Channel Occupancy Time Sharing for Sidelink Transmissions

Abstract

Provides channel occupancy time sharing for sidelink transmissions. [Solution] Exemplary embodiments of the present disclosure relate to terminal devices, methods, apparatuses, and computer-readable storage media for channel occupation time sharing for sidelink transmissions. A first terminal device initiates a channel occupation time (COT) by performing an LBT procedure associated with CAPC, transmits a COT indication for SL transmissions between the multiple terminal devices to multiple terminal devices, and detects the SL transmissions during the COT. Thus, the first terminal device can recognize information about the SL transmissions during the COT, and the information can be used to adjust the CW, for example. As a result, communication efficiency of the SL transmissions can be improved.

Description

[Technical Field]

[0001] Exemplary embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to terminal devices, methods, apparatus, and computer-readable storage media for channel occupation time sharing for sidelink transmissions. [Background technology]

[0002] Given the scarcity and expense of bandwidth in licensed spectrum and the increasing demand for data transmission capacity, there is growing interest in offloading at least some communication traffic to unlicensed spectrum. Listen-Before-Talk (LBT) has been proposed, whereby a device intending to transmit must first successfully complete an LBT check before it can begin transmitting. LBT is sometimes referred to as Clear Channel Assessment (CCA).

[0003] It is proposed to consider and specify support for sidelink unlicensed (SL-U) spectrum, and sidelink extensions still need to be considered. Summary of the Invention

[0004] Generally, the exemplary embodiments of the present disclosure provide a solution for channel occupation time sharing for sidelink transmissions.

[0005] In a first aspect, a first terminal device is provided, the first terminal device comprising: at least one processor; and at least one memory that stores instructions that, when executed by the at least one processor, cause the first terminal device to perform at least the following steps: initiating a channel occupation time (COT) by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); transmitting, to a plurality of terminal devices, an indication of the COT for a sidelink (SL) transmission among the plurality of terminal devices; and detecting an SL transmission during the COT.

[0006] In a second aspect, a second terminal device is provided, the second terminal device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second terminal device to perform at least the following steps: transmitting traffic information to one of the first terminal device or a network device; receiving from the first terminal device an indication of a channel occupation time (COT) initiated by the first terminal device; and transmitting a sidelink (SL) transmission to a third terminal device during the COT.

[0007] In a third aspect, a network device is provided, the network device comprising: at least one processor; and at least one memory that stores instructions that, when executed by the at least one processor, cause the network device to perform at least the step of sending, to a first terminal device, a start command instructing the first terminal device to start a channel occupation time (COT), the start command including at least one of a channel access priority class (CAPC), a plurality of identifiers of the plurality of terminal devices, traffic information of side link (SL) transmissions between the plurality of terminal devices, or timing information for starting the COT.

[0008] In a fourth aspect, a method is provided that is performed by a first terminal device, the method including: initiating a channel occupation time (COT) by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC) at the first terminal device; transmitting an indication of the COT for a sidelink (SL) transmission among the plurality of terminal devices to a plurality of terminal devices; and detecting the SL transmission during the COT.

[0009] In a fifth aspect, there is provided a method performed by a second terminal device, the method including: transmitting, at the second terminal device, traffic information to at least one of a first terminal device or a network device, receiving from the first terminal device an indication of a channel occupation time (COT) initiated by the first terminal device, and transmitting a sidelink (SL) transmission to a third terminal device during the COT.

[0010] In a sixth aspect, there is provided a method performed by a network device, the method including: sending a start command to a first terminal device, instructing the first terminal device to start a channel occupation time (COT), the start command including at least one of a channel access priority class (CAPC), a plurality of identifiers of a plurality of terminal devices, traffic information of side link (SL) transmissions between the plurality of terminal devices, or timing information for starting the COT.

[0011] In a seventh aspect, an apparatus is provided, the apparatus including: means for initiating a channel occupation time (COT) at a first terminal device by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC), means for transmitting an indication of the COT for a sidelink (SL) transmission among the plurality of terminal devices to a plurality of terminal devices, and means for detecting the SL transmission during the COT.

[0012] In an eighth aspect, an apparatus is provided, the apparatus including: means, at a second terminal device, for transmitting traffic information to at least one of a first terminal device or a network device, means for receiving from the first terminal device an indication of a channel occupation time (COT) initiated by the first terminal device, and means for transmitting a sidelink (SL) transmission to a third terminal device during the COT.

[0013] In a ninth aspect, an apparatus is provided, the apparatus including: means for transmitting, to a first terminal device, a start command instructing the first terminal device to start a channel occupation time (COT), the start command including at least one of an access priority class (CAPC), a plurality of identifiers of a plurality of terminal devices, traffic information of a side link (SL) transmission between the plurality of terminal devices, or timing information for starting the COT.

[0014] In a tenth aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any of the fifth to eighth aspects.

[0015] In an eleventh aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the method of any of the fifth to eighth aspects.

[0016] In a twelfth aspect, a first terminal device is provided, the first terminal device including: an initiating circuit configured to initiate a COT by performing an LBT procedure associated with a CAPC; a transmitting circuit configured to transmit, to a plurality of terminal devices, an indication of the COT for an SL transmission between the plurality of terminal devices; and a detecting circuit configured to detect the SL transmission during the COT.

[0017] In a thirteenth aspect, a second terminal device is provided, the second terminal device including: a transmitting circuit configured to transmit traffic information to at least one of the first terminal device or a network device; a receiving circuit configured to receive, from the first terminal device, an indication of a COT initiated by the first terminal device; and a transmitting circuit configured to transmit an SL transmission to a third terminal device during the COT.

[0018] In a fourteenth aspect, a network device is provided, the network device including: a transmitting circuit configured to transmit a start command to a first terminal device, the start command instructing the first terminal device to start a channel occupation time (COT), the start command including at least one of a channel access priority class (CAPC), a plurality of identifiers of a plurality of terminal devices, traffic information of a side link (SL) transmission between the plurality of terminal devices, or timing information for starting the COT.

[0019] It should be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description.

[0020] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0021] [Figure 1A] 1 illustrates an example of a network environment in which some exemplary embodiments of the present disclosure may be implemented. [Figure 1B] 1 illustrates an example scenario in which some example embodiments of the present disclosure may be implemented. [Figure 1C] 1 illustrates an example scenario in which some example embodiments of the present disclosure may be implemented. [Figure 2A] 1 illustrates an example diagram of a CCA slot in which some example embodiments of the present disclosure may be implemented. [Figure 2B] 1 shows an example diagram of an acquisition of a COT by an initiating device via a Type 1 LBT, in which some example embodiments of the present disclosure may be implemented. [Figure 3A] 10A-10C illustrate some examples of Type 1 LBT CW countdown procedures in which some exemplary embodiments of the present disclosure may be implemented. [Figure 3B]10A-10C illustrate some examples of tolerance gaps for Type 2 LBT, in which some exemplary embodiments of the present disclosure may be implemented. [Figure 3C] 1 illustrates an example of a relationship between LBT bandwidth and sub-channel bandwidth for SL-U in which some exemplary embodiments of the present disclosure may be implemented. [Figure 4A] 1 illustrates an example of a process flow according to some exemplary embodiments of the present disclosure. [Figure 4B] 10 illustrates another example of a process flow according to some exemplary embodiments of the present disclosure. [Figure 5] 10 illustrates another example of a process flow according to some exemplary embodiments of the present disclosure. [Figure 6] 1 illustrates an example frame structure according to some example embodiments of the present disclosure. [Figure 7] 1 illustrates a flowchart of a method implemented in a first terminal device, according to some example embodiments of the present disclosure. [Figure 8] 10 illustrates a flowchart of a method implemented in a second terminal device, according to some example embodiments of the present disclosure. [Figure 9] 1 illustrates a flowchart of a method implemented in a network device, according to some example embodiments of the present disclosure. [Figure 10] FIG. 1 shows a simplified block diagram of a device suitable for implementing some exemplary embodiments of the present disclosure. [Figure 11] 1 illustrates a block diagram of an example computer-readable medium in accordance with some exemplary embodiments of the present disclosure.

[0022] Throughout the drawings, the same or similar reference numbers refer to the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0023] The principles of the present disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are provided for illustrative purposes only, to assist those skilled in the art in understanding and practicing the present disclosure, but do not imply any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0024] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0025] References in this disclosure to "one embodiment," "embodiment," "exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments need include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, it is submitted that when a particular feature, structure, or characteristic is described in connection with one embodiment, it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0026] While the terms "first," "second," and the like may be used herein to describe various elements, it should be understood that these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0027] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, it will be understood that the terms "comprises," "comprising," "has," "having," "includes," and / or "including," when used herein, specify the presence of stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. As used herein, "at least one of" refers to "a list of two or more elements" and "at least one of " and similar phrases, where a list of two or more elements is joined by "and" or "or," meaning at least one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0028] As used in this application, the term "circuit" may refer to one or more or all of the following: (a) Hardware-only circuit implementation (e.g., implementation using only analog and / or digital circuits) (b) Combinations of hardware circuits and software, e.g. (where applicable) (i) a combination of analog and / or digital hardware circuitry and software / firmware; (ii) Any portion of a hardware processor with software (including a digital signal processor, software, and memory that work together to cause a device, such as a mobile phone or server, to perform various functions). (c) A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (e.g., firmware) to operate; however, the software may be absent when not required for operation.

[0029] This definition of circuit applies to all uses of the term in this application, including any claims. As a further example, the term circuit, as used in this application, also encompasses simply a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor, as well as its (or their) accompanying software and / or firmware implementations. The term circuit also encompasses, for example, a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to certain claim elements.

[0030] As used herein, the term "communication network" refers to a network conforming to any suitable communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), or Narrowband Internet of Things (NB-IoT). Furthermore, communications between terminal devices and network devices in a communication network may be performed according to any suitable generation of communication protocols, including, but not limited to, first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, future fifth-generation (5G) communication protocols, and / or any other protocols currently known or developed in the future. Embodiments of the present disclosure may be applied to various communication systems. Given the rapid development of communications, there will naturally be future types of communication technologies and systems in which the present disclosure can be embodied. This should not be understood as limiting the scope of the present disclosure to only the aforementioned systems.

[0031] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services therefrom. A network device may refer to a base station (BS) or access point (AP), e.g., a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a new radio (NR) NB (also referred to as gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), an integrated access backhaul (IAB) node, a relay, and, depending on the terminology and technology applied, low-power nodes such as femto, pico, etc.

[0032] The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, voice-over-IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback equipment, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop embedded equipment (LEEs), laptop mounted equipment (LMEs), USB dongles, smart devices, wireless customer premises equipment (CPEs), Internet of Things (IoT) devices, machine-type communication (MTC) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain contexts), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. In the following description, the terms “terminal device,” “communications device,” “terminal,” “user equipment,” and “UE” may be used interchangeably.

[0033] It is proposed to consider and specify support for sidelink over unlicensed spectrum in Release-18. The following text box provides some non-limiting introductory information for SL-U that may be used in some example embodiments of the present disclosure. [R18 Work Item (RP-213678)] 2. Study and specify support for sidelink over unlicensed spectrum for both Mode 1 and Mode 2, where Uu operation for Mode 1 is limited to licensed spectrum only [RAN1, RAN2, RAN4] The channel access mechanism from NR-U should be reused for sidelink unlicensed operation. Evaluate the applicability of sidelink resource reservation to unlicensed channel access mechanisms and sidelink unlicensed operation within the boundaries of operation from Rel-16 / Rel-17 No specific extensions to the Rel-17 resource allocation mechanism If the existing NR-U channel access framework does not support the required SL-U functionality, the WG will make appropriate recommendations for RAN approval. Physical Channel Design Framework: Required changes to NR sidelink physical channel structure and procedures for operation over unlicensed spectrum The existing NR sidelink and NR-U channel structure shall be reused as a baseline. -No specific extensions to existing NR SL features This study should focus on the FR1 unlicensed bands (n46 and n96 / n102) and should be completed by RAN#98.

[0034] In sub-7 GHz unlicensed bands, new radio (NR) coexistence with other systems (such as Institute of Electrical and Electronics Engineers (IEEE) 802.11) is ensured via the LBT channel access mechanism. A user equipment (UE) intending to perform a sidelink (SL) transmission must first successfully complete an LBT check before it can begin that same transmission; the UE may be referred to in some embodiments as an SL UE.

[0035] For unlicensed spectrum operation, an SL UE can acquire the “right” to access the channel via Type 1 LBT for a period of time, denoted as the channel occupation time (COT) for SL transmission (i.e., initiate the COT), or can share the COT initiated by another UE to acquire the channel via a “reduced” LBT procedure (e.g., Type 2 LBT) for SL transmission. Clearly, the “reduced” LBT (i.e., Type 2A / 2B / 2C LBT) procedure would be more friendly to SL UEs (e.g., sensor devices, low-cost MTC devices, or even low-cost terminal devices) in terms of power consumption, latency, and capability requirements. For this reason, it makes sense for a device with at least Type 1 LBT capability to initiate the COT and then share the COT with other SL UEs for SL transmission in the unlicensed spectrum.

[0036] Exemplary embodiments of the present disclosure provide a solution for SL-U. In particular, a first terminal device initiates a COT by performing an LBT procedure associated with a channel access priority class (CAPC), shares the COT with other terminal devices, and may detect sidelink transmissions during the COT. Thus, the first terminal device can recognize information about SL transmissions during the COT, and the information can be used to adjust CWs, for example. As a result, communication efficiency of SL transmissions can be improved. The principles and exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0037] 1A illustrates an example of a network environment 100 in which some exemplary embodiments of the present disclosure may be implemented. The network environment 100 may include a first terminal device 110, a plurality of terminal devices 120, and a network device 130. The network device 130 may provide a wireless access cell through which the first terminal device 110 and each of the plurality of terminal devices 120 may communicate with the network device 130. In some exemplary embodiments, the network device 130 may be a gNB providing a 3GPP® NR cell. In other exemplary embodiments, the network device 130 may be an eNB providing an LTE cell. The air interface through which the first terminal device 110, the plurality of terminal devices 120, and the network device 130 communicate may be compatible with 3GPP® technical specifications, such as those defining fifth-generation (5G) NR system standards.

[0038] 1A, the plurality of terminal devices 120 includes terminal device 120-1, terminal device 120-2, ..., terminal device 120-M. It should be noted that the number M may be any suitable natural number. It should be understood that the number of network devices and terminal devices is for illustrative purposes only, without implying any limitation. The network environment 100 may include any suitable number of network devices and terminal devices adapted to implement embodiments of the present disclosure. It should be noted that some example embodiments of the present disclosure may be implemented without the presence of network device 130.

[0039] The first terminal device 110 and the plurality of terminal devices 120 may also communicate directly with each other via a sidelink interface. The sidelink interface may alternatively be referred to as a ProSe interface, a device-to-device (D2D) interface, a user-to-user (U2U) interface, or a ProSe Communication 5 (PC5) interface. In some demonstrative embodiments, the network environment 100 may be deployed within a vehicular communication system. In the vehicular communication system, the first terminal device 110 and the plurality of terminal devices 120 may communicate with each other using cellular vehicle-to-everything (V2X) communication. V2X may involve vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (VTN), or vehicle-to-pedestrian (V2P) communication. Thus, while FIG. 1A illustrates the first terminal device 110 and the plurality of terminal devices 120 as mobile phones, the first terminal device 110 and the plurality of terminal devices 120 may be any type of user equipment.

[0040] In some demonstrative embodiments, the transmission link between the first terminal device 110 and any of the plurality of terminal devices 120 may be denoted as a sidelink (SL).

[0041] 1A is for illustrative purposes only, without implying any limitation on the scope of the present disclosure. For example, in other embodiments, the first terminal device 110 may be replaced by another network device, such as a base station.

[0042] Communications in network environment 100 may be implemented according to any suitable communications protocol, including, but not limited to, cellular communications protocols such as first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), wireless local network communications protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol now known or developed in the future. Furthermore, communications may utilize any suitable wireless communications technology, including, but not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiple access (OFDM) discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology now known or developed in the future.

[0043] In the following description, the first terminal device 110 can be considered as a head device of the plurality of terminal devices 120. In some exemplary embodiments, the first terminal device 110 may be referred to as a cluster head (CH) device, and the plurality of terminal devices 120 may be referred to as cluster member (CM) devices. In some embodiments, the plurality of terminal devices 120 may be divided into one or more clusters according to a cluster configuration from the network device 130. In some embodiments, the first terminal device 110 and the plurality of terminal devices 120 may be within the coverage of the network device 130.

[0044] 1B illustrates an example of a network environment 105 in which some exemplary embodiments of the present disclosure may be implemented. The network environment 105 may include a first terminal device 110 and terminal devices 120-1 to 120-5. As illustrated in FIG. 1B, the first terminal device 110 and the terminal devices 120-1 to 120-5 are located in a vehicle. There are two clusters illustrated in FIG. 1B, where the first cluster includes terminal devices 120-1 and 120-2 and the second cluster includes terminal devices 120-3 to 120-5.

[0045] In some exemplary embodiments, the first terminal device 110 (CH device) may be responsible for LBT clearance to obtain COT for multiple terminal devices 120-1 to 120-5 (i.e., one or more groups of CM devices) intended for an in-vehicle SL communication scenario. In some examples, each of the multiple terminal devices 120-1 to 120-5 may be a sensor device, a low-cost MTC device, or a low-cost UE terminal device. In some examples, each of the multiple terminal devices 120-1 to 120-5 may have capability limitations for LBT operation. For example, only Type 2 LBT (e.g., Type 2 CLBT) is supported for cost reduction in the multiple terminal devices 120-1 to 120-5.

[0046] 1B is for illustrative purposes only, without implying any limitation as to the scope of the present disclosure. For example, in other embodiments, network device 130 may be present.

[0047] For example, the first terminal device 110 and the plurality of terminal devices 120 may be located in other scenarios. As a non-limiting example, the first terminal device 110 may be a device with smart home technology, such as an air conditioner or a refrigerator in a home, which may have LBT capabilities and act as a CH device. The plurality of terminal devices 120 may be sensors installed in a home window curtain. In some examples, the first terminal device 110 may be responsible for obtaining unlicensed channel access for the plurality of terminal devices 120, such as sensors for opening and closing a home window curtain.

[0048] 1C illustrates an example of a network environment 115 in which some exemplary embodiments of the present disclosure may be implemented. The network environment 115 may include a first terminal device 110 and terminal devices 120-1 through 120-5. As shown in FIG. 1C, assume that data transmission may occur between terminal devices 120-1 and 120-2, and another data transmission may occur between terminal devices 120-3 and 120-4, which are shown by solid lines in FIG. 1C. In addition, there may be control signaling from the first terminal device 110 to any of terminal devices 120-1 through 120-4, which are shown by dashed lines in FIG. 1C.

[0049] In some exemplary embodiments, the transmission channel between two different terminal devices may be either a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), or a Physical Sidelink Feedback Channel (PSFCH).

[0050] 1C is for illustrative purposes only, without implying any limitation on the scope of the present disclosure. For example, in other embodiments, there may be a network device 130. For example, in other embodiments, there may be data transmission from the first terminal device 110 to one of the terminal devices 120-1 through 120-5.

[0051] For a terminal device to pass the LBT check, the terminal device must observe the channel as available for several consecutive durations. The total duration of the consecutive durations may be referred to as the contention window (CW) duration. One of the durations within the CW duration may be referred to as a CCA slot or sensing slot, and the length of the CCA slot is T sl FIG. 2A shows an example diagram 210 of a CCA slot in sub-7 GHz. As shown in FIG. 2A, the length of the CCA slot 214 is T sl =9μs.

[0052] In some demonstrative embodiments, a terminal device may consider a channel available in a CCA slot if the measured power is below a regulatory specified threshold. With reference to FIG. 2A, the terminal device may measure the power within duration 212 (e.g., 4 μs in FIG. 2A), and the terminal device may determine that the channel is available if the measured power is below the threshold. In some embodiments, the threshold may depend on the operating band and / or geographic region, and the present disclosure is not limited in this respect.

[0053] In the context of this disclosure, the term "initiating device" may refer to a device that initiates a COT for a sidelink transmission using a Type 1 LBT procedure, and the term "responding device" may refer to a device that shares a COT for a sidelink transmission using a reduced LBT type. In the context of this disclosure, the terms "sidelink (SL) transmission" and "SL communication" may be used interchangeably. In the context of the present disclosure, the term "Type 1 LBT" may also be referred to as LBT Type 1, extended LBT, etc., and the term "Type 2 LBT" may also be referred to as LBT Type 2, reduced LBT, etc. In some embodiments, extended LBT and reduced LBT may refer to those described in TS 37.213 and will not be repeated here.

[0054] When a terminal device (initiating device) initiates communication, the terminal device may perform a Type 1 LBT to obtain the right to access the channel for a certain period of time, i.e., to initiate a COT. Figure 2B shows an example diagram 220 of an initiating device obtaining a COT via a Type 1 LBT. As shown in Figure 2B, the initiating device may perform a Type 1 LBT during a CW duration 222, and communication may be performed during a subsequent COT 224.

[0055] In some exemplary embodiments, the maximum duration of the COT and the size of the CW duration may depend on the channel access priority class (CAPC) associated with the terminal device's traffic, as shown in Table 1. In some embodiments, control plane traffic (such as the PSCCH) is transmitted with p=1, while user plane traffic has p>1. [Table 1]

[0056] A detailed description of Table 1 can be found in "Table 4.2.1-1: UL Channel Access Priority Class (CAPC)" in TS.37.213, and therefore will not be repeated herein. In some examples, the size of the CW duration may refer to the number of CCA slots within the CW duration, for example, the size of the CW duration may be indicated as N, which is an integer. In some examples, the size of the CW duration may be referred to as the CW size, CW size, or CW for short. The CW in the CCA slot associated with each CAPC is limited to a minimum value (CW min,p ) and maximum value (CW max,p ) and the duration of the COT can be T ulm cot,p It should be understood that the LBT parameter can be given by: Table 1 shows the details of Type 1 LBT for Uu uplink (UL) that can be adopted in SL. However, it should be understood that the downlink (DL) case Type 1 LBT parameters or any other parameters can also be adopted in SL and will not be repeated here.

[0057] 3A illustrates several examples of a Type 1 LBT CW countdown procedure 310 in which some exemplary embodiments of the present disclosure may be implemented. In some exemplary embodiments, as shown in FIG. 3A(a), a deferral time (T dIf the channel is detected as free during the deferral time (denoted as T), the CW countdown procedure is performed. If neither the deferral time nor the countdown is interrupted (i.e., the channel is not detected as busy during the sensing slot), the Type 1 LBT ends and SL transmission may continue. In some exemplary embodiments, as shown in FIG. 3A(b), if the deferral time is interrupted, i.e., the channel is detected as busy during the deferral time sensing slot, another deferral time is further detected until it is free. In some exemplary embodiments, as shown in FIG. 3A(c), if the channel is detected as free during the deferral time and the countdown is interrupted, i.e., the channel is detected as busy during the countdown sensing slot (the LBT check is performed during the CCA slot (T), the LBT check is performed. sl )), the countdown stops and resumes if the channel is deemed free for another deferral time. In some embodiments, N in FIG. 3A refers to the number of CCA slots that must be deemed free before the contention window countdown is complete.

[0058] In NR-U, the terminal device uses the contention window value CW p maintains the CW for its transmission before the Type 1 LBT procedure associated with channel access priority class p. p In some embodiments, the terminal device may adjust the CW based on the success or failure of receiving a PUSCH (such as an UL HARQ-ACK feedback) in the previous COT, as specified in TS37.213. p can be adjusted.

[0059] In some embodiments, upon successful completion of the Type 1 LBT, the initiating device can obtain a COT with the maximum duration associated with the corresponding CAPC, and thus the initiating device can perform a transmission. In some embodiments, the obtained COT remains valid even if the initiating device pauses its transmission. In some embodiments, if the initiating device wants to perform a new transmission within the obtained COT, it is still required to perform a reduced LBT procedure.

[0060] In some exemplary embodiments, the initiating device may share the acquired COT with its intended receiver, i.e., the responding device. To this end, the initiating device shall inform the responding device (e.g., via control signaling) about the remaining duration of the COT. When the responding device intends to perform a transmission with the initiating device, the responding device may determine which type of LBT to apply based on the shared COT from the initiating device. In some examples, if the responding device's intended transmission falls within the range of the COT, a reduced LBT may be performed by the responding device.

[0061] 3B illustrates some examples of allowed gaps for a Type 2 LBT 320 in which some exemplary embodiments of the present disclosure may be implemented. In FIG. 3B, (a), (b), and (c) illustrate cases where the gap is between two transmissions, both from the initiating UE, and (d), (e), and (f) illustrate cases where the gap is between two different transmissions, respectively, from the initiating UE and the responding UE.

[0062] In some other exemplary embodiments, the reduced LBT may be referred to as Type 2 LBT, and may include Type 2 ALBT, Type 2 BLBT, and Type 2 CLBT. Type 2A (25 μs LBT): An SL transmission within the acquired COT (an SL transmission following another SL transmission) when the gap between the two SL transmissions is 25 μs or more, as shown in (c) and (f) of Figure 3B. Type 2B (16 μs LBT): An SL transmission within the acquired COT (an SL transmission following another SL transmission) when the gap is exactly equal to 16 μs, as shown in Figure 3B (b) and (e). Type 2C (without LBT): SL transmission within the obtained COT (SL transmission following another SL transmission) when the gap is less than 16 μs and the allowed duration of the SL transmission is less than 584 μs, as shown in Figure 3B (a) and (d).

[0063] In some other exemplary embodiments, if the intended subsequent transmission is outside the obtained COT, another Type 1 LBT should be performed to obtain a new COT.

[0064] In some exemplary embodiments, for SL single-carrier operation in Release-16 or Release-17, a terminal device bases its resource selection on sensing results using a resource pool (RP) for resource allocation (RA) mode 2. In some examples, the RP may be further divided into subchannels in the frequency domain, and each subchannel may consist of a contiguous, non-overlapping set of at least 10 physical resource blocks (PRBs) in a slot. In some embodiments, SL RA mode-2 resource allocation, sensing, and resource selection may be performed on a subchannel basis.

[0065] In some exemplary embodiments, the LBT bandwidth in the frequency domain is typically 20 MHz in Release-16 NR-U. In some embodiments, the 20 MHz LBT bandwidth may correspond to an RP bandwidth with multiple subchannels for SL operation in unlicensed spectrum. FIG. 3C illustrates an example relationship 330 between the LBT bandwidth and subchannel bandwidth for SL-U, in which some exemplary embodiments of the present disclosure may be implemented. As shown in FIG. 3C, there are five subchannels configured within the transmitter / receiver (TX / RX) RP, and each subchannel may consist of 10 PRBs by assuming a subcarrier spacing (SCS) of 30 kHz.

[0066] Additionally, multiple subchannels may be assigned to different terminal devices for SL communications.

[0067] Based on the above description, in the case of unlicensed spectrum operation, a terminal device can acquire a channel via Type 1 LBT by itself to initiate a COT, or the terminal device can acquire a channel via Type 2 LBT within a COT shared by another terminal device. It is understood that Type 2 LBT may be preferable for a terminal device in terms of power consumption, latency, and capacity requirements. The principles and some exemplary embodiments of the present disclosure are described in detail below with reference to FIGS. 4 to 10.

[0068] 4A shows an example of a process flow 400 according to some example embodiments of the present disclosure. For purposes of explanation, the process flow 400 will be described with reference to FIG. 1A. The process flow 400 includes a first terminal device 110, a terminal device 120-1, and a terminal device 120-2. In some embodiments, the terminal device 120-1 may be referred to as a second terminal device, and the terminal device 120-2 may be referred to as a third terminal device. While the process flow 400 is described in the network environment 100 of FIG. 1A, it will be understood that the process flow may be similarly applied to other communication scenarios.

[0069] In process flow 400, the first terminal device 110 initiates COT by performing an LBT procedure associated with CAPC (410). In some embodiments, the LBT procedure may be a Type 1 LBT procedure or may also be referred to as a Type 1 LBT. In some embodiments, the first terminal device 100 has Type 1 LBT capabilities.

[0070] In some exemplary embodiments, the first terminal device 110 may receive a start command from the network device 130 and start the COT based on the start command. A detailed description may refer to the discussion with reference to FIG. 5 below.

[0071] In some exemplary embodiments, the CAPC may be a fixed CAPC. In some examples, the CAPC may be predefined in the first terminal device 110. In some other examples, the CAPC may be preconfigured by the network device 130. For example, the network device 130 may determine the CAPC during cluster configuration and send the CAPC to the first terminal device 110.

[0072] In some examples, the predefined or preconfigured CAPC may be the lowest CAPC among multiple preconfigured CAPCs, and thus the first terminal device 110 may always be given priority access to the terminal device 120.

[0073] In some examples, the predefined or preconfigured CAPC may be the highest CAPC among multiple preconfigured CAPCs, and thus the first terminal device 110 may provide lower priority access to the terminal device 120 (compared to the lowest CAPC), but the initiated COT may be longer.

[0074] In some exemplary embodiments, the CAPC may be determined based on traffic information. For example, the CAPC may be determined by the first terminal device 110 or may be determined by the network device 130.

[0075] In some examples, at least one of the terminal devices 120 may transmit traffic information to the first terminal device 110, and thus the first terminal device 110 may receive traffic information from at least one of the terminal devices 120, and the first terminal device 110 may determine a CAPC based on the received traffic information.

[0076] In some other examples, at least one of the terminal devices 120 may transmit traffic information to the network device 130, and thus the network device 130 may receive the traffic information from at least one of the terminal devices 120. The network device 130 may further transmit the traffic information to the first terminal device 110, and thus the first terminal device 110 may receive the traffic information and determine a CAPC based on the received traffic information.

[0077] In some other examples, the network device 130 may determine traffic information based on categories of the multiple terminal devices 120, for example, during cluster configuration. The network device 130 may transmit the determined traffic information to the first terminal device 110, so that the first terminal device 110 may receive the traffic information and determine a CAPC based on the received traffic information.

[0078] In some embodiments, the first terminal device 110 may determine the CAPC based on the received traffic information and further based on one or more of the channel load, the expected COT.

[0079] In some other examples, at least one of the terminal devices 120 may transmit traffic information to the network device 130, so that the network device 130 may receive the traffic information from the at least one of the terminal devices 120, and further, the network device 130 may determine a CAPC based on the received traffic information. The network device 130 may further transmit the determined CAPC to the first terminal device 110, so that the first terminal device 110 may receive the CAPC.

[0080] In some other examples, the network device 130 may determine traffic information based on categories of the multiple terminal devices 120, for example, during cluster configuration. The network device 130 may determine a CAPC based on the determined traffic information. The network device 130 may further transmit the determined CAPC to the first terminal device 110, so that the first terminal device 110 may receive the CAPC.

[0081] In some exemplary embodiments, the CAPC may be determined by the first terminal device 110. In some examples, the first terminal device 110 may select a CAPC from a plurality of pre-configured CAPCs.

[0082] For example, the selected CAPC may be the highest CAPC among multiple preconfigured CAPCs. In some examples, if the first terminal device 110 does not know the traffic information of multiple terminal devices 120, the first terminal device 110 may select the highest CAPC.

[0083] In some embodiments, the plurality of preconfigured CAPCs may include 1, 2, 3, and 4, as described in Table 1. In some embodiments, traffic information transmitted from at least one of the terminal devices 120 to the first terminal device 110 may be carried in a buffer status report (BSR). In some embodiments, the traffic information may indicate a traffic type (or types) associated with a category of the plurality of terminal devices 120.

[0084] In some embodiments, there may be a default CAPC stored (or predefined or preconfigured) in the first terminal device 110. In some embodiments, there may be the same default CAPC in multiple terminal devices 120.

[0085] In some demonstrative embodiments, the first terminal device 110 may initiate (or determine) the COT. In some examples, the first terminal device 110 may determine the maximum COT and size of the CW (between the minimum contention window and the maximum contention window) based on the CAPC, and the first terminal device 110 may perform Type 1 LBT based on the CW to initiate the COT.

[0086] In process flow 400, a first terminal device 110 transmits (420) a COT 421 instruction to multiple terminal devices 120, including terminal device 120-1 and terminal device 120-2, as shown in Figure 4A. Thus, terminal device 120-1 may receive (422) the COT 421 instruction, and terminal device 120-2 may receive (424) the COT 421 instruction.

[0087] In some embodiments, the indication of COT 421 may be transmitted via control signaling, such as sidelink control information (SCI) or sequence-based signaling.

[0088] Alternatively or additionally, the first terminal device 110 may send the CAPC indication to the multiple terminal devices 120. In some embodiments, the CAPC indication may be sent through control signaling. In some embodiments, the COT indication and the CAPC indication may be carried in the same signaling.

[0089] In some exemplary embodiments, an indication of CAPC may not be sent from the first terminal device 110 to the plurality of terminal devices 120. In some examples, if the CAPC determined by the first terminal device 110 is the same as the default CAPC, the CAPC may not be indicated, thus reducing signaling overhead.

[0090] In some demonstrative embodiments, it is assumed that there is an SL transmission initiated by terminal device 120-1. Alternatively or additionally, terminal device 120-1 may determine 430 a traffic type of the SL transmission to be performed during the COT.

[0091] In some embodiments, if a CAPC indication is transmitted, terminal device 120-1 may determine the traffic type of the SL transmission to be performed based on the indicated CAPC.

[0092] In some embodiments, in the absence of a CAPC instruction transmitted from the first terminal device 110, the terminal device 120-1 may determine a default (or predefined or preconfigured) CAPC and further determine the traffic type of the SL transmission to be performed based on the default CAPC.

[0093] In process flow 400, terminal device 120-1 transmits 440 an SL transmission 442 to terminal device 120-2 during the COT. On the other side of the communication, terminal device 120-2 receives 444 the SL transmission 442. Specifically, terminal device 120-1 may transmit 442 based on the resource selection and the indicated COT.

[0094] In some exemplary embodiments, SL transmissions 442 performed within the COT may be limited by the traffic type determined in 430. In some exemplary embodiments, SL transmissions 442 within the COT may be limited to groupcast and / or unicast transmissions, although this disclosure is not limited in this respect. In some exemplary embodiments, SL transmissions 442 may be transmitted over a PSCCH or PSSCH, although this disclosure is not limited in this respect.

[0095] Terminal device 120-2 transmits 450 feedback information 452 of the SL transmission to terminal device 120-1. Accordingly, terminal device 120-1 receives 454 the feedback information 452. In some exemplary embodiments, feedback information 452 may be transmitted via a PSCCH or a PSFCH.

[0096] Alternatively or additionally, terminal device 120-1 or terminal device 120-2 may perform a further SL transmission after the Type 2 LBT procedure within the indicated COT.

[0097] Therefore, a first terminal device 110 having at least Type 1 LBT capability can initiate a COT, and the COT can be shared with other terminal devices 120 for SL transmission in the unlicensed band. Thus, the terminal device 120 does not need to perform Type 1 LBT, and power consumption in the terminal device 120 can be reduced.

[0098] 4A, the first terminal device 110 detects an SL transmission during the COT (460). In some demonstrative embodiments, the first terminal device 110 may detect the SL transmission and determine a detection result.

[0099] In some exemplary embodiments, the detection result may include one or more of an SCI associated with the SL transmission, HARQ feedback information for the SL transmission, or a channel energy level for the SL transmission. Alternatively or additionally, the first terminal device 110 may determine input information based at least on the detection result, and the input information may be used for CW adjustment.

[0100] In some embodiments, the first terminal device 110 may monitor SL transmissions (PSCCH and / or PSFCH) within the COT. In some examples, the first terminal device 110 may monitor intra-cluster SCI exchanges (i.e., PSCCH) based on an identifier (ID) of the terminal device 120. For example, the first terminal device 110 may detect whether the terminal device 120 can transmit during the COT, and the first terminal device 110 may further incorporate the detection information in the SCI as part of the input information.

[0101] In some embodiments, the first terminal device 110 may detect a resource allocation for the SL transmission (PSSCH) of the terminal device 120 within the COT. In some embodiments, the first terminal device 110 may monitor HARQ feedback information (PSFCH) based on the resource allocation. In some examples, the first terminal device 110 may take the HARQ feedback information as part of the input information.

[0102] In some embodiments, the first terminal device 110 may detect a channel energy level by sensing the channel at a predetermined time. In some examples, the first terminal device 110 may sense the channel for a detected energy level during the COT and take the detected energy level as part of the input information. For example, by detecting energy in the channel at a predetermined time, the first terminal device 110 may determine whether a terminal device (such as terminal device 120-2) successfully received the SL transmission 442. In other words, the detected energy may implicitly indicate whether the SL transmission 442 was successful.

[0103] Alternatively or additionally, the first terminal device 110 performs a CW adjustment based on the input information (470). In some embodiments, the first terminal device 110 may adjust the CW associated with the CAPC according to at least one predefined rule.

[0104] In some embodiments, the first terminal device 110 can reset the size of the CW to an initial value based on one or more of the following: the number of acknowledgements (ACKs) indicated by the HARQ feedback information exceeds an ACK number threshold; the ratio of the number of ACKs to the total number of feedbacks indicated by the HARQ feedback information exceeds an ACK ratio threshold; the number of terminal devices transmitting SCI exceeds a device number threshold; or the ratio of the number of terminal devices transmitting SCI to the number of multiple terminal devices exceeds a device ratio threshold.

[0105] In some examples, the ACK number threshold is denoted as N0 (an integer such as 1), and the ACK ratio threshold is denoted as x% (such as 10%). Thus, if at least N0 HARQ feedbacks or x% of the HARQ feedbacks are "ACKs" for PSSCH transmissions within the COT, the first terminal device 110 may reset the size of the CW.

[0106] In some examples, the first terminal device 110 may determine a change in detected channel energy before and after a predefined time within the COT and determine that the feedback information indicates an ACK if the change exceeds an energy detection threshold. In some examples, the first terminal device 110 may determine that an "ACK" is detected when no NACK is detected in the case of NACK-only feedback.

[0107] In some examples, the device count threshold is denoted as MO (an integer such as 1), and the device ratio threshold is denoted as y% (such as 10%). Thus, if at least MO expected devices, or y% of the expected devices, of the plurality of terminal devices 120 are detected to transmit SCIs within the COT, the first terminal device 110 may reset the size of the CW. In some examples, for a particular terminal device (such as terminal device 120-2), the first terminal device 110 may determine whether terminal device 120-2 is an expected device based on the monitored SCIs of terminal device 120-2 and / or the BSR from terminal device 120-2.

[0108] In some embodiments, the first terminal device 110 may increase the size of the CW based on one or more of the following: no SCI detected, no HARQ feedback detected, the number of detected SCIs below an SCI threshold, the number of detected HARQ feedbacks below a feedback threshold, or the ratio of the time period during which the channel energy level is above a threshold to the COT exceeding a time ratio threshold. For example, the SCI threshold may be denoted as N1, the feedback threshold may be denoted as N2, and the time ratio threshold may be denoted as z%. In some examples, no SCI detected may indicate that no SL transmission is performed.

[0109] That is, the first terminal device 110 can increase the CW if at least one of the following conditions is met: there is no HARQ feedback for SL transmissions of multiple terminal devices 120 during the COT; no SL transmission is detected via an SCI during the COT; the number of detected SCIs is less than N1; the number of detected HARQ feedbacks is less than N2; or energy sensing at the first terminal device 110 exceeds a threshold for a period exceeding z% of the COT.

[0110] In some embodiments, the thresholds discussed above, such as N0, M0, N1, N2, x, y, and z, may be predefined or preconfigured by the network device 130.

[0111] In this manner, the first terminal device 110 can make CW adjustments based on input information associated with detection results in a COT shared with multiple terminal devices 120.

[0112] Note that the first terminal device 110 (CH device) may acquire the COT but is not engaged in SL transmission with any of the multiple terminal devices 120 (CM devices). In other words, there is no logical channel associated with the intended transmission for the first terminal device 110 in the COT. The present disclosure provides a CW adjustment mechanism for a Type 1 LBT procedure to facilitate the first terminal device 110 (CH) sharing the COT initiated for SL transmission with the multiple terminal devices 120. According to the present disclosure, the first terminal device 110 can adjust the CW based on input information even if there is no logical channel associated with the intended transmission in the COT. In some embodiments, the first terminal device 110 and the multiple terminal devices 120 are within the coverage of the network device 130.

[0113] 4B illustrates another example of a process flow 405 according to some exemplary embodiments of the present disclosure. The process flow 405 includes a CH device 401, a first CM device 402, and a second CM device 403. In some embodiments, the process flow 405 may be a specific implementation of the process flow 400 described above. For example, the CH device 401 may be the first terminal device 110, the first CM device 402 may be the terminal device 120-1, and the second CM device 120-2 may be the terminal device 120-2.

[0114] In process flow 405, the CH device 401 determines (4051) a CAPC for COT sharing with CM devices, including a first CM device 402 and a second CM device 403. In some examples, the determination depends at least on whether traffic information of the CM devices 402-403 during the expected COT is available at the CH device 401.

[0115] The CH device 401 obtains 4052 a COT with a CW associated with the determined CAPC. The CH device 401 then indicates 4053 the COT information to its CM device. In some embodiments, the COT information may be transmitted via control signaling (e.g., SCI or sequence-based).

[0116] In some embodiments, the COT information may indicate an obtained COT. In some other embodiments, the COT information may indicate an obtained COT and a determined CAPC. In some embodiments, the COT information may be shared with the first CM device 402. In some other embodiments, the COT information may be shared with the first CM device 402 and the second CM device 403.

[0117] The first CM device 402 determines 4054 a traffic type for the SL transmission. In some examples, the determination is based at least on whether CAPC is indicated in the COT information.

[0118] In some embodiments, if the COT information indicates a captured COT and a determined CAPC, the traffic type may be determined based on the indicated CAPC. In some other embodiments, if the COT information indicates a captured COT (no CAPC), the traffic type may be determined based on the default CAPC.

[0119] The first CM device 402 and the second CM device 403 perform SL transmissions within the COT (e.g., PSCCH / PSSCH 4055 and PSFCH 4056 shown in FIG. 4B). In some embodiments, the SL transmissions may be based on resource selection and COT indication. In some embodiments, the SL transmissions within the COT may be limited to groupcast and / or unicast transmissions.

[0120] In process flow 405, the CH device 401 monitors SL transmissions (PSCCH / PSFCH) and / or channel energy levels of SL transmissions 4057. In some embodiments, the CH device 401 can monitor SL transmissions between its CM devices to determine input information for CW adjustments.

[0121] In some alternative embodiments, when the CH device 401 and the CM devices 402-403 are within the coverage of a network device (such as a gNB) and SL HARQ feedback is reported to the gNB, the gNB can monitor the results of the HARQ feedback from the CM devices 402-403 and indicate the results to the CH device 401 as part of the input information for CW adjustment.

[0122] The CH device 401 further adjusts the CW based on predefined rules and input information (4058).

[0123] It should be understood that the process 405 depicted in FIG. 4B is for illustrative purposes only, without implying any limitation.

[0124] 5 illustrates an example of a process flow 500 according to some exemplary embodiments of the present disclosure. For purposes of explanation, the process flow 500 will be described with reference to FIG. 1A. Although the process flow 500 is described in the network environment 100 of FIG. 1A, it will be understood that the process flow may be applied to other communication scenarios as well.

[0125] Process flow 500 includes a first terminal device 110, a terminal device 120-1, a terminal device 120-2, and a network device 130. In some embodiments, the first terminal device 110 may be a CH device, and terminal device 120-1 and terminal device 120-2 are CM devices in the same cluster. In some embodiments, terminal device 120-1 may be an initiator device of an SL transmission, and terminal device 120-2 may be a responder device of the SL transmission.

[0126] In process flow 500, the first terminal device 110 determines 510 a CAPC. Alternatively or additionally, operations 501 or 505 may be performed before decision 510.

[0127] 5, terminal device 120-1 transmits (502) traffic information 503 to first terminal device 110, and first terminal device 110 receives (504) traffic information 503. Thus, first terminal device 110 can determine a CAPC based on the traffic information from terminal device 120-1.

[0128] 5, network device 130 sends (508) a start command 509 to first terminal device 110. Alternatively or additionally, terminal device 120-1 can send (506) traffic information 503 to network device 130, and network device 130 receives (507) traffic information 503.

[0129] In some embodiments, the start command 509 may be carried in an RRC message or RRC signaling. In some other embodiments, the start command 509 may be carried in a separate message, and the present disclosure is not limited in this respect.

[0130] In some exemplary embodiments, the start command 509 is used to indicate to the first terminal device 110 to start the COT. In some exemplary embodiments, the start command includes one or more of a CAPC, identifiers of the terminal devices, traffic information, or timing information for starting the COT.

[0131] In some examples, network device 130 may determine the CAPC according to a cluster configuration. In some examples, network device 130 may determine the CAPC based on traffic information from terminal device 120-1.

[0132] In some examples, multiple terminal devices may be grouped into one or more clusters. For example, as shown in FIG. 1B, terminal device 120-1 and terminal device 120-2 belong to the same cluster, and terminal device 120-3, terminal device 120-4, and terminal device 120-5 belong to another cluster.

[0133] In some embodiments, it is assumed that there is an SL transmission from terminal device 120-1 to terminal device 120-2, and therefore, start command 509 may include an identifier for terminal device 120-1 and an identifier for terminal device 120-2. In some examples, start command 509 may also indicate that terminal device 120-1 is the initiator of the SL transmission and that terminal device 120-2 is the responder of the SL transmission.

[0134] It should be understood that in some other embodiments, when there is a first SL transmission from terminal device 120-1 to terminal device 120-2 and a second SL transmission from terminal device 120-3 to terminal device 120-4 (as shown in FIG. 1C), start command 509 may further indicate that terminal device 120-1 and terminal device 120-2 belong to the same cluster, and that terminal device 120-3, terminal device 120-4, and terminal device 120-5 belong to another cluster.

[0135] In some examples, start command 509 may include traffic information associated with terminal device 120-1 and / or terminal device 120-2. It should be appreciated that in some other embodiments, start command 509 may further include other traffic information associated with terminal device 120-3 and / or terminal device 120-4.

[0136] In some examples, the start command 509 may include timing information for starting the COT. For example, the timing information may indicate a start time, so the first terminal device 110 may start the COT at the start time. For example, the timing information may indicate a start periodicity, so the first terminal device 110 may restart the COT after a previous start based on the expiration of the period of the start periodicity.

[0137] On the other side of the communication, the first terminal device 110 receives the start command 509 (5091). In some examples, if the start command 509 includes a CAPC, the first terminal device 110 may determine the CAPC by obtaining the CAPC from the start command 509 (510). In some other examples, if the start command 509 does not include a CAPC but does include traffic information, the first terminal device 110 may determine the CAPC based on the traffic information (510). In some other examples, if the start command 509 does not include a CAPC or traffic information, the first terminal device 110 may determine the CAPC itself, for example, a predefined CAPC, which may be the lowest or highest CAPC of multiple preconfigured CAPCs, or based on the traffic information 503 received in 504 (510).

[0138] The first terminal device 110 initiates COT by performing an LBT procedure associated with CAPC (520). In some embodiments, the LBT procedure may be a Type 1 LBT procedure or may also be referred to as a Type 1 LBT. In some embodiments, the first terminal device 100 may initiate COT based on a start command 509 from the network device 130.

[0139] In some embodiments, the start command 509 includes timing information for starting the COT, and the first terminal device 110 may start the COT based on the timing information (520). For example, the first terminal device 110 may start the COT at a start time indicated by the timing information. For example, the timing information may indicate a start periodicity, and the first terminal device 110 may restart the COT after a previous start based on the expiration of a period of the start periodicity.

[0140] The first terminal device 110 transmits (530) the COT 531 indication to multiple terminal devices 120, including terminal device 120-1 and terminal device 120-2 as shown in Figure 5. Thus, terminal device 120-1 may receive (532) the COT 531 indication, and terminal device 120-2 may receive (534) the COT 531 indication. Alternatively or additionally, the first terminal device 110 may transmit the CAPC indication to multiple terminal devices 120.

[0141] In some examples, the first terminal device 110 may determine that the target terminal devices of the COT instruction include terminal device 120-1 and terminal device 120-2 based on the start command 509. For example, the start command 509 may include identifiers of terminal device 120-1 and terminal device 120-2.

[0142] Terminal device 120-1 determines the traffic type of the SL transmission based on the CAPC (536). Terminal device 120-1 transmits SL transmission 542 to terminal device 120-2 during the COT (540). On the other side of the communication, terminal device 120-2 receives SL transmission 542 (544). Terminal device 120-2 transmits feedback information 552 of the SL transmission to terminal device 120-1 (550). Thus, terminal device 120-1 receives feedback information 552 (554).

[0143] It should be understood that processes 520-554 may refer to processes described with reference to FIG. 4A and therefore will not be repeated here.

[0144] 5, network device 130 monitors 560 feedback information transmitted by terminal device 120-2. Network device 130 then transmits 570 feedback information 572 to first terminal device 110, which therefore receives feedback information 572.

[0145] The first terminal device 110 detects the SL transmission during the COT (580). In some exemplary embodiments, the first terminal device 110 may detect the SL transmission and determine a detection result. In some exemplary embodiments, the detection result may include one or more of an SCI associated with the SL transmission or a channel energy level of the SL transmission.

[0146] Alternatively or additionally, the first terminal device 110 may determine input information based at least on the detection result or feedback information 572 from the network device 130, and the input information may be used for CW adjustment.

[0147] The first terminal device 110 performs the CW adjustment based on the input information (590). In some embodiments, the first terminal device 110 may adjust the CW associated with the CAPC according to at least one predefined rule.

[0148] It should be understood that similar operations in Figure 5 may refer to operations described with reference to Figure 4A. Although the embodiments are described with reference to Figures 4A-5, respectively, it should be understood that some operations may be combined in some other embodiments. For example, the first terminal device 110 may start a COT based on a start command from the network device 130 in Figure 4A. As another example, the first terminal device 110 receives timing information from the network device 130 and traffic information from the terminal device 120-1 in Figure 5. The present disclosure is not limited in this respect.

[0149] 1C , assume that the network device 130 can configure the first terminal device 110 as a CH device and the multiple terminal devices 120-1 to 120-5 as CM devices. The first terminal device 110 can be responsible for initiating and sharing a COT with the multiple terminal devices 120-1 to 120-5. In some examples, because the multiple terminal devices 120-1 to 120-5 are within the coverage of the first terminal device 110, the first terminal device 110 can successfully share its initiated COT with the multiple terminal devices 120-1 to 120-5, and the first terminal device 110 can detect SL transmissions between the multiple terminal devices 120-1 to 120-5 based on the identifiers of the multiple terminal devices 120-1 to 120-5.

[0150] Assume there is an SL transmission between terminal device 120-1 and terminal device 120-2, and another SL transmission between terminal device 120-3 and terminal device 120-4. Figure 6 shows an example frame structure 600 in accordance with some example embodiments of the present disclosure.

[0151] In some embodiments, the first terminal device 110 may determine expected terminal devices based on the BSR, for example, the expected terminal devices include terminal devices 120-1 through 120-4.

[0152] The first terminal device 110 performs a Type 1 LBT procedure 60 in slot #n. If the first terminal device 110 successfully acquires the channel, it starts a COT with a duration of 30 OFDM symbols (62) and shares the COT with the terminal devices 120-1 to 120-4 for SL transmission (61). For example, the first terminal device 110 transmits (e.g., through a sequence) control signaling to indicate the COT over two OFDM symbols 61 within COT 52 (i.e., OFDMA symbols #11 / 12 in slot #n). In some examples, the COT indication may be able to at least inform the terminal devices 120-1 to 120-4 whether the COT will be acquired in subsequent slots.

[0153] Terminal device 120-1 and terminal device 120-3 are each intended to perform SL transmission. Therefore, terminal device 120-1 and terminal device 120-3 may perform reduced LBT (e.g., Type 2 CLBT) on the second guard symbols of slot #n and slot #(n+1) (shown as 611 and 613 in FIG. 6) to access the channel, respectively. Therefore, terminal device 120-1 may transmit PSCCH / PSSCH 621 to terminal device 120-2 in slot #(n+1) within the COT. Terminal device 120-3 may transmit PSCCH / PSSCH 623 to terminal device 120-4 in slot #(n+2) within the COT.

[0154] Terminal device 120-2 and terminal device 120-4 may perform reduced LBT (e.g., Type 2 CLBT) on the first guard symbols of slot #(n+1) and slot #(n+2) (shown as 612 and 614 in FIG. 6), respectively, to access the channel. Thus, terminal device 120-2 transmits PSFCH 622 for HARQ feedback to terminal device 120-1 at slot #(n+1) in the COT. Terminal device 120-4 transmits PSFCH 624 for HARQ feedback to terminal device 120-3 at slot #(n+2) in the COT.

[0155] It should be understood that the reduced LBT may be implemented in guard symbols by CP extension as in NR-U, and the present disclosure does not limit this aspect. Furthermore, SL transmission during COT may be groupcast SL transmission or unicast SL transmission, and therefore either groupcast SL transmission or unicast SL transmission is allowed in different subbands.

[0156] In this example, the CH can determine how to adjust the CW size based on, for example, the SCI on the PSCCH or the HARQ feedback on the PSFCH (i.e., the PSSCH or PSFCH is the reference resource for CW adjustment). Alternatively, the CH may simply detect the channel energy, for example, during the AGC symbol DMRS or PSFCH. Yet another option is for the CH to perform detection of the DMRS sequence transmitted by the CM.

[0157] 7 shows a flowchart 700 of a method implemented in a first terminal device according to some exemplary embodiments of the present disclosure. For illustrative purposes, the method 700 will be described from the perspective of the first terminal device 110 with reference to FIG. 1A.

[0158] In block 710, the first terminal device 110 initiates a channel occupation time (COT) by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC). In block 720, the first terminal device 110 transmits an indication of the COT for sidelink (SL) transmissions to the multiple terminal devices 120 among the multiple terminal devices 120. In block 730, the first terminal device 110 detects an SL transmission during the COT.

[0159] In some demonstrative embodiments, the first terminal device 110 receives a start command from the network device 130 indicating that the first terminal device is to start COT, the start command including at least one of CAPC, a plurality of identifiers of the plurality of terminal devices, traffic information for SL transmission, or timing information for starting COT.

[0160] In some exemplary embodiments, the first terminal device 110 receives traffic information of the SL transmission from one of the plurality of terminal devices 120 and determines a CAPC based on the traffic information.

[0161] In some exemplary embodiments, the traffic information indicates traffic types associated with multiple categories of terminal devices 120 .

[0162] In some exemplary embodiments, the first terminal device 110 determines that the CAPC is a predefined CAPC, where the predefined CAPC is the lowest CAPC or the highest CAPC among a plurality of preconfigured CAPCs.

[0163] In some exemplary embodiments, the first terminal device 110 determines the CAPC to be the highest CAPC from a plurality of pre-configured CAPCs.

[0164] In some exemplary embodiments, the first terminal device 110 transmits the CAPC indication to multiple terminal devices 120 .

[0165] In some demonstrative embodiments, the first terminal device 110 determines input information based at least on the detection result of the SL transmission during the COT and performs a contention window (CW) adjustment based at least in part on the input information.

[0166] In some example embodiments, the detection result of the SL transmission includes at least one of sidelink control information (SCI) associated with the SL transmission, HARQ feedback information for the SL transmission, or a channel energy level for the SL transmission.

[0167] In some exemplary embodiments, the first terminal device 110 detects a resource allocation for the SL transmission within the COT and monitors HARQ feedback information based on the resource allocation.

[0168] In some exemplary embodiments, the first terminal device 110 detects the channel energy level by sensing the channel at a predetermined time.

[0169] In some exemplary embodiments, the first terminal device 110 receives HARQ feedback information from the network device 130 , and the first terminal device 110 and the plurality of terminal devices 120 are within the coverage of the network device 130 .

[0170] In some exemplary embodiments, the first terminal device 110 resets the size of the CW to an initial value based on at least one of the following: the number of acknowledgements (ACKs) indicated by the HARQ feedback information exceeds an ACK number threshold; the ratio of the number of ACKs to the total number of feedbacks indicated by the HARQ feedback information exceeds an ACK ratio threshold; the number of terminal devices transmitting SCI exceeds a device number threshold; or the ratio of the number of terminal devices transmitting SCI to the number of multiple terminal devices 120 exceeds a device ratio threshold.

[0171] In some exemplary embodiments, the HARQ feedback is determined based on the change in detected channel energy before and after a predetermined time within the COT that exceeds an energy detection threshold.

[0172] In some exemplary embodiments, the first terminal device 110 increases the size of the CW based on at least one of: no SCI is detected; no HARQ feedback is detected; the number of detected SCIs is below an SCI threshold; the number of detected HARQ feedbacks is below a feedback threshold; or the ratio of the duration that the channel energy level is above a threshold to the COT exceeds a time ratio threshold.

[0173] 8 shows a flowchart 800 of a method implemented in a second terminal device according to some exemplary embodiments of the present disclosure. For illustrative purposes, the method 800 will be described from the perspective of one of the plurality of terminal devices 120 (such as the second terminal device 120-1) with reference to FIG. 1A.

[0174] At block 810, the second terminal device 120-1 transmits traffic information to at least one of the first terminal device 110 or the network device 130. At block 820, the second terminal device 120-1 receives from the first terminal device 110 an indication of a channel occupation time (COT) initiated by the first terminal device 110. At block 830, the second terminal device 120-1 transmits a sidelink (SL) transmission to the third terminal device 120-2 during the COT.

[0175] In some demonstrative embodiments, the traffic information indicates traffic types associated with categories of multiple terminal devices 120, including second terminal device 120-1 and third terminal device 120-2.

[0176] In some exemplary embodiments, second terminal device 120-1 receives from first terminal device 110 an indication of a channel access priority class (CAPC).

[0177] In some exemplary embodiments, second terminal device 120-1 determines a default CAPC configured by network device 130 if no indication of a CAPC is received from first terminal device 110.

[0178] In some exemplary embodiments, second terminal device 120-1 determines SL transmission using traffic type based on CAPC.

[0179] In some exemplary embodiments, the second terminal device 120-1 receives hybrid automatic repeat request (HARQ) feedback information for SL transmissions within the COT from the third terminal device 120-2.

[0180] 9 shows a flowchart 900 of a method implemented in a network device according to some other embodiments of the present disclosure. For illustrative purposes, the method 900 will be described from the perspective of the network device 130 with reference to FIG. 1A.

[0181] In block 910, the network device 130 sends a start command to the first terminal device 110 indicating that the first terminal device will start COT, the start command including at least one of CAPC, multiple identifiers of the multiple terminal devices, traffic information of SL transmission between the multiple terminal devices, or timing information for starting COT.

[0182] In some demonstrative embodiments, network device 130 receives from second terminal device 120-1 traffic information of SL transmissions between the second terminal device and a third terminal device, and the plurality of terminal devices comprises the second terminal device and the third terminal device.

[0183] In some exemplary embodiments, the traffic information indicates traffic types associated with categories of the second terminal device and the third terminal device.

[0184] In some demonstrative embodiments, network device 130 monitors feedback information transmitted by third terminal device 120-2 to second terminal device 120-1, the feedback information is provided for an SL transmission from second terminal device 120-1 to third terminal device 120-2, the SL transmission is transmitted during a COT initiated by first terminal device 110, and the plurality of terminal devices includes the second terminal device and the third terminal device. Network device 130 then transmits the feedback information to first terminal device 110.

[0185] In some exemplary embodiments, the feedback information includes hybrid automatic repeat request (HARQ) feedback information.

[0186] In some demonstrative embodiments, an apparatus capable of performing method 700 (e.g., first terminal device 110) may comprise means for performing each step of method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0187] In some demonstrative embodiments, an apparatus includes means for initiating a channel occupation time (COT) at a first terminal device by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); means for transmitting, to a plurality of terminal devices, an indication of the COT for a sidelink (SL) transmission between the plurality of terminal devices; and means for detecting the SL transmission during the COT.

[0188] In some exemplary embodiments, the method includes means for receiving a start command from the network device indicating that the first terminal device is to start the COT, the start command including at least one of CAPC, a plurality of identifiers of the plurality of terminal devices, traffic information for SL transmission, or timing information for starting the COT.

[0189] In some exemplary embodiments, an apparatus includes means for receiving traffic information of an SL transmission from one of a plurality of terminal devices, and means for determining a CAPC based on the traffic information.

[0190] In some exemplary embodiments, the traffic information indicates traffic types associated with multiple categories of terminal devices.

[0191] In some exemplary embodiments, the apparatus includes means for determining the CAPC to be a predefined CAPC, the predefined CAPC being the lowest CAPC or the highest CAPC among a plurality of preconfigured CAPCs.

[0192] In some exemplary embodiments, the apparatus includes means for determining a CAPC to be the highest CAPC from a plurality of pre-configured CAPCs.

[0193] In some exemplary embodiments, the apparatus includes means for transmitting CAPC instructions to a plurality of terminal devices.

[0194] In some demonstrative embodiments, the apparatus includes means for determining input information based at least on a result of detecting SL transmissions during the COT, and means for performing a contention window (CW) adjustment based at least in part on the input information.

[0195] In some example embodiments, the detection result of the SL transmission includes at least one of sidelink control information (SCI) associated with the SL transmission, hybrid automatic repeat request (HARQ) feedback information for the SL transmission, or a channel energy level for the SL transmission.

[0196] In some exemplary embodiments, an apparatus includes means for detecting a resource allocation for a SL transmission within a COT and means for monitoring HARQ feedback information based on the resource allocation.

[0197] In some exemplary embodiments, the apparatus includes means for detecting a channel energy level by sensing the channel at a predetermined time.

[0198] In some demonstrative embodiments, an apparatus includes means for receiving HARQ feedback information from a network device, wherein a first terminal device and a plurality of terminal devices are within coverage of the network device.

[0199] In some exemplary embodiments, the apparatus includes means for resetting the size of the CW to an initial value based on at least one of the following: a number of acknowledgements (ACKs) indicated by the HARQ feedback information exceeds an ACK number threshold; a ratio of the number of ACKs to the total number of feedbacks indicated by the HARQ feedback information exceeds an ACK ratio threshold; a number of terminal devices transmitting an SCI exceeds a device number threshold; or a ratio of the number of terminal devices transmitting an SCI to the number of multiple terminal devices exceeds a device ratio threshold.

[0200] In some exemplary embodiments, the HARQ feedback is determined based on the change in detected channel energy before and after a predetermined time within the COT that exceeds an energy detection threshold.

[0201] In some exemplary embodiments, the apparatus includes means for increasing the size of the CW based on at least one of: no SCI is detected; no HARQ feedback is detected; the number of detected SCIs is below an SCI threshold; the number of detected HARQ feedbacks is below a feedback threshold; or the ratio of the duration that the channel energy level is above a threshold to the COT exceeds a time ratio threshold.

[0202] In some exemplary embodiments, the apparatus further comprises means for performing other steps in some exemplary embodiments of method 700. In some exemplary embodiments, the means comprises at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code configured to cause performance of the apparatus by the at least one processor.

[0203] In some demonstrative embodiments, an apparatus capable of performing method 800 (e.g., second terminal device 120-1) may comprise means for performing each step of method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0204] In some demonstrative embodiments, the apparatus includes means, at the second terminal device, for transmitting traffic information to at least one of the first terminal device or the network device; means for receiving from the first terminal device an indication of a channel occupation time (COT) initiated by the first terminal device; and means for transmitting a sidelink (SL) transmission to a third terminal device during the COT.

[0205] In some exemplary embodiments, the traffic information indicates traffic types associated with a category of a plurality of terminal devices comprising a second terminal device and a third terminal device.

[0206] In some exemplary embodiments, an apparatus includes means for receiving an indication of a channel access priority class (CAPC) from a first terminal device.

[0207] In some exemplary embodiments, the apparatus includes means for determining a default CAPC configured by the network device if an indication of the CAPC is not received from the first terminal device.

[0208] In some exemplary embodiments, the apparatus includes means for determining a SL transmission having a traffic type based on the CAPC.

[0209] In some exemplary embodiments, the apparatus includes means for receiving, from a third terminal device, hybrid automatic repeat request (HARQ) feedback information for an SL transmission within the COT.

[0210] In some exemplary embodiments, the apparatus further comprises means for performing other steps in some exemplary embodiments of method 800. In some exemplary embodiments, the means comprises at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code configured to cause, by the at least one processor, performance of the apparatus.

[0211] In some demonstrative embodiments, an apparatus capable of performing method 900 (e.g., network device 130) may comprise means for performing each step of method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0212] In some demonstrative embodiments, the apparatus includes means for sending a start command to a first terminal device instructing the first terminal device to start a COT, the start command including at least one of a CAPC, a plurality of identifiers of the plurality of terminal devices, traffic information of SL transmission between the plurality of terminal devices, or timing information for starting the COT.

[0213] In some demonstrative embodiments, the apparatus includes means for receiving, from the second terminal device, traffic information of an SL transmission between the second terminal device and a third terminal device, and the plurality of terminal devices comprises the second terminal device and the third terminal device.

[0214] In some exemplary embodiments, the traffic information indicates traffic types associated with categories of the second terminal device and the third terminal device.

[0215] In some demonstrative embodiments, the apparatus includes means, at the network device, for monitoring feedback information transmitted by a third terminal device to a second terminal device, the feedback information being provided for an SL transmission from the second terminal device to the third terminal device, the SL transmission being transmitted during a COT initiated by the first terminal device, the plurality of terminal devices comprising the second terminal device and the third terminal device, and means for transmitting the feedback information to the first terminal device.

[0216] In some exemplary embodiments, the feedback information includes hybrid automatic repeat request (HARQ) feedback information.

[0217] In some exemplary embodiments, the apparatus further comprises means for performing other steps in some exemplary embodiments of method 900. In some exemplary embodiments, the means comprises at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code configured to cause, by the at least one processor, performance of the apparatus.

[0218] 10 shows a simplified block diagram of a device 1000 suitable for implementing some exemplary embodiments of the present disclosure. The device 1000 may be provided to implement a communication device, such as the first terminal device 110, any of the terminal devices 120, or the network device 130 as shown in FIG. 1A. As shown, the device 1000 includes one or more processors 1010, one or more memories 1020 coupled to the processors 1010, and one or more communication modules 1040 coupled to the processors 1010.

[0219] The communication module 1040 is for two-way communication. The communication module 1040 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary for communication with other network elements.

[0220] The processor 1010 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 1000 may have multiple processors, such as application specific integrated circuit chips that are time-slaved to a clock that synchronizes the main processor.

[0221] The memory 1020 can include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read-only memory (ROM) 1024, electrically programmable read-only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), and other magnetic and / or optical storage. Examples of volatile memory include, but are not limited to, random access memory (RAM) 1022 and other volatile memory that does not persist during power-down durations.

[0222] The computer program 1030 includes computer-executable instructions that are executed by the associated processor 1010. The program 1030 may be stored in the ROM 1024. The processor 1010 may load the program 1030 into the RAM 1022 to perform any suitable actions and processes.

[0223] 4A to 9, the device 1000 may be implemented by a program 1030 such that the device 1000 may execute any process of the present disclosure. The embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0224] In some demonstrative embodiments, the program 1030 may be tangibly contained in a computer-readable medium, which may be included in the device 1000 (such as the memory 1020) or other storage device accessible by the device 1000. The device 1000 may load the program 1030 from the computer-readable medium into RAM 1022 for execution. The computer-readable medium may include any type of tangible non-volatile storage, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc.

[0225] 11 illustrates a block diagram of an example computer-readable medium 1100 according to some exemplary embodiments of the present disclosure. The computer-readable medium 1100 has stored thereon a program 1030. While the computer-readable medium 1100 is shown in the form of a CD or DVD in FIG. 11, it should be noted that the computer-readable medium 1100 may be in any other form suitable for carrying or retaining the program 1030.

[0226] In general, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. While some aspects may be implemented in hardware, other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. While various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it should be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller, or other computing device, or some combination thereof.

[0227] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, that execute on a target real or virtual processor device to perform a method such as those described above with reference to any of FIGS. 7-9. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or divided among program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed in local or distributed devices. In distributed devices, program modules may be located in both local and remote storage media.

[0228] Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code implements the functions / acts specified in the flowcharts and / or block diagrams. The program code may run entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine, partially on a remote machine, or entirely on a remote machine or server.

[0229] In the context of the present disclosure, computer program code or associated data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations as described above. Examples of carriers include signals, computer-readable media, etc.

[0230] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. As used herein, the term "non-transitory" refers to the medium itself (i.e., tangible rather than signal), as opposed to a limitation on data storage permanence (e.g., RAM vs. ROM).

[0231] Furthermore, while operations are shown in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in sequential order, or that all of the shown operations be performed, to achieve desirable results. In some situations, multitasking and parallel processing may be advantageous. Similarly, while some specific implementation details are included in the above description, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Some features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

[0232] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined by the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first terminal device to: Initiating a channel occupation time (COT) by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); transmitting, to a plurality of terminal devices, an indication of the COT for side link (SL) transmissions between the plurality of terminal devices; and detecting the SL transmission during the COT.

2. The first terminal device further comprises: receiving a start command from a network device instructing the first terminal device to start the COT, the start command comprising: The CAPC, a plurality of identifiers of the plurality of terminal devices; Traffic information of the SL transmission, or timing information for initiating the COT; 2. The first terminal device of claim 1, comprising at least one of:

3. The first terminal device further comprises: receiving traffic information of the SL transmission from one of the plurality of terminal devices; 2. The first terminal device according to claim 1, further comprising: a step of determining the CAPC based on the traffic information.

4. 4. The first terminal device of claim 2 or 3, wherein the traffic information indicates traffic types associated with categories of the plurality of terminal devices.

5. The first terminal device further comprises:

2. The first terminal device according to claim 1, further comprising: a step of determining that the CAPC is a predefined CAPC; and the predefined CAPC is the lowest CAPC or the highest CAPC among a plurality of preconfigured CAPCs.

6. The first terminal device further comprises: The first terminal device according to claim 1, further comprising a step of transmitting the CAPC instruction to the plurality of terminal devices.

7. The first terminal device further comprises: determining input information based at least on the detection of the SL transmission during the COT; and performing a contention window (CW) adjustment based at least in part on the input information.

8. The detection result of the SL transmission is Sidelink Control Information (SCI) related to the SL transmission; Hybrid Automatic Repeat Request (HARQ) feedback information for the SL transmission; or 8. The first terminal device of claim 7, wherein the first terminal device comprises at least one of the channel energy levels of the SL transmission.

9. The first terminal device further comprises: Detecting resource allocation for the SL transmission within the COT; and monitoring the HARQ feedback information based on the resource allocation.

10. The first terminal device further comprises:

9. The first terminal device of claim 8, wherein the step of detecting the channel energy level is performed by sensing the channel at a predetermined time.

11. The first terminal device further comprises: The first terminal device of claim 8, characterized in that the first terminal device and the plurality of terminal devices are within the coverage of the network device, and the first terminal device performs the step of receiving the HARQ feedback information from a network device.

12. The first terminal device performs the CW adjustment, The size of the CW is set to the initial value. the number of acknowledgements (ACKs) indicated by the HARQ feedback information exceeding a threshold number of ACKs; a ratio of the number of ACKs to the total number of feedbacks indicated by the HARQ feedback information exceeding an ACK ratio threshold; The number of terminal devices transmitting the SCI exceeds a threshold number of devices, or a ratio of the number of terminal devices transmitting the SCI to the number of the plurality of terminal devices that exceeds a device ratio threshold; 8. The first terminal device of claim 7, wherein the step of performing the CW adjustment is performed by resetting based on at least one of:

13. 13. The first terminal device of claim 12, wherein the HARQ feedback is determined based on a change in detected channel energy before and after a predetermined time within the COT exceeding an energy detection threshold.

14. The first terminal device performs the CW adjustment, The size of the CW is Undetected SCI, Undetected HARQ feedback, the number of detected SCIs below the SCI threshold; the number of detected HARQ feedbacks below the feedback threshold, or a ratio of the duration that the channel energy level is above a threshold to the COT, the ratio exceeding a threshold time ratio; 8. The first terminal device of claim 7, wherein the step of performing the CW adjustment is performed by increasing the CW frequency based on at least one of:

15. at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first terminal device to: transmitting traffic information to one of the first terminal device or network device; receiving, from the first terminal device, an indication of a channel occupation time (COT) initiated by the first terminal device; and transmitting a side link (SL) transmission to a third terminal device during the COT.

16. 16. The second terminal device of claim 15, wherein the traffic information indicates traffic types associated with a plurality of categories of terminal devices, including the second terminal device and the third terminal device.

17. The second terminal device further comprises:

16. The second terminal device of claim 15, further comprising the step of receiving an indication of a channel access priority class (CAPC) from the first terminal device.

18. The second terminal device further comprises:

16. The second terminal device of claim 15, further comprising: performing a step of determining a default CAPC configured by the network device according to a determination that a CAPC indication is not received from the first terminal device.

19. The second terminal device further comprises:

18. The second terminal device of claim 17, further comprising: a step of determining the SL transmission having a traffic type based on the CAPC.

20. The second terminal device further comprises:

20. The second terminal device according to any one of claims 15 to 19, characterized in that it performs a step of receiving Hybrid Automatic Repeat Request (HARQ) feedback information of the SL transmission in the COT from the third terminal device.

21. at least one processor; and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing a first terminal device to: sending a start command to the first terminal device instructing the first terminal device to start a channel occupation time (COT), the start command comprising: Channel Access Priority Class (CAPC), a plurality of identifiers for a plurality of terminal devices; Traffic information of sidelink (SL) transmissions between the plurality of terminal devices; or At least one of timing information for initiating the COT; A network device comprising:

22. The network terminal device further comprises:

22. The network device of claim 21, further comprising: a step of receiving, from a second terminal device, the traffic information of the SL transmission between the second terminal device and a third terminal device; and wherein the plurality of terminal devices comprises the second terminal device and the third terminal device.

23. 23. The network device of claim 22, wherein the traffic information indicates traffic types associated with categories of the second terminal device and the third terminal device.

24. The network terminal device further comprises: performing a step of monitoring feedback information transmitted by a third terminal device to a second terminal device, the feedback information being provided from the second terminal device to the third terminal device for the SL transmission, the SL transmission being transmitted during the COT initiated by the first terminal device, the plurality of terminal devices including the second terminal device and the third terminal device; 24. A network device according to any one of claims 21 to 23, characterized in that it is adapted to transmit said feedback information to said first terminal device.

25. 25. The network device of claim 24, wherein the feedback information comprises hybrid automatic repeat request (HARQ) feedback information.

26. Initiating a channel occupation time (COT) at a first terminal device by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); transmitting, to a plurality of terminal devices, an indication of the COT for side link (SL) transmissions between the plurality of terminal devices; and detecting the SL transmission during the COT.

27. transmitting, at the second terminal device, traffic information to at least one of the first terminal device or the network device; receiving, from the first terminal device, an indication of a channel occupation time (COT) initiated by the first terminal device; and transmitting a sidelink (SL) transmission to a third terminal device during the COT.

28. transmitting a start command to a first terminal device instructing the first terminal device to start a channel occupation time (COT), the start command comprising: Channel Access Priority Class (CAPC), a plurality of identifiers for a plurality of terminal devices; Traffic information of sidelink (SL) transmissions between the plurality of terminal devices; or At least one of timing information for initiating the COT; A method comprising:

29. means for initiating a channel occupation time (COT) at a first terminal device by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); means for transmitting, to a plurality of terminal devices, the indication of the COT for a side link (SL) transmission between the plurality of terminal devices; and means for detecting said SL transmission during said COT.

30. means, at the second terminal device, for transmitting traffic information to at least one of the first terminal device or the network device; means for receiving, from the first terminal device, an indication of a channel occupation time (COT) initiated by the first terminal device; and means for sending a sidelink (SL) transmission to a third terminal device during the COT.

31. means for transmitting a start command to a first terminal device to instruct the first terminal device to start a channel occupation time (COT), the start command comprising: Channel Access Priority Class (CAPC), a plurality of identifiers for a plurality of terminal devices; Traffic information of sidelink (SL) transmissions between the plurality of terminal devices; or At least one of timing information for initiating the COT; 10. An apparatus comprising:

32. A computer-readable medium containing program instructions that, when executed by an apparatus, cause the apparatus to: Initiating a channel occupation time (COT) at a first terminal device by performing a listen-before-talk (LBT) procedure associated with a channel access priority class (CAPC); transmitting, to a plurality of terminal devices, an indication of the COT for side link (SL) transmissions between the plurality of terminal devices; and detecting the SL transmission during the COT.

33. A computer-readable medium containing program instructions that, when executed by an apparatus, cause the apparatus to: transmitting, at the second terminal device, traffic information to at least one of the first terminal device or the network device; receiving, from the first terminal device, an indication of a channel occupation time (COT) initiated by the first terminal device; and transmitting a sidelink (SL) transmission to a third terminal device during the COT.

34. A computer-readable medium containing program instructions that, when executed by an apparatus, cause the apparatus to: Execute a step of sending a start command to a first terminal device, the start command instructing the first terminal device to start a channel occupation time (COT), the start command comprising: Channel Access Priority Class (CAPC), a plurality of identifiers for a plurality of terminal devices; Traffic information of sidelink (SL) transmissions between the plurality of terminal devices; or At least one of timing information for initiating the COT; 1. A computer-readable medium comprising:

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