Synchronization signal for sidelink

Abstract

Sidelink synchronization helps provide a timing reference for sidelink communications, including the transmission of sidelink messages and / or the reception of sidelink messages. The receive beam and the transmit beam may change due to a change in the position and / or direction of the transmitting wireless device. An apparatus for wireless communication at a wireless device determines a variable duration for a SLSS. The apparatus transmits the SLSS using the variable duration determined by the wireless device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Non-Provisional Application No. 16 / 992,700, filed on August 13, 2020, entitled “SYNCHRONIZATION SIGNAL FOR SIDELINK,” and U.S. Provisional Application No. 62 / 886,783, filed on August 14, 2019, entitled “VARIABLEDURATION SSB FOR SIDELINK,” the entire contents of which are expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to communication systems and, more particularly, to sidelink-based wireless communications. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. 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.

[0005] 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 municipal, national, regional, 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 Third Generation Partnership Project (3GPP) and is designed to meet new requirements related to latency, reliability, security, scalability (e.g., Internet of Things (IoT)), and other requirements. 5G NR includes services related to 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. Aspects of wireless communications may include direct communications between devices, such as in V2X, V2V, and / or D2D communications. There is a need to further improve V2X, V2V, and / or D2D technologies. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify the 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 a more detailed description that is presented later.

[0007] Sidelink synchronization helps provide a timing reference for sidelink communications, including the transmission of sidelink messages and / or the reception of sidelink messages. A sidelink synchronization signal (SLSS) is used for synchronization in time and frequency. The SLSS may include a sidelink primary synchronization signal (PSS), a sidelink secondary synchronization signal (SSS), or a physical broadcast channel (PBCH).

[0008] A user equipment (UE) may be configured to act as a source of SLSS. The UE may be instructed by the network to send SLSS, the UE may decide to send SLSS on its own when covered by a cell, or the UE may send SLSS when out of cell coverage. The UE may be configured to send SLSS using beamforming, which may allow the sending UE to consider distance coverage, but at the expense of angle coverage. However, for example, due to changes in the position and / or orientation of the sending UE, the receiving beam may change for the same transmitting beam. The aspects presented herein provide a solution to the problem of changes in the receiving beam and / or transmitting beam due to changes in the position and / or orientation of the sending UE by utilizing a variable duration for sending SLSS. In some aspects, a wider beam may be used to send SLSS, which may compensate for changes in the orientation of the sending UE.

[0009] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. An example apparatus for wireless communication at a wireless device determines a variable duration for a SLSS. The example apparatus transmits the SLSS using the variable duration determined by the wireless device.

[0010] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. An example apparatus for wireless communication at a wireless device searches for a first SLSS based on a first duration for initial acquisition. The example apparatus searches for a second SLSS based on a second duration for refinement. In some aspects, the first duration can be longer than the second duration.

[0011] To achieve the foregoing and related ends, one or more aspects include 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 represent only a few of the various ways in which the principles of the various aspects may be employed, and the present description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0013] Figure 2 Example aspects of a sidelink slot structure are shown.

[0014] Figure 3 is a diagram illustrating an example of a first device and a second device involved in wireless communication based on, for example, V2V, V2X and / or device-to-device communication.

[0015] Figure 4 An example of wireless communication between devices based on V2X / V2V / D2D communication is shown.

[0016] Figure 5 An example communication flow between a first device and a second device is shown, in accordance with certain aspects of the present disclosure.

[0017] Figure 6 is a flow chart of a wireless communication method.

[0018] Figure 7 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example apparatus.

[0019] Figure 8 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0020] Fig. 9 is a flow chart of a wireless communication method.

[0021] Fig.10 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example apparatus.

[0022] Fig.11 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system. DETAILED DESCRIPTION

[0023] 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 configuration in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing 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 confusion with these concepts.

[0024] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0025] As an example, any part of an element or any combination of elements may be implemented as a "processing system" including one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted as referring to 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., whether referring to software, firmware, middleware, microcode, hardware description languages, or other.

[0026] Therefore, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, these 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. Storage media may be any available media that a computer can access. As an example and not limitation, such a computer-readable medium may include a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), an optical disk storage, a magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, or any other medium that can be used to store computer executable code in the form of computer-accessible instructions or data structures.

[0027] Figure 1 1 is a diagram showing 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 a core network (e.g., 5GC) 190. 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. A small cell includes a femto cell, a pico cell, and a micro cell.

[0028] A base station 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 via a backhaul link 132 (e.g., an S1 interface). A base station 102 configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with the core network 190 via a backhaul link 184. The base station 102 may perform one or more of the following functions, among other functions: transmission of user data, wireless 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, non-access distribution layer (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backhaul link 134 (eg, an X2 interface). The backhaul link 134 may be wired or wireless.

[0029] 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 can be overlapping geographic coverage areas 110. For example, a small cell 102′ macro base station 102 can have a coverage area 110′ that overlaps with the coverage area 110 of one or more macro base stations 102. A network including small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between the base station 102 and the UE 104 can include an uplink (UL) (also known as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also known as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. The base station 102 / UE 104 may use spectrum (x component carriers) of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation totaling up to Yx MHz for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric for DL ​​and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The 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 carrier may be referred to as a secondary cell (SCell).

[0030] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use 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). The D2D communication may be through various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0031] The wireless communication system may also include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether a channel is available prior to communication.

[0032] The small cell 102' can operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' can adopt NR and use the same 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' adopting NR in the unlicensed spectrum can enhance coverage and / or increase the capacity of the access network.

[0033] Whether a small cell 102′ or a large cell (e.g., a macro base station), the base station 102 can include an eNB, a gNodeB (gNB), or other types of base stations. Some base stations 180, such as gNBs, can operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies for communicating with UE 104. When a gNB operates in mmW or near mmW frequencies, the gNB can be referred to as a mmW base station. Extremely high frequency (EHF) is part of the radio frequency in the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz, with wavelengths between 1 mm and 10 mm. Radio waves in this frequency band can be referred to as millimeter waves. Near millimeter waves may extend down to frequencies of 3 GHz with wavelengths of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also called centimeter waves. Communications using the mmW / near mmW radio frequency bands have extremely high path loss and short distances. The mmW base station 180 can utilize beamforming 182 of the UE 104 to compensate for the extremely high path loss and short distance.

[0034] Devices can use beamforming to send and receive communications. For example, Figure 1 It is shown that the base station 180 can send beamformed signals to the UE 104 in one or more transmit directions 182'. The UE 104 can receive the beamformed signals from the base station 180 in one or more receive directions 182". The UE 104 can also send beamformed signals to the base station 180 in one or more transmit directions. The base station 180 can receive the beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 can perform beam training to determine the best receive and transmit directions for each base station 180 / UE 104. The transmit and receive directions of the base station 180 can be the same or different. The transmit and receive directions of the UE 104 can be the same or different. Although the beamformed signals are described between the UE 104 and the base station 102 / 180, aspects of the beamforming can be similarly applied by the UE 104 or roadside unit (RSU) 107 to communicate with another UE 104 or RSU 107, such as based on V2X, V2V or D2D communication.

[0035] The 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. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The 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 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and collecting charging information related to eMBMS.

[0036] 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. Typically, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to the IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0037] A base station may also be referred to as a gNB, Node B, evolved Node B (eNB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit receive point (TRP), or some other suitable term. 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 smart phone, 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, 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.

[0038] Some wireless communication networks may include vehicle-based communication devices that may communicate from vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node, such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes, such as a base station), and / or combinations thereof and / or used with other devices, which may be collectively referred to as vehicle-to-anything (V2X) communications. Again, referring to Figure 1 In some aspects, a UE 104, such as a transmitting vehicle user equipment (VUE) or other UE, can be configured to send messages directly to another UE 104. The communication can be based on V2V / V2X / V2I or other D2D communication, such as ProSe, etc. The V2V, V2X, V2I and / or D2D based communication can also be sent and received by other transmitting and receiving devices such as a roadside unit (RSU) 107. Aspects of the communication can be based on PC5 or sidelink communication, such as in combination with Figure 2 Although the following description may provide examples of V2X / D2D communications related to 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0039] Reference again Figure 1 In some aspects, a transmitting device such as UE 104 may include a duration component 198 configured to determine a variable duration for a SLSS. In some examples, UE 104 may use a first duration for a SLSS on a first channel and a second duration for a SLSS on a second channel. The example duration component 198 may also be configured to transmit the SLSS using a variable duration determined by the UE.

[0040] Reference again Figure 1 In some aspects, a receiving device such as UE 104 may include a first SLSS component 199 configured to search for a first SLSS. In some examples, UE 104 may search for the first SLSS based on a first duration for initial acquisition. UE 104 may also be configured to search for a second SLSS based on a second duration for refinement, wherein the first duration is longer than the second duration.

[0041] Although the following description may focus on variable duration for SLSS for sidelink communications, the concepts described herein are similarly applicable to other similar areas, such as establishing an access link connection (e.g., between a UE and a base station). In addition, 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 in which a device can provide a timing reference signal for a sidelink connection.

[0042] Figure 2Example diagrams 200 and 210 are shown, which show example time slot structures that can be used for wireless communication (e.g., for sidelink communication) between UE 104 and UE 104'. The time slot structure can be within a 5G / NR frame structure. Although the following description may focus on 5G NR, the concepts described herein are applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. This is just an example, and other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) can be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, 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. Figure 200 shows a single time slot transmission, which may correspond to a 0.5ms transmission time interval (TTI), for example. Diagram 210 shows an example two-slot aggregation, for example, an aggregation of two 0.5ms TTIs. Diagram 200 shows a single RB, while diagram 210 shows N RBs. In diagram 210, 10 RBs used for control are just an example. The number of RBs may be different.

[0043] The frame structure can be represented using a resource grid. Each time slot may include a resource block (RB) (also called a physical RB (PRB)) extending 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. Figure 2 As shown, some REs may include control information, for example, along with a demodulation RS (DMRS). Figure 2 It is also shown that the symbols may include a channel state information reference signal (CSI-RS). Figure 2The symbol indicated for DMRS or CSI-RS in the symbol indication symbol includes DMRS or CSI-RS RE. Such a symbol may also include REs including data. For example, if the number of ports for DMRS or CSI-RS is 1, and the comb-2 mode is used for DMRS / CSI-RS, half of the REs may include RS, and the other half of the REs may include data. The CSI-RS resource may start from any symbol of the time slot and may occupy 1, 2, or 4 symbols depending on the number of configured ports. The CSI-RS may be periodic, semi-permanent, or aperiodic (e.g., based on DCI triggering). For time / frequency tracking, the CSI-RS may be periodic or aperiodic. The CSI-RS may be sent in bursts of two or four symbols spread across one or two time slots. The control information may include sidelink control information (SCI). As described herein, at least one symbol may be used for feedback. Symbols before and / or after feedback may be used for a turnaround between reception of data and transmission of feedback. Although symbol 12 is shown for data, it may alternatively be an interval symbol to enable a turnaround of feedback in symbol 13. Another symbol, for example, at the end of a time slot may be used as a gap. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device, for example, in the next time slot. As shown, data may be sent in the remaining REs. The data may include data messages as described herein. The location of any of the SCI, feedback, and LBT symbols may differ from Figure 2 Example shown. Multiple time slots can be aggregated together. Figure 2 An example aggregation of two time slots is also shown. The total number of time slots can also be greater than two. When time slots are aggregated, the symbols used for feedback and / or spacing symbols may be different than for a single time slot. As shown in the single time slot example, although feedback is not illustrated for the aggregate example, feedback can also be assigned symbol(s) in a multiple time slot aggregation.

[0044] Figure 230 shows an example of various sidelink channels within a time slot structure. The physical sidelink control channel (PSCCH) 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 sidelink primary synchronization signal (S-PSS) can be within symbol 2 of a specific subframe of a frame. The S-PSS is used by UE104 to determine the subframe / symbol timing and physical layer identification. The sidelink secondary synchronization signal (S-SSS) can be within symbol 4 of a specific subframe of a frame. The S-SSS is used by the UE to determine the physical layer cell identification group number and radio frame timing. Based on the PCI, the UE can determine the location of the above-mentioned DM-RS. The physical sidelink broadcast channel (PSBCH) carrying the master information block (MIB) can be logically grouped with the S-PSS and S-SSS to form a sidelink synchronization signal (SS) / PBCH block (S-SSB). The MIB provides multiple RBs and a system frame number (SFN) in the system bandwidth. The data channel may carry user data, broadcast system information not transmitted through the PBCH, such as system information blocks (SIBs), and paging messages.

[0045] Figure 3 300 is a block diagram of a device 310 configured to communicate wirelessly with a device 350, for example, via V2V / V2X / D2D communication. The device 310 may include a transmitting device that communicates with a receiving device (e.g., device 350) via V2V / V2X / D2D communication. The communication may be based on, for example, a side link. The transmitting device 310 may include a UE, an RSU, etc. The receiving device may include a UE, an RSU, etc. The packet may be provided to a controller / processor 375 that implements layer 3 and layer 2 functions. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a media access control (MAC) layer.

[0046] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 includes a physical (PHY) layer, which may include error detection on a transmission channel, forward error correction (FEC) encoding / decoding of a transmission channel, interleaving, rate matching, mapping to a physical channel, physical modulation / demodulation channels, and MIMO antenna processing. The TX processor 316 is based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

[0047] At the device 350, each receiver 354RX receives a signal through its respective 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 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the device 350. If multiple spatial streams are destined for the device 350, they can be combined into a single OFDM symbol stream by the RX processor 356. 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 and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation point sent by the 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 controller / processor 359, which implements Layer 3 and Layer 2 functionality.

[0048] The controller / processor 359 may be associated with 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, packet reassembly, decryption, header decompression, and control signal processing between transport and logical channels. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0049] Similar to the functions described in conjunction with transmission by device 310, the controller / processor 359 may provide RRC layer functions associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functions related to header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with transmission 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 functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0050] Channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the device 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes 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 respective spatial stream for transmission.

[0051] 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 respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to a RX processor 370.

[0052] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. The controller / processor 375 provides demultiplexing, packet reassembly, decryption, header decompression, control signal processing between transport and logical channels. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0053] At least one of the TX processor 368, RX processor 356, or controller / processor 359 of device 350 or the TX 316, RX processor 370, or controller / processor 375 of device 310 may be configured to perform a combined Figure 1 Duration component 198 and / or Figure 1 Aspects of the first SLSS component 199 are described.

[0054] Figure 4 An example 400 of wireless communication between devices based on V2X / V2V / D2D communication is shown. The communication may be based on a combination of Figure 2 The time slot structure of the described aspects. For example, UE 402 can send a transmission 414, for example, including a control channel and / or a corresponding data channel, which can be received by UE 404, 406, 408. The control channel may include information for decoding the data channel and the information may also be used by the receiving device to avoid interference by suppressing transmission on occupied resources during data transmission. The number of TTIs and the RBs to be occupied by the data transmission can be indicated in a control message from the transmitting device. In addition to operating as a receiving device, each of UE 402, 404, 406, 408 may be capable of operating as a transmitting device. Therefore, UE 406, 408 is shown as sending transmissions 416, 420. Transmissions 414, 416, 420 can be broadcast or multicast to nearby devices. For example, UE 402 can send a communication 414 intended to be received by other UEs within range 401 of UE 402. Additionally / alternatively, the RSU 407 may receive communications from and / or send communications to the UEs 402 , 404 , 406 , 408 .

[0055] Similar to combining Figure 1 198, UE 402, 404, 406, 408 or RSU 407 may include a duration component. Sidelink synchronization helps provide a timing reference for sidelink communications, including the transmission of sidelink messages and / or the reception of sidelink messages. A sidelink synchronization signal (SLSS) is used for synchronization in time and frequency. SLSS may include S-PSS, S-SSS or PSBCH.

[0056] The UE may be configured to act as a source of SLSS. The UE may be instructed by the network to send SLSS, the UE may decide to send SLSS when covered by the cell, or the UE may send SLSS when out of cell coverage. The UE may be configured to send SLSS using beamforming, which may allow the sending UE to consider distance coverage, but at the expense of angle coverage. The base station may sweep different beam directions to obtain full-angle coverage of a sector or cell. The UE may find an SS-SSB beam from the base station, for example, with a threshold strength. The UE may send a random access message, such as a physical random access channel (PRACH), on a resource associated with the S-SSB beam. The UE may use the same receive beam to average a given S-SSB across multiple SS periods, for example, in order to select a beam for random access. Subsequent communications may be sent on the selected S-SSB beam, for example, until further beam refinement is configured for the UE. Based on CSI-RS configuration, etc., refinement may occur during the random access process after the UE is in RRC connected mode. However, the transmitting device and / or the receiving device may be mobile and may change position relative to each other. Thus, for example, the receive beam may change for the same transmit beam due to changes in the position and / or orientation of the transmitting UE.Aspects presented herein enable the transmitting UE to determine a variable duration for transmitting the SLSS in order to reduce beam shape sensitivity due to the orientation of the transmitting UE.

[0057] Figure 5 An example communication flow 500 between a device 502 (e.g., a UE) and a device 504 (e.g., a UE) is shown. The communication may be based on V2X, V2V, or D2D based communication directly from a transmitting device to a receiving device. Communications sent from devices 502, 504 may be broadcast and received by multiple receiving devices within range of a particular transmitting device, such as in conjunction with Figure 4 As described.

[0058] At 506, the transmitting device 502 may be configured to determine a variable duration for SLSS. The device 502 may use a first duration for SLSS on a first channel and a second duration for SLSS on a second channel. The first duration or the second duration may include a variable duration. In some aspects, the first duration of the first channel may be different from the second duration of the second channel. For example, the first duration of the first channel may be longer than the second duration of the second channel. The first duration being longer than the second duration may allow the first channel to be transmitted using a wider beam, which may help reduce the sensitivity of the transmit beam based on the orientation of the transmitting device 502. For example, an omnidirectional beam may have the lowest sensitivity to the orientation of the transmitting device 502. The use of a wider beam by the transmitter may help the receiving UE perform receive beam training even if the transmitting UE changes orientation. Within a single SS burst / period, a single long duration wide beam may provide an effect similar to scanning multiple short duration narrow beams. Looking at the burst, a wider beam may have an advantage over the scanning of a narrow beam. The present disclosure is not intended to be limited to the first duration or the second duration. In some aspects, the transmitting device 502 can be configured to utilize multiple durations, such that the multiple durations can include a variable duration. Additionally, a longer first duration can allow the transmitting device to improve its range coverage.

[0059] The robustness provided by the wider beam is acceptable or preferred for initial acquisition, for example, where the mobility state may be unknown. However, after initial acquisition, training to refine the beam may be helpful. For example, it may be helpful to obtain beamforming gain and / or avoid time domain overhead. Therefore, a second S-SSB with different parameters can be sent. One of the parameters may be a duration different from the first S-SSB. Therefore, a mixture of S-SSBs can be sent. A second duration shorter than the first duration may allow the second channel to be transmitted using a narrower beam, which may allow further refinement of the transmission of the SLSS. For example, refinement may occur during a random access channel (RACH) process, or after the transmitting device 502 is connected by RRC, or through CSI-RS configuration. In some aspects, a first SLSS for a first channel may be based on a synchronization raster, and a second SLSS for a second channel may be at an offset relative to the synchronization raster. In some aspects, the first or second SLSS may be based on different offsets not defined by the synchronization raster. In some aspects, the first and / or second SLSS can be based on a synchronized raster, or certain durations can deviate from the raster at specific offsets.

[0060] In some aspects, a cross-S-SSB QCL relationship may be indicated for a first S-SSB and a second S-SSB. For example, an S-SSB repetition may be indicated. The indicated relationship between S-SSBs may be used to increase the coverage of some S-SSBs (e.g., for use as a positioning reference signal (PRS)). For example, the indication may be applied after initial acquisition.

[0061] Each S-SSB channel transmitted by the UE may have multiple S-SSB beams, and the S-SSB channels on different S-SSB beams may have the same duration. Different S-SSB channels may have different durations. Repetition of symbols of the S-SSB and / or lower SCS may be used to increase the duration of the S-SSB. The repetition level may be different for different signals of the S-SSB. For example, the repetition level may be different for the S-PSS, S-SSS, and / or PSBCH within a single S-SSB. The repetition level of different signals of the S-SSB may be the same across multiple S-SSB opportunities in the S-SSB channel. In some examples, the repetition level of different signals of the S-SSB may be the same at each S-SSB opportunity in the S-SSB channel.

[0062] At 508, the transmitting device 502 may be configured to determine a variable parameter for the SLSS. For example, in some aspects, the transmitting device 502 may determine a variable subcarrier spacing (SCS) for the SLSS. In some aspects, the SLSS may be transmitted based on the determined variable SCS. In some aspects, the transmitting device 502 may transmit a first SLSS using a first SCS and may transmit a second SLSS using a second SCS. The first SCS may be smaller than the second SCS. The transmitting device 502 may use a first duration of the first SLSS that is longer than the second duration. The first SCS being smaller than the second SCS allows the first channel to achieve a longer duration.

[0063] In some aspects, the transmitting device 502 may be configured to determine a variable beam width for the SLSS. The SLSS may be transmitted using the determined beam width. The UE may transmit a longer duration SLSS using a wider beam than a shorter duration SLSS. In some aspects, an omnidirectional beam may be used to transmit a SLSS having a longer duration. A wider beam width may allow for improved distance coverage. A wider beam width may also reduce the transmit beam sensitivity of the orientation of the transmitting device 502. For example, even if the transmitting device 502 changes its orientation, the receiving device 504 may be able to better train its receive beam if it is stationary. In addition, even if the transmitting device 502 changes its orientation, the receiving device 504 may be able to average across multiple SLSS periods.

[0064] In some aspects, the transmitting device 502 may be configured to determine additional variable parameters for SLSS. In some aspects, the variable parameter may be at least one of the periodicity, frequency position, frequency hopping pattern, or time domain position of the PBCH payload position within a frame or S-SSB. Different S-SSB channels may have different periodicities, frequency positions, frequency hopping patterns, PBCH payloads, time domain positions with frames or S-SSB periods, etc. In some aspects, the first and / or second channels may include at least one of the additional variable parameters. In some aspects, SLSS with a short duration may not include a PBCH payload, while SLSS with a longer duration may include a PBCH payload indicating the presence or configuration of a shorter SLSS. This may allow different combinations of time division multiplexing (TDM) or frequency division multiplexing (FDM) of S-SSBs with different durations. In addition, such aspects may achieve a trade-off between beam robustness and time domain overhead. In some other aspects, the PSBCH payload of a shorter S-SSB may indicate the presence or configuration of a longer S-SSB. Furthermore, in some aspects, an S-SSB channel having one periodicity may indicate the presence or configure parameters for another S-SSB channel having another periodicity.

[0065] At 510, the transmitting device 502 may be configured to apply collision rules. In some aspects, the transmitting device 502 may apply the collision rules based on a variable duration determined by the transmitting device 502 for the SLSS. For example, the collision rules may prioritize S-SSB over other channels and may only apply to certain durations of the S-SSB.

[0066] At 512, the transmitting device 502 may be configured to FDM the SLSS using the at least one other channel. In some aspects, the transmitting device 502 may FDM the SLSS using the at least one other channel based on a variable duration determined by the transmitting device 502 for the SLSS.

[0067] At 514, the transmitting device 502 may be configured to transmit the SLSS using a variable duration determined by the transmitting device 502. In some aspects, the transmitting device 502 may transmit the SLSS using multiple beams. In some aspects, the SLSS may be transmitted using the same duration on each of the multiple beams of the corresponding channel. In some aspects, the transmitting device 502 may transmit repetitions when transmitting the SLSS using a first duration that is longer than a second duration. The SLSS may include an S-PSS, an S-SSS, and a PSBCH. The transmitting device 502 may use different repetition levels for at least one of the S-PSS, the S-SSS, or the PSBCH.

[0068] At 516, the receiving device 504 may be configured to search for a first SLSS. In some aspects, the receiving device 504 may search for the first SLSS based on a first duration for initial acquisition. The first SLSS may include an S-PSS, an S-SSS, and a PSBCH. The first SLSS may be based on different repetition levels of at least one of the S-PSS, S-SSS, or PSBCH. The receiving device 504 may be configured to average across multiple S-SSB periods when searching for the first SLSS. In some aspects, the first duration of the first SLSS may be long so that the receiving device 504 can train its receive beam even if the transmitting device 502 changes its orientation.

[0069] At 518, the receiving device 504 may be configured to search for a second SLSS. In some aspects, the receiving device 504 may search for the second SLSS based on a second duration for refinement. For example, after the receiving device 504 has acquired the first SLSS, the receiving device 504 may train the beam based on a second SLSS having a shorter duration in order to obtain beamforming gain and avoid any time domain overhead. The different durations between the first and second SLSS allow beamforming gain to be obtained while reducing time domain overhead. In some aspects, beam refinement may occur during the RACH process, after the receiving device 504 is in an RRC connected state, or through CSI-RS configuration. In some aspects, the first duration may be longer than the second duration. In some aspects, the first SLSS may include more symbol repetitions than the second SLSS. The first SLSS may have a lower SCS than the second SLSS.

[0070] In some aspects, the first SLSS and the second SLSS can be based on at least one different parameter. For example, the at least one different parameter can include periodicity, frequency position, frequency hopping pattern, or time domain position of a PBCH payload position within a frame or within an S-SSB. In some aspects, one of the first SLSS and the second SLSS can be based on a synchronization raster, wherein the other of the first SLSS and the second SLSS can be at an offset relative to the synchronization raster.

[0071] In some aspects, the first SLSS and the second SLSS may be associated with different RACH resources. In some aspects, the RACH resources associated with the first SLSS and the second SLSS may have different configurations. In some aspects, the PRACH associated with the first SLSS and the second SLSS may have different formats. For example, a longer SLSS may be associated with a longer RACH symbol or a longer PRACH format.

[0072] Figure 6600 is a flow chart of a wireless communication method. The method may be performed by a UE or a component of a UE (e.g., UE 104, 350, 402, 404, 406, 408, 502, 504, 750, 1050; device 702 / 702'; processing system 814, which may include memory 360 and may be the entire UE 350 or a component of UE 350, such as TX processor 368, RX processor 356 and / or controller / processor 359). According to various aspects, one or more of the operations shown in method 600 may be omitted, swapped and / or performed simultaneously. A UE may implement the method of Figure 500. Optional aspects are shown in dashed lines. The method may improve synchronization between UEs for sidelink communication.

[0073] At 602, the UE may determine a variable duration for the SLSS. For example, 602 may be performed by a duration component 706 of the apparatus 702. In some aspects, the UE may use a first duration for a SLSS on a first channel and a second duration for a SLSS on a second channel. The first duration or the second duration may include a variable duration. In some aspects, the first duration of the first channel may be different from the second duration of the second channel. In some aspects, the first SLSS for the first channel may be based on a synchronization raster, and the second SLSS for the second channel may be at an offset from the synchronization raster.

[0074] At 604, the UE may determine a variable SCS for the SLSS. For example, 604 may be performed by the SCS component 708 of the apparatus 702. In some aspects, the SLSS may be sent based on the determined variable SCS. In some aspects, the UE may send a first SLSS using a first SCS and may send a second SLSS using a second SCS. The first SCS may be smaller than the second SCS. The UE may use a first duration of the first SLSS that is longer than the second duration.

[0075] At 606, the UE may determine a variable beamwidth for the SLSS. For example, 606 may be performed by the beamwidth component 710 of the apparatus 702. In some aspects, the SLSS may be transmitted using the determined beamwidth. The UE may transmit the SLSS of longer duration using a wider beam than the SLSS of shorter duration. In some aspects, the SLSS of longer duration may be transmitted using an omni-directional beam.

[0076] At 608, the UE may determine additional variable parameters for the SLSS. For example, 608 may be performed by parameter component 712 of apparatus 702. In some aspects, the additional variable parameters may include at least one of a periodicity, a frequency position, a frequency hopping pattern, or a time domain position of a PBCH payload within a frame or within an S-SSB. In some aspects, the first and / or second channel may include at least one of the additional variable parameters.

[0077] At 610, the UE may apply conflict rules. For example, 610 may be performed by conflict rules component 714 of apparatus 702. In some aspects, the UE may apply conflict rules based on a variable duration determined by the UE for the SLSS.

[0078] At 612, the UE may frequency division multiplex (FDM) the SLSS using at least one other channel. For example, 612 may be performed by the FDM component 716 of the apparatus 702. In some aspects, the UE may FDM the SLSS using at least one other channel based on a variable duration determined by the UE for the SLSS.

[0079] At 614, the UE may send the SLSS using a variable duration determined by the UE. For example, 614 may be performed by the SLSS component 718 of the device 702. In some aspects, the UE may send the SLSS using multiple beams. In some aspects, the SLSS may be sent using the same duration in each of the multiple beams of the corresponding channel. In some aspects, when the SLSS is sent using a first duration that is longer than a second duration, the UE may send repetitions. The SLSS may include an S-PSS, an S-SSS, and a PSBCH. The UE may use different repetition levels for at least one of the S-PSS, the S-SSS, or the PSBCH.

[0080] Figure 7 700 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example apparatus 702. The apparatus may be a UE or a component of a UE. The apparatus may perform the method of flowchart 600. The apparatus includes a receiving component 704 that may be configured to receive various types of signals / messages and / or other information from other devices including, for example, a UE 750. The apparatus includes a duration component 706 that may be configured to determine a variable duration for a SLSS, for example, as in conjunction with Figure 6 The apparatus includes an SCS component 708 that can be configured to determine a variable SCS for the SLSS, for example, as described in conjunction with Figure 6 The apparatus includes a beam width component 710 that can be configured to determine a variable beam width for the SLSS, for example, as described in conjunction with Figure 6The apparatus includes a parameter component 712 that can be configured to determine additional variable parameters for the SLSS, for example, as described in conjunction with Figure 6 The apparatus includes a conflict rule component 714 that can be configured to apply conflict rules, for example, as described in conjunction with Figure 6 The apparatus includes an FDM component 716 that can be configured to perform FDM on the SLSS using at least one other channel, for example, as combined with Figure 6 The apparatus includes a SLSS component 718 that can be configured to send the SLSS using a variable duration determined by the UE, for example, as described in conjunction with Figure 6 The apparatus includes a transmitting component 720 that may be configured to transmit various types of signals / messages and / or other information to other devices including, for example, a UE 750.

[0081] The device may include performing the above Figure 6 The flowchart of each block of the algorithm is an additional component. Therefore, Figure 6 Each block in the aforementioned flow chart may be performed by a component, and the apparatus may include one or more of these components. The component may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for processor implementation, or some combination thereof.

[0082] Figure 8 800 is a diagram illustrating an example of a hardware implementation of an apparatus 702′ employing a processing system 814. The processing system 814 may be implemented with a bus architecture, generally represented by a bus 824. The bus 824 may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system 814. The bus 824 links together various circuits, including one or more processors and / or hardware components, represented by the processor 804, components 704, 706, 708, 710, 712, 714, 716, 718, 720, and computer readable medium / memory 806. The bus 824 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0083] The processing system 814 can be coupled to the transceiver 810. The transceiver 810 is coupled to one or more antennas 820. The transceiver 810 provides components for communicating with various other devices through a transmission medium. The transceiver 810 receives signals from the one or more antennas 820, extracts information from the received signals, and provides the extracted information to the processing system 814, specifically the receiving component 704. In addition, the transceiver 810 receives information from the processing system 814, specifically the transmitting component 720, and based on the received information, generates a signal to be applied to the one or more antennas 820. The processing system 814 includes a processor 804 coupled to a computer-readable medium / memory 806. The processor 804 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 806. The software, when executed by the processor 804, causes the processing system 814 to perform the various functions described above for any specific device. The computer-readable medium / memory 806 can also be used to store data manipulated by the processor 804 when executing the software. The processing system 814 also includes at least one of the components 704, 706, 708, 710, 712, 714, 716, 718, 720. These components may be software components running in the processor 804, resident / stored in the computer-readable medium / memory 806, one or more hardware components coupled to the processor 804, or some combination thereof. The processing system 814 may be a component of the device 310 or the device 350 and may include at least one of the memory 376, 360 and / or the TX processor 316, 368, the RX processor 370, 356, and the controller / processor 375, 359. Alternatively, the processing system 814 may be the entire UE (e.g., see Figure 3 device 310 or 350).

[0084] In one configuration, the apparatus 702 / 702′ for wireless communication includes a component for determining a variable duration for a SLSS. The apparatus includes a component for sending the SLSS using the variable duration determined by the wireless device. The apparatus also includes a component for determining a variable SCS for the SLSS. The SLSS is further transmitted using the determined variable SCS. The device also includes a device for determining a variable beamwidth for the SLSS. The SLSS can be sent using the determined beamwidth. The apparatus also includes a component for determining additional variable parameters for the SLSS. The additional variable parameters may include at least one of a periodicity, a frequency position, a frequency hopping pattern, or a time domain position of a PBCH payload position within a frame or within an S-SSB. The apparatus also includes a component for applying a conflict rule based on a variable duration determined by the wireless device for the SLSS. The apparatus also includes a component for performing FDM on the SLSS using at least one other channel based on the variable duration determined by the wireless device for the SLSS. The aforementioned components may be one or more of the aforementioned components of the apparatus 702 and / or the processing system 814 of the apparatus 702′, configured to perform the functions listed by the aforementioned components. As described above, the processing system 814 may include the TX processors 316, 368, the RX processors 370, 356, and the controller / processors 375, 359. Thus, in one configuration, the above components may be the TX processors 316, 368, the RX processors 370, 356, and the controller / processors 375, 359 configured to perform the functions recited by the above components.

[0085] Fig. 9 900 is a flow chart of a method for wireless communication. The method may be performed by a UE or a component of a UE (e.g., UE 104, 350, 402, 404, 406, 408, 502, 504, 750, 1050; apparatus 1002 / 1002′; processing system 1114, which may include memory 360 and may be the entire UE 350 or a component of UE 350, such as TX processor 368, RX processor 356 and / or controller / processor 359). According to various aspects, one or more of the operations shown in method 900 may be omitted, swapped and / or performed simultaneously. A UE may implement the method of Figure 500. Optional aspects are shown in dashed lines. The method may improve synchronization between UEs for sidelink communication.

[0086] At 902, the UE may search for a first SLSS. For example, 902 may be performed by a first SLSS component 1006 of the apparatus 1002. In some aspects, the UE may search for the first SLSS based on a first duration for initial acquisition. The first SLSS may include an S-PSS, an S-SSS, and a PSBCH. The first SLSS may be based on a different repetition level for at least one of the S-PSS, the S-SSS, or the PSBCH.

[0087] At 904, the UE may search for a second SLSS. For example, 904 may be performed by the second SLSS component 1008 of the device 1002. In some aspects, the UE may search for the second SLSS based on a second duration for refinement. In some aspects, the first duration may be longer than the second duration. In some aspects, the first SLSS may include more symbol repetitions than the second SLSS. The first SLSS may have a lower SCS than the second SLSS. In some aspects, the first SLSS and the second SLSS may be based on at least one different parameter. For example, at least one different parameter may include a periodicity, a frequency position, a frequency hopping pattern, or a time domain position with a PSBCH payload position within a frame or within an S-SSB. In some aspects, one of the first SLSS and the second SLSS may be based on a synchronization raster, wherein the other of the first SLSS and the second SLSS may be at an offset relative to the synchronization raster.

[0088] Fig.10 1000 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example apparatus 1002. The apparatus may be a UE or a component of a UE. The apparatus may perform the method of flowchart 900. The apparatus includes a receiving component 1004, which may be configured to receive various types of signals / messages and / or other information from other devices including, for example, a UE 1050. The apparatus includes a first SLSS component 1006, which may be configured to search for a first SLSS, for example, as described in conjunction with Fig. 9 902 as described. The apparatus includes a second SLSS component 1008, which can be configured to search for a second SLSS, for example, as combined Fig. 9 As described in 904.

[0089] The device may include performing the above Fig. 9 The flowchart of each block of the algorithm is appended. In this way, Fig. 9 Each block in the aforementioned flow chart may be performed by a component, and the apparatus may include one or more of these components. The component may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for processor implementation, or some combination thereof.

[0090] Fig.11 1100 is a diagram illustrating an example of a hardware implementation of an apparatus 1002′ employing a processing system 1114. The processing system 1114 may be implemented with a bus architecture, generally represented by bus 1124. The bus 1124 may include any number of interconnecting buses and bridges depending on the specific application and overall design constraints of the processing system 1114. The bus 1124 links together various circuits including one or more processors and / or hardware components, represented by processor 1104, components 1004, 1006, 1008, 1010, and computer readable medium / memory 1106. The bus 1124 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and will not be described further.

[0091] The processing system 1114 may be coupled to the transceiver 1110. The transceiver 1110 is coupled to one or more antennas 1120. The transceiver 1110 provides components for communicating with various other devices over a transmission medium. The transceiver 1110 receives signals from the one or more antennas 1120, extracts information from the received signals, and provides the extracted information to the processing system 1114, specifically the receiving component 1004. In addition, the transceiver 1110 receives information 1114 from the processing system, specifically the transmitting component 1010, and based on the received information, generates a signal to be applied to the one or more antennas 1120. The processing system 1114 includes a processor 1104 coupled to a computer-readable medium / memory 1106. The processor 1104 is responsible for general processing, including executing software stored on the computer-readable medium / memory 1106. The software, when executed by the processor 1104, causes the processing system 1114 to perform the various functions described above for any particular device. The computer-readable medium / memory 1106 may also be used to store data that is manipulated by the processor 1104 when executing software. The processing system 1114 also includes at least one of the components 1004, 1006, 1008, 1010. These components may be software components running in the processor 1104, resident / stored in the computer-readable medium / memory 1106, one or more hardware components coupled to the processor 1104, or some combination thereof. The processing system 1114 may be a component of the device 310 or device 350 and may include at least one of the memories 376, 360 and / or the TX processors 316, 368, the RX processors 370, 356, and the controllers / processors 375, 359. Alternatively, the processing system 1114 may be the entire UE (e.g., see Figure 3 device 310 or 350).

[0092] In one configuration, the apparatus 1002 / 1002′ for wireless communication includes a component for searching for a first SLSS based on a first duration for initial acquisition. The apparatus includes a component for searching for a second SLSS based on a second duration for refinement, wherein the first duration is longer than the second duration. The aforementioned components may be one or more of the aforementioned components of the apparatus 1002 and / or the processing system 1114 of the apparatus 1002′, which are configured to perform the functions listed in the aforementioned components. As described above, the processing system 1114 may include TX processors 316, 368, RX processors 370, 356, and controllers / processors 375, 359. Therefore, in one configuration, the aforementioned components may be TX processors 316, 368, RX processors 370, 356, and controllers / processors 375, 359 configured to perform the functions listed in the aforementioned components.

[0093] The present disclosure relates to sending SLSS using variable duration. Aspects presented herein provide a solution to the problem of changes in receive beams and transmit beams due to changes in the position and / or orientation of the transmitting UE by utilizing a variable duration for sending SLSS. The UE can be configured to act as a source of SLSS. The UE can be instructed by the network to send SLSS, the UE can decide to send SLSS when it is covered by a cell, or the UE can send SLSS when it is out of cell coverage. The UE can be configured to send SLSS using beamforming, which can allow the sending UE to consider distance coverage, but at the expense of angle coverage. At least one advantage of the present disclosure is that the use of variable repetitions at different durations can make up for the loss of distance coverage from a wider beam.

[0094] With respect to the techniques disclosed herein, in a wireless communication system such as system 100, a wider transmit beam makes the transmit beam shape less sensitive to the orientation of a transmitter such as UE 104 - in the case of an omni-directional beam, mostly insensitive to the orientation of the transmitter. If a receiving device such as another UE 104 is stationary, the receiving device can more easily train its reception on the wider beam from the transmitter.

[0095] The robustness gained from wider transmitter beamwidths comes with a tradeoff - longer transmit durations. In initial acquisition where mobility state is unknown, this tradeoff is acceptable. However, after acquisition, it is advantageous to train one or more refined beams - exploiting beamforming gain and avoiding the time domain overhead associated with wider beams and longer transmission durations. In some scenarios, this suggests a mix of SSBs - some wide and some narrow.

[0096] Cross-SSB QCL relationships may be indicated, effectively indicating SSB repetition as a way to create "longer" but potentially non-contiguous SSBs in time. In this approach, the indication is not limited to the typical DL SSB structure. In some examples of the techniques disclosed herein, separate SSB channels may be used. Each SSB channel may have multiple SSB beams, all of which have the same duration.

[0097] In some examples, different SSB channels may have different durations. In some such examples, the technique may repeat the OFDM signal containing the SSB, or use a lower SCS to achieve a longer duration. The repetition levels of the PSS, SSS, and PBCH within the SSB may be different (but the same across all SSB opportunities in the SSB channel). In addition, different SSB channels may have different periods, frequency positions, frequency hopping patterns, PBCH payloads, and time domain positions with frames or SSB periods. For example, a very short SSB may have no PBCH at all. The PBCH payload of a long SSB may indicate the presence / configuration of a shorter SSB. This approach allows different combinations of TDM and FDM for SSBs of different durations and allows for a trade-off between beam robustness and time domain overhead. In some examples, all channels may be on a synchronized raster, or certain durations may deviate from the raster at a specific offset (effectively defining a new raster for these SSBs).

[0098] For initial acquisition, the receiver may search for SSBs of longer duration. Subsequently, the receiver may refine using SSBs of shorter duration. A RACH resource may be associated with SSBs of multiple channels having SSBs of longer duration associated with RACHs of longer duration. Note that in this context, the RACH resources may reuse procedures similar to the access link RACH procedures for transmission with associated reception of subsequent messages, but the resource structure, waveform, and channelization may be similar to those of the access link ("Uu") RACH resources, or may have alternative designs. Collision rules and FDM processing for SSBs and other channels may be different for different SSB channels and durations. For example, a rule that prioritizes SSBs over other channels may only apply to certain SSB durations.

[0099] In some examples, while the duration may be fixed according to the number of OFDM symbols in one SSB (e.g., 2+2+9 for PSS / SSS / PBCH with normal cyclic prefix, and 2+2+7 in case of extended cyclic prefix, respectively), the number of such SSBs may be different. For example, based on the IE, it may be 1, 2, 4, 8, 16, 32, or 64 in the FR2 120KHz digital parameter set. Other digital parameter sets / FRs may provide a subset of these possibilities, such as: FR1, SCS=15kHz: 1, 2; FR1, SCS=30kHz: 1, 2, 4; FR1, SCS=60kHz: 1, 2, 4, 8; FR2, SCS=60kHz: 1, 2, 4, 8, 16, 32; FR2, SCS=120kHz: 1, 2, 4, 8, 16, 32, 64. Even in a single digital parameter set, there may be multiple SLSS configurations with different numbers of SSBs. Multiple digital numerologies provide another dimension that leads to variable duration SLSS (since the number of symbols may be fixed, but the symbol duration itself depends on the digital numerology set). Further examples include different SSB durations corresponding to different beam shapes, and the idea of ​​cross-SSB QCL for sidelink.

[0100] It should be understood that the specific order or hierarchy of blocks in the disclosed process / flowchart is an illustration of an example method. Based on design preferences, it is understood that the specific order or hierarchy of blocks in the process / flowchart can be rearranged. In addition, some blocks can be combined or omitted. The attached method claims present the elements of various blocks in a sample order and are not meant to be limited to the specific order or hierarchy presented.

[0101] The previous 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 are intended to conform to the full scope consistent with the language claims, wherein unless specifically so stated, the elements mentioned in the singular are not intended to represent "one and only one", but "one or more". The word "exemplary" used herein is used to represent "as an example, instance or illustration". Any aspect described as "exemplary" herein does not have to be interpreted as preferred or superior to other aspects. Unless otherwise expressly stated, the term "some" refers to one or more. 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" includes any combination of A, B and / or C, and may include multiples of A, multiples of B or multiples of 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," "at least one of A, B, or 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, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described in the present disclosure that are known or later become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered 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. cannot replace the word "component." Therefore, any claim element shall not be interpreted as a part plus function unless the element is expressly referenced using the phrase "component for..."

Claims

1. A method for wireless communication at a wireless device, comprising: determining a variable duration and a variable beamwidth for a sidelink synchronization signal SLSS, wherein the determined variable beamwidth is related to the determined variable duration such that a longer duration is associated with a wider beam; and The SLSS is transmitted using the variable duration and the variable beamwidth determined by the wireless device.

2. The method according to claim 1, wherein: The wireless device uses a first duration for the SLSS on a first channel and a second duration for the SLSS on a second channel, wherein the first duration or the second duration includes the variable duration.

3. The method according to claim 2, wherein: The first duration of the first channel is different from the second duration of the second channel.

4. The method according to claim 2, wherein: The wireless device transmits the SLSS using a plurality of beams, and wherein the SLSS is transmitted using a same duration on each of the plurality of beams for a corresponding channel.

5. The method according to claim 1, wherein: The wireless device sends a repetition of a symbol when sending the SLSS using a first duration that is longer than a second duration.

6. The method according to claim 5, wherein: The SLSS includes a sidelink primary synchronization signal S-PSS, a sidelink secondary synchronization signal S-SSS and a physical sidelink broadcast channel PSBCH, and wherein the wireless device uses different repetition levels for at least one of the S-PSS, the S-SSS or the PSBCH.

7. The method according to claim 1, further comprising: A variable subcarrier spacing SCS for the SLSS is determined, wherein the SLSS is further transmitted using the determined variable SCS.

8. The method according to claim 7, wherein: The wireless device sends a first SLSS using a first subcarrier spacing SCS and sends a second SLSS using a second SCS, wherein the first SCS is smaller than the second SCS, and wherein the wireless device uses a first duration of the first SLSS that is longer than a second duration.

9. The method according to claim 1, wherein: Longer duration SLSS are transmitted using omnidirectional beams.

10. The method according to claim 1, further comprising determining additional variable parameters for the SLSS, wherein the additional variable parameters include at least one of the following: Periodicity, Frequency position, frequency hopping mode, and The time domain position of the physical broadcast channel PBCH payload position within a frame or sidelink synchronization signal block S-SSB.

11. The method of claim 1, wherein a first SLSS for a first channel is based on a synchronization raster, and wherein a second SLSS for a second channel is at an offset relative to the synchronization raster.

12. The method according to claim 1, further comprising: A conflict rule is applied based on the variable duration for the SLSS determined by the wireless device.

13. The method according to claim 1, further comprising: The SLSS is frequency division multiplexed (FDM) using at least one other channel based on the variable duration for the SLSS determined by the wireless device.

14. An apparatus for wireless communication at a wireless device, comprising: means for determining a variable duration and a variable beamwidth for a sidelink synchronization signal SLSS, wherein the determined variable beamwidth is related to the determined variable duration such that a longer duration is associated with a wider beam; as well as Means for transmitting the SLSS using the variable duration and the variable beamwidth determined by the wireless device.

15. The device according to claim 14, wherein: The wireless device uses a first duration for the SLSS on a first channel and a second duration for the SLSS on a second channel, wherein the first duration or the second duration includes the variable duration.

16. The device according to claim 15, wherein: The first duration of the first channel is different from the second duration of the second channel.

17. The device according to claim 15, wherein: The wireless device transmits the SLSS using a plurality of beams, and wherein the SLSS is transmitted using a same duration on each of the plurality of beams for a corresponding channel.

18. The device according to claim 14, wherein: The wireless device sends a repetition of a symbol when sending the SLSS using a first duration that is longer than a second duration.

19. The device according to claim 18, wherein: The SLSS includes a sidelink primary synchronization signal S-PSS, a sidelink secondary synchronization signal S-SSS and a physical sidelink broadcast channel PSBCH, and wherein the wireless device uses different repetition levels for at least one of the S-PSS, the S-SSS or the PSBCH.

20. The apparatus of claim 14, further comprising: A means for determining a variable subcarrier spacing SCS for the SLSS, wherein the SLSS is further transmitted using the determined variable SCS.

21. The device according to claim 20, wherein: The wireless device sends a first SLSS using a first subcarrier spacing SCS and sends a second SLSS using a second SCS, wherein the first SCS is smaller than the second SCS, and wherein the wireless device uses a first duration of the first SLSS that is longer than a second duration.

22. The device according to claim 14, wherein: Longer duration SLSS are transmitted using omnidirectional beams.

23. The device according to claim 14, wherein: The method further includes determining additional variable parameters for the SLSS, wherein the additional variable parameters include at least one of the following: Periodicity, Frequency position, frequency hopping mode, and The time domain position of the physical broadcast channel PBCH payload position within a frame or sidelink synchronization signal block S-SSB.

24. An apparatus for wireless communication at a wireless device, comprising: Memory; as well as at least one processor coupled to the memory and configured to cause the wireless device to: determining a variable duration and a variable beamwidth for a sidelink synchronization signal SLSS, wherein the determined variable beamwidth is related to the determined variable duration such that a longer duration is associated with a wider beam; and The SLSS is transmitted using the variable duration and the variable beamwidth determined by the wireless device.

25. The device according to claim 24, wherein: The wireless device uses a first duration for the SLSS on a first channel and a second duration for the SLSS on a second channel, wherein the first duration or the second duration includes the variable duration.

26. The device according to claim 25, wherein The first duration of the first channel is different from the second duration of the second channel.

27. The device according to claim 25, wherein: The wireless device transmits the SLSS using a plurality of beams, and wherein the SLSS is transmitted using a same duration on each of the plurality of beams for a corresponding channel.

28. The device according to claim 24, wherein: The wireless device sends a repetition of a symbol when sending the SLSS using a first duration that is longer than a second duration.

29. The device according to claim 28, wherein The SLSS includes a sidelink primary synchronization signal S-PSS, a sidelink secondary synchronization signal S-SSS and a physical sidelink broadcast channel PSBCH, and wherein the wireless device uses different repetition levels for at least one of the S-PSS, the S-SSS or the PSBCH.

30. The device according to claim 24, wherein: The at least one processor is further configured to: A variable subcarrier spacing SCS for the SLSS is determined, wherein the SLSS is further transmitted using the determined variable SCS.

31. The device according to claim 30, wherein The wireless device sends a first SLSS using a first subcarrier spacing SCS and sends a second SLSS using a second SCS, wherein the first SCS is smaller than the second SCS, and wherein the wireless device uses a first duration of the first SLSS that is longer than a second duration.

32. The apparatus of claim 24, wherein: Longer duration SLSS are transmitted using omnidirectional beams.

33. The apparatus of claim 24, further comprising determining additional variable parameters for the SLSS, wherein the additional variable parameters include at least one of: Periodicity, Frequency position, frequency hopping mode, and The time domain position of the physical broadcast channel PBCH payload position within a frame or sidelink synchronization signal block S-SSB.

34. A computer readable medium storing computer executable code for wireless communication at a wireless device, the code when executed by a processor causing the wireless device to: Determining a variable duration and a variable beamwidth for a side link synchronization signal SLSS, wherein The determined variable beam width is related to the determined variable duration such that a longer duration is associated with a wider beam; and The SLSS is transmitted using the variable duration and the variable beamwidth determined by the wireless device.

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