SL-U SSB enhancements in broadband operation

Abstract

An apparatus for wireless communication at a user equipment (UE) includes: a transceiver; a memory storing computer executable instructions; and a processor coupled with the transceiver and the memory, and configured to manage transmission and reception of a sidelink synchronization signal block (SL-SSB). The apparatus receives, via the transceiver, an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band. The apparatus transmits or receives, via the transceiver, the SL-SSB on an SL-SSB occasion based on a set of reference resource blocks at the frequency location, wherein the set of reference resource blocks of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

Description

Background Art Technical Field

[0001] The present disclosure relates to wireless communications including sidelink synchronization signal blocks (SSBs) in wideband operation on unlicensed or shared spectrum.

[0002] introduction

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0004] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continued mobile broadband evolution promulgated by the 3rd Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Certain aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the Invention

[0005] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects and is neither intended to identify key or critical elements of all aspects nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be presented later.

[0006] In some aspects, the technology described herein relates to an apparatus for wireless communication at a user equipment (UE), the apparatus comprising: a transceiver; a memory storing computer-executable instructions; a processor coupled to the transceiver and the memory and configured to execute the computer-executable instructions to: receive, via the transceiver, an indication of a frequency location of a side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and send or receive, via the transceiver, the SL-SSB on a SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0007] In some aspects, the techniques described herein relate to an apparatus wherein the indication includes an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

[0008] In some aspects, the techniques described herein relate to an apparatus wherein the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

[0009] In some aspects, the techniques described herein relate to an apparatus wherein the indication identifies a center frequency of the reference set of resource blocks as an index to a set of resource blocks within the bandwidth portion.

[0010] In some aspects, the techniques described herein relate to an apparatus wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

[0011] In some aspects, the techniques described herein relate to an apparatus, wherein the reference resource block set is within a minimum resource block set that is an intersection of a set of supported resource block set configurations. In some implementations, the minimum resource block set excludes resource blocks in the guard band between the first 20 MHz channel and the other channel in the bandwidth portion, and excludes resource blocks in one or more other guard bands for at least one other wireless device.

[0012] In some aspects, the technology described herein relates to an apparatus wherein multiple SL-SSB opportunities are supported in other resource block sets within the bandwidth portion corresponding to the frequency position of the SL-SSB within the reference resource block set, wherein in order to send or receive the SL-SSB at the SL-SSB opportunity based on the reference resource block set, the processor is configured to execute instructions to send or receive the SL-SSB at one or more SL-SSB opportunities among the multiple SL-SSB opportunities that satisfy a listen-before-talk (LBT) condition.

[0013] In some aspects, the techniques described herein relate to an apparatus wherein the plurality of SL-SSB opportunities includes one SL-SSB opportunity in each of the other sets of resource blocks within the bandwidth portion.

[0014] In some aspects, the techniques described herein relate to an apparatus wherein the indication comprises a bitmap indicating whether each of the sets of resource blocks within the bandwidth portion includes a SL-SSB opportunity.

[0015] In some aspects, the techniques described herein relate to an apparatus wherein the indication comprises a resource indication value indicating a number of a set of contiguous resource blocks within the bandwidth portion starting from the set of reference resource blocks that include SL-SSB opportunities.

[0016] In some aspects, the technology described herein relates to an apparatus wherein the indication includes a bitmap indicating whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

[0017] In some aspects, the technology described herein relates to an apparatus wherein, in order to send the SL-SSB on one or more SL-SSB opportunities among the plurality of SL-SSB opportunities, the processor is configured to execute the instructions to send the SL-SSB on each SL-SSB opportunity that satisfies the LBT condition.

[0018] In some aspects, the technology described herein relates to an apparatus wherein, to transmit the SL-SSB on one or more of the plurality of SL-SSB opportunities, the processor is configured to execute instructions to transmit the SL-SSB on a set of contiguous resource blocks.

[0019] In some aspects, the technology described herein relates to an apparatus, wherein, to send the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities, the processor is configured to execute the instructions to select one of the SL-SSB opportunities that satisfies the LBT condition for sending the SL-SSB.

[0020] In some aspects, the technology described herein relates to a method of wireless communication, the method comprising: receiving, at a wireless device, an indication of a frequency location of a side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and sending or receiving, at the wireless device, the SL-SSB at a SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0021] In some aspects, the technology described herein relates to a method wherein the indication includes an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

[0022] In some aspects, the techniques described herein relate to a method in which the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

[0023] In some aspects, the techniques described herein relate to a method wherein the indication identifies a center frequency of the reference set of resource blocks as an index to a set of resource blocks within the bandwidth portion.

[0024] In some aspects, the technology described herein relates to a method wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

[0025] In some aspects, the techniques described herein relate to a method wherein the reference resource block set is within a minimum resource block set, the minimum resource block set being an intersection of a set of supported resource block set configurations. In some aspects, the techniques described herein relate to a method wherein a plurality of SL-SSB opportunities are supported in other resource block sets within the bandwidth portion corresponding to the frequency location of the SL-SSB within the reference resource block set, wherein sending or receiving the SL-SSB at the SL-SSB opportunity based on the reference resource block set comprises sending or receiving the SL-SSB at one or more SL-SSB opportunities among the plurality of SL-SSB opportunities that satisfy a listen-before-talk (LBT) condition.

[0026] In some aspects, the techniques described herein relate to a method wherein the plurality of SL-SSB opportunities includes one SL-SSB opportunity in each of the other sets of resource blocks within the bandwidth portion.

[0027] In some aspects, the technology described herein relates to a method wherein the indication comprises a bitmap indicating whether each of the sets of resource blocks within the bandwidth part includes a SL-SSB opportunity.

[0028] In some aspects, the technology described herein relates to a method wherein the indication includes a resource indication value indicating a number of a set of contiguous resource blocks within the bandwidth portion starting from the set of reference resource blocks that include SL-SSB opportunities.

[0029] In some aspects, the technology described herein relates to a method wherein the indication includes a bitmap that indicates whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

[0030] In some aspects, the technology described herein relates to a method, wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities includes: sending the SL-SSB on each SL-SSB opportunity that satisfies the LBT condition.

[0031] In some aspects, the technology described herein relates to a method wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities among the plurality of SL-SSB opportunities includes sending the SL-SSB on a set of contiguous resource blocks.

[0032] In some aspects, the technology described herein relates to a method, wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities includes: selecting an SL-SSB opportunity among the SL-SSB opportunities that satisfies the LBT condition for sending the SL-SSB.

[0033] In some aspects, the technology described herein relates to an apparatus for wireless communications at a user equipment (UE), the apparatus comprising: means for receiving an indication of a frequency location of a first side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and means for sending the first SL-SSB on a SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band; and means for receiving a second SL-SSB on the SL-SSB opportunity.

[0034] In some aspects, the technology described herein relates to a non-transitory computer-readable medium storing computer-executable instructions that, when executed by a processor of a wireless device, cause the wireless device to: receive an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and send or receive the SL-SSB on a SL-SSB opportunity based on a set of reference resource blocks at the frequency location, wherein the set of reference resource blocks for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0035]

[0011] In some aspects, the technology described herein relates to a method of wireless communication for a base station, comprising transmitting an indication of a frequency location of a reference sidelink synchronization signal block (SL-SSB) opportunity within a bandwidth portion of a shared frequency band.

[0036] The present disclosure also provides an apparatus (e.g., the BS) comprising a memory storing computer-executable instructions and at least one processor configured to execute these computer-executable instructions to perform the above-mentioned method for a base station (BS), an apparatus comprising components for performing the above-mentioned method for the BS, and a computer-readable medium storing computer-executable instructions for performing the above-mentioned method for the BS.

[0037] To accomplish the foregoing and related ends, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of but a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0039] Figure 2Ais a diagram illustrating an example of a first 5G NR frame.

[0040] Figure 2B is a diagram illustrating an example of downlink channels within a 5G NR subframe.

[0041] Figure 2C is a diagram illustrating an example of a second 5G NR frame.

[0042] Figure 2D is a diagram illustrating an example of uplink channels within a 5G NR subframe.

[0043] Figure 3 is a diagram illustrating an example in which a first wireless communication device communicates with a second wireless communication device.

[0044] Figure 4 is a diagram of an example of a set of resource blocks (RBs) used for communication between wireless communication devices.

[0045] Figure 5 is a diagram illustrating an example of side link synchronization signal block (SL-SSB) timing within a set of RBs used for communication between wireless communication devices (such as UEs).

[0046] Figure 6 is a message diagram illustrating example messages between a base station and one or more UEs.

[0047] Figure 7 is a resource map illustrating a bitmap used to indicate whether each of the resource block sets within the bandwidth part includes an SL-SSB opportunity.

[0048] Figure 8 is a resource map illustrating a bitmap used to indicate whether a non-reference RB set within a bandwidth part includes an SL-SSB opportunity.

[0049] Figure 9 is a conceptual data flow diagram illustrating the data flow between different parts / components in an example UE including an SL-SSB component.

[0050] Figure 10 is a flow chart of an example method for operating a UE to send or receive SL-SSB. DETAILED DESCRIPTION

[0051] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0052] The described features generally relate to synchronization signal blocks (SSBs) for sidelink communications, which may also be referred to as direct link communications. As used herein, a direct link refers to a direct wireless communication path from a first wireless device to a second wireless device. For example, in fifth generation (5G) new radio (NR) communication technology, a direct link between two user equipments (UEs) may be referred to as a side link (SL), rather than communicating over a Uu interface (e.g., from a gNB to a user equipment (UE). Direct links may be utilized in D2D communication technologies, which may include vehicle-to-vehicle (V2V) communications, vehicle-to-infrastructure (V2I) communications (e.g., from a vehicle-based communication device to a road infrastructure node), vehicle-to-network (V2N) communications (e.g., from a vehicle-based communication device to one or more network nodes such as a base station), combinations thereof, and / or communications with other devices, which may be collectively referred to as vehicle-to-everything (V2X) communications. In V2X communications, vehicle-based communication devices may communicate with each other and / or with infrastructure devices via a direct link channel.

[0053] In one aspect, the described features relate to sidelink SSB in an unlicensed band or unlicensed shared spectrum. Shared spectrum may refer to a portion of the spectrum to which devices belonging to different networks are allowed to access. In some implementations, the shared spectrum may be referred to as unlicensed spectrum or an unlicensed band. Sidelink communications over such shared spectrum may be referred to as SL-U. In some cases, a universal license may apply to the shared spectrum. A listen-before-talk (LBT) process or a channel assessment (CA) process may be applicable to communications in the shared spectrum.

[0054] The SSB may carry information used to identify a device and allow other devices to synchronize with it. For example, in 5G NR, a base station may transmit an SSB on one or more beams. A user equipment (UE) may determine a cell identifier (ID) based on the SSB. The SSB may also include a broadcast channel (BCH) that allows the UE to locate system information. Similarly, in sidelink communications, a UE may transmit an SSB to identify the UE and provide information about services provided by the UE.

[0055] Shared spectrum offers the potential to expand the available resources for sidelink communications. For example, a large portion of the spectrum can be designated as shared spectrum between frequency range 1 (FR1) and frequency range 2 (FR2) (e.g., 5.9 GHz to 7.1 GHz), within FR2, or at higher frequencies. However, shared spectrum presents several technical challenges in transmitting sidelink SSBs. First, shared spectrum can utilize a 20 MHz basic channel unit. This basic channel unit may include a set of resource blocks (RBs) separated from another basic channel unit by an intra-cell guard band, the size of which may vary depending on the capabilities of different UEs. In order for multiple UEs to receive SL-SSBs, it may be necessary to transmit the SL-SSBs on a subset of the RB set that is common to all UEs and does not overlap with the guard band of any UE. This available RB may be referred to as a common minimum RB set. Second, the size of the shared spectrum may result in inefficiencies in signaling specific frequency locations. Conventionally, an absolute radio frequency channel number (ARFCN) has been used to indicate a specific frequency, such as a carrier center frequency. For frequencies less than 3000 MHz, the ARFCN may correspond to a width of 5 kHz, and for frequencies from 3000 MHz to 24,260 MHz, it may correspond to 15 kHz. Thus, ARFCN values ​​of 600,000 to 2,016,666 may indicate frequencies in the frequency range 3000 MHz to 24,260 MHz. However, as noted above, only some frequency locations may be available for SL-SSBs, so dedicating a large number of bits to signaling larger ARFCN values ​​to indicate SL-SSB locations may be inefficient. Third, LBT or CA mechanisms used for shared spectrum may delay or prevent the transmission of SL-SSBs on a particular set of RBs.

[0056] In one aspect, the present disclosure provides a signaling mechanism for SL-SSB. Specifically, the UE may receive an indication of the frequency location of the SL-SSB within the bandwidth portion of the shared frequency band. For example, the indication may be received in a radio resource control (RRC) message sent by a base station or another UE. The indication may specify the frequency location of a reference resource block set. The reference resource block set may be separated from another channel in the bandwidth portion by a guard band. The UE may send or receive the SL-SSB on a SL-SSB occasion based on the reference resource block set. In some specific implementations, the SL-SSB opportunity may be within a common minimum resource block set. In some specific implementations, the UE may attempt to send or receive the SL-SSB on multiple SL-SSB opportunities to increase the likelihood of LBT success.

[0057] The disclosed SL-SSB-related signaling can resolve ambiguity regarding the frequency location of SL-SSBs. Furthermore, the signaling can be more efficient than conventional ARFCN-based signaling. For example, the number of bits used to indicate the frequency location can be based on the number of RB sets in a bandwidth portion rather than the number of ARFCNs in a frequency range. The ability to attempt transmission on more than one SL-SSB opportunity can increase the likelihood of LBT success and the likelihood of successfully transmitting and receiving SL-SSBs.

[0058] Several aspects of telecommunication systems will now be presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively, "elements"). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0059] As an example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. The example of a processor includes a microprocessor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor, a digital signal processor (DSP), a reduced instruction set computing (RISC) processor, a system on a chip (SoC), a baseband processor, a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, a gating logic, a discrete hardware circuit and other suitable hardware configured to perform various functionalities described throughout this disclosure. One or more processors in a processing system can execute software. Whether it is referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0060] Therefore, in one or more example implementations, the functions described herein may be implemented with hardware, software, or any combination thereof. If implemented in software, the functions may be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media, which may be referred to as non-transitory computer-readable media. Non-transitory computer-readable media may not include transient signals. The storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of the foregoing types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0061] Figure 1 1 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. Small cells include femto cells, pico cells, and micro cells.

[0062] In one aspect, one or more of the UEs 104 may include an SL-SSB component 140 configured to control SL-SSB transmission and / or reception with the other UEs 104. The SL-SSB component 140 may include an indication receiving component 142 configured to receive an indication of a frequency location of the SL-SSB within the bandwidth portion of the shared frequency band. The SL-SSB component 140 may include an SL-SSB receiving component 144 configured to receive the SL-SSB at the SL-SSB opportunity based on a reference resource block set at the frequency location. The SL-SSB component 140 may include an SL-SSB transmitting component 146 configured to transmit the SL-SSB at the SL-SSB opportunity based on the reference resource block set at the frequency location. The reference resource block set for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0063] In an aspect, one or more of the UEs 104 (e.g., a second UE) may also include an SL-SSB component 140. The SL-SSB component 140 of the second UE 104 may be configured to send a first SL-SSB to the first UE 104 and receive a second SL-SSB sent by the first UE 104.

[0064] In one aspect, one or more of base stations 102 may include a sidelink configuration component 120 configured to send an indication of a frequency location of the SL-SSB within the bandwidth portion of the shared frequency band. For example, sidelink configuration component 120 may be configured to send a radio resource control (RRC) message with the indication. For example, the indication may be associated with an RRC configuration for the bandwidth portion.

[0065] Base stations 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interact with the EPC 160 via a first backhaul link 132 (e.g., an S1 interface), where the first backhaul link can be a wired link or a wireless link. Base stations 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interact with the core network 190 via a second backhaul link 184, where the second backhaul link can be wired or wireless. Among other functions, the base station 102 may perform one or more of the following functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via the EPC 160 or the core network 190) via a third backhaul link 134 (e.g., an X2 interface). The third backhaul link 134 may be wired or wireless.

[0066] Base stations 102 can communicate wirelessly with UEs 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102′ can have a coverage area 110′ that overlaps with the coverage area 110 of one or more macro base stations 102. A network that includes both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include home evolved Node Bs (eNBs) (HeNBs), which can provide service to a restricted group known as a closed subscriber group (CSG). The communication link 112 between base station 102 and UE 104 can include uplink (UL) (also known as reverse link) transmissions from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmissions from base station 102 to UE 104. The communication link 112 can use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link can be over one or more carriers. Base station 102 / UE 104 may use spectrum with a bandwidth of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, etc.) for each carrier allocated in the carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction. These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​compared to UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carriers may be referred to as secondary cells (SCells).

[0067] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may utilize the DL / UL WWAN spectrum. The D2D communication link 158 may utilize one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be accomplished via various wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR. In one aspect, the D2D communication link 158 may be configured with direct link carrier aggregation for multiple component carriers.

[0068] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether the channel is available before communicating.

[0069] Small cell 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, small cell 102' can employ NR and utilize the same 5 GHz unlicensed spectrum as used by Wi-Fi AP 150. Small cell 102' employing NR in unlicensed spectrum can improve access network coverage and / or increase access network capacity.

[0070] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz–7.125 GHz) and FR2 (24.25 GHz–52.6 GHz). Frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is often (interchangeably) referred to as the “sub-6 GHz” band in various documents and articles. A similar naming issue sometimes arises with FR2, which is often (interchangeably) referred to as the “millimeter wave” band in various documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz to 300 GHz), which the International Telecommunication Union (ITU) has identified as the “millimeter wave” (mmW) band.

[0071] With all of the above in mind, unless otherwise specified, it should be understood that when the term "sub-6 GHz" or the like is used herein, it can be broadly interpreted to mean frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Furthermore, unless otherwise specified, it should be understood that when the term "millimeter wave" or the like is used herein, it can be broadly interpreted to mean frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band. Communications using mmW radio frequency bands have extremely high path loss and a short range. mmW base station 180 can utilize beamforming 182 with UE 104 to compensate for the path loss and short range.

[0072] Base station 180 may transmit beamformed signals in one or more transmit directions 182′ to UE 104. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182″. UE 104 may also transmit beamformed signals in one or more transmit directions to base station 180. Base station 180 may receive beamformed signals in one or more receive directions from UE 104. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may be the same or different. The transmit direction and receive direction of UE 104 may be the same or different.

[0073] EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. MME 162 may communicate with a Home Subscriber Server (HSS) 174. MME 162 is a control node that handles signaling between UE 104 and EPC 160. Generally speaking, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Services 176. IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 provides functionality for MBMS user service provisioning and delivery. It serves as the entry point for content providers' MBMS delivery, authorizes and initiates MBMS bearer services within the Public Land Mobile Network (PLMN), and schedules MBMS delivery. The MBMS Gateway 168 distributes MBMS services to base stations 102 within a Multicast Broadcast Single Frequency Network (MBSFN) area that broadcasts specific services. It is also responsible for session management (start / stop) and for collecting eMBMS-related billing information.

[0074] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Generally speaking, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are passed through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to the IP services 197. The IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0075] A base station may include and / or be referred to as a gNB, Node B, eNB, access point, base transceiver station, radio base station, radio transceiver, transceiver functionality, basic service set (BSS), extended service set (ESS), transmit receive point (TRP), or some other suitable terminology. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smartphone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0076] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0077] Figure 2A FIG200 is a diagram illustrating an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G NR subframe. Figure 2CFIG250 is a diagram illustrating an example of a second subframe within a 5G NR frame structure. Figure 2D FIG280 is a diagram illustrating an example of UL channels within a 5G NR subframe. The 5G / NR frame structure can be frequency division duplex (FDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to either DL or UL, or time division duplex (TDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to both DL and UL. Figure 2A 、 Figure 2C In the example provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (most of which are DL), where D is DL, U is UL, and X can be used flexibly between DL / UL, and subframe 3 is configured with slot format 34 (most of which are UL). Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe can be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are all DL and all UL, respectively. The other slot formats 2-61 include a mix of DL, UL, and flexible symbols. The UE is configured with the slot format via the received slot format indicator (SFI) (dynamically configured via DL control information (DCI) or semi-statically / statically configured via radio resource control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0078] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include mini-slots, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single-stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter set (numerology). For slot configuration 0, different parameter sets μ0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Thus, for slot configuration 0 and parameter set μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is parameter set 0 to 5. Therefore, the subcarrier spacing for parameter set μ=0 is 15kHz, and the subcarrier spacing for parameter set μ=5 is 480kHz. Symbol length / duration is inversely related to subcarrier spacing. Figures 2A to 2D An example is provided for slot configuration 0 with 14 symbols per slot and parameter set μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

[0079] A resource grid can be used to represent the frame structure. Each slot includes a resource block (RB) (also called a physical RB (PRB)) that extends over 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0080] like Figure 2A As illustrated, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) for channel estimation at the UE (indicated as R for one specific configuration). x, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signal (CSI-RS). RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and phase tracking RS (PT-RS).

[0081] Figure 2B Examples of various DL channels within a subframe of a frame are illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE includes nine RE groups (REGs), and each REG includes four consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) may be within symbol 2 of a specific subframe of the frame. The PSS is used by the UE 104 to determine the subframe / symbol timing and the physical layer identification. The secondary synchronization signal (SSS) may be within symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identification group number and the radio frame timing. Based on the physical layer identification and the physical layer cell identification group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the position of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the system frame number (SFN) and the number of RBs in the system bandwidth. The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not sent through the PBCH (such as System Information Blocks (SIBs)), and paging messages.

[0082] like Figure 2C As illustrated, some of the REs carry DM-RS (indicated as R for a specific configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit the DM-RS of the physical uplink control channel (PUCCH) and the DM-RS of the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first or first two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is transmitted and depending on the specific PUCCH format used, the PUCCH DM-RS may be transmitted in different configurations. The UE may transmit a sounding reference signal (SRS). The SRS may be transmitted in the last symbol of the subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of the comb structures in the comb structure. The SRS may be used by the base station for channel quality estimation to achieve frequency-dependent scheduling of the UL.

[0083] Figure 2DExamples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at the position indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry buffer status reports (BSRs), power headroom reports (PHRs), and / or UCI.

[0084] Figure 3 300 is a block diagram illustrating a first wireless communication device 310 in communication with a second wireless communication device 350, for example, via V2V / V2X / D2D communication. Device 310 may include a transmitter device communicating with a receiver device (e.g., device 350) via V2V / V2X / D2D communication. The communication may be based on a sidelink, for example. The transmitter device 310 may include a UE, a RSU, etc. The receiver device may include a UE, an RSU, etc. Packets may be provided to a controller / processor 375 that implements Layer 3 and Layer 2 functionality. Layer 3 includes an RRC layer, and Layer 2 includes a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer.

[0085] The transmit (TX) processor 316 and receive (RX) processor 370 implement Layer 1 functionality associated with various signal processing functions. Layer 1, which includes the physical (PHY) layer, may include error detection on transport channels, forward error correction (FEC) coding / decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation / demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles the mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-order phase-shift keying (M-PSK), and M-order quadrature amplitude modulation (M-QAM). The coded and modulated symbols are then separated into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying the time-domain OFDM symbol stream. The OFDM stream is spatially pre-decoded to generate multiple spatial streams. Channel estimates from channel estimator 374 can be used to determine the coding and modulation schemes, as well as for spatial processing. The channel estimates can be derived from a reference signal and / or channel condition feedback sent by device 350. Each spatial stream can then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX can modulate an RF carrier with a corresponding spatial stream for transmission.

[0086] At device 350, each receiver 354RX receives a signal via its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement Layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial streams destined for device 350. If multiple spatial streams are destined for device 350, the RX processor 356 can combine them into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point most likely transmitted by device 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by device 310. The data and control signals are then provided to a controller / processor 359, which implements layer 3 and layer 2 functionality.

[0087] The controller / processor 359 may be coupled to a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. The controller / processor 359 may provide demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0088] Similar to the functions described in conjunction with the transmission performed by the device 310, the controller / processor 359 may provide RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0089] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the device 310 may be used by a TX processor 368 to select an appropriate coding and modulation scheme, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0090] The transmission is processed at device 310 in a manner similar to that described in conjunction with the receiver functionality at device 350. Each receiver 318RX receives a signal through its corresponding antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to an RX processor 370.

[0091] The controller / processor 375 may be coupled to a memory 376 that stores program codes and data. Memory 376 may be referred to as a computer-readable medium. The controller / processor 375 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing. The controller / processor 375 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0092] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to combine Figure 1 Similarly, at least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to combine Figure 1 The SL-SSB component 140 is used to perform various aspects.

[0093] Figure 4 4 is a diagram illustrating an example of RB sets for communication between wireless communication devices (such as UEs). For example, within a cell, there may be five UEs 104 configured for sidelink communication within a bandwidth part (BWP) 402. For example, each pair of UEs may be configured with a different set of RBs based on the capabilities of each UE. For example, the base station may configure an inter-cell guard band for each UE for both transmitting on the uplink (UL) and receiving on the downlink (DL). Similarly, an inter-cell guard band may be applied when transmitting on the sidelink or receiving on the sidelink.

[0094] For example, Figure 4As illustrated, a first UE (UE0) may be configured with a guard band (GB) 414 for communication 410 with a second UE (UE1). GB 414 may separate each RB set 412 within BWP 402. Similarly, the first UE may be configured with GB 424 for communication 420 with a third UE (UE2). For example, because the third UE has a greater reception capability than the second UE, GB 424 may be smaller than GB 414. RB set 422 may be larger than RB set 412 (i.e., include more RBs). A fourth UE (UE3) may be configured with GB 434 for communication 430 with a fifth UE (UE4). GB 434 may be larger than GB 414 and GB 424. Therefore, RB set 432 may be smaller than RB set 412 or RB set 422. In some implementations, the minimum RB set among the configured UEs may be referred to as a common minimum RB set or a minimum overlapping RB set. In some implementations, the common minimum RB set may be the intersection of all supported RB set configurations. For example, the supported RB set configurations may be defined in a standard document or specification.

[0095] SL-SSB 440 may be transmitted over multiple RBs. Figure 2B As illustrated, SSBs on the Uu link are conventionally transmitted over 20 RBs. With a 15 kHz subcarrier spacing (SCS), 20 RBs may be equal to 3.6 MHz. In some 3GPP Release 16 and 17 systems, SL-SSBs may span 11 common RBs within the SL bandwidth portion. A larger SCS may result in a larger portion of bandwidth being used to transmit SSBs. For communications in unlicensed spectrum, the choice of frequency location for the SL-SSB 440 may be limited given the 20 MHz basic channel unit and the GB limiting the size of the RB set. For example, there may be an occupied channel bandwidth (OCB) requirement, i.e., the transmission occupies between 80% and 100% of the 20 MHz channel. In unlicensed spectrum, the SL-SSB may be enhanced to meet the OCB requirement, for example, via repetition over more RBs. For example, the UE 104 may transmit the SL-SSB over the minimum RB set 432 so that the SL-SSB transmission meets the OCB requirement and other UEs may receive the SL-SSB. SL-SSB 440 may use a majority (eg, at least 80%) of RB set 432. Because SL-SSB 440 should not overlap with a GB, only some positions within RB set 432 may be suitable for SL-SSB 440.

[0096] Conventionally, an Absolute Radio Frequency Channel Number (ARFCN) 450 is used to indicate the center frequency of an SSB. Although not to scale, the number of ARFCNs 450 can be much larger than the number of RBs in an RB set. For example, there can be 1333 ARFCNs within a 20 MHz basic channel unit at 3000 MHz. In one aspect, signaling the ARFCNs can be inefficient for indicating the location of a SL-SSB, for example, because a large number of ARFCNs can correspond to unsuitable locations for a SL-SSB, and in some cases, multiple ARFCNs can indicate the same RB.

[0097] Figure 5 5 is a diagram illustrating an example of SL-SSB opportunities within an RB set for communication between wireless communication devices (such as UEs). A bandwidth portion 504 may be configured on a shared frequency band 502. The bandwidth portion 504 may include multiple channels 506 (e.g., channels 506a, 506b, and 506c). Each UE may be configured with an RB set in each channel 506. For example, RB sets for three UEs (UE0 510, UE1 520, and UE2 530) are illustrated. Each UE may be configured with a corresponding GB 514, 524, 534 (e.g., based on the UE's receive capabilities). In some implementations, the minimum RB set may be the size of the minimum RB set configured for the UE. For example, as illustrated, the RB set 522 for UE 520 may be the smallest because GB 534 is the largest. Therefore, the minimum RB set 540 may have the same size as the RB set 522. In some implementations, the minimum RB set 540 can be the minimum configurable size for a UE (e.g., based on the maximum GB size), even if no UE is actually configured with the minimum RB set 540. The minimum RB set 540 within each channel can be common to each of the UEs 510, 520, 530. Thus, if an SL-SSB is transmitted in the minimum RB set 540, each UE configured with an RB set on that channel 506 can receive the SL-SSB.

[0098] In one aspect, the indication may identify the location of a reference SL-SSB opportunity 550 rather than an ARFCN indicating a center frequency of the SL-SSB. The SL-SSB opportunity may refer to a frequency location at which the SL-SSB is transmitted. In some implementations, the indication may efficiently indicate the location of the SL-SSB opportunity because the SL-SSB opportunity is within a 20 MHz basic channel unit, within an RB set, or within a minimum RB set. Additionally, the SL-SSB opportunity may be a reference SL-SSB opportunity, or the RB set may be a reference RB set in one channel that corresponds to the SL-SSB opportunities in other channels. The SL-SSB opportunities in each channel may have the same relative positioning such that the UE may determine the SL-SSB opportunity in each channel based on the reference SL-SSB opportunity or the reference RB set.

[0099] In a first example, the indication may be a value similar to the ARFCN, but with a different formula to indicate the center frequency of the SL-SSB. For example, a defined RRC parameter such as sl-AbsoluteFrequencySSB may be used to signal an index indicating the location of the SL-SSB. In one implementation, the following formula may indicate the center frequency (F) of the SL-SSB. S-SSB ):

[0100] F S-SS =F BWP +ΔF×index

[0101] Among them F BWP is the starting frequency of the bandwidth portion 504, ΔF is a preconfigured or configured step size, and the index is a signaled value. For example, ΔF may be preconfigured in a standard document or specification, or configured via broadcast or RRC signaling. For example, ΔF may be 15 kHz, 20 MHz, or another configured size. In the illustrated example, ΔF 550 may be configured as 10 MHz. An index (e.g., 3) may be selected to restrict the SL-SSB to within one RB set (e.g., a minimum RB set). In some implementations, the formula may also include an offset (e.g., to adjust the positioning of the SL-SSB opportunity within the RB set). The offset may be preconfigured or configured. For example, in the illustrated example, a ΔF 570 of 20 MHz and an offset 572 of 10 MHz may be used to indicate a reference SL-SSB opportunity.

[0102] F S-DDB =F BWP +ΔF×index+offset

[0103] In a second example, the frequency position of the SL-SSB opportunity may be the center frequency position of the RB set. The indication may indicate which RB set includes the reference SL-SSB position. The size of the indication may be based on the number of configured RB sets within the BWP, which may be much smaller than the number of ARFCNs. For example, in the illustrated example, two bits (e.g., 01) may be used to indicate three possible RB sets. In some implementations, a defined RRC parameter (such as sl-AbsoluteFrequencySSB) may be used with different interpretations of the value to indicate the RB set that includes the reference SL-SSB opportunity. In some implementations, a new parameter may be defined to indicate the RB set that includes the reference SL-SSB opportunity.

[0104] In a third example, the frequency location of the SL-SSB opportunity 550 can be indicated as an RB offset 580 of the first resource block of the SL-SSB opportunity 550 from the first RB of the bandwidth portion 504. The offset 580 can be selected so that the SL-SSB opportunity 550 is within an RB set (e.g., a minimum RB set). The RB offset 580 can be signaled as an RRC parameter.

[0105] In one aspect, the RB set configuration may be different for different links, for example, due to different intra-cell guard band sizes. However, synchronizing nodes to transmit SL-SSBs in the same frequency enables single frequency network (SFN) transmission. Using the minimum RB set 540 of all possible RB set configurations to carry the SL-SSB enables communication for different links with different RB set configurations. Therefore, in some implementations, the RB set offset may be selected such that the SL-SSB falls within the minimum RB set 540 and does not overlap with any GB (e.g., GB 514, 524, or 534).

[0106] On the other hand, supporting multiple candidate SL-SSB opportunities when the resource pool for the UE includes multiple RB sets can alleviate LBT uncertainty. For example, if the UE is configured with a single SL-SSB opportunity 550, if there is another device using the channel so that the UE detects energy during the LBT process, the UE may not be able to transmit the SL-SSB on the single SL-SSB opportunity 550. If the UE is configured with multiple SL-SSB opportunities 550 (e.g., based on a reference SL-SSB opportunity 550), the UE may perform an LBT process on each channel and select one or more channels to transmit the SL-SSB through the LBT process.

[0107] like Figure 5As illustrated, the other SL-SSB opportunities 552 may correspond to the reference SL-SSB opportunity 550. For example, the other SL-SSB opportunities 552 may have the same relative frequency positioning relative to the center of the channel 506 as the reference SL-SSB opportunity. The positioning of the other SL-SSB opportunities 552 may be similarly defined relative to the RB set 512 or the minimum RB set 540. The number of candidate SL-SSB opportunities may be predefined or configured via RRC signaling.

[0108] In a first example, candidate SL-SSB opportunities may be located in each RB set. That is, the number of SL-SSB opportunities may depend on the number of RB sets within bandwidth portion 504. In a second example, the RRC signaling may include an absolute bitmap indicating whether each resource block set in the resource block sets within the bandwidth portion includes an SL-SSB opportunity. That is, each bit of the bitmap may indicate whether the corresponding RB set includes an SL-SSB opportunity. In a third example, the RRC signaling may indicate a resource indication value indicating the number of consecutive resource block sets within bandwidth portion 504 that include SL-SSB opportunities, starting from a reference resource block set. In a fourth example, the indication includes a bitmap indicating whether each resource block set in other resource block sets within bandwidth portion 504, starting from a resource block set in a frequency channel above the reference resource block set (e.g., channel 506c) and wrapping around to a lower frequency channel (e.g., RB set 512a in channel 506a), includes an SL-SSB opportunity 552.

[0109] When the UE has an SL-SSB to send and has passed the LBT procedure for one or more SL-SSB opportunities, the UE may determine one or more SL-SSB opportunities on which to send the SL-SSB. In some implementations, the UE may send the SL-SSB on all channels or RB sets that have passed the LBT procedure. Transmitting on multiple sets may increase frequency diversity and / or enable soft combining of SL-SSBs from different RB sets. In some implementations, the UE may send the SL-SSB on a set of consecutive resource blocks that have passed the LBT procedure. In some implementations, the UE may select one of the SL-SSB opportunities that meets the conditions for sending the SL-SSB. Transmitting on a single RB set may avoid splitting the transmit power among multiple channels, which may increase the range of the transmission compared to transmitting the SL-SSB on multiple channels.

[0110] Figure 66 is a message diagram 600 illustrating example messages between a base station 602 and one or more UEs 510, 520. The base station 602 may utilize parameters to configure UEs within its coverage area. In some implementations, the UEs 510, 520 may be connected to the base station 602, for example, via a Uu link with an RRC connection. The base station 602 may send an RRC configuration message to the UEs 510, 520. In some implementations, the UE 520 may not be connected to the base station 602 or may not receive the RRC configuration message. Another UE 510 may forward the contents of the RRC message to the UE 520.

[0111] In one aspect, the base station 602 can send an indication 610 of a frequency location of the SL-SSB within the bandwidth portion of the shared spectrum band. For example, the indication 610 can indicate the frequency location of the SL-SSB opportunity 550 within the bandwidth portion 504 of the shared spectrum band 502. In some implementations, the indication 610 is an RRC configuration message. The indication 610 can also configure the bandwidth portion 504 and / or the RB sets 512, 522, 532. As discussed above, the indication 610 can have a format specific to the shared spectrum that can be more efficient than signaling the ARFCN of the center frequency of the SL-SSB. In some implementations, the first UE 510 that receives the indication 610 can forward the contents of the indication to one or more other UEs 520. For example, the first UE 510 can send the indication 612, which can be, for example, a sidelink RRC message.

[0112] In one aspect, the first UE 510 may determine one or more SL-SSB opportunities 550, 552 based on the indication 610. The UE 510 may transmit an SL-SSB 620 on the one or more SL-SSB opportunities 550, 552. For example, the SL-SSB may include a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH). In some implementations, transmitting the SL-SSB 620 may include transmitting interleaved RBs for all S-PSS / S-SSS / PSBCH. In another example, transmitting the SL-SSB 620 may use interleaved RBs only for the PSBCH and apply an occupied channel bandwidth (OCB) exemption to the S-PSS and S-SSS. In some implementations, transmitting the SL-SSB 620 may include repeating the S-PSS / S-SSS / PSBCH N times in the frequency domain, and there may be gaps between the repetitions to meet the OCB requirement. In some implementations, the transmit SL-SSB 620 may repeat only the S-PSS / S-SSS K times in the frequency domain and may rate match the PSBCH. There may be gaps between these repetitions to meet OCB requirements. In some implementations, the transmit SL-SSB 620 may maintain the legacy S-PSS / S-SSS / PSBCH (e.g., in licensed spectrum) while repeating the PSBCH N times in the frequency domain and rate matching the PSBCH to the S-PSS / S-SSS symbols, and there may be gaps between these PSBCH repetitions to meet OCB requirements. The transmit SL-SSB 620 may optionally apply an OCB exemption to all S-PSS / S-SSS / PSBCH.

[0113] The second UE 520 may also determine the one or more SL-SSB opportunities 550, 552 based on the indication 610 or the indication 612. The second UE 520 may receive the SL-SSB 620 at the one or more SL-SSB opportunities 550, 552. For example, the UE 520 may be configured to receive the SL-SSB 620 using any of the transmission formats discussed above. The second UE 520 may also transmit the SL-SSB 630 at the one or more SL-SSB opportunities 550, 552. The first UE 510 and the second UE 520 may select different time domain resources to transmit the SL-SSB 620 and the SL-SSB 630. For example, the LBT process may ensure that only one of the first UE 510 or the second UE 520 transmits on the channel. The second UE 520 may transmit the SL-SSB in the same manner as the first UE 510, except that the S-PSS, S-SSS, and PBSCH may be different.

[0114] SL-SSB 620 may allow a receiving second UE 520 to receive other sidelink channels, such as a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH), from UE 510. Similarly, SL-SSB 630 may allow a receiving first UE 510 to receive the PSCCH and / or PSSCH from UE 520. Thus, after exchanging at least one of SL-SSB 620 or SL-SSB 630, first UE 510 and second UE 520 may engage in sidelink communication 640.

[0115] Figure 7 7 is a resource diagram 700 illustrating a bitmap 710 for indicating whether each of the resource block sets 512 within the bandwidth portion 504 includes an SL-SSB opportunity 550, 552. The bitmap 710 may be a field within the indicator 610. The length of the bitmap 710 may be equal to the number of RB sets configured in the bandwidth portion 504. For example, as illustrated, the bandwidth portion 504 may include four RB sets 512 (e.g., 512a, 512b, 512c, and 512d). The bitmap 710 may have a value of 0101, which indicates that the RB sets 512b and 512d include an SL-SSB opportunity 550 or 552.

[0116] Figure 8 8 is a resource diagram 800 illustrating a bitmap 810 for indicating whether a non-reference RB set 512 within a bandwidth portion 504 includes an SL-SSB opportunity 552. The bitmap 810 may be a field in the indicator 610. The indicator 610 may indicate a reference RB set (e.g., RB set 512b). The length of the bitmap 810 may be equal to the number of RB sets configured in the bandwidth portion 504 minus one. For example, as illustrated, the bandwidth portion 504 may include four RB sets 512 (e.g., 512a, 512b, 512c, and 512d), and the length of the bitmap 810 may be three. The bitmap 810 may have a value of 010. The bitmap 810 indicates whether each set of resource blocks in the other resource block sets 512 within the bandwidth portion 504, starting with RB set 512c in the frequency channel 506c above the reference RB set 512b and wrapping around to the highest frequency channel (e.g., channel 506d) in the bandwidth portion 504 to the lower frequency channels (e.g., channel 506a), includes an SL-SSB opportunity. Thus, as illustrated, the bitmap 810 indicates that RB sets 512b and 512d include SL-SSB opportunities 550 or 552.

[0117] Figure 9 is a conceptual data flow diagram 900 illustrating the data flow between different parts / components in an example UE 904, which may be an example of a UE 104 including the SL-SSB component 140.

[0118] UE 904 may also include a receiver component 910 and a transmitter component 912. Receiver component 910 may include, for example, an RF receiver for receiving the signals described herein. Transmitter component 912 may include, for example, an RF transmitter for transmitting the signals described herein. In some implementations, receiver component 910 and transmitter component 912 may be co-located on a transceiver (such as Figure 3 Tx / Rx 354).

[0119] Receiver component 910 may receive downlink or sidelink signals, such as indication 610 or 612, SL-SSB 620 or 630, and communication 640. Receiver component 910 may communicate indication 610 or 612 to indication receiving component 142. Receiver component 910 may communicate SL-SSB 620 or 630 to SL-SSB receiving component 144.

[0120] Indication receiving component 142 can receive indication 610 or 612. Indication receiving component 142 can decode the received indication to determine an SL-SSB opportunity. Indication receiving component 142 can determine one or more values ​​signaled in indication 610, such as ΔF 560, offset 572, RB offset 580, index 920, RB index 930, bitmap 710, bitmap 810, or resource indication value (RIV) 940. Indication receiving component 142 can then determine a reference RB set and / or a reference SL-SSB opportunity 550 based on the signaled values. In some implementations, indication receiving component 142 can determine whether one or more of the other RB sets configured for UE 904 include a corresponding SL-SSB opportunity 552. Indication receiving component 142 can output the reference SL-SSB opportunity 550 and any corresponding SL-SSB opportunity 552 to both SL-SSB receiving component 144 and SL-SSB transmitting component 146.

[0121] The SL-SSB receiving component 144 can be configured to receive the SL-SSBs 620, 630 at the SL-SSB opportunities 550, 552 based on the reference resource block sets at the frequency locations. For example, the SL-SSB receiving component 144 can monitor the signals received via the receiver component 910 at the indicated SL-SSB opportunities 550, 552 for the SL-SSBs 620, 630.

[0122] The SL-SSB transmitting component 146 can be configured to transmit the SL-SSB 620, 630 at the SL-SSB opportunities 550, 552 based on the reference resource block set at the frequency location. For example, the SL-SSB receiving component 144 can generate the SL-SSB signal for transmission at the indicated SL-SSB opportunities 550, 552 via the transmitter component 912.

[0123] Figure 10 1 is a flow chart of an example method 1000 for operating a UE 104 (e.g., a first UE 104) to transmit or receive SL-SSB in a shared spectrum. The method 1000 may be performed by a UE (such as UE 104, which may include memory 360 and may be the entire UE 104 or a component of UE 104 such as SL-SSB component 140, TX processor 368, RX processor 356, or controller / processor 359). The method 1000 may be performed by the SL-SSB component 140 in communication with the sidelink configuration component 120 of the base station 102 and the SL-SSB component 140 of the second UE 104.

[0124] At block 1010, the method 1000 includes receiving, at a wireless device, an indication of a frequency location of an SL-SSB within a bandwidth portion of a shared frequency band. In one aspect, for example, the UE 104, the RX processor 356, and / or the controller / processor 359 can execute the SL-SSB component 140, the transmitter component 912, and / or the indication receiving component 142 to receive, at the wireless device (e.g., the UE 104, 510, 520, or 904), an indication 610 of a frequency location of an SL-SSB 620, 630 within the bandwidth portion 504 of the shared frequency band 502. In some implementations, the indication 610 includes an index 920 of a sidelink absolute frequency that indicates a starting frequency of the SL-SSB opportunity 550 based on the bandwidth portion 504, a step size (e.g., ΔF 560), and a center frequency of the index 920. In some implementations, the center frequency of the SL-SSB opportunity 550 is further based on an offset 572 from a starting point of the step size. In some implementations, indication 610 identifies the center frequency of the reference resource block set (e.g., RB set 512b) as an index of a resource block set within bandwidth portion 504 (e.g., RB index 930). In some implementations, indication 610 includes an offset (e.g., RB offset 580) of the first resource block of SL-SSB opportunity 550 from the first resource block of bandwidth portion 504. In some implementations, the reference resource block set (e.g., RB set 512b) is within a minimum resource block set 540, which is the intersection of a set of supported resource block set configurations. In some implementations, minimum resource block set 540 excludes resource blocks in a guard band (e.g., GB 514) between a first 20 MHz channel (e.g., channel 506a) and another channel (e.g., 506b) within bandwidth portion 504, and excludes resource blocks in one or more other guard bands (e.g., GB 524 or 534) for at least one other wireless device. Thus, the UE 104, RX processor 356 and / or controller / processor 359 executing the SL-SSB component 140, receiver component 910 and / or indication reception component 142 may provide components for receiving an indication of the frequency location of the SL-SSB within the bandwidth portion of the shared frequency band at the wireless device.

[0125] At block 1020, the method 1000 includes transmitting or receiving an SL-SSB on the SL-SSB opportunity based on the reference resource block set at the frequency location. In one aspect, for example, the UE 104, the TX processor 368, the RX processor 356, and / or the controller / processor 359 may execute the SL-SSB component 140, the SL-SSB transmitting component 146, and / or the SL-SSB receiving component 144 to transmit or receive an SL-SSB 620, 630 on the SL-SSB opportunity 550, 552 based on the reference resource block set (e.g., RB set 512b) at the frequency location. The reference resource block set for the SL-SSB is within the first 20 MHz channel 506a separated from another channel 506b in the bandwidth portion 504 by the GB 514.

[0126] In some implementations, multiple SL-SSB opportunities 552 are supported in the other resource block sets 512 within the bandwidth portion 504 corresponding to the frequency location of the SL-SSB within the reference resource block set (e.g., RB set 512b). In such implementations, at sub-block 1022, block 1020 may optionally include transmitting or receiving the SL-SSB at one or more SL-SSB opportunities from the multiple SL-SSB opportunities that meet the LBT condition. For example, in some implementations, at sub-block 1024, block 1020 may optionally include transmitting the SL-SSB at each SL-SSB opportunity that meets the LBT condition. In some implementations, at sub-block 1026, block 1020 may optionally include transmitting the SL-SSB on a set of consecutive resource blocks. In some implementations, at sub-block 1028, block 1020 may optionally include selecting one of the SL-SSB opportunities that meets the LBT condition for transmitting the SL-SSB. For example, the SL-SSB sending component 146 can select the one SL-SSB opportunity randomly or pseudo-randomly.

[0127] Thus, the UE 104 , the RX processor 356 , and / or the controller / processor 359 executing the SL-SSB component 140 , the SL-SSB transmission component 146 , and / or the SL-SSB reception component 144 may provide components for transmitting or receiving a SL-SSB at a SL-SSB opportunity based on a set of reference resource blocks at a frequency location.

[0128] Some further example clauses

[0129] Specific implementation examples are described in the following numbered clauses:

[0130] Clause 1. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: a transceiver; a memory storing computer-executable instructions; a processor coupled to the transceiver and the memory and configured to execute the computer-executable instructions to: receive, via the transceiver, an indication of a frequency location of a side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and send or receive, via the transceiver, the SL-SSB at an SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0131] Clause 2. An apparatus according to clause 1, wherein the indication comprises an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

[0132] Clause 3. The apparatus of clause 2, wherein the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

[0133] Clause 4. The apparatus of clause 1, wherein the indication identifies a center frequency of the reference set of resource blocks as an index of a set of resource blocks within the bandwidth portion.

[0134] Clause 5. The apparatus of clause 1, wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

[0135] Clause 6. The apparatus of any of clauses 1 to 5, wherein the reference resource block set is within a minimum resource block set, the minimum resource block set being the intersection of a set of supported resource block set configurations.

[0136] Clause 7. An apparatus according to any one of clauses 1 to 6, wherein multiple SL-SSB opportunities are supported in other resource block sets within the bandwidth portion corresponding to the frequency position of the SL-SSB within the reference resource block set, wherein in order to send or receive the SL-SSB on the SL-SSB opportunity based on the reference resource block set, the processor is configured to execute the instructions to send or receive the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities that satisfy a listen-before-talk (LBT) condition.

[0137] Clause 8. The apparatus of clause 7, wherein the plurality of SL-SSB opportunities comprises one SL-SSB opportunity in each of the other sets of resource blocks within the bandwidth portion.

[0138] Clause 9. The apparatus of clause 7, wherein the indication comprises a bitmap indicating whether each of the resource block sets within the bandwidth portion includes a SL-SSB opportunity.

[0139] Clause 10. The apparatus of clause 7, wherein the indication comprises a resource indication value indicating a number of a set of consecutive resource blocks within the bandwidth portion starting from the set of reference resource blocks that include SL-SSB opportunities.

[0140] Clause 11. An apparatus according to clause 7, wherein the indication comprises a bitmap indicating whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

[0141] Clause 12. An apparatus according to any one of clauses 7 to 11, wherein in order to send the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities, the processor is configured to execute the instructions to send the SL-SSB on each SL-SSB opportunity that satisfies the LBT condition.

[0142] Clause 13. An apparatus according to any one of clauses 7 to 11, wherein in order to send the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities, the processor is configured to execute the instructions to send the SL-SSB on a set of consecutive resource blocks.

[0143] Clause 14. An apparatus according to any one of clauses 7 to 11, wherein, in order to send the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities, the processor is configured to execute the instructions to select one SL-SSB opportunity among the SL-SSB opportunities that satisfies the LBT condition for sending the SL-SSB.

[0144] Clause 15. A method of wireless communication, the method comprising: receiving, at a wireless device, an indication of a frequency location of a side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and sending or receiving, at the wireless device, the SL-SSB at a SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0145] Clause 16. The method of clause 15, wherein the indication comprises an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

[0146] Clause 17. The method of clause 16, wherein the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

[0147] Clause 18. The method of clause 15, wherein the indication identifies a center frequency of the reference set of resource blocks as an index of a set of resource blocks within the bandwidth portion.

[0148] Clause 19. The method of clause 15, wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

[0149] Clause 20. The method of any of clauses 15 to 20, wherein the reference resource block set is within a minimum resource block set, the minimum resource block set being the intersection of a set of supported resource block set configurations.

[0150] Clause 21. A method according to any one of clauses 15 to 20, wherein multiple SL-SSB opportunities are supported in other resource block sets within the bandwidth part corresponding to the frequency position of the SL-SSB within the reference resource block set, wherein sending or receiving the SL-SSB on the SL-SSB opportunity based on the reference resource block set includes: sending or receiving the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities that satisfy a listen-before-talk (LBT) condition.

[0151] Clause 22. The method of clause 21, wherein the plurality of SL-SSB opportunities comprises one SL-SSB opportunity in each of the other sets of resource blocks within the bandwidth portion.

[0152] Clause 23. The method of clause 21, wherein the indication comprises a bitmap indicating whether each of the resource block sets within the bandwidth portion includes a SL-SSB opportunity.

[0153] Clause 24. The method of clause 21, wherein the indication comprises a resource indication value indicating a number of consecutive sets of resource blocks within the bandwidth portion starting from the reference set of resource blocks that include SL-SSB opportunities.

[0154] Clause 25. A method according to clause 21, wherein the indication includes a bitmap indicating whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

[0155] Clause 26. A method according to any one of clauses 21 to 24, wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities includes: sending the SL-SSB on each SL-SSB opportunity that satisfies the LBT condition.

[0156] Clause 27. A method according to any one of clauses 21 to 24, wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities of the plurality of SL-SSB opportunities comprises sending the SL-SSB on a set of consecutive resource blocks.

[0157] Clause 28. A method according to any one of clauses 21 to 24, wherein sending or receiving the SL-SSB on one or more SL-SSB opportunities among the multiple SL-SSB opportunities includes: selecting one SL-SSB opportunity among the SL-SSB opportunities that meets the LBT condition for sending the SL-SSB.

[0158] Clause 29. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: a component for receiving an indication of a frequency location of a first side link synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and a component for sending the first SL-SSB on a SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band; and a component for receiving a second SL-SSB on the SL-SSB opportunity.

[0159] Clause 30. An apparatus according to clause 29, wherein the means for sending the first SL-SSB on a SL-SSB opportunity based on the set of reference resource blocks at the frequency location is configured to send the SL-SSB according to a method according to any one of clauses 15 to 28.

[0160] Clause 31. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a processor of a wireless device, cause the wireless device to: receive an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and send or receive the SL-SSB at a SL-SSB opportunity based on a set of reference resource blocks at the frequency location, wherein the set of reference resource blocks for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

[0161] Clause 32. The non-transitory computer-readable medium of Clause 31, wherein the computer-executable instructions comprise instructions for performing the method of any one of Clauses 15 to 28.

[0162] It should be understood that the specific order or hierarchy of blocks in the disclosed process / flowchart is merely illustrative of exemplary methods. It should be understood that the specific order or hierarchy of blocks in the process / flowchart may be rearranged based on design preferences. Furthermore, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, but are not intended to be limited to the specific order or hierarchy presented.

[0163] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but to conform to the full scope consistent with the language claims, wherein elements mentioned in the singular are not intended to represent "one and only one" unless specifically stated otherwise, but rather "one or more". The word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any aspect described herein as "exemplary" is not necessarily to be interpreted as being preferred or having an advantage over other aspects. Unless otherwise specifically stated, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, which may include multiple A, multiple B, or multiple C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combination may include one or more members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are or later become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is expressly recited in the claims. Words such as "module," "mechanism," "element," "device," etc. are not intended to be substituted for the word "component." Thus, no claim element will be construed as part-plus-function unless the element is expressly recited using the phrase "component for..."

Claims

1. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: transceiver; a memory storing computer-executable instructions; and a processor coupled to the transceiver and the memory and configured to execute the computer-executable instructions to: receiving, via the transceiver, an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and The SL-SSB is sent or received via the transceiver on an SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

2. The apparatus of claim 1 , wherein the indication comprises an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

3. The apparatus of claim 2, wherein the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

4. The apparatus of claim 1, wherein the indication identifies a center frequency of the reference resource block set as an index of a resource block set within the bandwidth part.

5. The apparatus of claim 1 , wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

6. The apparatus of claim 1, wherein the reference resource block set is within a minimum resource block set, the minimum resource block set being an intersection of a set of supported resource block set configurations.

7. The apparatus according to claim 1, wherein multiple SL-SSB opportunities are supported in other resource block sets corresponding to the frequency position of the SL-SSB within the reference resource block set within the bandwidth part, wherein in order to send or receive the SL-SSB on the SL-SSB opportunity based on the reference resource block set, the processor is configured to execute the instructions to send or receive the SL-SSB on one or more SL-SSB opportunities that meet a listen-before-talk (LBT) condition among the multiple SL-SSB opportunities.

8. The apparatus of claim 7, wherein the plurality of SL-SSB opportunities comprises one SL-SSB opportunity in each of the other resource block sets within the bandwidth portion.

9. The apparatus of claim 7, wherein the indication comprises a bitmap indicating whether each of the resource block sets within the bandwidth part includes an SL-SSB opportunity.

10. The apparatus of claim 7, wherein the indication comprises a resource indication value indicating a number of consecutive resource block sets including SL-SSB opportunities starting from the reference resource block set within the bandwidth part.

11. The apparatus of claim 7 , wherein the indication comprises a bitmap indicating whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

12. The apparatus of claim 7 , wherein, in order to transmit the SL-SSB on one or more of the plurality of SL-SSB opportunities, the processor is configured to execute the instructions to transmit the SL-SSB on each SL-SSB opportunity that satisfies the LBT condition.

13. The apparatus of claim 7, wherein, to transmit the SL-SSB on one or more of the plurality of SL-SSB opportunities, the processor is configured to execute the instructions to transmit the SL-SSB on a set of consecutive resource blocks.

14. The apparatus of claim 7 , wherein, in order to transmit the SL-SSB on one or more of the plurality of SL-SSB opportunities, the processor is configured to execute the instructions to select one of the SL-SSB opportunities that satisfies the LBT condition for transmitting the SL-SSB.

15. A method of wireless communication, the method comprising: receiving, at the wireless device, an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; as well as The SL-SSB is sent or received at the wireless device on an SL-SSB opportunity based on a reference resource block set at the frequency location, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band.

16. The method of claim 15, wherein the indication comprises an index of a sidelink absolute frequency, the index indicating a starting frequency of the SL-SSB opportunity based on the bandwidth portion, a step size, and a center frequency of the index.

17. The method of claim 16, wherein the center frequency of the SL-SSB opportunity is further based on an offset from a starting point of a step size.

18. The method of claim 15, wherein the indication identifies a center frequency of the reference resource block set as an index of a resource block set within the bandwidth part.

19. The method of claim 15, wherein the indication comprises an offset of a first resource block of the SL-SSB opportunity from a first resource block of the bandwidth portion.

20. The method of claim 15, wherein the reference resource block set is within a minimum resource block set, the minimum resource block set being an intersection of a set of supported resource block set configurations.

21. The method of claim 15 , wherein a plurality of SL-SSB opportunities are supported in other resource block sets within the bandwidth portion corresponding to the frequency location of the SL-SSB within the reference resource block set, wherein transmitting or receiving the SL-SSB at the SL-SSB opportunity based on the reference resource block set comprises: The SL-SSB is sent or received on one or more SL-SSB opportunities that satisfy a listen-before-talk (LBT) condition among the multiple SL-SSB opportunities.

22. The method of claim 21, wherein the plurality of SL-SSB opportunities comprises one SL-SSB opportunity in each of the other resource block sets within the bandwidth portion.

23. The method of claim 21, wherein the indication comprises a bitmap indicating whether each of the resource block sets within the bandwidth part includes an SL-SSB opportunity.

24. The method of claim 21, wherein the indication comprises a resource indication value indicating a number of consecutive resource block sets including SL-SSB opportunities starting from the reference resource block set within the bandwidth part.

25. The method of claim 21 , wherein the indication comprises a bitmap indicating whether each of the other resource block sets within the bandwidth portion, starting from a resource block set in a frequency channel above the reference resource block set and wrapping around to a lower frequency channel, includes an SL-SSB opportunity.

26. The method of claim 21 , wherein sending or receiving the SL-SSB on one or more of the plurality of SL-SSB opportunities comprises: The SL-SSB is sent at each SL-SSB opportunity that meets the LBT condition.

27. The method of claim 21 , wherein sending or receiving the SL-SSB on one or more of the plurality of SL-SSB opportunities comprises: The SL-SSB is sent on a set of consecutive resource blocks.

28. The method of claim 21 , wherein sending or receiving the SL-SSB on one or more of the plurality of SL-SSB opportunities comprises: Select one of the SL-SSB opportunities that satisfies the LBT condition for sending the SL-SSB.

29. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: means for receiving an indication of a frequency location of a first sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; means for transmitting the first SL-SSB on a SL-SSB opportunity based on a set of reference resource blocks at the frequency location, wherein the set of reference resource blocks for the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth portion by a guard band; and Means for receiving a second SL-SSB on said SL-SSB opportunity.

30. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a processor of a wireless device, cause the wireless device to: receiving an indication of a frequency location of a sidelink synchronization signal block (SL-SSB) within a bandwidth portion of a shared frequency band; and The SL-SSB is sent or received at the SL-SSB opportunity based on a reference resource block set at the frequency position, wherein the reference resource block set of the SL-SSB is within a first 20 MHz channel separated from another channel in the bandwidth part by a guard band.

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