Method and apparatus for s-SSB transmission in unlicensed spectrum

Abstract

The present disclosure relates to a method and apparatus for sidelink synchronization signal block (S-SSB) transmission in unlicensed spectrum. One embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver; and a processor coupled with the transceiver and configured to receive, using the transceiver, configuration information for an S-SSB in an unlicensed spectrum, the configuration information including at least one of: a first configuration associated with an S-SSB structure, the configuration comprises at least one of a first structure configuration in a time domain, a second structure configuration in a frequency domain, or a configuration for a physical sidelink broadcast channel (PSBCH); or a second configuration associated with an S-SSB period comprising one or more S-SSB occasions; selecting at least one S-SSB opportunity based on the configuration information; and in response to a listen before talk (LBT) process associated with the at least one S-SSB occasion being successful, transmitting, using the transceiver, an S-SSB on the at least one S-SSB occasion.

Description

Technical Field

[0001] The present disclosure relates to wireless communication technology, 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 Third Generation Partnership Project (3GPP). It enables direct communication between nearby user equipment (UEs), without the data passing through a base station (BS) or core network. A sidelink communication system has been introduced in 3GPP 5G wireless communication technology, where a direct link between two UEs is called a sidelink.

[0003] Sidelink synchronization information is carried in SL SSB (S-SSB). In unlicensed spectrum, S-SSB transmissions need to meet several requirements, such as occupied channel bandwidth (OCB) requirements and listen-before-talk (LBT) requirements. Therefore, a novel design for S-SSB transmissions in unlicensed spectrum is needed. Summary of the Invention

[0004] One embodiment of the present disclosure provides a UE, comprising: a transceiver; and a processor, coupled to the transceiver and configured to: use the transceiver to receive configuration information for S-SSB in an unlicensed spectrum, comprising at least one of the following: a first configuration associated with an S-SSB structure, comprising at least one of the following: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for a physical sidelink broadcast channel (PSBCH); or a second configuration associated with an S-SSB period comprising one or more S-SSB opportunities; select at least one S-SSB opportunity based on the configuration information; and in response to a listen-before-talk (LBT) procedure associated with the at least one S-SSB opportunity being successful, use the transceiver to transmit an S-SSB on the at least one S-SSB opportunity.

[0005] In some embodiments, 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).

[0006] In some embodiments, the configuration information is received 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).

[0007] In some embodiments, the first structural configuration in the time domain includes at least one of the following: the number of symbols as gaps for performing the LBT process in an S-SSB slot, or the position of the symbols in the S-SSB slot.

[0008] In some embodiments, the second structural configuration in the frequency domain includes at least one of: the number of S-SSB repetitions in the frequency band; the position of the S-SSB repetitions in the frequency band; the number of resource blocks (RBs) in the frequency band not occupied by the S-SSB repetitions; or the position of the RBs in the frequency band.

[0009] In some embodiments, the second structural configuration in the frequency domain includes at least one of: an interleaving pattern in a frequency band; an index of available interleavings in the frequency band; the number of interleavings of one S-SSB; or an indicator indicating whether frequency domain multiplexing (FDM) is enabled.

[0010] In some embodiments, the processor is further configured to: select an interlace for transmitting the S-SSB from the available interlaces based at least in part on the second structural configuration in the frequency domain; and map the S-SSB to be transmitted to the RB set of the selected interlace.

[0011] In some embodiments, if the indicator indicates that FDM is not enabled, the processor is further configured to: select the interlace for transmitting the S-SSB based on random selection; or select the first one or more interlaces for transmitting the S-SSB from the available interlaces.

[0012] In some embodiments, where the indicator indicates that FDM is enabled, the processor is further configured to: select the interlace for transmitting the S-SSB based on at least one of: random selection, an identifier of the UE, an identifier of a sidelink synchronization signal (SLSS) associated with the UE, or a priority level of a synchronization reference of the UE.

[0013] In some embodiments, the configuration indication PSBCH for the PSBCH includes at least one of: a first indicator indicating whether the S-SSB including the PSBCH is within a channel occupancy time (COT); a second indicator indicating whether the next S-SSB is within the current COT; a parameter associated with a quasi co-location (QCL) relationship; or a third indicator indicating whether the beam is used for repeated transmission of an S-SSB within an S-SSB window.

[0014] In some embodiments, the second configuration includes at least one of: the length of the S-SSB cycle; the number of S-SSB windows within the S-SSB cycle; the number of S-SSB opportunities within each S-SSB window; an offset from the start time slot of the S-SSB cycle to the start time slot of the first S-SSB window within the S-SSB window within the S-SSB cycle; an interval between the start time slots of two adjacent S-SSB windows; an indicator indicating whether each S-SSB window is a type 1 window, a type 2 window, or a type 3 window; or an LBT process type.

[0015] In some embodiments, the number of S-SSB opportunities within each S-SSB window is determined based on at least one of: a channel access procedure associated with the S-SSB; a configuration of beam-based sidelink transmissions; or a frequency band associated with the S-SSB.

[0016] Another embodiment of the present disclosure provides a BS comprising: a transceiver; and a processor coupled to the transceiver and configured to: use the transceiver to transmit configuration information for S-SSB in an unlicensed spectrum, comprising at least one of: a first configuration associated with an S-SSB structure, comprising at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for PSBCH; or a second configuration associated with an S-SSB period comprising one or more S-SSB opportunities.

[0017] In some embodiments, 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.

[0018] In some embodiments, the configuration information is transmitted via at least one of: a MIB message, a SIB message, RRC signaling, or a MAC CE.

[0019] In some embodiments, the first structural configuration in the time domain includes at least one of the following: the number of symbols as gaps for performing the LBT process in an S-SSB slot, or the position of the symbols in the S-SSB slot.

[0020] In some embodiments, the second structural configuration in the frequency domain includes at least one of: the number of S-SSB repetitions in the frequency band; the position of the S-SSB repetitions in the frequency band; the number of RBs in the frequency band not occupied by the S-SSB repetitions; or the position of the RBs in the frequency band.

[0021] In some embodiments, the second structure configuration in the frequency domain includes at least one of: an interleaving pattern in a frequency band; an index of an available interleaving in the frequency band; the number of interleavings used for one S-SSB; or an indicator indicating whether FDM is enabled.

[0022] In some embodiments, the configuration indication for the PSBCH includes at least one of: a first indicator indicating whether the S-SSB including the PSBCH is within the COT; a second indicator indicating whether the next S-SSB is within the current COT; a parameter associated with the QCL relationship; or a third indicator indicating whether the beam is used for repeated transmission of S-SSBs within the S-SSB window.

[0023] In some embodiments, the second configuration includes at least one of: the length of the S-SSB cycle; the number of S-SSB windows within the S-SSB cycle; the number of S-SSB opportunities within each S-SSB window; an offset from the start time slot of the S-SSB cycle to the start time slot of the first S-SSB window within the S-SSB window within the S-SSB cycle; an interval between the start time slots of two adjacent S-SSB windows; an indicator indicating whether each S-SSB window is a type 1 window, a type 2 window, or a type 3 window; or an LBT process type.

[0024] In some embodiments, the number of S-SSB opportunities within each S-SSB window is determined based on at least one of: a channel access procedure associated with the S-SSB; a configuration of beam-based sidelink transmissions; or a frequency band associated with the S-SSB.

[0025] Another embodiment of the present disclosure provides a method performed by a UE, comprising: receiving configuration information for S-SSB in an unlicensed spectrum, the configuration information including at least one of: a first configuration associated with an S-SSB structure, which includes at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for PSBCH; or a second configuration associated with an S-SSB period including one or more S-SSB opportunities; selecting at least one S-SSB opportunity based on the configuration information; and transmitting an S-SSB on the at least one S-SSB opportunity in response to a success of an LBT process associated with the at least one S-SSB opportunity.

[0026] Another embodiment of the present disclosure provides a method performed by a BS, comprising: transmitting configuration information for S-SSB in an unlicensed spectrum, the configuration information including at least one of the following: a first configuration associated with an S-SSB structure, which includes at least one of the following: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for PSBCH; or a second configuration associated with an S-SSB period including one or more S-SSB opportunities. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To illustrate 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 application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered limiting of its scope.

[0028] Figure 1 An exemplary wireless communication system according to some embodiments of the present disclosure is described.

[0029] Figure 2 Exemplary S-SSB time slots according to some embodiments of the present disclosure are described.

[0030] Figure 3 An exemplary distribution of opportunities for S-SSB according to some embodiments of the present disclosure is described.

[0031] Figure 4 An exemplary S-SSB structure in the time domain according to some embodiments of the present disclosure is described.

[0032] Figure 5A An exemplary repetition structure for S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0033] Figure 5B Another exemplary repetition structure for S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0034] Figure 6 An exemplary interleaving structure of S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0035] Figure 7 An exemplary distribution of S-SSB opportunities within an S-SSB cycle according to some embodiments of the present disclosure is described.

[0036] Figure 8 Another exemplary distribution of S-SSB opportunities within one S-SSB cycle according to some embodiments of the present disclosure is described.

[0037] Figure 9A flow chart illustrating an exemplary method for S-SSB transmission in unlicensed spectrum according to some embodiments of the present disclosure.

[0038] Figure 10 A simplified block diagram illustrating an exemplary apparatus for S-SSB transmission in unlicensed spectrum in accordance with some embodiments of the present disclosure. DETAILED DESCRIPTION

[0039] The detailed description of the accompanying drawings is intended as a description of the presently preferred embodiments of the present invention and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be implemented by different embodiments intended to be encompassed within the spirit and scope of the present invention.

[0040] Although operations are depicted in a particular order in the figures, those skilled in the art will readily recognize that such operations need not be performed in the particular order or sequential order as shown, or that all illustrated operations need not be performed to achieve a desired result; one or more operations may sometimes be omitted. Furthermore, the figures 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 certain circumstances, multitasking and parallel processing may be advantageous.

[0041] Reference will now be made in detail to certain embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, the embodiments are provided in the context of specific network architectures and new service scenarios, such as 3GPP 5G New Radio (NR), 3GPP LTE, etc. It is contemplated that as network architectures and new service scenarios evolve, all embodiments of the present disclosure will also be applicable to similar technical issues. Furthermore, the terminology used in the present disclosure may be modified without affecting the principles of the present disclosure.

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

[0043] like Figure 1 As illustrated in FIG, a 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. Although 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 the 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 security cameras), an in-vehicle computer, a network device (e.g., a router, a switch, and a modem), etc.

[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 identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals over a wireless network.

[0046] According to some other embodiments of the present disclosure, UE 101 includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, etc.

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

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

[0049] In a sidelink communication system, a transmitting UE may also be referred to as a transmitting UE, Tx UE, sidelink Tx UE, sidelink transmitting UE, etc. A receiving UE may also be referred to as a receiving UE, Rx UE, sidelink Rx UE, sidelink receiving UE, etc.

[0050] according to Figure 1 In some embodiments, UE 101a serves as a Tx UE and UE 101b serves as a Rx UE. UE 101a may exchange sidelink messages with UE 101b via a sidelink, for example, via a PC5 interface as defined in 3GPP TS 23.303. 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 a multicast group (e.g., a group of UEs) via a sidelink multicast transmission session. Figure 1In 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 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.

[0052] In some embodiments of the present disclosure, UE 101a may communicate with UE 101b on a licensed spectrum, while in other embodiments, UE 101a may communicate with UE 101b on an unlicensed spectrum.

[0053] Figure 1 In the embodiments of the present invention, both UE 101a and UE 101b can transmit information to BS 102 and receive control information from BS 102, for example, via an LTE or NR Uu interface. BS 102 can be distributed over a geographical area. In certain embodiments of the present disclosure, each of BSs 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 radio access network, which may include one or more controllers communicatively coupled to one or more corresponding BSs 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 may be compatible with wireless communication networks, cellular telephone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3GPP-based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, 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 on the downlink (DL) using an orthogonal frequency division multiplexing (OFDM) modulation scheme, and the UE 101 transmits data on the uplink (UL) using a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix OFDM (CP-OFDM) scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0056] In some embodiments of the present disclosure, BS 102 may communicate using other communication protocols (e.g., the IEEE 802.11 wireless communication protocol family). Furthermore, in some embodiments of the present disclosure, BS 102 may communicate over a licensed spectrum, while in other embodiments, BS 102 may communicate over an unlicensed spectrum. The present disclosure is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In still other embodiments of the present disclosure, BS 102 may communicate with UE 101 using 3GPP 5G protocols.

[0057] The sidelink synchronization information is carried in the S-SSB, which consists of the 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.

[0058] refer to Figure 2 , S-SSB occupies one time slot in the time domain and 11 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 , an S-SSB slot may include a total of 14 OFDM symbols (e.g., symbol #0 to symbol #13). The S-PSS is repeatedly transmitted on the second and third symbols (e.g., symbol #1 and symbol #2) in the S-SSB slot. The S-SSS is repeatedly transmitted on the fourth and fifth symbols (e.g., symbol #3 and symbol #4) in the S-SSB slot. The S-PSS and S-SSS occupy 127 subcarriers in the frequency domain, from the third subcarrier to the 129th subcarrier relative to the beginning of the S-SSB bandwidth.

[0059] The S-PSS and S-SSS are collectively referred to as the Sidelink Synchronization Signal (SLSS). The SLSS is used for time and frequency synchronization. By detecting the SLSS sent by a synchronization reference UE (also called a SyncRef UE), a UE can synchronize to the SyncRef UE and estimate the start of the frame and carrier frequency offset.

[0060] The S-PSS can be generated from a maximum length sequence (m-sequence) using the same design (i.e., generator polynomial, initialization value, cyclic shift, etc.) as that used to generate the m-sequence in the primary synchronization signal (PSS) in 3GPP documents. In NR Uu, there are three candidate sequences for the PSS. However, only two candidate sequences are used for the S-PSS.

[0061] The S-SSS can be generated from a golden sequence using the same design (i.e., generator polynomial, initialization value, cyclic shift, etc.) as that used to generate the golden sequence for the Secondary Synchronization Signal (SSS) in the 3GPP document. This results in 336 candidate sequences for the S-SSS, just like the SSS in NR Uu.

[0062] For the transmission of SLSS within S-SSB, SyncRef The UE can select S-PSS and S-SSS from candidate sequences based on the SLSS identifier (ID). SLSSID represents the identifier of the SyncRef UE and conveys the SyncRef UE priority, just like 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.

[0063] 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., symbols #5 to #12) following the S-SSS in the S-SSB slot. When using an extended CP, the PSBCH is transmitted on the first symbol and six symbols following the S-SSS in the S-SSB slot. The PSBCH occupies 132 subcarriers in the frequency domain. The PSBCH in the first symbol of the S-SSB slot is used for automatic gain control (AGC). The last symbol (e.g., symbol #13) in the S-SSB slot is used as a guard symbol.

[0064] The UE may be configured with a configuration for an S-SSB period that includes one or more S-SSB opportunities. Figure 3 An exemplary distribution of opportunities for S-SSB according to some embodiments of the present disclosure is described.

[0065] like Figure 3 As shown in FIG, within one S-SSB cycle, 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 cycle is marked as "cycle". There is an offset from the start time slot of the S-SSB cycle to the first S-SSB opportunity (e.g., S-SSB#0) in the S-SSB cycle. 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 3As shown in FIG, the interval between S-SSB #N-3 and S-SSB #N-2 is labeled "interval." Therefore, the configuration for one S-SSB period may include at least one of the parameters "period," "offset," or "interval." The UE may select one or more SSB opportunities to transmit an SSB based on the configuration.

[0066] The S-SSB period may include 16 frames, for example, 160ms, as specified in NR V2X. The possible number of S-SSB opportunities within one S-SSB period is shown in Table 1 below:

[0067] Table 1 Number of S-SSB opportunities within an S-SSB period (160ms)

[0068]

[0069] Several issues need to be addressed for S-SSB transmissions in unlicensed spectrum. The first is how to meet the OCB requirement for large channel bandwidths in unlicensed spectrum. According to the OCB requirement, the bandwidth containing 99% of the signal's power should be between 80% and 100% of the declared nominal channel bandwidth. The second issue is how to meet the LBT requirement. The UE must perform the LBT procedure before S-SSB transmission.

[0070] The present disclosure provides various solutions for S-SSB transmission in unlicensed spectrum, which may address at least one of the above-mentioned problems.

[0071] Solution 1

[0072] In unlicensed spectrum, before performing any transmission, a device (e.g., UE) needs to perform a LBT procedure. The present disclosure proposes to introduce a gap in the S-SSB slot structure for the channel access procedure with LBT. The gap may contain a certain number of symbols, where the number (which may be referred to as ) may depend on the SCS.

[0073] For shorter SCS (e.g., 15kHz or 30kHz), the number of symbols in the gap may include one symbol. Figure 2 The guard symbol including one symbol shown in can be used as a gap for the channel access process. In some other embodiments, any one of the 14 symbols in the S-SSB slot can be used as a gap for the channel access process.

[0074] For longer SCS (e.g., 60kHz or 120kHz), the number of symbols in the gap may include more than one symbol. Figure 2The one-symbol guard symbol shown in FIG and one or more symbols preceding the guard symbol (e.g., symbol #12, symbol #11, etc.) may be used as a gap for the channel access process. In some other embodiments, other symbols among the 14 symbols in the S-SSB slot may be used as gaps for the channel access process. For example, assuming that three symbols are required to perform a channel access process with LBT, symbols #11, #12, and #13 may be used to perform the LBT process. Alternatively, other symbols (e.g., symbol #6, symbol #7, and symbol #8, or symbol #0, symbol #1, and symbol #2) may be used to perform the LBT process.

[0075] Figure 4 An exemplary S-SSB structure in the time domain according to some embodiments of the present disclosure is described.

[0076] exist Figure 4 Two S-SSB slots (e.g., slot #m-1 and slot #m) are illustrated in FIG. Each S-SSB slot includes 14 OFDM symbols and has the same Figure 2 , except that the last symbol in each S-SSB slot (e.g., symbol #13) is a gap for the channel access procedure. More specifically, the gap is used by the UE to perform a channel access procedure with LBT. For example, if the LBT procedure performed in symbol #13 of slot #m-1 is successful, a COT including slot #m can be initiated, and the UE can transmit an S-SSB in slot #m.

[0077] The BS or network may transmit gap configuration information to the UE, wherein the gap configuration information may include a structure configuration in the time domain, for example, an S-SSB slot format. The S-SSB slot format may include the number of symbols used as a gap for the channel access process (i.e., a gap for performing the LBT process), or the position of the symbol used as a gap for the channel access process. Figure 4 In the example, the configuration information of the gap may indicate that the number of symbols as gaps for the channel access process is 1, and the position of the symbol as the gap for the channel access process is symbol #13; or the configuration information of the gap may only indicate that the position of the symbol as the gap for the channel access process is symbol #13, which implies that the number of symbols as gaps for the channel access process is 1.

[0078] The granularity of the gap configuration information can be:

[0079] 1. Per-channel bandwidth: Configuration information can be different for different channel bandwidths;

[0080] 2. Per carrier: Configuration information can be different for different carriers;

[0081] 3. Per bandwidth portion: Configuration information may be different for different bandwidth portions;

[0082] 4. Each frequency range: For different frequency ranges, such as frequency range 1 (FR1), FR2, etc., the configuration information can be different, or

[0083] 5. Per SCS: For different SCSs, such as 15kHz, 30kHz, etc., the configuration information may be different.

[0084] Configuration information of the gap may be transmitted from the BS to the UE via MIB messages, SIB messages, RRC signaling, MAC CE, etc.

[0085] Solution 2

[0086] To meet OCT requirements, the present disclosure proposes transmitting S-SSB repetitions across the required channel bandwidth.

[0087] For example, assuming a frequency band (eg, a channel) includes several RBs in the frequency domain, which can be represented as And each S-SSB repetition contains RBs.

[0088] Can transmit in the frequency band S-SSB repeats. It can be calculated by the following equation (1) The maximum value of:

[0089]

[0090] There may be some unoccupied RBs in the frequency band. The number of unoccupied RBs can be calculated by the following equation (2) (which can be expressed as ):

[0091]

[0092] The location of unoccupied RBs may be deployed based on OCB requirements. For example, unoccupied RBs may be deployed at any of the following locations: near the center frequency of the band, at the edge of the band, at the beginning of the band, at the end of the band, between any two S-SSB repetitions, or at other locations.

[0093] exist Can be In the case of divisibility, there may be S-SSBs are repeated without any unoccupied RBs.

[0094] Can be no greater than Any number of S-SSB repetitions may satisfy the OCB requirement. For example, there may be only two S-SSB repetitions, and the frequency offset between the first RB (lowest in the frequency domain) of the first S-SSB repetition and the last RB (highest in the frequency domain) of the second S-SSB repetition is between 80% and 100% of the nominal channel bandwidth of the channel.

[0095] Figure 5A An exemplary repetition structure for S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0096] refer to Figure 5A , the bandwidth of the band is 20 MHz, its SCS is 15 kHz, and the number of RBs in the band is equal to 106, that is, The S-SSB slot indexed as #m (i.e., S-SSB#m) is repeatedly mapped within the frequency band. According to equation (1), the maximum number of S-SSB repetitions is calculated as follows:

[0097]

[0098] exist Figure 5A In the example, The number of unoccupied RBs is calculated according to equation (2) as follows:

[0099]

[0100] Furthermore, unoccupied RBs are configured to be deployed in the center frequency of the frequency band.

[0101] Based on the above, nine S-SSB repetitions (e.g., SSB#m_0 to SSB#m_8) of S-SSB#m are transmitted in the frequency band, where each S-SSB repetition includes 11 consecutive RBs, and seven unoccupied RBs are arranged in the center frequency of the frequency band, for example, between the fifth S-SSB repetition (e.g., SSB#m_4) and the sixth S-SSB repetition (e.g., SSB#m_5). Therefore, among the 106 RBs in the frequency band, the S-SSB repetitions and unoccupied RBs are as follows:

[0102] 1. The first S-SSB repetition, S-SSB#m_0, is transmitted from RB#0 to RB#10.

[0103] 2. The second S-SSB repetition, S-SSB#m_1, is transmitted from RB#11 to RB#21.

[0104] 3. The third S-SSB repetition, S-SSB#m_2, is transmitted from RB#22 to RB#32.

[0105] 4. The fourth S-SSB repetition, S-SSB#m_3, is transmitted from RB#33 to RB#43.

[0106] 5. The fifth S-SSB repetition, S-SSB#m_4, is transmitted from RB#44 to RB#54.

[0107] 6. The 7 unoccupied RBs are from RB#55 to RB#61.

[0108] 7. The sixth S-SSB repetition, S-SSB#m_5, is transmitted from RB#62 to RB#72.

[0109] 8. The seventh S-SSB repetition, S-SSB#m_6, is transmitted from RB#73 to RB#83.

[0110] 9. The eighth S-SSB repetition, S-SSB#m_7, is transmitted from RB#84 to RB#94, and

[0111] 10. The ninth S-SSB repetition, S-SSB#m_8, is transmitted from RB#95 to RB#105.

[0112] Use the above S-SSB repetition to meet the OCB requirements.

[0113] Figure 5B Another exemplary repetition structure for S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0114] Figure 5B In addition, a frequency band with a bandwidth of 20 MHz and an SCS of 15 kHz is described, and the number of RBs in the frequency band is equal to 106, that is, The S-SSB slot indexed as #m (i.e., S-SSB#m) is repeatedly mapped within the frequency band. Figure 5B In the example, The first S-SSB repetition (S-SSB#m_0) will be in the first RB of the band. The second S-SSB (S-SSB#m_1) will be transmitted in the last RB of the band. and the unoccupied RBs are configured to be deployed at the center of the band, for example, from RB#11 to RB#94. Using the above-mentioned S-SSB repetition, the OCB requirement is met.

[0115] The configuration information of the S-SSB repetition may include a structure configuration in the frequency domain, which may include at least one of the following parameters:

[0116] 1. Number of S-SSB repetitions in a band, e.g., for an exemplary Figure 5A , the number is 9, and for the exemplary Figure 5B , the number is 2;

[0117] 2. The location of the S-SSB repetition in the band, e.g. Figure 5A In the , the first S-SSB is repeated from RB#0 to RB#10;

[0118] 3. The number of RBs in the band that are not occupied by S-SSB duplication, e.g., for an exemplary Figure 5A , the number of unoccupied RBs is 7, and for the exemplary Figure 5B , the number of unoccupied RBs is 84; or

[0119] 4. The location of RBs (i.e., unoccupied RBs) in the frequency band, e.g. Figure 5A , the positions of RBs in the frequency band are from RB#55 to RB#61.

[0120] The granularity and transmission method of the configuration information of the S-SSB repetition are similar to the configuration information of the gap as described above, and the details are omitted here.

[0121] Solution 3

[0122] In some other embodiments, the frequency domain includes The frequency band of RBs is divided into several interlaces. For simplicity, the number of interlaces is represented as T, and every T-th RB belongs to the same interlace.

[0123] An interlace may contain a set of RBs. The maximum number of RBs in an interlace (which may be denoted as A for simplicity) may be calculated by the following equation (3):

[0124]

[0125] exist When divisible by T, the total number of RBs in each of the T interlaces is A; In the case where T is not divisible, some interlaces contain A RBs, while other interlaces contain A–1 RBs.

[0126] If the first interlace (interlace #0) includes A RBs, it may include the 1st RB, the Tth RB, the (2×T)th RB, ..., and the ((A–1)×T)th RB. If the mth interlace (interlace #m-1) includes A-1 RBs, it may include the mth RB, the (m+T)th RB, ..., and the (m+(A–2)×T)th RB.

[0127] Among the T interlaces, there may be some interlaces containing a number of RBs that is not less than the number of RBs of S-SSB, that is, These interlaces are considered as available interlaces, and one S-SSB can be mapped to the RB set (or subset) of the available interlaces through a one-to-one mapping. Some interlaces may contain fewer RBs than the number of RBs for S-SSBs, and these interlaces are considered as unavailable interlaces, where the number of RBs is insufficient to support the one-to-one mapping of S-SSBs. In some other embodiments, interlaces containing fewer RBs than the number of RBs for S-SSBs may also be considered as available interlaces for S-SSBs. For example, in the case where interlace #P contains P1 RBs, where P1 is less than The next available interlace (e.g., interlace #(P+1)) can then be used in conjunction with interlace #P to provide sufficient RBs to support a one-to-one mapping of the S-SSB. In this case, the S-SSB can be mapped to the RB set of interlace #P and a portion of the RB set of interlace #(P+1), and interlace #P is also considered an available interlace. In some other embodiments, some RBs of the S-SSB can be punctured, and the S-SSB with a reduced number of RBs can be mapped to an interlace with a smaller number of RBs than the standard number of RBs for an S-SSB (i.e., 11 RBs).

[0128] The interleaved configuration information may include a structure configuration in the frequency domain, which may include at least one of the following:

[0129] 1. The interleaving pattern in the frequency band, which may include the number of interlaces and the RB set for each interlace;

[0130] 2. The index of the available interlace in the band;

[0131] 3. The number of interlaces used for one S-SSB; or

[0132] 4. Indicator indicating whether FDM is enabled or disabled.

[0133] The granularity and transmission manner of the configuration information of the interlace are similar to the configuration information of the gap as described above, and the details are omitted here.

[0134] The UE may select an interlace from the available interlaces based on the above configuration information according to any of the following solutions:

[0135] Solution 3-1:

[0136] In this solution, FDM for multiple S-SSBs from different UEs is not supported. In other words, the indicator in the configuration information indicates that FDM is disabled. For the interlace pattern within the frequency band, the UE may first select one or more interlaces from the available interlaces for transmitting the S-SSBs. In some embodiments, the UE may select one or more interlaces based on random selection. In some other embodiments, the UE may first select one or more interlaces from the available interlaces, and the number of selected interlaces is determined to meet reliability requirements.

[0137] After selecting one or more available interlaces, the UE may map the S-SSBs to the RB sets of the selected interlaces. The UE may start with the interlace with the smallest index and map in ascending order of RB index until the largest RB index in the interlace, and then perform the same operation for other interlaces in ascending order of interlace index until all selected interlaces are completed.

[0138] Solution 3-2:

[0139] In this solution, FDM is supported for multiple S-SSBs from different UEs. In other words, the indicator in the configuration information indicates that FDM is enabled. That is, the available interlaces of the frequency band can be used by different UEs. For the interlace pattern within the frequency band, the UE may first select one or more interlaces from the available interlaces for transmitting the S-SSBs. In some embodiments, the UE may select one or more interlaces based on random selection. In some other embodiments, the UE may select several interlaces from the available interlaces based on the UE's identifier. For example, UE A may select an interlace with an index obtained by taking the number of available interlaces modulo UE A's ID, UE B may select an interlace with another index obtained by taking the number of available interlaces modulo UE B's ID, and so on. In still other embodiments, the UE may select several interlaces from the available interlaces based on the SLSS identifier associated with the UE. For example, UE A may select an interlace with an index obtained by taking the number of available interlaces modulo UE A's SLSSID, UE B may select an interlace with another index obtained by taking the number of available interlaces modulo UE B's SLSSID, and so on. In yet other embodiments, the UE may select several interlaces from the available interlaces based on the priority level of the UE's synchronization reference. For example, according to the 3GPP specification, five priority levels of synchronization reference are defined, i.e., level 1 to level 5. If the priority level of the UE's synchronization reference is level 1, the UE may select the first interlace, if the priority level of its synchronization reference is level 2, the UE may select the second interlace, and so on.

[0140] After selecting one or more available interlaces, the UE may map the S-SSBs to the RB sets of the selected interlaces. The UE may start with the interlace with the smallest index and map in ascending order of RB index until the largest RB index in the interlace, and then perform the same operation for other interlaces in ascending order of interlace index until all selected interlaces are completed.

[0141] Figure 6 An exemplary interleaving structure for S-SSB in the frequency domain according to some embodiments of the present disclosure is described.

[0142] Figure 6 Assume a frequency band with a bandwidth of 20 MHz and an SCS of 15 kHz, and the number of RBs in the frequency band is equal to 106, which includes RB#0, RB#1, ..., RB#105. Ten interlaces (e.g., interlace#0, interlace#1, ..., interlace#9) are included in the frequency band. Based on the above equation (3), the maximum number of RBs in the 10 interlaces is calculated as follows:

[0143]

[0144] From interlace #0 to interlace #5, each interlace contains 11 RBs. For example, interlace #0 includes 11 RBs: RB #0, RB #10, RB #20, ..., and RB #100; interlace #5 includes 11 RBs: RB #5, RB #15, RB #25, ..., and RB #105. From interlace #6 to interlace #9, each interlace contains (A-1) RBs, that is, 10 RBs. For example, interlace #6 includes 10 RBs: RB #6, RB #16, RB #26, ..., and RB #96; interlace #9 includes 10 RBs: RB #9, RB #19, RB #29, ..., and RB #99.

[0145] Each S-SSB spans (For example, 11) RBs. Since the number of RBs included in one S-SSB is 11, and each interlace from Interlace #0 to Interlace #5 includes 11 RBs, each RB of one S-SSB can be mapped to an RB in one of Interlaces #0 to #5. Therefore, Interlaces #0 to #5 are considered available interlaces. Each interlace from Interlace #6 to #9 includes 10 RBs and is not considered available interlaces.

[0146] The UE may select one or more interlaces from available interlace #0 to interlace #5 and map the RBs of the S-SSB to the RB set of the selected interlace.

[0147] Solution 4

[0148] In Solution 4, an S-SSB cycle may include several separate S-SSB windows, and an S-SSB window within an S-SSB cycle may include several S-SSB opportunities. The number of S-SSB opportunities within an S-SSB window is arranged in a continuous manner in the time domain.

[0149] The S-SSB window is designed to support more S-SSB opportunities and more chances for UEs to access the channel, which is required in, for example, beam-based transmission scenarios.

[0150] The S-SSB window can contain the following types:

[0151] 1. Type 1 window: S-SSBs in the Type 1 window are transmitted on the same beam.

[0152] 2. Type 2 window: S-SSBs in the Type 2 window are transmitted on different beams, for example, to perform beam scanning.

[0153] 3. The Type 3 window is a hybrid of the Type 1 window and the Type 2 window. Some S-SSBs in the Type 3 window may be transmitted on the same beam, while other S-SSBs may be transmitted on different beams.

[0154] The number of S-SSB opportunities in the S-SSB window may be determined based on at least one of the following:

[0155] 1. Channel access procedure defined for S-SSB. For example, in unlicensed spectrum, a channel access procedure with LBT is required before performing S-SSB transmission.

[0156] 2. Configuration of beam-based transmission, for example, the number of transmit beams used to perform S-SSB transmission.

[0157] 3. Frequency band: For example, for higher frequency bands, the S-SSB window may include more S-SSB opportunities.

[0158] The BS may transmit a configuration associated with an S-SSB period including an S-SSB opportunity to the UE. Specifically, the configuration may include at least one of the following:

[0159] 1. Period indicates the length of the S-SSB period.

[0160] 2. The offset from the start time slot of the S-SSB period to the start time slot of the first S-SSB window within the S-SSB period, which is used to perform the channel access procedure with LBT. To allow sufficient time to perform the LBT procedure, the offset is configured to be sufficient to perform the supported LBT type before the S-SSB window.

[0161] 3. The interval between two adjacent S-SSB windows (e.g., between the start time slots of two adjacent S-SSB windows) for performing a channel access procedure with LBT. The interval is determined based on the LBT type. Specifically, the interval is sufficient to perform the supported LBT type before the S-SSB window.

[0162] 4. The number of S-SSB windows within the S-SSB period, which may be denoted as “M1”.

[0163] 5. The number of S-SSB opportunities within each S-SSB window, which can be denoted as "N1". The S-SSB opportunities are arranged in a continuous manner in each S-SSB window. That is, N1 S-SSB opportunities are continuous in the time domain.

[0164] 6. Type of S-SSB window, which may include: Type 1, Type 2, or Type 3.

[0165] 7. Information used for channel access procedure, which may include LBT type.

[0166] The granularity of configuration and the manner of transmission are similar to the configuration information of the gaps described above, and the details are omitted here.

[0167] Figure 7 An exemplary distribution of S-SSB opportunities within an S-SSB cycle according to some embodiments of the present disclosure is described.

[0168] An S-SSB period includes M1 S-SSB windows, namely S-SSB window #0, S-SSB window #1, ..., S-SSB window #M1-1. Each S-SSB window includes N1 S-SSB opportunities, namely S-SSB opportunity #0, S-SSB opportunity #1, ..., S-SSB opportunity #N1-1. The period is the length of the S-SSB period. The offset is the duration from the start time slot of the S-SSB period to the start time slot of S-SSB window #0. The interval is the duration from the start time slot of S-SSB window #0 to the start time slot of S-SSB window #1.

[0169] In some embodiments, the number of S-SSB opportunities within one S-SSB window may be 1, that is, N1 is 1. In this case, the S-SSB window is an S-SSB opportunity, and the configuration may include at least one of the following:

[0170] 1. Period indicates the length of the S-SSB period.

[0171] 2. The offset from the start time slot of the S-SSB cycle to the start time slot of the first S-SSB opportunity within the S-SSB cycle.

[0172] 3. The interval between two adjacent S-SSB opportunities.

[0173] 4. The number of S-SSB opportunities within the S-SSB period, which may be denoted as “N2”.

[0174] 5. Information used for the channel access procedure, which may include the LBT type.

[0175] Figure 8 Another exemplary distribution of S-SSB opportunities within one S-SSB cycle according to some embodiments of the present disclosure is described.

[0176] An S-SSB cycle includes N2 S-SSB opportunities, namely S-SSB opportunity #0, S-SSB opportunity #1, ..., S-SSB opportunity #N2-1. The period is the length of the S-SSB cycle. The offset is the duration from the start time slot of the S-SSB cycle to the start time slot of the first S-SSB opportunity (i.e., S-SSB opportunity #0). The interval is the duration from one S-SSB opportunity to the next (e.g., S-SSB opportunity #1 to S-SSB opportunity #2).

[0177] Solution 5

[0178] Regarding PSBCH, in R16, PSBCH can contain the following contents:

[0179] • Direct Frame Number (DFN), which contains 10 bits.

[0180] Slot index, which contains 7 bits. Based on the DFN and slot index, the UE can determine the location of the S-SSB.

[0181] • Coverage indicator, which contains 1 bit, indicating whether the UE is in coverage.

[0182] TDD Configuration: It contains 12 bits, which indicates the configuration related to TDD.

[0183] Reserved bits: 2

[0184] In this disclosure, it is proposed that the PSBCH includes at least one of the following information:

[0185] • DFN, which may contain 10 bits.

[0186] • Slot index, which may contain 7 bits. Since the exact transmission time of the S-SSB is unknown to the receiving UE, the transmission timing needs to be included in the PSBCH.

[0187] A first indicator indicating whether the S-SSB including the PSBCH is within the COT. If the indicator indicates that the S-SSB is within the COT, this means that the S-SSB transmission is transmitted continuously. If the indicator indicates that the S-SSB is not within the COT, this means that the S-SSB transmission is a discrete transmission without a COT.

[0188] A second indicator indicating whether the next S-SSB is within the current COT. If the indicator indicates that the next S-SSB is within the current COT, this means that the S-SSB transmission is transmitted continuously. If the indicator indicates that the S-SSB is not within the current COT, this means that the S-SSB transmission is discrete.

[0189] Parameter Q, which is used to support beam-based transmission of S-SSBs in unlicensed spectrum by indicating the QCL relationship. In some embodiments, for the sidelink in the unlicensed band, the QCL assumption can be linked to the PSBCH demodulation reference signal (DMRS) sequence index. S-SSBs with the same sequence index modulo parameter Q are assumed to have the same QCL relationship, i.e., the S-SSBs are transmitted using the same beam.

[0190] • A third indicator indicating whether the beam is used for repeated transmission of S-SSB within the S-SSB window.

[0191] Figure 9 Flowchart illustrating an exemplary method for S-SSB transmission in unlicensed spectrum according to some embodiments of the present disclosure. Although the method is described below with respect to a UE, it is contemplated that the method may be performed by any other device having similar functionality.

[0192] In operation 901, a UE may receive configuration information for an S-SSB in an unlicensed spectrum, the configuration information including at least one of: a first configuration associated with an S-SSB structure including at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for a PSBCH; or a second configuration associated with an S-SSB period including one or more S-SSB opportunities. In operation 902, the UE may select at least one S-SSB opportunity based on the configuration information. In operation 903, the UE may transmit an S-SSB on the at least one S-SSB opportunity in response to a successful LBT procedure associated with the at least one S-SSB opportunity.

[0193] Correspondingly, at the BS side, the BS may transmit configuration information for S-SSB in the unlicensed spectrum to the UE.

[0194] In some embodiments, 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. In some embodiments, the configuration information is received via at least one of the following: MIB message, SIB message, RRC signaling, or MAC CE.

[0195] In some embodiments, the first structure configuration in the time domain includes at least one of the following: the number of symbols as a gap for performing the LBT process in the S-SSB slot, or the position of the symbols in the S-SSB slot. Figure 4 As shown in , the first structure configuration in the time domain includes one symbol as a gap for performing the LBT process, and the position of the symbol in the S-SSB slot is at symbol #13.

[0196] In some embodiments, the second structure configuration in the frequency domain includes at least one of the following: the number of S-SSB repetitions in the frequency band; the position of the S-SSB repetitions in the frequency band; the number of resource blocks (RBs) in the frequency band that are not occupied by S-SSB repetitions; or the position of the RBs in the frequency band. Figure 5A As shown in , the second structural configuration in the frequency domain includes 9 S-SSB repetitions, S-SSB#m_0, S-SSB#m_1, S-SSB#m_8, the positions of the S-SSB repetitions in the frequency band; 7 RBs not occupied by S-SSB repetitions; or the positions of 7 RBs in the frequency band.

[0197] In some embodiments, the second structure configuration in the frequency domain includes at least one of the following: an interleaving pattern in a frequency band; an index of an available interleaving in a frequency band; the number of interleavings used for one S-SSB; or an indicator indicating whether FDM is enabled. Figure 6 As shown in , the second structure configuration in the frequency domain includes an interleaving pattern in a frequency band, an index of available interleavings in a frequency band, which includes interleaving #0 to interleaving #5; the number of interleavings used for one S-SSB, e.g., 1; or an indicator indicating whether FDM is enabled.

[0198] In some embodiments, the UE may select an interlace for transmitting S-SSBs from the available interlaces based at least in part on a second structure configuration in the frequency domain; and map the S-SSBs to be transmitted to the RB set of the selected interlace. Figure 6 , the UE can select interlace #0 from interlace #0 to interlace #5 for transmitting S-SSB, and map the S-SSB to be transmitted to the RB set of interlace #0.

[0199] In some embodiments, where the indicator indicates that FDM is not enabled, the UE may select an interlace for transmitting the S-SSB based on random selection; or select the first one or more interlaces for transmitting the S-SSB from the available interlaces.

[0200] In some embodiments, when the indicator indicates that FDM is enabled, the UE may select an interlace for transmitting the S-SSB to be transmitted based on at least one of: random selection, an identifier of the UE, an identifier of a sidelink synchronization signal (SLSS) associated with the UE, or a priority level of the UE's synchronization reference.

[0201] In some embodiments, the configuration indication for the PSBCH includes at least one of: a first indicator indicating whether the S-SSB including the PSBCH is within the COT; a second indicator indicating whether the next S-SSB is within the current COT; a parameter associated with the QCL relationship; or a third indicator indicating whether the beam is used for repeated transmission of S-SSBs within the S-SSB window.

[0202] In some embodiments, the second configuration includes at least one of: a period indicating the length of an S-SSB period; a number of S-SSB windows within an S-SSB period; a number of S-SSB opportunities within each S-SSB window; an offset from a start time slot of an S-SSB period to a start time slot of a first S-SSB window in an S-SSB window within an S-SSB period; an interval between start time slots of two adjacent S-SSB windows; an indicator indicating whether each S-SSB window is a type 1 window, a type 2 window, or a type 3 window; or an LBT process type. For example, referring to Figure 7 The second configuration includes a period indicating the length of the S-SSB period, which is labeled "Period"; the number of S-SSB windows within the S-SSB period, which is M1; the number of S-SSB opportunities within each S-SSB window, which is N1; an offset from the start time slot of the S-SSB period to the start time slot of the first S-SSB window in the S-SSB window within the S-SSB period, which is Figure 7 The interval between the start time slots of two adjacent S-SSB windows is marked by "offset" in Figure 7 In the field, "Interval" is marked, indicating whether each S-SSB window is a Type 1 window, a Type 2 window, or a Type 3 window; or an LBT process type.

[0203] In some embodiments, the number of S-SSB opportunities within each S-SSB window is determined based on at least one of: a channel access procedure associated with the S-SSB; a configuration of beam-based sidelink transmissions; or a frequency band associated with the S-SSB. For example, according to Table 1, a higher frequency band may be configured with more S-SSB opportunities per S-SSB window.

[0204] Figure 10 A simplified block diagram illustrating an exemplary apparatus for S-SSB transmission in unlicensed spectrum in accordance with some embodiments of the present disclosure.

[0205] like Figure 10 , apparatus 1000 may include at least one processor 1004 and at least one transceiver 1002 coupled to the processor 1004. Apparatus 1000 may be a UE or a BS or any other device having similar functionality.

[0206] Although elements such as at least one transceiver 1002 and a processor 1004 are described in the singular in this figure, the plural form is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present disclosure, the transceiver 1002 may be divided into two devices, such as a receive circuit system and a transmit circuit system. In some embodiments of the present disclosure, the device 1000 may further include an input device, a memory, and / or other components.

[0207] In some embodiments of the present disclosure, the device 1000 may be a UE. The transceiver 1002 and the processor 1004 may interact with each other to perform Figures 1 to 9 In some embodiments of the present disclosure, the device 1000 may be a BS. The transceiver 1002 and the processor 1004 may interact with each other to perform Figures 1 to 9 The operation of the BS described in any one of .

[0208] In some embodiments of the present application, the apparatus 1000 may further include at least one non-transitory computer-readable medium.

[0209] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1004 to implement the method described above with respect to the UE. For example, when executed, the computer-executable instructions cause the processor 1004 to interact with the transceiver 1002 to perform Figures 1 to 9 The operations of the UE described in any one of .

[0210] In some embodiments of the present disclosure, a non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1004 to implement the method described above with respect to the BS. For example, when executed, the computer-executable instructions cause the processor 1004 to interact with the transceiver 1002 to perform Figures 1 to 9 The operation of the BS described in any one of .

[0211] The methods of the present disclosure may be implemented on a programmed processor. However, the controller, flow charts, and modules may also be implemented on a general-purpose or special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, a hardware electronic or logic circuit (e.g., a discrete element circuit), a programmable logic device, etc. In general, any device having a finite state machine capable of implementing the flow charts shown in the figures may be used to implement the processing functions of the present disclosure.

[0212] Although the present disclosure has been described using its specific embodiments, it is apparent that many alternatives, modifications, and variations are apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added, or replaced in other embodiments. In addition, not all elements of each figure are necessary for the operation of the disclosed embodiments. For example, a person skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting elements of independent technical solutions. Therefore, the embodiments of the present disclosure as described herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0213] In the present disclosure, for example, relational terms such as "first", "second" can only be used to distinguish an entity or action from another entity and action, and do not necessarily require or imply any actual such relationship or order between such entities or actions. The term "comprises, comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only comprises those elements, but also can comprise other elements that are not clearly listed or inherent to such processes, methods, articles or equipment. In the absence of more constraints, elements starting with "a, an" or the like do not exclude the presence of additional identical elements in the process, method, article or equipment comprising the elements. In addition, the term "another" is defined as at least a second or more. As used herein, the terms "comprise", "have" and the like are defined as "comprising".

Claims

1. A user equipment UE, comprising: Transceiver; and a processor coupled to the transceiver and configured to: The method further comprises receiving, using the transceiver, configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum, comprising at least one of: A first configuration associated with an S-SSB structure, comprising at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for a physical sidelink broadcast channel PSBCH; or a second configuration associated with an S-SSB period including one or more S-SSB opportunities; selecting at least one S-SSB opportunity based on the configuration information; and In response to a listen-before-talk (LBT) procedure associated with the at least one S-SSB opportunity being successful, transmitting an S-SSB on the at least one S-SSB opportunity using the transceiver.

2. The UE according to 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 is spaced SCS.

3. The UE according to claim 1, wherein the configuration information is received 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).

4. The UE according to claim 1, wherein the first structural configuration in the time domain includes at least one of the following: the number of symbols as gaps for performing the LBT process in an S-SSB slot, or the position of the symbols in the S-SSB slot.

5. The UE according to claim 1, wherein the second structure configuration in the frequency domain comprises at least one of the following: The number of S-SSB repetitions in the band; a position of said S-SSB repetition in said frequency band; The number of resource blocks (RBs) in the frequency band that are not repeatedly occupied by the S-SSBs; or The location of the RB in the frequency band.

6. The UE according to claim 1, wherein the second structure configuration in the frequency domain comprises at least one of the following: interweaving patterns in the frequency bands; an index of an available interlace in the frequency band; The number of interlaces used for one S-SSB; or Indicator indicating whether frequency domain multiplexing (FDM) is enabled.

7. The UE of claim 6, wherein the processor is further configured to: selecting an interlace for transmitting the S-SSB from the available interlaces based at least in part on the second structural configuration in the frequency domain; and The S-SSB to be transmitted is mapped to the selected interlaced RB set.

8. The UE of claim 7, wherein if the indicator indicates that FDM is not enabled, the processor is further configured to: selecting the interlace for transmitting the S-SSB based on random selection; or A first one or more interlaces are selected from the available interlaces for transmitting the S-SSB.

9. The UE of claim 7, wherein if the indicator indicates that FDM is enabled, the processor is further configured to: The interlace for transmitting the S-SSB is selected based on at least one of: random selection, an identifier of the UE, an identifier of a sidelink synchronization signal SLSS associated with the UE, or a priority level of a synchronization reference of the UE.

10. The UE according to claim 1, wherein the configuration indication for PSBCH includes at least one of the following: A first indicator, which indicates whether the S-SSB containing the PSBCH is within the channel occupancy time COT; a second indicator indicating whether the next S-SSB is within the current COT; Parameters associated with quasi-co-located QCL relationships; or The third indicator indicates whether the beam is used for repeated transmission of S-SSB within the S-SSB window.

11. The UE of claim 1 , wherein the second configuration comprises at least one of: The length of the S-SSB period; the number of S-SSB windows within the S-SSB period; The number of S-SSB opportunities in each S-SSB window; an offset from a start time slot of the S-SSB period to a start time slot of a first S-SSB window in the S-SSB windows within the S-SSB period; The interval between the start time slots of two adjacent S-SSB windows; an indicator indicating whether each S-SSB window is a type 1 window, a type 2 window, or a type 3 window; or LBT process type.

12. The UE of claim 11, wherein each S-SSB window includes only one S-SSB opportunity.

13. The UE of claim 11, wherein the number of the S-SSB opportunities within each S-SSB window is determined based on at least one of: Channel access procedures associated with S-SSB; Configuration of beam-based sidelink transmissions; or The frequency band associated with the S-SSB.

14. A base station BS, comprising: Transceiver; and a processor coupled to the transceiver and configured to: The method includes transmitting, using the transceiver, configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum, comprising at least one of: A first configuration associated with an S-SSB structure, comprising at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for a physical sidelink broadcast channel PSBCH; or A second configuration associated with an S-SSB period including one or more S-SSB opportunities.

15. A method performed by a user equipment UE, comprising: Receiving configuration information for a sidelink synchronization signal block (S-SSB) in an unlicensed spectrum, comprising at least one of: A first configuration associated with an S-SSB structure, comprising at least one of: a first structure configuration in the time domain, a second structure configuration in the frequency domain, or a configuration for a physical sidelink broadcast channel PSBCH; or a second configuration associated with an S-SSB period including one or more S-SSB opportunities; selecting at least one S-SSB opportunity based on the configuration information; and In response to a listen-before-talk (LBT) procedure associated with the at least one S-SSB opportunity being successful, an S-SSB is transmitted on the at least one S-SSB opportunity.

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