Method and apparatus for S-SSB transmission in unlicensed spectrum

Abstract

The embodiment of the invention relates to a method and equipment for side link 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 configuration information for an S-SSB in an unlicensed spectrum based on a configuration or a pre-configuration, where the configuration information includes a condition for determining a channel access failure based on a Listen Before Talk (LBT) Type 1 procedure prior to a target S-SSB occasion; performing a first LBT type 1 procedure associated with a first S-SSB occasion to initiate a first S-SSB channel occupancy starting from the first S-SSB occasion; and in response to determining a channel access failure based on the first LBT type 1 procedure and the configuration information prior to the first S-SSB occasion, performing at least one of: performing a second LBT type 1 procedure associated with a second S-SSB occasion following the first S-SSB occasion, to initiate a second S-SSB channel occupancy starting from the second S-SSB occasion; continuing to execute the first LBT type 1 procedure prior to the second S-SSB occasion to initiate a second S-SSB channel occupancy starting from the second S-SSB occasion; or executing a first LBT type 2 program; a transmitter coupled to the processor and configured to transmit an S-SSB at the first S-SSB opportunity in response to a channel being available for access based on the first LBT Type 1 procedure prior to the first S-SSB opportunity; 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) synchronization signal block (SSB) transmission in unlicensed spectrum. Background Art

[0002] Sidelink is a Long Term Evolution (LTE) feature introduced in Release 12 of the 3rd Generation Partnership Project (3GPP) and enables direct communication between near-end user equipments (UEs) without the data having to pass through a base station (BS) or core network. The sidelink communication system has 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 SL SSB (S-SSB). In the unlicensed spectrum, a channel access procedure may be performed before S-SSB transmission. Therefore, a new design for S-SSB transmission in the unlicensed spectrum is needed. Summary of the invention

[0004] The embodiments of the present application at least provide a technical solution for 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 configuration information for S-SSB in an unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes a condition for determining a channel access failure based on a listen-before-talk (LBT) type 1 procedure before a target S-SSB opportunity; execute a first LBT type 1 procedure associated with a first S-SSB opportunity to start a first S-SSB channel occupancy starting from the first S-SSB opportunity; and in response to determining that the channel access failed based on the first LBT type 1 procedure and the configuration information before the first S-SSB opportunity, perform at least one of the following operations: execute the same as immediately following a second LBT type 1 procedure associated with a second S-SSB opportunity of the first S-SSB opportunity to start a second S-SSB channel occupancy starting from the second S-SSB opportunity; continuing to execute the first LBT type 1 procedure before the second S-SSB opportunity to start a second S-SSB channel occupancy starting from the second S-SSB opportunity; or executing a first LBT type 2 procedure; a transmitter, which is coupled to the processor and configured to transmit an S-SSB at the first S-SSB opportunity in response to the channel being available for access based on the first LBT type 1 procedure before the first S-SSB opportunity; and a receiver, which is coupled to the processor.

[0006] In some embodiments of the present application, the conditions for determining channel access failure based on the LBT type 1 procedure before the target S-SSB timing include at least one of the following: the deferral duration of the LBT type 1 procedure cannot be completed before the target S-SSB timing associated with the LBT type 1 procedure; or the random backoff procedure of the LBT type 1 procedure cannot be completed before the target S-SSB timing.

[0007] In some embodiments of the present application, the configuration information further includes at least one of the following: a first mapping between a channel access priority category (CAPC) value and a priority of a synchronization reference; a second mapping between a CAPC value and a channel occupancy time (COT); or a third mapping between a length of a cyclic prefix extension (CPE) and a priority of a synchronization reference.

[0008] In some embodiments of the present application, a higher priority of a synchronization reference is mapped to a smaller CAPC value; a COT with a shorter length is mapped to a smaller CAPC value; or a higher priority of a synchronization reference is mapped to a longer CPE.

[0009] In some embodiments of the present application, the processor is configured to perform at least one of the following: determine a CAPC value based on the priority of the synchronization reference of the UE and the first mapping or based on the COT occupied by the first S-SSB channel and the second mapping; execute the first LBT type 1 procedure based on the CAPC value; or in response to the channel being available for access based on the first LBT type 1 procedure before the first S-SSB opportunity, transmit the CPE to occupy the channel until the first S-SSB opportunity begins.

[0010] In some embodiments of the present application, the processor is further configured to execute a second LBT type 2 procedure associated with the second S-SSB opportunity after the transmitter transmits the S-SSB at the first S-SSB opportunity.

[0011] In some embodiments of the present application, the processor is configured to perform at least one of the following: determine the time interval between the first S-SSB opportunity and the second S-SSB opportunity and a sensing interval within the time interval, wherein the length of the sensing interval is based on at least one of the following: the LBT type of the second LBT type 2 procedure or the length of the time interval; execute the second LBT type 2 procedure associated with the second S-SSB opportunity in the sensing interval; or before the start of the second S-SSB opportunity, in response to the success of the second LBT type 2 procedure, transmit the CPE to occupy the channel until the second S-SSB opportunity starts.

[0012] In some embodiments of the present application, the processor is configured to perform at least one of the following: determining a CAPC value based on the priority of the synchronization reference of the UE and the first mapping; executing the second LBT type 1 procedure based on the CAPC value; or in response to the channel being available for access based on the second LBT type 1 procedure before the second S-SSB opportunity, transmitting the CPE to occupy the channel until the second S-SSB opportunity begins.

[0013] In some embodiments of the present application, the processor is configured to perform at least one of the following: determining a CAPC value based on the COT occupied by the second channel and the second mapping; executing the second LBT type 1 procedure based on the CAPC value; or in response to the channel being available for access based on the second LBT type 1 procedure before the second S-SSB opportunity, transmitting the CPE to occupy the channel until the second S-SSB opportunity begins.

[0014] In some embodiments of the present application, the processor is further configured to transmit dummy data to occupy the channel until the second S-SSB opportunity starts after determining that the channel is available for access based on the first LBT type 1 procedure at a moment after the first S-SSB opportunity starts.

[0015] In some embodiments of the present application, the processor is further configured to: after determining that the channel is available for access based on the first LBT type 1 procedure at a moment after the start of the first S-SSB opportunity, execute a third LBT type 1 procedure associated with the second S-SSB opportunity based on a minimum CAPC value.

[0016] In some embodiments of the present application, the first LBT type 2 procedure is executed within a time interval between the first S-SSB opportunity and the second S-SSB opportunity, and the processor is configured to perform at least one of the following: determining the length of a sensing interval within the time interval based on the LBT type of the first LBT type 2 procedure; executing the first LBT type 2 procedure within the sensing interval; or in response to a channel being available for access based on the first LBT type 2 procedure, transmitting the CPE to occupy the channel until the second S-SSB opportunity begins.

[0017] In some embodiments of the present application, in response to determining that channel access fails based on the first LBT type 1 procedure before the first S-SSB opportunity, the first LBT type 2 procedure is executed before the first S-SSB opportunity, and the processor is configured to perform at least one of the following: determining the length of the sensing interval within the time interval based on the LBT type of the first LBT type 2 procedure; executing the first LBT type 2 procedure within the sensing interval; or in response to the channel being available for access based on the first LBT type 2 procedure, transmitting the CPE to occupy the channel until the first S-SSB opportunity begins.

[0018] In some embodiments of the present application, the receiver is configured to receive the configuration information via at least one of: a master information block (MIB) message, a system information block (SIB) message, a radio resource control (RRC) signaling, or a medium access control (MAC) control element (CE).

[0019] According to some other embodiments of the present application, a BS may include: a transmitter configured to: transmit configuration information for S-SSB in an unlicensed spectrum, wherein the configuration information includes at least one of: a condition for determining a channel access failure based on an LBT type 1 procedure before a target S-SSB opportunity; a first mapping between a CAPC value and a priority of a synchronization reference; a second mapping between a CAPC value and a COT; or a third mapping between a length of a CPE and a priority of a synchronization reference; a processor coupled to the transmitter; and a receiver coupled to the processor.

[0020] In some embodiments of the present application, the conditions for determining channel access failure based on the LBT type 1 procedure before the target S-SSB timing include at least one of the following: the deferral duration of the LBT type 1 procedure cannot be completed before the target S-SSB timing associated with the LBT type 1 procedure; or the random backoff procedure of the LBT type 1 procedure cannot be completed before the target S-SSB timing.

[0021] In some embodiments of the present application, the configuration information is transmitted via at least one of the following: a MIB message, a SIB message, an RRC signaling, or a MAC CE.

[0022] According to some other embodiments of the present application, a method performed by a UE may include: obtaining configuration information for S-SSB in an unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes a condition for determining a channel access failure based on an LBT type 1 procedure before a target S-SSB opportunity; executing a first LBT type 1 procedure associated with a first S-SSB opportunity to start a first S-SSB channel occupancy starting from the first S-SSB opportunity; in response to determining that the channel access failed based on the first LBT type 1 procedure and the configuration information before the first S-SSB opportunity, performing the following operations At least one of: executing a second LBT type 1 procedure associated with a second S-SSB opportunity immediately following the first S-SSB opportunity to start a second S-SSB channel occupancy starting from the second S-SSB opportunity; continuing to execute the first LBT type 1 procedure before the second S-SSB opportunity to start a second S-SSB channel occupancy starting from the second S-SSB opportunity; or executing a first LBT type 2 procedure; and in response to the channel being available for access based on the first LBT type 1 procedure before the first S-SSB opportunity, transmitting an S-SSB at the first S-SSB opportunity.

[0023] According to some other embodiments of the present application, a method performed by a BS may include: transmitting configuration information for S-SSB in an unlicensed spectrum, wherein the configuration information includes at least one of: a condition for determining a channel access failure based on an LBT type 1 procedure before a target S-SSB opportunity; a first mapping between a CAPC value and a priority of a synchronization reference; a second mapping between a CAPC value and a COT; or a third mapping between a length of a CPE and a priority of a synchronization reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order 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 reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and are therefore not to be considered limiting of its scope.

[0025] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

[0026] Figure 2 Describing exemplary S-SSB time slots according to some embodiments of the present application;

[0027] Figure 3 An exemplary distribution of S-SSB opportunities according to some embodiments of the present application is described;

[0028] Figure 4An exemplary distribution of S-SSB opportunities within an S-SSB period including a plurality of S-SSB windows according to some embodiments of the present application is described;

[0029] Figure 5 A flow chart illustrating an exemplary procedure for performing COT-based S-SSB transmission in unlicensed spectrum according to some embodiments of the present application;

[0030] Figure 6 Describe an exemplary channel access procedure according to some embodiments of the present application;

[0031] Figure 7 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0032] Figure 8 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0033] Fig. 9 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0034] Fig.10 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0035] Fig.11 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0036] Fig.12 Describe an exemplary channel access procedure according to some other embodiments of the present application;

[0037] Fig.13 Describe exemplary channel access procedures according to some other embodiments of the present application; and

[0038] Fig.14 A simplified block diagram illustrating an exemplary apparatus for S-SSB transmission in unlicensed spectrum in accordance with some embodiments of the present application. DETAILED DESCRIPTION

[0039] 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 intended to be included in the spirit and scope of the present application.

[0040] Although the operations are depicted in a particular order in the accompanying drawings, those skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in sequential order, or that all of the illustrated operations need not be performed to achieve the desired result; one or more operations may sometimes be skipped. In addition, the accompanying drawings may schematically depict one or more example processes in the form of flow charts. 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 some cases, multitasking and parallel processing may be advantageous.

[0041] 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 Advanced LTE, 3GPP 5G New Radio (NR), Advanced 5G, 6G, etc.). It is considered that with the development of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and in addition, the terms described in the present application may be changed, which should not affect the principles of the present application.

[0042] Figure 1 An exemplary wireless communication system 100 is illustrated in accordance with some embodiments of the present application.

[0043] like Figure 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 .

[0044] 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 (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a surveillance camera), a vehicle-mounted computer, a network device (e.g., a router, a switch, and a modem), or the like.

[0045] 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 identification module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals on a wireless network.

[0046] 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.

[0047] According to some embodiments of the present disclosure, UE 101 may include a vehicle UE (VUE) and / or an energy-saving UE (also referred to as a power-sensitive UE). An energy-saving UE may include a vulnerable road user (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, a VRU may include a pedestrian UE (P-UE), a cyclist UE, a wheelchair UE, or other UE that requires energy saving compared to a VUE.

[0048] In addition, UE 101 may be referred to as a subscriber unit, mobile device, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, user station, user terminal, or device, or described using other terms used in the art.

[0049] In a sidelink communication system, a transmitting UE may also be named as a transmitting UE, a Tx UE, a sidelink Tx UE, a sidelink transmitting UE or the like, and a receiving UE may also be named as a receiving UE, a Rx UE, a sidelink Rx UE, a sidelink receiving UE or the like.

[0050] according to Figure 1 In some embodiments, UE 101a is used as a Tx UE and UE 101b is used as an Rx UE. UE 101a may exchange sidelink messages with UE 101b via a sidelink, for example, via a PC5 interface as defined in 3GPP TS23.303. UE 101a may transmit information or data to other UEs within the sidelink communication system via sidelink unicast, sidelink multicast, or sidelink broadcast. For example, UE 101a may transmit data to UE 101b in a sidelink unicast session. UE 101a may transmit data to UE 101b and multicast packets ( Figure 1 In addition, UE 101a can transmit data to UE 101b and other UEs (not shown) via a sidelink broadcast transmission session. Figure 1 (not shown) transmission data.

[0051] 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.

[0052] 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.

[0053] 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 throughout 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 station, base station unit, macro cell, Node B, evolved Node B (eNB), gNB, master Node-B, relay node or device, or described using other terms used in the art. BS 102 is typically part of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding BS 102.

[0054] 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 a wireless communication network, a cellular telephone network, a network based on time division multiple access (TDMA), a network based on code division multiple access (CDMA), a network based on orthogonal frequency division multiple access (OFDMA), an LTE network, a network based on 3GPP, a 3GPP 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0055] 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 using an orthogonal frequency division multiplexing (OFDM) modulation scheme on the downlink (DL), and the UE 101 transmits data using a discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix-OFDM (CP-OFDM) scheme on the uplink (UL). However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0056] In some embodiments of the present disclosure, BS102 may communicate using other communication protocols, such as IEEE 802.11 series of wireless communication protocols. In addition, in some embodiments of the present disclosure, BS102 may communicate via licensed spectrum, while in other embodiments, BS102 may communicate via unlicensed spectrum. The present disclosure is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In some further embodiments of the present disclosure, BS102 may communicate with UE 101 using 3GPP 5G protocols.

[0057] In NR, accommodating multiple uncoordinated UEs in unlicensed spectrum requires a channel access procedure defined for NR. After a successful channel access procedure performed by a communication node, the channel may be used by the communication node during a period until the end of the period. Such a 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.

[0058] A BS or UE typically uses a dynamic channel access procedure 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 in some cases a random backoff time is applied. Two main types of dynamic channel access procedures may be defined in NR. One is a type 1 dynamic channel access procedure, also known as LBT type 1 or LBT cat4. The other is a type 2 dynamic channel access procedure, also known as LBT type 2.

[0059] The type 1 dynamic channel access procedure can be used to start data transmission at the beginning of COT. The initiator of the type 1 dynamic channel access procedure can be either the BS or the UE. The type 1 dynamic channel access procedure can be summarized as follows.

[0060] First, the initiator listens and waits during at least one period of time called the hold-off duration until a channel (e.g., a frequency channel) is available. The hold-off duration may be from 16 μs and many more (e.g., “m p ", which will be described below) is composed of 9μs time slots. As shown in Tables 1 and 2, "m p The value of " depends on the value of CAPC (denoted as "p"). Therefore, the deferral duration depends on the value of CAPC, as shown in Table 1 or Table 2 below. If the received energy is below the threshold during at least 4μs of each 9μs time slot, the channel is declared available.

[0061] Once the channel is declared available during the hold-off duration, the transmitter initiates a random backoff procedure during which it will wait for a random period of time.

[0062] The UE initiates the random backoff procedure by initializing the backoff timer with a random number within the contention window (CW). The random number is obtained from a uniform distribution [0, CW] and indicates that the channel must be available for the duration of the timer (e.g., defined by the random number multiplied by 9 μs) before transmission can be made. The value of "CW" can be selected from the "Allowed CW" in Table 1 or Table 2 below. p Size” (the minimum value is indicated as CW min，p , and the maximum value is expressed as CW max，p), depending on the value of CAPC.

[0063] For each sensing slot duration (eg, 9 μs) that the channel is sensed as idle, the backoff timer is decremented by 1; each time the channel is sensed as busy, the backoff timer is suspended until the channel has been idle for the defer duration.

[0064] Once the backoff timer expires (eg, the backoff timer decreases to 0), the random backoff procedure is complete and the transmitter has acquired the channel and can use it until the MCOT (eg, T mcot，p Or T in Table 2 below ulmcot，p , which depends on the value of CAPC) of the emission.

[0065] Tables 1 and 2 below respectively illustrate exemplary DL CAPC and UL CAPC, and m p , CW min，p , CW max，p 、T mcot，p 、T ulmcot，p And allowed CW p 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 intends to start 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 and allowed CW p When the UE intends to start 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) used in the Type 1 channel access procedure according to Table 2. p , CW min，p , CW max，p 、T ulmcot，p and allowed CW p size).

[0066] Table 1: DL channel access priority categories

[0067]

[0068] Table 2: UL channel access priority categories

[0069]

[0070] The size of the contention window may be adjusted based on hybrid automatic repeat request (HARQ) reports received from the transmitter during a reference interval that covers the start of the COT. For each received HARQ report, if a negative HARQ report (e.g., non-acknowledgement (NACK)) is received, the contention window is (approximately) doubled until the limit CW max，p For a positive HARQ report (eg, an ACK), the contention window is reset to its minimum value, ie, CW = CW min，p .

[0071] The type 2 dynamic channel access procedure can be used to discover bursty COT sharing and transmission. Depending on the duration of the gap in the COT (also called "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.

[0072] Type 2A dynamic channel access procedure (also called LBT cat2 or LBT type 2A): It is used when the gap is 25 μs or larger to detect bursty transmissions.

[0073] Type 2B dynamic channel access procedure (also called LBT Type 2B): It is used when the gap is 16 μs.

[0074] Type 2C dynamic channel access procedure (also called LBT Type 2C): It is used when the gap after the previous transmission burst is 16 μs or less.

[0075] For Type 2C dynamic channel access procedure, idle sensing between transmit bursts is not required. In this scenario, the duration of a transmit burst is limited to a maximum of 584 μs. This short transmit burst can carry a small amount of user data, uplink control information (UCI), such as HARQ status reports and channel state information (CSI) reports.

[0076] 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 to be idle in the gap, it is declared available; if the channel is detected to be busy, COT sharing fails and COT sharing cannot be used to transmit in this COT. If the COT sharing gap is 16 μs, the type 2B dynamic channel access procedure may be used, and the channel must be detected to be idle in the 16 μs gap before the next transmission burst. If the COT sharing gap is 25 μs or longer, the type 2A dynamic channel access procedure may be used, and the channel must be detected to be idle during at least 25 μs immediately before the next transmission burst.

[0077] The above embodiments provide several dynamic channel access procedures for NR in unlicensed spectrum. These dynamic channel access procedures can also be applied to sidelink transmissions in unlicensed spectrum.

[0078] The sidelink synchronization information is carried in the S-SSB, which consists of the Physical Sidelink Broadcast Channel (PSBCH), the Sidelink Primary Synchronization Signal (S-PSS) and the Sidelink Secondary Synchronization Signal (S-SSS). 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.

[0079] refer to Figure 2 , S-SSB occupies one time slot in the time domain and 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, such as 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, starting from the third subcarrier to the 129th subcarrier relative to the S-SSB bandwidth.

[0080] 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 called SyncRef UE), a UE can synchronize with the SyncRef UE and estimate the start of a frame and a carrier frequency offset.

[0081] The S-PSS can be generated from an m-sequence using the same design (i.e., generator polynomial, initial value, cyclic shift, etc.) used to generate the maximum length sequence (m-sequence) in the primary synchronization signal (PSS) in the 3GPP profile. In NR Uu, there are three candidate sequences for the PSS. However, the S-PSS uses only two candidate sequences.

[0082] The S-SSS can be generated from a Gold sequence using the same design (i.e., generator polynomial, initial value, cyclic shift, etc.) of the Gold sequence used to generate the Secondary Synchronization Signal (SSS) in the 3GPP profile. This results in 336 candidate sequences for the S-SSS, just like the SSS in NR Uu.

[0083] For the transmission of SLSS within S-SSB, SyncRef UE can select S-PSS and S-SSS from candidate sequences based on SLSS identifier (ID). SLSSID represents the identifier of SyncRef UE and conveys the priority of SyncRef UE as in LTE V2X. Each SLSSID corresponds to a unique combination of one S-PSS and one S-SSS among 2 S-PSS candidate sequences and 336 S-SSS candidate sequences.

[0084] The main purpose of PSBCH is to provide the UE with system-wide information and synchronization information required to establish a sidelink connection. Figure 2 In 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. When the extended CP is used, 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 in the S-SSB slot (e.g., symbol #13) is used as a guard symbol.

[0085] The UE may be configured with a configuration for an S-SSB period including one or more S-SSB opportunities.

[0086] Figure 3 An exemplary distribution of S-SSB opportunities according to some embodiments of the present disclosure is described.

[0087] like Figure 3As shown in FIG. 1 , an S-SSB period includes N S-SSB opportunities, namely S-SSB#0, S-SSB#1, ..., S-SSB#N-3, S-SSB#N-2, and S-SSB#N-1. The length of the S-SSB period is marked as "period". There is an offset from the starting time slot of the S-SSB period to the first S-SSB opportunity (e.g., S-SSB#0) in the S-SSB period. Figure 3 There is a gap between two adjacent S-SSB opportunities (e.g., between the start time slots of two adjacent S-SSB opportunities). Figure 3 , the interval between S-SSB #N-3 and S-SSB #N-2 is marked as "interval". Therefore, the configuration for one S-SSB period may include at least one of the parameter "period", the parameter "offset" or the parameter "interval". The UE may select one or more SSB opportunities for transmitting SSBs based on the configuration.

[0088] The S-SSB period may contain 16 frames, e.g. 160 ms, as specified in NR V2X. The possible number of S-SSB opportunities within one S-SSB period is shown in Table 3 below:

[0089] Table 3 Number of S-SSB opportunities within the S-SSB period (160ms)

[0090]

[0091] Figure 4 An exemplary distribution of S-SSB opportunities within an S-SSB period including a plurality of S-SSB windows according to some embodiments of the present application is described.

[0092] refer to Figure 4 , in the S-SSB period, N1 S-SSB windows are included, namely S-SSB window #0, S-SSB window #1, ..., S-SSB window #N1-1. In each S-SSB window, N2 S-SSB opportunities are included, namely S-SSB opportunity #0, S-SSB opportunity #1, ..., S-SSB opportunity #N2-1. In each S-SSB window, the time interval (for example, represented by TI-S-SSB) is positioned between two adjacent S-SSB opportunities. The length of the S-SSB period is marked as "period". The duration from the starting time slot of the S-SSB period to the starting time slot of S-SSB window #0 is marked as "offset". The interval between two adjacent S-SSB windows (for example, from the starting time slot of S-SSB window #0 to the starting time slot of S-SSB window #1) is marked as "interval".

[0093] Figure 2The structure of the S-SSB slot in Figure 3 and 4 The distribution of the timing of S-SSB in the 4000-0000 period is for illustration 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 in the time domain), and the distribution of the timing of S-SSB within an S-SSB period or within a window may change, which should not affect the principles of the present application.

[0094] For S-SSB transmission in unlicensed spectrum, in the time domain, an important requirement is that the UE needs to perform a channel access procedure (e.g., LBT procedure) before S-SSB transmission.

[0095] Compared with the licensed spectrum, the unlicensed spectrum may require more S-SSB opportunities for the following two reasons. One reason is to achieve the desired channel access opportunities for the UE. Another reason is to enable S-SSB for new scenarios, such as supporting latency-critical services, supporting beam-based transmission, etc.

[0096] Additionally, if accessing each S-SSB opportunity requires a separate LBT procedure that takes a long time, then the energy consumption will scale greatly with the number of S-SSB transmissions.

[0097] In view of the above, the sidelink requires COT-based S-SSB transmission in unlicensed spectrum. In order to guarantee the desired channel access opportunity, it is necessary to specify the behavior of the UE to perform COT-based S-SSB transmission. For example, the behavior of the UE includes, but is not limited to, the operation performed by the UE when it is determined that the channel access procedure for initiating COT-based S-SSB transmission fails, and the operation performed by the UE when the channel access procedure for initiating COT-based S-SSB transmission succeeds.

[0098] Embodiments of the present application provide an improved solution for S-SSB transmission in unlicensed spectrum, which proposes configuration, signaling and procedures for performing COT-based S-SSB transmission in unlicensed bands. More details will be described below in conjunction with the accompanying drawings.

[0099] According to some embodiments of the present application, the UE may obtain configuration information for S-SSB in unlicensed spectrum based on configuration or pre-configuration. The UE may use the configuration information to perform COT-based S-SSB transmission.

[0100] In some embodiments of the present application, the UE may obtain configuration information based on the configuration. Specifically, obtaining configuration information based on the configuration (i.e., configuring the configuration information to the UE) may refer to: Figure 1BS102 shown in FIG. 1 transmits configuration information to UE via at least one of the following: SIB message, MIB message, RRC signaling or MAC CE or downlink control information (DCI), so that UE can receive configuration information from BS. In an embodiment of the present application, obtaining configuration information based on configuration can be applicable to scenarios where UE is within the coverage of the network.

[0101] In some other embodiments of the present application, the UE may obtain configuration information based on pre-configuration. Specifically, obtaining configuration information based on pre-configuration (i.e., pre-configuring the configuration information to the UE) may mean that the configuration information may be hardwired into the UE, or stored on a user identity module (SIM) or universal user identity module (USIM) card of the UE, so that the UE may obtain the configuration information within the UE. In an embodiment of the present application, obtaining configuration information based on pre-configuration may be applicable to a scenario where the UE is out of coverage of the network.

[0102] The configuration information for S-SSB in unlicensed spectrum may include at least one of the following:

[0103] · a condition for determining a channel access failure based on an LBT Type 1 procedure before a target S-SSB opportunity (“before a target S-SSB opportunity” may mean “no later than the start of a target S-SSB opportunity”);

[0104] A first mapping between CAPC values ​​and priorities of synchronization references;

[0105] A second mapping between CAPC values ​​and COT; or

[0106] The length of the CPE (e.g., represented by T CPE Represents a third mapping between the priority of the synchronization reference).

[0107] In some embodiments of the present application, the conditions for determining channel access failure based on the LBT Type 1 procedure before the target S-SSB opportunity may include at least one of the following:

[0108] Condition 1: The deferral duration of the LBT Type 1 procedure cannot be completed before the target S-SSB opportunity associated with the LBT Type 1 procedure; or

[0109] Condition 2: The random backoff procedure of the LBT Type 1 procedure cannot be completed before the target S-SSB timing.

[0110] Such conditions may enable the UE to determine channel access failure in advance, for example, before the start of the target S-SSB opportunity (also known as the starting boundary).

[0111] For example, when the UE intends to start S-SSB channel occupation starting from the target S-SSB opportunity (e.g., with COT), the UE may perform the LBT Type 1 procedure before the target S-SSB opportunity. Without using the above conditions, the UE may determine the channel access failure associated with the S-SSB channel occupation starting from the target S-SSB opportunity only when it determines based on the LBT Type 1 procedure that the channel is still not available for access at the start of the target S-SSB opportunity. That is, the UE cannot determine the channel access failure until the target S-SSB opportunity starts.

[0112] In contrast, by using condition 1 or condition 2, the UE can determine that the channel access fails before the target S-SSB opportunity starts. For example, at time t1 when the LBT type 1 procedure is started, the UE can determine the deferral duration of the LBT type 1 procedure (given by T d t1) (e.g., based on the CAPC value) and the time offset (calculated by the function ΔT(*)) from time t1 to the start of the target S-SSB opportunity (denoted by t2), i.e., ΔT(t1, t2) = t2-t1. If ΔT(t1, t2) is less than T d , that is, ΔT(t1,t2) <T d , which means that the postponement duration of the LBT Type 1 procedure cannot be completed before the target S-SSB opportunity, then condition 1 is satisfied and thus the UE can determine that the channel access fails at time t1. A time can also be referred to as a time point.

[0113] In another example, at time t3 in the random backoff procedure of the LBT Type 1 procedure, the UE may determine the minimum time required to complete the remaining random backoff procedure (denoted by T min t3, t2) = t2-t3. If ΔT(t3, t2) is less than T min , which means that the random backoff procedure of the LBT type 1 procedure cannot be completed before the target S-SSB opportunity, then condition 2 is satisfied and therefore the UE can determine that the channel access fails at time t3. For example, T min It can be determined as follows: Assume that at t3, the backoff counter is denoted by N and the sensing time slot duration (eg, 9 μs) is denoted by T sl Indicates that, then T min T min =N*T sl calculate.

[0114] A UE can derive its own synchronization from four basic synchronization references, namely the Global Navigation Satellite System (GNSS), its serving BS (e.g., eNB or gNB), another UE transmitting a SLSS (e.g., called a SyncRef UE), or its own internal clock. In general, the GNSS or BS is considered to be the highest quality source. A SyncRef UE distinguishes between UEs that are directly synchronized to the GNSS or BS, UEs that are 1 step further from the GNSS or BS, and UEs that are ≥ 2 steps further from the GNSS or BS. As a last resort, a UE that cannot find any other synchronization reference will use its own internal clock to transmit the SLSS. The priority order of the synchronization references is as follows, with details specified in TS 36.331, where "Level 1" to "Level 5" are the priorities of the synchronization references from highest to lowest.

[0115] Level 1: The synchronization reference is either GNSS or BS, depending on the configuration or pre-configuration.

[0116] Level 2: The synchronization reference is the SyncRef UE that is directly synchronized with the Level 1 source.

[0117] Level 3: The synchronization reference is a SyncRef UE that is synchronized with a Level 2 source, i.e., indirectly synchronized with a Level 1 source.

[0118] • Level 4: The synchronization reference is any other SyncRef UE.

[0119] Level 5: UE's internal clock.

[0120] In some embodiments of the present application, one principle of the mapping between the CAPC value and the priority of the synchronization reference is to provide an earlier channel access opportunity for a synchronization reference with a higher priority. In order to realize the above principle, the first mapping between the CAPC value and the priority of the synchronization reference can map the higher priority of the synchronization reference to a smaller CAPC value. Based on Table 1 or Table 2 above, the smaller CAPC value can correspond to a shorter sensing interval of the LBT Type 1 procedure (the sensing interval can include a postponement duration and a random backoff procedure), thereby providing an earlier channel access opportunity.

[0121] Table 4 below shows an exemplary mapping between CAPC values ​​(eg, p) and priorities of synchronization references

[0122] Table 4

[0123] CAPC(p) Priority of synchronization references 1 Level 1 2 Level 2 2 Level 3 3 Level 4 4 Level 5

[0124] For example, in the case where the priority of the synchronization reference is level 2, according to Table 4, the corresponding CAPC value is 2. Based on the CAPC value, the UE may determine the length of the sensing interval for the LBT Type 1 procedure based on Table 1 or Table 2 above.

[0125] In some embodiments of the present application, one principle of the mapping between the CAPC value and the COT is to provide an earlier channel access opportunity for a COT with a shorter length, such as a smaller number of S-SSBs (or S-SSB opportunities) in the COT. In order to achieve the above principle, the second mapping between the CAPC value and the COT can map a COT with a shorter length (e.g., a COT with a smaller number of S-SSBs) to a smaller CAPC value. Based on Table 1 or Table 2 above, a smaller CAPC value can correspond to a shorter sensing interval for an LBT Type 1 procedure, thereby providing an earlier channel access opportunity.

[0126] Table 5 below shows an exemplary mapping between CAPC values ​​(eg, p) and the COT of S-SSBs, which is defined as the number of S-SSBs within the COT (ie, j).

[0127] Table 5

[0128] CAPC(p) COT(j) of S-SSB 1 <![CDATA[j=[1..floor(N S-SSB MCOT / 4)]]]> 2 <![CDATA[j=(floor(N S-SSB MCOT / 4)..2*floor(N S-SSB MCOT / 4)]]]> 3 <![CDATA[j=(2*floor(N S-SSB MCOT / 4)..3*floor(N S-SSB MCOT / 4)]]]> 4 <![CDATA[j=(3*floor(N S-SSB MCOT / 4)..N S-SSB MCOT ]]]>

[0129] Referring to Table 5, j is the number of S-SSBs (or S-SSB opportunities) in the COT, and N S-SSB MCOT is the number of S-SSBs (or S-SSB opportunities) included in the MCOT. For example, assuming that there are 8 S-SSBs in the MCOT and one COT has 3 S-SSBs, which is within the value range of the second row of Table 5 (e.g., j = (2..4] or j∈{3,4}), then the corresponding CAPC value is p=2. Based on the CAPC value, the UE can determine the length of the sensing interval for the LBT Type 1 procedure based on Table 1 or Table 2 above.

[0130] In some embodiments of the present application, when a channel is determined to be available based on the LBT procedure before the target S-SSB starts, a CPE may be transmitted to occupy the channel until the target S-SSB starts, and one principle of the mapping between the length of the CPE and the priority of the synchronization reference is to provide an earlier channel access opportunity for a synchronization reference with a higher priority. In order to achieve the above principle, the third mapping between the length of the CPE and the priority of the synchronization reference may map a higher priority of the synchronization reference to a longer CPE.

[0131] In some embodiments of the present application, the length of the CPE can be determined by the following equation (1):

[0132] T CPE= N UT * T UT (1)

[0133] In equation (1), T UT It is a time unit configured or preconfigured to the UE, such as T UT =9μs. UT is the number of time units. In such embodiments, the third mapping may be a mapping between the number of time units used to calculate the length of the CPE and the priority of the synchronization reference. In an embodiment, a higher priority of the synchronization reference is mapped to the number of time units associated with a longer CPE, thereby achieving that the higher the priority of the synchronization reference, the higher the priority of the CPE. CPE The longer the principle.

[0134] Table 6 below shows the CPE (by the number of time units (e.g., N UT ) represents an exemplary mapping between) and the priority of the synchronization reference.

[0135] Table 6

[0136] <![CDATA[CPE(N UT )]]> Priority of synchronization references 4 Level 1 3 Level 2 2 Level 3 1 Level 4 0 Level 5

[0137] For example, when the priority of the synchronization reference is level 2, according to Table 6, the number of time units "N UT ” is 3. Based on equation (1), the UE can determine T CPE =27μs.

[0138] Based on the obtained configuration information, the UE may perform COT-based SSB transmission in the unlicensed spectrum.

[0139] Figure 5 A flow chart illustrating an exemplary procedure for performing COT-based S-SSB transmissions in unlicensed spectrum in accordance with some embodiments of the present application. Figure 5 The procedure in may include at least the following steps.

[0140] At the start of the procedure, the UE may intend to start the first S-SSB channel occupancy starting from an S-SSB opportunity (e.g., S-SSB opportunity #m) or an SSB (e.g., S-SSB #m). The first S-SSB channel occupancy may have a first COT starting from S-SSB opportunity #m or S-SSB #m.

[0141] In some embodiments of the present application, the first COT may be defined as N S-SSB COT (S-SSB#m), which indicates the number of S-SSBs that the UE intends to transmit within the first COT starting from S-SSB#m. Parameter N S-SSB COT(S-SSB#m) may be determined by the UE's intent and is affected by the temporal distribution of the S-SSB opportunities and N S-SSB MCOT Constraints, for example, N S-SSB COT (S-SSB#m)≤N S-SSB MCOT , where N S-SSB MCOT Indicates the maximum number of S-SSBs that can be transmitted within one COT.

[0142] In step 501, the UE may start the initial value N S-SSB COT (S-SSB#m) COT counter (e.g., N C represents) (i.e., N C =N S-SSB COT (S-SSB#m)). The UE may also set the COT flag (e.g., by F C indicates) is set to TRUE (i.e., F C =TRUE). Then, the UE proceeds to step 502.

[0143] In step 502, the UE may execute a procedure I (e.g., a first LBT type 1 procedure) associated with (e.g., toward) S-SSB opportunity #m to start the first S-SSB channel occupation starting from S-SSB opportunity #m. The specific operation of procedure I will be described in detail below. Then, the UE proceeds to step 503.

[0144] In step 503, the UE may determine whether the channel is available for access based on procedure 1 before S-SSB opportunity #m. In response to the channel being available for access (ie, the "Y (Yes)" branch of step 503), the UE proceeds to step 504. Otherwise, in response to the channel access failure (ie, the "N (No)" branch of step 503), for example, according to condition 1 or condition 2, the UE proceeds to step 508.

[0145] In step 504, the UE may transmit the S-SSB at the first available S-SSB opportunity based on the corresponding channel access procedure. In addition, in step 504, the UE may also transmit N C Decrement by 1, that is, set N C =N C -1. Then, the UE proceeds to step 505.

[0146] In step 505, the UE may determine N C Is the current value of greater than 0? CIf the current value of N is greater than 0 (i.e., the "Y" branch of step 505), this means that at least one S-SSB is to be transmitted, and the UE proceeds to step 506. Otherwise, in N C In the case where the current value of is not greater than 0 (ie, the "N" branch of step 505), this means that all expected S-SSBs have been transmitted and the UE stops the procedure.

[0147] In step 506, after the UE transmits the S-SSB at the previous S-SSB opportunity, the UE may perform a procedure II (e.g., LBT type 2 procedure) associated with (e.g., toward) the next S-SSB opportunity within the first COT. For example, after transmitting the S-SSB at S-SSB opportunity #m, the UE may perform an LBT type 2 procedure associated with S-SSB opportunity #m+1. The specific operation of procedure II will be described in detail below. Then, the UE proceeds to step 507.

[0148] In step 507, the UE may determine whether the channel is available for access. In response to the channel being available for access (i.e., the "Y" branch of step 507), the UE proceeds to step 504. Otherwise, in response to the channel access failure (i.e., the "N" branch of step 507), the UE stops the procedure.

[0149] In step 508, the UE may perform a procedure III (e.g., an LBT type 1 procedure or an LBT type 2 procedure) associated with the S-SSB opportunity #m or the S-SSB opportunity immediately following the S-SSB opportunity #m (e.g., S-SSB opportunity #m+1). Specific operations of the procedure III will be described in detail below. In the procedure III, if the LBT type 2 procedure is performed, the UE may set N C =1. Then, the UE proceeds to step 507.

[0150] Program I

[0151] According to some embodiments of the present disclosure, in procedure I, the UE may execute a first LBT type 1 procedure associated with S-SSB opportunity #m to start the first S-SSB channel occupancy starting from S-SSB opportunity #m.

[0152] Procedure I may include at least one of the following steps.

[0153] Step 1-1: The UE may determine the CAPC value. In some embodiments of the present application, the UE may determine the CAPC value based on the priority of the UE's synchronization reference and the first mapping as described above. For example, based on Table 4 and the priority of the UE's synchronization reference, the UE may determine the corresponding CAPC value.

[0154] Alternatively, the UE may determine the first COT (eg, N ) occupied by the first S-SSB channel based on the first COT (eg, N ) as described above. S-SSB COT (S-SSB#m)) and the second mapping to determine the CAPC value. For example, based on Table 5 and N S-SSB COT (S-SSB#m), the UE can determine the corresponding CAPC value.

[0155] Step 1-2: The UE may perform a first LBT Type 1 procedure based on a CAPC value (e.g., the CAPC value determined in step 1-1). For example, based on the CAPC value, the UE may determine parameters required for the first LBT Type 1 procedure (e.g., “m” for determining the length of the deferral duration) based on Table 1 or Table 2. p ", "allowed CWp size" used to determine the backoff counter, etc.).

[0156] Step 1-3: In response to the channel being available for access based on the first LBT Type 1 procedure before S-SSB opportunity #m (e.g., the first LBT Type 1 procedure is successful before the start of S-SSB opportunity #m), the UE may transmit CPE to occupy the channel until the start of S-SSB opportunity #m.

[0157] In some embodiments of the present application, the UE may determine the length of the CPE based on the priority of the UE's synchronization reference and the third mapping as described above. The length of the CPE (eg, T CPE ) may indicate that the LBT procedure may have an offset (eg, T ) relative to the beginning (ie, the starting boundary) of S-SSB opportunity #m before the second time point. CPE ) starts from the first time point.

[0158] Figure 6 An exemplary channel access procedure (eg, procedure I) according to some embodiments of the present application is described.

[0159] like Figure 6 As shown in FIG. 1 , the UE may intend to start the first S-SSB channel occupation starting from S-SSB opportunity #m. The first S-SSB channel occupation may have a first COT (e.g., represented by COT #1) from time point n2 to time point n3, where n2 is the beginning (also called the starting boundary) of S-SSB opportunity #m. The first COT may include N S-SSB COT (S-SSB#m) S-SSB opportunities (or S-SSB). The length of the time interval between two adjacent S-SSB opportunities in the first COT can be represented by T TI-S-SSB Indicates that T TI-S-SSB ≥ 0. For simplicity, Figure 6Only two S-SSB occasions (e.g., S-SSB occasion #m and S-SSB occasion #m+1) are described as examples. For simplicity, S-SSB occasion #m and S-SSB occasion #m are represented as S-SSB#m and S-SSB#m+1 in Figure 6 as shown.

[0160] The UE can determine the CAPC value (e.g., represented by p#1) based on the method described above. Then, before S-SSB occasion #m, the UE can perform a first LBT type 1 procedure associated with S-SSB occasion #m based on the CAPC value to initiate the first S-SSB channel occupancy. The starting point of the first LBT type 1 procedure can be the time point n0.

[0161] In response to the channel being available for access at time point n1 (where n1 < n2) based on the first LBT type 1 procedure (e.g., the first LBT type 1 procedure is successful), the UE can transmit the CPE to occupy the channel until S-SSB occasion #m starts (e.g., n2), as Figure 6 shown.

[0162] Otherwise, in response to determining that channel access fails based on the first LBT type 1 procedure (e.g., by using condition 1 or condition 2) before S-SSB occasion #m (e.g., not later than the start of S-SSB occasion #m), the UE can execute procedure III, as Figure 5 described.

[0163] Program II

[0164] According to some embodiments of the present disclosure, procedure II includes a channel access procedure executed by the UE when the UE intends to transmit an S-SSB within the COT (except for the first S-SSB in the COT). Once the first S-SSB in the COT is successfully transmitted, the UE can perform the channel access procedure II for the remaining S-SSBs until the end of the COT.

[0165] In procedure II, the UE can perform an LBT type 2 procedure, which can be one of LBT type 2C, LBT type 2B, and LBT type 2A. In some embodiments, the LBT type of the LBT type 2 procedure (e.g., LBT type 2A, 2B, or 2C) can be indicated by configuration information configured or pre-configured to the UE.

[0166] Figure 7 Describe an exemplary channel access procedure (e.g., procedure II) according to some embodiments of the present application.

[0167] In Figure 7 the example of, with a first COT starting from S-SSB occasion #m (e.g., as Figure 6, the first S-SSB channel occupation (represented by COT#1 from n2 to n3) is initiated (e.g., by successful procedure I), and the S-SSB is successfully transmitted at S-SSB opportunity #m. Then, before transmitting the S-SSB at S-SSB opportunity #m+1, the UE performs a channel access procedure that may include at least one of the following steps.

[0168] Step 2-1: The UE may determine the time interval between S-SSB opportunity #m and S-SSB opportunity #m+1, and the sensing interval for the LBT type 2 procedure within the time interval.

[0169] The length of the time interval (e.g., represented by T TI-S-SSB Indicates) can be configured or pre-configured to the UE.

[0170] The length of the sensing interval (e.g., represented by T SI,TI Indicates) can be determined based on at least one of the following: the LBT type of the LBT type 2 program or the length of the time interval.

[0171] For example, the length of the sensing interval may be 0≤T when the LBT type is LBT type 2C. SI,TI ≤16μs, or when T TI-S-SSB =0, or T when the LBT type is LBT type 2B SI,TI = 16μs, or when the LBT type is LBT type 2A, it can be T SI,TI ≥25μs.

[0172] Step 2-2: The UE may perform an LBT type 2 procedure associated with S-SSB opportunity #m+1 within the sensing interval. For example, the UE may perform idle sensing within the sensing interval in response to the LBT type being LBT type 2B or LBT type 2A, or may perform idle sensing within the sensing interval in response to the LBT type being LBT type 2C or T TI-S-SSB =0 and LBT is not performed.

[0173] Step 2-3: The UE may transmit CPE to occupy the channel until the S-SSB opportunity #m+1 starts in response to the LBT type 2 procedure being successful before the S-SSB opportunity #m+1 starts. For example, the length of the CPE (e.g., T CPE,TI ) can be equal to T TI-S-SSB -T SI,TI .

[0174] although Figure 7 Take S-SSB timing #m+1 as an example, but Figure 7 The procedure in may be applied to any S-SSB opportunity within the first COT, except for the first S-SSB opportunity (e.g., Figure 7 Except for S-SSB timing #m).

[0175] Program III

[0176] According to some embodiments of the present disclosure, procedure III includes a channel access procedure performed by the UE after determining that channel access fails based on a first LBT type 1 procedure (e.g., by using condition 1 or condition 2) before a first S-SSB opportunity (e.g., S-SSB opportunity #m).

[0177] Procedure III may include at least one of the following methods:

[0178] 1) Method 1: performing a second LBT type 1 procedure associated with a second S-SSB opportunity (e.g., S-SSB opportunity #m+1) immediately following the first S-SSB opportunity to start occupation of a second S-SSB channel starting from the second S-SSB opportunity;

[0179] 2) Method 2: Continue to execute the first LBT Type 1 procedure before the second S-SSB opportunity to start the second S-SSB channel occupation starting from the second S-SSB opportunity; or

[0180] 3) Method 3: Execute LBT Type 2 procedure.

[0181] In the case of method 1 and method 2, the UE intends to perform COT-based S-SSB transmission starting from the second S-SSB opportunity. In the case of method 3, the UE intends to switch the COT-based S-SSB transmission (which is expected to be initiated by the first LBT type 1 procedure) to a single S-SSB transmission. This is why if the LBT type 2 procedure is performed in procedure III, the UE may set N C =1, as stated above with respect to step 508.

[0182] Two alternatives to method 1 referred to as Alternative 1 and Alternative 2 are described below.

[0183] Alternative Example 1

[0184] In alternative 1, the UE may perform at least one of the following steps:

[0185] Step 3-1-1-1: The UE may determine the CAPC value based on the priority of the UE's synchronization reference and the first mapping as described above.

[0186] Step 3-1-1-2: The UE may perform a second LBT type 1 procedure associated with a second S-SSB opportunity (eg, S-SSB opportunity #m+1) based on a CAPC value (eg, the CAPC value determined in step 3-1-1-1).

[0187] Step 3-1-1-3: The UE may, in response to the channel being available for access based on the second LBT Type 1 procedure before the second S-SSB opportunity, transmit the CPE to occupy the channel until the second S-SSB opportunity (e.g., S-SSB opportunity #m+1) begins.

[0188] Figure 8 An exemplary channel access procedure according to some embodiments of the present application is described (eg, Alternative Example 1).

[0189] like Figure 8 As shown in FIG. 1 , the UE may execute a first LBT type 1 procedure associated with S-SSB opportunity #m (eg, starting from time point n0) to initiate the first S-SSB channel occupancy starting from S-SSB opportunity #m.

[0190] The first S-SSB channel occupancy may have a first COT (e.g., represented by COT#1) from time point n1 to time point n5, where n1 is the beginning (also referred to as the starting boundary) of S-SSB opportunity #m. The first COT may include N S-SSB COT (S-SSB #m) S-SSB opportunities. The length of the time interval between two adjacent S-SSB opportunities in the first COT can be determined by T TI-S-SSB Indicates that T TI-S-SSB ≥ 0. For simplicity, Figure 8 Only two S-SSB opportunities (e.g., S-SSB opportunity #m and S-SSB opportunity #m+1) are described as an example. For simplicity, S-SSB opportunity #m and S-SSB opportunity #m+1 are Figure 8 It is represented as S-SSB#m and S-SSB#m+1.

[0191] A first LBT Type 1 procedure may be performed based on a CAPC value (e.g., represented by p#1). Figure 8 In the example of , the UE may determine p#1 based on the priority of the UE's synchronization reference and the first mapping as described above.

[0192] exist Figure 8 In the figure, for simplicity, a cross indicating "LBT failure" is marked at n1. However, the UE may determine that the channel access fails based on the first LBT type 1 procedure before S-SSB opportunity #m (i.e., no later than n1). In some embodiments of the present application, the UE may determine that the channel access fails based on the conditions described above (e.g., condition 1 or condition 2) before S-SSB opportunity #m.

[0193] In response to determining that channel access failed before S-SSB opportunity #m, the UE may perform a second LBT type 1 procedure associated with S-SSB opportunity #m+1 (e.g., starting from time point n2) to start a second S-SSB channel occupation starting from opportunity #m+1. The second S-SSB channel occupation may have a second COT (e.g., represented by COT#2) starting from S-SSB opportunity #m+1. The second COT may include N S-SSB COT (S-SSB#m+1) S-SSB opportunities. Figure 8 In the example of , COT#1 and COT#2 have the same end time point (e.g., n5). In this case, COT#2 (from n4 to n5) is shorter than COT#1 (from n1 to n5). It is considered that in some other embodiments, COT#1 and COT#2 may have different end time points, and COT#2 is not necessarily shorter than COT#1.

[0194] The second LBT Type 1 procedure may be performed based on another CAPC value (e.g., represented by p#2). The UE may determine p#2 based on the priority of the UE's synchronization reference and the first mapping as described above. Therefore, p#2 may have the same value as p#1.

[0195] In response to the channel being available for access based on the second LBT type 1 procedure before S-SSB opportunity #m+1, for example, determining that the channel is available for access at a time point (e.g., n3) before the start of S-SSB opportunity #m+1 (e.g., n4), the UE may transmit CPE to occupy the channel until the start of S-SSB opportunity #m+1.

[0196] Alternative Example 2

[0197] In alternative 2, the UE may perform at least one of the following steps:

[0198] Step 3-1-2-1: The UE may determine the CAPC value based on the COT of the second channel occupancy and the second mapping as described above.

[0199] Step 3-1-2-2: The UE may perform a second LBT Type 1 procedure based on the CAPC value (eg, the CAPC value determined in step 3-1-2-1).

[0200] Step 3-1-2-3: The UE may, in response to the channel being available for access based on the second LBT Type 1 procedure before the second S-SSB opportunity, transmit the CPE to occupy the channel until the second S-SSB opportunity (e.g., S-SSB opportunity #m+1) begins.

[0201] Fig. 9An exemplary channel access procedure according to some embodiments of the present application (eg, Alternative Example 2) is described.

[0202] Fig. 9 The parameters and operations of the UE described in Figure 8 Parameters and operations of the UE described in. Fig. 9 and Figure 8 The difference between the channel access procedures in Fig. 9 In the example, based on the first COT occupied by the first channel (eg, N S-SSB COT (S-SSB#m)) to determine a CAPC value p#1 associated with the first LBT type 1 procedure, and based on a second COT occupied by a second channel (e.g., N S-SSB COT (S-SSB#m+1)) to determine the CAPC value p#2 associated with the second LBT Type 1 procedure.

[0203] exist Fig. 9 In the example of , the first COT (e.g., represented by COT#1) and the second COT (e.g., represented by COT#2) have the same end time point (e.g., n5). In this case, the second COT (from n4 to n5) is shorter than the first COT (from n1 to n5). Based on the principle of mapping a COT with a shorter length to a smaller CAPC value as described above, the CAPC value p#2 may be smaller than the CAPC value p#1. Therefore, Figure 8 Compared with the alternative example 1 described in Fig. 9 The probability of successful channel access in alternative example 2 described in FIG. 1 may be increased because a smaller CAPC value p#2 may correspond to a shorter sensing interval, thereby providing an earlier channel access opportunity. It is considered that in some other embodiments, the first COT and the second COT may have different end time points, and the second COT is not necessarily shorter than the first COT.

[0204] Two alternatives to Method 2 are described below, referred to as Alternative 3 and Alternative 4.

[0205] Alternative Example 3

[0206] In alternative example 3, the UE may continue to perform the first LBT type 1 procedure before a second S-SSB opportunity (e.g., S-SSB opportunity #m+1) to start the second S-SSB channel occupation starting from the second S-SSB opportunity. After determining that the channel is available for access based on the first LBT type 1 procedure at a time after the start of the first S-SSB opportunity, the UE may occupy the channel (e.g., by transmitting dummy data or CPE) until the second S-SSB opportunity starts.

[0207] Fig.10An exemplary channel access procedure according to some embodiments of the present application is described (eg, Alternative Example 3).

[0208] like Fig.10 As shown in FIG. 1 , the UE may execute a first LBT type 1 procedure associated with S-SSB opportunity #m (eg, starting from time point n0) to initiate the first S-SSB channel occupancy starting from S-SSB opportunity #m.

[0209] The first S-SSB channel occupancy may have a first COT (e.g., represented by COT#1) from time point n1 to time point n4, where n1 is the beginning (also referred to as the starting boundary) of S-SSB opportunity #m. The first COT may include N S-SSB COT (S-SSB #m) S-SSB opportunities. The length of the time interval between two adjacent S-SSB opportunities in the first COT can be determined by T TI-S-SSB Indicates that T TI-S-SSB ≥ 0. For simplicity, Fig.10 Only two S-SSB opportunities (e.g., S-SSB opportunity #m and S-SSB opportunity #m+1) are described as an example. For simplicity, S-SSB opportunity #m and S-SSB opportunity #m+1 are Fig.10 It is represented as S-SSB#m and S-SSB#m+1.

[0210] The first LBT type 1 procedure may be performed based on a CAPC value (e.g., represented by p#1), where p#1 may be based on the priority of the synchronization reference of the UE and the first mapping as described above or based on the first COT of the first channel occupancy as described above (e.g., N S-SSB COT (S-SSB#m)) and the second mapping are used to determine.

[0211] exist Fig.10 In the figure, for simplicity, a cross indicating "LBT failure" is marked at n1. However, the UE may determine that the channel access fails based on the first LBT type 1 procedure before S-SSB opportunity #m (i.e., no later than n1). In some embodiments of the present application, the UE may determine that the channel access fails based on the conditions described above (e.g., condition 1 or condition 2) before S-SSB opportunity #m.

[0212] In response to determining that the channel access fails before S-SSB opportunity #m, the UE may continue to perform the first LBT type 1 procedure before S-SSB opportunity #m+1 to start a second S-SSB channel occupation starting from S-SSB opportunity #m+1. The second S-SSB channel occupation may have a second COT (e.g., represented by COT#2) starting from S-SSB opportunity #m+1. The second COT may include NS-SSB COT (S - SSB#m + 1) S - SSB opportunities. In Fig.10 the example of, COT#1 and COT#2 have the same end time point (e.g., n4). In this case, COT#2 (from n3 to n4) is shorter than COT#1 (from n1 to n4). It is considered that, in some other embodiments, COT#1 and COT#2 may have different end time points, and COT#2 is not necessarily shorter than COT#1.

[0213] When it is determined that the channel is available for access at a moment (e.g., n2) after the start of S - SSB opportunity #m and before the start of S - SSB opportunity #m + 1 (e.g., n3) (i.e., n1 < n2 < n3), the UE may transmit dummy data to occupy the channel until the start of S - SSB opportunity #m + 1.

[0214] Alternative Example 4

[0215] In alternative example 4, the UE may continue to perform the first LBT type 1 procedure before the second S - SSB opportunity (e.g., S - SSB opportunity #m + 1) to initiate the second S - SSB channel occupancy starting from the second S - SSB opportunity. After it is determined that the channel is available for access based on the first LBT type 1 procedure at a moment after the start of the first S - SSB opportunity, the UE may perform the third LBT type 1 procedure associated with the second S - SSB opportunity (e.g., S - SSB opportunity #m + 1) based on the minimum CAPC value.

[0216] Fig.11 Illustrate an exemplary channel access procedure (e.g., alternative example 4) according to some embodiments of the present application.

[0217] As Fig.11 shown, the UE may perform the first LBT type 1 procedure associated with S - SSB opportunity #m (e.g., starting from time point n0) to initiate the first S - SSB channel occupancy starting from S - SSB opportunity #m.

[0218] The first S - SSB channel occupancy may have a first COT from time point n1 to time point n6 (e.g., represented by COT#1), where n1 is the start of S - SSB opportunity #m (also referred to as the start boundary). The first COT may include N S-SSB COT (S - SSB#m) S - SSB opportunities. The length of the time interval between two adjacent S - SSB opportunities within the first COT may be represented by T TI-S-SSB where T TI-S-SSB ≥0. For simplicity, Fig.11Only two S-SSB opportunities (e.g., S-SSB opportunity #m and S-SSB opportunity #m+1) are described as an example. For simplicity, S-SSB opportunity #m and S-SSB opportunity #m+1 are Fig.11 It is represented as S-SSB#m and S-SSB#m+1.

[0219] exist Fig.11 Before the time point n2 in Fig.10 For example, in response to determining that the channel access fails before S-SSB opportunity #m, the UE may continue to perform the first LBT type 1 procedure before S-SSB opportunity #m+1 to start the second S-SSB channel occupation starting from S-SSB opportunity #m+1. The second S-SSB channel occupation may have a second COT (e.g., represented by COT#2) starting from S-SSB opportunity #m+1. The second COT may include N S-SSB COT (S-SSB#m+1) S-SSB opportunities. Fig.11 In the example of , COT#1 and COT#2 have the same end time point (e.g., n6). In this case, COT#2 (from n5 to n6) is shorter than COT#1 (from n1 to n6). It is considered that in some other embodiments, COT#1 and COT#2 may have different end time points, and COT#2 is not necessarily shorter than COT#1.

[0220] The difference is: in Fig.11 In the embodiment, after n2 determines that the channel is available for access, the UE may perform a third LBT type 1 procedure associated with S-SSB opportunity #m+1 based on the minimum CAPC value (e.g., represented by p#2) among the CAPC values ​​configured or preconfigured to the UE.

[0221] The third LBT type 1 procedure may be initiated at a time (eg, n3) prior to S-SSB opportunity #m+1.

[0222] In the event that it is determined that the channel is available for access at a time (e.g., n4) before the start of S-SSB opportunity #m+1 (e.g., n5), the UE may transmit CPE to occupy the channel until the start of S-SSB opportunity #m+1.

[0223] The probability of successful channel access in Alternative Example 3 may be higher than that in Alternative Example 4 because Alternative Example 3 provides an earlier channel access opportunity by occupying the channel with dummy data. However, the earlier channel access opportunity of Alternative Example 3 is achieved at the expense of lower spectral efficiency.

[0224] Two alternatives to Method 3 are described below, referred to as Alternative 5 and Alternative 6.

[0225] Alternative Example 5

[0226] In alternative example 5, in response to determining that channel access failed based on the first LBT type 1 procedure before the first S-SSB opportunity (e.g., S-SSB opportunity #m), the UE may perform an LBT type 2 procedure associated with the second S-SSB opportunity (e.g., S-SSB opportunity #m+1). That is, the LBT type 2 procedure may be performed in a time interval between the first S-SSB opportunity and the second S-SSB opportunity. In alternative example 5, the LBT type 2 procedure may be one of LBT type 2B and LBT type 2A. In some embodiments, the LBT type (e.g., LBT type 2A or 2B) of the LBT type 2 procedure may be indicated by configuration information configured or preconfigured to the UE.

[0227] Fig.12 An exemplary channel access procedure according to some embodiments of the present application is described (eg, Alternative Example 5).

[0228] like Fig.12 As shown in FIG. 1 , the UE may execute a first LBT type 1 procedure associated with S-SSB opportunity #m (eg, starting from time point n0) to initiate the first S-SSB channel occupancy starting from S-SSB opportunity #m.

[0229] Fig.12 The first S-SSB channel occupancy described in Figure 8 The first S-SSB channel occupancy is the same as that described in Fig.12 The operation for determining a channel access failure based on a first LBT type 1 procedure performed by the UE before S-SSB opportunity #m in the example of Figure 8 The operations described are the same.

[0230] The difference is: in Fig.12 In response to determining that channel access fails based on the first LBT type 1 procedure before S-SSB opportunity #m, the UE performs the LBT type 2 procedure associated with S-SSB #m+1 within a time interval (greater than zero) between S-SSB opportunity #m and S-SSB opportunity #m+1. The specific operation may include at least one of the following steps.

[0231] Step 3-3-1-1: The UE may determine the length of the sensing interval within the time interval based on the LBT type of the first LBT type 2 procedure.

[0232] Step 3-3-1-2: The UE may perform LBT Type 2 procedure within the sensing interval.

[0233] In some cases, the UE may determine the length of the CPE based on the priority of the UE's synchronization reference and the third mapping as described above. For example, a higher priority of the synchronization reference may be mapped to a longer CPE. In some embodiments of the present application, the length of the CPE may be determined by T CPE =N UT *T UT In such embodiments, T UT is a time unit configured or preconfigured for the UE, and N UT is the number of time units determined based on the priority of the UE's synchronization reference and the third mapping as described above. In such a case, the earliest starting point of the LBT Type 2 procedure is T relative to the start of S-SSB opportunity #m+1 (e.g., n4). SI +T CPE , where T SI is the length of the sensing interval and T CPE is the length of the CPE. Fig.12 In the example, the starting point of the LBT type 2 procedure is n2.

[0234] Step 3-3-1-3: When it is determined at time point n3 that the channel is available for access based on the first LBT Type 2 procedure, the UE may transmit CPE to occupy the channel until S-SSB opportunity #m+1 starts (e.g., time point n4).

[0235] In addition, according to some embodiments of the present application, the method of alternative example 5 may be triggered in response to the remaining duration of the first COT (for example, the number of remaining S-SSB opportunities in the first COT) being lower than a threshold configured or preconfigured for the UE.

[0236] Alternative Example 6

[0237] In alternative example 6, in response to determining that channel access fails based on the first LBT type 1 procedure before the first S-SSB opportunity (e.g., S-SSB opportunity #m), the UE may perform an LBT type 2 procedure associated with the first S-SSB. That is, the LBT type 2 procedure may be performed before the first S-SSB opportunity. In alternative example 6, the LBT type 2 procedure may be one of LBT type 2B and LBT type 2A. In some embodiments, the LBT type (e.g., LBT type 2A or 2B) of the LBT type 2 procedure may be indicated by configuration information configured or preconfigured to the UE.

[0238] Fig.13 An exemplary channel access procedure according to some embodiments of the present application is described (eg, Alternative Example 6).

[0239] like Fig.13As shown, the UE may execute a first LBT type 1 procedure associated with the S-SSB occasion #m (e.g., starting from time point n0) to initiate the first S-SSB channel occupancy starting from the S-SSB occasion #m.

[0240] The first S-SSB channel occupancy may have a first COT from time point n1 to time point n4 (e.g., represented by COT#1), where n1 is the start of the S-SSB occasion #m (also referred to as the starting boundary). The first COT may include N S-SSB COT (S-SSB#m) S-SSB occasions. The length of the time interval between two adjacent S-SSB occasions within the first COT may be represented by T TI-S-SSB where T TI-S-SSB ≥0. For simplicity, Fig.13 only two S-SSB occasions (e.g., S-SSB occasion #m and S-SSB occasion #m+1) are illustrated as examples. For simplicity, S-SSB occasion #m and S-SSB occasion #m+1 are represented as S-SSB#m and S-SSB#m+1 in Fig.13 respectively.

[0241] The first LBT type 1 procedure may be executed based on the CAPC value (e.g., represented by p#1), where p#1 may be determined based on the priority of the UE's synchronization reference and the first mapping as described above or based on the first COT of the first channel occupancy (e.g., N S-SSB COT (S-SSB#m)) and the second mapping as described above.

[0242] In Fig.13 the UE may determine a channel access failure based on the first LBT type 1 procedure before the start of the S-SSB occasion #m (e.g., at time point n2, where n2 < n1). For example, when condition 1 or condition 2 is satisfied, the UE may determine a channel access failure.

[0243] In response to determining a channel access failure before the S-SSB occasion #m, the UE may execute an LBT type 2 procedure before the S-SSB occasion #m. The specific operations may include at least one of the following steps.

[0244] Step 3-3-2-1: The UE may determine the length of the sensing interval within the time interval based on the LBT type of the first LBT type 2 procedure.

[0245] Step 3-3-2-2: The UE may execute the LBT type 2 procedure within the sensing interval.

[0246] In some cases, the UE may determine the length of the CPE based on the priority of the UE's synchronization reference and the third mapping as described above. Fig.12 The operations described for determining the length of CPE are also applicable here. In such cases, the earliest starting point of the LBT Type 2 procedure is T relative to the start of S-SSB opportunity #m (e.g., n1). SI +T CPE , where T SI is the length of the sensing interval and T CPE is the length of the CPE. Fig.13 In the example, the starting point of the LBT type 2 procedure is n2.

[0247] Step 3-3-2-3: When it is determined at time point n3 that the channel is available for access based on the first LBT Type 2 procedure, the UE may transmit CPE to occupy the channel until S-SSB opportunity #m begins.

[0248] Fig.14 A simplified block diagram illustrating an exemplary apparatus 1400 for S-SSB transmission in unlicensed spectrum according to some embodiments of the present application. In some embodiments, the apparatus 1400 may be or include a UE (e.g., Figure 1 In some other embodiments, the device 1400 may be or include a BS (e.g., Figure 1 At least a portion of BS102).

[0249] refer to Fig.14 , the apparatus 1400 may include at least one transmitter 1402, at least one receiver 1404, and at least one processor 1406. The at least one transmitter 1402 is coupled to the at least one processor 1406, and the at least one receiver 1404 is coupled to the at least one processor 1406.

[0250] Although in this figure, elements such as transmitter 1402, receiver 1404, and processor 1406 are illustrated in singular form, plural form is contemplated unless limitation to the singular form is explicitly stated. In some embodiments of the present application, transmitter 1402 and receiver 1404 may be combined into one device, such as a transceiver. In some embodiments of the present application, apparatus 1400 may further include an input device, a memory, and / or other components. Transmitter 1402, receiver 1404, and processor 1406 may be configured to perform any of the methods described herein (e.g., regarding Figures 5 to 13 ).

[0251] According to some embodiments of the present application, the device 1400 may be a UE, and the transmitter 1402, the receiver 1404, and the processor 1406 may be configured to perform the Figures 5 to 13 Operations of a method performed by a UE as described in any of . For example, the processor 1406 may be configured to: obtain configuration information for S-SSB in an unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes a condition for determining a channel access failure based on an LBT type 1 procedure before a target S-SSB opportunity; execute a first LBT type 1 procedure associated with a first S-SSB opportunity to start occupation of a first S-SSB channel starting from the first S-SSB opportunity; and in response to determining that the channel access failure has occurred based on the first LBT type 1 procedure and the configuration information before the first S-SSB opportunity, perform at least one of the following operations: execute a second LBT type 1 procedure associated with a second S-SSB opportunity immediately following the first S-SSB opportunity to start occupation of a second S-SSB channel starting from the second S-SSB opportunity; continue to execute the first LBT type 1 procedure before the second S-SSB opportunity to start occupation of a second S-SSB channel starting from the second S-SSB opportunity; or execute a first LBT type 2 procedure. The transmitter 1402 may be configured to transmit an S-SSB at a first S-SSB opportunity in response to a channel being available for access based on a first LBT Type 1 procedure prior to the first S-SSB opportunity.

[0252] According to some embodiments of the present application, the device 1400 may be a BS, and the transmitter 1402, the receiver 1404, and the processor 1406 may be configured to perform the Figures 5 to 13 Operations of a method performed by a BS as described in any of . For example, the transmitter 1402 may be configured to transmit configuration information for S-SSB in an unlicensed spectrum, wherein the configuration information includes at least one of: a condition for determining a channel access failure based on an LBT type 1 procedure before a target S-SSB opportunity; a first mapping between a CAPC value and a priority of a synchronization reference; a second mapping between a CAPC value and a COT; or a third mapping between a length of a CPE and a priority of a synchronization reference.

[0253] In some embodiments of the present application, the device 1400 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 1406 to implement any of the methods described above. For example, when the computer-executable instructions are executed, the processor 1406 may interact with the transmitter 1402 and / or the receiver 1404 to perform the operations of the method, such as, for example, as to Figures 5 to 13 as described by any of .

[0254] 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 may be used to implement the processor functions of the present application. For example, an embodiment of the present application provides an apparatus for S-SSB transmission in an unlicensed spectrum, which includes a processor and a memory. Computer programmable instructions for implementing a method for 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 a method for S-SSB transmission in an unlicensed spectrum. The method for S-SSB transmission in an unlicensed spectrum may be any method as described in the present application.

[0255] 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 a method for S-SSB transmission in an unlicensed spectrum according to any embodiment of the present application.

[0256] Although the present application has been described with reference to the specific embodiments of the present application, it is apparent that many substitutions, modifications and changes may be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added or substituted in other embodiments. Moreover, 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 to which the disclosed embodiments belong 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 set forth herein are intended to be illustrative and not restrictive. Various changes may 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 configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes conditions for determining a channel access failure based on a listen-before-talk (LBT) type 1 procedure before a target S-SSB opportunity; executing a first LBT type 1 procedure associated with a first S-SSB opportunity to initiate occupation of a first S-SSB channel starting from the first S-SSB opportunity; and In response to determining that channel access failed based on the first LBT type 1 procedure and the configuration information before the first S-SSB opportunity, at least one of the following operations is performed: performing a second LBT type 1 procedure associated with a second S-SSB opportunity immediately following the first S-SSB opportunity to initiate occupation of a second S-SSB channel starting from the second S-SSB opportunity; Continue to execute the first LBT type 1 procedure before the second S-SSB opportunity to start a second S-SSB channel occupation starting from the second S-SSB opportunity; or executing a first LBT type 2 procedure; a transmitter coupled to the processor and configured to transmit an S-SSB at the first S-SSB opportunity in response to a channel being available for access based on the first LBT Type 1 procedure prior to the first S-SSB opportunity; and A receiver is coupled to the processor.

2. The UE of claim 1 , wherein the condition for determining a channel access failure based on an LBT Type 1 procedure before a target S-SSB opportunity comprises at least one of: The deferral duration of the LBT Type 1 procedure cannot be completed before the target S-SSB opportunity associated with the LBT Type 1 procedure; or The random backoff procedure of the LBT Type 1 procedure cannot be completed before the target S-SSB opportunity.

3. The UE according to claim 1, wherein the configuration information further comprises at least one of the following: a first mapping between a channel access priority class CAPC value and a priority of a synchronization reference; A second mapping between CAPC values ​​and channel occupancy time COT; or A third mapping between the length of the cyclic prefix extension CPE and the priority of the synchronization reference.

4. The UE according to claim 3, Wherein a higher priority of synchronization reference is mapped to a smaller CAPC value; where a COT with a shorter length is mapped to a smaller CAPC value; or Where higher priority of synchronization reference is mapped to longer CPE.

5. The UE of claim 3, wherein the processor is configured to perform at least one of the following: Determine a CAPC value based on the priority of the synchronization reference of the UE and the first mapping or based on the COT occupied by the first S-SSB channel and the second mapping; performing the first LBT Type 1 procedure based on the CAPC value; or In response to a channel being available for access based on the first LBT Type 1 procedure before the first S-SSB opportunity, the transmitting CPE occupies the channel until the first S-SSB opportunity begins.

6. The UE of claim 1, wherein the processor is further configured to, after the transmitter transmits the S-SSB at the first S-SSB opportunity, perform a second LBT Type 2 procedure associated with the second S-SSB opportunity.

7. The UE of claim 6, wherein the processor is configured to perform at least one of the following: determining a time interval between the first S-SSB opportunity and the second S-SSB opportunity and a sensing interval within the time interval, wherein a length of the sensing interval is based on at least one of: an LBT type of the second LBT type 2 procedure or a length of the time interval; performing, in the sensing interval, the second LBT type 2 procedure associated with the second S-SSB opportunity; or Before the second S-SSB opportunity begins, in response to the second LBT type 2 procedure being successful, the transmitting CPE occupies a channel until the second S-SSB opportunity begins.

8. The UE of claim 3, wherein the processor is configured to perform at least one of the following: determining a CAPC value based on a priority of a synchronization reference of the UE and the first mapping; performing the second LBT Type 1 procedure based on the CAPC value; or In response to the channel being available for access based on the second LBT Type 1 procedure before the second S-SSB opportunity, the transmitting CPE occupies the channel until the second S-SSB opportunity begins.

9. The UE of claim 3, wherein the processor is configured to perform at least one of the following: determining a CAPC value based on the COT occupied by the second channel and the second mapping; performing the second LBT Type 1 procedure based on the CAPC value; or In response to the channel being available for access based on the second LBT Type 1 procedure before the second S-SSB opportunity, the transmitting CPE occupies the channel until the second S-SSB opportunity begins.

10. The UE of claim 1, wherein the processor is further configured to transmit dummy data to occupy the channel until the second S-SSB opportunity starts after determining that the channel is available for access based on the first LBT Type 1 procedure at a moment after the first S-SSB opportunity starts.

11. The UE according to claim 1, wherein the processor is further configured to: after determining that the channel is available for access based on the first LBT type 1 procedure at a moment after the start of the first S-SSB opportunity, perform a third LBT type 1 procedure associated with the second S-SSB opportunity based on a minimum CAPC value.

12. The UE of claim 1 , wherein the first LBT Type 2 procedure is performed in a time interval between the first S-SSB opportunity and the second S-SSB opportunity, and the processor is configured to perform at least one of the following: determining a length of a sensing interval within the time interval based on an LBT type of the first LBT type 2 procedure; performing the first LBT type 2 procedure during the sensing interval; or In response to the channel being available for access based on the first LBT Type 2 procedure, the transmitting CPE occupies the channel until the second S-SSB opportunity begins.

13. The UE of claim 1 , wherein in response to determining that channel access fails based on the first LBT type 1 procedure before the first S-SSB opportunity, the first LBT type 2 procedure is performed before the first S-SSB opportunity, and the processor is configured to perform at least one of the following: determining a length of a sensing interval within the time interval based on an LBT type of the first LBT type 2 procedure; performing the first LBT type 2 procedure during the sensing interval; or In response to the channel being available for access based on the first LBT Type 2 procedure, the transmitting CPE occupies the channel until the first S-SSB opportunity begins.

14. A base station BS, comprising: A transmitter configured to: Transmitting configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum, wherein the configuration information includes at least one of the following: Used to determine the conditions for channel access failure based on the listen-before-talk LBT Type 1 procedure before the target S-SSB opportunity; a first mapping between a channel access priority class CAPC value and a priority of a synchronization reference; A second mapping between CAPC values ​​and channel occupancy time COT; or A third mapping between the length of the cyclic prefix extension CPE and the priority of the synchronization reference; a processor coupled to the transmitter; and A receiver is coupled to the processor.

15. A method performed by a user equipment UE, comprising: obtaining configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes conditions for determining a channel access failure based on a listen-before-talk (LBT) type 1 procedure before a target S-SSB opportunity; executing a first LBT type 1 procedure associated with a first S-SSB opportunity to initiate occupation of a first S-SSB channel starting from the first S-SSB opportunity; In response to determining that channel access failed based on the first LBT type 1 procedure and the configuration information before the first S-SSB opportunity, at least one of the following operations is performed: performing a second LBT type 1 procedure associated with a second S-SSB opportunity immediately following the first S-SSB opportunity to initiate occupation of a second S-SSB channel starting from the second S-SSB opportunity; Continue to execute the first LBT type 1 procedure before the second S-SSB opportunity to start a second S-SSB channel occupation starting from the second S-SSB opportunity; or executing a first LBT type 2 procedure; and In response to, prior to the first S-SSB opportunity, based on the first LBT Type 1 procedure, the channel being available for access, an S-SSB is transmitted at the first S-SSB opportunity.

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