Channel structure of sidelink synchronization signal block in listen before talk operation

Abstract

Systems, methods, apparatuses, or computer readable media for performing listen before talk (LBT) operations in sidelink communications are provided. A wireless communication device may perform an LBT operation with respect to a sidelink synchronization signal block (S-SSB), the S-SSB having a first portion and a second portion. The first portion may repeat one or more symbols of the second portion according to a configuration of the second portion. The wireless communication device may determine a failure of LBT operation at a first point of the S-SSB. The wireless communication device may determine success of the LBT operation at a second point of the S-SSB, the second point after the first point. In response to the success, the wireless communication device may transmit at least a portion of the S-SSB that is mapped to one or more time domain resources starting from the second point.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, including but not limited to systems and methods for performing listen-before-talk (LBT) operations in secondary link communications. Background Art

[0002] The third generation partnership project (3GPP), a standards organization, is currently specifying a new radio interface called 5G New Radio (5GNR) and the next generation packet core network (NG-CN or NGC). 5G NR will have three main components: 5G access network (5G-AN), 5G core network (5GC) and user equipment (UE). To facilitate the implementation of different data services and requirements, the elements of 5GC (also known as network functions) have been simplified, and some of them are software-based so that they can be adjusted as needed. Summary of the invention

[0003] The example embodiments disclosed herein are intended to solve problems related to one or more problems arising in the prior art, and to provide additional features, which will become apparent by reference to the detailed description below in conjunction with the accompanying drawings. According to various embodiments, example systems, methods, devices, and computer program products are disclosed herein. However, it should be understood that these embodiments are presented by way of example, not by way of limitation, and that it will be apparent to those of ordinary skill in the art who read this disclosure that various modifications may be made to the disclosed embodiments while remaining within the scope of this disclosure.

[0004] At least one aspect relates to a system, method, apparatus, or computer-readable medium for performing a listen-before-talk (LBT) operation in a sidelink communication. A wireless communication device may perform an LBT operation on a sidelink synchronization signal block (S-SSB), the S-SSB having a first portion and a second portion. The first portion may repeat one or more symbols of the second portion according to a configuration of the second portion. The wireless communication device may determine a failure of the LBT operation at a first point of the S-SSB. The wireless communication device may determine a success of the LBT operation at a second point of the S-SSB, the second point being after the first point. In response to the success, the wireless communication device may transmit at least a portion of the S-SSB, the portion being mapped to one or more time domain resources starting from the second point.

[0005] In some embodiments, the wireless communication device may determine a second failure of the LBT operation at a third point of the S-SSB, the third point being after the first point. In some embodiments, in response to the second failure, the wireless communication device may transmit a second portion of the S-SSB, the second portion having one or more second time domain resources after the first point. In some embodiments, in response to success at the second point, the wireless communication device may discard a second portion of the S-SSB, the second portion having one or more second time domain resources starting from the second point. In some embodiments, the wireless communication device may determine a success of the LBT operation at a third point of the S-SSB, the third point being after the first point. In some embodiments, in response to success at the third point, the wireless communication device may transmit a second portion of the S-SSB, the second portion having one or more second time domain resources starting from the third point.

[0006] In some embodiments, the first part of the S-SSB may repeat one or more symbols of a type among multiple types, which is one of multiple types used for sublink synchronization. The multiple types may include at least one of a sublink primary synchronization signal (S-PSS) or a sublink secondary synchronization signal (S-SSS). In some embodiments, the first part of the S-SSB may repeat one or more symbols of the second part according to the configuration of the first part. In some embodiments, the first part of the S-SSB may repeat one or more symbols of the second part starting from an initial symbol index and ending at an end symbol index, and the end symbol index is before the initial symbol of the physical sublink broadcast channel (PSBCH).

[0007] In some embodiments, the transmission of S-SSBs may be applied only to the second S-SSB set. In some embodiments, the second S-SSB set may be located on a time slot that is not mapped by the resource pool association bitmap. In some embodiments, when the second point corresponds to the initial symbol index, the entire first S-SSB set may be transmitted. In some embodiments, the first S-SSB set is located on a time slot mapped by the resource pool association bitmap. In some embodiments, only a single starting point of the PSSCH / PSCCH may be configured or predefined / used on a time slot where the first S-SSB set is transmitted / configured / predefined.

[0008] In some embodiments, in response to success at a second point corresponding to the initial symbol index, the wireless communication device may transmit the entire S-SSB, the entire S-SSB being mapped to one or more time domain resources. In some embodiments, the wireless communication device may discard at least one initial symbol corresponding to the initial symbol index in transmission in response to (i) LBT failure at a first point corresponding to the initial symbol index and (ii) LBT success at a second point corresponding to at least one index after the initial symbol index. In some embodiments, in response to (i) LBT failure at a first point and (ii) success at a second point corresponding to a multiple of 9μs or 16μs after the first point, the wireless communication device may discard at least some time domain resources in transmission that are multiples of 9μs or 16μs after the first point.

[0009] In some embodiments, based on at least one of the number of symbols used for mapping, the subcarrier spacing, the number of RBs, or the number of interleavings, the first part of the S-SSB may repeat a repetition range corresponding to one or more symbols of the second part. In some embodiments, the first number of S-SSBs that do not belong to the resource pool and the second number of S-SSBs that belong to the resource pool may be configured or predefined, respectively. In some embodiments, the mapping ratio between the first number of S-SSBs that do not belong to the resource pool and the second number of S-SSBs that belong to the resource pool may be configured or predefined.

[0010] In some embodiments, the first number defined within a set of resource blocks (RBs) or a bandwidth part (BWP) may be different from or the same as the second number of symbols. In some embodiments, the first point and the second point may be identified from a plurality of candidate starting points for LBT operation. Each candidate starting point may be defined within at least one of a set of resource blocks (RBs) or a bandwidth part (BWP).

[0011] In some embodiments, a first number of candidate starting points for LBT operation in the first RB set may be less than a second number of candidate starting points for LBT operation in the second RB set. In some embodiments, a first position of at least one first candidate starting point for LBT operation in the first RB set may be earlier than a second position of at least one second candidate starting point for LBT operation in the second RB set. In some embodiments, a greater number of candidate starting points or an earlier position of the candidate starting points may correspond to a higher priority of the S-SSB or fewer LBT failures, the S-SSB being located in a time slot not mapped by the resource pool associated bitmap, or in a time slot mapped by the resource pool associated bitmap. In some embodiments, the above-mentioned S-SSB located in a time slot not mapped by the bitmap is associated with an SSB located in a time slot mapped by the bitmap. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various example embodiments of the present solution are described in detail below with reference to the following drawings or diagrams. The drawings are provided for illustrative purposes only and only depict example embodiments of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be regarded as limiting the breadth, scope or applicability of the present solution. It should be noted that for clarity and ease of description, these drawings are not necessarily drawn to scale.

[0013] Figure 1 shows an example cellular communication network in which the techniques disclosed herein may be implemented according to embodiments of the present disclosure;

[0014] Figure 2 A block diagram showing example base station and user equipment apparatus according to some embodiments of the present disclosure is shown;

[0015] Figure 3 A block diagram showing a network architecture for sidelink communications according to an illustrative embodiment;

[0016] Figure 4 A block diagram showing a channel structure of a sidelink synchronization signal block (S-SSB) according to an illustrative embodiment;

[0017] Figure 5 A block diagram illustrating resource elements in a sidelink synchronization signal block (S-SSB) according to an illustrative embodiment;

[0018] Fig. 6A shows a block diagram of a secondary link synchronization signal block (S-SSB) according to an illustrative embodiment, whose repetition range contains a single type of synchronization signal occupying the entire frequency range;

[0019] Figure 6B A block diagram of a sidelink synchronization signal block (S-SSB) with a repetition range containing multiple types of synchronization signals and a physical sidelink broadcast channel (PSBCH) that are staggered (e.g., the synchronization signals are not the same on all symbols within the repetition range), occupy different frequency range segments, according to an illustrative embodiment;

[0020] Figure 6C A block diagram of a sidelink synchronization signal block (S-SSB) with a repetition range containing non-interleaved (e.g., the synchronization signal is the same on all symbols within the repetition range), a single type of synchronization signal occupying different frequency range segments and a physical sidelink broadcast channel (PSBCH) according to an illustrative embodiment is shown;

[0021] Fig.6DA block diagram of a sidelink synchronization signal block (S-SSB) is shown with a repetition range containing multiple types of synchronization signals and a physical sidelink broadcast channel (PSBCH) that are staggered (e.g., the synchronization signals on all symbols in the repetition range are not the same), occupying the entire frequency range, according to an illustrative embodiment;

[0022] Fig. 7A A block diagram of a sidelink synchronization signal block (S-SSB) is shown according to an illustrative embodiment, wherein a first portion thereof repeats multiple types of synchronization signals and a physical sidelink broadcast channel (PSBCH) occupying different frequency segments and symbols of a second portion;

[0023] Figure 7B A block diagram of a sidelink synchronization signal block (S-SSB) having a first portion repeating a single type of synchronization signal of a second portion occupying an entire frequency segment according to an illustrative embodiment is shown;

[0024] Figure 7C A block diagram of a sidelink synchronization signal block (S-SSB) having a first portion repeating a single type of synchronization signal and PSBCH occupying the entire frequency segment of a second portion according to an illustrative embodiment;

[0025] Figure 8 A block diagram of a sidelink synchronization signal block (S-SSB) is shown that repeats symbols of a second portion using a symbol index in a first portion in accordance with an illustrative embodiment;

[0026] Fig.9A A block diagram of a sidelink synchronization signal block (S-SSB) is shown, which discards a first symbol of a first portion, having a second portion of multiple types of synchronization signals and a physical sidelink broadcast channel (PSBCH) occupying different frequency segments and symbols, according to an illustrative embodiment;

[0027] Fig. 9B A block diagram of a sidelink synchronization signal block (S-SSB) is shown that discards a first symbol of a first portion having a second portion of a single type of synchronization signal occupying an entire frequency segment in accordance with an illustrative embodiment;

[0028] Fig. 9C A block diagram of a sidelink synchronization signal block (S-SSB) is shown that discards a first symbol of a first portion having a second portion of multiple types of synchronization signals occupying an entire frequency segment in accordance with an illustrative embodiment; and

[0029] Fig.10 A flow chart of a method of performing a listen-before-talk (LBT) operation in a secondary link communication is shown in accordance with an illustrative embodiment. DETAILED DESCRIPTION

[0030] Various example embodiments of the present solution will be described below with reference to the accompanying drawings so that a person of ordinary skill in the art can make and use the present solution. A person of ordinary skill in the art will understand that, after reading this disclosure, various changes or modifications may be made to the examples described herein without departing from the scope of the present solution. Therefore, the present solution is not limited to the example embodiments and applications described and shown herein. In addition, the specific order or hierarchy of steps in the methods disclosed herein are merely example methods. Based on design preferences, the specific order or hierarchy of steps of the disclosed methods or processes may be rearranged while still within the scope of the present solution. Therefore, a person of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or actions in an example order, and the present solution is not limited to the specific order or hierarchy presented unless otherwise expressly stated.

[0031] 1. Mobile communication technology and environment

[0032] Figure 1 An example wireless communication network and / or system 100 is shown in which the techniques disclosed herein may be implemented in accordance with an embodiment of the present disclosure. In the discussion below, the wireless communication network 100 may be any wireless network, such as a cellular network or a narrowband Internet of Things (NB-IoT) network, and is referred to herein as "network 100." This example network 100 includes seven base stations 102 (hereinafter referred to as "BS 102"; also referred to as wireless communication nodes) and user equipment devices 104 (hereinafter referred to as "UE 104"; also referred to as wireless communication devices), which may communicate with each other via communication links 110 (e.g., wireless communication channels), and a cluster of cells 126, 130, 132, 134, 136, 138, and 140 covering a geographic area 101. In Figure 1 1 , BS 102 and UE 104 are contained within respective geographic boundaries of cell 126. Each of the other cells 130, 132, 134, 136, 138, and 140 may include at least one base station operating within its allocated bandwidth to provide adequate radio coverage for its intended users.

[0033] For example, BS 102 may operate under the allocated channel transmission bandwidth to provide sufficient coverage to UE 104. BS 102 and UE 104 may communicate via downlink radio frames 118 and uplink radio frames 124, respectively. Each radio frame 118 / 124 may be further divided into subframes 120 / 127, which may include data symbols 122 / 128. In the present disclosure, BS 102 and UE 104 are described herein as non-limiting examples of "communication nodes", which, in general, may practice the methods disclosed herein. According to various embodiments of the present solution, such communication nodes may be capable of wireless and / or wired communication.

[0034] Figure 2 A block diagram of an example wireless communication system 200 for sending and receiving wireless communication signals (e.g., OFDM / OFDMA signals) according to some embodiments of the present solution is shown. System 200 may include components and elements configured to support known or conventional operating features, which need not be described in detail herein. In an illustrative embodiment, system 200 may be used in a wireless communication environment (e.g., Figure 1 The present invention relates to a method for transmitting (eg, sending and receiving) data symbols in a wireless communication environment 100 of the present invention, as described above.

[0035] The system 200 generally includes a base station 202 (hereinafter referred to as "BS 202") and a user equipment device 204 (hereinafter referred to as "UE 204"). The BS 202 includes a BS (base station) transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each of which is coupled and interconnected via a data communication bus 220 as needed. The UE 204 includes a UE (user equipment) transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each of which is coupled and interconnected via a data communication bus 240 as needed. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium suitable for transmitting data described herein.

[0036] Those skilled in the art will appreciate that the system 200 may also include Figure 2 . Those skilled in the art will appreciate that the various illustrative blocks, modules, circuits, and processing logics described in relation to the embodiments disclosed herein can be implemented in hardware, computer-readable software, firmware, or any actual combination thereof. In order to clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are generally described with their functionality. Whether these functions are implemented as hardware, firmware, or software may depend on specific applications and the design constraints imposed on the entire system. Personnel familiar with the concepts described herein can implement these functions in a suitable manner for each specific application, but these implementation decisions should not be interpreted as limiting the scope of the present disclosure.

[0037] According to some embodiments, the UE transceiver 230 may be referred to herein as an "uplink" transceiver 230, which includes a radio frequency (RF) transmitter and an RF receiver, each including circuitry coupled to an antenna 232. A duplex switch (not shown) may alternately couple the uplink transmitter or receiver to the uplink antenna in a time division duplex manner. Similarly, according to some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210, which includes an RF transmitter and an RF receiver, each including circuitry coupled to an antenna 212. The downlink duplex switch may alternately couple the downlink transmitter or receiver to the downlink antenna 212 in a time division duplex manner. The operation of the two transceiver modules 210 and 230 may be coordinated in time such that the uplink receiver circuitry is coupled to the uplink antenna 232 to receive transmissions on the wireless transmission link 250 while the downlink transmitter is coupled to the downlink antenna 212. Instead, the operation of the two transceivers 210 and 230 may be coordinated in time such that the downlink receiver is coupled to the downlink antenna 212 to receive transmissions on the wireless transmission link 250 while the uplink transmitter is coupled to the uplink antenna 232. In some embodiments, there is tight time synchronization with minimal guard times between changes in duplex direction.

[0038] The UE transceiver 230 and the base station transceiver 210 are configured to communicate via a wireless data communication link 250 and cooperate with an appropriately configured RF antenna arrangement 212 / 232, which can support specific wireless communication protocols and modulation schemes. In some illustrative embodiments, the UE transceiver and the base station transceiver 210 are configured to support industry standards such as long-term evolution (LTE) and emerging 5G standards. However, it should be understood that the present disclosure is not necessarily limited to specific standards and related protocols in application. Instead, the UE transceiver 230 and the base station transceiver 210 can be configured to support alternative or additional wireless data communication protocols, including future standards or variants thereof.

[0039] According to various embodiments, BS 202 may be, for example, an evolved Node B (eNB), a serving eNB, a target eNB, a femtocell or a microcell. In some embodiments, UE 204 may be embodied in various types of user equipment, such as a mobile phone, a smart phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, a wearable computing device, etc. Processor modules 214 and 236 may be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof to perform the functions described herein. In this manner, the processor may be implemented as a microprocessor, a controller, a microcontroller, a state machine, etc. The processor may also be implemented as a combination of computing devices, such as a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a digital signal processor core, or any other such configuration.

[0040] Furthermore, the steps of the methods or algorithms described in connection with the embodiments disclosed herein may be directly embodied in hardware, in firmware, in software modules executed by the processor modules 214 and 236, respectively, or in any practical combination thereof. The memory modules 216 and 234 may be implemented as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. In this regard, the memory modules 216 and 234 may be coupled to the processor modules 210 and 230, respectively, so that the processor modules 210 and 230 may read information from and write information to the memory modules 216 and 234, respectively. The memory modules 216 and 234 may also be integrated into their respective processor modules 210 and 230. In some embodiments, the memory modules 216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during instructions to be executed by the processor modules 210 and 230, respectively. Memory modules 216 and 234 may also each include non-volatile memory for storing instructions to be executed by processor modules 210 and 230, respectively.

[0041] The network communication module 218 generally represents the hardware, software, firmware, processing logic and / or other components of the base station 202, which enables two-way communication between the base station transceiver 210 and other network components and communication nodes configured to communicate with the base station 202. For example, the network communication module 218 can be configured to support Internet or WiMAX traffic. In a typical deployment, but not limited to, the network communication module 218 provides an 802.3 Ethernet interface so that the base station transceiver 210 can communicate with a traditional computer network based on Ethernet. In this way, the network communication module 218 can include a physical interface for connecting to a computer network (e.g., a mobile switching center (MSC)). The terms "configured for", "configured to" and their variants used herein for a specific operation or function refer to a device, component, circuit, structure, machine, signal, etc. that is physically constructed, programmed, formatted and / or arranged to perform a specific operation or function.

[0042] The Open Systems Interconnection (OSI) model (referred to herein as the "OSI model") is a concept and logical layout that defines network communications used by systems (e.g., wireless communication devices, wireless communication nodes) that are open for interconnection and communication with other systems. The model is divided into seven subcomponents or layers, each of which represents a set of conceptual services provided to its upper and lower layers. The OSI model also defines logical networks and effectively describes computer data packet transmission by using different layer protocols. The OSI model may also be referred to as a seven-layer OSI model or a seven-layer model. In some embodiments, the first layer may be a physical layer. In some embodiments, the second layer may be a medium access control (MAC) layer. In some embodiments, the third layer may be a radio link control (RLC) layer. In some embodiments, the fourth layer may be a packet data convergence protocol (PDCP) layer. In some embodiments, the fifth layer may be a radio resource control (RRC) layer. In some embodiments, the sixth layer may be a non-access stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer is other layers.

[0043] Figure 3A schematic diagram of a network architecture for side link communication is shown. For example, as shown in the figure, the network may include a base station (BS), a relay (node) (e.g., a header UE) and two UEs, UE1 and UE2. For example, UE1 may be a mobile phone, and UE2 may be a smart gadget (e.g., smart glasses). In some embodiments, UE1 and / or UE2 may be Internet of Things (IoT) devices. UE1 and UE2 may communicate with the BS directly or via a relay. Based on the side link (SL) scheduling received from the BS, the relay, UE1, and UE2 may communicate with each other. The communication between each two relays, UE1, and UE2 may be referred to as side link communication. SL communication may be in the form of unicast, multicast, or broadcast. In addition, UE2 may communicate with the BS / relay via UE1. That is, UE1 may act as a UE / mobile relay.

[0044] 2. System and method for performing "listen before talking" operation in secondary link communication

[0045] Reference now Figure 4 , a block diagram of the channel structure of the sidelink synchronization signal block (S-SSB) is shown. For sidelink synchronization signal block (S-SSB) transmission in sidelink operation on unlicensed spectrum, LBT failure may result in failure to transmit the physical sidelink broadcast channel (PSBCH) and synchronization signal, thereby degrading the synchronization and communication performance of the sidelink. Compared to WiFi, which can transmit at any time, LBT failure may occur more easily. This may be because, when the LBT operation senses idleness for a given duration before this moment, S-SSB transmission may be initiated only at the time slot boundary starting from the PSBCH at symbol 0, such as Figure 3 shown.

[0046] In order to increase the S-SSB channel access opportunities, a method of increasing the number of candidate starting points of S-SSB (for example, within a time slot) may be proposed. In this way, when the LBT operation is unsuccessful at the specified initial starting point a, the LBT operation may be performed at the starting point b. The time interval between a and b may be 9 μs, 16 μs, or an integer multiple of a symbol. If the LBT operation is successful at the candidate starting point b, the S-SSB may still successfully access the channel by not transmitting the mapping signal or channel between the initial starting points a and b, or by only transmitting the mapping signal or channel after b.

[0047] For S-SSB transmissions of the secondary link operating on unlicensed spectrum, some transmission time slots may be excluded from the candidate according to the following procedure. Under the first procedure, the set of time slots that may belong to the secondary link resource pool may be expressed as in:

[0048]

[0049] The slot index may be relative to slot 0 of a radio frame corresponding to a system frame number (SFN) 0 or a direct frame number (DFN) 0 of a serving cell. S-SSB time slots, the set may include all other time slots.

[0050] For the sidelink operation on the unlicensed spectrum, there may be two types of S-SSB slots. According to the above procedure, one type of S-SSB slot may be excluded from the SL (sidelink) resource pool. This type of S-SSB slot may therefore not be mapped by the resource pool association bitmap.

[0051] Another type of S-SSB time slot is configured or predefined in the set of time slots that may belong to the secondary link resource pool (e.g., not in the set to be excluded). This type of S-SSB time slot can therefore be mapped by the resource pool association bitmap. However, these S-SSB time slots may be located in the set of time slots allocated to the secondary link resource pool and correspond to time slots Its corresponding b k′ = 1, where k′ = k mod L 位图 .

[0052] Under the second procedure, the user equipment (UE) may determine the set of time slots allocated to the secondary link resource pool as follows. The resource pool association bitmap may be used The length of the bitmap is L 位图 Can be configured by higher layers. If b k′ = 1, where k′ = k mod L 位图 , then the time slot belongs to this set. The time slots in the set can be reindexed so that the remaining time slots The subscript i is continuous {0,1,…,T′ max -1}, where T′ max It can be the number of remaining time slots in the set.

[0053] The UE may determine the set of resource blocks allocated to the secondary link resource pool. PRB A subchannel m (m = 0, 1, ..., numSubchannel-1) can include a group of n subCHsize There are consecutive resource blocks, and the physical resource block number is n PRB =n subChRBstart +m·n subCHsize +j, j=0,1,…,n subCHsize -1, where n subCHRBstart and n subCHsizeThe UE may not need to use the last N in the resource pool. PRB modn subCHsize PRBs.

[0054] A. Symbol Configuration in the Sidelink Synchronization Signal Block (S-SSB)

[0055] In conjunction with performing a listen-before-talk (LBT) operation, the symbol configuration in the secondary link synchronization signal block (S-SSB) may be as follows. A repetition range for carrying a repeated primary synchronization signal (PSS), secondary synchronization signal (SSS), or physical secondary link broadcast channel PSBCH may be predefined or configured. The predefined or configured frequency resources may be occupied by some or all of the S-PSS / S-SSS / PSBCH. The configuration may include configuration by gNB, radio resource control (RRC), system information, or preconfiguration.

[0056] Reference now Figure 5 , depicts a block diagram of resource elements in a sidelink synchronization signal block (S-SSB). For example, a sidelink PSS (S-PSS) or sidelink SSS (S-SSS) of length 127 may occupy up to 11 resource blocks (RBs), with resource elements (REs) {0,1,129,130,131}, denoted as guard REs, set to 0. The PSBCH may occupy a configured or predefined frequency range (e.g., number of interleavings). The PSBCH cannot be mapped to intra-cell guard RBs or REs.

[0057] Reference now Fig. 6A , a block diagram of a sidelink synchronization signal block (S-SSB) is shown, whose repetition range contains a single type of synchronization signal occupying the entire frequency range. The S-SSB can be mapped from a starting point (e.g., the first symbol of a time slot) to the end of a time slot. The S-SSB can include two parts. The first part can start from symbol k0 and include L0 symbols. The second part can start from symbol k1 and include L1 symbols. k0 can take a value in the range of {0,1,2,3,4,5,6,7}.

[0058] In the first part, the S-PSS or S-SSS may be mapped to a configured or predefined frequency range (e.g., to the number of interlaces if configured or predefined). An S-PSS or S-SSS of length 127 may occupy no more than 11 RBs (132 REs), where REs {0, 1, 129, 130, 131} are set to 0. The S-PSS or S-SSS may be repeated starting from (i) the configured / predefined symbol and (ii) the first symbol with the S-PSS or S-SSS until the last symbol containing the same number of symbols as in the repetition range in the second part, and further repeated in the frequency domain of the first part.

[0059] refer to Figure 6B , a block diagram of a secondary link synchronization signal block (S-SSB) is shown, whose repetition range includes multiple types of synchronization signals and PSBCH that are staggered (e.g., the synchronization signals on all symbols in the repetition range are not the same), occupy different frequency range segments. Now refer to Figure 6C , a block diagram of a sidelink synchronization signal block (S-SSB) is shown, whose repetition range includes non-interleaved (e.g., the synchronization signal is the same on all symbols in the repetition range) a single type of synchronization signal and PSBCH occupying different frequency range segments. As shown in these examples, a set of configured predefined symbols of the second part (e.g., symbols containing only S-PSS or symbols containing only S-SSS) can be repeated to the configured predefined symbols in the first part.

[0060] Reference now Fig.6D , a block diagram of a sidelink synchronization signal block (S-SSB) is shown, whose repetition range contains multiple types of synchronization signals that are staggered (e.g., the synchronization signals on all symbols in the repetition range are not the same) and occupy the entire frequency range. As shown in the example, in the second part, the configured or predefined S-PSS, S-SSS or PSBCH can be mapped to the configured or predefined frequency range, such as the number of staggers, the number of resource blocks (RBds).

[0061] Reference now Fig. 7A , shows a block diagram of a secondary link synchronization signal block (S-SSB), wherein the first part repeats a single type of synchronization signal of the second part, occupying the entire frequency segment. Also refer to Figure 7B, shows a block diagram of a sidelink synchronization signal block (S-SSB), where the first part repeats the second part of a single type of synchronization signal that occupies the entire frequency segment. In some embodiments, an S-PSS or S-SSS of length 127 may occupy no more than 11 RBs (132 REs), where REs {0,1,129,130,131} are set to 0. As shown, symbols containing the S-PSS or S-SSS may be wrapped by the PSBCH. The PSBCH cannot be mapped to REs set to 0 and should not be mapped to intra-cell guard bands between RB sets. Reference Figure 7C , shows a block diagram of a sidelink synchronization signal block (S-SSB), where the first part repeats a single type of synchronization signal and PSBCH of the second part that occupies the entire frequency segment. All symbols within the repetition range should be repeated from symbols with one of S-PSS or S-SSS in the second part. This structure may have the benefit of distinguishing the first part pattern from the second part pattern.

[0062] The configured predefined symbols (e.g., symbols containing only S-PSS or symbols containing only S-SSS) may be repeated from the second part to the predefined symbols configured in the first part. The symbols of the first part and the second part may be generated, for example, by repeating the second part symbols to the symbol positions in the first part and mapping to the slot structure. The symbols of the second part may be mapped to positions within the slot and then repeated to the configured or predefined symbols in the first part to generate the slot structure.

[0063] A set of candidate starting points may be set for the UE to perform channel access, and if a listen-before-talk (LBT) operation at a given starting point is unsuccessful, the next starting point will be used for the LBT operation. The UE may perform LBT at a candidate starting point (e.g., the first symbol or before the first symbol).

[0064] If the LBT operation is successful, the S-SSB can be transmitted, and the mapped signal or channel between the initial candidate starting point and the candidate starting point where the LBT operation is successful is discarded. Only the mapped signal or channel after the candidate starting point where the LBT operation is successful can be transmitted. Otherwise, LBT can be performed at another candidate starting point, which can be 9μs, 16μs, or one symbol after the previous starting point. The above procedure is applicable to S-SSBs that do not belong to the resource pool, such as S-SSBs whose time slots are not mapped by the resource pool association bitmap. For S-SSBs whose time slots are not mapped by the resource pool association bitmap, the starting symbol index can take a value within {0,1,2,3,4,5,6,7}.

[0065] The number of predefined or configured S-SSBs that do not belong to the resource pool and the number of S-SSBs that belong to the resource pool (e.g., S-SSBs whose time slots are mapped by a resource pool associated bitmap) can be configured separately within a specified frequency range (e.g., within an RB set, a bandwidth part (BWP), or a carrier). For example, the number can be the same or different. For an S-SSB whose time slot is mapped by a resource pool associated bitmap, the starting symbol index can take a value of 0.

[0066] The configuration or predefinition of candidate starting points from which at least one starting point can be identified may include the number of candidate starting points, the location of the starting point, the index of the associated S-SSB in the resource pool (e.g., an S-SSB whose time slot is mapped by a bitmap associated with the resource pool), the priority level or the circumstances (e.g., number) of LBT failure operations of S-SSBs belonging to or not belonging to the resource pool, etc.

[0067] B. Transmission of the secondary link synchronization signal block (S-SSB) when the listen-before-talk (LBT) operation succeeds at the initial symbol

[0068] like Fig. 7A As shown in FIG. 7B , the PSBCH quantity may be mapped to a configured or predefined frequency resource by a staggered number (e.g., 2, 3, 4, or 5), a number of RBs (e.g., 20, 30, 40, 50), or a number of symbols for PSBCH mapping starting from a configured or predefined symbol index after symbol 0. The repetition range may be configured or predefined as a symbol range between symbol 0 and the last symbol before the PSBCH start symbol. Now referring to Figure 8 , shows a block diagram of a sidelink synchronization signal block (S-SSB), in which symbols of the second part with symbol indexes are repeated in the first part. The repeated S-PSS or S-SSS in the original symbols 1–2, 3–4 can be mapped to symbols 0–1 and 2–3, respectively, according to the index in the second part; or the repeated S-PSS or S-SSS in symbols 5–6, 7–8 can be mapped to symbols 0–1 and 2–3, respectively, according to the index of the entire time slot. In this case, the time slot structure can be transmitted when the LBT operation succeeds at symbol 0 and idleness is detected within a specified duration before symbol 0.

[0069] C. Transmission of the secondary link synchronization signal block (S-SSB) when the listen-before-talk (LBT) operation fails at the initial symbol and succeeds at the next symbol

[0070] The number of PSBCHs can be mapped to a configured or predefined frequency resource by the number of interleavings (e.g., 2, 3, 4, or 5), the number of RBs, or the number of symbols used for PSBCH mapping starting from a configured or predefined symbol index, which is after symbol 0. . The repetition range can be configured or predefined as the symbol range between symbol 0 and the last symbol before the PSBCH start symbol. The S-PSS or S-SSS repeated in the original symbols 1-2, 3-4 can be mapped to symbols 0-1, 2-3, respectively, according to the index within the second part, or the S-PSS or S-SSS repeated in symbols 5-6, 7-8 can be mapped to symbols 0-1, 2-3, respectively, according to the index of the entire time slot. In this case, when the LBT operation fails at symbol 0 and idleness is sensed within a specified duration before symbol 1 through symbol 1, the time slot structure can be transmitted. The symbol S-PSS mapped to symbol 0 can be discarded, and the S-PSS, PSBCH, or S-SSS mapped from symbol 1 to the end of the time slot can be transmitted.

[0071] These are reflected in the examples depicted. Fig.9A , depicts a block diagram of a sidelink synchronization signal block (S-SSB) that discards a first symbol of a first portion having a second portion of multiple types of synchronization signals and a physical sidelink broadcast channel (PSBCH) occupying different frequency segments and symbols. Fig. 9B , depicts a block diagram of a sidelink synchronization signal block (S-SSB) that discards the first symbol of the first portion and has a second portion of a single type of synchronization signal occupying the entire frequency segment. Fig. 9C , depicts a block diagram of a sidelink synchronization signal block (S-SSB) that discards a first symbol of a first part having a second part of multiple types of synchronization signals occupying an entire frequency segment.

[0072] D. Repetition range of the secondary link synchronization signal block (S-SSB) part

[0073] The number of repetition ranges may be predefined or configured within {1,2,3,4,5,6,7} symbols, and the number of repetition ranges may be different depending on the configured or predefined subcarrier spacing and interleaving number used for PSBCH mapping. For example, configuring 2 symbols as the number of symbols within the repetition range may be to set the number of interleavings used to carry PSBCH to 3 at a 30kHz subcarrier spacing. In this case, the PSBCH may be a rate that matches floor(11 / 15*9)=7 orthogonal frequency division multiplexing (OFDM) symbols, omitting 2 symbols as a repetition range. In another example, configuring 4 symbols as the number of symbols within the repetition range may be to set the number of interleavings used to carry PSBCH to 2 at a 15kHz subcarrier spacing. In this case, the PSBCH may be a rate that matches floor(11 / 20*9)=5 OFDM symbols, omitting 4 symbols as a repetition range.

[0074] Some other settings and PSBCH rate matching methods may result in other numbers of repetition ranges, such as {1,3,5,6,7} symbols. The number of OFDM symbols may be derived from the association rule between the number of interleavings configured / defined for mapping PSBCH or the number of RBs and the subcarrier spacing of S-SSB. One or more symbols of S-PSS, S-SSS, or PSBCH may be mapped to symbols within the repetition range. One or more of S-PSS, S-SSS, or PSBCH may be mapped to symbols within the repetition range.

[0075] E. Mapping of symbols in the sublink synchronization block (S-SSB) relative to the resource pool

[0076] The number of S-SSBs configured or predefined as not belonging to the resource pool may be greater than the number of S-SSBs configured or predefined as belonging to the resource pool. The number of S-SSBs configured or predefined as not belonging to the resource pool may be mapped to the number of S-SSBs configured or predefined as belonging to the resource pool by a mapping ratio greater than 1, and the number of S-SSBs configured or predefined as not belonging to the resource pool may be located in different RB sets or BWPs. The above-mentioned time slot structure may be applicable to one or more S-SSBs configured or predefined as not belonging to the resource pool.

[0077] F. Configuration of candidate starting points for the Listen Before Talk (LBT) operation

[0078] By using different starting points for LBT operation, candidate starting points for LBT operation can be configured or predefined, and the candidate starting points for LBT operation are used for multiple S-SSBs configured within a frequency range (e.g., in different RB sets or BWPs). The number of candidate starting points for LBT operation in one RB set may be less than the number of candidate starting points for LBT operation in another RB set.

[0079] The position of the candidate starting point of the LBT operation in one RB set may be earlier than the position of the candidate starting point of the LBT operation in another RB set. The earlier the position of the S-SSB candidate starting point in the RB set or the fewer the number of LBT operation candidate starting points, the higher the priority of the S-SSB that does not belong to the resource pool or the S-SSB associated with the resource pool. The earlier the position of the candidate starting point of the S-SSB in the RB set or the fewer the number of LBT operation candidate starting points, the more LBT failures of the S-SSB that does not belong to the resource pool or the S-SSB associated with the resource pool. The position of the S-SSB candidate starting point may be determined based on the number of candidate starting points, the priority of the S-SSB that does not belong to the resource pool or the S-SSB associated with the resource pool, and the number of LBT failures of the S-SSB that does not belong to the resource pool or the S-SSB associated with the resource pool.

[0080] G. Procedure for performing listen-before-talk (LBT) operation in secondary link communication

[0081] Reference now Fig.10 , a flow chart of a method 1000 for performing a listen-before-talk (LBT) operation in a secondary link communication is shown. The method 1000 may be implemented or performed using any of the components described above, such as BS 102 or 202 or UE 104 or 204, etc. In a brief overview, a wireless communication device may configure a secondary link synchronization signal block (S-SSB) (1005). The wireless communication device may perform an LBT operation on the S-SSB (1010). The wireless communication device may detect that the LBT operation at a first point ("point A") fails (1015). The wireless communication device may determine whether the LBT operation is successful at a second point ("point B") after the first point (1020). If the LBT operation is successful at the second point, the wireless communication device may transmit a portion of the S-SSB starting from the second point (1025). The wireless communication device may also discard another portion of the S-SSB between the first point and the second point (1030). On the other hand, if the LBT operation fails at the second point, the wireless communication device may continue to perform the LBT operation at a third point (again referred to as the second point when determining transmission) (1035).

[0082] In more detail, a wireless communication device (e.g., UE 104 or 204) may define or configure a link synchronization signal block (S-SSB) (1005). The S-SSB may include a set of resource elements or symbols defined across frequency and time, which are used to perform a listen-before-talk (LBT) operation. The S-SSB may identify or include a first part and a second part, etc. Each of the first part and the second part may include a corresponding subset of resource elements or symbols for secondary link synchronization. The first part may copy, repeat, or repeat one or more symbols of the second part according to the configuration of the second part. In some embodiments, the first part may repeat one or more symbols of the second part according to the configuration of the first part.

[0083] The first portion may correspond to a repeating range portion of the S-SSB (e.g., Figure 5 A- Figure 5 C), and may include a subset of symbols of the second part. In some embodiments, the first part of the S-SSB may repeat one or more symbols of a type that is one of multiple types used for sub-link synchronization. The symbol may correspond to a resource block or resource element defined across frequency and time. The multiple types may identify or include one or more of the following: a sub-link primary synchronization signal (S-PSS) or a sub-link secondary synchronization signal (S-SSS), etc. One or more repeated symbols may start before the initial symbol of the second part of the S-SSB, which is the initial symbol of the physical sub-link broadcast channel (PSBCH) symbol.

[0084] In some embodiments, the first part of the S-SSB may repeat a repetition range corresponding to one or more symbols of the second part. The repetition range may be based on one or more of the number of symbols, subcarrier spacing, number of RBs, or number of interleavings used for mapping. The mapping may be a mapping between one or more symbols in the first part of the S-SSB and one or more symbols in the second part of the S-SSB. The number of symbols may correspond to the number of S-PSS, S-SSS, or PSBCH symbols, etc. The subcarrier spacing (SCS) may correspond to the inverse of the symbol time in a specified channel. The number of interleavings may correspond to the number of times a specified set of symbols (e.g., S-PSS and S-SSS) is repeated within the repetition range of the S-SSB.

[0085] The S-SSBs configured by the wireless communication device for LBT operation may be located outside a resource pool to which at least one other S-SSB belongs. In some embodiments, a first number of S-SSBs that do not belong to the resource pool and a second number of S-SSBs that belong to the resource pool may be configured or predefined separately. In some embodiments, a mapping ratio between a first number of S-SSBs that do not belong to the resource pool and a second number of S-SSBs that belong to the resource pool is predefined. In some embodiments, a first number defined within a resource block (RB) set or a bandwidth part (BWP) is different from or the same as a second number of symbols.

[0086] The wireless communication device may perform, execute, or implement an LBT operation (1010) with respect to S-SSB. The wireless communication device may perform an LBT operation in an unlicensed spectrum to perform an S-SSB transmission in a secondary link operation. While performing the operation, the wireless communication device may monitor other communications or sense communications (e.g., signals or channels) within the unlicensed spectrum. By sensing, the wireless communication device may determine whether there are other communications on the same resources (e.g., resources defined in time and frequency) as the S-SSB in the unlicensed spectrum.

[0087] The wireless communication device may determine, identify, or detect a failure of an LBT operation at a first point ("point A") (1015). While performing an LBT operation, the wireless communication device may detect the failure if there is other communication on the same resource as the S-SSB in the monitored spectrum. By detecting the failure, the wireless communication device may measure, determine, or identify the first point in time when the failure occurred. The wireless communication device may identify the first point from a set of candidate starting points for the LBT operation, and may define the first point within a set of resource blocks (RBs) or a bandwidth part (BWP). The wireless communication device may continue to perform the LBT operation from the first point as a reference.

[0088] The wireless communication device may identify or determine whether the LBT operation is successful at a second point ("point B") after the first point (1020). When performing the LBT operation, if there is no other communication on the same resource as the S-SSB after the first point, the wireless communication device may determine that the LBT operation is successful. In the case of determining success, the wireless communication device may measure, determine, or identify a second point in the time at which success is detected. The wireless communication device may identify the second point from a set of candidate starting points for the LBT operation (e.g., the same set as the first point), and may define the second point within a set of resource blocks (RBs) or a bandwidth part (BWP). In some embodiments, between the first point and the second point, the first part of the S-SSB may repeat one or more symbols of the second part starting from the initial symbol index. In addition, the first part may end the repetition at a termination symbol index, which is before the initial symbol of the physical sidelink broadcast channel (PSBCH).

[0089] Alternatively, when other communications exist on the same resources as the S-SSB, the wireless communication device may determine the LBT operation after the first point as a failure. In the event of a failure, the wireless communication device may promptly measure, determine, or identify a second point (also referred to herein as a third point) until success is detected. In the process of performing the LBT operation at the third point, the second point at which the LBT operation is successful should continue to be identified, and the third point is 9μs, 16μs, or a symbol after the previous second point. The third point can be identified by the wireless communication device from a set of candidate starting points for the LBT operation (e.g., the same set as the first point), and the second point can be defined within a set of resource blocks (RBs) or a bandwidth part (BWP).

[0090] The wireless communication device may identify a first point, a second point, and a third point from a set of candidate starting points for the LBT operation. In some embodiments, a first number of candidate starting points for the LBT operation in the first RB set is less than a second number of candidate starting points for the LBT operation in the second RB set. In some embodiments, a first position of at least one first candidate starting point for the LBT operation in the first RB set may be earlier than a second position of at least one second candidate starting point for the LBT operation in the second RB set.

[0091] If the LBT operation succeeds at the second point, the wireless communication device may send, provide, or transmit a portion of the S-SSB starting from the second point (1025). The portion of the SSB may be mapped to one or more time domain resources (e.g., symbols or intervals between symbols) starting from the second point. In some embodiments, upon success at the second point corresponding to the initial symbol index, the wireless communication device may transmit the entire S-SSB mapped to the one or more time domain resources.

[0092] With respect to the resource pool, the portion of the S-SSB to be transmitted may be unrelated to the resource pool of another S-SSB set. In some embodiments, the transmission of the S-SSB may apply only to the second S-SSB set. The second S-SSB set may be located on a time slot that is not mapped by the resource pool association bitmap. In some embodiments, when the second point corresponds to the initial symbol index, the entire first S-SSB set may be transmitted. The first S-SSB set may be located on a time slot that is mapped by the resource pool association bitmap.

[0093] The wireless communication device may also release or discard another portion of the S-SSB between the first point and the second point in the transmission (1030). In some embodiments, the wireless communication device may discard at least one symbol corresponding to the initial symbol index in the transmission. The discarding of the symbol may be in response to: (i) a failure at a first point corresponding to the initial symbol index; and (ii) a success at a second point corresponding to at least one index after the initial symbol index.

[0094] On the other hand, if the LBT operation fails at the second point, the wireless communication device may continue to perform the LBT operation at a third point (1035). The third point may be, for example, 9 μs, 16 μs, or a symbol after the second point. If the LBT operation is successful, the third point may replace the second point, and transmission may be performed starting from the second point, and the S-SSB symbols between the first point and the second point may be discarded. Alternatively, the LBT operation may be continued at points after the third point until the LBT operation succeeds at a designated point that replaces the second point. In some embodiments, the wireless communication device may determine that the S-SSB after the first point is at the third point, and the LBT operation is successful. When the LBT operation succeeds at the third point, the wireless communication device may start transmitting a second portion of the S-SSB, the second portion having one or more resources (e.g., time domain resources) or symbols starting from the third point.

[0095] Although various embodiments of the present solution have been described above, it should be understood that they are presented by way of example only, rather than by way of limitation. Similarly, various diagrams may depict example architectures or configurations, which are provided to enable those of ordinary skill in the art to understand the example features and functions of the present solution. However, these people will understand that the solution is not limited to the example architectures or configurations shown, but can be implemented using various alternative architectures and configurations. In addition, as those of ordinary skill in the art will understand, one or more features of an embodiment may be combined with one or more features of another embodiment described herein. Therefore, the breadth and scope of the present disclosure should not be limited by any of the illustrative embodiments described above.

[0096] It should also be understood that any reference to an element using names such as "first," "second," etc., herein generally does not limit the number or order of these elements. Instead, these names may be used herein as a convenient means of distinguishing two or more elements or instances of an element. Thus, a reference to a first and a second element does not mean that only two elements may be used, or that the first element must be located before the second element in some manner.

[0097] In addition, those skilled in the art will understand that information and signals may be represented using any of a variety of different techniques and methods. For example, the data, instructions, commands, information, signals, bits, and symbols that may be referenced in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0098] It will also be understood by those of ordinary skill in the art that any of the various illustrative logic blocks, modules, processors, devices, circuits, methods, and functions associated with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementation, analog implementation, or a combination of both), firmware, various forms of programs or design codes containing instructions (which may be referred to herein as "software" or "software modules" for convenience), or any combination of these technologies. In order to clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above in general terms of their functionality. Whether these functions are implemented as hardware, firmware, or software, or a combination of these technologies, depends on the specific application and the design constraints imposed on the overall system. A skilled technician may implement the described functions in various ways for each specific application, but such implementation decisions will not result in a departure from the scope of this disclosure.

[0099] In addition, it will be understood by those of ordinary skill in the art that the various illustrative logic blocks, modules, devices, components, and circuits described herein may be implemented within or performed by an integrated circuit (IC), which may include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may also include antennas and / or transceivers to communicate with various components within a network or within a device. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other suitable configuration to perform the functions described herein.

[0100] If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium. Therefore, the steps of the method or algorithm disclosed herein may be implemented as software stored on a computer-readable medium. Computer-readable media include computer storage media and communication media, including any medium capable of transferring a computer program or code from one place to another. The storage medium may be any available medium accessible by a computer. By way of example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer.

[0101] In this document, the term "module" as used herein refers to software, firmware, hardware, and any combination of these elements for performing the relevant functions described herein. In addition, for ease of discussion, various modules are described as discrete modules; however, as is clear to those of ordinary skill in the art, two or more modules can be combined to form a single module that performs relevant functions according to embodiments of the present solution.

[0102] In addition, in the embodiment of the present scheme, memory or other storage and communication components can be adopted.It should be understood that, for the sake of clarity, the above description has described the embodiment of the present scheme with reference to different functional units and processors.However, it is obvious that any appropriate functional distribution between different functional units, processing logic elements or domains can be used without departing from the present scheme.For example, the function performed by a separate processing logic element or controller can be performed by the same processing logic element or controller.Therefore, the reference to a specific functional unit is only a reference to a suitable device for providing the function, rather than indicating a strict logical or physical structure or organization.

[0103] It will be readily apparent to those skilled in the art that various modifications to the embodiments described in the present disclosure, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but should be given the widest scope consistent with the novel features and principles disclosed herein, as described in the appended claims.

Claims

1. A method for performing a listen-before-talk (LBT) operation in a secondary link communication, comprising: performing, by a wireless communication device, an LBT operation on a secondary link synchronization signal block (S-SSB), the S-SSB having a first portion and a second portion, wherein the first portion repeats one or more symbols of the second portion according to a configuration of the second portion; determining, by the wireless communication device, a failure of the LBT operation at a first point of the S-SSB; determining, by the wireless communication device, success of the LBT operation at a second point of the S-SSB, the second point being subsequent to the first point; and In response to the success, at least a portion of the S-SSB is transmitted by the wireless communication device, and the at least a portion is mapped to one or more time domain resources starting from the second point.

2. The method according to claim 1, further comprising: determining, by the wireless communication device, a second failure of the LBT operation at a third point of the S-SSB, the third point being after the first point; as well as In response to success at the second point, a second portion of the S-SSB is transmitted by the wireless communication device, the second portion having one or more second time domain resources starting from the second point.

3. The method according to claim 1, further comprising: determining, by the wireless communication device, success of the LBT operation at a third point of the S-SSB, the third point being after the first point; as well as In response to success at the third point, a second portion of the S-SSB is transmitted by the wireless communication device, the second portion having one or more second time domain resources starting from the third point.

4. The method according to claim 1, further comprising: In response to the success, a second portion of the S-SSB located between the first point and the second point is discarded in the transmission by the wireless communication device.

5. The method according to claim 1, wherein: The first part of the S-SSB repeats one or more symbols of a type, where the type is one of multiple types used for sub-link synchronization, and the multiple types include at least one of a sub-link primary synchronization signal (S-PSS) or a sub-link secondary synchronization signal (S-SSS).

6. The method according to claim 1, wherein: Depending on the configuration of the first part of the S-SSB, the first part repeats one or more symbols of the second part.

7. The method according to claim 1, wherein: The first part of the S-SSB starts from an initial symbol index and ends at a termination symbol index, repeating one or more symbols of the second part, wherein the termination symbol index is before the initial symbol of the physical sidelink broadcast channel (PSBCH).

8. The method according to claim 1, wherein: The transmission of the S-SSB is only applied to the second S-SSB set.

9. The method according to claim 8, wherein: The second S-SSB set is located on a time slot that is not mapped by the resource pool association bitmap.

10. The method according to claim 1, wherein: In case the second point corresponds to the initial symbol index, the entire first S-SSB set is transmitted.

11. The method according to claim 10, wherein: The first S-SSB set is located on a time slot mapped by a resource pool associated bitmap.

12. The method according to claim 7, wherein: Transmitting also includes: in response to success at a second point corresponding to the initial symbol index, transmitting the entire S-SSB, wherein the entire S-SSB is mapped to the one or more time domain resources.

13. The method according to claim 7, further comprising: In response to the following situation, at least one initial symbol corresponding to the initial symbol index is discarded in transmission by the wireless communication device: (i) a failure at a first point corresponding to said initial symbol index; as well as (ii) success at a second point corresponding to at least one index subsequent to the initial symbol index.

14. The method according to claim 1, wherein: Based on at least one of the number of symbols, the subcarrier spacing, the number of resource blocks (RBs), or the number of interleavings used for mapping, the first part of the S-SSB repeats a repetition range corresponding to one or more symbols of the second part.

15. The method according to claim 1 or 7, wherein: The first number of S-SSBs that do not belong to the resource pool and the second number of S-SSBs that belong to the resource pool are configured or predefined respectively.

16. The method according to claim 1 or 7, wherein: A mapping ratio between a first number of S-SSBs that do not belong to the resource pool and a second number of S-SSBs that belong to the resource pool is predefined.

17. The method according to claim 14 or 15, wherein: The first number defined within a set of resource blocks (RBs) or a bandwidth part (BWP) is the same as or different from the second number of symbols.

18. The method according to claim 1, wherein: The first point and the second point are identified from a plurality of candidate starting points for LBT operation, each candidate starting point being defined within at least one of a resource block (RB) set or a bandwidth part (BWP).

19. The method according to claim 15, wherein: A first number of candidate starting points for the LBT operation in the first RB set is less than a second number of candidate starting points for the LBT operation in the second RB set.

20. The method according to claim 15, wherein: A first position of at least one first candidate starting point for the LBT operation in the first RB set is earlier than a second position of at least one second candidate starting point for the LBT operation in the second RB set.

21. A wireless communication device comprising a processor and a memory, wherein: The processor is configured to read code from the memory and execute the method according to any one of claims 1 to 20.

22. A computer program product comprising computer readable program medium code stored thereon, which, when executed by a processor, causes the processor to perform the method according to any one of claims 1 to 20.

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