Frequency resource reservation for sidelink communication

Abstract

Wireless communications systems and methods related to frequency resource reservation for sidelink communications over a shared radio frequency band are provided. A first user equipment (UE) senses in a pool of sidelink resources within a shared radio frequency band. The first UE reserves, based on the sensing, a frequency resource of the pool of sidelink resources for an instance of a variable time range. The first UE performs one or more listen before talk (LBT) in the shared radio frequency band. The first UE transmits, based on the one or more LBT, a sidelink transmission to a second UE using the frequency resource for the instance of the variable time range.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to U.S. Patent Application No. 17 / 305,455, filed July 7, 2021, and U.S. Provisional Application No. 62 / 706,688, filed September 2, 2020, the entire contents of which are incorporated herein by reference as fully set forth herein and for all applicable purposes. Technical Field

[0003] This application relates to wireless communication systems, and more particularly to frequency resource reservation for sidelink communication over a shared radio frequency band.

[0004] introduction

[0005] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, message sending and receiving, broadcasting, and so on. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Wireless multiple access communication systems may include several base stations (BSs), each supporting communication from multiple communication devices simultaneously, which may also be referred to as user equipment (UEs).

[0006] To meet the growing demand for extended mobile broadband connectivity, wireless communication technologies are evolving from Long Term Evolution (LTE) to Next Generation New Radio (NR), often referred to as fifth generation (5G). For example, NR is designed to offer lower latency, higher bandwidth or throughput, and greater reliability compared to LTE. NR is designed to operate across a wide range of frequency bands, from low-frequency bands below approximately 1 GHz and mid-frequency bands from approximately 1 GHz to approximately 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing allows operators to opportunistically pool spectrum to dynamically support high-bandwidth services. Spectrum sharing can extend the benefits of NR technology to operating entities that may not have access to licensed spectrum.

[0007] In wireless communication networks, a Base Station (BS) can communicate with a UE in both uplink and downlink directions. Sidelinks were introduced in LTE to allow a UE to send data to another UE without tunneling through the BS and / or the associated core network. LTE sidelink technology has been extended to provide device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, and / or cellular vehicle-to-everything (C-V2X) communication. Similarly, NR can be extended to support sidelink communication, D2D communication, V2X communication, and / or C-V2X on licensed and / or unlicensed frequency bands.

[0008] A brief overview of some examples

[0009] The following outlines some aspects of this disclosure to provide a basic understanding of the techniques discussed. This overview is not an exhaustive summary of all conceived features of this disclosure, and is neither intended to identify all key or decisive elements of all aspects of this disclosure, nor to define the scope of any or all aspects of this disclosure. Its sole purpose is to provide, in an overview form, some concepts of one or more aspects of this disclosure as a prelude to the more detailed description that follows.

[0010] For example, in one aspect of this disclosure, a wireless communication method performed by a user equipment (UE) includes: sensing a sidelink resource pool within a shared radio frequency band; reserving frequency resources of the sidelink resource pool within an instance of a variable time range based on the sensing; performing one or more Listen-Before-Talk (LBT) operations within the shared radio frequency band; and transmitting a sidelink transmission to a second UE using the frequency resources within the instance of the variable time range based on the one or more LBT operations.

[0011] In an additional aspect of this disclosure, a first user equipment (UE) includes: a processor configured to: sense a sidelink resource pool within a shared radio frequency band; reserve frequency resources of the sidelink resource pool within an instance of a variable time range based on the sensing; and perform one or more Listen-Before-Talk (LBT) operations within the shared radio frequency band; and a transceiver configured to: transmit sidelink transmissions to a second UE using the frequency resources within the instance of the variable time range based on the one or more LBT operations.

[0012] In an additional aspect of this disclosure, a non-transient computer-readable medium having program code recorded thereon, the program code including code for causing a first user equipment (UE) to sense in a sidelink resource pool within a shared radio frequency band; code for causing the first UE to reserve frequency resources of the sidelink resource pool within a variable time range based on the sensing; code for causing the first UE to perform one or more Listen-Before-Talk (LBT) operations in the shared radio frequency band; and code for causing the first UE to use the frequency resources to transmit a sidelink transmission to a second UE within the variable time range based on the one or more LBT operations.

[0013] In an additional aspect of this disclosure, a first user equipment (UE) includes: means for sensing in a sidelink resource pool within a shared radio frequency band; means for reserving frequency resources of the sidelink resource pool within a variable time range based on the sensing; means for performing one or more listen-before-talk (LBT) operations in the shared radio frequency band; and means for transmitting sidelink transmissions to a second UE using the frequency resources within the variable time range based on the one or more LBT operations.

[0014] Other aspects, features, and embodiments of the invention will become apparent to those skilled in the art after reading the following description of specific exemplary embodiments of the invention in conjunction with the accompanying drawings. While features of the invention may be discussed below with reference to certain embodiments and drawings, all embodiments of the invention may include one or more advantageous features discussed herein. In other words, while one or more embodiments may be discussed having certain advantageous features, one or more such features may also be used according to various embodiments of the invention discussed herein. Similarly, although exemplary embodiments may be discussed below as embodiments of devices, systems, or methods, it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods. Brief description of the attached diagram

[0016] Figure 1 The present disclosure explains some aspects of wireless communication networks.

[0017] Figure 2 The present disclosure describes a wireless communication network that provides sidelink communication according to some aspects thereof.

[0018] Figure 3A This is a sequence diagram illustrating an autonomous sidelink sensing method according to some aspects of this disclosure.

[0019] Figure 3B The autonomous sidelink sensing scheme based on some aspects of this disclosure is explained.

[0020] Figure 4A This is a sequence diagram illustrating an autonomous sidelink sensing method according to some aspects of this disclosure.

[0021] Figure 4B The autonomous sidelink sensing scheme based on some aspects of this disclosure is explained.

[0022] Figure 5 The sidelink communication scheme based on some aspects of this disclosure is explained.

[0023] Figure 6AThis is a flowchart illustrating a method for performing last-minute reassessment and listen-before-speak (LBT) of reserved frequency resources, according to some aspects of this disclosure.

[0024] Figure 6B The disclosure explains some aspects of the last-minute reassessment of reserved frequency resources.

[0025] Figure 7A This is a flowchart of a method for performing LBT with respect to a group of back-to-back time slots in a reserved frequency resource, according to some aspects of this disclosure.

[0026] Figure 7B It is a timing diagram of one or more LBTs performed on a group of back-to-back time slots in a reserved frequency resource, according to some aspects of this disclosure.

[0027] Figure 8A The disclosure explains the reservation and sharing of frequency resources and time-frequency resources in some aspects.

[0028] Figure 8B The disclosure explains the reserved sharing between the first frequency resources and the second frequency resources according to some aspects of this disclosure.

[0029] Figure 9A The reserved cluster between the first frequency resource and the second frequency resource according to some aspects of this disclosure is explained.

[0030] Figure 9B The reserved clusters between first frequency resources and time-frequency resources according to some aspects of this disclosure are explained.

[0031] Figure 9C The reserved cluster between the first frequency resource and the second frequency resource according to some aspects of this disclosure is explained.

[0032] Figure 10 This is a flowchart illustrating a method for transmitting a soft reservation of frequency resources according to some aspects of this disclosure.

[0033] Figure 11 This is a flowchart illustrating a method for receiving a soft reservation of frequency resources according to some aspects of this disclosure.

[0034] Figure 12 This is a block diagram of an exemplary base station (BS) according to some aspects of this disclosure.

[0035] Figure 13 This is a block diagram of an exemplary user equipment (UE) according to some aspects of this disclosure.

[0036] Figure 14 This is a flowchart of a wireless communication method according to some aspects of this disclosure.

[0037] Detailed description

[0038] The detailed description that follows, taken in conjunction with the accompanying drawings, is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein can be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0039] This disclosure generally relates to wireless communication systems (also known as wireless communication networks). In various embodiments, technologies and apparatus can be used in wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single Carrier FDMA (SC-FDMA) networks, LTE networks, Global System for Mobile Communications (GSM) networks, 5G or New Radio (NR) networks, and other communication networks. As described herein, the terms "network" and "system" may be used interchangeably.

[0040] OFDMA networks can implement radio technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, and flash-OFDM. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunications System (UMTS). Specifically, Long Term Evolution (LTE) is a UMTS version using E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization called the 3rd Generation Partnership Project (3GPP), while cdma2000 is described in documents from an organization called 3rd Generation Partnership Project 2 (3GPP2). These various radio technologies and standards are known or under development. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between various telecommunications association groups that aims to define globally applicable third-generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP project aimed at improving the UMTS mobile phone standard. 3GPP defines specifications for next-generation mobile networks, mobile systems, and mobile devices. This disclosure focuses on the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond, which features shared access to the radio spectrum between networks using new and different sets of radio access technologies or radio air interfaces.

[0041] Specifically, 5G networks envision diverse deployments, diverse spectrum, and diverse services and devices that can be achieved using a unified air interface based on OFDM. To achieve these goals, in addition to developing new radio technologies for 5G NR networks, further enhancements to LTE and LTE-A are also considered. 5G NR will be able to scale to provide coverage for: (1) ultra-high density (e.g., approximately 1 M nodes / km) 2 (1) A massive Internet of Things (IoT) with ultra-low complexity (e.g., approximately tens of bits per second), ultra-low energy consumption (e.g., approximately 10+ years of battery life), and deep coverage capable of reaching challenging locations; (2) A large-scale Internet of Things (IoT) with strong security (to protect sensitive personal, financial, or confidential information), ultra-high reliability (e.g., approximately 99.9999% reliability), ultra-low latency (e.g., approximately 1 ms), and mission-critical control for users with a wide range of mobility or lack of mobility; and (3) Enhanced mobile broadband, including extremely high capacity (e.g., approximately 10 Tbps / km). 2 Extreme data rates (e.g., multi-Gbps rates, 100+Mbps user experience rates), and deep insights with advanced discovery and optimization.

[0042] 5G NR communication systems can be implemented using optimized OFDM-based waveforms with scalable parameter designs and transmission time intervals (TTIs). Additional features may include a shared, flexible framework for efficiently multiplexing services and features using dynamically low latency Time Division Duplex (TDD) / Frequency Division Duplex (FDD) designs; and the utilization of advanced wireless technologies such as massive MIMO, robust millimeter-wave (mmWave) transmission, advanced channel decoding, and device-centric mobility. The scalability of parameter designs in 5G NR (and the scaling of subcarrier spacing) can efficiently address the operation of diverse services across diverse spectrum and deployments. For example, in various outdoor and macro coverage deployments implemented with FDD / TDD below 3 GHz, subcarrier spacing can occur at 15 kHz over bandwidths (BWs) such as 5, 10, and 20 MHz. For other various outdoor and small-cell coverage deployments with TDD above 3 GHz, subcarrier spacing can occur at 30 kHz over an 80 / 100 MHz BW. For various other indoor broadband implementations, by using TDD in the unlicensed portion of the 5 GHz band, the subcarrier spacing can occur at 60 kHz over a 160 MHz BW. Finally, for various deployments using mmWave components for TDD at 28 GHz, the subcarrier spacing can occur at 120 kHz over a 500 MHz BW.

[0043] 5G NR's scalable parameter design enables scalable TTIs to meet diverse latency and Quality of Service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmissions to begin at symbol boundaries. 5G NR also envisions a self-contained integrated subframe design that incorporates UL / downlink scheduling information, data, and confirmation within the same subframe. Self-contained integrated subframes support communication in unlicensed or contention-based shared spectrum and support adaptive UL / downlink that can be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet current traffic needs.

[0044] Various other aspects and features of this disclosure are further described below. It should be apparent that the teachings herein can be embodied in a variety of forms, and any specific structure, function, or both disclosed herein are merely representative and not limiting. Based on the teachings herein, those skilled in the art will appreciate that the aspects disclosed herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement an apparatus or practice a method. Furthermore, such an apparatus or practice can be implemented using other structures, functionalities, or structures and functionalities that complement or differ from one or more aspects set forth herein. For example, a method can be implemented as part of a system, device, apparatus, and / or as instructions stored on a computer-readable medium for execution on a processor or computer. Moreover, an aspect may include at least one element of the claims.

[0045] Sidelink communication refers to communication between User Equipment (UE) devices without tunneling a Base Station (BS) and / or the core network. Sidelink communication can be transmitted on the Physical Sidelink Control Channel (PSCCH) and the Physical Sidelink Shared Channel (PSSCH). The PSCCH and PSSCH are analogous to the Physical Downlink Control Channel (PDCCH) and Physical Downlink Shared Channel (PDSCH) in downlink (DL) communication between the BS and the UE. For example, the PSCCH may carry Sidelink Control Information (SCI) and the PSSCH may carry sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH may carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. Use cases for sidelink communication may include V2X, enhanced mobile broadband (eMBB), industrial IoT (IIoT), and / or NR-Lightweight.

[0046] As used herein, the term "sidelink UE" can refer to a user equipment equipment that performs device-to-device communication or other types of communication with another user equipment equipment independently of any tunneling through a BS (e.g., gNB) and / or associated core network. As used herein, the term "sidelink transmitting UE" can refer to a user equipment equipment that performs sidelink transmission operations. As used herein, the term "sidelink receiving UE" can refer to a user equipment equipment that performs sidelink reception operations. A sidelink UE can operate as a transmitting sidelink UE at one time and as a receiving sidelink UE at another time.

[0047] NR supports two Radio Resource Allocation (RRA) modes for sidelinks on licensed spectrum: Mode 1 RRA and Mode 2 RRA. Mode 1 RRA supports network control RRA that can be used for in-coverage sidelink communication. For example, the serving BS can determine radio resources on behalf of the sidelink UE and transmit instructions for radio resources to the sidelink UE. Mode 2 RRA supports autonomous RRA that can be used for out-of-coverage or partially-covered sidelink UEs. For example, out-of-coverage or partially-covered UEs can be pre-configured with a sidelink resource pool and can select radio resources from the pre-configured pool for sidelink communication.

[0048] For Mode 2 RRA, the sidelink UE can perform sensing in the sidelink resource pool. Sensing may include decoding the SCI and / or measuring the signal energy in the channel. For SCI decoding, the UE can blindly decode the SCI from the PSCCH of each resource. If decoding is successful, the UE can record the decoded SCI. For signal measurement, the UE can receive signals from each resource and calculate the Reference Received Power (RSRP) and / or Received Signal Strength Indicator (RSSI) for each resource. The UE can also record signal measurements. The UE can generate packets for transmission (e.g., Media Access Control (MAC), Packet Data Units (PDUs)). The UE can trigger resource selection at the time of packet generation. The UE can define a sensing window and a resource selection window in the resource pool with respect to the timing of triggering resource selection. The sensing window can be located before triggering, and the resource selection window can be located after triggering. The UE can determine the sensing window and the resource selection window based on a preconfigurable and / or predetermined set of parameters. The UE can identify candidate resources within the resource selection window based on past sensing results obtained in the sensing window (e.g., decoded SCIs and / or signal measurements). In other words, the UE can predict resource usage within the resource selection window based on past sensing results. The UE can randomly select resources from identified candidate resources. The selected resources can be within a fixed subchannel in the frequency domain and a fixed sidelink time slot in the time domain. The UE can indicate a reservation for the selected resource. In other words, the reservation can have the granularity of a sidelink time slot. This reservation can facilitate Channel-Sensitive Multiple Access (CSMA) between sidelink UEs (e.g., in a sidelink-internal system). In some instances, the UE can continue sensing and perform a last-minute evaluation of the reserved resource (e.g., T3 duration prior to the actual transmission time) to check if the reserved resource has been preempted by another UE. If the last-minute evaluation indicates that the reserved resource is still available, the UE can use the selected resource to transmit sidelink transmissions (e.g., including SCI in PSCCH and packets in PSSCH). In some instances, when Hybrid Automatic Repeat Request (HARQ) is used for packet transmissions, the UE can select multiple resources from the candidate resources, such as a first resource for the initial transmission of packets and a second resource for packet retransmissions.

[0049] The deployment of NR in unlicensed spectrum is referred to as NR-Unlicensed (NR-U). Some studies have been conducted on NR-U deployment in the 5 GHz unlicensed band. Channel access in unlicensed bands can be regulated by regulations. For example, Level Bypass (LBT) is applied to some unlicensed bands. To perform LBT, a transmitting node can listen to the channel to determine if there is active transmission in the channel (e.g., based on channel signal energy measurements). When the channel is idle (passing LBT), the transmitting node can transmit in the channel. However, if the channel is busy (failed LBT), the transmitting node can suppress access to the channel. Therefore, LBT can lead to channel access uncertainty. Autonomous Mode 2RRA and sensing are designed to operate in licensed bands and therefore may not account for channel access uncertainty. As a result, even after the UE has determined through last-minute reassessment that resources are still available for transmission, the UE's LBT may fail, indicating that the channel is busy. In such cases, the UE may be prevented from using resources to transmit, and transmission may be delayed.

[0050] To facilitate sidelink communication on shared radio frequency bands (e.g., in unlicensed or shared spectrum), resources in the sidelink resource pool may include gaps for sidelink UEs to perform LBTs. Therefore, sidelink resources may have overlaps with LBT gaps near the end of the sidelink resource, where such LBT gaps can be used by a sidelink UE intending to use the next sidelink resource in time. In other words, sidelink resources with overlapping LBTs can end earlier, thereby reducing the allowed transmission time. Reduced transmission time can impact performance, and therefore UEs may wish to avoid resources that include LBT gaps overlapping with another UE's, or at least avoid resources with large overlaps with LBT gaps. In this way, the use of LBT gaps can cause UEs to avoid using adjacent (e.g., back-to-back) resources in the time domain and / or terminate transmissions before the resource ends. Additionally, sidelink UEs may include LBT gap information in the SCI along with sidelink resource reservations. LBT gap information in SCI allows other sidelink UEs performing channel sensing (monitoring sidelink UEs) to know the LBT gap in the first sidelink resource immediately preceding the reserved sidelink resource. For example, if another sidelink UE decides to reserve the first sidelink resource, that other sidelink UE can shorten its transmission in the first resource. Therefore, the use of LBT gaps can lead to a loss of spectral efficiency, and the implementation of SCI sensing utilizing LBT gap information and LBT gap avoidance can be complex.

[0051] As used herein, the term "frequency resource" can refer to radio resources in a fixed frequency subchannel identified by a fixed subchannel index in the frequency domain. As used herein, the term "variable time range" can refer to a variable number of time units (e.g., sidelink time slots). As used herein, the terms "frequency resource reservation" or "frequency reservation only" can refer to the reservation of radio resources having a fixed subchannel index in the frequency domain and a variable (e.g., floating) time index in the time domain. In other words, a variable time range can refer to the time spanned by a frequency resource reservation, which can correspond to the number of resources and / or time slots included in the frequency resource reservation. The variable aspect of the terms "variable time range" or "variable time index" can relate to a flexible (e.g., non-fixed) starting time slot boundary within the variable time range for using frequency resources to transmit sidelink transmissions, as described below, and / or can refer to the difference in the time spanned by different instances of the variable time range (e.g., the number of time slots included therein).

[0052] This application describes a mechanism for reserving frequency resources in a variable time range from a pool of sidelink resources in a shared radio frequency band (e.g., in shared spectrum or unlicensed spectrum). For example, a first UE may reserve frequency resources in the same subchannel within the variable time range (e.g., reserve resources with a fixed subchannel index) for communication with a second UE. The variable time range may include one or more adjacent time slots, which may provide the first UE with more opportunities and / or flexibility to transmit sidelink transmissions. For example, the first UE may perform one or more LBTs after reserving the frequency resources and may transmit sidelink transmissions to the second UE based on the one or more LBTs. Thus, the first UE may begin transmitting sidelink transmissions at a time slot after identifying a successful (e.g., passed) LBT corresponding to a time slot in the variable time range (e.g., occurring in a gap preceding that time slot). On the other hand, after identifying a failed LBT at a time slot in the variable time range, the first UE may continue to perform one or more LBTs for the remaining time slots in the variable time range, and / or may reschedule sidelink transmissions to alternative frequency resources in another variable time range. Therefore, by increasing the number of time slots included in the variable time range, the likelihood of frequency resources being associated with the LBT increases.

[0053] In some aspects, to reserve frequency resources, the first UE can perform sensing within a sidelink resource pool and identify available candidate resources within that pool based on this sensing. The first UE can further filter candidate resources, particularly based on the size M of the variable time range (e.g., the number of time slots M included in the variable time range). For example, the first UE can filter candidate resources to identify time-adjacent (e.g., back-to-back) candidate resources spanning variable time ranges within the same subchannel. In some instances, the first UE can determine the size M of the variable time range based on pre-configuration, Radio Resource Control (RRC) configuration, System Information Block (SIB), Packet Delay Budget (PDB) for sidelink transmissions, Channel Busy Rate (CBR) associated with the sidelink resource pool, and so on. Furthermore, the first UE can adjust (e.g., reduce) the variable time range in response to determining that the sidelink resource pool lacks sufficient (e.g., below a threshold) available candidate resources to reserve frequency resources.

[0054] In some respects, the first UE may transmit a reservation of frequency resources to reserve frequency resources over a variable time range. For example, the UE may transmit the reservation within the SCI via the PSCCH. The reservation may include information identifying the subchannel index associated with the frequency resource and / or the slot index associated with the variable time range (such as the slot index associated with the slot at the beginning of the variable time range).

[0055] In some respects, the first UE can use random backoff or a countdown to perform one or more LBTs. In such respects, the first UE can perform a first LBT, which may involve executing a countdown until a first timeslot boundary of a variable time range. In response to determining that the first LBT has failed, the first UE can perform a second LBT, which may involve resuming the countdown before a second timeslot boundary of the variable time range. In this way, the first UE can continue to use the same countdown for the first and second LBTs, which can reduce transmission latency.

[0056] In some aspects, after a first UE reserves frequency resources over a variable time range, the reservation of frequency resources may be shared by another UE at least based on the priority associated with the reservation (e.g., conditional reservation). For example, a third UE may reserve time-frequency resources (in a fixed time slot) or second frequency resources (in a variable number of time slots) in the same subchannel as the first UE's reserved frequency resources, overlapping with one or more time slots in the first UE's reserved variable time range. In other words, the third UE may share the first UE's reservation. However, the third UE may only use the time-frequency resources or the second frequency resources for transmission if the first UE does not use each of the overlapping time slots to transmit sidelink transmissions. For example, if the first UE successfully transmits a sidelink transmission in a first time slot within the variable time range of the frequency resource reservation, and the frequency resource reservation includes two or more time slots, the third UE may transmit in any remaining time slots reserved by the third UE. In this way, the third UE may proactively reserve resources within the first UE's frequency resource reservation that may not necessarily be utilized by the first UE.

[0057] In some aspects, the first UE can reserve a second frequency resource after reserving a frequency resource. Furthermore, the first UE can reserve the second frequency resource by clustering it with other frequency resources. For example, the first UE can select a second frequency resource such that it is frequency-adjacent to the frequency resource (e.g., within an adjacent sub-channel), time-adjacent to the frequency resource (e.g., within an adjacent time slot), or both (e.g., overlapping with the frequency resource). As a result, in some instances, the first UE can transmit sidelink transmissions and additional sidelink transmissions associated with the second frequency resource based on the same LBT. For example, when the frequency resource is reserved and the second frequency resource is reserved in an adjacent sub-channel and time-offset, the first UE can perform a self-delay after identifying the LBT associated with the first time slot boundary of the frequency resource (by that offset), so that the first UE can simultaneously transmit sidelink transmissions and additional sidelink transmissions in the adjacent sub-channel in a frequency division multiplexing (FDM) manner. Alternatively, when the frequency resource reservation and the second frequency resource reservation are in the same subchannel with overlapping time slots or with a time-coherent variable time range, the first UE may perform self-delay after identifying the first time slot boundary associated with the frequency resource via LBT, so that the first UE can transmit sidelink transmissions and additional sidelink transmissions back-to-back in time-division multiplexing (TDM).

[0058] In some aspects, when a first UE reserves frequency resources, it can transmit a soft reservation of a second frequency resource for transmitting a different sidelink transmission (e.g., a different transport block). Subsequently, if the second frequency resource is not preempted by another wireless communication device (e.g., another UE), the first UE can use the second frequency resource to transmit this different sidelink transmission. To this end, in response to receiving a soft reservation of the second frequency resource, a third UE can make a best effort to schedule transmissions around the soft reservation. For example, when reserving resources, the third UE can treat the resource associated with the soft reservation as unavailable until it is determined that the third UE cannot reserve the resource without preempting at least a portion of the soft reservation.

[0059] The aspects of this disclosure offer several benefits. For example, by reserving frequency resources over a variable time range for sidelink transmissions, these transmissions can be delivered with less latency. Therefore, instead of rescheduling sidelink transmissions based on frequency resource pre-occupancy at a specific time slot or associated with LBT failure, the sidelink transmissions can be delivered within the same frequency resources on different time slots. Furthermore, the aspects of this disclosure provide greater robustness regarding LBT operation. For example, by restoring the same countdown for LBTs associated with different time slot boundaries, the success rate of LBTs performed for a particular transmission can be increased. Additionally, the aspects of this disclosure can avoid the complex implementation associated with SCI reservation and SCI sensing utilizing LBT gap information.

[0060] Figure 1 A wireless communication network 100 according to some aspects of this disclosure is described. Network 100 may be a 5G network. Network 100 includes several base stations (BSs) 105 (labeled 105a, 105b, 105c, 105d, 105e, and 105f, respectively) and other network entities. BS 105 may be a station communicating with UE 115, and may also be referred to as an evolved B-node (eNB), a next-generation eNB (gNB), an access point, etc. Each BS 105 may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to that specific geographic coverage area of ​​BS 105 and / or the BS subsystem serving that coverage area, depending on the context in which the term is used.

[0061] BS 105 can provide communication coverage for macrocells or small cells (such as picocells or femtocells), and / or other types of cells. Macrocells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access by UEs with service subscriptions to a network provider. Small cells (such as picocells) typically cover a relatively small geographic area and allow unrestricted access by UEs with service subscriptions to a network provider. Small cells (such as femtocells) also typically cover a relatively small geographic area (e.g., a residential area) and, in addition to unrestricted access, allow restricted access by UEs associated with that femtocell (e.g., UEs in a closed subscriber group (CSG), UEs of users in that residence, etc.). A BS used for macrocells may be referred to as a macro BS. A BS used for small cells may be referred to as a small cell BS, pico BS, femtocell BS, or home BS. Figure 1 In the examples shown, BS 105d and 105e can be conventional macro BSs, while BS 105a-105c can be macro BSs with one of three-dimensional (3D), full-dimensional (FD), or massive MIMO enabled. BS 105a-105c can leverage its higher-dimensional MIMO capabilities to increase coverage and capacity using 3D beamforming in both elevation and azimuth beamforming. BS 105f can be a small cell BS, which can be a home node or a portable access point. BS 105 can support one or more (e.g., two, three, four, etc.) cells.

[0062] Network 100 can support synchronous or asynchronous operation. For synchronous operation, each BS can have similar frame timing, and transmissions from different BSs can be roughly aligned in time. For asynchronous operation, each BS can have different frame timing, and transmissions from different BSs may not be aligned in time.

[0063] Each UE 115 is distributed throughout the wireless network 100, and each UE 115 may be stationary or mobile. UE 115 may also be referred to as a terminal, mobile station, subscriber unit, station, etc. UE 115 may be a cellular phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, tablet computer, laptop computer, cordless phone, wireless local loop (WLL) station, etc. In one aspect, UE 115 may be a device including a Universal Integrated Circuit Card (UICC). In another aspect, UE may be a device without a UICC. In some aspects, UE 115 without a UICC may also be referred to as an IoT device or an Internet of Things (IoE) device. UE 115a-115d are examples of mobile smartphone-type devices accessing network 100. UE 115 may also be a machine specifically configured for connected communications (including Machine Type Communication (MTC), Enhanced MTC (eMTC), Narrowband IoT (NB-IoT), etc.). UE 115e-115h are examples of various machines configured for communication within access network 100. UE 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication within access network 100. UE 115 can communicate with any type of BS (whether macro BS, small cell, etc.). Figure 1 In this context, the lightning bolt (e.g., a communication link) indicates radio transmissions between UE 115 and serving BS 105, desired transmissions between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UE 115, where serving BS 105 is the BS designated to serve UE 115 on the downlink (DL) and / or uplink (UL).

[0064] In operation, BS 105a-105c can use 3D beamforming and coordinated spatial technologies (such as Coordinated Multipoint (CoMP) or multi-connectivity) to serve UE 115a and 115b. Macro BS 105d can perform backhaul communication with BS 105a-105c and small cell BS 105f. Macro BS 105d can also deliver multicast services subscribed to and received by UE 115c and 115d. Such multicast services may include mobile TV or streaming video, or may include other services for providing community information (such as weather emergencies or alerts, such as Amber Alerts or Grey Alerts).

[0065] BS 105 can also communicate with the core network. The core network provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some BS 105s (e.g., examples of gNBs or Access Node Controllers (ANCs)) can interface with the core network via backhaul links (e.g., NG-C, NG-U, etc.) and can perform radio configuration and scheduling for communication with UE 115. In various examples, BS 105s can communicate with each other directly or indirectly (e.g., via the core network) on backhaul links (e.g., X1, X2, etc.), which can be wired or wireless communication links.

[0066] Network 100 can also support mission-critical communication with highly reliable and redundant links for mission-critical devices such as UE 115e, which could be a drone. Redundant communication links with UE 115e may include links from macro BSs 105d and 105e, and links from small cell BS 105f. Other machine-type devices (such as UE 115f (e.g., a thermometer), UE 115g (e.g., a smart meter), and UE 115h (e.g., a wearable device)) can communicate directly with BSs (such as small cell BS 105f and macro BS 105e) via network 100, or be in a multi-step configuration by communicating with another user equipment that relays its information to the network (e.g., UE 115f relays temperature measurement information to smart meter UE 115g, which is then reported to the network via small cell BS 105f). Network 100 can also provide additional network efficiency through dynamic, low latency TDD / FDD communication, such as V2V, V2X, C-V2X communication between UE 115i, 115j or 115k and other UE 115, and / or vehicle-to-infrastructure (V2I) communication between UE 115i, 115j or 115k and BS 105.

[0067] In some implementations, network 100 utilizes OFDM-based waveforms for communication. OFDM-based systems can divide the system BW into multiple (K) orthogonal subcarriers, which are often referred to as subcarriers, frequency modulation, frequency slots, etc. Each subcarrier can be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system BW. The system BW can also be divided into subbands. In other instances, the subcarrier spacing and / or the duration of the time interval (TTI) can be scalable.

[0068] In some respects, BS 105 may assign or schedule (e.g., in the form of time-frequency resource blocks (RBs)) transmission resources for downlink (DL) and uplink (UL) transmissions in network 100. DL refers to the transmission direction from BS 105 to UE 115, while UL refers to the transmission direction from UE 115 to BS 105. Communication may take the form of radio frames. Radio frames may be divided into multiple subframes or time slots, for example, about 10. Each time slot may be further divided into sub-time slots. In FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes UL subframes in the UL band and DL subframes in the DL band. In TDD mode, UL and DL transmissions occur using the same frequency band at different time periods. For example, a subset of subframes in a radio frame (e.g., DL subframes) may be used for DL ​​transmissions, and another subset of subframes in a radio frame (e.g., UL subframes) may be used for UL transmissions.

[0069] DL subframes and UL subframes can be further divided into several regions. For example, each DL or UL subframe may have a predefined region for the transmission of reference signals, control information, and data. Reference signals are predetermined signals that facilitate communication between BS 105 and UE 115. For example, reference signals may have a specific pilot pattern or structure, wherein the pilot frequencies may span the operating BW or frequency band, and each pilot frequency is positioned at a predefined time and predefined frequency. For example, BS 105 may transmit a cell-specific reference signal (CRS) and / or channel state information-reference signal (CSI-RS) to enable UE 115 to estimate the DL channel. Similarly, UE 115 may transmit a probe reference signal (SRS) to enable BS 105 to estimate the UL channel. Control information may include resource allocation and protocol control. Data may include protocol data and / or operational data. In some aspects, BS 105 and UE 115 may communicate using self-contained subframes. Self-contained subframes may include portions for DL ​​communication and portions for UL communication. Self-contained subframes can be DL-centered or UL-centered. DL-centered subframes can include a duration for DL ​​communication that is longer than the duration for UL communication. UL-centered subframes can include a duration for UL communication that is longer than the duration for DL ​​communication.

[0070] In some respects, network 100 may be an NR network deployed on licensed spectrum. BS 105 may transmit synchronization signals (e.g., including primary synchronization signal (PSS) and secondary synchronization signal (SSS)) within network 100 to facilitate synchronization. BS 105 may broadcast system information associated with network 100 (e.g., including primary information block (MIB), residual system information (RMSI), and other system information (OSI)) to facilitate initial network access. In some instances, BS 105 may broadcast PSS, SSS, and / or MIB in the form of synchronization signal block (SSB) on the physical broadcast channel (PBCH) and may broadcast RMSI and / or OSI on the physical downlink shared channel (PDSCH).

[0071] In some respects, UE 115 attempting to access network 100 can perform an initial cell search by detecting a PSS from BS 105. The PSS enables time-period synchronization and indicates a physical layer identity value. UE 115 can subsequently receive an SSS. The SSS enables radio frame synchronization and provides a cell identity value, which can be combined with a physical layer identity value to identify the cell. The PSS and SSS can be located in the center portion of the carrier or at any suitable frequency within the carrier.

[0072] After receiving the PSS and SSS, UE 115 can receive the MIB. The MIB may include system information for initial network access and scheduling information for RMSI and / or OSI. After decoding the MIB, UE 115 can receive the RMSI and / or OSI. The RMSI and / or OSI may include radio resource control (RRC) information related to the Random Access Channel (RACH) procedure, paging, control resource set (CORESET) for monitoring the Physical Downlink Control Channel (PDCCH), Physical UL Control Channel (PUCCH), Physical UL Shared Channel (PUSCH), power control, and SRS.

[0073] After obtaining the MIB, RMSI, and / or OSI, UE 115 can execute a random access procedure to establish a connection with BS 105. In some examples, the random access procedure can be a four-step random access procedure. For example, UE 115 can transmit a random access preamble, and BS 105 can respond with a random access response. The random access response (RAR) may include the detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, UL grant, temporary cell radio network temporary identifier (C-RNTI), and / or backoff indicator. Upon receiving the random access response, UE 115 can transmit a connection request to BS 105, and BS 105 can respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, RAR, connection request, and connection response may be referred to as message 1 (MSG 1), message 2 (MSG 2), message 3 (MSG 3), and message 4 (MSG 4), respectively. In some examples, the random access procedure can be a two-step random access procedure, where UE 115 can transmit the random access preamble and connection request in a single transmission, and BS 105 can respond by transmitting the random access response and connection response in a single transmission.

[0074] After the connection is established, UE 115 and BS 105 can enter the normal operation phase, during which operational data can be exchanged. For example, BS 105 can schedule UE 115 for UL and / or DL ​​communication. BS 105 can transmit UL and / or DL ​​scheduling permission to UE 115 via PDCCH. The scheduling permission can be transmitted in the form of DL control information (DCI). BS 105 can transmit DL communication signals (e.g., carrying data) to UE 115 via PDSCH based on the DL scheduling permission. UE 115 can transmit UL communication signals to BS 105 via PUSCH and / or PUCCH based on the UL scheduling permission.

[0075] In some aspects, network 100 may operate on a system BW or a component carrier (CC) BW. Network 100 may divide the system BW into multiple BWPs (e.g., multiple parts). BS 105 may dynamically assign UE 115 to operate on a particular BWP (e.g., a part of the system BW). The assigned BWP may be referred to as the active BWP. UE 115 may monitor the active BWP to look for signaling information from BS 105. BS 105 may schedule UE 115 to perform UL or DL ​​communication in the active BWP. In some aspects, BS 105 may assign a pair of BWPs within a CC to UE 115 for UL and DL communication. For example, the BWP pair may include one BWP for UL communication and one BWP for DL ​​communication.

[0076] In some aspects, network 100 may operate on a shared channel, which may include a shared frequency band or an unlicensed frequency band. For example, network 100 may be an NR unlicensed (NR-U) network operating on an unlicensed frequency band. In such aspects, BS 105 and UE 115 may be operated by multiple network operating entities. To avoid collisions, BS 105 and UE 115 may employ a LBT procedure to monitor transmission opportunities (TXOP) in the shared channel. The wireless communication device may perform LBT in the shared channel. LBT is a channel access scheme that can be used in unlicensed spectrum. When the LBT result is LBT pass (the wireless communication device wins the contention for the wireless medium), the wireless communication device may access the shared medium to transmit and / or receive data. For example, a transmitting node (e.g., BS 105 or UE 115) may perform LBT before transmitting in the channel. When LBT pass, the transmitting node may then transmit. When LBT fail, the transmitting node may suppress transmission in the channel. In one example, LBT may be based on energy detection. For example, when the signal energy measured from the channel is below a threshold, the LBT result is a pass. Conversely, when the signal energy measured from the channel exceeds the threshold, the LBT result is a failure. In another example, LBT can be based on signal detection. For example, when no channel reservation signal (e.g., a predefined preamble signal) is detected in the channel, the LBT result is a pass. Conversely, when a channel reservation signal is detected in the channel, the LBT result is a failure. TXOP can also be referred to as Channel Occupancy Time (COT).

[0077] Additionally, LBT can be in various modes. The LBT mode can be, for example, Category 4 (CAT4) LBT or Category 2 (CAT2) LBT. CAT2 LBT refers to an LBT without a random backoff period. CAT4 LBT refers to an LBT with random backoff and a variable contention window (CW). The serving BS 105 can perform CAT4 LBT to obtain the COT for communicating with the UE. Additionally, the BS 105 can, for example, transmit a COT indication at the beginning of the COT to indicate the duration of the COT and / or one or more subbands in which the COT resides. The serving BS 105 can share the COT with the UE 115. To share the COT of the BS 105, the UE can perform CAT2 LBT within the COT of the BS 105. During CAT2 LBT, the UE can transmit UL transmissions within the COT of the BS 105. The UE 115 can also obtain a COT outside the COT of the serving BS 105 for UL transmissions by performing CAT4 LBT. In some instances, UE 115 can also share the COT of UE 115 with BS 105. In some instances, CAT4 LBT mode may be referred to as Type 1 LBT, and CAT2 LBT mode may be referred to as Type 2 LBT.

[0078] In some respects, network 100 can provide sidelink communication to allow UE 115 to communicate with another UE 115 without tunneling through BS 105 and / or the core network, such as... Figure 2As shown above, sidelink communication can be transmitted on the PSCCH and PSSCH. For example, the PSCCH may carry an SCI and the PSSCH may carry an SCI and / or sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH may carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. The SCI may also carry information for reserving future resources (e.g., up to about two future PSSCHs for retransmission with HARQ). In some examples, the transmitting sidelink UE 115 may indicate the SCI in two phases. In the first phase SCI, UE 115 may transmit an SCI in the PSCCH carrying information for resource allocation and decoding the second phase SCI. The first-stage SCI may include at least one of the following: priority, PSSCH resource allocation, resource reservation period (if enabled), PSSCH DMRS mode (if more than one mode is configured), second-stage SCI format (e.g., the size of the second-stage SCI), amount of resources used for the second-stage SCI, number of PSSCH demodulation reference signal (DMRS) ports, modulation and coding scheme (MCS), etc. In the second-stage SCI, UE 115 may transmit an SCI carrying information for decoding the PSSCH within the PSCCH. The second-stage SCI may include a 1-bit L1 destination identifier (ID), an 8-bit L1 resource ID, a HARQ procedure ID, a new data indicator (NDI), a redundancy version (RV), etc. It should be understood that these are examples, and the first-stage SCI and / or the second-stage SCI may include or indicate additional or different information compared to those examples provided. Sidelink communication can also be transmitted on the Physical Sidelink Feedback Control Channel (PSFCH), which indicates acknowledgment (ACK) or negation (NACK) for previously transmitted PSSCH.

[0079] In some respects, a pair of sidelink transmitting UEs 115 and sidelink receiving UEs 115 can communicate with each other using the autonomous mode 2RRA discussed above. For example, the sidelink transmitting UE 115 can continuously sense or monitor resources in the sidelink resource pool. Sensing or monitoring may include decoding the SCI and / or measuring the signal energy in the channel. The sidelink transmitting UE 115 can record the SCI decoding results and signal measurements. Upon receiving a data packet for transmission, the sidelink transmitting UE 115 can determine a resource selection window based on the sensing results obtained from the sensing window (e.g., decoded SCI and signal measurements) and identify candidate resources from that resource selection window, as will be discussed below. Figures 3A-3BThis is discussed more comprehensively in the following section. The sidelink transmitter UE 115 may randomly select resources from the candidate resources and use the selected resources to transmit sidelink transmissions (e.g., including SCI on PSCCH and / or data on PSSCH).

[0080] According to various aspects of this disclosure, the sidelink transmitter UE 115 can select a frequency resource with a variable time range (the same subchannel index within the variable time range) based on identified candidate resources, reserve the selected frequency resource within the variable time range, and use the frequency resource to transmit sidelink transmissions during available time slots within the variable time range, as will be stated below. Figures 4A-4B This will be discussed more fully in the following section. By selecting and reserving frequency resources over a variable time range, the sidelink transmitter UE 115 can transmit sidelink transmissions in any available time slot within that variable time range. To this end, before transmitting a sidelink transmission, the UE 115 can perform one or more LBTs in a shared radio frequency band and can identify available time slots associated with the LBTs within that variable time range. Thus, when a first time slot in the variable time range is associated with a failed LBT, the sidelink transmitter UE 115 can transmit a sidelink transmission from a second time slot within the variable time range, which can be associated with the LBTs. In this way, the likelihood that the sidelink transmitter UE 115 will reschedule a sidelink transmission based on resource or channel unavailability that could lead to delayed communication, as will be described more fully.

[0081] Figure 2 An example of a wireless communication network 200 providing sidelink communication according to various aspects of this disclosure is explained. Network 200 may correspond to a portion of network 100. Figure 2For the purpose of simplifying the discussion, one BS 205 and five UEs 215 (shown as 215a, 215v, 215c, 215d, and 215e) are described, but it will be appreciated that aspects of this disclosure can be scaled to any suitable number of UEs 215 (e.g., about 2, 3, 4, 5, 7, or more UEs 215) and / or BS 205 (e.g., about 2, 3, or more BSs 205). BS 205 and UE 215 may be similar to BS 105 and UE 115, respectively. BS 205 and UE 215 may share the same radio frequency band for communication. In some instances, the radio frequency band may be a licensed band. In some instances, the radio frequency band may be an unlicensed band (e.g., in the 5 GHz band). In some instances, the radio frequency band may be the Frequency Range 1 (FR1) band. In some instances, the radio frequency band may be the FR2 band. Generally speaking, the radio frequency band can be at any suitable frequency and can have any suitable bandwidth (e.g., about 5 MHz, about 10 MHz, about 20 MHz, about 80 MHz, about 100 MHz or greater).

[0082] In network 200, some UEs 215 can communicate with each other in peer-to-peer communication. For example, UE 215a can communicate with UE 215b on side link 251, UE 215c can communicate with UE 215d on side link 252 and / or with UE 215e on side link 254, and UE 215d can communicate with UE 215e on side link 255. Side links 251, 252, 254, and 255 are unicast bidirectional links. Some UEs 215 can also communicate with BS 205 in the UL direction and / or DL ​​direction via communication link 253. For example, UEs 215a, 215b, and 215c are within the coverage area 210 of BS 205 and are thus in communication with BS 205. UEs 215d and UE 215e are outside the coverage area 210 and may therefore not communicate directly with BS 205. In some instances, UE 215c may operate as a relay to enable UE 215d to reach BS205. In some aspects, some UE 215s are associated with vehicles (e.g., similar to UE 115i-k), and communication on sidelinks 251 and / or 252 may be C-V2X communication. C-V2X communication may refer to communication between a vehicle and any other wireless communication device in a cellular network.

[0083] Discussing each other in relation to each other Figure 3A and 3B To explain autonomous sidelink sensing using mode 2RRA. Figure 3AThis is a sequence diagram illustrating an autonomous sidelink sensing method 300 according to some aspects of this disclosure. Method 300 can be implemented by UE 215. As explained, method 300 includes several enumeration actions, but aspects of method 300 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0084] Autonomous sidelink sensing can be implemented between the MAC layer 302 and the PHY layer 304 at UE 215. As shown in the figure, in action 310, the PHY layer 304 accesses the sidelink resource pool (e.g., Figure 3B Sensing is performed within the sidelink resource pool 350. The sidelink resource pool can refer to a set of time and frequency resources available for sidelink operation. For example, the PHY layer 304 can continuously sense or monitor resources in the sidelink resource pool (e.g., for...). Figure 3B (Resource 352). Sensing or monitoring may include decoding the SCI and / or measuring the signal energy in the channel. For SCI decoding, PHY layer 304 may blindly decode the SCI from the PSCCH of each resource. If decoding is successful, PHY layer 304 may record the decoded SCI. For signal measurement, PHY layer 304 may receive signals from each resource and calculate the Reference Received Power (RSRP) and / or Received Signal Strength Indicator (RSSI) for each resource. PHY layer 304 may also record signal measurements.

[0085] In action 312, MAC layer 302 sends a resource selection trigger to PHY layer 304, for example, based on the generation and preparation of a MAC PDU for transmission. Figure 3B Resource selection triggers 346).

[0086] In action 314, in response to a resource selection trigger, PHY layer 304 identifies candidate resources from the resource pool based on the sensing results. In this regard, PHY layer 304 may determine the sensing window based on the resource selection trigger (e.g., Figure 3B The sensing window 342) and the resource selection window (e.g., Figure 3B The resource selection window 344). The PHY layer 304 can identify candidate resources from the resource selection window based on past sensing results obtained in the sensing window (e.g., decoded SCI and / or signal measurements). Figure 3B The diagram shows the resource selection trigger, sensing window, and resource selection window.

[0087] Figure 3B An autonomous sidelink sensing scheme 340 according to some aspects of this disclosure is explained. Scheme 340 can be adopted by UE 215 or any other UE (such as UE 115 and 215). Figure 3BIn this diagram, the x-axis represents time in some arbitrary unit, and the y-axis represents frequency in some arbitrary unit.

[0088] In scheme 340, UE 215 is pre-configured with a sidelink resource pool 350. The sidelink resource pool 350 may span a frequency bandwidth within a licensed frequency band. The sidelink resource pool 350 may include multiple time-frequency resources 352. Each resource 352 may include a certain number of symbols (e.g., OFDM symbols) in time and a certain number of frequency subcarriers in frequency. In some aspects, resources 352 may be in units of RBs (e.g., including 12 consecutive subcarriers in frequency and the time duration of a time slot or any suitable time duration). Figure 3B The sidelink resource pool 350 for a certain time period is explained. Generally, the sidelink resource pool may include time-frequency resources on consecutive time slots (e.g., consecutive time periods) and / or time-spaced time slots (e.g., non-consecutive time periods).

[0089] exist Figure 3B In the illustrated example, MAC layer 302 can generate a MAC PDU at time slot n, and can also generate a resource selection trigger 346 at time slot n. Upon receiving the resource selection trigger 346, PHY layer 304 can, based on including T proc,0 T proc,1 T0, T1, T2 and T2 min The parameter set defines the sensing window 342 and the resource selection window 344 relative to the time of resource selection trigger 346. For example, the PHY layer 304 can determine the start of the sensing window 342 based on the T0 duration before resource selection trigger 346, and can determine the start of the sensing window 342 based on the T0 duration before resource selection trigger 346. proc,0 The duration is used to determine the end of the sensing window 342. As shown in the figure, the sensing window 342 begins at the start of duration T0 and ends at T... proc,0 The duration ends at the beginning of the time interval. PHY layer 304 can determine the start of resource selection window 344 based on the T1 duration following resource selection trigger 346, and can determine the end of resource selection window 344 based on the T2 duration following resource selection trigger 346. The T1 duration can have parameters T... proc,1 The upper limit of the constraint (e.g., 0 ≤ T, 1 ≤ T) proc,1 The duration of T2 can be determined to satisfy a certain packet delay budget (PDB), and can have a duration determined by T2. min The lower bound of the constraint (e.g., T2) min ≤T2≤PDB). As shown in the figure, the resource selection window 344 begins at the end of time T1 and ends at the end of time T2. In some aspects, the PHY layer 304 can be pre-configured with certain parameters (e.g., T...). proc,0 T proc,1In some respects, PHY layer 304 can receive parameters (e.g., T1, T2, T3) from upper layers (e.g., RRC layer). min ).although Figure 3B The resource selection window 344, which includes 16 resources, has been described. However, it should be understood that in other examples, the resource selection window may include fewer resources (e.g., about 4, 5, 6, 8, or 10) or more resources (e.g., 17, 18, 19, 20, 24, 32, or more).

[0090] PHY layer 304 can identify candidate resources 352 within resource selection window 344 by examining or analyzing sensing results obtained within sensing window 342. In other words, PHY layer 304 can use past sensing results to predict the future use of resources 352 in resource selection window 344. PHY layer 304 can identify candidate resources using a combination of SCI decoding, signal measurements, and / or priority information. In some aspects, PHY layer 304 can exclude resources 352 that are reserved in resource selection window 344 (e.g., based on SCI decoding and / or prediction in sensing window 342). PHY layer 304 can exclude resources 352 in resource selection window 344 that will be used for transmissions with a higher traffic priority than UE 215 (e.g., based on SCI decoding and / or prediction in sensing window 342). PHY layer 304 can exclude resources 352 in resource selection window 344 based on signal measurements (e.g., RSRP and / or RSSI) within sensing window 342 that are above a certain signal threshold and the predicted resource usage pattern. PHY layer 304 can perform resource filtering or exclusion in resource selection window 344 in any suitable order through SCI decoding, prioritization, and / or signal measurement. If the remaining candidate resources 352 in resource selection window 344 are less than 20% of the total resources in resource selection window 344, PHY layer 304 can increase the signal threshold and repeat resource filtering or exclusion until the candidate resources 352 in resource selection window 344 account for approximately 20% of the total resources 352 in resource selection window 344. Figure 3B In the resource selection window 344, candidate resources (available resources) 352 are displayed as empty filled boxes. Unavailable resources 352 are displayed as pattern filled boxes.

[0091] Return to Figure 3A In action 316, the PHY layer 304 sends an indication of the identified candidate resource 352 (e.g., Figure 3B The resource selection window 344 shown contains an empty fill box containing a candidate resource report. This report can indicate the time and frequency location information of the candidate resources.

[0092] In action 318, upon receiving a candidate resource report, MAC layer 302 selects one or more resources from the candidate resources. For example, MAC layer 302 may randomly select a first resource from the candidate resources for transmitting the MAC PDU. As an example, if the report includes a list of N candidate resources, MAC layer 302 may draw a random number between 1 and N (e.g., k) and select the k-th candidate resource. In some instances, UE 215 may apply HARQ to the transmission of a transport block (TB) (carrying a MAC PDU) and may retransmit the same TB if a NACK is received from the corresponding receiving UE for that transmission or if an ACK is not received. Therefore, MAC layer 302 may also randomly select a second resource from the candidate resources by drawing another random number between 1 and N for potential retransmission of the MAC PDU, for example. Figure 3B An example of resource selection was explained.

[0093] refer to Figure 3B The MAC layer 302 can randomly select a first resource 352a (shown by a black circle) from the candidate resources for initial transmission, and can randomly select a second resource 352b (shown by a black circle) from the candidate resources for retransmission. In some instances, the MAC layer 302 can select the second resource 352b for retransmission such that the first resource 352a and the second resource 352b are separated by a T4 duration. In some aspects, the T4 duration can be less than approximately 32 time slots or any other suitable time duration. In some aspects, the T4 duration can have a predetermined or pre-configured lower limit and / or upper limit.

[0094] refer to Figure 3A In action 320, the MAC layer 302 sends a resource reassessment request to the PHY layer 304 (e.g., Figure 3B Resource reassessment request 348). A resource reassessment request may request the PHY layer 304 to report the updated available resources at that moment, to double-check the previously selected resources (e.g., Figure 3B Whether resources 352a and 352b are still available. In some instances, MAC layer 302 can use the selected first resource (e.g., Figure 3B The resource re-evaluation request is sent slightly earlier than the actual time of transmission of the MAC PDU (e.g., 1, 2, 3, 4 symbols, or one time slot earlier) than the resource 352a) in the resource. Thus, the resource re-evaluation request can also be referred to as a "last-minute re-evaluation".

[0095] refer to Figure 3BThe MAC layer 302 sends a resource reassessment request 348 at a time T3 prior to the actual transmission time for the selected first resource 352a. In some respects, the T3 duration may have a predetermined or pre-configured lower and / or upper limit.

[0096] refer to Figure 3A In action 322, in response to a resource re-evaluation request, PHY layer 304 sends an updated resource report to MAC layer 302. PHY layer 304 can identify resources in resource selection window 344 that are still available at the time the resource re-evaluation request was received. PHY layer 304 can use a mechanism substantially similar to that discussed in action 314 to identify available resources (candidate resources) at that time. If a first resource previously selected by MAC layer 302 (e.g., resource 352a) is no longer available, PHY layer 304 can indicate this in the report. For example, the report may include a reselection flag set to 1 for the first resource. Similarly, if a second resource previously selected by MAC layer 302 (e.g., resource 352b) is no longer available, PHY layer 304 can indicate this in the report. For example, the report may include a reselection flag set to 1 for the second resource.

[0097] If the first resource is no longer available, MAC layer 302 may reselect another resource from the candidate resources indicated in the updated candidate resource report in action 324, and may repeat actions 320 and 322 at a later time to perform another last-minute resource re-evaluation on the newly selected resource. Otherwise, in action 326, PHY layer 304 may use the selected first resource to transmit a MAC PDU to the UE on the other side link (e.g., UE 115 and / or 215).

[0098] Similarly, if the second resource (to be used for retransmission) is no longer available, then in action 324, MAC layer 302 can reselect another resource from the candidate resources indicated in the updated candidate resource report. MAC layer 302 can also request PHY layer 304 to perform a last-minute resource reassessment of the resource to be used for retransmission.

[0099] In some respects, UE 215 can communicate with another UE (similar to UE 115, 215, and / or 215) on a sidelink channel in a shared radio frequency band (e.g., in a shared spectrum or unlicensed spectrum). As discussed above, when communicating in an unlicensed band, LBT can be used, where the transmitting node can listen to the channel (by measuring the signal energy in the channel and comparing the measurement to a threshold). When the channel is idle (e.g., where the signal measurements are below the threshold), the transmitting node can transmit in the channel. However, if the channel is busy (e.g., where the signal measurements are above the threshold), the transmitting node can suppress access to the channel. Therefore, LBT can lead to channel access uncertainty.

[0100] For example, refer to Figure 3B As shown in the example, UE 215 can perform CAT4 LBT (Type 1 LBT) before transmitting the MAC PDU. As discussed above, CAT4 LBT can include random backoff or a countdown. The duration of the random backoff or countdown can depend on the CW size. In some instances, the random backoff can have a duration greater than T used to define the T1 duration. proc,1 The parameters have significantly longer durations (e.g., CW could have a duration of 1024 time slots). Thus, resource selection window 344 might begin before the LBT countdown completes. Additionally, the LBT countdown might still be in progress when the resource reassessment request is sent by MAC layer 302, so PHY layer 304 might not be able to reassess resource availability. Furthermore, the T4 duration between the selected first resource 352a (to be used for the initial transmission of the MAC PDU) and the second resource 352b (to be used for the retransmission of the MAC PDU) might be too short for performing another LBT before the retransmission. Therefore, adding LBT to autonomous sidelink sensing would impact packet delivery delay, power consumption at UE 215, and / or spectral efficiency. Additionally or alternatively, UE 215 might detect interference during reassessment, and thus LBT might fail. However, the interference could be temporary and might not exist during the selected or reserved resource period. Therefore, UE 215 may expect to reserve frequency resources over a variable time range (including multiple adjacent time slots) to account for LBT delay, thereby allowing for flexible transmission start times or start time slots within the variable time range as discussed below.

[0101] Discussing each other in relation to each other Figure 4A and 4B The frequency resources are reserved for commentary. Figure 4AThis is a sequence diagram illustrating a frequency resource reservation method 400 according to some aspects of this disclosure. Method 400 can be implemented by UE 215. As explained, method 400 includes several enumeration actions, but aspects of method 400 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0102] In action 410, MAC layer 302 sends a sensing request to PHY layer 304. The sensing request may include... Figure 4B The sensing request may indicate the size (M) of the variable time range 458 of the frequency resource reservation 454 (e.g., the number of time slots (M time slots) included in the variable time range 458). Additionally or alternatively, the sensing request may include a candidate set size threshold for the resource selection window 444. For example, in some aspects, the MAC layer 302 may indicate via the sensing request that the candidate set size threshold is greater than a certain percentage (e.g., 20%, 25%, 30%, etc.) of the resources included in the resource selection window 444. Furthermore, the candidate set size threshold may exceed a pre-configured and / or default candidate size threshold to increase the likelihood of a set 456 of M resources with coherent time slots (variable time range 458) within the candidate resource set within the resource selection window 444. In some aspects, the candidate set size threshold may be determined based on the number of time slots M included in the variable time range 458. In this way, a sensing request corresponding to a variable time range 458 with fewer time slots may indicate a smaller candidate set size threshold than a sensing request corresponding to a variable time range 458 with a larger number of time slots.

[0103] Furthermore, in some aspects, the number of time slots M included in the variable time range 458 may be determined based on one or more factors. For example, UE 215 and / or MAC layer 302 may determine the size M based on predetermined values ​​pre-configured within UE 215 and pre-configured by the network (e.g., network 100, network 200). Additionally or alternatively, UE 215 may be configured to receive an indication of the size M from BS 205 in RRC configuration, System Information Block (SIB), etc. In some aspects, UE 215 may be further configured to adjust the predetermined value based on the received indication.

[0104] Furthermore, in some aspects, UE 215 can be configured to determine the size M based on the traffic priority and / or PDB of the sidelink transmission to be transmitted on resources reserved by frequency resource reservation 454. For example, for a first sidelink transmission with a higher traffic priority and / or a lower PDB, the UE can determine a larger M value than a second sidelink transmission with a lower traffic priority and / or a higher PDB. A larger M value or a larger number of time slots in a variable time range provides UE 215 with more opportunities to find available resources with LBT passage. In this way, the first sidelink transmission can be transmitted with a smaller delay than the second sidelink transmission.

[0105] In some respects, UE 215 can determine the size M based on the Channel Busy Rate (CBR) associated with the sidelink resource pool 444. The CBR is a measure indicating the number of sub-channels in the sidelink resource pool with a measured Received Signal Strength Indicator (RSSI) greater than a certain threshold, divided by the total number of sub-channels in the resource pool. The CBR can provide an estimate of the overall channel occupancy status. In such cases, for a given traffic priority of the sidelink transmission, UE 215 can determine a reduced size M for an increasing CBR value. For example, for each given sidelink transmission traffic priority, UE 215 can configure a mapping between CBR values ​​and the size M via pre-configured broadcast SIB-based, RRC-based, or other configurations, such as a maximum value M for each CBR value or a range of CBR values.

[0106] In action 412, PHY layer 304 uses the sidelink resource pool (e.g., Figure 4B Sensing is performed in the sidelink resource pool 450. (See above reference.) Figure 3B As described, the sidelink resource pool can refer to a set of time and frequency resources available for sidelink operation. Sensing or monitoring may include decoding the SCI and / or measuring signal energy in the channel. For SCI decoding, PHY layer 304 can blindly decode the SCI from the PSCCH of each resource. If decoding is successful, PHY layer 304 can record the decoded SCI. For signal measurement, PHY layer 304 can receive signals from each resource and calculate the Reference Received Power (RSRP) and / or Received Signal Strength Indicator (RSSI) for each resource. PHY layer 304 can also record signal measurements.

[0107] In some respects, PHY layer 304 can sense or monitor resources based on sensing requests (e.g., Figure 4B Resource 352). For example, PHY layer 304 may perform sensing in response to receiving (e.g., in action 410) a sensing request transmitted by MAC layer 302. Furthermore, in some aspects, PHY layer 304 may continuously sense or monitor resources in the sidelink resource pool (e.g., Figure 4B(Resource 352). In such cases, the PHY layer 304 can perform sensing before receiving a sensing request, as referenced above. Figure 3A The explanation and general description.

[0108] In action 414, MAC layer 302 sends a resource selection trigger to PHY layer 304 (e.g., ...). Figure 4B Frequency resource selection trigger 446). In some embodiments, MAC layer 302 may send a resource selection trigger based on MAC PDUs and / or transport blocks (TBs) (e.g., transport blocks carrying MAC PDUs) being generated and prepared for transmission (e.g., sidelink transmission). Furthermore, in some aspects, as a supplement to or replacement of sensing request 410, MAC layer 302 may include an indication of the size M of the variable time range 458 and / or a candidate set size threshold within the frequency resource selection trigger 446. Where the indication of size M and / or the candidate set size threshold are included within the resource selection trigger 446, sensing request 410 may be omitted.

[0109] In action 416, in response to a resource selection trigger, PHY layer 304 identifies candidate resources from the resource pool based on the sensing results. In this regard, PHY layer 304 may determine the sensing window based on the resource selection trigger (e.g., Figure 4B The sensing window 442) and the resource selection window (e.g., Figure 4B The frequency resource selection window 444. PHY layer 304 can identify candidate resources from the resource selection window based on past sensing results obtained in the sensing window (e.g., decoded SCI and / or signal measurements). Furthermore, PHY layer 304 can identify candidate resources based on a candidate set size threshold received from MAC layer 302. Figure 4B The diagram shows the resource selection trigger, sensing window, and resource selection window.

[0110] Figure 4B An autonomous sidelink sensing scheme 440 according to some aspects of this disclosure is explained. Scheme 440 can be adopted by UE 215 or any other UE (such as UE 115 and 215). Figure 4B In this diagram, the x-axis represents time in some arbitrary unit, and the y-axis represents frequency in some arbitrary unit.

[0111] In scheme 440, UE 215 is pre-configured with a sidelink resource pool 450. Sidelink resource pool 450 can span a frequency bandwidth within a licensed or shared frequency band. Sidelink resource pool 450 can be similar to sidelink resource pool 350 and uses the same... Figure 3BThe same resource pool structure can be used as an example. As shown in the figure, the sidelink resource pool 450 may include multiple time-frequency resources 352. Each resource 352 may include a certain number of symbols (e.g., OFDM symbols) in time and a certain number of frequency subcarriers in frequency. In some aspects, resources 352 may be in units of RBs (e.g., including 12 consecutive subcarriers in frequency and the time duration of the time slot or any suitable time duration). Figure 4B The sidelink resource pool 450 for a certain time period is described. Generally, the sidelink resource pool may include time-frequency resources 352 on consecutive time slots (e.g., consecutive time periods) and / or time-spaced time slots (e.g., non-consecutive time periods).

[0112] exist Figure 4B In the illustrated example, MAC layer 302 can generate a frequency resource selection trigger 446 at time slot n. Upon receiving the resource selection trigger 446, PHY layer 304 can, based on T... proc,0 T proc,1 T0, T1, T2 and T2 min The parameter set is relative to the time definition of the resource selection trigger 446, the sensing window 442, and the resource selection window 444, as referenced above. Figure 3B General description. Although Figure 4B The resource selection window 444, which includes 16 resources, has been described. However, it should be understood that in other examples, the resource selection window may include fewer resources (e.g., about 4, 5, 6, 8, or 10) or more resources (e.g., 17, 18, 19, 20, 24, 32, or more).

[0113] PHY layer 304 can examine or analyze the sensing results obtained within sensing window 442 (e.g., in...). Figure 4AAction 416) identifies candidate resources 352 within resource selection window 444. In other words, PHY layer 304 can use past sensing results to predict the future use of resources 352 in resource selection window 444. PHY layer 304 can identify candidate resources using a combination of SCI decoding, signal measurement, and / or priority information. In some aspects, PHY layer 304 can exclude resources 352 that are reserved in resource selection window 444 (e.g., based on SCI decoding and / or prediction in sensing window 442). PHY layer 304 can exclude resources 352 in resource selection window 444 that will be used for transmissions with a higher traffic priority than UE 215 (e.g., based on SCI decoding and / or prediction in sensing window 442). PHY layer 304 can exclude resources 352 in resource selection window 442 based on signal measurements (e.g., RSRP and / or RSSI) above a certain signal threshold and predicted resource usage patterns within sensing window 444. PHY layer 304 can perform resource filtering or exclusion in resource selection window 444 in any suitable order via SCI decoding, prioritization, and / or signal measurement. If the remaining candidate resources 352 in resource selection window 444 are less than a candidate set size threshold (e.g., a percentage of the total resources in resource selection window 444), PHY layer 304 can increase the signal threshold and repeat resource filtering or exclusion until the candidate resources 352 in resource selection window 444 meet (e.g., are equal to or exceed) the candidate set size threshold. Figure 4B In the resource selection window 444, candidate resources (available resources) 352 are shown as empty filled boxes (or reserved by frequency resource reservation 454). Additionally or alternatively, the PHY layer 304 may exclude resources 352 based on a size M. For example, the PHY layer 304 may exclude resources 352 that are not contiguous with other available resources 352 in the time domain and / or the set of contiguous resources 352 smaller than M. Unavailable resources 352 are shown as pattern-filled boxes.

[0114] Return to Figure 4A In action 418, PHY layer 304 sends an indication of the identified candidate resource 352 (e.g., Figure 3B The candidate resource report (shown in the empty-filled box of the resource selection window 344) can indicate the time and frequency location information (e.g., time and frequency index) of the candidate resource 352.

[0115] In action 420, upon receiving a candidate resource report, MAC layer 302 selects one or more resources from candidate resources 352. More specifically, MAC layer 302 can select two or more resources (e.g., M time-adjacent resources) from the candidate resources 352 for frequency resource reservation 454 within the same sub-channel. Furthermore, before selecting these one or more resources, MAC layer 302 can filter (e.g., screen) the candidate resource reports 418. For example, MAC layer 302 can filter the candidate resources 352 based on a size M. To do this, MAC layer 302 can receive candidate resource reports 418 and can filter to obtain a group of M time-adjacent resources 352 within the corresponding sub-channel. Furthermore, it can be understood that, as a supplement or replacement to the filtering described above with respect to PHY layer 304, MAC layer 302 can filter resources.

[0116] In some aspects, by filtering candidate resources within the candidate resource report, MAC layer 302 can identify a set of M time-adjacent (e.g., back-to-back) available candidate resources within the candidate resource report 418. Subsequently, if the number of identified sets is less than (e.g., fails to meet) a threshold (which may be pre-configured and / or predetermined within UE 215), MAC layer 302 can reduce the size of M and / or restart method 400 by transmitting a new sensing request 410. On the other hand, if the identified sets are greater than or equal to (e.g., meet) the threshold, MAC layer 302 can select a set of M time-adjacent available candidate resources from that set. For this purpose, MAC layer 302 can select frequency resources 455 (shown as a set of M resources 456) over a variable time range 458.

[0117] In some aspects, MAC layer 302 can use clustered resource selection to select a set 456 of M resources for frequency resource reservation 454. For example, MAC layer 302 can select frequency resource reservation 454 to perform frequency division multiplexing (FDM), time division multiplexing (TDM), and / or overlap with another frequency resource reservation 454 and / or reserved time-frequency resource 352, as described in more detail below. Additionally or alternatively, MAC layer 302 can randomly select frequency resource reservation 454. For example, MAC layer 302 can randomly select a first set of resources from candidate resources for transmitting MAC PDUs. As a further example, if the candidate resource report includes a list of N sets of adjacent candidate resource groups of size M, MAC layer 302 can draw a random number between 1 and N (e.g., k) and select the k-th candidate resource set as the set 456 of M resources for frequency resource reservation 454. Furthermore, in some instances, UE 215 can apply HARQ to the transmission of a transport block (TB) (carrying a MAC PDU) and can retransmit the same TB if a NACK is received from the corresponding receiving UE for that transmission or if an ACK is not received. Therefore, MAC layer 302 can also randomly select a second set of M resources of a second frequency resource over a second variable time range from the candidate resources by drawing another random number between 1 and N for potential retransmission of the MAC PDU, for example.

[0118] Now for reference Figure 4B MAC layer 302 can randomly select a frequency resource reserve 454 from candidate resources for initial transmission or retransmission. Therefore, although a single frequency resource reserve 454 has been described, MAC layer 302 can select multiple frequency resource reserves 454 from candidate resources (such as a first frequency resource reserve for initial transmission and a second frequency resource reserve (not shown) for retransmission), as described above. In such a case, the second frequency resource reserve may be spaced apart from the first frequency resource reserve by time interval (T4), as referenced above. Figure 3B As stated above.

[0119] Return to Figure 4A In action 422, PHY layer 304 may transmit sidelink transmissions (e.g., MAC PDUs and / or TBs) to the other sidelink UE (e.g., UE 115 and / or 215) using one of the selected or reserved resources reserved by frequency resource reservation 454. More specifically, PHY layer 304 may transmit sidelink transmissions after determining, based on a last-minute reassessment and one or more LBTs, that resources in the set 454 of M resources are available for transmission within a variable time range 458, as referenced below. Figure 6A and 6B A more detailed description.

[0120] Turn now Figure 5 According to some aspects of this disclosure, the reservation of a set 456 of M resources 455 of frequency resources 455 over a variable time range 458 within a sidelink communication scheme 500 is explained. Scheme 500 can be adopted by UE 215 or any other UE (such as UE 115 and 215). Figure 5 In this diagram, the x-axis represents time in some arbitrary unit, and the y-axis represents frequency in some arbitrary unit.

[0121] In some aspects, UE 215 may reserve a set 456 of M resources (e.g., frequency resource reservation 454) so ​​that other UEs (e.g., UE 115 and / or 215) can detect the reservation. For example, UE 215 may transmit a reservation 542 (e.g., a reservation message) based on the frequency resource reservation 454 selected by MAC layer 302 (e.g., in action 420). Reservation 542 may include a sub-channel index identifying frequency resource 455, a timeslot index of variable time range 458 (such as a timeslot index identifying the start timeslot of variable time range 458 (e.g., timeslot 460)), the total number of timeslots included in variable time range 458 (e.g., the duration of variable time range), or a combination thereof. Furthermore, as described above, MAC layer 302 may select multiple frequency resource reservations 454. Therefore, reservation 542 may include information (e.g., sub-channel and / or timeslot indexes) for identifying both the first set 456 of M resources and the second set of M resources (not explained).

[0122] Although Figure 5 It has been explained that reservation 542 occupies the entire time-frequency resource 540, but reservation 542 can be transmitted within a portion of time-frequency resource 540. In some aspects, UE 215 can transmit an SCI indicating the reservation in the PSCCH portion of resource 540. Therefore, other UEs 215 can detect and / or receive reservation 542 via sensing in the sidelink resource pool 450. Furthermore, in response to detecting reservation 542 for frequency resource 455 on variable time range 458, UE 215 can be configured to set the LBT gap located within that variable time range 458 to zero. In other words, other UEs 215 can leave no LBT gap within the set 456 of M resources reserved only by frequency reservation 454.

[0123] In some cases, one or more time slots of the reserved set 456 of M resources may be preempted or become unavailable during the time between the reservation and / or selection of the set 456 of M resources and the transmission time of the sidelink transmission (e.g., the time slot boundary of time slot 460). For example, another UE 215 with a higher priority or a transmission with a higher priority may preempt one or more time slots of the set 456 of M resources for its corresponding transmission. Additionally or alternatively, the LBT performed before the set 456 of M resources may fail, which may cause UE 215 to suppress transmission in the channel in at least some time slots within the variable time range 458. While one or more time slots of the set 456 of M resources may become unavailable for transmission by UE 215, an additional set of time slots in the variable time range 458 may remain available for transmission using frequency resource 455. For this purpose, the use of the additional set of time slots may not be preempted, and the additional set of time slots may be associated with the passed LBT. Therefore, prior to transmission on the transmission side link, UE 215 can be configured to perform a last-minute reassessment (e.g., at time T3 before the start time Ts of frequency resource reservation 454) and one or more LBTs with respect to a set 456 of M resources to identify time slots available for transmission by UE 215 in the variable time range 458.

[0124] Discussed in relation to each other Figure 6A and 6B This is to explain the last-minute reassessment and LBT of the set of M reserved resources (e.g., frequency resource reservation). Figure 6A This is a flowchart illustrating a method 600 for performing a last-minute reassessment and LBT (Local Time Bypass) of a set of M retained resources, according to some aspects of this disclosure. Method 600 can be implemented by UE215. As explained, method 600 includes several enumeration actions, but aspects of method 600 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0125] In some respects, the UE can reserve frequency resources (e.g., Figure 6BMethod 600 is executed at a time T3 prior to the start time (Ts) of the frequency resource reservation (454). For example, the UE may be configured to execute method 600 at time Ts-T3. Additionally or alternatively, method 600 may be executed based on a frequency resource reassessment request. For example, MAC layer 302 may be configured to transmit a frequency resource reassessment request to PHY layer 304 after selecting a frequency resource reservation (e.g., action 420) and before a sidelink transmission is transmitted (e.g., action 422). Subsequently, the UE may execute method 600 to determine whether any of the reserved M resources are available for transmitting a sidelink transmission, or whether the sidelink transmission should be rescheduled, for example, by transmitting a new sensing request from MAC layer 302.

[0126] At a higher level, during the reassessment at the last moment of time Ts-T3, the UE can determine a subset of available resources (not reserved or preempted by another UE with higher priority) from the set of M resources within the variable time range, and perform LBT (during the LBT interval) before each available resource until an available resource with a successful LBT is found (before that resource). If no available resource with a successful LBT is found, the UE can perform another resource selection.

[0127] In box 602, the UE may set the start index (i) to the slot index corresponding to the start (s) of the frequency resource reservation (e.g., set to the slot index s of the start slot within a variable time range).

[0128] In box 604, the UE can determine whether the time slot (e.g., the resource corresponding to the time slot) corresponding to the start index (time slot (i)) is available. For example, the UE can perform a last-minute reassessment to determine whether the time slot (i) has already been preempted (reserved) by another UE (e.g., because that other UE has higher priority traffic than this UE). The UE can determine preemption based on SCI decoding from PHY sensing and / or predictions from PHY sensing results.

[0129] If, in box 604, the UE determines that the resource corresponding to slot (i) within the frequency resource reservation is unavailable, then in box 606, the UE can increment the start index i to subsequent indices. As an illustrative example, the UE can determine in box 604... Figure 6B The first resource 352a in the set of M resources 456 is unavailable.

[0130] Figure 6B Communication scheme 650 according to some aspects of this disclosure is explained. Scheme 650 can be adopted by UE 215 or any other UE (such as UE 115 and 215). Figure 6BIn this case, the x-axis represents time in some arbitrary units, and the y-axis represents frequency in some arbitrary units.

[0131] Now referring to Figure 6B and Figure 6A of box 604, the UE can determine that the first resource 352a has been pre-empted by another UE (e.g., based on SCI decoding and / or prediction at the first resource 352a). Thus, the UE can move to the next resource (e.g., resource 352b), which corresponds to a time slot with an incremented start index i. As shown, at box 606, the UE can increment the start index i. The unavailability of the first resource 352a is indicated by "x" in Figure 6B In this case.

[0132] Subsequently, at box 608, the UE can determine whether the incremented (e.g., incremented at box 606) start index exceeds the time slot index included in the set of M reserved resources (e.g., i >= s + M - 1). In this way, the UE can determine whether it has completed the iteration through the time slots included in the frequency resource reservation, or whether there are additional time slots remaining for performing a last-minute re-evaluation (e.g., for identifying as available or unavailable).

[0133] If at box 608 the UE determines that there are no time slots (e.g., no resources 352) remaining in the set of M reserved resources for identifying as available or unavailable (e.g., i >= s + M - 1), then the UE 215 can transmit a new sensing request at box 609, as described above referring to Figure 4A For example, if the UE determines at box 608 that there are no time slots remaining in the set of M reserved resources for identifying as available or unavailable, the UE may have determined that each time slot of the frequency resource reservation is unavailable. Thus, the UE can refrain from using the frequency resource reservation for transmission and can alternatively, for example, re-schedule the sidelink transmission by reserving another set of M resources based on the new PHY sensing results.

[0134] On the other hand, if the UE determines at box 608 that time slots remain in the set of M reserved resources for identifying as available or unavailable (e.g., i < s + M - 1), then the UE 215 can continue to determine at box 604 whether the time slot corresponding to the start index i is available.

[0135] Returning to box 604, if the UE determines that the resource corresponding to the time slot (i) is available, then at box 610, the UE can set the end index (j) to the index of the end of a group of time slots back-to-back with the time slot (i) of the frequency resource reservation. For example, as Figure 6BAs explained, in response to determining that the time slot (i) corresponding to the second resource 352b is available, the UE can then determine that the third resource 352c and the fourth resource 352d back-to-back with the second resource 352b are also available, while the fifth resource 352e is not available. Since the second, third, and fourth resources (352b-d) are contiguous, this back-to-back group of time slots can be indexed between the start index i, which was previously set as the index of the second resource 352b, and the end index j, which can be set as the index of the fourth resource 352d.

[0136] At block 612, the UE can perform LBT based on the time slot (i) boundary. For example, the UE 215 can perform LBT in the gap before the time slot (i) time slot boundary. Thus, if the LBT passes at block 614 (e.g., LBT is successful), the UE 215 can transmit a sidelink transmission starting at the resource corresponding to the time slot (i) (e.g., using the frequency resource at the time slot (i) within a variable time range) at block 616. In some aspects, performing LBT can involve performing an independent (e.g., different) LBT each time the method 600 advances to block 612. In other aspects, performing LBT can involve continuing the LBT at block 614 (e.g., continuing the countdown of the LBT), as described in more detail below with reference to Figure 7A and 7B described in more detail.

[0137] On the other hand, if the LBT fails (e.g., LBT is not successful), then at block 618, the UE 21� can determine whether there are additional time slots (e.g., additional resources) remaining between the start index i and the end index j (e.g., whether i < j). For example, if the LBT corresponding to Figure 6B the second resource 352b fails, the UE can determine that the third resource 352c and the fourth resource 352d are still available for continuing the LBT or performing an additional LBT. If there are additional time slots remaining (e.g., i < j), the UE can increment the start index i (e.g., i++) at block 620 to repeat block 612 based on the next time slot boundary.

[0138] If there are no available time slots remaining at block 618 (e.g., i >= j), the UE can determine at block 6^{22} whether the start time of the time slot with the end index j is less than the T3 duration from the last time slot included in the set 456 of the reserved M resources (e.g., j >= s + M - 1 - T3, in time slots). In this way, the UE can determine whether there is time to perform a last-minute re-evaluation for any remaining time slots in the frequency resource reservation after the back-to-back time slot group (resources 352b, 352c, and 352d).

[0139] If, at block 622, the UE determines that there is no time to perform a last-minute re-evaluation of the remaining time slots (after resource 352d) in the set of M reserved resources (e.g., no resource 352), the UE may transmit a new sensing request at block 623, as described above with reference to Figure 4A (e.g., action 410). For example, if the UE determines at block 622 that there are no remaining time slots in the frequency resource reservation for identification as available or unavailable, the UE may have determined that each time slot of the frequency resource reservation is unavailable. As an illustrative example, in response to determining that the ending index j corresponds to Figure 6B the fifth resource 352e (e.g., the last resource in the set 456 of M resources), the UE may transmit a new sensing request. Thus, the UE may refrain from reserving the frequency resource for transmission and may instead re-schedule the sidelink transmission.

[0140] On the other hand, if the UE determines at block 622 that time slots remain in the frequency resource reservation for identification as available or unavailable (e.g., j < s + M - 1 - T3, in time slot units), the UE may continue at block 624 to set the starting index i to j + T3 time slot units. Subsequently, the UE may determine at block 604 whether the time slot corresponding to the updated starting index i is available (by performing a last-minute re-evaluation). For example, if Figure 6B the set 456 of M resources illustrated in

[0141] includes one or more resources 352 after the fifth resource 352e, the UE may continue method 600 to determine whether the time slots corresponding to these resources are available and / or perform LBT at any available time slot.

[0142] Although the identification of time slots in a frequency resource reservation available for UE transmission has been described with respect to method 600, it will be appreciated that any suitable method may be used to identify the time slots in a frequency resource reservation available for UE transmission. For example, in some aspects, the UE may perform a last-minute re-evaluation for each time slot in the frequency resource reservation and may subsequently perform one or more LBTs with respect to the time slots identified as available after the last re-evaluation. Additionally, in some aspects, LBT may be performed before or concurrently with the last-minute re-evaluation of the time slots of the frequency resource reservation. Figure 7A and 7B have been discussed in relation to one another to illustrate performing LBT on a back-to-back time slot group reserved by a frequency resource reservation. Figure 7AThis is a flowchart illustrating a method 700 for performing an LBT (Local Bit-Based Shift) with respect to a back-to-back time slot group reserved by a frequency resource reservation, according to some aspects of this disclosure. Method 700 can be implemented by UE 215. Furthermore, aspects of method 700 can be used to perform aspects of method 600, such as blocks 612, 614, 618, and / or 620. As explained, method 700 includes several enumeration actions, but aspects of method 700 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0143] At box 702, the UE (e.g., UE 115, UE 215) can perform a LBT with a countdown. For example, the UE can perform an LBT that includes random backoff or a countdown, such as a CAT4 LBT (Type 1 LBT). As described herein, the UE can perform an LBT to determine whether it can use frequency resources (e.g., frequency resource 455) to transmit a sidelink transmission in a time slot with a variable time range. Therefore, the UE can perform an LBT based on the time slot boundaries within a set of M resources. For example, the UE can perform an LBT during an LBT gap or immediately before a time slot boundary. To perform an LBT, the UE can draw a random number and perform a countdown based on the drawn number. This random number can indicate the number of time units the UE will perform the LBT for. For example, if the channel remains idle for that number of time units, the UE can transmit on that channel.

[0144] As an illustrative example, Figure 7B The available back-to-back time slot group 750 within the set of M resources 456 is explained. Figure 7B In this context, the x-axis represents time in some arbitrary unit. Group 750 can correspond to the above reference. Figure 6A and 6B The description identifies the available time slots that are indexed between start index i and end index j (e.g., resource 352b-d). Figure 7B This further includes a counter 752 corresponding to the random backoff or countdown of LBT. In some aspects, the UE may perform LBT at a point in the countdown of counter 752 based on the slot boundary 754 of the first slot (e.g., the first resource) in group 750 (e.g., in box 702).

[0145] Return to Figure 7AIn box 704, the UE can determine whether the LBT performed in box 702 passed. For example, the UE can determine whether the countdown at the time slot boundary (when available resources begin) has completed (e.g., reached zero). If the countdown completes at the time slot boundary, the LBT passes; if the countdown is still in progress at the time slot boundary, the LBT may fail. Additionally or alternatively, the LBT passes when the signal energy measured from the channel is below a threshold. Conversely, the LBT fails when the signal energy measured from the channel exceeds the threshold. In another example, the LBT can be based on signal detection. For example, the LBT passes when no channel reservation signal (e.g., a predefined preamble signal) is detected in the channel. Conversely, the LBT fails when a channel reservation signal is detected in the channel.

[0146] For example, in Figure 7B At time slot boundary 754, the countdown is still ongoing (e.g., counter 752 has not yet reached 0). Therefore, in Figure 7A At frame 704, the UE can determine that the LBT performed based on time slot boundary 754 has failed.

[0147] In response to the LBT being confirmed in block 704, the UE can transmit sidelink transmissions in block 706. More specifically, the UE can use frequency resources starting at the time slot boundary on which the LBT is based in block 702 to transmit sidelink transmissions. In this way, the UE can use frequency resources to transmit sidelink transmissions within a variable time range based on the LBT.

[0148] In response to determining LBT failure in block 704, the UE can determine in block 708 whether any time slots (e.g., resources) remain within the set of M reserved resources. More specifically, the UE can determine whether any time slots remain within the available back-to-back time slot groups (such as group 750) reserved by frequency resource reservation.

[0149] about Figure 7B For example, after determining that LBT has failed based on slot boundary 754, the UE can determine two remaining additional slots in block 708. In this way, the UE can determine whether LBT can be performed based on slot boundary 756 and / or slot boundary 758 to determine whether frequency resources within a variable time range can be used to transmit sidelink transmissions at slot boundary 756 and / or slot boundary 758, respectively.

[0150] If the UE determines in block 708 that no time slots remain, the UE can retransmit the sensing request in block 710. To do this, the UE can suppress the use of available back-to-back time slot groups (such as group 750) reserved by frequency resource reservations to transmit sidelink transmissions. Alternatively, in some aspects, the UE can terminate method 700 in response to determining in block 708 that no time slots remain. In such cases, the UE can restart method 700 in block 702 for a different back-to-back time slot group reserved by the same frequency resource reservation. In this way, method 700 can be applied to each available time slot in a set of M resources, or it can be repeated for a subset of available time slots in a set of M resources.

[0151] On the other hand, if the UE determines that a time slot remains in block 708, the UE can resume the countdown in block 712 based on subsequent time slot boundaries. For example, the UE can pause or hold the LBT after performing it in block 702, and then resume the countdown based on different time slot boundaries after that LBT. In this way, the UE can perform the LBT in block 702 based on the resumed countdown. To this end, the UE can perform one or more LBTs by pausing and resuming the LBT based on a set of different time slot boundaries using the same countdown.

[0152] For example, in Figure 7B In the example shown, the countdown of counter 752 is paused based on an LBT failure for time slot boundary 754, and the countdown of counter 752 is resumed before time slot boundary 756. In some aspects, the UE can resume the countdown of counter 752 within an LBT gap 760 positioned before time slot boundary 756, as explained. Furthermore, the UE can perform LBT based on time slot boundary 756 and the resumed countdown of counter 752 (e.g., in block 702). The UE can then determine LBT passage based on time slot boundary 756 and the resumed countdown of counter 752 (e.g., in block 704), and can use frequency resources 455 starting from time slot boundary 756 of variable time range 458 to transmit sidelink transmissions.

[0153] Although method 700 is described herein as resuming the countdown associated with the LBT, it will be understood that any suitable method can be used to perform one or more LBTs based on one or more time slots of the set of M reserved resources. For example, in some aspects, the UE may perform an independent LBT based on each time slot boundary until an LBT is identified as having passed. In this way, the UE can use a separate random backoff or countdown for each time slot boundary.

[0154] As discussed, when reserving resources (e.g., resource 352) and / or a set of M resources (e.g., a set of M resources 456), UE 215 can identify and select candidate resources from the sidelink resource pool 450 based on several factors. For example, PHY layer 304 can identify candidate resources based on a combination of SCI decoding, signal measurement, and / or priority information. Furthermore, while PHY layer 304 can exclude reserved resources associated with a higher priority than that triggered by the current (e.g., active) resource selection (e.g., reservations based on reserved resources and / or transmissions associated with reserved resources), reserved resources with equal or lower priorities can be preempted and / or shared (e.g., conditionally reserved). In this way, a first frequency resource reservation performed by the first UE can be shared by a reservation performed by the second UE, as referenced below. Figure 8A and 8B A more detailed description.

[0155] Figure 8A The reservation sharing between frequency resource reservation 454 and time-frequency resource reservation 813 (e.g., legacy reservation) is explained, which reserves resources with fixed sub-channel indexes and fixed time / slot indexes. Figure 8B The sharing of frequency resources between frequency resource reservation 454 and second frequency resource reservation 820 is explained, whereby the second frequency resource reservation 820 reserves frequency resources in a fixed sub-channel over a second variable time range 822. Figure 8A and 8B In this model, the x-axis represents time in some arbitrary units, while the y-axis represents frequency in some arbitrary units. Furthermore, Figure 8A and Figure 8B The text explains the reservation sharing between reservation 810, which identifies frequency resource reservation 454 made by the first UE, and second subsequent reservations (e.g., 812, 816) identified by time-frequency resource reservation 813 and second frequency resource reservation 820 made by the second UE, respectively.

[0156] like Figure 8AAs explained herein, the first UE may transmit a first reservation 810 that identifies and reserves a set 456 of M resources, as described herein. For example, the first UE may transmit the first reservation 810 after a resource within the frequency resource reservation 454 (e.g., by the PHY layer 304) is identified as available and (e.g., by the MAC layer 302) selected. Furthermore, in some aspects, the first UE may transmit the first reservation 810 only after determining that no resource in the set 456 of M resources has already been reserved for time-frequency resource reservations (e.g., legacy reservations). In other aspects, the first UE may transmit the first reservation 810 only after determining that no resource in the set 456 of M resources has already been reserved for time-frequency resource reservations with a higher priority than that associated with the first reservation.

[0157] Subsequently, the second UE can transmit a second reservation 812, which can identify and reserve the time-frequency resource reservation 813. As described herein, according to Figure 3A In various aspects of method 300, the second UE can reserve time-frequency resource 352f of time-frequency resource reservation 813. For example, the second UE can detect a first reservation 810 on a variable time range 458. The second UE can reserve time-frequency resource 352f in the same sub-channel (frequency resource 455) as the first reservation 810 and in time slots overlapping with the variable time range 458 based on the priority associated with frequency resource reservation 454 and / or the first reservation 810 and the priority associated with resource 352f and / or the second reservation 812. For example, if the priority associated with frequency resource reservation 454 is lower than the priority associated with the traffic priority of the second UE, the second UE can first occupy the use of time slots in the set 456 of M resources (e.g., the time slot corresponding to resource 352f). Furthermore, if the priority associated with frequency resource reservation 454 is equal to the traffic priority of the second UE, the second UE can share the reservation of a subset of the set 456 of M resources (e.g., the subset corresponding to resource 352f). In some respects, the second UE can further determine to share a reservation based on a subset 456 of M resources that no other UE is sharing. In other words, when no other legacy reservation (e.g., with a fixed subchannel index and a fixed time / slot index) is detected for the subset 456 of M resources, the second UE can make a second reservation 812.

[0158] By sharing the reservation, if resource 352f remains unused by the first UE, the second UE can use resource 352f to transmit sidelink transmissions. To this end, instead of treating each resource in the set 456 of M resources reserved by frequency resource reservation 454 as unavailable (e.g., excluding resources from the candidate resources), the second UE can treat the resources in the set 456 of M resources as conditionally available. More specifically, frequency resource reservation 454 includes several time slots within a variable time range 458, which can create redundancy. However, the first UE can use frequency resource 455 to transmit sidelink transmissions within a subset of time slots within the variable time range 458, leaving the originally unused portion of frequency resource reservation 454. Therefore, the second UE can reserve resource 352f so that resource 352f can be used by the second UE (if available). Furthermore, in some aspects, the first UE can ignore the second reservation 812 during last-minute re-evaluation (e.g., block 604 of method 600). Therefore, the first UE can still use resource 352f for sidelink transmissions if needed.

[0159] In some respects, when a second UE (reservation 813 of the second UE) has a lower traffic priority than the first UE (reservation 454), the second UE may share the reservation; however, the reservation of the second UE may be restricted to later time slots within the variable time range 458 of reservation 454. In this regard, if the priority associated with frequency resource reservation 454 is greater than the priority associated with resource reservation 813, the second UE may share the reservation of resource 352f, as generally described above. However, the shared reservation may be restricted to resources at the end of the set 456 of M resources (e.g., within the last 1, 2, 3 time slots of the variable time range 458, etc.). Resources within the set 456 of M resources available for shared reservations with lower priority reservations may be pre-configured in the first and / or second UE and / or may depend on information included in the SIB, RRC configuration, and / or determined based on CBR estimation.

[0160] Figure 8B The first reservation 810, transmitted by the first UE for frequency resource reservation 454, and the second reservation 816, transmitted by the second UE for the second frequency resource reservation 820 on the variable time range 822, are explained. The second UE can transmit as described above. Figure 8AThe second reservation 816 and the second reservation 812 are generally described. In this way, the second UE can preemptively occupy the first frequency reservation 454 based on the higher priority second frequency resource reservation 820, and can share a portion of the first frequency resource reservation 454 based on the second frequency resource reservation 820 with an equal or lower priority relative to the first frequency resource reservation 454. For this purpose, the variable time range 822 of the second frequency resource reservation 820 can overlap with the variable time range 458 of the frequency resource reservation 454. Furthermore, in some aspects, when the second frequency resource reservation 820 is associated with the same priority as the first frequency resource reservation 454, the second UE can be configured to only partially overlap with the frequency resource reservation (e.g., share a portion of the frequency resource reservation 454 instead of all of it). Furthermore, in the case of the lower priority second frequency resource reservation 820, the partial overlap can be limited to the time slot at the end of the frequency resource reservation 454, as described above. By only partially overlapping with the frequency resource reservation 454, the second UE can increase the possibility that the second UE can use the second frequency resource 821 to transmit sidelink transmissions within the second variable time range 822. Alternatively, the second UE may be configured to share all of the first frequency resource reservation 454 with the second frequency resource reservation 820 if the priority associated with the first and second reservations (e.g., 810 and 816, respectively) is equal.

[0161] In some respects, the second UE can also be configured to share the reservation of one or more resources based on the determination that one or more resources in the set 456 of the first M resources have not yet been shared or reserved by another UE (e.g., for a third frequency resource reservation or a time-frequency resource reservation). In this way, the reservation of a specific resource of the first frequency resource reservation can be shared only by the first UE and one other device.

[0162] Figures 9A-9C The document explains the reservation clusters corresponding to different TBs made by the same UE (e.g., UE 215). Figures 9A-9C In this diagram, the x-axis represents time in some arbitrary unit, and the y-axis represents frequency in some arbitrary unit. Figures 9A-9C Use and Figure 4B Similar resources and / or reserved configurations will be used for explanation, and the same reference numerals may be used for simplicity.

[0163] In some aspects, UE 215 may transmit a first reservation 910 that identifies and reserves a set 456 of first M resources for transmitting a first TB, as described herein. For example, the UE may transmit the first reservation 910 after resources within frequency resource reservation 454 (e.g., by PHY layer 304) are identified as available and (e.g., by MAC layer 302) selected. After the first reservation 910 is transmitted and / or after the set 456 of first M resources is selected, the UE may prepare to transmit a second reservation 912, which corresponds to a second frequency resource reservation 913 for a set 914 of second M resources within a variable time range 915, or corresponds to time-frequency resources (e.g., legacy reservations) for transmitting a different second TB (carrying different information bits than the first TB). In some aspects, the UE may identify and / or select resources for the second frequency reservation 912 based on the first reservation 910 and / or the set 456 of first M resources. For example, the UE can select resources corresponding to the second reservation 912 such that they are adjacent to or overlap with at least one subset of the set 456 of the first M resources (e.g., positioned (in the time or frequency domain) adjacent to or overlapping with the at least one subset). By clustering the set 914 of the second M resources (as explained) and / or the time-frequency resources with the set 456 of the first M resources, the UE can reduce the number of LBTs performed to transmit the first and second TBs (e.g., first and second sidelink transmissions) using the first and second resources respectively. In this way, clustering can improve robustness with respect to LBTs.

[0164] Figure 9A This section explains cluster resource selection for frequency resource reservation using Frequency Division Multiplexing (FDM) technology. To this end, Figure 9A The explanation describes the clustering of a first set 456 of resources corresponding to the first reservation 910 and a second set 914 of resources corresponding to the second reservation 912, such that they correspond to corresponding sub-channels adjacent to each other in the frequency domain (e.g., adjacent frequency resources 455 and 916, respectively). To achieve such frequency and / or sub-channel clustering, the MAC layer 302 can be configured to perform clustered resource selection instead of the aforementioned random resource selection. In this way, the MAC layer 302 can filter and select resources within sub-channels adjacent to the sub-channels corresponding to the first set 456 of resources. By clustering resources (such as the explained first set 456 of resources and the second set 914 of resources), the UE can cluster the transmission of the first and second TBs on the same time slot. For example, the UE can transmit the first and second TBs starting from the time slot boundary 918 using the first frequency resource 455 and the second frequency resource 916, respectively.

[0165] In some aspects, to cluster the transmissions of the first and second TBs on the same time slot, the UE can be configured to perform self-delay after the LBT passes. For example, suppose a first UE determines that an LBT has passed associated with time slot boundary 920. In some aspects, the UE can perform self-delay such that instead of transmitting the first TB from time slot boundary 920, the UE waits until time slot boundary 918 to transmit both the first and second TBs (e.g., using first frequency resource 455 and second frequency resource 916, respectively). However, by performing self-delay, the UE may risk missing transmission opportunities associated with the LBT passing. For example, traffic may occur between the LBT passing and time slot boundary 918, which could prevent the UE from transmitting at time slot boundary 918. Therefore, in other aspects, the UE can be configured to transmit sidelink transmissions at the earliest opportunity.

[0166] Figure 9B This section explains cluster resource selection for resource reservation using Time Division Multiplexing (TDM) technology. To this end, Figure 9B The resources corresponding to the first reservation 910 and the second reservation 912 are clustered such that they correspond to the same subchannel and are located in adjacent time slots in the time domain. To achieve this time-based clustering, the MAC layer 302 can be configured to perform clustered resource selection instead of the random resource selection described above. In this way, the MAC layer 302 can filter and select resources within the same subchannel (e.g., corresponding to frequency resource 455) as the set 456 of the first M resources, as well as resources within time slots or time slot groups adjacent to the variable time range 458. As shown, the second reservation 912 reserves resource 352g in the time slot adjacent to the last time slot of the set 456 of the M resources.

[0167] Figure 9C The overlapping clusters were explained. Therefore, Figure 9C The resources corresponding to the first reservation 910 and the resources corresponding to the second reservation 912 are clustered such that they at least partially overlap. To achieve such overlapping clustering, the MAC layer 302 can be configured to perform clustered resource selection instead of the random resource selection described above. In this way, the MAC layer 302 can filter and select at least some resources corresponding to the set 456 of M resources of the first frequency resource reservation 454. For example, the MAC layer 302 performs a second reservation 942 on the frequency resource 455 in the same subchannel as the frequency resource 455 of the first reservation 910 but on a different variable time range 945 that partially overlaps with the variable time range 458 (shown by resource set 944).

[0168] By clustering resources over time, such as at least in Figure 9B and 9CAs explained, the UE can transmit the first and second TBs in different time slots. Furthermore, in some aspects, the UE can reduce the number of LBTs used to transmit the first and second TBs. For example, at time slot boundaries marked with a variable time range of 458 (such as... Figure 9B The time slot boundary 922 or Figure 9C After passing through the LBT (corresponding to the time slot boundary 952), the UE can transmit the first TB. Furthermore, after transmitting the first TB, the UE can continue to use the same subchannel and second resource (e.g., a second time-frequency resource or a set of the second M resources) to... Figure 9B The time slot boundary 924 and Figure 9C The second TB is transmitted at time slot boundary 954 without performing another LBT. Additionally or alternatively, in some aspects, the UE may pause the countdown corresponding to the failed LBT based on time slot boundary 922, and may also based on... Figure 9B The countdown can continue at time slot boundary 924, as described above regarding method 700. Similarly, the UE can pause the countdown corresponding to the failed LBT based on time slot boundary 952, and can also based on... Figure 9C The time slot boundary 954 shown in the figure continues the countdown as described above regarding method 700.

[0169] Turn now Figure 10 The flowchart of method 1000 for transmitting soft reservation is explained. Method 1000 can be implemented by UE215. As explained, method 1000 includes several enumeration actions, but aspects of method 1000 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0170] As used herein, the term "soft reservation" can refer to a reservation for a second transport block that accompanies a reservation for a first transport block and / or a retransmission of the first transport block. For example, the UE can use the techniques described herein to reserve resources, such as a set of M resources 456. Furthermore, while reserving resources, the UE can perform a time-scheduled retransmission after that resource, such as a HARQ retransmission. In some aspects, the UE can be additionally configured to transmit the second TB after transmitting the first transport block. For example, the UE can include data that queues for transmissions in the second TB while making a reservation for the first TB. Therefore, instead of waiting until the reservation of resources for the first TB is complete to reserve resources for the second TB, the UE can transmit the soft reservation corresponding to the second TB together with the reservation corresponding to the first TB, as described in more detail below.

[0171] In block 1002, the UE may transmit a soft reservation. The UE may transmit the soft reservation together with or within a reservation for frequency resources (e.g., frequency resource reservation 454). The reservation may identify a first set of M resources, which may correspond to frequency resources within a variable time range, suitable for transmission or retransmission of a first TB, while the soft reservation may identify a second set of M resources, which may correspond to second frequency resources within a second variable time range, suitable for transmission of a different second TB. According to some aspects, the UE may identify and / or select the second set of M resources from the same candidate resources from which the UE identifies and / or selects the first set of M resources.

[0172] For example, UE 215's MAC layer 302 can transmit a resource selection trigger to the PHY layer, and in response, the PHY layer 304 can identify candidate resources and transmit a candidate resource report to the MAC layer 302, as referenced herein. Figure 4A The MAC layer 302 can then filter candidate resources to select a first set of M resources. Subsequently, the MAC layer 302 can select a second set of M resources from the remaining candidate resources. After selecting both the first set of M resources and the second set of M resources, the UE 215 can transmit a reservation (e.g., a reservation message or SCI). This reservation may include information identifying the first set of M resources, and a soft reservation, which may include information identifying the second set of M resources. In some aspects, the UE may transmit reservations and soft reservations separately (in different SCIs).

[0173] After transmitting the soft reservation, the UE can determine in block 1004 whether the soft reservation has been preempted (reserved by a higher-priority UE). For example, the UE can determine whether another UE has already preempted the use of the set of the second M resources associated with the soft reservation. If the UE determines in block 1004 that the soft reservation has not been preempted, the UE can use the set of the second M resources corresponding to the soft reservation (e.g., using the second frequency resources within the second variable time range) in block 1006 to transmit the sidelink transmission corresponding to the second TB. Furthermore, in some aspects, if the UE determines that only resources corresponding to a different subset of the second time slots within the second variable time range have been preempted, the UE can use a first subset of the time slots within the second variable time range to transmit the sidelink transmission.

[0174] If, in box 1004, the UE determines that the soft reservation is preempted, then in box 1008, the UE may suppress the use of the second set of M resources to transmit sidelink transmissions corresponding to the second TB. Alternatively, the UE may suppress the use of resources corresponding to a preempted subset of slots within a second variable time range (such as the second subset described above) to transmit sidelink transmissions.

[0175] Figure 11 A flowchart of method 1100 for receiving or detecting a soft hold is provided. Method 1100 can be implemented by UE 215. As explained, method 1100 includes several enumeration actions, but aspects of method 1100 may include additional actions before, after, and between these enumeration actions. In some aspects, one or more of these enumeration actions may be omitted or performed in a different order.

[0176] In box 1102, the UE may receive a soft reservation. For example, a first UE may receive and / or identify a soft reservation transmitted by a second UE. In some respects, the first UE may identify the soft reservation based on SCI decoding or any suitable method.

[0177] In box 1104, the UE can be configured to attempt to bypass soft reservations to retain frequency resource reservations. For example, to transmit a sidelink transmission (e.g., a transport block), the UE can be configured to reserve a frequency resource and can attempt to reserve that frequency resource using a set of M resources that are not preemptively reserved within a variable time range. In this way, the UE can make a best effort to avoid preemptively reserving soft reservations. For example, in response to a resource selection trigger associated with a sidelink transmission, PHY layer 304 can be configured to identify candidate resources that exclude the set of M resources identified by soft reservations.

[0178] In box 1106, the UE can determine whether there are resources available to bypass soft reservation to reserve frequency resources (e.g., a set of M resources). For example, MAC layer 302 can determine whether the number of candidate resource sets identified by PHY layer 304 meets (e.g., meets or exceeds) a threshold, as referenced above. Figure 4A As described.

[0179] If the UE determines in box 1106 that there are sufficient resources to reserve frequency resources, the UE can reserve frequency resources in box 1108. In this case, the UE can avoid preempting soft reservations. In other words, the UE can comply with a soft reservation by reserving frequency resources using resources different from those identified by the soft reservation.

[0180] On the other hand, if the UE determines in block 1106 that there are insufficient resources to reserve frequency resources, the UE can pre-allocate a soft reservation or a portion of the soft reservation (e.g., a subset of time slots) in block 1110. According to some aspects, if at least a portion of the second frequency resources corresponding to the soft reservation is pre-allocated, the UE can determine in block 1110 whether there are sufficient resources to reserve frequency resources. If so, the UE can reserve frequency resources by pre-allocating at least a subset of the set of the second M resources. Additionally or alternatively, in response to determining in block 1106 that there are insufficient resources to reserve frequency resources, the UE can relax (e.g., reduce) the threshold used in block 1106.

[0181] In some respects, UE 215 can utilize the above-mentioned... Figures 4A-4B and Figure 5 The frequency of the discussion and resource reservation, the above regarding Figures 6A-6B Last-minute reassessment and execution of one or more LBTs, above regarding Figures 7A-7B The discussion concerns the execution of one or more LBTs for a time slot group within a variable time range, and the above regarding... Figures 8A-8B Frequency resource reservation sharing between the two UEs discussed above. Figures 9A-9C The frequency of resource reservation clusters discussed, and / or the above regarding Figure 10-11 Any suitable combination of soft reservations discussed.

[0182] Figure 12 This is a block diagram of an exemplary BS 1200 according to some aspects of this disclosure. BS 1200 may be as described above. Figure 1 The network 100 discussed herein includes a BS 105. As shown, the BS 1200 may include a processor 1202, a memory 1204, a sidelink configuration module 1208, a transceiver 1210 including a modem subsystem 1212 and an RF unit 1214, and one or more antennas 1216. These components may communicate directly or indirectly with each other, for example, via one or more buses.

[0183] Processor 1202 may have various features as a special-purpose processor. For example, these features may include a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 1202 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0184] Memory 1204 may include cache memory (e.g., cache memory of processor 1202), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or combinations of different types of memory. In some aspects, memory 1204 may include non-transient computer-readable medium. Memory 1204 may store instructions 1306. Instructions 1306 may include causing processor 1202 to perform the operations described herein when executed by processor 1202 (e.g., ...). Figure 1-2Instructions (in various aspects). Instruction 1306 may also be referred to as program code. Program code can be used to cause a wireless communication device to perform these operations, for example by causing one or more processors (such as processor 1202) to control or command the wireless communication device to do so. The terms "instruction" and "code" should be interpreted broadly to include any type of computer-readable statement. For example, the terms "instruction" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, etc. "Instruction" and "code" may include a single computer-readable statement or many computer-readable statements.

[0185] The sidelink configuration module 1208 may be implemented via hardware, software, or a combination thereof. For example, the sidelink configuration module 1208 may be implemented as a processor, circuitry, and / or instructions 1306 stored in memory 1204 and executed by processor 1202. In some examples, the sidelink configuration module 1208 may be integrated within the modem subsystem 1212. For example, the sidelink configuration module 1208 may be implemented by a combination of software components (e.g., executed by a DSP or general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1212.

[0186] The sidelink configuration module 1208 can communicate with one or more components of the BS 1200 to perform various aspects of this disclosure, such as... Figure 1-2 All aspects. The sidelink configuration module 1208 is configured to configure the UE (e.g., UE 115, 215) with sidelink configuration for sidelink communication (e.g., sidelink resource pool 450) and / or configuration for a variable time range size M when the UE is within the coverage of BS 1200.

[0187] As shown, transceiver 1210 may include modem subsystem 1212 and RF unit 1214. Transceiver 1210 may be configured to communicate bidirectionally with other devices, such as UE 115 and / or another core network element. Modem subsystem 1212 may be configured to modulate and / or encode data according to MCS (e.g., LDPC decoding scheme, turbo decoding scheme, convolutional decoding scheme, digital beamforming scheme, etc.). RF unit 1214 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / encoded data transmitted from modem subsystem 1212 (on out-of-band transmission) or originating from another source (such as UE 115) (e.g., RRC configuration, sidelink resource pool configuration, frequency resource reservation only configuration). RF unit 1214 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in transceiver 1210, modem subsystem 1212 and / or RF unit 1214 may be separate devices coupled together at BS 105 so that BS 105 can communicate with other devices.

[0188] RF unit 1214 may provide modulated and / or processed data (e.g., data packets (or more generally, data messages containing one or more data packets and other information)) to antenna 1216 for transmission to one or more other devices. This may include, for example, information transmission for completing attachment to the network and communication with the resident UE 115, according to some aspects of this disclosure. Antenna 1216 may further receive data messages transmitted from other devices and provide the received data messages for processing and / or demodulation at transceiver 1210. Transceiver 1210 may provide demodulated and decoded data to sidelink configuration module 1208 for processing. Antenna 1216 may include multiple antennas of similar or different designs to maintain multiple transmission links.

[0189] In one aspect, the BS 1200 may include multiple transceivers 1210 implementing different RATs (e.g., NR and LTE). In another aspect, the BS 1200 may include a single transceiver 1210 implementing multiple RATs (e.g., NR and LTE). In yet another aspect, the transceiver 1210 may include various components, wherein different combinations of the components can implement different RATs.

[0190] Figure 13 This is a block diagram of an exemplary UE 1300 according to some aspects of this disclosure. UE 1300 may be as described above regarding... Figure 1 The UE 115 discussed above, or as mentioned above... Figure 2 , 3AUE 215 discussed in -3B, 4A-4B, 5, 6A-6B, 7A-7B, 8A-8B, 9A-9C, 10, and 11. As shown in the figure, UE 1300 may include a processor 1302, a memory 1304, a sidelink module 1308 based on frequency resource reservation, a transceiver 1310 including a modem subsystem 1312 and a radio frequency (RF) unit 1314, and one or more antennas 1316. These components may communicate directly or indirectly with each other, for example, via one or more buses.

[0191] Processor 1302 may include a central processing unit (CPU), digital signal processor (DSP), application-specific integrated circuit (ASIC), controller, field-programmable gate array (FPGA) device, other hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 1302 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0192] Memory 1304 may include cache memory (e.g., cache memory of processor 1302), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard disk drives, other forms of volatile and non-volatile memory, or combinations of different types of memory. In one aspect, memory 1304 includes a non-transient computer-readable medium. Memory 1304 may store or have instructions 1306 recorded thereon. Instructions 1306 may include, when executed by processor 1302, causing processor 1302 to perform various aspects of this disclosure in conjunction with reference to UE 115 and / or 215 (e.g., ...). Figure 2 , 3A Instructions 1306 (including aspects of -3B, 4A-4B, 5, 6A-6B, 7A-7B, 8A-8B, 9A-9C, 10, 11, and 14) describe the operations. Instruction 1306 may also be referred to as program code, which can be broadly interpreted as including, as referenced above... Figure 12 Any type of computer-readable statement discussed.

[0193] The frequency resource reservation-based sidelink module 1308 can be implemented via hardware, software, or a combination thereof. For example, the frequency resource reservation-based sidelink module 1308 can be implemented as a processor, circuitry, and / or instructions 1306 stored in memory 1304 and executed by processor 1302. In some examples, the frequency resource reservation-based sidelink module 1308 can be integrated within the modem subsystem 1312. For example, the frequency resource reservation-based sidelink module 1308 can be implemented by a combination of software components (e.g., executed by a DSP or general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1312.

[0194] The sidelink module 1308 based on frequency resource reservation can communicate with one or more components of the UE 1300 to perform various aspects of this disclosure, such as... Figure 2 , 3A -3B, 4A-4B, 5, 6A-6B, 7A-7B, 8A-8B, 9A-9C, 10, 11, and 14. In some aspects, the side link module 1308 based on frequency resource reservation is configured to reserve frequency resources within an instance of variable time range, for example, as mentioned above regarding... Figures 4A-4B The following are discussed in sections 5, 8A-8B, 9A-9C, 10, and 11.

[0195] The frequency resource-reserved sidelink module 1308 is further configured to perform sensing within a pool of sidelink resources in a shared radio frequency band. Sensing or monitoring may include decoding the SCI and / or measuring signal energy in the channel. The frequency resource-reserved sidelink module 1308 may be configured to blindly decode the SCI from the PSCCH of each resource, record the decoded SCI upon successful decoding, determine signal measurements (e.g., RSRP and / or RSSI) for each resource, and record the signal measurements.

[0196] The frequency resource reservation-based sidelink module 1308 is further configured to reserve frequency resources within an instance of a variable time range based on the sensing. For example, the frequency resource reservation-based sidelink module 1308 may be configured to identify and select time-adjacent resources (e.g., a set of M resources) identified as available based on the sensing. Subsequently, the frequency resource reservation-based sidelink module 1308 may transmit a reservation message identifying the selected resources (e.g., identifying the sub-channels and / or time slot indices associated with these resources) to reserve frequency resources within a variable time range, as described above. Figures 4A-4B And the five discussed.

[0197] The frequency resource-reserved sidelink module 1308 is further configured to perform one or more LBTs in a shared radio frequency band. To this end, the frequency resource-reserved sidelink module 1308 can be configured to perform LBTs based on one or more time slot boundaries within an instance of a variable time range, identifying time slots within the frequency resource available for sidelink transmission, as described above. Figures 6A-6B As discussed in 7A-7B.

[0198] In some aspects, the frequency resource reservation-based sidelink module 1308 is further configured to perform reservation sharing with another UE (e.g., UE 115, 215, and / or 1300), as described above regarding Figures 8A-8B The discussion focuses on the following. In some aspects, the frequency resource reservation-based sidelink module 1308 is further configured to perform resource reservation for multiple TBs by clustering the reserved resources in FDM and / or TDM modes, thereby reducing the number of LBTs used to transmit multiple TBs, as discussed above. Figures 9A-9C The discussion focuses on the following. In some aspects, the sidelink module 1308 based on frequency resource reservation is further configured to perform only soft frequency reservation and / or take into account the soft frequency reservation of another UE (e.g., UE 115, 215, and / or 1300), as discussed above. Figure 10 and 11 The subject of discussion.

[0199] As shown, transceiver 1310 may include modem subsystem 1312 and RF unit 1314. Transceiver 1310 may be configured to communicate bidirectionally with other devices, such as BS 105. Modem subsystem 1312 may be configured to modulate and / or encode data from memory 1304 and / or from sidelink module 1308 based on frequency resource reservation, according to modulation and coding schemes (MCS) (e.g., low-density parity-check (LDPC) coding scheme, turbo coding scheme, convolutional coding scheme, digital beamforming scheme, etc.). RF unit 1314 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / coded data (e.g., PSCCH SCI, PSSCH data, frequency-only, time-frequency legacy, soft-frequency-only) transmitted from modem subsystem 1312 (in out-of-band transmission) or from another source (such as UE 115 or BS 105). RF unit 1314 can be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in transceiver 1310, modem subsystem 1312 and RF unit 1314 can be separate devices coupled together at UE 115 to enable UE 115 to communicate with other devices.

[0200] RF unit 1314 can provide modulated and / or processed data (e.g., data packets (or more generally, data messages that may include one or more data packets and other information)) to antenna 1316 for transmission to one or more other devices. Antenna 1316 can further receive data messages transmitted from other devices. Antenna 1316 can provide received data messages for processing and / or demodulation at transceiver 1310. Transceiver 1310 can provide demodulated and decoded data (e.g., RRC configuration, sidelink resource pool configuration, PSCCH SCI, PSSCH data, frequency reservation only, time-frequency legacy reservation, soft frequency reservation only) to a frequency resource reservation-based sidelink module 1308 for processing. Antenna 1316 may include multiple antennas of similar or different designs to maintain multiple transmission links. RF unit 1314 can configure antenna 1316.

[0201] In some aspects, processor 1302 is configured to communicate with one or more components of UE 1300 to sense a sidelink resource pool within a shared radio frequency band, based on the sensing, reserve frequency resources of the sidelink resource pool within an instance of a variable time range, and perform one or more LBTs within the shared radio frequency band. Transceiver 1310 is configured to communicate with one or more components of UE 1300 to transmit sidelink transmissions to a second UE (e.g., UE 115 and / or 215) using the frequency resources within the instance of the variable time range based on the one or more LBTs.

[0202] In one aspect, UE 1300 may include multiple transceivers 1310 implementing different RATs (e.g., NR and LTE). In another aspect, UE 1300 may include a single transceiver 1310 implementing multiple RATs (e.g., NR and LTE). In yet another aspect, transceiver 1310 may include various components, wherein different combinations of the components can implement different RATs.

[0203] Figure 14 This is a flowchart of a wireless communication method 1400 according to some aspects of the present disclosure. Aspects of method 1400 can be performed by a computing device of a wireless communication device (e.g., a processor, processing circuitry, and / or other suitable components) or other suitable means for performing the steps. For example, a wireless communication device (such as UE 115, 215, 1300) can utilize one or more components (such as processor 1302, memory 1304, frequency resource reservation-based sidelink module 1308, transceiver 1310, modem 1312, and one or more antennas 1316) to perform the steps of method 1400. Method 1400 can be implemented as described above. Figures 4A-4BSimilar mechanisms are described in 5, 6A-6B, 7A-7B, 8A-8B, 9A-9C, 10, and 11. As explained, method 1400 includes several enumeration steps, but aspects of method 1400 may include additional steps before, after, and between these enumeration steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

[0204] In block 1410, the UE can perform sensing within a sidelink resource pool (e.g., sidelink resource pool 450) within a shared radio frequency band. In some aspects, the UE can continuously sense or monitor resources in the sidelink resource pool (e.g., performed by the PHY layer at the UE). Sensing or monitoring may include decoding SCIs and / or measuring signal energy in the channel. For SCI decoding, the UE can blindly decode the SCI from the PSCCH of each resource. If decoding is successful, the UE can record the decoded SCI. For signal measurement, the UE can receive signals from each resource and calculate RSRP and / or RSSI for each resource. The UE can also record signal measurements. In some aspects, the UE can receive a sensing request from the PHY layer that includes an indication of instances with variable time ranges (such as an indication of the size M of the instances with variable time ranges) and can perform sensing based on the sensing request. In some respects, the UE may utilize one or more components, such as processor 1302, memory 1304, frequency resource reservation-based sidelink module 1308, transceiver 1310, modem 1312, and one or more antennas 1316, to perform the operation at block 1410.

[0205] In box 1420, the UE can reserve frequency resources of the sidelink resource pool within an instance of a variable time range based on the sensing. In some aspects, the UE can identify resources for reserving frequency resources within the resource selection window by examining or analyzing sensing results obtained within the sensing window (e.g., decoded SCI and / or signal measurements). The UE can filter resources in the resource selection window based on decoded SCI, signal measurements, and / or traffic priorities associated with sidelink transmissions. The UE can further filter resources based on the size M of the instance of the variable time range. In this way, the UE can select time-adjacent resources to reserve a set of M resources. After identifying and selecting the set of M resources, the UE can reserve the frequency resources by transmitting a reservation (e.g., a reservation message) that identifies the sub-channel of the frequency resource, the index of the first time slot of the frequency resource, etc., as referenced above. Figure 5 As described. In some respects, the UE may utilize one or more components, such as processor 1302, memory 1304, frequency resource reservation-based sidelink module 1308, transceiver 1310, modem 1312, and one or more antennas 1316, to perform the operation at block 1420.

[0206] In block 1430, the UE may perform one or more LBTs in the shared radio frequency band. In some aspects, the UE may perform the one or more LBTs based on the slot boundaries of an instance of a variable time range. For example, the UE may perform an LBT at the slot boundary corresponding to a resource in a set of M resources, which is identified as available after the UE performs a re-evaluation of the slot at the last moment. In some aspects, the UE may perform a first LBT based on a first slot boundary in an instance of a variable time range within the shared radio frequency band. The UE may also perform a second LBT based on a second slot boundary following the first slot boundary in response to identifying a failure of the first LBT. In some aspects, the UE may proceed to block 1440 to perform a sidelink transmission in response to identifying a success of the second LBT. Furthermore, in some aspects, the UE may perform the first LBT by executing a countdown until the first slot boundary, and the UE may perform the second LBT by resuming the countdown.

[0207] In some respects, the UE may utilize one or more components (such as processor 1302, memory 1304, frequency resource reservation-based sidelink module 1308, transceiver 1310, modem 1312, and one or more antennas 1316) to perform the operation at block 1430.

[0208] In block 1440, the UE may use the frequency resources to transmit sidelink transmissions to a second UE within the instance of the variable time range based on the one or more LBTs. In some aspects, the UE may utilize one or more components, such as processor 1302, memory 1304, frequency resource-reserved sidelink module 1308, transceiver 1310, modem 1312, and one or more antennas 1316, to perform the operation at block 1440.

[0209] In some aspects, the variable time range instance spans one or more adjacent time slots. In some aspects, the frequency resource is in the same subchannel of the side link resource pool on the variable time range instance. Furthermore, in some aspects, reserving frequency resources (e.g., box 1420) includes transmitting a reservation including at least one of a subchannel index identifying the frequency resource or a time slot index identifying the start time slot of the variable time range instance, as described above regarding... Figure 5 As described.

[0210] In some aspects, the UE may determine the variable time range based on a predetermined value. For example, the UE and / or the MAC layer (e.g., MAC layer 302) may determine the variable time range (e.g., the size M of the variable time range) based on a predetermined value. Additionally or alternatively, in some aspects, the UE may receive an indication of the variable time range in at least one of the RRC configuration or the SIB. Furthermore, in some aspects, the UE may determine the variable time range based on at least one of the PDB or traffic priority associated with sidelink transmissions. In some aspects, the UE may determine the variable time range based on the Channel Busy Rate (CBR) associated with the sidelink resource pool, as described above regarding... Figures 4A-4B As described.

[0211] In some aspects, the UE can receive candidate resources based on sensing identifiers at the MAC layer (e.g., MAC layer 302) (e.g., box 1410). Furthermore, the UE can identify a subset of candidate resources by the MAC layer, which has a number of adjacent time slots greater than or equal to the number of adjacent time slots within the instance of the variable time range. The UE can further reduce the number of adjacent time slots within the instance of the variable time range by the MAC layer based on the failure of the number of candidate resources in the subset to meet a threshold. In some aspects, the UE can retain a set of M resources corresponding to the frequency resources within the reduced number of adjacent time slots within the instance of the variable time range. Furthermore, in some aspects, the UE can retain frequency resources by transmitting a sensing request at the MAC layer including an indication of a candidate set size threshold for the resource selection window, as described above regarding... Figures 4A-4B The subject of discussion.

[0212] In some aspects, instances of variable time ranges include a set of time slots, and the UE can determine that a first subset of this set of time slots is unavailable for transport sidelink transmission. In such aspects, transport sidelink transmission may involve using frequency resources within a second subset of the time slot set of the instance of the variable time range for transport sidelink transmission. This second subset excludes the first subset, as described above regarding... Figures 6A-6B The subject of discussion.

[0213] In some aspects, the UE can detect reservations of second frequency resources within a second instance of the variable time range from a third UE in the link resource pool on that side. In response, the UE can set the LBT gap within the second instance of the variable time range to zero. In some aspects, the UE can reserve time-frequency resources in the time slots of the second instance of the variable time range and in the sub-channels of the second frequency resources based on the detected reservations from the third UE. The reservation of time-frequency resources can be based on a reservation priority or reservations used in at least one of the second instances of the variable time range. In some aspects, the UE can detect reservations from the third UE and can reserve frequency resources in the sub-channels of the second frequency resources and within the instance of the variable time range. The UE can reserve frequency resources based on a reservation priority or reservations used in at least one of the second instances of the variable time range, and the instance of the variable time range can at least partially overlap with the second instance of the variable time range. Furthermore, the UE can reserve frequency resources based on determining that there are no other frequency resource reservations that overlap with the second instance of the variable time range in the corresponding instance of the variable time range. Furthermore, in some aspects, the UE can reserve frequency resources so that an instance of a variable time range does not overlap with one or more time slots at the beginning of a second instance of that variable time range, as mentioned above. Figures 8A-8B As described.

[0214] In some respects, the UE can reserve a second frequency resource within a second instance of the sidelink resource pool in a variable time range. The second instance of the variable time range may at least partially overlap with an instance of the variable time range, and the second frequency resource may reside in a different subchannel than the first instance, as described above. Figure 9A As described.

[0215] In some respects, the UE can reserve the second frequency resource of the sidelink resource pool within the second instance of the variable time range. The second instance of the variable time range may not overlap with other instances of the variable time range, and the second frequency resource may reside in the same subchannel as that frequency resource, as described above regarding... Figure 9B As described.

[0216] In some respects, the UE can reserve a second frequency resource within a second instance of the sidelink resource pool in a variable time range. The second instance of the variable time range may at least partially overlap with an instance of the variable time range, and the second frequency resource may be located in the same subchannel as that frequency resource, as described above regarding... Figure 9C As described.

[0217] In some aspects, the UE can reserve second frequency resources of the sidelink resource pool within a second instance of the variable time range. The second instance of the variable time range may at least partially overlap with or be adjacent to an instance of the variable time range. According to such aspects, the UE can transmit sidelink transmissions during a first time slot within the instance of the variable time range, based on a delay originating from a first LBT of the one or more LBTs. The first time slot may be adjacent to the beginning of the second instance of the variable time range. The UE can further transmit second sidelink transmissions to a third UE using the second frequency resources during a second time slot at the beginning of the second instance of the variable time range, as described above regarding... Figures 9A-9C As described.

[0218] In some aspects, the UE can transmit a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of a variable time range. According to such aspects, the UE can transmit a sidelink transmission including a first transport block, and the soft reservation can be associated with a second transport block different from the first transport block. In response to determining that the soft reservation has not been pre-allocated, the UE can use the second frequency resource within the second instance of the variable time range to further transmit a second sidelink transmission including the second transport block to a third UE. Additionally or alternatively, the UE can suppress the use of the second frequency resource to transmit a second sidelink transmission including the second transport block within the second instance of the variable time range in response to determining that the soft reservation has been pre-allocated, as described above regarding... Figure 10 As described.

[0219] In some aspects, the UE may identify candidate resources in the sidelink resource pool within a resource selection window based on this sensing. The UE may also receive from a third UE a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of a variable time range. The soft reservation may be associated with one or more of the candidate resources. Subsequently, the UE may determine (e.g., consider) that one or more of the candidate resources as unavailable based on the soft reservation. The UE may further select frequency resources from the candidate resources based on the number of remaining candidate resources. This selection may involve selecting frequency resources within the instance of the variable time range from the remaining candidate resources based on determining that the number of remaining candidate resources in the resource selection window meets a threshold. Additionally or alternatively, this selection may involve selecting frequency resources from a subset of candidate resources based on determining that the number of remaining candidate resources in the resource selection window fails to meet a threshold, the subset including at least a first candidate resource among the one or more candidate resources, as described above. Figure 11 As described.

[0220] Further aspects of this disclosure include the following:

[0221] 1. A wireless communication method performed by a user equipment (UE), the method comprising:

[0222] Sensing is performed within the sidelink resource pool of the shared radio frequency band;

[0223] Based on this sensing, frequency resources of the sidelink resource pool are reserved within instances of variable time ranges;

[0224] Perform one or more Listen-Before-Speak (LBT) operations in the shared radio frequency band; and

[0225] Based on one or more LBTs, the frequency resources are used within the instance of the variable time range to transmit sidelink transmissions to the second UE.

[0226] 2. The method of Clause 1, wherein an instance of the variable time range spans one or more adjacent time slots.

[0227] 3. The method of Clause 1 or 2, wherein the frequency resource is in the same subchannel of the sidelink resource pool on the instance of the variable time range.

[0228] 4. The method as described in Clause 3, wherein the reservation includes:

[0229] The transmission includes the reservation of at least one of a subchannel index that identifies the frequency resource or a slot index that identifies the start slot of an instance of the variable time range.

[0230] 5. The method as described in any of Clauses 1-4, further comprising:

[0231] The variable time range is determined based on a predetermined value.

[0232] 6. The method as described in any of Clauses 1-4, further comprising:

[0233] An indication of the variable time range is received in at least one of the Radio Resource Control (RRC) configuration or the System Information Block (SIB).

[0234] 7. The method as described in any of Clauses 1-4, further comprising:

[0235] The variable time range is determined based on at least one of the packet delay budget (PDB) or traffic priority associated with the transmission on that side link.

[0236] 8. The method of any of the provisions 1-4 further includes: determining the variable time range based on the channel busy rate (CBR) associated with the sidelink resource pool.

[0237] 9. The method as described in any of Clauses 1-8, further comprising:

[0238] The physical (PHY) layer receives a sensing request, including an indication of the instance with a variable time range, and

[0239] The sensing is further based on the sensing request.

[0240] 10. The method as described in any of Clauses 1-9, further comprising:

[0241] At the Media Access Control (MAC) layer, candidate resources based on the sensed identifier are received;

[0242] The MAC layer identifies a subset of the candidate resources, the subset having a number of adjacent time slots greater than or equal to the number of adjacent time slots within the instance of the variable time range; and

[0243] The MAC layer reduces the number of adjacent time slots within the instance of the variable time range based on the fact that the number of candidate resources in the subset fails to meet the threshold.

[0244] The reservation includes reserving the frequency resources in a reduced number of adjacent time slots within the instance of the variable time range.

[0245] 11. The method as described in Clause 10, further comprising:

[0246] At this MAC layer, a sensing request is transmitted, including an indication of a threshold for the size of the candidate set of the resource selection window.

[0247] 12. The method of any one of clauses 1-11, wherein the instance of the variable time range comprises a set of time slots, the method further comprising:

[0248] It is determined that the first subset of this time slot set cannot be used to transmit on this side link.

[0249] The transmission of this side link includes:

[0250] The frequency resources are used to transmit the sidelink transmission within a second subset of the time slot set of the instance of the variable time range, wherein the second subset excludes the first subset.

[0251] 13. The method as described in any of Clauses 1-12, wherein:

[0252] Executing one or more LBTs includes:

[0253] The first LBT is performed in the shared radio frequency band based on the first time slot boundary of the instance of the variable time range; and

[0254] In response to the failure of the first LBT, a second LBT is performed based on a second time slot boundary following the first time slot boundary; and

[0255] The transmission includes: in response to the successful identification of the second LBT, transmitting the side link transmission starting from the second time slot boundary in the instance of the variable time range.

[0256] 14. The method as described in Clause 13, wherein:

[0257] Executing the first LBT includes:

[0258] Execute the countdown until the first time slot boundary; and

[0259] Executing the second LBT includes:

[0260] Resume the countdown.

[0261] 15. The method as described in any of Clauses 1-14, further comprising:

[0262] Detecting the reservation of second frequency resources of the link resource pool on that side from the third UE within the second instance of the variable time range; and

[0263] Based on this detection, the LBT gap within the second instance of the variable time range is set to zero.

[0264] 16. The method as described in any of Clauses 1-14, further comprising:

[0265] Detecting the reservation of second frequency resources of the link resource pool on that side from the third UE within the second instance of the variable time range; and

[0266] The time slots of the second instance of the variable time range and the time-frequency resources within the sub-channels of the second frequency resource are reserved based on the priority of the reservation or the reservation being used for at least one of the second instances of the variable time range.

[0267] 17. The method as described in any of Clauses 1-14, further comprising:

[0268] The system detects reservations of second frequency resources in the link resource pool on that side within the second instance of the variable time range from the third UE.

[0269] The reservation includes reserving a subchannel of the second frequency resource and the frequency resource within the instance of the variable time range based on the priority of the reservation or the reservation being used in at least one of the second instances of the variable time range, wherein the instance of the variable time range is configured to at least partially overlap with the second instance of the variable time range.

[0270] 18. The method of Clause 17, wherein the frequency resource is reserved further based on determining that there are no other frequency resources that overlap with a second instance of the variable time range.

[0271] 19. The method of any of Clauses 17 or 18, wherein an instance of the variable time range does not overlap with one or more time slots at the beginning of a second instance of the variable time range.

[0272] 20. The method as described in any of Clauses 1-14, further comprising:

[0273] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is in a different subchannel than the frequency resource.

[0274] 21. The method as described in any of Clauses 1-14, further comprising:

[0275] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range does not overlap with the instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0276] 22. The method as described in any of Clauses 1-14, further comprising:

[0277] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0278] 23. The method as described in any of Clauses 1-14, further comprising:

[0279] The second frequency resources of the sidelink resource pool within the second instance of the variable time range are reserved, wherein the second instance of the variable time range at least partially overlaps with or is adjacent to the instance of the variable time range.

[0280] in:

[0281] Transmitting this side link includes:

[0282] The sidelink transmission is transmitted during a first timeslot within an instance of the variable time range, based on a delay originating from the first LBT of the one or more LBTs, the first timeslot being adjacent to the start of a second instance of the variable time range; and

[0283] The method further includes:

[0284] Based on the first LBT, the second frequency resources are used to transmit the second sidelink transmission to the third UE during the second time slot at the beginning of the second instance within the variable time range.

[0285] 24. The method as described in any of Clauses 1-14, further comprising:

[0286] The transmission provides a soft reservation of the second frequency resources for the second instance within a variable time range for the side link resource pool.

[0287] 25. The method of Clause 24, wherein transmitting the soft reservation includes:

[0288] The transmission includes the sidelink transmission of the first transmission block.

[0289] The soft reservation is associated with a second transport block that is different from the first transport block.

[0290] 26. The method of Clause 25 further includes at least one of the following:

[0291] In response to determining that the soft reservation has not been preempted, a second sidelink transmission including a second transport block is transmitted to a third UE using the second frequency resources within the second instance of the variable time range; or

[0292] In response to determining that the soft reservation is preempted, the use of the second frequency resources to transmit a second sidelink transmission including a second transport block is suppressed within the second instance of the variable time range.

[0293] 27. The method as described in any of Clauses 1-14, further comprising:

[0294] Based on this sensing, candidate resources in the sidelink resource pool are identified within the resource selection window;

[0295] The third UE receives a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of the variable time range, the soft reservation being associated with one or more of the candidate resources.

[0296] Based on this soft reservation, one or more of the candidate resources are determined to be unavailable; and

[0297] The frequency resource is selected from the candidate resources based on the remaining number of candidate resources, wherein the selection includes at least one of the following:

[0298] Frequency resources within the instance of the variable time range are selected from the remaining candidate resources based on whether the number of remaining candidate resources in the resource selection window meets a threshold; or

[0299] The frequency resource is selected from a subset of candidate resources based on the determination that the number of remaining candidate resources in the resource selection window fails to meet the threshold, the subset including at least a first candidate resource among one or more of the candidate resources.

[0300] 28. A first user equipment (UE), comprising:

[0301] The processor is configured to:

[0302] Sensing is performed within the sidelink resource pool of the shared radio frequency band;

[0303] Based on this sensing, frequency resources of the sidelink resource pool are reserved within instances over variable time ranges; and

[0304] Perform one or more Listen-Before-Speak (LBT) operations in the shared radio frequency band; and

[0305] The transceiver is configured to:

[0306] Based on one or more LBTs, the frequency resources are used within the instance of the variable time range to transmit sidelink transmissions to the second UE.

[0307] 29. As in the first UE of Clause 28, wherein an instance of the variable time range spans one or more adjacent time slots.

[0308] 30. The first UE as in any of Clauses 28 or 29, wherein the frequency resource is in the same subchannel of the sidelink resource pool on the instance of the variable time range.

[0309] 31. As in the first UE of Clause 30, wherein the processor configured to reserve the frequency resources is further configured to:

[0310] The transceiver is configured to transmit a reservation including at least one of a subchannel index identifying the frequency resource or a slot index identifying the start slot of an instance of the variable time range.

[0311] 32. The first UE as described in Clause 28, wherein the processor is further configured to:

[0312] The variable time range is determined based on a predetermined value.

[0313] 33. The first UE as described in any of Clauses 28-32, wherein the transceiver is further configured to:

[0314] An indication of the variable time range is received in at least one of the Radio Resource Control (RRC) configuration or the System Information Block (SIB).

[0315] 34. The first UE as described in any of Clauses 28-32, wherein the processor is further configured to:

[0316] The variable time range is determined based on at least one of the packet delay budget (PDB) or traffic priority associated with the transmission on that side link.

[0317] 35. The first UE as described in any of Clauses 28-32, wherein the processor is further configured to:

[0318] The variable time range is determined based on the Channel Busy Rate (CBR) associated with the sidelink resource pool.

[0319] 36. The first UE as described in any of Clauses 28-35, wherein the processor is further configured to:

[0320] The physical (PHY) layer receives a sensing request, including an indication of the instance with a variable time range, and

[0321] The processor is configured to further perform sensing in the sidelink resource pool based on the sensing request.

[0322] 37. The first UE as described in any of Clauses 28-36, wherein the processor is further configured to:

[0323] At the Media Access Control (MAC) layer, candidate resources based on the sensed identifier are received;

[0324] The MAC layer identifies a subset of candidate resources, which has a number of adjacent time slots greater than or equal to the number of adjacent time slots within the instance of the variable time range; and

[0325] The MAC layer reduces the number of adjacent time slots within the instance of the variable time range based on the fact that the number of candidate resources in the subset fails to meet the threshold.

[0326] The processor configured to reserve the frequency resources is further configured to reserve the frequency resources in a reduced number of adjacent time slots within the instance of the variable time range.

[0327] 38. The first UE as described in Clause 37, wherein the processor is further configured to:

[0328] At this MAC layer, a sensing request is transmitted, including an indication of a threshold for the size of the candidate set of the resource selection window.

[0329] 39. The first UE as described in any of clauses 28-38, wherein the instance of the variable time range comprises a set of time slots, and wherein:

[0330] The processor is further configured to:

[0331] It is determined that the first subset of the time slot set cannot be used to transmit on this side link; and

[0332] The transceiver was further configured to:

[0333] The frequency resources are used to transmit the sidelink transmission within a second subset of the time slot set of the instance of the variable time range, wherein the second subset excludes the first subset.

[0334] 40. The first UE as specified in any of Clauses 28-39, wherein:

[0335] The processor is further configured to:

[0336] The first LBT of the one or more LBTs is executed within the shared radio frequency band based on the first time slot boundary of the instance of the variable time range; and

[0337] In response to the failure of the first LBT, a second LBT is performed based on a second time slot boundary following the first time slot boundary; and

[0338] The transceiver is further configured to perform the following operations in response to the processor identifying the success of the second LBT:

[0339] In this variable time range instance, the side link transmission begins from the second time slot boundary.

[0340] 41. The first UE as described in Clause 40, wherein the processor is further configured to:

[0341] The countdown continues until the first time slot boundary before the first LBT is executed; and

[0342] Resume the countdown to execute the second LBT.

[0343] 42. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0344] Detecting the reservation of second frequency resources of the link resource pool on that side from the third UE within the second instance of the variable time range; and

[0345] Based on this detection, the LBT gap within the second instance of the variable time range is set to zero.

[0346] 43. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0347] Detecting the reservation of second frequency resources of the link resource pool on that side from the third UE within the second instance of the variable time range; and

[0348] The time-frequency resources within the sub-channels of the second instance of the variable time range are reserved based on the priority of the reservation or the reservation being used for at least one of the second instances of the variable time range.

[0349] 44. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0350] The system detects reservations of second frequency resources in the link resource pool on that side within the second instance of the variable time range from the third UE.

[0351] The processor is configured to reserve a subchannel of the second frequency resource and the frequency resources within the instance of the variable time range based on the priority of the reservation or the reservation being used for at least one of the second instances of the variable time range, wherein the instance of the variable time range is configured to at least partially overlap with the second instance of the variable time range.

[0352] 45. The first UE as described in Clause 44, wherein the processor is configured to further reserve the frequency resource based on determining that there are no other frequency resource reservations that overlap between the corresponding instance of the variable time range and the second instance of the variable time range.

[0353] 46. ​​The first UE as in any of Clauses 44 or 45, wherein an instance of the variable time range does not overlap with one or more time slots at the beginning of a second instance of the variable time range.

[0354] 47. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0355] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is in a different subchannel than the frequency resource.

[0356] 48. The first UE as described in any of clauses 28-41, wherein the processor is further configured to:

[0357] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range does not overlap with the instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0358] 49. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0359] The second frequency resource of the sidelink resource pool is reserved in the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0360] 50. The first UE as specified in any of Clauses 28-41, wherein:

[0361] The processor is further configured to:

[0362] The second frequency resources of the sidelink resource pool within the second instance of the variable time range are reserved, wherein the second instance of the variable time range at least partially overlaps with or is adjacent to the instance of the variable time range; and

[0363] The transceiver was further configured to:

[0364] The sidelink transmission is transmitted during a first time slot within an instance of the variable time range, based on a delay originating from the first LBT of the one or more LBTs, the first time slot being adjacent to the start of a second instance of the variable time range; and

[0365] Based on the first LBT, the second frequency resources are used to transmit the second sidelink transmission to the third UE during the second time slot at the beginning of the second instance within the variable time range.

[0366] 51. The first UE as described in any of Clauses 28-41, wherein the transceiver is further configured to:

[0367] The transmission makes a soft reservation of the second frequency resources for the second instance within the variable time range for the side link resource pool.

[0368] 52. The first UE as described in Clause 51, wherein the transceiver is further configured to:

[0369] The transmission includes the sidelink transmission of the first transmission block, and

[0370] The soft reservation is associated with a second transport block that is different from the first transport block.

[0371] 53. As in the first UE of Clause 52, the transceiver is further configured to:

[0372] In response to the processor determining that the soft reservation has not been preempted, it uses the second frequency resources to transmit a second sidelink transmission, including the second transport block, to the third UE within the second instance of the variable time range; or

[0373] In response to the processor determining that the soft reservation is preempted, the use of the second frequency resources to transmit a second sidelink transmission including a second transport block is suppressed within the second instance of the variable time range.

[0374] 54. The first UE as described in any of Clauses 28-41, wherein the processor is further configured to:

[0375] Based on this sensing, candidate resources in the sidelink resource pool are identified within the resource selection window;

[0376] The third UE receives a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of the variable time range, the soft reservation being associated with one or more of the candidate resources.

[0377] Based on this soft reservation, one or more of the candidate resources are determined to be unavailable; and

[0378] The frequency resource is selected from the candidate resources based on the remaining number of candidate resources, wherein the selection includes at least one of the following:

[0379] Frequency resources within the instance of the variable time range are selected from the remaining candidate resources based on whether the number of remaining candidate resources in the resource selection window meets a threshold; or

[0380] The frequency resource is selected from a subset of candidate resources based on the determination that the number of remaining candidate resources in the resource selection window fails to meet the threshold, the subset of candidate resources including at least a first candidate resource among one or more of the candidate resources.

[0381] 55. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

[0382] Code used to enable the first user equipment (UE) to perform sensing within the sidelink resource pool in the shared radio frequency band:

[0383] Code used to enable the first UE to reserve frequency resources of the sidelink resource pool within an instance of a variable time range based on the sensing;

[0384] Code used to enable the first UE to execute one or more Listen-Before-Speak (LBT) codes in the shared radio frequency band; and

[0385] Code used to enable a first UE to transmit sidelink transmissions to a second UE using the frequency resources within the instance of the variable time range based on one or more LBTs.

[0386] 56. A non-transient computer-readable medium as described in Clause 55, wherein an instance of the variable time range spans one or more adjacent time slots.

[0387] 57. A non-transient computer-readable medium as in any of clauses 55 or 56, wherein the frequency resource is in the same subchannel of the sidelink resource pool on the instance of the variable time range.

[0388] 58. A non-transient computer-readable medium as described in Clause 57, wherein the code for causing a first UE to reserve the frequency resource is further configured to cause the first UE to:

[0389] The transmission includes the reservation of at least one of a subchannel index that identifies the frequency resource or a slot index that identifies the start slot of an instance of the variable time range.

[0390] 59. A non-transient computer-readable medium as described in any of clauses 55-58, further comprising:

[0391] Code used to enable the first UE to determine the variable time range based on a predetermined value.

[0392] 60. A non-transient computer-readable medium as described in any of clauses 55-58, further comprising:

[0393] Code used to enable the first UE to receive an indication of the variable time range in at least one of the Radio Resource Control (RRC) configuration or the System Information Block (SIB).

[0394] 61. A non-transient computer-readable medium as described in any of clauses 55-58, further comprising:

[0395] Code used to enable the first UE to determine the variable time range based on at least one of the packet delay budget (PDB) or traffic priority associated with the sidelink transmission.

[0396] 62. A non-transient computer-readable medium as described in any of clauses 55-58, further comprising:

[0397] Code used to enable the first UE to determine the variable time range based on the Channel Busy Rate (CBR) associated with the sidelink resource pool.

[0398] 63. A non-transient computer-readable medium as described in any of clauses 55-62, further comprising:

[0399] Code used to enable the first UE to receive a sensing request from the physical (PHY) layer, including an indication of the instance of the variable time range, and

[0400] The code used to enable the first UE to perform sensing is further configured to enable the first UE to perform sensing based on the sensing request.

[0401] 64. A non-transient computer-readable medium as described in any of clauses 55-63, further comprising:

[0402] Code used to enable the first UE to receive candidate resources based on the sensed identifier at the Media Access Control (MAC) layer;

[0403] Code used to enable the first UE to identify a candidate resource subset by the MAC layer, the candidate resource subset having a number of adjacent time slots greater than or equal to the number of adjacent time slots within the instance of the variable time range; and

[0404] Code used to reduce the number of adjacent time slots within the instance of the variable time range by the MAC layer based on the failure of the number of candidate resources in the subset to meet the threshold.

[0405] The code used to enable the first UE to reserve the frequency resource is further configured to enable the first UE to reserve the frequency resource in a reduced number of adjacent time slots within the instance of the variable time range.

[0406] 65. The non-transient computer-readable medium of Clause 64 further includes:

[0407] Code used to enable the first UE to transmit a sensing request at the MAC layer, including an indication of a threshold for the size of the candidate set of the resource selection window.

[0408] 66. A non-transient computer-readable medium as described in any of clauses 55-65, wherein an instance of the variable time range includes a set of time slots, the program code further comprising:

[0409] Code used to enable the first UE to determine that a first subset of the time slot set is not available for transmitting the sidelink transmission.

[0410] The code used to enable the first UE to transmit the side link transmission includes:

[0411] Code for enabling a first UE to use the frequency resources to transmit the sidelink transmission within a second subset of the time slot set of the instance of the variable time range, wherein the second subset excludes the first subset.

[0412] 67. A non-transient computer-readable medium as described in any of clauses 55-66, further comprising:

[0413] Code for enabling a first UE to execute the code of the first LBT in one or more LBTs based on the first time slot boundary in an instance of the variable time range within the shared radio frequency band; and

[0414] Code for causing a first UE to execute a second LBT in one or more LBTs based on a second time slot boundary following a first time slot boundary in response to identifying a failure of the first LBT; and

[0415] The code used to enable the first UE to transmit the sidelink transmission is further configured to enable the first UE to transmit the sidelink transmission from the second time slot boundary in the instance of the variable time range in response to the successful identification of the second LBT.

[0416] 68. A non-transient computer-readable medium as described in Clause 67, wherein:

[0417] The code used to cause the first UE to execute the first LBT is further configured to cause the first UE to execute a countdown until the first time slot boundary; and

[0418] The code used to cause the first UE to execute the second LBT is further configured to cause the first UE to resume the countdown.

[0419] 69. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0420] Code used to enable the first UE to detect the reservation of the second frequency resource of the link resource pool on that side within the second instance of the variable time range from the third UE; and

[0421] Code used to enable the first UE to set the LBT gap within the second instance of the variable time range to zero based on the detection.

[0422] 70. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0423] Code used to enable the first UE to detect the reservation of the second frequency resource of the link resource pool on that side within the second instance of the variable time range from the third UE; and

[0424] Code for enabling a first UE to reserve time-frequency resources in a time slot and a subchannel of a second instance of a variable time range based on the priority of the reservation or the reservation being used for at least one of the second instances of the variable time range.

[0425] 71. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0426] Code used to enable the first UE to detect the reservation of the second frequency resource of the link resource pool on that side within the second instance of the variable time range from the third UE.

[0427] The code for enabling the first UE to reserve the frequency resource is further configured to enable the first UE to reserve the sub-channel of the second frequency resource and the frequency resource within the instance of the variable time range based on the priority of the reservation or the reservation being used in at least one of the second instances of the variable time range, wherein the instance of the variable time range is configured to at least partially overlap with the second instance of the variable time range.

[0428] 72. A non-transient computer-readable medium as described in Clause 71, wherein the code for enabling a first UE to reserve the frequency resource is further configured to enable the first UE to reserve the frequency resource based on determining that there are no other frequency resource reservations overlapping between a corresponding instance of the variable time range and a second instance of the variable time range.

[0429] 73. A non-transient computer-readable medium as described in any of Clauses 71 or 72, wherein an instance of the variable time range does not overlap with one or more time slots at the beginning of a second instance of the variable time range.

[0430] 74. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0431] Code for enabling a first UE to reserve a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with an instance of the variable time range, and wherein the second frequency resource is in a different subchannel than the frequency resource.

[0432] 75. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0433] Code for enabling a first UE to reserve a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range does not overlap with an instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0434] 76. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0435] Code for enabling a first UE to reserve a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with an instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0436] 77. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0437] Code for enabling a first UE to reserve a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with or is adjacent to an instance of the variable time range.

[0438] in:

[0439] The code used to enable the first UE to transmit this sidelink transmission is further configured to enable the first UE to:

[0440] The sidelink transmission is transmitted during a first time slot within an instance of the variable time range, based on a delay originating from the first LBT of the one or more LBTs, the first time slot being adjacent to the start of a second instance of the variable time range; and

[0441] The non-transient computer-readable storage medium further includes:

[0442] Code for enabling a first UE to transmit a second sidelink transmission to a third UE using second frequency resources during a second time slot at the beginning of a second instance within the variable time range, based on a first LBT.

[0443] 78. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0444] Code used to enable the first UE to transmit a soft reservation of a second frequency resource for a second instance of the sidelink resource pool within a variable time range.

[0445] 79. A non-transient computer-readable medium as described in Clause 78, wherein the code for causing the first UE to transmit the soft reservation is further configured to cause the first UE to:

[0446] The transmission includes the sidelink transmission of the first transmission block.

[0447] The soft reservation is associated with a second transport block that is different from the first transport block.

[0448] 80. A non-transient computer-readable medium as described in Clause 79 further includes at least one of the following:

[0449] Code used to cause the first UE to transmit a second sidelink transmission, including a second transport block, to the third UE within a second instance of the variable time range, using the second frequency resources, in response to determining that the soft reservation has not been preempted; or

[0450] Code for causing the first UE to suppress the use of the second frequency resources to transmit second sidelink transmissions, including the second transport block, within the second instance of the variable time range in response to determining that the soft reservation is preempted.

[0451] 81. A non-transient computer-readable medium as described in any of clauses 55-68, further comprising:

[0452] Code used to enable the first UE to identify candidate resources in the sidelink resource pool within the resource selection window based on the sensing;

[0453] Code for enabling a first UE to receive from a third UE a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of the variable time range, the soft reservation being associated with one or more of the candidate resources;

[0454] Code used to cause the first UE to determine one or more of the candidate resources as unavailable based on the soft reservation; and

[0455] Code for enabling the first UE to select the frequency resource from the candidate resources based on the remaining number of candidate resources, wherein the code for enabling the first UE to make a selection is further configured to enable the first UE to:

[0456] Frequency resources within the instance of the variable time range are selected from the remaining candidate resources based on whether the number of remaining candidate resources in the resource selection window meets a threshold; or

[0457] The frequency resource is selected from a subset of candidate resources based on the determination that the number of remaining candidate resources in the resource selection window fails to meet the threshold, the subset of candidate resources including at least a first candidate resource among one or more of the candidate resources.

[0458] 82. A first user equipment (UE), comprising:

[0459] Device for sensing within a sidelink resource pool in a shared radio frequency band;

[0460] A means for reserving frequency resources of the sidelink resource pool within an instance of a variable time range based on the sensing;

[0461] A means for performing one or more Listen-Before-Speak (LBT) operations in the shared radio frequency band; and

[0462] A means for using frequency resources to transmit sidelink transmissions to a second UE within an instance of the variable time range based on one or more LBTs.

[0463] 83. The first UE as in Clause 82, wherein an instance of the variable time range spans one or more adjacent time slots.

[0464] 84. The first UE as in any of clauses 82 or 83, wherein the frequency resource is in the same subchannel of the sidelink resource pool on the instance of the variable time range.

[0465] 85. As in the first UE of Clause 84, wherein the means for reserving the frequency resource is further configured to:

[0466] The transmission includes the reservation of at least one of a subchannel index that identifies the frequency resource or a slot index that identifies the start slot of an instance of the variable time range.

[0467] 86. The first UE as described in any of clauses 82-85 further includes:

[0468] A device for determining the variable time range based on a predetermined value.

[0469] 87. The first UE as described in any of clauses 82-85 further includes:

[0470] A means for receiving an indication of the variable time range in at least one of a Radio Resource Control (RRC) configuration or a System Information Block (SIB).

[0471] 88. The first UE as described in any of clauses 82-85 further includes:

[0472] A means for determining the variable time range based on at least one of the packet delay budget (PDB) or traffic priority associated with the side link transmission.

[0473] 89. The first UE as described in any of clauses 82-85 further includes:

[0474] A means for determining the variable time range based on the Channel Busy Rate (CBR) associated with the sidelink resource pool.

[0475] 90. The first UE as described in any of clauses 82-89 further includes:

[0476] A means for receiving, by the physical (PHY) layer, a sensing request including an indication of an instance of a variable time range, and

[0477] The device used for sensing in the side link resource pool is further configured to perform sensing based on the sensing request.

[0478] 91. The first UE as described in any of clauses 82-90 further includes:

[0479] A means for receiving candidate resources based on the sensed identifier at the Media Access Control (MAC) layer;

[0480] A means for identifying a subset of candidate resources by the MAC layer, the subset of candidate resources having a number of adjacent time slots greater than or equal to the number of adjacent time slots within the instance of the variable time range; and

[0481] A means for reducing the number of adjacent time slots within an instance of a variable time range by the MAC layer based on the fact that the number of candidate resources in the subset fails to meet a threshold.

[0482] The means for reserving the frequency resources is further configured to reserve frequency resources in a reduced number of adjacent time slots within an instance of the variable time range.

[0483] 92. As in the first UE of Clause 91, further comprising:

[0484] A means for transmitting a sensing request at the MAC layer, including an indication of a threshold for the size of the candidate set of the resource selection window.

[0485] 93. The first UE as described in any of clauses 82-92, wherein an instance of the variable time range comprises a set of time slots, the first UE further comprising:

[0486] A means for determining that a first subset of the time slot set is unusable for transmitting the side link.

[0487] The device used to transmit the data via this side link is further configured as follows:

[0488] The frequency resources are used to transmit the sidelink transmission within a second subset of the time slot set of the instance of the variable time range, wherein the second subset excludes the first subset.

[0489] 94. The first UE as in any of clauses 82-93, wherein:

[0490] The means for performing the one or more LBTs further includes:

[0491] A means for performing a first LBT based on a first time slot boundary in an instance of the variable time range within the shared radio frequency band; and

[0492] A means for performing a second LBT based on a second time slot boundary following a first time slot boundary in response to an indication of a failure of the first LBT; and

[0493] The means for transmission is further configured to transmit the side link transmission from the second time slot boundary in the instance of the variable time range in response to the successful identification of the second LBT.

[0494] 95. As in the first UE of Clause 94, where:

[0495] The means for performing the first LBT is further configured to perform a countdown until the first time slot boundary; and

[0496] The device used to perform the second LBT is further configured to resume the countdown.

[0497] 96. The first UE as described in any of clauses 82-95 further includes:

[0498] A means for detecting the reservation of second frequency resources of the link resource pool on that side within the second instance of the variable time range from a third UE; and

[0499] A means for setting the LBT gap within a second instance of the variable time range to zero based on the detection.

[0500] 97. The first UE as described in any of clauses 82-95 further includes:

[0501] A means for detecting the reservation of second frequency resources of the link resource pool on that side within the second instance of the variable time range from a third UE; and

[0502] A means for reserving time-frequency resources in a time slot and a subchannel of a second instance of a variable time range based on the priority of the reservation or the reservation being used for at least one of the second instances of the variable time range.

[0503] 98. The first UE as described in any of clauses 82-95 further includes:

[0504] A means for detecting the reservation of a second frequency resource in the link resource pool on that side within a second instance of the variable time range from a third UE.

[0505] The means for reserving the frequency resource is further configured to reserve the sub-channel of the second frequency resource and the frequency resource within the instance of the variable time range based on the priority of the reservation or the reservation being used in at least one of the second instances of the variable time range, wherein the instance of the variable time range is configured to at least partially overlap with the second instance of the variable time range.

[0506] 99. The first UE as described in Clause 98, wherein the means for reserving the frequency resource is further configured to further reserve the frequency resource based on determining that there is no other frequency resource reservation overlapping between the corresponding instance of the variable time range and the second instance of the variable time range.

[0507] 100. The first UE as in any of Clauses 98 or 99, wherein an instance of the variable time range does not overlap with one or more time slots at the beginning of a second instance of the variable time range.

[0508] 101. The first UE as described in any of clauses 82-95 further includes:

[0509] A means for reserving a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with an instance of the variable time range, and wherein the second frequency resource is in a subchannel different from the frequency resource.

[0510] 102. The first UE as described in any of clauses 82-95 further includes:

[0511] A means for reserving a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range does not overlap with an instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0512] 103. The first UE as described in any of clauses 82-95 further includes:

[0513] A means for reserving a second frequency resource of the sidelink resource pool within a second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with an instance of the variable time range, and wherein the second frequency resource is in the same subchannel as the frequency resource.

[0514] 104. The first UE as described in any of clauses 82-95 further includes:

[0515] A means for reserving the second frequency resources of the sidelink resource pool within the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with or is adjacent to the instance of the variable time range.

[0516] in:

[0517] The device used to transmit the data via this side link is further configured to:

[0518] The sidelink transmission is transmitted based on a delay originating from the first LBT of one or more LBTs during a first timeslot within an instance of the variable time range, the first timeslot being adjacent to the start of a second instance of the variable time range; and

[0519] The first UE further includes:

[0520] A means for transmitting a second sidelink transmission to a third UE using a second frequency resource during a second time slot at the beginning of a second instance within the variable time range, based on a first LBT.

[0521] 105. The first UE as described in any of clauses 82-95 further includes:

[0522] A means for transmitting a soft reservation of a second frequency resource for a second instance within a variable time range for the sidelink resource pool.

[0523] 106. As in the first UE of Clause 105, wherein the means for transmitting the soft reservation is further configured to:

[0524] The transmission includes the sidelink transmission of the first transmission block.

[0525] The soft reservation is associated with a second transport block that is different from the first transport block.

[0526] 107. As in the first UE of Clause 106, it further includes at least one of the following:

[0527] Means for transmitting a second sidelink transmission, including a second transport block, to a third UE within a second instance of the variable time range using second frequency resources in response to determining that the soft reservation has not been preempted; or

[0528] A means for suppressing the use of a second frequency resource to transmit a second sidelink transmission including a second transport block within a second instance of the variable time range in response to determining that the soft reservation is preempted.

[0529] 108. The first UE as described in any of clauses 82-95 further includes:

[0530] A means for identifying candidate resources in the sidelink resource pool within a resource selection window based on the sensing;

[0531] Means for receiving from a third UE a soft reservation of a second frequency resource for the sidelink resource pool within a second instance of the variable time range, the soft reservation being associated with one or more of the candidate resources;

[0532] Means for determining one or more of the candidate resources as unavailable based on the soft reservation; and

[0533] A means for selecting a frequency resource from candidate resources based on the number of remaining candidate resources, wherein the means for selecting the frequency resource is further configured to:

[0534] Frequency resources within the instance of the variable time range are selected from the remaining candidate resources based on whether the number of remaining candidate resources in the resource selection window meets a threshold; or

[0535] The frequency resource is selected from a subset of candidate resources based on the determination that the number of remaining candidate resources in the resource selection window fails to meet the threshold, the subset of candidate resources including at least a first candidate resource among one or more of the candidate resources.

[0536] Information and signals can be represented using any of a wide variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0537] The various illustrative blocks and modules described herein can be implemented or executed using a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternatives, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration).

[0538] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Other examples and implementations fall within the scope of this disclosure and the appended claims. For example, due to the nature of software, the above-described functions may be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented at different physical locations. Additionally, as used herein (including in the claims), the use of "or" in an enumeration of items (e.g., an enumeration of items accompanied by phrases such as "at least one of" or "one or more of") indicates an inclusive enumeration, such that an enumeration such as [at least one of A, B, or C] means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0539] As will be appreciated by those skilled in the art by this time, and depending on the specific application at hand, many modifications, substitutions, and variations can be made to the materials, apparatus, configuration, and methods of use of the devices disclosed herein without departing from the spirit and scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the specific embodiments explained and described herein (as they are merely examples), but should be fully equivalent to the appended claims and their functional equivalents.

Claims

1. A method of wireless communication performed by a user equipment (UE), the method comprising: sensing in a sidelink resource pool within a shared radio frequency band; reserving, based on the sensing, frequency resources of the sidelink resource pool for an instance of a variable time range; transmitting a soft reservation for second frequency resources of the sidelink resource pool for a second instance of the variable time range; performing one or more listen before talk (LBTs) in the shared radio frequency band; and transmitting, based on the one or more LBTs, a sidelink transmission to a second UE using the frequency resources for the instance of the variable time range.

2. The method of claim 1, wherein the instance of the variable time range spans one or more contiguous slots.

3. The method of claim 1, wherein the frequency resources are in a same subchannel of the sidelink resource pool over the instance of the variable time range.

4. The method of claim 3, wherein the reserving comprises: transmitting a reservation comprising at least one of a subchannel index identifying the frequency resources or a time slot index identifying a starting slot of the instance of the variable time range.

5. The method of claim 1, further comprising: determining the variable time range based on a predetermined value.

6. The method of claim 1, further comprising: receiving an indication of the variable time range in at least one of a radio resource control (RRC) configuration or a system information block (SIB).

7. The method of claim 1, further comprising: determining the variable time range based on at least one of a packet delay budget (PDB) or a traffic priority associated with the sidelink transmission.

8. The method of claim 1, further comprising: determining the variable time range based on a channel busy ratio (CBR) associated with the sidelink resource pool.

9. The method of claim 1, further comprising: receiving, by a physical (PHY) layer, a sensing request comprising an indication of the instance of the variable time range, and wherein the sensing is further based on the sensing request.

10. The method of claim 1, further comprising: receiving, at a medium access control (MAC) layer, candidate resources identified based on the sensing; identifying, by the MAC layer, a subset of the candidate resources having a number of contiguous slots greater than or equal to a number of contiguous slots within the instance of the variable time range; and reducing, by the MAC layer, the number of contiguous slots within the instance of the variable time range based on a number of candidate resources in the subset failing to satisfy a threshold, wherein the reserving comprises reserving the frequency resources within the reduced number of contiguous slots for the instance of the variable time range.

11. The method of claim 10, further comprising: transmitting, at the MAC layer, a sensing request comprising an indication of a candidate set size threshold for a resource selection window.

12. The method of claim 1, wherein the instance of the variable time range comprises a set of slots, the method further comprising: determining that a first subset of the set of slots is unavailable for transmitting the sidelink transmission, ​ wherein transmitting the sidelink transmission comprises: transmitting the sidelink transmission using the frequency resources within a second subset of the set of slots of the instance of the variable time range, wherein the second subset excludes the first subset.

13. The method of claim 1, wherein: performing the one or more LBTs comprises: performing a first LBT based on a first slot boundary in the instance of the variable time range in the shared radio frequency band; and performing a second LBT based on a second slot boundary after the first slot boundary in response to identifying a failure of the first LBT; and the transmitting comprises transmitting the sidelink transmission starting from the second slot boundary in the instance of the variable time range in response to identifying a success of the second LBT.

14. The method of claim 13, wherein: performing the first LBT comprises: performing a countdown until the first slot boundary; and performing the second LBT comprises: resuming the countdown.

15. The method of claim 1, further comprising: detecting a reservation of the second frequency resource of the sidelink resource pool within the second instance of the variable time range from a third UE; and setting an LBT gap within a second instance of the variable time range to zero based on the detecting.

16. The method of claim 1, further comprising: detecting a reservation of the second frequency resource of the sidelink resource pool within the second instance of the variable time range from a third UE; and reserving time-frequency resources within a slot of a second instance of the variable time range and a subchannel of the second frequency resource based on at least one of a priority of the reservation or the reservation being for the second instance of the variable time range.

17. The method of claim 1, further comprising: detecting a reservation of the second frequency resource of the sidelink resource pool within the second instance of the variable time range from a third UE, wherein the reservation comprises reserving a subchannel of the second frequency resource and the frequency resource within the instance of the variable time range based on at least one of a priority of the reservation or the reservation being for the second instance of the variable time range, wherein the instance of the variable time range is configured to at least partially overlap with the second instance of the variable time range.

18. The method of claim 17, wherein reserving the frequency resource is further based on determining an absence of other frequency resource reservations of the respective instance of the variable time range overlapping with the second instance of the variable time range.

19. The method of claim 17, wherein the instance of the variable time range does not overlap with one or more slots at a beginning of the second instance of the variable time range.

20. The method of claim 1, further comprising: reserving the second frequency resource of the sidelink resource pool within the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is within a different subchannel than the frequency resource.

21. The method of claim 1, further comprising: reserving the second frequency resource of the sidelink resource pool within the second instance of the variable time range, wherein the second instance of the variable time range does not overlap with the instance of the variable time range, and wherein the second frequency resource is within a same subchannel as the frequency resource.

22. The method of claim 1, further comprising: reserving the second frequency resource of the sidelink resource pool within the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps with the instance of the variable time range, and wherein the second frequency resource is within a same subchannel as the frequency resource.

23. The method of claim 1, further comprising: reserving the second frequency resource of the sidelink resource pool within the second instance of the variable time range, wherein the second instance of the variable time range at least partially overlaps or is adjacent to the instance of the variable time range, wherein: transmitting the sidelink transmission includes: transmitting the sidelink transmission during a first time slot within the instance of the variable time range based on a deferral from a first LBT of the one or more LBTs, the first time slot being adjacent to a start of the second instance of the variable time range; and the method further includes: transmitting, based on the first LBT, a second sidelink transmission to a third UE during a second time slot at the start of the second instance of the variable time range using the second frequency resource.

24. The method of claim 1, wherein transmitting the soft reservation includes: transmitting the sidelink transmission including a first transport block, wherein the soft reservation is associated with a second transport block that is different than the first transport block.

25. The method of claim 24, further comprising at least one of: transmitting, to a third UE, a second sidelink transmission including the second transport block within the second instance of the variable time range using the second frequency resource in response to determining that the soft reservation is not preempted; or refraining from transmitting the second sidelink transmission including the second transport block within the second instance of the variable time range using the second frequency resource in response to determining that the soft reservation is preempted.

26. The method of claim 1, further comprising: identifying, based on the sensing, candidate resources of the sidelink resource pool within a resource selection window; receiving, from a third UE, a soft reservation for the second frequency resource of the sidelink resource pool within the second instance of the variable time range, the soft reservation being associated with one or more of the candidate resources; determining, based on the soft reservation, the one or more of the candidate resources as unavailable; and selecting the frequency resource from the candidate resources based on a number of remaining candidate resources, wherein the selecting comprises at least one of: selecting the frequency resource from remaining candidate resources based on a determination that a number of remaining candidate resources in the resource selection window satisfies a threshold; or selecting the frequency resource from a subset of the candidate resources based on a determination that a number of remaining candidate resources in the resource selection window fails to satisfy the threshold, the subset of the candidate resources comprising at least a first candidate resource of the one or more of the candidate resources.

27. A first user equipment (UE), comprising: a memory; a transceiver; and at least one processor coupled to the memory and the transceiver, wherein the first UE is configured to: sense in a sidelink resource pool within a shared radio frequency band; reserve, based on the sensing, a frequency resource of the sidelink resource pool within an instance of a variable time range; transmit a soft reservation for a second frequency resource of the sidelink resource pool within a second instance of the variable time range; perform one or more listen before talk (LBTs) in the shared radio frequency band; and transmit, based on the one or more LBTs, a sidelink transmission to a second UE using the frequency resource within the instance of the variable time range.

28. The first UE of claim 27, wherein the first UE is further configured to perform the method of any one of claims 2-26.

29. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising: code for causing a first user equipment (UE) to sense in a sidelink resource pool within a shared radio frequency band: code for causing the first UE to reserve, based on the sensing, a frequency resource of the sidelink resource pool within an instance of a variable time range; code for causing the first UE to transmit a soft reservation for a second frequency resource of the sidelink resource pool within a second instance of the variable time range; code for causing the first UE to perform one or more listen before talk (LBTs) in the shared radio frequency band; and code for causing the first UE to transmit, based on the one or more LBTs, a sidelink transmission to a second UE using the frequency resource within the instance of the variable time range.

30. A first user equipment (UE), comprising: means for sensing in a sidelink resource pool within a shared radio frequency band; means for reserving, based on the sensing, a frequency resource of the sidelink resource pool within an instance of a variable time range; means for transmitting a soft reservation for a second frequency resource of the sidelink resource pool within a second instance of the variable time range; means for performing one or more listen before talk (LBTs) in the shared radio frequency band; and means for transmitting, based on the one or more LBTs, a sidelink transmission to a second UE using the frequency resource within the instance of the variable time range. ​ ​ 31. The first UE of claim 30, further comprising means for performing the method of any one of claims 2-26.

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