System and method for resuming transmission in sidelink shared channel occupancy time

Abstract

Wireless communication systems and methods related to channel occupancy time (COT) sharing information (COT-SI) reservation for a COT for sidelink communication in an unlicensed frequency band are provided. In some aspects, a user equipment (UE) performs a channel access procedure to acquire one or more COTs in a sidelink channel on an unlicensed new radio (NR) band. Further, the UE transmits COT sharing information (COT-SI), which is configured to reserve one or more COTs for future transmission via a sidelink channel.

Description

Technical Field

[0001] This application relates to wireless communication systems, and more specifically to systems and methods for resuming transmission during side-link (SL) shared channel occupancy time (COT).

[0002] introduction 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 multiple base stations (BSs), each of which simultaneously supports communication with multiple communication devices, which may also be referred to as user equipment (UEs).

[0003] 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 higher reliability compared to LTE. NR is designed to operate across a wide spectrum band array, for example, 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 spectrum and shared spectrum. Spectrum sharing allows operators the opportunity to aggregate spectrum to dynamically support high-bandwidth services. Spectrum sharing extends the benefits of NR technology to operational entities that may not have access to licensed spectrum.

[0004] In wireless communication networks, a Base Station (BS) can communicate with a UE in both uplink and downlink directions. LTE introduces sidelinks to allow a UE to transmit 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, Radio Frequency (NR) can be extended to support sidelink communication, D2D communication, V2X communication, and / or C-V2X on licensed and / or unlicensed frequency bands. Summary of the Invention

[0005] The following summary outlines some aspects of this disclosure to provide a basic understanding of the techniques discussed. This summary is not an exhaustive overview of all the intended features of this disclosure, nor is it intended to identify key or essential elements of all aspects of this disclosure, nor to define the scope of any or all aspects of this disclosure. The sole purpose of this summary is to present, in a general form, some concepts of one or more aspects of this disclosure as a prelude to the more detailed description that follows.

[0006] In some aspects of this disclosure, a method of wireless communication performed by a first user equipment (UE) includes performing a channel access procedure to obtain a channel occupancy time (COT) in a sidelink channel. The method also includes sending COT sharing information (COT-SI) to one or more responding UEs. The method further includes sending a first message to at least one of the one or more responding UEs during the COT period. The method also includes avoiding transmission for a certain duration during the COT period after sending the first message. The method further includes, based on conditions, sending a second message to a second UE after the duration during the COT period.

[0007] In some aspects, the first user equipment (UE) includes: one or more memories; and one or more processors coupled to the one or more memories, the one or more memories storing instructions executable individually or in any combination by the one or more processors, the instructions being configured to cause the first UE to perform a channel access procedure to obtain Channel Occupancy Time (COT) in a sidelink channel. The one or more processors are further configured to cause the first UE to send COT-Shared Information (COT-SI) to one or more responding UEs. The one or more processors are further configured to cause the first UE to send a first message to at least one of the one or more responding UEs during the COT. The one or more processors are further configured to cause the first UE to avoid transmission for a certain duration during the COT after sending the first message. The one or more processors are further configured to cause the first UE to send a second message to a second UE after the duration during the COT, based on conditions.

[0008] In some aspects, a non-transitory computer-readable medium (CRM) records program code including: code for causing a first user equipment (UE) to perform a channel access procedure to obtain a channel occupancy time (COT) in a sidelink channel; code for causing the first UE to send COT sharing information (COT-SI) to one or more responding UEs; code for causing the first UE to send a first message to at least one of the one or more responding UEs during the COT; code for causing the first UE to avoid transmission for a certain duration during the COT after sending the first message; and code for causing the first UE to send a second message to a second UE after the duration during the COT based on conditions.

[0009] In some aspects, the first user equipment (UE) includes components for performing a channel access procedure to obtain the Channel Occupancy Time (COT) in the sidelink channel. The first UE also includes components for sending COT sharing information (COT-SI) to one or more responding UEs. The first UE further includes components for sending a first message to at least one of the one or more responding UEs during the COT. The first UE also includes components for avoiding transmission for a certain duration during the COT after sending the first message. The first UE further includes components for sending a second message to a second UE after the duration during the COT based on conditions.

[0010] Other aspects, features, and embodiments of the invention will become apparent to those skilled in the art after reviewing the following description of specific, exemplary embodiments of the invention in conjunction with the accompanying drawings. While features of the invention may be discussed with reference to certain embodiments and the drawings below, all embodiments of the invention may include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of these features may also be used according to the various embodiments of the invention discussed herein. Similarly, while exemplary embodiments may be discussed below as device, system, or method embodiments, it should be understood that these exemplary embodiments may be implemented in various devices, systems, and methods. Attached Figure Description

[0011] Figure 1 Examples of wireless communication networks according to some aspects of this disclosure are provided.

[0012] Figure 2 This is a timing diagram illustrating the radio frame structure according to some aspects of this disclosure.

[0013] Figure 3 An example is illustrated of a wireless communication network that provides sidelink communication according to some aspects of this disclosure.

[0014] Figures 4A to 4C An example diagram illustrating some aspects of this disclosure is provided for a UE to recover transmitted radio frame resources using shared channel occupancy time.

[0015] Figures 5 to 7 An example timing resource diagram with cyclic prefix extension is illustrated, according to some aspects of this disclosure, for resuming transmission by the UE using the shared channel occupancy time.

[0016] Figure 8 This is a block diagram of an exemplary user equipment (UE) according to some aspects of this disclosure.

[0017] Figure 9 This is a flowchart of a wireless communication method according to some aspects of this disclosure. Detailed Implementation

[0018] The detailed description below, 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. To provide a comprehensive understanding of the various concepts, the detailed description includes specific details. 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.

[0019] This disclosure relates throughout to wireless communication systems, also known as wireless communication networks. Various technologies and apparatuses can be used in various aspects of 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" are used interchangeably.

[0020] 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 provided by an organization called the 3rd Generation Partnership Project (3GPP), and 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 groups of telecommunications associations aimed at defining globally applicable third-generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP initiative aimed at improving the UMTS mobile phone standard. 3GPP defines specifications for next-generation mobile networks, mobile systems, and mobile devices. This disclosure relates to the evolution from LTE, 4G, 5G, NR, and more advanced wireless technologies, in which access to the radio spectrum is shared between networks using new and different radio access technologies or collections of radio air interfaces.

[0021] Specifically, 5G networks consider a variety of deployments, spectrums, services, and devices that can be implemented using a unified OFDM-based air interface. 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 (1) ultra-high densities (e.g., approximately 1 M nodes / km). 2 (1) Provide coverage for large-scale Internet of Things (IoT) with ultra-low complexity (e.g., approximately tens of bits / second) and ultra-low energy (e.g., approximately 10+ years of battery life), and provide deep coverage with the ability to reach challenging locations; (2) Provide coverage including strong security, ultra-high reliability (e.g., approximately 99.9999% reliability), ultra-low latency (e.g., approximately 1 millisecond), and mission-critical control for users with extensive or limited mobility; and (3) Provide coverage with enhanced mobile broadband (including extremely high capacity (e.g., approximately 10 Tbps / km)). 2 Coverage with extremely high data rates (e.g., multi-Gbps rates, 100+Mbps user experience rates) and deep awareness with advanced discovery and optimization.

[0022] 5G NR communication systems can be implemented using optimized OFDM-based waveforms with scalable parameter sets and transmission time intervals (TTIs). Additional features may include: a common, flexible framework for efficiently multiplexing services and features using dynamic, low-latency Time Division Duplex (TDD) / Frequency Division Duplex (FDD) designs; and advanced wireless technologies such as massive MIMO, robust millimeter-wave (mmWave) transmission, advanced channel decoding, and device-centric mobility. The scalability of the parameter set in 5G NR efficiently addresses the operation of diverse services across different spectrums and deployments through subcarrier spacing scaling. For example, in various outdoor and macro coverage deployments implementing FDD / TDD below 3 GHz, subcarrier spacing can occur at 15 kHz over bandwidths (BWs) such as 5 MHz, 10 MHz, and 20 MHz. For other various outdoor and small-cell coverage deployments using TDD above 3 GHz, subcarrier spacing can occur at 30 kHz over an 80 MHz / 100 MHz BW. For various other indoor broadband implementations, using TDD on 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 utilizing the mmWave component of TDD at 28 GHz, the subcarrier spacing can occur at 120 kHz over a 500 MHz BW.

[0023] 5G NR's scalable parameter set facilitates scalable TTIs for varying latency and Quality of Service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmission to begin at symbol boundaries. 5G NR also envisions self-contained integrated subframe designs that incorporate UL / downlink scheduling information, data, and acknowledgments within the same subframe. These self-contained integrated subframes support unlicensed or contention-based shared spectrum and can be flexibly configured on a per-cell basis for adaptive UL / downlink communication, dynamically switching between UL and downlink to meet current service demands.

[0024] Various other aspects and features of this disclosure are further described below. It should be apparent that the teachings herein can be embodied in various forms, and any particular structure, function, or both disclosed herein are merely representative and not limiting. Based on the teachings herein, those skilled in the art will understand 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 the aspects set forth herein can be used to implement an apparatus or practice a method. Furthermore, such apparatuses or methods can be implemented using structures, functionalities, or structures and functionalities other than or different from one or more of the 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. Additionally, an aspect may include at least one element of the claims.

[0025] 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 the transmission of sidelink data in the associated PSSCH. In some implementations, the SCI in the PSCCH may be referred to as SCI Part 1 or SCI Phase 1 (SCI-1), and additional SCIs (which may be referred to as SCI Part 2 or SCI Phase 2 (SCI-2)) may be carried in the PSSCH. SCI-2 may include more specific control information for the data carrier in the PSSCH (e.g., transmission parameters, modulation and decoding scheme (MCS)). Use cases for sidelink communication may include V2X, enhanced mobile broadband (eMBB), industrial IoT (IIoT), and / or NR-lightweight.

[0026] In some contexts, the term "sidelink UE" can refer to a user equipment (UE) that performs device-to-device or other types of communication with another UE independently of any tunneling through a BS (e.g., gNB) and / or associated core network. A sidelink UE can be a "sidelink transmitting UE," referring to a UE performing a sidelink transmitting operation, or a "sidelink receiving UE," referring to a UE performing a sidelink receiving operation (i.e., receiving from a sidelink transmitting UE). A sidelink UE can operate as a transmitting sidelink UE at one time and as a receiving sidelink UE at another time.

[0027] In some cases, a sidelink UE can be a "COT-initiating UE," where the sidelink can initiate or acquire Channel Occupancy Time (COT) in a shared radio band (e.g., in shared or unlicensed spectrum) for sidelink communication. For example, the initiating UE can perform Clear Channel Assessment (CCA) or Category 4 (CAT4) Listen-Before-Talk (LBT) in a shared radio band to compete for or acquire the COT. Upon passing the LBT (indicating the channel is idle for transmission), the initiating UE can transmit a sidelink transmission during the acquired COT, and the receiving UE can receive the sidelink transmission from the COT-initiating UE. In some cases, a sidelink UE can be a "responding UE," where the sidelink UE responds to a sidelink transmission using COT by any COT-initiating UE. A sidelink UE can operate as a COT-initiating UE at one time and as a responding UE at another.

[0028] Deploying sidelink services (such as device-to-device (D2D), vehicle-to-vehicle (V2V), vehicle-to-everything (V2X), and / or cellular vehicle-to-everything (C-V2X) communications) on dedicated or licensed spectrum is relatively straightforward because channel access in dedicated or licensed spectrum is guaranteed. NR Unlicensed (NR U) can benefit sidelink services, for example, by offloading sidelink traffic to unlicensed spectrum at no cost. However, channel access in shared or unlicensed spectrum is not guaranteed. Therefore, to deploy sidelink services on shared or unlicensed spectrum, sidelink user equipment (UEs) are required to compete for channel access in that spectrum, for example, via Clear Channel Assessment (CCA) and / or Listen-Before-Speak (LBT) procedures.

[0029] LBT can be based on energy detection (ED) or signal detection. For energy detection-based LBT, the LBT result is pass when the signal energy measured from the channel is below a threshold. Conversely, the LBT result is failure when the signal energy measured from the channel exceeds the threshold. For signal detection-based LBT, the LBT result is pass when no channel reservation signal (e.g., a predetermined preamble) is detected in the channel. Additionally, LBT can be in several modes. LBT modes can be, for example, Type 4 (CAT4) LBT, Type 2 (CAT2) LBT, or Type 1 (CAT1) LBT. CAT1 LBT is called the no-LBT mode, where no LBT is performed before transmission. CAT2 LBT refers to LBT without a random backoff period. For example, the transmitting node can determine the channel measurement within a time interval and determine channel availability based on a comparison of the channel measurement with an ED threshold. CAT4 LBT refers to LBT with random backoff and a variable contention window (CW). For example, the sending node can draw a random number and back off for a duration based on the drawn random number within a certain time unit.

[0030] In some aspects, a sidelink UE initiating a COT can compete for the COT in a shared radio band by performing a CCA or CAT4 LBT. While performing a CCA or CAT4 LBT (indicating the channel is idle for transmission), the sidelink UE can send sidelink transmissions to one or more sidelink receiving UEs during the COT. In some sidelink use cases (e.g., for V2X), sidelink data traffic may include small-sized or short data bursts (e.g., information data ranging from a few bytes to tens of kilobytes). In some aspects, the duration of the COT may depend on regulation imposed by a regulatory body for the shared radio band or specific deployment, and this duration can range from approximately 2 ms to approximately 10 ms (e.g., this duration may correspond to approximately 4 to approximately 20 time slots in NR CV2X with a 30 kHz subcarrier spacing (SCS)). Therefore, in some instances, sidelink transmissions with small-sized data bursts may not occupy the entire duration of the COT. Therefore, it may be desirable to share the remaining duration of the COT with the receiving UE or other UEs, rather than leaving the remaining COT unused. In some instances, the UE initiating a COT may include COT-related information, such as, but not limited to, the duration of the COT, in its transmission, enabling the receiving UE to use this information to share / utilize the COT. For example, the initiating UE may transmit a PSCCH after initiating a COT, and the SCI in the PSCCH may include COT-related information. As another example, the initiating UE may transmit a PSCCH or PSSCH after initiating a COT, and SCI-1 in the PSCCH or SCI-2 in the PSSCH may respectively include COT-related information. In some cases, after receiving an SCI, SCI-1, or SCI-2, when the receiving UE or another UE transmits during a COT initiated by the UE initiating the COT, the receiving UE or another UE may perform a CAT2 LBT or not perform an LBT, which may be advantageous because performing a CAT2 LBT or not performing an LBT has less uncertainty when accessing the channel.

[0031] In some cases, it may be desirable for the UE initiating a COT to reserve at least a portion of the acquired COT for future use. For example, the UE initiating the COT may send a message at the start of the COT, listen for transmissions from responding UEs sharing the COT, and then resume transmission during the COT. However, conflicts may occur between the UE initiating the COT and the responding UEs, each utilizing the same shared resources associated with the COT.

[0032] This disclosure discloses methods, systems, and apparatuses relating to resuming transmission in a sidelink-shared Co-op (COT). A UE initiating the COT may send COT-sharing information (COT-SI) to multiple "responding" UEs. A responding UE is a UE that receives an indication of resources it can use in association with the COT, and may also be referred to as a COT-sharing UE. The UE initiating the COT may send messages to one or more responding UEs using one or more frequency channels after sending the COT-SI. Following this initial transmission, the responding UEs can use the resources indicated in the COT-SI to communicate with the UE initiating the COT. In some aspects, different frequency channels may be allocated to the responding UEs, allowing multiple responding UEs to communicate with the UE initiating the COT simultaneously.

[0033] A UE that initiates a COT may resume transmission at a later time within the same COT period as the initial transmission. To avoid resource conflicts, certain rules or conditions may be used to determine which UE can use certain resources associated with the shared COT for transmission. For example, a resource conflict may occur if the responding UE is only capable of half-duplex communication, and both the responding UE and the COT-initiating UE attempt to send messages to each other using the same shared time and frequency resources. In some respects, a UE that initiates a COT may always resume its own COT.

[0034] In some respects, whether a UE initiating a COT can resume its COT depends on the service objective of the UE initiating the COT. For example, if the target of the UE initiating the COT is not a UE that can share the COT (i.e., a responding UE), then the UE initiating the COT can resume its COT. If the UE initiating the COT indicates the entire shareable COT to all responding UEs, then the target UE that the UE initiating the COT intends to transmit to should not be any responding UE that is instructed to share the COT. If the UE initiating the COT indicates a specific resource (i.e., both time and frequency) to each responding UE, then the target UE that the UE initiating the COT intends to transmit to should not be a responding UE whose indicated shared resource overlaps with the resumed transmission of the UE initiating the COT.

[0035] In some respects, if the target UE to which the UE initiating COT intends to transmit is not a responding UE whose reserved resources overlap with the resumed transmission of the UE initiating COT in time (i.e., a responding UE that performed Frequency Division Multiplexing (FDM)), then the UE initiating COT can resume its COT. In some respects, the ability of the UE initiating COT to resume transmission can further depend on the transmission priority of the UE initiating COT and the transmission priority of the responding UEs that performed FDM. If the UE initiating COT has a transmission priority higher than the highest transmission priority among all responding UEs that performed FDM, then the UE initiating COT can resume COT.

[0036] In some aspects, cyclic prefix extension (CPE) may be included during recovery transmissions by the UE initiating COT. The selection of the CPE length can be configured and predetermined based on heuristics / rules, etc. In some aspects, the responding UE can monitor the channel and sense when the UE initiating COT is transmitting a CPE, and if the UE initiating COT is transmitting, it can discard the scheduled transmission. In this way, the selection of CPE length / starting position can be used to control which UEs have access to the shared COT. For example, in some aspects, the UE initiating COT can always select the earliest starting position of the CPE, i.e., 16 microseconds (µs) before the first message transmission symbol, which ensures that the UE initiating COT takes precedence over the responding UE (unless, for example, the responding UE has the same CPE starting position). In some aspects, the UE initiating COT always selects the earliest starting position for the CPE from the candidate starting positions associated with the expected PSCCH / PSSCH transmission based on the required channel access type.

[0037] In some respects, the UE initiating COT selects the CPE starting location based on both the transmission priority of the responding UE that performed FDM and the CPE itself. For example, if the UE initiating COT has a higher transmission priority than the highest transmission priority among all responding UEs that performed FDM, the UE initiating COT will select an earlier CPE than the CPE of the responding UE that performed FDM. Otherwise, the UE initiating COT may select a later CPE than the CPE of the responding UE that performed FDM. In some respects, the CPE may be initiated before a second CPE associated with a responding UE that has a lower priority than the UE initiating COT and after a third CPE associated with a different responding UE that has a higher priority than the UE initiating COT.

[0038] In some respects, whether a UE initiating a COT will follow the legacy rules to select a CPE depends on conditions. For example, a legacy rule might be: if resource reservation is transmitted or detected, the UE selects the (pre)configured default CPE starting location; otherwise, it can randomly select a CPE starting location from one or more (pre)configured CPE starting candidate locations for each priority transmitted according to the PSCCH / PSSCH. In some respects, the condition is that if a transmission exists before the time slot the UE intends to use, the UE initiating the COT can always select a CPE with a gap equal to 16µs. In some respects, the selection of the CPE depends on the gap within the COT. If any gap between any two transmissions within the COT is as high as 16µs, the UE initiating the COT can always select a CPE with a gap equal to 16µs. If any gap between any two transmissions within the COT is as high as 25µs, the UE initiating the COT can select a CPE with a gap equal to 25µs. If these conditions are not met, the UE initiating the COT can use legacy rules to determine the CPE starting location. The UE initiating COT can determine the gap between two transmissions by measurement or by receiving an indication of the selected starting location from the responding UE. For example, the responding UE can indicate the CPE starting location via SCI-1 or SCI-2.

[0039] The various aspects of this disclosure offer several benefits. The UE initiating the COT can make fuller use of it by allowing other UEs to share the acquired COT, and also allows the UE initiating the COT to use it at different times without causing resource conflicts. This allows for less wasted time sensing channels to acquire the COT and more efficient use of available communication resources.

[0040] Figure 1 A wireless communication network 100 according to some aspects of this disclosure is illustrated. 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 (labeled 115a, 115b, 115c, 115d, 115e, 115f, 115g, 115h, and 115k, respectively), and may also be referred to as an evolved Node B (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.

[0041] BS 105 provides communication coverage for macrocells or small cells (such as picocells or femtocells) and / or other types of cells. Macrocells generally 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) generally 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 generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, provide restricted access by UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in a home, 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 to 105c can be macro BSs with one of three-dimensional (3D), full-dimensional (FD), or massive MIMO capabilities. BS 105a to 105c can utilize their higher-dimensional MIMO capabilities to employ 3D beamforming, either elevation or azimuth beamforming, to increase coverage and capacity. 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.

[0042] Network 100 can support synchronous or asynchronous operation. For synchronous operation, BSs can have similar frame timings, and transmissions from different BSs can be approximately time-aligned. For asynchronous operation, BSs can have different frame timings, and transmissions from different BSs can be out of time-aligned.

[0043] UE 115 is distributed throughout the wireless network 100, and each UE 115 can be stationary or mobile. UE 115 may also be referred to as a terminal, mobile station, subscriber unit, station, etc. UE 115 can 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 can be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, UE 115 can be a device that does not include a UICC. In some aspects, UE 115 without a UICC may also be referred to as an IoT device or Internet of Things (IoE) device. UE 115a-115d are examples of mobile smartphone-type devices accessing network 100. UE 115 can 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 via access network 100. UE 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication via access network 100. UE 115 can communicate with any type of BS (whether a macro BS or a small cell, etc.). Figure 1 In the diagram, the lightning bolt symbol (e.g., a communication link) indicates radio transmission between UE 115 and serving BS 105 (which is a BS designated to serve UE 115 on the downlink (DL) and / or uplink (UL), expected transmission between BS 105, backhaul transmission between BS, or sidelink transmission between UE 115.

[0044] In operation, BS 105a-105c can use 3D beamforming and cooperative spatial technologies, such as Cooperative Multipoint (CoMP) or multiple connectivity, to serve UEs 115a and 115b. Macro BS 105d can perform backhaul communications with BS 105a to 105c and the small cell BS 105f. Macro BS 105d can also transmit multicast services subscribed to and received by UEs 115c and 115d. Such multicast services may include mobile TV or streaming video, or other services for providing community information, such as weather emergencies or alerts, such as Amber Alerts or Grey Alerts.

[0045] BS 105 can also communicate with a core network. This core network provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs in BS 105 (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) via backhaul links (e.g., X1, X2, etc.), which can be wired or wireless communication links.

[0046] Network 100 can also support mission-critical communication using ultra-reliable and redundant links for mission-critical devices such as UE 115e, which may 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 via another user equipment of UE 115f (such as relaying temperature measurement information to the network via small cell BS 105f) in a multi-step configuration. Network 100 can also provide additional network efficiency through dynamic low-latency TDD / FDD communications, such as V2V, V2X, C-V2X communications between UE 115i, 115j or 115k and other UE 115 and / or vehicle-to-infrastructure (V2I) communications between UE 115i, 115j or 115k and BS 105.

[0047] 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, tones, 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.

[0048] In some aspects, BS 105 can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RBs)) for downlink (DL) and uplink (UL) transmissions in network 100. DL refers to the transmission direction from BS 105 to UE 115, while UL refers to the transmission direction from UE 115 to BS 105. This communication can take the form of radio frames. Radio frames can be divided into multiple subframes or time slots, for example, about 10. Each time slot can also be divided into micro-time slots. In FDD mode, simultaneous UL and DL transmissions can 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 at different time periods using the same frequency band. For example, a subset of subframes in a radio frame (e.g., DL subframes) can be used for DL ​​transmission, and another subset of subframes in the radio frame (e.g., UL subframes) can be used for UL transmission.

[0049] DL subframes and UL subframes can also be divided into several zones. For example, each DL subframe or UL subframe may have a predefined zone for transmitting 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, where pilot tones may span an operational BW or frequency band, and each pilot tone is located at a predefined time and predefined frequency. For example, BS 105 may transmit a cell-specific reference signal (CRS) and / or a channel state information-reference signal (CSI-RS) to enable UE 115 to estimate the DL channel. Similarly, UE 115 may transmit a sounding 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-centric or UL-centric. DL-centric subframes can include DL communication durations longer than UL communication durations. UL-centric subframes can include UL communication durations longer than UL communication durations.

[0050] 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 blocks (SSB) via the physical broadcast channel (PBCH), and may broadcast RMSI and / or OSI via the physical downlink shared channel (PDSCH).

[0051] In some respects, UE 115 attempting to access network 100 can perform an initial cell search by detecting the PSS from BS 105. The PSS enables time-slot synchronization and indicates a physical layer identification value. UE 115 can then receive the SSS. The SSS enables radio frame synchronization and provides a cell identification value, which can be combined with the physical layer identification 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.

[0052] 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.

[0053] After obtaining the MIB, RMSI, and / or OSI, UE 115 may perform a random access procedure to establish a connection with BS 105. In some examples, the random access procedure may be a four-step random access procedure. For example, UE 115 may send a random access preamble, and BS 105 may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, UL grant, temporary cell radio network temporary identifier (C-RNTI), and / or backoff indicator. Upon receiving the random access response, UE 115 may send a connection request to BS 105, and BS 105 may respond with a connection response. The connection response may indicate contention resolution. In some examples, the random access preamble, RAR, connection request, and connection response may be referred to as message 1 (MSG1), message 2 (MSG2), message 3 (MSG3), and message 4 (MSG4), respectively. In some examples, the random access procedure can be a two-step random access procedure, where UE 115 can send the random access preamble and connection request in a single transmission, and BS 105 can respond by sending the random access response and connection response in a single transmission. The combined random access preamble and connection request in the two-step random access procedure can be referred to as message A (MSG A). The combined random access response and connection response in the two-step random access procedure can be referred to as message B (MSG B).

[0054] After the connection is established, UE 115 and BS 105 can enter the normal operation phase, during which they can exchange operational data. For example, BS 105 can schedule UE 115 for UL communication and / or DL ​​communication. BS 105 can send UL scheduling permission and / or DL ​​scheduling permission to UE 115 via PDCCH. BS 105 can send DL communication signals to UE 115 via PDSCH based on DL scheduling permission. UE 115 can send UL communication signals to BS 105 via PUSCH and / or PUCCH based on UL scheduling permission. The connection may be referred to as an RRC connection. When UE 115 actively exchanges data with BS 105, UE 115 is in an RRC connection state.

[0055] In the example, after establishing a connection with BS 105, UE 115 can initiate an initial network attach procedure with network 100. BS 105 can coordinate with various network entities or 5G core (5GC) entities, such as Access and Mobility Functions (AMF), Serving Gateways (SGW), and / or Packet Data Network Gateways (PGWs), to complete the network attach procedure. For example, BS 105 can coordinate with network entities in the 5GC to identify, authenticate, and / or authorize the UE to transmit and / or receive data in network 100. Furthermore, the AMF can assign a set of Tracking Areas (TAs) to the UE. Once the network attach procedure is successful, a context is established for UE 115 in the AMF. After successfully attaching to the network, UE 115 can move around the current TA. For Tracking Area Updates (TAUs), BS 105 can request UE 115 to periodically update network 100 with UE 115's location. Alternatively, UE 115 can report its location to network 100 only when entering a new TA. TAU allows network 100 to quickly locate and page UE 115 when it receives an incoming data packet or a call to UE 115.

[0056] In some respects, BS 105 may use Hybrid Automatic Repeat Request (HARQ) technology to communicate with UE 115 to improve communication reliability, such as to provide URLLC services. BS 105 may schedule UE 115 for PDSCH communication by sending DL permission in the PDCCH. BS 105 may send DL data packets to UE 115 according to the scheduling in the PDSCH. DL data packets may be sent in transport blocks (TBs). If UE 115 successfully decodes the DL data packets, UE 115 may send a HARQ acknowledgment (ACK) to BS 105. Conversely, if UE 115 fails to successfully decode the DL transmission, UE 115 may send a HARQ negative acknowledgment (NACK) to BS 105. Upon receiving a HARQ NACK from UE 115, BS 105 may retransmit the DL data packets to UE 115. The retransmission may include the same decoded version of the DL data as the initial transmission. Alternatively, the retransmission may include a different decoded version of the DL data than the initial transmission. UE 115 can apply soft combining to combine encoded data received from the initial transmission and retransmission for decoding. BS 105 and UE 115 can also use a mechanism substantially similar to DL HARQ to apply HARQ to UL communications.

[0057] 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., portions). BS 105 may dynamically assign UE 115 to operate on a specific BWP (e.g., a specific portion 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 communication or DL ​​communication within the active BWP. In some aspects, BS 105 may assign a pair of BWPs within a CC to UE 115 for both UL and DL communication. For example, the BWP pair may include one BWP for UL communication and one BWP for DL ​​communication.

[0058] In some aspects, network 100 can operate on a shared channel, which may include a shared frequency band or an unlicensed frequency band. For example, network 100 may be an unlicensed NR (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 an LBT procedure to monitor for 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 can 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 continue transmitting. When LBT fail, the transmitting node may prohibit 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 "pass". Conversely, when the signal energy measured from the channel exceeds the threshold, the LBT result is "fail". In another example, LBT can be based on signal detection. For example, when no channel reservation signal (e.g., a predetermined preamble signal) is detected in the channel, the LBT result is "pass". Conversely, when a channel reservation signal is detected in the channel, the LBT result is "fail". TXOP can also be referred to as Channel Occupancy Time (COT).

[0059] In some aspects, 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. As discussed above, sidelink communication can occur on PSCCH and PSSCH. For example, PSCCH can carry SCI, and PSSCH can carry SCI and / or sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH can carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. In some examples, the sending sidelink UE 115 can indicate the SCI in two phases. In the first phase SCI (which may be referred to as SCI-1), UE 115 can transmit an SCI in the PSCCH carrying information for resource allocation and decoding of 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 decoding scheme (MCS), etc. In the second-stage SCI (which may be referred to as SCI-2), UE 115 may transmit an SCI carrying information for decoding the PSSCH in the PSCCH. The second-stage SCI may include an 8-bit L1 destination identifier (ID), an 8-bit L1 source 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 these provided examples. Sidelink communication can also be transmitted via the Physical Side Link Feedback Control Channel (PSFCH), which indicates acknowledgment (ACK) - negative acknowledgment (NACK) for previously transmitted PSSCH.

[0060] In some aspects, sidelink communication can be in unicast, multicast, or broadcast mode, where HARQ can be applied to unicast and / or multicast communication. For unicast communication, the sidelink transmitting UE 115 can transmit a sidelink transmission including data to a single sidelink receiving UE 115 and can request HARQ acknowledgment / negative acknowledgment (ACK / NACK) feedback from that sidelink receiving UE 115. If the sidelink receiving UE 115 successfully decodes the data from the sidelink transmission, it transmits an ACK. Conversely, if the sidelink receiving UE 115 fails to decode the data from the sidelink transmission, it transmits a NACK. Upon receiving a NACK, the sidelink transmitting UE 115 can retransmit the data. For broadcast communication, the sidelink transmitting UE 115 can transmit a sidelink transmission to a group 115 of sidelink receiving UEs 115 in its neighborhood (e.g., 2, 3, 4, 5, 6, or more) without requesting ACK / NACK feedback for that sidelink transmission.

[0061] For multicast communication, the sidelink transmitting UE 115 can transmit sidelink transmissions to a group of sidelink receiving UEs 115 (e.g., 2, 3, 4, 5, 6, or more). Multicast communication can have a wide variety of use cases in a sidelink. For example, multicast communication can be used in V2X use cases (e.g., vehicle queuing) to instruct a group of vehicles near an intersection or traffic light to stop at the intersection. In some aspects, multicast communication can be connection-based, where the group of sidelink receiving UEs 115 can be pre-configured as a group identified by a group identifier (ID). Thus, the sidelink receiving UEs 115 in the group are known to the sidelink transmitting UE 115, and therefore the sidelink transmitting UE 115 can request ACK / NACK feedback from each sidelink receiving UE 115 in the group. In some instances, the sidelink transmitting UE 115 can provide each sidelink receiving UE with different resources (e.g., orthogonal resources) for transmitting ACK / NACK feedback. In some other aspects, multicast communication can be connectionless, where the sidelink receiving UE group 115 capable of receiving the multicast transmission may be unknown to the sidelink transmitting UE 115. In some instances, the sidelink receiving UE group 115 may receive multicast communication based on the district or geographic location of the receiving UE 115. Since the sidelink transmitting UE 115 may not have knowledge of the receiving sidelink UE 115, the sidelink transmitting UE 115 may request only NACK feedback from the sidelink receiving UE 115, referred to as multicast option 1 transmission. For example, if the sidelink receiving UE detects the presence of SCI but fails to decode the data (transport block) from the sidelink transmission, the sidelink receiving UE 115 may transmit NACK. If the data is successfully decoded, the sidelink receiving UE 115 may not transmit ACK. Multicast option 2 transmission refers to the scenario where the sidelink receiving UE transmits ACK if the data decoding is successful and NACK if decoding fails. In some instances, the sidelink receiving UE 115 may be assigned the same resources for transmitting NACK feedback. Synchronous NACK transmissions from multiple sidelink receiving UEs 115 from the same resource can form a single-frequency network (SFN) transmission at the sidelink transmitting UE 115 (where the waveforms of multiple NACK transmissions are combined). Similar to unicast communication, the sidelink transmitting UE 115 can retransmit sidelink data when it receives a NACK for connection-based or connectionless multicast transmission.

[0062] In some respects, the UE initiating a COT may send COT sharing information (COT-SI) to other UEs. The COT-SI may be sent as a separate message using PSCCH or PSSCH, or as part of SCI-1, SCI-2, or other appropriate message structures. The COT-SI may indicate the time and / or frequency resources allocated to the responding UE, where there are fewer or no LBT requirements due to the sharing of the COT acquired by the initiating UE. In some respects, the responding UE is not permitted to use shared COT resources when communicating with UEs other than the initiating UE. However, the initiating UE may communicate during the COT with UEs other than the responding UE whose resources are indicated via the COT-SI.

[0063] Figure 2 This is a timing diagram illustrating a radio frame structure 200 according to some aspects of this disclosure. The radio frame structure 200 can be used for communication by a BS (such as BS 105) and a UE (such as UE 115) in a network (such as network 100). Specifically, the BS can use time-frequency resources configured as shown in the radio frame structure 200 to communicate with the UE. Figure 2 In this diagram, the x-axis represents time in some arbitrary unit, and the y-axis represents frequency in some arbitrary unit. The radio frame structure 200 includes a radio frame 201. The duration of the radio frame 201 can vary depending on various factors. In one example, the radio frame 201 may have a duration of approximately ten milliseconds. The radio frame 201 includes M time slots 202, where M can be any suitable positive integer. In one example, M may be approximately 10.

[0064] Each time slot 202 includes multiple subcarriers 204 in frequency and multiple symbols 206 in time. The number of subcarriers 204 and / or symbols 206 in time slot 202 can vary depending on various factors, such as channel bandwidth, subcarrier spacing (SCS), and / or CP mode. One subcarrier 204 in frequency and one symbol 206 in time form a resource element (RE) 212 for transmission. A resource block (RB) 210 is formed by multiple consecutive subcarriers 204 in frequency and multiple consecutive symbols 206 in time.

[0065] In some respects, BS (for example, Figure 1 BS 105 in the middle can schedule the UE at the time granularity of time slot 202 or micro-time slot 208 (e.g., Figure 1UE 115 in the BS performs UL and / or DL ​​communication. Each time slot 202 can be time-divided into K micro-time slots 208. Each micro-time slot 208 may include one or more symbols 206. Micro-time slots 208 in time slot 202 may have variable lengths. For example, when time slot 202 includes N symbols 206, micro-time slot 208 may have a length between one symbol 206 and (N-1) symbols 206. In some aspects, micro-time slot 208 may have a length of approximately two symbols 206, approximately four symbols 206, or approximately seven symbols 206. In some examples, the BS may schedule the UE at a frequency granularity of resource blocks (RBs) 210 (e.g., including approximately 12 subcarriers 204 of 1 symbol, 2 symbols, ..., 14 symbols). In some aspects, the UE (e.g., Figure 1 UE 115i) can be in a time slot similar to time slot 202 with another UE (e.g., Figure 1 The UE 115j performs sidelink communication.

[0066] In some respects, the acquired COT may have a duration of one or more microslots or one or more time slots. The resources allocated to different UEs (the UE initiating the COT or the responding UE) as indicated in the COT-SI may be indicated based on the time within the microslot or time slot structure.

[0067] Figure 3 An example of a wireless communication network 300 providing sidelink communication according to various aspects of this disclosure is illustrated. Network 300 may correspond to a portion of network 100, which may utilize radio frame structure 200 for communication. For the purpose of simplifying the discussion, Figure 3 The description includes one BS 305 and five UEs 315 (shown as 315a, 315b, 315c, 315d, and 315e), although it will be appreciated that aspects of this disclosure are extendable to any suitable number of UEs 315 (e.g., approximately 2, 3, 4, 6, 7, or more) and / or BS 305 (e.g., approximately 2, 3, or more). BS 305 and UE 315 may be similar to BS 105 and UE 115, respectively. BS 305 and UE 315 may share the same radio band for communication. In some instances, the radio band may be a licensed band. In some instances, the radio band may be an unlicensed band. In some instances, the radio band may be a frequency range 1 (FR1) band. In some instances, the radio band may be an FR2 band. Generally, the radio band may be at any suitable frequency.

[0068] In network 300, some UEs in UE 315 can communicate with each other in peer-to-peer communication. For example, UE 315a can communicate with UE 315b via side link 351, UE 315c can communicate with UE 315d via side link 352 and / or with UE 315e via side link 354, and UE 315d can communicate with UE 315e via side link 355. Side links 351, 352, 354, and 355 are unicast bidirectional links. In some respects, UE 315c can also communicate with UE 315d and UE 315e in multicast mode. Similarly, UE 315d can also communicate with UE 315c and UE 315e in multicast mode. Generally, UEs 315c, 315d, and 315e can communicate with each other in either unicast or multicast mode. In some respects, COT-SI can be delivered via ensemble or unicast.

[0069] Some UEs in UE 315 may also communicate with BS 305 in the UL direction and / or DL ​​direction via communication link 353. For example, UEs 315a, 315b, and 315c are within the coverage area 310 of BS 305 and therefore can communicate with BS 305. UEs 315d and UE 315e are outside the coverage area 310 and therefore may not communicate directly with BS 305. In some instances, UE 315c may operate as a repeater for UE 315d to reach BS 305. In some aspects, some UEs in UE 315 are associated with vehicles (e.g., similar to UEs 115i to 115k), and communication via side links 351 and / or 352 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.

[0070] Figures 4A to 4C An example diagram illustrating some aspects of this disclosure is provided for a UE to recover transmitted radio frame resources using shared channel occupancy time. Figures 4A to 4C In each of these, the X-axis represents time in some units, and the Y-axis represents frequency in some units. The illustrated frames may represent time slots, micro-slots, portions of time slots, or more than one time slot within a radio frame. Arrows indicate the assignment / allocation / indication of frequency and / or time resources, particularly those associated with shared COT. Figures 4A to 4C The conditions under which a UE initiating a COT can resume transmission within a shared COT are described. It should be noted that, in some respects, a UE initiating a COT can always resume its own COT, regardless of the state of other UEs sharing the COT.

[0071] Figure 4AOne aspect of this disclosure is illustrated, in which the UE initiating COT (designated herein as UE 0) resumes transmission during a COT shared with the responding UE. In some aspects, whether the UE initiating COT can resume its COT depends on the service objective of the UE initiating COT. For example, if the target of the UE initiating COT is not a UE that can share COT (i.e., the responding UE), then the UE initiating COT can resume its COT. Figure 4A In this context, COT-SI indicates to each responding UE that the entire COT is available for transmission, and therefore a UE sharing the COT (UE 0) can resume transmission only if it resumes transmission to any responding UE that is not a responding UE.

[0072] As illustrated, COT-SI 402 is sent to multiple responding UEs (UE 1, UE 2, and UE 3). UE 0 may transmit to one or more UEs during transmission 404 within the acquired COT. Subsequently, UE 1 may use all or part of the acquired frequency resources to transmit message 406 to UE 0. UE 2 and UE 3 may transmit messages 408 and 410 to UE 0, respectively. Note that messages 408 and 410 may be transmitted at overlapping times because they use different frequency resources. UE 0 may resume transmission by sending message 412 to UE 4. In some respects, UE 4 is not a responding UE because it has not received the resources indicated by the shared COT. Since UE 4 is not a responding UE, there is no risk that UE 4 will attempt to transmit to UE 0 during the COT, and therefore UE 0 is free to resume transmission to UE 4 using the resources.

[0073] Figure 4BAnother aspect of this disclosure is illustrated, wherein the UE initiating the COT (designated herein as UE 0) resumes transmission during a COT shared with a responding UE. In some aspects, if the UE initiating the COT (UE 0) indicates a designated resource (i.e., both time and frequency) to each responding UE, the target UE for which the UE initiating the COT intends to transmit should not be a responding UE whose indicated shared resource overlaps with the resumed transmission of the UE initiating the COT. As illustrated, the area with the hash marker is the resource indicated in the COT-SI for each responding UE. For example, the shaded area next to message 406 indicates that the shaded area is allocated by the COT-SI for additional transmission from UE 1. Similarly, UE 2 can use the indicated area adjacency message 408 to further transmit to UE 0. Since the COT-SI does not indicate the complete COT to each responding UE, this allows the UE initiating the COT greater flexibility in which responding UE it can communicate with during the resumed transmission. For example, message 414 could be sent to UE 3, since UE 3 is not sharing resources at that time. Message 416 can be sent to either UE 2 or UE 3 because the resources indicated for UE 2 expire before the time when message 416 is scheduled. In this way, in some respects, the UE that initiated COT can resume sending to the responding UE.

[0074] Figure 4CAnother aspect of this disclosure is illustrated, wherein the UE initiating the COT (designated herein as UE 0) resumes transmission during the COT shared with the responding UE. In some aspects, the UE initiating the COT may resume its COT if the target UE to which the UE intends to transmit is not a responding UE that has performed FDM (i.e., a responding UE whose reserved resources overlap with the resumption of transmission by the UE initiating the COT in time). As illustrated, COT-SI 402 is sent to multiple responding UEs (UE 1, UE 2, and UE 3). UE 0 may transmit to one or more UEs within the acquired COT at the time of transmission 404. Subsequently, UE 1 may use all or part of the acquired frequency resources to send message 406 to UE 0. UE 2 and UE 3 may send messages 408 and 410 to UE 0, respectively. It should be noted that messages 408 and 410 may be sent at overlapping times because they use different frequency resources. UE 1 may also send message 418 to UE 0. UE 0 can resume transmission via message 420, which is sent to UE 2 and / or UE 3 using a different frequency resource than message 418 from UE 1. The condition illustrated here is that UE 0 can resume transmission to a responding UE that is not performing FDM, in the case of message 420, which is UE 1, which simultaneously sent message 418. Furthermore, if UE 3 sends message 422, concurrently, UE 0 can resume transmission by sending message 424 to UE 1 and / or UE 2, since they are not performing FDM at that time.

[0075] In some respects, UE 0 can resume its transmission based on the transmission priority of the UE that initiated COT (UE 0) and the transmission priority of the UE that responded with FDM. For example, if the UE that initiated COT (UE 0) has a higher transmission priority than the highest transmission priority among all UEs that responded with FDM, then the UE that initiated COT can resume COT regardless.

[0076] Figures 5 to 7 An example timing resource diagram with cyclic prefix extension is illustrated, according to some aspects of this disclosure, for resuming transmission by the UE using shared channel occupancy time. Figures 5 to 7 In each of these, the X-axis represents time in some units, and the Y-axis represents frequency in some units. The illustrated frames may represent time slots, micro-time slots, portions of time slots, or more than one time slot within a radio frame.

[0077] Figure 5One aspect of this disclosure is illustrated, wherein the UE initiating the COT (designated herein as UE 0) resumes transmission during the COT shared with the responding UE and includes a cyclic prefix extension (CPE) upon resuming transmission. In some aspects, the selection of the CPE length can be configured and predetermined based on heuristics / rules, etc. In some aspects, the responding UE can monitor the channel and sense when the UE initiating the COT is transmitting a CPE, and if the UE initiating the COT is transmitting, it can discard the scheduled transmission. In this way, the selection of the CPE length / starting position can be used to control which UEs have access to the shared COT. For example, in some aspects, the UE initiating the COT can always select the earliest starting position of the CPE, i.e., 16 microseconds (µs) before the first message transmission symbol, which ensures that the UE initiating the COT takes precedence over the responding UE (unless, for example, the responding UE has the same CPE starting position). Figure 5 The illustration in the diagram illustrates message 508 from UE 1 to UE 0 in time slot 502, another time slot 504, and then message 510 from the COT-initiating UE (UE 0) to UE 1 in time slot 506. The extended portion in the diagram represents one or more symbol periods immediately preceding time slot 506, which includes message 510. As illustrated, the symbol period may include segments 520-526, each of which may be 16µs and / or 9µs in length. In the example above, the CPE for message 510 will be determined by UE 0 to be initiated after segment 520, such that there is only a 16µs gap between the transmission in time slot 504 and message 510, which includes the CPE. In some respects, the UE initiating the COT always selects the earliest start location for the CPE from the candidate start locations associated with the expected PSCCH / PSSCH transmission based on the desired channel access type. For example, if the channel access type requires a longer channel sensing time, a gap period longer than 16µs may be used.

[0078] Figure 5 The illustration in the diagram illustrates an example scenario, which only shows a portion of the resources.

[0079] Figure 6 Another aspect of this disclosure is illustrated, wherein the UE that initiates the COT (designated herein as UE 0) resumes transmission during the COT shared with the responding UE and includes a cyclic prefix extension (CPE) upon resuming transmission.

[0080] In some aspects, the UE initiating COT selects the CPE starting location based on both the transmission priority of the responding UE that performed FDM and the CPE itself. For example, if the transmission priority of the UE initiating COT is higher than the highest transmission priority among all responding UEs that performed FDM, the UE initiating COT will select an earlier CPE than the CPE of the responding UE that performed FDM. Otherwise, the UE initiating COT may select a later CPE than the CPE of the responding UE that performed FDM. In some aspects, the CPE may be initiated before a second CPE associated with a responding UE that has a lower priority than the UE initiating COT and after a third CPE associated with a different responding UE that has a higher priority than the UE initiating COT. As illustrated, the symbol period may include segments 620-626, each of which may be 16 µs and / or 9 µs in length.

[0081] For example, Figure 6 Examples include the initial message 610 from UE 0 (the UE initiating the COT) to UE 1, response messages 612, 614, and 618, and the message 616 resuming transmission from UE 0 to UE 1. If UE 0 has a higher priority than UE 1, UE 2, and UE 3, UE 0 can select the earliest permissible CPE to initiate, for example, allowing a 16µs gap after segment 620. If UE 0 has a higher priority than some responding UEs but a lower priority than others, the CPE of message 616 can be selected such that the CPE initiates only before the lower priority responding UEs. For example, based on priority determination, UE 0 can initiate the CPE after segment 622.

[0082] Figure 7Another aspect of this disclosure is illustrated, wherein the UE initiating the COT (designated herein as UE 0) resumes transmission during the COT shared with the responding UE and includes a Cyclic Prefix Extension (CPE) upon resuming transmission. In some aspects, whether the UE initiating the COT will follow legacy rules to select the CPE depends on conditions. In some aspects, the condition is that if a transmission exists prior to the time slot intended for use by the UE initiating the COT, the UE initiating the COT may always select a CPE that makes the gap equal to 16 µs. In some aspects, the selection of the CPE depends on the gap within the COT. If any gap between any two transmissions within the COT is as high as 16 µs, the UE initiating the COT may always select a CPE that makes the gap equal to 16 µs. If any gap between any two transmissions within the COT is as high as 25 µs, the UE initiating the COT may select a CPE that makes the gap equal to 25 µs. If these conditions are not met, the UE initiating the COT may use legacy rules to determine the CPE starting position. The UE initiating the COT may determine the gap between two transmissions by measurement or by receiving an indication of the selected starting position from the responding UE. For example, the UE can indicate the CPE to start positioning via SCI-1 or SCI-2.

[0083] exist Figure 7 In the example illustrated, message 710 is sent from UE 0 (the UE initiating the COT) to responding UE 1 in time slot 702. Message 712 is sent from UE 2 to UE 0 in time slot 704. Message 714 is sent from UE 3 to UE 0 in time slot 706. Message 716 is sent from UE 0 to UE 1 in time slot 708. Message 716 may include a CPE initiated at a time determined by the conditions described above. Here, there are two additional gaps between messages in the shared COT, specifically, gap 730 between messages 710 and 712, and gap 734 between messages 712 and 714. Based on the duration of these gaps, UE 0 can determine the CPE initiation location to achieve the specific gap between messages 714 and 716. Figures 5 to 6Similarly, an extended view of the symbols immediately preceding the resumption of UE 0's transmission is illustrated, where segments 720-726 illustrate potential CPE initiation times. In some aspects, UE 0 ignores gaps 730 and 734 and chooses to initiate the CPE after segment 720. In some aspects, both gaps 730 and 734 have a duration of 16µs, and UE 0 determines to initiate the CPE based on at least one of the gap durations 730 and 734, leaving a 16µs gap (i.e., after segment 720). In some aspects, both gaps 730 and 734 have a duration of 25µs, and UE 0 determines to initiate the CPE based on at least one of the gap durations 730 and 734, leaving a 25µs gap (i.e., after segment 721).

[0084] Figure 8 This is a block diagram of an exemplary UE 800 according to some aspects of this disclosure. UE 800 may be as described above regarding... Figure 1 The UE 115 under discussion. As shown in the figure, UE 800 may include a processor 802, a memory 804, a COT sharing module 808, a transceiver 810 including a modem subsystem 812 and a radio frequency (RF) unit 814, and one or more antennas 816. These components may be coupled to each other. The term "coupled" may refer to direct or indirect coupling or connection to one or more intermediary components. For example, these components may communicate directly or indirectly with each other, for example, via one or more buses.

[0085] Processor 802 may have various features as a particular type of 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 802 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.

[0086] Memory 804 may include cache memory (e.g., the cache memory of processor 802), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory devices, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or combinations of different types of memory. In some aspects, memory 804 may include a non-transitory computer-readable medium. Memory 804 may store instructions 806. Instructions 806 may include, when executed by processor 802, causing processor 802 to perform the operations described herein (e.g., ...). Figures 1 to 8Instructions (as shown in Figure 10). Instruction 806 may also be referred to as program code, which can be broadly interpreted as including any type of computer-readable statement. 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 802) to control or command the wireless communication device to do so. The terms "instruction" and "code" should be broadly interpreted to include any type of computer-readable statement. For example, the terms "instruction" and "code" can refer to one or more programs, routines, subroutines, functions, procedures, etc. "Instruction" and "code" can include a single computer-readable statement or multiple computer-readable statements.

[0087] The COT shared module 808 may be implemented via hardware, software, or a combination thereof. For example, the COT shared module 808 may be implemented as a processor, circuitry, and / or instructions 806 stored in memory 804 and executed by processor 802. In some examples, the COT shared module 808 may be integrated within the modem subsystem 812. For example, the COT shared module 808 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 812.

[0088] The COT shared module 808 can communicate with various components of the UE 800 to perform various aspects of this disclosure, such as, Figures 1 to 7 and Figure 9 In some aspects, the COT sharing module 808 is configured to perform a channel access procedure to acquire the Channel Occupied Time (COT) in a sidelink channel on an unlicensed new radio (NR) band. The COT sharing module 808 is further configured to use the acquired COT to transmit, stop transmitting, and resume transmission within the same COT, according to the method described herein. The COT sharing module 808 is further configured to determine a Cyclic Prefix Extension (CPE) according to the implementation described herein and apply the CPE to one or more transmissions.

[0089] As shown in the figure, transceiver 810 may include modem subsystem 812 and RF unit 814. Transceiver 810 may be configured to communicate bidirectionally with other devices, such as BS 105. Modem subsystem 812 may be configured to modulate and / or encode data from memory 804 and / or COT sharing module 808 according to a modulation and decoding scheme (MCS) (e.g., low-density parity-check (LDPC) decoding scheme, turbo decoding scheme, convolutional decoding scheme, digital beamforming scheme, etc.). RF unit 814 can be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / encoded data (e.g., PSCCH, PSSCH, SCI-1, SCI-2, sidelink data, COT-SI, COT sharing information, such as but not limited to COT duration, reserved COT time / frequency location, offset from COT reservation, reserved COT starting subchannel, received COT resource width, etc.) transmitted from modem subsystem 812 (regarding outbound transmission) or originating from another source (such as UE115 or BS 105). RF unit 814 can be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as integrated together in transceiver 810, modem subsystem 812 and RF unit 814 can be separate devices coupled together at UE115 to enable UE115 to communicate with other devices. In some respects, transceiver 810 may be configured to transmit COT sharing information (COT-SI) configured to reserve one or more COTs in a sidelink channel on an unlicensed new radio (NR) band, which are acquired by COT sharing module 808 via a channel access procedure, for example for future transmission via the sidelink channel.

[0090] RF unit 814 may provide modulated and / or processed data, such as data packets (or more generally, data messages that may include one or more data packets and other information), to antenna 816 for transmission to one or more other devices. Antenna 816 may further receive data messages transmitted from other devices. Antenna 816 may provide the received data messages for processing and / or demodulation at transceiver 810. Transceiver 810 may provide demodulated and decoded data (e.g., PSCCH, PSSCH, SCI-1, SCI-2, sidelink data, COT-SI, COT sharing information) to COT sharing module 808 for processing. Antenna 816 may include multiple antennas with similar or different designs to maintain multiple transmission links. RF unit 814 may configure antenna 816.

[0091] In one aspect, UE 800 may include multiple transceivers 810 implementing different RATs (e.g., NR and LTE). In another aspect, UE 800 may include a single transceiver 810 implementing multiple RATs (e.g., NR and LTE). In yet another aspect, transceiver 810 may include various components, wherein different combinations of components may implement different RATs.

[0092] Figure 9 This is a flowchart of method 900 according to some aspects of this disclosure. Aspects of method 900 may be performed by a computing device of a wireless communication device (e.g., one or more memories and one or more processors coupled to the one or more memories (which store instructions executable individually or in any combination by the one or more processors) and / or other suitable components) or other suitable components for performing the steps. For example, a wireless communication device (such as UE 115, UE 315, or UE 800) may utilize one or more components (such as processor 802, memory 804, COT sharing module 808, transceiver 810, modem 812, and one or more antennas 816) to perform the steps of method 900. Method 900 may employ the same methods described above. Figures 1 to 8 A similar mechanism to that described herein. As illustrated, method 900 includes multiple listed steps, but aspects of method 900 may include additional steps before, after, and between the listed steps. In some aspects, one or more of the listed steps may be omitted or performed in a different order.

[0093] At box 901, in some respects, the first UE (e.g., UE 115, UE 315, or UE 800) performs a channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel.

[0094] At box 902, in some respects, the first UE sends COT sharing information (COT-SI) to one or more responding UEs.

[0095] At box 903, in some respects, the first UE sends a first message to at least one of one or more responding UEs during COT.

[0096] At box 904, in some respects, the first UE avoids sending during a certain duration in the COT period after sending the first message.

[0097] At box 905, in some aspects, the first UE sends a second message to the second UE after the duration of the COT, based on a condition. In some aspects, the condition includes that the second message be sent using time and frequency resources that do not overlap with the time and frequency resources allocated to the second UE via the COT-SI. In some aspects, the second UE is not a responding UE among responding UEs. For example, the second UE may be a different UE that does not receive the COT-SI and / or does not receive an indication in the COT-SI that has resources for sharing the COT. In some aspects, the second UE is a responding UE among responding UEs. For example, under certain conditions, the first UE may resume transmission and send a second message to the second UE, which is a responding UE sharing the COT. In some aspects, the condition includes that the second message be sent using time resources that do not overlap with the time resources allocated to the second UE. In some aspects, the condition also includes that the first UE has a higher priority than all responding UEs that have been allocated time resources that overlap with the time resources to be used to send the second message.

[0098] At box 906, in some aspects, the first UE transmits a cyclic prefix extension (CPE) associated with the second message. In some aspects, the CPE is initiated a predetermined amount of time before the second message. In some aspects, the CPE is initiated a certain amount of time before the second message based on the channel access type. In some aspects, the CPE is initiated a certain amount of time before the second message based on a first transmission priority of the second message and a second transmission priority associated with one of the one or more responding UEs. In some aspects, the CPE is initiated before a second CPE associated with a responding UE having a lower priority than the first UE and after a third CPE associated with a different responding UE having a higher priority than the first UE. In some aspects, the first UE has a transmission priority higher than the highest transmission priority of any of the one or more responding UEs, and the CPE is initiated before any CPE associated with any of the one or more responding UEs based on the transmission priority. In some aspects, the CPE is initiated a predetermined amount of time after transmission from one of the one or more responding UEs. In some aspects, the CPE is initiated a certain amount of time before the second message based on the interval between transmissions during COT. In some respects, the first UE measures the gap time or receives an indication of the gap time from one or more responding UEs.

[0099] This disclosure includes some references. Aspect 1. A method for wireless communication performed by a first user equipment (UE), the method comprising: Perform a channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel. Send COT sharing information (COT-SI) to one or more responding UEs; During the COT, a first message is sent to at least one of the one or more responding UEs; After sending the first message, avoid sending for a certain duration during the COT period; and Based on the conditions, a second message is sent to the second UE after the duration during the COT period. Aspect 2. The method according to aspect 1, wherein the condition includes that the second message is to be transmitted using time and frequency resources that do not overlap with the time and frequency resources allocated to the second UE via the COT-SI. Aspect 3. The method according to aspect 2, wherein the second UE is not one of the one or more responding UEs. Aspect 4. The method according to aspect 2, wherein the second UE is one of the one or more responding UEs. Aspect 5. The method according to aspect 1, wherein the condition includes that the second message is to be sent using time resources that do not overlap with the time resources allocated to the second UE. Aspect 6. The method according to aspect 5, wherein the condition further includes the first UE having a higher priority than all the responding UEs that are allocated time resources that overlap with the time resources to be used to send the second message. Aspect 7. The method according to aspect 1, further comprising: Send the cyclic prefix extension (CPE) associated with the second message. Aspect 8. The method according to aspect 7, wherein the CPE is initiated a predetermined amount of time prior to the second message. Aspect 9. The method according to aspect 7, wherein the CPE is initiated at a certain time prior to the second message based on the channel access type. Aspect 10. The method according to aspect 7, wherein the CPE is initiated a certain amount of time before the second message based on a first transmission priority of the second message and a second transmission priority associated with one of the one or more responding UEs. Aspect 11. The method according to aspect 10, wherein the CPE is activated before a second CPE associated with a responding UE having a lower priority than the first UE among the one or more responding UEs and after a third CPE associated with a different responding UE having a higher priority than the first UE among the one or more responding UEs. Aspect 12. According to the method described in aspect 7, The first UE has a higher transmission priority than the highest transmission priority of any of the one or more responding UEs. The CPE is initiated before any CPE associated with any of the one or more responding UEs, based on the transmission priority. Aspect 13. The method according to aspect 7, wherein the CPE is activated for a predetermined amount of time after transmission from one of the one or more responding UEs. Aspect 14. The method according to aspect 7, wherein the CPE is initiated based on the interval between transmissions during the COT, prior to the second message, by a certain amount of time. Aspect 15. The method according to aspect 14, wherein the first UE measures the gap time or receives an indication of the gap time from one of the one or more responding UEs. Aspect 16. A first UE, the first UE comprising: one or more memories; and one or more processors coupled to the one or more memories, the one or more memories storing instructions executable individually or in any combination by the one or more processors, the instructions being configured to cause the first UE to perform the method according to aspects 1 to 15. Aspect 17. A non-transitory computer-readable medium (CRM) having program code recorded thereon, the program code including code for causing a first UE to perform the method according to aspects 1 to 15. Aspect 18. A first UE, the first UE including components for performing the method according to aspects 1 to 15.

[0100] Information and signals can be represented using any of a variety of different techniques and skills. 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 optical particles, or any combination thereof.

[0101] The various exemplary blocks and modules described herein can be implemented or performed using general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternative embodiments, 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 combined with a DSP core, or any other such configuration).

[0102] 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 as one or more instructions or code on or transmitted via a computer-readable medium. Other examples and specific implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described above 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 various portions distributed such that the functions are implemented in different physical locations. Furthermore, as used herein (including in the claims), "or" as used in a list of items (e.g., a list of items followed by such terms as "at least one of" or "one or more of") indicates an inclusive list, such that a list 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).

[0103] As those skilled in the art will understand to date and depending on the specific application at hand, many modifications, substitutions, and variations may be made to the materials, apparatus, configuration, and methods of use of the apparatus 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 aspects illustrated 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 for wireless communication performed by a first user equipment (UE), the method comprising: Perform a channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel. Send COT sharing information (COT-SI) to one or more responding UEs; During the COT, a first message is sent to at least one of the one or more responding UEs; After sending the first message, avoid sending it for a certain duration during the COT period; as well as Based on the conditions, a second message is sent to the second UE after the duration during the COT period.

2. The method of claim 1, wherein the condition includes that the second message is to be transmitted using time and frequency resources that do not overlap with the time and frequency resources allocated to the second UE via the COT-SI.

3. The method of claim 2, wherein the second UE is not one of the one or more responding UEs.

4. The method of claim 2, wherein the second UE is one of the one or more response UEs.

5. The method of claim 1, wherein the condition includes that the second message is to be sent using time resources that do not overlap with the time resources allocated to the second UE.

6. The method of claim 5, wherein the condition further comprises that the first UE has a higher priority than all the responding UEs that have been allocated time resources that overlap with the time resources to be used to send the second message.

7. The method according to claim 1, further comprising: Send the cyclic prefix extension (CPE) associated with the second message.

8. The method of claim 7, wherein the CPE is activated a predetermined amount of time before the second message.

9. The method of claim 7, wherein the CPE is activated a certain amount of time before the second message based on the channel access type.

10. The method of claim 7, wherein the CPE initiates a certain amount of time before the second message based on a first transmission priority of the second message and a second transmission priority associated with one of the one or more responding UEs.

11. The method of claim 10, wherein the CPE is activated before a second CPE associated with a responding UE having a lower priority than the first UE among the one or more responding UEs and after a third CPE associated with a different responding UE having a higher priority than the first UE among the one or more responding UEs.

12. The method according to claim 7, The first UE has a higher transmission priority than the highest transmission priority of any of the one or more responding UEs. The CPE is initiated before any CPE associated with any of the one or more responding UEs, based on the transmission priority.

13. The method of claim 7, wherein the CPE is activated for a predetermined amount of time after transmission from one of the one or more responding UEs.

14. The method of claim 7, wherein the CPE is activated based on the interval between transmissions during the COT, prior to the second message by a certain amount of time.

15. The method of claim 14, wherein the first UE measures the gap time or receives an indication of the gap time from one of the one or more responding UEs.

16. A first user equipment (UE), the first user equipment (UE) comprising: One or more memory units; and One or more processors coupled to one or more memories, the one or more memories storing instructions executable individually or in any combination by the one or more processors, the instructions being configured to cause the first UE to: Perform a channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel. Send COT sharing information (COT-SI) to one or more responding UEs; During the COT, a first message is sent to at least one of the one or more responding UEs; After sending the first message, avoid sending it for a certain duration during the COT period; as well as Based on the conditions, a second message is sent to the second UE after the duration during the COT period.

17. The UE of claim 16, wherein the condition includes that the second message is to be transmitted using time and frequency resources that do not overlap with the time and frequency resources allocated to the second UE via the COT-SI.

18. The UE of claim 17, wherein the second UE is not one of the one or more responding UEs.

19. The UE of claim 17, wherein the second UE is one of the one or more responding UEs.

20. The UE of claim 16, wherein the condition includes that the second message is to be transmitted using time resources that do not overlap with the time resources allocated to the second UE.

21. The UE of claim 20, wherein the condition further includes the first UE having a higher priority than all the responding UEs that have been allocated time resources that overlap with the time resources to be used to send the second message.

22. The UE of claim 16, wherein the one or more processors are further configured to cause the first UE to: Send the cyclic prefix extension (CPE) associated with the second message.

23. The UE of claim 22, wherein the CPE is activated a predetermined amount of time before the second message.

24. The UE of claim 22, wherein the CPE is initiated a certain amount of time prior to the second message based on the channel access type.

25. The UE of claim 22, wherein the CPE initiates a certain amount of time before the second message based on a first transmission priority of the second message and a second transmission priority associated with one of the one or more responding UEs.

26. The UE of claim 25, wherein the CPE is activated before a second CPE associated with a responding UE having a lower priority than the first UE among the one or more responding UEs and after a third CPE associated with a different responding UE having a higher priority than the first UE among the one or more responding UEs.

27. The UE according to claim 22, The first UE has a higher transmission priority than the highest transmission priority of any of the one or more responding UEs. The CPE is initiated before any CPE associated with any of the one or more responding UEs, based on the transmission priority.

28. The UE of claim 22, wherein the CPE is activated for a predetermined amount of time after transmission from one of the one or more responding UEs.

29. A non-transitory computer-readable medium (CRM) having program code recorded thereon, the program code comprising: Code used to enable the first user equipment (UE) to perform a channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel; Code used to cause the first UE to send COT-Signal Information (COT-SI) to one or more responding UEs; Code for causing the first UE to send a first message to at least one of the one or more responding UEs during the COT; Code used to cause the first UE to avoid sending during a certain duration of the COT after sending the first message; and Code for enabling the first UE to send a second message to the second UE after the duration during the COT, based on conditions.

30. A first user equipment (UE), the first user equipment (UE) comprising: A component used to perform the channel access procedure to obtain the channel occupancy time (COT) in the sidelink channel; A component used to send COT-Shared Information (COT-SI) to one or more responding UEs; A component for sending a first message to at least one of the one or more responding UEs during the COT; A component for avoiding transmission for a certain duration during the COT period after the first message has been sent; and A component for sending a second message to a second UE based on conditions during the COT period and after the duration.

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