Channel Occupancy Time (COT) Sharing for Side Links

Abstract

A wireless communication system and method are provided related to Channel Occupancy Time (COT) sharing for sidelink communication. A first User Equipment (UE) receives a first sidelink transmission from a second UE during a first COT, wherein the first COT is associated with the second UE. The first UE determines whether the second UE is one of two or more UEs intending to receive the second sidelink transmission. The first UE transmits the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing. COT sharing is in response to determining that the second UE is one of the two or more UEs intending to receive the second sidelink transmission.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Greek patent application No. 20210100003, filed on January 4, 2021, entitled CHANNEL OCCUPANCY TIME (COT) SHARINGFOR SIDELINK, the entire contents of which are incorporated herein by reference as fully set forth herein and for all applicable purposes. Technical Field

[0003] This application relates to wireless communication systems, and more particularly to channel occupancy time (COT) sharing for sidechain communication.

[0004] introduction

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

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

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

[0008] A brief overview of some examples

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

[0010] For example, in one aspect of this disclosure, a wireless communication method performed by a first user equipment (UE) includes: receiving a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; determining whether the second UE is one of two or more UEs intended to receive a second sidelink transmission; and transmitting the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

[0011] In an additional aspect of this disclosure, a first user equipment (UE) includes a transceiver configured to: receive a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; and a processor coupled to the transceiver, wherein the processor is configured to: determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission; wherein the transceiver is further configured to: transmit the second sidelink transmission to two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of two or more UEs intended to receive the second sidelink transmission.

[0012] In an additional aspect of this disclosure, a non-transient computer-readable medium having program code recorded thereon, the program code including code for causing a first user equipment (UE) to: receive a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; code for causing the first UE to determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission; and code for causing the first UE to transmit the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

[0013] In an additional aspect of this disclosure, a first user equipment (UE) includes: means for receiving a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; means for determining whether the second UE is one of two or more UEs intended to receive the second sidelink transmission; and means for transmitting the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

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

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

[0017] Figure 2 This is a timing diagram illustrating the radio frame structure according to some aspects of this disclosure.

[0018] Figure 3 The present disclosure describes a wireless communication network that provides sidelink communication according to some aspects thereof.

[0019] Figure 4The sidelink communication scheme based on some aspects of this disclosure is explained.

[0020] Figure 5A This is a sequence diagram illustrating a sidelink channel occupancy time (COT) sharing method according to some aspects of this disclosure.

[0021] Figure 5B This is a timing diagram illustrating the side-link COT sharing method based on some aspects of this disclosure.

[0022] Figure 6A This is a sequence diagram illustrating the side-link COT sharing method based on some aspects of this disclosure.

[0023] Figure 6B This is a timing diagram illustrating the side-link COT sharing method based on some aspects of this disclosure.

[0024] Figure 7 This is a flowchart of a sidelink COT sharing method based on some aspects of this disclosure.

[0025] Figure 8A This is a sequence diagram illustrating the side-link COT sharing method based on some aspects of this disclosure.

[0026] Figure 8B This is a timing diagram illustrating the side-link COT sharing method based on some aspects of this disclosure.

[0027] Figure 9 This is a flowchart of a sidelink COT sharing method based on some aspects of this disclosure.

[0028] Figure 10 This is a block diagram of an exemplary base station (BS) according to some aspects of this disclosure.

[0029] Figure 11 This is a block diagram of an exemplary user equipment (UE) according to some aspects of this disclosure.

[0030] Figure 12 This is a flowchart of a wireless communication method according to some aspects of this disclosure.

[0031] Detailed description

[0032] The detailed description that follows, taken in conjunction with the accompanying drawings, is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein can be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0033] This disclosure generally relates 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" may be used interchangeably.

[0034] OFDMA networks can implement radio technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, and flash-OFDM. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunications System (UMTS). Specifically, Long Term Evolution (LTE) is a UMTS version using E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization called the 3rd Generation Partnership Project (3GPP), while cdma2000 is described in documents from an organization called 3rd Generation Partnership Project 2 (3GPP2). These various radio technologies and standards are known or under development. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between various telecommunications association groups that aims to define globally applicable third-generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP project aimed at improving the UMTS mobile phone standard. 3GPP defines specifications for next-generation mobile networks, mobile systems, and mobile devices. This disclosure focuses on the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond, which features shared access to the radio spectrum between networks using new and different sets of radio access technologies or radio air interfaces.

[0035] Specifically, 5G networks envision diverse deployments, diverse spectrum, and diverse services and devices that can be achieved using a unified air interface based on OFDM. To achieve these goals, in addition to developing new radio technologies for 5G NR networks, further enhancements to LTE and LTE-A are also considered. 5G NR will be able to scale to provide coverage for: (1) ultra-high density (e.g., approximately 1 M nodes / km) 2(1) A massive Internet of Things (IoT) with ultra-low complexity (e.g., approximately tens of bits per second), ultra-low energy consumption (e.g., approximately 10+ years of battery life), and deep coverage capable of reaching challenging locations; (2) A large-scale Internet of Things (IoT) with strong security (to protect sensitive personal, financial, or classified information), ultra-high reliability (e.g., approximately 99.9999% reliability), ultra-low latency (e.g., approximately 1 ms), and mission-critical control for users with a wide range of mobility or lack of mobility; and (3) Enhanced mobile broadband, including extremely high capacity (e.g., approximately 10 Tbps / km). 2 Extreme data rates (e.g., multi-Gbps rates, 100+Mbps user experience rates), and deep insights with advanced discovery and optimization.

[0036] 5G NR communication systems can be implemented using optimized OFDM-based waveforms with scalable parameter designs and transmission time intervals (TTIs). Additional features may include a shared, flexible framework for efficiently multiplexing services and features using dynamically low latency Time Division Duplex (TDD) / Frequency Division Duplex (FDD) designs; and the utilization of advanced wireless technologies such as massive MIMO, robust millimeter-wave (mmWave) transmission, advanced channel decoding, and device-centric mobility. The scalability of parameter designs in 5G NR (and the scaling of subcarrier spacing) can efficiently address the operation of diverse services across diverse spectrum and deployments. For example, in various outdoor and macro coverage deployments implemented with FDD / TDD below 3 GHz, subcarrier spacing can occur at 15 kHz over bandwidths (BWs) such as 5, 10, and 20 MHz. For other various outdoor and small-cell coverage deployments with TDD above 3 GHz, subcarrier spacing can occur at 30 kHz over an 80 / 100 MHz BW. For various other indoor broadband implementations, by using TDD in the unlicensed portion of the 5 GHz band, the subcarrier spacing can occur at 60 kHz over a 160 MHz BW. Finally, for various deployments using mmWave components for TDD at 28 GHz, the subcarrier spacing can occur at 120 kHz over a 500 MHz BW.

[0037] 5G NR's scalable parameter design enables scalable TTIs to meet diverse latency and Quality of Service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmissions to begin at symbol boundaries. 5G NR also envisions a self-contained integrated subframe design that incorporates UL / downlink scheduling information, data, and confirmation within the same subframe. Self-contained integrated subframes support communication in unlicensed or contention-based shared spectrum and support adaptive UL / downlink that can be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet current traffic needs.

[0038] Various other aspects and features of this disclosure are further described below. It should be apparent that the teachings herein can be embodied in a variety of forms, and any specific structure, function, or both disclosed herein are merely representative and not limiting. Based on the teachings herein, those skilled in the art will appreciate that the aspects disclosed herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement an apparatus or practice a method. Furthermore, such an apparatus or practice can be implemented using other structures, functionalities, or structures and functionalities that complement or differ from one or more aspects set forth herein. For example, a method can be implemented as part of a system, device, apparatus, and / or as instructions stored on a computer-readable medium for execution on a processor or computer. Moreover, an aspect may include at least one element of the claims.

[0039] Sidelink communication refers to communication between User Equipment (UE) devices without tunneling a Base Station (BS) and / or the core network. Sidelink communication can be transmitted on the Physical Sidelink Control Channel (PSCCH) and the Physical Sidelink Shared Channel (PSSCH). The PSCCH and PSSCH are analogous to the Physical Downlink Control Channel (PDCCH) and Physical Downlink Shared Channel (PDSCH) in downlink (DL) communication between the BS and the UE. For example, the PSCCH may carry Sidelink Control Information (SCI) and the PSSCH may carry sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH may carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. In some implementations, the SCI in the PSCCH may be referred to as SCI Part 1 (SCI-1), and an additional SCI, referred to as SCI Part 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 coding scheme (MCS)). Use cases for sidelink communication may include V2X, enhanced mobile broadband (eMBB), industrial IoT (IIoT), and / or NR-lightweight.

[0040] As used herein, the term "sidelink UE" can refer to a user equipment equipment that performs device-to-device communication or other types of communication with another user equipment equipment independently of any tunneling through a BS (e.g., gNB) and / or associated core network. As used herein, the term "sidelink transmitting UE" can refer to a user equipment equipment performing a sidelink transmission operation. As used herein, the term "sidelink receiving UE" can refer to a user equipment equipment performing a sidelink receiving operation. A sidelink UE may operate as a transmitting sidelink UE at one time and as a receiving sidelink UE at another time.

[0041] As used herein, the terms "synchronous UE," "sidelink synchronous UE," "anchor UE," or "sidelink anchor UE" refer to a sidelink UE that transmits an S-SSB to facilitate sidelink communication between multiple sidelink UEs (e.g., when operating in a self-contained sidelink system), and these terms are interchangeable without departing from the scope of this disclosure. As used herein, the terms "asynchronous UE," "non-anchor UE," or "client" refer to a sidelink UE that relies on an anchor UE to provide sidelink system information. A sidelink UE may operate as an initiating UE at one time and as a responding UE at another time. A sidelink synchronous UE may also operate as a transmitting sidelink UE and / or an initiating UE at one time and as a receiving sidelink UE and / or a responding UE at another time.

[0042] As used herein, the term "initiating UE" can refer to a user equipment that initiates or captures Channel Occupied Time (COT) in a shared radio band (e.g., shared spectrum or unlicensed spectrum) for sidelink communication. For example, an initiating UE may perform Clear Channel Assessment (CCA) or Category 4 (CAT4) Listen-Before-Talk (LBT) in a shared radio band to contend for or capture the COT. Upon passing through the LBT (indicating that the channel is clear for transmission), the initiating UE may transmit a sidelink transmission during the captured COT. As used herein, the term "responding UE" can refer to a user equipment that responds to a sidelink transmission transmitted by any initiating UE. A sidelink UE may operate as an initiating UE at one time and as a responding UE at another time.

[0043] NR supports two Radio Resource Allocation (RRA) modes for sidelinks on licensed spectrum: Mode 1 RRA and Mode 2 RRA. Mode 1 RRA supports network control RRA that can be used for in-coverage sidelink communication. For example, the serving BS (e.g., gNB) can determine radio resources on behalf of the sidelink UE and transmit instructions for those resources to the sidelink UE. In some aspects, the serving BS grants permission for sidelink transmission using downlink control information (DCI). However, significant base station involvement exists in this mode, and it is only operational when the sidelink UE is within the serving BS's coverage area. Mode 2 RRA supports autonomous RRA that can be used for out-of-coverage or partially covered sidelink UEs. For example, the serving BS can configure a sidelink UE (e.g., within its coverage area) to have a sidelink resource pool that can be used for sidelinks when the sidelink UE is not within the serving BS's coverage area. The serving BS can also configure a sidelink UE to operate as a sidelink anchor UE to provide sidelink system information for out-of-coverage sidelink UEs to communicate sidelink communication. For example, a sidelink anchor UE can provide sidelink system information by broadcasting a sidelink synchronization signal block (S-SSB). The S-SSB can be similar to an SSB broadcast by a BS. For example, the S-SSB may include synchronization signals and / or sidelink system information. Some examples of sidelink system information may include a sidelink bandwidth portion (BWP) configuration, one or more sidelink transmit resource pools, and / or one or more sidelink receive resource pools, S-SSB transmission-related parameters (e.g., sidelink time slots configured for S-SSB transmission and / or S-SSB transmission periodicity), and / or any other configuration information related to sidelink communication. In some implementations, the anchor UE may also schedule other sidelink UEs for communication. Therefore, the sidelink anchor UE can operate as a mini gNB that facilitates and / or coordinates communication between sidelink UEs. In 5G NR, a sidelink channel through which two UEs can communicate directly with each other can also be referred to as a PC5 interface.

[0044] Sidelink communication can be in unicast, multicast, or broadcast mode. Additionally, Hybrid Automatic Repeat Request (HARQ) can be applied to unicast or multicast sidelink communication to improve transmission reliability. For unicast communication, a sidelink transmitting UE can transmit a sidelink transmission including data to a single sidelink receiving UE and can request HARQ acknowledgment / negative acknowledgment (ACK / NACK) feedback from that sidelink receiving UE. If the sidelink receiving UE successfully decodes the data from the sidelink transmission, it transmits an ACK. Conversely, if the sidelink receiving UE fails to decode the data from the sidelink transmission, it transmits a NACK. Upon receiving a NACK, the sidelink transmitting UE can retransmit the data. For broadcast communication, a sidelink transmitting UE can transmit a sidelink transmission to a group of sidelink receiving UEs in its neighborhood (e.g., 2, 3, 4, 5, 6, or more) and may not request ACK / NACK feedback for that sidelink transmission.

[0045] Multicast sidelink communication can be connection-based or connectionless. Connection-based multicast sidelink communication is destined for a specific group of UEs; for example, each UE belongs to a group identified by a group identifier (ID) and is known to the sidelinks transmitting to that UE. In this case, the sidelink transmitting UE can request ACK / NACK feedback from each sidelink receiving UE in the group and can also assign different feedback resources to each sidelink receiving UE in the group. For connectionless multicast sidelink communication, the group of UEs capable of receiving the multicast transmission may be unknown to the sidelink transmitting UE. In this case, the sidelink transmitting UE can request NACK-only feedback from UEs that received the multicast sidelink communication (successfully decoding the presence of SCI) but failed to decode the information data from the multicast sidelink communication. In some examples, the sidelink transmitting UE can also assign the same NACK-only feedback resources to all UEs that failed to decode the data.

[0046] 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 (UE) is required to contend for channel access in that spectrum, for example, via Clear Channel Assessment (CCA) and / or Listen-Before-Speak (LBT) procedures.

[0047] 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 signal) is detected in the channel. Additionally, LBT can be in various modes. LBT modes can be, for example, Category 4 (CAT4) LBT, Category 2 (CAT2) LBT, or Category 1 (CAT1) LBT. CAT1 LBT is referred to as 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 the 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 transmitting node can draw a random number and back off for a duration based on the drawn random number in a certain time unit.

[0048] In some aspects, the initiating UE can contend for the COT in the shared radio band by performing CCA or CAT4 LBT. While performing CCA or CAT4 LBT (indicating the channel is open for transmission), the initiating UE can transmit sidelink traffic to the receiving UE during the COT. In some sidelink use cases (e.g., for V2X), sidelink data traffic may include small-size or short data bursts (e.g., informational data of a few bytes to tens of bytes). In some aspects, the duration of the COT may depend on regulations imposed by the modulator of the shared radio band or specific deployment. Therefore, in some instances, sidelink transmissions with small-size data bursts may not occupy the entire duration of the COT. Accordingly, it may be desirable to share the remaining duration of the COT with the receiving UE, rather than leaving the remaining COT unused.

[0049] In NR-U, each UE is served by a serving BS, and COT sharing is supported between the BS and the served UE. For example, the BS can perform CAT4 LBT in a shared channel to contend for the COT. While passing through CAT4 LBT, the BS can transmit DL transmissions to the served UE during a portion of the COT. The BS can allow the served UE to utilize the remaining portion of the COT. In some instances, the BS can schedule the served UE to transmit UL transmissions during the remaining portion of the COT. When the served UE transmits during the BS-initiated COT, the served UE can perform CAT2 LBT or no LBT. CAT2 LBT or no LBT has lower overhead and less uncertainty when accessing the channel. Accordingly, COT sharing provides efficient operation. Similarly, a UE can perform CAT4 LBT in a shared channel to contend for the COT. While passing through CAT4 LBT, the UE can transmit UL transmissions to the serving BS during a portion of the COT (e.g., configured to allow or not allow transmissions). The UE can share the remaining portion of the UE-initiated COT with the serving BS.

[0050] As can be observed, BS-UE COT sharing is based on the transmitting device that initiates or contends for the COT and the receiving or responding device that shares the COT, but is limited to transmissions destined for the transmitting device that initiated the COT. BS-UE COT sharing performs well for communication between the BS and the served UE because BS-UE communication is primarily unicast (e.g., a transmission from a single source to a designated or receiving device). On the other hand, sidelink communication is often multicast (e.g., a transmission from a single source to a group of receivers). Furthermore, a sidelink UE receiving a multicast can sequentially transmit another multicast transmission to multiple sidelink UEs. Thus, COT sharing, limited to sharing between a pair of initiating devices and a single responding device, may not be suitable for sidelink use cases that primarily involve sidelink multicast.

[0051] This application describes a mechanism for sharing the Channel Overhead Transmission (COT) in sidelink multicast and / or broadcast communications. For example, an initiating UE (e.g., a first UE) may contend for the COT in a shared channel by performing a CAT4 LBT. During the CAT4 LBT (indicating the channel is open for transmission), the initiating UE may transmit a first sidelink transmission during a portion of the COT. The first sidelink transmission may be a unicast, multicast, or broadcast transmission. A responding UE (e.g., a second UE) may share the remainder of the COT. In some aspects, if the initiating UE is the intended recipient of a second sidelink transmission, the responding UE may be allowed to utilize the remainder of the COT in multicast mode (e.g., connection-based or connectionless) or broadcast mode for the second sidelink transmission. In this regard, the responding UE may determine whether the initiating UE is one of two or more UEs intended to receive the second sidelink transmission. Connection-based multicast transmissions are destined for a group of UEs known to the responding UE. For example, each UE in the group is assigned a specific group identifier (ID). Connectionless multicast transmissions will be received by a group of UEs unknown to the responding UE. In some instances, connectionless multicast transmissions may be intended for UEs within a specific zone. Therefore, if the second sidelink transmission is in connectionless multicast mode, the responding UE may determine whether the initiating UE is the intended recipient based on zone information associated with it. Zone information may be related to the geographic location of the initiating UE or the physical distance between the initiating UE and the responding UE. In some instances, zones may be pre-configured, and the initiating UE may include zone information (e.g., a zone ID identifying the zone associated with the initiating UE) in the SCI within the first sidelink transmission. If the responding UE determines that the initiating UE is one of two or more UEs intended to receive the second sidelink transmission, the responding UE may transmit the second sidelink transmission to those two or more UEs during the remainder of the COT (shared portion). Then, if the responding UE determines that the initiating UE is not one of two or more UEs intended to receive the second sidelink transmission, the responding UE may suppress the transmission of the second sidelink transmission during the remainder of the COT (shared portion).

[0052] The first sidelink transmission may include an SCI (e.g., SCI-1 or SCI-2) and sidelink data. In some aspects, the SCI may include an indication of whether the first sidelink transmission was transmitted by the UE that initiated the COT, and the responding UE may determine, based on the SCI, whether to transmit a second sidelink transmission within the COT. For example, if the SCI indicates that the first sidelink transmission is from the initiating UE of the COT, the responding UE may share the COT, and if the SCI indicates that the first sidelink transmission is not from the initiating UE of the COT, the responding UE may suppress sharing the COT. In some aspects, the SCI may include a COT-SI, which includes COT sharing information (e.g., the duration of the shared COT) and an indication of whether the first sidelink transmission is from the UE that initiated the COT. In some aspects, the first sidelink transmission is a unicast transmission, and the responding UE may transmit ACK / NACK feedback for the first sidelink transmission to the initiating UE during the COT. In some aspects, the first-sidelink transmission is a connection-based multicast transmission, and the responding UE may transmit ACK / NACK feedback for the first-sidelink transmission to the initiating UE during the COT period. In other aspects, the first-sidelink transmission is a connectionless multicast transmission, and the responding UE may transmit NACK-only feedback for the first-sidelink transmission to the initiating UE during the COT period.

[0053] In some respects, the third UE can receive second-sidelink transmissions during COT. When the second-sidelink transmission is a connection-based multicast, the third UE can transmit ACK / NACK feedback for the second-sidelink transmission. Alternatively, when the second-sidelink transmission is a connectionless multicast, the third UE can transmit NACK-only feedback for the second-sidelink transmission. The third UE can determine whether to transmit ACK / NACK feedback or NACK-only feedback during COT based on whether the third UE detects COT-related COT-sharing information (e.g., transmitted along with the first-sidelink transmission). In this regard, if the third UE detects COT-sharing information, the third UE can transmit ACK / NACK feedback or NACK-only feedback during COT. Then, if the third UE fails to detect COT-sharing information, the third UE can suppress the transmission of ACK / NACK feedback or NACK-only feedback during COT.

[0054] Various aspects of this disclosure can provide several benefits. For example, allowing responding UEs to share a COT used for multicast sidelink transmission (where no LBT or CAT2 LBT is performed prior to the multicast sidelink transmission) can improve sidelink operational efficiency. Constraining COT sharing based on whether the initiating UE is the intended recipient can prevent COT sharing propagation. COT sharing propagation can refer to the initiating UE sharing a COT with a responding UE, and the responding UE further sharing the COT with another UE, which in turn may further share the COT with yet another UE, etc. Although this disclosure is described in the context of COT sharing for sidelink multicast, this disclosure can also be applied to COT sharing for sidelink broadcast.

[0055] Figure 1 A wireless communication network 100 according to some aspects of this disclosure is described. Network 100 may be a 5G network. Network 100 includes several base stations (BSs) 105 (labeled 105a, 105b, 105c, 105d, 105e, and 105f, respectively) and other network entities. BS 105 may be a station communicating with UEs 115 (labeled 115a, 15b, 115c, 115d, 115e, 115f, 115g, 115h, and 115k, respectively), and may also be referred to as an evolved B-node (eNB), a next-generation eNB (gNB), an access point, etc. Each BS 105 may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to that specific geographic coverage area of ​​BS 105 and / or the BS subsystem serving that coverage area, depending on the context in which the term is used.

[0056] BS 105 can provide communication coverage for macrocells or small cells (such as picocells or femtocells), and / or other types of cells. Macrocells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access by UEs with service subscriptions to a network provider. Small cells (such as picocells) typically cover a relatively small geographic area and allow unrestricted access by UEs with service subscriptions to a network provider. Small cells (such as femtocells) also typically cover a relatively small geographic area (e.g., a residential area) and, in addition to unrestricted access, allow restricted access by UEs associated with that femtocell (e.g., UEs in a closed subscriber group (CSG), UEs of users in that residence, etc.). A BS used for macrocells may be referred to as a macro BS. A BS used for small cells may be referred to as a small cell BS, pico BS, femtocell BS, or home BS. Figure 1In the examples shown, BS 105d and 105e can be conventional macro BSs, while BS 105a-105c can be macro BSs with one of three-dimensional (3D), full-dimensional (FD), or massive MIMO enabled. BS 105a-105c can leverage its higher-dimensional MIMO capabilities to increase coverage and capacity using 3D beamforming in both elevation and azimuth beamforming. BS 105f can be a small cell BS, which can be a home node or a portable access point. BS 105 can support one or more (e.g., two, three, four, etc.) cells.

[0057] Network 100 can support synchronous or asynchronous operation. For synchronous operation, each BS can have similar frame timing, and transmissions from different BSs can be roughly aligned in time. For asynchronous operation, each BS can have different frame timing, and transmissions from different BSs may not be aligned in time.

[0058] Each UE 115 is distributed throughout the wireless network 100, and each UE 115 may be stationary or mobile. UE 115 may also be referred to as a terminal, mobile station, subscriber unit, station, etc. UE 115 may be a cellular phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, tablet computer, laptop computer, cordless phone, wireless local loop (WLL) station, etc. In one aspect, UE 115 may be a device including a Universal Integrated Circuit Card (UICC). In another aspect, UE may be a device without a UICC. In some aspects, UE 115 without a UICC may also be referred to as an IoT device or an Internet of Things (IoE) device. UE 115a-115d are examples of mobile smartphone-type devices accessing network 100. UE 115 may also be a machine specifically configured for connected communications (including Machine Type Communication (MTC), Enhanced MTC (eMTC), Narrowband IoT (NB-IoT), etc.). UE 115e-115h are examples of various machines configured for communication within access network 100. UE 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication within access network 100. UE 115 can communicate with any type of BS (whether macro BS, small cell, etc.). Figure 1 In this context, the lightning bolt (e.g., a communication link) indicates radio transmissions between UE 115 and serving BS 105, desired transmissions between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UE 115, where serving BS 105 is the BS designated to serve UE 115 on the downlink (DL) and / or uplink (UL).

[0059] In operation, BS 105a-105c can use 3D beamforming and coordinated spatial technologies (such as Coordinated Multipoint (CoMP) or multi-connectivity) to serve UE 115a and 115b. Macro BS 105d can perform backhaul communication with BS 105a-105c and small cell BS 105f. Macro BS 105d can also deliver multicast services subscribed to and received by UE 115c and 115d. Such multicast services may include mobile TV or streaming video, or may include other services for providing community information (such as weather emergencies or alerts, such as Amber Alerts or Grey Alerts).

[0060] BS 105 can also communicate with the core network. The core network provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some BS 105s (e.g., examples of gNBs or Access Node Controllers (ANCs)) can interface with the core network via backhaul links (e.g., NG-C, NG-U, etc.) and can perform radio configuration and scheduling for communication with UE 115. In various examples, BS 105s can communicate with each other directly or indirectly (e.g., via the core network) on backhaul links (e.g., X1, X2, etc.), which can be wired or wireless communication links.

[0061] Network 100 can also support mission-critical communication with highly reliable and redundant links for mission-critical equipment 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 be in a multi-step configuration by communicating with another user equipment relaying its information to the network (e.g., UE 115f relays temperature measurement information to smart meter UE 115g, which is then reported to the network via small cell BS 105f). Network 100 can also provide additional network efficiency through dynamic, low latency TDD / FDD communication, such as V2V, V2X, C-V2X communication between UE 115i, 115j or 115k and other UE 115, and / or vehicle-to-infrastructure (V2I) communication between UE 115i, 115j or 115k and BS 105.

[0062] In some implementations, network 100 utilizes OFDM-based waveforms for communication. OFDM-based systems can divide the system BW into multiple (K) orthogonal subcarriers, which are often referred to as subcarriers, frequency modulation, frequency slots, etc. Each subcarrier can be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system BW. The system BW can also be divided into subbands. In other instances, the subcarrier spacing and / or the duration of the time interval (TTI) can be scalable.

[0063] In some respects, BS 105 may assign or schedule (e.g., in the form of time-frequency resource blocks (RBs)) transmission resources for downlink (DL) and uplink (UL) transmissions in network 100. DL refers to the transmission direction from BS 105 to UE 115, while UL refers to the transmission direction from UE 115 to BS 105. Communication may take the form of radio frames. Radio frames may be divided into multiple subframes or time slots, for example, about 10. Each time slot may be further divided into sub-time slots. In FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. In TDD mode, UL and DL transmissions occur using the same frequency band but at different time periods. For example, a subset of subframes in a radio frame (e.g., DL subframes) may be used for DL ​​transmissions, and another subset of subframes in a radio frame (e.g., UL subframes) may be used for UL transmissions.

[0064] DL subframes and UL subframes can be further divided into several regions. For example, each DL or UL subframe may have a predefined region for the transmission of reference signals, control information, and data. Reference signals are predetermined signals that facilitate communication between BS 105 and UE 115. For example, reference signals may have a specific pilot pattern or structure, wherein the pilot frequencies may span the operating BW or frequency band, and each pilot frequency is positioned at a predefined time and predefined frequency. For example, BS 105 may transmit a cell-specific reference signal (CRS) and / or channel state information-reference signal (CSI-RS) to enable UE 115 to estimate the DL channel. Similarly, UE 115 may transmit a probe reference signal (SRS) to enable BS 105 to estimate the UL channel. Control information may include resource allocation and protocol control. Data may include protocol data and / or operational data. In some aspects, BS 105 and UE 115 may communicate using self-contained subframes. Self-contained subframes may include portions for DL ​​communication and portions for UL communication. Self-contained subframes can be DL-centered or UL-centered. DL-centered subframes can include a duration for DL ​​communication that is longer than the duration for UL communication. UL-centered subframes can include a duration for UL communication that is longer than the duration for DL ​​communication.

[0065] In some respects, network 100 may be an NR network deployed on licensed spectrum. BS 105 may transmit synchronization signals (e.g., including primary synchronization signal (PSS) and secondary synchronization signal (SSS)) within network 100 to facilitate synchronization. BS 105 may broadcast system information associated with network 100 (e.g., including primary information block (MIB), residual system information (RMSI), and other system information (OSI)) to facilitate initial network access. In some instances, BS 105 may broadcast PSS, SSS, and / or MIB in the form of synchronization signal block (SSB) on the physical broadcast channel (PBCH) and may broadcast RMSI and / or OSI on the physical downlink shared channel (PDSCH).

[0066] In some respects, UE 115 attempting to access network 100 can perform an initial cell search by detecting a PSS from BS 105. The PSS enables time-period synchronization and indicates a physical layer identity value. UE 115 can subsequently receive an SSS. The SSS enables radio frame synchronization and provides a cell identity value, which can be combined with a physical layer identity value to identify the cell. The PSS and SSS can be located in the center portion of the carrier or at any suitable frequency within the carrier.

[0067] 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) protocol, 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.

[0068] After obtaining the MIB, RMSI, and / or OSI, UE 115 can execute a random access procedure to establish a connection with BS 105. In some examples, the random access procedure can be a four-step random access procedure. For example, UE 115 can transmit a random access preamble, and BS 105 can respond with a random access response. The random access response (RAR) may include the detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, UL grant, temporary cell radio network temporary identifier (C-RNTI), and / or backoff indicator. Upon receiving the random access response, UE 115 can transmit a connection request to BS 105, and BS 105 can respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, RAR, connection request, and connection response may be referred to as message 1 (MSG 1), message 2 (MSG 2), message 3 (MSG 3), and message 4 (MSG 4), respectively. In some examples, the random access procedure can be a two-step random access procedure, where UE 115 can transmit the random access preamble and connection request in a single transmission, and BS 105 can respond by transmitting the random access response and connection response in a single transmission. 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).

[0069] After the connection is established, UE 115 and BS 105 can enter the normal operation phase, where operational data can be exchanged. For example, BS 105 can schedule UE 115 for UL and / or DL ​​communication. BS 105 can transmit UL and / or DL ​​scheduling permission to UE 115 via PDCCH. BS 105 can transmit DL communication signals to UE 115 via PDSCH based on DL scheduling permission. UE 115 can transmit UL communication signals to BS 105 via PUSCH and / or PUCCH based on UL scheduling permission. This connection can be referred to as an RRC connection. When UE 115 actively exchanges data with BS 105, UE 115 is in an RRC connected state.

[0070] In one example, after establishing a connection with BS 105, UE 115 can initiate an initial network attachment 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 attachment procedure. For example, BS 105 can coordinate with network entities in the 5GC to identify the UE, authenticate the UE, and / or authorize the UE to send and / or receive data in network 100. Furthermore, the AMF can assign a set of Tracking Areas (TAs) to the UE. Once the network attachment procedure is successful, a context is established for UE 115 in the AMF. After successfully attaching to the network, UE 115 can move around its 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 may report only its location to network 100 when a new TA is entered. TAU allows network 100 to quickly locate and page UE 115 upon receiving an input data packet or a call to UE 115.

[0071] In some respects, BS 105 can use Hybrid Automatic Repeat Request (HARQ) technology to communicate with UE 115 to improve communication reliability, such as to provide URLLC services. BS 105 can schedule UE 115 for PDSCH communication by transmitting DL permission in the PDCCH. BS 105 can transmit DL data packets to UE 115 according to the scheduling in the PDSCH. DL data packets can be transmitted in transport blocks (TBs). If UE 115 successfully decodes the DL data packets, UE 115 can transmit a HARQ ACK to BS 105. Conversely, if UE 115 fails to successfully decode the DL transmission, UE 115 can transmit a HARQ NACK to BS 105. Once a HARQ NACK is received from UE 115, BS 105 retransmits the DL data packets to UE 115. The retransmission may include the same encoded version of the DL data as the initial transmission. Alternatively, the retransmission may include a different encoded 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 retransmissions for decoding. BS 105 and UE 115 can also use a mechanism substantially similar to DL HARQ to apply HARQ to UL communications.

[0072] In some aspects, network 100 may operate on a system BW or a component carrier (CC) BW. Network 100 may divide the system BW into multiple BWPs (e.g., multiple parts). BS 105 may dynamically assign UE 115 to operate on a particular BWP (e.g., a part of the system BW). The assigned BWP may be referred to as the active BWP. UE 115 may monitor the active BWP to look for signaling information from BS 105. BS 105 may schedule UE 115 to perform UL or DL ​​communication in the active BWP. In some aspects, BS 105 may assign a pair of BWPs within a CC to UE 115 for UL and DL communication. For example, the BWP pair may include one BWP for UL communication and one BWP for DL ​​communication.

[0073] In some aspects, network 100 may operate on a shared channel, which may include a shared frequency band or an unlicensed frequency band. For example, network 100 may be an NR unlicensed (NR-U) network operating on an unlicensed frequency band. In such aspects, BS 105 and UE 115 may be operated by multiple network operating entities. To avoid collisions, BS 105 and UE 115 may employ a LBT procedure to monitor transmission opportunities (TXOP) in the shared channel. The wireless communication device may perform LBT in the shared channel. LBT is a channel access scheme that can be used in unlicensed spectrum. When the LBT result is LBT pass (the wireless communication device wins the contention for the wireless medium), the wireless communication device may access the shared medium to transmit and / or receive data. For example, a transmitting node (e.g., BS 105 or UE 115) may perform LBT before transmitting in the channel. When LBT pass, the transmitting node may then transmit. When LBT fail, the transmitting node may suppress transmission in the channel. In one example, LBT may be based on energy detection. For example, when the signal energy measured from the channel is below a threshold, the LBT result is a pass. Conversely, when the signal energy measured from the channel exceeds the threshold, the LBT result is a failure. In another example, LBT can be based on signal detection. For example, when no channel reservation signal (e.g., a predefined preamble signal) is detected in the channel, the LBT result is a pass. Conversely, when a channel reservation signal is detected in the channel, the LBT result is a failure. TXOP can also be referred to as Channel Occupancy Time (COT).

[0074] In some respects, network 100 can provide sidelink communication to allow UE 115 to communicate with another UE 115 without tunneling through BS 105 and / or the core network, such as... Figure 2As shown above, sidelink communication can occur on the PSCCH and PSSCH. For example, the PSCCH may carry an SCI and the PSSCH may carry an SCI and / or sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH may carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. In some examples, the transmitting sidelink UE 115 may indicate the SCI in two phases. In the first phase SCI (which may be referred to as SCI-1), the UE 115 may transmit an SCI in the PSCCH carrying information for resource allocation and decoding of the second phase SCI. The first phase SCI may include at least one of the following: priority, PSSCH resource assignment, resource reservation period (if enabled), PSSCH DMRS mode (if more than one mode is configured), second phase SCI format (e.g., the size of the second phase SCI), amount of resources for the second phase SCI, number of PSSCH demodulation reference signal (DMRS) ports, modulation and coding 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 Resource ID, a HARQ Procedure ID, a New Data Indicator (NDI), a Redundancy Version (RV), etc. It should be understood that these are examples, and the first-stage SCI and / or the second-stage SCI may include or indicate additional or different information than those provided in the examples. Sidelink communication may also be transmitted on the Physical Sidelink Feedback Control Channel (PSFCH), which indicates ACK-NACK for previously transmitted PSSCHs.

[0075] In some aspects, BS 105 can configure UE 115 to operate as a sidelink synchronizing or anchor UE 115 to provide sidelink system information to other sidelink UEs 115 that may be outside the coverage area of ​​BS 105 to communicate sidelink communications. The sidelink synchronizing UE 115 can transmit sidelink system information in the form of an S-SSB. The S-SSB may include synchronization signals (e.g., PSS and / or SSS) and sidelink system information, such as sidelink BWP configuration, one or more sidelink transmit resource pools and / or one or more sidelink receive resource pools, S-SSB transmission-related parameters (e.g., sidelink time slots configured for S-SSB transmission and / or S-SSB transmission periods) and / or any other configuration information related to sidelink communications. In some aspects, BS 105 can configure the sidelink synchronizing UE 115 to transmit an S-SSB according to a synchronization grating defined for NR-U. In some instances, the S-SSB according to the NR-U synchronization grating may be offset from the lowest frequency of the corresponding sidelink BWP transmitting the S-SSB. In other aspects, the BS 105 can transmit the S-SSB according to a synchronization grating defined for the sidelink. The sidelink synchronization grating can be defined such that the S-SSB can be aligned with the lowest frequency of the corresponding sidelink BWP transmitting the S-SSB.

[0076] 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 may transmit sidelink transmissions to a group of sidelink receiving UEs 115 (e.g., 2, 3, 4, 5, 6 or more) in the neighborhood of the sidelink transmitting UE 115, and may not request ACK / NACK feedback for the sidelink transmission.

[0077] 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 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 NACK-only feedback from the sidelink receiving UE 115. 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. In some instances, the sidelink receiving UE 115 may be assigned the same resources used for transmitting NACK feedback. Synchronous NACK transmissions from multiple sidelink receiving UEs 115 within 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 upon receiving a NACK for connection-based or connectionless multicast transmission.

[0078] According to various aspects of this disclosure, an initiating UE 115 (e.g., a first UE) may contend for the COT in a shared channel by performing CAT4 LBT. During CAT4 LBT (indicating the channel is open for transmission), the initiating UE 115 may transmit a first sidelink transmission during a portion of the COT. The first sidelink transmission may be a unicast, multicast, or broadcast transmission. A responding UE 115 (e.g., a second UE) of the first sidelink transmission may share the remainder of the COT. In some aspects, if the initiating UE 115 is the intended recipient of a second sidelink transmission, the responding UE 115 may be permitted to utilize the remainder of the COT in multicast mode (e.g., connection-based or connectionless) or broadcast mode for the second sidelink transmission. In this regard, the responding UE 115 may determine whether the initiating UE 115 is one of two or more UEs 115 intended to receive the second sidelink transmission. If the second sidelink transmission is in connectionless multicast mode, the responding UE 115 may determine whether the initiating UE 115 is the intended recipient based on zoning information associated with the initiating UE 115. Zoning information may be related to the geographic location of the initiating UE 115 or the physical distance between the initiating UE 115 and the responding UE 115. In some instances, the zoning may be pre-configured, and the initiating UE 115 may include zoning information (e.g., a zoning ID identifying the zoning associated with the initiating UE 115) in the SCI within the first sidelink transmission. In some instances, the zoning information is part of the second-stage SCI of the first sidelink transmission. If the responding UE 115 determines that the initiating UE 115 is one of two or more UEs 115 intended to receive the second sidelink transmission, the responding UE 115 may transmit the second sidelink transmission to those two or more UEs during the remainder of the COT (shared portion). Then, if the responding UE 115 determines that the initiating UE 115 is not one of two or more UE 115s intended to receive the second sidelink transmission, the responding UE 115 may suppress the transmission of the second sidelink transmission during the remainder of the COT (shared portion).

[0079] The first sidelink transmission may include an SCI (e.g., SCI-1 or SCI-2) and sidelink data. In some aspects, the SCI may include an indication of whether the first sidelink transmission originates from the UE 115 initiating the COT, and the responding UE 115 may determine whether to transmit a second sidelink transmission in the COT based on the SCI indicating that the first sidelink transmission was transmitted by the initiating UE of the COT. In some aspects, the SCI may include a COT-SI, which includes COT sharing information (e.g., the duration of the shared COT) and an indication of whether the first sidelink transmission originates from the initiating UE 115 of the COT. In some aspects, the first sidelink transmission is a unicast transmission, and the responding UE 115 may transmit ACK / NACK feedback to the initiating UE 115 during the COT. In some aspects, the first sidelink transmission is a connection-based multicast transmission, and the responding UE 115 may transmit ACK / NACK feedback to the initiating UE 115 during the COT. In some respects, the first-side-link transmission is a connectionless multicast transmission, and the responding UE115 can send a NACK-only feedback to the initiating UE115 during COT.

[0080] In some aspects, the receiving UE 115 (e.g., a third UE) of the second sidelink transmission may also transmit ACK / NACK feedback for the second sidelink transmission (e.g., when the second sidelink transmission is connection-based multicast) or NACK-only feedback for the second sidelink transmission (e.g., when the second sidelink transmission is connectionless multicast). The third UE may determine whether to transmit ACK / NACK feedback or NACK-only feedback during the COT period based on whether the third UE detects COT sharing information of the first sidelink transmission. In this regard, if the third UE detects COT sharing information of the first sidelink transmission, the third UE may transmit ACK / NACK feedback or NACK-only feedback during the COT period. Then, if the third UE fails to detect COT sharing information of the first sidelink transmission, the third UE may suppress the transmission of ACK / NACK feedback or NACK-only feedback during the COT period. The mechanism for COT sharing for sidelink communication (e.g., in multicast or broadcast mode) is described in more detail herein.

[0081] 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 adopted by a BS (such as BS 105) and a UE (such as UE 115) in a network (such as network 100) for communication. In particular, the BS can use time-frequency resources configured as shown in the radio frame structure 200 to communicate with the UE. Figure 2In this diagram, the x-axis represents time in some arbitrary unit, while 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 10 milliseconds. The radio frame 201 includes a number of M time slots 202, where M can be any suitable positive integer. In one example, M can be approximately 10.

[0082] Each time slot 202 includes several subcarriers 204 in frequency and several symbols 206 in time. The number of subcarriers 204 and / or symbols 206 in time slot 202 may vary depending on various factors, such as channel bandwidth, subcarrier spacing (SCS), and / or CP mode. A subcarrier 204 in frequency form and a symbol 206 in time form form a resource element (RE) 212 for transmission. A resource block (RB) 210 is formed from several consecutive subcarriers 204 in frequency and several consecutive symbols 206 in time.

[0083] 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 mini time slot 208 (e.g., Figure 1 UE 115 in the BS performs UL and / or DL ​​communication. Each time slot 202 can be time-divided into K mini-time slots 208. Each mini-time slot 208 may include one or more symbols 206. The mini-time slots 208 in the time slot 202 may have variable lengths. For example, when the time slot 202 includes N symbols 206, the mini-time slot 208 may have a length between 1 symbol 206 and (N-1) symbols 206. In some aspects, the mini-time slot 208 may have a length of about two symbols 206, about four symbols 206, or about seven symbols 206. In some examples, the BS may schedule the UE at the frequency granularity of resource blocks (RBs) 210 (e.g., including about 12 subcarriers 204 of 1 symbol, 2 symbols, ..., 14 symbols). In some aspects, the UE (e.g., Figure 1 UE 115i) can communicate with another UE (e.g., in time slots similar to time slot 202) in units similar to time slot 202. Figure 1 The UE 115j) will conduct sidelink communication, which will be discussed in the following... Figure 4 Further details are provided below.

[0084] Figure 3 An example of a wireless communication network 300 providing sidelink communication according to various aspects of this disclosure has been explained. 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 3The 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). The BS 305 and UEs 315 may be similar to BS 105 and UE 115, respectively. The BS 305 and UEs 315 may share the same radio frequency band for communication. In some instances, the radio frequency band may be a licensed band. In some instances, the radio frequency band may be an unlicensed band. In some instances, the radio frequency band may be a frequency range 1 (FR1) band. In some instances, the radio frequency band may be an FR2 band. Generally, the radio frequency band may be at any suitable frequency.

[0085] In network 300, some UEs 315 can communicate with each other in peer-to-peer communication. For example, UE 315a can communicate with UE 315b on side link 351, UE 315c can communicate with UE 315d on side link 352 and / or with UE 315e on side link 354, and UE 315d can communicate with UE 315e on 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.

[0086] Some UEs 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 relay for UE 315d to reach BS 305. In some aspects, some UEs 315 are associated with vehicles (e.g., similar to UE 115i-k), and communication on side links 351 and / or 352 may be C-V2X communication. C-V2X communication can refer to communication between a vehicle and any other wireless communication device in the cellular network.

[0087] In some respects, BS 305 can configure sidelink UE 315 to operate as a sidelink anchor UE (e.g., UE 315c). When operating as a sidelink synchronization UE, UE 315 can broadcast an S-SSB, which may include synchronization signals (e.g., PSS and / or SSS) and sidelink system information, such as sidelink BWP configuration, one or more sidelink transmit resource pools, and / or one or more sidelink receive resource pools, S-SSB transmission-related parameters (e.g., sidelink time slots configured for S-SSB transmission and / or S-SSB transmission cycles) and / or any other configuration information related to sidelink communication. Accordingly, other UEs near UE 315c but possibly outside the coverage area of ​​BS 305 (e.g., UEs 315d and 315e) can listen to and synchronize with the S-SSB and communicate with each other based on the S-SSB. Other UEs 315d and 315e that receive sidelink system information from UE 315c can be referred to as client UEs.

[0088] Figure 4 A sidelink communication scheme 400 according to some aspects of this disclosure is explained. Scheme 400 can be adopted by UEs (such as UEs 115 and 315) in a network (such as network 100 and / or 300) for sidelink communication. Figure 4 As shown, the first UE 402a can communicate with the second UE 402b (and one or more other UEs 402) via one or more sidelink channels 410. UEs 402 and 402b can use one or more sidelink channels 410 to communicate for P2P communication, D2D communication, V2X communication (e.g., may include V2V communication, V2I communication, V2P communication, etc.), mesh networking, etc. In some aspects, UE 402 (e.g., UE 402a and / or UE 402b) may correspond to one or more other UEs described elsewhere herein, such as UE 115 and / or 315. In some aspects, one or more sidelink channels 410 may use a PC5 interface and / or may operate in a high-frequency band (e.g., about 4 GHz, 5 GHz, 6 GHz, or millimeter-wave band). Additionally or alternatively, UE 402 may use Global Navigation Satellite System (GNSS) timing to synchronize the timing of transmission time intervals (TTIs) (e.g., frames, subframes, time slots, symbols, etc.).

[0089] like Figure 4As further shown, one or more sidelink channels 410 may include PSCCH 415, PSSCH 420, and / or PSFCH 425. PSCCH 415 may be used to convey control information, similar to PDCCH and / or PUCCH used for cellular communication with base station 110 via an access link or access channel. PSCCH 420 may be used to convey data, similar to PDSCH and / or PUSCH used for cellular communication with base station 110 via an access link or access channel. In some aspects, PSCCH 415 may carry SCI 430, which may indicate various control information used for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, spatial resources, etc.), wherein a transport block (TB) 435 may be carried on PSSCH 420. TB 435 may include data. PSFCH 425 may be used to convey sidelink feedback 440, such as HARQ feedback (e.g., ACK / NACK information), transmit power control (TPC), scheduling request (SR), etc. In some respects, SCI 430 in PSCCH 415 may include a first-stage SCI (e.g., resource information), and PSSCH 420 may carry a second-stage SCI (e.g., transmission parameters (such as MCS) used to transmit data 435).

[0090] In some aspects, one or more sidelink channels 410 may use resources from a sidelink resource pool. A sidelink resource pool may refer to a set of time resources (including multiple symbols similar to symbol 206 or multiple time slots similar to time slot 202) and frequency resources (including multiple subcarriers similar to subcarrier 204 or multiple RBs similar to RB 210) that can be used for sidelink transmission. In some aspects, specific RBs spanning time may be used to transmit scheduling assignments in a subchannel (e.g., included in SCI 430). In some aspects, data transmissions associated with a scheduling assignment (e.g., on PSSCH 420) may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, scheduling assignments and associated data transmissions are not transmitted on adjacent RBs.

[0091] In some aspects, UE 402 may operate using a transmission mode in which resource selection and / or scheduling is performed by UE 402 (e.g., instead of base station 105 or 305). In some aspects, UE 402 may perform resource selection and / or scheduling by sensing channel availability for transmission. In some aspects, UE 402 may measure Received Signal Strength Indicator (RSSI) parameters (e.g., sidelink-RSSI (S-RSSI) parameters) associated with various sidelink channels; may measure Reference Signal Received Power (RSRP) parameters (e.g., PSSCH-RSRP parameters) associated with various sidelink channels; may measure Reference Signal Received Quality (RSRQ) parameters (e.g., PSSCH-RSRQ parameters) associated with various sidelink channels, etc.; and may select channels for transmitting sidelink communications based at least in part on (these) measurements.

[0092] Alternatively or additionally, UE 402 may use the SCI 430 received in PSCCH 415 (which may indicate the resources used, channel parameters, etc.) to perform resource selection and / or scheduling. Alternatively or additionally, UE 402 may perform resource selection and / or scheduling by determining the Channel Busy Rate (CBR) associated with various sidelink channels, which may be used for rate control (e.g., by indicating the maximum number of resource blocks available to UE 402 for a particular subframe set).

[0093] In a transmission mode where resource selection and / or scheduling is performed by UE 402, UE 402 may generate sidelink grants, and these grants may be transmitted in SCI 430. In some aspects, sidelink grants may indicate one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks (e.g., for TB 435) to be used for an upcoming sidelink transmission on PSSCH 420, one or more subframes to be used for an upcoming sidelink transmission, modulation and coding scheme (MCS) to be used for an upcoming sidelink transmission, etc. In some aspects, UE 402 may generate sidelink grants indicating one or more parameters for semi-persistent scheduling (SPS), such as the periodicity of the sidelink transmission. Additionally or alternatively, UE 402 may generate sidelink grants for event-driven scheduling (such as for on-demand sidelink messages).

[0094] PSFCH resources may come from a sidelink resource pool. A time slot for PSFCH transmission may exist within the resource pool. In some aspects, the sidelink resource pool may include multiple time slots, and PSFCH resources may be allocated in each, two, or four time slots. In some aspects, within a time slot that includes PSFCH, the PSFCH resources may be located after the PSFCH and the minimum time interval (e.g., approximately one symbol) used for PSFCH.

[0095] As indicated above, Figure 4 It is provided as one aspect. Other aspects may differ from those concerning... Figure 4 The aspects described. Although Figure 4 It is explained for use in P2P or unicast sidelink communication, but it should be understood that in other examples, similar mechanisms can be used for sidelink multicast, where data 435 can be addressed to multiple sidelink UEs similar to UE 402b.

[0096] Discussing each other in relation to each other Figure 5A and 5B This explains COT sharing used for sidelink multicast. Figure 5A This is a sequence diagram illustrating a sidelink COT sharing method 500 according to some aspects of this disclosure. Method 500 can be implemented among UEs 502a, UE 502b, UE 502c, and UE 502d operating on a shared radio frequency band (e.g., in a shared spectrum or unlicensed spectrum). UEs 502a-d can be similar to UEs 115, 315, and / or 402. Figure 5B This is a timing diagram 520 illustrating the side-link COT sharing method 500 based on some aspects of this disclosure. Figure 5B In this context, the x-axis represents time in some arbitrary units.

[0097] In action 510, UE 502a (e.g., the initiating UE) performs CAT4LBT (in the shared channel) Figure 5B (shown as 522) Initiating COT (in the shared radio band) Figure 5B (This is shown as 524). For example, CAT4 LBT 522 is successful (indicating that the channel is clear for transmission), as shown by the checkmark.

[0098] In action 512, during the passage of CAT4 LBT, UE 502a transmits sidelink transmission A during part 506 of COT 524 (in Figure 5B (Illustrated as 530). Sidelink transmission A may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding Figure 4The sidelink transmission A discussed herein is a multicast transmission intended to be received by, for example, UE 502b and UE 502c, as indicated by the two arrows in the dashed elliptical grouping. UE 502b and UE 502c (e.g., responding UEs) may receive sidelink transmission A.

[0099] In some aspects, sidelink transmission A can be a connection-based multicast transmission, and the SCI can include a group identifier (ID) identifying the group to which UE 502b and UE 502c belong. Accordingly, UE 502b and UE 502c can receive sidelink transmission A based on the SCI indicating the group ID. In some aspects, sidelink transmission A can be a connectionless multicast transmission and UE, and can be intended for UEs within a certain zone, rather than based on the group ID. For example, UE 502b and UE 502c can be within a certain zone (a geographical area or a physical distance range from UE 502a), and therefore can receive sidelink transmission A. In some instances, zones can be pre-configured, and UE 502b and UE 502c can receive zone information (e.g., a zone ID identifying the zone associated with UE 502a) in the SCI within sidelink transmission A. In some respects, sidelink transmission A can be a broadcast transmission, and any UE in the neighborhood of UE 502a, including UE 502b and UE 502c, can receive sidelink transmission A.

[0100] Sidechain transmission A may include COT shared information. For example... Figure 5B As shown, sidelink transmission A includes indicator 532. Indicator 532 indicates whether sidelink transmission A 530 is transmitted by the initiating node (COT 524) or the responding node. In some aspects, indicator 532 may have a length of 1 bit, where a bit value of 1 indicates the initiating node and a bit value of 0 indicates the responding node, and vice versa. In some aspects, indicator 532 may be part of a first-stage SCI or a second-stage SCI. In some aspects, indicator 532 may be part of a COT-SI. For example, COT-SI may include a bit map, and indicator 532 may correspond to bits within that bit map. In some cases, COT-SI may indicate other information associated with COT 524 (e.g., the duration of COT 524 for sharing, such as...). Figure 5B Part 508 shown.

[0101] In some respects, if the UE that initiated the COT is the intended recipient of the multicast transmission, the responding UE may be permitted to transmit the multicast transmission in the shared portion of the COT. For example, after UE 502b receives sidelink transmission A, UE 502b may expect to transmit sidelink transmission B in multicast mode. Therefore, UE 502b can determine whether the initiating UE 502a is the intended recipient of sidelink transmission B. In action 514, based on the fact that the initiating UE 502a is the intended recipient of sidelink transmission B 540, UE 502b transmits sidelink transmission B in multicast mode (as shown by the two arrows grouped by the dashed arrows) to UE 502a and UE 502c during the shared portion 508 of COT 524. Figure 5B (Illustrated as 540). Sidelink transmission B540 may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding Figure 4 The discussion focuses on the fact that, in some respects, the partially shared portion 508 may be separated from the portion 506 (the non-shared portion), or may begin at a symbol within COT 524.

[0102] In some aspects, UE 502b may perform CAT2 LBT before transmitting sidelink transmission B in shared COT 524. In other aspects, UE 502b may transmit sidelink transmission B in shared COT 524 without performing LBT before that transmission. Accordingly, COT sharing can reduce LBT overhead and / or channel access uncertainty, and thus provide efficient sidelink communication. In some aspects, UE 502b may determine whether to perform no LBT or perform CAT2 LBT before transmitting sidelink transmission B in shared COT 524 based on the interval duration between sidelink transmission B and the previous transmission in COT. For example, when the interval is short (e.g., shorter than a duration threshold), UE 502b may transmit sidelink transmission B without performing LBT.

[0103] In some respects, UE 502b may also expect to transmit the sidelink transmission C to UE 502d in unicast mode. UE 502b can determine that the initiating UE 502a is not the intended recipient of the sidelink transmission C, and therefore may not transmit the sidelink transmission C in the shared portion 508 of COT 524. In action 516, as Figure 5A Arrows with the symbol "X" and Figure 5BAs shown in the dashed box C with the symbol "X", UE 502b suppresses the transmission of sidelink transmission C to UE 502d during COT 524. To transmit sidelink transmission C, UE 502b can perform CAT4 LBT 552 in the shared channel to contend for COT 554, and transmit sidelink transmission C560 during CAT4 LBT 552 (with checksum flag), as... Figure 5B As shown, the sidelink transmission C560 may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding... Figure 4 The subject of discussion.

[0104] Discussing each other in relation to each other Figure 6A and 6B This explains COT sharing used for sidelink multicast. Figure 6A This is a sequence diagram illustrating a sidelink COT sharing method 600 according to some aspects of this disclosure. Method 600 can be implemented among UEs 502a, UE 502b, UE 502c, and UE 502d operating on a shared radio frequency band (e.g., in a shared spectrum or unlicensed spectrum). UEs 502a-d can be similar to UEs 115 and / or 315. Figure 6B This is a timing diagram 620 illustrating the side-link COT sharing method 600 based on some aspects of this disclosure. Figure 6B In this context, the x-axis represents time in some arbitrary unit. Method 600 is essentially similar to the above regarding... Figure 5A and 5B Method 500 is discussed in the present paper. However, in method 600, the responder UE 502c of the sidelink transmission B may expect to transmit the sidelink transmission D in multicast mode after receiving the sidelink transmission B.

[0105] As discussed above, in action 514, UE 502b, as the initiator of COT 524, UE 502a is the intended recipient of sidelink transmission B 540 and transmits sidelink transmission B 540 during the shared portion 508 of COT 524.

[0106] In some respects, if a sidelink transmission is delivered by a UE that initiated a COT, then a UE receiving the sidelink transmission in that COT can transmit it within the shared portion of that COT. For example, after receiving sidelink transmission B from UE 502b, UE 502b may expect to transmit sidelink transmission D in multicast mode and may determine whether sidelink transmission D can be transmitted during COT 524. UE 502b may determine whether UE 502b is the initiating UE of COT 524.

[0107] To assist the responding UE in determining whether COT 524 can be shared in the sidelink transmission B 540, UE 502b may include indicator 642 in the sidelink transmission B 540, such as Figure 6B As shown, indicator 642 may be substantially similar to indicator 532, but may indicate that sidelink transmission B 540 is transmitted by the responding UE of COT 524. Accordingly, UE 502c, which receives sidelink transmission B, can decode indicator 642 and know that sidelink transmission B is received from the responding UE of COT 524 (e.g., UE 502b), and not from the initiating UE of COT 524. Accordingly, UE 502c can determine that it may not share COT 524 for transmitting sidelink transmission D.

[0108] In action 616, upon determining that COT 524 is not intended for sharing by UE 502c, UE 502c suppresses transmission-side link transmission D during COT 524, as if by Figure 6A Arrows with the symbol "X" and Figure 6B The dashed box D with the symbol "X" is shown in the diagram. To transmit sidelink transmission C, UE 502c can perform CAT4 LBT 652 in the shared channel to contend for COT654, and transmit sidelink transmission D 660 while passing through CAT4 LBT 552 (with a checksum), as shown. Figure 6B As shown, the sidelink transmission D 660 may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding... Figure 4 The subject of discussion.

[0109] As can be observed, regardless of whether sidelink transmission D 660 is intended to be received by UE 502b, which has transmitted sidelink transmission B540, UE 502c may not transmit sidelink transmission D 660 during COT 524 because UE 502b is not the initiating UE of COT 524.

[0110] Furthermore, by preventing UE 502c from sharing COT 524 based on UE 502 receiving sidelink transmission B from the responding node during COT 524, COT sharing can be avoided from propagating from UE 502b to UE 502c (based on sidelink transmission B540) and from UE 502c to UE 502d (based on sidelink transmission D660). Preventing COT sharing propagation allows for fairer channel access between different wireless communication devices sharing the same channel on the same RAT or different RATs, rather than depriving other wireless communication devices of channel access opportunities.

[0111] Figure 7This is a flowchart of a sidelink communication COT sharing method 700 according to some aspects of this disclosure. Aspects of method 700 can be performed by a computing device of a wireless communication device (e.g., a processor, processing circuitry, and / or other suitable components) or other suitable means for performing the steps. For example, a wireless communication device (such as UE 115, 315, 402, or 502) can utilize one or more components (such as processor 1102, memory 1104, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116) to perform the steps of method 700. Method 700 can be implemented as described above. Figure 1-4 A similar mechanism to that described in 5A-5B and 6A-6B. As explained, method 700 includes several enumeration steps, but aspects of method 700 may include additional steps before, after, and between these enumeration steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

[0112] In block 710, a first UE (e.g., UE 115, 315, 502, or 1100) receives a first sidelink transmission from a second UE during COT (e.g., COT524) in a shared channel. The first sidelink transmission may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding... Figure 4 The subject of discussion.

[0113] In block 720, the first UE determines whether the COT is used for sharing. For example, the first sidelink transmission may include COT sharing information similar to indicators 532 and / or 642. In some aspects, the COT sharing information may indicate whether COT sharing in the first COT is permitted. In some aspects, the COT sharing information may indicate whether the first sidelink transmission is transmitted by the initiating UE of the COT. If the COT sharing information indicates that the first sidelink transmission is transmitted by the initiating UE of the COT, then the COT is used for sharing by the responding UE of the first sidelink transmission. However, if the COT sharing information indicates that the first sidelink transmission is transmitted by the responding UE of the COT, then the COT is not used for sharing by the responding UE of the first sidelink transmission. Accordingly, the first UE may determine whether the COT is used for sharing based on the COT sharing information. If the first UE determines that the COT is used for sharing, the first UE proceeds to block 730.

[0114] In box 730, the first UE determines whether the second UE is one of two or more UEs (e.g., a group of UEs) intended to receive the second sidelink transmission. In some aspects, the first UE may determine to transmit the second sidelink transmission in a connection-based multicast mode to a specific group of receiving UEs (e.g., approximately 2, 3, 4, 5, 6, or more), and thus determine whether the second UE is in that specific group. In some aspects, the first UE may determine to transmit the second sidelink transmission in a connectionless multicast mode, and may determine whether the second UE is the intended recipient based on a zone associated with the second UE. The zone may be based on the geographical location of the second UE or the physical distance between the first and second UEs. In some instances, the zone may be pre-configured, and the second UE may include zone information (e.g., a zone ID identifying the zone associated with the second UE) in the SCI within the first sidelink transmission. If the first UE determines that the second UE is one of two or more UEs intended to receive the second sidelink transmission, the first UE proceeds to box 740.

[0115] In box 740, a first UE transmits a second sidelink transmission to two or more UEs during a shared portion of the COT (e.g., portion 508) based on COT sharing. COT sharing may be in response to determining that the second UE is one of two or more UEs intended to receive the second sidelink transmission. The first UE may identify the shared portion (e.g., duration) from the COT sharing information carried in the first sidelink transmission. The second sidelink transmission may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding... Figure 4 The subject of discussion.

[0116] Returning to box 720, if the first UE determines that the COT is not used for sharing, the first UE proceeds to box 750. In box 750, the first UE suppresses the transmission of second sidelink transmissions during the shared portion of the COT. For example, the first UE may alternatively initiate the second COT by performing a CAT4 LBT in the shared channel and transmit second sidelink transmissions during the second COT while passing through the CAT4 LBT.

[0117] Returning to box 730, if the first UE determines that the second UE is not one of two or more UEs intended to receive transmissions on the second side link, the first UE proceeds to box 750.

[0118] Discussing each other in relation to each other Figure 8A and 8B This explains COT sharing used for sidelink multicast. Figure 8AThis is a sequence diagram illustrating a sidelink COT sharing method 800 according to some aspects of this disclosure. Method 800 can be implemented among UEs 502a, UE 502b, UE 502c, and UE 502d operating on a shared radio frequency band (e.g., in a shared spectrum or unlicensed spectrum). UEs 502a-d can be similar to UEs 115 and / or 315. Figure 8B This is a timing diagram 840 illustrating the side-link COT sharing method 800 based on some aspects of this disclosure. Figure 8B In this context, the x-axis represents time in some arbitrary units.

[0119] Method 800 is basically similar to methods 500, 600, and 700, and can be used as described above. Figures 5A-5B The mechanisms in methods 600 and 700 discussed in 6A-6B and 7 are described. Method 800 further explains how a responding UE of a sidelink transmission can utilize COT sharing to transmit ACK / NACK feedback (e.g., feedback 440 in PSFCH 425). As explained above, a sidelink transmitting UE can request ACK / NACK feedback from an intended receiving UE or a responding UE for unicast sidelink transmissions or connection-based sidelink transmissions. A sidelink transmitting UE can also request NACK-only feedback from an intended receiving UE or a responding UE for connectionless multicast transmissions. In method 800, if the responding UE can detect COT sharing information from the initiating UE of the COT, rather than based on whether the initiating UE of the COT transmitted a sidelink transmission, the responding UE receiving the sidelink transmission in that COT can transmit ACK / NACK feedback in the shared portion of that COT. In other words, COT sharing for PSFCH transmissions is independent of COT sharing for PSSCH transmissions. Although Method 800 is described in the context of ACK / NACK transmission with COT sharing in a multicast transmission scenario, it should be understood that similar mechanisms can be applied to ACK / NACK transmission in unicast transmission scenarios in other examples.

[0120] As shown, in action 810, UE 502a (e.g., the initiating UE) performs CAT4LBT in the shared channel. Figure 8B The middle is shown as 842) to initiate COT ( Figure 8B (This is shown as 844). For example, CAT4 LBT 842 is successful (indicating that the channel is clear for transmission), as shown by the check flag.

[0121] During action 820, while traversing CAT4 LBT, UE 502a transmits sidelink transmission A during part 806 of COT 844 (in Figure 8B(Illustrated as 850). Sidelink transmission A may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding Figure 4 The sidelink transmission A discussed herein is a multicast transmission intended to be received by, for example, UE 502b and UE 502c, as indicated by the two arrows in the dashed elliptical grouping. UE 502b and UE 502c (e.g., responding UEs) may receive sidelink transmission A.

[0122] As an example, sidelink transmission A can be a connection-based multicast transmission, and UE 502a can request ACK / NACK feedback for sidelink transmission A from each intended receiver. In some aspects, UE 502a can include a PSFCH resource allocation indication (e.g., carried in the SCI) in sidelink transmission A for each intended receiver to transmit NACK / NACK feedback. In some instances, UE 502a can transmit data in the PSSCH area of ​​a time slot and can indicate different PSFCH resources in the PSFCH area of ​​the time slot for different UEs. In some examples, a time slot can include 14 symbols indexed from 0 to 13, the PSSCH area can include symbols 1 to 9 of that time slot, and the PSFCH area can include symbols 11 and 12 of that time slot. The different PSFCH resources for different intended receivers can be FDM, TDM, and / or code division multiplexing (CDM) in the PSFCH area.

[0123] Similar to methods 500 and 600, UE 502a may include an indicator 854 in the sidelink transmission A to provide COT sharing information related to COT 844. The indicator 854 may indicate whether the sidelink transmission A 850 is transmitted by the initiating UE (of COT 844) or the responding UE (of COT 844). In some aspects, the indicator 854 may have a length of 1 bit, where a bit value of 1 indicates the initiating node, a bit value of 0 indicates the responding node, and vice versa. In some aspects, the indicator 854 may be part of a first-phase SCI or a second-phase SCI. In some aspects, the indicator 854 may be part of a COT-SI. For example, the COT-SI may include a bit map, and the indicator 854 may correspond to bits within that bit map. In some cases, the COT-SI may indicate other information related to COT 844 (e.g., the duration of the shared COT 844, such as...). Figure 8B Part 808 shown.

[0124] In action 822, upon receiving sidelink transmission A at UE 502b, UE 502b sends ACK / NACK feedback to UE 502a. If UE 502b successfully decodes the data from sidelink transmission A 850, UE 502b may send ACK. Conversely, if UE 502b detects the presence of sidelink transmission A 850 (based on successful SCI decoding) but fails to decode the data from sidelink transmission A 850, UE 502b may send NACK. In some aspects, UE 502b may send a predetermined waveform sequence to indicate ACK, and may send different predetermined waveform sequences to indicate NACK. Since UE 502b will send ACK / NACK feedback to UE 502a, which initiated COT 844, UE 502b may send ACK / NACK feedback during the shared portion 808 of COT 844 (shown as 852b), as... Figure 8B As shown in the diagram, UE 502b can use the PSFCH resource as indicated by the sidelink transmission A 850 to transmit ACK / NACK feedback 852b.

[0125] In action 824, upon receiving sidelink transmission A at UE 502c, UE 502c sends an ACK / NACK feedback to UE 502a. UE 502c may send an ACK or NACK depending on whether UE 502c successfully decodes the data from sidelink transmission A 850. Since UE 502c will send an ACK / NACK feedback to UE 502a, which initiated COT 844, UE 502c may send the ACK / NACK feedback during the shared portion 808 of COT 844 (shown as 852c), as... Figure 8B As shown in the diagram, UE 502c can use the PSFCH resource as indicated by the sidelink transmission A 850 to transmit ACK / NACK feedback 852b.

[0126] Similar to methods 500 and / or 600, after UE 502b receives sidelink transmission A, UE 502b may expect to transmit sidelink transmission B in multicast mode to UE 502a, UE 502c, and UE 502d (e.g., a group of UEs identified by a group ID). UE 502b can determine that the initiating UE 502a is the intended recipient of sidelink transmission B. Therefore, in action 830, UE 502b transmits sidelink transmission B in multicast mode (as indicated by the three arrows grouped by the dashed arrows) to UE 502a, UE 502c, and UE 502d during the shared portion 508 of COT524. Figure 8B(Illustrated as 860). Sidelink transmission B 860 may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding Figure 4 As discussed above, UE 502a may include a PSFCH resource allocation indication (e.g., carried in the SCI) in sidelink transmission B 860 for each intended receiver to transmit NACK / NACK feedback, as discussed above in action 820 with respect to sidelink transmission A. In some aspects, sidelink transmission B 860 may also include an indication 864 similar to indication 854, for example, indicating that sidelink transmission B 860 is transmitted by the responding UE of COT 844.

[0127] In action 832, upon receiving sidelink transmission B at UE 502a, UE 502a sends an ACK / NACK feedback to UE 502b. UE 502a may send ACK or NACK depending on whether UE 502a has successfully decoded the data from sidelink transmission A 850. Since COT 844 is initiated by UE 502a, UE 502a can, as... Figure 8B During the shared portion 808 of COT 844 shown, ACK / NACK feedback is transmitted (as shown in 862a). UE 502a may use the PSFCH resources indicated by sidelink transmission B 860 to transmit ACK / NACK feedback 862a.

[0128] In action 834, upon receiving sidelink transmission B at UE 502c, UE 502c sends ACK / NACK feedback to UE 502b. UE 502c may send ACK or NACK depending on whether UE 502c successfully decodes data from sidelink transmission A 850. In some aspects, UE 502c may monitor COT sharing indications and may determine whether to send ACK / NACK feedback in COT 844 based on whether a COT sharing indication for COT 844 is detected. As an example, UE 502c may be located near UE 502a and may detect COT sharing information (indicator 854) related to COT 844 during which sidelink transmission B 860 is received. Accordingly, UE 502c may send ACK / NACK feedback (shown as 862c) during the sharing portion 808 of COT 844, as shown. Figure 8B As shown in the figure.

[0129] In action 836, upon receiving sidelink transmission B at UE 502d, UE 502d sends ACK / NACK feedback to UE 502b. UE 502c may send ACK or NACK depending on whether UE 502d successfully decodes the data from sidelink transmission A 850. In some respects, UE 502d may monitor COT sharing indications and may determine whether to send ACK / NACK feedback in COT 844 based on whether a COT sharing indication for COT 844 is detected. As an example, UE 502d may be located further away from UE 502a and may not detect COT sharing information (indicator 854) related to COT 844 during which sidelink transmission B 860 is received, and therefore may suppress the transmission of ACK / NACK feedback during the sharing portion 806 of COT 844, as by Figure 8A Arrows with the symbol "X" and Figure 8B The dashed box with the symbol "X" indicates this. To transmit ACK / NACK feedback, UE 502d can perform CAT4 LBT 872 in the shared channel to contend for COT 874, and transmit ACK / NACK feedback 862d upon passing CAT4 LBT 872 (checked), as shown below. Figure 8B As shown in the figure.

[0130] As can be observed in method 800, when a responding UE (e.g., UE 502b) shares a COT for sidelink transmission (unicast or multicast), the responding UE may not know whether the receiving UE of the sidelink transmission can detect the COT sharing information, because each receiving UE may experience different interference. Thus, the responding UE can include a CAT4 LBT channel access type indicator in the sidelink transmission and allow the receiving UE to choose whether to share the COT for ACK / NACK transmission. For example, if the receiving UE cannot detect the COT sharing information for the COT, the receiving UE can perform CAT4 LBT in the shared channel to contend for another COT and transmit ACK / NACK during the other COT while passing through CAT4 LBT. However, if the receiving UE detects the COT sharing information for the COT, the receiving UE can either not perform LBT or perform CAT2 LBT before transmitting ACK / NACK in the COT. For example, UE 502b can include a channel access type indicator 866 in sidelink transmission B 860, such as... Figure 8BAs shown, the Channel Access Type Indicator 866 can indicate CAT4 LBT for ACK / NACK transmission. For example, UE 502c can switch to performing CAT2 LBT before transmitting ACK / NACK at action 822 based on UE 502c detecting indicator 854 with COT sharing information for COT 844.

[0131] Figure 9 This is a flowchart of a sidelink communication COT sharing method 900 according to some aspects of this disclosure. Aspects of method 900 can be performed by a computing device of a wireless communication device (e.g., a processor, processing circuitry, and / or other suitable components) or other suitable means for performing the steps. For example, a wireless communication device (such as UE 115, 315, or 502) can utilize one or more components (such as processor 1102, memory 1104, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116) to perform the steps of method 900. Method 900 can be implemented as described above. Figure 1-4 Similar mechanisms to those described in 8A-8B. As explained, method 900 includes several enumeration steps, but aspects of method 900 may include additional steps before, after, and between these enumeration steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

[0132] In box 910, a first UE (e.g., UE 115, 315, 402, 502, or 1100) receives a first sidelink transmission from a second UE during COT (e.g., COT 524) in a shared channel. The first sidelink transmission may include SCI (e.g., SCI 430) and data (e.g., data 435), as described above regarding... Figure 4 The first UE can successfully decode the SCI and can perform decoding to decode data transmitted from the first sidelink. In some aspects, the first sidelink transmission can be a unicast transmission. In some aspects, the first sidelink transmission can be a multicast transmission. The first sidelink transmission may also include PSFCH resource allocation information for the receiving UE to transmit ACK / NACK feedback for the first sidelink transmission.

[0133] In block 920, the first UE determines ACK / NACK feedback for the first sidelink transmission. For example, the UE may perform data decoding on the first sidelink transmission. If the first UE successfully decodes the data from the first sidelink transmission, the first UE may generate an ACK (e.g., a waveform sequence representing an ACK). Conversely, if the first UE fails to decode the data from the first sidelink transmission, the first UE may generate a NACK (e.g., a waveform sequence representing a NACK).

[0134] In block 930, the first UE determines whether the second UE is the initiating UE of the first COT. To assist the responding UE of the first sidelink transmission in determining whether the first COT can be shared, the first sidelink transmission may include a COT-SI indicator (e.g., indicator 532, 642, and / or 864) indicating whether the first sidelink transmission was transmitted by the initiating UE of the first COT. The COT-SI may be part of the SCI in the first sidelink transmission. The COT-SI indicator may also include an indication of the duration in the first COT used for sharing. Accordingly, the first UE may determine whether the second UE is the initiating UE of the first COT based on the indicator. If the first UE determines that the second UE is the initiating UE of the first COT, the first UE proceeds to block 970.

[0135] In box 970, in response to determining that the second UE is the initiating UE of the first COT, the first UE performs CAT2 LBT before transmitting ACK / NACK in the COT. The first UE may perform CAT2 LBT based on the fact that ACK / NACK is to be transmitted within the shared portion of the first COT. In some other instances, the first UE may not perform LBT before transmission in the shared COT.

[0136] In frame 980, upon passing through CAT2 LBT, the first UE transmits ACK / NACK feedback for first side link transmission during the shared portion of the first COT. The first UE can obtain time-related information regarding the duration of the shared portion from the COT-SI indicator.

[0137] Returning to box 930, if the first UE determines that the second UE is not the initiating UE of the first COT, the first UE proceeds to box 940. In box 940, the first UE determines whether COT sharing information for the first COT has been detected. For example, the first UE may monitor COT-SI or COT sharing information from other UEs, for instance, by performing SCI decoding at each PSCCH resource in the sidelink resource pool. Upon successful SCI decoding, the first UE may read the information in the SCI. The first UE may determine whether COT sharing information for the first COT has been detected based on the information read from the decoded SCI. If the first UE determines that COT sharing information for the first COT has been detected, the first UE proceeds to box 970.

[0138] If the first UE determines that no COT sharing information for the first COT is detected, the first UE proceeds to block 950. In block 950, the first UE performs CAT4 LBT in the shared channel to contend for the second COT. For example, CAT4 LBT is through (indicating that the channel is open for transmission).

[0139] In frame 960, during the passage of CAT4 LBT, the first UE transmits ACK / NACK feedback during the second COT.

[0140] Figure 10 This is a block diagram of an exemplary BS 1000 according to some aspects of this disclosure. The BS 1000 can be as described above. Figure 1 The BS 105 in network 100 or BS 305 in network 300 discussed herein. As shown, BS 1000 may include processor 1002, memory 1004, sidelink configuration module 1008, transceiver 1010 including modem subsystem 1012 and RF unit 1014, and one or more antennas 1016. 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 to each other, for example, via one or more buses.

[0141] Processor 1002 may include a central processing unit (CPU), digital signal processor (DSP), application-specific integrated circuit (ASIC), controller, field-programmable gate array (FPGA) device, other hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 1002 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.

[0142] Memory 1004 may include cache memory (e.g., cache memory of processor 1002), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard disk drives, other forms of volatile and non-volatile memory, or combinations of different types of memory. In one aspect, memory 1004 includes a non-transient computer-readable medium. Memory 1004 may store or have instructions 1006 recorded thereon. Instructions 1006 may include, when executed by processor 1002, causing processor 1002 to perform various aspects of this disclosure as referenced herein in conjunction with UE 115 (e.g., ...). Figure 1-3 Instructions 1006 are instructions describing the operations described in various aspects. Instruction 1006 may also be referred to as program code, which can be broadly interpreted as including any type of computer-readable statement(s).

[0143] The sidelink configuration module 1008 may be implemented via hardware, software, or a combination thereof. For example, the sidelink configuration module 1008 may be implemented as a processor, circuitry, and / or instructions 1006 stored in memory 1004 and executed by processor 1002. In some examples, the sidelink configuration module 1008 may be integrated within the modem subsystem 1012. For example, the sidelink configuration module 1008 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 1012.

[0144] The sidelink configuration module 1008 can communicate with various components of the BS 1000 to perform various aspects of this disclosure, such as... Figure 1-3 Various aspects. For example, the sidelink configuration module 1008 is configured to configure UEs (e.g., UEs 115, 315, 402, and 502) to have a sidelink resource pool for sidelink communication and / or configure certain UEs as anchor UEs, as described above.

[0145] As shown, transceiver 1010 may include modem subsystem 1012 and RF unit 1014. Transceiver 1010 may be configured to communicate bidirectionally with other devices, such as UE 115 and / or another core network element. Modem subsystem 1012 may be configured to modulate and / or encode data according to MCS (e.g., LDPC decoding scheme, turbo decoding scheme, convolutional decoding scheme, digital beamforming scheme, etc.). RF unit 1014 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / encoded data transmitted from modem subsystem 1012 (on out-of-band transmission) or originating from another source (such as UE 115) (e.g., RRC configuration, sidelink resource pool configuration). RF unit 1014 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in transceiver 1010, modem subsystem 1012 and / or RF unit 1014 may be separate devices coupled together at BS 105 so that BS 105 can communicate with other devices.

[0146] RF unit 1014 may provide modulated and / or processed data (e.g., data packets (or more generally, data messages containing one or more data packets and other information)) to antenna 1016 for transmission to one or more other devices. This may include, for example, information transmission for completing attachment to the network and communication with the resident UE 115, according to some aspects of this disclosure. Antenna 1016 may further receive data messages transmitted from other devices and provide the received data messages for processing and / or demodulation at transceiver 1010. Transceiver 1010 may provide demodulated and decoded data to sidelink configuration module 1008 for processing. Antenna 1016 may include multiple antennas of similar or different designs to maintain multiple transmission links.

[0147] In one aspect, the BS 1000 may include multiple transceivers 1010 implementing different RATs (e.g., NR and LTE). In another aspect, the BS 1000 may include a single transceiver 1010 implementing multiple RATs (e.g., NR and LTE). In yet another aspect, the transceiver 1010 may include various components, wherein different combinations of the components can implement different RATs.

[0148] Figure 11 This is a block diagram of an exemplary UE 1100 according to some aspects of this disclosure. UE 1100 may be as described above regarding... Figure 1 The UE 115 discussed above, as mentioned above... Figure 3 The UE 315 discussed above, or as mentioned above... Figure 4 , 5A The UE 502 discussed in -5B, 6A-6B, and 8A-8B. As shown, UE 1100 may include a processor 1102, a memory 1104, a sidelink COT mode-sharing module 1108, a transceiver 1110 including a modem subsystem 1112 and a radio frequency (RF) unit 1114, and one or more antennas 1116. 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.

[0149] Processor 1102 may have various features as a special-purpose processor. For example, these features may include a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 1102 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.

[0150] Memory 1104 may include cache memory (e.g., cache memory of processor 1102), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or combinations of different types of memory. In some aspects, memory 1104 may include non-transient computer-readable medium. Memory 1104 may store instructions 1106. Instructions 1106 may include causing processor 1102 to perform the operations described herein when executed by processor 1102 (e.g., ...). Figure 1-3 Instructions 1106 (including aspects of 4, 5A-5B, 6A-6B, 7, 8A-8B, 9, and 12). Instructions 1106 may also be referred to as program code. Program code can be used to cause wireless communication devices to perform these operations, for example by causing one or more processors (such as processor 1102) to control or command the wireless communication devices to do so. The terms “instruction” and “code” should be interpreted broadly to include any type of computer-readable statement. For example, the terms “instruction” and “code” can refer to one or more programs, routines, subroutines, functions, procedures, etc. “Instruction” and “code” can include a single computer-readable statement or many computer-readable statements, as described above regarding Figure 10 The subject of discussion.

[0151] The sidelink COT sharing module 1108 can be implemented via hardware, software, or a combination thereof. For example, the sidelink COT sharing module 1108 can be implemented as a processor, circuitry, and / or instructions 1106 stored in memory 1104 and executed by processor 1102. In some examples, the sidelink COT sharing module 1108 can be integrated within the modem subsystem 1112. For example, the sidelink COT sharing module 1108 can be implemented by a combination of software components (e.g., executed by a DSP or general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1112.

[0152] The sidelink COT sharing module 1108 can communicate with various components of the UE 1100 to perform various aspects of this disclosure, such as... Figure 1-3The aspects of 4, 5A-5B, 6A-6B, 7, 8A-8B, 9, and 11. In some aspects, the sidelink COT sharing module 1108 is configured to initiate a COT in the shared channel by performing a CAT4 LBT (e.g., COT 524, 844), and transmit a first sidelink transmission (e.g., sidelink transmission 530, 850) during a portion of the COT while performing the CAT4 LBT. The first sidelink transmission may be a unicast transmission, a multicast transmission, or a broadcast transmission. In some aspects, the sidelink COT sharing module 1108 is configured to include an indicator (e.g., indicator 532 and 854) in the first sidelink transmission to indicate that the first sidelink transmission is initiated by the UE of the COT and that the COT is used for sharing (e.g., by indicating the shared portion of the COT).

[0153] In some aspects, the sidelink COT sharing module 1108 is configured to receive a first sidelink transmission (e.g., sidelink transmission 530, 850) from a second UE (e.g., UE 115, 315, 502 and / or 1100) during a first COT (e.g., COT 524, 844), wherein the first COT is initiated by the second UE. The first sidelink transmission may include an indication (e.g., indicator 642 and 864) of whether the first sidelink transmission was transmitted by the UE that initiated the first COT. The sidelink COT sharing module 1108 is configured to determine, based on COT sharing, whether the second UE is one of two or more UEs intended to receive the second sidelink transmission, and to transmit the second sidelink transmission to those two or more UEs during a portion of the first COT. For example, COT sharing responds to determining that the second UE is one of two or more UEs intended to receive the second sidelink transmission, as described above regarding Figures 5A-5B The above are discussed in sections 6A-6B and 7.

[0154] In some aspects, the sidelink COT sharing module 1108 is configured to receive a third sidelink transmission from a third UE during the second COT (e.g., sidelink transmissions 540, 860). The third sidelink transmission may include data and may indicate that the third sidelink UE is not the initiator of the second COT. The sidelink COT sharing module 1108 is configured to determine whether data decoding from the third sidelink transmission was successful, and based on the success of the data decoding, to transmit ACK / NACK feedback to the third UE (e.g., ACK / NACK feedbacks 852 and 862). The sidelink COT sharing module 1108 is further configured to monitor COT sharing information and whether COT sharing information for the second COT sharing is detected. The sidelink COT sharing module 1108 is further configured to determine whether to transmit ACK / NACK feedback during the second COT based on whether COT sharing information for the COT is detected, for example, as described above regarding... Figures 8A-8B And the nine discussed.

[0155] As shown, transceiver 1110 may include modem subsystem 1112 and RF unit 1114. Transceiver 1110 may be configured to communicate bidirectionally with other devices (such as BS 105). Modem subsystem 1112 may be configured to modulate and / or encode data from memory 1104 and / or sidelink COT sharing module 1108 according to modulation and coding schemes (MCS) (e.g., low-density parity-check (LDPC) coding scheme, turbo coding scheme, convolutional coding scheme, digital beamforming scheme, etc.). RF unit 1114 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated / coded data (e.g., PSCCH, PSSCH, SCI-1, SCI-2, sidelink data, COT-SI, COT sharing information) transmitted from modem subsystem 1112 (in out-of-band transmission) or from another source (such as UE 115 or BS 105). RF unit 1114 can be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in transceiver 1110, modem subsystem 1112 and RF unit 1114 can be separate devices coupled together at UE 115 to enable UE 115 to communicate with other devices.

[0156] RF unit 1114 can provide modulated and / or processed data (e.g., data packets (or more generally, data messages that may include one or more data packets and other information)) to antenna 1116 for transmission to one or more other devices. Antenna 1116 can further receive data messages transmitted from other devices. Antenna 1116 can provide received data messages for processing and / or demodulation at transceiver 1110. Transceiver 1110 can provide demodulated and decoded data (e.g., PSCCH, PSSCH, SCI-1, SCI-2, sidelink data, COT-SI, COT sharing information) to sidelink COT sharing module 1108 for processing. Antenna 1116 may include multiple antennas of similar or different designs to maintain multiple transmission links. RF unit 1114 can configure antenna 1116.

[0157] In one aspect, transceiver 1110 is configured to receive a first sidelink transmission from a second UE (e.g., UE 115, 315, 502, and / or 1100) during a first COT, wherein the first COT is associated with the second UE. For example, the first COT is initiated by the second UE. Processor 1102 is coupled to the transceiver and configured to determine whether the second UE is one of two or more UEs intended to receive the second sidelink transmission. Transceiver 1110 is further configured to transmit the second sidelink transmission to two or more UEs based on COT sharing during a portion of the first COT. COT sharing is in response to determining that the second UE is one of two or more UEs intended to receive the second sidelink transmission.

[0158] In one aspect, UE 1100 may include multiple transceivers 1110 implementing different RATs (e.g., NR and LTE). In another aspect, UE 1100 may include a single transceiver 1110 implementing multiple RATs (e.g., NR and LTE). In yet another aspect, transceiver 1110 may include various components, wherein different combinations of the components can implement different RATs.

[0159] Figure 12 This is a flowchart of a wireless communication method 1200 according to some aspects of this disclosure. Aspects of method 1200 can be performed by a computing device of a wireless communication device (e.g., a processor, processing circuitry, and / or other suitable components) or other suitable means for performing the steps. For example, a wireless communication device (such as UE 115, 315, 402, or 1100) can utilize one or more components (such as processor 1102, memory 1104, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116) to perform the steps of method 1200. Figure 3-4 Similar mechanisms are described in 5A-5B, 6A-6B, 7, 8A-8B, and 9. As explained, method 1200 includes several enumeration steps, but aspects of method 1200 may include additional steps before, after, and between these enumeration steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

[0160] In block 1210, a first UE (e.g., UE 115, 315, 502, or 1100) receives a first sidelink transmission from a second UE during a first COT, wherein the first COT is associated with the second UE. The first sidelink transmission may include an SCI and sidelink data. In some aspects, the SCI may indicate whether the second UE is the initiating UE of the first COT. In some aspects, the SCI may include a first-phase SCI and a second-phase SCI. In some instances, an indication of whether the second UE is the initiating UE of the first COT (e.g., indicator 532, 642, 854) may be included in the first-phase SCI. In some other instances, an indication of whether the second UE is the initiating UE of the first COT (e.g., indicator 532, 642, 854) may be included in the second-phase SCI. In some aspects, the SCI may include a COT-SI indicating whether COT sharing in the first COT is permitted. In some instances, the first UE may utilize one or more components, such as processor 1102, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116, to perform the operation of block 1220.

[0161] In box 1220, the first UE determines whether the second UE is one of two or more UEs intended to receive the second sidelink transmission. In some aspects, the second sidelink transmission will be delivered as a multicast transmission. In some aspects, a multicast transmission is a connection-based transmission intended to be received by a specific group of UEs (associated with a specific group ID). Accordingly, the first UE is aware of the UEs in the specific group and can determine whether the second UE is one of the UEs in that specific group. In some aspects, the multicast transmission is connectionless. In other words, the second sidelink transmission is not targeted at a specific group of UEs with a specific group ID. Instead, the second sidelink transmission may be intended to be received by UEs located in a certain district or area, or within a certain physical distance or distance range from the first UE. Therefore, the second UE may determine whether the first UE is one of the UEs in a specific district, for example, based on the geographical location of the first UE or the physical distance between the first UE and the second UE. In some instances, districts may be pre-configured, and the second UE may provide area information (e.g., a district ID identifying the district associated with the second UE) in the SCI within the first sidelink transmission. In some respects, the second sidelink transmission will be broadcast to all UEs in the neighborhood of the first UE, and therefore the second UE is the intended recipient of the second sidelink transmission. In some instances, the first UE may utilize one or more components, such as processor 1102, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116, to perform the operation of block 1220.

[0162] In box 1230, the first UE transmits a second sidelink transmission to two or more UEs during a portion of the first COT (e.g., sharing portion 508 or 808) based on COT sharing. The second sidelink transmission can be a multicast transmission or a broadcast transmission. COT sharing may be initiated in response to determining that the second UE is one of two or more UEs intended to receive the second sidelink transmission, for example, as described above regarding... Figures 5A-5B As discussed in 6A-6B and 7. In some instances, the first UE may utilize one or more components, such as processor 1102, sidelink COT sharing module 1108, transceiver 1110, modem 1112, and one or more antennas 1116, to perform the operation of block 1230.

[0163] In some respects, the first UE may further transmit a second sidelink transmission during that part of the first COT based on the SCI indicating that the second UE is the initiating UE of the first COT (in the first sidelink transmission).

[0164] In some respects, the first UE may further instruct the COT sharing, which is permitted in the first COT, to transmit the second side link transmission during that part of the first COT, based on the COT-SI (in the first side link transmission).

[0165] In some aspects, the first UE can transmit second-sidelink transmissions in connection-based multicast mode. In some aspects, the first UE can transmit second-sidelink transmissions in connectionless mode. In some aspects, the first UE can transmit second-sidelink transmissions in broadcast mode.

[0166] In some aspects, the first UE may further receive a third-sidelink transmission including data from a third UE (e.g., UE 115, 315, 402, 502, or 1100) during the second COT. The first UE may determine, for example, whether the third UE is the initiating UE of the second COT based on indications in the third-sidelink transmission (e.g., indications 532, 642, 854, and / or 864). In response to determining that the third UE is the initiating UE of the second COT, the first UE may transmit ACK / NACK feedback on the data received / negatively acknowledged (NACK) during a portion of the second COT, for example, as described above regarding... Figures 8A-8B And the nine discussed.

[0167] In some aspects, the first UE may receive third-sidelink transmissions, including data, from a third UE during the second COT. The third UE may be a responding UE of the second COT. The first UE may monitor COT-shared information associated with the second COT. As explained above, the COT-shared information may be carried in the SCI, and therefore the first UE may perform SCI decoding in the SCI resources to detect the COT-shared information. The first UE may determine, based on the monitoring, whether to transmit ACK / NACK feedback for data during a portion of the second COT. In some aspects, the first UE may suppress the transmission of ACK / NACK feedback during that portion of the second COT in response to determining that no COT-shared information associated with the second COT is detected from the monitoring. In some aspects, the first UE may further perform CAT4 LBT and transmit ACK / NACK feedback during the third COT based on CAT4 LBT. In some aspects, the third-sidelink transmission may include a channel access type indicating the CAT4 LBT mode for transmitting ACK / NACK feedback. In some respects, the first UE may receive COT-shared information associated with the second COT, and in response to receiving the COT-shared information associated with the second COT, transmit ACK / NACK feedback during that portion of the second COT, for example, as described above regarding Figures 8A-8B And the nine discussed.

[0168] In some respects, the first UE may further determine whether the second UE is one of two or more UEs intended to receive third-sidelink transmissions. The first UE may suppress the transmission of third-sidelink transmissions during that portion of the first COT in response to determining that the second UE is not one of two or more UEs intended to receive third-sidelink transmissions.

[0169] Further aspects of this disclosure include the following:

[0170] Aspect 1 includes a method of wireless communication performed by a first user equipment (UE), the method comprising: receiving a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; determining whether the second UE is one of two or more UEs intended to receive a second sidelink transmission; and transmitting the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

[0171] Aspect 2 includes the method of aspect 1, wherein receiving the first sidelink transmission includes: receiving sidelink control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; and transmitting the second sidelink transmission during that part of the first COT based on COT sharing, further based on the SCI indicating that the second UE is the initiating UE of the first COT.

[0172] Aspect 3 includes a method of any of Aspects 1-2, wherein receiving a first sidelink transmission includes receiving sidelink control information (SCI) from a second UE, the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted. And during that portion of the first COT, transmitting a second sidelink transmission further indicates, based on the COT-SI, that COT sharing in the first COT is permitted.

[0173] Aspect 4 includes any of the methods of aspects 1-3, wherein transmitting the second side link transmission includes transmitting the second side link transmission in a broadcast mode.

[0174] Aspect 5 includes the method of any of Aspects 1-4, wherein transmitting the second side link transmission includes transmitting the second side link transmission in a multicast mode.

[0175] Aspect 6 includes the method of any of Aspects 1-5, further comprising: receiving a third side link transmission including data from a third UE during a second COT; determining whether the third UE is the initiating UE of the second COT; and transmitting ACK / NACK feedback on the data during a portion of the second COT in response to determining that the third UE is the initiating UE of the second COT.

[0176] Aspect 7 includes the method of any of Aspects 1-6, and further includes: receiving a third side link transmission including data from a third UE during the second COT; monitoring COT-shared information associated with the second COT; and determining, based on the monitoring, whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

[0177] Aspect 8 includes the method of any of Aspects 1-7, further comprising: determining whether the second UE is one of two or more UEs intended to receive third sidelink transmission; and suppressing the transmission of third sidelink transmission during that portion of the first COT in response to determining that the second UE is not one of two or more UEs intended to receive third sidelink transmission.

[0178] Aspect 9 includes a first user equipment (UE) comprising a memory, a transceiver, and at least one processor coupled to the memory and the transceiver, wherein the first UE is configured to: receive a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission; and transmit the second sidelink transmission to two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

[0179] Aspect 10 includes the first UE of aspect 9, wherein the first UE is further configured to: receive side link control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; and further transmit a second side link transmission during that portion of the first COT based on the SCI indicating that the second UE is the initiating UE of the first COT.

[0180] Aspect 11 includes a first UE of either Aspect 9 or 10, wherein the first UE is further configured to receive side link control information (SCI) from a second UE, the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted; and further transmitting a second side link transmission during that portion of the first COT based on the indication that COT sharing in the first COT is permitted by the COT-SI.

[0181] Aspect 12 includes a first UE of any of aspects 9-11, wherein the first UE is further configured to transmit second side link transmissions in broadcast mode.

[0182] Aspect 13 includes a first UE of any of Aspects 9-12, wherein the first UE is further configured to transmit second side link transmissions in a multicast mode.

[0183] Aspect 14 includes a first UE of any of Aspects 9-13, wherein the first UE is further configured to receive a third side link transmission including data from a third UE during the second COT; determine whether the third UE is the initiating UE of the second COT; and transmit ACK / NACK feedback on the data during a portion of the second COT in response to determining that the third UE is the initiating UE of the second COT.

[0184] Aspect 15 includes a first UE of any of Aspects 9-14, wherein the first UE is further configured to: receive a third side link transmission including data from a third UE during the second COT; monitor COT-shared information associated with the second COT; and determine, based on the monitoring, whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

[0185] Aspect 16 includes a first UE of any of Aspects 9-15, wherein the first UE is further configured to: suppress transmission of ACK / NACK feedback during that portion of the second COT in response to determining that no COT-shared information associated with the second COT is detected from surveillance; perform Category 4 (CAT4) LBT; and transmit ACK / NACK feedback during the third COT based on CAT4 LBT.

[0186] Aspect 17 includes a non-transient computer-readable medium storing one or more instructions for wireless communication, the one or more instructions including, when executed by one or more processors equipped by a first user, causing the one or more processors to execute any one of aspects 1-8.

[0187] Aspect 18 includes a non-transient computer-readable medium storing one or more instructions for wireless communication, the one or more instructions including, when executed by one or more processors equipped by a first user, causing the one or more processors to execute any one of aspects 9-16.

[0188] Aspect 19 includes a first user equipment (UE) comprising one or more means for performing any one or more of aspects 1-8.

[0189] Aspect 20 includes a first user equipment (UE) comprising one or more means for performing any one or more of aspects 9-16.

[0190] Information and signals can be represented using any of a wide variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0191] The various illustrative blocks and modules described herein can be implemented or executed using a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternatives, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration).

[0192] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Other examples and implementations fall within the scope of this disclosure and the appended claims. For example, due to the nature of software, the above-described functions may be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed such that different parts of the functions are implemented in different physical locations. Additionally, as used herein (including in the claims), the use of "or" in an enumeration of items (e.g., an enumeration of items accompanied by phrases such as "at least one of" or "one or more of") indicates an inclusive enumeration, such that an enumeration such as [at least one of A, B, or C] means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0193] As will be appreciated by those skilled in the art by this time, and depending on the specific application at hand, many modifications, substitutions, and variations can be made to the materials, apparatus, configuration, and methods of use of the devices disclosed herein without departing from the spirit and scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the specific aspects explained and described herein (which are merely examples of this disclosure), but should be fully equivalent to the appended claims and their functional equivalents.

Claims

1. A wireless communication method performed by a first user equipment (UE), the method comprising: During the first channel occupancy time (COT), a first sidelink transmission is received from the second UE, wherein the first COT is associated with the second UE; Determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission, wherein the second sidelink transmission is a multicast or broadcast transmission; as well as The second sidelink transmission is transmitted to the two or more UEs during a portion of the first COT based on COT sharing, wherein the COT sharing is in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

2. The method of claim 1, wherein: Receiving the first side link transmission includes: Receive sidelink control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; and The second sidelink transmission is transmitted during a portion of the first COT based on the COT sharing, and further based on the SCI indicating that the second UE is the initiating UE of the first COT.

3. The method of claim 1, wherein: Receiving the first side link transmission includes: The second UE receives side link control information (SCI), the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted; and During the portion of the first COT, the transmission of the second sidelink further indicates, based on the COT-SI, that the COT sharing in the first COT is permitted.

4. The method of claim 1, wherein transmitting the second side link transmission comprises: The second-side link transmission is transmitted in broadcast mode.

5. The method of claim 1, wherein transmitting the second side link transmission comprises: The second-side link is transmitted in a multicast mode.

6. The method of claim 1, further comprising: During the second COT, a third-side link transmission including data is received from the third UE; Determine whether the third UE is the initiating UE of the second COT; as well as In response to determining that the third UE is the initiating UE of the second COT, an ACK / NACK feedback on the data is transmitted during a portion of the second COT.

7. The method of claim 1, further comprising: During the second COT, a third-side link transmission including data is received from the third UE; Monitor COT-shared information associated with the second COT; as well as Based on the monitoring, it is determined whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

8. The method of claim 1, further comprising: Determine whether the second UE is one of two or more UEs intended to receive third-side link transmissions; as well as In response to determining that the second UE is not one of the two or more UEs intended to receive the third sidelink transmission, the transmission of the third sidelink transmission is suppressed during the portion of the first COT.

9. A first user equipment (UE), comprising: Memory; transceiver; as well as At least one processor coupled to the memory and the transceiver, wherein the first UE is configured to: During the first channel occupancy time (COT), a first sidelink transmission is received from the second UE, wherein the first COT is associated with the second UE; Determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission, wherein the second sidelink transmission is a multicast or broadcast transmission; as well as The second sidelink transmission is transmitted to the two or more UEs during a portion of the first COT based on COT sharing, wherein the COT sharing is in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

10. The first UE as claimed in claim 9, wherein: The first UE is further configured to: Receive sidelink control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; and Further, based on the SCI indicating that the second UE is the initiating UE of the first COT, the second sidelink transmission is transmitted during the portion of the first COT.

11. The first UE as claimed in claim 9, wherein: The first UE is further configured to: The second UE receives side link control information (SCI), the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted; and Furthermore, based on the COT-SI indication, the COT sharing in the first COT is permitted to transmit the second side link transmission during the portion of the first COT.

12. The first UE as claimed in claim 9, wherein the first UE is further configured to: The second-side link transmission is transmitted in broadcast mode.

13. The first UE as claimed in claim 9, wherein the first UE is further configured to: The second-side link is transmitted in a multicast mode.

14. The first UE as claimed in claim 9, wherein: The first UE is further configured to: During the second COT, a third-side link transmission including data is received from the third UE; Determine whether the third UE is the initiating UE of the second COT; as well as In response to determining that the third UE is the initiating UE of the second COT, an ACK / NACK feedback on the data is transmitted during a portion of the second COT.

15. The first UE as claimed in claim 9, wherein: The first UE is further configured to: During the second COT, a third-side link transmission including data is received from the third UE; Monitor COT-shared information associated with the second COT; as well as Based on the monitoring, it is determined whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

16. The first UE as claimed in claim 15, wherein: The first UE is further configured to: In response to determining that no COT-shared information associated with the second COT is detected from the monitoring, it is determined to suppress the transmission of the ACK / NACK feedback during the portion of the second COT. Execution Category 4 (CAT4) LBT; as well as The ACK / NACK feedback is transmitted during the third COT based on the CAT4 LBT.

17. A non-transient computer-readable medium having program code recorded thereon, the program code comprising: Code for enabling a first user equipment (UE) to receive a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; Code used to enable the first UE to determine whether the second UE is one of two or more UEs intended to receive a second sidelink transmission, wherein the second sidelink transmission is a multicast or broadcast transmission; as well as Code for enabling the first UE to transmit the second sidelink transmission to the two or more UEs during a portion of the first COT based on COT sharing, the COT sharing being in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

18. The non-transient computer-readable medium of claim 17, wherein: The code used to enable the first UE to receive the first sidelink transmission is configured as follows: Receive side link control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; as well as The code for enabling the first UE to transmit the second sidelink transmission during the portion of the first COT is configured to: Further, based on the SCI indicating that the second UE is the initiating UE of the first COT, the second sidelink transmission is transmitted during the portion of the first COT.

19. The non-transient computer-readable medium of claim 17, wherein: The code used to enable the first UE to receive the first sidelink transmission is configured as follows: The second UE receives side link control information (SCI), the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted; and The code for enabling the first UE to transmit the second sidelink transmission during the portion of the first COT is configured to: Furthermore, based on the COT-SI indication, the COT sharing in the first COT is permitted to transmit the second side link transmission during the portion of the first COT.

20. The non-transient computer-readable medium of claim 17, wherein the code for enabling the first UE to transmit the second sidelink transmission is configured to: The second-side link transmission is transmitted in broadcast mode.

21. The non-transient computer-readable medium of claim 17, wherein the code for enabling the first UE to transmit the second sidelink transmission is configured to: The second-side link is transmitted in a multicast mode.

22. The non-transient computer-readable medium of claim 17, further comprising: Code used to enable the first UE to receive a third-side link transmission including data from the third UE during the second COT; Code used to enable the first UE to determine whether the third UE is the initiating UE of the second COT; as well as Code used to cause the first UE to transmit an ACK / NACK feedback on the data during a part of the second COT in response to determining that the third UE is the initiating UE of the second COT.

23. The non-transient computer-readable medium of claim 17, further comprising: Code used to enable the first UE to receive a third-side link transmission including data from the third UE during the second COT; Code used to enable the first UE to monitor COT-shared information associated with the second COT; as well as Code used to enable the first UE to determine, based on the monitoring, whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

24. The non-transient computer-readable medium of claim 17, wherein the program code further comprises: Code used to enable the first UE to determine whether the second UE is one of two or more UEs intended to receive third sidelink transmissions; as well as Code for causing the first UE to suppress transmission of the third sidelink transmission during the portion of the first COT in response to determining that the second UE is not one of the two or more UEs intended to receive the third sidelink transmission.

25. A first user equipment (UE), comprising: A means for receiving a first sidelink transmission from a second UE during a first channel occupancy time (COT), wherein the first COT is associated with the second UE; A means for determining whether the second UE is one of two or more UEs intended to receive a second sidelink transmission, wherein the second sidelink transmission is a multicast or broadcast transmission; as well as Means for transmitting a second sidelink transmission to two or more UEs during a portion of a first COT based on COT sharing, wherein the COT sharing is in response to determining that the second UE is one of the two or more UEs intended to receive the second sidelink transmission.

26. The first UE as claimed in claim 25, wherein: The means for receiving the transmission from the first side link is configured to: Receive sidelink control information (SCI) from the second UE indicating whether the second UE is the initiating UE of the first COT; and The means for transmitting the second side link transmission during said portion of the first COT is configured to: Further, based on the SCI indicating that the second UE is the initiating UE of the first COT, the second sidelink transmission is transmitted during the portion of the first COT.

27. The first UE as claimed in claim 25, wherein: The means for receiving the transmission from the first side link is configured to: The second UE receives side link control information (SCI), the SCI including a COT structure indicator (COT-SI) indicating whether COT sharing in the first COT is permitted; and The means for transmitting the second side link transmission during said portion of the first COT is configured to: Furthermore, based on the COT-SI indication, the COT sharing in the first COT is permitted to transmit the second side link transmission during the portion of the first COT.

28. The first UE of claim 25, wherein the means for transmitting the second side link transmission is configured to: The second-side link transmission shall be transmitted in at least one of the following manner: Broadcast mode; or Group broadcast mode.

29. The first UE as claimed in claim 25, further comprising: A means for receiving third-side link transmissions, including data, from a third UE during a second COT; A means for determining whether the third UE is the initiating UE of the second COT; as well as A means for transmitting ACK / NACK feedback on the data during a portion of the second COT in response to determining that the third UE is the initiating UE of the second COT.

30. The first UE as claimed in claim 25, further comprising: A means for receiving third-side link transmissions, including data, from a third UE during a second COT; A means for monitoring COT-shared information associated with the second COT; as well as A means for determining, based on the monitoring, whether to transmit ACK / NACK feedback on the data during a portion of the second COT.

Images