Optimizing synchronization signals for nr-lte in-band coexistence

Abstract

The invention relates to a method and an apparatus for scheduling synchronization signals for NR-LTE in-band coexistence. The apparatus detects a first sidelink synchronization signal from a first RAT and a second sidelink synchronization signal from a second RAT. The apparatus determines a priority between synchronization sources associated with the first RAT and the second RAT. The apparatus transmits data using a timing based on the determination of the priority between the first RAT and the second RAT. The apparatus determines to transmit a sidelink synchronization signal as the synchronization source in response to detecting the first sidelink synchronization signal from the first RAT. The apparatus determines to transmit at least one of the first sidelink synchronization signal or the second sidelink synchronization signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. patent application serial number 17 / 663,203, filed on May 12, 2022, and entitled “METHOD FOR PRIORITIZATION OF SYNCHRONIZATION SIGNALSFOR NR-LTE IN-BAND COEXISTENCE,” which is expressly incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to communication systems, and more particularly, to configurations for prioritizing synchronization signals for NR-LTE in-band coexistence. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Certain aspects of 5G NR may be based on 4G Long Term Evolution (LTE) standards. It is necessary to further improve 5GNR technology. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive review of all contemplated aspects. This summary is neither intended to identify key or important elements of all aspects, nor to describe the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0007] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be an apparatus at a relay UE. The apparatus may be a processor and / or a modem at a relay UE or the relay UE itself. The apparatus detects a first side link synchronization signal from a first radio access technology (RAT) and a second side link synchronization signal from a second RAT. The apparatus determines a priority between synchronization sources associated with the first RAT and the second RAT. The apparatus sends data using timing based on a determination of a priority between the first RAT and the second RAT.

[0008] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be an apparatus at a target UE. The apparatus may be a processor and / or a modem at the target UE or the target UE itself. The apparatus determines to send a sidelink synchronization signal as a synchronization source. The apparatus selects to send at least one of a first sidelink synchronization signal associated with a first radio access technology (RAT) or a second sidelink synchronization signal associated with a second RAT.

[0009] To achieve the aforementioned and related purposes, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some exemplary features of one or more aspects. However, these features are only indicative of only some of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0011] Figure 2 Example aspects of a sidelink timeslot structure are illustrated.

[0012] Figure 3 is a diagram illustrating an example of a first device and a second device involved in wireless communication based on, for example, a side link.

[0013] Figure 4 Example aspects of sidelink communications between devices according to various aspects presented herein are illustrated.

[0014] Figure 5is a diagram illustrating an example of an NR resource pool frame structure according to various aspects presented herein.

[0015] Fig. 6A is a diagram illustrating an example of an LTE synchronization subframe in accordance with various aspects presented herein.

[0016] Figure 6B is a diagram illustrating an example of an NR synchronization subframe according to various aspects presented herein.

[0017] Figure 7 is a diagram illustrating an example of an NR synchronization subframe according to various aspects presented herein.

[0018] Figure 8 is a call flow diagram of signaling between a first UE and a second UE.

[0019] Fig. 9 is a flow chart of a method of wireless communication.

[0020] Fig.10 is a flow chart of a method of wireless communication.

[0021] Fig.11 are diagrams illustrating examples of hardware implementations for example apparatuses and / or network entities.

[0022] Fig.12 is a call flow diagram of signaling between a first UE and a second UE.

[0023] Fig.13 is a flow chart of a method of wireless communication.

[0024] Fig.14 is a flow chart of a method of wireless communication.

[0025] Fig.15 are diagrams illustrating examples of hardware implementations for example apparatuses and / or network entities. DETAILED DESCRIPTION

[0026] In wireless communications such as sidelink communications, NR V2X and LTE V2X may have to operate in the same channel. Partly due to the lack of wireless spectrum, NR V2X and LTE V2X may have to operate in the same channel. In the absence of a coordination mechanism, NR V2X transmissions may conflict with LTE V2X transmissions because both occupy the same time-frequency resources. The performance of the two systems may be degraded due to the conflict. In some cases, NR V2X may include dual radio equipment.

[0027] The coordination may include a resource pool frame structure so that NR V2X can access the channel in one time slot and LTE V2X can access the channel in another time slot. However, in order to utilize the resource pool frame structure, both technologies and all UEs in the network will have to agree on the resource pool partitioning. However, changes in the LTE procedures / modems may not be available so that changes can occur in a way that the NR device can implicitly make the LTE device aware of the resource pool partitioning.

[0028] Aspects presented herein provide a configuration for prioritizing synchronization signals for NR-LTE in-band coexistence. Aspects presented herein provide a scheme for NR UEs to effectively prioritize synchronization reference and synchronization burst transmissions when both LTE and NR synchronization reference (SyncRef) UEs are in the network. At least one advantage of the present disclosure is that additional priority levels can be distinguished between NR and LTE SyncRef UEs. At least another advantage is that dual devices (e.g., devices that support both NR and LTE) can have rules for prioritizing synchronization signaling based on set priority rules.

[0029] The detailed description set forth below in conjunction with the accompanying drawings is a description of various configurations and does not represent the only configurations with which the concepts described herein can be practiced. In order to provide a thorough understanding of the various concepts, the specific embodiments include specific details. However, these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid blurring these concepts.

[0030] Several aspects of telecommunication systems are presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0031] For example, an element, or any part of an element, or any combination of elements may be implemented as a "processing system", which includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic components, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout the present disclosure. One or more processors in a processing system may execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

[0032] Thus, in one or more example aspects, implementations, and / or use cases, the described functionality may be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality may be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media may be any available media that can be accessed by a computer. For example, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other media that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0033] Although various aspects, specific implementations and / or use cases are described in this application by illustrating some examples, additional or different aspects, specific implementations and / or use cases may be generated in many different arrangements and scenarios. The various aspects, specific implementations and / or use cases described herein may be implemented across many different platform types, devices, systems, shapes, sizes and packaging arrangements. For example, various aspects, specific implementations and / or use cases may be generated via integrated chip specific implementations and other devices based on non-module components (e.g., end-user devices, vehicles, communication equipment, computing equipment, industrial equipment, retail / purchase equipment, medical equipment, devices that enable artificial intelligence (AI), etc.). Although some examples may or may not be specifically for use cases or applications, the examples described may have a wide range of applicability. Various aspects, specific implementations and / or use cases may be implemented from chip-level or modular components to non-modular, non-chip-level specific implementations, and further to the range of aggregated, distributed or original equipment manufacturer (OEM) devices or systems in conjunction with one or more technologies herein. In some practical environments, the equipment combined with the various aspects and features described may also include additional components and features for implementing and practicing the claimed and described aspects. For example, the transmission and reception of wireless signals necessarily include multiple components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.). The various techniques described herein can be practiced in a wide variety of devices of various sizes, shapes, and configurations, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc.

[0034] The deployment of a communication system (such as a 5G NR system) can be arranged in a variety of ways using various components or constituent parts. In a 5G NR system or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element, or a network equipment (such as a base station (BS), or one or more units (or one or more components) that perform base station functionality) can be implemented in an aggregated or decomposed architecture. For example, a BS (such as a Node B (NB), an evolved NB (eNB), an NR BS, a 5G NB, an access point (AP), a transmit receive point (TRP), or a cell, etc.) can be implemented as an aggregated base station (also referred to as an independent BS or a monolithic BS) or a decomposed base station.

[0035] A converged base station may be configured to utilize a radio protocol stack physically or logically integrated within a single RAN node. A decomposed base station may be configured to utilize a protocol stack physically or logically distributed between two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed in one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of a CU, a DU, and a RU may be implemented as a virtual unit, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0036] Base station operation or network design may take into account the aggregated nature of base station functionality. For example, a disaggregated base station may be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (network configuration such as that initiated by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Decomposition may include distributing functionality across two or more units at various physical locations, as well as virtually distributing functionality of at least one unit, which may enable flexibility in network design. Individual units of a disaggregated base station or disaggregated RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0037] Figure 1 1 is a diagram 100 illustrating an example of a wireless communication system and an access network. The illustrated wireless communication system includes a disaggregated base station architecture. The disaggregated base station architecture may include one or more CUs 110 that may communicate directly with a core network 120 via a backhaul link, or indirectly with the core network 120 through one or more disaggregated base station units, such as a near real-time (near RT) RAN intelligent controller (RIC) 125 via an E2 link, or a non-real-time (non-RT) RIC 115 associated with a service management and orchestration (SMO) framework 105, or both. The CU 110 may communicate with one or more DUs 130 via corresponding midhaul links, such as an F1 interface. The DU 130 may communicate with one or more RUs 140 via corresponding fronthaul links. The RU 140 may communicate with corresponding UEs 104 via one or more radio frequency (RF) access links. In some implementations, a UE 104 may be served simultaneously by multiple RUs 140.

[0038] Each of the units (i.e., CU 110, DU 130, RU 140, and near-RT RIC 125, non-RT RIC 115, and SMO framework 105) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of these units or an associated processor or controller that provides instructions to the communication interface of these units may be configured to communicate with one or more of the other units via a transmission medium. For example, these units may include a wired interface configured to receive signals or transmit signals to one or more of the other units via a wired transmission medium. Additionally, these units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) configured to receive signals or transmit signals to one or more of the other units via a wireless transmission medium.

[0039] In some aspects, CU 110 may host one or more higher layer control functions. Such control functions may include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by CU 110. CU 110 may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some specific implementations, CU 110 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). If necessary, CU 110 may be implemented to communicate with DU 130 for network control and signaling.

[0040] DU 130 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 140. In some aspects, DU 130 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation, demodulation, etc.) at least in part according to a functional split (such as a functional split defined by 3GPP). In some aspects, DU 130 may further host one or more low PHY layers. Each layer (or module) may be implemented using an interface that is configured to communicate signals with other layers (and modules) hosted by DU 130 or with control functions hosted by CU 110.

[0041] The lower layer functionality may be implemented by one or more RUs 140. In some deployments, the RU 140 controlled by the DU 130 may correspond to a logical node that hosts RF processing functions or low PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc.), or both, based at least in part on functional splitting (such as lower layer functional splitting). In such an architecture, the RU 140 may be implemented to handle over-the-air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control plane and user plane communications with the RU 140 may be controlled by the corresponding DU 130. In some scenarios, this configuration may enable the implementation of the DU 130 and the CU 110 in a cloud-based RAN architecture (such as a vRAN architecture).

[0042] The SMO framework 105 may be configured to support RAN deployment and provisioning of non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 105 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO framework 105 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 190) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements may include, but are not limited to, CU 110, DU 130, RU 140, and near-RT RIC 125. In some specific implementations, the SMO framework 105 may communicate with hardware aspects of the 4G RAN (such as an open eNB (O-eNB) 111) via the O1 interface. Additionally, in some specific implementations, the SMO framework 105 may communicate directly with one or more RUs 140 via the O1 interface. The SMO framework 105 may also include a non-RT RIC 115 configured to support the functionality of the SMO framework 105 .

[0043] The non-RT RIC 115 may be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence (AI) / machine learning (ML) (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 125. The non-RT RIC 115 may be coupled to or communicate with the near-RT RIC 125 (such as via an A1 interface). The near-RT RIC 125 may be configured to include logic functions that enable near-real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via an E2 interface) that connects one or more CUs 110, one or more DUs 130, or both, and the O-eNB with the near-RT RIC 125.

[0044] In some implementations, in order to generate an AI / ML model to be deployed in the near-RT RIC 125, the non-RT RIC 115 may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 125 and may be received from a non-network data source or from a network function at the SMO framework 105 or the non-RT RIC 115. In some examples, the non-RT RIC 115 or the near-RT RIC 125 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 115 may monitor long-term trends and patterns of performance and employ AI / ML models to perform corrective actions through the SMO framework 105 (such as via reconfiguration of O1) or via the creation of RAN management policies (such as A1 policies).

[0045] At least one of the CU 110, the DU 130, and the RU 140 may be referred to as a base station 102. Therefore, the base station 102 may include one or more of the CU 110, the DU 130, and the RU 140 (each component is indicated by a dotted line to indicate that each component may be included in the base station 102 or may not be included in the base station). The base station 102 provides an access point to the core network 120 for the UE 104. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). Small cells include femto cells, pico cells, and micro cells. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). The communication link between RU 140 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to RU 140 and / or downlink (DL) (also known as forward link) transmission from RU 140 to UE 104. The communication link may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link may pass through one or more carriers. For each carrier allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, 400MHz, etc.) bandwidth. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0046] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL wireless wide area network (WWAN) spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be performed via a variety of wireless D2D communication systems, such as, for example, Bluetooth, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

[0047] Some examples of sidelink communications may include vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and / or combinations thereof, and / or vehicle-based communication devices communicating with other devices, which may be collectively referred to as vehicle-to-everything (V2X) communications. Sidelink communications may be based on V2X or other D2D communications, such as proximity services (ProSe), etc. In addition to the UE, sidelink communications may also be sent and received by other transmitting devices and receiving devices, such as a roadside unit (RSU) 107, etc. The PC5 interface may be used to exchange sidelink communications, such as in conjunction with Figure 2 Although including Figure 2 The following description of an example time slot structure may provide examples for sidelink communications related to 5G NR, but the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0048] The wireless communication system may also include a Wi-Fi AP 150 that communicates with a UE 104 (also referred to as a Wi-Fi station (STA)) via a communication link 154, e.g., in a 5 GHz unlicensed spectrum, etc. When communicating in an unlicensed spectrum, the UE 104 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether a channel is available.

[0049] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). Although a portion of FR1 is greater than 6 GHz, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band in various documents and articles. A similar naming issue sometimes 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).

[0050] 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 FR2-2 (52.6GHz-71GHz), FR4 (71GHz-114.25GHz) and FR5 (114.25GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

[0051] In view of the above, unless otherwise specifically stated, if the term "below 6 GHz" or the like is used in this document, it may broadly refer to frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. In addition, unless otherwise specifically stated, if the term "millimeter wave" or the like is used in this document, it may broadly refer to frequencies that may include mid-band frequencies, may be within FR2, FR4, FR2-2, and / or FR5, or may be within the EHF band.

[0052] The base station 102 and the UE 104 may each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming. The base station 102 may send a beamformed signal 182 to the UE 104 in one or more transmit directions. The UE 104 may receive the beamformed signal from the base station 102 in one or more receive directions. The UE 104 may also send a beamformed signal 184 to the base station 102 in one or more transmit directions. The base station 102 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 102 / UE 104 may perform beam training to determine the best receive direction and the best transmit direction for each of the base station 102 / UE 104. The transmit direction and the receive direction of the base station 102 may be the same, or may be different. The transmit direction and the receive direction of the UE 104 may be the same, or may be different.

[0053] The base station 102 may include and / or be referred to as a gNB, a Node B, an eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), a network node, a network entity, a network equipment, or some other suitable term. The base station 102 may be implemented as an integrated access and backhaul (IAB) node, a relay node, a sidelink node, an aggregated (monolithic) base station with a baseband unit (BBU) (including a CU and a DU) and a RU, or as a disaggregated base station including one or more of a CU, a DU, and / or a RU. A set of base stations that may include disaggregated base stations and / or aggregated base stations may be referred to as a next generation (NG) RAN (NG-RAN).

[0054] The core network 120 may include an access and mobility management function (AMF) 161, a session management function (SMF) 162, a user plane function (UPF) 163, a unified data management (UDM) 164, one or more location servers 168, and other functional entities. AMF 161 is a control node that handles signaling between UE 104 and core network 120. AMF 161 supports registration management, connection management, mobility management, and other functions. SMF 162 supports session management and other functions. UPF 163 supports packet routing, packet forwarding, and other functions. UDM 164 supports the generation of authentication and key agreement (AKA) credentials, user identity handling, access authorization, and subscription management. One or more location servers 168 are illustrated as including a gateway mobile location center (GMLC) 165 and a location management function (LMF) 166. However, in general, the one or more location servers 168 may include one or more location / positioning servers, which may include one or more of the GMLC 165, LMF 166, position determination entity (PDE), serving mobile location center (SMLC), mobile positioning center (MPC), etc. GMLC 165 and LMF 166 support UE location services. GMLC 165 provides an interface for clients / applications (e.g., emergency services) to access UE positioning information. LMF 166 receives measurement and assistance information from NG-RAN and UE 104 via AMF 161 to calculate the location of UE 104. NG-RAN may determine the location of UE 104 using one or more positioning methods. Positioning UE 104 may involve signal measurements, position estimation, and optional speed calculation based on these measurements. Signal measurements may be performed by UE 104 and / or serving base station 102. The measured signals may be based on a satellite positioning system (SPS) 170 (e.g., one or more of a global navigation satellite system (GNSS), a global positioning system (GPS), a non-terrestrial network (NTN), or other satellite positioning / positioning systems), LTE signals, wireless local area network (WLAN) signals, Bluetooth signals, a terrestrial beacon system (TBS), sensor-based information (e.g., an atmospheric pressure sensor, a motion sensor), an NR enhanced cell ID (NR E-CID) method, NR signals (e.g., multi-round trip time (multi-RTT), DL angle of departure (DL-AoD), DL time difference of arrival (DL-TDOA), UL time difference of arrival (UL-TDOA), and UL angle of arrival (UL-AoA) positioning), and / or one or more of other systems / signals / sensors.

[0055] Examples of UE 104 include cellular phones, smart phones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electric meters, gas pumps, large or small kitchen appliances, healthcare equipment, implants, sensors / actuators, displays, or any other similarly functional devices. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.). UE 104 may also be referred to as stations, mobile stations, subscriber stations, mobile units, subscriber units, wireless units, remote units, mobile devices, wireless devices, wireless communication devices, remote devices, mobile subscriber stations, access terminals, mobile terminals, wireless terminals, remote terminals, mobile phones, user agents, mobile clients, clients, or some other suitable terms. In some scenarios, the term UE may also be applied to one or more supporting devices, such as in a device cluster arrangement. One or more of these devices may access the network collectively and / or individually.

[0056] Reference again Figure 1 In certain aspects, the UE 104 may include a priority component 198 configured to detect a first sidelink synchronization signal from a first RAT and a second sidelink synchronization signal from a second RAT; determine a priority between synchronization sources associated with the first RAT and the second RAT; and send data using timing based on the determination of the priority between the first RAT and the second RAT.

[0057] Reference again Figure 1 In certain aspects, the UE 104 may include a synchronization component 199 configured to determine a side link synchronization signal to send as a synchronization source; and to select to send at least one of a first side link synchronization signal associated with a first RAT or a second side link synchronization signal associated with a second RAT.

[0058] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0059] Figure 2Diagrams 200 and 210 are included that illustrate example aspects of a slot structure that may be used for sidelink communications (e.g., between UE 104, RSU 107, etc.). In some examples, the slot structure may be within a 5G / NR frame structure. In other examples, the slot structure may be within an LTE frame structure. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. Figure 2 The example time slot structure in is only an example, and other side link communications may have different frame structures and / or different channels for side link communications. A frame (10ms) may be divided into 10 subframes of the same size (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4 or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. Schematic diagram 200 illustrates a single resource block transmitted in a single time slot corresponding to a 0.5ms transmission time interval (TTI). The physical side link control channel may be configured to occupy multiple physical resource blocks (PRBs), for example, 10, 12, 15, 20 or 25 PRBs. PSCCH may be limited to a single subchannel. PSCCH duration may be configured to, for example, 2 symbols or 3 symbols. A subchannel may include, for example, 10, 15, 20, 25, 50, 75, or 100 PRBs. Resources for sidelink transmissions may be selected from a resource pool including one or more subchannels. As a non-limiting example, a resource pool may include between 1 and 27 subchannels. A PSCCH size may be established for a resource pool, for example, to be between 10%-100% of a subchannel within a duration of 2 symbols or 3 symbols. Figure 2 Diagram 210 in illustrates an example in which the PSCCH occupies approximately 50% of a subchannel as an example to illustrate the concept of the PSCCH occupying a portion of a subchannel. A physical sidelink shared channel (PSSCH) occupies at least one subchannel. In some examples, the PSCCH may include a first portion of sidelink control information (SCI), and the PSSCH may include a second portion of the SCI.

[0060] A resource grid may be used to represent the frame structure. Each time slot may include a resource block (RB) (also called a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a number of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. Figure 2 As illustrated, some of the REs may include control information in the PSCCH and some of the REs may include a demodulation RS (DMRS).At least one symbol may be used for feedback. Figure 2 An example of two symbols for a physical sidelink feedback channel (PSFCH) with adjacent gap symbols is illustrated. Symbols before and / or after the feedback may be used for a transition between reception of data and transmission of feedback. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device in a subsequent time slot, for example. Data may be sent in the remaining REs as illustrated. The data may include data messages as described herein. The location of any of the data, DMRS, SCI, feedback, gap symbols, and / or LBT symbols may be different from Figure 2 Illustrated example. In some aspects, multiple time slots can be aggregated together.

[0061] Figure 3 3 is a block diagram of a first wireless communication device 310 communicating with a second wireless communication device 350 based on a side link. In some examples, the devices 310 and 350 may communicate based on V2X or other D2D communications. The communication may be based on a side link using a PC5 interface. The devices 310 and 350 may include UEs, RSUs, base stations, etc. Packets may be provided to a controller / processor 375 that implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer.

[0062] The transmit (TX) processor 316 and receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-order phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be separated into parallel streams. Each stream may then be mapped to an OFDM subcarrier, each stream may be multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and each stream may then be combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially pre-coded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback sent by the device 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate a radio frequency (RF) carrier with a corresponding spatial stream for transmission.

[0063] At the device 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial streams destined for the device 350. If multiple spatial streams are destined for the device 350, the RX processor 356 can combine them into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the signal constellation point most likely to be sent by the device 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by device 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functionality.

[0064] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. The controller / processor 359 may provide demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0065] Similar to the functionality described in conjunction with transmissions performed by device 310, the controller / processor 359 may provide RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0066] Channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the device 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0067] Transmissions are processed at device 310 in a manner similar to that described in connection with the receiver functionality at device 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to a RX processor 370.

[0068] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. The controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0069] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to combine Figure 1 The 198 came to execute all aspects.

[0070] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to combine Figure 1 199 to perform all aspects.

[0071] Figure 4 An example 400 of sidelink communication between devices is illustrated. The communication may be based on a combination of Figure 2 The time slot structure of the various aspects described. For example, UE 402 may send a sidelink transmission 414, such as a control channel (e.g., PSCCH) and / or a corresponding data channel (e.g., PSSCH), which may be received by UE 404, 406, 408. The control channel may include information for decoding the data channel (e.g., sidelink control information (SCI)), which includes reservation information, such as information about the time and / or frequency resources reserved for data channel transmission. For example, the SCI may indicate the TTI and the number of RBs to be occupied by the data transmission. The SCI may also be used by the receiving device to avoid interference by avoiding transmission on the reserved resources. In addition to the sidelink reception, UE 402, 404, 406, 408 may each be capable of sidelink transmission. Therefore, UE 404, 406, 408 is illustrated as sending sidelink transmissions 413, 415, 416, 420. The sidelink transmissions 413, 414, 415, 416, 420 may be unicast, broadcast, or multicast to nearby devices. For example, UE 404 may transmit sidelink transmissions 413, 415 intended to be received by other UEs within range 401 of UE 404, and UE 406 may transmit sidelink transmission 416. Additionally / alternatively, RSU 407 may receive communications from UE 402, 404, 406, 408 and / or transmit communications 418 to these UEs. One or more of UE 402, 404, 406, 408 or RSU 407 may include, for example, a combination of Figure 1 The priority component 198 is described.

[0072] Sidelink communication may be based on resource allocation mechanisms of different types or modes. In a first resource allocation mode (which may be referred to herein as "mode 1"), centralized resource allocation may be provided by a network entity. For example, a base station 102 may determine resources for sidelink communication, and may allocate resources to different UEs 104 for sidelink transmission. In this first mode, the UE receives an allocation of sidelink resources from the base station 102. In a second resource allocation mode (which may be referred to herein as "mode 2"), distributed resource allocation may be provided. In mode 2, each UE may autonomously determine the resources to be used for sidelink transmission. In order to coordinate the selection of sidelink resources by each UE, each UE may use sensing technology to monitor the resource reservations of other sidelink UEs, and may select resources for sidelink transmission from unreserved resources. A device communicating based on a sidelink may determine one or more radio resources used by other devices in the time domain and the frequency domain in order to select transmission resources that avoid conflicts with other devices. Sidelink transmissions and / or resource reservations may be periodic or aperiodic, where the UE may reserve resources for transmissions in the current slot and up to two future slots (as discussed below).

[0073] Thus, in this second mode (e.g., Mode 2), each UE may autonomously select resources for sidelink transmission, e.g., without a central entity (such as a base station) indicating resources for the device. The first UE may reserve the selected resources in order to inform other UEs about the resources that the first UE intends to use for sidelink transmission.

[0074] In some examples, resource selection for sidelink communication can be based on a sensing mechanism. For example, before selecting resources for data transmission, the UE can first determine whether the resources have been reserved by other UEs.

[0075] For example, as part of a sensing mechanism for resource allocation mode 2, the UE may determine (e.g., sense) whether the selected side link resource has been reserved by other UEs before selecting the side link resource for data transmission. If the UE determines that the side link resource has not been reserved by other UEs, the UE may use the selected side link resource for sending data, for example, in a PSSCH transmission. The UE may estimate or determine which radio resources (e.g., side link resources) may be in use and / or reserved by other UEs by detecting and decoding side link control information (SCI) sent by other UEs. The UE may estimate or determine which radio resources are in use and / or reserved by other UEs using a sensing-based resource selection algorithm. The UE may receive an SCI from another UE, the SCI including reservation information based on a resource reservation field included in the SCI. The UE may continuously monitor (e.g., sense) and decode the SCI from a peer UE. The SCI may include reservation information, for example, indicating that a particular UE has selected a time slot and RB for future transmission. The UE may exclude resources used and / or reserved by other UEs from the candidate resource set used by the UE for sidelink transmission, and the UE may select / reserve resources for sidelink transmission from resources that are not used and thus form a candidate resource set. The UE may continuously perform sensing on the SCI with resource reservations so as to maintain a candidate resource set from which the UE may select one or more resources for sidelink transmission. Once the UE selects a candidate resource, the UE may send an SCI indicating the UE's own reservation of resources for sidelink transmission. The number of resources (e.g., subchannels per subframe) reserved by the UE may depend on the size of the data to be sent by the UE. Although this example is described for a UE receiving reservation information from another UE, the reservation information may also be received from an RSU or other device communicating based on a sidelink.

[0076] In wireless communications such as sidelink communications, NR V2X and LTE V2X may have to operate in the same channel. Partly due to the lack of wireless spectrum, NR V2X and LTE V2X may have to operate in the same channel. In the absence of a coordination mechanism, NR V2X transmissions may conflict with LTE V2X transmissions because both occupy the same time-frequency resources. The performance of the two systems may be degraded due to the conflict. In some cases, NR V2X may include dual radio devices. NR V2X dual radio devices can be configured to send basic safety message (BSM) packets or collaborative awareness message (CAM) packets in LTE V2X, and to send sensor sharing or other business data on NR V2X.

[0077] In the simplest form, the coordination may include a resource pool frame structure such that NR V2X may access the channel in one time slot and LTE V2X may access the channel in another time slot. However, in order to utilize the resource pool frame structure, both technologies and all UEs in the network will have to agree on the resource pool partitioning. The resource pool partitioning will evolve over time as NR V2X penetration increases. The resource pools may also evolve based on changes in traffic on NR or LTE. However, changes in the LTE protocol / modem may not be available such that the changes may occur in a manner such that the NR device can implicitly make the LTE device aware of the resource pool partitioning.

[0078] Resource partitioning between NR and LTE may be utilized so that NR and LTE coexist. At least one approach may include partitioning the available bandwidth between LTE and NR, but this approach may not adapt to network conditions. For example, when there are more LTE UEs in the system, equal partitioning may degrade LTE performance. In some cases, when there are more NR UEs in the system, equal or fixed partitioning may prevent NR from using available radio resources for advanced services. An adaptive approach may include LTE performing resource sorting based on received signal strength indication (RSSI), which may back off resources where the measured RSSI is higher. NR may estimate the ratio of NR devices to LTE devices in the system, and may determine resource pool partitioning based on the NR to LTE ratio. NR UEs may transmit on resources determined for NR and may skip resources determined for LTE.

[0079] Figure 5 5 is a diagram illustrating an example of an NR resource pool frame structure. The NR resource pool frame structures 502, 504, 506 may include an LTE slot 514, an NR slot 516, an NR PSFCH resource slot 518, an NR and LTE frequency domain multiplexing slot 520, or an NR and LTE time domain multiplexing slot 508. In some cases, the NR resource pool frame structure may be determined based on NR penetration, such as, for example Figure 5502 or 504. The penetration rate may be a percentage of UEs with NR capabilities. The penetration rate may be determined by an indication in the LTE side link control information or in the MAC-CE indicating that the UE is capable of NR and LTE. In some cases, the penetration rate may be estimated using a channel busy rate (CBR) or by decoding control and data for both NR and LTE. Each NR device may be configured to adjust the resource pool frame structure based on the most recent or latest penetration rate estimate. LTE and NR resources may be time-domain multiplexed on some time slots, or may be frequency-domain multiplexed on the same or other time slots. For example, the NR resource pool frame structure 506 includes NR and LTE time-domain multiplexed time slots 508, wherein the first half 510 of the time slot is used for LTE, and the second half 512 of the time slot is used for NR, so that LTE and NR are time-domain multiplexed within the time slot 508. In some cases, the resource pool pattern may include physical side link feedback channel resources (e.g., 518) for the NR side link.

[0080] Fig. 6A 600 is a diagram illustrating an example of an LTE synchronization subframe 602. The LTE synchronization subframe 602 may include a physical sidelink broadcast channel (PSBCH) 604, 610 and a sidelink (SL) synchronization signal (SS) (SL-SS) 606, 608. The LTE synchronization subframe 602 may include 2 primary sidelink synchronization signal symbols, 2 secondary sidelink synchronization signal symbols, 3 DMRS symbols for decoding PSBCH, and 1 guard symbol. The transmission bandwidth may include 6 PRBs and may have a transmission periodicity of 160ms.

[0081] Figure 6B620 is a diagram illustrating an example of an NR synchronization subframe 622. The NR synchronization subframe 622 may include one subframe every 160 ms for in-coverage and two or three subframes every 160 ms for out-of-coverage, as shown in a synchronization resource structure 624. In some cases, one resource may be configured for in-coverage using a synchOffsetIndicator 626. In pre-configuration, the network entity may ensure that the synchOffsetIndicator 626 is the same as the synchOffsetIndicator-1 628. Two or three resources may be configured for out-of-coverage using, for example, synchOffsetIndicator-1 628, synchOffsetIndicator-2 630, or synchOffsetIndicator-3 632. The synchronization procedure may be different based on whether the synchOffsetIndicator-3 632 is configured. The synchronization source may include one or more of a base station, a GNSS, or a synchronization reference UE (SyncRefUE). SyncRef UE may have a direct connection (eg, 1 hop or indirect (greater than 1 hop) or independent synchronization source) to a base station or GNSS.

[0082] Figure 7 700 is an example of an NR synchronization subframe 702. The NR synchronization subframe 702 may include PSBCH 704, 710, SL primary synchronization signal (PSS) (SL-PSS) 706 and SL secondary synchronization signal (SL-SSS) 708. NR uses many LTE synchronization procedures. The sidelink synchronization signal identifier (Id) may be selected based on the synchronization reference signal, and support for in-coverage, GNSS and out-of-coverage synchronization may be provided, and the synchronization resource location may be indicated by SyncOffset. However, the NR synchronization signal has some differences compared to LTE. For example, the NR synchronization signal may have a different synchronization signal position in the subframe compared to LTE. NR synchronization may reuse the NR PSS and SSS for Uu (e.g., LTE uses Zadoff Chu sequences, NR uses m-sequences similar to NR PSS / SSS). LTE has a fixed mapping of sidelink synchronization signal subframes on frequency. NR UEs may have a configured or preconfigured starting RB for the synchronization subframe.

[0083] Sidelink synchronization priority may be based on synchronization source. For example, in the case of network coverage where GNSS has the highest priority, the sidelink synchronization priority order may include GNSS, synchronization reference (SyncRef) UE (e.g., synchronized to GNSS, SLSSID=0), or network entity. In the case of out-of-coverage where GNSS has the highest priority, the sidelink synchronization priority order may include GNSS, SyncRef UE directly synchronized to the network entity (e.g., SL SSID=0, INC=1 / or / SL SSID=0, resource=3), SyncRef UE indirectly synchronized to the network entity (e.g., SL SSID in slss_net, INC=0), SyncRef UE indirectly synchronized to GNSS via INC UE (e.g., SL SSID=0, INC=FALSE and resource 1 or 2), SyncRef UE indirectly synchronized to GNSS via out-of-coverage UE (e.g., SL SSID=169, INC=FALSE), or independent SyncRef UE.

[0084] In the case where the network entity (e.g., base station) is within the network coverage with the highest priority, the sidelink synchronization priority order may include the network entity. In the case where the network entity is outside the coverage with the highest priority, the sidelink synchronization priority order may include a SyncRef UE directly synchronized to the network entity (e.g., SL SSID in slss_net, INC=1), a SyncRef UE indirectly synchronized to the network entity (e.g., SL SSID in slss_net, INC=0), GNSS, a SyncRef UE directly synchronized to the GNSS (e.g., SL SSID=0, INC=1, or SL SSID=0, resource=3), a SyncRef UE indirectly synchronized to the GNSS (e.g., SL SSID=0, INC=FALSE and resource 1 or 2), a SyncRef UE indirectly synchronized to the GNSS via an out-of-coverage UE (e.g., SL SSID=169, INC=FALSE), or an independent SyncRef UE.

[0085] Co-channel coexistence between NR and LTE requires time synchronization between LTE and NR devices, otherwise any dynamic mechanism to avoid or minimize conflicts may not be feasible. The network may have multiple synchronization sources. In a distributed network, NR and LTE UEs should achieve the same timing. Therefore, it is necessary to determine the priority rules for time synchronization without making any changes to LTE devices.

[0086] Aspects presented herein provide a configuration for prioritizing synchronization signals for NR-LTE in-band coexistence. Aspects presented herein provide a scheme for NR UE to effectively prioritize synchronization reference and synchronization burst transmissions when both LTE and NR SyncRef UEs are in the network. At least one advantage of the present disclosure is that additional priority levels can be distinguished between NR and LTE SyncRef UEs. At least another advantage is that dual devices (e.g., devices that support both NR and LTE) can have rules for prioritizing synchronization signaling based on set priority rules.

[0087] Figure 8 8 is a call flow diagram 800 of signaling between UE 802 and UE 804. UE 802 may be configured to communicate with a base station (not shown). Figure 1 In the context of , UE 802 may correspond to at least UE 104, and UE 804 may correspond to at least UE 104. For example, in Figure 3 In the context of , UE 804 may correspond to device 310 and UE 802 may correspond to device 350.

[0088] At 810, UE 802 may detect a first sidelink synchronization signal from a first RAT. UE 802 may also detect a second sidelink synchronization signal from a second RAT. For example, UE 802 may detect a first sidelink synchronization signal 812 from a first RAT 806, and UE 802 may detect a second synchronization signal 814 from a second RAT 808. In some aspects, the first RAT may include LTE and the second RAT may include NR. However, the present disclosure is not intended to be limited to the first RAT and the second RAT being LTE and NR. In some aspects, the first RAT and / or the second RAT may include or may be associated with any wireless communication network.

[0089] At 816, UE 802 may determine a priority between a first synchronization source associated with the first RAT and a second synchronization source associated with the second RAT. In some aspects, the priority of the first RAT may be higher than the priority of the second RAT. For example, where the first RAT includes LTE, the first synchronization source may have a higher priority than the priority of the second synchronization source associated with the second RAT such that synchronization is performed using the first sidelink synchronization source. In some aspects, the priority of the first RAT may be preconfigured or configurable.

[0090] At 818, UE 802 may send data using timing based on a determination of a priority between the first RAT and the second RAT. For example, UE 802 may send data to another UE 804 via a side link using timing based on a determination of a priority between the first RAT and the second RAT. In some aspects, the timing of the first RAT may be used based on at least a first side link synchronization signal of the first RAT. The first side link synchronization signal of the first RAT may be derived from a synchronization source having a higher priority than the current synchronization source, wherein the current synchronization source does not include a synchronization reference UE. For example, when the current synchronization source is not a synchronization reference UE, the LTE side link synchronization signal may have a higher priority than the current synchronization source. In some aspects, the timing of the first RAT may be used based on at least a synchronization reference UE being associated with the second RAT. In such aspects, the signal strength of the first side link synchronization signal may be greater than the signal strength of the side link SSB received from the synchronization reference UE associated with the second RAT by a first threshold. The first threshold may be preconfigured or configurable. For example, where the first RAT includes LTE and the second RAT includes NR, if the synchronization reference UE is associated with NR, the signal strength of the LTE sidelink synchronization signal is greater than the sidelink SSB signal strength received from the synchronization reference UE associated with the second RAT. In another example, where both the LTE sidelink synchronization signal transmitter and the NR SSB transmitter are independent synchronization sources, the UE receiving the synchronization signal may make a selection based on the RSRP difference. In some aspects, the timing of the first RAT may be used based at least on the association of the synchronization reference UE with the second RAT. The second sidelink synchronization signal of the synchronization reference UE may be derived from a synchronization source having a priority similar to or less than a priority of the first sidelink synchronization signal of the synchronization reference UE associated with the first RAT. For example, in some aspects, the SSB sequence ID and / or the SSB transmission resource may indicate the source of the synchronization information.

[0091] At 820, UE 802 may determine to send a sidelink synchronization signal as a synchronization source. The UE may determine to send a sidelink synchronization signal as a synchronization source in response to detecting a first sidelink synchronization signal from a first RAT. For example, where the UE includes an NR UE, the NR UE may determine to become a synchronization source upon detecting an LTE sidelink synchronization signal. In some aspects, the UE may select an LTE UE as its synchronization source.

[0092] At 822, UE 802 may determine to send at least one of a first side link synchronization signal or a second side link synchronization signal. In some aspects, the first side link synchronization signal may be sent. In some aspects, the second side link synchronization signal may be sent. In some aspects, the first side link synchronization signal and the second side link synchronization signal may be based on at least one of the following: a received signal reference power (RSRP) of the first side link synchronization signal is less than a threshold, the timing of the second side link synchronization signal is not synchronized with the timing of the first side link synchronization signal (e.g., the NR side link SSB is asynchronous with the LTE UE timing tμs), the UE's previous timing is not synchronized with the timing of the first side link synchronization signal (e.g., the previous timing is asynchronous with the LTE UE timing t 0 μs), or the UE can be a synchronization source for other UEs.

[0093] At 824, UE 802 may send a first sidelink synchronization signal or a second sidelink synchronization signal. The UE may send the first sidelink synchronization signal or the second sidelink synchronization signal based on the determination of 822 to send at least one of the first sidelink synchronization signal or the second sidelink synchronization signal. UE 802 may send the first sidelink synchronization signal or the second sidelink synchronization signal to UE 804.

[0094] Fig. 9 900 is a flow chart of a method of wireless communication. The method may be performed by a UE (eg, UE 104; device 1104). One or more of the illustrated operations may be omitted, swapped, or performed simultaneously. The method may allow the UE to effectively prioritize synchronization references from different sources.

[0095] At 902, the UE may detect a first sidelink synchronization signal. For example, 902 may be performed by the priority component 198 of the device 1104. The UE may detect the first sidelink synchronization signal from the first RAT. The UE may also detect a second sidelink synchronization signal from the second RAT. In some aspects, the first RAT may include LTE and the second RAT may include NR.

[0096] At 904, the UE may determine a priority between synchronization sources associated with the first RAT and the second RAT. For example, 904 may be performed by the priority component 198 of the device 1104. In some aspects, the priority of the first RAT may be higher than the priority of the second RAT. In some aspects, the priority of the first RAT may be preconfigured or configurable.

[0097] At 906, the UE may send data using timing based on a determination of a priority between the first RAT and the second RAT. For example, 906 may be performed by the priority component 198 of the device 1104. The UE may send data to another UE via a side link using timing based on a determination of a priority between the first RAT and the second RAT. In some aspects, the timing of the first RAT may be used based at least on a first side link synchronization signal of the first RAT. The first side link synchronization signal of the first RAT may be derived from a synchronization source having a higher priority than the current synchronization source. In some aspects, the current synchronization source may not include a synchronization reference UE. In some aspects, the timing of the first RAT may be used based at least on the synchronization reference UE being associated with the second RAT. In such aspects, the signal strength of the first side link synchronization signal may be greater than the signal strength of the side link synchronization signal block (SSB) received from the synchronization reference UE associated with the second RAT by a first threshold. The first threshold may be preconfigured or configurable. In some aspects, the timing of the first RAT may be used based at least on the synchronization reference UE being associated with the second RAT. The second sidelink synchronization signal of the synchronization reference UE may be derived from a synchronization source having a priority similar to or less than a priority of the first sidelink synchronization signal of the synchronization reference UE associated with the first RAT.

[0098] Fig.10 1000 is a flow chart of a method of wireless communication. The method may be performed by a UE (eg, UE 104; device 1104). One or more of the illustrated operations may be omitted, swapped, or performed simultaneously. The method may allow the UE to effectively prioritize synchronization references from different sources.

[0099] At 1002, the UE may detect a first sidelink synchronization signal. For example, 1002 may be performed by the priority component 198 of the device 1104. The UE may detect the first sidelink synchronization signal from the first RAT. The UE may also detect a second sidelink synchronization signal from the second RAT. In some aspects, the first RAT may include LTE and the second RAT may include NR.

[0100] At 1004, the UE may determine a priority between synchronization sources associated with the first RAT and the second RAT. For example, 1004 may be performed by a priority component 198 of the device 1104. In some aspects, the priority of the first RAT may be higher than the priority of the second RAT. In some aspects, the priority of the first RAT may be preconfigured or configurable.

[0101] At 1006, the UE may send data using timing based on a determination of a priority between the first RAT and the second RAT. For example, 1006 may be performed by the priority component 198 of the device 1104. The UE may send data to another UE via a side link using timing based on a determination of a priority between the first RAT and the second RAT. In some aspects, the timing of the first RAT may be used based at least on a first side link synchronization signal of the first RAT. The first side link synchronization signal of the first RAT may be derived from a synchronization source having a higher priority than the current synchronization source, wherein the current synchronization source does not include a synchronization reference UE. In some aspects, the timing of the first RAT may be used based at least on the association of the synchronization reference UE with the second RAT. In such aspects, the signal strength of the first side link synchronization signal may be greater than the signal strength of the side link SSB received from the synchronization reference UE associated with the second RAT by a first threshold. The first threshold may be preconfigured or configurable. In some aspects, the timing of the first RAT may be used based at least on the association of the synchronization reference UE with the second RAT. The second sidelink synchronization signal of the synchronization reference UE may be derived from a synchronization source having a priority similar to or less than a priority of the first sidelink synchronization signal of the synchronization reference UE associated with the first RAT.

[0102] At 1008, the UE may determine to send a sidelink synchronization signal as a synchronization source. For example, 1008 may be performed by the priority component 198 of the device 1104. The UE may determine to send a sidelink synchronization signal as a synchronization source in response to detecting a first sidelink synchronization signal from a first RAT.

[0103] At 1010, the UE may determine to send at least one of a first side link synchronization signal or a second side link synchronization signal. For example, 1010 may be performed by the priority component 198 of the device 1104. In some aspects, the first side link synchronization signal may be sent. In some aspects, the first side link synchronization signal and the second side link synchronization signal may be based on at least one of: a received signal reference power (RSRP) of the first side link synchronization signal is less than a threshold, the timing of the second side link synchronization signal is not synchronized with the timing of the first side link synchronization signal, the previous timing of the UE is not synchronized with the timing of the first side link synchronization signal, or the UE may be a synchronization source for other UEs.

[0104] Fig.111100 is a diagram illustrating an example of a hardware implementation for an apparatus 1104. The apparatus 1104 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus 1104 may include a cellular baseband processor 1124 (also referred to as a modem) coupled to one or more transceivers 1122 (e.g., a cellular RF transceiver). The cellular baseband processor 1124 may include on-chip memory 1124'. In some aspects, the apparatus 1104 may also include one or more subscriber identity module (SIM) cards 1120 and an application processor 1106 coupled to a secure digital (SD) card 1108 and a screen 1110. The application processor 1106 may include on-chip memory 1106'. In some aspects, the device 1104 may also include a Bluetooth module 1112, a WLAN module 1114, an SPS module 1116 (e.g., a GNSS module), one or more sensor modules 1118 (e.g., an atmospheric pressure sensor / altimeter; a motion sensor such as an inertial management unit (IMU), a gyroscope, and / or an accelerometer; light detection and ranging (LIDAR), radio-aided detection and ranging (RADAR), sound navigation and ranging (SONAR), a magnetometer, audio for positioning, and / or other technologies), an additional memory module 1126, a power source 1130, and / or a camera 1132. The Bluetooth module 1112, the WLAN module 1114, and the SPS module 1116 may include an on-chip transceiver (TRX) (or in some cases, only a receiver (RX)). The Bluetooth module 1112, the WLAN module 1114, and the SPS module 1116 may include their own dedicated antennas and / or communicate using antennas 1180. The cellular baseband processor 1124 communicates with the UE 104 and / or with the RU associated with the network entity 1102 through the transceiver 1122 via one or more antennas 1180. The cellular baseband processor 1124 and the application processor 1106 may each include a computer-readable medium / memory 1124', 1106', respectively. The additional memory module 1126 may also be considered a computer-readable medium / memory. Each computer-readable medium / memory 1124', 1106', 1126 may be non-transitory. The cellular baseband processor 1124 and the application processor 1106 are each responsible for general processing, including executing software stored on a computer-readable medium / memory. The software, when executed by the cellular baseband processor 1124 / application processor 1106, enables the cellular baseband processor 1124 / application processor 1106 to perform the various functions described above. The computer-readable medium / memory may also be used to store data manipulated by the cellular baseband processor 1124 / application processor 1106 when executing the software.The cellular baseband processor 1124 / application processor 1106 may be a component of the device 350 and may include the memory 360, and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. In one configuration, the device 1104 may be a processor chip (modem and / or application) and include only the cellular baseband processor 1124 and / or the application processor 1106, and in another configuration, the device 1104 may be the entire UE (e.g., see. Figure 3 350) and includes additional modules of device 1104.

[0105] As discussed above, component 198 is configured to detect a first sidelink synchronization signal from a first RAT and a second sidelink synchronization signal from a second RAT; determine a priority between synchronization sources associated with the first RAT and the second RAT; and send data using timing based on the determination of the priority between the first RAT and the second RAT. Component 198 may be within the cellular baseband processor 1124, within the application processor 1106, or within both the cellular baseband processor 1124 and the application processor 1106. Component 198 may be one or more hardware components that are specifically configured to perform the stated process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. As shown, the device 1104 may include a variety of components configured for various functions. In one configuration, the device 1104, and specifically, the cellular baseband processor 1124 and / or the application processor 1106, includes a component that detects a first sidelink synchronization signal from a first RAT and a second sidelink synchronization signal from a second RAT. The device includes a component for determining a priority between synchronization sources associated with a first RAT and a second RAT. The device includes a component for sending data using a timing based on a determination of a priority between the first RAT and the second RAT. The device also includes a component for determining to send a side link synchronization signal as a synchronization source in response to detecting a first side link synchronization signal from the first RAT. The device also includes a component for determining to send at least one of the first side link synchronization signal or the second side link synchronization signal. The component can be a component 198 of the device 1104 configured to perform the functions recorded by the component. As described above, the device 1104 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Therefore, in one configuration, the component can be a TX processor 368, an RX processor 356, and / or a controller / processor 359 configured to perform the functions recorded by the component.

[0106] Fig.121200 is a call flow diagram of signaling between UE 1202 and UE 1204. UE 1202 may be configured to communicate with a base station (not shown). Figure 1 In the context of , UE 1202 may correspond to at least UE 104, and UE 1204 may correspond to at least UE 104. For example, in Figure 3 In the context of , UE 1204 may correspond to device 310 and UE 1202 may correspond to device 350.

[0107] At 1210, UE 1202 may receive a sidelink synchronization signal from a first RAT and a sidelink synchronization signal from a second RAT. For example, UE 1202 may receive a first sidelink synchronization signal 1212 from a first RAT 1206, and UE 1202 may receive a second sidelink synchronization signal 1214 from a second RAT 1208. The sidelink synchronization signal from the first RAT and the sidelink synchronization signal from the second RAT may come from one or more sources. In some aspects, the source of the second RAT may include a GNSS, and the source of the first RAT may be from a synchronization reference UE. In some aspects, timing information derived from a second sidelink synchronization signal associated with the second RAT may be selected for transmission in response to the source of the sidelink synchronization signal from the second RAT having a higher priority. For example, the first sidelink synchronization signal may include an NR sidelink SSB, and the second sidelink synchronization signal may include an LTE sidelink synchronization signal, wherein if the NR sidelink SSB is from a synchronization source having a higher priority, the UE 1202 may send the NR sidelink SSB, otherwise the UE 1202 may send the LTE sidelink synchronization source. In some aspects, the timing information derived from the first sidelink synchronization signal associated with the first RAT may be selected for transmission in response to the source of the sidelink synchronization signal from the first RAT having a higher priority. In some aspects, the second sidelink synchronization signal associated with the second RAT may be selected for transmission. The second sidelink synchronization signal associated with the second RAT may be selected for transmission in response to an estimate of the number of UEs capable of communicating with the second RAT being higher than a threshold. For example, in the case where the UE 1202 includes an NR UE, if the NR penetration rate is higher than a threshold, the NR UE may send the NR sidelink SSB, wherein the threshold may be configurable or preconfigured.

[0108] At 1216, UE 1202 may determine to send a sidelink synchronization signal. The UE may determine to send a sidelink synchronization signal as a synchronization source.

[0109] At 1218, UE 1202 may select to send at least one of a first side link synchronization signal associated with a first RAT or a second side link synchronization signal associated with a second RAT. In some aspects, the first side link synchronization signal associated with the first RAT may be selected for transmission. In some aspects, the second side link synchronization signal associated with the second RAT may be selected for transmission. The first side link synchronization signal associated with the first RAT may be selected for transmission in response to the first side link synchronization signal and the second side link synchronization signal operating on the same frequency band. For example, in the case where the first side link synchronization signal includes an LTE side link synchronization signal and the second side link synchronization signal includes an NR side link SSB, the UE sends the LTE side link synchronization signal and does not send the NR side link SSB. In some aspects, the selection of the first side link synchronization signal or the second side link synchronization signal may be based on the priority of the synchronization source, and the first side link synchronization signal and the second side link synchronization signal are derived from the synchronization source. In some aspects, the first side link synchronization signal may be selected for transmission in response to the first side link synchronization signal source having a timing priority higher than the second side link synchronization signal source. In some aspects, the second sidelink synchronization signal may be selected for transmission in response to the second sidelink synchronization signal having a higher timing priority than the first sidelink synchronization signal. For example, the UE may receive an NR sidelink SSB and an LTE sidelink synchronization signal from different sources, wherein the source of the NR sidelink SSB comprises a GNSS and the source of the LTE sidelink synchronization signal comprises a synchronization reference UE, such that if the GNSS has a higher priority, the UE may transmit the NR sidelink SSB, otherwise the UE transmits the LTE sidelink synchronization signal.

[0110] At 1220, UE 1202 may send a first sidelink synchronization signal or a second sidelink synchronization signal. The UE may send the first sidelink synchronization signal or the second sidelink synchronization signal based on the selection of sending at least one of the first sidelink synchronization signal associated with the first RAT or the second sidelink synchronization signal associated with the second RAT at 1218. UE 1202 may send the first sidelink synchronization signal or the second sidelink synchronization signal to UE 1204.

[0111] Fig.13 1300 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104; device 1504). One or more of the illustrated operations may be omitted, swapped, or performed simultaneously. The method may allow the UE to effectively prioritize synchronization transmission when there are different synchronization reference UEs.

[0112] At 1302, the UE may determine to send a sidelink synchronization signal. For example, 1302 may be performed by synchronization component 199 of device 1504. The UE may determine to send a sidelink synchronization signal as a synchronization source.

[0113] At 1304, the UE may select to send at least one of a first side link synchronization signal associated with the first RAT or a second side link synchronization signal associated with the second RAT. For example, 1304 may be performed by the synchronization component 199 of the device 1504. In some aspects, the first side link synchronization signal associated with the first RAT may be selected for transmission. The first side link synchronization signal associated with the first RAT may be selected for transmission in response to the first side link synchronization signal and the second side link synchronization signal operating on the same frequency band. In some aspects, the selection of the first side link synchronization signal or the second side link synchronization signal may be based on the priority of the synchronization source, and the first side link synchronization signal and the second side link synchronization signal are derived from the synchronization source. In some aspects, the first side link synchronization signal may be selected for transmission. The first side link synchronization signal may be selected for transmission in response to the first side link synchronization signal source having a higher timing priority than the second side link synchronization signal source. In some aspects, the second side link synchronization signal may be selected for transmission. The second side link synchronization signal may be selected for transmission in response to the second side link synchronization signal having a higher timing priority than the first side link synchronization signal.

[0114] Fig.14 1400 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104; device 1504). One or more of the illustrated operations may be omitted, swapped, or performed simultaneously. The method may allow the UE to effectively prioritize synchronization transmission when there are different synchronization reference UEs.

[0115] At 1402, the UE may receive a sidelink synchronization signal from a first RAT and a sidelink synchronization signal from a second RAT. For example, 1402 may be performed by the synchronization component 199 of the device 1504. The sidelink synchronization signal from the first RAT and the sidelink synchronization signal from the second RAT may come from one or more sources. In some aspects, the source of the second RAT may include GNSS, and the source of the first RAT may come from a synchronization reference UE. In some aspects, the timing information derived from the second sidelink synchronization signal associated with the second RAT may be selected for transmission in response to the source of the sidelink synchronization signal from the second RAT having a higher priority. In some aspects, the timing information derived from the first sidelink synchronization signal associated with the first RAT may be selected for transmission in response to the source of the sidelink synchronization signal from the first RAT having a higher priority. In some aspects, the second sidelink synchronization signal associated with the second RAT may be selected for transmission. The second sidelink synchronization signal associated with the second RAT may be selected for transmission in response to an estimate of the number of UEs capable of communicating with the second RAT being higher than a threshold.

[0116] At 1404, the UE may determine to send a sidelink synchronization signal. For example, 1404 may be performed by synchronization component 199 of device 1504. The UE may determine to send a sidelink synchronization signal as a synchronization source.

[0117] At 1406, the UE may select to send at least one of a first side link synchronization signal associated with the first RAT or a second side link synchronization signal associated with the second RAT. For example, 1406 may be performed by the synchronization component 199 of the device 1504. In some aspects, the first side link synchronization signal associated with the first RAT may be selected for transmission. The first side link synchronization signal associated with the first RAT may be selected for transmission in response to the first side link synchronization signal and the second side link synchronization signal operating on the same frequency band. In some aspects, the selection of the first side link synchronization signal or the second side link synchronization signal may be based on the priority of the synchronization source, and the first side link synchronization signal and the second side link synchronization signal are derived from the synchronization source. In some aspects, the first side link synchronization signal may be selected for transmission. The first side link synchronization signal may be selected for transmission in response to the first side link synchronization signal source having a higher timing priority than the second side link synchronization signal source. In some aspects, the second side link synchronization signal may be selected for transmission. The second side link synchronization signal may be selected for transmission in response to the second side link synchronization signal having a higher timing priority than the first side link synchronization signal.

[0118] Fig.151500 is a diagram illustrating an example of a hardware implementation for an apparatus 1504. The apparatus 1504 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus 1504 may include a cellular baseband processor 1524 (also referred to as a modem) coupled to one or more transceivers 1522 (e.g., a cellular RF transceiver). The cellular baseband processor 1524 may include on-chip memory 1524'. In some aspects, the apparatus 1504 may also include one or more subscriber identity module (SIM) cards 1520 and an application processor 1506 coupled to a secure digital (SD) card 1508 and a screen 1510. The application processor 1506 may include on-chip memory 1506'. In some aspects, the device 1504 may also include a Bluetooth module 1512, a WLAN module 1514, an SPS module 1516 (e.g., a GNSS module), one or more sensor modules 1518 (e.g., an atmospheric pressure sensor / altimeter; a motion sensor such as an inertial management unit (IMU), a gyroscope, and / or an accelerometer; light detection and ranging (LIDAR), radio-aided detection and ranging (RADAR), sound navigation and ranging (SONAR), a magnetometer, audio for positioning, and / or other technologies), an additional memory module 1526, a power source 1530, and / or a camera 1532. The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include an on-chip transceiver (TRX) (or in some cases, only a receiver (RX)). The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include their own dedicated antennas and / or communicate using an antenna 1580. The cellular baseband processor 1524 communicates with the UE 104 and / or with the RU associated with the network entity 1502 through the transceiver 1522 via one or more antennas 1580. The cellular baseband processor 1524 and the application processor 1506 may each include a computer-readable medium / memory 1524', 1506', respectively. The additional memory module 1526 may also be considered as a computer-readable medium / memory. Each computer-readable medium / memory 1524', 1506', 1526 may be non-transitory. The cellular baseband processor 1524 and the application processor 1506 are each responsible for general processing, including executing software stored on a computer-readable medium / memory. The software, when executed by the cellular baseband processor 1524 / application processor 1506, enables the cellular baseband processor 1524 / application processor 1506 to perform the various functions described above. The computer-readable medium / memory can also be used to store data manipulated by the cellular baseband processor 1524 / application processor 1506 when executing the software.The cellular baseband processor 1524 / application processor 1506 may be a component of the device 310 and may include the memory 360, and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. In one configuration, the apparatus 1504 may be a processor chip (modem and / or application) and include only the cellular baseband processor 1524 and / or the application processor 1506, and in another configuration, the apparatus 1504 may be the entire UE (e.g., see. Figure 3 310) and includes additional modules of device 1504.

[0119] As discussed above, component 199 is configured to determine to send a sidelink synchronization signal as a synchronization source; and to select to send at least one of a first sidelink synchronization signal associated with a first RAT or a second sidelink synchronization signal associated with a second RAT. Component 199 may be within the cellular baseband processor 1524, within the application processor 1506, or within both the cellular baseband processor 1524 and the application processor 1506. Component 199 may be one or more hardware components that are specifically configured to perform the stated process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. As shown, device 1504 may include a variety of components configured for various functions. In one configuration, device 1504, and in particular cellular baseband processor 1524 and / or application processor 1506, includes a component for determining to send a sidelink synchronization signal as a synchronization source. The apparatus includes a component for selecting to send at least one of a first side link synchronization signal associated with a first RAT or a second side link synchronization signal associated with a second RAT. The apparatus also includes a component for receiving a side link synchronization signal from the first RAT and a side link synchronization signal from the second RAT from one or more sources. The component may be a component 199 of the apparatus 1504 configured to perform the functions recorded by the component. As described above, the apparatus 1504 may include a TX processor 316, an RX processor 370, and a controller / processor 375. Therefore, in one configuration, the component may be a TX processor 316, an RX processor 370, and / or a controller / processor 375 configured to perform the functions recorded by the component.

[0120] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely an illustration of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart may be rearranged based on design preferences. In addition, some blocks may be combined or omitted. The attached method claims provide the elements of the various blocks in a sample order, but are not limited to the specific order or hierarchy provided.

[0121] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not limited to the various aspects described herein, but should be given the full scope consistent with the language claims. Unless otherwise specified, reference to an element in the singular form does not mean "one and only one", but "one or more". Terms such as "if", "when ..." and "at ..." do not mean an immediate time relationship or reaction. That is, these phrases, such as "when ...", do not mean an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that if the conditions are met, the action will occur, but no specific or immediate time limit is required for the occurrence of the action. The wording "exemplary" is used herein to mean "used as an example, instance or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or having advantages over other aspects. Unless otherwise specifically stated, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple A, multiple B, or multiple C. Specifically, combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may contain one or more members of A, B, or C. A set should be interpreted as a set of elements, wherein the number of elements is one or more. Thus, for a set of X, X will include one or more elements. If the first device receives data from the second device or sends data to the second device, data may be directly received / sent between the first device and the second device, or indirectly received / sent between the first device and the second device through a collection of devices. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are known or will be known later to a person of ordinary skill in the art are expressly incorporated herein by reference and are covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. Words such as "module", "mechanism", "element", "device" cannot replace the word "component". Therefore, no claim element will be understood as a functional component unless the element is explicitly stated using the phrase "component for..."

[0122] As used herein, the phrase "based on" should not be interpreted as referring to a closed set of information, one or more conditions, one or more factors, etc. In other words, the phrase "based on A" (where "A" can be information, a condition, a factor, etc.) should be interpreted as "based at least on A" unless specifically stated differently.

[0123] The following aspects are merely illustrative and may be combined with other aspects or teachings described herein, but are not limiting.

[0124] Aspect 1: A method for wireless communication at a UE, the method comprising: detecting a first sidelink synchronization signal from a first RAT and a second sidelink synchronization signal from a second RAT; determining a priority between synchronization sources associated with the first RAT and the second RAT; and sending data using timing based on the determination of the priority between the first RAT and the second RAT.

[0125] Aspect 2 is a method according to aspect 1, the method further comprising: the priority of the first RAT is higher than the priority of the second RAT.

[0126] Aspect 3 is a method according to any one of aspects 1 and 2, the method further comprising: the priority of the first RAT is preconfigured or configurable.

[0127] Aspect 4 is a method according to any one of Aspects 1 to 3, and the method also includes: the timing of the first RAT is used based at least on the first side link synchronization signal of the first RAT derived from the synchronization source with a higher priority than the current synchronization source, wherein the current synchronization source is not a synchronization reference UE.

[0128] Aspect 5 is a method according to any one of Aspects 1 to 4, the method further comprising: the timing of the first RAT is used at least based on the synchronization reference UE being associated with the second RAT, wherein the signal strength of the first sidelink synchronization signal is greater than the signal strength of the sidelink SSB received from the synchronization reference UE associated with the second RAT by a first threshold.

[0129] Aspect 6 is a method according to any one of aspects 1 to 5, the method further comprising: the first threshold is preconfigured or configurable.

[0130] Aspect 7 is a method according to any one of Aspects 1 to 6, the method also including: wherein the timing of the first RAT is used at least based on the association of the synchronization reference UE with the second RAT, wherein the second side link synchronization signal of the synchronization reference UE is derived from the synchronization source having a priority similar to or less than the priority of the first side link synchronization signal of the synchronization reference UE associated with the first RAT.

[0131] Aspect 8 is a method according to any one of aspects 1 to 7, the method further comprising: determining to send a sidelink synchronization signal as the synchronization source in response to detecting the first sidelink synchronization signal from the first RAT.

[0132] Aspect 9 is a method according to any one of Aspects 1 to 8, the method further comprising: determining to send at least one of the first side link synchronization signal or the second side link synchronization signal.

[0133] Aspect 10 is a method according to any one of aspects 1 to 9, the method further comprising: the first sidelink synchronization signal is sent.

[0134] Aspect 11 is a method according to any one of Aspects 1 to 10, and the method also includes: the first side link synchronization signal and the second side link synchronization signal are based on at least one of the following: the RSRP of the first side link synchronization signal is less than a threshold, the timing of the second side link synchronization signal is not synchronized with the timing of the first side link synchronization signal, the previous timing of the UE is not synchronized with the timing of the first side link synchronization signal, or the UE is the synchronization source for other UEs.

[0135] Aspect 12 is an apparatus for wireless communication at a target UE, the apparatus comprising at least one processor coupled to a memory and at least one transceiver, the at least one processor being configured to implement any one of aspects 1 to 11.

[0136] Aspect 13 is an apparatus for wireless communication at a target UE, the apparatus comprising means for implementing any one of aspects 1 to 11.

[0137] Aspect 14 is a computer-readable medium storing computer-executable code, wherein the code, when executed by a processor, causes the processor to implement any one of aspects 1 to 11.

[0138] Aspect 15 is a method for performing wireless communication at a UE, the method comprising: determining to send a sidelink synchronization signal as a synchronization source; and selecting to send at least one of a first sidelink synchronization signal associated with a first RAT or a second sidelink synchronization signal associated with a second RAT.

[0139] Aspect 16 is a method according to aspect 15, the method further comprising: the first sidelink synchronization signal associated with the first RAT is selected for transmission in response to the first sidelink synchronization signal and the second sidelink synchronization signal operating on the same frequency band.

[0140] Aspect 17 is a method according to any one of Aspects 15 and 16, and the method also includes: the selection of the first side link synchronization signal or the second side link synchronization signal is based on the priority of the synchronization source, and the first side link synchronization signal and the second side link synchronization signal are derived from the synchronization source.

[0141] Aspect 18 is a method according to any one of Aspects 15 to 17, the method further comprising: the first side link synchronization signal is selected for transmission in response to the first side link synchronization signal source having a higher timing priority than the second side link synchronization signal source.

[0142] Aspect 19 is a method according to any one of Aspects 15 to 18, the method further comprising: the second side link synchronization signal is selected for transmission in response to the second side link synchronization signal having a higher timing priority than the first side link synchronization signal.

[0143] Aspect 20 is a method according to any one of aspects 15 to 19, the method further comprising: receiving a third sidelink synchronization signal from the first RAT and a fourth sidelink synchronization signal from the second RAT from one or more sources.

[0144] Aspect 21 is a method according to any one of aspects 15 to 20, the method further comprising: the source of the second RAT is GNSS, and the source of the first RAT is from a synchronization reference UE.

[0145] Aspect 22 is a method according to any one of Aspects 15 to 21, the method further comprising: timing information derived from the second side link synchronization signal associated with the second RAT is selected for transmission in response to the source of the side link synchronization signal from the second RAT having a higher priority.

[0146] Aspect 23 is a method according to any one of Aspects 15 to 22, the method further comprising: timing information derived from the first sidelink synchronization signal associated with the first RAT is selected for transmission in response to a source of the sidelink synchronization signal from the first RAT having a higher priority.

[0147] Aspect 24 is a method according to any one of Aspects 15 to 23, the method also including: the second sidelink synchronization signal associated with the second RAT is selected for transmission in response to an estimate of the number of UEs capable of communicating with the second RAT being higher than a threshold.

[0148] Aspect 25 is an apparatus for wireless communication at a target UE, the apparatus comprising at least one processor coupled to a memory and at least one transceiver, the at least one processor being configured to implement any one of aspects 15 to 24.

[0149] Aspect 26 is an apparatus for wireless communication at a target UE, the apparatus comprising means for implementing any one of aspects 15 to 24.

[0150] Aspect 27 is a computer-readable medium storing computer-executable code, wherein the code, when executed by a processor, causes the processor to implement any one of aspects 15 to 24.

Claims

1. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: detecting a first sidelink synchronization signal from a first radio access technology (RAT) and a second sidelink synchronization signal from a second RAT; determining a priority between synchronization sources associated with the first RAT and the second RAT; as well as Data is transmitted using timing based on the determination of the priority between the first RAT and the second RAT.

2. The device according to claim 1, further comprising: A transceiver is coupled to the at least one processor. 3 . The apparatus of claim 1 , wherein the priority of the first RAT is higher than the priority of the second RAT. The apparatus of claim 1 , wherein the priority of the first RAT is preconfigured or configurable.

5. The apparatus of claim 1 , wherein the timing of the first RAT is used based on at least the first sidelink synchronization signal of the first RAT derived from the synchronization source having a higher priority than a current synchronization source, wherein the current synchronization source is not a synchronization reference UE.

6. The apparatus of claim 5 , wherein the timing of the first RAT is used based at least on the synchronization reference UE being associated with the second RAT, wherein a signal strength of the first sidelink synchronization signal is greater than a signal strength of a sidelink synchronization signal block (SSB) received from the synchronization reference UE associated with the second RAT by a first threshold. The apparatus according to claim 6 , wherein the first threshold is preconfigured or configurable.

8. An apparatus according to claim 6, wherein the timing of the first RAT is used based at least on the association of the synchronization reference UE with the second RAT, wherein the second sidelink synchronization signal of the synchronization reference UE is derived from the synchronization source having a priority similar to or less than a priority of the first sidelink synchronization signal of the synchronization reference UE associated with the first RAT.

9. The apparatus of claim 1 , wherein the at least one processor is further configured to: A transmit sidelink synchronization signal is determined as the synchronization source in response to detecting the first sidelink synchronization signal from the first RAT.

10. The apparatus of claim 9, wherein the at least one processor is further configured to: Determine to send at least one of the first sidelink synchronization signal or the second sidelink synchronization signal.

11. The apparatus of claim 10, wherein the first sidelink synchronization signal is transmitted.

12. The apparatus of claim 10, wherein the first sidelink synchronization signal and the second sidelink synchronization signal are based on at least one of: a received signal reference power (RSRP) of the first sidelink synchronization signal is less than a threshold, the timing of the second sidelink synchronization signal is not synchronized with the timing of the first sidelink synchronization signal, The previous timing of the UE is not synchronized with the timing of the first sidelink synchronization signal, or The UE is the synchronization source for other UEs.

13. A method of wireless communication at a user equipment (UE), the method comprising: detecting a first sidelink synchronization signal from a first radio access technology (RAT) and a second sidelink synchronization signal from a second RAT; determining a priority between synchronization sources associated with the first RAT and the second RAT; as well as Data is transmitted using timing based on the determination of the priority between the first RAT and the second RAT.

14. The method of claim 13, wherein the timing of the first RAT is used based on at least the first sidelink synchronization signal of the first RAT derived from the synchronization source having a higher priority than a current synchronization source, wherein the current synchronization source is not a synchronization reference UE.

15. The method according to claim 13, further comprising: A transmit sidelink synchronization signal is determined as the synchronization source in response to detecting the first sidelink synchronization signal from the first RAT.

16. The method according to claim 15, further comprising: Determine to send at least one of the first sidelink synchronization signal or the second sidelink synchronization signal.

17. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: Determining to send a side link synchronization signal as a synchronization source; as well as Selecting to transmit at least one of a first sidelink synchronization signal associated with a first radio access technology (RAT) or a second sidelink synchronization signal associated with a second RAT.

18. The apparatus according to claim 17, further comprising: A transceiver is coupled to the at least one processor.

19. The apparatus of claim 17, wherein the first sidelink synchronization signal associated with the first RAT is selected for transmission in response to the first sidelink synchronization signal and the second sidelink synchronization signal operating on a same frequency band.

20. The apparatus of claim 17, wherein selection of the first sidelink synchronization signal or the second sidelink synchronization signal is based on a priority of the synchronization source from which the first sidelink synchronization signal and the second sidelink synchronization signal are derived.

21. The apparatus of claim 20, wherein the first sidelink synchronization signal is selected for transmission in response to the first sidelink synchronization signal source having a higher timing priority than the second sidelink synchronization signal source.

22. The apparatus of claim 20, wherein the second sidelink synchronization signal is selected for transmission in response to the second sidelink synchronization signal having a higher timing priority than the first sidelink synchronization signal.

23. The apparatus of claim 17, wherein the at least one processor is further configured to: A third sidelink synchronization signal from the first RAT and a fourth sidelink synchronization signal from the second RAT are received from one or more sources.

24. The apparatus of claim 23, wherein the source of the second RAT is GNSS and the source of the first RAT is from a synchronization reference UE.

25. The apparatus of claim 23, wherein timing information derived from the second sidelink synchronization signal associated with the second RAT is selected for transmission in response to a source of the sidelink synchronization signal from the second RAT having a higher priority.

26. The apparatus of claim 23, wherein timing information derived from the first sidelink synchronization signal associated with the first RAT is selected for transmission in response to a source of the sidelink synchronization signal from the first RAT having a higher priority.

27. The apparatus of claim 23, wherein the second sidelink synchronization signal associated with the second RAT is selected for transmission in response to an estimate of a number of UEs capable of communicating with the second RAT being above a threshold.

28. A method of wireless communication at a user equipment (UE), the method comprising: Determining to send a side link synchronization signal as a synchronization source; as well as Selecting to transmit at least one of a first sidelink synchronization signal associated with a first radio access technology (RAT) or a second sidelink synchronization signal associated with a second RAT.

29. The method of claim 28, wherein the first sidelink synchronization signal associated with the first RAT is selected for transmission in response to the first sidelink synchronization signal and the second sidelink synchronization signal operating on a same frequency band.

30. The method of claim 28, further comprising: A third sidelink synchronization signal from the first RAT and a fourth sidelink synchronization signal from the second RAT are received from one or more sources.

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