Independent sidelink communication over unlicensed bands

Abstract

Wireless communications systems and methods related to independent sidelink communications are provided. A first user equipment (UE) determines system parameter information to initiate a sidelink communication. The first UE transmits the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period. The first UE communicates sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period that is different from the first time period based on the system parameter information.

Description

TECHNICAL FIELD

[0001] The present application relates to wireless communication systems, and more specifically, to independent sidelink communications in a shared radio frequency band shared by multiple network operating entities (e.g., in a shared spectrum or unlicensed spectrum). BACKGROUND

[0002] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems can be capable of supporting communication for multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless multiple-access communications system can include a number of base stations (BSs), each simultaneously supporting communications for multiple communication devices, which can be otherwise known as user equipment (UE).

[0003] To meet the growing demand for expanded mobile broadband connectivity, wireless communication technologies are advancing from the long-term evolution (LTE) technology to a next generation new radio (NR) technology, which can be referred to as 5th Generation (5G). For example, NR is designed to provide a lower latency, a higher bandwidth or a higher throughput, and a higher reliability than LTE. NR is designed to operate over a range of spectrum bands (e.g., from low-frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands). NR is also designed to operate across different spectrum types (from licensed spectrum to unlicensed and shared spectrum). Spectrum sharing enables operators to opportunistically aggregate spectrum to dynamically support high-bandwidth services. Spectrum sharing can extend the benefits of NR technologies to operating entities that can not have access to licensed spectrum.

[0004] In a wireless communication network, a BS can communicate with UEs in the uplink and downlink directions. Sidelink was introduced in LTE to allow a UE to transmit data to another UE without tunneling through a BS and / or associated core network. LTE sidelink technology has been extended to provide device-to-device (D2D) communications, vehicle-to-anything (V2X) communications, and / or cellular vehicle-to-anything (C-V2X) communications. Similarly, NR can be extended to support sidelink communications for D2D, V2X, and / or C-V2X over dedicated spectrum, licensed spectrum, and / or unlicensed spectrum. SUMMARY

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

[0006] For example, in one aspect of the disclosure, a method of wireless communication includes determining, by a first UE, system parameter information to initiate sidelink communication; transmitting, by the first UE, the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period; and communicating, by the first UE, sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0007] In one additional aspect of the disclosure, a first UE includes a processor configured to determine system parameter information to initiate sidelink communication; and a transceiver configured to transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period, and communicate sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0008] In one additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon, wherein the program code includes code for causing a first UE to determine system parameter information to initiate sidelink communication; code for causing the first UE to transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period; and code for causing the first UE to communicate sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0009] In one additional aspect of the disclosure, a first UE includes means for determining system parameter information to initiate sidelink communication; means for transmitting the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period; and means for communicating sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0010] Other aspects, features, and embodiments of the application will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments of the application in conjunction with the accompanying figures. While features of the present application can be discussed relative to certain embodiments and figures below, all embodiments of the application can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments can be discussed as having certain advantageous features, one or more of these features can also be used in accordance with the various embodiments of the application discussed herein. Similarly, while exemplary embodiments can be discussed herein as devices, systems, or methods, it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 A wireless communication network is shown in accordance with some aspects of the disclosure.

[0012] Figure 2 A wireless communication network providing sidelink communications is shown in accordance with some aspects of the disclosure.

[0013] Figure 3 A sidelink communications scheme is shown in accordance with some aspects of the disclosure.

[0014] Figure 4 is a simplified block diagram of an exemplary frame structure of a sidelink master information block in accordance with some aspects of the disclosure.

[0015] Figure 5 is a block diagram of an exemplary non-anchor user equipment (UE) in accordance with some aspects of the disclosure.

[0016] Figure 6 is a block diagram of an exemplary anchor UE in accordance with some aspects of the disclosure.

[0017] Figure 7 is a flow diagram of an anchor node discovery procedure in accordance with some aspects of the disclosure.

[0018] Figure 8 is a flow diagram of a sidelink communications procedure in accordance with some aspects of the disclosure.

[0019] Figure 9 is a flow diagram of a sidelink system information broadcast procedure in accordance with some aspects of the disclosure.

[0020] Figure 10 is a flow diagram of a sidelink communications procedure in accordance with some aspects of the disclosure. DETAILED DESCRIPTION

[0021] The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein can be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts.

[0022] This disclosure relates generally to wireless communication systems, also referred to as wireless communication networks. In various embodiments, the techniques and apparatuses can be used for wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, LTE networks, Global System for Mobile Communications (GSM) networks, 5thGeneration (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” can be used interchangeably.

[0023] An OFDMA network can implement a radio technology such as evolved UTRA (E- UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM, etc. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS). In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from the organization named “3rd Generation Partnership Project” (3GPP) and cdma2000 is described in documents from a consortium named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project to improve the UMTS mobile phone standard. The 3GPP can define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is related to aspects of shared access to wireless spectrum between networks employing some new and different wireless access technologies or radio air interfaces, wireless technologies evolving from LTE, 4G, 5G, NR, and beyond.

[0024] 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that can be implemented using a unified, OFDM- based, air interface. Toward these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. 5G NR will be capable of scaling to deliver extreme mobile broadband and ultra-low latency 2 access to mission critical communications, including public safety applications, that require ultra-reliable, low-latency connectivity. 2 5G NR can be implemented to use optimized OFDM-based waveforms with scalable numerology, a common, flexible framework to efficiently multiplex services and features with dynamic, low-latency time

[0025] 5G NR can be implemented to use optimized OFDM-based waveforms with scalable numerology, a common, flexible framework to efficiently multiplex services and features with dynamic, low-latency time

[0026] The scalable numerology of 5G NR facilitates scalable TTIs for diverse latency and quality of service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with UL / downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communication in unlicensed or contention-based shared spectrum, can be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet current traffic demands.

[0027] Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein can be embodied in a wide variety of forms, and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary skill in the art should appreciate that an aspect disclosed herein can be implemented independently of any other aspects and that two or more aspects can be combined in various ways. For example, an apparatus can be implemented or a method can be practiced using any number of the aspects set forth herein. In addition, such an apparatus can be implemented or such a method can be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method can be implemented as part of a system, device, apparatus, and / or as part of instructions for execution on a processor or computer. Furthermore, an aspect can comprise at least one of the enumerated elements.

[0028] Sidelink refers to communication between user equipment (UE) devices without tunneling through a base station (BS) and / or core network. Sidelink communication can be transmitted on a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH). The PSCCH and PSSCH are analogous to a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) in downlink (DL) communication between a BS and a UE. For example, the PSCCH can carry sidelink control information (SCI) and the PSSCH can carry sidelink data (e.g., user data). Each PSCCH is associated with a corresponding PSSCH, where the SCI in the PSCCH can carry reservation and / or scheduling information for sidelink data transmission in the associated PSSCH. Use cases for sidelink communication can include V2X, enhanced mobile broadband (eMBB), industrial IoT (IIoT), and / or NR-lite.

[0029] As used herein, the term “sidelink UE” can refer to a user equipment device that performs device-to-device communication with another user equipment device or other type of communication without relying on any tunneling through a BS (e.g., gNB) and / or associated core network. As used herein, the term “sidelink transmitting UE” can refer to a user equipment device that performs sidelink transmitting operations. As used herein, the term “sidelink receiving UE” can refer to a user equipment device that performs sidelink receiving operations. As used herein, the terms “anchor UE” or “sidelink anchor UE” refer to a sidelink UE that is designated as an anchor node with independent sidelink configuration that can autonomously (e.g., independent of any cell and / or associated core network) initiate sidelink operations, and the terms are interchangeable without departing from the scope of the present disclosure.

[0030] Deployment of NR over unlicensed spectrum is referred to as NR-unlicensed (NR-U). Some studies have been conducted for NR-U deployment over 5 gigahertz (GHz) unlicensed bands. The Federal Communications Commission (FCC) and the European Telecommunications Standards Institute (ETSI) are working to regulate 6 GHz as a new unlicensed band for wireless communications. The addition of the 6 GHz band allows hundreds of megahertz (MHz) of bandwidth (BW) to be available for unlicensed band communications. In addition, NR-U can also be deployed over the 2.4 GHz unlicensed band that is currently shared by various radio access technologies (RATs), such as IEEE 802.11 wireless local area network (WLAN) or WiFi and / or licensed assisted access (LAA). Sidelink can benefit from utilizing the additional bandwidth available in unlicensed spectrum. However, channel access in certain unlicensed spectrum can be regulated by the relevant authorities. For example, the regulations in the 2.4 GHz band allow a node to transmit without performing LBT when the node applies frequency hopping to the transmission and meets a transmission sequence or on / off pattern with a maximum transmission duration of about 5 ms and a minimum silence or gap duration of about 5 ms between transmissions.

[0031] For sidelink over licensed spectrum, NR supports two modes of radio resource allocation (RRA), mode 1 RRA and mode 2 RRA. Mode 1 RRA supports network-controlled RRA that can be used for in-coverage sidelink communications. For example, a serving BS (e.g., gNB) can determine radio resources on behalf of a sidelink UE and send an indication of the radio resources to the sidelink UE. In some aspects, the serving BS utilizes downlink control information (DCI) to grant a sidelink transmission. However, for this mode, there is significant base station involvement and it is only operable when the sidelink UE is within the coverage area of the serving BS. Mode 2 RRA supports autonomous RRA that can be used for out-of-coverage sidelink UEs or partially-covered sidelink UEs. For example, an out-of-coverage sidelink UE or partially-covered UE can be preconfigured with a pool of sidelink resources and can select radio resources from the preconfigured pool of sidelink resources for sidelink communications. For this mode, a V2X system can be possible to operate independent of a serving BS. However, mode 2 RRA relies on sidelink settings across different environments (e.g., vehicles). For example, this mode would require that the sidelink settings be uniform such that each sidelink UE (e.g., vehicle) can communicate with each other. This would rely on device user vendors (e.g., different automobile manufacturers) to coordinate and implement a common sidelink setting. This can place a significant burden on device user vendors to develop and implement a uniform sidelink setting such that all NR-U sidelink user equipment devices can communicate via respective sidelink connections. As such, there is a desire to deploy NR-U sidelink systems as standalone systems.

[0032] The present application describes mechanisms to deploy a standalone sidelink communication with other sidelink UEs by configuring a subset of sidelink UEs as anchor nodes within a network for the sidelink UEs to initiate sidelink operations autonomously in a synchronous sidelink system operating over a shared radio frequency band (e.g., in a shared radio spectrum or unlicensed spectrum) of any cell and / or associated core network. In various embodiments, the standalone sidelink system of the subject technology is not intended to replace and / or supplant a serving BS function to coordinate sidelink operations. The sidelink UEs can be configured to operate similar to user equipment devices operating in mode 2 RRA, however, the sidelink UEs of the subject technology can operate with a standalone sidelink design that has several advantages over the mode 2 RRA mechanisms, which will be described in greater detail herein.

[0033] In some embodiments of the subject technology, a first user equipment (UE) includes a processor configured to determine system parameter information to initiate sidelink communications. The first UE includes a transceiver configured to transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period. The transceiver can communicate sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0034] In some embodiments, the first UE provides timing synchronization and control signaling to other sidelink UEs including the second UE. In some aspects, the processor is further configured to generate a synchronization signal to facilitate synchronization between the first UE and the second UE, and allocate the synchronization signal to a first portion of a sidelink synchronization signal block (S-SSB), where the synchronization signal includes a primary synchronization signal followed by a secondary synchronization signal. In some aspects, the processor is further configured to determine a sidelink master information block (SL-MIB) including at least a portion of the system parameter information, and allocate the SL-MIB to a second portion of the S-SSB, where the second portion follows the first portion. In some aspects, the one or more first sub-bands include a physical sidelink broadcast channel (PSBCH) in a first portion of the first time period, and the transceiver configured to transmit the system parameter information is further configured to transmit the S-SSB on the PSBCH. In some aspects, the processor configured to determine the SL-MIB is further configured to: determine an initial transmission radio resource pool configuration, where the initial transmission radio resource pool configuration includes one or more of a plurality of sub-channels, a plurality of modulation symbols, or a set of time domain slots within the first time period during which remaining minimum system information (RMSI) is transmitted; and allocate the initial transmission radio resource pool configuration to one or more locations in the SL-MIB. In some aspects, the processor is further configured to provide an indication within the SL-MIB indicating whether RMSI is present for processing by the second UE.

[0035] In some embodiments, the first UE provides additional system parameters in the form of RMSI. In some aspects, the RMSI includes additional system parameter information that is different from at least a portion of the system parameter information in the SL-MIB. In some aspects, the transceiver is further configured to transmit, with the second UE, the RMSI in the second sub-band during the first time period. In some aspects, the second sub-band includes a plurality of physical sidelink control channels (e.g., PSCCHs) multiplexed on at least one of time or frequency in a first portion of the first time period and a plurality of physical sidelink shared channels (e.g., PSSCHs) multiplexed on at least one of time or frequency in a second portion of the first time period, the second portion being different from the first portion, the transceiver configured to transmit the RMSI is further configured to transmit the RMSI in one or more of the plurality of PSCCHs, and the transceiver configured to transmit the sidelink data is further configured to transmit the sidelink data in at least one of the plurality of PSSCHs. In some aspects, the transceiver is further configured to transmit, in the RMSI, an indication of an in-cell guard band for the second UE to use to recover the one or more sets of resource blocks.

[0036] In some embodiments, the first UE provides a bandwidth allocation within the additional system parameters. In some aspects, the transceiver is further configured to transmit, in the RMSI, a sidelink BWP configuration. In some aspects, the processor configured to determine the SL-MIB is further configured to determine a plurality of predefined sets of initial sidelink bandwidth part (BWP) configurations and provide, within one or more locations in the SL-MIB, an indication indicating at least one of the plurality of predefined sets of initial sidelink BWP configurations. In some aspects, the at least one of the plurality of predefined sets of initial sidelink BWP configurations includes a starting resource block (RB) and a number of RBs, and the starting RB corresponds to a first location in a resource grid and the S-SSB occupies at least a second location in the resource grid, where the first location and the second location are separated by a resource block level offset. In some aspects, the sidelink BWP configuration is different from at least one initial sidelink BWP configuration in the at least one of the plurality of predefined sets of initial sidelink BWP configurations included in the SL-MIB.

[0037] In some embodiments, the first UE provides resource allocation information to the sidelink UE. In some aspects, the transceiver is further configured to transmit, in the RMSI, a transmission resource pool configuration indicating which radio resources are allocated to the first UE for the first UE to transmit the sidelink communication. In some aspects, the transceiver is further configured to transmit, in the RMSI, a reception resource pool configuration indicating which radio resources are allocated to the first UE for the first UE to receive the sidelink communication. In some aspects, the transceiver is further configured to transmit, in the RMSI, a transmission mode of the S-SSB to enable the second UE to rate match the S-SSB. In some aspects, the transceiver is further configured to transmit, in the RMSI, a transmission mode of the RMSI to enable the second UE to monitor the RMSI.

[0038] In some embodiments, the first UE provides an announcement of its anchor node configuration and monitors other anchor nodes to maintain local consistency of system parameters. In some aspects, the transceiver is further configured to transmit an output announcement message to announce that the first UE is configured to be an anchor node that autonomously sets system parameters for sidelink operations of other UEs including the second UE. In some aspects, the processor is further configured to monitor a physical sidelink discovery channel (PSDCH) for an input announcement message indicating a presence of another UE configured to be an anchor node. In some aspects, when the input announcement message indicating the presence of the other UE configured to be an anchor node is not detected by the first UE, the transceiver configured to transmit the output announcement message is further configured to transmit one or more discovery messages including the output announcement message in the PSDCH. In some aspects, the processor is further configured to determine that one or more predetermined factors are satisfied to qualify the first UE as an anchor node and adopt one or more system parameters of the other UE configured to be an anchor node when the input announcement message indicating the presence of the other UE configured to be an anchor node is detected. In some aspects, the processor configured to adopt the one or more system parameters is further configured to receive the one or more system parameters broadcast from the other UE to the first UE on the PSDCH. In some aspects, the processor is further configured to update local system parameters with the one or more system parameters adopted from the other UE to generate updated system parameter information, and the transceiver is further configured to transmit the updated system parameter information during a third time period subsequent to the first time period. In some aspects, the transceiver configured to transmit the updated system parameter information is further configured to transmit the updated system parameter information on a PSBCH. In some aspects, the transceiver configured to transmit the updated system parameter information is further configured to transmit the updated system parameter information to one or more other UEs having a sidelink connection with the first UE in one or more of a unicast transmission or a groupcast transmission. In some aspects, the processor configured to adopt the one or more system parameters is further configured to determine whether the other UE is an in-coverage UE based on a location of the other UE relative to a coverage area of a cell, and determine that the other UE has a higher priority than the first UE for determining system parameters between the first UE and the other UE when the other UE is in-coverage based on the other UE being within the coverage area of the cell.

[0039] In some aspects, the transceiver configured to communicate the sidelink data is further configured to receive, from the second UE, a sidelink message during the second time period in the second sub-band in at least one of the plurality of PSCCHs or in at least one of the plurality of PSSCHs based on the reception resource pool configuration, the sidelink message causing the first UE to establish the sidelink connection with the second UE.

[0040] In some aspects, the sidelink system can be a synchronous system, where the sidelink receiving UEs are synchronized in time, e.g., based on synchronization signaling received from a sidelink anchoring UE. In some aspects, the shared radio frequency band can be divided into multiple sub-channels or frequency sub-bands. In some aspects, the sidelink receiving UEs can be configured with one or more radio resource pools in the shared radio frequency band. The sidelink receiving UEs can utilize a wideband receiver to monitor or sense in the respective radio resource pools, and can utilize a narrowband transmitter for frequency sub-band based channel access based on allocated radio resources from the respective radio resource pools. Additionally, channel access can be in time units of sidelink communication frames.

[0041] Aspects of the disclosure can provide several benefits. For example, the independent sidelink system provides flexibility (independent of any serving BS and / or associated core network) by facilitating setup of system information for sidelink operation. The independent sidelink system can maintain local consistency of the sidelink system across multiple and / or different anchoring nodes by implementing a mechanism of adoption of system parameters across anchoring nodes. In this regard, system parameters can be kept consistent across different anchoring nodes for coordinated deployment of user equipment devices (e.g., IIoT). Otherwise, if there are multiple anchoring nodes with different system parameters in a neighborhood (or network), sidelink system operation becomes increasingly burdensome. Use of the independent sidelink communication mechanism can allow the sidelink system to be compatible with regulations in the 2.4 GHz unlicensed band, and thus can allow deployment of the sidelink system on the 2.4 GHz unlicensed band. The independent sidelink communication mechanism can deploy channel busy ratio (CBR) and / or channel access occupancy ratio (CR) computation to provide a better or more accurate view of channel status and / or sidelink UE channel utilization within the sidelink system, and thus the sidelink anchoring UEs can be able to more efficiently configure the sidelink UEs, resource pools, and / or frequency hopping patterns for the sidelink UEs to reduce intra-system collisions. While the disclosure is described in the context of deploying an independent sidelink communication on the 2.4 GHz unlicensed band, the disclosed embodiments can be applied to any suitable shared or unlicensed band.

[0042] Figure 1A wireless communication network 100 according to some aspects of the present disclosure is shown. The network 100 can be a 5G network. The network 100 includes a plurality of base stations (BSs) 105 (individually labeled as 105a, 105b, 105c, 105d, 105e, and 105f) and other network entities. A BS 105 can be a station that communicates with UEs 115 and can also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each BS 105 can provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of a BS 105 and / or a BS subsystem serving the coverage area, depending on the context in which the term is used.

[0043] BSs 105 can provide communication coverage for a macro cell, a small cell, such as a pico cell or a femto cell, and / or other types of cells. A macro cell generally covers a relatively large geographic area (e.g., 5 km in radius) and can allow unrestricted access by UEs with service subscriptions with the network provider. A small cell such as a pico cell can cover a relatively small geographic area and can allow restricted access by UEs such as UEs in an association with the small cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, etc.). A BS for a macro cell can be referred to as a macro BS. A BS for a small cell can be referred to as a small cell BS, a pico BS, a femto BS, or a home BS. In Figure 1 In the example shown, BSs 105d and 105e can be regular macro BSs, while BSs 105a- 105c can be macro BSs with one of three-dimensional (3D), full-dimensional (FD), or massive MIMO capabilities. BSs 105a-105c can utilize their higher dimension MIMO capabilities to utilize 3D beamforming in elevation and azimuth to improve coverage and capacity. BS 105f can be a small cell BS, which can be a home node or a portable access point. A BS 105 can support one or multiple (e.g., two, three, four, etc.) cells.

[0044] The network 100 can support synchronous or asynchronous operation. For synchronous operation, the BSs can have similar frame timing, and transmissions from different BSs can be approximately aligned in time. For asynchronous operation, the BSs can have different frame timing, and transmissions from different BSs can not be aligned in time.

[0045] UEs 115 are dispersed throughout the wireless network 100, and each UE 115 can be stationary or mobile. A UE 115 can also be referred to as a terminal, a mobile station, a subscriber unit, a station, etc. A UE 115 can be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, etc. In one aspect, a UE 115 can be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE can be a device that does not include a UICC. In some aspects, UEs 115 that do not include UICCs can also be referred to as IoT devices or Internet of Everything (IoE) devices. UEs 115a-115d are examples of mobile smart phone-type devices accessing network 100 A UE 115 can also be a machine specifically configured to perform communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. UEs 115e-115h are examples of various machines configured to access the network 100 for communication. UEs 115i- 115k are examples of vehicles equipped with wireless communication devices configured to access network 100 for communication. A UE 115 can be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In Figure 1 In general, a lightning bolt (e.g., a communication link) indicates a wireless transmission between a UE 115 and a serving BS 105, which is a BS 105 that is designated to serve the UE 115 on the downlink (DL) and / or uplink (UL) as well as a desired transmission between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UEs 115.

[0046] In operation, BSs 105a- 105c can employ 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity, to serve UEs 115a and 115b. Macro BS 105d can perform backhaul communications with BSs 105a-105c as well as small cell BS 105f. Macro BS 105d can also transmit a multicast service which is received and processed by UEs 115c and 115d. Such a multicast service can include mobile television or stream video, or can include other services for providing community information, such as weather emergencies or alerts (such as Amber alerts or gray alerts).

[0047] The BSs 105 can also communicate with a core network. The core network can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which can be an example of a gNB or an access node controller (ANC)) can interface with the core network

[0048] The network 100 can also support mission critical communications for mission critical devices, such as the UE 115e, which can be an example of a drone. Redundant communication links with the UE 115e can include links from the macro BSs 105d and 105e, as well as the small cell BS 105f. Other machine type devices, such as the UE 115f (e.g., a thermometer), the UE 115g (e.g., a smart meter), and UE 115h (e.g., a wearable device) can communicate through the network 100 directly with BSs, such as the small cell BS 105f and the macro BS 105e, or through the UE 115g using a device-to-device (D2D) communication link, in a multi-step configuration. The network 100 can also provide additional network efficiency through dynamic, low-latency TDD / FDD communications, such as V2V, V2X, C-V2X communications between UEs 115i, 115j, or 115k and other UEs 115, and / or vehicle-to-infrastructure (V2I) communications between UEs 115i, 115j, or 115k and BSs 105.

[0049] In some implementations, the network 100 employs an OFDM-based waveform for communications. An OFDM-based system can partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier can be modulated with data. In some instances, the subcarrier spacing can be fixed, and the total number of subcarriers K can be dependent on the system BW. The system BW can also be partitioned into subbands. In other instances, the subcarrier spacing and / or the duration of TTIs can be scalable.

[0050] In some aspects, the BS 105 can allocate or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RBs)) for downlink (DL) and uplink (UL) transmissions in the network 100. DL refers to the transmission direction from a BS 105 to a UE 115, whereas UL refers to the transmission direction from a UE 115 to a BS 105. The communication can be in the form of radio frames. A radio frame can be divided into multiple subframes or slots, for example, about 10. Each slot can be further divided into mini-slots. In FDD mode, UL and DL simultaneous transmissions can occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame can be used for DL transmissions, and another subset of the subframes (e.g., UL subframes) in the radio frame can be used for UL transmissions.

[0051] The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe can have pre-defined regions for transmission of reference signals, control information, and data. Reference signals are predetermined signals that facilitate communication between the BS 105 and the UE 115. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones can span across an operating BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, the BS 105 can transmit cell specific reference signals (CRS) and / or channel state information reference signals (CSI-RS) to enable a UE 115 to estimate a DL channel. Similarly, a UE 115 can transmit sounding reference signals (SRS) to enable a BS 105 to estimate a UL channel. Control information can include resource assignments and protocol controls. Data can include protocol data and / or operational data. In some aspects, the BS 105 and the UE 115 can communicate using self-contained subframes. A self-contained subframe can include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe can include a longer duration for DL communication than for UL communication. A UL-centric subframe can include a longer duration for UL communication than for DL communication.

[0052] In some aspects, the network 100 can be an NR network deployed over a licensed spectrum. The BSs 105 can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) in the network 100 to facilitate synchronization. The BSs 105 can broadcast system information associated with the network 100 (e.g., including a master information block (MIB), remaining minimum system information (e.g., RMSI) and other system information (OSI)) to facilitate initial network access. In some instances, the BSs 105 can broadcast the PSS, the SSS, and / or the MIB in the form of synchronization signal blocks (SSBs) over a physical broadcast channel (PBCH) and can broadcast the RMSI and / or the OSI over a physical downlink shared channel (e.g., a PDSCH).

[0053] In some aspects, a UE 115 attempting to access the network 100 can perform an initial cell search by detecting a PSS from a BS 105. The PSS can enable synchronization of periodic timing and can indicate a physical layer identification value. The UE 115 can then receive an SSS. The SSS can enable radio frame synchronization and can provide a cell identification value that can be combined with the physical layer identification value to identify a cell. The PSS and the SSS can be in a center portion of a carrier or any suitable frequency within the carrier.

[0054] After receiving the PSS and the SSS, the UE 115 can receive a MIB. The MIB can include system information for initial network access and scheduling information for RMSI and / or OSI. After decoding the MIB, the UE 115 can receive the RMSI and / or the OSI. The RMSI and / or the OSI can include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource sets (CORESETs) for physical downlink control channel (PDCCH) monitoring, physical UL control channel (PUCCH), physical UL shared channel (PUSCH), power control, and SRS.

[0055] After obtaining the MIB, the RMSI, and / or the OSI, the UE 115 can perform a random access procedure to establish a connection with the BS 105. In some examples, the random access procedure can be a four-step random access procedure. For example, the UE 115 can transmit a random access preamble and the BS 105 can respond with a random access response. The random access response (RAR) can include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, a UL grant, a temporary cell radio network temporary identifier (C-RNTI), and / or a backoff indicator. After receiving the random access response, the UE 115 can transmit a connection request to the BS 105 and the BS 105 can respond with a connection response. The connection response can indicate a contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response can be referred to as message 1 (MSG1), message 2 (MSG2), message 3 (MSG3), and message 4 (MSG4), respectively. In some examples, the random access procedure can be a two-step random access procedure, where the UE 115 can transmit a random access preamble and a connection request in a single transmission and the BS 105 can respond by transmitting a random access response and a connection response in a single transmission.

[0056] After establishing a connection, the UE 115 and the BS 105 can enter a normal operation stage, where operational data can be exchanged. For example, the BS 105 can schedule the UE 115 for UL and / or DL communications. The BS 105 can transmit UL and / or DL scheduling grants to the UE 115 via PDCCH. The scheduling grants can be transmitted in the form of DL control information (DCI). The BS 105 can transmit DL communication signals (e.g., carrying data) to the UE 115 in accordance with a DL scheduling grant via PDSCH. The UE 115 can transmit UL communication signals to the BS 105 in accordance with a UL scheduling grant via PUSCH and / or PUCCH.

[0057] In some aspects, the BSs 105 can employ HARQ techniques to communicate with the UEs 115 to improve communication reliability, for example, to provide URLLC services. The BSs 105 can schedule the UEs 115 for PDSCH communication by transmitting a DL grant in a PDCCH. The BSs 105 can transmit a DL data packet to the UEs 115 in accordance with the scheduling in the PDSCH. The DL data packet can be transmitted in the form of a DL transport block (TB). If the UE 115 successfully receives the DL data packet, the UE 115 can transmit a HARQ ACK to the BS 105. Conversely, if the UE 115 fails to successfully receive the DL transmission, the UE 115 can transmit a HARQ NACK to the BS 105. Upon receiving the HARQ NACK from the UE 115, the BS 105 can retransmit the DL data packet to the UE 115. The retransmission can include the same coded version of the DL data as the initial transmission. Alternatively, the retransmission can include a different coded version of the DL data than the initial transmission. The UE 115 can apply soft combining to combine the coded data received from the initial transmission and the retransmission for decoding. The BSs 105 and the UEs 115 can also apply HARQ to UL communication using substantially similar mechanisms as for DL HARQ.

[0058] In some aspects, the network 100 can operate over a system BW or a component carrier (CC) BW. The network 100 can partition the system BW into multiple BWPs (e.g., portions). The BSs 105 can dynamically assign the UEs 115 to operate over a certain BWP (e.g., a certain portion of the system BW). The assigned BWP can be referred to as the active BWP. The UEs 115 can monitor the active BWP for signaling information from the BSs 105. The BSs 105 can schedule the UEs 115 for UL or DL communication in the active BWP. In some aspects, the BSs 105 can assign a pair of BWPs within a CC to a UE 115 for UL and DL communication. For example, the pair of BWPs can include one BWP for UL communication and one BWP for DL communication.

[0059] In some aspects, the network 100 can operate over a shared channel, which can include a shared frequency band and / or an unlicensed frequency band. For example, the network 100 can be an NR-U network that operates over an unlicensed frequency band. In such an aspect, the BSs 105 and the UEs 115 can be operated by multiple network operating entities. To avoid collisions, the BSs 105 and the UEs 115 can employ a listen before talk (LBT) procedure to monitor for transmission opportunities (TXOPs) in the shared channel. A TXOP can also be referred to as a COT. For example, a transmitting node (e.g., a BS 105 or a UE 115) can perform an LBT before transmitting in the channel. When the LBT passes, the transmitting node can proceed with the transmission. When the LBT fails, the transmitting node can refrain from transmitting in the channel.

[0060] The LBT can be based on energy detection (ED) or signal detection. For an ED-based LBT, the LBT passes when a measured signal energy from the channel is below a threshold. Conversely, the LBT fails when the measured signal energy from the channel exceeds the threshold. For a signal detection-based LBT, the LBT passes when no channel reservation signal (e.g., a predetermined preamble signal) is detected in the channel. Additionally, the LBT can be in multiple modes. The LBT mode can be, for example, a category 4 (CAT4) LBT, a category 2 (CAT2) LBT, or a category 1 (CAT1) LBT. CAT1 LBT is referred to as a no-LBT mode, in which no LBT is performed before transmission. CAT2 LBT refers to an LBT without a random backoff period. For example, a transmitting mode can determine a channel measurement in a time interval and determine whether the channel is available based on a comparison of the channel measurement with an ED threshold. CAT4 LBT refers to an LBT with a random backoff and a variable contention window (CW). For example, a transmitting node can draw a random number and backoff for a duration based on the drawn random number in a certain time unit.

[0061] In some aspects, the network 100 can support sidelink communications between UEs 115 over a shared radio frequency band (e.g., in a shared spectrum or an unlicensed spectrum). In some aspects, the UEs 115 can communicate with each other over a 2.4 GHz unlicensed band, which can be shared by multiple network operating entities using various radio access technologies (RATs), such as NR-U, WiFi, and / or licensed assisted access (LAA), as shown in Figure 2

[0062] ​In some aspects, network 100 can support independent sidelink communication between UEs 115 on a shared radio frequency band, wherein a subset of UEs 115 is adapted to act as anchor nodes (e.g., sidelink anchored UEs) and autonomously initiates sidelink operations for UEs 115. In this aspect, the sidelink anchored UE is autonomous and can perform sidelink operations independently of any cell (e.g., BS 105).

[0063] In order to target Figure 1 For the sake of brevity, the remaining portion of the description refers to the UE 115 configured as the anchor node as the "anchor UE," and the remaining UE 115 configured to receive system information from the anchor UE as the "side link receiving UE." In some examples, UE 115j may represent the anchor UE, and UE 115k may represent the side link receiving UE; however, in appropriate implementations, the remaining UE 115 may act as both the anchor UE and the side link receiving UE independently, without departing from the scope of this disclosure.

[0064] Anchored UEs can autonomously determine system parameter information (e.g., independent of any cell in coverage and / or associated core network). Across different anchored UEs (e.g., UE 115j, 115d), in some embodiments the system parameter information may be substantially the same to facilitate coordinated deployment (e.g., IIoT), or in other embodiments the system information may differ at least partially for deployments of different applications.

[0065] An anchored UE (e.g., 115j) can transmit synchronization signals (e.g., including PSS and SSS) in network 100 to initiate sidelink operation in network 100 and facilitate synchronization with a sidelink receiving UE (e.g., 115k) that decides to join the sidelink operation. In some instances, each of the PSS and SSS includes an encoded synchronization preamble sequence.

[0066] The anchored UE may broadcast system parameter information associated with network 100 (e.g., including a sidelink master information block (e.g., SL-MIB) and / or residual minimum system information (e.g., RMSI)) to facilitate sidelink communication with the anchored UE. In some instances, the anchored UE may broadcast PSS, SSS, and / or SL-MIB in the form of a sidelink synchronization signal block (e.g., S-SSB) on a physical sidelink broadcast channel (e.g., PSBCH). The S-SSB may be transmitted periodically at predefined time intervals. The anchored UE may transmit RMSI on a physical sidelink shared channel (e.g., PSSCH). The PSS and SSS may be located in the center portion of the carrier or at any suitable frequency within the carrier.

[0067] In some aspects, a UE 115 can autonomously decide whether it should configure itself as an anchor node and announce itself as an anchor node on a sidelink broadcast channel (e.g., PSBCH). In some aspects, an anchor UE (e.g., 115j) can broadcast system parameter information on a sidelink broadcast channel to proximate UEs 115 (e.g., 115i, 115k) so that each sidelink receiving UE can monitor and recover control and data messages on sidelink control and / or data channels, respectively. For example, a sidelink receiving UE attempting to communicate with a proximate sidelink UE can perform an initial anchor node search by monitoring the PSBCH and detecting a PSS from an anchor UE on the PSBCH. The PSS can enable synchronization of periodic timing and can indicate a physical layer identification value. The sidelink receiving UE can then receive an SSS from the anchor UE on the PSBCH. The SSS can enable synchronization of radio frames and can provide a UE identification value that can be combined with the physical layer identification value to identify the anchor UE.

[0068] After receiving the PSS and SSS, the sidelink receiving UE can receive a SL-MIB on the PSBCH. The SL-MIB can include system information for initial network access and a pointer to scheduling information for RMSI. The SL-MIB can also include one or more predefined sets of initial BWP configurations and / or initial transmission resource pool configurations. In some aspects, the S-SSB is transmitted within a bandwidth defined in the initial BWP configuration.

[0069] After decoding the SL-MIB, the sidelink receiving UE can recover RMSI based on the pointer. In other instances, the anchor UE can allocate a bit location to include an indication of whether the SL-MIB includes RMSI. For example, the SL-MIB indication can indicate that RMSI is not present and the sidelink receiving UE can not attempt to recover RMSI.

[0070] The RMSI can include additional system parameters. In some aspects, the RMSI includes intra-cell guard band information for an NR-U system to be used by another sidelink receiving UE (e.g., 115i) to derive a set of resource blocks. In various embodiments, the RMSI includes transmission resource pool configuration information and / or reception resource pool configuration information. The transmission resource pool configuration information can define a subset of available subframes and resource blocks for sidelink transmission by the anchor UE. The reception resource pool configuration information can define a subset of available subframes and resource blocks for sidelink reception by the anchor UE. In some aspects, the RMSI includes transmission mode information, such as S-SSB transmission mode for rate matching purposes and / or RMSI transmission mode for monitoring purposes.

[0071] After obtaining the SL-MIB and / or the RMSI, the sidelink receiving UE can perform a sidelink communication procedure to establish a sidelink connection of the anchor UE. For example, the anchor UE can allocate radio resources to the sidelink receiving UE for sidelink communication via a transmission resource pool configuration included in the RMSI. The anchor UE can transmit additional system parameters, such as scheduling information, to the sidelink receiving UE on a PSCCH. The additional system parameters can be transmitted in the form of sidelink control information (SCI).

[0072] After establishing the sidelink connection, the sidelink receiving UE and the anchor UE can enter a normal sidelink operation phase, in which the roles of the sidelink receiving UE and the anchor UE can be exchanged. The anchor UE can transmit sidelink communication signals (e.g., carrying sidelink data) to the sidelink receiving UE on a PSSCH according to a transmission resource pool configuration. The sidelink receiving UE can transmit sidelink communication signals to the anchor UE on a PSSCH and / or a PSCCH according to a reception resource pool configuration.

[0073] In some aspects, the anchor UE can use HARQ techniques to communicate with the sidelink receiving UE to improve communication reliability. For example, the sidelink receiving UE can transmit feedback messages (e.g., HARQ ACK / NACK) to the anchor UE on a physical sidelink feedback channel (PSFCH).

[0074] Figure 2 An example of a wireless communication network 200 that provides sidelink communication in accordance with embodiments of the present disclosure is shown. The network 200 can correspond to a portion of the network 100. For simplicity of discussion, Figure 2 Two BSs 205 (shown as 205a and 205b) and six UEs 215 (shown as 215al, 215a2, 215a3, 215a4, 215bl, and 215b2) are shown, but it will be recognized that embodiments of the present disclosure can scale to any suitable number of UEs 215 (e.g., about 2, 3, 4, 5, 7, or more) and / or BSs 205 (e.g., about 1, 3, or more). The BSs 205 and UEs 215 can be similar to the BSs 105 and UEs 115, respectively. The BSs 205 and UEs 215 can share the same radio frequency band for communication. In some instances, the radio frequency band can be a 2.4 GHz unlicensed band, a 5 GHz unlicensed band, or a 6 GHz unlicensed band. In general, the shared radio frequency band can be at any suitable frequency.

[0075] BS 205a and UEs 215al-215a4 can be operated by a first network operating entity. BS 205b and UEs 215bl-215b2 can be operated by a second network operating entity. In some aspects, the first network operating entity can utilize a same RAT as the second network operating entity. For example, BSs 205a and UEs 215al-215a4 of the first network operating entity and BS 205b and UEs 215bl-215b2 of the second network operating entity are NR-U devices. In some other aspects, the first network operating entity can utilize a different RAT than the second network operating entity. For example, BSs 205a and UEs 215al-215a4 of the first network operating entity can utilize NR-U technology, while BS 205b and UEs 215bl-215b2 of the second network operating entity can utilize WiFi or LAA technology.

[0076] In network 200, some of UEs 215al-215a4 can communicate with each other in peer-to-peer communications. For example, UE 215al can communicate with UE 215a2 on a sidelink 252, UE 215a3 can communicate with UE 215a4 on another sidelink 251, and UE 215bl can communicate with UE 215b2 on yet another sidelink 254. Sidelinks 251, 252, and 254 are unicast bidirectional links. Some of UEs 215 can also communicate with BS 205a or BS 205b in the UL and / or DL direction via a communication link 253. For example, UEs 215al, 215a3, and 215a4 are within a coverage area 210 of BS 205a and thus can communicate with BS 205a. UE 215a2 is outside of coverage area 210 and thus can not communicate directly with BS 205a. In some instances, UE 215al can operate as a relay for UE 215a2 to reach BS 205a. Similarly, UE 215bl is within a coverage area 212 of BS 205b and thus can communicate with BS 205b and can operate as a relay for UE 215b2 to reach BS 205b. In some aspects, some of UEs 215 are associated with vehicles (e.g., similar to UEs 115i-k) and the communications on sidelinks 251, 252, and 254 can be C-V2X communications. C-V2X communications can refer to communications between a vehicle and any other wireless communication device in a cellular network.

[0077] As discussed above, NR supports a standalone sidelink communication mechanism. In some aspects, a first user equipment (UE) includes a processor configured to determine system parameter information to initiate sidelink communication, and a transceiver configured to transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period, and communicate sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0078] In NR and NR-U systems, a synchronization subframe can be triggered by discovery and communication modes, and thus, there can not be a "standalone" broadcast / synchronization procedure. However, the subject technology provides a sidelink anchor UE to communicate a synchronization subframe to other sidelink receiving UEs by initiating a standalone broadcast / synchronization procedure. For example, UE 215a2 can act as a sidelink anchor UE and UE 215al can act as a sidelink receiving UE, where UE 215a2 transmits system parameter information including a timing synchronization signal on a sidelink broadcast channel (e.g., PSBCH) so that UE 215al can receive and recover resource configuration and timing information to facilitate sidelink communication with UE 215a2. For purposes of simplicity of illustration and discussion, the remaining description will be discussed with respect to UE 215al (e.g., a sidelink receiving UE) and UE 215a2 (e.g., a sidelink anchor UE). Figure 2

[0079] Sidelink discovery by other sidelink transmitting UEs (such as other anchor nodes) can be facilitated by the use of a transmission channel known as the transmission sidelink discovery channel (SL-DCH), and its physical counterpart (i.e., the physical sidelink discovery channel (e.g., PSDCH)). In some aspects, a sidelink transmitting UE can transmit one or more announcement messages that are generated using a physical layer transport block with zero medium access control overhead. For example, UE 215a2 can broadcast an announcement message on the PSDCH to announce its status as an anchor node.

[0080] ​In various embodiments, a sidelink anchoring UE can utilize a sidelink discovery procedure to: 1) advertise its presence as an anchoring UE to potentially proximate sidelink UEs by sending a message containing its application information or other useful information fields (e.g., GSP coordinates, time, etc.), and 2) monitor for the presence of other proximate sidelink UEs by detecting and decoding corresponding discovery messages, and respond to sidelink transmitting UEs with similar discovery messages. In some instances, the discovery messages can include information about the type of discovery being performed and / or the type of content being provided by the sidelink transmitting UE (e.g., an advertisement, a query). For example, UE 215a2 can broadcast a discovery message on the PSDCH, where the discovery message includes an indication that the discovery message belongs to an advertisement of its anchoring node status.

[0081] In some aspects, depending on the implementation, UE 215a2 can perform sensing operations on one or more of a discovery channel, such as the PSDCH, or a sidelink broadcast channel, such as the PSBCH. If UE 215a2 does not detect an existing anchoring UE on the discovery channel, UE 215a2 can configure itself as an anchoring UE and broadcast an advertisement indicating itself as an anchoring UE. If UE 215a2 detects an existing anchoring UE, UE 215a2 can determine whether it is needed to be an anchoring node within wireless communication network 200.

[0082] In some instances, there can be multiple anchor nodes in the wireless communication network 200. A sidelink anchor UE, such as UE 215a2, can perform sensing operations on the sidelink discovery channel. In some aspects, when two anchor UEs sense each other, one anchor UE can adopt the system parameters of the other anchor UE to maintain local consistency of system parameters in the wireless communication network 200. In some instances, an in-coverage anchor UE (e.g., a sidelink anchor UE within the coverage area of an existing cell) can have priority in determining system parameters. For example, UE 215al can be configured as an anchor node, such that UE 215a2 senses UE 215al as an anchor node and determines that it is an in-coverage anchor UE based on its location being within the coverage area of BS 205a. In some embodiments, an anchor UE that adopts new system parameters can broadcast its updated system parameters to other sidelink receiving UEs on the sidelink broadcast channel. For example, UE 215a2 can adopt the system parameters of UE 215al, and in turn, UE 215a2 can broadcast its updated system parameters to other neighboring sidelink receiving UEs (e.g., 215a3, 215a4, 215b2). In other embodiments, a sidelink anchor UE can actively communicate with other sidelink receiving UEs via unicast or groupcast transmissions to indicate changes in system parameters.

[0083] For in-coverage sidelink operation, where both the transmitting UE and the sidelink receiving UE exist in the same coverage area of a BS, time synchronization is provided by the BS, and it can not be necessary for UE 215a2 to become an anchor UE to initiate sidelink operation by performing sidelink-specific synchronization. However, there can be several scenarios where it can be necessary for UE 215a2 to become an anchor UE to perform sidelink-specific operations: (i) in multi-cell coverage, where the sidelink receiving UE exists in a different asynchronous cell relative to the sidelink transmitting UE; (ii) in partial coverage, where the sidelink receiving UE is out of coverage, and can need to acquire synchronization from an in-coverage sidelink transmitting UE; and / or (iii) out of coverage, where both sidelink UEs are outside the coverage of a cell, and the sidelink transmitting UE decides to act as a reference synchronization source (referred to as an anchor UE).

[0084] In some aspects, UE 215a2 can evaluate other factors, including but not limited to: a transmission priority level of UE 215a2, an application type of UE 215a2, a number of sidelink UE participants within a synchronization range of UE 215a2, and / or a network congestion level within a sidelink coverage area of UE 215a2.

[0085] In some aspects, UE 215a2 can determine that it can be an anchor node if it determines, through quantitative and / or qualitative analysis, that one or more of the above factors are satisfied. In this aspect, UE 215a2 can adopt the system parameters of the detected anchor UE (e.g., UE 215al) and any associated timing parameters. In some aspects, the detected anchor UE can propagate its system parameters to UE 215a2. This would allow multiple anchor UEs to coexist in network 200 with the anchor UEs having corresponding system parameters to maintain local consistency of sidelink system operation.

[0086] In various embodiments, UE 215a2 as an anchor node can autonomously form mode-specific pools of time and frequency radio resources. UE 215a2 can allocate specific resources from these pools of radio resources for control and data for other sidelink receiving UEs. In some instances, UE 215a2 can form a pool of radio resources for discovery communications (hereinafter referred to as a “sidelink discovery resource pool”). In other instances, UE 215a2 can form pools of radio resources for control and data communications, such as a control channel resource pool (hereinafter referred to as a “PSCCH resource pool”) and a data channel resource pool (hereinafter referred to as a “PSSCH resource pool”). In various embodiments, UE 215a2 can provide a transmission resource pool configuration including configuration information for a discovery resource pool configuration and a control / data communication resource pool configuration.

[0087] Sidelink receiving UEs (e.g., UE 215al) can monitor multiple resources to listen for discovery announcements transmitted by anchor UEs (e.g., UE 215a2) to minimize and / or avoid sidelink UE interference. In some embodiments, UE 215a2 can autonomously determine a sidelink discovery resource pool containing certain subframes that carry sidelink control signals, while the remaining portion of the subframes can carry sidelink data. In this aspect, sidelink receiving UEs can be allocated time and frequency resources for transmitting discovery messages to other sidelink receiving UEs from the sidelink discovery resource pool and / or monitoring for discovery messages from the sidelink discovery resource pool. In selecting resources from the pool, UE 215a2 can attempt to avoid allocation of common time / frequency resources to different sidelink receiving UEs. In some embodiments, UE 215a2 can select time and frequency resources from the pool using randomization parameters to minimize (or at least reduce) the number of resource allocation collisions.

[0088] In some embodiments, the discovery resource pool configuration can indicate which RBs are available for discovery transmissions, whether broadcast synchronization signals can be triggered in response to discovery messages, whether such broadcast synchronization signals are to be transmitted once or periodically, and / or an indication of how sidelink radio resources are allocated to different discovery transmissions, e.g., autonomously by a sidelink anchor UE or a sidelink transmitting UE. The discovery resource pool configuration can include additional parameter information indicating which resources a sidelink receiving UE can monitor for identifying potential discovery announcement messages, as well as other parameter information for tuning channel estimation and channel decoding operations at the sidelink receiving UE. In operation of the discovery mode, discovery messages can follow transmission of broadcast synchronization signals according to the time / frequency resource configuration defined in the discovery resource pool configuration.

[0089] In standalone sidelink communications, the radio resource pool for PSCCH and PSSCH can be separate. In some instances, the PSSCH radio resource pool can start at a fixed time offset relative to the PSCCH radio resource pool. In some embodiments, a UE 215a2 that is an anchor node can autonomously select time / frequency resources from the PSCCH radio resource pool based on a randomization parameter to allocate resources for a sidelink control channel, PSCCH. The UE 215a2 can also autonomously select time / frequency resources from the PSSCH radio resource pool based on a UE-specific subframe bitmap to allocate resources for a sidelink shared channel, PSSCH. In various embodiments, sidelink communications between sidelink UEs can be facilitated through the use of a transport channel, i.e., a sidelink shared channel (SL-SCH), and its physical counterpart, i.e., PSSCH.

[0090] Timing synchronization and system information acquisition by a sidelink receiving UE, e.g., 215al, can be facilitated by a sidelink broadcast transport channel, SL-BCH, and its physical counterpart, PSBCH. These channels can be used to broadcast a set of preambles and system parameter information in the vicinity of the UE 215a2. A set of primary and secondary preambles, PSS and SSS, can be used for synchronization by a sidelink receiving UE, e.g., 215al. As described herein, a sidelink master information block, SL-MIB, can carry sidelink system parameter information. Through acquisition of the PSS / SSS preambles, a proximate sidelink receiving UE, e.g., UE 215al, can acquire time synchronization with a sidelink anchor UE, e.g., UE 215a2, and obtain its physical identity. The SL-MIB can include system information for initial network access and scheduling information for RMSI. The SL-MIB can also include one or more predefined sets of initial BWP configurations and / or initial transmission resource pool configurations. In some aspects, the S-SSB is transmitted within a bandwidth defined in the initial BWP configuration.

[0091] After decoding the SL-MIB, the sidelink receiving UE (e.g., UE 215al) can recover the RMSI based on a pointer included in a change purpose bit field of the SL-MIB. The RMSI can include additional system parameters. In some aspects, the RMSI includes intra-cell guard band information for the NR-U system to be used by the sidelink receiving UE (e.g., UE 215al) to derive a set of resource blocks. In various embodiments, the RMSI includes transmission resource pool configuration information and / or reception resource pool configuration information. The transmission resource pool configuration information can define a subset of available subframes and resource blocks for sidelink transmission from the sidelink anchor UE (e.g., 215a2). The reception resource pool configuration information can define a subset of available subframes and resource blocks for sidelink reception by the sidelink anchor UE. In some aspects, the RMSI includes transmission mode information, such as S-SSB transmission mode for rate matching purposes and / or RMSI transmission mode for monitoring purposes.

[0092] In some aspects, the RMSI can include an active BWP configuration to assign an active sidelink BWP to the sidelink receiving UE. The sidelink anchor UE can use the active sidelink BWP configuration included in the RMSI to dynamically assign the sidelink receiving UE to operate on a particular sidelink BWP (e.g., a particular portion of the system BW). The sidelink receiving UE can monitor the active sidelink BWP for signaling information from the sidelink anchor UE. In some embodiments, the active sidelink BWP configuration can correspond to the initial sidelink BWP configuration, or in other embodiments, the active sidelink BWP configuration can be different than the initial sidelink BWP configuration. In some aspects, the active sidelink BWP configuration and the initial sidelink BWP configuration can include separate numerologies. In this aspect, the UE 215a2 can schedule the UE 215al for sidelink communications in the active sidelink BWP.

[0093] Figure 3 A sidelink communication scheme 300 is shown in accordance with some aspects of the disclosure. The scheme 300 can be employed by UEs (such as the UEs 115 and / or 215) in a network (such as the networks 100 and / or 200). In particular, a sidelink UE can employ the scheme 300 to communicate a sidelink over a shared radio frequency band (e.g., in a shared spectrum or unlicensed spectrum). As discussed in Figure 2 The shared radio frequency band can be shared by multiple RATs, as discussed in Figure 3 In the scheme 300, the x-axis represents time in some arbitrary units, and the y-axis represents frequency in some arbitrary units.

[0094] In scheme 300, the shared radio frequency band 301 is divided into multiple sub-channels or frequency sub-bands 302 (shown as 302) in terms of frequency. S0 302 S1 302 S2 The frequency band 301 is divided into multiple sidelink frames 304 (shown as 304a, 304b, 304c, 304d, ...) for sidelink communication. The frequency band 301 can be at any suitable frequency (e.g., at approximately 2.4 GHz, 5 GHz, or 6 GHz). The frequency band 301 can have any suitable band width (BW) and can be divided into any suitable number of frequency subbands 302. The number of frequency subbands 302 can depend on the sidelink communication BW requirements. The frequency band 301 can be at any suitable frequency. In some aspects, the frequency band 301 is an unlicensed 2.4 GHz band and can have a bandwidth of approximately 80 MHz divided into approximately fifteen 5 MHz frequency subbands 302.

[0095] Sidelink UEs (e.g., UE 115 and / or 215) may be equipped with a wideband receiver and a narrowband transmitter. For example, a UE may utilize a narrowband transmitter to access frequency subband 302. S2 This allows for sidelink transmission using frame structure 304. Frame structure 304 is repeated in each frequency subband 302. In some instances, such as... Figure 3 As shown, frequency gaps or guard bands may exist between adjacent frequency sub-bands 302 to mitigate interference between adjacent frequency bands. Therefore, multiple sidelink data can be transmitted simultaneously in different frequency sub-bands 302 (e.g., FDM). Frame structure 304 also repeats in time. For example, frame structure 304 can be used to repeat frequency sub-bands 302. S2 Time is divided into multiple frames.

[0096] Frame structure 304 includes sidelink resources 306 in each frequency subband 302. Figure 305 indicates the type of sidelink channel within sidelink resource 306. Sidelink resource 306 can have a structure substantially similar to NR sidelink resources. For example, sidelink resource 306 may include multiple subcarriers or RBs (in frequency) and multiple symbols (in time). In some instances, sidelink resource 306 may have a duration between approximately one millisecond (ms) and approximately 20 ms. Each sidelink resource 306 may include PSCCH 310 and PSSCH 320. PSCCH 310 and PSSCH 320 may be multiplexed in time and / or frequency. Figure 3In the illustrated example of FIG. 3, for each sidelink resource 306, the PSCCH 310 is during the beginning symbol (e.g., about 1 symbol or about 2 symbols) of the sidelink resource 306 and occupies a portion of the corresponding frequency subband 302, and the PSSCH 320 occupies the remaining time-frequency resources in the sidelink resource 306. In some instances, the sidelink resource 306 can also include, for example, a physical sidelink feedback channel (PSFCH) during the ending symbol of the sidelink resource 306. Generally, the PSCCH 310, PSSCH 320, and / or PSFCH can be multiplexed in any suitable configuration within the sidelink resource 306.

[0097] As discussed above, the subject technology provides a sidelink UE configured as a sidelink anchor UE (e.g., 115j, 215a2) for configuring resource allocations for other sidelink receiving UEs. As such, the sidelink anchor UE can configure the sidelink receiving UEs with resource pool configurations indicating resources in the frequency band 301 and / or subbands 302 and / or timing information associated with the sidelink frame 304. For example, the sidelink anchor UE can provide resource allocation information to the sidelink receiving UEs. In some aspects, the sidelink anchor UE can transmit a transmission resource pool configuration in RMSI, where the transmission resource pool configuration indicates which radio resources are allocated to the sidelink anchor UE for the sidelink anchor UE to transmit sidelink communications. In some aspects, the sidelink anchor UE can transmit a reception resource pool configuration in RMSI, where the reception resource pool configuration indicates which radio resources are allocated to the sidelink anchor UE for the sidelink anchor UE to receive sidelink communications. In this aspect, the sidelink receiving UEs can receive and decode physical communication channels (e.g., PSCCH 310, PSSCH 320) from the sidelink anchor UE based on the transmission resource pool configuration, and encode and transmit PSCCH 310 and PSSCH 320 to the sidelink anchor UE based on the reception resource pool configuration.

[0098] In sidelink communications, in order for the sidelink receiving UEs to successfully decode the PSCCH 310 and PSSCH 320, information describing the specific resources allocated for transmission by the sidelink anchor UE and transmission configuration can be carried in sidelink control information, SCI. In this aspect, the control information for the sidelink communications can be transmitted in the form of a SCI message. The SCI message can be sent on the PSCCH 310, which carries information related to the transmission of data on the PSSCH 320.

[0099] The SCI can inform the sidelink receiving UE of the resource reservation interval, the frequency locations of the initial transmission and retransmissions, the time gap between the initial transmission and retransmissions, and the modulation and coding scheme (MCS) used to modulate the data transmitted on the PSSCH 320.

[0100] The SCI message can be populated based on the mode of radio resource allocation (e.g., mode 1 RRA or mode 2 RRA). For mode 1 RRA, the SCI can be populated using higher layer information carried by L3 control signaling (e.g., RRC, and L1 control signaling configured at a cell, such as BS 215). For mode 2 RRA, the SCI can be populated based on autonomous decisions taken by each sidelink anchoring UE. The structure of the SCI message can include a frequency hopping flag field, a resource block allocation and frequency hopping resource allocation field, a time resource pattern field, a MCS field, a timing advance field, and a group destination identifier field. The structure of the SCI message can include other additional fields as appropriate to support V2X control signaling. The frequency hopping flag field, and the resource block allocation and frequency hopping resource allocation field can provide information for the sidelink receiving UE to identify the RBs in which the data channel (e.g., PSSCH 320) exists. The sidelink anchoring UE can autonomously configure each of these two fields. The identified RBs can belong to a sidelink communication resource pool (e.g., PSSCH resource pool). The time resource pattern field can provide the time domain resource allocation for the data channel (e.g., PSSCH 320), and in particular, the potential subframes for PSSCH transmission. The MCS field can provide the MCS for the PSSCH 320, which can be autonomously selected by the sidelink anchoring UE. The timing advance field can provide the sidelink timing adjustment for mode 2 RRA or other applicable modes. The group destination identifier field can indicate the group of sidelink receiving UEs that can be interested in the transmitted message from the sidelink anchoring UE. This can be used by the sidelink receiving UEs to ignore messages destined to other groups of sidelink UEs.

[0101] In some aspects, the SCI message can be processed with transport channel coding to generate an SCI message transport block, which is then followed by physical channel coding to generate a corresponding PSCCH block. The PSCCH block is carried on the corresponding subframe resource unit for transmission. The sidelink receiving UEs can receive one or more resource units on the corresponding subframe to recover the control signaling information, and can extract the data channel allocation and transmission configuration.

[0102] The PSCCH 310 can be used to carry SCI 330. The PSSCH 320 can be used to carry sidelink data. Depending on the sidelink application, the sidelink data can be various forms and types. For example, when the sidelink application is a V2X application, the sidelink data can carry V2X data (e.g., vehicle location information, travel speed and / or direction, vehicle sensing measurements, etc.). Alternatively, when the sidelink application is an IIoT application, the sidelink data can carry IIoT data (e.g., sensor measurements, device measurements, temperature readings, etc.). The PSFCH can be used to carry feedback information, e.g., HARQ ACK / NACK for sidelink data received in the earlier sidelink data resource 306.

[0103] In some aspects, the scheme 300 is used for synchronization of sidelink communications. In other words, the sidelink UEs are synchronized in time and aligned in terms of symbol boundaries, sidelink resource boundaries (e.g., start time of the sidelink frame 304). The sidelink UEs can perform synchronization in a number of forms, e.g., based on a sidelink SSB received from a sidelink UE and / or a NR-U SSB received from a BS (e.g., the BS 105 and / or 205), when in coverage of the BS. In some aspects, the sidelink UEs can be preconfigured with the resource pool 308 in the frequency band 301, e.g., when configured in coverage of a serving BS according to a mode 1 RRA. The resource pool 308 can include a plurality of sidelink resources 306.

[0104] In the NR sidelink frame structure, the sidelink frames 304 in the resource pool 308 can be contiguous in time. A sidelink receiving UE (e.g., the UE 115 and / or 215) can include a reservation in the SCI 330 for a sidelink resource 306 in a subsequent sidelink frame 304. Accordingly, another sidelink UE (e.g., a UE in the same NR-U sidelink system) can perform SCI sensing in the resource pool 308 to determine whether the sidelink resource 306 is available or occupied. For example, if the sidelink UE detects SCI indicating a reservation for the sidelink 306, the sidelink UE can refrain from transmitting in the reserved sidelink resource 306. If the sidelink UE determines that there is no detected reservation for the sidelink resource 306, the sidelink UE can transmit in the sidelink resource 306. As such, the SCI sensing can help the UEs identify target frequency sub-bands 302 to reserve sidelink communications and avoid intra-system collisions with another sidelink UE in the NR-U sidelink system. In some aspects, the UEs can be configured with a sensing window for the SCI sensing or monitoring to reduce intra-system collisions.

[0105] In some aspects, frequency hopping can be used to configure the sidelink UE. In this case, the sidelink UE can hop from a frequency subband 302 in one sidelink frame 304 to another frequency subband 302 in another sidelink frame 304. Figure 3 In the example shown, during sidelink frame 304a, the sidelink UE is in frequency subband 302 S2 SCI 330 is transmitted in side link resource 306 to retain it in frequency subband 302. S1 The next side walkway resource 306 in the side walkway frame 304b. Similarly, during side walkway frame 304b, the side walkway UE is in frequency subband 302. S1 SCI 332 is transmitted in side link resource 306 to retain it in frequency subband 302. S1 The next side-bypass resource 306 in the side-bypass frame 304c. During side-bypass frame 304c, the side-bypass UE is in frequency subband 302. S1 SCI 334 is transmitted in side link resource 306 to retain it in frequency subband 302. S0 The next side-bypass resource 306 in the side-bypass frame 304d. During side-bypass frame 304d, the side-bypass UE is in frequency subband 302. S0 SCI 336 is transmitted in side link resource 306. SCI 336 may be retained in side link resource 306 in subsequent side link frames 304.

[0106] The SCI can also indicate scheduling information and / or identify the destination identifier (ID) for the target sidelink receiving UE used in the next sidelink resource 306. Therefore, the sidelink UE can monitor SCIs sent by other sidelink UEs. After detecting an SCI in sidelink resource 306, the sidelink UE can determine whether it is the target receiver based on the destination ID. If the sidelink UE is the target receiver, it can continue to receive and decode the sidelink data indicated by the SCI. In some aspects, multiple sidelink UEs can simultaneously transmit sidelink data in sidelink frame 304 in different frequency subbands (e.g., via FDM). For example, in sidelink frame 304b, a pair of sidelink UEs can use frequency subband 302. S2 The sidelink resource 306 in the middle is used to transmit sidelink data, while another pair of sidelink UEs can use frequency subband 302. S1 Sidelink resource 306 is used to transmit sidelink data.

[0107] Figure 4is a simplified block diagram of an exemplary frame structure 400 of a sidelink master information block according to some aspects of the present disclosure. The frame structure 400 includes a sidelink bandwidth field 402, an in-coverage indicator field 404, a time division duplex (TDD) configuration field 406, a reserved field 408, a frame number field 410, and a subframe number field 412. However, not all of the illustrated frame structure fields can be required, and one or more implementations can include additional frame structure fields not shown in the figure. Variations can be made to the arrangement and type of frame structure fields without departing from the scope of the claims set forth herein. Additional frame structure fields, different frame structure fields, or fewer frame structure fields can be provided.

[0108] As described herein, a sidelink master information block can carry system parameter information. The sidelink master information block can be analogous to the MIB in NR and NR-U systems. In NR or NR-U systems, the MIB can contain an 8-bit information field that configures CORESET 0 and Type 0 PDCCH monitoring. However, in sidelink communications, the sidelink master information block can not contain such bit field information corresponding to CORESET 0 and Type 0 PDCCH monitoring. In some embodiments, the SL-MIB in the S-SSB changes the use of the 8-bit information field to indicate the location of the RMSI. For example, the use of the reserved field 408 and / or multiple bits in the TDD configuration field 406 of the sidelink master information block can be changed by the sidelink anchor UE to an initial sidelink resource configuration field 414.

[0109] The sidelink master information block can be mapped to a reference subframe and / or time resource configuration at a particular frequency. As shown in Figure 4 The frame structure 400 of the sidelink master information block can include a 40-bit sequence, as shown in some instances. The sidelink bandwidth field 402 can provide a bandwidth mode (e.g., 5, 10, 15, 20 MHz), in some instances. The in-coverage indicator field 404 can inform sidelink receiving UEs of the coverage status (e.g., in-coverage, partial-coverage, out-of-coverage) of the sidelink anchor UE. The frame field 410 and the subframe field 412 can provide timing reference information on the frame and subframe time scales, respectively.

[0110] As described herein, a sidelink master information block can carry system parameter information. The sidelink master information block can be analogous to the MIB in NR and NR-U systems. In NR or NR-U systems, the MIB can contain an 8-bit information field that configures CORESET 0 and Type 0 PDCCH monitoring. However, in sidelink communications, the sidelink master information block can not contain such bit field information corresponding to CORESET 0 and Type 0 PDCCH monitoring. In some embodiments, the SL-MIB in the S-SSB changes the use of the 8-bit information field to indicate the location of the RMSI. For example, the use of the reserved field 408 and / or multiple bits in the TDD configuration field 406 of the sidelink master information block can be changed by the sidelink anchor UE to an initial sidelink resource configuration field 414. Figure 4As shown, the purpose of TDD configuration field 406 and reserved field 408 has been changed to initial sidelink configuration field 414. In some instances, initial sidelink configuration field 414 may include a pointer indicating the location of the RMSI for use by the sidelink receiving UE to recover the RMSI after locating the S-SSB. In some aspects, the sidelink anchored UE may allocate bit fields in initial sidelink resource configuration field 414 to indicate at least one of a plurality of predefined sets of initial sidelink BWP configurations. In some aspects, the sidelink master information block includes an initial transport radio resource pool configuration at one or more bit positions within initial sidelink configuration field 414. The initial transport radio resource pool configuration may include one or more of a plurality of subchannels, a plurality of modulation symbols, or time-domain time slots during which the RMSI is transmitted.

[0111] After decoding the sidelink master information block, the sidelink receiving UE can receive and recover the RMSI based on the pointer provided in the initial sidelink configuration field 414. In other instances, the anchoring UE can allocate bit positions in the initial sidelink configuration field 414 to include an indication of whether the sidelink master information block includes the RMSI. For example, the sidelink master information block indication could indicate that the RMSI is not present, and the sidelink receiving UE could choose not to attempt to detect the RMSI.

[0112] Figure 5 This is a block diagram of an exemplary non-anchored UE 500 based on some aspects of this disclosure. The non-anchored UE 500 can be... Figure 1 In the network 100 discussed above, UE 115 or Figure 2 The UE 215 discussed above. As shown, the non-anchored UE 500 may include a processor 502, a memory 504, a sidelink communication module 508, a transceiver 510 (including a modem subsystem 512 and a radio frequency (RF) unit 514), and one or more antennas 516. These components may communicate with each other directly or indirectly, for example via one or more buses.

[0113] Processor 502 may include a central processing unit (CPU), digital signal processor (DSP), application-specific integrated circuit (ASIC), controller, field-programmable gate array (FPGA) device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 502 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0114] The memory 504 can include cache memory (e.g., of the processor 502), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard disk drive, other forms of volatile and non-volatile memory, or a combination of different types of memory. In one aspect, the memory 504 includes a non-transitory computer-readable medium. The memory 504 can store or have recorded thereon, instructions 506. The instructions 506 can include instructions that, when executed by the processor 502, cause the processor 502 to perform the operations described herein with reference to the UEs 115 in connection with aspects of the present disclosure (e.g., aspects of the UEs 115, 215, and / or 600). The instructions 506 can also be referred to as program code. The program code can be for causing a wireless communication device to perform these operations, e.g., by causing one or more processors (such as the processor 502) to control or command the wireless communication device to perform these operations. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” can refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” can include a single computer-readable statement or many computer-readable statements. Figures 1-4

[0115] The sidelink communication module 508 can be implemented via hardware, software, or combinations thereof. For example, the sidelink communication module 508 can be implemented as a processor, circuit, and / or instructions 506 stored in the memory 504 and executed by the processor 502. In some instances, the sidelink communication module 508 can be integrated within the modem subsystem 512. For example, the sidelink communication module 508 can be implemented by a combination of software components (e.g., executed by a DSP or general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 512.

[0116] The sidelink communication module 508 can be used for various aspects of the present disclosure, for example, aspects of the UEs 115, 215, and / or 600. In some aspects, the sidelink communication module 508 is adapted to receive SSBs from a BS (e.g., the BS 105 and / or 205), receive SSBs from a sidelink anchoring UE (e.g., the UE 115, 215, and / or 600), perform synchronization based on the received SSBs, receive a sidelink configuration from the BS indicating a resource pool (e.g., the resource pool 308), a frequency hopping pattern, a sidelink communication frame structure (e.g., the frame structure 304), and / or perform sidelink communications in accordance with the received sidelink configuration. Figures 1-4

[0117] ​​As shown, transceiver 510 can include modem subsystem 512 and RF unit 514. Transceiver 510 can be configured to communicate bi-directionally with other devices, such as the BS 105. Modem subsystem 512 can be configured to modulate and / or encode data from memory 504 and / or sidelink communications module 508, according to a modulation and coding scheme (MCS), e.g., a low-density parity check (LDPC) coding scheme, a Turbo coding scheme, a convolutional coding scheme, a polar coding scheme, a digital beamforming scheme, etc. RF unit 514 can be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated / encoded data from modem subsystem 512 (on outbound transmissions) or for transmissions originating from another source such as a UE 115 or a BS 105. RF unit 514 can be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown together in transceiver 510, modem subsystem 512 and RF unit 514 can be separate devices coupled together at UE 115 so that UE 115 is capable of communicating with other devices.

[0118] RF unit 514 can provide the modulated and / or processed data, e.g., data packets (or, more generally, data messages that can contain one or more data packets and other information) to antenna 516 for transmission toward one or more other devices. RF unit 514 can process modulated / encoded data and generate a corresponding time-domain waveform using SC-FDMA modulation, for transmission via antenna 516. In other instances, RF unit 514 can utilize OFDM modulation to generate the time-domain waveform. Antenna 516 can also receive data messages transmitted from other devices. Antenna 516 can provide the received data messages for processing and / or demodulation at transceiver 510. Transceiver 510 can provide the modulated and encoded data (e.g., sidelink configuration, SCI, sidelink data, SCI reservation conflict information, synchronization signals, SSBs) to sidelink communications module 508 for processing. Antenna 516 can include multiple antennas of similar or different designs, to sustain multiple transmission links. RF unit 514 can configure antenna 516. In some aspects, RF unit 514 can include various RF components such as local oscillators (LOs), analog filters, and / or mixers. The LOs and mixers can be configured based on a particular channel central frequency. The analog filters can be configured to have a particular bandpass depending on the channel BW. The RF components can be configured to operate at various power modes (e.g., normal power mode, low power mode, power-off mode), and can be switched between different power modes depending on transmission and / or reception requirements at anchor UE 500.

[0119] In one aspect, the non-anchor UE 500 can include multiple transceivers 510 implementing different RATs (e.g., NR and LTE). In one aspect, the non-anchor UE 500 can include a single transceiver 510 implementing multiple RATs (e.g., NR and LTE). In one aspect, the transceiver 510 can include various components, where different combinations of components can implement different RATs.

[0120] In some aspects, the transceiver 510 can monitor a sidelink broadcast channel (e.g., PSBCH) or a sidelink discovery channel (e.g., PSDCH). For example, the non-anchor UE 500 can monitor any anchor UE and / or any sidelink transmitting UE (e.g., non-anchor node). In some aspects, the transceiver 510 can obtain one or more sidelink synchronization signal blocks on the sidelink broadcast channel. In some instances, the sidelink communication module 508, in conjunction with the processor 502, can recover a synchronization preamble sequence (e.g., PSS, SSS) from the sidelink synchronization signal block.

[0121] In some aspects, the sidelink communication module 508, in conjunction with the processor 502, can recover a sidelink master information block from the sidelink synchronization signal block. In some aspects, the sidelink communication module 508, in conjunction with the processor 502, can obtain an initial sidelink BWP configuration from the sidelink master information block. In some aspects, the sidelink communication module 508, in conjunction with the processor 502, can obtain an initial transmitting resource pool configuration from the sidelink master information block. In some instances, the processor 502 can determine whether RMSI is present within the sidelink master information block. If RMSI is present, the processor 502 can determine, from the initial transmitting resource pool configuration, radio resources over which the RMSI is transmitted.

[0122] In some aspects, the transceiver 510 can tune to a sub-band containing a PSCCH based on the RMSI radio resources. In some instances, the transceiver 510 can obtain RMSI on the PSCCH. In some aspects, the sidelink communication module 508, in conjunction with the processor 502, can recover a transmitting resource pool configuration and a receiving resource pool configuration from the RMSI. In this aspect, the transceiver 510 can tune to a sub-band containing a PSSCH based on the transmitting resource pool configuration. In various instances, the transceiver 510 can receive sidelink data on the PSSCH.

[0123] Figure 6 is a block diagram of an example anchor UE 600 according to some aspects of the present disclosure. The anchor UE 600 can be a UE 115 in the network 100 discussed above in Figure 1 or a base station 105 in the network 100 discussed above in Figure 2The UE 215 discussed above is an example. As shown, the anchored UE 600 may include a processor 602, a memory 604, a sidelink configuration module 608, a transceiver 610 (including a modem subsystem 612 and an RF unit 614), and one or more antennas 616. These components may communicate with each other directly or indirectly, for example, via one or more buses.

[0124] Processor 602 may have various features as a particular type of processor. For example, these may include a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. Processor 602 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0125] Memory 604 may include cache memory (e.g., cache memory of processor 602), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory devices, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or combinations of different types of memory. In some aspects, memory 604 includes a non-transitory computer-readable medium. Memory 604 may store instructions 606. Instructions 606 may include causing processor 602 to perform the operations described herein when executed by processor 602 (e.g., ...). Figures 1-4 Instructions (in aspects of 7 and 9). Instruction 606 can also be referred to as code, which should be interpreted broadly as including the instructions mentioned above. Figure 5 Any type of computer-readable statement discussed.

[0126] The sidelink configuration module 608 can be implemented via hardware, software, or a combination thereof. For example, the sidelink configuration module 608 can be implemented as a processor, circuitry, and / or instructions 606 stored in memory 604 and executed by processor 602. In some instances, the sidelink configuration module 608 can be integrated within the modem subsystem 612. For example, the sidelink configuration module 608 can be implemented by a combination of software components (e.g., executed by a DSP or general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 612.

[0127] The sidelink configuration module 608 can be used in various aspects of this disclosure, for example, Figures 1-4Aspects of the sidelink configuration module 608 can be the same as or similar to aspects of the sidelink configuration module 608 of FIGURE 6, the sidelink configuration module 604 of FIGURE 6, and / or aspects of the sidelink configuration module 708 of FIGURE 7 and 9. For example, the sidelink configuration module 608 is configured to transmit, to a sidelink receiving UE (e.g., UE 115, 215, and / or 500), a sidelink configuration indicating a sidelink resource pool, a sidelink communication parameter, a sidelink resource pool, and / or a frequency hopping pattern. The sidelink configuration can indicate time-frequency resources in the sidelink resource pool. For example, the configuration can indicate frequency band information (e.g., frequency band 301, PSCCH is in a control channel, PSCCH multiplexing configuration, PSSCH for frequency hopping base access), PSCCH to PSSCH mapping, and / or sidelink frame timing information. The sidelink communication parameter can include a frequency hopping pattern. In some aspects, the sidelink configuration module 608 is configured to transmit, to the UE, a CBR / CR table. The CBR / CR table can include an entry indicating allowable CRs for a transmitter-originated SCI at a given CBR and allowable CRs for a receiver-originated SCI to control intra-system collisions.

[0128] As shown, the transceiver 610 can include the modem subsystem 612 and the RF unit 614. The transceiver 610 can be configured to communicate bi-directionally with other devices, such as the UE 115 and / or 600 and / or another core network element. The modem subsystem 612 can be configured to modulate and / or encode data according to a MCS, e.g., a LDPC coding scheme, a Turbo coding scheme, a convolutional coding scheme, a polar coding scheme, a digital beamforming scheme, etc. The RF unit 614 can be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated / encoded data (e.g., PDCCH, PDSCH, SSB, sidelink configuration, sidelink resource pool configuration, SSB, frequency hopping pattern for sidelink communication) from the modem subsystem 612 (on outbound transmissions) or of transmissions originating from another source such as a UE 115 and / or UE 600. The RF unit 614 can be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown together in the transceiver 610, the modem subsystem 612 and / or the RF unit 614 can be separate devices coupled together at the UE 115 such that the UE 115 is capable of communicating with other devices.

[0129] The RF unit 614 can provide the modulated and / or processed data, e.g., data packets (or, more generally, data messages that can contain one or more data packets along with other information) to the antennas 616 for transmission to one or more other devices. The RF unit 614 can handle modulation / demodulation and / or processing of

[0130] In one aspect, the anchor UE 600 can include multiple transceivers 610 implementing different RATs (e.g., NR and LTE). In one aspect, the anchor UE 600 can include a single transceiver 610 implementing multiple RATs (e.g., NR and LTE). In one aspect, the transceiver 610 can include various components, where different combinations of components can implement different RATs.

[0131] Mechanisms for standalone sidelink communications are described in greater detail herein, where a sidelink transmitting UE acts as an anchor node to autonomously initiate sidelink operations with other sidelink receiving UEs over a shared radio frequency band or an unlicensed band.

[0132] In some aspects, the processor 602 can determine system parameter information to initiate sidelink communications, and the transceiver 610 can transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period, and communicate sidelink data with a second UE (e.g., a non-anchor UE 500) in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

[0133] In some aspects, the sidelink configuration module 608 can transmit a SSB to facilitate synchronization at the UE for synchronizing sidelink communications. For example, the sidelink communication module 508 is configured to provide timing synchronization and control signaling to other sidelink receiving UEs including the non-anchor UE 500. In some aspects, the processor 602 can generate a synchronization signal to facilitate synchronization between the anchor UE 600 and the non-anchor UE 500 and allocate the synchronization signal for a first portion of a sidelink synchronization signal block (e.g., S-SSB), where the synchronization signal includes a primary synchronization signal followed by a secondary synchronization signal. In some aspects, the processor 602 can determine a sidelink master information block (e.g., SL-MIB) including at least a portion of system parameter information and allocate the SL-MIB for a second portion of the S-SSB, where the second portion follows the first portion.

[0134] In some aspects, the one or more first sub-bands include a physical sidelink broadcast channel (e.g., PSBCH) in a first portion of the first time period, and the transceiver 610, which can transmit system parameter information, is further configured to transmit the S-SSB on the PSBCH. In some aspects, the processor 602 can determine an initial transmission radio resource pool configuration, where the initial transmission radio resource pool configuration can include one or more of a plurality of sub-channels, a plurality of modulation symbols, or a set of time domain slots within the first time period during which remaining minimum system information (e.g., RMSI) is transmitted, and allocate the initial transmission radio resource pool configuration for one or more locations in the SL-MIB. In some aspects, the processor 602 can provide an indication within the SL-MIB indicating whether RMSI is present for processing by the non-anchor UE 500.

[0135] In some embodiments, the anchor UE 600 can provide additional system parameters in the form of RMSI. In some aspects, the RMSI includes additional system parameter information that is different from at least a portion of the system parameter information in the SL-MIB. In some aspects, the transceiver 610 can transmit the RMSI with the non-anchor UE 500 in a second sub-band during the first time period. In some aspects, the second sub-band includes a plurality of physical sidelink control channels (e.g., PSCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period and a plurality of physical sidelink shared channels (e.g., PSSCHs) multiplexed in at least one of time or frequency in a second portion of the first time period, where the second portion is different from the first portion. In some aspects, the transceiver 610 can transmit the RMSI in one or more of the plurality of PSCCHs, and the transceiver 610 can further transmit sidelink data in at least one of the plurality of PSSCHs. In some aspects, the transceiver 610 can transmit an indication of an intra-cell guard band in the RMSI for use by the non-anchor UE 500 to recover one or more sets of resource blocks.

[0136] In some embodiments, the anchor UE 600 can provide bandwidth allocation within the additional system parameters. In some aspects, the transceiver 610 can transmit a sidelink BWP configuration in the RMSI. In some aspects, the processor 602 can determine a plurality of predefined sets of initial sidelink bandwidth part (BWP) configurations and provide an indication in one or more locations in the SL-MIB indicating at least one of the plurality of predefined sets of initial sidelink BWP configurations. In some aspects, at least one of the plurality of predefined sets of initial sidelink BWP configurations can include a starting RB and a number of RBs. In this aspect, the initial BWP configuration can include a group of contiguous RBs up to the number of RBs. The starting RB can correspond to a first location in a resource grid, and the S-SSB can occupy at least a second location in the resource grid, where the first location and the second location are separated by a resource block level offset. In various aspects, the resource grid includes a two-dimensional array of resource blocks and modulation symbols (e.g., OFDM symbols). In some aspects, the sidelink BWP configuration is different from at least one initial sidelink BWP configuration in at least one of the at least one of the plurality of predefined sets of initial sidelink BWP configurations included in the SL-MIB. In some aspects, each of the plurality of predefined sets of initial sidelink BWP configurations can include a separate numerology. In some aspects, the S-SSB is transmitted within a bandwidth defined in the initial BWP configuration.

[0137] In some embodiments, the anchor UE 600 can provide resource allocation information to the sidelink receiving UEs. In some aspects, the transceiver 610 can transmit a transmission resource pool configuration in the RMSI, where the transmission resource pool configuration can indicate which radio resources are allocated to the anchor UE 600 for the anchor UE 600 to transmit sidelink communications. In some aspects, the transceiver 610 can transmit a reception resource pool configuration in the RMSI, where the reception resource pool configuration can indicate which radio resources are allocated to the anchor UE 600 for the anchor UE 600 to receive sidelink communications. In some aspects, the transceiver 610 can transmit a transmission mode of S-SSBs in the RMSI to enable the non-anchor UE 500 to rate match the S-SSBs. In some aspects, the transceiver can transmit a transmission mode of the RMSI in the RMSI to enable the non-anchor UE 500 to monitor the RMSI.

[0138] In some embodiments, the anchor UE 600 can provide an announcement of its anchor node configuration and monitor other anchor nodes to maintain local consistency of system parameters in the sidelink system. In some aspects, the transceiver 610 can transmit an output announcement message to announce that the anchor UE 600 is configured as an anchor node to autonomously set sidelink operations for other UEs including the non-anchor UE 500. In some aspects, the processor 602 can monitor the PSDCH for an input announcement message indicating a presence of another UE configured as an anchor node. In some aspects, the transceiver 610 can transmit one or more discovery messages including an output announcement message in the PSDCH when the input announcement message indicating the presence of another UE configured as an anchor node is not detected by the anchor UE 600. In some aspects, when the input announcement message indicating the presence of another UE configured as an anchor node is detected, the processor 602 can determine that one or more predetermined factors are satisfied to qualify the first UE as an anchor node and adopt one or more system parameters of the other UE configured as an anchor node. In some aspects, the processor 602 can receive one or more system parameters propagated from the other UE to the anchor UE 600 on the PSDCH. In some aspects, the processor 602 can update the local system parameters with the one or more system parameters adopted from the other UE to generate updated system parameter information and the transceiver 610 can transmit the updated system parameter information during a third time period after the first time period. In some aspects, the transceiver 610 can transmit the updated system parameter information on the PSBCH. In some aspects, the transceiver 610 can transmit the updated system parameter information to one or more other UEs having a sidelink connection with the anchor UE 600 in one or more of a unicast transmission or a groupcast transmission. For example, the anchor UE 600 can perform a unicast transmission to the non-anchor UE 500 to communicate the updated system parameter information with the non-anchor UE 500. In some aspects, the processor 602 can determine whether the other UE is an in-coverage UE based on a location of the other UE relative to a coverage area of a cell (e.g., the BS 205) and determine that the other UE has a higher priority than the anchor UE 600 for determining system parameters between the anchor UE 600 and the other UE when the other UE is in-coverage based on the other UE being within the coverage area of the cell.

[0139] In some aspects, the transceiver 610 can receive, from the non-anchor UE 500, a sidelink message in at least one of the plurality of PSCCHs or in at least one of the plurality of PSSCHs in the second sub-band during the second time period based on receiving the resource pool configuration. In some aspects, the sidelink message can cause the anchor UE 600 to establish a sidelink connection with the non-anchor UE 500.

[0140] Figure 7 FIG. 7 is a flow diagram illustrating an example of an anchor node discovery procedure in accordance with some aspects of the present disclosure. Aspects of the procedure 700 can be executed by a computing device (e.g., a processor, processing circuit, and / or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device such as a UE 115, 215, and / or 500 can utilize one or more components, such as the processor 502, the memory 504, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to execute the steps of the procedure 700. As shown, the procedure 700 includes a number of enumerated steps, but aspects of the procedure 700 can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps can be omitted or performed in a different order.

[0141] At block 702, the sidelink transmitting UE (e.g., UE 115j) can perform a sensing operation. In some aspects, the sensing operation can be performed on a sidelink discovery channel. In some aspects, the sidelink discovery channel can be similar to a PSDCH. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to perform the sensing operation.

[0142] At block 704, the sidelink transmitting UE can determine whether another anchor node is present by detecting other anchor UEs on the sidelink discovery channel. In some aspects, the other anchor UEs can broadcast one or more discovery messages with an announcement of their presence. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, and the modem 512, to determine the presence of another anchor UE. If the sidelink transmitting UE detects other anchor UEs, the procedure 700 proceeds to block 712. Otherwise, the procedure 700 proceeds to block 706.

[0143] At block 706, the sidelink transmitting UE can configure itself as an anchor node when it has determined that no other anchor nodes exist. In some aspects, the sidelink transmitting UE can autonomously decide to configure itself as an anchor node based on a number of factors. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, to configure itself as an anchor node.

[0144] At block 708, the sidelink transmitting UE can announce its anchor node status. In some aspects, the sidelink transmitting UE can broadcast one or more discovery messages marked as an announcement on a sidelink discovery channel. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communications module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to perform the announcement of its anchor node status.

[0145] At block 710, the sidelink transmitting UE (now configured as an anchor node) can broadcast system parameters. In some aspects, the sidelink transmitting UE can transmit the system parameters on a sidelink broadcast channel in the form of a sidelink synchronization signal block. In some aspects, the sidelink broadcast channel can be similar to a PSBCH. In some aspects, the sidelink synchronization signal block can contain synchronization signals (e.g., PSS, SSS) multiplexed in time or frequency with a sidelink master information block. The sidelink synchronization signal block can include a PSCCH multiplexed in time or frequency with the synchronization signals and / or the sidelink master information block, where the PSCCH can carry remaining minimum system information. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communications module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to broadcast the system parameters.

[0146] At block 712, the sidelink transmitting UE can determine whether it is configuring itself as an anchor node. In some aspects, the sidelink transmitting UE can perform sensing operations in a first workflow, where the sidelink transmitting UE decides to become a new anchor node, or in a second workflow, where the sidelink transmitting UE has been configured as an anchor node and performs regular sensing operations for other anchor nodes. If the sidelink transmitting UE is configuring itself as an anchor node, the process 700 proceeds to block 714. Otherwise, the process 700 proceeds to block 716. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communications module 508, the transceiver 510, and the modem 512, to determine whether it is configuring itself as an anchor node.

[0147] At block 714, the sidelink transmitting UE can determine whether it is justified to configure itself as a new anchor node. In some aspects, the sidelink transmitting UE can determine the need for it to become an anchor node based on a number of factors. If the need is justified, the process 700 can proceed to block 720. Otherwise, the process 700 proceeds back to immediately begin block 702. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, to determine whether it is justified to configure itself as an anchor node.

[0148] At block 716, when the sidelink transmitting UE is not configuring itself as an anchor node because the sidelink transmitting UE is already an anchor node, the sidelink transmitting UE can determine a prioritization of other anchor nodes. In some aspects, the sidelink transmitting UE can consider the coverage of other anchor nodes relative to the coverage of the serving BS, such that an anchor node in coverage can have a higher priority. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, to determine the prioritization of other anchor nodes.

[0149] At block 718, the sidelink transmitting UE can determine whether the other anchor node has a higher priority. In this aspect, the sidelink transmitter UE can determine its location of coverage relative to the coverage area of the serving BS. If the sidelink transmitting UE determines that the location of the other anchor UE is within the coverage area of the serving BS, the sidelink transmitting UE concludes that the other anchor node has a higher priority. In this aspect, the process 700 proceeds to block 720. Otherwise, the process 700 proceeds to block 722. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, to determine whether the other anchor node has a higher priority.

[0150] At block 720, the sidelink transmitting UE can adopt the system parameters of the other anchor node. In some aspects, when the sidelink transmitting UE detects the other anchor node and it finds that it is justified to become a new anchor node, the sidelink transmitting UE adopts the system parameters of the other anchor node. In other aspects, when the other anchor node has a higher priority for determining system parameters and the sidelink transmitting UE (configured as an anchor node in this example) is deferring to the other anchor node, the sidelink transmitting UE adopts the system parameters of the other anchor node. In this aspect, by adopting the system parameters of the other anchor node, the sidelink system of the subject technology is helping to maintain local consistency of system parameters, and is helping to reduce the complexity of maintaining multiple, different system parameters across anchor nodes in the sidelink system.

[0151] Returning to block 710, the sidelink transmitting UE can broadcast the updated local system parameters. By adopting the system parameters of the other anchor node, the sidelink transmitting UE updates its local system parameters and announces the updated system parameters to the sidelink receiving UEs. In some aspects, the sidelink transmitting UE can broadcast on the PSBCH or can transmit the updated system parameters to a specific sidelink receiving UE in a unicast transmission or to a group of sidelink receiving UEs in a groupcast transmission. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to broadcast the updated local system parameters.

[0152] At block 722, the sidelink transmitting UE can propagate its system parameters to the other anchor nodes. In some aspects, the sidelink transmitting UE makes a determination that it has a higher priority in setting the system parameters for sidelink operation. In this regard, the other anchor nodes will adopt the system parameters provided by the sidelink transmitting UE. In some instances, the sidelink transmitting UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to propagate its system parameters to the other anchor nodes.

[0153] Figure 8 FIG. 8 is a flow diagram illustrating an example of a sidelink communication process 800 that can be performed by a wireless communication device, in accordance with some aspects of the present disclosure. As shown, process 800 includes a number of enumerated steps, but aspects of process 800 can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps can be omitted or performed in a different order.

[0154] At block 802, the sidelink receiving UE can monitor a sidelink broadcast channel. In some aspects, the sidelink broadcast channel can be similar to a PSBCH. In some instances, the shared radio frequency band can be similar to frequency band 301, and the sub-bands can be similar to frequency sub-bands 302. The first time period can be similar to sidelink frame 304. In some instances, the sidelink receiving UE can monitor the sidelink broadcast channel with one or more components, such as processor 602, sidelink communication module 608, transceiver 610, modem 612, and one or more antennas 616.

[0155] At block 804, the sidelink receiving UE can receive, during the first time period, a sidelink synchronization signal block from the anchor UE on the sidelink broadcast channel in a first sub-band of a plurality of sub-bands within the shared radio frequency. In some instances, the sidelink receiving UE can receive the sidelink synchronization signal block with one or more components, such as processor 602, sidelink communication module 608, transceiver 610, modem 612, and one or more antennas 616.

[0156] At block 806, the sidelink receiving UE can recover a sidelink master information block from the sidelink synchronization block. In some aspects, the sidelink master information block is multiplexed in time or frequency with a synchronization signal (e.g., PSS, SSS) in the sidelink synchronization signal block. In some instances, the sidelink receiving UE can recover the sidelink master information block with one or more components, such as processor 602, sidelink communication module 608, transceiver 610, and modem 612.

[0157] At block 808, the sidelink receiving UE can obtain an initial sidelink bandwidth part configuration from the sidelink master information block. In some aspects, the initial sidelink bandwidth part configuration indicates a resource grid having a plurality of resource blocks and an indication of a starting resource block within the resource grid. In some instances, the sidelink receiving UE can obtain the initial sidelink bandwidth part configuration with one or more components, such as processor 602, sidelink communication module 608, transceiver 610, and modem 612.

[0158] At block 810, the sidelink receiving UE can obtain an initial transmission resource pool configuration from the sidelink master information block. In some aspects, the initial transmission resource pool can indicate radio resources for sidelink messages transmitted by the anchor node, including an indication of radio resources allocated to remaining minimum system information. In some instances, the sidelink receiving UE can obtain the initial transmission resource pool configuration with one or more components, such as processor 602, sidelink communication module 608, transceiver 610, and modem 612.

[0159] At block 812, the sidelink receiving UE determines whether remaining minimum system information is present within the sidelink synchronization signal block. In some aspects, the master information block contains an indicator that serves as an indication of whether remaining minimum system information is present. In this aspect, if the indication shows that remaining minimum system information is present, the process 800 proceeds to block 814, where the sidelink receiving UE can attempt to recover the remaining minimum system information. Otherwise, the process 800 proceeds back to immediately begin with block 802.

[0160] At block 814, the sidelink receiving UE can determine, from the initial transmission resource pool configuration, the radio resources over which the remaining minimum system information is transmitted. In some aspects, the sidelink receiving UE can be pointed to an inclusion in the master information block that enables the sidelink receiving UE to locate and decode the remaining minimum system information. In some aspects, the pointer can correspond to a changed use bit field within the sidelink master information block. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, and the modem 612, to determine the radio resources of the remaining minimum system information.

[0161] At block 816, the sidelink receiving UE can tune to a sidelink control channel based on the radio resources of the remaining minimum system information. In some aspects, the sidelink control channel can be similar to a PSCCH. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, the modem 612, and the one or more antennas 616, to tune to the sidelink control channel.

[0162] At block 818, the sidelink receiving UE can obtain the remaining minimum system information on the PSCCH. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, and the modem 612, to recover the remaining minimum system information.

[0163] At block 820, the sidelink receiving UE can recover the transmission resource pool configuration from the remaining minimum system information. In some aspects, the remaining minimum system information can also include a reception resource pool configuration. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, and the modem 612, to recover the transmission resource pool configuration.

[0164] At block 822, the sidelink receiving UE can tune to the sidelink shared channel based on the radio resources of the remaining minimum system information. In some aspects, the sidelink shared channel can be similar to a PSSCH. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, the modem 612, and the one or more antennas 616, to tune to the sidelink shared channel.

[0165] At block 824, the sidelink receiving UE can receive, from the anchor UE, sidelink data on the PSSCH in a second sub-band of the plurality of sub-bands during a second time period that is different from the first time period based on the transmission resource pool configuration. In some instances, the first UE can utilize one or more components, such as the processor 602, the sidelink communication module 608, the transceiver 610, the modem 612, and the one or more antennas 616, to receive the sidelink data.

[0166] Figure 9 FIG. 9 is a flow diagram illustrating an example of a sidelink system information broadcast procedure 900 in accordance with some aspects of the present disclosure. Aspects of the procedure 900 can be executed by a computing device (e.g., a processor, processing circuit, and / or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device such as a UE 115, 215, and / or 500 can utilize one or more components, such as the processor 502, the memory 504, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to execute the steps of the procedure 900. The procedure 900 can be at least partially performed in conjunction with the mechanisms discussed above with respect to the procedure 700. Figure 7 As illustrated, the procedure 900 includes a number of enumerated steps, but aspects of the procedure 900 can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps can be omitted or performed in a different order.

[0167] At block 910, the sidelink transmitting UE (or anchor UE) can determine system parameter information to initiate sidelink communications. In some aspects, the anchor UE determines the system parameter information autonomously and independent of any serving BS and / or associated core network. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 502, to determine the system parameter information.

[0168] At block 920, the anchor UE can transmit system parameter information on a sidelink broadcast channel in one or more of a plurality of sub-bands within a shared radio frequency during a first time period. In some instances, the shared radio frequency band can be similar to frequency band 301 and the sub-bands can be similar to frequency sub-bands 302. The first time period can be similar to sidelink frame 304. In some instances, the sidelink receiving UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to transmit the system parameter information.

[0169] At block 930, the anchor UE can communicate sidelink data with the sidelink receiving UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information. In some instances, the first UE can utilize one or more components, such as the processor 502, the sidelink communication module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to communicate the sidelink data.

[0170] Figure 10 is a flow diagram of a sidelink communication procedure 1000 in accordance with some aspects of the present disclosure. Aspects of the procedure 1000 can be executed by a computing device (e.g., a processor, a processing circuit, and / or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device such as a UE 115, 215, and / or 600 can utilize one or more components, such as the processor 602, the memory 604, the sidelink communication module 608, the transceiver 610, the modem 612, and the one or more antennas 616, to execute the steps of the procedure 1000. The procedure 1000 can employ similar mechanisms as discussed above with respect to the procedure 800. Figure 8 As illustrated, the procedure 1000 includes a number of enumerated steps, but aspects of the procedure 1000 can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps can be omitted or performed in a different order.

[0171] At block 1010, the sidelink-receiving UE can receive, during a first time period, system parameter information from a sidelink-transmitting UE (or an anchor UE) on a sidelink broadcast channel in a first sub-band of a plurality of sub-bands within a shared radio frequency band. In some instances, the shared radio frequency band can be similar to frequency band 301, and the sub-bands can be similar to frequency sub-bands 302. The first time period can be similar to sidelink frame 304. In some instances, the sidelink-receiving UE can utilize one or more components, such as processor 602, sidelink communication module 608, transceiver 610, modem 612, and one or more antennas 616, to receive the system parameter information.

[0172] At block 1020, the sidelink-receiving UE can recover remaining minimum system information from the system parameter information. In some aspects, the sidelink-receiving UE can be pointed to a portion of the system parameter information included in a master information block that enables the sidelink-receiving UE to locate and decode the remaining minimum system information. In some instances, the sidelink-receiving UE can utilize one or more components, such as processor 602, sidelink communication module 608, transceiver 610, and modem 612, to recover the remaining minimum system information.

[0173] At block 1030, the sidelink-receiving UE can recover a transmit resource pool configuration from the remaining minimum system information. In some aspects, the remaining minimum system information can also include a receive resource pool configuration. In some instances, the sidelink-receiving UE can utilize one or more components, such as processor 602, sidelink communication module 608, transceiver 610, and modem 612, to recover the transmit resource pool configuration.

[0174] At block 1040, the sidelink-receiving UE can receive, during a second time period different from the first time period, sidelink data from the anchor UE in a second sub-band of the plurality of sub-bands based on the transmit resource pool configuration. In some instances, the first UE can utilize one or more components, such as processor 602, sidelink communication module 608, transceiver 610, modem 612, and one or more antennas 616, to receive the sidelink data.

[0175] Information and signals can be represented using a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0176] The various illustrative blocks and modules described in connection with the disclosure herein can be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0177] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed as discrete components or other means for performing the functions described herein, and may

[0178] As those skilled in the art will readily appreciate, many modifications, substitutions and variations of the present disclosure can be made in the materials, designs, arrangements, parts, and methods of use thereof, without departing from the spirit and scope of the disclosure. Accordingly, the scope of the present disclosure should not be limited to the above described embodiments but should be given the full breadth of the appended claims and any equivalents thereof.

Claims

1. A method of wireless communication, comprising: determining, by a first user equipment (UE), system parameter information to initiate sidelink communication, wherein the first UE is an out-of-coverage UE; transmitting, by the first UE, the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period; and communicating, by the first UE, sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

2. The method of claim 1, further comprising: generating, by the first UE, a synchronization signal to facilitate synchronization between the first UE and the second UE; and allocating, by the first UE, the synchronization signal for a first portion of a sidelink synchronization signal block (S-SSB), wherein the synchronization signal comprises a primary synchronization signal followed by a secondary synchronization signal.

3. The method of claim 2, further comprising: determining, by the first UE, a sidelink master information block (SL-MIB) comprising at least a portion of the system parameter information; and allocating, by the first UE, the SL-MIB for a second portion of the S-SSB, wherein the second portion follows the first portion.

4. The method of claim 3, wherein: the one or more first sub-bands comprise a physical sidelink broadcast channel (PSBCH) in a first portion of the first time period, and the transmitting the system parameter information comprises transmitting, by the first UE, the S-SSB on the PSBCH. determining the SL-MIB comprises: determining, by the first UE, an initial transmission radio resource pool configuration, wherein the initial transmission radio resource pool configuration comprises one or more of a plurality of sub-channels, a plurality of modulation symbols, or a set of time domain slots within the first time period during which remaining minimum system information (RMSI) is transmitted; and 5. The method of claim 3, wherein, allocating, by the first UE, the initial transmission radio resource pool configuration for one or more locations in the SL-MIB.

6. The method of claim 5, further comprising: communicating, by the first UE, the RMSI with the second UE in the second sub-band during the first time period.

7. The method of claim 1, further comprising: transmitting, by the first UE, an outgoing announcement message to announce that the first UE is configured to be an anchor node that autonomously sets sidelink operations for other UEs including the second UE. the first UE being an out-of-coverage UE comprises: a processor configured to:

8. A first user equipment (UE), wherein, determine system parameter information to initiate sidelink communication; and a transceiver configured to: transmit the system parameter information in one or more first sub-bands of a plurality of sub-bands within a shared radio frequency during a first time period; and ​ ​ transmit sidelink data with a second UE in a second sub-band of the plurality of sub-bands during a second time period different from the first time period based on the system parameter information.

9. The first UE of claim 8, wherein, The processor is further configured to: generate a synchronization signal to facilitate synchronization between the first UE and the second UE; and allocate the synchronization signal for a first portion of a sidelink synchronization signal block (S-SSB), wherein the synchronization signal includes a primary synchronization signal followed by a secondary synchronization signal.

10. The first UE of claim 9, wherein, The processor is further configured to: determine a sidelink master information block (SL-MIB) including at least a portion of the system parameter information; and allocate the SL-MIB for a second portion of the S-SSB, wherein the second portion follows the first portion.

11. The first UE of claim 10, wherein: the one or more first sub-bands include a physical sidelink broadcast channel (PSBCH) in a first portion of the first time period, and the transceiver configured to transmit the system parameter information is further configured to transmit the S-SSB on the PSBCH.

12. The first UE of claim 10, wherein, The processor configured to determine the SL-MIB is further configured to: determine an initial transmission radio resource pool configuration, wherein the initial transmission radio resource pool configuration includes one or more of a plurality of sub-channels, a plurality of modulation symbols, or a set of time domain slots within the first time period during which remaining minimum system information (RMSI) is transmitted; and allocate the initial transmission radio resource pool configuration for one or more locations in the SL-MIB.

13. The first UE of claim 12, wherein, The transceiver is further configured to: transmit the RMSI with the second UE in the second sub-band during the first time period.

14. The first UE of claim 13, wherein: the second sub-band includes a plurality of physical sidelink control channels (PSCCHs) multiplexed on at least one of time or frequency in a first portion of the first time period and a plurality of physical sidelink shared channels (PSSCHs) multiplexed on at least one of time or frequency in a second portion of the first time period, the second portion being different from the first portion, the transceiver configured to transmit the RMSI is further configured to transmit the RMSI in one or more of the plurality of PSCCHs, and the transceiver configured to transmit the sidelink data is further configured to transmit the sidelink data in at least one of the plurality of PSSCHs.

15. The first UE of claim 12, wherein, The processor is further configured to: provide, within the SL-MIB, an indication to indicate whether the RMSI for processing by the second UE is present.

16. The first UE of claim 12, wherein, The RMSI includes additional system parameter information different from at least a portion of the system parameter information in the SL-MIB.

17. The first UE of claim 12, wherein, The processor configured to determine the SL-MIB is further configured to: determine a plurality of predefined sets of an initial sidelink bandwidth part (BWP) configuration; and determine a set of the initial BWP configuration from the plurality of predefined sets of the initial BWP configuration based on the system parameter information. provide, in one or more locations in the SL-MIB, an indication of at least one predefined set of the plurality of predefined sets of initial sidelink BWP configurations.

18. The first UE of claim 17, wherein: the at least one predefined set of the plurality of predefined sets of initial sidelink BWP configurations comprises a starting resource block (RB) and a number of RBs, and the starting RB corresponds to a first location in a resource grid and the S-SSB occupies at least a second location in the resource grid, the first location and the second location separated by a resource block level offset.

19. The first UE of claim 17, wherein, the transceiver is further configured to: transmit, in the RMSI, a sidelink BWP configuration.

20. The first UE of claim 19, wherein, the sidelink BWP configuration is different from at least one initial sidelink BWP configuration in the at least one predefined set of the plurality of predefined sets of initial sidelink BWP configurations included in the SL-MIB.

21. The first UE of claim 12, wherein, the transceiver is further configured to: transmit, in the RMSI, an indication of an intra-cell guard band for use by the second UE to recover one or more sets of resource blocks.

22. The first UE of claim 12, wherein, the transceiver is further configured to: transmit, in the RMSI, a transmission resource pool configuration indicating which radio resources are allocated to the first UE for the first UE to transmit sidelink communications.

23. The first UE of claim 14, wherein, the transceiver is further configured to: transmit, in the RMSI, a reception resource pool configuration indicating which radio resources are allocated to the first UE for the first UE to receive sidelink communications.

24. The first UE of claim 23, wherein, the transceiver configured to transmit the sidelink data is further configured to: receive, based on the reception resource pool configuration, a sidelink message from the second UE in the second sub-band during the second time period in at least one of the plurality of PSCCHs or in at least one of the plurality of PSSCHs, the sidelink message causing the first UE to establish a sidelink connection with the second UE.

25. The first UE of claim 12, wherein, the transceiver is further configured to: transmit, in the RMSI, a transmission mode of the S-SSB to enable the second UE to rate match the S-SSB.

26. The first UE of claim 12, wherein, the transceiver is further configured to: transmit, in the RMSI, a transmission mode of the RMSI to enable the second UE to monitor the RMSI.

27. The first UE of claim 8, wherein, the transceiver is further configured to: transmit an output announcement message to announce that the first UE is configured to be an anchor node that autonomously sets sidelink operations for other UEs including the second UE.

28. The first UE of claim 27, wherein, the processor is further configured to: monitor a physical sidelink discovery channel (PSDCH) for an input announcement message indicating a presence of another UE configured to be an anchor node.

29. The first UE of claim 28, wherein, the transceiver configured to transmit the output announcement message is further configured to: when the announcement message indicating the presence of the other UE configured as the anchor node is not detected by the first UE, transmitting one or more discovery messages including an announcement message of the output in the PSDCH.

30. The first UE of claim 28, wherein, The processor is further configured to: when the announcement message indicating the presence of the other UE configured as the anchor node is detected, determining that one or more predetermined factors are satisfied to prove that the first UE is the anchor node; and adopting one or more system parameters of the other UE configured as the anchor node.

31. The first UE of claim 30, wherein, The processor configured to adopt the one or more system parameters is further configured to: receive the one or more system parameters broadcast from the other UE to the first UE on the PSDCH.

32. The first UE of claim 30, wherein: The processor is further configured to: update local system parameters with the one or more system parameters adopted from the other UE to generate updated system parameter information; and The transceiver is further configured to: transmit the updated system parameter information during a third time period after the first time period.

33. The first UE of claim 32, wherein, The transceiver configured to transmit the updated system parameter information is further configured to: transmit the updated system parameter information on a physical sidelink broadcast channel (PSBCH).

34. The first UE of claim 32, wherein, The transceiver configured to transmit the updated system parameter information is further configured to: transmit the updated system parameter information to one or more other UEs having a sidelink connection with the first UE in one or more of a unicast transmission or a groupcast transmission.

35. The first UE of claim 30, wherein, The processor configured to adopt the one or more system parameters is further configured to: determine whether the other UE is an in-coverage UE based on a location of the other UE relative to a coverage area of a cell; and when the other UE is an in-coverage UE based on the other UE being within the coverage area of the cell, determine that the other UE has a higher priority than the first UE for determining system parameters between the first UE and the other UE.

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