized by other UEs).

[0085] In one example, when a UE detects a COT-initiating transmission (and corresponding COT-SI), the UE may treat future reservations of resources occurring outside this COT (out-of-COT resources) from responders UEs to this COT as corresponding to a new reservation signal RSRP that is smaller than the original RSRP associated with a reservation transmission that reserved the out-of-COT resources. In some examples, the new RSRP value may be a fixed preconfigured or pre-defined value. In some examples, the difference between the new RSRP value and the original RSRP value may be a preconfigured or pre-defined value.

[0086] In another example, when a UE detects a COT-initiating transmission (and corresponding COT-SI), the UE may treat future reservations of out-of-COT resources from responders UEs (to this COT) as corresponding to a new priority that is lower in priority than the original priority associated with the reservation transmission that reserved the out-of-COT resources (e.g., the reservation SCI- 1 ). For example, if a higher priority value corresponds to a lower priority transmission, the new priority may have a higher priority value than the original priority value. In some examples, the new priority value may be a fixed preconfigured or pre-defined value. In some examples, the difference between the new priority value and the original priority may be a preconfigured value.

[0087] In another example, when a UE detects a COT-initiating transmission (and corresponding COT-SI), the UE may treat future reservations of out-of-COT resources from responders UEs (to this COT) as corresponding to a new reservation signal RSRP that is smaller than the original RSRP associated with the reservation transmission that reserved the out-of-COT resources and corresponding to a new priority that is lower in priority than the original priority associated with the reservation transmission that reserved the out-of-COT resources (e.g., the reservation SCI-1).

[0088] In some aspects, the previously reserved out-of-COT resources that can be released for other UEs may be restricted to the number of first out-of-COT resources that were reserved after the COT (in case there are more than the number first out-of-COT resources have been reserved).

[0089] The number of first out-of-COT resources may be determined in various ways. In some examples, the number may be a preconfigured or pre-defined number. In some examples, the number may be related to the available/remaining COT duration for the responder UE to transmit. For example, the number may correspond to the maximum number of resources that can fit within the available/remaining COT duration.

[0090] In some examples, the number of first out-of-COT resources may depend on the number of reservations made by the responder UE already contained in the COT. For example, if a responder UE has reservations already in the COT, the responder UE may not move the out-of-COT resources within the COT as there is already one resource within the COT. In that case, the out-of-COT resources may not be released to other UEs.

[0091] In some examples, the number of first out-of-COT resources may depend on the number of non-reserved in-COT transmissions made by the responder UE. For example, at the time of resource selection, if a resource-seeking UE identifies that a responder UE has performed two non-reserved in-COT transmissions, which suggests that the responder UE may not use at least two previously reserved out-of-COT resources, the first two, previously reserved, out-of-COT resources may be released and become available to the resource-seeking UE. This procedure may utilize a resource-seeking UE to monitor the responder UEs’ activity within the COT. [0092] In some examples, the number of first out-of-COT resources may correspond to the number of out-of-COT reservations that are within a preconfigured time interval after the end of the COT.

[0093] FIG. 8 is a diagram 800 illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure. As shown in FIG. 8, the first UE (e.g., UE 811) may reserve two resources (at slots 9 and 11) for future transmissions. The second UE (e.g., UE 812) may initiate a COT 820. For example, the COT 820 may last three slots (from slot 5 to slot 7). The first UE (e.g., UE 811) may be a responder UE of the COT 820, and transmit in the COT 820 (e.g., at slot 6). The first UE’s (e.g., UE 811 ’s) utilization of the COT 820 may cause the release of the out-of-COT resources reserved by the first UE. The release of the out-of-COT resources may be limited to a number of first resources reserved by the first UE. For example, the number may be one, and the first out-of-COT resource reserved by the first UE after the COT 820 (e.g., slot 9) may be released, and the other out-of-COT resources reserved by the first UE (e.g., slot 11) may remain reserved (non-released).

[0094] In some aspects, the previously reserved out-of-COT resources that can be released for other UEs may not include the resources reserved for future TBs, if the period indicated by SCI-1 is greater than a preconfigured threshold. If a large reservation period is indicated, the reserved sources may correspond to periodic traffic, and it may not be necessary to move these future TB resources to an earlier time, as the data to be transmitted may not be available at the earlier time.

[0095] In some aspects, the release of future out-of-COT reservations from responder UEs may be activated or de-activated by a COT-initiator. The COT-initiator may be, for example, a UE. The COT-initiator may evaluate the likelihood that the responder UE(s) is to perform a COT-aware re-selection/re-evaluation, and hence may activate or de-active the release of future out-of-COT reservations accordingly.

[0096] In one configuration, the release of future out-of-COT reservations from responder UEs may be activated or de-activated by a COT-initiator transmission (e.g., as part of COT-SI). In one example, a resource pool (or BWP) may be preconfigured to not perform the release of future out-of-COT reserved resources by default. When a future out-of-COT reserved resource is to be released, the COT-SI may indicate the release for the responder UE(s) of this COT. In one example, a resource pool (or BWP) may be preconfigured to perform the release of future out-of-COT reserved resources by default. When a future out-of-COT reserved resource is not released, the COT-SI may indicate the non-release for the responder UE(s) of this COT.

[0097] In some aspects, when a COT-initiator is configured to activate or de-activate the release of future out-of-COT reservations from responder UEs, the activation or deactivation may be applicable to the out-of-COT resources reserved by a subset of responder UEs. The subset of responder UEs may be indicated in various ways. In one example, the subset of responder UEs may be explicitly indicated as part of, for example, COT-SI. In another example, the subset of responder UEs may be indicated by a set of UE identifiers (IDs) respectively corresponding to the subset of UEs, or by a group ID corresponding to the subset of UEs. In another example, the subset of UEs may be identified by a portion of the UE IDs or group ID (e.g., a few bits of each ID). [0098] In some aspects, a responder UE of a COT (e.g., a UE that made an out-of-COT reservation and used a COT for transmission) may decide whether the future out-of- COT resources it reserved can be released and become available for other UEs to utilize. For example, a responder UE that performs a transmission over a non-reserved in-COT resource may explicitly indicate the release of the future out-of-COT resources it reserved.

[0099] The responder UE may indicate the release of the future out-of-COT resources it reserved in various ways. In one example, a responder UE’s transmission over a nonreserved in-COT resource may include a control field indicating that a number of first out-of-COT resources it reserved may be released. In another example, a responder UE’s transmission over a non-reserved in-COT resource may have a frequency domain resource allocation (FDRA) indication and a time domain resource allocation (TDRA) indication, and the FDRA/TDRA indication may match the FDRA/TDRA indication in previous reservation SCI (e.g., the FDRA/TDRA indications may identify the same resources). A UE that receives the same FDRA/TDRA by the same source UE for a second time may consider the corresponding resources to be released. In some examples, an additional single-bit field may be provided to indicate that the FDRA/TDRA indication is for the purpose of releasing (not “reserving”) the resource. This additional single-bit field may be useful for UEs that missed the original reservation transmission for that FDRA/TDRA. For the responder UE of a COT to indicate the release of future out-of-COT resources they reserved, the responder UE may use the same ID (e.g., a global ID) for all the reservation and release transmissions involved. [0100] FIG. 9 is a diagram 900 illustrating an example of future out-of-COT reservations release in accordance with various aspects of the present disclosure. As shown in FIG. 9, the first UE (e.g., UE 911) may reserve, at 930, a resource (at slots 9) for future transmission. The second UE (e.g., UE 912) may initiate a COT 920. For example, the COT 920 may last three slots (from slot 5 to slot 7). The first UE (e.g., UE 911) may be a responder UE of the COT 920 and may transmit in the COT 920 (e.g., at slot 6). The first UE (e.g., UE 911) may explicitly indicate, at 940, that a future out- of-COT resource it reserved (e.g., slot 9) to be release and become available for other UEs to utilize.

[0101] FIG. 10 is a call flow diagram 1000 illustrating a method of wireless communication in accordance with various aspects of this present disclosure.

[0102] As shown in FIG. 10, a responder UE 1006 may reserve, at 1010, a transmission resource. For example, referring to FIG. 7, a responder UE (UE 711) may reserve a transmission resource (at slot 9). Referring to FIG. 8, a responder UE (UE 711) may reserve a transmission resource (at slot 9 or slot 11).

[0103] At 1012, the responder UE 1006 may utilize a COT located before the reserved transmission resource for communication. For example, referring to FIG. 7, the responder UE (UE 711) may utilize a COT 720 located before the reserved transmission resource (slot 9) for communication.

[0104] At 1014, the resource-seeking UE 1002 may receive, from a COT-initiating UE 1008, a COT-initiating transmission including COT-SI (the COT-initiating transmission may be receivable by the responder UE 1006 as well, as shown in FIG. 10). For example, referring to FIG. 7, a resource-seeking UE may receive, from a COT- initiating UE (UE 712), a COT-initiating transmission including COT-SI.

[0105] At 1016, the resource-seeking UE 1002 may detect whether the responder UE 1006 is eligible for utilizing the COT. For example, referring to FIG. 7, a resource-seeking UE may detect whether the responder UE (UE 712) is eligible for utilizing the COT 720.

[0106] At 1018, the resource-seeking UE 1002 may receive from the responder UE 1006, a release indication. For example, referring to FIG. 9, a resource-seeking UE may receive from the responder UE (UE 911) a release indication. The release indication may indicate the release of an out-of-COT resource (e.g., slot 9) the responder UE (UE 911) previously reserved. [0107] At 1020, the resource-seeking UE 1002 may adjust, in response to the responder UE being eligible for utilizing the COT and/or the reception of the release indication (received at 1018) by the responder UE 1002, a reservation status of the transmission resource to the resource-seeking UE such that the transmission resource becomes available to the resource-seeking UE. For example, referring to FIG. 7, a resourceseeking UE may adjust, in response to the responder UE (UE 711) being eligible for utilizing the COT 720, a reservation status of the transmission resource (slot 9) to the resource-seeking UE such that the transmission resource (slot 9) become available to the resource-seeking UE. Referring to FIG. 9, a resource-seeking UE may adjust, in response to the reception of the release indication (at 940) by the responder UE 911, a reservation status of the transmission resource (slot 9) to the resource-seeking UE such that the transmission resource (slot 9) become available to the resource-seeking UE.

[0108] At 1022, the resource-seeking UE 1002 may perform sidelink communication based on the adjusted reservation status of the transmission resource. The resource-seeking UE 1002 may perform sidelink communication with a sidelink UE 1004. In one example, the sidelink UE 1004 may be the responder UE 1006. In another example, the sidelink UE 1004 may be another UE different from the responder UE 1006. For example, referring to FIG. 7, a resource-seeking UE may perform sidelink communication based on the adjusted reservation status of the transmission resource (slot 9).

[0109] FIG. 11 is a flowchart 1100 illustrating methods of wireless communication at a first UE in accordance with various aspects of the present disclosure. The method may be performed by the first UE. The first UE may be the UE 104, 350, 1002, or the apparatus 1504 in the hardware implementation of FIG. 15. The method enables one UE to use a transmission resource reserved by another UE based on another UE’s utilization of a preceding transmission resource (e.g., a COT). The method enables more efficient utilization of transmission resources and improves the efficiency of wireless communication.

[0110] As shown in FIG. 11, at 1102, the first UE may detect whether a second UE is eligible for utilizing a COT. A transmission resource reserved by the second UE may be located after the COT and unavailable to the first UE for communication. FIGs. 7, 8, 9, and 10 illustrate various aspects of the steps in connection with flowchart 1100. For example, referring to FIG. 10, the first UE (UE 1002) may detect, at 1016, whether a second UE (UE 1006) is eligible for utilizing a COT. Referring to FIG. 7, the first UE (a resource-seeking UE, not shown in FIG. 7) may detect whether the second UE (UE 711) is eligible for utilizing the COT 720. A transmission resource (slot 9) reserved by the second UE (UE 711) may be located after the COT 720 and unavailable to the first UE (the resource-seeking UE) for communication. In some aspects, 1102 may be performed by the resource reservation management component 198.

[OHl] At 1104, the first UE may adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE. For example, referring to FIG. 10, the first UE (UE 1002) may adjust, at 1020, in response to the second UE (UE 1006) being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE (UE 1002) such that the transmission resource becomes available to the first UE (UE 1002). Referring to FIG. 7, the first UE (a resource-seeking UE, not shown in FIG. 7) may adjust, in response to the second UE (UE 711) being eligible for utilizing the COT 720, a reservation status of the transmission resource (slot 9) to the first UE (the resource-seeking UE) such that the transmission resource (slot 9) become available to the first UE (the resource-seeking UE). In some aspects, 1104 may be performed by the resource reservation management component 198.

[0112] At 1106, the first UE may perform sidelink communication based on the adjusted reservation status of the transmission resource. For example, referring to FIG. 10, the first UE (UE 1002) may perform, at 1022, sidelink communication with, for example, a sidelink UE 1004, based on the adjusted reservation status of the transmission resource. In some aspects, 1106 may be performed by the resource reservation management component 198.

[0113] FIG. 12 is a flowchart 1200 illustrating methods of wireless communication at a first UE in accordance with various aspects of the present disclosure. The method may be performed by the first UE. The first UE may be the UE 104, 350, 1002, or the apparatus 1504 in the hardware implementation of FIG. 15. The method enables one UE to use a transmission resource reserved by another UE based on another UE’s utilization of a preceding transmission resource (e.g., a COT). The method enables more efficient utilization of transmission resources and improves the efficiency of wireless communication. [0114] As shown in FIG. 12, at 1204, the first UE may detect whether a second UE is eligible for utilizing a COT. A transmission resource reserved by the second UE may be located after the COT and unavailable to the first UE for communication. FIGs. 7, 8, 9, and 10 illustrate various aspects of the steps in connection with flowchart 1200. For example, referring to FIG. 10, the first UE (UE 1002) may detect, at 1016, whether a second UE (UE 1006) is eligible for utilizing a COT. Referring to FIG. 7, the first UE (a resource-seeking UE, not shown in FIG. 7) may detect whether the second UE (UE 711) is eligible for utilizing the COT 720. A transmission resource (slot 9) reserved by the second UE (UE 711) may be located after the COT 720 and unavailable to the first UE (the resource-seeking UE) for communication. In some aspects, 1204 may be performed by the resource reservation management component 198.

[0115] At 1208, the first UE may adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE. For example, referring to FIG. 10, the first UE (UE 1002) may adjust, at 1020, in response to the second UE (UE 1006) being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE (UE 1002) such that the transmission resource becomes available to the first UE (UE 1002). Referring to FIG. 7, the first UE (a resource-seeking UE, not shown in FIG. 7) may adjust, in response to the second UE (UE 711) being eligible for utilizing the COT 720, a reservation status of the transmission resource (slot 9) to the first UE (the resource-seeking UE) such that the transmission resource (slot 9) become available to the first UE (the resource-seeking UE). In some aspects, 1208 may be performed by the resource reservation management component 198.

[0116] At 1210, the first UE may perform sidelink communication based on the adjusted reservation status of the transmission resource. For example, referring to FIG. 10, the first UE (UE 1002) may perform, at 1022, sidelink communication with, for example, a sidelink UE 1004, based on the adjusted reservation status of the transmission resource. In some aspects, 1210 may be performed by the resource reservation management component 198.

[0117] At 1202, the first UE may receive a COT-initiating transmission including COT system information (COT-SI). The detection of whether the second UE is eligible for utilizing the COT is based on the COT-SI. For example, referring to FIG. 10, the first UE (UE 1002) may receive a COT-initiating transmission including COT-SI from a third UE (UE 1008). The detection (at 1016) of whether the second UE (UE 1006) is eligible for utilizing the COT is based on the COT-SI. In some aspects, 1202 may be performed by the resource reservation management component 198.

[0118] In some aspects, to detect whether the second UE is eligible for utilizing the COT, the first UE may be configured to identify the second UE based on sidelink control information (SCI) associated with the transmission resource. For example, referring to FIG. 10, to detect (at 1016) whether the second UE (UE 1006) is eligible for utilizing the COT, the first UE (UE 1002) may be configured to identify the second UE (UE 1006) based on sidelink control information (SCI) associated with the transmission resource. Referring to FIG. 7, the first UE (a resource-seeking UE, not shown in FIG. 7) may be configured to identify the second UE (UE 711) based on sidelink control information (SCI) associated with the transmission resource (slot 9).

[0119] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority. For example, referring to FIG. 10, to adjust (at 1020) the reservation status of the transmission resource to the first UE (UE 1002), the first UE (UE 1002) may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority. Referring to FIG. 7, to adjust the reservation status of the transmission resource to the first UE (a resource-seeking UE, not shown in FIG. 7), the first UE (the resource-seeking UE) may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource (slot 9) to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource (slot 9) to an adjusted priority lower than the original priority.

[0120] In some aspects, the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP may be a preconfigured number or a predetermined number. [0121] In some aspects, the adjusted priority or a priority difference between the original priority and the adjusted priority may be a preconfigured number or a predetermined number.

[0122] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust, in response to the transmission resource being one of a number of first transmission resources reserved by the second UE after the COT, the reservation status of the transmission resource to the first UE. For example, referring to FIG. 8, the first UE (a resource-seeking UE, not shown in FIG. 8) may be configured to: adjust, in response to the transmission resource (slot 9) being one of a number of first transmission resources reserved by the second UE (UE 811) after the COT 820, the reservation status of the transmission resource (slot 9) to the first UE (the resource-seeking UE).

[0123] In some aspects, the number of first transmission resources is a preconfigured number or a predetermined number. For example, referring to FIG. 8, the number of first transmission resources may be one, which may be a preconfigured number or a predetermined number.

[0124] In some aspects, the number of first transmission resources is based on a duration of a part of the COT which the second UE is eligible to utilize. For example, referring to FIG. 8, the number of first transmission resources may be based on a duration of a part of the COT 820 which the second UE (UE 811) is eligible to utilize (e.g., the second UE (UE 811) may be eligible to utilize one slot (slot 6) of the three slots (slots 5-7) of the COT 820).

[0125] In some aspects, the number of first transmission resources is based on the maximum number of resources in the part of the COT which the second UE is eligible to utilize. For example, referring to FIG. 8, the number of first transmission resources may be based on the maximum number of resources in the part of the COT 820 which the second UE (UE 811) is eligible to utilize.

[0126] In some aspects, the number of first transmission resources is based on one or more of: the number of resource reservations made by the second UE in the COT; the number of non-reserved transmissions made by the second UE in the COT; or the number of first transmissions after the COT occurring within a time interval after the COT. For example, referring to FIG. 8, the number of first transmission resources may be based on one or more of: the number of resource reservations made by the second UE (UE 811) in the COT 820; the number of non-reserved transmissions made by the second UE (UE 811) in the COT 820; or the number of first transmissions after the COT 820 (after slot 7) occurring within a time interval after the COT 820.

[0127] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the first UE. For example, referring to FIG. 10, when the first UE (UE 1002) adjusts, at 1020, the reservation status of the transmission resource to the first UE (UE 1002), the first UE (UE 1002) may adjust, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the first UE (UE 1002). Referring to FIG. 7, the first UE may adjust, in response to a reservation period associated with the transmission resource (slot 9) being less than a period threshold, the reservation status of the transmission resource (slot 9) to the first UE.

[0128] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust, based on the COT-SI, the reservation status of the transmission resource to the first UE. For example, referring to FIG. 10, when the first UE (UE 1002) adjusts, at 1020, the reservation status of the transmission resource to the first UE (UE 1002), the first UE (UE 1002) may adjust, based on the COT-SI (received at 1014), the reservation status of the transmission resource to the first UE. Referring to FIG. 7, the first UE may adjust, based on the COT-SI (received from UE 712), the reservation status of the transmission resource (slot 9) to the first UE.

[0129] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust, in response to the COT-SI including a future reservation release indication, the reservation status of the transmission resource to the first UE in order to make the transmission resource available to the first UE. For example, referring to FIG. 7, the first UE may adjust, in response to the COT-SI (received from UE 712) including a future reservation release indication, the reservation status of the transmission resource (slot 9) to the first UE in order to make the transmission resource (slot 9) available to the first UE.

[0130] In some aspects, to adjust the reservation status of the transmission resource to the first UE, the first UE may be configured to: maintain, in response to the COT-SI including a future reservation non-release indication, the reservation status of the transmission resource as being unavailable to the first UE. For example, referring to FIG. 7, the first UE may maintain, in response to the COT-SI (received from UE 712) including a future reservation non-release indication, the reservation status of the transmission resource (slot 9) as being unavailable to the first UE.

[0131] In some aspects, to adjust, based on the COT-SI, the reservation status of the transmission resource to the first UE, the first UE may be configured to: adjust, based on the COT-SI and the second UE being one UE of a subset of candidate UEs, the reservation status of the transmission resource to the first UE. The subset of the candidate UEs is indicated by one or more of the COT-SI; a set of UE IDs identifying the subset of candidate UEs; or a group ID identifying the subset of candidate UEs. For example, referring to FIG. 7, the first UE may adjust, based on the COT-SI (received from UE 712) and the second UE (UE 711) being one UE of a subset of candidate UEs, the reservation status of the transmission resource (slot 9) to the first UE. The subset of the candidate UEs may be indicated by one or more of the COT- SI (received from UE 712); a set of UE IDs identifying the subset of candidate UEs; or a group ID identifying the subset of candidate UEs.

[0132] At 1206, the first UE may receive a release indication for a release of the transmission resource. The reservation status of the transmission resource is adjusted to the first UE based on the release indication. For example, referring to FIG. 10, the first UE (UE 1002) may receive, at 1018, a release indication (from UE 1006) for a release of the transmission resource. Referring to FIG. 9, the first UE may receive a release indication (from UE 911) for a release of the transmission resource (slot 9). The reservation status of the transmission resource (slot 9) may be adjusted to the first UE based on the release indication. In some aspects, 1206 may be performed by the resource reservation management component 198.

[0133] In some aspects, the release indication is included in a control field of a first transmission of the second UE utilizing the COT, and the release indication indicates a first number of transmission resources reserved by the second UE after the COT, where the first number of transmission resources are available to the first UE. For example, referring to FIG. 10, when the first UE (UE 1002) receives the release indication at 1018, the release indication may be included in a control field of a first transmission of the second UE (UE 1006) utilizing the COT, and the release indication may indicate a first number of transmission resources reserved by the second UE (UE 1006) after the COT, where the first number of transmission resources are available to the first UE (UE 1002).

[0134] In some aspects, the release indication is included in a frequency domain resource allocation (FDRA) indication or a time domain resource allocation (TDRA) indication of a first transmission of the second UE utilizing the COT, and the reservation status of the transmission resource is adjusted to be available to the first UE if the FDRA indication or the TDRA indication identifying the transmission resource is received from the second UE for a second time. For example, referring to FIG. 10, when the first UE (UE 1002) receives the release indication at 1018, the release indication may be included in an FDRA indication or a TDRA indication of a first transmission of the second UE (UE 1006) utilizing the COT. The reservation status of the transmission resource may be adjusted (at 1020) to be available to the first UE (UE 1002) if the FDRA indication or the TDRA indication identifying the transmission resource is received from the second UE (UE 1006) for a second time.

[0135] FIG. 13 is a flowchart 1300 illustrating methods of wireless communication at a first UE in accordance with various aspects of the present disclosure. The method may be performed by the first UE. The first UE may be the UE 104, 350, 1006, or the apparatus 1504 in the hardware implementation of FIG. 15. The method enables one UE to use a transmission resource reserved by another UE based on another UE’s utilization of a preceding transmission resource (e.g., a COT). The method enables more efficient utilization of transmission resources and improves the efficiency of wireless communication.

[0136] As shown in FIG. 13, at 1302, the first UE may reserve a transmission resource for communication. FIGs. 7, 8, 9, and 10 illustrate various aspects of the steps in connection with flowchart 1300. For example, referring to FIG. 10, the first UE (UE 1006) may reserve, at 1010, a transmission resource for communication. Referring to FIGs. 7, 8, and 9, the first UE (UE 711, 811, 911) may reserve a transmission resource (slot 9) for communication. In some aspects, 1302 may be performed by the resource reservation management component 198.

[0137] At 1304, the first UE may utilize a COT located before the transmission resource for the communication. The utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE. For example, referring to FIG. 10, the first UE (UE 1006) may utilize, at 1012, a COT located before the transmission resource for the communication. Referring to FIG. 7, the first UE (UE 711) may utilize a COT 720 located before the transmission resource (slot 9) for the communication. The utilization of the COT 720 may correspond to a reservation status of the transmission resource (slot 9) being adjusted to a second UE (a resourceseeking UE, not shown in FIG. 7). In some aspects, 1304 may be performed by the resource reservation management component 198.

[0138] FIG. 14 is a flowchart 1400 illustrating methods of wireless communication at a first UE in accordance with various aspects of the present disclosure. The method may be performed by the first UE. The first UE may be the UE 104, 350, 1006, or the apparatus 1504 in the hardware implementation of FIG. 15. The method enables one UE to use a transmission resource reserved by another UE based on another UE’s utilization of a preceding transmission resource (e.g., a COT). The method enables more efficient utilization of transmission resources and improves the efficiency of wireless communication.

[0139] As shown in FIG. 14, at 1402, the first UE may reserve a transmission resource for communication. FIGs. 7, 8, 9, and 10 illustrate various aspects of the steps in connection with flowchart 1400. For example, referring to FIG. 10, the first UE (UE 1006) may reserve, at 1010, a transmission resource for communication. Referring to FIGs. 7, 8, and 9, the first UE (UE 711, 811, 911) may reserve a transmission resource (slot 9) for communication. In some aspects, 1402 may be performed by the resource reservation management component 198.

[0140] At 1404, the first UE may utilize a COT located before the transmission resource for the communication. The utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE. For example, referring to FIG. 10, the first UE (UE 1006) may utilize, at 1012, a COT located before the transmission resource for the communication. Referring to FIG. 7, the first UE (UE 711) may utilize a COT 720 located before the transmission resource (slot 9) for the communication. The utilization of the COT 720 may correspond to a reservation status of the transmission resource (slot 9) being adjusted to a second UE (a resourceseeking UE, not shown in FIG. 7). In some aspects, 1404 may be performed by the resource reservation management component 198.

[0141] At 1406, the first UE may transmit, upon utilizing the COT, a future reservation release indication for a release of the transmission resource to the second UE. The reservation status of the transmission resource may be adjusted to the second UE based on the future reservation release indication. For example, referring to FIG. 10, the first UE (UE 1006) may transmit, at 1018, upon utilizing the COT (at 1012), a future reservation release indication (the release indication of 1018) for a release of the transmission resource to the second UE (UE 1002). The reservation status of the transmission resource may be adjusted (at 1020) to the second UE (UE 1002) based on the future reservation release indication (the release indication of 1018). Referring to FIG. 9, the first UE (UE 911) may transmit, upon utilizing the COT 920, a future reservation release indication for a release of the transmission resource (slot 9) to the second UE (a resource-seeking UE, not shown in FIG. 9). The reservation status of the transmission resource (slot 9) may be adjusted to the second UE (the resourceseeking UE) based on the future reservation release indication. In some aspects, 1406 may be performed by the resource reservation management component 198.

[0142] In some aspects, to adjust the reservation status of the transmission resource to the second UE, the first UE may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority. For example, referring to FIG. 10, to adjust (at 1020) the reservation status of the transmission resource to the second UE (UE 1002), the first UE (UE 1006) may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority. Referring to FIG. 7, to adjust the reservation status of the transmission resource to the second UE (a resource-seeking UE, not shown in FIG. 7), the first UE (UE 711) may be configured to: adjust an original RSRP associated with a reservation transmission reserving the transmission resource (slot 9) to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource (slot 9) to an adjusted priority lower than the original priority.

[0143] In some aspects, the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP may be a first preconfigured number or a first predetermined number, and the adjusted priority or a priority difference between the original priority and the adjusted priority may be a second preconfigured number or a second predetermined number. [0144] In some aspects, the reservation status of the transmission resource to the second UE is adjusted by: adjusting, in response to the transmission resource being one of a number of first transmission resources reserved by the first UE after the COT, the reservation status of the transmission resource to the second UE. The number of first transmission resources may be one or more of: a preconfigured number or a predetermined number, the number based on a duration of a part of the COT which the first UE is eligible to utilize, the number of resource reservations made by the first UE in the COT, the number of non-reserved transmissions made by the first UE in the COT, or the number of first transmissions after the COT occurring within a time interval after the COT. For example, referring to FIG. 8, the reservation status of the transmission resource (slot 9) to the second UE (a resource-seeking UE, not shown in FIG. 8) may be adjusted by: adjusting, in response to the transmission resource (slot 9) being one of a number of first transmission resources reserved by the first UE (UE 811) after the COT 820, the reservation status of the transmission resource (slot 9) to the second UE (the resource-seeking UE). Referring to FIG. 8, the number of first transmission resources may be one, which may be a preconfigured number or a predetermined number. The number of first transmission resources may be based on a duration of a part of the COT 820 which the first UE (UE 811) is eligible to utilize (e.g., the first UE (UE 811) may be eligible to utilize one slot (slot 6) of the three slots (slots 5-7) of the COT 820), the maximum number of resources in the part of the COT 820 which the first UE (UE 811) is eligible to utilize, the number of resource reservations made by the first UE (UE 811) in the COT 820, the number of nonreserved transmissions made by the first UE (UE 811) in the COT 820, or the number of first transmissions after the COT 820 occurring within a time interval after the COT 820.

[0145] In some aspects, the reservation status of the transmission resource to the second UE is adjusted by: adjusting, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the second UE. For example, referring to FIG. 10, the reservation status of the transmission resource may be adjusted (at 1020) by adjusting, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the second UE (UE 1002). Referring to FIG. 7, the reservation status may be adjusted, in response to a reservation period associated with the transmission resource (slot 9) being less than a period threshold.

[0146] In some aspects, to adjust the reservation status of the transmission resource to the second UE, the first UE may be configured to: adjust, in response to the COT-SI included in a COT-initiating transmission initiating the COT including a future reservation release indication, the reservation status of the transmission resource in order to make the transmission resource available to the second UE; or maintain, based on the COT-SI including a future reservation non-release indication, the transmission resource as being unavailable to the second UE. For example, referring to FIG. 7, to adjust the reservation status of the transmission resource (slot 9) to the second UE (a resource-seeking UE, not shown in FIG. 7), the first UE 711 may be configured to: adjust, in response to the COT-SI included in a COT-initiating transmission initiating the COT 720 (received from UE712) including a future reservation release indication, the reservation status of the transmission resource (slot 9) in order to make the transmission resource available to the second UE (the resourceseeking UE); or maintain, based on the COT-SI including a future reservation nonrelease indication, the transmission resource (slot 9) as being unavailable to the second UE (the resource-seeking UE).

[0147] In some aspects, the future reservation release indication is included in a control field of a first transmission of the first UE utilizing the COT, and the future reservation release indication indicates a first number of transmission resources reserved by the first UE after the COT, where the first number of transmission resources are available to the second UE. For example, referring to FIG. 10, when the first UE (UE 1006) transmits the future reservation release indication at 1018, the future reservation release indication may be included in a control field of a first transmission of the first UE (UE 1006) utilizing the COT, and the future reservation release indication may indicate a first number of transmission resources reserved by the first UE (UE 1006) after the COT. The first number of transmission resources are available to the second UE (UE 1002).

[0148] In some aspects, the future reservation release indication is included in a frequency domain resource allocation (FDRA) indication or a time domain resource allocation (TDRA) indication of a first transmission of the first UE utilizing the COT, and the first UE may be configured to adjust the reservation status of the transmission resource to be available to the second UE if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the first UE for a second time. For example, referring to FIG. 10, when the first UE (UE 1006) transmits the future reservation release indication at 1018, the future reservation release indication may be included in an FDRA indication or a TDRA indication of a first transmission of the first UE (UE 1006) utilizing the COT, and, the first UE (UE 1006) may be configured to adjust the reservation status of the transmission resource (at 1020) to be available to the second UE (UE 1002) if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the first UE (UE 1006) for a second time.

[0149] FIG. 15 is a diagram 1500 illustrating an example of a hardware implementation for an apparatus 1504. The apparatus 1504 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus 1504 may include a cellular baseband processor 1524 (also referred to as a modem) coupled to one or more transceivers 1522 (e.g., cellular RF transceiver). The cellular baseband processor 1524 may include on-chip memory 1524'. In some aspects, the apparatus 1504 may further include one or more subscriber identity modules (SIM) cards 1520 and an application processor 1506 coupled to a secure digital (SD) card 1508 and a screen 1510. The application processor 1506 may include on-chip memory 1506'. In some aspects, the apparatus 1504 may further include a Bluetooth module 1512, a WLAN module 1514, an SPS module 1516 (e.g., GNSS module), one or more sensor modules 1518 (e.g., barometric pressure sensor / altimeter; motion sensor such as inertial measurement unit (IMU), gyroscope, and/or accelerometer(s); light detection and ranging (LIDAR), radio assisted detection and ranging (RADAR), sound navigation and ranging (SONAR), magnetometer, audio and/or other technologies used for positioning), additional memory modules 1526, a power supply 1530, and/or a camera 1532. The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include an on-chip transceiver (TRX) (or in some cases, just a receiver (RX)). The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include their own dedicated antennas and/or utilize the antennas 1580 for communication. The cellular baseband processor 1524 communicates through the transceiver s) 1522 via one or more antennas 1580 with the UE 104 and/or with an RU associated with a network entity 1502. The cellular baseband processor 1524 and the application processor 1506 may each include a computer-readable medium / memory 1524', 1506', respectively. The additional memory modules 1526 may also be considered a computer-readable medium / memory. Each computer- readable medium / memory 1524', 1506', 1526 may be non-transitory. The cellular baseband processor 1524 and the application processor 1506 are each responsible for general processing, including the execution of software stored on the computer- readable medium / memory. The software, when executed by the cellular baseband processor 1524 / application processor 1506, causes the cellular baseband processor 1524 / application processor 1506 to perform the various functions described supra. The computer-readable medium / memory may also be used for storing data that is manipulated by the cellular baseband processor 1524 / application processor 1506 when executing software. The cellular baseband processor 1524 / application processor 1506 may be a component of the UE 350 and may include the memory 360 and/or at least one of the TX processor 368, the RX processor 356, and the controller/processor 359. In one configuration, the apparatus 1504 may be a processor chip (modem and/or application) and include just the cellular baseband processor 1524 and/or the application processor 1506, and in another configuration, the apparatus 1504 may be the entire UE (e.g., see UE 350 of FIG. 3) and include the additional modules of the apparatus 1504.

[0150] As discussed supra, in some aspects, the component 198 may be configured to detect whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and perform sidelink communication based on the adjusted reservation status of the transmission resource. In some aspects, the component 198 may be configured to reserve a transmission resource for communication; and utilize a COT located before the transmission resource for the communication, where the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE.

[0151] The component 198 may be further configured to perform any of the aspects described in connection with the flowcharts in FIG. 11, FIG. 12, FIG. 13, FIG. 14 and/or performed by the UE 1002 in FIG. 10, and UE 1006 in FIG. 10. The component 198 may be within the cellular baseband processor 1524, the application processor 1506, or both the cellular baseband processor 1524 and the application processor 1506. The component 198 may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer- readable medium for implementation by one or more processors, or some combination thereof. As shown, the apparatus 1504 may include a variety of components configured for various functions. In one configuration, the apparatus 1504, and in particular the cellular baseband processor 1524 and/or the application processor 1506, includes means for detecting whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication, means for adjusting, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE, and means for performing sidelink communication based on the adjusted reservation status of the transmission resource. In some aspects, the apparatus 1504 may include means for reserving a transmission resource for communication, and means for utilizing a COT located before the transmission resource for the communication, where the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE. The apparatus 1504 may further include means for performing any of the aspects described in connection with the flowcharts in FIG. 11, FIG. 12, FIG. 13, FIG. 14, and/or aspects performed by the UE 1002 in FIG. 10 and UE 1006 in FIG. 10. The means may be the component 198 of the apparatus 1504 configured to perform the functions recited by the means. As described supra, the apparatus 1504 may include the TX processor 368, the RX processor 356, and the controller/processor 359. As such, in one configuration, the means may be the TX processor 368, the RX processor 356, and/or the controller/processor 359 configured to perform the functions recited by the means. [0152] FIG. 16 is a diagram 1600 illustrating an example of a hardware implementation for a network entity 1602. The network entity 1602 may be a BS, a component of a BS, or may implement BS functionality. The network entity 1602 may include at least one of a CU 1610, a DU 1630, or an RU 1640. For example, depending on the layer functionality handled by the component 199, the network entity 1602 may include the CU 1610; both the CU 1610 and the DU 1630; each of the CU 1610, the DU 1630, and the RU 1640; the DU 1630; both the DU 1630 and the RU 1640; or the RU 1640. The CU 1610 may include a CU processor 1612. The CU processor 1612 may include on-chip memory 1612'. In some aspects, the CU 1610 may further include additional memory modules 1614 and a communications interface 1618. The CU 1610 communicates with the DU 1630 through a midhaul link, such as an Fl interface. The DU 1630 may include a DU processor 1632. The DU processor 1632 may include on- chip memory 1632'. In some aspects, the DU 1630 may further include additional memory modules 1634 and a communications interface 1638. The DU 1630 communicates with the RU 1640 through a fronthaul link. The RU 1640 may include an RU processor 1642. The RU processor 1642 may include on-chip memory 1642'. In some aspects, the RU 1640 may further include additional memory modules 1644, one or more transceivers 1646, antennas 1680, and a communications interface 1648. The RU 1640 communicates with the UE 104. The on-chip memory 1612', 1632', 1642' and the additional memory modules 1614, 1634, 1644 may each be considered a computer-readable medium / memory. Each computer-readable medium / memory may be non -transitory. Each of the processors 1612, 1632, 1642 is responsible for general processing, including the execution of software stored on the computer- readable medium / memory. The software, when executed by the corresponding processor(s) causes the processor(s) to perform the various functions described supra. The computer-readable medium / memory may also be used for storing data that is manipulated by the processor(s) when executing software.

[0153] The component 199 may be within one or more processors of one or more of the CU 1610, DU 1630, and the RU 1640. The component 199 may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by one or more processors, or some combination thereof. The network entity 1602 may include a variety of components configured for various functions. The means may be the component 199 of the network entity 1602 configured to perform the functions recited by the means. As described supra, the network entity 1602 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the means may be the TX processor 316, the RX processor 370, and/or the controller/processor 375 configured to perform the functions recited by the means.

[0154] This disclosure provides a method for wireless communication at a UE. The method may include detecting whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjusting, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and performing sidelink communication based on the adjusted reservation status of the transmission resource. The method enables one UE to use a transmission resource reserved by another UE based on another UE’s utilization of a preceding transmission resource (e.g., a COT). The method enables more efficient utilization of transmission resources and improves the efficiency of wireless communication.

[0155] It is understood that the specific order or hierarchy of blocks in the processes / flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes / flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not limited to the specific order or hierarchy presented.

[0156] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not limited to the aspects described herein, but are to be accorded the full scope consistent with the language claims. Reference to an element in the singular does not mean “one and only one” unless specifically so stated, but rather “one or more.” Terms such as “if,” “when,” and “while” do not imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when,” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof’ include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof’ may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. Sets should be interpreted as a set of elements where the elements number one or more. Accordingly, for a set of X, X would include one or more elements. If a first apparatus receives data from or transmits data to a second apparatus, the data may be received/transmitted directly between the first and second apparatuses, or indirectly between the first and second apparatuses through a set of apparatuses. A device configured to “output” data, such as a transmission, signal, or message, may transmit the data, for example with a transceiver, or may send the data to a device that transmits the data. A device configured to “obtain” data, such as a transmission, signal, or message, may receive, for example with a transceiver, or may obtain the data from a device that receives the data. Information stored in a memory includes instructions and/or data. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are encompassed by the claims. Moreover, nothing disclosed herein is dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”

[0157] As used herein, the phrase “based on” shall not be construed as a reference to a closed set of information, one or more conditions, one or more factors, or the like. In other words, the phrase “based on A” (where “A” may be information, a condition, a factor, or the like) shall be construed as “based at least on A” unless specifically recited differently.

[0158] The following aspects are illustrative only and may be combined with other aspects or teachings described herein, without limitation.

[0159] Aspect 1 is a method of wireless communication at a first UE. The method may include detecting whether a second UE is eligible for utilizing a COT, where a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjusting, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and performing sidelink communication based on the adjusted reservation status of the transmission resource.

[0160] Aspect 2 is the method of aspect 1, where the method may further include receiving a COT-initiating transmission including COT-SI. The detection of whether the second UE is eligible for utilizing the COT may be based on the COT-SI,

[0161] Aspect 3 is the method of aspect 1, where detecting whether the second UE is eligible for utilizing the COT may include: identifying the second UE based on SCI associated with the transmission resource.

[0162] Aspect 4 is the method of aspect 2, where adjusting the reservation status of the transmission resource to the first UE may include: adjusting an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjusting an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority.

[0163] Aspect 5 is the method of aspect 4, where the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP may be a preconfigured number or a predetermined number.

[0164] Aspect 6 is the method of aspect 4, where the adjusted priority or a priority difference between the original priority and the adjusted priority may be a preconfigured number or a predetermined number.

[0165] Aspect 7 is the method of any of aspects 1 to 2, where adjusting the reservation status of the transmission resource to the first UE may include: adjusting, in response to the transmission resource being one of a number of first transmission resources reserved by the second UE after the COT, the reservation status of the transmission resource to the first UE.

[0166] Aspect 8 is the method of aspect 7, where the number of first transmission resources may be a preconfigured number or a predetermined number.

[0167] Aspect 9 is the method of aspect 7, where the first number of first transmission resources may be based on a duration of a part of the COT which the second UE is eligible to utilize.

[0168] Aspect 10 is the method of aspect 9, where the number of first transmission resources may be based on the maximum number of resources in the part of the COT which the second UE is eligible to utilize. [0169] Aspect 11 is the method of aspect 7, where the number of first transmission resources may be based on one or more of: the number of resource reservations made by the second UE in the COT; the number of non-reserved transmissions made by the second UE in the COT; or the number of first transmissions after the COT occurring within a time interval after the COT.

[0170] Aspect 12 is the method any of aspects 1 to 2, where adjusting the reservation status of the transmission resource to the first UE may include: adjusting, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the first UE.

[0171] Aspect 13 is the method of aspect 2, where adjusting the reservation status of the transmission resource to the first UE may include: adjusting, based on the COT-SI, the reservation status of the transmission resource to the first UE.

[0172] Aspect 14 is the method of aspect 13, where adjusting the reservation status of the transmission resource to the first UE may include: adjusting, in response to the COT- SI including a future reservation release indication, the reservation status of the transmission resource to the first UE in order to make the transmission resource available to the first UE.

[0173] Aspect 15 is the method of aspect 13, where adjusting the reservation status of the transmission resource to the first UE may include: maintaining, in response to the COT-SI including a future reservation non-release indication, the reservation status of the transmission resource as being unavailable to the first UE.

[0174] Aspect 16 is the method of aspect 13, where adjusting, based on the COT-SI, the reservation status of the transmission resource to the first UE may include: adjusting, based on the COT-SI and the second UE being one UE of a subset of candidate UEs, the reservation status of the transmission resource to the first UE. The subset of the candidate UEs may be indicated by one or more of: the COT-SI, a set of UE IDs identifying the subset of candidate UEs, or a group ID identifying the subset of candidate UEs.

[0175] Aspect 17 is the method of any of aspects 1 to 2, where the method may further include receiving a release indication for a release of the transmission resource. The reservation status of the transmission resource may be adjusted to the first UE based on the release indication.

[0176] Aspect 18 is the method of aspect 17, where the release indication may be included in a control field of a first transmission of the second UE utilizing the COT, and the release indication may indicate a first number of transmission resources reserved by the second UE after the COT. The first number of transmission resources may be available to the first UE.

[0177] Aspect 19 is the method of aspect 17, where the release indication may be included in an FDRA indication or a TDRA indication of a first transmission of the second UE utilizing the COT, and the reservation status of the transmission resource may be adjusted to be available to the first UE if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the second UE for a second time.

[0178] Aspect 20 is an apparatus for wireless communication at a UE, including: a memory; and at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to perform the method of any of aspects 1-19.

[0179] Aspect 21 is the apparatus of aspect 20, further including at least one of a transceiver or an antenna coupled to the at least one processor and configured to perform sidelink communication.

[0180] Aspect 22 is an apparatus for wireless communication including means for implementing the method of any of aspects 1-19.

[0181] Aspect 23 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer executable code, where the code when executed by a processor causes the processor to implement the method of any of aspects 1-19.

[0182] Aspect 24 is a method of wireless communication at a first UE. The method may include reserving a transmission resource for communication; and utilizing a COT located before the transmission resource for the communication, where the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE.

[0183] Aspect 25 is the method of aspect 24, where adjusting the reservation status of the transmission resource to the second UE may include: adjusting an original RSRP associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjusting an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority.

[0184] Aspect 26 is the method of aspect 25, where the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP may be a first preconfigured number or a first predetermined number, and the adjusted priority or a priority difference between the original priority and the adjusted priority may be a second preconfigured number or a second predetermined number.

[0185] Aspect 27 is the method of aspect 24, where the reservation status of the transmission resource to the second UE may be adjusted by: adjusting, in response to the transmission resource being one of the number of first transmission resources reserved by the first UE after the COT, the reservation status of the transmission resource to the second UE. The number of first transmission resources may be one or more of a preconfigured number or a predetermined number, a number based on a duration of a part of the COT which the first UE is eligible to utilize, the number of resource reservations made by the first UE in the COT, the number of non-reserved transmissions made by the first UE in the COT, or the number of first transmissions after the COT occurring within a time interval after the COT.

[0186] Aspect 28 is the method of aspect 24, where the reservation status of the transmission resource to the second UE may be adjusted by: adjusting, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the second UE.

[0187] Aspect 29 is the method of aspect 24, where the reservation status of the transmission resource to the second UE may be adjusted by: adjusting, in response to the COT-SI included in a COT-initiating transmission the COT including a future reservation release indication, the reservation status of the transmission resource in order to make the transmission resource available to the second UE; or maintaining, based on the COT-SI including a future reservation non-release indication, the transmission resource as being unavailable to the second UE.

[0188] Aspect 30 is the method of any of aspects 24 to 29, where the method may further include transmitting, upon utilizing the COT, a future reservation release indication for a release of the transmission resource to the second UE. The reservation status of the transmission resource may be adjusted to the second UE based on the release indication.

[0189] Aspect 31 is the method of aspect 30, where the future reservation release indication may be included in a control field of a first transmission of the first UE utilizing the COT, and the future reservation release indication may indicate a first number of transmission resources reserved by the first UE after the COT. The first number of transmission resources may be available to the second UE. [0190] Aspect 32 is the method of aspect 30, where the future reservation release indication may be included in an FDRA indication or a TDRA indication of a first transmission of the first UE utilizing the COT, and the reservation status of the transmission resource may be adjusted to be available to the second UE if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the first UE for a second time.

[0191] Aspect 33 is an apparatus for wireless communication at a UE, including: a memory; and at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to perform the method of any of aspects 24-32.

[0192] Aspect 34 is the apparatus of aspect 33, further including at least one of a transceiver or an antenna coupled to the at least one processor and configured to reserve the transmission resource.

[0193] Aspect 35 is an apparatus for wireless communication including means for implementing the method of any of aspects 24-32.

[0194] Aspect 36 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer executable code, where the code when executed by a processor causes the processor to implement the method of any of aspects 24-32.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. An apparatus for wireless communication at a first user equipment (UE), comprising: memory; and at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to: detect whether a second UE is eligible for utilizing a channel occupancy time (COT), wherein a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjust, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and perform sidelink communication based on the adjusted reservation status of the transmission resource.

2. The apparatus of claim 1, further comprising a transceiver coupled to the at least one processor, wherein, to perform the sidelink communication, the at least one processor is configured to perform the sidelink communication via the transceiver, and wherein the at least one processor is further configured to: receive a COT-initiating transmission comprising COT system information (COT-SI), wherein the detection of whether the second UE is eligible for utilizing the COT is based on the COT-SI.

3. The apparatus of claim 2, wherein, to detect whether the second UE is eligible for utilizing the COT, the at least one processor is configured to: identify the second UE based on sidelink control information (SCI) associated with the transmission resource.

4. The apparatus of claim 2, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust an original reference signal received power (RSRP) associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority.

5. The apparatus of claim 4, wherein the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP is a preconfigured number or a predetermined number.

6. The apparatus of claim 4, wherein the adjusted priority or a priority difference between the original priority and the adjusted priority is a preconfigured number or a predetermined number.

7. The apparatus of claim 2, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust, in response to the transmission resource being one of a number of first transmission resources reserved by the second UE after the COT, the reservation status of the transmission resource to the first UE.

8. The apparatus of claim 7, wherein the number of first transmission resources is a preconfigured number or a predetermined number.

9. The apparatus of claim 7, wherein the number of first transmission resources is based on a duration of a part of the COT which the second UE is eligible to utilize.

10. The apparatus of claim 9, wherein the number of first transmission resources is based on a maximum number of resources in the part of the COT which the second UE is eligible to utilize.

11. The apparatus of claim 7, wherein the number of first transmission resources is based on one or more of: a number of resource reservations made by the second UE in the COT; a number of non-reserved transmissions made by the second UE in the COT; or a number of first transmissions after the COT occurring within a time interval after the COT.

12. The apparatus of claim 2, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the first UE.

13. The apparatus of claim 2, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust, based on the COT-SI, the reservation status of the transmission resource to the first UE.

14. The apparatus of claim 13, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust, in response to the COT-SI comprising a future reservation release indication, the reservation status of the transmission resource to the first UE in order to make the transmission resource available to the first UE.

15. The apparatus of claim 13, wherein, to adjust the reservation status of the transmission resource to the first UE, the at least one processor is configured to: maintain, in response to the COT-SI comprising a future reservation non-release indication, the reservation status of the transmission resource as being unavailable to the first UE.

16. The apparatus of claim 13, wherein, to adjust, based on the COT-SI, the reservation status of the transmission resource to the first UE, the at least one processor is configured to: adjust, based on the COT-SI and the second UE being one UE of a subset of candidate UEs, the reservation status of the transmission resource to the first UE, wherein the subset of the candidate UEs is indicated by one or more of: the COT-SI; a set of UE IDs identifying the subset of candidate UEs; or a group ID identifying the subset of candidate UEs.

17. The apparatus of claim 1, wherein the at least one processor is further configured to: receive a release indication for a release of the transmission resource, and wherein the reservation status of the transmission resource is adjusted to the first UE based on the release indication.

18. The apparatus of claim 17, wherein the release indication is included in a control field of a first transmission of the second UE utilizing the COT, and the release indication indicates a first number of transmission resources reserved by the second UE after the COT, wherein the first number of transmission resources are available to the first UE.

19. The apparatus of claim 17, wherein the release indication is included in a frequency domain resource allocation (FDRA) indication or a time domain resource allocation (TDRA) indication of a first transmission of the second UE utilizing the COT, and wherein the at least one processor is configured to adjust the reservation status of the transmission resource to be available to the first UE if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the second UE for a second time.

20. An apparatus for wireless communication at a first user equipment (UE), comprising: memory; and at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to: reserve a transmission resource for communication; and utilize a channel occupancy time (COT) located before the transmission resource for the communication, wherein the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE.

21. The apparatus of claim 20, wherein to adjust the reservation status of the transmission resource to the second UE, the at least one processor is configured to one or more of: adjust an original reference signal received power (RSRP) associated with a reservation transmission reserving the transmission resource to an adjusted RSRP lower than the original RSRP; or adjust an original priority associated with the reservation transmission reserving the transmission resource to an adjusted priority lower than the original priority.

22. The apparatus of claim 21, wherein the adjusted RSRP or an RSRP difference between the original RSRP and the adjusted RSRP is a first preconfigured number or a first predetermined number, and wherein the adjusted priority or a priority difference between the original priority and the adjusted priority is a second preconfigured number or a second predetermined number.

23. The apparatus of claim 20, wherein, to adjust the reservation status of the transmission resource to the second UE, the at least one processor is configured to: adjust, in response to the transmission resource being one of a number of first transmission resources reserved by the first UE after the COT, the reservation status of the transmission resource to the second UE, wherein the number of first transmission resources is one or more of: a preconfigured number or a predetermined number, a number based on a duration of a part of the COT which the first UE is eligible to utilize, a number of resource reservations made by the first UE in the COT, a number of non-reserved transmissions made by the first UE in the COT, or a number of first transmissions after the COT occurring within a time interval after the COT.

24. The apparatus of claim 20, wherein the reservation status of the transmission resource to the second UE is adjusted by: adjusting, in response to a reservation period associated with the transmission resource being less than a period threshold, the reservation status of the transmission resource to the second UE.

25. The apparatus of claim 20, wherein, to adjust the reservation status of the transmission resource to the second UE, the at least one processor is configured to: adjust, in response to COT system information (COT-SI) included in a COT- initiating transmission initiating the COT comprising a future reservation release indication, the reservation status of the transmission resource in order to make the transmission resource available to the second UE; or maintain, based on the COT-SI comprising a future reservation non-release indication, the transmission resource as being unavailable to the second UE.

26. The apparatus of claim 20, wherein the at least one processor is further configured to: transmit, upon utilizing the COT, a future reservation release indication for a release of the transmission resource to the second UE, and wherein the reservation status of the transmission resource is adjusted to the second UE based on the future reservation release indication.

27. The apparatus of claim 26, wherein the future reservation release indication is included in a control field of a first transmission of the first UE utilizing the COT, and the future reservation release indication indicates a first number of transmission resources reserved by the first UE after the COT, wherein the first number of transmission resources are available to the second UE.

28. The apparatus of claim 26, wherein the future reservation release indication is included in a frequency domain resource allocation (FDRA) indication or a time domain resource allocation (TDRA) indication of a first transmission of the first UE utilizing the COT, and wherein the at least one processor is configured to adjust the reservation status of the transmission resource to be available to the second UE if the FDRA indication or the TDRA indication identifying the transmission resource is configured to be received from the first UE for a second time.

29. A method of wireless communication at a first user equipment (UE), comprising: detecting whether a second UE is eligible for utilizing a channel occupancy time

(COT), wherein a transmission resource reserved by the second UE is located after the COT and unavailable to the first UE for communication; adjusting, in response to the second UE being eligible for utilizing the COT, a reservation status of the transmission resource to the first UE such that the transmission resource becomes available to the first UE; and performing sidelink communication based on the adjusted reservation status of the transmission resource.

30. A method of wireless communication at a first user equipment (UE), comprising: reserving a transmission resource for communication; and utilizing a channel occupancy time (COT) located before the transmission resource for the communication, wherein the utilization of the COT corresponds to a reservation status of the transmission resource being adjusted to a second UE.