Method and apparatus for S-SSB transmission in unlicensed spectrum

Abstract

The embodiment of the invention relates to a method and equipment for sidelink synchronization signal block (S-SSB) transmission in an unlicensed spectrum. In accordance with an embodiment of the present disclosure, a user equipment (UE) may include a processor configured to obtain configuration information for an S-SSB in an unlicensed spectrum based on a configuration or a pre-configuration, where the configuration information includes at least one of a first configuration, a second configuration, and a third configuration. The S-SSB opportunities are associated with time intervals between adjacent S-SSB opportunities sharing the same channel occupancy time (COT); a second configuration for performing listen before talk (LBT) type 2; or a third configuration for performing LBT Type 1; and executing an LBT program associated with an S-SSB occasion based on the configuration information; a transmitter coupled to the processor and configured to transmit an S-SSB on the S-SSB occasion in response to the LBT program being successful; 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 neighboring user equipments (UEs) without the data having to pass through a base station (BS) or core network. Sidelink communication systems have been introduced into 3GPP 5G wireless communication technology, where a direct link between two UEs is called a sidelink.

[0003] The sidelink synchronization information is carried in the 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 at least one of the following: a first configuration, which is associated with the time interval between adjacent S-SSB opportunities sharing the same channel occupancy time (COT); a second configuration, which is used to perform listen-before-talk (LBT) type 2; or a third configuration, which is used to perform LBT type 1; and based on the configuration information, perform an LBT procedure associated with the S-SSB opportunity; a transmitter, which is coupled to the processor and configured to transmit an S-SSB on the S-SSB opportunity in response to the success of the LBT procedure; and a receiver, which is coupled to the processor.

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

[0007] 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).

[0008] In some embodiments of the present application, the first configuration indicates at least one of: the length of the time interval; the position of the time interval; or the configuration of the time interval.

[0009] In some embodiments of the present application, the time interval occupies one or more orthogonal frequency division multiplexing (OFDM) symbols, and the number of OFDM symbols included in the time interval is determined based on the maximum length of the sensing interval used to perform the LBT procedure and the SCS.

[0010] In some embodiments of the present application, the construction of the time interval includes at least one of the following: the length of the sensing interval for performing the LBT procedure, the location of the sensing interval, or the content for filling in the time interval.

[0011] In some embodiments of the present application, the position of the sensing interval is immediately after the previous symbol adjacent to the time interval or immediately before the next symbol adjacent to the time interval; or the content used to fill in the time interval is a complete or partial copy of the symbol adjacent to the time interval, or a cyclic prefix extension (CPE) of the first symbol in the S-SSB opportunity next to the time interval.

[0012] In some embodiments of the present application, the second configuration indicates at least one of: the LBT type; the time unit used to calculate the length of the CPE; a mapping between the number of time units used to calculate the length of the CPE and the priority of the synchronization reference; or the maximum channel occupancy time (MCOT) for S-SSB.

[0013] In some embodiments of the present application, a higher priority of a synchronization reference is mapped to the number of time units associated with a longer CPE.

[0014] In some embodiments of the present application, the third configuration indicates at least one of: an LBT type; 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 length of a COT for S-SSB; or an MCOT for S-SSB.

[0015] In some embodiments of the present application, higher priorities of synchronization references are mapped to smaller CAPC values.

[0016] In some embodiments of the present application, a shorter length of COT for SSB is mapped to a smaller CAPC value.

[0017] In some embodiments of the present application, the MCOT for S-SSB is defined as the maximum number of S-SSBs to be transmitted within one COT, or is defined as the maximum channel occupancy time for continuous S-SSB transmission.

[0018] In some embodiments of the present application, the processor is configured to: execute the LBT procedure associated with the S-SSB opportunity in a sensing interval, wherein the length of the sensing interval is determined based on the LBT type; and the transmitter is further configured to transmit the CPE to occupy the channel until the start boundary of the S-SSB opportunity in response to the success of the LBT procedure.

[0019] In some embodiments of the present application, the configuration information further includes at least one of the following: the maximum number of S-SSBs to be transmitted within an S-SSB period; or the maximum number of S-SSBs to be transmitted within an S-SSB window.

[0020] 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 first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT; a second configuration for performing LBT type 2; or a third configuration for performing LBT type 1; and a processor coupled to the transmitter; and a receiver coupled to the processor.

[0021] 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 at least one of the following: a first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT; a second configuration for performing LBT type 2; or a third configuration for performing LBT type 1; performing an LBT procedure associated with the S-SSB opportunity based on the configuration information; and transmitting an S-SSB at the S-SSB opportunity in response to success of the LBT procedure.

[0022] 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 first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT; a second configuration for performing LBT type 2; or a third configuration for performing LBT type 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 therefore should not be considered to limit its scope.

[0024] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

[0025] Figure 2 illustrating exemplary S-SSB time slots according to some embodiments of the present disclosure;

[0026] Figure 3 An exemplary distribution of opportunities for S-SSB according to some embodiments of the present disclosure is described;

[0027] Figure 4 A flow chart illustrating an exemplary method for S-SSB transmission in unlicensed spectrum according to some embodiments of the present application;

[0028] Figure 5 An exemplary time domain structure of a time interval between two adjacent S-SSBs according to some embodiments of the present application is illustrated;

[0029] Figure 6 An exemplary time domain structure of a time interval between two adjacent S-SSBs according to some other embodiments of the present application is illustrated;

[0030] Figure 7 An exemplary time domain structure for performing LBT Type 2 according to some embodiments of the present application is described;

[0031] Figure 8 An exemplary time domain structure for performing LBT Type 1 according to some embodiments of the present application is described;

[0032] Fig. 9 An exemplary distribution of S-SSB opportunities within an S-SSB period according to some embodiments of the present application is described; and

[0033] Fig.10 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

[0034] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application, but 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 implemented by different embodiments that are intended to be included in the spirit and scope of the present application.

[0035] Although the operations are depicted in a particular order in the drawings, those skilled in the art will readily recognize that such operations need not be performed in the particular order shown or in sequential order, or that all of the illustrated operations need not be performed to achieve a desired result; one or more operations may sometimes be skipped. In addition, the drawings may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous.

[0036] 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 Air Interface (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 listed in the present application may be changed, which should not affect the principles of the present application.

[0037] Figure 1 An exemplary wireless communication system 100 is illustrated in accordance with some embodiments of the present application.

[0038] As in Figure 1 As shown in FIG. 1 , the wireless communication system 100 includes at least one UE 101 and at least one BS 102. Specifically, for illustrative 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 .

[0039] 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 security camera), a vehicle-mounted computer, a network device (e.g., a router, a switch, and a modem), or the like.

[0040] According to some other embodiments of the present disclosure, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals over a wireless network.

[0041] In some other embodiments according to the present disclosure, UE 101 includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, or the like.

[0042] According to some embodiments of the present disclosure, UE 101 may include a vehicle UE (VUE) and / or an energy-saving UE (also known 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 UEs that require energy saving compared to a VUE.

[0043] In addition, UE 101 may be referred to as a subscriber unit, mobile equipment, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal or device, or described using other terms used in the art.

[0044] In a sidelink communication system, a transmitting UE may also be named a transmitting UE, a Tx UE, a sidelink Tx UE, a sidelink transmitting UE, or the like. A receiving UE may also be named a receiving UE, a Rx UE, a sidelink Rx UE, a sidelink receiving UE, or the like.

[0045] 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 a multicast group ( 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.

[0046] Alternatively, according to Figure 1 In some other embodiments, UE 101b functions as a Tx UE and transmits a sidelink message, and UE 101a functions as a Rx UE and receives a sidelink message from UE 101b.

[0047] 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.

[0048] exist Figure 1 In an embodiment of the present disclosure, both UE 101a and UE 101b 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, base unit, macro cell, Node B, evolved Node B (eNB), gNB, home Node B, relay node or device, or described using other terms used in the art. BS 102 is typically part of a wireless access network, which may include one or more controllers communicatively coupled to one or more corresponding BS 102.

[0049] 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 3GPP5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0050] 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 OFDM modulation scheme on a 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 an 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.

[0051] 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 specific 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.

[0052] In NR, accommodating multiple uncoordinated UEs in unlicensed spectrum requires a channel access procedure defined for NR. After a successful channel access procedure is performed by a communication node, the channel may be used by the communication node during a period of time until the end of the period of time. This period of time 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.

[0053] A dynamic channel access procedure is typically used by a BS or UE to access a channel in an unlicensed spectrum. The dynamic channel access procedure may be based on LBT, where the transmitter listens to potential transmission activity on the channel before transmitting, and 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, which is also referred to as LBT type 1 or LBT cat4. The other is a type-2 dynamic channel access procedure, which is also referred to as LBT type 2.

[0054] The type-1 dynamic channel access procedure can be used to start data transmission at the beginning of COT. The initiator for the type-1 dynamic channel access procedure can be the BS or the UE. The type-1 dynamic channel access procedure can be summarized as follows.

[0055] First, the initiator listens and waits until a channel (eg, a frequency channel) is available for at least a period of time called a hold-off period. The hold-off period may be from 16 μs to a number (eg, “m p ", which will be described below) 9μs time slot. As shown in Table 1 and Table 2, "m p The value of " depends on the value of CAPC (denoted as "p"). Therefore, the deferral period depends on the value of CAPC, as shown in Table 1 or Table 2 below. If the received energy during at least 4μs in each 9μs time slot is below the threshold, the channel is declared available.

[0056] Once the channel has been declared available during the hold-off period, the transmitter begins a backoff procedure during which it will wait for a random period of time.

[0057] The UE starts the backoff procedure by initializing the backoff timer with a random number within the contention window (CW). The random number is taken from a uniform distribution [0, CW] and indicates that the channel must be available within the timer duration (e.g., defined by the random number multiplied by 9 μs) before transmission can occur. The value of "CW" can be selected from the "Allowed CW" in Table 1 or Table 2 below. p Size” (minimum value is CW min,p , and the maximum value is expressed as CW max,p ), depending on the value of CAPC.

[0058] When the channel is detected to be idle for each 9 μs duration, the back-off timer is decremented by one; whenever the channel is sensed to be busy, the back-off timer is suspended until the channel has been idle for the deferral period.

[0059] Once the backoff timer has expired (eg, the backoff timer is reduced to 0), the random backoff procedure is complete and the transmitter has acquired the channel and may use it for transmission until the MCOT (eg, T in Table 1 below). mcot,p Or T in Table 2 below ulmcot,p , which depends on the value of CAPC).

[0060] Tables 1 and 2 below illustrate exemplary CAPCs for DL ​​and UL, respectively, and m p , CW min,p , CW max,p , T mcot,p , T ulmcot,p The corresponding value of 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 activate COT 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 permitted CW p When the UE intends to activate COT 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 permitted CW p size).

[0061] Table 1: DL channel access priority levels

[0062]

[0063] Table 2: UL channel access priority levels

[0064]

[0065] 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., not acknowledged (NACK)) is received, the contention window is (approximately) doubled to the limit CW max,p For a positive HARQ report (eg, an acknowledgement (ACK)), the contention window is reset to its minimum value, ie, CW = CW. min,p .

[0066] The type-2 dynamic channel access procedure can be used for transmission of COT sharing and discovery bursts. Depending on the duration of the gap in the COT (also referred to as the "COT sharing gap"), the type-2 dynamic channel access procedure can be further divided into the following three procedures, where the procedure to be used can be determined depending on the duration of the gap between two transmission bursts.

[0067] Type 2A dynamic channel access procedure (also known as LBT cat2 or LBT type 2A): It is used to transmit discovery bursts when the gap is 25 μs or more.

[0068] Type 2B dynamic channel access procedure (also known as LBT Type 2B): It is used when the gap is 16 μs.

[0069] • Type 2C dynamic channel access procedure (also known as LBT Type 2C): It is used when the gap after the previous transmission burst is 16 μs or less.

[0070] For Type 2C dynamic channel access procedure, idle sensing is not required between transmit bursts. In such scenarios, 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.

[0071] 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 it is detected to be busy, COT sharing fails, and COT sharing cannot be used for transmission in this COT. If the COT sharing gap is 16μs, the Type 2B dynamic channel access procedure can be used, and the channel must be detected to be idle in the 16μs gap before the next transmission burst. If the COT sharing gap is 25μs or longer, the Type 2A dynamic channel access procedure can be used, and the channel must be detected to be idle during at least 25μs immediately before the next transmission burst.

[0072] 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.

[0073] 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.

[0074] 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 in the S-SSB slot, such as symbol #1 and symbol #2. The S-SSS is repeatedly transmitted on the fourth and fifth symbols in the S-SSB slot, such as symbol #3 and symbol #4. The S-PSS and S-SSS occupy 127 subcarriers in the frequency domain, which are from the third subcarrier to the 129th subcarrier relative to the beginning of the S-SSB bandwidth.

[0075] S-PSS and S-SSS are collectively referred to as Sidelink Synchronization Signal (SLSS). SLSS is used for time and frequency synchronization. By detecting the SLSS sent by a synchronization reference UE (also referred to as a SyncRef UE), a UE can synchronize with the SyncRef UE and estimate the start of a frame and a carrier frequency offset.

[0076] The S-PSS can be generated from a maximum length sequence (m-sequence) using the same design (i.e., generator polynomial, initial value, cyclic shift, etc.) used in the 3GPP document to generate the m-sequence in the primary synchronization signal (PSS). In NR Uu, there are three candidate sequences for the PSS. However, only two candidate sequences are used for the S-PSS.

[0077] 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 in the 3GPP document to generate the Secondary Synchronization Signal (SSS). This results in 336 candidate sequences for the S-SSS, just like the SSS in NR Uu.

[0078] For the transmission of SLSS within S-SSB, SyncRef UE can select S-PSS and S-SSS from the candidate sequences based on SLSS identifier (ID). SLSSID represents the identifier of SyncRef UE and conveys the priority of SyncRef UE as in LTE V2X. Each SLSSID corresponds to a unique combination of S-PSS and S-SSS among 2 S-PSS candidate sequences and 336 S-SSS candidate sequences.

[0079] The main purpose of PSBCH is to provide system-wide information and synchronization information required by the UE 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. In the case of using extended CP, the PSBCH is transmitted on the first symbol and six symbols after the S-SSS in the S-SSB slot. The PSBCH occupies 132 subcarriers in the frequency domain. The PSBCH in the first symbol of the S-SSB slot is used for automatic gain control (AGC). The last symbol in the S-SSB slot (e.g., symbol #13) is used as a guard symbol.

[0080] The UE may be configured with a configuration for an S-SSB period including one or more S-SSB opportunities. Figure 3 An exemplary distribution of timings of S-SSB according to some embodiments of the present disclosure is described.

[0081] like Figure 3As shown in FIG. 1 , within one S-SSB period, there are 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 start time slot of the S-SSB period to the first S-SSB opportunity in the S-SSB period, such as S-SSB#0, which is 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 of 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 the SSB based on the configuration.

[0082] The S-SSB period may include 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:

[0083] Table 3 Number of S-SSB opportunities within the S-SSB period (160ms)

[0084]

[0085] Figure 2 The structure of S-SSB time slot and Figure 3 The distribution of the timing of S-SSB in is for illustrative purposes only. It is considered that with the development of network architecture and new service scenarios, S-SSB may have other structures (for example, S-SSB may include 4 OFDM symbols in the time domain), and the timing distribution of S-SSB within an S-SSB period may change, which should not affect the principles of the present application.

[0086] 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.

[0087] Compared with the licensed spectrum, the unlicensed spectrum may require more S-SSB opportunities for the following two reasons. One reason is to provide the UE with the desired channel access opportunities. Another reason is that S-SSB will be used in new scenarios, such as supporting latency-critical services, supporting beam-based transmission, etc.

[0088] Additionally, if accessing each S-SSB opportunity requires having a long independent LBT procedure, then the energy consumption will primarily scale with the number of S-SSB transmissions.

[0089] In view of the above, there is a need to address how to support S-SSB transmission (e.g., COT-based S-SSB transmission or single S-SSB transmission) in unlicensed spectrum.

[0090] The embodiments of the present application provide an improved solution for S-SSB transmission in unlicensed spectrum, which proposes configuration, signaling and procedures for implementing a channel access procedure (or LBT procedure) before S-SSB transmission, thereby supporting COT-based S-SSB transmission in unlicensed spectrum. More details will be described below in conjunction with the accompanying drawings.

[0091] Figure 4 A flow chart illustrating an exemplary method 400 for S-SSB transmission in unlicensed spectrum according to some embodiments of the present application. Figure 4 The method 400 described in the embodiment may be performed by a UE (eg, Figure 1 UE 101a or UE 101b) or other devices with similar functions are executed.

[0092] As in Figure 4 As shown in the figure, in step 401, the UE may obtain configuration information for S-SSB in unlicensed spectrum based on configuration or pre-configuration; in step 403, the UE may perform an LBT procedure associated with the S-SSB opportunity based on the configuration information; in step 405, the UE may transmit an S-SSB at the S-SSB opportunity in response to the success of the LBT procedure.

[0093] In some embodiments of the present application, the UE may obtain configuration information based on configuration. Specifically, obtaining configuration information based on configuration (ie, the configuration information is configured to the UE) may refer to: the configuration information is provided by the BS (eg, Figure 1 BS102 shown in FIG) is transmitted to the UE via at least one of the following: SIB message, MIB message, RRC signaling or MAC CE or downlink control information (DCI), so that the UE can receive the configuration information from the BS. In an embodiment of the present application, obtaining the configuration information based on the configuration can be applied to a scenario in which the UE is in the coverage of the network.

[0094] 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., the configuration information is pre-configured to the UE) may mean that the configuration information may be hardwired into the UE or stored on a subscriber identity module (SIM) or universal subscriber 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 applied to a scenario in which the UE is out of coverage of the network.

[0095] In some embodiments of the present application, the configuration information is based on at least one of the following granularities: per channel bandwidth, per carrier, per bandwidth portion, per frequency range, or per SCS.

[0096] The configuration information may include at least one of: a first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT (e.g., represented as TI-S-SSB); a second configuration for performing LBT type 2; or a third configuration for performing LBT type 1.

[0097] The first configuration may be used to support continuous S-SSB transmission within the same COT. The time interval determined based on the first configuration may be used between adjacent S-SSB opportunities having any structure in the time domain and the frequency domain. For example, the S-SSB opportunities may have a structure such as Figure 2 , where an S-SSB opportunity occupies one time slot in the time domain. In another example, an S-SSB opportunity may occupy 4 symbols (e.g., OFDM symbols) in the time domain. In some other examples, an S-SSB opportunity may occupy any other number of symbols in the time domain.

[0098] The first configuration associated with the time interval may take into account the following features.

[0099] In some embodiments, to support continuous S-SSB transmission, an important feature is the sensing interval for channel access between two adjacent S-SSB opportunities, regardless of how many symbols the S-SSB opportunity occupies (e.g., 4 symbols, one time slot, etc.). Therefore, the time interval may include the sensing interval.

[0100] The duration of the sensing interval may be set according to the following considerations.

[0101] On the one hand, a short sensing interval duration is expected so that more S-SSB opportunities can be obtained within a given duration of resources used for S-SSB transmission. In some extreme cases, two adjacent S-SSB opportunities may be distributed in the time domain in a continuous manner without any gap in between.

[0102] On the other hand, a long sensing interval duration is contemplated so that sufficient time is guaranteed to perform the channel access procedure before each S-SSB opportunity. In that case, the duration of the sensing interval may depend on the type of LBT to be used.

[0103] Additionally, the duration of the sensing interval may also need to take into account a gap (eg, one symbol) for supporting switching between transmission and reception of the same UE.

[0104] In some embodiments, to ensure that S-SSB transmissions are aligned with OFDM symbol boundaries, the time interval between adjacent S-SSB opportunities may include a positive integer number of OFDM symbols.

[0105] In view of the above, the first configuration associated with the time interval may indicate at least one of: a length of the time interval; a location of the time interval; or a configuration of the time interval.

[0106] The time interval may occupy one or more OFDM symbols. In some embodiments, the length of the time interval may be defined by the number of OFDM symbols included in the time interval. In some other embodiments, the length of the time interval may be defined by a duration that is a multiple of the duration of the OFDM symbol. The number of OFDM symbols included in the time interval may be determined based on the maximum length of the sensing interval for performing the LBT procedure and the SCS. For example, for a given SCS, if the maximum length of the sensing interval for performing the LBT procedure is not longer than one OFDM symbol, then one OFDM symbol may be sufficient as the time interval. Otherwise, more OFDM symbols may be required.

[0107] The time interval may be located between two adjacent S-SSB opportunities (e.g., between two adjacent S-SSB opportunities within the same COT). For example, the time interval may be immediately between adjacent S-SSB opportunities. In other words, the time interval is immediately after the last symbol of one of the two adjacent S-SSB opportunities and immediately before the first symbol of the other of the two adjacent S-SSB opportunities.

[0108] The location of the time interval is suitable for any S-SSB as defined in the current 3GPP standard documents and to be defined in future 3GPP standard documents. For example, if the S-SSB occupies 4 OFDM symbols in the time domain, the time interval can be located at the symbol before each S-SSB. In another example, if the S-SSB occupies 13 OFDM symbols in a time slot, the time interval can be located at the last symbol of the time slot containing the S-SSB, i.e., the 14th symbol.

[0109] The time interval may be filled completely or partially with certain content to obtain the desired length of the sensing interval for performing the LBT procedure. Thus, the construction of the time interval may include at least one of the following: the length of the sensing interval for performing the LBT procedure, the location of the sensing interval, or the content for filling in the time interval.

[0110] According to the content filled in the time interval, the construction of the time interval may include the following two cases, namely, case 1 and case 2.

[0111] In case 1, the content used to fill in the time interval is a complete or partial copy of the symbol adjacent to the time interval, so that the sensing interval within the time interval is no more than 16 μs. For example, the symbol adjacent to the time interval may be the previous symbol adjacent to the time interval or the next symbol adjacent to the time interval. In other words, in case 1, the time interval is one OFDM symbol, and the type 2C dynamic channel access procedure is applied, so idle sensing is not required between S-SSBs.

[0112] According to the position of the sensing interval in the time interval, case 1 may further include case 1-A and case 1-B. In case 1-A, the sensing interval is located immediately after the previous symbol adjacent to the time interval. In case 1-B, the sensing interval is located immediately before the next symbol adjacent to the time interval.

[0113] Figure 5 An exemplary time domain structure of the time interval between two adjacent S-SSBs according to some embodiments of the present application is described. Specifically, Figure 5 Two exemplary time-domain structures of the time intervals in Case 1-A and Case 1-B are shown.

[0114] exist Figure 5 In the two cases 1-A and 1-B, the length of the time interval is one symbol, and the length of the sensing interval (e.g., denoted as T SI ) is no more than 16μs, that is, 0≤T SI ≤16μs.

[0115] for Figure 5 In case 1-A, the time interval contains a complete or partial copy of the next symbol adjacent to the time interval. For example, the next symbol may carry PSBCH or SLSS. The sensing interval is positioned immediately after the previous symbol adjacent to the time interval. That is, the sensing interval is located at the beginning of the time interval.

[0116] for Figure 5In case 1-B, the time interval contains a complete or partial copy of the next symbol adjacent to the time interval. For example, the next symbol may carry PSBCH or SLSS. The sensing interval is positioned immediately before the next symbol adjacent to the time interval. That is, the sensing interval is located at the end of the time interval.

[0117] In case 2, the content used for padding in the time interval is the extension of the CP of the first symbol in the S-SSB opportunity next to the time interval (which is called CPE). The length of the sensing interval (e.g., denoted as T SI ) can be 0≤T SI ≤16μs, T SI =16μs or T SI ≥ 25 μs, which corresponds to LBT Type 2C, LBT Type 2B or LBT Type 2A, respectively. For a given length of a time interval (e.g., denoted as T TI-S-SSB ), the length of the CPE (e.g., T CPE ) can be used to obtain the desired sensing interval T based on the following equation (1): SI :

[0118] T TI-S-SSB = T SI + T CPE . (1)

[0119] Therefore, Case 2 can be applied to Type 2A dynamic channel access procedure, Type 2B dynamic channel access procedure and Type 2C dynamic channel access procedure.

[0120] According to the position of the sensing interval in the time interval, case 2 may further include case 2-A and case 2-B. In case 2-A, the sensing interval is located immediately after the previous symbol adjacent to the time interval. In case 2-B, the sensing interval is located immediately before the next symbol adjacent to the time interval.

[0121] Figure 6 An exemplary time domain structure of the time interval between two adjacent S-SSBs according to some embodiments of the present application is described. Specifically, Figure 6 Two exemplary time-domain structures of the time intervals in Case 2-A and Case 2-B are shown.

[0122] exist Figure 6 In the example of , for both cases 2-A and 2-B, the length of the time interval is a symbol, and as stated above, the length of the sensing interval (e.g., denoted as T ) is determined based on the LBT type (e.g., LBT Type 2C, LBT Type 2B, or LBT Type 2A). SI ).

[0123] for Figure 6In case 2-A, the time interval contains the CPE of the first symbol in the S-SSB opportunity next to the time interval, where the length of the CPE is denoted by T CPE For example, the first symbol in the next S-SSB opportunity may carry PSBCH or SLSS. The sensing interval is positioned immediately after the previous symbol adjacent to the time interval. That is, the sensing interval is located at the beginning of the time interval.

[0124] for Figure 6 In case 2-B, the time interval contains the CPE of the first symbol in the S-SSB opportunity next to the time interval, where the length of the CPE is denoted by T CPE For example, the first symbol in the next S-SSB opportunity may carry PSBCH or SLSS. The sensing interval is positioned immediately before the next symbol adjacent to the time interval (ie, the first symbol in the next S-SSB opportunity). That is, the sensing interval is located at the end of the time interval.

[0125] After obtaining the first configuration, the UE may perform an LBT procedure associated with the S-SSB opportunity based on the first configuration in step 403. For example, for any S-SSB opportunity within the COT (except the first S-SSB opportunity within the COT), before transmitting the S-SSB on the S-SSB opportunity, the UE may perform the LBT procedure in a sensing interval within a time interval configured by the first configuration. In step 405, the UE may transmit the S-SSB on the S-SSB opportunity in response to the LBT procedure being successful.

[0126] In some embodiments, the sensing interval may be located before the content for filling in the time interval. Then, in step 403, the UE may perform the LBT procedure in the sensing interval within the time interval. In response to the LBT procedure being successful, the UE may transmit the content for filling to occupy the channel until the start boundary of the S-SSB opportunity. Then, in step 405, the UE may transmit the S-SSB on the S-SSB opportunity. Taking case 2-A as an example, in step 403, the UE may transmit the S-SSB on the S-SSB opportunity. SI Then, once the channel is determined to be idle (i.e., the LBT procedure is successful), the UE can perform idle sensing with T CPE The duration of the CPE (e.g., at T CPE The UE may transmit a S-SSB during the S-SSB opportunity.

[0127] In some embodiments, the sensing interval may be located after the content for filling in the time interval. Then, the UE may first transmit the content for filling, and then perform the LBT procedure in the sensing interval in step 403. In step 405, the UE may transmit the S-SSB on the S-SSB opportunity in response to the LBT procedure being successful. Taking case 2-B as an example, the UE may first transmit the content for filling by performing a LBT procedure with T CPE The duration of the CPE to occupy the channel (for example, at T CPE The UE may transmit the CPE during the duration of T SI In step 405, the UE may transmit an S-SSB on an S-SSB opportunity in response to the LBT procedure being successful.

[0128] The second configuration may be used to support LBT Type 2. For example, the second configuration may be used to support LBT Type 2 associated with a single S-SSB opportunity (e.g., before transmitting a single S-SSB). In another example, the second configuration may be used to support LBT Type 2 associated with a first S-SSB opportunity within a COT (e.g., before transmitting the first S-SSB within the COT). That is, the second configuration may be used to initiate COT-based S-SSB transmission.

[0129] To support LBT Type 2, the length of the sensing interval for performing LBT (e.g., denoted as T SI ) may be determined by the LBT type (e.g., Type 2A, Type 2B, or Type 2C). For example, in the case of a Type 2A dynamic channel access procedure, T SI ≥25μs; In case of type 2B dynamic channel access procedure, T SI =16μs; in case of type 2C dynamic channel access procedure, 0≤T SI ≤16μs. In view of this, the LBT type can be indicated by the second configuration.

[0130] In order to ensure that the UE transmits the S-SSB from the start boundary of the S-SSB opportunity, the second configuration may also indicate information for calculating the length of the CPE before transmitting the S-SSB. For example, the CPE may be an extension of the CP of the first symbol in the S-SSB opportunity performing LBT type 2. In some embodiments of the present application, the length of the CPE may be set based on the priority of the synchronization reference of the UE.

[0131] In addition, if the second configuration is used to enable COT-based S-SSB transmission, the MCOT for S-SSB may also be indicated by the second configuration.

[0132] In view of the above, the second configuration may include at least one of the following: LBT type; a length for calculating the CPE (for example, represented as T CPE ) of the time unit (for example, represented by T UT ); The number of time units used to calculate the length of the CPE (e.g., represented by N UT ) and the priority of the synchronization reference; or MCOT for S-SSB.

[0133] As stated above, the LBT type may be a Type 2A, Type 2B, or Type 2C dynamic channel access procedure, which is used to determine the sensing interval for performing the LBT procedure.

[0134] The MCOT for S-SSB may be defined as the maximum number of S-SSBs to be transmitted within one COT, or as the maximum channel occupancy time for continuous S-SSB transmissions.

[0135] To set T CPE The principle is that the higher the priority of the synchronization reference, the higher the T CPE That is, the principle can provide an earlier channel access opportunity to a synchronization reference with a higher priority.

[0136] There are four basic synchronization references from which a UE can derive its own synchronization, namely the Global Navigation Satellite System (GNSS), its serving BS (e.g., eNB or gNB), another UE transmitting SLSS (e.g., which is called SyncRef UE), or its own internal clock. In general, the GNSS or BS is considered to be the highest quality source. SyncRef UEs are distinguished as UEs synchronized directly with the GNSS or BS, UEs one step away from the GNSS or BS, and UEs ≥ 2 other steps away 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 SLSS. The priority order of synchronization references is as follows, the details are specified in TS 36.331, where "Level 1" to "Level 5" are the priorities of the synchronization references from highest to lowest.

[0137] Level 1: Synchronization reference is GNSS or BS, depending on configuration or pre-configuration.

[0138] • Level 2: The synchronization reference is the SyncRef UE that is directly synchronized to the Level 1 source.

[0139] Level 3: The synchronization reference is the SyncRef UE synchronized to a Level 2 source, i.e. indirectly synchronized to a Level 1 source.

[0140] • Level 4: The synchronization reference is any other SyncRef UE.

[0141] Level 5: UE's internal clock.

[0142] In some embodiments of the present application, the length of the CPE can be determined by the following equation (2):

[0143] T CPE = N UT * T UT (2)

[0144] In some examples, T UT = 9 μs. The number of time units “N” in the above equation is UT " can be determined based on a mapping between the number of time units used to calculate the length of the CPE and the priority of the synchronization reference. According to some embodiments of the present application, a higher priority of the synchronization reference is mapped to the number of time units associated with a longer CPE, thereby achieving a higher priority of the synchronization reference, T CPE The longer the principle.

[0145] Then, once the UE determines its synchronization reference, the priority of the synchronization reference is determined. Based on the mapping included in the second configuration, the number of time units corresponding to the priority "N" is determined. UT ”.

[0146] Table 4 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.

[0147] Table 4

[0148] <![CDATA[CPE(N UT )]]> Priority of synchronization references 4 Level 1 3 Level 2 2 Level 3 1 Level 4 0 Level 5

[0149] For example, in the case where the priority of the synchronization reference is level 2, according to Table 4, the number of time units "N UT ” is 3. Based on equation (2), the UE can determine T CPE =27μs.

[0150] After obtaining the second configuration, in step 403, the UE may perform LBT type 2 associated with the S-SSB opportunity based on the second configuration. For example, based on the second configuration, the UE may determine the length of the sensing interval, i.e., T SI , and the length of CPE, i.e. T CPE Then, the UE may perform the LBT procedure associated with the S-SSB opportunity (i.e., LBT type 2) within the sensing interval, where the earliest starting point of the LBT procedure is T relative to the starting boundary of the S-SSB opportunity. SI +T CPEIn response to the LBT procedure being successful, the UE may transmit the CPE to occupy the channel until the start boundary of the S-SSB opportunity. In step 405, the UE may transmit the S-SSB on the S-SSB opportunity.

[0151] Figure 7 An exemplary time domain structure for performing LBT Type 2 according to some embodiments of the present application is described.

[0152] refer to Figure 7 , when the UE intends to transmit S-SSB at the S-SSB opportunity, the UE may perform LBT Type 2 before the S-SSB opportunity.

[0153] Based on the LBT type indicated by the second configuration, the UE may determine the length of the sensing interval, ie, T SI The length of the CPE (ie, T CPE ). That is, relative to the start boundary of the S-SSB opportunity, the earliest start point of UE occupying the channel is T CPE The UE may then perform an LBT procedure associated with an S-SSB opportunity (i.e., LBT Type 2) within the sensing interval, where the earliest starting point for idle sensing is T relative to the start boundary of the S-SSB opportunity. SI +T CPE In response to the LBT procedure being successful, the UE may transmit the CPE to occupy the channel until the start boundary of the S-SSB opportunity. Figure 7 In the example of , CPE is an extension of the CP of the first symbol in the S-SSB opportunity. The UE may then transmit the S-SSB on the S-SSB opportunity.

[0154] The third configuration may be used to support LBT Type 1. For example, the third configuration may be used to support LBT Type 1 associated with the first S-SSB opportunity within the COT (e.g., before the first S-SSB is transmitted within the COT). That is, the third configuration may be used to initiate COT-based S-SSB transmission.

[0155] In order to support LBT type 1, the LBT type may be indicated by the third configuration. In addition, since the third configuration is used to enable COT-based S-SSB transmission, the MCOT for S-SSB may also be indicated by the third configuration.

[0156] As stated in the above embodiments, for LBT Type 1, the length of the sensing interval (e.g., denoted as T SI). In some embodiments of the present application, the CAPC value may be determined based on at least one of the following: the priority of the UE's synchronization reference or the length of the COT for S-SSB. The length of the COT for S-SSB may be defined as the number of S-SSBs (or S-SSB opportunities) to be transmitted within the COT, or as the channel occupancy time for consecutive S-SSB transmissions in the COT. The length of the COT for SSB is constrained by the MCOT (e.g., less than or equal to the MCOT) and may be determined by the strength used by the UE for S-SSB transmission.

[0157] In view of the above, the third configuration may include at least one of: LBT type; a first mapping between CAPC value and priority of synchronization reference; a second mapping between CAPC value and length of COT for S-SSB; or MCOT for S-SSB.

[0158] The LBT type in the third configuration may be set to LBT type 1. The MCOT for S-SSB may be defined as the maximum number of S-SSBs to be transmitted within one COT, or as the maximum channel occupancy time for continuous S-SSB transmissions.

[0159] In some embodiments of the present application, one principle of mapping between CAPC values ​​and priorities of synchronization references is to provide earlier channel access opportunities for synchronization references with higher priorities. In order to implement the above principle, higher priorities of synchronization references can be mapped to smaller CAPC values. Based on Table 1 or Table 2, smaller CAPC values ​​can correspond to shorter sensing intervals, thereby providing earlier channel access opportunities.

[0160] Table 5 below shows an exemplary mapping between CAPC values ​​(eg, p) and priorities of synchronization references.

[0161] Table 5

[0162] CAPC(p) Priority of synchronization references 1 Level 1 2 Level 2 2 Level 3 3 Level 4 4 Level 5

[0163] For example, in the case where the priority of the synchronization reference is level 2, according to Table 5, the corresponding CAPC value is 2. Based on the CAPC value, the UE may determine the length of the sensing interval based on Table 1 or Table 2.

[0164] In some embodiments of the present application, one principle of mapping between the CAPC value and the length of the COT for S-SSB is to provide an earlier channel access opportunity for a COT with a shorter length (e.g., a smaller number of S-SSBs in the COT). In order to achieve the above principle, a COT with a shorter length for S-SSB (e.g., a COT with a smaller number of S-SSBs) is mapped to a smaller CAPC value. Based on Table 1 or Table 2, a smaller CAPC value may correspond to a shorter sensing interval, thereby providing an earlier channel access opportunity.

[0165] Table 6 below shows an exemplary mapping between CAPC values ​​(eg, p) and the length of the COT for S-SSBs, which is defined as the number of S-SSBs within the COT (ie, j).

[0166] Table 6

[0167] CAPC(p) Length of COT for S-SSB (j) 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 ]]]>

[0168] Referring to Table 6, 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 the COT has 3 S-SSBs (which is within the value range of the second row of Table 6 (e.g., j=[2,3,4])), the corresponding CAPC value is 2. Based on the CAPC value, the UE can determine the length of the sensing interval based on Table 1 or Table 2.

[0169] After obtaining the third configuration, in step 403, the UE may perform LBT type 1 associated with the S-SSB opportunity based on the third configuration. For example, based on the third configuration, the UE may determine a CAPC value, i.e., p. Then, the UE may perform LBT type 1 associated with the S-SSB opportunity within a sensing interval based on the CAPC value. In the case where there is a gap between the end of the sensing interval and the start boundary of the S-SSB opportunity, the UE may transmit CPE to occupy the channel until the start boundary of the S-SSB opportunity in response to the success of the LBT procedure. In step 405, the UE may transmit the S-SSB on the S-SSB opportunity. In the case where there is no gap between the end of the sensing interval and the start boundary of the S-SSB opportunity, the UE may transmit the S-SSB on the S-SSB opportunity in response to the success of the LBT type 1.

[0170] Figure 8 An exemplary time domain structure for performing LBT Type 1 according to some embodiments of the present application is described.

[0171] refer to Figure 8, when the UE intends to transmit an S-SSB at an S-SSB opportunity, the UE may perform LBT Type 1 before the S-SSB opportunity.

[0172] Based on the third configuration, the UE may determine the CAPC value as stated above. The UE may perform an LBT procedure associated with the S-SSB opportunity (i.e., LBT Type 1) in the sensing interval based on the CAPC value. In response to the LBT procedure being successful, the UE may transmit the CPE to occupy the channel until the start boundary of the S-SSB opportunity. Figure 8 In the example of , the CPE is an extension of the CP of the first symbol in the S-SSB opportunity. The UE may then initiate a S-SSB transmission based on the COT. For example, the UE may transmit an S-SSB (e.g., the first S-SSB in the COT) on the S-SSB opportunity.

[0173] According to some embodiments of the present application, the configuration information obtained in step 401 may also include at least one of the following: the maximum number of S-SSBs to be transmitted by the UE in one S-SSB period; or the maximum number of S-SSBs to be transmitted by the UE in one S-SSB window. This type of information can be used to define the number of S-SSBs that the UE can transmit in one S-SSB period or one S-SSB window, and thus the S-SSBs in one S-SSB period or one S-SSB window can support the transmission of one or more UEs.

[0174] Fig. 9 An exemplary distribution of S-SSB opportunities within an S-SSB period including multiple S-SSB windows according to some embodiments of the present application is described.

[0175] refer to Fig. 9 , in the S-SSB period, N1 S-SSB windows are included, which are S-SSB window #0, S-SSB window #1, ..., S-SSB window #N1-1. In each S-SSB window, N2 S-SSB opportunities are included, which are S-SSB opportunity #0, S-SSB opportunity #1, ..., S-SSB opportunity #N2-1. In each S-SSB window, a time interval (e.g., expressed as TI-S-SSB) is located between two adjacent S-SSB opportunities. For example, the structure of the time interval can be determined based on the first configuration described above. The length of the S-SSB period is marked as "period". The duration from the start time slot of the S-SSB period to the start time slot of S-SSB window #0 is marked as "offset". The interval between two adjacent S-SSB windows (e.g., from the start time slot of S-SSB window #0 to the start time slot of S-SSB window #1) is marked as "interval".

[0176] Fig.10A simplified block diagram illustrating an exemplary apparatus 1000 for S-SSB transmission in unlicensed spectrum according to some embodiments of the present application. In some embodiments, the apparatus 1000 may be or include a UE (e.g., Figure 1 In some other embodiments, the device 1000 may be or include a BS (e.g., Figure 1 At least a portion of BS102).

[0177] refer to Fig.10 , the apparatus 1000 may include at least one transmitter 1002, at least one receiver 1004, and at least one processor 1006. The at least one transmitter 1002 is coupled to the at least one processor 1006, and the at least one receiver 1004 is coupled to the at least one processor 1006.

[0178] Although in this figure, elements such as transmitter 1002, receiver 1004, and processor 1006 are illustrated in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, transmitter 1002 and receiver 1004 may be combined into one device, such as a transceiver. In some embodiments of the present application, apparatus 1000 may further include an input device, a memory, and / or other components. Transmitter 1002, receiver 1004, and processor 1006 may be configured to perform any of the methods described herein (e.g., regarding Figures 4 to 9 any of the methods described in ).

[0179] According to some embodiments of the present application, the device 1000 may be a UE, and the transmitter 1002, the receiver 1004, and the processor 1006 may be configured to perform the Figures 4 to 9 Operations of the method performed by the UE as described in any one of . For example, the processor 1006 may be configured to: obtain configuration information for S-SSB in unlicensed spectrum based on configuration or pre-configuration, wherein the configuration information includes at least one of the following: a first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT; a second configuration for performing LBT type 2; or a third configuration for performing LBT type 1; perform an LBT procedure associated with the S-SSB opportunity based on the configuration information. The transmitter 1002 may be configured to transmit an S-SSB on the S-SSB opportunity in response to the LBT procedure being successful.

[0180] According to some embodiments of the present application, the device 1000 may be a BS, and the transmitter 1002, the receiver 1004, and the processor 1006 may be configured to perform the operations described in any Figures 4 to 9Operations of the described method performed by the BS. For example, the transmitter 1002 may be configured to transmit configuration information for S-SSB in an unlicensed spectrum, wherein the configuration information includes at least one of: a first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same COT; a second configuration for performing LBT Type 2; or a third configuration for performing LBT Type 1.

[0181] In some embodiments of the present application, the device 1000 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may store thereon computer-executable instructions to enable the processor 1006 to implement any of the methods described above. For example, when the computer-executable instructions are executed, the processor 1006 may interact with the transmitter 1002 and / or the receiver 1004 to perform, for example, Figures 4 to 9 Describe the operation of the method.

[0182] The method according to the embodiments of the present application may also be implemented on a programmed processor. However, the controller, flow chart and module may also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit (such as a discrete element circuit), a programmable logic device or the like. In general, any device on which a finite state machine capable of implementing the flow chart shown in the figure resides can be used to implement the processor functions of the present application. For example, an embodiment of the present application provides an apparatus for S-SSB transmission in an unlicensed spectrum, comprising a processor and a memory. Computer programmable instructions for implementing the 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 the 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.

[0183] 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.

[0184] Although the present application has been described with specific embodiments of the present application, it is apparent that many substitutions, modifications and variations may be apparent to those skilled in the art. For example, in other embodiments, the various components of the embodiments may be interchangeable, added or replaced. In addition, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the art of the disclosed embodiments to make and use the teachings of the present application by simply adopting the elements of the independent claims. Therefore, the embodiments of the present application set forth herein are intended to be illustrative, rather than 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 at least one of the following: A first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same channel occupancy time COT; A second configuration for performing listen-before-talk LBT type 2; or A third configuration for performing LBT Type 1; and performing an LBT procedure associated with the S-SSB opportunity based on the configuration information; a transmitter coupled to the processor and configured to transmit an S-SSB on the S-SSB opportunity in response to the LBT procedure being successful; and A receiver is coupled to the processor.

2. The UE of claim 1, wherein the configuration information is based on at least one of the following granularities: Bandwidth per channel, Per carrier, Per bandwidth portion, per frequency range, or Each subcarrier spacing SCS; or 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).

3. The UE according to claim 1, wherein the first configuration indicates at least one of the following: the length of the time interval; the position of the said time interval; or The construction of the time interval.

4. The UE according to claim 3, wherein the time interval occupies one or more orthogonal frequency division multiplexing (OFDM) symbols, and the number of OFDM symbols included in the time interval is determined based on the maximum length of the sensing interval for performing the LBT procedure and the SCS.

5. The UE according to claim 3, wherein the construction of the time interval includes at least one of the following: the length of the sensing interval for performing the LBT procedure, the location of the sensing interval, or the content for filling in the time interval.

6. The UE according to claim 5, wherein: The position of the sensing interval is immediately after a previous symbol adjacent to the time interval or immediately before a next symbol adjacent to the time interval; or The content used to fill in the time interval is a complete or partial copy of the symbol adjacent to the time interval, or a cyclic prefix extension CPE of the first symbol in the S-SSB opportunity next to the time interval.

7. The UE according to claim 1, wherein the second configuration indicates at least one of the following: LBT type; The time unit used to calculate the length of the cyclic prefix extension CPE; A mapping between the number of time units used to calculate the length of the CPE and the priority of the synchronization reference; or Maximum channel occupancy time MCOT for S-SSB.

8. The UE of claim 7, wherein a higher priority of a synchronization reference is mapped to the number of time units associated with a longer CPE.

9. The UE according to claim 1, wherein the third configuration indicates at least one of the following: LBT type; 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 the length of the COT for the S-SSB; or MCOT for S-SSB.

10. The UE of claim 9, wherein a higher priority of the synchronization reference is mapped to a smaller CAPC value.

11. The UE of claim 9, wherein a shorter length of the COT for the SSB is mapped to a smaller CAPC value.

12. The UE according to claim 7 or 9, wherein the MCOT for S-SSB is defined as a maximum number of S-SSBs to be transmitted within one COT, or is defined as a maximum channel occupancy time for continuous S-SSB transmission.

13. The UE according to claim 7 or 9, wherein the processor is configured to: performing the LBT procedure associated with the S-SSB opportunity in a sensing interval, wherein a length of the sensing interval is determined based on the LBT type; and Wherein the transmitter is further configured to transmit the CPE to occupy a channel until a starting boundary of the S-SSB opportunity in response to the LBT procedure being successful.

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: A first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same channel occupancy time COT; A second configuration for performing listen-before-talk LBT type 2; or A third configuration for performing LBT type 1; and 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 at least one of the following: A first configuration associated with a time interval between adjacent S-SSB opportunities sharing the same channel occupancy time COT; A second configuration for performing listen-before-talk LBT type 2; or A third configuration for performing LBT type 1; performing an LBT procedure associated with the S-SSB opportunity based on the configuration information; and and transmitting an S-SSB at the S-SSB opportunity in response to the LBT procedure being successful.

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