Method and apparatus for SL transmission and s-SSB transmission in unlicensed spectrum

Abstract

Embodiments of the present disclosure relate to methods and devices for sidelink (SL) transmission and sidelink synchronization signal block (S-SSB) transmission in an unlicensed spectrum. In accordance with an embodiment of the present disclosure, a user equipment (UE) may include a processor configured to obtain slot structure information for an unlicensed spectrum based on a configuration or a pre-configuration, where the slot structure information includes at least one of: a first set of start symbols for SL transmission; a second set of start symbols and duration of S-SSB opportunity; or indicating whether the time slot contains time domain information of S-SSB opportunity; and performing a channel access procedure based on the slot structure information to initiate a channel occupancy time (COT) for SL transmissions, wherein the COT includes a plurality of consecutive slots; a transmitter coupled to the processor; and a receiver coupled to the processor.

Description

Technical Field

[0001] Embodiments of the present application relate to wireless communication techniques, and more particularly, to methods and apparatus for sidelink (SL) transmission and SL synchronization signal block (S-SSB) transmission in unlicensed spectrum. Background Art

[0002] Sidelink is a Long Term Evolution (LTE) feature introduced in 3rd Generation Partnership Project (3GPP) Release 12 and enables direct communication between neighboring user equipments (UEs) without the data passing through a base station (BS) or core network. Sidelink communication systems have been introduced into 3GPP 5G wireless communication technology, where a direct link between two UEs is called a sidelink.

[0003] The sidelink synchronization information is carried in the S-SSB. In unlicensed spectrum, SL transmission and S-SSB transmission may be multiplexed in some cases. Therefore, a new design for SL transmission and S-SSB transmission in unlicensed spectrum is needed. Summary of the invention

[0004] The embodiments of the present application provide at least one technical solution for SL transmission and S-SSB transmission in unlicensed spectrum.

[0005] According to some embodiments of the present application, a UE may include: a processor, which is configured to: obtain time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of start symbols for SL transmission; a second set of start symbols and duration of an S-SSB opportunity; or time domain information indicating whether a time slot includes an S-SSB opportunity; and perform a channel access procedure based on the time slot structure information to initiate a channel occupancy time (COT) for SL transmission, wherein the COT includes multiple consecutive time slots; a transmitter, which is coupled to the processor; and a receiver, which is coupled to the processor.

[0006] In some embodiments of the present application, the time slot structure information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth part (BWP), per frequency range, or per subcarrier spacing (SCS).

[0007] In some embodiments of the present application, the receiver is configured to receive the time slot structure information via at least one of: a master information block (MIB) message, a system information block (SIB) message, a radio resource control (RRC) signaling, a medium access control (MAC) control element (CE) or downlink control information (DCI).

[0008] In some embodiments of the present application, at least one time slot in the COT includes an S-SSB opportunity.

[0009] In some embodiments of the present application, the time slot structure information indicates the maximum duration of the S-SSB allowed within the COT for SL transmission.

[0010] In some embodiments of the present application, at least one time slot in the COT includes both an S-SSB opportunity and time domain resources for SL transmission, and the time domain resources for SL transmission are located before the S-SSB opportunity.

[0011] In some embodiments of the present application, when S-SSB and physical sidelink feedback channel (PSFCH) are periodically configured in the resource pool for SL transmission, the time slot structure information further indicates a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with the position of the PSFCH in the time slot; when S-SSB is periodically configured in the resource pool for SL transmission and PSFCH is not periodically configured in the resource pool for SL transmission, the transmitter is configured to transmit an indication of the position of the PSFCH that does not overlap with the S-SSB opportunity; or the time slot structure information further includes an indication of whether the position is used for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a certain position.

[0012] In some embodiments of the present application, the indication indicating whether the location is for S-SSB or PSFCH is based on the priority of S-SSB or PSFCH or is defined as a default value.

[0013] In some embodiments of the present application, at least one time slot in the COT includes both an S-SSB opportunity and a time domain resource for SL transmission, and the S-SSB opportunity is located before the time domain resource for SL transmission.

[0014] In some embodiments of the present application, the time slot structure information further includes at least one of the following: an indicator indicating whether to enable or disable the occupation of the S-SSB opportunity by non-S-SSB transmission; or a parameter indicating a duration for identifying whether the S-SSB opportunity is used.

[0015] In some embodiments of the present application, the processor is further configured to: determine a third group of start symbols for SL transmission in a time slot based on the first group of start symbols and the second group of start symbols when the indicator indicates enabling of S-SSB opportunities occupied by non-S-SSB transmissions; or determine that the third group of start symbols for SL transmission in a time slot is the first group of start symbols when the indicator indicates disabling of S-SSB opportunities occupied by non-S-SSB transmissions.

[0016] In some embodiments of the present application, when the indicator indicates enabling occupation of the S-SSB opportunity by non-S-SSB transmission and the UE does not want to transmit an S-SSB on an S-SSB opportunity within a time slot in the at least one time slot, the processor is further configured to: perform a sensing operation starting from the S-SSB opportunity within the duration indicated by the parameter; in response to determining that the S-SSB opportunity is not used, perform at least one of the following operations: perform non-S-SSB transmission until the S-SSB opportunity ends; or perform SL transmission until the time slot including the S-SSB opportunity ends.

[0017] In some embodiments of the present application, when at least one time slot among the multiple consecutive time slots includes an S-SSB opportunity, the transmitter is further configured to perform at least one of the following steps: transmitting an SL transmission in a first time slot within the COT in response to determining that the channel is available for access before the first time slot within the COT based on the channel access procedure; transmitting an SL transmission in a time slot within the COT other than the first time slot in response to determining that the channel is available for access before the SL transmission based on a listen-before-talk (LBT) type 2 procedure associated with the SL transmission; or transmitting an S-SSB transmission at an S-SSB opportunity in a time slot within the COT or skipping the S-SSB opportunity in the time slot.

[0018] According to some other embodiments of the present application, a UE may include: a processor, which is configured to: obtain time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of start symbols for SL transmission; a second set of start symbols and duration of an S-SSB opportunity; or time domain information indicating whether a time slot includes an S-SSB opportunity; a receiver, which is coupled to the processor and configured to receive SL transmission based on the time slot structure information; and a transmitter, which is coupled to the processor.

[0019] In some embodiments of the present application, the time slot structure information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth part, per frequency range, or per SCS.

[0020] In some embodiments of the present application, the receiver is configured to receive the time slot structure information via at least one of the following: a MIB message, a SIB message, an RRC signaling, a MAC CE, or a DCI.

[0021] In some embodiments of the present application, the time slot structure information indicates the maximum duration of the S-SSB allowed within the COT for SL transmission.

[0022] In some embodiments of the present application, when S-SSB and PSFCH are periodically configured in a resource pool for SL transmission, the time slot structure information further indicates a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with the position of the PSFCH in the time slot; when S-SSB is periodically configured in a resource pool for SL transmission and PSFCH is not periodically configured in a resource pool for SL transmission, the receiver is configured to receive an indication of the position of the PSFCH that does not overlap with the S-SSB opportunity; or the time slot structure information further includes an indication of whether the position is for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a certain position.

[0023] In some embodiments of the present application, the indication indicating whether the location is for S-SSB or PSFCH is based on the priority of S-SSB or PSFCH or is defined as a default value.

[0024] In some embodiments of the present application, the time slot structure information further includes at least one of the following: an indicator indicating whether to enable or disable the occupation of the S-SSB opportunity by non-S-SSB transmission; or a parameter indicating a duration identifying whether the S-SSB opportunity is used.

[0025] In some embodiments of the present application, the processor is further configured to: determine a third group of start symbols for SL transmission in a time slot based on the first group of start symbols and the second group of start symbols when the indicator indicates enabling of S-SSB opportunities occupied by non-S-SSB transmissions; or determine that the third group of start symbols for SL transmission in a time slot is the first group of start symbols when the indicator indicates disabling of S-SSB opportunities occupied by non-S-SSB transmissions; and the reception is further configured to receive the SL transmission based on the third group of start symbols.

[0026] According to some other embodiments of the present application, a BS may include: a transmitter configured to: transmit time slot structure information of an unlicensed spectrum, wherein the time slot structure information includes at least one of: a first set of start symbols for SL transmission; a second set of start symbols and duration of an S-SSB opportunity; or time domain information indicating whether a time slot includes an S-SSB opportunity; a processor coupled to the transmitter; and a receiver coupled to the processor.

[0027] In some embodiments of the present application, the time slot structure information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth part, per frequency range, or per SCS.

[0028] In some embodiments of the present application, the transmitter is configured to transmit the time slot structure information via at least one of the following: a MIB message, a SIB message, an RRC signaling, a MAC CE, or a DCI.

[0029] In some embodiments of the present application, the time slot structure information indicates the maximum duration of the S-SSB allowed within the COT for SL transmission.

[0030] In some embodiments of the present application, when S-SSB and PSFCH are periodically configured in a resource pool for SL transmission, the time slot structure information further indicates a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with the position of the PSFCH in the time slot; or the time slot structure information further includes an indication of whether the position is used for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a certain position.

[0031] In some embodiments of the present application, the indication indicating whether the location is for S-SSB or PSFCH is based on the priority of S-SSB or PSFCH or is defined as a default value.

[0032] In some embodiments of the present application, the time slot structure information further includes at least one of the following: an indicator indicating whether to enable or disable the occupation of the S-SSB opportunity by non-S-SSB transmission; or a parameter indicating a duration identifying whether the S-SSB opportunity is used.

[0033] According to some embodiments of the present application, a method performed by a UE may include: obtaining time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of start symbols for SL transmission; a second set of start symbols and duration of an S-SSB opportunity; or time domain information indicating whether the time slot includes an S-SSB opportunity; and performing a channel access procedure based on the time slot structure information to initiate a COT for SL transmission, wherein the COT includes multiple consecutive time slots.

[0034] According to some embodiments of the present application, a method performed by a UE may include: obtaining time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of starting symbols for SL transmission; a second set of starting symbols and duration of an S-SSB opportunity; or time domain information indicating whether the time slot includes an S-SSB opportunity; and receiving SL transmission based on the time slot structure information.

[0035] According to some embodiments of the present application, a method performed by a BS may include: transmitting time slot structure information of an unlicensed spectrum, wherein the time slot structure information includes at least one of the following: a first set of starting symbols for SL transmission; a second set of starting symbols and duration of an S-SSB opportunity; or time domain information indicating whether the time slot includes an S-SSB opportunity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] To describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by referring to specific embodiments thereof illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the present application and are therefore not to be considered limiting of its scope.

[0037] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

[0038] Figure 2 Describing exemplary S-SSB time slots according to some embodiments of the present application;

[0039] Figure 3 An exemplary distribution of S-SSB opportunities in the time domain according to some embodiments of the present application is described;

[0040] Figure 4 A flowchart illustrating an exemplary method for SL transmission and S-SSB transmission according to some embodiments of the present application;

[0041] Figure 5 An exemplary COT in case 1 according to some embodiments of the present application is described;

[0042] Figure 6 An exemplary COT in case 2 according to some embodiments of the present application is described;

[0043] Figure 7 An exemplary COT in case 3 according to some embodiments of the present application is described;

[0044] Figure 8 An exemplary procedure including operations for identifying unused S-SSB opportunities in Case 3 is described according to some embodiments of the present application;

[0045] Fig. 9 A flowchart illustrating an exemplary method for SL transmission and S-SSB transmission according to some other embodiments of the present application; and

[0046] Fig.10 A simplified block diagram illustrating an exemplary apparatus for SL transmission and S-SSB transmission in an unlicensed spectrum according to some embodiments of the present application. DETAILED DESCRIPTION

[0047] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be accomplished by different embodiments that are intended to be included in the spirit and scope of the present application.

[0048] Although the operations are depicted in a particular order in the drawings, it should be readily recognized by those skilled in the art that such operations need not be performed in the particular order shown or in sequential order or that all of the illustrated operations need not be performed to achieve a desired result; one or more operations may sometimes be skipped. In addition, the drawings may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In certain scenarios, multitasking and parallel processing may be advantageous.

[0049] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., 3GPP LTE and LTE Advanced, 3GPP 5G Radio (NR), 5G Advanced, 6G, etc.). It should be considered that, as network architectures and new service scenarios evolve, all embodiments in the present application are also applicable to similar technical problems; and in addition, the terms listed in the present application may be changed, which should not affect the principles of the present application.

[0050] Figure 1 An exemplary wireless communication system 100 is illustrated in accordance with some embodiments of the present application.

[0051] like Figure 1 As shown in FIG. 1 , the wireless communication system 100 includes at least one UE 101 and at least one BS 102. Specifically, for illustration purposes, the wireless communication system 100 includes two UEs 101 (eg, UE 101a and UE 101b) and one BS 102. Figure 1 A specific number of UEs 101 and BSs 102 are depicted in FIG. 1 , but it is contemplated that any number of UEs 101 and BSs 102 may be included in wireless communication system 100 .

[0052] According to some embodiments of the present disclosure, UE 101 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (such as a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a vehicle-mounted computer, a network device (such as a router, a switch, and a modem), or the like.

[0053] According to some other embodiments of the present disclosure, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals over a wireless network.

[0054] According to some other embodiments of the present disclosure, UE 101 may include a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, or the like.

[0055] According to some embodiments of the present disclosure, UE 101 may include a vehicle UE (VUE) and / or a power saving UE (also referred to as a power sensitive UE). The power saving UE may include a vulnerable traffic unit (VRU), a public safety UE (PS-UE), and / or a commercial sidelink UE (CS-UE) that is sensitive to power consumption. In an embodiment of the present disclosure, the VRU may include a pedestrian UE (P-UE), a cyclist UE, a wheelchair UE, or other UE that needs to save power compared to the VUE.

[0056] Furthermore, UE 101-A may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal or a device, or described using other terms used in the art.

[0057] In a sidelink communication system, a transmission UE may also be referred to as a transmitting UE, Tx UE, sidelink Tx UE, sidelink transmission UE or the like, and a reception UE may also be referred to as a receiving UE, Rx UE, sidelink Rx UE, sidelink reception UE or the like.

[0058] according to Figure 1 In some embodiments of the present invention, UE 101a acts as a Tx UE and UE 101b acts as an Rx UE. UE 101a can exchange sidelink messages with UE 101b via a sidelink (e.g., via a PC5 interface defined in 3GPP TS23.303). UE 101a can transmit information or data to other UEs in the sidelink communication system via sidelink unicast, sidelink multicast, or sidelink broadcast. For example, UE 101a can transmit data to UE 101b in a sidelink unicast session. UE 101a can transmit data to UE 101b and other UEs in a multicast group via a sidelink multicast transmission session. Figure 1 In addition, UE 101a may transmit data to UE 101b and other UEs via a sidelink broadcast transmission session ( Figure 1 not shown).

[0059] Alternatively, according to Figure 1 In some other embodiments, UE 101b acts as a Tx UE and transmits a sidelink message, and UE 101a acts as a Rx UE and receives a sidelink message from UE 101b.

[0060] In some embodiments of the present disclosure, UE 101a may communicate with UE 101b via a licensed spectrum, while in other embodiments, UE 101a may communicate with UE 101b via an unlicensed spectrum.

[0061] Figure 1 Both UE 101a and UE 101b in the embodiments of the present invention may transmit information to BS 102 and receive control information from BS 102, for example, via an LTE or NR Uu interface. BS 102 may be distributed in a geographic area. In certain embodiments of the present disclosure, each of BS 102 may also be referred to as an access point, access terminal, base, base unit, macro cell, Node-B, evolved Node B (eNB), gNB, home Node-B, relay node or device or described using other terms used in the art. BS 102 is generally part of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding BS 102.

[0062] The wireless communication system 100 may be compatible with any type of network capable of sending and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with wireless communication networks, cellular telephone networks, networks based on time division multiple access (TDMA), networks based on code division multiple access (CDMA), networks based on orthogonal frequency division multiple access (OFDMA), LTE networks, networks based on 3GPP, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and / or other communication networks.

[0063] In some embodiments of the present disclosure, the wireless communication system 100 is compatible with the 5G NR of the 3GPP protocol, wherein the BS 102 transmits data on the downlink (DL) using an orthogonal frequency division multiplexing (OFDM) modulation scheme, and the UE 101 transmits data on the uplink (UL) using a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix OFDM (CP-OFDM) scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0064] In some embodiments of the present disclosure, BS102 may communicate using other communication protocols (e.g., IEEE 802.11 series of wireless communication protocols). In addition, in some embodiments of the present disclosure, BS102 may communicate via a licensed spectrum, while in other embodiments, BS102 may communicate via an unlicensed spectrum. The present disclosure is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In still other embodiments of the present disclosure, BS102 may communicate with UE 101 using 3GPP 5G protocols.

[0065] In NR, accommodating multiple uncoordinated UEs in unlicensed spectrum requires a channel access procedure defined for NR. After a channel access procedure is successfully performed by a communication node, the channel may be used by the communication node during a certain period until the end of the period. This period may be referred to as a COT. During the COT, one or more transmissions may be exchanged between the communication nodes, where the transmissions may be downlink transmissions or uplink transmissions.

[0066] The dynamic channel access procedure is typically used by a BS or UE to access a channel in an unlicensed spectrum. The dynamic channel access procedure may be based on LBT, where the transmitter listens to potential transmission activity on the channel before transmitting and applies a random backoff time in some cases. Two main types of dynamic channel access procedures may be defined in NR. One is a type 1 dynamic channel access procedure, which is also referred to as LBT type 1 or LBT cat4. The other is a type 2 dynamic channel access procedure, which is also referred to as LBT type 2.

[0067] The type 1 dynamic channel access procedure can be used to initiate data transmission at the beginning of COT. The initiator of the type 1 dynamic channel access procedure can be the BS or the UE. The type 1 dynamic channel access procedure can be summarized as follows.

[0068] First, the initiator listens and waits until a channel (eg, a frequency channel) is available during at least one period called a delay duration. The delay duration may be from 16 μs to several (eg, “m p ", which will be described below) 9μs time slot. As shown in Table 1 and Table 2, "m p The value of " depends on the value of the channel access priority level (CAPC) (denoted as "p"). Therefore, the delay duration depends on the value of the CAPC shown in Table 1 or Table 2 below. If the received energy during at least 4μs of each 9μs time slot is below the threshold, the channel is declared available.

[0069] Once the channel is declared available during the delay duration, the transmitter begins a random backoff procedure during which it waits for a random amount of time.

[0070] The UE begins the random backoff procedure by initializing the backoff timer with a random number within the contention window (CW). The random number is taken from a uniform distribution [0, CW] and indicates that the channel must be available for the timer duration (e.g., defined by the random number multiplied by 9 μs) before transmission can occur. The value of "CW" can be selected from the "Allowed CW" in Table 1 or Table 2 below. p Size” (minimum value is CW min，p , and the maximum value is expressed as CW max，p ), which depends on the value of CAPC.

[0071] The backoff timer is decremented by 1 for each sensing slot duration (eg, 9 μs) that the channel is sensed as idle; each time the channel is sensed as busy, the backoff timer is suspended until the channel has been idle for the delay duration.

[0072] Once the backoff timer expires (eg, the backoff timer is reduced to 0), the random backoff procedure is complete and the transmitter has acquired the channel and can use it to transmit up to MCOT (eg, T in Table 1 below). mcot，p Or Tul in Table 2 below mcot，p , which depends on the value of CAPC).

[0073] Table 1 and Table 2 below respectively illustrate exemplary CAPC for DL ​​and CAPC and m for UL. p , CW min，p , CW max，p , T mcot，p , T ulmcot，p With permission from CWp Table 1 is the same as Table 4.1.1-1 in TS 37.213 and Table 2 is the same as Table 4.2.1-1 in TS 37.213. When the BS wishes to initiate channel occupation for DL ​​transmission, it may determine the CAPC value before performing the Type 1 channel access procedure, and then determine the corresponding value (e.g., m) used in the Type 1 channel access procedure according to Table 1. p , CW min，p , CW max，p , T mcot，p With permission from CW p When the UE wishes to initiate channel occupation for UL transmission, it may determine the CAPC value before performing the Type 1 channel access procedure, and then determine the corresponding value (e.g., m) for use in the Type 1 channel access procedure according to Table 2. p , CW min，p , CW max，p , T ulmcot，p With permission from CW p size).

[0074] Table 1: Channel access priority levels for DL

[0075]

[0076] Table 2: Channel access priority levels for UL

[0077]

[0078]

[0079] The size of the contention window can be adjusted based on the Hybrid Automatic Repeat Request (HARQ) reports received from the transmitter during a reference time interval covering the start of the COT. For each HARQ report received, if a negative HARQ report (e.g., a negative acknowledgement (NACK)) is received, the contention window is (roughly) doubled up to the limit CW max,p For a positive HARQ report (eg, an acknowledgement (ACK)), the contention window is reset to its minimum value, ie, CW = CW min,p .

[0080] The type 2 dynamic channel access procedure can be used for transmission of COT sharing and discovery bursts. Depending on the duration of the gap in the COT (also referred to as the "COT sharing gap"), the type 2 dynamic channel access procedure can be further divided into the following three procedures, where which procedure to use can be determined depending on the duration of the gap between two transmission bursts.

[0081] Type 2A dynamic channel access procedure (also known as LBT cat2 or LBT type 2A): It is used to discover bursty transmissions when the gap is 25 μs or larger.

[0082] Type 2B dynamic channel access procedure (also known as LBT Type 2B): It is used when the gap is 16 μs.

[0083] • Type 2C dynamic channel access procedure (also known as LBT Type 2C): It is used when the gap is 16 μs or less after the previous transmission burst.

[0084] For Type 2C dynamic channel access procedure, no idle sensing is required between transmission bursts. In this scenario, the duration of a transmission burst is limited to a maximum of 584 μs. This short transmission burst can carry a small amount of user data, uplink control information (UCI), such as HARQ status reports and channel state information (CSI) reports.

[0085] The Type 2A dynamic channel access procedure and the Type 2B dynamic channel access procedure may be similar to the Type 1 dynamic channel access procedure but without random backoff. That is, in the Type 2A dynamic channel access procedure and the Type 2B dynamic channel access procedure, if the channel is detected as idle in the gap, it is declared available; if it is detected as busy, COT sharing has failed and COT sharing cannot be used for transmission in this COT. If the COT sharing gap is 16μs, the Type 2B dynamic channel access procedure may be used and the channel must be detected as idle in the 16μs gap before the next transmission burst. If the COT sharing gap is 25μs or longer, the Type 2A dynamic channel access procedure may be used and the channel must be detected as idle during at least 25μs immediately before the next transmission burst.

[0086] The above embodiments provide some dynamic channel access procedures in the unlicensed spectrum of NR. These dynamic channel access procedures can also be applied to sidelink transmissions in the unlicensed spectrum.

[0087] The S-SSB, which consists of a physical sidelink broadcast channel (PSBCH), a sidelink primary synchronization signal (S-PSS) and a sidelink secondary synchronization signal (S-SSS), carries sidelink synchronization information. Figure 2 Exemplary S-SSB time slots according to some embodiments of the present disclosure are described. Figure 2 In the embodiment, a normal cyclic prefix (CP) is used.

[0088] refer to Figure 2, S-SSB occupies one time slot in the time domain and occupies 11 resource blocks (RBs) in the frequency domain. Each RB spans 12 subcarriers, so the S-SSB bandwidth is 132 (11×12) subcarriers. Figure 2 In the example of , the S-SSB slot may include a total of 14 OFDM symbols, e.g., symbol #0 to symbol #13. The S-PSS is repeatedly transmitted on the second and third symbols (e.g., symbol #1 and symbol #2) in the S-SSB slot. The S-SSS is repeatedly transmitted on the fourth and fifth symbols (e.g., symbol #3 and symbol #4) in the S-SSB slot. The S-PSS and S-SSS occupy 127 subcarriers in the frequency domain, from the third subcarrier to the 129th subcarrier relative to the beginning of the S-SSB bandwidth.

[0089] S-PSS and S-SSS are collectively referred to as Sidelink Synchronization Signal (SLSS). SLSS is used for time and frequency synchronization. By detecting the SLSS sent by a synchronization reference UE (also referred to as a SyncRef UE), a UE is able to synchronize to the SyncRef UE and estimate the start of a frame and a carrier frequency offset.

[0090] The S-PSS can be generated from a maximum length sequence (m-sequence) using the same design (i.e., generator polynomial, initial value, cyclic shift, etc.) used to generate the m-sequence in the primary synchronization signal (PSS) in the 3GPP document. In NR Uu, there are three candidate sequences for the PSS. However, only two candidate sequences are used for the S-PSS.

[0091] The S-SSS can be generated from a Gold sequence using the same design (i.e., generator polynomial, initial value, cyclic shift, etc.) used to generate the Gold sequence for the Secondary Synchronization Signal (SSS) in the 3GPP document. This results in 336 candidate sequences for the S-SSS, such as the SSS in NR Uu.

[0092] For the transmission of SLSS within S-SSB, SyncRef UE can select S-PSS and S-SSS from the candidate sequences based on SLSS identifier (ID). SLSSID represents the identifier of SyncRef UE and conveys the priority of SyncRef UE, as in LTEV2X. Each SLSSID corresponds to a unique combination of S-PSS and S-SSS among 2 S-PSS candidate sequences and 336 S-SSS candidate sequences.

[0093] The main purpose of PSBCH is to provide system-wide information and synchronization information, which is required by the UE to establish a sidelink connection. Figure 2In the example of , the PSBCH is transmitted on the first symbol (e.g., symbol #0) and eight symbols (e.g., symbol #5 to symbol #12) after the S-SSS in the S-SSB slot. In the case of using extended CP, the PSBCH is transmitted on the first symbol and six symbols after the S-SSS in the S-SSB slot. The PSBCH occupies 132 subcarriers in the frequency domain. The PSBCH in the first symbol of the S-SSB slot is used for automatic gain control (AGC). The last symbol (e.g., symbol #13) in the S-SSB slot is used as a guard symbol.

[0094] The UE may be configured with a configuration for an S-SSB period including one or more S-SSB opportunities.

[0095] Figure 3 An exemplary distribution of S-SSB opportunities in the time domain according to some embodiments of the present disclosure is described.

[0096] exist Figure 3 In the example, one S-SSB window is included in one S-SSB period. It is considered that in other examples, more S-SSB windows may be included in one S-SSB period. The S-SSB period may also include resources for SL transmission, which do not overlap with the S-SSB window in the time domain. The resource pool may define the overall time and frequency domain resources available for SL transmission within a carrier. In other words, the resources used for SL transmission in the S-SSB period are in the resource pool. The SL transmission in the embodiments of the present disclosure may refer to at least one of the following: a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH). In the time domain, the resource pool consists of a group of time slots that are repeated within the resource pool period. Although the time slot groups within the resource pool are logically organized in a continuous manner, in fact the time slots within the resource pool may be discretely distributed in the time domain.

[0097] like Figure 3 As shown in FIG. 1 , the S-SSB window includes N S-SSB opportunities, namely S-SSB opportunity #0, S-SSB opportunity #1, ..., S-SSB opportunity #N-1.

[0098] exist Figure 3 The length of the S-SSB period is labeled "S-SSB period". There is an offset between the start of the S-SSB period and the start of the S-SSB window, which is Figure 3 Marked as "T 偏移,1 There is another offset between the end of the S-SSB window and the beginning of the resources in the resource pool, which is Figure 3 Marked as "T 偏移,2 There is a gap between two adjacent S-SSB opportunities (e.g., the start time slots of two adjacent S-SSB opportunities), which is Figure 3 Marked as "T 间隔 Therefore, the configuration of an S-SSB period may include the parameter "S-SSB period", the parameter "T 偏移,1 ”、Parameter “T 间隔 ” or at least one of a parameter “N” indicating the number of S-SSB opportunities within one S-SSB window (or one S-SSB period).

[0099] In 3GPP Release 16 (Rel-16) or Release 17 (Rel-17), the S-SSB period may contain 160ms, as specified in NR V2X. However, as network architecture and new service scenarios evolve, the S-SSB period may have other values, which should not affect the principles of the present disclosure.

[0100] Figure 2 The structure of the S-SSB time slot in Figure 3 The timing distribution of S-SSB in is for illustrative purposes only. It is considered that with the development of network architecture and new service scenarios, S-SSB may have other structures (for example, S-SSB may include 4 OFDM symbols or 6 OFDM symbols in the time domain) and the timing distribution of S-SSB within an S-SSB period or a window may change, which should not affect the principles of the present application.

[0101] In some cases of the present disclosure, the S-SSB is not frequency multiplexed with any other SL physical channel (e.g., PSCCH or PSSCH) within the SL BWP, that is, the S-SSB is not transmitted in a time slot of the resource pool.

[0102] As a feature in unlicensed bands, COT-based transmission is promising for application in sidelinks. Considering NR Uu links in unlicensed bands, the length of MCOT can be up to 10ms. Therefore, there may be a situation where the S-SSB opportunity is multiplexed with the SL transmission slot in the time domain within one COT.

[0103] In addition, the following issues are involved within the scope of Release 18 (Rel-18) sidelink studies: (1) whether or how to support shorter S-SSB durations (e.g., S-SSB durations less than one time slot); (2) whether or how to introduce more S-SSB opportunities than Rel-16 or Rel-17; and (3) whether or how to support a time slot structure in which data transmission is not constrained by time slot boundaries.

[0104] In view of the above, new time slot structures for SL transmission and S-SSB transmission and corresponding UE behaviors need to be defined to aim at reducing the loss of channel access opportunities for UEs during COT-based SL transmission caused by periodic S-SSB opportunities.

[0105] Embodiments of the present application provide improved solutions for SL transmission and S-SSB transmission in unlicensed spectrum. For example, embodiments of the present application define a new time slot structure for multiplexing S-SSB and SL transmission within COT in an unlicensed band. In addition, embodiments of the present application also propose configurations, signaling, and procedures for performing COT-based SL transmission in an unlicensed band. More details will be described below in conjunction with the accompanying drawings.

[0106] Figure 4 A flow chart illustrating an exemplary method 400 for SL transmission and S-SSB transmission according to some embodiments of the present application. Figure 4 The method 400 described in the above may be performed by a UE (eg, Figure 1 The UE 101a or UE 101b in the COT or other devices with the same function may also be referred to as the initiating UE or COT initiator.

[0107] like Figure 4 As shown in FIG. 4 , in step 401, the UE may obtain time slot structure information of the unlicensed spectrum based on configuration or pre-configuration.

[0108] In some embodiments of the present application, the UE may obtain the time slot structure information based on the configuration. Specifically, obtaining the time slot structure information based on the configuration (i.e., configuring the time slot structure information for the UE) may refer to: the time slot structure information is provided by the BS (e.g., Figure 1 BS102 shown in FIG) transmits to UE via at least one of the following: SIB message, MIB message, RRC signaling or MAC CE or DCI, so that UE can receive time slot structure information from BS. In an embodiment of the present application, obtaining time slot structure information based on configuration can be applied to a scenario in which UE is within the coverage of the network.

[0109] In some other embodiments of the present application, the UE may obtain the time slot structure information based on pre-configuration. Specifically, obtaining the time slot structure information based on pre-configuration (i.e., pre-configuring the time slot structure information for the UE) may refer to: the time slot structure information may be hardwired into the UE or stored on a subscriber identity module (SIM) or a universal subscriber identity module (USIM) card of the UE, so that the UE may obtain the time slot structure information within the UE. In an embodiment of the present application, obtaining the time slot structure information based on pre-configuration may be applied to a scenario in which the UE is out of coverage of the network.

[0110] In some embodiments of the present application, the time slot structure information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth portion, per frequency range, or per SCS.

[0111] The time slot structure information of the unlicensed spectrum may include at least one of the following:

[0112] The first set of starting symbols for SL transmission (also referred to as first symbols): The starting symbol or first symbol for SL transmission may be defined by an indicator indicating the position of the first symbol for SL transmission, e.g.

[0113] A set of starting symbols may be indicated by a set of indices of the first symbol used for SL transmission;

[0114] · A second set of starting symbols (also referred to as first symbols) and duration of an S-SSB opportunity: the starting symbol or first symbol of the S-SSB opportunity may be defined by an indicator indicating the position of the first symbol of the S-SSB opportunity, for example, the second set of starting symbols of the S-SSB opportunity may be indicated by a set of indices of the first symbol of the S-SSB opportunity; in some cases, the duration of the S-SSB opportunity may be one time slot including a guard symbol; in some other cases, the duration of the S-SSB opportunity may be less than one time slot (e.g., 4 OFDM symbols or 6 OFDM symbols); or

[0115] Time domain information indicating whether a time slot includes an S-SSB opportunity: For example, the time domain information may be a bitmap, and each bit of the bitmap may correspond to a time slot in the resource pool, for example, a bit value of "0" indicates that the corresponding time slot does not include an S-SSB opportunity, and a bit value of "1" indicates that the corresponding time slot includes an S-SSB opportunity, or vice versa; in another example, the time domain information may include configuration information for indicating the distribution of S-SSB opportunities (for example, refer to Figure 3 The configuration information described in the example) and the configuration information for SL transmission in the resource pool, so that the UE can determine whether the time slot contains the S-SSB opportunity based on the above two configuration information; the time domain information in the above example is only for illustration purposes, and after consideration,

[0116] The time domain information may be any other information for indicating whether a time slot includes an S-SSB opportunity.

[0117] In step 403, the UE may perform a channel access procedure based on the time slot structure information to initiate a COT for SL transmission. The COT may include multiple consecutive time slots. The specific operations performed in step 403 will be described in detail below.

[0118] The distribution of S-SSB opportunities and SL transmission resources in the time domain can be divided into the following three cases (ie, Case 1, Case 2, and Case 3) by considering whether the S-SSB opportunity can be positioned within the time slot used for SL transmission.

[0119] Case 1

[0120] In case 1, the S-SSB opportunity cannot be located in the time slot used for SL transmission. In other words, the S-SSB opportunity and SL transmission are not allowed to be located in the same time slot.

[0121] In some embodiments of case 1, the duration or S-SSB opportunity may be one time slot, such as Figure 2 As shown in . In some other embodiments of Case 1, considering the wider bandwidth in the unlicensed band, the duration of the S-SSB opportunity (or S-SSB) may be reduced, and thus the total duration of a given number of S-SSB opportunities may be limited to a shorter range. For example, the duration of the S-SSB opportunity (or S-SSB) may be 4 OFDM symbols (i.e., 4 symbols) or 6 OFDM symbols (i.e., 6 symbols). This S-SSB opportunity (or S-SSB) may be referred to as a 4-symbol S-SSB opportunity (or 4-symbol S-SSB) or a 6-symbol S-SSB opportunity (6-symbol S-SSB). In view of this, the starting symbol and duration of the S-SSB opportunity within the time slot may be included in the time slot structure information obtained in step 401.

[0122] Based on the time slot structure information, the UE may perform a channel access procedure in step 403 to initiate a COT for SL transmission. In some cases, at least one time slot in the COT includes an S-SSB opportunity. In some other cases, none of the multiple consecutive time slots in the COT includes an S-SSB opportunity.

[0123] Figure 5 An exemplary COT in case 1 according to some embodiments of the present application is illustrated.

[0124] refer to Figure 5 , the UE may perform a channel access procedure (e.g., LBT type 1 procedure) before time slot #i to initiate a COT for SL transmission starting from time slot #i. The COT may include 4 time slots, e.g., time slot #i, time slot #i+1, time slot #i+2, and time slot #i+3. The UE may determine that time slot #i+1 and time slot #i+2 include an S-SSB opportunity, for example, based on the time domain information included in the time slot structure information.

[0125] exist Figure 5 In the example of , the time slot structure information may indicate that the first group of starting symbols for SL transmission includes symbol #0, the second group of starting symbols for S-SSB opportunity includes symbol #0 and symbol #7, and the duration of S-SSB opportunity is 4 symbols. Therefore, the UE can determine the distribution of S-SSB opportunities based on the above information, such as Figure 5 As shown in .

[0126] refer to Figure 5, it can be seen that the problem with the time slot structure in Case 1 is that the UE is prone to lose the channel access opportunity due to the long interruption caused by the S-SSB opportunity.

[0127] One possible solution to the above problem is to impose a constraint on the maximum length of the S-SSB opportunity allowed within the COT for SL transmission. The constraint can affect resource selection when the UE wants to initiate a COT. The following embodiments provide methods on how to implement the constraint.

[0128] In some embodiments of the present application, the time slot structure information may further indicate the maximum duration of the S-SSB allowed within the COT for SL transmission (e.g., represented by MaxS-SSBInCOTForSL). In some instances, the maximum duration may be in units of time slots, symbols, milliseconds (ms), etc. In some instances, the maximum duration may be in units of S-SSB opportunities. In step 403, the UE may perform a channel access procedure based on the maximum duration to initiate the COT for SL transmission, so that the COT is subject to the maximum duration.

[0129] In some cases, the maximum duration may be greater than 0 (e.g., not less than one time slot). Then, at least one time slot of the COT initiated in step 403 may include an S-SSB opportunity, and the duration of the S-SSB within the COT is not greater than the maximum duration. For example, assuming that the maximum duration is 3 time slots, the UE may perform a channel access procedure to initiate the COT (e.g., Figure 5 The COT described in ), where the duration of the S-SSB within the COT is 2 time slots.

[0130] In some other cases, the maximum duration may be equal to 0, which means that the COT may not include any S-SSB opportunities.

[0131] In some other embodiments of the present application, the constraint may be a provision that the S-SSB opportunity should not be included in the COT for SL transmission. This provision may be configured or pre-configured for the UE. For example, the time slot structure information obtained in step 401 may indicate that the COT for SL transmission does not include any S-SSB opportunity. Then, in step 403, the UE may perform a channel access procedure to initiate the COT for SL transmission so that the COT does not include any S-SSB opportunity.

[0132] In case 1, when the UE wishes to initiate COT-based SL transmission, the UE may perform a procedure including at least the following steps.

[0133] In step 1-1, if the UE wishes to initiate a COT starting from a time slot (e.g., time slot #i) for SL transmission (in some cases, the COT may be subject to the above constraints), the UE may initiate a COT counter (e.g., consisting of N C Indicates), where the initial value is N slot COT (Time Slot #i) (i.e., N C =N slot COT (time slot #i)), where N slot COT (Slot #i) indicates the length of the COT starting from slot #i (eg, in units of slots). Next, the UE goes to step 1-2.

[0134] In step 1-2, the UE may perform a channel access procedure (e.g., LBT type 1 procedure) associated with (e.g., for) time slot #i to initiate a COT starting from time slot #i. In response to determining that the channel is available before time slot #i based on the channel access procedure, the UE proceeds to step 1-3. Otherwise, in response to a channel access failure, the UE stops the procedure.

[0135] In step 1-3, the UE may transmit SL transmission on the first available time slot based on the corresponding channel access procedure. In addition, in step 1-3, the UE may also enable N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 1-4. Otherwise, C In case the current value of is not greater than 0, the UE stops the procedure.

[0136] In step 1-4, the UE may determine the type of the next time slot, wherein the type of the next time slot may indicate whether the next time slot is used for SL transmission or for S-SSB transmission. In other words, the type of the next time slot may indicate whether the next time slot includes an S-SSB opportunity or includes a time domain resource for SL transmission. If the next time slot is used for SL transmission, the UE proceeds to step 1-5. Otherwise, if the next time slot is used for S-SSB transmission, the UE may perform S-SSB transmission in the next time slot or skip the next time slot according to the UE's intention, and then use N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 1-4. Otherwise, C In case the current value of is not greater than 0, the UE stops the procedure.

[0137] In step 1-5, the UE may perform an LBT type 2 procedure associated with the next time slot. In response to determining that the channel is available before the next time slot based on the LBT type 2 procedure, the UE proceeds to step 1-3. Otherwise, in response to a channel access failure, the UE stops the procedure.

[0138] Case 2

[0139] In case 2, the S-SSB opportunity and the SL transmission may be located within the time slot, and the time domain resources used for the SL transmission may be located before the S-SSB opportunity within the time slot.

[0140] In case 2, since the S-SSB opportunity and the SL transmission can be located within the time slot, the maximum gap between two adjacent SL transmissions can be limited to about the length of the S-SSB opportunity. Therefore, the time slot structure in case 2 can solve the above-mentioned problem in case 1.

[0141] In case 2, the duration of the S-SSB opportunity (or S-SSB) may be less than one time slot. For example, the duration of the S-SSB opportunity (or S-SSB) may be 4 OFDM symbols (i.e., 4 symbols) or 6 OFDM symbols (i.e., 6 symbols). In view of this, the starting symbol and duration of the S-SSB opportunity in the time slot may be included in the time slot structure information obtained in step 401.

[0142] In step 403, the UE may perform a channel access procedure based on the time slot structure information to initiate a COT for SL transmission. In some cases, at least one time slot within the COT may include both an S-SSB opportunity and a time domain resource for SL transmission, and the time domain resource for SL transmission is located before the S-SSB opportunity. In some other cases, none of the multiple consecutive time slots in the COT includes an S-SSB opportunity.

[0143] Figure 6 An exemplary COT in Case 2 according to some embodiments of the present application is illustrated.

[0144] refer to Figure 6 , the UE may perform a channel access procedure (e.g., LBT type 1 procedure) before time slot #i to initiate a COT for SL transmission starting from time slot #i. The COT may include 4 time slots, e.g., time slot #i, time slot #i+1, time slot #i+2, and time slot #i+3. The UE may determine that time slot #i+1 and time slot #i+2 include an S-SSB opportunity, for example, based on the time domain information included in the time slot structure information.

[0145] exist Figure 6In the example of , the time slot structure information may indicate that the first group of starting symbols for SL transmission includes symbol #0, the second group of starting symbols for S-SSB opportunity includes symbol #9, and the duration of S-SSB opportunity is 4 symbols. Therefore, the UE can determine the distribution of S-SSB opportunities based on the above information, such as Figure 6 As shown in .

[0146] refer to Figure 6 It can be seen that the problem of the time slot structure in case 2 is that a conflict between the S-SSB opportunity and the PSFCH may occur because both the S-SSB opportunity and the PSFCH are near the end of the time slot. The following embodiments may provide a method for solving the above problem.

[0147] In some embodiments, S-SSB and PSFCH may be periodically configured in a resource pool for SL transmission. In such embodiments, the time slot structure information may also indicate a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with the position of the PSFCH in the time slot.

[0148] In some embodiments, S-SSB may be periodically configured within a resource pool for SL transmission and PSFCH may be non-periodically configured within a resource pool for SL transmission. In such embodiments, the UE may transmit an indication of the location of the PSFCH that does not overlap with the S-SSB opportunity.

[0149] In some embodiments, the UE may further obtain an indication of whether the position is for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a certain position based on configuration or pre-configuration. For example, the indication may be included in the time slot structure information obtained in step 401.

[0150] In an embodiment, the indication may be based on the priority of S-SSB or PSFCH. For example, in the case where S-SSB takes precedence over PSFCH, the indication may indicate that the position is for S-SSB when a conflict between S-SSB and PSFCH occurs at the position. In the case where PSFCH takes precedence over S-SSB, the indication may indicate that the position is for PSFCH when a conflict between S-SSB and PSFCH occurs at the position.

[0151] In another embodiment, the indication may be defined as a default value, and the default value may indicate whether the position is used for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a position. For example, the default value may be "0", which indicates that the position is used for S-SSB when a conflict between S-SSB and PSFCH occurs at a position, or the default value may be "1", which indicates that the position is used for PSFCH when a conflict between S-SSB and PSFCH occurs at a position.

[0152] In the above embodiments, the position of the PSFCH may refer to a symbol of the PSFCH or a time slot of the PSFCH.

[0153] In case 2, when the UE wishes to initiate COT-based SL transmission, the UE may perform a procedure including at least the following steps.

[0154] In step 2-1, if the UE wishes to initiate a COT starting from a time slot (eg, time slot #i) for SL transmission, the UE may initiate a COT counter (eg, consisting of N C Indicates), where the initial value is N slot COT (Time Slot #i) (i.e., N C =N slot COT (time slot #i)), where N slot COT (Slot #i) indicates the length of the COT starting from slot #i (eg, in units of slots). Next, the UE proceeds to step 2-2.

[0155] In step 2-2, the UE may perform a channel access procedure (e.g., LBT type 1 procedure) associated with (e.g., for) time slot #i to initiate a COT starting from time slot #i. In response to determining that the channel is available before time slot #i based on the channel access procedure, the UE proceeds to step 2-3. In addition, in response to a channel access failure, the UE stops the procedure.

[0156] In step 2-3, the UE may transmit the SL transmission on the first available time slot based on the corresponding channel access procedure. In addition, in step 2-3, the UE may also enable N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 2-4. Otherwise, C In case the current value of is not greater than 0, the UE stops the procedure.

[0157] In step 2-4, the UE may determine the type of the next time slot, wherein the type of the next time slot may indicate whether the next time slot is used for SL transmission or for both SL transmission and S-SSB transmission. In other words, the type of the next time slot may indicate whether the next time slot includes only time domain resources for SL transmission or includes S-SSB opportunities. If the next time slot is used for SL transmission, the UE proceeds to step 2-5; otherwise, if the next time slot is used for both SL transmission and S-SSB transmission, the UE proceeds to step 2-6.

[0158] In step 2-5, the UE may perform an LBT type 2 procedure associated with SL transmission in the next time slot. In response to the channel being available for access before the next time slot based on the LBT type 2 procedure, the UE proceeds to step 2-3. Otherwise, in response to the channel access failure, the UE stops the procedure.

[0159] In step 2-6, the UE may perform an LBT type 2 procedure associated with SL transmission in the next time slot. In response to the channel being available for access before the next time slot based on the LBT type 2 procedure, the UE may perform the SL transmission. Otherwise, in response to the channel access failure, the UE stops the procedure.

[0160] In step 2-6, after performing the SL transmission, the UE may further perform S-SSB transmission in the same time slot (e.g., after the S-SSB transmission procedure) or skip the S-SSB transmission according to the UE's intention. In some embodiments, the S-SSB transmission procedure may include performing an LBT type 2 procedure associated with the S-SSB opportunity before performing the S-SSB transmission on the S-SSB opportunity.

[0161] In step 2-6, after performing or skipping S-SSB transmission, at the end of the transmission opportunity in the time slot, the UE may use N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 2-4. Otherwise, C In case the current value of is not greater than 0, the UE stops the procedure.

[0162] Case 3

[0163] In case 3, the S-SSB opportunity and the SL transmission may be located within the time slot, and the S-SSB opportunity may be located before the time domain resources used for the SL transmission within the time slot.

[0164] In case 3, since the S-SSB opportunity and the SL transmission can be located within the time slot, the maximum gap between two adjacent SL transmissions can be limited to about the length of the S-SSB opportunity. Therefore, the time slot structure in case 3 can solve the above-mentioned problem in case 1. In addition, since the S-SSB opportunity is located in the front part of the time slot, the time slot structure of case 3 can avoid the possible conflict between the S-SSB and the PSFCH in case 2.

[0165] In case 3, SL transmission may have different starting symbols in different time slots. Therefore, different starting symbols for SL transmission may be included in the time slot structure information obtained in step 401. In addition, the duration of the S-SSB opportunity (or S-SSB) in case 3 may be less than one time slot. For example, the duration of the S-SSB opportunity (or S-SSB) may be 4 OFDM symbols (i.e., 4 symbols) or 6 OFDM symbols (i.e., 6 symbols). In view of this, the duration of the S-SSB opportunity may be included in the time slot structure information obtained in step 401.

[0166] In step 403, the UE may perform a channel access procedure based on the time slot structure information to initiate a COT for SL transmission. In some cases, at least one time slot in the COT may include both an S-SSB opportunity and a time domain resource for SL transmission, and the S-SSB opportunity is located before the time domain resource for SL transmission. In some other cases, none of the multiple consecutive timings in the COT includes an S-SSB opportunity.

[0167] Figure 7 An exemplary COT in case 3 according to some embodiments of the present application is illustrated.

[0168] refer to Figure 7 , the UE may perform a channel access procedure (e.g., LBT type 1 procedure) before time slot #i to initiate a COT for SL transmission starting from time slot #i. The COT may include 4 time slots, e.g., time slot #i, time slot #i+1, time slot #i+2, and time slot #i+3. The UE may determine that time slot #i+1 and time slot #i+2 include an S-SSB opportunity, for example, based on the time domain information included in the time slot structure information.

[0169] exist Figure 7 In an example of , the time slot structure information may indicate: the first group of starting symbols for SL transmission includes symbol #0 and symbol #5, where symbol #0 may be the starting symbol of SL transmission in a time slot that only includes SL transmission (e.g., time slot #i and time slot #i+3), and symbol #5 may be the starting symbol of SL transmission in a time slot that includes both SL transmission and S-SSB opportunity (e.g., time slot #i+1 and time slot #i+2); the second group of starting symbols for S-SSB opportunity includes symbol #0; and the duration of S-SSB opportunity is 4 symbols. Therefore, the UE may determine the distribution of S-SSB opportunities based on the above information, such as Figure 7 As shown in .

[0170] In case 3, when the UE wishes to initiate COT-based SL transmission, the UE may perform a procedure including at least the following steps.

[0171] In step 3-1, if the UE wishes to initiate a COT starting from a time slot (eg, time slot #i) for SL transmission, the UE may initiate a COT counter (eg, counted by N C Indicates), where the initial value is N slot COT (Time Slot #i) (i.e., N C =N slot COT (time slot #i)), where N slot COT (Slot #i) indicates the length of the COT starting from slot #i (eg, in units of slots). Next, the UE proceeds to step 3-2.

[0172] In step 3-2, the UE may perform a channel access procedure (e.g., LBT type 1 procedure) associated with (e.g., for) time slot #i to initiate a COT starting from time slot #i. In response to determining that the channel is available before time slot #i based on the channel access procedure, the UE proceeds to step 3-3. Otherwise, in response to a channel access failure, the UE stops the procedure.

[0173] In step 3-3, the UE may transmit SL transmission on the first available time slot based on the corresponding channel access procedure. In addition, in step 3-3, the UE may also enable N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 3-4. Otherwise, C If the current value of is not greater than 0, the UE stops the procedure.

[0174] In step 3-4, the UE may determine the type of the next time slot, wherein the type of the next time slot may indicate whether the next time slot is used for SL transmission or for both SL transmission and S-SSB transmission. In other words, the type of the next time slot may indicate whether the next time slot includes only time domain resources for SL transmission or includes S-SSB opportunities. If the next time slot is used for SL transmission, the UE proceeds to step 3-5; otherwise, if the next time slot is used for both SL transmission and S-SSB transmission, the UE proceeds to step 3-6.

[0175] In step 3-5, the UE may perform an LBT type 2 procedure associated with SL transmission in the next time slot. In response to the channel being available for access before the next time slot based on the LBT type 2 procedure, the UE proceeds to step 3-3. Otherwise, in response to the channel access failure, the UE stops the procedure.

[0176] In step 3-6, the UE may perform S-SSB transmission in the next time slot (e.g., after the S-SSB transmission procedure) or skip S-SSB transmission according to the UE's intention. In some embodiments, the S-SSB transmission procedure may include performing an LBT type 2 procedure associated with the S-SSB opportunity before performing S-SSB transmission on the S-SSB opportunity.

[0177] In step 3-6, after performing or skipping S-SSB transmission, the UE may also perform LBT type 2 procedures associated with SL transmission in the same time slot. In response to the channel being available for access before the start symbol for SL transmission, the UE may perform SL transmission. Otherwise, in response to channel access failure, the UE stops the procedure.

[0178] In step 3-6, after performing SL transmission, at the end of the transmission opportunity in the time slot, the UE may use N C Subtract 1, that is, set N C =N C -1. In N C If the current value of is greater than 0, the UE proceeds to step 3-4. Otherwise, C In case the current value of is not greater than 0, the UE stops the procedure.

[0179] In some embodiments of Case 3, when the S-SSB opportunity before identifying the SL transmission is not used, enhanced channel access opportunities for guaranteed COT-based SL transmission can be achieved by occupying the channel.

[0180] In such embodiments, the time slot structure information may further include at least one of the following:

[0181] An indicator indicating whether to enable or disable the occupation of S-SSB opportunities by non-S-SSB transmissions (e.g., dummy data, SL transmissions, etc.) (e.g., S-SSB OccupiedByNon-S-SSB or S-SSB OccupiedBySL): In some cases, the indicator may be implemented to define UE behavior, e.g., the UE may abandon SL transmission when SL transmission overlaps with S-SSB opportunities; or

[0182] Parameter indicating the duration for identifying whether the S-SSB opportunity is used: In some embodiments, the identification of whether the S-SSB opportunity is used may be accomplished by, for example, sensing, LBT, or other methods; in some embodiments, the duration may be expressed in units of symbols, for example, the parameter may be expressed as It is the number of symbols contained in the duration; for example, Can be set to 1, which means the duration contains 1 symbol.

[0183] Based on the above information, the UE can determine the third set of starting symbols for SL transmission, which is used by the UE to perform SL transmission.

[0184] Specifically, when the indicator indicates that the occupation of S-SSB opportunities by non-S-SSB transmission is enabled, the UE may determine the third group of starting symbols for SL transmission in the time slot based on the first group of starting symbols for SL transmission and the second group of starting symbols for S-SSB opportunities. When the indicator indicates that the occupation of S-SSB opportunities by non-S-SSB transmission is disabled, the UE may determine (or set) that the third group of starting symbols for SL transmission in the time slot is the same as the first group of starting symbols for SL transmission.

[0185] For example, assume that the first set of start symbols for SL transmission (e.g., represented by Set1) indicates an index set of start symbols for SL transmission. For example, Set1 = {0, 5, 7}, where symbol #0 may be a start symbol of SL transmission in a time slot containing only SL transmission, symbol #5 may be a start symbol of SL transmission in a time slot containing an S-SSB opportunity whose duration is 4 symbols, and symbol #7 may be a start symbol of SL transmission in a time slot containing an S-SSB opportunity whose duration is 6 symbols.

[0186] In addition, it is assumed that the second set of starting symbols for the S-SSB opportunity (e.g., represented by Set2) indicates the index set of the starting symbol for the S-SSB opportunity. For example, Set2 = {0}, which means that the starting symbol of the S-SSB opportunity is symbol #0.

[0187] When S-SSBOccupiedBySL (eg, having a value of "0") indicates disabling of occupying S-SSB opportunities by non-S-SSB transmissions, the UE may set Set3 = Set1, where Set3 is the third set of starting symbols for SL transmission.

[0188] When S-SSBOccupiedBySL (e.g., has a value of "1") indicates enabling the seizure of S-SSB opportunities by non-S-SSB transmissions, the UE may set assumed Set3 = {0,1,5,7}. That is, if the S-SSB opportunity is declared by the identification operation in the If the UE is idle for a duration of symbols, the UE may transmit an SL transmission from the symbol immediately after the identification operation.

[0189] In such an embodiment, the S-SSB transmission and SL transmission in the time slot in the above procedure in Case 3 may be changed. For example, the operations in Steps 3-6 may be changed.

[0190] For example, when the indicator indicates enabling occupation of the S-SSB opportunity by non-S-SSB transmission and the UE does not want to transmit an S-SSB on the S-SSB opportunity within the time slot that includes both the S-SSB opportunity and the time domain resources for SL transmission, the UE may perform at least one of the following steps relative to the S-SSB opportunity.

[0191] In step 4-1, the UE may perform an LBT type 2 procedure associated with the S-SSB opportunity. In response to determining that the channel is available for access before the S-SSB opportunity based on the LBT type 2 procedure, the UE proceeds to step 4-2. Otherwise, in response to a channel access failure, the UE may skip the S-SSB opportunity.

[0192] In step 4-2, the UE may perform the following operations for a duration (eg, In response to determining that the S-SSB opportunity is not used (e.g., declaring the channel to be idle), the UE proceeds to step 4-3. Otherwise, the UE may skip the S-SSB opportunity.

[0193] In step 4-3, the UE may perform non-S-SSB transmission until the S-SSB opportunity ends. Alternatively or in addition, the UE may perform SL transmission until the time slot containing the S-SSB opportunity ends.

[0194] Figure 8 An exemplary procedure including operations for identifying unused S-SSB opportunities in Case 3 according to some other embodiments of the present application is described.

[0195] Figure 7 All assumptions in Figure 8 In addition, it is further assumed that the time slot structure information includes an indicator indicating enabling occupation of the S-SSB opportunity by non-S-SSB transmission and further includes a parameter indicating that the duration for identifying whether the S-SSB opportunity is used is 1 symbol.

[0196] refer to Figure 8, before an S-SSB opportunity (e.g., an S-SSB opportunity in slot #i+1 or an S-SSB opportunity in slot #i+2), the UE may perform an LBT type 2 procedure associated with the S-SSB opportunity. In response to determining based on the LBT type 2 procedure that the channel is available for access before the S-SSB opportunity and the UE does not want to transmit an S-SSB at the S-SSB opportunity, the UE may perform a sensing operation or LBT within the first symbol in the S-SSB opportunity. In response to determining that the S-SSB opportunity is not used (e.g., declaring the channel to be idle), the UE may transmit a non-S-SSB transmission (e.g., dummy data) until the S-SSB opportunity ends, or transmit an SL transmission until the corresponding time slot ends.

[0197] Fig. 9 Flowchart illustrating an exemplary method 900 for SL transmission and S-SSB transmission according to some other embodiments of the present application. The method 900 may be performed by a UE (e.g., Figure 1 The UE 101a or UE 101b) or other devices with similar functions may be used for execution. The UE that receives the SL transmission may also be referred to as a receiving UE.

[0198] like Fig. 9 As shown in FIG. 9 , in step 901, the UE may obtain time slot structure information of an unlicensed spectrum based on configuration or pre-configuration.

[0199] In some embodiments of the present application, the UE may obtain the time slot structure information based on the configuration. Specifically, obtaining the time slot structure information based on the configuration (i.e., configuring the time slot structure information for the UE) may refer to: the time slot structure information is provided by the BS (e.g., Figure 1 BS102 shown in FIG) transmits to UE via at least one of the following: SIB message, MIB message, RRC signaling or MAC CE or DCI, so that UE can receive time slot structure information from BS. In an embodiment of the present application, obtaining time slot structure information based on configuration can be applied to a scenario in which UE is within the coverage of the network.

[0200] In some other embodiments of the present application, the UE may obtain the time slot structure information based on pre-configuration. Specifically, obtaining the time slot structure information based on pre-configuration (i.e., pre-configuring the time slot structure information for the UE) may refer to: the time slot structure information may be hardwired into the UE or stored on the SIM or USIM card of the UE, so that the UE may obtain the time slot structure information within the UE. In an embodiment of the present application, obtaining the time slot structure information based on pre-configuration may be applied to a scenario in which the UE is out of coverage of the network.

[0201] In some embodiments of the present application, the time slot structure information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth portion, per frequency range, or per SCS.

[0202] The time slot structure information for unlicensed spectrum can be compared with the above with respect to Figures 4 to 8 The time slot structure information described is the same. Figures 4 to 8 All definitions of the described slot structure information are applicable here.

[0203] For example, the time slot structure information may include at least one of the following: a first set of starting symbols (also referred to as first symbols) for SL transmission; a second set of starting symbols (also referred to as first symbols) and duration of an S-SSB opportunity; or time domain information indicating whether the time slot includes an S-SSB opportunity.

[0204] As described above, the distribution of S-SSB opportunities and SL transmission resources in the time domain can be divided into Case 1, Case 2, and Case 3 by considering whether the S-SSB opportunity can be located within the time slot for SL transmission. All definitions of Case 1, Case 2, and Case 3 as described above are applicable here.

[0205] In some embodiments of case 1, the slot structure information may further indicate the maximum duration of the S-SSB allowed within the COT for SL transmission (e.g., represented by MaxS-SSBInCOTForSL). In some instances, the maximum duration may be in units of slots, symbols, ms, etc. In some instances, the maximum duration may be in units of S-SSB opportunities. In some cases, the maximum duration may be greater than 0. In some other cases, the maximum duration may be equal to 0.

[0206] In some other embodiments of case 1, the UE may be configured or preconfigured to specify that the COT for SL transmission should not include S-SSB opportunities. For example, the time slot structure information obtained in step 901 may indicate that the COT for SL transmission does not include any S-SSB opportunities.

[0207] In some embodiments of case 2, S-SSB and PSFCH may be periodically configured in a resource pool for SL transmission. In such embodiments, the time slot structure information may also indicate a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with the position of the PSFCH in the time slot.

[0208] In some other embodiments of Case 2, S-SSB may be periodically configured within the resource pool for SL transmission, while PSFCH may not be periodically configured within the resource pool for SL transmission. In such embodiments, the UE may receive an indication of the location of the PSFCH that does not overlap with the S-SSB opportunity.

[0209] In some other embodiments of case 2, the UE may further obtain an indication of whether the position is for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a certain position based on configuration or pre-configuration. For example, the indication may be included in the time slot structure information obtained in step 901.

[0210] In an embodiment, the indication may be based on the priority of S-SSB or PSFCH. For example, in the case where S-SSB takes precedence over PSFCH, the indication may indicate that the position is for S-SSB when a conflict between S-SSB and PSFCH occurs at the position. In the case where PSFCH takes precedence over S-SSB, the indication may indicate that the position is for PSFCH when a conflict between S-SSB and PSFCH occurs at the position.

[0211] In another embodiment, the indication may be defined as a default value, and the default value may indicate whether the position is used for S-SSB or PSFCH when a conflict between S-SSB and PSFCH occurs at a position. For example, the default value may be "0", which indicates that the position is used for S-SSB when a conflict between S-SSB and PSFCH occurs at a position, or the default value may be "1", which indicates that the position is used for PSFCH when a conflict between S-SSB and PSFCH occurs at a position.

[0212] In the above embodiments, the position of the PSFCH may refer to a symbol of the PSFCH or a time slot of the PSFCH.

[0213] In some embodiments of case 3, the time slot structure information may further include at least one of the following:

[0214] An indicator indicating whether to enable or disable the occupation of S-SSB opportunities by non-S-SSB transmissions (e.g., dummy data, SL transmissions, etc.) (e.g., S-SSB OccupiedByNon-S-SSB or S-SSB OccupiedBySL); or

[0215] · Parameter indicating the duration for identifying whether the S-SSB opportunity is used: In some embodiments, the identification of whether the S-SSB opportunity is used can be accomplished by, for example, sensing, LBT or other methods; in some embodiments, the duration can be expressed in symbols.

[0216] Based on the above information, the UE can determine the third group of starting symbols for SL transmission, which is used for the UE to receive the SL transmission.

[0217] Specifically, when the indicator indicates that the occupation of S-SSB opportunities by non-S-SSB transmission is enabled, the UE may determine the third group of starting symbols for SL transmission in the time slot based on the first group of starting symbols for SL transmission and the second group of starting symbols for S-SSB opportunities. When the indicator indicates that the occupation of S-SSB opportunities by non-S-SSB transmission is disabled, the UE may determine (or set) that the third group of starting symbols for SL transmission in the time slot is the same as the first group of starting symbols for SL transmission.

[0218] In step 903, the UE may receive the SL transmission based on the time slot structure information obtained in step 901. For example, based on the time slot structure information, the UE may determine at least one of the starting symbol for SL transmission or the starting symbol of the S-SSB opportunity within the time slot, and then may receive the SL transmission based on the starting symbol of the SL transmission. In some embodiments of the present application, the UE may receive the SL transmission based on the third group of starting symbols for SL transmission.

[0219] Fig.10 A simplified block diagram illustrating an exemplary apparatus 1000 for SL transmission and S-SSB transmission in unlicensed spectrum according to some embodiments of the present application. In some embodiments, the apparatus 1000 may be or include a UE that initiates a COT-based SL transmission or a UE that receives a SL transmission (e.g., Figure 1 In some other embodiments, the device 1000 may be or include a BS (e.g., Figure 1 At least a portion of BS102).

[0220] refer to Fig.10 , the apparatus 1000 may include at least one transmitter 1002, at least one receiver 1004, and at least one processor 1006. The at least one transmitter 1002 is coupled to the at least one processor 1006, and the at least one receiver 1004 is coupled to the at least one processor 1006.

[0221] Although in this figure, elements such as transmitter 1002, receiver 1004, and processor 1006 are illustrated in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, transmitter 1002 and receiver 1004 may be combined into one device, such as a transceiver. In some embodiments of the present application, apparatus 1000 may further include an input device, a memory, and / or other components. Transmitter 1002, receiver 1004, and processor 1006 may be configured to perform any of the methods described herein (e.g., with respect to Figures 4 to 9 ).

[0222] According to some embodiments of the present application, the device 1000 may be a UE that initiates a COT-based SL transmission, and the transmitter 1002, the receiver 1004, and the processor 1006 may be configured to perform the Figures 4 to 8 Operations of the method performed by the UE as described in any of . For example, the processor 1006 may be configured to: obtain time slot structure information of the unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of start symbols for SL transmission; a second set of start symbols and duration of an S-SSB opportunity; or time domain information indicating whether a time slot includes an S-SSB opportunity; and perform a channel access procedure based on the time slot structure information to initiate a COT for SL transmission, wherein the COT includes a plurality of consecutive time slots.

[0223] According to some embodiments of the present application, the device 1000 may be a UE that receives a SL transmission, and the transmitter 1002, the receiver 1004, and the processor 1006 may be configured to perform the corresponding Fig. 9 Operations of the described method performed by the UE. For example, the processor 1006 may be configured to: obtain time slot structure information of the unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: a first set of starting symbols for SL transmission; a second set of starting symbols and duration of S-SSB opportunities; or time domain information indicating whether the time slot includes an S-SSB opportunity. The receiver 1004 may be configured to receive the SL transmission based on the time slot structure information.

[0224] According to some embodiments of the present application, the device 1000 may be a BS, and the transmitter 1002, the receiver 1004, and the processor 1006 may be configured to perform the Figures 4 to 9 For example, the transmitter 1002 may be configured to transmit time slot structure information of the unlicensed spectrum, wherein the time slot structure information includes at least one of the following: a first set of starting symbols for SL transmission; a second set of starting symbols and duration of an S-SSB opportunity; or time domain information indicating whether a time slot includes an S-SSB opportunity.

[0225] In some embodiments of the present application, the device 1000 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1006 to implement any of the methods described above. For example, when the computer-executable instructions are executed, the processor 1006 may interact with the transmitter 1002 and / or the receiver 1004 to perform, for example, Figures 4 to 9 The operations of the methods described by any of .

[0226] The method according to the embodiments of the present application may also be implemented on a programmed processor. However, the controller, flow chart and module may also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit (such as a discrete element circuit, a programmable logic device or the like). In general, any device on which a finite state machine capable of implementing the flow chart shown in the figure resides can be used to implement the processor functions of the present application. For example, an embodiment of the present application provides an apparatus for SL transmission and S-SSB transmission in an unlicensed spectrum including a processor and a memory. Computer programmable instructions for implementing the method for SL transmission and S-SSB transmission in an unlicensed spectrum are stored in a memory, and the processor is configured to execute the computer programmable instructions to implement the method for SL transmission and S-SSB transmission in an unlicensed spectrum. The method for SL transmission and S-SSB transmission in an unlicensed spectrum may be any method described in the present application.

[0227] Alternative embodiments preferably implement methods according to embodiments of the present application in a non-transitory computer-readable storage medium storing computer programmable instructions. The instructions are preferably executed by a computer-executable component that is preferably integrated with a network security system. The non-transitory computer-readable storage medium may be stored on any suitable computer-readable medium, such as RAM, ROM, flash memory, EEPROM, optical storage device (CD or DVD), hard drive, floppy disk drive, or any suitable device. The computer-executable component is preferably a processor, but the instructions may alternatively or additionally be executed by any suitable dedicated hardware device. For example, embodiments of the present application provide a non-transitory computer-readable storage medium having computer programmable instructions stored therein. The computer programmable instructions are configured to implement the method for SL transmission and S-SSB transmission in an unlicensed spectrum according to any embodiment of the present application.

[0228] Although the present application has been described using its specific embodiments, it is obvious that many substitutions, modifications and changes can be understood by those skilled in the art. For example, the various components of the embodiments can be interchanged, added or replaced in other embodiments. In addition, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the art of the disclosed embodiments to make and use the teachings of the present application by simply adopting the elements of the independent claims. Therefore, the embodiments of the present application as described herein are intended to be illustrative rather than restrictive. Various changes can be made without departing from the spirit and scope of the present application.

Claims

1. A user equipment UE, comprising: A processor configured to: Obtaining time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: The first group of start symbols for sidelink SL transmission; The second set of starting symbols and duration of a sidelink synchronization signal block S-SSB opportunity; or Time domain information indicating whether the time slot contains an S-SSB opportunity; and Performing a channel access procedure based on the time slot structure information to initiate a channel occupation time COT for SL transmission, wherein the COT includes a plurality of consecutive time slots; a transmitter coupled to the processor; and A receiver is coupled to the processor.

2. The UE according to claim 1, wherein the time slot structure information is based on at least one of the following granularities: Bandwidth per channel, Per carrier, Per bandwidth portion, per frequency range, or The spacing between each subcarrier is SCS.

3. The UE according to claim 1, wherein the receiver is configured to receive the time slot structure information via at least one of the following: a master information block (MIB) message, a system information block (SIB) message, a radio resource control (RRC) signaling, a media access control (MAC) control element (CE), or downlink control information (DCI).

4. The UE according to claim 1, wherein at least one time slot in the COT includes an S-SSB opportunity.

5. The UE according to claim 4, wherein the time slot structure information indicates the maximum duration of the S-SSB allowed within the COT for SL transmission.

6. The UE according to claim 1, wherein at least one time slot in the COT includes both an S-SSB opportunity and a time domain resource for SL transmission, and the time domain resource for SL transmission is located before the S-SSB opportunity.

7. The UE according to claim 6, wherein: In the case where the S-SSB and the physical sidelink feedback channel PSFCH are periodically configured in the resource pool for SL transmission, the time slot structure information further indicates a time slot including an S-SSB opportunity, wherein the S-SSB opportunity is not allowed to overlap with a position of the PSFCH in the time slot; In a case where S-SSB is periodically configured within a resource pool for SL transmission and PSFCH is not periodically configured within a resource pool for SL transmission, the transmitter is configured to transmit an indication of a location of the PSFCH that does not overlap with an S-SSB opportunity; or The time slot structure information further includes an indication of whether a position is used for S-SSB or PSFCH when a collision between S-SSB and PSFCH occurs at the position.

8. The UE of claim 7, wherein the indication indicating whether the location is for S-SSB or PSFCH is based on a priority of S-SSB or PSFCH or is defined as a default value.

9. The UE according to claim 1, wherein at least one time slot in the COT includes both an S-SSB opportunity and a time domain resource for SL transmission, and the S-SSB opportunity is located before the time domain resource for SL transmission.

10. The UE according to claim 9, wherein the time slot structure information further includes at least one of the following: an indicator indicating whether to enable or disable the occupation of S-SSB opportunities by non-S-SSB transmissions; or A parameter indicating the duration for identifying whether the S-SSB opportunity is used.

11. The UE of claim 10, wherein the processor is further configured to: In a case where the indicator indicates enabling occupation of S-SSB opportunities by non-S-SSB transmissions, determining a third group of start symbols for SL transmission in a time slot based on the first group of start symbols and the second group of start symbols; or In a case where the indicator indicates deactivation of occupation of S-SSB opportunities by non-S-SSB transmissions, the third group of starting symbols used for SL transmission within the time slot is determined to be the first group of starting symbols.

12. The UE of claim 10, wherein if the indicator indicates enabling occupation of S-SSB opportunities by non-S-SSB transmissions and the UE does not wish to transmit an S-SSB on an S-SSB opportunity within a time slot in the at least one time slot, the processor is further configured to: performing a sensing operation starting from the S-SSB opportunity within the duration indicated by the parameter; In response to determining that the S-SSB opportunity is not used, performing at least one of the following operations: performing non-S-SSB transmission until the S-SSB opportunity ends; or SL transmission is performed until the end of the time slot containing the S-SSB opportunity.

13. The UE of claim 1 , wherein if at least one of the plurality of consecutive time slots includes an S-SSB opportunity, the transmitter is further configured to perform at least one of the following steps: transmitting a SL transmission in a first time slot in response to determining based on the channel access procedure that a channel is available for access prior to a first time slot within the COT; transmitting a SL transmission in a time slot other than the first time slot within the COT in response to determining that a channel is available for access prior to the SL transmission based on a listen-before-talk (LBT) type 2 procedure associated with the SL transmission; or An S-SSB transmission is transmitted on an S-SSB opportunity in a time slot within the COT or the S-SSB opportunity in the time slot is skipped.

14. A user equipment UE, comprising: A processor configured to: Obtaining time slot structure information of an unlicensed spectrum based on configuration or pre-configuration, wherein the time slot structure information includes at least one of the following: The first group of start symbols for sidelink SL transmission; The second set of starting symbols and duration of a sidelink synchronization signal block S-SSB opportunity; or Time domain information indicating whether the time slot contains an S-SSB opportunity; a receiver coupled to the processor and configured to receive a SL transmission based on the slot structure information; and A transmitter is coupled to the processor.

15. A base station BS, comprising: A transmitter configured to: Transmitting time slot structure information of an unlicensed spectrum, wherein the time slot structure information includes at least one of: The first group of start symbols for sidelink SL transmission; The second set of starting symbols and duration of a sidelink synchronization signal block S-SSB opportunity; or Time domain information indicating whether the time slot contains an S-SSB opportunity; a processor coupled to the transmitter; and A receiver is coupled to the processor.

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