WO2024073989A1

WO2024073989A1 - Methods and apparatuses for multiple channel access for s-ssb transmission in unlicensed spectra

Info

Publication number: WO2024073989A1
Application number: PCT/CN2023/073381
Authority: WO
Inventors: Xin Guo; Haipeng Lei; Zhennian SUN; Xiaodong Yu
Original assignee: Lenovo (Beijing) Limited
Priority date: 2023-01-20
Filing date: 2023-01-20
Publication date: 2024-04-11

Abstract

Embodiments of the present disclosure relate to methods and apparatuses for multiple channel access for sidelink synchronization signal block (S-SSB) transmission in unlicensed spectra. According to an embodiment of the present disclosure, a user equipment can include: a transceiver; and a processor coupled to the transceiver and configured to: obtain first configuration information for multiple channel access on a first set of resource block (RB) sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting frequency division multiplexed S-SSB and sidelink transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; determine a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets; and transmit, via the transceiver, S-SSB on at least one RB set within the determined second set of RB sets.

Description

METHODS AND APPARATUSES FOR MULTIPLE CHANNEL ACCESS FOR S-SSB TRANSMISSION IN UNLICENSED SPECTRA

TECHNICAL FIELD

Embodiments of the present application are related to wireless communication technologies, and more particularly, related to methods and apparatuses for multiple channel access for sidelink synchronization signal block (S-SSB) transmission in unlicensed spectra.

BACKGROUND

A sidelink is a long-term evolution (LTE) feature introduced in 3rd generation partnership project (3GPP) Release 12, and enables a direct communication between proximal user equipments (UEs) , in which data does not need to go through a base station (BS) or a core network. A sidelink communication system has been introduced into 3GPP 5G wireless communication technology, in which a direct link between two UEs is called a sidelink.

Sidelink synchronization information is carried in an S-SSB. In unlicensed spectra, how to transmit S-SSB needs to be discussed.

SUMMARY OF THE APPLICATION

Embodiments of the present application at least provide a technical solution for multiple channel access for S-SSB transmission in unlicensed spectra.

According to some embodiments of the present application, a UE may include: a transceiver; and a processor coupled to the transceiver and configured to: obtain first configuration information for multiple channel access on a first set of resource block (RB) sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting frequency division multiplexed (FDMed) S-SSB and sidelink (SL) transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; determine a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets; and transmit, via the transceiver, S-SSB on at least one RB set within the determined second set of RB sets.

In some embodiments of the present application, the first set of RB sets is determined based on bandwidth part (BWP) , carrier, resource pool, or frequency range.

In some embodiments of the present application, the first configuration information further includes at least one of: one or more channel access priority class (CAPC) values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more cyclic prefix extension (CPE) values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission.

In some embodiments of the present application, to determine the second set of RB sets, the processor is configured to: perform a Type-1 channel access procedure on each RB set within the first set of RB sets according to a CAPC value within the one or more CAPC values; and determine the second set of RB sets to include all RB set(s) within the first set of RB sets which is (are) identified to be idle based on the Type-1 channel access procedure.

In some embodiments of the present application, to determine the second set of RB sets, the processor is configured to: select a first RB set within the first set of RB sets and perform a Type-1 channel access procedure on the first RB set according to a CAPC value within the one or more CAPC values; and in the case that the first RB set is identified to be idle based on the Type-1 channel access procedure: perform a Type 2A channel access procedure on each of remaining RB set (s) within the first set of RB sets before availability for transmitting on the first RB set; and determine the second set of RB sets to include the first RB set and all RB set (s) within the remaining RB set (s) which is (are) identified to be idle based on the Type 2A channel access procedure.

In some embodiments of the present application, the second configuration information indicates one of: interlace (s) available for S-SSB transmission within each RB set of the first set of RB sets; or contiguous RBs and symbols of each cluster and S-SSB component (s) carried by each cluster located in each RB set of the first set of RB sets.

In some embodiments of the present application, in the case that the second or fourth configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on a lowest or highest RB set within the determined second set of RB sets based on the second or fourth configuration information, respectively.

In some embodiments of the present application, the third configuration information indicates: a slot structure of S-SSB within each RB set of the N1 RB sets.

In some embodiments of the present application, in the case that the third configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on lowest or highest N1 RB sets within the determined second set of RB sets based on the third configuration information.

In some embodiments of the present application, the fourth configuration information indicates a non-zero time offset between starting boundaries of S-SSB periods from at least two RB sets within the first set of RB sets.

In some embodiments of the present application, the fifth configuration information indicates: RB (s) available for S-SSB transmission within the guard band (s) ; and a slot structure of S-SSB spanning over the N2 adjacent RB sets and the guard band (s) .

In some embodiments of the present application, in the case that the fifth configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on lowest or highest N2 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween.

In some embodiments of the present application, the sixth configuration information indicates: interlace (s) available for S-SSB transmission within at least one RB set of the N3 adjacent RB sets; interlace (s) available for SL transmission within remaining RB set (s) of the N3 adjacent RB sets; and RB (s) available for S-SSB transmission within the guard band (s) .

In some embodiments of the present application, in the case that the sixth configuration information is included in the first configuration information, the processor is configured to transmit FDMed S-SSB and SL transmission on lowest or highest N3 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween.

According to some embodiments of the present application, a UE may include: a transceiver; and a processor coupled to the transceiver and configured to: obtain first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; and monitor the first set of RB sets to detect S-SSB on at least one RB set within the first set of RB sets based on the obtained first configuration information.

In some embodiments of the present application, the first set of RB sets is determined based on: BWP, carrier, resource pool, or frequency range.

In some embodiments of the present application, the processor is configured to:in the case that the second or fourth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on one RB set of the first set of RB sets or until an end of the monitoring; in the case that the third configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N1 RB sets of the first set of RB sets or until an end of the monitoring; in the case that the fifth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N2 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring; or in the case that the sixth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting FDMed S-SSB and SL transmission on N3 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring.

According to some embodiments of the present application, a BS may include: a transceiver; and a processor coupled to the transceiver and configured to: transmit, via the transceiver, first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one.

In some embodiments of the present application, the processor is configured to transmit, via the transceiver, the first 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, a medium access control (MAC) control element (CE) , or downlink control information (DCI) .

In some embodiments of the present application, the first configuration information further includes at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission.

In some embodiments of the present application, the fifth configuration information indicates: RB (s) available for S-SSB transmission within the guard band (s) ; and a slot structure for S-SSB spanning over the N2 adjacent RB sets and the guard band (s) .

According to some embodiments of the present application, a method performed by a UE may include: obtaining first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; determining a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets; and transmitting S-SSB on at least one RB set within the determined second set of RB sets.

According to some embodiments of the present application, a method performed by a UE may include: obtaining first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; and monitoring the first set of RB sets to detect S-SSB on at least one RB set within the first set of RB sets based on the obtained first configuration information.

According to some embodiments of the present application, a method performed by a BS may include: transmitting first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.

FIG. 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

FIG. 2 illustrates an exemplary S-SSB slot according to some embodiments of the present application;

FIG. 3 illustrates an exemplary interlace RB-based structure for 15kHz subcarrier spacing (SCS) in 20MHz bandwidth according to some embodiments of the present application;

FIG. 4 illustrates a flowchart of an exemplary method for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some embodiments of the present application;

FIG. 5 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple RB sets according to some embodiments of the present application;

FIG. 6 illustrates an exemplary cluster-based slot structure for S-SSB on multiple RB sets according to some embodiments of the present application;

FIG. 7 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple RB sets according to some other embodiments of the present application;

FIG. 8 illustrates an exemplary cluster-based slot structure for S-SSB on multiple RB sets according to some other embodiments of the present application;

FIG. 9 illustrates an exemplary time domain distribution of S-SSB occasions over multiple RB sets according to some embodiments of the present application;

FIG. 10 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple adjacent RB sets and guard band (s) therebetween according to some embodiments of the present application;

FIG. 11 illustrates an exemplary slot structure supporting FDMed S-SSB and SL transmission on multiple adjacent RB sets and guard band (s) therebetween according to some embodiments of the present application;

FIG. 12 illustrates a flowchart of an exemplary method for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some other embodiments of the present application; and

FIG. 13 illustrates a simplified block diagram of an exemplary apparatus for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some embodiments of the present application.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of preferred embodiments of the present application and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

While operations are depicted in the drawings in a particular order, persons skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all illustrated operations need be performed, to achieve desirable results; sometimes one or more operations can be skipped. Further, the drawings can schematically depict one or more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing can be advantageous.

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 architecture and new service scenarios, such as 3GPP LTE and LTE advanced, 3GPP 5G new radio (NR) , 5G-Advanced, 6G, and so on. It is contemplated that along with developments of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and moreover, the terminologies recited in the present application may change, which should not affect the principle of the present application.

FIG. 1 illustrates an exemplary wireless communication system 100 in accordance with some embodiments of the present application.

As shown in FIG. 1, the wireless communication system 100 includes at least one UE 101 and at least one BS 102. In particular, the wireless communication system 100 includes two UEs 101 (e.g., UE 101a and UE 101b) and one BS 102 for illustrative purpose. Although a specific number of UEs 101 and BS 102 are depicted in FIG. 1, it is contemplated that any number of UEs 101 and BSs 102 may be included in the wireless communication system 100.

According to some embodiments of the present disclosure, the UE (s) 101 may include computing devices, such as desktop computers, laptop computers, personal digital assistants (PDAs) , tablet computers, smart televisions (e.g., televisions connected to the Internet) , set-top boxes, game consoles, security systems (including security cameras) , vehicle on-board computers, network devices (e.g., routers, switches, and modems) , or the like.

According to some other embodiments of the present disclosure, the UE (s) 101 may include a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network.

According to some other embodiments of the present disclosure, the UE (s) 101 may include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like.

According to some embodiments of the present disclosure, the UE (s) 101 may include vehicle UEs (VUEs) and/or power-saving UEs (also referred to as power sensitive UEs) . The power-saving UEs may include vulnerable road users (VRUs) , public safety UEs (PS-UEs) , and/or commercial sidelink UEs (CS-UEs) that are 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 which require power saving compared with a VUE.

Moreover, the UE (s) 101 may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art.

In a sidelink communication system, a transmission UE may also be named as a transmitting UE, a Tx UE, a sidelink Tx UE, a sidelink transmission UE, or the like. A reception UE may also be named as a receiving UE, an Rx UE, a sidelink Rx UE, a sidelink reception UE, or the like.

According to some embodiments of FIG. 1, UE 101a functions as a Tx UE, and UE 101b functions as an Rx UE. UE 101a may exchange sidelink messages with UE 101b through a sidelink, for example, via PC5 interface as defined in 3GPP TS 23.303. UE 101a may transmit information or data to other UE (s) within the sidelink communication system, through sidelink unicast, sidelink groupcast, or sidelink broadcast. For instance, UE 101a may transmit data to UE 101b in a sidelink unicast session. UE 101a may transmit data to UE 101b and other UE (s) in a groupcast group (not shown in FIG. 1) by a sidelink groupcast transmission session. Also, UE 101a may transmit data to UE 101b and other UE (s) (not shown in FIG. 1) by a sidelink broadcast transmission session.

Alternatively, according to some other embodiments of FIG. 1, UE 101b functions as a Tx UE and transmits sidelink messages, and UE 101a functions as an Rx UE and receives the sidelink messages from UE 101b.

In some embodiments of the present disclosure, UE 101a may communicate with UE 101b over licensed spectrums, whereas in other embodiments, UE 101a may communicate with UE 101b over unlicensed spectrums.

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

The wireless communication system 100 may be compatible with any type of network that is 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 time division multiple access (TDMA) based network, a code division multiple access (CDMA) based network, an orthogonal frequency division multiple access (OFDMA) based network, an LTE network, a 3GPP-based network, a 3GPP 5G network, a satellite communications network, a high-altitude platform network, and/or other communications networks.

In some embodiments of the present disclosure, the wireless communication system 100 is compatible with the 5G NR of the 3GPP protocol, wherein BS (s) 102 transmit data using an orthogonal frequency division multiplexing (OFDM) modulation scheme on the downlink (DL) and UE (s) 101 transmit 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. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocols, for example, WiMAX, among other protocols.

In some embodiments of the present disclosure, BS (s) 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Further, in some embodiments of the present disclosure, BS(s) 102 may communicate over licensed spectrums, whereas in other embodiments, BS(s) 102 may communicate over unlicensed spectrums. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. In yet some embodiments of the present disclosure, BS (s) 102 may communicate with UE (s) 101 using the 3GPP 5G protocols.

In NR, accommodating multiple uncoordinated UEs in an unlicensed spectrum requires channel access procedures defined for NR. Following a successful channel access procedure performed by a communicating node, the channel can be used by the communicating node during a period until the end of the period. Such a period may be referred to as a channel occupancy time (COT) . During a COT, one or more transmissions may be exchanged between the communicating nodes, wherein a transmission may be a downlink transmission or an uplink transmission.

Dynamic channel access procedures are usually used by a BS or a UE to access a channel in an unlicensed spectrum. Dynamic channel access procedures may be based on listen-before-talk (LBT) , where a transmitter listens to potential transmission activity on a channel prior to transmitting and applies a random back-off time in some cases. Two main types of dynamic channel access procedures may be defined in NR. One is Type-1 dynamic channel access procedure, which is also referred to as LBT type 1 or LBT cat4. The other is Type-2 dynamic channel access procedure, which is also referred to as LBT type 2.

Type-1 dynamic channel access procedure may be used to initiate data transmission at the beginning of a COT. The initiator for the Type-1 dynamic channel access procedure may be either a BS or a UE. The Type-1 dynamic channel access procedure may be summarized as follows.

First, the initiator listens and waits until a channel (e.g., a frequency channel) is available during at least one period referred to as a defer duration. The defer duration may consist of 16 μs and a number (e.g., "m_p" in the following Table 1 or Table 2, which will be illustrated below) of 9 μs slots. As shown in Table 1 and Table 2, a value of "m_p" depends on a value of CAPC (represented as "p" ) . Accordingly, the defer duration depends on the value of CAPC as shown in the following Table 1 or Table 2. A channel is declared to be available if the received energy during at least 4 μs of each 9 μs slot is below a threshold.

Once the channel has been declared available during the defer duration, the transmitter starts a random back-off procedure during which it will wait a random period of time.

The UE starts the random back-off procedure by initializing a back-off timer with a random number within a contention window (CW) . The random number is drawn from a uniform distribution [0, CW] and represents that the channel must be available for a timer duration (e.g., defined by the random number multiplying 9 μs) before transmission can take place. The value of "CW" may be selected from "allowed CW_p sizes" (the minimum value is represented as CW_min, p, and the maximum value is represented as CW_max, p) in the following Table 1 or Table 2, which depends on a value of CAPC.

The back-off timer is decreased by one for each sensing slot duration (e.g., 9 μs) the channel is sensed to be idle; whenever the channel is sensed to be busy, the back-off timer is put on hold until the channel has been idle for a defer duration.

Once the back-off timer has expired (e.g., the back-off timer is decreased to be 0) , the random back-off procedure is completed, and the transmitter has acquired the channel and can use it for transmission up to a maximum channel occupancy time (MCOT) (e.g., T_mcot, p in the following Table 1 or T_ulmcot, p in the following Table 2, which depends on a value of CAPC) .

The following Table 1 and Table 2 illustrate exemplary CAPC for DL and CAPC for UL, respectively, and corresponding values of m_p, CW_min, p, CW_max, p, T_mcot, p, T_ulmcot, p, and allowed CW_p sizes. 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 a BS intends to initiate a channel occupancy for DL transmission, it may determine a CAPC value before performing a Type-1 channel access procedure, and then determine the corresponding values (e.g., m_p, CW_min, p, CW_max, p, T_mcot, p, and allowed CW_psizes) used in the Type-1 channel access procedure according to Table 1. When a UE intends to initiate a channel occupancy for UL transmission, it may determine a CAPC value before performing a Type-1 channel access procedure, and then determine the corresponding values (e.g., m_p, CW_min, p, CW_max, p, T_ulmcot, p, and allowed CW_psizes) used in the Type-1 channel access procedure according to Table 2.

Table 1: Channel Access Priority Class for DL

Table 2: Channel Access Priority Class for UL

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, which covers the beginning of the COT. For each received HARQ report, the contention window is (approximately) doubled up to the limit CW_max, p if a negative HARQ report (e.g., non-acknowledgement (NACK) ) is received. For a positive HARQ report (e.g., acknowledgement (ACK) ) , the contention window is reset to its minimum value, i.e., CW=CW_min, p.

Type-2 dynamic channel access procedure may be used for COT sharing and transmission of discovery bursts. Depending on a duration of a gap (also referred to as "COT sharing gap" ) in the COT, Type-2 dynamic channel access procedure may be further classified into the following three procedures, wherein which procedure to be used may be determined depending on the duration of the gap between two transmission bursts.

· Type 2A dynamic channel access procedure (also referred to as LBT cat2 or LBT type 2A) : which is used when the gap is 25 μs or more for transmission of the discovery bursts.

· Type 2B dynamic channel access procedure (also referred to as LBT type 2B) : which is used when the gap is 16 μs.

· Type 2C dynamic channel access procedure (also referred to as LBT type 2C) : which is used when the gap is 16 μs or less after the preceding transmission burst.

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

Type 2A dynamic channel access procedure and Type 2B dynamic channel access procedure may be similar to Type-1 dynamic channel access procedure but without the random back-off. That is, in Type 2A dynamic channel access procedure and Type 2B dynamic channel access procedure, if a channel is detected to be idle in the gap, it is declared to be available; if it is detected to be busy, the COT sharing has failed and the transmission cannot occur using COT sharing in this COT. If the COT sharing gap is 16 μs, Type 2B dynamic channel access procedure may be used and the channel must be detected to be idle in the 16 μs gap prior to the next transmission burst. If the COT sharing gap is 25 μs or longer, Type 2A dynamic channel access procedure may be used and the channel must be detected to be idle during at least 25 μs immediately preceding the next transmission burst.

The above embodiments provide several dynamic channel access procedures in an unlicensed spectrum for NR. These dynamic channel access procedures may also apply for sidelink transmissions in an unlicensed spectrum.

Sidelink synchronization information is carried in an S-SSB that consists of physical sidelink broadcast channel (PSBCH) , sidelink primary synchronization signal (S-PSS) and sidelink secondary synchronization signal (S-SSS) . FIG. 2 illustrates an exemplary S-SSB slot according to some embodiments of the present disclosure. In the embodiments of FIG. 2, a normal cyclic prefix (CP) is used.

Referring to FIG. 2, an S-SSB occupies one slot in the time domain and occupies 11 RBs in the frequency domain. Each RB spans 12 subcarriers, thus the S-SSB bandwidth is 132 (11 × 12) subcarriers. In the example of FIG. 2, the S-SSB slot may include 14 OFDM symbols in total, e.g., symbol #0 to symbol #13. The S-PSS is transmitted repeatedly on the second and third symbols in the S-SSB slot, e.g., symbol #1 and symbol #2. The S-SSS is transmitted repeatedly on the fourth and fifth symbols in the S-SSB slot, e.g., symbol #3 and symbol #4. The S-PSS and the S-SSS occupy 127 subcarriers in the frequency domain, which are from the third subcarrier relative to the start of the S-SSB bandwidth up to the 129th subcarrier.

The S-PSS and the S-SSS are jointly 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 referred to as a SyncRef UE) , a UE is able to synchronize to the SyncRef UE and estimate the beginning of the frame and carrier frequency offsets.

The S-PSS may be generated from the maximum length sequences (m-sequences) that use the same design (i.e., generator polynomials, initial values and cyclic shifts, etc. ) which is used for generating the m-sequences in the primary synchronization signal (PSS) in the 3GPP documents. In NR Uu, there are three candidate sequences for PSS. However, only two candidate sequences are used for S-PSS.

The S-SSS may be generated from the Gold sequences that use the same design (i.e., generator polynomials, initial values and cyclic shifts, etc. ) which is utilized for generating the Gold sequences for the secondary synchronization signal (SSS) in the 3GPP documents. This results in 336 candidate sequences for S-SSS like for the SSS in NR Uu.

For the transmission of SLSS within an S-SSB, a SyncRef UE may select an S-PSS and an S-SSS out of the candidate sequences based on an SLSS identifier (ID) . The SLSS ID represents an identifier of the SyncRef UE and conveys a priority of the SyncRef UE as in LTE vehicle-to-everything (V2X) . Each SLSS ID corresponds to a unique combination of an S-PSS and an S-SSS out of the 2 S-PSS candidate sequences and the 336 S-SSS candidate sequences.

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

The structure of S-SSB slot in FIG. 2 is only for illustrative purpose. It is contemplated that along with developments of network architectures and new service scenarios, the S-SSB may have other structures (for example, the S-SSB may include 6 OFDM symbols in the time domain) , which should not affect the principle of the present application.

In some embodiments of the present application, S-SSB may be transmitted on an unlicensed spectrum. For S-SSB transmission over an unlicensed spectrum, some requirements should be met. These requirements may include at least one of the followings:

· Occupied channel bandwidth (OCB) requirement, which requires that the bandwidth containing 99%of the power of the signal, shall be between 80%and 100%of declared Nominal Channel Bandwidth; or

· Power Spectral Density (PSD) requirement, which constraints power to 10dBm per MHz bandwidth at most.

According to some embodiments of the present application, for unlicensed spectra, a frequency range (e.g., a BWP, a carrier, a resource pool, etc. ) may be divided into multiple channels upon which a channel access procedure is defined. Each channel may be referred to as an RB set. Operating on the carrier may require guard bands between RB sets. In some embodiments, the size of the guard bands may be chosen such that no filtering is needed to ensure that transmission on one RB set does not cause significant interference to a neighboring RB set not available for transmission.

For example, the concept of "RB set" is specified in Release 16 5G NR in unlicensed spectrum (NR-U) , which defines the exact available RBs without RBs in either inter-cell guard band or intra-cell guard band. The guard band and RB set are configured by RRC signaling in unit of common resource block (CRB) . In detail, when a UE is configured with intraCellGuardBand for a carrier, the UE is provided with N_RB-set-1 intra-cell guard bands on the carrier, each defined by a start CRB and an end CRB, i.e.,andrespectively. The intra-cell guard bands separate N_RB-set RB sets, each defined by a start CRB and an end CRB, i.e., andrespectively. The UE determines and the remaining end and start CRBs as andWhen the UE is not configured with intraCellGuardBand, the UE determines intra-cell guard band and corresponding RB set according to the default intra-cell guard band pattern from TS38.101 corresponding to μ and carrier sizeThe specific definitions of the variables or parameters as mentioned above can be found in 3GPP standard documents.

As an example, a carrier wider than 20MHz may be divided into multiple 20MHz channels upon which a channel access procedure is defined. Each 20MHz channel may be referred to as one RB set.

The following Table 3 shows the number of RBs (e.g., N_RB) included in different bandwidths for different SCSs for frequency range 1 (FR1) (e.g., 450 MHz–7125 MHz) .

Table 3: Max transmission bandwidth configuration N_RB for FR1 (450 –7125 MHz)

Referring to Table 3, taking 20MHz bandwidth as an example, for 15kHz SCS, the 20MHz bandwidth includes 106 RBs (e.g., an RB set may include 106 RBs) ; for 30kHz SCS, the 20MHz bandwidth includes 51 RBs.

FIG. 3 illustrates an exemplary interlace RB-based structure (also referred to as interlace pattern) for 15kHz SCS in 20MHz bandwidth according to some embodiments of the present application. It should be understood that the interlace RB-based structure in FIG. 3 is only for illustrative purposes and should not be construed as limiting the embodiments of the present disclosure.

As shown in FIG. 3, the channel (e.g., RB set) with 20MHz bandwidth may include 106 RBs (e.g., denoted as RBs 0-105) , and the RBs of the channel are divided into 10 interlaces (denoted as interlaces #0-#9) . Within interlaces #0 to #5, each interlace contains 11 RBs. Within interlaces #6 to #9, each interlace contains 10 RBs.

Each interlace of the 10 interlaces may include evenly-spaced RBs in the frequency domain. As shown in FIG. 3, interlace #0 may include RB 0, RB 10, RB 20, RB 30, and so on; interlace #1 may include RB 1, RB 11, RB 21, RB 31, and so on;…; and interlace #9 may include RB 9, RB 19, RB 29, and so on.

According to some embodiments of the present application, multiple RB sets may be available for S-SSB transmission. For S-SSB, transmission across multiple RB sets may increase channel access opportunities in unlicensed spectra. In addition, multiple RB sets are beneficial for providing sufficient RBs for S-SSB transmission, especially for interlace RB-based S-SSB transmission. Therefore, new designs for related slot structures of S-SSB and UE behavior for S-SSB transmission (s) on multiple RB sets (or channels) are needed.

Given the above, embodiments of the present application provide solutions for multiple channel access for S-SSB transmission in unlicensed spectra. For example, embodiments of the present application provide several solutions regarding S-SSB slot structure and UE behavior for supporting S-SSB transmission (s) on multiple RB sets (or channels) , which may increase channel access opportunities and provide sufficient RBs for S-SSB transmission in unlicensed spectra. More details will be described in the following text in combination with the appended drawings.

FIG. 4 illustrates a flowchart of an exemplary method 400 for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some embodiments of the present application. The method 400 illustrated in FIG. 4 may be performed by a UE (e.g., UE 101a or UE 101b in FIG. 1) which intends to transmit at least S-SSB, or other apparatus with the like functions.

As shown in FIG. 4, in step 401, the UE may obtain first configuration information for multiple channel access on a first set of RB sets for S-SSB. For example, the UE may obtain the first configuration information based on configuration, pre-configuration, or pre-definition.

In some embodiments of the present application, the UE may obtain the first configuration information based on configuration. Specifically, obtaining the first configuration information based on configuration (i.e., the first configuration information is configured to the UE) may refer to that: the first configuration information is transmitted by a BS (e.g., BS 102 as shown in FIG. 1) to the UE via at least one of: a SIB message, a MIB message, an RRC signaling, or a MAC CE, or DCI, such that the UE may receive the first configuration information from the BS. In an embodiment of the present application, obtaining the first configuration information based on configuration may apply to the scenario where the UE is in coverage of a network.

In some other embodiments of the present application, the UE may obtain the first configuration information based on pre-configuration or pre-definition. Specifically, obtaining the first configuration information based on pre-configuration or pre-definition (i.e., the first configuration information is pre-configured or pre-defined to the UE) may refer to that: the first configuration information may be hard-wired into the UE or stored on a subscriber identity module (SIM) or universal subscriber identity module (USIM) card for the UE, such that the UE may obtain the first configuration information within the UE. In an embodiment of the present application, obtaining the first configuration information based on pre-configuration or pre-definition may apply to the scenario where the UE is out of coverage of the network.

In some embodiments of the present application, the first configuration information may be determined based on BWP, carrier, resource pool, or frequency range. That is, the first configuration information may be configured, pre-configured, or pre-defined per BWP, per carrier, per resource pool, or per frequency range.

In some embodiments of the present application, the first configuration information may indicate the first set of RB sets (e.g., denoted as C_S-SSB) . C_S-SSB may indicate all RB sets for S-SSB transmission within a frequency range (e.g., a BWP, a carrier, a resource pool, etc. ) . C_S-SSB may include at least two RB sets, i.e., |C_S-SSB|≥2. C_S-SSB may be a subset of C_All, wherein C_All may indicate all RB sets within the frequency range. For example, within a BWP including four or even more RB sets, only two or three of them are indicated as elements of C_S-SSB by the first configuration information for S-SSB transmission. This design aims at limiting the number of RB sets for S-SSB transmission and thus can decrease the consumption for both transmitting S-SSB and receiving S-SSB.

In some embodiments of the present application, the first set of RB sets may be determined based on BWP, carrier, resource pool, or frequency range. That is, the first set of RB sets may be configured, pre-configured, or pre-defined per BWP, per carrier, per resource pool, or per frequency range.

In some embodiments of the present application, the first configuration information may also include one of the following:

· second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB;

· third configuration information for supporting S-SSB structure spanning over N1 RB sets, wherein N1 is an integer greater than one;

· fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets;

· fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween, wherein N2 is an integer greater than one; and

· sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N3 is an integer greater than one.

The definition regarding each of the above items included in the first configuration information will be described in detail later with reference to Embodiments 1-5.

In step 403, the UE may determine a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets. The specific operations performed in step 403 will be described in detail later with reference to Embodiments 1-5.

In step 405, the UE may transmit S-SSB on at least one RB set within the determined second set of RB sets. The specific operations performed in step 405 will be described in detail later with reference to Embodiments 1-5.

The following Embodiments 1-5 provide various exemplary solutions for transmission (s) of S-SSB on multiple RB sets (or channels) , depending on at least one of the followings:

· Whether guard bands between RB sets are used for S-SSB transmission or not;

· Whether slot structures for S-SSB on different RB sets are identical or not;

· Whether S-SSB period boundaries for different RB sets are aligned or not; or

· Which multi-channel access procedures are used for S-SSB transmission.

Embodiment 1

In Embodiment 1, guard bands between RB sets are not used for S-SSB transmission and one S-SSB occasion is configured per RB set. That is, in the frequency domain, one S-SSB occasion spans within one RB set. In Embodiment 1, the S-SSB occasion is configured, transmitted, and detected per RB set.

In Embodiment 1, the first configuration information obtained in step 401 may include the second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB.

In some examples of Embodiment 1, an interlace RB-based transmission scheme may be applied for S-SSB transmission. Then, the second configuration information may indicate interlace (s) available for S-SSB transmission within each RB set of the first set of RB sets. For example, the second configuration information may indicate index (es) of interlace (s) available for S-SSB transmission within each RB set of the first set of RB sets. The index (es) of interlace (s) available for S-SSB transmission may be either identical or different in different RB sets. In such examples, in the time domain, an S-SSB (or an S-SSB occasion) may follow a slot structure as specified in 3GPP (e.g., Release 16 and Release 17) for S-SSB, e.g., the slot structure for S-SSB illustrated in FIG. 2.

FIG. 5 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple RB sets according to some embodiments of the present application, which may be applied in Embodiment 1.

In the example of FIG. 5, a frequency range may be divided into multiple RB sets. For simplicity, FIG. 5 illustrates two adjacent RB sets in the multiple RB sets, which are denoted as RB set #n and RB set #n+1, respectively. RB set #n and RB set #n+1 may be included in the first set of RB sets for SSB. A guard band, which is not used for S-SSB transmission, may be located between RB set #n and RB set #n+1.

Referring to FIG. 5, in the time domain, one slot may include one S-SSB occasion. In the example of FIG. 5, the slot structure for S-SSB illustrated in FIG. 2 is used. In the frequency domain, an interlace RB-based transmission is applied for S-SSB and one S-SSB occasion spans within one RB set. For example, the second configuration information may indicate that interlace #m in RB set #n is available for S-SSB transmission and interlace #m1 in RB set #n+1 is available for S-SSB transmission. The second configuration information may also indicate interlace (s) available for S-SSB transmission within other RB set (s) within the first set of RB sets, although not shown in FIG. 5.

In some other examples of Embodiment 1, a cluster-based transmission scheme may be applied for S-SSB transmission. That is, one S-SSB occasion may include two or more clusters, and different clusters may be used to carry different S-SSB components by utilizing a plurality of contiguous RBs. The frequency range spanned by S-SSB may meet OCB requirement per RB set. For example, in the time domain, within each RB set of the first set of RB sets, a slot may include at least one S-SSB occasion, and each S-SSB occasion may include two or more clusters. Then, the second configuration information may indicate contiguous RBs and symbols of each cluster and S-SSB component (s) carried by each cluster of the at least one S-SSB occasion in each RB set of the first set of RB sets.

FIG. 6 illustrates an exemplary cluster-based slot structure for S-SSB on multiple RB sets according to some embodiments of the present application, which may be applied in Embodiment 1.

In the example of FIG. 6, a frequency range may be divided into multiple RB sets. For simplicity, FIG. 6 illustrates two adjacent RB sets in the multiple RB sets, which are denoted as RB set #n and RB set #n+1, respectively. RB set #n and RB set #n+1 may be included in the first set of RB sets for SSB. A guard band, which is not used for S-SSB transmission, may be located between RB set #n and RB set #n+1.

Referring to FIG. 6, within each RB set, in the time domain, a slot may include at least one S-SSB occasion, each of which may be carried by 7 symbols. For simplicity, the example of FIG. 6 only shows one S-SSB occasion in the slot within each RB set. It is contemplated that the S-SSB occasion in the slot may be carried by a different number of symbols in other examples.

In the frequency domain, a cluster-based transmission is applied for S-SSB and one S-SSB occasion spans within one RB set. For simplicity, the example of FIG. 6 only shows that one S-SSB occasion includes two clusters. The frequency range spanned by S-SSB meets OCB requirement per RB set.

The second configuration information may indicate that each cluster of the two clusters includes 7 symbols (e.g., symbols #0-#6 in the slot) in the time domain and indicate a plurality of contiguous RBs for each cluster of the two clusters.

In addition, the second configuration information may also indicate S-SSB component (s) carried by each cluster of the two clusters. For example, the second configuration information may indicate that: in the cluster located close to the lower end of each RB set, the first symbol is used to carry PSBCH with AGC purpose, the second and third symbols are used to carry S-PSS, the fourth and fifth symbols are used to carry S-SSS, and the sixth symbol is used to carry PSBCH; in the cluster located close to the higher end of each RB set, all the six symbols are used to carry PSBCH, wherein the first symbol is also for AGC purpose. The seventh symbol in each cluster of the two clusters is used as a guard symbol.

Comparing with the interlace RB-based transmission scheme (e.g., as shown in FIG. 5) , the cluster-based transmission scheme (e.g., as shown in FIG. 6) may reduce the number of symbols occupied by one S-SSB occasion.

In some cases of Embodiment 1, the first configuration information may also include at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission.

In some embodiments, the one or more CAPC values may be specific for S-SSB, which may be different from CAPC value (s) for SL transmission (e.g., at least one of physical sidelink control channel (PSCCH) transmission or physical sidelink shared channel (PSSCH) transmission) within the first set of RB sets. In an embodiment, a CAPC value may be configured, pre-configured, or pre-defined per RB set. That is, the first configuration information may include a corresponding CAPC value for each RB set of the first set of RB sets. In another embodiment, the first configuration information may include one or more CAPC values for the first set of RB sets, and a CAPC value for an RB set within the first set of RB sets may be randomly selected from the one or more CAPC values by the UE.

A CPE value may represent a length of a CPE, which may be greater than or equal to 0. The CPE may be transmitted by the UE to occupy a channel until the beginning of a target transmission (e.g., at least one of S-SSB transmission or SL transmission) when the channel is determined to be available based on an LBT procedure before the beginning of the target transmission. What is transmitted in the CPE may include a repetition of cyclic prefix (CP) of the first symbol within the target transmission.

In some embodiments, the one or more CPE values may be specific for S-SSB, which may be different from CAPC value (s) for SL transmission (e.g., at least one of PSCCH transmission or PSSCH transmission) within the first set of RB sets. In an embodiment, a CPE value may be configured, pre-configured, or pre-defined per RB set. That is, the first configuration information may include a corresponding CPE value for each RB set of the first set of RB sets. In another embodiment, the first configuration information may include one or more CPE values for the first set of RB sets, and a CPE value for an RB set within the first set of RB sets may be randomly selected from the one or more CPE values by the UE.

In Embodiment 1, if the UE intends to transmit S-SSB on an S-SSB occasion, the UE may perform a multi-channel access procedure on the first set of RB sets. For example, the multi-channel access procedure may include step 403, in which the UE may determine the second set of RB sets (e.g., denoted as C^*) available for S-SSB transmission based on the obtained first configuration information.

The second set of RB sets may be determined based on the following Type A multi-channel access procedure or Type B multi-channel access procedure.

In the Type A multi-channel access procedure, the UE may perform channel access before an S-SSB occasion on each RB set c_i∈C_S-SSB (C_S-SSB is the first set of RB sets) according to a Type-1 channel access procedure independently.

For example, the UE may perform a Type-1 channel access procedure on each RB set within the first set of RB sets according to a CAPC value for the RB set. The CAPC value may be within the one or more CAPC values included in the first configuration information. As stated above, the CAPC value for each RB set may be configured, pre-configured, or pre-defined for the respective RB set or may be randomly selected from one or more CAPC values configured, pre-configured, or pre-defined for the first set of RB sets. Then, the UE may determine the second set of RB sets to include all RB set (s) that is (are) within the first set of RB sets and identified to be idle based on the Type-1 channel access procedure.

In the Type B multi-channel access procedure, firstly, the UE may select a first RB set (which may be any RB set within the first set of RB sets) within the first set of RB sets, and perform a Type-1 channel access procedure on the first RB set according to a CAPC value for the first RB set, wherein the CAPC value may be within the one or more CAPC values included in the first configuration information. As stated above, the CAPC value for the first RB set may be configured, pre-configured, or pre-defined for the first RB set or may be randomly selected from one or more CAPC values configured, pre-configured, or pre-defined for the first set of RB sets. In the case that the first RB set is identified to be idle based on the Type-1 channel access procedure, the UE may perform a Type 2A channel access procedure on each of remaining RB set (s) within the first set of RB sets before (e.g., immediately before) availability for transmitting on the first RB set. Then, the UE may determine the second set of RB sets to include the first RB set and all RB set (s) that is (are) within the remaining RB set (s) and identified to be idle based on the Type 2A channel access procedure.

For example, in the Type B multi-channel access procedure, the UE may perform as follows:

· The UE selects one RB set c_j from C_S-SSB by uniformly randomly choosing, and performs channel access before an S-SSB occasion on the RB set c_j according to a Type-1 channel access procedure.

· The UE performs channel access before an S-SSB occasion on RB set c_i≠c_j, c_i∈C_S-SSB according to a Type-2A channel access procedure (e.g., sensing for at least a sensing interval T_mc=25us) immediately before availability for transmitting on the RB set c_j by the UE, and the UE obtains an access opportunity on the RB set c_i immediately after sensing the RB set c_i to be idle for at least the sensing interval T_mc. The RB set c_i is considered to be idle for T_mc if the RB set c_i is sensed to be idle during all the time durations in which such idle sensing is performed on the RB set c_j in the given interval T_mc.

In some embodiments of the present application, the Type B multi-channel access procedure may be a default procedure for the UE. That is, without an explicit indication, the UE may select the Type B multi-channel access procedure. The Type B multi-channel access procedure is beneficial in power saving for the UE performing S-SSB transmission.

After determining the second set of RB sets, in step 405, the UE may transmit S-SSB on at least one RB set within the determined second set of RB sets. The slot structure of the S-SSB in each of the at least one RB set may be based on the second configuration information as described above.

In some embodiments, the UE may transmit S-SSB at least on the lowest or highest RB set within the second set of RB sets.

Embodiment 2

In Embodiment 2, guard bands between RB sets are not used for S-SSB transmission and one S-SSB occasion spans over multiple RB sets in the frequency domain. In Embodiment 2, the S-SSB occasion is configured, transmitted, and detected spanning over N1 (N1≥2) RB sets.

In Embodiment 2, the first configuration information obtained in step 401 may include the third configuration information for supporting S-SSB structure spanning over N1 RB sets. For example, the third configuration information may indicate a slot structure of S-SSB within each RB set of the N1 RB sets. The N1 RB sets may be adjacent or not adjacent.

The slot structure of S-SSB within each RB set of the N1 RB sets may include the time domain structure of S-SSB within each RB set of the N1 RB sets and the frequency domain structure of S-SSB within each RB set of the N1 RB sets.

In some examples of Embodiment 2, an interlace RB-based transmission scheme may be applied for S-SSB transmission. Then, in the frequency domain, the third configuration information may indicate interlace (s) available for S-SSB transmission within each RB set of the N1 RB sets. For example, the third configuration information may indicate index (es) of interlace (s) available for S-SSB transmission within each RB set of the N1 RB sets. The index (es) of interlace (s) available for S-SSB transmission may be either identical or different in different RB sets. In the time domain, a slot may include at least one S-SSB occasion. The third configuration information may indicate symbols included in each S-SSB occasion and S-SSB component (s) carried by these symbols.

FIG. 7 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple RB sets according to some embodiments of the present application, which may be applied in Embodiment 2.

In the example of FIG. 7, a frequency range may be divided into multiple RB sets and N1=2. FIG. 7 illustrates two RB sets (e.g., denoted as RB set #n and RB set #n+1, respectively) in the multiple RB sets which may be used for transmitting S-SSB. A guard band, which is not used for S-SSB transmission, may be located between RB set #n and RB set #n+1. In the example of FIG. 7, RB set #n and RB set #n+1 are two adjacent RB sets. However, in some other examples, the two RB sets may be not adjacent.

Referring to FIG. 7, in the frequency domain, an interlace RB-based transmission is applied for S-SSB and one S-SSB occasion spans over two RB sets. For example, the third configuration information may indicate that interlace #m in RB set #n is available for S-SSB transmission and interlace #m1 in RB set #n+1 is available for S-SSB transmission.

In the time domain, within each RB set, a slot may include at least one S-SSB occasion, each of which may be carried by 7 symbols. For simplicity, the example of FIG. 7 only shows one S-SSB occasion in the slot. It is contemplated that the S-SSB occasion in the slot may be carried by a different number of symbols in other examples. The third configuration information may indicate that one S-SSB occasion includes 7 symbols (e.g., symbols #0-#6 in the slot) in the time domain. In addition, the third configuration information may also indicate S-SSB component carried by each symbol in each RB set of the two RB sets. For example, the third configuration information may indicate that: in the lower RB set of the two RB sets (e.g., RB set #n) , the first symbol is used to carry PSBCH with AGC purpose, the second and third symbols are used to carry S-PSS, the fourth and fifth symbols are used to carry S-SSS, and the sixth symbol is used to carry PSBCH; in the higher RB set of the two RB sets (e.g., RB set #n+1) , all the six symbols are used to carry PSBCH, wherein the first symbol is also for AGC purpose. The seventh symbol in each RB set of the two RB sets is used as a guard symbol.

In some other examples of Embodiment 2, a cluster-based transmission scheme may be applied for S-SSB transmission. For example, in the time domain, within each RB set of the N1 RB sets, a slot may include at least one S-SSB occasion, and each S-SSB occasion may include two or more clusters. The third configuration information may indicate contiguous RBs and symbols of each cluster and S-SSB component (s) carried by each cluster of the at least one S-SSB occasion in each RB set of the N1 RB sets. In the frequency domain, the frequency range spanned by S-SSB may meet the OCB requirement per RB set.

FIG. 8 illustrates an exemplary cluster-based slot structure for S-SSB on multiple RB sets according to some other embodiments of the present application, which may be applied in Embodiment 2.

In the example of FIG. 8, a frequency range may be divided into multiple RB sets and N1=2. FIG. 8 illustrates two RB sets (e.g., denoted as RB set #n and RB set #n+1, respectively) in the multiple RB sets which may be used for transmitting S-SSB. A guard band, which is not used for S-SSB transmission, may be located between RB set #n and RB set #n+1. In the example of FIG. 8, RB set #n and RB set #n+1 are two adjacent RB sets. However, in some other examples, the two RB sets may be not adjacent.

Referring to FIG. 8, within each RB set, in the time domain, a slot may include at least one S-SSB occasion, each of which may be carried by 7 symbols. For simplicity, the example of FIG. 8 only shows one S-SSB occasion in the slot. It is contemplated that the S-SSB occasion in the slot may be carried by a different number of symbols in other examples.

In the frequency domain, a cluster-based transmission is applied for S-SSB and one S-SSB occasion spans over two RB sets. For simplicity, the example of FIG. 8 only shows that one S-SSB occasion within each RB set includes two clusters. The frequency range spanned by S-SSB meets OCB requirement per RB set.

The third configuration information may indicate that each cluster of the two clusters in each RB set of the two RB sets includes 7 symbols (e.g., symbols #0-#6 in the slot) in the time domain and indicate a plurality of contiguous RBs for each cluster of the two clusters in each RB set of the two RB sets.

In addition, the third configuration information may also indicate S-SSB component carried by each cluster of the two clusters in each RB set of the two RB sets. For example, the third configuration information may indicate that: in each cluster of the lower RB set of the two RB sets (e.g., RB set #n) , the first symbol is used to carry PSBCH with AGC purpose, the second and third symbols are used to carry S-PSS, the fourth and fifth symbols are used to carry S-SSS, and the sixth symbol is used to carry PSBCH; in each cluster of the higher RB set of the two RB sets (e.g., RB set #n+1) , all the six symbols are used to carry PSBCH, wherein the first symbol is also for AGC purpose. The seventh symbol in each RB set of the two RB sets is used as a guard symbol.

The above structures in Embodiment 2 are beneficial in reducing the number of symbols occupied by one S-SSB occasion, even for the interlace RB-based transmission scheme (e.g., compared with that as shown in FIG. 5) .

In some embodiments, using a pair of RB sets for S-SSB transmission (e.g., N1=2) is beneficial for providing good balance between high channel access opportunity and low spectrum cost.

In some cases of Embodiment 2, the first configuration information may also include at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission. The definitions regarding the one or more CAPC values and the one or more CPE values provided in Embodiment 1 may also apply here.

In Embodiment 2, if the UE intends to transmit S-SSB on an S-SSB occasion, in step 403, the UE may determine the second set of RB sets (e.g., denoted as C^*) available for S-SSB transmission based on the obtained first configuration information by performing the same operations as those described in Embodiment 1.

After determining the second set of RB sets, in step 405, the UE may transmit S-SSB on N1 RB sets within the determined second set of RB sets. For example, the UE may transmit S-SSB on the lowest or highest N1 RB sets within the determined second set of RB sets based on the third configuration information. The slot structure for the S-SSB on the N1 RB sets may be based on the third configuration information as described above. For example, the slot structure for S-SSB may be mapped to RBs available for S-SSB in the N1 RB sets in an ascending or descending order.

Embodiment 3

In Embodiment 3, S-SSB period boundaries for different RB sets may be not aligned. That is, there may be a time offset (e.g., denoted as T_Offset, PB) between starting (or starting boundaries) of S-SSB periods from different RB sets.

This design is beneficial in the following perspectives. On one hand, it can increase the density of S-SSB occasions in the time domain, without increasing the number of S-SSB occasions in each RB set and thus decreasing the impact of S-SSB transmission on COT-based SL transmission. On the other hand, the above design can increase channel access opportunity for S-SSB compared to the case where S-SSB periods for different RB sets are aligned.

In Embodiment 3, the first configuration information obtained in step 401 may include the fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets. For example, the fourth configuration information may indicate a non-zero time offset (e.g., T_Offset, PB) between starting boundaries of S-SSB periods from at least two RB sets within the first set of RB sets, 0<T_Offset, PB<L_{S-SSB Period}, wherein L_{S-SSB Period} indicates a length of an S-SSB period.

In some embodiments, the non-zero time offset may be explicitly indicated by the fourth configuration information. For example, the fourth configuration information may directly indicate time offset (s) between starting boundaries of at least two S-SSB periods from at least two RB sets within the first set of RB sets.

In some other embodiments, the non-zero time offset may be implicitly indicated by the fourth configuration information. For example, for each RB set within the first set of RB sets, the fourth configuration information may indicate a time offset of a starting boundary of a corresponding S-SSB period relative to an identical reference point (e.g., starting of the first fame) .

Within each RB set of the first set of RB sets, the S-SSB occasions may be distributed by following any distribution structure as specified in 3GPP (e.g., Release 15, Release 16, Release 17, Release 18 and so on) . For example, the distribution of S-SSB occasions within each RB set of the first set of RB sets may be determined based on the following parameters:

· "S-SSB period" which indicates a length of an S-SSB period;

· "T_Offset" which indicates an offset between the starting of the S-SSB period and the first S-SSB occasion within the S-SSB period;

· "T_Interval" which indicates an interval between two adjacent S-SSB occasions; and

· "M1" which indicates the number of S-SSB occasions within one S-SSB period.

In some cases of Embodiment 3, the fourth configuration information may also indicate a slot structure of S-SSB within each RB set of the first set of RB sets. For example, all the information included in the second configuration information described in Embodiment 1 may also be included in the fourth configuration information, and the slot structures for S-SSB within each RB set as described in Embodiment 1 may also apply, except that S-SSB occasions on different RB sets may be in different locations in the time domain in Embodiment 3.

FIG. 9 illustrates an exemplary time domain distribution of S-SSB occasions over multiple RB sets according to some embodiments of the present application.

In the example of FIG. 9, a frequency range may be divided into multiple RB sets. For simplicity, FIG. 9 illustrates two adjacent RB sets in the multiple RB sets, which are denoted as RB set #n and RB set #n+1, respectively. A guard band may be located between RB set #n and RB set #n+1.

The distribution of S-SSB occasions within each RB set may be determined based on "S-SSB period, " "T_Offset, " "T_Interval, " and "M1" as described above, wherein each S-SSB occasion may be indicated by an index of N_i, i∈ [0, .., M1-1] .

The fourth configuration information may indicate a non-zero time offset (e.g., denoted as T_Offset, _PB) between the starting boundaries of S-SSB periods from the two RB sets.

In some cases of Embodiment 3, the first configuration information may also include at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission. The definitions regarding the one or more CAPC values and the one or more CPE values provided in Embodiment 1 may also apply here.

In Embodiment 3, if the UE intends to transmit S-SSB on an S-SSB occasion, in step 403, the UE may determine the second set of RB sets (e.g., denoted as C^*) available for S-SSB transmission based on the obtained first configuration information. For example, in some cases of Embodiment 3, at least two S-SSB occasions from at least two RB sets may be in the same location in the time domain. In such cases, the UE may perform a Type A multi-channel access procedure or a Type B multi-channel access procedure as described in Embodiment 1 to determine the second set of RB sets from the at least two RB sets. After determining the second set of RB sets, in step 405, the UE may transmit S-SSB on at least one RB set within the determined second set of RB sets. For example, the UE may transmit S-SSB on the lowest or highest RB set within the determined second set of RB sets based on the fourth configuration information. The slot structure for the S-SSB on the lowest or highest RB set may be based on the fourth configuration information as described above.

In some cases of Embodiment 3, all the S-SSB occasions from the first set of RB sets may be in different locations in the time domain. In such cases, if the UE intends to transmit S-SSB on an S-SSB occasion in an RB set, the UE may perform a Type-1 channel access procedure on the RB set based on a CAPC value for the RB set. The CAPC value may be within the one or more CAPC values included in the first configuration information. As stated above, the CAPC value for the RB set may be configured, pre-configured, or pre-defined for the RB set or may be randomly selected from one or more RB sets configured, pre-configured, or pre-defined for the first set of RB sets. In the case that the RB set is identified to be idle based on the Type-1 channel access procedure, the second set of RB sets includes only the RB set, and then in step 405, the UE may transmit S-SSB on the RB set.

Embodiment 4

In Embodiment 4, guard band (s) between RB sets may be used for S-SSB transmission and one S-SSB occasion spans over multiple RB sets in the frequency domain. In Embodiment 4, the S-SSB occasion is configured, transmitted, and detected spanning over N2 (N2≥2) adjacent RB sets and guard band (s) therebetween.

In Embodiment 4, the first configuration information obtained in step 401 may include the fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween. For example, the fifth configuration information may indicate: RB (s) available for S-SSB transmission within the guard band (s) ; and a slot structure of S-SSB spanning over the N2 adjacent RB sets and the guard band (s) therebetween.

In some embodiments, the information included in the third configuration information described in Embodiment 2 may also be included in the fifth configuration information. In addition, the fifth configuration information may further indicate a slot structure of S-SSB in the guard band (s) . For example, the fifth configuration information may further indicate symbols in the guard band (s) for S-SSB transmission and S-SSB component (s) carried by the symbols in the guard band (s) .

FIG. 10 illustrates an exemplary interlace RB-based slot structure for S-SSB on multiple adjacent RB sets and guard band (s) therebetween according to some embodiments of the present application.

In the example of FIG. 10, a frequency range may be divided into multiple RB sets and N2=2. FIG. 10 illustrates two adjacent RB sets (e.g., denoted as RB set #n and RB set #n+1, respectively) in the multiple RB sets which may be used for transmitting S-SSB. A guard band is located between RB set #n and RB set #n+1, and can also be used for S-SSB transmission.

Referring to FIG. 10, in the frequency domain, an interlace RB-based transmission is applied for S-SSB and one S-SSB occasion spans over two RB sets and the guard band therebetween. For example, the fifth configuration information may indicate that interlace #m in RB set #n is available for S-SSB transmission and interlace #m1 in RB set #n+1 is available for S-SSB transmission. The fifth configuration information may also indicate RB (s) available for S-SSB transmission within the guard band. The guard band locates between the two RB sets can be used to provide sufficient RBs for S-SSB transmission. For example, if interlace #m in RB set #n contains only 10 RBs, but S-PSS and S-SSS needs 11 RBs, then the fifth configuration information may indicate one RB in the guard band available for S-SSB transmission.

In the time domain, within each RB set and the guard band, a slot may include at least one S-SSB occasion, each of which may be carried by 7 symbols. For simplicity, the example of FIG. 10 only shows one S-SSB occasion in the slot. It is contemplated that the S-SSB occasion in the slot may be carried by a different number of symbols in other examples. The fifth configuration information may indicate that one S-SSB occasion includes 7 symbols (e.g., symbols #0-#6 in the slot) in the time domain. In addition, the fifth configuration information may also indicate S-SSB component carried by each symbol in each RB set of the two RB sets and the guard band. For example, the fifth configuration information may indicate that: in the lower RB set of the two RB sets (e.g., RB set #n) and the guard band, the first symbol is used to carry PSBCH with AGC purpose, the second and third symbols are used to carry S-PSS, the fourth and fifth symbols are used to carry S-SSS, and the sixth symbol is used to carry PSBCH; in the higher RB set of the two RB sets (e.g., RB set #n+1) , all the six symbols are used to carry PSBCH, wherein the first symbol is also for AGC purpose. The seventh symbol in each RB set of the two RB sets and the guard band are used as a guard symbol.

In some cases of Embodiment 4, the first configuration information may also include at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission. The definitions regarding the one or more CAPC values and the one or more CPE values provided in Embodiment 1 may also apply here.

In Embodiment 4, if the UE intends to transmit S-SSB on an S-SSB occasion, in step 403, the UE may determine the second set of RB sets (e.g., denoted as C^*) available for S-SSB transmission based on the obtained first configuration information by performing the same operations as those described in Embodiment 1.

After determining the second set of RB sets, in step 405, the UE may transmit S-SSB on N2 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween. For example, the UE may transmit S-SSB on the lowest or highest N2 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween based on the fifth configuration information. The slot structure for the S-SSB on the N2 adjacent RB sets and the guard band (s) therebetween may be based on the fifth configuration information as described above. For example, the slot structure for S-SSB may be mapped to RBs available for S-SSB in the N2 adjacent RB sets and guard band (s) therebetween in an ascending or descending order.

Embodiment 5

In Embodiment 5, guard band (s) between RB sets may be used for S-SSB transmission and FDMed S-SSB and SL transmission (or FDM of S-SSB and SL transmission) spans over multiple RB sets in the frequency domain. In Embodiment 5, FDMed S-SSB and SL transmission is configured, transmitted, and detected spanning over N3 (N3≥2) adjacent RB sets and guard band (s) therebetween.

In Embodiment 5, the first configuration information obtained in step 401 may include the sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween. For example, the sixth configuration information may indicate: interlace (s) available for S-SSB transmission within at least one RB set of the N3 adjacent RB sets; interlace (s) available for SL transmission within remaining RB set (s) of the N3 adjacent RB sets; and RB (s) available for S-SSB transmission within the guard band (s) . In some examples, in the time domain, an S-SSB (or an S-SSB occasion) may follow a slot structure as specified in 3GPP (e.g., Release 16 and Release 17) for S-SSB, e.g., the slot structure for S-SSB illustrated in FIG. 2. An SL transmission may follow any slot structures as specified in 3GPP (e.g., Release 15, Release 16, Release 17, Release 18 and so on) for SL transmission.

In some embodiments, the at least one RB set including interlace (s) available for S-SSB transmission may be adjacent to the remaining RB set (s) including interlace (s) available for SL transmission, and the guard band (s) including RB (s) available for S-SSB transmission may include guard band (s) between adjacent ones in the at least one RB set and/or the guard band between an RB set in the at least one RB set and an adjacent RB set which is in the remaining RB set (s) . For example, the N3 adjacent RB sets and the guard band (s) therebetween may be divided into two parts, one part (e.g., the lower part in the frequency domain) may be used for S-SSB transmission, and the other part (e.g., the higher part in the frequency domain) may be used for SL transmission.

FIG. 11 illustrates an exemplary slot structure supporting FDMed S-SSB and SL transmission on multiple adjacent RB sets and guard band (s) therebetween according to some embodiments of the present application.

In the example of FIG. 11, a frequency range may be divided into multiple RB sets and N3=2. FIG. 11 illustrates two adjacent RB sets (e.g., denoted as RB set #n and RB set #n+1, respectively) in the multiple RB sets which may be used for FDMed S-SSB and SL transmission. A guard band is located between RB set #n and RB set #n+1, and can be used for S-SSB transmission.

Referring to FIG. 11, in the frequency domain, an interlace RB-based transmission is applied for S-SSB and SL transmission. The sixth configuration information may indicate that interlace #m in RB set #n is available for S-SSB transmission and interlace #m1 in RB set #n+1 is available for SL transmission. The fifth configuration information may also indicate RB (s) available for S-SSB transmission within the guard band between RB set #n and RB set #n+1. The guard band locates between the two RB sets can be used to provide sufficient RBs for S-SSB transmission. For example, if interlace #m in RB set #n contains only 10 RBs, but S-PSS and S-SSS needs 11 RBs, then the sixth configuration information may indicate one RB in the guard band available for S-SSB transmission.

In the time domain, an S-SSB (or an S-SSB occasion) may follow a slot structure as specified in 3GPP (e.g., Release 16 and Release 17) for S-SSB, e.g., the slot structure for S-SSB illustrated in FIG. 2. An SL transmission may follow any slot structures as specified in 3GPP (e.g., Release 15, Release 16, Release 17, Release 18 and so on) for SL transmission.

In some cases of Embodiment 5, the first configuration information may also include at least one of: one or more CAPC values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or one or more CPE values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission. The definitions regarding the one or more CAPC values and the one or more CPE values provided in Embodiment 1 may apply here.

In Embodiment 5, if the UE intends to transmit S-SSB on an S-SSB occasion, in step 403, the UE may also determine the second set of RB sets (e.g., denoted as C^*) available for S-SSB transmission based on the obtained first configuration information by performing the same operations as those described in Embodiment 1.

After determining the second set of RB sets, in step 405, the UE may transmit FDMed S-SSB and SL transmission on N3 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween. For example, the UE may transmit FDMed S-SSB and SL transmission on the lowest or highest N3 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween. The slot structure for the FDMed S-SSB and SL transmission on the N3 adjacent RB sets and the guard band (s) therebetween may be based on the sixth configuration information as described above. For example, the slot structure for the FDMed S-SSB and SL transmission may be mapped to RBs available for FDMed S-SSB and SL transmission in the N3 adjacent RB sets and guard band (s) therebetween in an ascending or descending order.

FIG. 12 illustrates a flowchart of an exemplary method 1200 for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some other embodiments of the present application. The method 1200 illustrated in FIG. 12 may be performed by a UE (e.g., UE 101a or UE 101b in FIG. 1) which intends to receive or detect at least S-SSB, or other apparatus with the like functions.

As shown in FIG. 12, in step 1201, the UE may obtain first configuration information for multiple channel access on a first set of RB sets for S-SSB. For example, the UE may obtain the first configuration information based on configuration, pre-configuration, or pre-definition.

All the definitions regarding configuration, pre-configuration, or pre-definition as provided above may also apply here. All the definitions regarding the first configuration information as provided above may also apply here. For example, the first configuration information may indicate the first set of RB sets and include one of the second configuration information, the third configuration information, the fourth configuration information, the fifth configuration information, and the sixth configuration information, as described above.

In step 1203, the UE may monitor the first set of RB sets to detect S-SSB on at least one RB set within the first set of RB sets based on the obtained first configuration information.

In some embodiments, the second or fourth configuration information may be included in the first configuration information. The UE may monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on one RB set of the first set of RB sets or until an end of the monitoring.

In some embodiments, the third configuration information may be included in the first configuration information. The UE may monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N1 RB sets of the first set of RB sets or until an end of the monitoring.

In some embodiments, the fifth configuration information is included in the first configuration information. The UE may monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N2 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring; or

In some embodiments, the sixth configuration information may be included in the first configuration information. The UE may monitor the first set of RB sets in an ascending or descending order until detecting FDMed S-SSB and SL transmission on N3 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring. In some examples of such embodiments (e.g., N3 =2) , the UE may first monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on one RB set of the first set of RB sets or until an end of the monitoring. In the case that the UE detects S-SSB on one RB set, then the UE may perform detection of SL transmission on the next RB set in the monitoring order.

According to some embodiments of the present application, a BS may transmit first configuration information to one or more UEs (e.g., UE 101a and UE 101b) . All the definitions regarding the first configuration information as described in the above embodiments may also apply here.

In an embodiment, the BS may transmit the first configuration information to the one or more UEs via at least one of: a MIB message, a SIB message, an RRC signaling, a MAC CE, or DCI.

FIG. 13 illustrates a simplified block diagram of an exemplary apparatus 1300 for multiple channel access for S-SSB transmission in an unlicensed spectrum according to some embodiments of the present application. In some embodiments, the apparatus 1300 may be or include at least part of a UE (e.g., UE 101a or UE 101b in FIG. 1) . In some other embodiments, the apparatus 1300 may be or include at least part of a BS (e.g., BS 102 in FIG. 1) .

Referring to FIG. 13, the apparatus 1300 may include at least one transceiver 1302 and at least one processor 1306. The at least one transceiver 1302 is coupled to the at least one processor 1306.

Although in this figure, elements such as the transceiver 1302 and the processor 1306 are illustrated in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 1302 may be divided into two devices, such as receiving circuitry (or a receiver) and transmitting circuitry (or a transmitter) . In some embodiments of the present application, the apparatus 1300 may further include an input device, a memory, and/or other components. The transceiver 1302 and the processor 1306 may be configured to perform any of the methods described herein (e.g., the methods described with respect to FIGS. 4-12 or other methods described in the embodiments of the present application) .

According to some embodiments of the present application, the apparatus 1300 may be a UE which intends to transmit at least S-SSB, and the transceiver 1302 and the processor 1306 may be configured to perform operations of a UE in any of the methods as described with respect to FIGS. 4-11 or other methods described in the embodiments of the present application. For example, the processor 1306 is configured to: obtain first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; determine a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets; and transmit, via the transceiver 1302, S-SSB on at least one RB set within the determined second set of RB sets.

According to some embodiments of the present application, the apparatus 1300 may be a UE which intends to receive or detect at least S-SSB, and the transceiver 1302 and the processor 1306 may be configured to perform operations of a UE in any of the methods as described with respect to FIG. 12 or other methods described in the embodiments of the present application. For example, the processor 1306 is configured to: obtain first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; and monitor the first set of RB sets to detect S-SSB on at least one RB set within the first set of RB sets based on the obtained first configuration information.

According to some embodiments of the present application, the apparatus 1300 may be a BS, and the transceiver 1302 and the processor 1306 may be configured to perform operations of a BS described in the embodiments of the present application. For example, the processor 1306 is configured to: transmit, via the transceiver 1302, first configuration information for multiple channel access on a first set of RB sets for S-SSB, wherein the first configuration information indicates the first set of RB sets and includes one of the following: second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB; third configuration information for supporting S-SSB structure spanning over N1 RB sets; fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets; fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and sixth configuration information for supporting FDMed S-SSB and SL transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one.

In some embodiments of the present application, the apparatus 1300 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 1306 to implement any of the methods as described above. For example, the computer-executable instructions, when executed, may cause the processor 1306 to interact with the transceiver 1302, so as to perform operations of the methods, e.g., as described with respect to FIGS. 4-12 or other methods described in the embodiments of the present application.

The method according to any of the embodiments of the present application can also be implemented on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented on a general purpose 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 resides a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processor functions of this application. For example, an embodiment of the present application provides an apparatus for multiple channel access for S-SSB transmission, including a processor and a memory. Computer programmable instructions for implementing a method for multiple channel access for S-SSB transmission are stored in the memory, and the processor is configured to perform the computer programmable instructions to implement the method for multiple channel access for S-SSB transmission. The method for multiple channel access for S-SSB transmission may be any method as described in the present application.

An alternative embodiment preferably implements the 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 computer-executable components preferably integrated with a network security system. The non-transitory, computer-readable storage medium may be stored on any suitable computer readable media such as RAMs, ROMs, flash memory, EEPROMs, optical storage devices (CD or DVD) , hard drives, floppy drives, 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, an embodiment of the present application provides a non-transitory, computer-readable storage medium having computer programmable instructions stored therein. The computer programmable instructions are configured to implement a method for multiple channel access for S-SSB transmission according to any embodiment of the present application.

While this application has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the application by simply employing the elements of the independent claims. Accordingly, embodiments of the application as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the application.

In this disclosure, relational terms such as "first, " "second, " and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A user equipment (UE) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

obtain first configuration information for multiple channel access on a first set of resource block (RB) sets for sidelink synchronization signal block (S-SSB) , wherein the first configuration information indicates the first set of RB sets and includes one of the following:

second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB;

third configuration information for supporting S-SSB structure spanning over N1 RB sets;

fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets;

fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and

sixth configuration information for supporting frequency division multiplexed (FDMed) S-SSB and sidelink (SL) transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one;

determine a second set of RB sets available for S-SSB transmission based on the obtained first configuration information, wherein the second set of RB sets is a subset of the first set of RB sets; and

transmit, via the transceiver, S-SSB on at least one RB set within the determined second set of RB sets.
The UE of Claim 1, wherein the first set of RB sets is determined based on bandwidth part (BWP) , carrier, resource pool, or frequency range.
The UE of Claim 1, wherein the first configuration information further includes at least one of:

one or more channel access priority class (CAPC) values for performing Type-1 channel access procedure on the first set of RB sets for S-SSB transmission; or

one or more cyclic prefix extension (CPE) values for Type 2A channel access procedure on the first set of RB sets for S-SSB transmission.
The UE of Claim 3, wherein to determine the second set of RB sets, the processor is configured to:

perform a Type-1 channel access procedure on each RB set within the first set of RB sets according to a CAPC value within the one or more CAPC values; and

determine the second set of RB sets to include all RB set (s) within the first set of RB sets which is (are) identified to be idle based on the Type-1 channel access procedure.
The UE of Claim 3, wherein to determine the second set of RB sets, the processor is configured to:

select a first RB set within the first set of RB sets and perform a Type-1 channel access procedure on the first RB set according to a CAPC value within the one or more CAPC values; and

in the case that the first RB set is identified to be idle based on the Type-1 channel access procedure:

perform a Type 2A channel access procedure on each of remaining RB set (s) within the first set of RB sets before availability for transmitting on the first RB set; and

determine the second set of RB sets to include the first RB set and all RB set (s) within the remaining RB set (s) which is (are) identified to be idle based on the Type 2A channel access procedure.
The UE of Claim 1, wherein the second configuration information indicates one of:

interlace (s) available for S-SSB transmission within each RB set of the first set of RB sets; or

contiguous RBs and symbols of each cluster and S-SSB component (s) carried by each cluster located in each RB set of the first set of RB sets.
The UE of Claim 1, in the case that the second or fourth configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on a lowest or highest RB set within the determined second set of RB sets based on the second or fourth configuration information, respectively.
The UE of Claim 1, wherein the third configuration information indicates:

a slot structure of S-SSB within each RB set of the N1 RB sets.
The UE of Claim 1, in the case that the third configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on lowest or highest N1 RB sets within the determined second set of RB sets based on the third configuration information.
The UE of Claim 1, wherein the fourth configuration information indicates a non-zero time offset between starting boundaries of S-SSB periods from at least two RB sets within the first set of RB sets.
The UE of Claim 1, wherein the fifth configuration information indicates:

RB(s) available for S-SSB transmission within the guard band (s) ; and

a slot structure of S-SSB spanning over the N2 adjacent RB sets and the guard band (s) .
The UE of Claim 1, in the case that the fifth configuration information is included in the first configuration information, the processor is configured to transmit S-SSB on lowest or highest N2 adjacent RB sets within the determined second set of RB sets and guard band (s) therebetween.
A user equipment (UE) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

obtain first configuration information for multiple channel access on a first set of resource block (RB) sets for sidelink synchronization signal block (S-SSB) , wherein the first configuration information indicates the first set of RB sets and includes one of the following:

second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB;

third configuration information for supporting S-SSB structure spanning over N1 RB sets;

fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets;

fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and

sixth configuration information for supporting frequency division multiplexed (FDMed) S-SSB and sidelink (SL) transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one; and

monitor the first set of RB sets to detect S-SSB on at least one RB set within the first set of RB sets based on the obtained first configuration information.
The UE of Claim 13, wherein the processor is configured to:

in the case that the second or fourth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on one RB set of the first set of RB sets or until an end of the monitoring;

in the case that the third configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N1 RB sets of the first set of RB sets or until an end of the monitoring;

in the case that the fifth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting S-SSB on N2 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring; or

in the case that the sixth configuration information is included in the first configuration information, monitor the first set of RB sets in an ascending or descending order until detecting FDMed S-SSB and SL transmission on N3 adjacent RB sets of the first set of RB sets and guard band (s) therebeween or until an end of the monitoring.
A base station (BS) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

transmit, via the transceiver, first configuration information for multiple channel access on a first set of resource block (RB) sets for sidelink synchronization signal block (S-SSB) , wherein the first configuration information indicates the first set of RB sets and includes one of the following:

second configuration information for supporting interlace RB-based transmission or cluster-based transmission for S-SSB;

third configuration information for supporting S-SSB structure spanning over N1 RB sets;

fourth configuration information indicating time domain distribution of S-SSB occasions over the first set of RB sets;

fifth configuration information for supporting S-SSB structure spanning over N2 adjacent RB sets and guard band (s) therebetween; and

sixth configuration information for supporting frequency division multiplexed (FDMed) S-SSB and sidelink (SL) transmission spanning over N3 adjacent RB sets and guard band (s) therebetween, wherein N1, N2, and N3 are integers greater than one.