Synchronization in sidelink operation

Abstract

Aspects of the present disclosure generally relate to wireless communications. In some aspects, a user equipment (UE) may determine, within a set of synchronization resources, synchronization resources for transmitting UE-specific sidelink synchronization signals. The UE may transmit the UE-specific sidelink synchronization signal using the synchronization resources included in the set of synchronization resources. Numerous other aspects are described.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. non-provisional patent application No. 17 / 804,020, filed on May 25, 2022, entitled “SYNCHRONIZATION IN SIDELINK OPERATION,” which is hereby expressly incorporated herein by reference. Technical Field

[0003] Aspects of the present disclosure relate generally to wireless communications, and to techniques and apparatus for synchronization in sidelink operations. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). 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, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0005] A wireless network may include one or more base stations that support communications for a user equipment (UE) or multiple UEs. A UE may communicate with a base station via downlink communications and uplink communications. A "downlink" (or "DL") refers to the communication link from a base station to a UE, and an "uplink" (or "UL") refers to the communication link from a UE to a base station.

[0006] The above-mentioned multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different UEs to communicate at a city, country, region and / or global level. New Radio (NR), which may be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and using orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) (CP-OFDM) on the downlink, using CP-OFDM and / or single carrier frequency division multiplexing (SC-FDM) (also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink to better integrate with other open standards, as well as supporting beamforming, multiple input multiple output (MIMO) antenna technology and carrier aggregation. As the demand for mobile broadband access continues to increase, further improvements in LTE, NR and other radio access technologies remain useful. Summary of the invention

[0007] Some aspects described herein relate to a method of wireless communication performed by a user equipment (UE). The method may include determining a synchronization resource within a synchronization resource set for sending a UE-specific sidelink synchronization signal. The method may include using the synchronization resource included in the synchronization resource set to send the UE-specific sidelink synchronization signal.

[0008] Some aspects described herein relate to a UE for wireless communication. The UE may include a memory and one or more processors, the one or more processors being coupled to the memory. The one or more processors may be configured to determine a synchronization resource for sending a UE-specific sidelink synchronization signal within a synchronization resource set. The one or more processors may be configured to use the synchronization resource included in the synchronization resource set to send the UE-specific sidelink synchronization signal.

[0009] Some aspects described herein relate to a non-transitory computer-readable medium storing an instruction set for wireless communication by a UE. The instruction set, when executed by one or more processors of the UE, may cause the UE to determine a synchronization resource for sending a UE-specific sidelink synchronization signal within a synchronization resource set. The instruction set, when executed by one or more processors of the UE, may cause the UE to use the synchronization resource included in the synchronization resource set to send the UE-specific sidelink synchronization signal.

[0010] Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for determining a synchronization resource within a set of synchronization resources for transmitting a device-specific sidelink synchronization signal. The apparatus may include means for transmitting the device-specific sidelink synchronization signal using the synchronization resource included in the set of synchronization resources.

[0011] The various aspects generally include methods, apparatuses, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices and / or processing systems as fully described herein with reference to the drawings and description and as illustrated in the drawings and description.

[0012] The features and technical advantages of the examples according to the present disclosure have been outlined quite extensively above so that the following specific embodiments may be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples may be easily used as a basis for modifying or designing other structures for achieving the same purpose of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both in terms of their organization and method of operation, and the associated advantages will be better understood by considering the following description in conjunction with the accompanying drawings. Each of the figures in the accompanying drawings is provided for the purpose of illustration and description, and not as a definition of the limitations of the claims.

[0013] Although various aspects are described in the present disclosure by illustrating some examples, it will be understood by those skilled in the art that such aspects can be implemented in many different arrangements and scenarios. The technology described herein can be implemented using different platform types, devices, systems, shapes, sizes and / or packaging arrangements. For example, some aspects can be implemented via integrated chip implementations or other devices based on non-module components (e.g., end-user devices, vehicles, communication equipment, computing equipment, industrial equipment, retail / shopping equipment, medical equipment, and / or artificial intelligence devices). Various aspects can be implemented in chip-level components, modular components, non-modular components, non-chip-level components, device-level components and / or system-level components. The equipment incorporating the various aspects and features described may include additional components and features for implementing and practicing the various aspects claimed and described. For example, the transmission and reception of wireless signals may include one or more components (e.g., hardware components, including antennas, radio frequency (RF) chains, power amplifiers, modulators, buffers, processors, interleavers, adders and / or summers) for analog and digital purposes. The various aspects described herein are intended to be practiced in various devices, components, systems, distributed arrangements, and / or end-user devices of various sizes, shapes and configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to fully understand the above-mentioned features of the present disclosure, a more specific description of the invention briefly summarized above can be obtained by referring to various aspects (some of which are illustrated in the accompanying drawings). However, it should be noted that the accompanying drawings only illustrate certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the specification may admit of other equally effective aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0015] Figure 1 is a diagram illustrating an example of a wireless network according to the present disclosure.

[0016] Figure 2 is a diagram illustrating an example of communication between a base station and a user equipment (UE) in a wireless network according to the present disclosure.

[0017] Figure 3 is a diagram illustrating an example of side link communication according to the present disclosure.

[0018] Figure 4 is a diagram illustrating an example of side link communication and access link communication according to the present disclosure.

[0019] Figure 5 is a diagram illustrating an example of a synchronization signal hierarchical structure according to the present disclosure.

[0020] Figure 6 is a diagram illustrating an example of decoupling synchronization and communication in a sidelink operation according to the present disclosure.

[0021] Figure 7 is a diagram illustrating an example associated with synchronization in a side link operation according to the present disclosure.

[0022] Figure 8 is a diagram illustrating an example process associated with synchronization in sidelink operations according to the present disclosure.

[0023] Fig. 9 is a diagram of an example apparatus for wireless communications according to the present disclosure. DETAILED DESCRIPTION

[0024] The various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be embodied in many different forms, and should not be construed as being limited to any specific structure or function presented throughout the present disclosure. Instead, these aspects are provided so that the present disclosure will be thorough and complete, and the protection scope of the present disclosure will be fully conveyed to those skilled in the art. It should be appreciated by those skilled in the art that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed herein, whether it is implemented independently or in combination with any other aspect of the present disclosure. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods implemented using other structures, functions, or structures and functions in addition to or different from the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the present invention.

[0025] Several aspects of telecommunication systems will now be presented with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a 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.

[0026] Although various aspects may be described herein using terms generally associated with 5G or new radio (NR) radio access technology (RAT), various aspects of the present disclosure may be applied to other RATs, such as 3G RAT, 4G RAT, and / or post-5G RATs (e.g., 6G).

[0027] Figure 11 is a diagram illustrating an example of a wireless network 100 according to the present disclosure. The wireless network 100 may be a 5G (e.g., NR) network and / or a 4G (e.g., Long Term Evolution (LTE)) network, or may include elements of a 5G (e.g., NR) network and / or elements of a 4G (e.g., Long Term Evolution (LTE)) network, among other examples. The wireless network 100 may include one or more base stations 110 (shown as BS110a, BS110b, BS110c, and BS110d), a user equipment (UE) 120 or multiple UEs 120 (shown as UE120a, UE 120b, UE 120c, UE 120d, and UE 120e), and / or other network entities. The base station 110 is an entity that communicates with the UE 120. Base station 110 (sometimes referred to as BS) may include, for example, an NR base station, an LTE base station, a Node B, an eNB (e.g., in 4G), a gNB (e.g., in 5G), an access point, and / or a transmit receive point (TRP). Each base station 110 may provide communication coverage for a particular geographic area. In the Third Generation Partnership Project (3GPP), the term "cell" may refer to a coverage area of ​​a base station 110 and / or a base station subsystem serving the coverage area, depending on the context in which the term is used.

[0028] The base station 110 may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by a UE 120 with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by a UE 120 with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by a UE 120 associated with the femto cell (e.g., a UE 120 in a closed subscriber group (CSG)). A base station 110 for a macro cell may be referred to as a macro base station. A base station 110 for a pico cell may be referred to as a pico base station. A base station 110 for a femto cell may be referred to as a femto base station or a home base station. In Figure 1 In the example shown in , BS 110a may be a macro base station for macro cell 102a, BS 110b may be a pico base station for pico cell 102b, and BS 110c may be a femto base station for femto cell 102c. A base station may support one or more (eg, three) cells.

[0029] In some examples, the cell may not necessarily be fixed, and the geographic area of ​​the cell may move according to the location of the mobile base station 110 (e.g., a mobile base station). In some examples, the base stations 110 can be interconnected with each other and / or to one or more other base stations 110 or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces, such as direct physical connections or virtual networks, using any suitable transport network.

[0030] The wireless network 100 may include one or more relay stations. A relay station is an entity that can receive transmissions of data from an upstream station (e.g., a base station 110 or a UE 120) and transmit the transmissions of data to a downstream station (e.g., a UE 120 or a base station 110). A relay station may be a UE 120 that is capable of relaying transmissions for other UEs 120. Figure 1 In the example shown in , BS 110d (eg, a relay base station) can communicate with BS 110a (eg, a macro base station) and UE 120d to facilitate communication between BS 110a and UE 120d. Base station 110 that relays communication may be referred to as a relay station, relay base station, relay, etc.

[0031] The wireless network 100 may be a heterogeneous network that includes different types of base stations 110, such as macro base stations, pico base stations, femto base stations, relay base stations, etc. These different types of base stations 110 may have different transmit power levels, different coverage areas, and / or different impacts on interference in the wireless network 100. For example, a macro base station may have a high transmit power level (e.g., 5 watts to 40 watts), while a pico base station, a femto base station, and a relay base station may have a lower transmit power level (e.g., 0.1 watt to 2 watts).

[0032] A network controller 130 may be coupled to or in communication with a set of base stations 110 and may provide coordination and control for the base stations 110. The network controller 130 may communicate with the base stations 110 via backhaul communication links. The base stations 110 may communicate directly with each other or indirectly via wireless or wired backhaul communication links.

[0033] UE 120 can be dispersed throughout the wireless network 100, and each UE 120 can be fixed or mobile. UE 120 can include, for example, access terminals, terminals, mobile stations, and / or subscriber units. UE 120 can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device, a biometric device, a wearable device (e.g., a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring or a smart bracelet)), an entertainment device (e.g., a music device, a video device, and / or a satellite radio), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, and / or any other suitable device configured to communicate via a wireless medium.

[0034] Some UEs 120 may be considered as machine type communication (MTC) or evolved or enhanced machine type communication (eMTC) UEs. MTC UEs and / or eMTC UEs may include, for example, robots, drones, remote devices, sensors, meters, monitors, and / or location tags that may communicate with a base station, another device (e.g., a remote device), or some other entity. Some UEs 120 may be considered as Internet of Things (IoT) devices and / or may be implemented as NB-IoT (narrowband IoT) devices. Some UEs 120 may be considered as customer premises equipment. UE 120 may be included in a housing that houses components of UE 120, such as a processor component and / or a memory component. In some examples, the processor component and the memory component may be coupled together. For example, a processor component (e.g., one or more processors) and a memory component (e.g., a memory) may be operationally coupled, communicatively coupled, electronically coupled, and / or electrically coupled.

[0035] In general, any number of wireless networks 100 may be deployed in a given geographic area. Each wireless network 100 may support a specific RAT and may operate on one or more frequencies. RAT may be referred to as a radio technology, an air interface, etc. Frequency may be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0036] In some examples, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more side link channels (e.g., without using base station 110 as an intermediary to communicate with each other). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, or vehicle-to-pedestrian (V2P) protocols), and / or mesh networks. In such examples, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by base station 110.

[0037] The devices of the wireless network 100 may communicate using an electromagnetic spectrum, which may be subdivided into various categories, bands, channels, etc., based on frequency or wavelength. For example, the devices of the wireless network 100 may communicate using one or more operating bands. In 5G NR, two initial operating bands have been identified as frequency ranges designated FR1 (410 MHz–7.125 GHz) and FR2 (24.25 GHz–52.6 GHz). It should be understood that, although a portion of FR1 is greater than 6 GHz, FR1 is often (interchangeably) referred to as the “below 6 GHz” band in various documents and articles. A similar naming issue sometimes occurs with respect to FR2, which is often (interchangeably) referred to as the “millimeter wave” band in documents and articles, although different from the extremely high frequency (EHF) band (30 GHz–300 GHz) identified as the “millimeter wave” band by the International Telecommunication Union (ITU).

[0038] Frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands for these mid-band frequencies as frequency range designation FR3 (7.125GHz–24.25GHz). The bands falling within FR3 can inherit FR1 characteristics and / or FR2 characteristics, so the features of FR1 and / or FR2 can be effectively extended to mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations to more than 52.6GHz. For example, three higher operating bands have been identified as frequency range designations FR4a or FR4-1 (52.6GHz–71GHz), FR4 (52.6GHz–114.25GHz), and FR5 (114.25GHz–300GHz). Each of these higher frequency bands falls within the EHF band.

[0039] Considering the above examples, unless otherwise expressly stated, it should be understood that if the term "below 6 GHz" or the like is used herein, the term can broadly refer to frequencies that can be lower than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise expressly stated, it should be understood that if the term "millimeter wave" or the like is used herein, the term can broadly refer to frequencies that can include mid-band frequencies, can be within FR2, FR4, FR4-a or FR4-1 and / or FR5, or can be within the EHF band. It is contemplated that the frequencies included in these operating bands (e.g., FR1, FR2, FR3, FR4, FR4-a, FR4-1, and / or FR5) can be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0040] In some aspects, the UE 120 may include a communication manager 140. As described in more detail elsewhere herein, the communication manager 140 may determine a synchronization resource within a synchronization resource set for sending a UE-specific sidelink synchronization signal; and use the synchronization resource included in the synchronization resource set to send the UE-specific sidelink synchronization signal. Additionally or alternatively, the communication manager 140 may perform one or more other operations described herein.

[0041] As indicated above, Figure 1 are provided as examples. Other examples can be found in the Figure 1 Different than described.

[0042] Figure 2 2 is a diagram illustrating an example 200 of base station 110 communicating with UE 120 in wireless network 100 according to the present disclosure. Base station 110 may be equipped with a set of antennas 234a to 234t, such as T antennas (T≥1). UE 120 may be equipped with a set of antennas 252a to 252r, such as R antennas (R≥1).

[0043] At the base station 110, the transmit processor 220 may receive data intended for the UE 120 (or a set of UEs 120) from the data source 212. The transmit processor 220 may select one or more modulation and coding schemes (MCS) for the UE 120 based at least in part on one or more channel quality indicators (CQI) received from the UE 120. The base station 110 may process (e.g., encode and modulate) the data for the UE 120 based at least in part on the MCS selected for the UE 120, and may provide data symbols for the UE 120. The transmit processor 220 may process system information (e.g., for semi-static resource partitioning information (SRPI)) and control information (e.g., CQI requests, grants, and / or upper layer signaling), and provide overhead symbols and control symbols. The transmit processor 220 may generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS) or demodulation reference signals (DMRS)) and synchronization signals (e.g., primary synchronization signals (PSS) or secondary synchronization signals (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols, where applicable, and may provide a set of output symbol streams (e.g., T output symbol streams) to a corresponding set of modems 232 (e.g., T modems) (shown as modems 232a to 232t). For example, each output symbol stream may be provided to a modulator component (shown as MOD) of the modem 232. Each modem 232 may process a corresponding output symbol stream (e.g., for OFDM) using a corresponding modulator component to obtain an output sample stream. Each modem 232 may further process (e.g., convert to analog, amplify, filter, and / or up-convert) the output sample stream using a corresponding modulator component to obtain a downlink signal. The modems 232a to 232t may transmit a set of downlink signals (e.g., T downlink signals) via a corresponding set of antennas 234 (e.g., T antennas) (shown as antennas 234a to 234t).

[0044] At the UE 120, a set of antennas 252 (shown as antennas 252a to 252r) may receive downlink signals from the base station 110 and / or other base stations 110, and a set of received signals (e.g., R received signals) may be provided to a set of modems 254 (e.g., R modems) (shown as modems 254a to 254r). For example, each received signal may be provided to a demodulator component (shown as DEMOD) of the modem 254. Each modem 254 may use a corresponding demodulator component to condition (e.g., filter, amplify, downconvert, and / or digitize) the received signal to obtain input samples. Each modem 254 may use a demodulator component to further process the input samples (e.g., for OFDM) to obtain received symbols. A MIMO detector 256 may obtain received symbols from the modem 254, may perform MIMO detection on the received symbols where applicable, and may provide detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, may provide decoded data for the UE 120 to the data sink 260, and may provide decoded control information and system information to the controller / processor 280. The term "controller / processor" may refer to one or more controllers, one or more processors, or a combination thereof. The channel processor may determine a reference signal received power (RSRP) parameter, a received signal strength indicator (RSSI) parameter, a reference signal received quality (RSRQ) parameter, and / or a CQI parameter, among other things. In some examples, one or more components of the UE 120 may be included in the housing 284.

[0045] The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292. The network controller 130 may include, for example, one or more devices in a core network. The network controller 130 may communicate with the base station 110 via the communication unit 294.

[0046] One or more antennas (e.g., antennas 234a to 234t and / or antennas 252a to 252r) may include or be included within one or more antenna panels, one or more antenna groups, one or more sets of antenna elements, and / or one or more antenna arrays, etc. Antenna panels, antenna groups, sets of antenna elements, and / or antenna arrays may include one or more antenna elements (within a single housing or multiple housings), sets of coplanar antenna elements, sets of non-coplanar antenna elements, and / or coupled to one or more transmit and / or receive components (such as, Figure 2 One or more antenna elements of one or more components in.

[0047] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information from the controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, and / or CQI). The transmit processor 264 may generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be pre-decoded by the TX MIMO processor 266, where applicable, further processed by the modem 254 (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to the base station 110. In some examples, the modem 254 of the UE 120 may include a modulator and a demodulator. In some examples, the UE 120 includes a transceiver. The transceiver may include any combination of an antenna 252, a modem 254, a MIMO detector 256, a receive processor 258, a transmit processor 264, and / or a TX MIMO processor 266. The transceiver may be used by a processor (eg, controller / processor 280) and memory 282 to perform the functions described herein (eg, reference Figures 7 to 9 ) or any aspect of any of the methods described herein.

[0048] At the base station 110, uplink signals from the UE 120 and / or other UEs may be received by the antenna 234, processed by the modem 232 (e.g., a demodulator component of the modem 232 shown as DEMOD), detected by the MIMO detector 236 where applicable, and further processed by the receive processor 238 to obtain decoded data and control information transmitted by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239 and the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and may communicate with the network controller 130 via the communication unit 244. The base station 110 may include a scheduler 246 to schedule one or more UEs 120 for downlink and / or uplink communications. In some examples, the modem 232 of the base station 110 may include a modulator and a demodulator. In some examples, the base station 110 includes a transceiver. The transceiver may include any combination of antenna 234, modem 232, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver may be used by a processor (e.g., controller / processor 240) and memory 242 to perform the operations described herein (e.g., reference 2 Figures 7 to 9 ) or any aspect of any of the methods described herein.

[0049] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other components of the base station 110 may perform one or more techniques associated with synchronization in sidelink operations, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other component of the Figure 8 800 and / or operations of other processes as described herein. Memory 242 and memory 282 may store data and program codes for base station 110 and UE 120, respectively. In some examples, memory 242 and / or memory 282 may include a non-transitory computer-readable medium that stores one or more instructions (e.g., code and / or program code) for wireless communication. For example, the one or more instructions, when executed by one or more processors of base station 110 and / or UE 120 (e.g., directly, or after compilation, conversion, and / or interpretation), may cause the one or more processors, UE 120, and / or base station 110 to perform or direct, for example, Figure 8 The process 800 and / or operations of other processes as described herein. In some examples, executing instructions may include running instructions, converting instructions, compiling instructions, and / or interpreting instructions, etc.

[0050] In some aspects, the UE 120 includes a means for determining a synchronization resource within a synchronization resource set for transmitting a UE-specific sidelink synchronization signal; and a means for transmitting the UE-specific sidelink synchronization signal using the synchronization resource included in the synchronization resource set. The means for the UE 120 to perform the operations described herein may include, for example, one or more of the communication manager 140, the antenna 252, the modem 254, the MIMO detector 256, the receive processor 258, the transmit processor 264, the TX MIMO processor 266, the controller / processor 280, or the memory 282.

[0051] Although Figure 2 The blocks in the 2000 and 2010 are illustrated as distinct components, but the functionality described above for these blocks may be implemented in a single hardware, software, or combined component or in various combinations of components. For example, the functionality described for the transmit processor 264, the receive processor 258, and / or the TX MIMO processor 266 may be performed by or under the control of the controller / processor 280.

[0052] As indicated above, Figure 2 are provided as examples. Other examples can be found in the Figure 2 Different than described.

[0053] Figure 3is a diagram illustrating an example 300 of sidelink communications according to the present disclosure.

[0054] like Figure 3 As shown in , the first UE 305-1 can communicate with the second UE 305-2 (and one or more other UEs 305) via one or more side link channels 310. UEs 305-1 and 305-2 can communicate using one or more side link channels 310 for P2P communication, D2D communication, V2X communication (e.g., which may include V2V communication, V2I communication and / or V2P communication) and / or mesh networks. In some aspects, UE 305 (e.g., UE 305-1 and / or UE 305-2) may correspond to one or more other UEs described elsewhere herein, such as UE 120. In some aspects, one or more side link channels 310 may use a PC5 interface and / or may operate in a high frequency band (e.g., a 5.9 GHz band). Additionally or alternatively, UE 305 may use global navigation satellite system (GNSS) timing to synchronize the timing of a transmit time interval (TTI) (e.g., a frame, subframe, time slot, or symbol).

[0055] like Figure 3 As further shown, the one or more sidelink channels 310 may include a physical sidelink control channel (PSCCH) 315, a physical sidelink shared channel (PSSCH) 320, and / or a physical sidelink feedback channel (PSFCH) 325. The PSCCH 315 may be used to communicate control information, similar to a physical downlink control channel (PDCCH) and / or a physical uplink control channel (PUCCH) used for cellular communication with the base station 110 via an access link or access channel. The PSSCH 320 may be used to communicate data, similar to a physical downlink shared channel (PDSCH) and / or a physical uplink shared channel (PUSCH) used for cellular communication with the base station 110 via an access link or access channel. For example, the PSCCH 315 may carry sidelink control information (SCI) 330, which may indicate various control information for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, and / or space resources), wherein a transport block (TB) 335 may be carried on the PSSCH 320. TB 335 may include data. PSFCH 325 may be used to communicate sidelink feedback 340, such as hybrid automatic repeat request (HARQ) feedback (eg, acknowledgement or negative acknowledgement (ACK / NACK) information), transmit power control (TPC), and / or scheduling request (SR).

[0056] Although shown on PSCCH 315, in some aspects, SCI 330 may include multiple communications in different levels, such as a first level SCI (SCI-1) and a second level SCI (SCI-2). SCI-1 may be sent on PSCCH 315. SCI-2 may be sent on PSSCH 320. SCI-1 may include, for example, an indication of one or more resources (e.g., time resources, frequency resources, and / or space resources) on PSSCH 320, information for decoding sidelink communications on PSSCH, a quality of service (QoS) priority value, a resource reservation period, a PSSCH DMRS pattern, an SCI format for SCI-2, a beta offset for SCI-2, a number of PSSCH DMRS ports, and / or an MCS. SCI-2 may include information associated with data transmission on PSSCH 320, such as a HARQ process ID, a new data indicator (NDI), a source identifier, a destination identifier, and / or a channel state information (CSI) report trigger.

[0057] In some aspects, one or more sidelink channels 310 may use a resource pool. For example, a scheduling assignment (e.g., included in SCI 330) may be sent in a subchannel across time using specific resource blocks (RBs). In some aspects, data transmissions associated with a scheduling assignment (e.g., on PSSCH 320) may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and the associated data transmission are not sent on adjacent RBs.

[0058] In some aspects, the UE 305 may operate using a sidelink transmission mode (e.g., Mode 1) where resource selection and / or scheduling is performed by the base station 110. For example, the UE 305 may receive a grant for sidelink channel access and / or scheduling from the base station 110 (e.g., in downlink control information (DCI) or in a radio resource control (RRC) message, such as a grant for configuration). In some aspects, the UE 305 may operate using a sidelink transmission mode (e.g., Mode 2) where resource selection and / or scheduling is performed by the UE 305 (e.g., instead of the base station 110). In some aspects, the UE 305 may perform resource selection and / or scheduling by sensing channel availability for transmission. For example, UE 305 may measure RSSI parameters associated with various side link channels (e.g., sidelink-RSSI (S-RSSI) parameters), may measure RSRP parameters associated with various side link channels (e.g., PSSCH-RSRP parameters), and / or may measure RSRQ parameters associated with various side link channels (e.g., PSSCH-RSRQ parameters), and may select a channel for sending side link communications based at least in part on the measurement results.

[0059] Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling using the SCI 330 received in the PSCCH 315, which may indicate occupied resources and / or channel parameters. Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling by determining a channel busy rate (CBR) associated with each sidelink channel, which may be used for rate control (e.g., by indicating a maximum number of resource blocks that the UE 305 may use for a particular set of subframes).

[0060] In a transmission mode in which resource selection and / or scheduling is performed by the UE 305, the UE 305 may generate a sidelink grant and may transmit the grant in the SCI 330. The sidelink grant may indicate, for example, one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks (e.g., for TB 335) to be used for an upcoming sidelink transmission on the PSSCH 320, one or more subframes to be used for an upcoming sidelink transmission, and / or an MCS to be used for an upcoming sidelink transmission. In some aspects, the UE 305 may generate a sidelink grant that indicates one or more parameters (such as the periodicity of the sidelink transmission) for semi-persistent scheduling (SPS). Additionally or alternatively, the UE 305 may generate a sidelink grant for event-driven scheduling (such as for an on-demand sidelink message).

[0061] As indicated above, Figure 3 are provided as examples. Other examples can be found in the Figure 3 Different than described.

[0062] Figure 4 is a diagram illustrating an example 400 of side link communications and access link communications according to the present disclosure.

[0063] like Figure 4 As shown, the transmitter (Tx) / receiver (Rx) UE 405 and the Rx / Tx UE 410 can communicate with each other via a side link, as described above in conjunction with Figure 3 As further shown, in some sidelink modes, the base station 110 may communicate with the Tx / Rx UE 405 via a first access link. Additionally or alternatively, in some sidelink modes, the base station 110 may communicate with the Rx / Tx UE 410 via a second access link. The Tx / Rx UE 405 and / or the Rx / Tx UE 410 may correspond to one or more UEs described elsewhere herein, such as Figure 1120. Thus, a direct link between UEs 120 (e.g., via a PC5 interface) may be referred to as a side link, and a direct link between base station 110 and UE 120 (e.g., via a Uu interface) may be referred to as an access link. Side link communications may be sent via a side link, and access link communications may be sent via an access link. Access link communications may be downlink communications (from base station 110 to UE 120) or uplink communications (from UE 120 to base station 110).

[0064] As indicated above, Figure 4 are provided as examples. Other examples can be found in the Figure 4 Different than described.

[0065] Figure 5 is a diagram illustrating an example 500 of a synchronization signal (SS) hierarchical structure according to the present disclosure. Figure 5 As shown, the SS hierarchy may include an SS burst set 505, which may include multiple SS bursts 510 (shown as SS burst 0 to SS burst N-1, where N is the maximum number of repetitions of the SS burst 510 that can be sent by the base station). As further shown, each SS burst 510 may include one or more SS blocks (SSBs) 515 (shown as SSB 0 to SSB M-1, where M is the maximum number of SSBs 515 that can be carried by the SS burst 510). In some aspects, different SSBs 515 can be beamformed in different manners (e.g., transmitted using different beams) and can be used for cell search, cell acquisition, beam management, and / or beam selection (e.g., as part of an initial network access process). The SS burst set 505 may be sent by a wireless node (e.g., base station 110) periodically (such as every X milliseconds), such as Figure 5 In some aspects, SS burst set 505 may have a fixed or dynamic length (which may be Figure 5 In some cases, the SS burst set 505 or the SS burst 510 may be referred to as a discovery reference signal (DRS) transmission window or an SSB measurement time configuration (SMTC) window.

[0066] In some aspects, the SSB 515 may include resources that carry a primary synchronization signal (PSS) 520, a secondary synchronization signal (SSS) 525, and / or a physical broadcast channel (PBCH) 530. In some aspects, multiple SSBs 515 are included in an SS burst 510 (e.g., utilizing transmissions on different beams), and the PSS 520, SSS 525, and / or PBCH 530 may be the same across each SSB 515 in an SS burst 510. In some aspects, a single SSB 515 may be included in an SS burst 510. In some aspects, the SSB 515 may be at least four symbols (e.g., OFDM symbols) in length, with each symbol carrying one or more of the following: a PSS 520 (e.g., occupying one symbol), a SSS 525 (e.g., occupying one symbol), and / or a PBCH 530 (e.g., occupying two symbols). In some aspects, the SSB 515 may be referred to as an SS / PBCH block.

[0067] In some aspects, the symbols of SSB 515 are consecutive, such as Figure 5 . In some aspects, the symbols of the SSB 515 are non-contiguous. Similarly, in some aspects, one or more SSBs 515 of the SS burst 510 may be sent in contiguous radio resources (e.g., consecutive symbols) during one or more time slots. Additionally or alternatively, one or more SSBs 515 of the SS burst 510 may be sent in non-contiguous radio resources.

[0068] In some aspects, the SS burst 510 may have a burst periodicity, and the SSB 515 of the SS burst 510 may be sent by a wireless node (e.g., base station 110) according to the burst periodicity. In this case, the SSB 515 may repeat during each SS burst 510. In some aspects, the SS burst set 505 may have a burst set periodicity, whereby the SS bursts 510 in the SS burst set 505 are sent by the wireless node according to a fixed burst set periodicity. In other words, the SS burst 510 may repeat during each SS burst set 505.

[0069] In some aspects, the SSB 515 may include an SSB index, which may correspond to a beam for carrying the SSB 515. The UE 120 may monitor and / or measure the SSB 515 using different receive (Rx) beams during an initial network access procedure and / or a cell search procedure, among other examples. Based at least in part on the monitoring and / or measurement, the UE 120 may indicate one or more SSBs 515 having the best signal parameters (e.g., RSRP parameters) to the base station 110. The base station 110 and the UE 120 may use the indicated one or more SSBs 515 to select one or more beams to be used for communication between the base station 110 and the UE 120 (e.g., for a random access channel (RACH) procedure). Additionally or alternatively, the UE 120 may use the SSB 515 and / or the SSB index to determine a cell timing for a cell (e.g., a serving cell) via which the SSB 515 is received.

[0070] As indicated above, Figure 5 are provided as examples. Other examples can be found in the Figure 5 Different than described.

[0071] Figure 6 is a diagram illustrating an example 600 of decoupled synchronization and communication in sidelink operation according to the present disclosure.

[0072] In a typical cellular network, a UE may achieve time and frequency synchronization on an access link using periodic broadcasts (e.g., periodic SSB transmissions) from a base station. In a similar aspect, in a sidelink operation, one or more synchronization sources may send sidelink synchronization information to establish a reference time, indicate symbol timing, indicate frame timing, and / or otherwise send information to ensure that neighboring UEs participating in sidelink communications have the same timing reference. For example, the sidelink synchronization information may be carried in a sidelink SSB (S-SSB) that occupies one time slot and uses the same parameter set as configured in the sidelink bandwidth portion (e.g., the same parameter set as the PSCCH and / or PSSCH). For example, as shown in reference numeral 610, the S-SSB typically includes eleven (11) RBs within thirteen (13) symbols in a time slot, wherein a physical sidelink broadcast channel (PSBCH) is transmitted in the first symbol (s0) and the sixth to thirteenth symbols (s5 to s12), a sidelink PSS (S-PSS) is transmitted in the second and third symbols (s1 and s2), and a sidelink SSS (S-SSS) is transmitted in the fourth and fifth symbols (s3 and s4). In this case, the S-PSS and S-SSS may occupy 127 subcarriers and use the same sequence as the PSS and SSS used for the access link SSB, and the PSBCH / DMRS may occupy 132 subcarriers. In a sidelink SSB configuration, since the sidelink is configured as a time division duplex (TDD) band, the last (fourteenth) symbol is reserved as a gap symbol or a guard symbol for transmit / receive retuning.

[0073] S-PSS and S-SSS may be collectively referred to as side link synchronization signals (SLSS) for time and frequency synchronization between neighboring UEs. For example, as described herein, neighboring UEs may include UEs that perform side link communication with each other, UEs within a threshold proximity of each other, and / or UEs within a communication range of each other, etc. By detecting the SLSS sent by the synchronization source, the UE can synchronize with the synchronization source and estimate the start and carrier frequency offset of the frame. The UE can use the side link timing reference provided by the synchronization source to perform side link transmission with neighboring UEs using the same timing reference. Therefore, the transmitting UE does not need to also send S-SSB. S-PSS and S-SSS each include a 127-bit sequence. S-PSS is generated from an m-sequence using the same polynomial and initial value as used to generate a maximum length sequence (m-sequence) in the access link PSS. S-SSS is generated from a Gold sequence using the same design (e.g., generating polynomial, initial value, and cyclic offset) as the Gold sequence used to generate the access link SSS. In addition, the PSBCH is sent in the S-SSB along with the SLSS (e.g., S-PSS and S-SSS) to convey synchronization-related information such as a direct frame number (DFN), an indication of slot-level and symbol-level time resources for sidelink transmission, an in-coverage indicator, and / or other suitable information. The S-SSB is periodically sent by the synchronization source every 160 milliseconds (ms), with N repetitions within the 160 ms period, where N is preconfigured according to the subcarrier spacing and / or configured by the base station.

[0074] In existing wireless networks, a challenge that may arise in sidelink operation is that the sidelink synchronization process and the sidelink communication process are decoupled, which is different from access link communication. For example, in access link communication, the UE communicating with the base station on the uplink and downlink is also synchronized to the base station. On the other hand, in sidelink operation, the node (e.g., GNSS transmitter, base station or UE) that acts as a synchronization source and sends SLSS or S-SSB is not necessarily a sidelink transmitter or sidelink receiver for the UE synchronized to the synchronization source, and in some cases, the sidelink communication may not even involve a synchronization source. More specifically, in sidelink operation, synchronization is based on a predefined hierarchical synchronization process, which is defined so that the UE is always synchronized to a synchronization source with a higher priority. For example, reference numeral 620 depicts an example of GNSS-based synchronization that can be used in sidelink operation, which defines a synchronization hierarchy in which the GNSS signal has the highest priority (such as priority P0), whereby the UE synchronizes to the GNSS timing whenever the GNSS signal is available. In the case where GNSS signals are unavailable, UEs search and synchronize to S-SSB based on descending priority, where UEs directly synchronized to GNSS signals have the second highest priority (such as priority P1), UEs indirectly synchronized to GNSS signals have the next highest priority (such as priority P2), base stations have the next highest priority (such as priority P3), UEs directly synchronized to base stations have the next highest priority (such as priority P4), UEs indirectly synchronized to base station signals have the next highest priority (such as priority P5), and the remaining UEs have the lowest priority (such as priority P6). Figure 6 In the example shown, UE1 is directly synchronized to the GNSS signal and therefore has the second highest priority P1, and UE2 and UE3 have a lower priority (such as priority P2) due to being indirectly synchronized to the GNSS signal (e.g., via the S-SSB sent by UE1). Alternatively, in some cases, base station-based synchronization may be used, in which case the respective priorities of the base station and GNSS signal are reversed (e.g., priorities P3 to P5 and priorities P0 to P2 in the GNSS-based hierarchy correspond to priorities P0 to P2 and priorities P3 to P5 in the base station-based hierarchy, respectively).

[0075] In the case where there are multiple nodes acting as synchronization sources, different synchronization sources may send sidelink synchronization signals (e.g., S-SSB, or S-PSS and S-SSS, collectively referred to as SLSS) in a single frequency network (SFN) manner. Specifically, when different nodes are eligible to act as synchronization sources to send SLSS or S-SSB, these different nodes may all use the same time and frequency resources to send the same SLSS or S-SSB, and any UE receiving the SLSS or S-SSB from the sending node may determine the frame and time slot boundaries based on the timing information indicated in the SLSS or S-SSB or otherwise associated with the SLSS or S-SSB. Then, the UE receiving the SLSS or S-SSB may participate in the sidelink communication based on the timing information obtained from the SLSS or S-SSB, although not necessarily with the node sending the SLSS or S-SSB. Therefore, decoupling sidelink synchronization and sidelink communication and sending SLSS or S-SSB in a SFN manner may maintain common timing between UEs communicating with other neighboring UEs on the sidelink, which may be suitable for certain sidelink communication scenarios. For example, decoupling sidelink synchronization and communication and sending SLSS or S-SSB in SFN manner can reduce synchronization overhead and interference in one-to-many sidelink communication scenarios (such as multicast or broadcast) and / or when sidelink operations are performed in a distributed manner (e.g., in Mode 2 sidelink operations, which do not rely on scheduling by a base station). However, in some sidelink scenarios, decoupled synchronization and communication may be suboptimal.

[0076] For example, in Figure 6In the sidelink scenario depicted in , UE1 may be in an open space or other location to detect GNSS signals and thus synchronize directly to the GNSS signals, but UE2 may be in a shielded location or other location where GNSS signals are not available. In this case, UE1 may send SLSS or S-SSB based on the GNSS signals detected at UE1, and UE2 may obtain sidelink synchronization information based on the SLSS or S-SSB sent by UE1. However, as discussed above, UE1 and UE2 do not necessarily participate in each other's sidelink communications because synchronization and communication are decoupled, whereby UE2 may be synchronized to UE1 while participating in sidelink communications with another UE, such as UE4 in the illustrated example. In general, decoupling sidelink synchronization and communication based on hierarchical synchronization priorities may maintain a coarse synchronization state between adjacent UEs, whereby the timing between the transmitter UE and the receiver UE may not be precisely aligned. For example, although the timing between the two UEs may be fully aligned if both UEs are synchronized to GNSS signals, the propagation delay during the sidelink communication between the two UEs may introduce timing errors. Therefore, when sidelink synchronization and communication are decoupled, the timing of sidelink communications is imperfect, which requires the sidelink UE to run a per-slot time and frequency loop (e.g., each UE must estimate the timing error and frequency error in each slot to optimize reception performance).

[0077] In certain sidelink scenarios or use cases (such as sidelink relay or UE-scheduled sidelink communications), it is necessary to run a per-slot time and frequency loop to resolve the time and / or frequency errors caused when the sidelink synchronization and communication are decoupled, which may add additional complexity to the UE implementation without any significant benefit. For example, a relay UE may operate in a sidelink relay role to relay downlink and / or uplink communications between a base station and a remote UE that may be in an out-of-coverage scenario (e.g., in Figure 6In such a case, UE2 may receive downlink transmissions from a base station via an access link and relay the downlink transmissions to a remote UE (such as UE4) on a side link, and / or may receive uplink transmissions from a remote UE via a side link and relay the uplink transmissions to the base station via an access link). In such a case, the timing of the relay UE may be more important to the remote UE served by the relay UE, but in a case where sidelink synchronization and communication are decoupled, the remote UE may need to be synchronized to another synchronization source (e.g., the remote UE may need to be synchronized to a GNSS signal (if available), or to another UE that is directly synchronized to a GNSS signal (if the relay UE is indirectly synchronized to a GNSS signal)). In a similar aspect, in a sidelink usage case where a head UE is scheduling sidelink transmissions by other UEs, the timing of the head UE may be more important or relevant to the UEs scheduled by the head UE. In these (and other) sidelink scenarios, the decoupled synchronization and communication may at most provide coarse time and / or frequency synchronization for the sidelink operation, but the receiver UE participating in the sidelink communication must still perform finer real-time (e.g., per-slot) time and frequency synchronization and / or tracking based on sidelink signals sent by a transmitter UE (e.g., a relay UE or a head UE) participating in the sidelink communication with the receiver UE.

[0078] Therefore, some aspects described herein relate to techniques for coupling synchronization and communication in sidelink operations. Specifically, a transmitter UE communicating with one or more receiver UEs on a sidelink may send a UE-specific sidelink synchronization signal that is received and measured only by the intended receiver UE. For example, as described herein, a "UE-specific sidelink synchronization signal" may generally refer to a sidelink synchronization signal (e.g., S-SSB, S-PSS / S-SSS, and / or sidelink-specific reference signal) that carries information that is unique to or otherwise specific to the transmitter UE, a sidelink synchronization signal that is sent using time and / or frequency resources that are unique to or otherwise specific to the transmitter UE, or a sidelink synchronization signal that carries information that is specific to the transmitter UE and is sent using time and / or frequency resources that are specific to the transmitter UE. In this way, the sidelink communication between the transmitter UE and the receiver UE can be synchronized in a manner similar to the access link communication, because the receiver UE is synchronized to the transmitter UE in a manner similar to the synchronization of the served UE to the base station. In this way, coupled sidelink synchronization and communication may be more suitable for sidelink use cases such as UE sidelink relay or UE scheduled sidelink communication, because the UE may be able to run a longer loop in the sidelink communication for time and frequency tracking (e.g., the UE may not need to run a time and frequency tracking loop in every time slot), which may significantly reduce the complexity of UE specific implementation and / or save resources, etc.

[0079] As indicated above, Figure 6are provided as examples. Other examples can be found in the Figure 6 Different than described.

[0080] Figure 7 is a diagram illustrating an example associated with synchronization in a side link operation according to the present disclosure. Figure 7 As shown in , example 700 includes communication between a transmitter UE (shown as Tx UE) and a receiver UE (shown as Rx UE). In some aspects, the Tx UE and the Rx UE may communicate in a wireless network (such as wireless network 100) via a side link. In addition, in some aspects, the Tx UE may communicate with a base station via a wireless access link, which may include an uplink and a downlink (e.g., when acting as a side link relay role and / or communicating via a side link using mode 1 scheduling, where the base station schedules or coordinates the side link communication). Additionally or alternatively, the Tx UE and the Rx UE may communicate in a distributed manner without relying on scheduling or other coordination performed by the base station (e.g., when the Tx UE is using mode 2 scheduling to act as a side link scheduler or head UE role).

[0081] In some aspects, such as Figure 7 As shown, the Tx UE may send a UE-specific sidelink synchronization signal, which includes information for aligning or otherwise synchronizing time and / or frequency. For example, as described herein, the UE-specific sidelink synchronization signal may include an S-SSB, an S-PSS / S-SSS, a sidelink-specific reference signal, and / or another suitable signal carrying time and / or frequency information unique to or otherwise specific to the Tx UE, a sidelink synchronization signal sent using a synchronization resource unique to or otherwise specific to the Tx UE (e.g., a time and / or frequency resource in a synchronization resource set dedicated to the Tx UE and / or a time and / or frequency resource selected from a common synchronization resource set shared among multiple Tx UEs), or a sidelink synchronization signal carrying time and / or frequency information specific to the Tx UE and sent using a synchronization resource specific to the Tx UE. Because the sidelink synchronization signal is UE-specific (e.g., as opposed to legacy S-SSB or SLSS, where multiple nodes can send the same synchronization signal using the same time and frequency resources via SFN), only the intended Rx UE receives and measures the UE-specific sidelink synchronization signal.

[0082] In some aspects, the Tx UE may send UE-specific sidelink synchronization signals in addition to or independently of any legacy S-SSB or legacy SLSS. For example, in the case where the Tx UE may send UE-specific sidelink synchronization signals in addition to the legacy S-SSB or legacy SLSS, a first set or primary set of synchronization resources may be configured for SFN-based transmission of the legacy S-SSB or SLSS, and a second set or secondary set of synchronization resources may be configured and used for UE-specific sidelink synchronization signal transmission by Tx UEs operating in certain sidelink roles (e.g., a Tx UE acting as a relay UE to relay uplink and downlink communications of a remote UE and / or a Tx UE acting as a head UE to schedule sidelink transmissions by one or more scheduled UEs). In such cases, one or more Tx UEs having authority to send UE-specific sidelink synchronization signals may use the secondary set of synchronization resources to send UE-specific sidelink synchronization signals. Alternatively, in some aspects, the transmission of the UE-specific sidelink synchronization signal in the secondary set of synchronization resources may be independent of (e.g., not dependent on or otherwise dependent on) the synchronization signal carried in the legacy S-SSB or the legacy SLSS. For example, in such a case, the Rx UE may obtain time and frequency information directly from the UE-specific synchronization signal transmitted in the secondary set of synchronization resources.

[0083] Thus, as indicated by reference numeral 720, the Tx UE may be configured to determine a synchronization resource for sending a UE-specific side link synchronization signal. For example, as indicated by reference numeral 730, a synchronization resource set (e.g., a dedicated resource pool including a set of time and frequency resources) may be configured or pre-configured for UE-specific side link synchronization signal transmission, and the Tx UE may use the synchronization resources in the (pre-)configured synchronization resource set to send the UE-specific side link synchronization signal. In some aspects, the synchronization resource set for UE-specific side link synchronization signal transmission may be periodic, wherein the period of the synchronization resource set may be equal to the period of the legacy side link synchronization resource (e.g., 160ms), a fraction of the period of the legacy side link synchronization resource (e.g., 40ms or 80ms), or a multiple of the period of the legacy side link synchronization resource (e.g., 320ms or 640ms). In addition, as described above, in addition to or independently of the legacy side link synchronization resource, a synchronization resource set for sending a UE-specific side link synchronization signal may be (pre-)configured. For example, in the case where a set of synchronization resources for sending UE-specific side link synchronization signals is (pre-)configured in addition to the legacy side link synchronization resources, the Rx UE can use the synchronization signal sent in the legacy side link synchronization resources for coarse time and / or frequency synchronization (e.g., the Rx UE can use the legacy synchronization signal to determine frame and time slot boundaries), and the UE-specific side link synchronization signal can be used for finer time and / or frequency loop tracking (e.g., to estimate the timing offset or frequency offset from the Tx UE relative to the frame and time slot boundaries).

[0084] In some aspects, as described herein, a set of synchronization resources used to send UE-specific sidelink synchronization signals may be configured (e.g., configured by a base station) or pre-configured (e.g., defined in a wireless communication standard or otherwise derived independently of a configuration provided by a base station). For example, in some aspects, depending on whether the Tx UE and the Rx UE are participating in sidelink communications based on mode 1 scheduling (e.g., coordinated sidelink operations controlled by a base station) or sidelink communications based on mode 2 scheduling (e.g., distributed sidelink operations independent of a base station), different techniques may be used to configure or otherwise define a set of synchronization resources used to send UE-specific sidelink synchronization signals.

[0085] For example, as shown by reference numeral 740, in the case where the Tx UE and the Rx UE participate in sidelink communication based on mode 1 scheduling, the synchronization resource set may be configured by the base station. In such a case, the base station may send and the Tx UE may receive semi-static or broadcast signaling used to configure the synchronization resource set including the synchronization resource for sending the UE-specific sidelink synchronization signal. For example, in some aspects, the base station may configure the synchronization resource set in radio resource control (RRC) signaling, broadcast signaling, system information block (SIB) and / or other suitable semi-static or broadcast signaling. In some aspects, the base station may then send and the Tx UE may receive dynamic signaling used to allocate the synchronization resource for the Tx UE to send the UE-specific sidelink synchronization signal within the configured synchronization resource set. For example, in some aspects, the dynamic signaling used to allocate the synchronization resource to the Tx UE may include a legacy downlink control information (DCI) format associated with the sidelink scheduling and / or a DCI format associated with allocating the sidelink synchronization resource. Thus, in the mode 1 scheduling configuration, the Tx UE may then use a portion of the synchronization resource set allocated to the Tx UE to send UE-specific sidelink synchronization signals within the configured synchronization resource set. Additionally or alternatively, in some cases, the synchronization resource set may be specific to the Tx UE (e.g., the synchronization resource set configured by the base station includes only UE-specific synchronization resources for a single Tx UE). In such cases, if the synchronization resource set is configured, the Tx UE may always send the UE-specific sidelink synchronization signal in the synchronization resource set, or the base station may send and the Tx UE may receive control signaling (e.g., DCI) used to activate and / or deactivate the sending of the UE-specific sidelink synchronization signal.

[0086] Additionally or alternatively, for sidelink communications based on mode 2 scheduling, the set of synchronization resources used by the Tx UE to send UE-specific sidelink synchronization signals may be preconfigured (e.g., defined in a wireless communication standard) or configured by a base station (e.g., when the Tx UE is in coverage). In such a case, when the Tx UE sends a UE-specific sidelink synchronization signal, the Tx UE may select synchronization resources for UE-specific sidelink synchronization signal transmission. For example, in some aspects, the Tx UE may randomly select synchronization resources for UE-specific sidelink synchronization signal transmission from the (pre)configured set of synchronization resources, or may select synchronization resources for UE-specific sidelink synchronization signal transmission based on one or more UE identifiers (e.g., to increase the probability that different Tx UEs will use different synchronization resources to send different UE-specific sidelink synchronization signals). For example, in the case where the Tx UE selects synchronization resources for UE-specific sidelink synchronization signal transmission based on one or more UE identifiers, the Tx UE may employ a selection algorithm, thereby determining the location of the synchronization resources used by the Tx UE based at least in part on the one or more UE identifiers. For example, the selection algorithm may be based on a periodicity P of a synchronization resource set, where each period of the synchronization resource set includes a total number N of synchronization resources indexed from 0 to N - 1. In this example, the synchronization resource selected for UE-specific sidelink synchronization signaling may have an index mod(UE_ID, N), where mod is a modulo operation and UE_ID is a UE identifier (e.g., a layer 1 or layer 2 source identifier associated with a Tx UE and / or a layer 1 or layer 2 destination identifier associated with a Rx UE).

[0087] In some aspects, as described herein, a UE-specific sidelink synchronization signal may correspond to a legacy sidelink synchronization signal (e.g., a legacy S-SSB or SLSS) sent using UE-specific synchronization resources, a sidelink synchronization signal carrying information specific to the Tx UE and sent using legacy synchronization resources, or a sidelink synchronization signal carrying information specific to the Tx UE and sent using UE-specific synchronization resources. In the case where the UE-specific sidelink synchronization signal carries information specific to the Tx UE, the UE-specific sidelink synchronization signal may be an S-SSB, wherein the sequence identifier associated with the S-PSS and / or S-SSS in the UE-specific S-SSB may be different from the sequence identifier associated with the S-PSS and / or S-SSS in the legacy S-SSB (e.g., one or more sequence identifiers for the S-PSS and / or S-SSS may be allocated for UE-specific sidelink synchronization signal transmission). Additionally or alternatively, the UE-specific S-SSB may include a PSBCH associated with information different from the legacy PSBCH. For example, the PSBCH in the UE-specific S-SSB and the PSBCH in the legacy S-SSB may have different content, different scrambling sequence identifiers and / or other different information. For example, in some aspects, an identifier related to a UE-specific side link operation (e.g., a source identifier, a destination identifier, a group identifier and / or another suitable identifier) ​​may be carried in the payload of the PSBCH in the UE-specific S-SSB and / or used to generate a UE-specific scrambling sequence for the PSBCH in the UE-specific S-SSB. Alternatively, instead of using S-SSB, the UE-specific side link synchronization signal may be configured as a side link reference signal. For example, the side link reference signal used as a UE-specific side link synchronization signal may be a side link tracking reference signal (S-TRS) or another suitable side link reference signal, which may be configured as UE-specific by using a side link source identifier, a side link destination identifier and / or other UE-specific parameters as a seed to generate a sequence (e.g., a Gold sequence) for a side link reference signal.

[0088] In some aspects, when one or more conditions are met, the Tx UE may generally send a UE-specific sidelink synchronization signal. For example, as shown in reference numeral 750, the base station may send and the Tx UE may receive control signaling (e.g., DCI) used to activate or otherwise allow the transmission of a UE-specific sidelink synchronization signal. For example, in some aspects, the base station may allow the Tx UE to transmit a UE-specific sidelink synchronization signal based on the Tx UE operating in a sidelink relay role and / or based on the Tx UE operating in a sidelink scheduler role. For another example, the base station may activate the Tx UE to transmit a UE-specific sidelink synchronization signal based on the Tx UE sending a scheduling request (SR) message, a buffer status report (BSR) message, and / or another suitable message to the base station to indicate that the Tx UE has sidelink data to be transmitted. In this example, based on one or more messages indicating that the Tx UE has sidelink data to be transmitted, the base station may activate the transmission of a UE-specific sidelink synchronization signal to achieve sidelink synchronization and communication for coupling of the Tx UE and the Rx UE intended to receive the sidelink data. In some aspects, where the base station activates UE-specific synchronization signal transmission, the base station may also send control signaling to subsequently deactivate UE-specific sidelink synchronization signal transmission, at which time the Tx UE may stop sending UE-specific sidelink synchronization signals.

[0089] Additionally or alternatively, as indicated by reference numeral 760, the Tx UE may send a UE-specific sidelink synchronization signal based on a request received from the Rx UE or another peer UE (e.g., another UE communicating with the Tx UE on a sidelink). For example, in some aspects, the Rx / peer UE may determine (e.g., based on a reduced signal to interference plus noise ratio (SINR), a reduced CQI, and / or an increased block error rate (BLER), etc.) that the Rx / peer UE needs to perform a time and / or frequency tracking loop update. Thus, in such a case, the Rx / peer UE may send a request to the Tx UE to trigger the Tx UE to perform the sending of a UE-specific sidelink synchronization signal so that the time and / or frequency tracking loop update may be performed based on the UE-specific sidelink synchronization signal sending. Additionally or alternatively, the Tx UE may autonomously determine whether and / or when to send a UE-specific sidelink synchronization signal (e.g., independently of a base station and / or any Rx UE participating in sidelink communications with the Tx UE). For example, in some aspects, the Tx UE may autonomously send a UE-specific sidelink synchronization signal when the Tx UE has sidelink data to send in order to couple sidelink synchronization with subsequent sidelink communications.

[0090] In some aspects, as shown by reference numeral 770, an Rx UE that receives a UE-specific sidelink synchronization signal from a Tx UE may subsequently perform time and / or frequency tracking operations based at least in part on the UE-specific sidelink synchronization signal. For example, in some aspects, the Rx UE may receive a first signal from a third node (e.g., a base station, another base station, and / or another UE, etc.), wherein the Rx UE uses the first signal for coarse time and / or frequency synchronization and uses the UE-specific sidelink synchronization signal received from the Tx UE for finer time and / or frequency tracking. For example, in some aspects, the Rx UE may receive a legacy S-SSB or a legacy SLSS in a legacy S-SSB or SLSS resource, and the legacy S-SSB or SLSS may be used to at least determine frame and slot boundaries. Thus, when the Rx UE receives a UE-specific sidelink synchronization signal from the Tx UE in the synchronization resource used by the Tx UE, the UE-specific sidelink synchronization signal may be used for finer loop updates (e.g., to estimate carrier frequency offset (CFO) and / or slot timing offset (STO)). Additionally or alternatively, the Rx UE may receive an access link synchronization signal (e.g., SSB) from the base station or another base station, and may determine frame and slot boundaries based on the access link synchronization signal (e.g., when legacy S-SSB or legacy SLSS is not allowed or otherwise not transmitted). In either case, the finer time and / or frequency tracking performed by the Rx UE based on the UE-specific sidelink synchronization signal may subsequently be applied to sidelink control channel (e.g., PSCCH) and / or sidelink data channel (e.g., PSSCH) reception (e.g., to receive sidelink control channel and sidelink data channel transmissions from the Tx UE, thereby coupling sidelink synchronization and sidelink communication).

[0091] Alternatively, in some aspects, the Rx UE may perform time and / or frequency tracking loop updates based only on the UE-specific sidelink synchronization signal. For example, in some aspects, when performing sidelink reception of a sidelink signal sent by the Tx UE, the Rx UE may use only the time and / or frequency estimates obtained from the UE-specific sidelink synchronization signal (e.g., the Rx UE may avoid performing time and / or frequency tracking loop updates based on other signals such as DMRS carried in the sidelink data transmission). Alternatively, as another example, the Tx UE may indicate whether and / or when the Rx UE may apply the time and / or frequency estimates obtained from the UE-specific sidelink synchronization signal to the sidelink reception (e.g., when the UE-specific sidelink synchronization signal has a longer period than the legacy S-SSB, the UE-specific sidelink synchronization signal may be suboptimal for receiving the sidelink transmission after a threshold time, and the Tx UE may indicate the threshold time based on the oscillator (e.g., crystal oscillator) capability of the Tx UE). As another example, the Rx UE may determine (e.g., based on the oscillator capabilities of the Rx UE) the duration for which the time and / or frequency estimate from the UE-specific sidelink synchronization signal is valid. Thus, as described herein, the Rx UE may generally apply the time and / or frequency estimate from the UE-specific sidelink synchronization signal sent by the Tx UE to improve the reception performance of the sidelink control and / or data channel transmissions from the Tx UE, thereby coupling the sidelink synchronization and communication. In addition, in the case where the Rx UE receives UE-specific sidelink synchronization signal transmissions from multiple Tx UEs, the Rx UE may operate a time and / or frequency tracking loop based on the respective UE-specific sidelink synchronization signals sent by the multiple Tx UEs, so as to couple the sidelink synchronization and communication in a manner that can improve the reception performance of the sidelink control and / or data channel transmissions from each respective Tx UE.

[0092] As indicated above, Figure 7 are provided as examples. Other examples can be found in the Figure 7 Different than described.

[0093] Figure 8 800 is a diagram illustrating an example process 800 performed, for example, by a UE according to the present disclosure. Example process 800 is an example in which a UE (e.g., UE 120, UE 305, Tx / Rx UE 405, Rx / Tx UE 410, etc.) performs operations associated with synchronization in sidelink operations.

[0094] like Figure 8 As shown, in some aspects, process 800 may include determining a synchronization resource within a set of synchronization resources for transmitting a UE-specific sidelink synchronization signal (block 810). For example, a UE (e.g., using Fig. 9The communication manager 140 and / or resource determination component 908 depicted in FIG. 1 may determine a synchronization resource within a set of synchronization resources for sending a UE-specific sidelink synchronization signal, as described above.

[0095] like Figure 8 As further shown, in some aspects, process 800 may include using the synchronization resource included in the set of synchronization resources to send the UE-specific sidelink synchronization signal (block 820). For example, a UE (e.g., using communication manager 140 and / or Fig. 9 The sending component 904) depicted in the figure can use the synchronization resources included in the synchronization resource set to send the UE-specific sidelink synchronization signal, as described above.

[0096] Process 800 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in conjunction with one or more other processes described elsewhere herein.

[0097] In a first aspect, the synchronization resource used to send the UE-specific sidelink synchronization signal is periodic and has a period based at least in part on a legacy sidelink synchronization resource period.

[0098] In a second aspect, alone or in combination with the first aspect, process 800 includes receiving semi-static signaling or broadcast signaling from a network node to configure the set of synchronization resources including the synchronization resource for sending the UE-specific sidelink synchronization signal.

[0099] In a third aspect, alone or in combination with one or more of the first and second aspects, process 800 includes receiving dynamic signaling from the network node for allocating the synchronization resource within the synchronization resource set for sending the UE-specific sidelink synchronization signal.

[0100] In a fourth aspect, either alone or in combination with one or more of the first to third aspects, process 800 includes receiving control signaling from a network node for activating the sending of a UE-specific side link synchronization signal, wherein the UE-specific side link synchronization signal is sent at least in part based on the control signaling using the synchronization resource included in the synchronization resource set.

[0101] In a fifth aspect, in combination with the fourth aspect, the control signaling used to activate the sending of the UE-specific sidelink synchronization signal is at least partially based on a sidelink role associated with the UE.

[0102] In a sixth aspect, in combination with one or more aspects of the fourth or fifth aspect, process 800 includes sending one or more messages to the network node indicating that the UE has sidelink data to be sent, wherein the control signaling used to activate the sending of a specific sidelink synchronization signal of the UE is at least partially based on the one or more messages.

[0103] In the seventh aspect, alone or in combination with one or more of the first to sixth aspects, process 800 includes receiving control signaling from a network node to deactivate the sending of the UE-specific side link synchronization signal, and stopping sending the UE-specific side link synchronization signal based at least in part on the control signaling.

[0104] In the eighth aspect, alone or in combination with one or more aspects from the first to the seventh aspects, determining the synchronization resource for sending the UE-specific side link synchronization signal includes randomly selecting the synchronization resource for sending the UE-specific side link synchronization signal within the synchronization resource set.

[0105] In the ninth aspect, alone or in combination with one or more aspects from the first to the eighth aspects, determining the synchronization resource for sending the UE-specific side link synchronization signal includes autonomously selecting the synchronization resource for sending the UE-specific side link synchronization signal within the synchronization resource set based at least in part on one or more UE identifiers.

[0106] In the tenth aspect, either alone or in combination with one or more of the first to ninth aspects, the one or more UE identifiers include a source identifier associated with the UE or a destination identifier associated with a receiving UE intended to receive a sidelink synchronization signal specific to the UE.

[0107] In the eleventh aspect, alone or in combination with one or more aspects from the first to the tenth aspect, the UE-specific side link synchronization signal is sent based at least in part on the UE determining that one or more conditions for sending the UE-specific side link synchronization signal are met.

[0108] In the twelfth aspect, either alone or in combination with one or more of the first to eleventh aspects, process 800 includes receiving a request from a peer UE to send a UE-specific side link synchronization signal, wherein the UE-specific side link synchronization signal is sent based at least in part on the request from the peer UE.

[0109] In the thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, the UE-specific sidelink synchronization signal is an S-SSB.

[0110] In a fourteenth aspect, either alone or in combination with one or more of the first to thirteenth aspects, the S-SSB comprises a sequence identifier different from a sequence identifier used in a legacy S-SSB.

[0111] In a fifteenth aspect, either alone or in combination with one or more of the first to fourteenth aspects, the S-SSB comprises a PSBCH different from a legacy PSBCH.

[0112] In a sixteenth aspect, either alone or in combination with one or more of the first to fifteenth aspects, the UE-specific sidelink synchronization signal is a sidelink reference signal.

[0113] In the seventeenth aspect, alone or in combination with one or more of the first to sixteenth aspects, the seed for generating a sequence associated with the sidelink reference signal includes a sidelink source identifier associated with the UE or a sidelink destination identifier associated with the receiving UE.

[0114] although Figure 8 An example block diagram of process 800 is shown, but in some aspects, process 800 may include Figure 8 In some aspects, the process 800 may include additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner than those boxes depicted in the process 800. Additionally or alternatively, two or more boxes in the boxes of process 800 may be performed in parallel. For example, in some aspects, a UE receiving a UE-specific sidelink synchronization signal may communicate on a sidelink according to the UE-specific sidelink synchronization signal. In some cases, a transmitting UE and a UE receiving a UE-specific sidelink synchronization signal may communicate on a sidelink according to the UE-specific sidelink synchronization signal.

[0115] Fig. 9 900 is a diagram of an example apparatus 900 for wireless communication. Apparatus 900 may be a UE, or a UE may include apparatus 900. In some aspects, apparatus 900 includes a receiving component 902 and a transmitting component 904 that may communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, apparatus 900 may communicate with another apparatus 906 (such as a UE, a base station, or another wireless communication device) using receiving component 902 and transmitting component 904. As further shown, apparatus 900 may include a communication manager 140. Communication manager 140 may include resource determination component 908, among other things.

[0116] In some aspects, the apparatus 900 may be configured to perform Figure 7 Additionally or alternatively, the apparatus 900 may be configured to perform one or more processes described herein, such as Figure 8 In some aspects, the apparatus 900 and / or Fig. 9 One or more of the components shown in the figure may include a combination of Figure 2 Additionally or alternatively, Fig. 9 One or more of the components shown in the figure may be combined with Figure 2 Additionally or alternatively, one or more components in the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as an instruction or code that is stored in a non-transitory computer-readable medium and can be executed by a controller or processor to perform the function or operation of the component.

[0117] The receiving component 902 may receive communications from the device 906, such as reference signals, control information, data communications, or combinations thereof. The receiving component 902 may provide the received communications to one or more other components of the device 900. In some aspects, the receiving component 902 may perform signal processing (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, demapping, equalization, interference cancellation, or decoding, etc.) on the received communications and may provide the processed signals to one or more other components of the device 900. In some aspects, the receiving component 902 may include combining Figure 2 One or more antennas, modems, demodulators, MIMO detectors, receive processors, controllers / processors, memories, or combinations thereof of the described UE.

[0118] The transmitting component 904 may transmit communications, such as reference signals, control information, data communications, or combinations thereof, to the device 906. In some aspects, one or more other components of the device 900 may generate communications and may provide the generated communications to the transmitting component 904 for transmission to the device 906. In some aspects, the transmitting component 904 may perform signal processing (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, etc.) on the generated communications and may transmit the processed signals to the device 906. In some aspects, the transmitting component 904 may include combining Figure 2 One or more antennas, modems, modulators, transmit MIMO processors, transmit processors, controllers / processors, memories, or combinations thereof of the described UE. In some aspects, the transmit component 904 can be co-located with the receive component 902 in a transceiver.

[0119] Resource determining component 908 can determine a synchronization resource within the set of synchronization resources for transmitting a UE-specific sidelink synchronization signal. Transmitting component 904 can transmit the UE-specific sidelink synchronization signal using the synchronization resource included in the set of synchronization resources.

[0120] The receiving component 902 may receive, from a network node, semi-static signaling or broadcast signaling for configuring the set of synchronization resources including the synchronization resource for sending the UE-specific sidelink synchronization signal.

[0121] The receiving component 902 can receive dynamic signaling from the network node for allocating the synchronization resource within the synchronization resource set for sending the UE-specific sidelink synchronization signal.

[0122] The receiving component 902 receives control signaling from a network node for activating transmission of the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is transmitted using the synchronization resource included in the synchronization resource set based at least in part on the control signaling.

[0123] The transmitting component 904 may transmit one or more messages to the network node indicating that the UE has sidelink data to transmit, wherein the control signaling used to activate transmission of the UE-specific sidelink synchronization signal is based at least in part on the one or more messages.

[0124] Receiving component 902 can receive control signaling from a network node to deactivate transmission of the UE-specific sidelink synchronization signal. Transmitting component 904 can stop transmitting the UE-specific sidelink synchronization signal based at least in part on the control signaling.

[0125] The resource determining component 908 can randomly select the synchronization resource within the set of synchronization resources for sending the UE-specific sidelink synchronization signal.

[0126] Resource determining component 908 can autonomously select the synchronization resource within the set of synchronization resources for transmitting the UE-specific sidelink synchronization signal based at least in part on one or more UE identifiers.

[0127] Receiving component 902 can receive a request from a peer UE to send the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is sent based at least in part on the request from the peer UE.

[0128] Fig. 9 The number and arrangement of components shown in the figure are provided as examples. In practice, there may be Fig. 9 Additional components, fewer components, different components, or components arranged in a different manner than those shown in FIG. Fig. 9 Two or more components shown in may be implemented in a single component, or Fig. 9 The single component shown in may be implemented as multiple distributed components. Additionally or alternatively, Fig. 9 The assembly of (one or more) components shown in the executable is described as being composed of Fig. 9Another collection of components shown in the figure performs one or more functions.

[0129] The following provides an overview of some aspects of the disclosure:

[0130] Aspect 1: A method of wireless communication performed by a UE, the method comprising: determining a synchronization resource for sending a UE-specific sidelink synchronization signal within a synchronization resource set; and using the synchronization resource included in the synchronization resource set to send the UE-specific sidelink synchronization signal.

[0131] Aspect 2: The method according to aspect 1, wherein the synchronization resource used to send the UE-specific sidelink synchronization signal is periodic and has a period based at least in part on a legacy sidelink synchronization resource period.

[0132] Aspect 3: According to the method described in any one of Aspects 1 to 2, the method further includes: receiving semi-static signaling or broadcast signaling from a network node for configuring the synchronization resource set including the synchronization resource for sending the UE-specific sidelink synchronization signal.

[0133] Aspect 4: According to the method of aspect 3, the method further comprises: receiving dynamic signaling from the network node for allocating the synchronization resource for sending the UE-specific sidelink synchronization signal within the synchronization resource set.

[0134] Aspect 5: According to the method described in any one of Aspects 1 to 4, the method further includes: receiving control signaling from a network node for activating the sending of the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is sent at least in part based on the control signaling using the synchronization resources included in the synchronization resource set.

[0135] Aspect 6: The method according to aspect 5, wherein the control signaling used to activate the transmission of the UE-specific sidelink synchronization signal is based at least in part on a sidelink role associated with the UE.

[0136] Aspect 7: According to the method described in Aspect 5, the method also includes: sending one or more messages to the network node indicating that the UE has sidelink data to be sent, wherein the control signaling used to activate the sending of the UE-specific sidelink synchronization signal is at least partially based on the one or more messages.

[0137] Aspect 8: According to the method described in any one of Aspects 1 to 7, the method also includes: receiving control signaling from a network node to deactivate the sending of the UE-specific side link synchronization signal; and stopping sending the UE-specific side link synchronization signal at least partially based on the control signaling.

[0138] Aspect 9: A method according to any one of Aspects 1 to 2, wherein determining the synchronization resource for sending the UE-specific sidelink synchronization signal includes: randomly selecting the synchronization resource for sending the UE-specific sidelink synchronization signal within the synchronization resource set.

[0139] Aspect 10: A method according to any one of Aspects 1 to 2, wherein determining the synchronization resource for sending the UE-specific side link synchronization signal includes: autonomously selecting the synchronization resource for sending the UE-specific side link synchronization signal within the synchronization resource set based at least in part on one or more UE identifiers.

[0140] Aspect 11: The method according to aspect 10, wherein the one or more UE identifiers include a source identifier associated with the UE or a destination identifier associated with a receiving UE intended to receive the UE-specific sidelink synchronization signal.

[0141] Aspect 12: A method according to any one of Aspects 1 to 4 or 9 to 11, wherein the UE-specific sidelink synchronization signal is sent at least in part based on the UE determining that one or more conditions for sending the UE-specific sidelink synchronization signal are met.

[0142] Aspect 13: According to the method described in any one of Aspects 1 to 4 or 9 to 11, the method further includes: receiving a request from a peer UE to send the UE-specific side link synchronization signal, wherein the UE-specific side link synchronization signal is sent at least in part based on the request from the peer UE.

[0143] Aspect 14: A method according to any one of Aspects 1 to 13, wherein the UE-specific sidelink synchronization signal is an S-SSB.

[0144] Aspect 15: A method according to aspect 14, wherein the S-SSB includes a sequence identifier different from the sequence identifier used in the legacy S-SSB.

[0145] Aspect 16: A method according to any one of aspects 14 to 15, wherein the S-SSB comprises a PSBCH different from a legacy PSBCH.

[0146] Aspect 17: A method according to any one of Aspects 1 to 13, wherein the UE-specific sidelink synchronization signal is a sidelink reference signal.

[0147] Aspect 18: The method according to aspect 17, wherein the seed used to generate the sequence associated with the sidelink reference signal includes a sidelink source identifier associated with the UE or a sidelink destination identifier associated with a receiving UE.

[0148] Aspect 19: An apparatus for performing wireless communications at a device, the apparatus comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform one or more of the methods described in Aspects 1 to 18.

[0149] Aspect 20: A device for wireless communication, the device comprising: a memory; and one or more processors, the one or more processors coupled to the memory, the one or more processors configured to execute the method according to one or more of aspects 1 to 18.

[0150] Aspect 21: An apparatus for wireless communication, the apparatus comprising at least one means for performing the method according to one or more of aspects 1 to 18.

[0151] Aspect 22: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method according to one or more of aspects 1 to 18.

[0152] Aspect 23: A non-transitory computer-readable medium storing an instruction set for wireless communication, the instruction set comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform one or more of the methods described in aspects 1 to 18.

[0153] While the foregoing disclosure provides illustration and description, it is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of these aspects.

[0154] As used herein, the term "component" is intended to be broadly interpreted as hardware, and / or a combination of hardware and software. Whether 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 modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures and / or functions, etc. As used herein, a "processor" is implemented in a combination of hardware and / or hardware and software. It will be clear that the system and / or method described herein can be implemented by a combination of hardware and / or hardware and software in different forms. The actual dedicated control hardware or software code used to implement these systems and / or methods does not limit various aspects. Therefore, there is no reference to a specific software code to describe the operation and behavior of the system and / or method herein, because those skilled in the art will understand that software and hardware can be designed to implement the system and / or method based at least in part on the description herein.

[0155] As used herein, "satisfying a threshold" may refer to a value being greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc., depending on the context.

[0156] Although specific combinations of features are set forth in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. Many of these features can be combined in a manner that is not specifically described in the claims and / or is not disclosed in the specification. The disclosure of various aspects includes each dependent claim combined with each other claim in the claim set. As used herein, the phrase "at least one of" the list of items refers to any combination of these items (which includes a single member). As an example, "at least one of a, b or c" is intended to cover a, b, c, a+b, a+c, b+c and a+b+c, and any combination with multiple identical elements (e.g., a+a, a+a+a, a+a+b, a+a+c, a+b+b, a+c+c, b+b, b+b+b, b+b+c, c+c and c+c+c, or any other ordering of a, b and c).

[0157] Any element, action or instruction used herein should not be interpreted as key or necessary, unless otherwise explicitly stated. In addition, as used herein, the articles "one" and "a kind of" are intended to include one or more items, and can be used interchangeably with "one or more". In addition, as used herein, the article "said" is intended to include one or more items connected to the article "said", and can be used interchangeably with "one or more". In addition, as used herein, the terms "set" and "group" are intended to include one or more items, and can be used interchangeably with "one or more". If only one item is intended to be referred to, the phrase "only one" or similar terms are used. Moreover, as used herein, the terms "have", "have" etc. are intended to be open terms, which do not limit the elements they modify (for example, "elements with" A can also have B). In addition, the phrase "based on" is intended to represent "based at least in part on", unless explicitly stated otherwise. Furthermore, as used herein, the term "or" when used in a series is intended to be open-ended and may be used interchangeably with "and / or" unless explicitly stated otherwise (eg, if used in conjunction with "either" or "only one of").

Claims

1. A method of wireless communication performed by a user equipment (UE), the method comprising: Determining, within the set of synchronization resources, a synchronization resource for sending a UE-specific sidelink synchronization signal; as well as The UE-specific sidelink synchronization signal is sent using the synchronization resources included in the set of synchronization resources.

2. The method of claim 1 , wherein the synchronization resource used to send the UE-specific sidelink synchronization signal is periodic and has a period based at least in part on a legacy sidelink synchronization resource period.

3. The method according to claim 1, further comprising: Semi-static signaling or broadcast signaling is received from a network node to configure the set of synchronization resources including the synchronization resource for sending the UE-specific sidelink synchronization signal.

4. The method according to claim 3, further comprising: Dynamic signaling is received from the network node for allocating the synchronization resources within the set of synchronization resources for sending the UE-specific sidelink synchronization signal.

5. The method according to claim 1, further comprising: Control signaling is received from a network node to activate transmission of the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is transmitted using the synchronization resources included in the set of synchronization resources based at least in part on the control signaling.

6. The method of claim 5, wherein the control signaling used to activate transmission of the UE-specific sidelink synchronization signal is based at least in part on a sidelink role associated with the UE.

7. The method according to claim 5, further comprising: One or more messages are sent to the network node indicating that the UE has sidelink data to send, wherein the control signaling used to activate the sending of the UE-specific sidelink synchronization signal is based at least in part on the one or more messages.

8. The method according to claim 1, further comprising: receiving control signaling from a network node to deactivate sending of the UE-specific sidelink synchronization signal; as well as The sending of the UE-specific sidelink synchronization signal is ceased based at least in part on the control signaling.

9. The method of claim 1 , wherein determining the synchronization resource for sending the UE-specific sidelink synchronization signal comprises: The synchronization resource for sending the UE-specific sidelink synchronization signal is randomly selected within the synchronization resource set.

10. The method of claim 1, wherein determining the synchronization resource for sending the UE-specific sidelink synchronization signal comprises: The synchronization resource for transmitting the UE-specific sidelink synchronization signal is autonomously selected within the set of synchronization resources based at least in part on one or more UE identifiers.

11. The method of claim 10, wherein the one or more UE identifiers include a source identifier associated with the UE or a destination identifier associated with a receiving UE intended to receive the UE-specific sidelink synchronization signal.

12. The method of claim 1, wherein the UE-specific sidelink synchronization signal is sent based at least in part on the UE determining that one or more conditions for sending the UE-specific sidelink synchronization signal are met.

13. The method according to claim 1, further comprising: A request is received from a peer UE to send the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is sent based at least in part on the request from the peer UE.

14. The method of claim 1, wherein the UE-specific sidelink synchronization signal is a sidelink synchronization signal block (S-SSB).

15. The method of claim 14, wherein the S-SSB includes a sequence identifier that is different from a sequence identifier used in a legacy S-SSB.

16. The method of claim 14, wherein the S-SSB comprises a physical sidelink broadcast channel (PSBCH) that is different from a legacy PSBCH.

17. The method of claim 1, wherein the UE-specific sidelink synchronization signal is a sidelink reference signal.

18. The method of claim 17, wherein a seed used to generate a sequence associated with the sidelink reference signal comprises a sidelink source identifier associated with the UE or a sidelink destination identifier associated with a recipient UE.

19. A user equipment (UE) for wireless communication, the user equipment (UE) comprising: Memory; and one or more processors coupled to the memory and configured to: determining, within the set of synchronization resources, a synchronization resource for sending a UE-specific sidelink synchronization signal; and The UE-specific sidelink synchronization signal is sent using the synchronization resources included in the set of synchronization resources.

20. The UE of claim 19, wherein the synchronization resource used to send the UE-specific sidelink synchronization signal is periodic and has a period based at least in part on a legacy sidelink synchronization resource period.

21. The UE of claim 19, wherein the one or more processors are further configured to: receiving, from a network node, semi-static signaling or broadcast signaling for configuring the set of synchronization resources including the synchronization resource for sending the UE-specific sidelink synchronization signal; and Dynamic signaling is received from the network node for allocating the synchronization resources within the set of synchronization resources for sending the UE-specific sidelink synchronization signal.

22. The UE of claim 19, wherein the one or more processors are further configured to: Control signaling is received from a network node to activate transmission of the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is transmitted using the synchronization resources included in the set of synchronization resources based at least in part on the control signaling.

23. The UE of claim 19, wherein the one or more processors are further configured to: receiving control signaling from a network node to deactivate transmission of the UE-specific sidelink synchronization signal; and The sending of the UE-specific sidelink synchronization signal is ceased based at least in part on the control signaling.

24. The UE of claim 19, wherein to determine the synchronization resource for sending the UE-specific sidelink synchronization signal, the one or more processors are configured to: The synchronization resource for sending the UE-specific sidelink synchronization signal is randomly selected within the synchronization resource set.

25. The UE of claim 19, wherein to determine the synchronization resource for sending the UE-specific sidelink synchronization signal, the one or more processors are configured to: The synchronization resource for sending the UE-specific sidelink synchronization signal is autonomously selected within the synchronization resource set based at least in part on one or more UE identifiers, wherein the one or more UE identifiers include a source identifier associated with the UE or a destination identifier associated with a receiving UE intended to receive the UE-specific sidelink synchronization signal.

26. The UE of claim 19, wherein the UE-specific sidelink synchronization signal is sent based at least in part on the UE determining that one or more conditions for sending the UE-specific sidelink synchronization signal are met.

27. The UE of claim 19, wherein the one or more processors are further configured to: A request is received from a peer UE to send the UE-specific sidelink synchronization signal, wherein the UE-specific sidelink synchronization signal is sent based at least in part on the request from the peer UE.

28. The UE of claim 19, wherein the UE-specific sidelink synchronization signal is a sidelink synchronization signal block (S-SSB) or a sidelink reference signal.

29. A non-transitory computer readable medium storing an instruction set for wireless communication, the instruction set comprising: One or more instructions that, when executed by one or more processors of a user equipment (UE), cause the UE to: determining, within the set of synchronization resources, a synchronization resource for sending a UE-specific sidelink synchronization signal; and The UE-specific sidelink synchronization signal is sent using the synchronization resources included in the set of synchronization resources.

30. An apparatus for wireless communication, the apparatus comprising: means for determining a synchronization resource within a set of synchronization resources for transmitting a device-specific sidelink synchronization signal; and Means for sending the device-specific sidelink synchronization signal using the synchronization resource included in the set of synchronization resources.

Images