Time-reversal precoding for sidelink-based positioning

Abstract

This provides a method for time-reverse precoding for sidelink-based positioning. [Solution] In a wireless communication system, the method derives a time-reverse (TR) precoder based at least partially on an estimated channel between a first user device (UE) and a second UE, and sends a TR-precoded sidelink (SL) positioning reference signal (PRS) to the second UE. The estimated channel is based on channel status information (CSI) associated with a wideband (WB) reference signal (RS). The TR precoder is based on transmission or reception on the SL communication channel between the first UE and the second UE.

Description

Claim of Priority

[0001] Cross - Reference to Related Applications

[0001] This application claims priority to Greek Patent Application No. 20210100170, entitled "TIME REVERSAL PRECODING FOR SIDELINK BASED POSITIONING", filed on March 18, 2021, which has been assigned to the assignee of this application and is hereby expressly incorporated by reference in its entirety.

Technical Field

[0002]

[0002] Aspects of the present disclosure generally relate to wireless communication.

Background Art

[0003]

[0003] Wireless communication systems have evolved through various generations, including the first - generation analog wireless telephone service (1G), the second - generation (2G) digital wireless telephone service (including intermediate 2.5G and 2.75G networks), the third - generation (3G) high - speed data, Internet - enabled wireless services, and the fourth - generation (4G) services (such as Long - Term Evolution (LTE (registered trademark)) or WiMax (registered trademark)). Currently, there are many different types of wireless communication systems in use, including cellular and personal communication service (PCS) systems. Examples of known cellular systems include the Cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM (registered trademark)), etc.

[0004]

[0004] The fifth-generation (5G) wireless standard, also known as New Radio (NR), requires improvements such as higher data transfer speeds, a greater number of connections, and better coverage. The 5G standard by the Next Generation Mobile Network Alliance is designed to provide tens of megabits per second of data rates to each of tens of thousands of users and 1 gigabit per second of data rates to dozens of workers on an office floor. Hundreds of thousands of simultaneous connections should be supported to support large sensor deployments. Therefore, the spectral efficiency of 5G mobile communications should be significantly expanded compared to the current 4G standard. Furthermore, signaling efficiency should be expanded and latency should be significantly reduced compared to the current standard.

[0005]

[0005] In particular, leveraging the increased data rates and reduced latency of 5G, vehicle-to-everything (V2X) communication technologies are being implemented to support autonomous driving applications, such as wireless communication between vehicles, between vehicles and roadside infrastructure, and between vehicles and pedestrians. [Overview of the project]

[0006]

[0006] The following provides a simplified overview relating to one or more embodiments disclosed herein. Therefore, the following overview should not be considered a broad overview relating to all intended embodiments, nor should it be considered to identify important or significant elements relating to all intended embodiments or to define the scope relating to a particular embodiment. Accordingly, the following overview has the sole purpose of presenting, in a simplified form, some concepts relating to one or more embodiments relating to the mechanisms disclosed herein, prior to embodiments for carrying out the invention presented below.

[0007]

[0007] In one embodiment, a method of wireless communication performed by a first UE includes deriving a time reversal (TR) precoder based at least partially on an estimated channel between the first UE and a second UE, and sending a TR-precoded sidelink positioning reference signal (SL-PRS) to the second UE.

[0008]

[0008] In one embodiment, a method of wireless communication performed by a first UE includes receiving a wideband reference signal (WB RS) from a second UE, determining channel status information (CSI) based at least in part on the WB RS, and sending the CSI to the second UE.

[0009]

[0009] In one embodiment, a method of wireless communication performed by a first UE includes receiving a WB RS from a second UE, estimating a channel between the second UE and the first UE based at least in part on the WB RS, deriving a TR precoder based on the estimated channel, and sending the TR precoder to the second UE.

[0010]

[0010] In one embodiment, a method of wireless communication performed by the first UE includes sending a WB RS to a second UE and receiving a TR-precoded SL-PRS from the second UE.

[0011]

[0011] In one embodiment, the first UE includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, the at least one processor being configured to derive a TR precoder based at least partially on an estimated channel between the first UE and the second UE and to send the TR precoded SL-PRS to the second UE.

[0012]

[0012] In one embodiment, the first UE includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to receive WB RS from the second UE, determine a CSI at least partially based on the WB RS, and send the CSI to the second UE.

[0013]

[0013] In one embodiment, the first UE includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to receive a WB RS from the second UE, estimate a channel between the second UE and the first UE based at least in part on the WB RS, derive a TR precoder based on the estimated channel, and send the TR precoder to the second UE.

[0014]

[0014] In one embodiment, the first UE includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, the at least one processor being configured to send WB RS to the second UE and receive TR precoded SL-PRS from the second UE.

[0015]

[0015] In one embodiment, the first UE includes means for deriving a TR precoder based at least partially on an estimated channel between the first UE and the second UE, and means for sending the TR precoded SL-PRS to the second UE.

[0016]

[0016] In one embodiment, the first UE includes means for receiving WB RS from the second UE, means for determining the CSI at least partially based on the WB RS, and means for sending the CSI to the second UE.

[0017]

[0017] In one embodiment, the first UE includes means for receiving WB RS from the second UE, means for estimating a channel between the second UE and the first UE based at least in part on the WB RS, means for deriving a TR precoder based on the estimated channel, and means for sending the TR precoder to the second UE.

[0018]

[0018] In one embodiment, the first UE includes means for sending WB RS to the second UE and means for receiving TR-precoded SL-PRS from the second UE.

[0019]

[0019] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, the one or more instructions causing the first UE to derive a TR precoder based at least partially on an estimated channel between the first UE and the second UE, and to send a TR precoded SL-PRS to the second UE, when executed by one or more processors of the first UE, the non-temporary computer-readable medium.

[0020]

[0020] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, the one or more instructions causing the first UE to receive a WB RS from a second UE, determine a CSI at least partially based on the WB RS, and send the CSI to the second UE when executed by one or more processors of the first UE, the non-temporary computer-readable medium.

[0021]

[0021] In one aspect, a non - transitory computer - readable medium storing a set of instructions, the set of instructions comprising one or more instructions that, when executed by one or more processors of a first UE, cause the first UE to receive a WB RS from a second UE, estimate a channel between the second UE and the first UE based at least in part on the WB RS, derive a TR precoder based on the estimated channel, and send the TR precoder to the second UE.

[0022]

[0022] In one aspect, a non - transitory computer - readable medium storing a set of instructions, the set of instructions comprising one or more instructions that, when executed by one or more processors of a first UE, cause the first UE to send a WB RS to a second UE and receive a TR - precoded SL - PRS from the second UE.

[0023]

[0023] Other objects and advantages related to the aspects disclosed herein will be apparent to those skilled in the art based on the accompanying drawings and detailed description.

[0024]

[0024] The accompanying drawings are presented to assist in the description of various aspects of the present disclosure and are provided for purposes of illustration of the aspects, not limitation.

Brief Description of the Drawings

[0025] [Figure 1]

[0025] A diagram illustrating an exemplary wireless communication system according to an aspect of the present disclosure. [Figure 2A]

[0026] A diagram illustrating an exemplary wireless network structure according to an aspect of the present disclosure. [Figure 2B] A diagram illustrating an exemplary wireless network structure according to an aspect of the present disclosure. [[ID=二十九]] [Figure 3]

[0027] A diagram showing an example of a wireless communication system that supports unicast side link establishment according to an aspect of the present disclosure. [Figure 4]

[0028] A block diagram showing various components of an exemplary user equipment (UE) according to an aspect of the present disclosure. [Figure 5A]

[0029] A diagram showing two methods for single cell UE positioning that can be implemented when a cell includes multiple UEs engaged in SL communication. [Figure 5B] A diagram showing two methods for single cell UE positioning that can be implemented when a cell includes multiple UEs engaged in SL communication. [Figure 6]

[0030] A diagram showing a flowchart of an exemplary process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 7]

[0031] A messaging and event diagram showing a process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 8]

[0032] A messaging and event diagram showing a process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 9]

[0033] A messaging and event diagram showing a process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 10]

[0034] A diagram showing a flowchart of an exemplary process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 11]

[0035] A diagram showing a flowchart of an exemplary process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Figure 12]

[0036] A diagram showing a flowchart of an exemplary process related to TR precoding for SL-based positioning according to an aspect of the present disclosure. [Modes for carrying out the invention]

[0026]

[0037] Aspects of this disclosure are provided in the following description and related drawings, which cover various examples provided for illustrative purposes. Alternative embodiments may be devised without departing from the scope of this disclosure. Furthermore, well-known elements of this disclosure are not described in detail or are omitted so as not to obscure relevant details of this disclosure.

[0027]

[0038] The words “exemplary” and / or “example” are used herein to mean “to serve as an example, case, or illustration.” Any aspect described herein as “exemplary” and / or “example” should not necessarily be construed as being preferable or advantageous to any other aspect. Similarly, the term “aspects of the disclosure” does not require that all aspects of the disclosure include the described features, advantages, or modes of operation.

[0028]

[0039] Those skilled in the art will understand that the information and signals described below may be represented using any of the various different techniques and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the following description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof, depending in part with the specific application, in part with the desired design, in part with the corresponding technology.

[0029]

[0040] Furthermore, many embodiments are described, for example, with respect to a set of actions to be performed by elements of a computing device. It will be recognized that the various actions described herein may be performed by a particular circuit (e.g., an application-specific integrated circuit (ASIC)), by program instructions executed by one or more processors, or a combination of both. Furthermore, the set of actions described herein may be considered to be performed as a whole in any form of non-temporary computer-readable storage medium storing, at runtime, a corresponding set of computer instructions that cause or instruct the relevant processors of the device to perform the functions described herein. Thus, the various embodiments of this disclosure may be implemented in several different forms, all of which are intended to fall within the scope of the claimed subject matter. Furthermore, for each of the embodiments described herein, any corresponding form of such embodiment may be described herein, for example, as “logic configured to perform” the described actions.

[0030]

[0041] As used herein, the terms “User Equipment” (UE), “Vehicle UE” (V-UE), “Pedestrian UE” (P-UE), and “Base Station” are not intended to be specific to, or in any case limited to, any particular Radio Access Technology (RAT), unless otherwise noted. Generally, a UE can be any wireless communication device used by a user to communicate over a wireless communication network (e.g., a vehicle onboard computer, a vehicle navigation device, a mobile phone, a router, a tablet computer, a laptop computer, a tracking device, a wearable (e.g., a smartwatch, glasses, an augmented reality (AR) / virtual reality (VR) headset, etc.), a vehicle (e.g., a car, a motorcycle, a bicycle, etc.), an Internet of Things (IoT) device, etc.). A UE can be mobile or (e.g., at some time) stationary and can communicate with a Radio Access Network (RAN). As used herein, the terms “UE” may be interchangeably referred to as “Mobile Device,” “Access Terminal,” or “AT,” “Client Device,” “Wireless Device,” “Subscriber Device,” “Subscriber Terminal,” “Subscriber Station,” “User Terminal,” or “UT,” “Mobile Terminal,” “Mobile Station,” or variations thereof.

[0031]

[0042] A V-UE is a type of UE that can be any in-vehicle wireless communication device, such as a navigation system, warning system, head-up display (HUD), or onboard computer. Alternatively, a V-UE can be a portable wireless communication device (e.g., a cell phone, tablet computer) carried by the driver or passengers in the vehicle. The term "V-UE" may refer to an in-vehicle wireless communication device or the vehicle itself, depending on the context. A P-UE is a type of UE that can be a portable wireless communication device carried by a pedestrian (i.e., a user who is not driving or not in the vehicle). Generally, a UE can communicate with the core network via the RAN, and through the core network, a UE can connect to external networks such as the Internet and other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for a UE, such as via a wired access network, a wireless local area network (WLAN) network (e.g., based on IEEE 802.11, etc.).

[0032]

[0043] A base station may operate according to one of several RATs communicating with a UE, depending on the network in which it is deployed, and may alternatively be called an access point (AP), network node, node B, advanced node B (eNB), next-generation eNB (ng-eNB), or new radio (NR) node B (also called gNB or g node B). Base stations may be used primarily to support wireless access by UEs, including supporting data, voice, and / or signaling connections for supported UEs. In some systems, a base station may provide purely edge node signaling functionality, while in others it may provide additional control and / or network management functionality. The communication link through which a UE can signal to a base station is called an uplink (UL) channel (e.g., reverse traffic channel, reverse control channel, access channel, etc.). The communication link through which a base station can signal to a UE is called a downlink (DL) or forward link channel (e.g., paging channel, control channel, broadcast channel, forward traffic channel, etc.). As used herein, the term Traffic Channel (TCH) may refer to either a UL / reverse traffic channel or a DL / forward traffic channel.

[0033]

[0044] The term “base station” can refer to a single physical transmit / receive point (TRP), or to multiple physical TRPs, which may or may not be colocated. For example, when the term “base station” refers to a single physical TRP, the physical TRP could be the base station’s antennas corresponding to the base station’s cells (or several cell sectors). When the term “base station” refers to multiple colocated physical TRPs, the physical TRPs could be the base station’s antenna arrays (for example, in a multi-input multiple-output (MIMO) system, or if the base station employs beamforming). When the term “base station” refers to multiple uncolocated physical TRPs, the physical TRPs could be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transport medium) or a remote radio head (RRH) (a remote base station connected to a serving base station). Alternatively, uncolocated physical TRPs could be a serving base station receiving measurement reports from a UE and a neighbor base station where the UE is measuring its reference RF signal. Since a TRP is the point from which a base station transmits and receives wireless signals, references to transmission from a base station or reception at a base station used herein should be understood to refer to a specific TRP of the base station.

[0034]

[0045] In some implementations supporting UE positioning, a base station may not support wireless access by the UE (for example, it may not support data, voice, and / or signaling connectivity for the UE), but instead may transmit a reference RF signal to the UE to be measured by the UE, and / or receive and measure signals transmitted by the UE. Such a base station may be called a positioning beacon (for example, when transmitting an RF signal to the UE) and / or a location measurement unit (for example, when receiving and measuring an RF signal from the UE).

[0035]

[0046] An "RF signal" comprises an electromagnetic wave of a given frequency that transports information through the space between a transmitter and a receiver. A transmitter used herein may transmit a single "RF signal" or multiple "RF signals" to a receiver. However, due to the propagation characteristics of RF signals through multipath channels, a receiver may receive multiple "RF signals" corresponding to each transmitted RF signal. The same transmitted RF signal on different paths between the transmitter and receiver may be called a "multipath" RF signal. As used herein, an RF signal may be called a "wireless signal," or simply a "signal" where the term "signal" is clear from the context that it refers to either a wireless signal or an RF signal.

[0036]

[0047] Figure 1 shows an exemplary wireless communication system 100 according to an aspect of the present disclosure. The wireless communication system 100 (sometimes called a wireless wide area network (WWAN)) may include various base stations 102 (marked "BS") and various UEs 104. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macrocell base station 102 may include an eNB and / or ng-eNB corresponding to an LTE network, or a gNB corresponding to an NR network, or a combination of both, and the small cell base station may include femtocells, picocells, microcells, etc.

[0037]

[0048] The base stations 102 collectively form a RAN and interface with the core network 174 (e.g., an Advanced Packet Core (EPC) or a 5G core (5GC)) through the backhaul link 122, and may interface with one or more location servers 172 (e.g., a Location Management Function (LMF) or a Secure User Plane Location (SUPL) Location Platform (SLP)) through the core network 174. The location servers 172 may be part of the core network 174 or may be outside of the core network 174. In addition to other functions, base stations 102 may perform functions related to the transfer of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access layer (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracing, RAN information management (RIM), paging, positioning, and delivery of warning messages. Base stations 102 may communicate with each other directly or indirectly (e.g., through EPC / 5GC) via backhaul links 134, which may be wired or wireless.

[0038]

[0049] Base station 102 can communicate wirelessly with UE 104. Each base station 102 can provide communication coverage to its respective geographical coverage area 110. In one embodiment, one or more cells may be supported by base stations 102 in each geographical coverage area 110. A “cell” is a logical communication entity used for communication with a base station (over some frequency resource, such as carrier frequency, component carrier, carrier, or band), and may be associated with an identifier (e.g., Physical Cell Identifier (PCI), Extended Cell Identifier (ECI), Virtual Cell Identifier (VCI), Cell Global Identifier (CGI), etc.) to distinguish cells operating over the same or different carrier frequencies. In some cases, different cells may be configured according to different protocol types (e.g., Machine Type Communications (MTC), Narrowband IoT (NB-IoT), Enhanced Mobile Broadband (eMBB), or others) that may provide access to different types of UEs. Since a cell is supported by a particular base station, the term “cell” may, depending on the context, refer to either or both the logical communication entity and the base station that supports it. In some cases, the term “cell” may also refer to the geographical coverage area (e.g., sector) of a base station, insofar as the carrier frequency can be detected and used for communications within some portion of the geographical coverage area 110.

[0039]

[0050] The geographical coverage areas 110 of neighboring macrocell base stations 102 may partially overlap (for example, in the handover area), but some of the geographical coverage areas 110 may largely overlap with larger geographical coverage areas 110. For example, a small cell base station 102' (marked "SC" for "small cell") may have a geographical coverage area 110' that largely overlaps with the geographical coverage areas 110 of one or more macrocell base stations 102. A network that includes both small cell base stations and macrocell base stations may be known as a heterogeneous network. A heterogeneous network may also include a home eNB (HeNB) that can serve a limited group known as a limited subscriber group (CSG).

[0040]

[0051] The communication link 120 between base station 102 and UE 104 may include uplink transmissions from UE 104 to base station 102 (also called a reverse link) and / or downlink (DL) transmissions from base station 102 to UE 104 (also called a forward link). The communication link 120 may use MIMO antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may be traversed by one or more carrier frequencies. Carrier allocation may be asymmetric with respect to the downlink and uplink (for example, more or fewer carriers may be allocated to the downlink than to the uplink).

[0041]

[0052] The wireless communication system 100 may further include a WLAN access point (AP) 150 communicating with a wireless local area network (WLAN) station (STA) 152 via a communication link 154 in an unlicensed frequency spectrum (e.g., 5 GHz). When communicating in an unlicensed frequency spectrum, the WLAN STA 152 and / or WLAN AP 150 may perform a clear channel assessment (CCA) procedure or a listen-before-talk (LBT) procedure before communication to determine whether the channel is available.

[0042]

[0053] Small cell base station 102' may operate in licensed and / or unlicensed frequency spectrums. When operating in an unlicensed frequency spectrum, small cell base station 102' may employ LTE or NR technology and use the same 5GHz unlicensed frequency spectrum used by WLAN AP150. Small cell base station 102' employing LTE / 5G in an unlicensed frequency spectrum may boost coverage to the access network and / or increase the capacity of the access network. NR in an unlicensed spectrum may be referred to as NR-U. LTE in an unlicensed spectrum may be referred to as LTE-U, License-Assisted Access (LAA), or MulteFire.

[0043]

[0054] The wireless communication system 100 may further include a mmW base station 180 that communicates with UE 182 and may operate in mmW and / or near-mmW frequencies. Extremely high frequency (EHF) is a part of RF in the electromagnetic spectrum. EHF has a range from 30 GHz to 300 GHz and wavelengths between 1 millimeter and 10 millimeters. Radio waves in this band are sometimes called millimeter waves. Near-mmW can extend down to frequencies up to 3 GHz with wavelengths of 100 millimeters. The very high frequency (SHF) band, also called centimeter waves, extends between 3 GHz and 30 GHz. Communication using the mmW / near-mmW radio frequency bands has high path loss and relatively short range. The mmW base station 180 and UE 182 may utilize beamforming (transmit and / or receive) via the mmW communication link 184 to compensate for the extremely high path loss and short range. Furthermore, in alternative configurations, it will be understood that one or more base stations 102 may also transmit using mmW or near-mmW and beamforming. Accordingly, it will be understood that the above description is merely illustrative and should not be construed as limiting the various embodiments disclosed herein.

[0044]

[0055] Transmit beamforming is a technique for focusing RF signals in a specific direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectionally). In transmit beamforming, the network node determines where a given target device (e.g., a UE) is located (relative to the transmitting network node) and projects a stronger downlink RF signal in that specific direction, thereby providing a faster and stronger RF signal (in terms of data rate) to one or more receiving devices. To change the directionality of an RF signal when transmitting, the network node can control the phase and relative amplitude of the RF signal at each of the one or more transmitters broadcasting the RF signal. For example, the network node may use an array of antennas (called a "phased array" or "antenna array") that can create beams of RF waves that can be "steered" to point in different directions without actually moving the antennas. Specifically, the RF current from the transmitter is supplied to individual antennas with the appropriate phase relationship so that the radio waves from separate antennas are added together to increase radiation in the desired direction, while canceling out and suppressing radiation in undesirable directions.

[0045]

[0056] Transmit beams can be pseudo-collocated, meaning that the transmit beam appears to the receiver (e.g., UE) to have the same parameters regardless of whether the network node's transmit antenna itself is physically collocated. In NR, there are four types of pseudo-collocation (QCL) relationships. In particular, a given type of QCL relationship means that several parameters relating to a second reference RF signal on a second beam can be derived from information about the source reference RF signal on the source beam. Thus, if the source reference RF signal is QCL type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, mean delay, and delay spread of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type C, the receiver can use the source reference RF signal to estimate the Doppler shift and mean delay of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type D, the receiver can use the source reference RF signal to estimate the spatial reception parameters of a second reference RF signal transmitted on the same channel.

[0046]

[0057] In receive beamforming, a receiver uses a received beam to amplify an RF signal detected on a given channel. For example, a receiver may increase the gain setting of an antenna array in a particular direction and / or adjust the phase setting to amplify an RF signal received from that direction (e.g., increase its gain level). Therefore, when a receiver is said to beamform in a certain direction, it means that the beam gain in that direction is higher than the beam gain along other directions, or that the beam gain in that direction is the highest compared to the beam gain in that direction of all other receive beams available to the receiver. This results in a stronger received signal intensity (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference plus noise ratio (SINR), etc.) of the RF signal received from that direction.

[0047]

[0058] The transmit beam and receive beam can be spatially related. This spatial relationship means that parameters for a second beam (e.g., transmit or receive beam) of a second reference signal can be derived from information about a first beam (e.g., receive or transmit beam) of a first reference signal. For example, a UE might use a specific receive beam to receive a reference downlink reference signal (e.g., a synchronization signal block (SSB)) from a base station. The UE can then form a transmit beam to send an uplink reference signal (e.g., a sounding reference signal (SRS)) to that base station, based on the parameters of the receive beam.

[0048]

[0059] It should be noted that a “downlink” beam can be either a transmit beam or a receive beam, depending on the entity forming it. For example, if a base station forms a downlink beam to transmit a reference signal to a UE, then the downlink beam is a transmit beam. However, if a UE forms a downlink beam, then it is a receive beam for receiving a downlink reference signal. Similarly, an “uplink” beam can be either a transmit beam or a receive beam, depending on the entity forming it. For example, if a base station forms an uplink beam, then it is an uplink receive beam, and if a UE forms an uplink beam, then it is an uplink transmit beam.

[0049]

[0060] In 5G, the frequency spectrum on which wireless nodes (e.g., base stations 102 / 180, UE104 / 182) operate is divided into several frequency ranges: FR1 (450 to 6000 MHz), FR2 (24250 to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). The mmW frequency band generally includes the FR2, FR3, and FR4 frequency ranges. Therefore, the terms "mmW" and "FR2" or "FR3" or "FR4" can generally be used interchangeably.

[0050]

[0061] In multi-carrier systems such as 5G, one of the carrier frequencies is called the “primary carrier,” “anchor carrier,” “primary serving cell,” or “PCell,” while the remaining carrier frequencies are called “secondary carriers,” “secondary serving cells,” or “SCell.” In carrier aggregation, the anchor carrier is the carrier operating on the primary frequency (e.g., FR1) utilized by UE104 / 182 and the cell from which UE104 / 182 either performs the initial radio resource control (RRC) connection establishment procedure or initiates the RRC connection re-establishment procedure. The primary carrier carries all common and UE-specific control channels and may be a carrier in licensed frequencies (though this is not always the case). The secondary carrier is the carrier operating on a second frequency (e.g., FR2) which may be configured once an RRC connection is established between UE104 and the anchor carrier and may be used to provide additional radio resources. In some cases, the secondary carrier may be a carrier in unlicensed frequencies. The secondary carrier may contain only the necessary signaling information and signals, and since both the primary uplink carrier and primary downlink carrier are typically UE-specific, there may be no UE-specific information in the secondary carrier. This means that different UE104 / 182s in a cell can have different downlink primary carriers. The same is true for uplink primary carriers. The network can change the primary carrier of any UE104 / 182 at any time. This is done, for example, to distribute the load across different carriers. Since a “serving cell” (whether PCell or SCell) corresponds to the carrier frequency / component carrier through which some base station is communicating, terms such as “cell,” “serving cell,” “component carrier,” and “carrier frequency” can be used interchangeably.

[0051]

[0062] For example, still referring to Figure 1, one of the frequencies utilized by the macrocell base station 102 could be the anchor carrier (or "PCell"), and the other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 could be the secondary carriers ("SCell"). Simultaneous transmission and / or reception of multiple carriers allows UE 104 / 182 to significantly increase its data transmission and / or reception rates. For example, two 20MHz aggregated carriers in a multicarrier system would theoretically lead to a doubling of the data rate (i.e., 40MHz) compared to what would be achieved with a single 20MHz carrier.

[0052]

[0063] In the example in Figure 1, one or more Earth Orbiting Satellite Positioning System (SPS) space vehicles (SV) 112 (e.g., satellites) may be used as an independent source of location information for any of the illustrated UEs (shown in Figure 1 as a single UE 104 for simplicity). UE 104 may include one or more dedicated SPS receivers specifically designed to receive SPS signals 124 for deriving geolocation information from SV 112. SPS typically includes a system of transmitters arranged to enable a receiver (e.g., UE 104) to determine the receiver's location on or above the Earth based at least in part on signals (e.g., SPS signals 124) received from a transmitter (e.g., SV 112). Such transmitters typically transmit signals marked with a set number of repeating pseudo-random noise (PN) codes. While typically located in SV 112, transmitters may sometimes be located on ground-based control stations, base stations 102, and / or other UE 104s.

[0053]

[0064] The use of SPS signal 124 can be augmented by various satellite-based augmentation systems (SBAS) that are associated with or can be enabled for use with one or more global and / or regional navigation satellite systems. For example, an SBAS may include (one or more) augmentation systems that provide integrity information, differential corrections, etc., such as a Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), Multi-functional Satellite Augmentation System (MSAS), or GPS-Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN). Therefore, as used herein, SPS may include one or more global and / or regional navigation satellite systems and / or any combination of augmentation systems, and SPS signal 124 may include SPS signals, SPS-like signals, and / or other signals associated with one or more such SPS systems.

[0054]

[0065] In particular, leveraging the increased data rates and reduced latency of NR, Vehicle-to-Everything (V2X) communication technology is being implemented to support Intelligent Transport System (ITS) applications, including vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-pedestrian (V2P)) wireless communication. The goal is for vehicles to sense their surrounding environment and communicate that information to other vehicles, infrastructure, and personal mobile devices. Such vehicle communication will enable improvements in safety, mobility, and the environment that current technologies cannot provide. When fully implemented, the technology is expected to reduce unimpaired vehicle collisions by 80%.

[0055]

[0066] Referring again to Figure 1, the wireless communication system 100 may include multiple V-UEs 160 that can communicate with a base station 102 via a communication link 120 (for example, using a Uu interface). The V-UEs 160 may also communicate directly with each other via a wireless sidelink 162, with a roadside access point 164 (also called a “roadside unit”) via a wireless sidelink 166, or with a UE 104 via a wireless sidelink 168. A wireless sidelink (or simply a “sidelink”) is an adaptation of a core-cellular (e.g., LTE, NR) standard that enables direct communication between two or more UEs without the need for that communication to go through a base station. Sidelink communication can be unicast or multicast and may be used for D2D media sharing, V2V communication, V2X communication (e.g., cellular V2X (cV2X) communication, enhanced V2X (eV2X) communication, etc.), emergency rescue applications, etc. One or more of the groups of V-UE160s utilizing sidelink communication may be located within the geographical coverage area 110 of base station 102. Other V-UE160s in such groups may be outside the geographical coverage area 110 of base station 102, or otherwise unable to receive transmissions from base station 102. In some cases, groups of V-UE160s communicating via sidelink communication may utilize a one-to-many (1:M) system where each V-UE160 transmits to any other V-UE160 in the group. In some cases, base station 102 facilitates the scheduling of resources for sidelink communication. In other cases, sidelink communication occurs between V-UE160s without the involvement of base station 102.

[0056]

[0067] In one embodiment, sidelinks 162, 166, and 168 may operate over a wireless communication medium of interest, which may be shared with other vehicles and / or infrastructure access points, as well as with other wireless communications between other RATs. The “medium” may consist of one or more time, frequency, and / or spatial communication resources (e.g., encompassing one or more channels across one or more carriers) related to wireless communications between one or more transmitter / receiver pairs.

[0057]

[0068] In one embodiment, sidelinks 162, 166, and 168 may be cV2X links. The first generation of cV2X is standardized in LTE, and the next generation is expected to be defined in NR. cV2X is a cellular technology that also enables device-to-device communication. In the United States and Europe, cV2X is expected to operate in licensed ITS bands in the sub-6 GHz range. In other countries, other bands may be allocated. Thus, as a specific example, the medium of interest utilized by sidelinks 162, 166, and 168 may correspond to at least a portion of the licensed ITS frequency band in the sub-6 GHz range. However, this disclosure is not limited to this frequency band or cellular technology.

[0058]

[0069] In one embodiment, sidelinks 162, 166, and 168 may be dedicated short-range communication (DSRC) links. DSRC is a one-way or two-way short-to-medium-range wireless communication protocol that uses the Wireless Access for Vehicular Environments (WAVE) protocol, also known as IEEE 802.11p, for V2V, V2I, and V2P communication. IEEE 802.11p is an approved amendment to the IEEE 802.11 standard and operates in the 5.9 GHz (5.85–5.925 GHz) authorized ITS band in the United States. In Europe, IEEE 802.11p operates in the ITS G5A band (5.875–5.905 MHz). Other bands may be allocated in other countries. The V2V communication briefly described above takes place over a safety channel, which in the United States is typically a 10 MHz channel dedicated to safety purposes. The remainder of the DSRC band (with a total bandwidth of 75 MHz) is used for other services of interest to drivers, such as road regulations, toll collection, and automated parking. Thus, as a specific example, the medium of interest utilized by side links 162, 166, and 168 may correspond to at least a portion of the 5.9 GHz authorized ITS frequency band.

[0059]

[0070] Alternatively, the medium of interest could correspond to at least a portion of the unlicensed frequency bands shared among various RATs. While different licensed frequency bands are reserved for certain communication systems (for example, by government agencies such as the Federal Communications Commission (FCC) in the United States), these systems, particularly those employing small cell access points, have recently extended their operation to unlicensed frequency bands, such as the unlicensed National Information Infrastructure (U-NII) bands used by Wireless Local Area Network (WLAN) technology, most notably the IEEE 802.11x WLAN technology commonly known as "Wi-Fi®". Exemplary systems of this type include different variants such as CDMA systems, TDMA systems, FDMA systems, orthogonal FDMA (OFDMA) systems, and single-carrier FDMA (SC-FDMA) systems.

[0060]

[0071] Communication between V-UE160 is called V2V communication, communication between V-UE160 and one or more roadside access points 164 is called V2I communication, and communication between V-UE160 and one or more UE104 (where UE104 is P-UE) is called V2P communication. V2V communication between V-UE160 may include, for example, information about the V-UE160's position, speed, acceleration, orientation, and other vehicle data. V2I information received by V-UE160 from one or more roadside access points 164 may include, for example, road regulations, parking automation information, etc. V2P communication between V-UE160 and UE104 may include, for example, information about the V-UE160's position, speed, acceleration, and orientation, as well as information about the UE104's position, speed (for example, if UE104 is carried by a user on a bicycle), and orientation.

[0061]

[0072] Although Figure 1 shows only two of the UEs as V-UEs (V-UE160), it should be noted that any of the illustrated UEs (e.g., UE104, 152, 182, 190) could be V-UEs. Furthermore, although only V-UE160 and a single UE104 are shown as being connected via sidelinks, any of the UEs shown in Figure 1, regardless of whether they are V-UEs or P-UEs, may be capable of sidelink communication. Additionally, although only UE182 is described as being capable of beamforming, any of the illustrated UEs, including V-UE160, may be capable of beamforming. If V-UE160 is capable of beamforming, they may beamform toward each other (i.e., toward other V-UE160s), toward roadside access point 164, toward other UEs (e.g., UE104, 152, 182, 190), etc. Therefore, in some cases, the V-UE160 can utilize beamforming via side links 162, 166, and 168.

[0062]

[0073] The wireless communication system 100 may further include one or more UEs, such as UE 190, which are indirectly connected to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the example in Figure 1, UE 190 has a D2D P2P link 192 with one of UEs 104 connected to one of base stations 102 (through which UE 190 can indirectly obtain cellular connectivity), and a D2D P2P link 194 with a WLAN STA 152 connected to a WLAN AP 150 (through which UE 190 can indirectly obtain WLAN-based internet connectivity). In one example, D2D P2P links 192 and 194 may be supported using any well-known D2D RAT, such as LTE Direct (LTE-D), WiFi Direct® (WiFi®-D), or Bluetooth®. As another example, D2D P2P links 192 and 194 may be side links, as described above with respect to side links 162, 166, and 168.

[0063]

[0074] Figure 2A shows an exemplary wireless network structure 200. For example, 5GC210 (also called Next Generation Core (NGC)) can be functionally considered as control plane functions (C plane) 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions (U plane) 212 (e.g., UE gateway functions, access to data networks, IP routing, etc.), working collaboratively to form the core network. User plane interface (NG-U) 213 and control plane interface (NG-C) 215 connect gNB222 to 5GC210, in particular to user plane functions 212 and control plane functions 214, respectively. In an additional configuration, ng-eNB224 may also be connected to 5GC210 via NG-C215 to control plane functions 214 and NG-U213 to user plane functions 212. Furthermore, ng-eNB224 may communicate directly with gNB222 via backhaul connection 223. In some configurations, the next-generation RAN (NG-RAN) 220 may have only one or more gNB222s, while other configurations may include one or more of both ng-eNB224s and gNB222s. Either (or both) of the gNB222s or ng-eNB224s may communicate with a UE204 (for example, any of the UEs described herein). In one embodiment, two or more UE204s may communicate with each other via a wireless sidelink 242, which may correspond to the wireless sidelink 162 in Figure 1.

[0064]

[0075] Another optional embodiment may include a location server 230, which may communicate with 5GC210 to provide location assistance to UE204. The location server 230 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, each may correspond to a single server. The location server 230 may be configured to support one or more location services for UE204, which can be connected to the location server 230 via the core network, 5GC210, and / or the internet (not shown). Furthermore, the location server 230 may be incorporated into the core network components, or alternatively, be outside the core network.

[0065]

[0076] Figure 2B shows another exemplary wireless network structure 250. 5GC260 (which may correspond to 5GC210 in Figure 2A) can functionally be considered as control plane functions provided by the Access and Mobility Management Function (AMF) 264 and user plane functions provided by the User Plane Function (UPF) 262, working collaboratively to form the core network (i.e., 5GC260). The user plane interface 263 and the control plane interface 265 connect ng-eNB224 to 5GC260, specifically to UPF262 and AMF264, respectively. In an additional configuration, gNB222 may also be connected to 5GC260 via the control plane interface 265 to AMF264 and the user plane interface 263 to UPF262. Furthermore, ng-eNB224 may communicate directly with gNB222 via the backhaul connection 223, with or without gNB direct connectivity to 5GC260. In some configurations, the NG-RAN220 may have only one or more gNB222s, while other configurations may include one or more of both ng-eNB224s and gNB222s. The base station of the NG-RAN220 communicates with the AMF264 via the N2 interface and with the UPF262 via the N3 interface. Either (or both) of the gNB222 or ng-eNB224 may communicate with a UE204 (for example, any of the UEs described herein). In one embodiment, two or more UE204s may communicate with each other via a sidelink 242, which may correspond to sidelink 162 in Figure 1.

[0066]

[0077] The functions of AMF264 include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between UE204 and Session Management Function (SMF)266, transparent proxy service for routing SM messages, access authentication and access permission, transport for short message service (SMS) messages between UE204 and Short Message Service Function (SMSF) (not shown), and security anchor function (SEAF). AMF264 also interacts with Authentication Server Function (AUSF) (not shown) and UE204 and receives intermediate keys established as a result of the UE204 authentication process. In the case of authentication based on UMTS (Universal Mobile Telecommunications System) Subscriber Identification Module (USIM), AMF264 retrieves security materials from AUSF. The functions of AMF264 also include security context management (SCM). SCM receives keys from SEAF that it uses to derive access network-specific keys. The AMF264's functionality also includes location service management for regulatory services, transport for location service messages between the UE204 and the LMF270 acting as a location server 230, transport for location service messages between the NG-RAN220 and the LMF270, EPS bearer identifier allocation for interaction with Advanced Packet Systems (EPS), and UE204 mobility event notification. Furthermore, the AMF264 also supports functionality for non-3GPP® access networks.

[0067]

[0078] The functions of UPF262 include acting as an anchor point for intra-RAT mobility (when applicable), acting as an external protocol data unit (PDU) session point for interconnection to a data network (not shown), providing packet routing and forwarding, packet inspection, user plane policy rule enforcement (e.g., gating, redirection, traffic steering), lawful interception (user plane collection), traffic usage reporting, quality of service (QoS) handling for the user plane (e.g., uplink / downlink rate enforcement, reflective QoS marking on the downlink), uplink traffic verification (service data flow (SDF) vs. QoS flow mapping), transport level packet marking on the uplink and downlink, downlink packet buffering and downlink data notification triggering, and sending and forwarding one or more “termination markers” to the source RAN node. UPF262 may also support the forwarding of location service messages over the user plane between UE204 and location servers such as SLP272.

[0068]

[0079] The functions of the SMF266 ​​include session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering in the UPF262 for routing traffic to appropriate destinations, policy enforcement and some QoS control, and downlink data notification. The interface through which the SMF266 ​​communicates with the AMF264 is called the N11 interface.

[0069]

[0080] Another optional embodiment may include an LMF270 that may communicate with 5GC260 to provide location assistance to UE204. LMF270 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.) or alternatively, each corresponding to a single server. LMF270 may be configured to support one or more location services for UE204 that can connect to LMF270 via the core network, 5GC260, and / or via the internet (not shown). The SLP272 may support similar functionality to the LMF270, however, the LMF270 can communicate with the AMF264, NG-RAN220, and UE204 via the control plane (using interfaces and protocols intended for transmitting signaling messages rather than voice or data, for example), while the SLP272 can communicate with the UE204 and external clients (not shown in Figure 2B) via the user plane (using protocols intended for carrying voice and / or data, such as Transmission Control Protocol (TCP) and / or IP).

[0070]

[0081] Figure 3 shows an example of a wireless communication system 300 supporting wireless unicast sidelink establishment according to an aspect of this disclosure. In some examples, the wireless communication system 300 may implement aspects of wireless communication systems 100, 200, and 250. The wireless communication system 300 may include a first UE 302 and a second UE 304, which may be examples of any of the UEs described herein. In particular examples, UEs 302 and 304 may correspond to V-UE160 in Figure 1, UEs 190 and UEs 104 in Figure 1 connected via sidelink 192, or UEs 204 in Figures 2A and 2B.

[0071]

[0082] In the example in Figure 3, UE302 may attempt to establish a unicast connection via a sidelink with UE304, which may be a V2X sidelink between UE302 and UE304. In a specific example, the established sidelink connection may correspond to sidelinks 162 and / or 168 in Figure 1, or sidelink 242 in Figures 2A and 2B. Sidelink connections may be established over an omnidirectional frequency range (e.g., FR1) and / or a mmW frequency range (e.g., FR2). In some cases, UE302 may be called the initiating UE that starts the sidelink connection procedure, and UE304 may be called the target UE that is targeted by the sidelink connection procedure by the initiating UE.

[0072]

[0083] To establish a unicast connection, Access Layer (AS) parameters (a functional layer in the UMTS and LTE protocol stacks between the RAN and UE, which is part of Layer 2 and is responsible for transporting data over the wireless link and managing radio resources) can be configured and negotiated between UE302 and UE304. For example, transmit and receive capability matching can be negotiated between UE302 and UE304. Each UE may have different capabilities (e.g., transmit and receive, 64 quadrature amplitude modulation (QAM), transmit diversity, carrier aggregation (CA), supported communication frequency bands, etc.). In some cases, different services may be supported in the upper layers of the corresponding protocol stacks for UE302 and UE304. Furthermore, a security association can be established between UE302 and UE304 for the unicast connection. Unicast traffic may benefit from link-level security protections (e.g., integrity protection). Security requirements may differ for different wireless communication systems. For example, a V2X system and a Uu system may have different security requirements (e.g., Uu security does not include confidentiality protection). Furthermore, the IP configuration (e.g., IP version, address, etc.) may be negotiated for the unicast connection between UE302 and UE304.

[0073]

[0084] In some cases, UE304 may create a service announcement (e.g., a service capability message) to be transmitted over a cellular network (e.g., cV2X) to assist in establishing a sidelink connection. Traditionally, UE302 may identify and locate a candidate for sidelink communication based on a broadcasted basic service message (BSM) decrypted by a nearby UE (e.g., UE304). The BSM may include location information, security and identification information, and vehicle information (e.g., speed, operation, size, etc.) for the corresponding UE. However, for different wireless communication systems (e.g., D2D or V2X communication), a discovery channel may not be configured so that UE302 can discover (one or more) BSMs. Therefore, service announcements (e.g., discovery signals) transmitted by UE304 and other nearby UEs are higher-layer signals and may be broadcast (e.g., in an NR sidelink broadcast). In some cases, UE304 may include one or more parameters about itself in the service announcement, including the connectivity parameters and / or capabilities it possesses. UE302 may then monitor and receive broadcasted service announcements to identify potential UEs for the corresponding sidelink connection. In some cases, UE302 may identify potential UEs based on the capabilities that each UE indicates in their respective service announcements.

[0074]

[0085] A service announcement may include information to help UE302 (for example, or any initiating UE) identify the UE sending the service announcement (UE304 in the example in Figure 3). For example, a service announcement may include channel information if a direct communication request can be sent. In some cases, the channel information may be RAT-specific (for example, specific to LTE or NR) and may include the resource pool in which UE302 sends the communication request. Furthermore, a service announcement may include a specific destination address for the UE (for example, a Layer 2 destination address) if the destination address is different from the current address (for example, the address of the streaming provider or the UE sending the service announcement). A service announcement may also include the network or transport layer for which UE302 sends the communication request. For example, the network layer (also called "Layer 3" or "L3") or the transport layer (also called "Layer 4" or "L4") may indicate the application port number for the UE sending the service announcement. In some cases, IP addressing may not be required if the signaling (e.g., PC5 signaling) directly carries a protocol (e.g., Real-Time Transport Protocol (RTP)) or provides a locally generated random protocol. Furthermore, service announcements may include certain types of protocols for proof establishment and QoS relation parameters.

[0075]

[0086] After identifying a potential sidelink connection target (UE304 in the example in Figure 3), the initiating UE (UE302 in the example in Figure 3) may send a connection request 315 to the identified target UE304. In some cases, the connection request 315 may be a first RRC message (e.g., an "RRCDirectConnectionSetupRequest" message) sent by UE302 to request a unicast connection with UE304. For example, the unicast connection may utilize the PC5 interface for the sidelink, and the connection request 315 may be an RRC connection setup request message. Furthermore, UE302 may use a sidelink signaling radio bearer 305 to transport the connection request 315.

[0076]

[0087] After receiving connection request 315, UE304 may decide whether to accept or reject the connection request 315. UE304 may base this decision on transmit / receive capabilities, the ability to adapt to a unicast connection over a sidelink, specific services indicated for the unicast connection, content to be transmitted over the unicast connection, or a combination thereof. For example, if UE302 wishes to use a first RAT to transmit or receive data, but UE304 does not support the first RAT, UE304 may reject connection request 315. Additionally or alternatively, UE304 may reject connection request 315 based on the inability to adapt to a unicast connection over a sidelink due to limited radio resources, scheduling issues, etc. Therefore, UE304 may send an indication in connection response 320 whether the request is accepted or rejected. Similar to UE302 and connection request 315, UE304 may use the sidelink signaling radio bearer 310 to transport connection response 320. Furthermore, connection response 320 may be a second RRC message (for example, an "RRCDirectConnectionResponse" message) sent by UE304 in response to connection request 315.

[0077]

[0088] In some cases, sidelink signaling radio bearer 305 and sidelink signaling radio bearer 310 may be the same sidelink signaling radio bearer or may be separate sidelink signaling radio bearers. Therefore, the radio link control (RLC) layer acknowledgment mode (AM) may be used for sidelink signaling radio bearers 305 and 310. UEs supporting unicast connections may listen on the logical channels associated with the sidelink signaling radio bearers. In some cases, the AS layer (i.e., Layer 2) may pass information directly through RRC signaling (e.g., the control plane) instead of the V2X layer (e.g., the data plane).

[0078]

[0089] If the connection response 320 indicates that UE 304 has received the connection request 315, UE 302 may send a connection establishment 325 message on the sidelink signaling radio bearer 305 to indicate that the unicast connection setup is complete. In some cases, connection establishment 325 may be a third RRC message (e.g., an "RRCDirectConnectionSetupComplete" message). Each of the connection request 315, connection response 320, and connection establishment 325 may use basic capabilities to enable each UE to receive and decode the corresponding transmission (e.g., an RRC message) when they are being transported from one UE to the other.

[0079]

[0090] Furthermore, identifiers may be used for each of the connection request 315, connection response 320, and connection establishment 325. For example, the identifier may indicate which UE302 / 304 is sending which message and / or which UE302 / 304 the message is intended for. In physical (PHY) layer channels, the same identifier (e.g., Layer 2 ID) may be used for RRC signaling and subsequent data transmission. However, in logical channels, identifiers may be separate for RRC signaling and for data transmission. For example, on a logical channel, RRC signaling and data transmission may be treated differently and have different acknowledgment (ACK) feedback messaging. In some cases, physical layer ACKs may be used for RRC messaging to ensure that the corresponding messages are properly sent and received.

[0080]

[0091] For unicast connections, one or more informational elements may be included in the connection request 315 and / or connection response 320 for UE302 and / or UE304, respectively, to enable negotiation of corresponding AS layer parameters. For example, UE302 and / or UE304 may include PDCP parameters in the corresponding unicast connection setup message to set up the Packet Data Convergence Protocol (PDCP) context for the unicast connection. In some cases, the PDCP context may indicate whether PDCP replication is used for the unicast connection. Furthermore, UE302 and / or UE304 may include RLC parameters when establishing a unicast connection to set up the RLC context for the unicast connection. For example, the RLC context may indicate whether AM (e.g., t-reordering) or Unacknowledged Response (UM) mode is used for the RLC layer of the unicast communication.

[0081]

[0092] Furthermore, UE302 and / or UE304 may include MAC parameters to set a Media Access Control (MAC) context for a unicast connection. In some cases, the MAC context may enable a resource selection algorithm, a Hybrid Automatic Retransmission Request (HARQ) feedback scheme (e.g., ACK or Negative ACK (NACK) feedback), parameters for the HARQ feedback scheme, carrier aggregation, or a combination thereof for a unicast connection. Additionally, UE302 and / or UE304 may include PHY layer parameters when establishing a unicast connection to set a PHY layer context for the unicast connection. For example, the PHY layer context may specify the transmit format and radio resource configuration (e.g., bandwidth portion (BWP), numerology, etc.) for a unicast connection (unless a transmit profile is included for each UE302 / 304). These informational elements may be supported for different frequency range configurations (e.g., FR1 and FR2).

[0082]

[0093] In some cases, a security context may also be established for a unicast connection (for example, after the connection establishment 325 message has been sent). Sidelink signaling radio bearers 305 and 310 may not be protected before a security association (e.g., a security context) is established between UE302 and UE304. After the security association is established, sidelink signaling radio bearers 305 and 310 may be protected. Thus, a security context can enable unicast connections and secure data transmission over sidelink signaling radio bearers 305 and 310. Furthermore, IP layer parameters (e.g., link-local IPv4 or IPv6 addresses) may also be negotiated. In some cases, IP layer parameters may be negotiated by higher-layer control protocols that operate after RRC signaling is established (e.g., after a unicast connection is established). As described above, UE304 may base its decision on whether to accept or reject connection request 315 on specific services and / or content to be transmitted over the unicast connection (e.g., higher-layer information) that are instructed for the unicast connection. Specific services and / or content may also be instructed by higher-layer control protocols that operate after RRC signaling is established.

[0083]

[0094] After a unicast connection is established, UE302 and UE304 can communicate using the unicast connection via sidelink 330, where sidelink data 335 is transmitted between the two UE302 and UE304. Sidelink 330 may correspond to sidelinks 162 and / or 168 in Figure 1, and / or sidelink 242 in Figures 2A and 2B. In some cases, the sidelink data 335 may include RRC messages transmitted between the two UE302 and UE304. To maintain this unicast connection on sidelink 330, UE302 and / or UE304 may send keep-alive messages (e.g., "RRCDirectLinkAlive" messages, fourth RRC messages, etc.). In some cases, keep-alive messages may be triggered periodically or on demand (e.g., event-triggered). Thus, triggering and sending keep-alive messages may be invoked by UE302, or by both UE302 and UE304. As an addition or alternative, a MAC control element (CE) (defined, for example, via sidelink 330) may be used to monitor the status of a unicast connection on sidelink 330 and maintain that connection. When the unicast connection is no longer needed (for example, UE302 has moved far enough away from UE304), either UE302 and / or UE304 may initiate a release procedure to drop the unicast connection via sidelink 330. Consequently, subsequent RRC messages may not be sent between UE302 and UE304 over the unicast connection.

[0084]

[0095] Figure 4 is a block diagram showing various components of an exemplary UE400 according to aspects of this disclosure. In one aspect, UE400 may correspond to any of the UEs described herein. As a particular example, UE400 may be a V-UE, such as V-UE160 in Figure 1. For simplicity, the various features and functions shown in the block diagram of Figure 4 are connected to one another using a common data bus, which means that these various features and functions are operably coupled to one another. Those skilled in the art will recognize that other connections, mechanisms, features, functions, etc., may be provided and adapted as needed to operably couple and configure an actual UE. Furthermore, it should be recognized that one or more of the features or functions shown in the example of Figure 4 may be further subdivided, or two or more of the features or functions shown in Figure 4 may be combined.

[0085]

[0096] The UE400 may include at least one transceiver 404 connected to one or more antennas 402, the at least one transceiver 404 providing means (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) for communicating with other network nodes such as V-UEs (e.g., V-UE160), infrastructure access points (e.g., roadside access point 164), P-UEs (e.g., UE104), base stations (e.g., base station 102) via one or more communication links (e.g., communication link 120, side links 162, 166, 168, mmW communication link 184) via at least one designated RAT (e.g., cV2X or IEEE802.11p). The transceiver 404 may be configured in various ways to transmit and encode signals (e.g., messages, instructions, information, etc.) and, conversely, to receive and decode signals (e.g., messages, instructions, information, pilots, etc.) according to the designated RAT.

[0086]

[0097] As used herein, “transceiver” may, in some implementations, include at least one transmitter and at least one receiver in an integrated device (for example, implemented as transmitter and receiver circuits of a single communication device), in some implementations it may comprise a separate transmitter device and a separate receiver device, or in other implementations it may be implemented in other ways. In one embodiment, the transmitter may include or be coupled to a plurality of antennas (e.g., (one or more) antennas 402), such as an antenna array, enabling the UE400 to perform transmit “beamforming.” Similarly, the receiver may include or be coupled to a plurality of antennas (e.g., (one or more) antennas 402), such as an antenna array, enabling the UE400 to perform receive beamforming. In one embodiment, the (one or more) transmitters and the (one or more) receivers may share the same plurality of antennas (e.g., (one or more) antennas 402), so that the UE400 can receive or transmit only at a given time, rather than receiving and transmitting both simultaneously. In some cases, a transceiver may not provide both transmitting and receiving capabilities. For example, to reduce costs when full communication is not required, some designs may employ a low-performance receiver circuit (e.g., a receiver chip or similar circuit that simply provides low-level sniffing).

[0087]

[0098] The UE400 may also include a satellite positioning service (SPS) receiver 406. The SPS receiver 406 may be connected to one or more antennas 402 and may provide means for receiving and / or measuring satellite signals. The SPS receiver 406 may have any suitable hardware and / or software for receiving and processing SPS signals, such as Global Positioning System (GPS) signals. The SPS receiver 406 requests information and actions from other systems as appropriate and performs calculations necessary to determine the position of the UE400 using measurements obtained by any suitable SPS algorithm.

[0088]

[0099] One or more sensors 408 may be coupled to a processing system 410 and may provide means for sensing or detecting information relating to the state and / or environment of the UE400, such as speed, direction (e.g., compass direction), headlight status, and gas mileage. For example, one or more sensors 408 may include a speedometer, tachometer, accelerometer (e.g., a microelectromechanical system (MEMS) device), gyroscope, geomagnetic sensor (e.g., compass), altimeter (e.g., barometric altimeter), and the like.

[0089]

[0100] The processing system 410 may include one or more microprocessors, microcontrollers, ASICs, processing cores, digital signal processors, etc., that provide processing functions as well as other computing and control functions. Thus, the processing system 410 may also be referred to as a processor, one or more processors, or at least one processor. The processing system 410 may therefore provide means for processing, such as means for determining, means for computing, means for receiving, means for transmitting, and means for directing. The processing system 410 may include any form of logic suitable for implementing at least the techniques described herein or for having the components of the UE400 implement them.

[0090]

[0101] The processing system 410 may also be coupled to a memory 414 that provides means for storing data and software instructions (including means for retrieving, maintaining, etc.) for executing functions programmed within the UE 400. The memory 414 may be mounted on the processing system 410 (for example, in the same integrated circuit (IC) package), and / or the memory 414 may be outside the processing system 410 and functionally coupled via a data bus.

[0091]

[0102] The UE400 may include a user interface 450 that provides any preferred interface system, such as a microphone / speaker 452, a keypad 454, and a display 456, enabling user interaction with the UE400. The microphone / speaker 452 may provide voice communication services with the UE400. The keypad 454 may have any preferred buttons for user input to the UE400. The display 456 may have any preferred display, such as a backlit liquid crystal display (LCD), and may further include a touchscreen display for additional user input modes. The user interface 450 may therefore be means for providing instructions to the user (e.g., audible and / or visual instructions) and / or for receiving user input (e.g., via user activation of sensing devices such as a keypad, touchscreen, microphone).

[0092]

[0103] In one embodiment, the UE400 may include a sidelink manager 470 coupled to the processing system 410. The sidelink manager 470 may be a hardware, software, or firmware component that, when executed, causes the UE400 to perform the operations described herein. For example, the sidelink manager 470 may be a software module stored in memory 414 and executable by the processing system 410. As another example, the sidelink manager 470 may be hardware circuitry within the UE400 (e.g., an ASIC, a field-programmable gate array (FPGA), etc.).

[0093]

[0104] Figures 5A and 5B illustrate two methods for single-cell UE positioning that can be implemented when a cell contains multiple UEs engaged in SL communication. In Figures 5A and 5B, the UE transmitting SL-PRS may be referred to as "TxUE," and the UE receiving SL-PRS may be referred to as "RxUE." The methods shown in Figures 5A and 5B have the technical advantage of not requiring any uplink transmission and saving power.

[0094]

[0105] In Figure 5A, relay UE 500 (which has a known location) participates in positioning estimation of remote UE 502 without having to perform any UL PRS transmission to base station 504 (e.g., gNB). As shown in Figure 5A, remote UE 502 receives DL-PRS from BS504 and transmits SL-PRS to relay UE 500. This SL-PRS transmission from remote UE 502 can be low power because it does not need to reach BS504 and only needs to reach the nearby relay UE 500.

[0095]

[0106] In Figure 5B, multiple relay UEs, including relay UE500 acting as the first relay UE and relay UE506 acting as the second relay UE, transmit SL-PRS signals (SL-PRS1 and SL-PRS2, respectively) to remote UE502. In contrast to the method shown in Figure 5A, where remote UE502 is the TxUE and relay UE500 is the RxUE, in Figure 5B their roles are reversed, with relay UE500 and relay UE506 being the TxUEs and remote UE502 being the RxUE. In this scenario as well, the SL-PRS signals transmitted by the TxUEs can be low power and UL communication is not required.

[0096]

[0107] However, there are several technical challenges. For example, the accuracy of wireless-based positioning can be significantly affected by non-line-of-sight (NLOS) multipath propagation, which is unavoidable in some scenarios, such as urban areas and typical indoor environments. Distance / range estimation (e.g., by ToA measurement) is difficult in NLOS multipath propagation channels as the first path is not detected. At low SNR ranges, low-power first paths may not be properly detected by receivers. Therefore, the technical challenge is how to enhance the ability to detect the first arrival path in NLOS multipath channels under low SNR conditions.

[0097]

[0108] Referring back to Figures 5A and 5B, communication between TxUE and RxUE can occur under NLOS multipath channel conditions with a low SNR. Therefore, SL-PRS transmission from TxUE to RxUE may benefit from techniques that improve the SNR.

[0098]

[0109] To address the aforementioned technical challenges, several techniques for improving the SNR of sidelink transmissions, including SL transmissions for positioning, are presented herein. More specifically, the technique of time reversal (TR) precoding for sidelink-based positioning is presented herein. In TR precoding, the transmitted reference signal is pre-filtered with a time-reversal channel impulse response (CIR) between the UE and BS. This is expressed by the following equation:

[0099]

number

[0100] S is the unfiltered reference signal. t This is a pre-filtered reference signal, h(-t) * This is a time-reversal filter, which is the time-reversed CIR between the UE and BS. The resulting received signal is described as follows:

[0101]

number

[0102] On the receiving end, the equivalent CIR is the convolution of the time-reversed channel and the actual channel, which means the following:

[0103]

number

[0104] This is the autocorrelation of the channel. Calculating the equivalent channel has the effect of compressing the channel. Therefore, TR precoding compresses multipath channels, thereby improving the signal-to-noise ratio (SNR) and, in particular, the accuracy of the time-of-arrival (ToA) estimation.

[0105]

[0110] Precoding a signal transmitted based on channel conditions assumes that channels are reciprocal, meaning that a one-way transmission (e.g., BS to UE) has the same channel conditions as a reverse transmission (e.g., UE to BS). Due to channel reciprocity, h(t) and h(-t) * It can be assumed that there is a high degree of correlation between them. TR precoding needs to reflect the channel between the transmitter and receiver, and is therefore usually based on channel status information (CSI). However, the current specification does not consider the use of TR precoding for SL communication, much less the scenarios shown in Figures 5A and 5B.

[0106]

[0111] Figure 6 is a flowchart of an exemplary process 600 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. In some aspects, one or more process blocks in Figure 6 may be performed by a first user equipment (UE) (e.g., UE104 in Figure 1). In some aspects, one or more process blocks in Figure 6 may be performed by a device or group of devices separate from or including the first user equipment (UE). Additionally or alternatively, one or more process blocks in Figure 6 may be performed by one or more components of device 400, such as a processing system 410, a transceiver 404, a memory 414, a user interface 450, and / or a sidelink manager 470, any or all of which may be considered means for performing this operation.

[0107]

[0112] As shown in Figure 6, process 600 may include deriving a time-reversed (TR) precoder based at least partially on an estimated channel between the first UE and the second UE (block 610). Means for performing the operation in block 610 may include a processing system 410 for UE400. For example, the processing system 410 for UE400 may estimate a channel based on a signal sent by another UE and received by UE400, and compute a filter that precodes the signal using a time-reversed version of the channel's impulse response before transmitting the signal over the same channel. The estimated channel may be an SL communication channel, for example, a channel whose spectrum is designated for DL ​​transmission and reception, and will undergo some resource allocation process, different from the unlicensed spectrum of WIFI or other technologies.

[0108]

[0113] As further shown in Figure 6, process 600 may also include sending a TR-precoded sidelink (SL) positioning reference signal (PRS) to a second UE (block 620). Means for performing the operation in block 610 may include the transceiver 404 of UE 400 and the processing system 410. For example, the processing system 410 of UE 400 may TR-precode the transmitted SL-PRS signal, and the transceiver 404 of UE 400 may send the TR-precoded SL-PRS to the second UE.

[0109]

[0114] Process 600 may include additional embodiments, such as any single embodiment or any combination of embodiments described below, and / or relating to one or more other processes described elsewhere herein. Figure 6 shows an exemplary block of Process 600, but in some embodiments, Process 600 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently from the block shown in Figure 6. As an addition or alternative, two or more blocks of Process 600 may be carried out in parallel.

[0110]

[0115] As will be explained in more detail in Figures 7-9 below, there are many ways in which a TR precoder can be derived.

[0111]

[0116] Figure 7 is a messaging and event diagram illustrating a process 700 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. Figure 7 shows block 610 of Figure 6 in more detail. As shown in Figure 7, in some aspects, deriving a TR precoder based at least partially on an estimated channel between a first UE (TxUE702) and a second UE (RxUE704) (block 610) comprises the following steps: TxUE702 sends a wideband (WB) RS to RxUE704 (block 706). RxUE704 measures the WB RS and determines the CSI at least partially on the WB RS (block 708). Optionally, TxUE702 sends a trigger message, such as an SCI message, to RxUE704 to request CSI information (block 709). TxUE702 receives the CSI associated with the WB RS from RxUE704 (block 710). In some embodiments, the CSI is sent by RxUE704 in response to an arbitrary trigger message in block 709. Alternatively, the CSI is sent in response to the reception of the WB RS in block 706. TxUE702 estimates the channel between TxUE702 and RxUE704 based at least partially on the CSI (block 712). TxUE702 derives the TR precoder based at least partially on the estimated channel between TxUE702 and RxUE704. In the example shown in Figure 7, TxUE702 then sends the TR-precoded SL-PRS to RxUE704 (block 620). In the example shown in Figure 7, RxUE704 can then perform positioning operations, such as determining the ToA for the TR-precoded SL-PRS (block 714).

[0112]

[0117] In some embodiments, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS (e.g., a broadband reference signal transmitted by the UE rather than the BS or gNB). In some embodiments, the WB RS is associated with at least one SL-PRS. The WB RS is used to characterize the sidelink channel and to determine the TR precoder from the channel estimate, and is aware that the channel may change in time or frequency, so it is useful when the WB RS and SL-PRS are close to each other in terms of time, frequency, or both. For example, the WB RS and SL-PRS may be considered temporally close if they are separated by less than a threshold duration. The threshold duration may be set based on channel conditions, e.g., how quickly the channel characteristics change over time, UE mobility, e.g., how fast or slow the UE is moving if it is, and other considerations. Thus, in some embodiments, the WB RS and SL-PRS may be considered close to each other if they are in the same slot, in adjacent slots, or in other predetermined intervals in the time domain. Similarly, WB RS and SL-PRS may be considered close in frequency if they are on the same subcarrier or separated by a threshold number of subcarriers. The threshold number of subcarriers can be set based on channel characteristics, UE capabilities, and other considerations. Thus, in some embodiments, WB RS and SL-PRS may be considered close to each other if they are on the same resource block, adjacent resource block, or other predefined separations in the frequency domain.

[0113]

[0118] In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission. In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof. In some embodiments, the CSI is received from a second UE via a physical sidelink shared channel (PSSCH). In some embodiments, the CSI is associated with a specific SL-PRS resource. In some embodiments, the CSI is associated with a channel sounding RS for CSI-RS feedback. In some embodiments, the CSI is received aperiodically. In some embodiments, the CSI is received in response to a trigger message sent from a first UE to a second UE. In some embodiments, the trigger message comprises a sidelink control information (SCI) message.

[0114]

[0119] Figure 8 is a messaging and event diagram illustrating a process 800 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. Figure 8 shows block 610 of Figure 6 in more detail. As shown in Figure 8, in some aspects, deriving a TR precoder based at least partially on an estimated channel between a first UE (TxUE702) and a second UE (RxUE704) (block 610) comprises the following steps: TxUE702 sends a wideband (WB) RS to RxUE704 (block 802). RxUE704 measures the WB RS and determines the CSI based at least partially on the WB RS (block 804). RxUE704 derives a TR precoder, for example, at least partially on the CSI (block 806). TxUE702 receives the TR precoder from RxUE704 (block 808). In the example shown in Figure 8, TxUE702 transmits the TR-precoded SL-PRS to RxUE704 (block 620). Although not shown in Figure 8, RxUE704 can then perform positioning operations, such as determining the ToA of the TR-precoded SL-PRS.

[0115]

[0120] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS. In some embodiments, the WB RS is associated with at least one SL-PRS. In some embodiments, the WB RS is located within a threshold distance of a TR-precoded SL-PRS in the time domain, frequency domain, or both.

[0116]

[0121] Figure 9 is a messaging and event diagram illustrating a process 900 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. Figure 9 shows block 610 of Figure 6 in more detail. As shown in Figure 9, in some aspects deriving a TR precoder based at least in part on an estimated channel between a first UE (TxUE702) and a second UE (RxUE704) (block 610) comprises the following steps: TxUE702 may optionally send a trigger message to RxUE704 that triggers RxUE704 to generate a WB RS toward TxUE702 (block 902). In some aspects the trigger may be a sidelink control information (SCI) message. As shown in Figure 9, RxUE704 sends a WB RS to TxUE702 (block 904). Next, TxUE702 can estimate the channel from RxUE704 to TxUE702, for example, by measuring the WB RS and determining the CSI (block 906). In some embodiments, TxUE702 then derives a TR precoder based on the estimated channel between RxUE704 and TxUE702, for example (block 908). In the example shown in Figure 9, TxUE702 transmits the TR-precoded SL-PRS to RxUE704 (block 620). Although not shown in Figure 9, RxUE704 can then perform a positioning operation, for example, determining the ToA of the TR-precoded SL-PRS.

[0117]

[0122] In some embodiments, the WB RS is received in response to a trigger message sent from a first UE to a second UE. In some embodiments, the trigger message comprises a sidelink control information (SCI) message. In some embodiments, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS. In some embodiments, the WB RS is associated with at least one SL-PRS.

[0118]

[0123] Figure 10 is a flowchart of an exemplary process 1000 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. In some aspects, one or more process blocks in Figure 6 may be performed by a first user equipment (UE) (e.g., UE 104 in Figure 1). In some aspects, one or more process blocks in Figure 6 may be performed by a device or group of devices separate from or including the first user equipment (UE). Additionally or alternatively, one or more process blocks in Figure 6 may be performed by one or more components of device 400, such as a processing system 410, a transceiver 404, a memory 414, a user interface 450, and / or a sidelink manager 470, any or all of which may be considered means for performing this operation.

[0119]

[0124] As shown in Figure 10, process 1000 may include receiving a wideband reference signal (WB RS) from a second UE (block 1010). Means for performing the operation in block 1010 may include the transceiver 404 of UE 400 and the processing system 410. For example, UE 400 may receive the WB RS via the transceiver 404 as described above. In some embodiments, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS. In some embodiments, the WB RS is in proximity to a TR-precoded SL-PRS in time, frequency, or both. In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0120]

[0125] Furthermore, as shown in Figure 10, process 1000 may include determining channel status information (CSI) based at least partially on WB RS (block 1020). Means for performing the operation in block 1020 may include the processing system 410 and the sidelink manager 470 of UE400. For example, the processing system 410 of UE400 may determine channel status information (CSI) based at least partially on WB RS, as described above.

[0121]

[0126] Furthermore, as shown in Figure 10, process 1000 may include sending a CSI to a second UE (block 1030). Means for performing the operation in block 1030 may include the transceiver 404 and processing system 410 of UE 400. For example, the processing system 410 of UE 400 may instruct the transceiver 404 to send a CSI to the second UE, as described above. In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission. In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof. In some embodiments, the CSI is sent to the second UE via a physical sidelink shared channel (PSSCH). In some embodiments, the CSI is associated with a specific SL-PRS resource. In some embodiments, the CSI is associated with a channel sounding RS for CSI-RS feedback. In some embodiments, the CSI is sent aperiodically. In some embodiments, the CSI is sent in response to the receipt of a trigger message from a second UE. In some embodiments, the receipt of a trigger message comprises the receipt of a sidelink control information (SCI) message.

[0122]

[0127] Furthermore, as shown in Figure 10, process 1000 may optionally include receiving a TR-precoded SL-PRS from a second UE (block 1040). Means for performing the operation in block 1040 may include the transceiver 404 of UE 400 and the processing system 410. For example, UE 400 can receive a TR-precoded SL-PRS via the transceiver 404.

[0123]

[0128] Furthermore, as shown in Figure 10, process 1000 may optionally include performing a positioning operation using a TR-precoded SL-PRS (block 1050). Means for performing the operation in block 1050 may include the transceiver 404 and processing system 410 of the UE400. For example, the UE400 can use information collected from the TR-precoded SL-PRS to calculate its location.

[0124]

[0129] Process 1000 may include additional embodiments, such as any single embodiment or any combination of embodiments described below, and / or relating to one or more other processes described elsewhere in this specification. Figure 10 shows an example of blocks of Process 1000, but in some embodiments, Process 1000 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently from the blocks shown in Figure 10. As an addition or alternative, two or more blocks of Process 1000 may be carried out in parallel.

[0125]

[0130] Figure 11 is a flowchart of an exemplary process 1100 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. In some aspects, one or more process blocks in Figure 6 may be performed by a first user equipment (UE) (e.g., UE 104 in Figure 1). In some aspects, one or more process blocks in Figure 6 may be performed by a device or group of devices separate from or including the first user equipment (UE). Additionally or alternatively, one or more process blocks in Figure 6 may be performed by one or more components of device 400, such as a processing system 410, a transceiver 404, a memory 414, a user interface 450, and / or a sidelink manager 470, any or all of which may be considered means for performing this operation.

[0126]

[0131] As shown in Figure 11, process 1100 may include receiving a wideband (WB) reference signal (RS) from a second UE (block 1110). Means for performing the operation in block 1110 may include the transceiver 404 of UE 400 and the processing system 410. For example, UE 400 can receive the WB RS via the transceiver 404 as described above. In some embodiments, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

[0127]

[0132] Furthermore, as shown in Figure 11, process 1100 may also include estimating the channel between the second UE and the first UE based at least partially on the WB RS (block 1120). Means for performing the operation in block 1120 may include a processing system 410 for the UE 400. For example, the UE 400 can use the processing system 410, as described above, to estimate the channel between the UE 400 itself and the second UE based at least partially on the WB RS.

[0128]

[0133] Furthermore, as shown in Figure 11, process 1100 may include deriving a time-reverse (TR) precoder based on the estimated channels (block 1130). Means for performing the operation in block 1130 may include the processing system 410 of UE400. For example, UE400 can use the processing system 410, as described above, to derive a time-reverse (TR) precoder based on the estimated channels.

[0129]

[0134] Furthermore, as shown in Figure 11, process 1100 may also include sending the TR precoder to a second UE (block 1140). Means for performing the operation in block 1140 may include the transceiver 404 and processing system 410 of UE 400. For example, the processing system 410 of UE 400 can instruct the transceiver 404 to send the TR precoder to the second UE, as described above.

[0130]

[0135] Furthermore, as shown in Figure 11, process 1100 may optionally include receiving a TR-precoded SL-PRS from a second UE (block 1150). Means for performing the operation in block 1140 may include the transceiver 404 of UE 400 and the processing system 410. For example, UE 400 can receive a TR-precoded SL-PRS via the transceiver 404 as described above. In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in time, frequency, or both. In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0131]

[0136] Furthermore, as shown in Figure 11, process 1100 may optionally include performing a positioning system using TR-precoded SL-PRS (block 1160). Means for performing the operation in block 1140 may include the processing system 410 of UE400. For example, UE400 can use information collected from TR-precoded SL-PRS to calculate its location.

[0132]

[0137] Process 1100 may include additional embodiments, such as any single embodiment or any combination of embodiments described below, and / or relating to one or more other processes described elsewhere in this specification. Figure 11 shows an exemplary block of Process 1100, but in some embodiments, Process 1100 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently from the block shown in Figure 11. As an addition or alternative, two or more blocks of Process 1100 may be carried out in parallel.

[0133]

[0138] Figure 12 of the UE is a flowchart of an exemplary process 1200 related to TR precoding for SL-based positioning according to an aspect of the present disclosure. In some aspects, one or more process blocks in Figure 6 may be performed by a first user equipment (UE) (e.g., UE 104 in Figure 1). In some aspects, one or more process blocks in Figure 6 may be performed by a device or group of devices separate from the first user equipment (UE), or including the first user equipment (UE). Additionally or alternatively, one or more process blocks in Figure 6 may be performed by one or more components of device 400, such as a processing system 410, a transceiver 404, a memory 414, a user interface 450, and / or a sidelink manager 470, any or all of which may be considered means for performing this operation.

[0134]

[0139] As shown in Figure 12, process 1200 may include sending a wideband reference signal (WB RS) to a second UE (block 1210) and receiving a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS) from the second UE (block 1220). Means for performing the operations in blocks 1210 and 1220 may include a transceiver 404 of UE 400 and a processing system 410. For example, the processing system 410 may instruct the transceiver 404 to send the WB RS to the second UE, and the transceiver 404 may receive the TR-precoded SL-PRS as described above. In some embodiments, the WB RS is sent in response to the receipt of a trigger message from the second UE. In some embodiments, the receipt of a trigger message comprises the receipt of a sidelink control information (SCI) message. In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS. In some embodiments, the WB RS is in proximity to a TR-precoded SL-PRS in time, frequency, or both. In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0135]

[0140] As shown in Figure 12, process 1200 may optionally include performing a positioning operation using a TR-precoded SL-PRS (block 1230). Means for performing the operation in block 1230 may include the processing system 410 of UE400. For example, UE400 can use information collected from the TR-precoded SL-PRS to calculate its location.

[0136]

[0141] Process 1200 may include additional embodiments, such as any single embodiment or any combination of embodiments described below, and / or relating to one or more other processes described elsewhere in this specification. Figure 12 shows an exemplary block of Process 1200, but in some embodiments, Process 1200 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently from the block shown in Figure 12. As an addition or alternative, two or more blocks of Process 1200 may be carried out in parallel.

[0137]

[0142] Additional embodiments include, but are not limited to, the following:

[0138]

[0143] In one embodiment, the first UE comprises means for deriving a TR precoder based at least partially on an estimated channel between the first UE and the second UE, and means for sending the TR precoded SL-PRS to the second UE.

[0139]

[0144] In another embodiment, the first UE comprises means for receiving WB RS from the second UE, means for determining the CSI based at least in part on the WB RS, and means for sending the CSI to the second UE.

[0140]

[0145] In another embodiment, the first UE includes means for receiving WB RS from the second UE, means for estimating a channel between the second UE and the first UE based at least partially on the WB RS, means for deriving a TR precoder based on the estimated channel, and means for sending the TR precoder to the second UE.

[0141]

[0146] In another embodiment, the first UE includes means for sending a WB RS to a second UE and means for receiving a TR-precoded SL-PRS from the second UE.

[0142]

[0147] In another embodiment, a non-temporary computer-readable medium stores a set of instructions, the set of instructions comprising one or more instructions, which, when executed by one or more processors of a first UE, cause the first UE to derive a TR precoder based at least partially on an estimated channel between the first UE and the second UE, and to send a TR-precoded SL-PRS to the second UE.

[0143]

[0148] In another embodiment, a non-temporary computer-readable medium stores a set of instructions, the set of instructions comprising one or more instructions, when one or more instructions are executed by one or more processors of a first user UE, causing the first UE to receive a WB RS from a second UE, to determine a CSI based at least partially on the WB RS, and to send the CSI to the second UE.

[0144]

[0149] In another embodiment, a non-temporary computer-readable medium stores a set of instructions, the set of instructions comprising one or more instructions, when one or more instructions are executed by one or more processors of a first user UE, causing the first UE to receive a WB RS from a second UE, estimating a channel between the second UE and the first UE based at least partially on the WB RS, deriving a TR precoder based on the estimated channel, and sending the TR precoder to the second UE.

[0145]

[0150] In another embodiment, a non-temporary computer-readable medium stores a set of instructions, the set of instructions comprising one or more instructions, which, when executed by one or more processors of a first UE, cause the first UE to send a WB RS to a second UE and receive a TR-precoded SL-PRS from the second UE.

[0146]

[0151] The detailed explanation above shows that different features are grouped together in the examples. This format of disclosure should not be understood as an intention that the exemplary clauses have more features than those explicitly stated in each clause. Rather, the various aspects of this disclosure may contain fewer features than all features of the individual exemplary clauses disclosed. Accordingly, the following clauses should be considered incorporated herein, and each clause may exist as a separate example by itself. Each dependent clause may, in the clause, refer to a specific combination with one of the other clauses, but the (one or more) aspects of that dependent clause are not limited to a specific combination. It will be understood that other exemplary clauses may also include combinations of (one or more) dependent clause aspects with the subject matter of any other dependent or independent clause, or any combination of features with other dependent and independent clauses. The various aspects disclosed herein explicitly include certain combinations (for example, contradictory aspects such as defining an element as both an insulator and a conductor) unless it is explicitly stated or easily inferred that such combinations are not intended. Furthermore, it is also intended that the form of the clause may be included in any other independent clause, even if that clause is not directly subordinate to that independent clause.

[0147]

[0152] Examples of the embodiments are described in the following numbered clauses.

[0148]

[0153] Clause 1. A method of wireless communication performed by a first user device (UE), comprising: deriving a time-reverse (TR) precoder at least in part on an estimated channel between the first UE and a second UE; and sending a TR-precoded sidelink positioning reference signal (SL-PRS) to the second UE.

[0149]

[0154] Clause 2. The method according to Clause 1, comprising deriving a time-reverse (TR) precoder at least partially on an estimated channel between a first UE and a second UE, or deriving a TR precoder at least partially on a transmit or receive on a sidelink (SL) communication channel between a first UE and a second UE.

[0150]

[0155] The method according to any one of Clauses 1 to 2, wherein deriving a TR precoder at least in part on an estimated channel between a first UE and a second UE comprises sending a wideband reference signal (WB RS) to the second UE, receiving channel status information (CSI) associated with the WB RS from the second UE, estimating a channel between the first UE and the second UE at least in part on the CSI, and deriving a TR precoder at least in part on an estimated channel between the first UE and the second UE.

[0151]

[0156] Clause 4. The method according to Clause 3, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), channel-sounding RS, or WB beacon RS.

[0152]

[0157] Clause 5. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 3 to 4.

[0153]

[0158] Clause 6. The WB RS is associated with at least one other SL-PRS, as described in any of Clauses 3 to 5.

[0154]

[0159] Clause 7. The method of any of Clauses 3 to 6, wherein the CSI is a positioning CSI used for positioning rather than data transmission.

[0155]

[0160] Clause 8. The CSI comprises a complete or partial channel impulse response (CIR), a complete or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof, in any manner from Clauses 3 to 7.

[0156]

[0161] Clause 9. The CSI is received from the second UE via a physical sidelink shared channel (PSSCH) as described in any of Clauses 3 to 8.

[0157]

[0162] Clause 10. A CSI is associated with a specific SL-PRS resource in any of the manner described in Clauses 3 through 9.

[0158]

[0163] Clause 11. The method described in any of Clauses 3 through 10, relating the CSI to the Channel Sounding RS for CSI-RS feedback.

[0159]

[0164] Clause 12. CSI is received aperiodically, in any manner described in Clauses 3 through 11.

[0160]

[0165] Clause 13. The CSI is received in response to sending a trigger message to the second UE, as described in Clause 12.

[0161]

[0166] Clause 14. The method of Clause 13, wherein sending a trigger message comprises sending a side link control information (SCI) message.

[0162]

[0167] Clause 15. Deriving a TR precoder based at least in part on an estimated channel between a first UE and a second UE is any method of Clauses 1 to 14, comprising sending a wideband reference signal (WB RS) to the second UE and receiving a TR precoder from the second UE.

[0163]

[0168] Clause 16. The method of Clause 15, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), channel-sounding RS, or WB beacon RS.

[0164]

[0169] Clause 17. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 15 to 16.

[0165]

[0170] Clause 18. WB RS is associated with at least one other SL-PRS, as described in any of Clauses 15 to 17.

[0166]

[0171] Clause 19. Deriving a TR precoder at least partially based on an estimated channel between a first UE and a second UE is any method of Clauses 1 to 18, comprising: receiving a wideband reference signal (WB RS) from a second UE; estimating a channel between a first UE and a second UE at least partially based on the WB RS; and deriving a TR precoder at least partially based on the estimated channel between a first UE and a second UE.

[0167]

[0172] Clause 20. The WB RS is received in response to the first UE sending a trigger message to the second UE, as described in Clause 19.

[0168]

[0173] Clause 21. The method according to Clause 20, wherein sending a trigger message comprises sending a sidelink control information (SCI) message.

[0169]

[0174] Clause 22. WB RS comprising a side-link positioning reference signal (SL-PRS), channel-sounding RS, or WB beacon RS, as described in any of Clauses 19 to 21.

[0170]

[0175] Clause 23. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 19 to 22.

[0171]

[0176] Clause 24. WB RS is associated with at least one other SL-PRS, as described in any of Clauses 19 to 23.

[0172]

[0177] Clause 25. A method of wireless communication performed by a first user device (UE), the method comprising: receiving a wideband reference signal (WB RS) from a second UE; determining channel status information (CSI) at least in part based on the WB RS; and sending the CSI to the second UE.

[0173]

[0178] Clause 26. The method of Clause 25, further comprising receiving a TR-precoded sidelink positioning reference signal (SL-PRS) from a second UE.

[0174]

[0179] The method of Clause 26, further comprising performing a positioning operation using a TR-precoded SL-PRS.

[0175]

[0180] Clause 28. WB RS comprising a side-link positioning reference signal (SL-PRS), channel-sounding RS, or WB beacon RS, as described in any of Clauses 25 to 27.

[0176]

[0181] Clause 29. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 25 to 28.

[0177]

[0182] Clause 30. A WB RS is associated with at least one other SL-PRS, as described in any of Clauses 25 to 29.

[0178]

[0183] Clause 31. The method of any of Clauses 25 to 30, wherein the CSI is a positioning CSI used for positioning rather than data transmission.

[0179]

[0184] Clause 32. The CSI comprises a complete or partial channel impulse response (CIR), a complete or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof, in any manner from Clauses 25 to 31.

[0180]

[0185] Clause 33. The CSI is sent to the second UE via a physical sidelink shared channel (PSSCH) as described in any of Clauses 25 to 32.

[0181]

[0186] Clause 34. A CSI is associated with a specific SL-PRS resource in any of the manner described in Clauses 25 through 33.

[0182]

[0187] Clause 35. CSI is associated with channel sounding RS for CSI-RS feedback, as described in any of Clauses 25 to 34.

[0183]

[0188] Clause 36. CSIs are sent aperiodically, in any manner described in any of Clauses 25 through 35.

[0184]

[0189] Clause 37. A CSI is sent in response to the receipt of a trigger message from a second UE, as described in Clause 36.

[0185]

[0190] Clause 38. The method according to Clause 37, comprising receiving a trigger message, which includes receiving a side-link control information (SCI) message.

[0186]

[0191] Clause 39. A method of wireless communication performed by a first user device (UE), the method comprising: receiving a wideband (WB) reference signal (RS) from a second UE; estimating a channel between the second UE and the first UE based at least in part on the WB RS; deriving a time-reverse (TR) precoder based on the estimated channel; and sending the TR precoder to the second UE.

[0187]

[0192] Clause 40. The method according to Clause 39, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), channel-sounding RS, or WB beacon RS.

[0188]

[0193] Clause 41. The method of any one of Clauses 39 to 40, further comprising receiving a TR-precoded side-link positioning reference signal (SL-PRS) from a second UE.

[0189]

[0194] The method of Clause 41, further comprising performing a positioning operation using a TR-precoded SL-PRS.

[0190]

[0195] Clause 43. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 41 to 42.

[0191]

[0196] Clause 44. A WB RS is associated with at least one other SL-PRS, as described in any of Clauses 41 to 43.

[0192]

[0197] Clause 45. A method of wireless communication performed by a first user device (UE), the method comprising sending a wideband reference signal (WB RS) to a second UE and receiving a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS) from the second UE.

[0193]

[0198] The method of Clause 45, further comprising performing a positioning operation using a TR-precoded SL-PRS.

[0194]

[0199] Clause 47. WB RS is sent in response to the receipt of a trigger message from the second UE, as described in any of Clauses 45 to 46.

[0195]

[0200] Clause 48. The method of Clause 47, wherein receiving a trigger message comprises receiving a side-link control information (SCI) message.

[0196]

[0201] Clause 49. WB RS comprising a side-link positioning reference signal (SL-PRS), channel sounding RS, or WB beacon RS, as described in any of Clauses 45 to 48.

[0197]

[0202] Clause 50. The WB RS is in close proximity to the TR-precoded SL-PRS in terms of time, frequency, or both, as described in any of Clauses 45 to 49.

[0198]

[0203] Clause 51. A WB RS is associated with at least one other SL-PRS, as described in any of Clauses 45 to 50.

[0199]

[0204] Clause 52. An apparatus comprising memory and at least one processor communicatively coupled to the memory, wherein the memory and at least one processor are configured to perform the method described in any of Clauses 1 to 51.

[0200]

[0205] Clause 53. An apparatus comprising means for carrying out the method described in any of Clauses 1 to 51.

[0201]

[0206] Clause 54. A non-temporary computer-readable medium for storing computer-executable instructions, wherein the computer-executable instructions include at least one instruction causing a computer or processor to perform the method described in any of Clauses 1 to 51.

[0202]

[0207] Those skilled in the art will understand that information and signals can be represented using any of the various different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description can be represented by voltage, electric current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

[0203]

[0208] Furthermore, those skilled in the art will understand that the various exemplary logic blocks, modules, circuits, and algorithmic steps described in relation to the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. To clearly demonstrate this hardware-software compatibility, various exemplary components, blocks, modules, circuits, and steps have been described above in general terms of their function. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functions in various ways for each specific application, but such determination of embodiments should not be construed as resulting in a departure from the scope of this disclosure.

[0204]

[0209] The various exemplary logic blocks, modules, and circuits described in relation to the embodiments disclosed herein may be implemented or carried out using general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other such configuration.

[0205]

[0210] The methods, sequences, and / or algorithms described in relation to the embodiments disclosed herein may be implemented directly in hardware, in software modules executed by a processor, or in a combination of both. The software modules may reside in random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM®), registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated with the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., a UE). Alternatively, the processor and storage medium may reside as separate components in a user terminal.

[0206]

[0211] In one or more exemplary embodiments, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via computer-readable media as one or more instructions or codes. Computer-readable media include both computer storage media and computer communication media, including any media that facilitates the transfer of computer programs from one location to another. Storage media can be any available media accessible by a computer. Such computer-readable media may include, but not exclusively, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other media that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also appropriately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of a medium. As used herein, disk and disc include compact disc (CD), laserdisc (disc), optical disc (disc), digital versatile disc (disc) (DVD), floppy disk (disc), and Blu-ray (disc), where disk typically reproduces data magnetically and disc optically reproduces data by laser. Any combination of the above should also be included within the scope of computer-readable media.

[0207]

[0212] In one embodiment, a method of wireless communication performed by a first user device (UE) includes deriving a time-reverse (TR) precoder based at least partially on an estimated channel between the first UE and a second UE, and sending a TR-precoded side-link positioning reference signal (SL-PRS) to the second UE.

[0208]

[0213] In some embodiments, deriving a TR precoder based at least partially on an estimated channel between a first UE and a second UE comprises deriving a TR precoder based at least partially on transmission or reception on a sidelink (SL) communication channel between a first UE and a second UE.

[0209]

[0214] In some embodiments, deriving a TR precoder based at least partially on an estimated channel between a first UE and a second UE comprises sending a wideband reference signal (WB RS) to the second UE, receiving channel status information (CSI) associated with the WB RS from the second UE, estimating a channel between the first UE and the second UE based at least partially on the CSI, and deriving a TR precoder based at least partially on the estimated channel between the first UE and the second UE.

[0210]

[0215] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

[0211]

[0216] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0212]

[0217] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0213]

[0218] In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission.

[0214]

[0219] In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof.

[0215]

[0220] In some embodiments, the CSI is received from a second UE via a physical sidelink shared channel (PSSCH).

[0216]

[0221] In some cases, a CSI is associated with a specific SL-PRS resource.

[0217]

[0222] In some embodiments, the CSI is associated with a channel sounding reference signal (RS) for CSI-RS feedback.

[0218]

[0223] In some embodiments, CSI is received aperiodically.

[0219]

[0224] In some embodiments, the CSI is received in response to sending a trigger message to a second UE.

[0220]

[0225] In some embodiments, sending a trigger message comprises sending a sidelink control information (SCI) message.

[0221]

[0226] In some embodiments, deriving a TR precoder based at least partially on an estimated channel between a first UE and a second UE comprises sending a wideband reference signal (WB RS) to the second UE and receiving the TR precoder from the second UE.

[0222]

[0227] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

[0223]

[0228] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0224]

[0229] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0225]

[0230] In some embodiments, deriving a TR precoder based at least partially on an estimated channel between a first UE and a second UE comprises receiving a wideband reference signal (WB RS) from the second UE, estimating a channel between the first UE and the second UE based at least partially on the WB RS, and deriving a TR precoder based at least partially on the estimated channel between the first UE and the second UE.

[0226]

[0231] In some embodiments, the WB RS is received in response to a trigger message being sent from the first UE to the second UE.

[0227]

[0232] In some embodiments, sending a trigger message comprises sending a sidelink control information (SCI) message.

[0228]

[0233] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

[0229]

[0234] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0230]

[0235] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0231]

[0236] In one embodiment, a method of wireless communication performed by a first user device (UE) includes receiving a wideband reference signal (WB RS) from a second UE, determining channel status information (CSI) based at least in part on the WB RS, and sending the CSI to the second UE.

[0232]

[0237] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel-sounding RS, or a WB beacon RS.

[0233]

[0238] In some embodiments, the method includes receiving a TR-precoded sidelink positioning reference signal (SL-PRS) from a second UE.

[0234]

[0239] In some embodiments, the method includes performing a positioning operation using a TR-precoded SL-PRS.

[0235]

[0240] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0236]

[0241] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0237]

[0242] In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission.

[0238]

[0243] In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof.

[0239]

[0244] In some embodiments, the CSI is sent to a second UE via a physical sidelink shared channel (PSSCH).

[0240]

[0245] In some cases, a CSI is associated with a specific SL-PRS resource.

[0241]

[0246] In some embodiments, the CSI is associated with a channel sounding reference signal (RS) for CSI-RS feedback.

[0242]

[0247] In some embodiments, CSIs are transmitted aperiodically.

[0243]

[0248] In some embodiments, the CSI is sent in response to the receipt of a trigger message from the second UE.

[0244]

[0249] In some embodiments, receiving a trigger message comprises receiving a sidelink control information (SCI) message.

[0245]

[0250] In one embodiment, a method of wireless communication performed by a first user device (UE) includes receiving a wideband (WB) reference signal (RS) from a second UE; estimating a channel between the second UE and the first UE based at least in part on the WB RS; deriving a time-reverse (TR) precoder based on the estimated channel; and sending the TR precoder to the second UE.

[0246]

[0251] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

[0247]

[0252] In some embodiments, the method includes receiving a TR-precoded sidelink positioning reference signal (SL-PRS) from a second UE.

[0248]

[0253] In some embodiments, the method includes performing a positioning operation using a TR-precoded SL-PRS.

[0249]

[0254] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0250]

[0255] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0251]

[0256] In one embodiment, a method of wireless communication performed by a first user device (UE) includes sending a wideband reference signal (WB RS) to a second UE and receiving a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS) from the second UE.

[0252]

[0257] In some embodiments, the WB RS is sent in response to the receipt of a trigger message from the second UE.

[0253]

[0258] In some embodiments, receiving a trigger message comprises receiving a sidelink control information (SCI) message.

[0254]

[0259] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel-sounding RS, or a WB beacon RS.

[0255]

[0260] In some embodiments, the method includes performing a positioning operation using a TR-precoded SL-PRS.

[0256]

[0261] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0257]

[0262] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0258]

[0263] In one embodiment, the first user equipment (UE) includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to derive a time-reverse (TR) precoder at least partially based on an estimated channel between the first UE and the second UE, and to send a TR-precoded side-link positioning reference signal (SL-PRS) to the second UE.

[0259]

[0264] In some embodiments, at least one processor is configured to derive a TR precoder at least partially on an estimated channel between a first UE and a second UE, or to derive a TR precoder at least partially on a transmit or receive on a sidelink (SL) communication channel between a first UE and a second UE.

[0260]

[0265] In some embodiments, at least one processor is configured to derive a TR precoder based at least partially on an estimated channel between a first UE and a second UE, send a wideband reference signal (WB RS) to the second UE, receive channel state information (CSI) associated with the WB RS from the second UE, estimate the channel between the first UE and the second UE based at least partially on the CSI, and derive a TR precoder based at least partially on the estimated channel between the first UE and the second UE.

[0261]

[0266] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel-sounding RS, or a WB beacon RS.

[0262]

[0267] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0263]

[0268] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0264]

[0269] In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission.

[0265]

[0270] In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof.

[0266]

[0271] In some embodiments, the CSI is received from a second UE via a physical sidelink shared channel (PSSCH).

[0267]

[0272] In some cases, a CSI is associated with a specific SL-PRS resource.

[0268]

[0273] In some embodiments, the CSI is associated with the channel sounding RS for CSI-RS feedback.

[0269]

[0274] In some embodiments, CSI is received aperiodically.

[0270]

[0275] In some embodiments, the CSI is received in response to sending a trigger message to a second UE.

[0271]

[0276] In some embodiments, at least one processor is configured to send a sidelink control information (SCI) message when sending a trigger message.

[0272]

[0277] In some embodiments, at least one processor is configured to send a wideband reference signal (WB RS) to the second UE and receive the TR precoder from the second UE when deriving the TR precoder based at least partially on an estimated channel between the first UE and the second UE.

[0273]

[0278] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel-sounding RS, or a WB beacon RS.

[0274]

[0279] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0275]

[0280] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0276]

[0281] In some embodiments, at least one processor is configured to receive a wideband reference signal (WB RS) from a second UE and estimate the channel between the first UE and the second UE based at least partially on the estimated channel between the first UE and the second UE, and to derive a TR precoder based at least partially on the estimated channel between the first UE and the second UE, when deriving a TR precoder based at least partially on the estimated channel between the first UE and the second UE.

[0277]

[0282] In some embodiments, the WB RS is received in response to a trigger message being sent from the first UE to the second UE.

[0278]

[0283] In some embodiments, at least one processor is configured to send a sidelink control information (SCI) message when sending a trigger message.

[0279]

[0284] In some aspects, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

[0280]

[0285] In some aspects, the WB RS is proximate to a TR precoded SL-PRS in time, frequency, or both.

[0281]

[0286] In some aspects, the WB RS is associated with at least one other SL-PRS.

[0282]

[0287] In one aspect, a first user equipment (UE) includes a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor being configured to receive a wideband reference signal (WB RS) from a second UE, determine channel state information (CSI) based at least in part on the WB RS, and send the CSI to the second UE.

[0283]

[0288] In some aspects, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

[0284]

[0289] In some aspects, the at least one processor is further configured to receive a TR precoded sidelink positioning reference signal (SL-PRS) from the second UE.

[0285]

[0290] In some aspects, the at least one processor is further configured to perform a positioning operation using the TR precoded SL-PRS.

[0286]

[0291] In some aspects, the WB RS is proximate to a TR precoded SL-PRS in time, frequency, or both.

[0287]

[0292] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0288]

[0293] In some embodiments, the CSI comprises a positioning CSI used for positioning rather than data transmission.

[0289]

[0294] In some embodiments, the CSI comprises a full or partial channel impulse response (CIR), a full or partial channel frequency response (CFR), a power delay profile, Doppler information, or a combination thereof.

[0290]

[0295] In some embodiments, the CSI is sent to a second UE via a physical sidelink shared channel (PSSCH).

[0291]

[0296] In some cases, a CSI is associated with a specific SL-PRS resource.

[0292]

[0297] In some embodiments, the CSI is associated with the channel sounding RS for CSI-RS feedback.

[0293]

[0298] In some embodiments, CSIs are transmitted aperiodically.

[0294]

[0299] In some embodiments, the CSI is sent in response to the receipt of a trigger message from the second UE.

[0295]

[0300] In some embodiments, at least one processor is configured to receive a sidelink control information (SCI) message upon receiving a trigger message.

[0296]

[0301] In one embodiment, the first user equipment (UE) includes a memory, at least one transceiver, and at least one processor communically coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to receive a wideband (WB) reference signal (RS) from the second UE, estimate a channel between the second UE and the first UE based at least partially on the WB RS, derive a time-reverse (TR) precoder based on the estimated channel, and send the TR precoder to the second UE.

[0297]

[0302] In some embodiments, the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel-sounding RS, or a WB beacon RS.

[0298]

[0303] In some embodiments, at least one processor is further configured to receive a TR-precoded side-link positioning reference signal (SL-PRS) from a second UE.

[0299]

[0304] In some embodiments, at least one processor is further configured to perform positioning operations using TR-precoded SL-PRS.

[0300]

[0305] In some embodiments, the WB RS is in proximity to the TR-precoded SL-PRS in terms of time, frequency, or both.

[0301]

[0306] In some embodiments, the WB RS is associated with at least one other SL-PRS.

[0302]

[0307] In one aspect, a first user equipment (UE) includes a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor being configured to send a wideband reference signal (WB RS) to a second UE and receive, from the second UE, a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS).

[0303]

[0308] In some aspects, the WB RS is sent in response to receiving a trigger message from the second UE.

[0304]

[0309] In some aspects, the trigger message comprises a sidelink control information (SCI) message.

[0305]

[0310] In some aspects, the WB RS comprises a sidelink positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

[0306]

[0311] In some aspects, the at least one processor is further configured to perform a positioning operation using the TR precoded SL-PRS.

[0307]

[0312] In some aspects, the WB RS is proximate to the TR precoded SL-PRS in time, frequency, or both.

[0308]

[0313] In some aspects, the WB RS is associated with at least one other SL-PRS.

[0309]

[0314] In one aspect, a first user equipment (UE) includes means for deriving a time-reversed (TR) precoder based at least in part on an estimated channel between the first UE and a second UE, and means for sending a TR precoded sidelink positioning reference signal (SL-PRS) to the second UE.

[0310]

[0315] In one embodiment, the first user equipment (UE) includes means for receiving a wideband reference signal (WB RS) from a second UE, means for determining channel status information (CSI) based at least in part on the WB RS, and means for sending the CSI to the second UE.

[0311]

[0316] In one embodiment, the first user equipment (UE) includes means for receiving a wideband (WB) reference signal (RS) from the second UE; means for estimating a channel between the second UE and the first UE based at least in part on the WB RS; means for deriving a time-reverse (TR) precoder based on the estimated channel; and means for sending the TR precoder to the second UE.

[0312]

[0317] In one embodiment, the first user equipment (UE) includes means for sending a wideband reference signal (WB RS) to a second UE and means for receiving a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS) from the second UE.

[0313]

[0318] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, which, when executed by one or more processors of a first user device (UE), cause the UE to derive a time-reverse (TR) precoder based at least partially on an estimated channel between the first UE and a second UE, and to send a TR-precoded side-link positioning reference signal (SL-PRS) to the second UE.

[0314]

[0319] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, when one or more instructions are executed by one or more processors of a first user device (UE), the UE receives a wideband reference signal (WB RS) from a second UE, determines channel status information (CSI) based at least partially on the WB RS, and causes the UE to send the CSI to the second UE.

[0315]

[0320] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, which, when executed by one or more processors of a first user device (UE), causes the UE to receive a wideband (WB) reference signal (RS) from a second UE, estimate a channel between the second UE and the first UE based at least partially on the WB RS, derive a time-reverse (TR) precoder based on the estimated channel, and send the TR precoder to the second UE.

[0316]

[0321] In one embodiment, a non-temporary computer-readable medium for storing a set of instructions, the set of instructions comprising one or more instructions, which, when executed by one or more processors of a first user device (UE), send a wideband reference signal (WB RS) to a second UE and cause the second UE to receive a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS).

[0317]

[0322] While the above disclosures illustrate exemplary aspects of the Disclosure, it should be noted that various changes and modifications can be made herein without departing from the scope of the Disclosure as defined by the appended claims. The functions, steps, and / or actions of the method claims in the aspects of the Disclosure described herein do not need to be performed in a specific order. Furthermore, while elements of the Disclosure may be described or claimed in the singular, the plural is intended unless explicitly stated to limit them to the singular.

Claims

1. A method of wireless communication performed by a first user device (UE), Deriving a time-reversal (TR) precoder based at least partially on the estimated channel between the first UE and the second UE, Sending the TR-precoded sidelink positioning reference signal (SL-PRS) to the second UE, A method that includes [a certain feature].

2. The method according to claim 1, wherein deriving the TR precoder at least partially on the estimated channel between the first UE and the second UE comprises deriving the TR precoder at least partially on transmission or reception on a sidelink (SL) communication channel between the first UE and the second UE.

3. Deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE is equivalent to sending a wideband reference signal (WB RS) to the second UE, Receiving the TR precoder from the second UE, or At least one of the following: receiving channel state information (CSI) associated with the WB RS from the second UE, estimating the channel between the first UE and the second UE based at least partially on the CSI, and deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE; The method according to claim 1, comprising:

4. The method according to claim 3, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

5. The method according to claim 3, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

6. The aforementioned CSI is Positioning CSI, used for positioning rather than data transmission. Complete or partial channel impulse response (CIR), Full or partial channel frequency response (CFR), Power delay profile, Doppler information, or The method according to claim 3, comprising those combinations.

7. The method according to claim 3, wherein the CSI is associated with a specific SL-PRS resource, a channel sounding reference signal (RS) for CSI-RS feedback, or a combination thereof.

8. The method according to claim 3, wherein the CSI is received in response to sending a trigger message to the second UE.

9. The method according to claim 8, wherein sending the trigger message comprises sending a side link control information (SCI) message.

10. Deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE is, Receiving a wideband reference signal (WBRS) from the second UE, Estimating the channel between the first UE and the second UE based at least partially on the WB RS, Deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE, The method according to claim 1, comprising:

11. The method according to claim 10, wherein the WB RS is received in response to a trigger message being sent from the first UE to the second UE.

12. The method according to claim 10, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

13. The method according to claim 10, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

14. A method of wireless communication performed by a first user device (UE), wherein the method is: Receiving a wideband reference signal (WBRS) from the second UE, Determining channel status information (CSI) based at least partially on the WB RS, Sending the CSI to the second UE, A method that includes [a certain feature].

15. The method according to claim 14, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

16. The aforementioned CSI is Positioning CSI, used for positioning rather than data transmission. Complete or partial channel impulse response (CIR), Full or partial channel frequency response (CFR), Power delay profile, Doppler information, or The method according to claim 14, comprising those combinations.

17. The method according to claim 14, wherein the CSI is associated with a specific SL-PRS resource, a channel sounding reference signal (RS) for CSI-RS feedback, or a combination thereof.

18. The method according to claim 14, wherein the CSI is sent in response to the receipt of a trigger message from the second UE.

19. A method of wireless communication performed by a first user device (UE), Receiving a broadband (WB) reference signal (RS) from the second UE, Estimating the channel between the second UE and the first UE based at least partially on the WB RS, The process involves deriving a time-reversal (TR) precoder based on the estimated channel, Sending the aforementioned TR precoder to the second UE, A method that includes [a certain feature].

20. The method according to claim 19, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

21. A method of wireless communication performed by a first user device (UE), wherein the method is: Sending a wideband reference signal (WBRS) to the second UE, The second UE receives a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS), A method that includes [a certain feature].

22. The method according to claim 21, wherein sending the WB RS is performed in response to receiving a trigger message from the second UE.

23. The method according to claim 21, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

24. The method according to claim 21, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

25. The first user equipment (UE) is, Memory and At least one transceiver, The system comprises the memory and at least one processor communicatively coupled to the at least one transceiver, wherein the at least one processor is Deriving a time-reversal (TR) precoder based at least partially on the estimated channel between the first UE and the second UE, Sending a TR-precoded sidelink positioning reference signal (SL-PRS) to the second UE via at least one of the transceivers, A first user device (UE) configured to perform the following actions.

26. The first UE according to claim 25, in order to derive the TR precoder on at least partially the estimated channel between the first UE and the second UE, the at least one processor is configured to derive the TR precoder on at least partially the transmission or reception on the sidelink (SL) communication channel between the first UE and the second UE.

27. In order to derive the TR precoder based at least partially on the estimated channel between the first UE and the second UE, the at least one processor sends a wideband reference signal (WBRS) to the second UE, Receiving the TR precoder from the second UE via the at least one transceiver, or At least one of the following: receiving channel state information (CSI) associated with the WB RS from the second UE via the at least one transceiver; estimating the channel between the first UE and the second UE based at least partially on the CSI; and deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE; The first UE according to claim 25, configured to perform the following:

28. The first UE according to claim 27, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

29. The first UE according to claim 27, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

30. The aforementioned CSI is Positioning CSI, used for positioning rather than data transmission. Complete or partial channel impulse response (CIR), Full or partial channel frequency response (CFR), Power delay profile, Doppler information, or The first UE according to claim 27, comprising a combination thereof.

31. The first UE according to claim 27, wherein the CSI is associated with a specific SL-PRS resource, a channel sounding reference signal (RS) for CSI-RS feedback, or a combination thereof.

32. The CSI is received in response to sending a trigger message to the second UE, the first UE according to claim 27.

33. The first UE according to claim 32, wherein the at least one processor is configured to send a sidelink control information (SCI) message in order to send the trigger message.

34. In order to derive the TR precoder based at least partially on the estimated channel between the first UE and the second UE, the at least one processor receives a wideband reference signal (WBRS) from the second UE via the at least one transceiver, Estimating the channel between the first UE and the second UE based at least partially on the WB RS, Deriving the TR precoder based at least partially on the estimated channel between the first UE and the second UE, The first UE according to claim 25, configured to perform the following:

35. The WB RS is received in response to the first UE sending a trigger message from the first UE to the second UE, as described in claim 34.

36. The first UE according to claim 34, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

37. The first UE according to claim 34, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

38. User equipment (UE), Memory and At least one transceiver, The system comprises the memory and at least one processor communicatively coupled to the at least one transceiver, wherein the at least one processor is The system receives a wideband reference signal (WBRS) from a second UE via at least one of the transceivers, Determining channel status information (CSI) based at least partially on the WB RS, To send to the CSI via the at least one transceiver, User equipment (UE) configured to perform the following actions.

39. The UE according to claim 38, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

40. The aforementioned CSI is Positioning CSI, used for positioning rather than data transmission. Complete or partial channel impulse response (CIR), Full or partial channel frequency response (CFR), Power delay profile, Doppler information, or The UE according to claim 38, comprising those combinations.

41. The UE according to claim 38, wherein the CSI is associated with a specific SL-PRS resource, a channel sounding reference signal (RS) for CSI-RS feedback, or a combination thereof.

42. The UE according to claim 38, wherein the CSI is sent in response to the receipt of a trigger message from the second UE.

43. User equipment (UE), Memory and At least one transceiver, The system comprises the memory and at least one processor communicatively coupled to the at least one transceiver, wherein the at least one processor is Receiving a broadband (WB) reference signal (RS) from a second UE via at least one of the aforementioned transceivers, Estimating the channel between the first UE and the second UE based at least partially on the WB RS, The process involves deriving a time-reversal (TR) precoder based on the estimated channel, Sending the TR precoder to the second UE via at least one of the transceivers, User equipment (UE) configured to perform the following actions.

44. The UE according to claim 43, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding reference signal (RS), or a WB beacon RS.

45. User equipment (UE), Memory and At least one transceiver, The system comprises the memory and at least one processor communicatively coupled to the at least one transceiver, wherein the at least one processor is Sending a wideband reference signal (WBRS) to a second UE via at least one of the aforementioned transceivers, A user device (UE) configured to receive a time-reversed (TR) precoded sidelink positioning reference signal (SL-PRS) from the second UE via at least one of the transceivers.

46. The UE according to claim 45, wherein, in order to send the WB RS, the at least one processor is configured to send the WB RS in response to receiving a trigger message from the second UE.

47. The UE according to claim 45, wherein the WB RS comprises a side-link positioning reference signal (SL-PRS), a channel sounding RS, or a WB beacon RS.

48. The UE according to claim 45, wherein the WB RS is within a threshold distance from the TR-precoded SL-PRS in the time domain, the frequency domain, or both.

Images