Sidelink positioning reference signal pattern

Abstract

Techniques for wireless communications are disclosed. In one aspect, a first UE determines a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure. The sidelink PRS pattern includes at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium. The first UE performs one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE according to the sidelink PRS pattern. In another aspect, a second UE determines a sidelink PRS pattern and monitors the first PRS transmission opportunity for receiving the first PRS from the first UE according to the sidelink PRS pattern.

Description

[Technical field]

[0001] Aspects of the present disclosure relate generally to wireless communications. [Background technology]

[0002] Wireless communication systems have evolved through various generations, including first-generation analog wireless telephone service (1G), second-generation (2G) digital wireless telephone service (including interim 2.5G and 2.75G networks), third-generation (3G) high-speed data, Internet-enabled wireless service, and fourth-generation (4G) service (e.g., Long Term Evolution (LTE) or WiMax). Currently, many different types of wireless communication systems are in use, including cellular systems and personal communications 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), and the like.

[0003] The fifth generation (5G) wireless standard, called New Radio (NR), will enable higher data rates, more connections, and better coverage, among other improvements. The 5G standard is designed to provide higher data rates, more accurate positioning (e.g., based on a reference signal for positioning (RS-P), such as a downlink, uplink, or sidelink positioning reference signal (PRS)), and other technological enhancements compared to previous standards, according to the Next Generation Mobile Network Alliance.

[0004] In particular, vehicle-to-everything (V2X) communication technologies are being enabled to leverage 5G's increased data rates and reduced latency to support autonomous driving applications, such as wireless communications between vehicles, between vehicles and roadside infrastructure, between vehicles and pedestrians, etc. Summary of the Invention

[0005] The following presents a simplified summary related to one or more aspects disclosed herein. As such, the following summary is not intended to be an extensive overview of all contemplated aspects, nor is it intended to identify key or critical elements of all contemplated aspects or to delineate the scope related to any particular aspect. Thus, the sole purpose of the following summary is to present certain concepts of one or more aspects of the mechanisms disclosed herein in a simplified form prior to the detailed description presented below.

[0006] In an aspect, a method of operating a first user equipment (UE) includes determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and performing one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0007] In an aspect, a method of operating a second user equipment (UE) includes determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and monitoring the first PRS transmission opportunity for reception of a first PRS from a first UE in accordance with the sidelink PRS pattern.

[0008] In an 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, wherein the at least one processor is configured to: determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium; and perform one or more attempts to transmit a first PRS in the one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0009] In an aspect, a second 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, wherein the at least one processor is configured to: determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and monitor the first PRS transmission opportunity for receiving a first PRS from the first UE in accordance with the sidelink PRS pattern.

[0010] In one aspect, a method includes: a first user equipment (UE) includes means for determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and means for performing one or more attempts to transmit a first PRS in the one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0011] In one aspect, a second user equipment (UE) includes means for determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and means for monitoring a first PRS transmission opportunity for receiving a first PRS from a first UE in accordance with the sidelink PRS pattern.

[0012] In an aspect, a non-transitory computer-readable medium storing computer-executable instructions that, when executed by a first user equipment (UE), cause the first UE to determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and to perform one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0013] In an aspect, a non-transitory computer-readable medium storing computer-executable instructions that, when executed by a second user equipment (UE), cause the second UE to determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and to monitor the first PRS transmission opportunity for reception of a first PRS from a first UE in accordance with the sidelink PRS pattern.

[0014] Other objects and advantages associated with the aspects disclosed herein will become apparent to one of ordinary skill in the art based on the accompanying drawings and detailed description.

[0015] The accompanying drawings are presented to aid in the explanation of various aspects of the present disclosure and are provided only to illustrate, not limit, the aspects. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 illustrates an example wireless communication system according to an aspect of the present disclosure. [Figure 2A] FIG. 1 illustrates an example wireless network structure according to an aspect of the present disclosure. [Figure 2B]FIG. 1 illustrates an example wireless network structure according to an aspect of the present disclosure. [Figure 3A] 1 is a simplified block diagram of several sample aspects of components that may be employed in a user equipment (UE) and configured to support communications as taught herein; [Figure 3B] 1 is a simplified block diagram of several sample aspects of components that may be employed in a base station and configured to support communications as taught herein. [Figure 3C] 1 is a simplified block diagram of several sample aspects of components that may be employed in a network entity and configured to support communications as taught herein. [Figure 4] 1 illustrates an example of a wireless communication system supporting unicast sidelink establishment in accordance with an aspect of the present disclosure. [Diagram 5] 1 illustrates examples of various positioning methods supported in New Radio (NR) according to an embodiment of the present disclosure. [Figure 6] 1 shows time and frequency resources used for sidelink communication. [Figure 7] 1 illustrates an example wireless communication system in which a vehicle user equipment (V-UE) is exchanging ranging signals with a roadside unit (RSU) and another V-UE, in accordance with an aspect of the present disclosure. [Figure 8] 1 illustrates a sidelink communication scheduling (or resource allocation) scheme according to an aspect of the present disclosure. [Figure 9] 1 illustrates an example process for wireless communication according to an aspect of the present disclosure. [Figure 10] 1 illustrates an example process for wireless communication according to an aspect of the present disclosure. [Figure 11] 1 illustrates a sidelink PRS pattern according to an embodiment of the present disclosure. [Figure 12] 1 illustrates a sidelink PRS pattern according to an embodiment of the present disclosure. [Figure 13]1 illustrates a sidelink PRS pattern according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Aspects of the present disclosure are provided in the following description and associated drawings directed to various examples provided for illustrative purposes. Alternative aspects may be devised without departing from the scope of the present disclosure. Additionally, well-known elements of the present disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the present disclosure.

[0018] The words "exemplary" and / or "example" are used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" and / or "example" should not necessarily be construed as preferred or advantageous over other aspects. Similarly, the term "aspects of the disclosure" does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation.

[0019] Those skilled in the art will appreciate that the information and signals described below may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the following description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof, depending in part on the particular application, desired design, corresponding technology, etc.

[0020] Further, many aspects are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be appreciated that various actions described herein may be performed by specific circuitry (e.g., an application specific integrated circuit (ASIC), by program instructions executed by one or more processors, or by a combination of both. In addition, the sequence or sequences of actions described herein may be considered to be fully embodied in any form of non-transitory computer-readable storage medium having stored thereon a corresponding set of computer instructions that, when executed, cause or instruct an associated processor of a device to perform the functions described herein. Thus, various aspects of the present disclosure may be embodied in a number of different forms, all of which are contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the corresponding form of any such aspect may be described herein, for example, as "logic configured to" perform the described actions.

[0021] The terms "user equipment" (UE), "vehicle UE" (V-UE), "pedestrian UE" (P-UE), and "base station" as used herein are not intended to be specific or otherwise limited to any particular radio access technology (RAT) unless otherwise specified. In general, a UE may be any wireless communication device (e.g., a vehicle-mounted computer, a vehicle navigation device, a mobile phone, a router, a tablet computer, a laptop computer, an asset positioning device, a wearable (e.g., a smart watch, a smart glass, an augmented reality (AR) / virtual reality (VR) headset, etc.), a vehicle (e.g., an automobile, a motorcycle, a bicycle, etc.), an Internet of Things (IoT) device, etc.) used by a user to communicate over a wireless communication network. A UE may be mobile or stationary (e.g., at a given time) and may communicate with a radio access network (RAN). As used herein, the term "UE" may be referred to interchangeably as a "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.

[0022] A V-UE is a type of UE and may be any in-vehicle wireless communication device, such as a navigation system, a warning system, a heads-up display (HUD), an on-board computer, an in-vehicle infotainment system, an automated driving system (ADS), an advanced driver assistance system (ADAS), etc. Alternatively, a V-UE may be a portable wireless communication device (e.g., a cell phone, a tablet computer, etc.) carried by the driver of the vehicle or a passenger 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 and may be a portable wireless communication device carried by a pedestrian (i.e., a user not driving or riding in the vehicle). In general, a UE can communicate with a core network via a RAN, through which the UE can be connected to external networks such as the Internet and to other UEs. Of course, other mechanisms for a UE to connect to the core network and / or the Internet are possible, such as via a wired access network, a wireless local area network (WLAN) network (e.g., based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc.), etc.

[0023] A base station may operate according to one of several RATs in communication with UEs depending on the network in which the base station is deployed and may alternatively be referred to as an access point (AP), network node, Node B, evolved Node B (eNB), next generation eNB (ng-eNB), New Radio (NR) Node B (also referred to as gNB or gNode B), etc. A base station 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 only edge node signaling functionality, while in other systems, a base station may provide additional control and / or network management functionality. A communication link through which a UE may send signals to a base station is referred to as an uplink (UL) channel (e.g., reverse traffic channel, reverse control channel, access channel, etc.). A communication link through which a base station can send signals to a UE is called a downlink (DL) or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein, the term Traffic CHannel (TCH) can refer to either a UL / reverse traffic channel or a DL / forward traffic channel.

[0024] The term "base station" may refer to a single physical transmission-reception point (TRP) or multiple physical TRPs that may or may not be collocated. For example, when the term "base station" refers to a single physical TRP, the physical TRP may be an antenna of the base station that corresponds to a cell (or several cell sectors) of the base station. When the term "base station" refers to multiple collocated physical TRPs, the physical TRP may be an array of antennas of the base station (e.g., as in the case of a multiple-input multiple-output (MIMO) system or when the base station employs beamforming). When the term "base station" refers to multiple non-collocated physical TRPs, the physical TRP may 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, non-co-located physical TRPs may be serving base stations that receive measurement reports from the UE and neighboring base stations whose reference radio frequency (RF) signals the UE is measuring. Since a TRP is a point from which a base station transmits and receives wireless signals, as used herein, references to transmission from or reception at a base station should be understood as referring to a particular TRP of the base station.

[0025] In some implementations that support positioning of UEs, a base station may not support wireless access by the UE (e.g., may not support data, voice, and / or signaling connections for the UE), but instead may transmit reference RF signals to the UE to be measured by the UE and / or may receive and measure signals transmitted by the UE. Such a base station may be referred to as a positioning beacon (e.g., when it transmits RF signals to the UE) and / or a location measurement unit (e.g., when it receives and measures RF signals from the UE).

[0026] An "RF signal" includes electromagnetic waves of a given frequency that transport information through space between a transmitter and a receiver. As used herein, a transmitter may transmit a single "RF signal" or multiple "RF signals" to a receiver. However, the receiver may receive multiple "RF signals" corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through multipath channels. The same transmitted RF signal on different paths between a transmitter and a receiver may be referred to as a "multipath" RF signal. As used herein, an RF signal may also be referred to as a "wireless signal" or simply a "signal" when it is clear from the context that the term "signal" refers to a wireless signal or an RF signal.

[0027] 1 illustrates an example wireless communication system 100 according to an aspect of the disclosure. The wireless communication system 100 (sometimes referred to as a wireless wide area network (WWAN)) may include various base stations 102 (labeled as "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 an aspect, the macrocell base stations 102 may include eNBs and / or ng-eNBs where the wireless communication system 100 supports an LTE network, or gNBs where the wireless communication system 100 supports an NR network, or a combination of both, and the small cell base stations may include femtocells, picocells, microcells, etc.

[0028] The base stations 102 may collectively form a RAN and may interface to a core network 170 (e.g., evolved packet core (EPC) or 5G core (5GC)) through the backhaul links 122 and to 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 170. The location server(s) 172 may be part of the core network 170 or may be external to the core network 170. The location server 172 may be integrated with the base station 102. The UE 104 may communicate with the location server 172 directly or indirectly. For example, the UE 104 may communicate with the location server 172 via the base station 102 currently serving the UE 104. The UE 104 may also communicate with the location server 172 through another path, such as through an application server (not shown), through another network, such as through a wireless local area network (WLAN) access point (AP) (e.g., AP 150 described below), etc. For purposes of signaling, communication between the UE 104 and the location server 172 may be represented as an indirect connection (e.g., through a core network 170, etc.) or a direct connection (e.g., as shown via direct connection 128), with intervening nodes (if any) omitted from the signaling diagrams for clarity.

[0029] In addition to other functions, the base stations 102 may perform functions related to one or more of the following: forwarding 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, non-access stratum (NAS) message delivery, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracing, RAN information management (RIM), paging, positioning, and alert message delivery. The 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.

[0030] The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage to a respective geographic coverage area 110. In an aspect, one or more cells may be supported by the base stations 102 in each geographic coverage area 110. A "cell" is a logical communication entity used for communication with a base station (e.g., over some frequency resources, referred to as a carrier frequency, component carrier, carrier, band, etc.) and may be associated with an identifier (e.g., a physical cell identifier (PCI), an enhanced cell identifier (ECI), a virtual cell identifier (VCI), a 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 communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of UEs. Because cells are supported by a particular base station, the term "cell" may refer to either or both of the logical communication entity supporting the cell and the base station, depending on the context. In some cases, the term "cell" may also refer to the geographic coverage area (e.g., sector) of a base station, so long as the carrier frequency can be detected and used for communication within some portion of the geographic coverage area 110.

[0031] The geographic coverage areas 110 of neighboring macrocell base stations 102 may overlap partially (e.g., in handover regions) and some of the geographic coverage areas 110 may be substantially overlapped by larger geographic coverage areas 110. For example, a small cell base station 102' (labeled "SC" instead of "small cell") may have a geographic coverage area 110' that significantly overlaps with the geographic coverage area 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 home eNBs (HeNBs), which may serve closed groups known as closed subscriber groups (CSGs).

[0032] The communication link 120 between the base station 102 and the UE 104 may include uplink (also referred to as reverse link) transmissions from the UE 104 to the base station 102, and / or downlink (DL) (also referred to as forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may use MIMO antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may be through one or more carrier frequencies. The allocation of carriers may be asymmetric with respect to the downlink and uplink (e.g., more or fewer carriers may be allocated for the downlink than for the uplink).

[0033] The wireless communication system 100 may further include a wireless local area network (WLAN) access point (AP) 150 in communication with a wireless local area network (WLAN) station (STA) 152 over a communication link 154 in an unlicensed frequency spectrum (e.g., 5 GHz). When communicating in the unlicensed frequency spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or listen before talk (LBT) procedure before communicating to determine if a channel is available.

[0034] The small cell base station 102' may operate in a licensed and / or unlicensed frequency spectrum. When operating in the unlicensed frequency spectrum, the small cell base station 102' may utilize LTE or NR technology and use the same 5 GHz unlicensed frequency spectrum used by the WLAN AP 150. A small cell base station 102' employing LTE / 5G in the unlicensed frequency spectrum may extend coverage to and / or increase capacity of the access network. NR in the unlicensed spectrum may be referred to as NR-U. LTE in the unlicensed spectrum may be referred to as LTE-U, licensed assisted access (LAA), or MultiFire.

[0035] The wireless communication system 100 may further include a mmW base station 180 that may operate at millimeter wave (mmW) and / or sub-mmW frequencies while communicating with the UE 182. Extremely high frequency (EHF) is a portion of RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength of 1 millimeter to 10 millimeters. Radio waves in this band may be referred to as millimeter waves. Sub-mmW may extend down to frequencies of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as centimeter waves. Communications using the mmW / sub-mmW radio frequency bands have high path losses and relatively short distances. The mmW base station 180 and the UE 182 may utilize beamforming (transmit and / or receive) over the mmW communication link 184 to compensate for the extremely large path losses and short distances. Further, it will be appreciated that in alternative configurations, one or more base stations 102 may also transmit using mmW or quasi-mmW and beamforming. Thus, it will be appreciated that the above illustrations are merely examples and should not be construed as limiting various aspects disclosed herein.

[0036] Transmit beamforming is a technique for focusing an RF signal in a particular direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts it in all directions (omnidirectionally). With transmit beamforming, the network node determines where a given target device (e.g., UE) is located (relative to the transmitting network node) and projects a stronger downlink RF signal in that particular direction, thereby providing a faster and more powerful RF signal (in terms of data rate) to the receiving device(s). To vary the directionality of the 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 (also called a "phased array" or "antenna array") that creates beams of RF waves that can be "steered" to point in different directions without actually moving the antennas. In particular, RF current from a transmitter is fed to each antenna with the proper phase relationship so that the radio waves from the separate antennas combine together to enhance radiation in the desired direction while canceling out radiation in undesirable directions.

[0037] A transmit beam may be quasi-co-located, meaning that the transmit beam appears to a receiver (e.g., UE) to have the same parameters, regardless of whether the network node's own transmit antennas are physically co-located or not. In NR, there are four types of quasi-co-location (QCL) relationships. Specifically, a QCL relationship of a given type means that some parameters for a second reference RF signal on a second beam can be derived from information about a source reference RF signal on a 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, average delay, and delay spread of the 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 the 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 average 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 spatial reception parameters of a second reference RF signal transmitted on the same channel.

[0038] In receive beamforming, a receiver uses receive beams to amplify RF signals detected on a given channel. For example, the receiver can increase the gain setting and / or adjust the phase setting of an array of antennas in a particular direction to amplify (e.g., increase the gain level) RF signals received from that direction. Thus, when a receiver is said to beamform in some direction, it means that the beam gain in that direction is higher than the beam gains along other directions, or that the beam gain in that direction is the highest compared to the beam gains in that direction of all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) of RF signals received from that direction.

[0039] The transmit beam and the receive beam may be spatially related. The spatial relationship means that the parameters for the second beam (e.g., transmit beam or receive beam) for the second reference signal may be derived from information about the first beam (e.g., receive beam or transmit beam) for the first reference signal. For example, the UE may use a particular receive beam to receive a reference downlink reference signal (e.g., synchronization signal block (SSB)) from a base station. The UE may then form a transmit beam for transmitting an uplink reference signal (e.g., sounding reference signal (SRS)) to that base station based on the parameters of the receive beam.

[0040] Note that a "downlink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if the base station forms a downlink beam to transmit a reference signal to the UE, then the downlink beam is a transmit beam. However, if the UE forms a downlink beam, then it is a receive beam to receive a downlink reference signal. Similarly, an "uplink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if the base station forms an uplink beam, then it is an uplink receive beam, and if the UE forms an uplink beam, then it is an uplink transmit beam.

[0041] The electromagnetic spectrum is often subdivided into various classes, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified with frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). It should be understood that FR1 is often referred to (interchangeably) as the "sub-6 GHz" band in various documents and papers, although a portion of FR1 is above 6 GHz. Similar nomenclature issues may arise with respect to FR2, which is often referred to (interchangeably) as the "millimeter wave" band in documents and papers, even though it is different from the extremely high frequency (EHF) band (30 GHz-300 GHz) identified as the "millimeter wave" band by the International Telecommunications Union (ITU).

[0042] Frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified operating bands for these mid-band frequencies as frequency range designation FR3 (7.125 GHz to 24.25 GHz). Frequency bands that fall within FR3 may inherit FR1 and / or FR2 characteristics, and thus may in effect extend the features of FR1 and / or FR2 to the mid-band frequencies. Additionally, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR4a or FR4-1 (52.6 GHz to 71 GHz), FR4 (52.6 GHz to 114.25 GHz), and FR5 (114.25 GHz to 300 GHz). Each of these higher frequency bands falls within the EHF band.

[0043] With the above aspects in mind, it should be understood that unless otherwise specified, terms such as "sub-6 GHz" as used herein may broadly refer to frequencies that may be below 6 GHz, may be within FR1, or may include mid-band frequencies. Additionally, it should be understood that unless otherwise specified, terms such as "mmWave" as used herein may broadly refer to frequencies that may include mid-band frequencies, may be within FR2, FR4, FR4-a or FR4-1, and / or FR5, or may be within the EHF band.

[0044] In a multi-carrier system such as 5G, one of the carrier frequencies is called the "primary carrier" or "anchor carrier" or "primary serving cell" or "PCell" and the remaining carrier frequencies are called the "secondary carrier" or "secondary serving cell" or "SCell". In carrier aggregation, the anchor carrier is a carrier operating on the primary frequency (e.g., FR1) utilized by the UE 104 / 182 and on the cell in which the UE 104 / 182 either performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection re-establishment procedure. The primary carrier carries all common control channels and UE-specific control channels and may (but is not always) be a carrier among licensed frequencies. The secondary carrier is a carrier operating on a second frequency (e.g., FR2) that may be configured once an RRC connection is established between the UE 104 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. Since both the primary uplink carrier and the primary downlink carrier are typically UE specific, the secondary carrier may include only the necessary signaling information and signals, e.g., the signaling information and signals that are UE specific may not be present in the secondary carrier. This means that different UEs 104 / 182 in a cell may have different downlink primary carriers. The same applies to the uplink primary carrier. The network may change the primary carrier of any UE 104 / 182 at any time. This is done, for example, to distribute the load on different carriers. Since a "serving cell" (whether PCell or SCell) corresponds to a carrier frequency / component carrier over which several base stations are communicating, terms such as "cell", "serving cell", "component carrier", "carrier frequency", etc. may be used interchangeably.

[0045] For example, still referring to FIG. 1, one of the frequencies utilized by the macrocell base station 102 may be an anchor carrier (or “PCell”), and the other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 may be secondary carriers (“SCells”). Simultaneous transmission and / or reception of multiple carriers allows the UE 104 / 182 to significantly increase its data transmission and / or data reception rates. For example, two aggregated 20 MHz carriers in a multi-carrier system would theoretically lead to a two-fold increase in data rate (i.e., 40 MHz) compared to the data rate achieved by a single 20 MHz carrier.

[0046] In the example of FIG. 1, any of the illustrated UEs (shown in FIG. 1 as a single UE 104 for simplicity) may receive signals 124 from one or more Earth-orbiting space vehicles (SVs) 112 (e.g., satellites). In one aspect, the SVs 112 may be part of a satellite positioning system that the UEs 104 may use as an independent source of location information. A satellite positioning system typically includes a system of transmitters (e.g., SVs 112) positioned to enable receivers (e.g., UEs 104) to determine their location on or above the Earth based at least in part on positioning signals (e.g., signals 124) received from the transmitters. Such transmitters typically transmit signals marked with a repeating pseudo-random noise (PN) code of a set number of chips. Although typically located within the SVs 112, transmitters may sometimes be located on ground-based control stations, base stations 102, and / or other UEs 104. The UE 104 may include one or more dedicated receivers specifically designed to receive the signals 124 from the SV 112 to derive geolocation information.

[0047] In a satellite positioning system, the use of the signals 124 may be augmented by various satellite-based augmentation systems (SBAS) that may be associated with or otherwise enabled for use with one or more global and / or regional navigation satellite systems. For example, the SBAS may include an augmentation system or systems that provide integrity information, differential corrections, and the like, such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), the Multi-functional Satellite Augmentation System (MSAS), the Global Positioning System (GPS)-aided Geo-augmented Navigation, or the GPS and Geo Augmented Navigation system (GAGAN). Thus, a satellite positioning system, as used herein, may include any combination of one or more global and / or regional navigation satellites associated with such one or more satellite positioning systems.

[0048] In one aspect, the SV 112 may additionally or alternatively be part of one or more non-terrestrial networks (NTNs). In an NTN, the SV 112 is connected to an earth station (also called a ground station, NTN gateway, or gateway), which in turn is connected to an element in a 5G network, such as a modified base station 102 (without a terrestrial antenna) or a network node in a 5G network. This element will then provide access to other elements in the 5G network and ultimately to entities outside the 5G network, such as Internet web servers and other user devices. In this way, the UE 104 may receive communication signals (e.g., signal 124) from the SV 112 instead of or in addition to communication signals from the terrestrial base station 102.

[0049] In particular, vehicle-to-everything (V2X) communication technology is being implemented to leverage NR's increased data rates and reduced latency to support intelligent transportation systems (ITS) applications such as wireless communications between vehicles (vehicle-to-vehicle, V2V), between vehicles and roadside infrastructure (vehicle-to-infrastructure, V2I), and between vehicles and pedestrians (vehicle-to-pedestrian, V2P). The goal is for vehicles to be able to sense the environment around them and communicate that information to other vehicles, infrastructure, and personal mobile devices. Such vehicular communications will enable safety, mobility, and environmental improvements that current technologies cannot provide. When fully realized, the technology is expected to reduce unimpeded vehicle collisions by 80%.

[0050] 1, the wireless communication system 100 may include multiple V-UEs 160 that communicate with the base station 102 over a communication link 120 using a Uu interface (i.e., an air interface between the UE and the base station). The V-UEs 160 may also communicate directly with each other over a wireless sidelink 162, with a roadside unit (RSU) 164 (a roadside access point) over a wireless sidelink 166, or with a sidelink-enabled UE 104 over a wireless sidelink 168 using a PC5 interface (i.e., an air interface between sidelink-enabled UEs). The wireless sidelink (or simply "sidelink") is an adaptation of the core cellular (e.g., LTE, NR) standard that allows direct communication between two or more UEs without the communication having to go through a base station. Sidelink communications may be unicast or multicast and may be used for device-to-device (D2D) medium sharing, V2V communications, V2X communications (e.g., cellular V2X (cV2X) communications, enhanced V2X (eV2X) communications, etc.), emergency rescue applications, etc. One or more of the groups of V-UEs 160 utilizing sidelink communications may be within the geographic coverage area 110 of the base station 102. Other V-UEs 160 in such a group may be outside the geographic coverage area 110 of the base station 102 or may not otherwise be able to receive transmissions from the base station 102. In some cases, a group of V-UEs 160 communicating via sidelink communications may utilize a one-to-many (1:M) system in which each V-UE 160 transmits to all other V-UEs 160 in the group. In some cases, the base station 102 facilitates scheduling of resources for sidelink communications. In other cases, sidelink communication is performed between the V-UEs 160 without the involvement of the base station 102.

[0051] In one aspect, the sidelinks 162, 166, 168 may operate over a subject wireless communications medium, which may be shared with other vehicles and / or infrastructure access points, as well as other wireless communications between other RATs. The "medium" may consist of one or more time, frequency, and / or spatial communications resources (e.g., encompassing one or more channels across one or more carriers) associated with wireless communications between one or more transmitter / receiver pairs.

[0052] In one aspect, the sidelinks 162, 166, 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. Other countries may allocate other bands. Thus, as a specific example, the target medium utilized by the sidelinks 162, 166, 168 may correspond to at least a portion of the sub-6 GHz licensed ITS frequency band. However, the present disclosure is not limited to this frequency band or cellular technology.

[0053] In one aspect, the sidelinks 162, 166, 168 may be dedicated short-range communications (DSRC) links. DSRC is a one-way or two-way, short- to medium-range wireless communications protocol using the wireless access for vehicular environments (WAVE) protocol, also referred to as IEEE 802.11p, for V2V, V2I, and V2P communications. IEEE 802.11p is an approved amendment to the IEEE 802.11 standard, which operates in the United States in the licensed ITS band at 5.9 GHz (5.85-5.925 GHz). In Europe, IEEE 802.11p operates in the ITS G5A band (5.875-5.905 MHz). Other countries may allocate other bands. The V2V communications briefly described above are typically conducted on the Safety Channel, a 10 MHz channel dedicated for safety purposes in the United States. The remainder of the DSRC band (total bandwidth of 75 MHz) is intended for other services targeted to drivers, such as road enforcement, toll collection, automated parking, etc. Thus, as a specific example, the medium of interest utilized by the sidelinks 162, 166, 168 may correspond to at least a portion of the 5.9 GHz licensed ITS frequency band.

[0054] Alternatively, the medium of interest may correspond to at least a portion of an unlicensed frequency band shared among various RATs. Although different licensed frequency bands have been reserved for several communication systems (e.g., 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) technologies, most notably the IEEE 802.11x WLAN technology commonly referred to as "Wi-Fi". Exemplary systems of this type include CDMA systems, TDMA systems, FDMA systems, orthogonal FDMA (OFDMA) systems, single-carrier FDMA (SC-FDMA) systems, and various variants thereof.

[0055] Communication between V-UEs 160 is referred to as V2V communication, communication between V-UEs 160 and one or more RSUs 164 is referred to as V2I communication, and communication between V-UEs 160 and one or more UEs 104 (where UEs 104 are P-UEs) is referred to as V2P communication. V2V communication between V-UEs 160 may include, for example, information about the position, speed, acceleration, heading, and other vehicle data of V-UEs 160. V2I information received at V-UEs 160 from one or more RSUs 164 may include, for example, road regulations, parking automation information, and the like. V2P communication between V-UEs 160 and UEs 104 may include, for example, information about the position, speed, acceleration, and heading of V-UEs 160, and the position, speed (e.g., when UEs 104 are carried by a user on a bicycle), and heading of UEs 104.

[0056] It should be noted that while FIG. 1 illustrates only two of the UEs as V-UEs (V-UE 160), any of the illustrated UEs (e.g., UEs 104, 152, 182, 190) may be V-UEs. Additionally, while only V-UE 160 and a single UE 104 are illustrated as being connected via a sidelink, any of the UEs illustrated in FIG. 1, whether V-UE, P-UE, etc., may be capable of sidelink communication. Additionally, although only UE 182 was described as being capable of beamforming, any of the illustrated UEs, including V-UE 160, may be capable of beamforming. If V-UE 160 is capable of beamforming, V-UE 160 may beamform toward each other (i.e., toward other V-UEs 160), toward RSU 164, toward other UEs (e.g., UEs 104, 152, 182, 190), etc. Thus, in some cases, V-UE 160 may utilize beamforming on sidelinks 162, 166, and 168.

[0057] The wireless communication system 100 may further include one or more UEs, such as a UE 190, that indirectly connect to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the example of FIG. 1, the UE 190 has a D2D P2P link 192 (e.g., through which the UE 190 may indirectly obtain cellular connectivity) with one of the UEs 104 connected to one of the base stations 102, and a D2D P2P link 194 (through which the UE 190 may indirectly obtain WLAN-based Internet connectivity) with a WLAN STA 152 connected to a WLAN AP 150. In one example, the 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), Bluetooth, etc. As another example, the D2D P2P links 192 and 194 may be sidelinks such as those described above with respect to the sidelinks 162, 166, and 168.

[0058] 2A illustrates an exemplary wireless network structure 200. For example, a 5GC 210 (also referred to as Next Generation Core (NGC)) may be considered functionally as control plane (C-plane) functions 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane (U-plane) functions 212 (e.g., UE gateway functions, access to data networks, IP routing, etc.) that operate cooperatively to form a core network. A user plane interface (NG-U) 213 and a control plane interface (NG-C) 215 connect the gNB 222 to the 5GC 210, specifically to the user plane function 212 and the control plane function 214, respectively. In an additional configuration, the ng-eNB 224 may also be connected to the 5GC 210 via the NG-C 215 to the control plane function 214 and the NG-U 213 to the user plane function 212. Additionally, the ng-eNB 224 may communicate directly with the gNB 222 via a backhaul connection 223. In some configurations, the Next Generation RAN (NG-RAN) 220 may have one or more gNBs 222, while other configurations include one or more of both the ng-eNB 224 and the gNB 222. Either the gNB 222 or the ng-eNB 224 (or both) may communicate with one or more UEs 204 (e.g., any of the UEs described herein).

[0059] Another optional aspect may include a location server 230, which may be in communication with the 5GC 210 to provide location assistance to the UE(s) 204. The location servers 230 may be realized as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules 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 the UEs 204 that may connect to the location server 230 via the core network 5GC 210 and / or via the Internet (not shown). Furthermore, the location server 230 may be integrated into components of the core network, or alternatively, may be external to the core network (e.g., a third-party server, such as an original equipment manufacturer (OEM) server or a service server).

[0060] 2B illustrates another exemplary wireless network structure 250. A 5GC 260 (which may correspond to 5GC 210 in FIG. 2A) may be considered functionally as control plane functions provided by an access and mobility management function (AMF) 264 and user plane functions provided by a user plane function (UPF) 262, which operate cooperatively to form a core network (i.e., 5GC 260). The functions of the AMF 264 include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between one or more UEs 204 (e.g., any of the UEs described herein) and a session management function (SMF) 266, transparent proxy services for routing SM messages, access authentication and access authorization, transport for short message service (SMS) messages between the UE 204 and a short message service function (SMSF) (not shown), and security anchor functionality (SEAF). The AMF 264 also interacts with an authentication server function (AUSF) (not shown) and the UE 204 to receive intermediate keys established as a result of the UE 204 authentication process. In case of UMTS (universal mobile telecommunications system) subscriber identity module (USIM) based authentication, the AMF 264 retrieves security material from the AUSF. The AMF 264 functions also include security context management (SCM). The SCM receives keys from the SEAF that it uses to derive access network specific keys.The functionality of the AMF 264 also includes location service management for regulated services, transport for location service messages between the UE 204 and the Location Management Function (LMF) 270 (acting as the location server 230), transport for location service messages between the NG-RAN 220 and the LMF 270, Evolved Packet System (EPS) bearer identifier allocation for interworking with EPS, and UE 204 mobility event notification. In addition, the AMF 264 also supports functions for non-3GPP (Third Generation Partnership Project) access networks.

[0061] The functions of the UPF 262 include acting as an anchor point for intra / inter-RAT mobility (when applicable), acting as an external protocol data unit (PDU) session point for interconnection to a data network (not shown), routing and forwarding of packets, 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 in the downlink), uplink traffic validation (Service Data Flow (SDF) to QoS flow mapping), transport level packet marking in the uplink and downlink, downlink packet buffering and downlink data notification triggering, and sending and forwarding one or more "end markers" to the source RAN node. The UPF 262 may also support forwarding of location service messages on the user plane between the UE 204 and a location server such as the SLP 272.

[0062] The functions of the SMF 266 include session management, UE Internet protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering in the UPF 262 to route traffic to the appropriate destination, policy enforcement and control of part of QoS, and downlink data notification. The interface through which the SMF 266 communicates with the AMF 264 is called the N11 interface.

[0063] Another optional aspect may include an LMF 270, which may be in communication with the 5GC 260 to provide location assistance to the UE 204. The LMF 270 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules across multiple physical servers, etc.), or may alternatively each represent a single server. The LMF 270 may be configured to support one or more location services for the UE 204, which may be connected to the LMF 270 via a core network, the 5GC 260, and / or via the Internet (not shown). The SLP 272 may support similar functions as the LMF 270, while the LMF 270 may communicate with the AMF 264, the NG-RAN 220, and the UE 204 via the control plane (e.g., using interfaces and protocols intended to convey signaling messages rather than voice or data) and the SLP 272 may communicate with the UE 204 and external clients (e.g., third-party servers 274) via the user plane (e.g., using protocols intended to carry voice and / or data, such as Transmission Control Protocol (TCP) and / or IP).

[0064] Yet another optional aspect may include a third party server 274, which may be in communication with the LMF 270, the SLP 272, the 5GC 260 (e.g., via the AMF 264 and / or the UPF 262), the NG-RAN 220, and / or the UE 204 to obtain location information (e.g., a location estimate) for the UE 204. Thus, in some cases, the third party server 274 may be referred to as a location services (LCS) client or an external client. The third party servers 274 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.

[0065] A user plane interface 263 and a control plane interface 265 connect the 5GC 260, and in particular the UPF 262 and the AMF 264, respectively, to one or more gNBs 222 and / or ng-eNBs 224 in the NG-RAN 220. The interface between the gNB(s) 222 and / or ng-eNB(s) 224 and the AMF 264 is referred to as the “N2” interface, and the interface between the gNB(s) 222 and / or ng-eNB(s) 224 and the UPF 262 is referred to as the “N3” interface. The gNB(s) 222 and / or ng-eNB(s) 224 of the NG-RAN 220 may communicate directly with each other via a backhaul connection 223 referred to as the “Xn-C” interface. One or more of the gNBs 222 and / or ng-eNBs 224 may communicate with one or more UEs 204 via a wireless interface referred to as a “Uu” interface.

[0066] The functionality of the gNB 222 may be divided between a gNB Central Unit (gNB-CU) 226, eleven or more gNB Distributed Units (gNB-DU) 228, and eleven or more gNB Radio Units (gNB-RU) 229. The gNB-CU 226 is a logical node that includes base station functions such as forwarding user data, mobility control, radio access network sharing, positioning, session management, etc., except for those functions exclusively allocated to the gNB-DU(s) 228. More specifically, the gNB-CU 226 generally hosts the Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB 222. The gNB-DU 228 is a logical node that hosts the Radio Link Control (RLC) and Medium Access Control (MAC) layers of the gNB 222. Its operation is controlled by the gNB-CU 226. One gNB-DU 228 can support one or multiple cells, and one cell is supported by only one gNB-DU 228. The interface 232 between the gNB-CU 226 and one or more gNB-DUs 228 is referred to as the "F1" interface. The physical (PHY) layer functionality of the gNB 222 is generally hosted by eleven or more standalone gNB-RUs 229, which perform functions such as power amplification and signal transmission / reception. The interface between the gNB-DU 228 and the gNB-RU 229 is referred to as the "Fx" interface. Thus, the UE 204 communicates with the gNB-CU 226 via the RRC, SDAP, and PDCP layers, with the gNB-DU 228 via the RLC and MAC layers, and with the gNB-RU 229 via the PHY layer.

[0067] 3A, 3B, and 3C illustrate several example components (represented by corresponding blocks) that may be incorporated in a UE 302 (which may correspond to any of the UEs described herein), a base station 304 (which may correspond to any of the base stations described herein), and a network entity 306 (which may correspond to or embody any of the network functions described herein, including a location server 230 and an LMF 270, or alternatively, may be independent of the NG-RAN 220 and / or 5GC 210 / 260 infrastructure depicted in FIGS. 2A and 2B, such as a private network) to support file transmission operations taught herein. It will be understood that these components may be implemented in different types of devices in different implementations (e.g., in an ASIC, in a system on chip (SoC), etc.). The illustrated components may also be incorporated in other devices in a communication system. For example, other devices in the system may include components similar to the illustrated components to provide similar functionality. Also, a given device may include one or more of the components. For example, a device may contain multiple transceiver components that enable the device to operate on multiple carriers and / or communicate via different technologies.

[0068] The UE 302 and base station 304 each include one or more wireless wide area network (WWAN) transceivers 310 and 350, respectively, providing means for communicating (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) over one or more wireless communications networks (not shown), such as an NR network, an LTE network, a GSM network, etc. The WWAN transceivers 310 and 350 may each be connected to one or more antennas 316 and 356, respectively, for communicating with other network nodes, such as other UEs, access points, base stations (e.g., eNBs, gNBs), etc., over at least one designated RAT (e.g., NR, LTE, GSM, etc.) over a wireless communications medium of interest (e.g., some set of time / frequency resources in a particular frequency spectrum). The WWAN transceivers 310 and 350 may be variously configured to transmit and encode signals 318 and 358, respectively (e.g., messages, instructions, information, etc.), and conversely, to receive and decode signals 318 and 358, respectively (e.g., messages, instructions, information, pilots, etc.), in accordance with a designated RAT. In particular, the WWAN transceivers 310 and 350 include one or more transmitters 314 and 354, respectively, to transmit and encode signals 318 and 358, respectively, and include one or more receivers 312 and 352, respectively, to receive and decode signals 318 and 358, respectively.

[0069] The UE 302 and base station 304 also each, at least in some cases, include one or more short-range wireless transceivers 320 and 360, respectively. The short-range wireless transceivers 320 and 360 may be connected to one or more antennas 326 and 366, respectively, and may provide means for communicating (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) with other network nodes, such as other UEs, access points, base stations, etc., via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth, Zigbee, Z-Wave, PC5, Dedicated Short-Range Communications (DSRC), wireless access for vehicular environments (WAVE), Near Field Communication (NFC), etc.) over a wireless communication medium of interest. The short-range wireless transceivers 320 and 360 may be variously configured to transmit and encode signals 328 and 368, respectively (e.g., messages, instructions, information, etc.), and conversely, to receive and decode signals 328 and 368, respectively (e.g., messages, instructions, information, pilots, etc.), in accordance with a specified RAT. In particular, the short-range wireless transceivers 320 and 360 include one or more transmitters 324 and 364, respectively, to transmit and encode signals 328 and 368, respectively, and include one or more receivers 322 and 362, respectively, to receive and decode signals 328 and 368, respectively. As specific examples, the short-range wireless transceivers 320 and 360 may be WiFi transceivers, Bluetooth® transceivers, Zigbee® and / or Z-Wave® transceivers, NFC transceivers, or Vehicle-to-Vehicle (V2V) and / or Vehicle-to-Everything (V2X) transceivers.

[0070] The UE 302 and the base station 304 also, at least in some cases, include satellite signal receivers 330 and 370. The satellite signal receivers 330 and 370 may be connected to one or more antennas 336 and 376, respectively, and may provide means for receiving and / or measuring satellite positioning / communication signals 338 and 378, respectively. If the satellite signal receivers 330 and 370 are satellite positioning system receivers, the satellite positioning / communication signals 338 and 378 may be Global Positioning System (GPS) signals, Global Navigation Satellite System (GLONASS) signals, Galileo signals, Beidou signals, Navigation Satellite System of India (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. If the satellite signal receivers 330 and 370 are non-terrestrial network (NTN) receivers, the satellite positioning / communication signals 338 and 378 may be communication signals (e.g., carrying control and / or user data) originating from a 5G network. Satellite signal receivers 330 and 370 may comprise any suitable hardware and / or software for receiving and processing satellite positioning / communications signals 338 and 378, respectively. Satellite signal receivers 330 and 370 may request information and action from other systems as appropriate and, at least in some cases, perform calculations to determine the location of UE 302 and base station 304, respectively, using the acquired measurements according to any suitable satellite positioning system algorithms.

[0071] The base station 304 and the network entity 306 each include one or more network transceivers 380 and 390, respectively, that provide a means for communicating (e.g., a means for transmitting, a means for receiving, etc.) with other network entities (e.g., other base stations 304, other network entities 306). For example, the base station 304 may employ one or more network transceivers 380 to communicate with other base stations 304 or network entities 306 over one or more wired or wireless backhaul links. As another example, the network entity 306 may employ one or more network transceivers 390 to communicate with one or more base stations 304 over one or more wired or wireless backhaul links or with other network entities 306 over one or more wired or wireless core network interfaces.

[0072] A transceiver may be configured to communicate over a wired link or a wireless link. A transceiver (whether a wired transceiver or a wireless transceiver) includes transmitter circuitry (e.g., transmitters 314, 324, 354, 364) and receiver circuitry (e.g., receivers 312, 322, 352, 362). A transceiver may be an integrated device (e.g., embodying transmitter and receiver circuitry in a single device) in some implementations, may comprise separate transmitter circuitry and separate receiver circuitry in some implementations, or may be embodied in other ways in other implementations. The transmitter and receiver circuitry of a wired transceiver (e.g., network transceivers 380 and 390 in some implementations) may be coupled to one or more wired network interface ports. The wireless transmitter circuitry (e.g., transmitters 314, 324, 354, 364) may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array that enables the respective device (e.g., UE 302, base station 304) to perform transmit "beamforming," as described herein. Similarly, the wireless receiver circuitry (e.g., receivers 312, 322, 352, 362) may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array that enables the respective device (e.g., UE 302, base station 304) to perform receive beamforming, as described herein. In one aspect, the transmitter circuitry and the receiver circuitry may share multiple identical antennas (e.g., antennas 316, 326, 356, 366), such that the respective device can only receive or transmit at a given time, but not both at the same time. The wireless transceivers (eg, WWAN transceivers 310 and 350, short range wireless transceivers 320 and 360) may also include network listen modules (NLMs) and the like for performing various measurements.

[0073] As used herein, various wireless transceivers (e.g., transceivers 310, 320, 350, and 360, and network transceivers 380 and 390, in some implementations) and wired transceivers (e.g., network transceivers 380 and 390, in some implementations) may be generally characterized as a "transceiver," "at least one transceiver," or "one or more transceivers." Thus, whether a particular transceiver is a wired or wireless transceiver may be inferred from the type of communication being performed. For example, backhaul communications between network devices or servers generally involve signaling via wired transceivers, while wireless communications between a UE (e.g., UE 302) and a base station (e.g., base station 304) generally involve signaling via wireless transceivers.

[0074] The UE 302, base station 304, and network entity 306 also include other components that may be used in conjunction with operations as disclosed herein. The UE 302, base station 304, and network entity 306 each include one or more processors 332, 384, and 394, for example, to provide functionality related to wireless communications and to provide other processing functionality. Thus, the processors 332, 384, and 394 may comprise processing means, such as means for determining, means for calculating, means for receiving, means for transmitting, means for indicating, etc. In one aspect, the processors 332, 384, and 394 may include, for example, one or more general purpose processors, multi-core processors, central processing units (CPUs), ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGAs), other programmable logic devices or processing circuits, or various combinations thereof.

[0075] The UE 302, the base station 304, and the network entity 306 include memory circuitry implementing memories 340, 386, and 396, respectively (e.g., each including a memory device) for maintaining information (e.g., information indicating reserved resources, thresholds, parameters, etc.). Thus, the memories 340, 386, and 396 may provide storage means, retrieval means, maintenance means, etc. In some cases, the UE 302, the base station 304, and the network entity 306 may include sidelink resource components 342, 388, and 398, respectively. The sidelink resource components 342, 388, and 398 may be hardware circuits that are part of or coupled to the processors 332, 384, and 394, respectively, that, when executed, cause the UE 302, the base station 304, and the network entity 306 to perform the functions described herein. In other aspects, the sidelink resource components 342, 388, and 398 may be external to the processors 332, 384, and 394 (e.g., part of a modem processing system, integrated into another processing system, etc.). Alternatively, the sidelink resource components 342, 388, and 398 may be memory modules stored in the memories 340, 386, and 396, respectively, that when executed by the processors 332, 384, and 394 (or modem processing system, another processing system, etc.) cause the UE 302, the base station 304, and the network entity 306 to perform the functions described herein. Figure 3A illustrates a possible location of the sidelink resource component 342, which may be part of, for example, one or more WWAN transceivers 310, the memory 340, the one or more processors 332, or any combination thereof, or may be a stand-alone component. FIG. 3B shows a potential location of a sidelink resource component 388, which may be, for example, part of one or more WWAN transceivers 350, memory 386, one or more processors 384, or any combination thereof, or may be a stand-alone component.FIG. 3C shows a potential location of a sidelink resource component 398, which may be, for example, part of one or more network transceivers 390, memory 396, one or more processors 394, or any combination thereof, or may be a stand-alone component.

[0076] The UE 302 may include one or more sensors 344 coupled to the one or more processors 332 to provide a means for sensing or detecting movement and / or orientation information that is independent of movement data derived from signals received by the one or more WWAN transceivers 310, the one or more short-range wireless transceivers 320, and / or the satellite signal receiver 330. By way of example, the sensor(s) 344 may include an accelerometer (e.g., a microelectromechanical system (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric altimeter), and / or any other type of movement detection sensor. Additionally, the sensor(s) 344 may include multiple different types of devices and combine their outputs to provide movement information. For example, the sensor(s) 344 may use a combination of a multi-axis accelerometer and an orientation sensor to provide the ability to calculate a position in a two-dimensional (2D) and / or three-dimensional (3D) coordinate system.

[0077] Additionally, the UE 302 includes a user interface 346 that provides a means for providing indications to a user (e.g., audio and / or visual indications) and / or receiving user input (e.g., upon user actuation of a sensing device, such as a keypad, touch screen, microphone, etc.). Although not shown, the base station 304 and the network entity 306 may also include user interfaces.

[0078] Referring more particularly to the one or more processors 384, on the downlink, IP packets from the network entity 306 may be provided to the processor 384. The one or more processors 384 may implement functionality for an RRC layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer. The one or more processors 384 may provide RRC layer functions associated with broadcast of system information (e.g., Master Information Blocks (MIBs), System Information Blocks (SIBs)), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions, and RLC layer functions related to transfer of upper layer PDUs, error correction with automatic repeat request (ARQ), concatenation, segmentation, and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions related to mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

[0079] The transmitter 354 and receiver 352 may implement Layer 1 (L1) functions related to various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping onto the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The transmitter 354 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an orthogonal frequency division multiplexing (OFDM) subcarrier, multiplexed with reference signals (e.g., pilots) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying the time-domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 302. Each spatial stream may then be provided to one or more different antennas 356. The transmitter 354 may modulate an RF carrier with each spatial stream for transmission.

[0080] At the UE 302, the receiver 312 receives the signal through its respective antenna(s) 316. The receiver 312 recovers the information modulated onto the RF carriers and provides the information to one or more processors 332. The transmitter 314 and the receiver 312 perform layer 1 functions associated with various signal processing functions. The receiver 312 may perform spatial processing on the information to recover any spatial streams destined for the UE 302. If multiple spatial streams are destined for the UE 302, they may be combined by the receiver 312 into a single OFDM symbol stream. The receiver 312 then converts the OFDM symbol stream from the time domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the most likely signal constellation point transmitted by the base station 304. These soft decisions may be based on channel estimates calculated by a channel estimator. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 304. The data and control signals are then provided to one or more processors 332 that implement Layer 3 (L3) and Layer 2 (L2) functions.

[0081] In the uplink, one or more processors 332 provide demultiplexing between transport and logical channels, packet reassembly, decryption, header recovery, and control signal processing to recover IP packets from the core network. The one or more processors 332 are also responsible for error detection.

[0082] Similar to the functionality described in connection with downlink transmissions by the base station 304, the one or more processors 332 provide RRC layer functionality related to system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with forwarding of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via hybrid automatic repeat request (HARQ), priority handling, and logical channel prioritization.

[0083] Channel estimates derived by the channel estimator from a reference signal or feedback transmitted by the base station 304 may be used by the transmitter 314 to select an appropriate coding and modulation scheme and to facilitate spatial processing. The spatial streams generated by the transmitter 314 may be provided to different antenna(s) 316. The transmitter 314 may modulate an RF carrier with each spatial stream for transmission.

[0084] Uplink transmissions are processed at the base station 304 in a manner similar to that described with respect to the receiver function at the UE 302. The receiver 352 receives signals via its respective antenna(s) 356. The receiver 352 recovers the modulated information onto an RF carrier and provides the information to one or more processors 384.

[0085] In the uplink, the one or more processors 384 provide demultiplexing between transport and logical channels, packet reassembly, decryption, header recovery, and control signal processing to recover IP packets from the UE 302. The IP packets from the one or more processors 384 may be provided to a core network. The one or more processors 384 are also responsible for error detection.

[0086] For convenience, the UE 302, base station 304, and / or network entity 306 are illustrated in Figures 3A, 3B, and 3C as including various components that may be configured according to various examples described herein. However, it will be understood that the illustrated components may have different functions in different designs. In particular, various components in Figures 3A-3C are optional in alternative configurations, and various aspects include configurations that may vary due to design choice, cost, device use, or other considerations. For example, in the case of Figure 3A, a particular implementation of the UE 302 may omit the WWAN transceiver(s) 310 (e.g., a wearable device or tablet computer or PC or laptop may have Wi-Fi and / or Bluetooth capabilities without cellular capabilities), or may omit the short-range wireless transceiver(s) 320 (e.g., cellular only, etc.), or may omit the satellite signal receiver 330, or may omit the sensor(s) 344, etc. 3B, a particular implementation of base station 304 may omit WWAN transceiver(s) 350 (e.g., a Wi-Fi “hotspot” access point without cellular capability), or may omit short-range wireless transceiver(s) 360 (e.g., cellular only), or may omit satellite receiver 370, etc. For brevity, examples of various alternative configurations are not provided herein, but should be readily apparent to one of ordinary skill in the art.

[0087] The various components of the UE 302, base station 304, and network entity 306 may be communicatively coupled to one another via data buses 334, 382, ​​and 392, respectively. In an aspect, the data buses 334, 382, ​​and 392 may form or be part of communication interfaces of the UE 302, base station 304, and network entity 306, respectively. For example, when various logical entities are embodied within the same device (e.g., gNB and location server functionality integrated within the same base station 304), the data buses 334, 382, ​​and 392 may provide communication therebetween.

[0088] The components of Figures 3A, 3B, and 3C may be implemented in a variety of ways. In some implementations, the components of Figures 3A, 3B, and 3C may be implemented in one or more circuits, such as, for example, one or more processors and / or one or more ASICs (which may include one or more processors), where each circuit may use and / or incorporate at least one memory component for storing information or executable code used by the circuit to provide its functionality. For example, some or all of the functionality represented by blocks 310-346 may be performed by the processor and memory components of the UE 302 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor component(s)). Similarly, some or all of the functionality represented by blocks 350-388 may be performed by the processor and memory component(s) of the base station 304 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor component(s). Also, some or all of the functionality represented by blocks 390-398 may be performed by a processor and memory components of the network entity 306 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor component(s)). For simplicity, various operations, actions, and / or functions are described herein as being performed "by the UE," "by the base station," "by the network entity," etc. However, it will be understood that such operations, actions, and / or functions may actually be performed by a particular component or combination of components of the UE 302, base station 304, network entity 306, etc., such as the processors 332, 384, 394, transceivers 310, 320, 350, and 360, memories 340, 386, and 396, sidelink resource components 342, 388, and 398, etc.

[0089] In some designs, the network entity 306 may be implemented as a core network component. In other designs, the network entity 306 may be separate from the network operator or operation of the cellular network infrastructure (e.g., the NG RAN 220 and / or the 5GC 210 / 260). For example, the network entity 306 may be a component of a private network that may be configured to communicate with the UE 302 via the base station 304 or independently of the base station 304 (e.g., via a non-cellular communication link such as WiFi).

[0090] 4 illustrates an example of a wireless communication system 400 supporting wireless unicast sidelink establishment according to aspects of the disclosure. In some examples, the wireless communication system 400 may implement aspects of the wireless communication systems 100, 200, and 250. The wireless communication system 400 may include a first UE 402 and a second UE 404, which may be examples of any of the UEs described herein. As a specific example, the UEs 402 and 404 may correspond to the V-UEs 160 of FIG. 1.

[0091] In the example of Fig. 4, UE 402 may attempt to establish a unicast connection with UE 404 over a sidelink, which may be a V2X sidelink between UE 402 and UE 404. As a specific example, the established sidelink connection may correspond to sidelinks 162 and / or 168 in Fig. 1. The sidelink connection may be established in an omnidirectional frequency range (e.g., FR1) and / or a mmW frequency range (e.g., FR2). In some cases, UE 402 may be referred to as an initiating UE that initiates the sidelink connection procedure, and UE 404 may be referred to as a target UE that is targeted for the sidelink connection procedure by the initiating UE.

[0092] To establish a unicast connection, Access Stratum (AS) (a functional layer in the UMTS and LTE protocol stacks, and part of Layer 2, between the RAN and the UE responsible for transporting data over the wireless link and managing radio resources) parameters may be configured and negotiated between the UE 402 and the UE 404. For example, transmit and receive capability matching may be negotiated between the UE 402 and the UE 404. Each UE may have different capabilities (e.g., transmit and receive, 64 quadrature amplitude modulation (QAM), transmit diversity, carrier aggregation (CA), supported communication frequency band(s), etc.). In some cases, different services may be supported at higher layers of the corresponding protocol stacks for the UE 402 and the UE 404. In addition, a security association may be established between the UE 402 and the UE 404 for the unicast connection. Unicast traffic may benefit from security protection (e.g., integrity protection) at the link level. Security requirements may differ for different wireless communication systems. For example, V2X and Uu systems may have different security requirements (e.g., Uu security does not include confidentiality protection). In addition, IP configurations (e.g., IP version, addresses, etc.) may be negotiated for unicast connections between UE 402 and UE 404.

[0093] In some cases, the UE 404 may create a service announcement (e.g., a service capability message) to transmit over a cellular network (e.g., cV2X) to assist in sidelink connection establishment. Conventionally, the UE 402 may identify and locate candidates for sidelink communication based on a broadcasted basic service message (BSM) decrypted by a nearby UE (e.g., the UE 404). The BSM may include location information, security and identification information, and vehicle information (e.g., speed, operation, size, etc.) for the corresponding UE. However, in the case of a different wireless communication system (e.g., D2D or V2X communication), the discovery channel may not be configured to allow the UE 402 to detect the BSM(s). Thus, the service announcement (e.g., discovery signal) transmitted by the UE 404 and other nearby UEs may be a higher layer signal and may be broadcast (e.g., in an NR sidelink broadcast). In some cases, the UE 404 may include one or more parameters for itself in the service announcement, including connection parameters and / or capabilities it possesses. The UE 402 may then monitor for and receive the broadcasted service announcements to identify possible UEs for a corresponding sidelink connection. In some cases, the UE 402 may identify possible UEs based on the capabilities that each UE indicates in their respective service announcements.

[0094] The service announcement may include information to assist the UE 402 (e.g., or any initiating UE) in identifying the UE (UE 404 in the example of FIG. 4) that is sending the service announcement. For example, the service announcement may include channel information in which the direct communication request may be sent. In some cases, the channel information may be RAT specific (e.g., LTE or NR specific) and may include a resource pool in which the UE 402 sends the communication request. Additionally, the service announcement may include a specific destination address (e.g., Layer 2 destination address) for the UE if the destination address is different from the current address (e.g., the address of the streaming provider or the UE sending the service announcement). The service announcement may also include a network layer or transport layer in which the UE 402 sends the communication request. For example, the network layer (also referred to as "Layer 3" or "L3") or transport layer (also referred to as "Layer 4" or "L4") may indicate a port number of the application 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. Additionally, the service announcement may include the type of protocol for certificate establishment and QoS related parameters.

[0095] After identifying a possible sidelink connection target (UE 404 in the example of FIG. 4), the initiating UE (UE 402 in the example of FIG. 4) may send a connection request 415 to the identified target UE 404. In some cases, the connection request 415 may be a first RRC message (e.g., an "RRC Setup Request" message) sent by the UE 402 to request a unicast connection with the UE 404. For example, the unicast connection may utilize a PC5 interface for sidelink, and the connection request 415 may be an RRC Connection Setup Request message. Additionally, the UE 402 may transport the connection request 415 using the sidelink signaling radio bearer 405.

[0096] After receiving the connection request 415, the UE 404 may determine whether to accept or reject the connection request 415. The UE 404 may base this decision on transmit / receive capabilities, the ability to accommodate a unicast connection over the sidelink, the particular service indicated for the unicast connection, the content to be transmitted over the unicast connection, or a combination thereof. For example, if the UE 402 desires to use a first RAT to transmit or receive data, but the UE 404 does not support the first RAT, the UE 404 may reject the connection request 415. Additionally or alternatively, the UE 404 may reject the connection request 415 based on an inability to accommodate a unicast connection over the sidelink due to limited radio resources, scheduling issues, etc. Thus, the UE 404 may send an indication of whether the request was accepted or rejected in the connection response 420. Similar to the UE 402 and the connection request 415, the UE 404 may transport the connection response 420 using the sidelink signaling radio bearer 410. Additionally, the connection response 420 may be a second RRC message sent by the UE 404 in response to the connection request 415 (e.g., an “RRCResponse” message).

[0097] In some cases, the sidelink signaling radio bearers 405 and 410 may be the same sidelink signaling radio bearer or may be separate sidelink signaling radio bearers. Thus, a radio link control (RLC) layer acknowledged mode (AM) may be used for the sidelink signaling radio bearers 405 and 410. UEs supporting unicast connections may listen on 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., control plane) instead of the V2X layer (e.g., data plane).

[0098] If the connection response 420 indicates that the UE 404 accepted the connection request 415, the UE 402 may then send a connection establishment 425 message on the sidelink signaling radio bearer 405 to indicate that the unicast connection setup is complete. In some cases, the connection establishment 425 may be a third RRC message (e.g., an "RRC Setup Complete" message). Each of the connection request 415, the connection response 420, and the connection establishment 425 may enable each UE to receive and decode the corresponding transmission (e.g., an RRC message) using basic capabilities when in transport from one UE to the other UE.

[0099] Additionally, an identifier may be used for each of the connection request 415, the connection response 420, and the connection establishment 425. For example, the identifier may indicate which UE 402 / 404 is sending which message and / or which UE 402 / 404 the message is intended for. For physical (PHY) layer channels, the RRC signaling and any subsequent data transmissions may use the same identifier (e.g., Layer 2 ID). However, for logical channels, the identifiers may be separate for the RRC signaling and for the data transmissions. For example, on logical channels, the RRC signaling and the data transmissions may be treated differently and may have different acknowledgement (ACK) feedback messaging. In some cases, for RRC messaging, a physical layer ACK may be used to ensure that the corresponding message is transmitted and received correctly.

[0100] For the UE 402 and / or UE 404, one or more information elements may be included in the connection request 415 and / or connection response 420, respectively, to enable negotiation of corresponding AS layer parameters for the unicast connection. For example, the UE 402 and / or UE 404 may include Packet Data Convergence Protocol (PDCP) parameters in the corresponding unicast connection setup message to set up a PDCP context for the unicast connection. In some cases, the PDCP context may indicate whether PDCP duplication is utilized for the unicast connection. In addition, the UE 402 and / or UE 404 may include RLC parameters when establishing the unicast connection to set up an RLC context for the unicast connection. For example, the RLC context may indicate whether AM (e.g., reordering timer (t-reordering) is used) or unacknowledged mode (UM) is used for the RLC layer of the unicast communication.

[0101] In addition, the UE 402 and / or UE 404 may include medium access control (MAC) parameters for setting up a MAC context for a unicast connection. In some cases, the MAC context may enable a resource selection algorithm, a hybrid automatic repeat 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 the unicast connection. In addition, the UE 402 and / or UE 404 may include PHY layer parameters when establishing a unicast connection for setting up a PHY layer context for the unicast connection. For example, the PHY layer context may indicate a transmission format (if a transmission profile is not included per UE 402 / 404) and a radio resource configuration (e.g., bandwidth portion (BWP), numerology, etc.) for the unicast connection. These information elements may be supported for different frequency range configurations (e.g., FR1 and FR2).

[0102] In some cases, a security context may also be set for the unicast connection (e.g., after the connection establishment 425 message is sent). Before a security association (e.g., security context) is established between the UE 402 and the UE 404, the sidelink signaling radio bearers 405 and 410 may not be protected. After the security association is established, the sidelink signaling radio bearers 405 and 410 may be protected. Thus, the security context may enable secure data transmission over the unicast connection as well as the sidelink signaling radio bearers 405 and 410. Furthermore, IP layer parameters (e.g., link-local IPv4 or IPv6 addresses) may also be negotiated. In some cases, the IP layer parameters may be negotiated by a higher layer control protocol operating after the RRC signaling is established (e.g., the unicast connection is established). As mentioned above, the UE 404 may base its decision whether to accept or reject a connection request 415 for a particular service indicated for a unicast connection and / or the content (e.g., higher layer information) to be transmitted over the unicast connection. The particular service and / or content may also be indicated by higher layer control protocols operating after RRC signaling is established.

[0103] After the unicast connection is established, the UE 402 and the UE 404 may communicate using a unicast connection over the sidelink 430, where sidelink data 435 is transmitted between the two UEs 402 and 404. The sidelink 430 may correspond to the sidelinks 162 and / or 168 of FIG. 1. In some cases, the sidelink data 435 may include RRC messages transmitted between the two UEs 402 and 404. To maintain this unicast connection over the sidelink 430, the UE 402 and / or the UE 404 may transmit keep alive messages (e.g., "RRCLinkAlive" messages, fourth RRC messages, etc.). In some cases, the keep alive messages may be triggered (e.g., event triggered) periodically or on demand. Thus, the triggering and transmission of the keep alive messages may be invoked by the UE 402 or by both the UE 402 and the UE 404. Additionally or alternatively, a MAC Control Element (CE) (e.g., defined over sidelink 430) may be used to monitor the status of the unicast connection on sidelink 430 and maintain the connection. When the unicast connection is no longer needed (e.g., when UE 402 has moved far enough away from UE 404), either UE 402 and / or UE 404 may initiate a release procedure to remove the unicast connection over sidelink 430. Thus, no subsequent RRC messages may be transmitted between UE 402 and UE 404 on the unicast connection.

[0104] NR supports several cellular network-based positioning techniques, including downlink-based positioning methods, uplink-based positioning methods, and downlink- and uplink-based positioning methods. Downlink-based positioning methods include observed time difference of arrival (OTDOA) in LTE, downlink time difference of arrival (DL-TDOA) in NR, and downlink angle-of-departure (DL-AoD) in NR. FIG. 5 illustrates examples of various positioning methods according to aspects of the present disclosure. In an OTDOA or DL-TDOA positioning procedure illustrated by scenario 510, a UE measures the difference between the times of arrival (ToA) of reference signals (e.g., positioning reference signals (PRS)) received from pairs of base stations, called reference signal time difference (RSTD) or time difference of arrival (TDOA) measurements, and reports them to a positioning entity. More specifically, the UE receives an identifier (ID) of a reference base station (e.g., a serving base station) and multiple non-reference base stations in the assistance data. The UE then measures the RSTD between the reference base station and each of the non-reference base stations. Based on the known locations of the involved base stations and the RSTD measurements, a positioning entity (e.g., the UE in case of UE-based positioning, or a location server in case of UE-assisted positioning) can estimate the location of the UE.

[0105] For DL-AoD positioning illustrated by scenario 520, the positioning entity determines the angle(s) between the UE and the transmitting base station(s) using beam reports from the UE of received signal strength measurements of multiple downlink transmit beams. The positioning entity can then estimate the location of the UE based on the determined angle(s) and the known location(s) of the transmitting base station(s).

[0106] Uplink-based positioning methods include uplink time difference of arrival (UL-TDOA) and uplink angle-of-arrival (UL-AoA). UL-TDOA is similar to DL-TDOA, but is based on an uplink reference signal (e.g., Sounding Reference Signal (SRS)) transmitted by the UE. For UL-AoA positioning, one or more base stations measure the received signal strength of one or more uplink reference signals (e.g., SRS) received from the UE on one or more uplink receive beams. The positioning entity uses the signal strength measurements and the angle(s) of the receive beam(s) to determine the angle(s) between the UE and the base station(s). Based on the determined angle(s) and the known location(s) of the base station(s), the positioning entity can then estimate the location of the UE.

[0107] Downlink and uplink based positioning methods include extended cell ID (E-CID) positioning, and multiple round trip time (RTT) positioning (also called "multi-cell RTT" and "multi-RTT"). In an RTT procedure, a first entity (e.g., a base station or a UE) transmits a first RTT-related signal (e.g., a PRS or an SRS) to a second entity (e.g., a UE or a base station), and the second entity transmits a second RTT-related signal (e.g., an SRS or a PRS) back to the first entity. Each entity measures the time difference between the time of arrival (ToA) of the received RTT-related signal and the transmission time of the transmitted RTT-related signal. This time difference is called the reception-to-transmission (Rx-Tx) time difference. The Rx-Tx time difference measurement may be made or adjusted to include only the time difference between the nearest subframe boundaries for the received and transmitted signals. Both entities may then send their Rx-Tx time difference measurements to a location server (e.g., LMF 270), which calculates the round trip propagation time (i.e., RTT) between the two entities from the two Rx-Tx time difference measurements (e.g., as the sum of the two Rx-Tx time difference measurements). Alternatively, one entity may send its Rx-Tx time difference measurements to the other entity, which then calculates the RTT. The distance between the two entities may be determined from the RTT and a known signal speed (e.g., the speed of light). In the case of multi-RTT positioning illustrated by scenario 530, a first entity (e.g., a UE or a base station) performs an RTT positioning procedure with multiple second entities (e.g., multiple base stations or UEs) to enable the location of the first entity to be determined (e.g., using multilateration) based on the distance to the second entity and the known location of the second entity. As illustrated by scenario 540, RTT and multi-RTT methods can be combined with other positioning techniques, such as UL-AoA and DL-AoD, to improve location accuracy.

[0108] The E-CID positioning method is based on Radio Resource Management (RRM) measurements. In E-CID, the UE reports the serving cell ID, timing advance (TA), and identities of detected neighboring base stations, estimated timing, and signal strength. The location of the UE is then estimated based on this information and the known location of the base station(s).

[0109] To assist the positioning operation, a location server (e.g., location server 230, LMF 270, SLP 272) may provide assistance data to the UE. For example, the assistance data may include an identifier of the base station (or cell / TRP of the base station) from which to measure the reference signal, reference signal configuration parameters (e.g., number of consecutive positioning subframes, periodicity of the positioning subframes, muting sequence, frequency hopping sequence, reference signal identifier, reference signal bandwidth, etc.), and / or other parameters applicable to a particular positioning method. Alternatively, the assistance data may be obtained directly from the base station itself (e.g., in periodically broadcasted overhead messages, etc.). In some cases, the UE may be able to detect neighboring network nodes itself without using the assistance data.

[0110] In the case of OTDOA or DL-TDOA positioning procedures, the assistance data may further include an expected RSTD value and an associated uncertainty around the expected RSTD, i.e., a search window. In some cases, the value range for the expected RSTD may be + / - 500 microseconds (μs). In some cases, the value range for the expected RSTD uncertainty may be + / - 32 μs when any of the resources used for the positioning measurements are in FR1. In other cases, the value range for the expected RSTD uncertainty may be + / - 8 μs when all of the resources used for the positioning measurement(s) are in FR2.

[0111] A location estimate may be referred to by other names, such as a position estimate, location, position, position fix, fix, etc. A location estimate may be geodetic and comprise coordinates (e.g., latitude, longitude, and possibly altitude), or urban and comprise a street address, postal address, or some other linguistic description of a location. A location estimate may also be defined relative to some other known location, or defined absolutely (e.g., using latitude, longitude, and possibly altitude). A location estimate may include an expected error or uncertainty (e.g., by including an area or volume within which the location is expected to lie with some specified or default level of confidence).

[0112] FIG. 6 illustrates time and frequency resources used for sidelink communication. The time-frequency grid 600 is divided into subchannels in the frequency domain and into time slots in the time domain. Each subchannel comprises a number (e.g., 10, 15, 20, 25, 50, 75, or 100) of physical resource blocks (PRBs), and each slot includes a number (e.g., 14) of OFDM symbols. Sidelink communication may be (pre)configured to occupy fewer than 14 symbols in a slot. For automatic gain control (AGC) settling, the first symbol of a slot is repeated on the preceding symbol. The exemplary slot illustrated in FIG. 4 includes a physical sidelink control channel (PSCCH) portion and a physical sidelink shared channel (PSSCH) portion, with the PSCCH followed by a gap symbol. The PSCCH and PSSCH are transmitted in the same slot.

[0113] Sidelink communication takes place within a transmit or receive resource pool. Sidelink communication occupies one slot and eleven or more subchannels. Some slots are not available for sidelink and some slots include feedback resources. Sidelink communication may be pre-configured (e.g., preloaded on the UE) or configured (e.g., by the base station via RRC). The configuration in FIG. 6 is an example of a sidelink slot configuration, but other configurations are possible (e.g., some sidelink slot configurations may include two or more minislots, some sidelink slot configurations may be multiplexed with UL or DL ​​communication, some sidelink slot configurations may include a Physical Sidelink Feedback Channel (PSFCH) to the ACK and / or NACK PSSCH(s) of the previous slot, etc.).

[0114] In addition to downlink-based, uplink-based, and downlink-and-uplink-based positioning methods, NR supports various sidelink positioning techniques. For example, link-level ranging signals can be used to estimate the distance between a pair of V-UEs or between a V-UE and a roadside unit (RSU), similar to the round-trip-time (RTT) positioning procedure.

[0115] FIG. 7 illustrates an example wireless communication system 700 in which a V-UE 704 is exchanging ranging signals with an RSU 710 and another V-UE 706 according to an aspect of the disclosure. As illustrated in FIG. 7, a wideband (e.g., FR1) ranging signal (e.g., Zadoff Chu sequence) is transmitted by both endpoints (e.g., V-UE 704 and RSU 710, and V-UE 704 and V-UE 706). In an aspect, the ranging signal may be a Sidelink Positioning Reference Signal (SL-PRS) transmitted by the participating V-UE 704 and V-UE 706 on uplink resources. Upon receiving the ranging signal from the transmitter (e.g., V-UE 704), the receiver (e.g., RSU 710 and / or V-UE 706) responds by sending a ranging signal that includes a measurement of the difference between the reception time of the ranging signal and the transmission time of the response ranging signal, referred to as the receiver receive-transmit (Rx-Tx) time difference measurement.

[0116] Upon receiving the reply ranging signal, the transmitter (or other positioning entity) can calculate the RTT between the transmitter and the receiver based on the receiver's Rx-Tx time difference measurement and a measurement of the difference between the transmission time of the first ranging signal and the reception time of the reply ranging signal (referred to as the transmitter's transmit-receive (Tx-Rx) time difference measurement). The transmitter (or other positioning entity) uses the RTT and the speed of light to estimate the distance between the transmitter and the receiver. If one or both of the transmitter and receiver are beamforming capable, it may also be possible to determine the angle between the V-UE 704 and the V-UE 706. Additionally, if the receiver provides its Global Positioning System (GPS) location in the reply ranging signal, the transmitter (or other positioning entity) may be able to determine the absolute location of the transmitter as opposed to the relative location of the transmitter with respect to the receiver.

[0117] As can be seen, the ranging accuracy improves with the bandwidth of the ranging signal. In particular, a higher bandwidth can better separate different multipaths of the ranging signal.

[0118] Note that this positioning procedure assumes that the V-UEs involved are time synchronized (i.e., their system frame time is the same as the other V-UE(s) or has a known offset relative to the other V-UE(s). In addition, although Figure 7 shows two V-UEs, it will be appreciated that they do not have to be V-UEs, but instead may be any other type of UE capable of sidelink communication.

[0119] 8 illustrates a sidelink communication scheduling (or resource allocation) scheme 800 according to an aspect of the disclosure. In some designs, resource allocation in V2X may be performed via Mode 1, where the gNB assigns Tx resources for sidelink communication over DCI3_0. In other designs, resource allocation in V2X may be performed via Mode 2, where the transmitting UE autonomously determines resources for sidelink communication. In some designs, the behavior of the receiving UE is the same in both Mode 1 and Mode 2.

[0120] Referring to FIG. 8, mode 1 supports dynamic grant (DG), configured grant (CG) type 1, and CG type 2. In some designs, CG type 1 is activated via RRC signaling from the gNB. DCI 3_0 is transmitted by the gNB to the allocated time and frequency resources to indicate the transmission timing. In some designs, the modulation and coding scheme (MCS) MCS is left to the UE within the limits set by the gNB. In mode 2, the transmitting UE performs channel sensing by blind decoding all PSCCH channels and finds the reserved resources by other sidelink transmissions. The transmitting UE reports the available resources to the higher layer, and the higher layer decides the resource usage.

[0121] 5G NR V2X / sidelink communications are being introduced in 3GPP® Rel-16 / 17. In Rel-16 / 17 V2X / sidelink communications, several sidelink signals / physical channels are specified for transmission in either the cellular spectrum (i.e., SL shared spectrum in licensed cellular bands) or the dedicated Intelligent Transport System (ITS) spectrum. Sidelink positioning will be introduced in 3GPP® Rel-18. Several designs are focused on sidelink-based high precision positioning for V2X, public safety, and commercial use cases.

[0122] Sidelink positioning can support both relative and absolute positioning. Relative positioning (e.g., ranging) is related to the determination of the distance between two UEs. Absolute positioning is related to the determination of the geographic coordinates of the UE. Sidelink positioning can be performed based on measurements of sidelink positioning reference signals (PRS) transmitted over the sidelink. Location estimation can be based on measurements of ToA, TDoA, AoA, RTT, etc. of the SL-PRS. The location estimation accuracy is mainly determined by the SL-PRS bandwidth.

[0123] Some sidelink / V2X applications have very high accuracy requirements. For example, sub-meter level accuracy may be required to support vehicle steering cooperation. Therefore, PRS transmissions with very large bandwidths (e.g., about 100 MHz or more) may be used. Current ITS spectrum for V2X may not have such wideband available. For example, depending on the region, only 20-30 MHz of ITS bandwidth may be available for V2X. In some designs, transmitting sidelink PRS over a 20-30 MHz bandwidth may not provide the required positioning accuracy.

[0124] One possibility is to transmit the SL-PRS in an unlicensed spectrum. For example, UN-II 3 or UN-II 5 have a large bandwidth available. However, the unlicensed spectrum may be shared by other technologies (e.g., Wi-Fi) and access to the unlicensed spectrum may be subject to regulatory requirements. For example, one requirement in the unlicensed spectrum may be a contention-based protocol such as listen before talk (LBT), where a device must perform sensing (listen) to clear the channel before the device can transmit (talk).

[0125] For most LBTs, a device typically measures energy and decides to transmit if the measured energy is below a threshold. For example, Category (CAT) 1 LBT includes LBT without sensing (can transmit immediately; similar to Type 2c channel access in NR-U). In another example, CAT 2 LBT includes LBT with energy sensing but without random backoff (can transmit if the sensed energy is below a threshold for a certain period of time; similar to Type 2a / 2b channel access in NR-U). In another example, CAT 4 LBT includes LBT with random backoff with a variable-sized contention window (can transmit if the sensed energy in the contention window is below a threshold; similar to Type 1 channel access in NR-U). It should be noted that CAT 1 / 2 LBT is only allowed in certain scenarios.

[0126] When an SL-PRS is transmitted in an unlicensed spectrum, the transmission opportunity may be uncertain. This is due to the uncertainty from the LBT, i.e., the transmitter can transmit only if the LBT is successful. In addition to the PRS, a positioning assistance message may also be required in some designs. The positioning assistance message may be sent before and / or after the SL PRS transmission to carry SL positioning related configurations (e.g., PRS configurations, etc.), SL positioning related measurements (ToAs, etc.), etc. In some designs, the positioning assistance message may also be transmitted over the sidelink (between UEs), potentially in licensed or ITS bands (i.e., similar to a normal sidelink transmission).

[0127] In some designs, SL positioning may be performed between two or more UEs. For example, for RTT-based positioning, UE1 may send a PRS to UE2, and UE2 may also send a PRS to UE1, and the range between the two UEs may be calculated based on the round-trip time of the PRS. In another example, for sidelink positioning with RSU participation (a special UE that may be fixed), multiple UEs may perform positioning based on PRS transmissions from the RSUs and UEs.

[0128] One option to reduce the uncertainty of SL-PRS transmission in unlicensed spectrum is to enable sharing of channel occupancy (CO, or COT). For example, UE1 performs channel access (e.g., CAT 4 LBT) and transmits a PRS upon successful channel access. UE2 transmits a PRS upon detecting UE1's PRS transmission (UE1 has initiated a COT; this is shared with UE2). In some designs, at least CAT 4 LBT may be waived in UE2 for its PRS transmission in a COT sharing manner (e.g., a gap between two PRS transmissions not larger than a threshold (e.g., 25 μs) is allowed) (e.g., UE2 performs CAT 1 or 2 LBT).

[0129] In a PRS transmission, the UE that initiates the COT is called the initiator (e.g., UE1), and the UE(s) that share the COT following the initiator's transmission are called the responder (e.g., UE2). In a SL positioning capability, there can be one initiator and one or multiple responders.

[0130] SL PRS transmission in unlicensed spectrum may be on a COT sharing basis as described above. Two or more UEs may form a group for SL PRS transmission (e.g., a handshake is performed for UE grouping). The UEs in the group may agree on or be indicated a time resource location (t1) where the PRS transmission may begin. The transmission of the PRS (starting at t1) may be subject to LBT. One of the UEs in the group (the initiator) may perform a (CAT 4) LBT towards transmitting the PRS at t1. If the initiator's LBT is not successful at / before t1 (e.g., the channel is occupied by others), the initiator may continue to sense the channel and transmit the PRS after the LBT is successful, the time after which (t1+t_delta1) is unknown to the responder(s). Other UEs (responders) in the group may blindly detect the initiator PRS starting from t1 to determine if and when the PRS CO (or COT) was initiated by the initiator UE. If the initiator PRS is detected, the responder UE(s) may share the PRS COT and transmit its PRS. CAT 4 LBT may be waived at the responder UE if it shares the COT (e.g., only does CAT 1 or CAT 2 LBT).

[0131] In this scenario, problems arise due to the uncertainty of PRS transmission in unlicensed spectrum. For example, the responder UE keeps trying to detect the SL PRS from the initiator, which is not optimal from a power consumption perspective. Also, the responder UE may not be able to prepare the SL PRS for reply to the initiator UE until it detects the initiator's PRS, in which case the turnaround time at the responder UE becomes very tight (due to the time uncertainty).

[0132] Aspects of the present disclosure are directed to a sidelink PRS pattern for a sidelink estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium. In contrast to the scenario described above where only a PRS transmission opportunity for a responder UE is ascertainable once an initiator UE's PRS is detected, the use of a sidelink PRS pattern may improve certainty in terms of PRS transmission opportunity location. Such aspects may provide various technical advantages, such as reduced power consumption and streamlined PRS preparation in the responder UE(s).

[0133] 9 illustrates an example process 900 of wireless communication according to an aspect of the disclosure. In one aspect, the process 900 may be performed by a first UE, such as UE 302. Specifically, the first UE corresponds to an initiator UE (e.g., the only initiator UE associated with a UE group or one of multiple opportunistic initiator UEs associated with a UE group).

[0134] 9, at 910, a first UE (e.g., processor(s) 332, sidelink resource component 342, etc.) determines a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium. For example, the shared communication medium may correspond to an unlicensed spectrum (e.g., where other traffic, such as Wi-Fi, may be transmitted). In one example, each PRS transmission opportunity may correspond to a time-frequency (TF) resource, although the size of each PRS transmission opportunity need not be the same, as described in more detail below. The means for performing the determination of 910 may include the processor(s) 332, sidelink resource component 342, etc. of the UE 302.

[0135] 9, at 920, the first UE (e.g., transmitter 314 or 324, receiver 312 or 322, processor(s) 332, sidelink resource component 342, etc.) performs one or more attempts to transmit the first PRS in one or more PRS transmission opportunities associated with the first UE according to a sidelink PRS pattern. For example, the one or more attempts at 920 may be subject to a contention-based protocol (e.g., LBT), as described in more detail below. The means for performing the transmission at 920 may include the transmitter 314 or 324, receiver 312 or 322, processor(s) 332, sidelink resource component 342, etc. of the UE 302.

[0136] FIG. 10 illustrates an example process 1000 of wireless communication according to aspects of the disclosure. In one aspect, the process 1000 may be performed by a second UE, such as UE 302. Specifically, the second UE corresponds to a responder UE that is monitoring PRS from an initiator UE or an "intervening" responder UE (e.g., a UE that attempts to respond with a SL PRS in association with a COT initiated by an initiator UE of a UE group), as described in more detail below. However, in some aspects, the COT may be canceled due to lack of PRS detection, which may transition the second UE from a responder UE to an opportunistic initiator UE (e.g., to initiate a new COT) accordingly.

[0137] 10, at 1010, the second UE (e.g., processor(s) 332, sidelink resource component 342, etc.) determines a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of the group of UEs in a shared communication medium. For example, the shared communication medium may correspond to an unlicensed spectrum (e.g., where other traffic, such as Wi-Fi, may be transmitted). In one example, each PRS transmission opportunity may correspond to a time-frequency (TF) resource, although the size of each PRS transmission opportunity need not be the same, as described in more detail below. The means for performing the determination of 1010 may include the processor(s) 332, sidelink resource component 342, etc. of the UE 302.

[0138] 10, at 1020, the second UE (e.g., receiver 312 or 322, processor(s) 332, sidelink resource component 342, etc.) monitors the first PRS transmission opportunity for receiving the first PRS from the first UE according to the sidelink PRS pattern. As mentioned above, the one or more attempts at 920 may be subject to a contention-based protocol (e.g., LBT), and thus reception of the first PRS at 1020 may not be guaranteed. The means for performing the monitoring at 1020 may include the receiver 312 or 322, processor(s) 332, sidelink resource component 342, etc. of the UE 302.

[0139] 9-10 , in some designs, two or more UEs may form a positioning group based on a handshake procedure (e.g., based on a handshake procedure performed based on a message exchange between the UEs). In one example, two UEs are grouped together for PRS measurement for sidelink ranging. In another example, one RSU and one or more UEs are grouped together, and each of the UEs may intend to range itself to the RSU (e.g., the RSUs may be stationary and have known geographic locations). In some designs, a sidelink PRS pattern may be associated with a starting location and duration and may include a PRS transmission opportunity for each of the UEs in the group. In some designs, there are multiple PRS transmission opportunities for each UE in the sidelink PRS pattern. In some designs, the sidelink PRS pattern may be determined by one of the UEs and announced during group formation. In some designs, the UEs in the group may perform channel access prior to their respective PRS transmission opportunities. In some designs, channel access may be an energy sensing based LBT procedure, a PRS detection based approach, or a hybrid LBT plus PRS detection approach, as described in more detail below.

[0140] 9-10 , in some designs, the group of UEs includes a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE. An example of this aspect is shown in FIG. 11 .

[0141] FIG. 11 illustrates a sidelink PRS pattern 1100 according to an aspect of the disclosure. In FIG. 11, the UE group includes X UEs (X=4 UEs in this case, counting initiator UE+responder UEs 1-3), and the sidelink PRS pattern includes a total of 12 PRS transmission opportunities, with 6 PRS transmission opportunities (N=6) allocated to the initiator UE and another 6 PRS transmission opportunities (N=6) split between responder UEs 1-3. In FIG. 11, the PRS transmission opportunities for the initiator UE are followed by the PRS transmission opportunities for each responder UE. Responder UEs 1-3 each have the same number M of PRS transmission opportunities (i.e., M=2 PRS transmission opportunities for each responder UE). Thus, there are M×(X−1)=N PRS transmission opportunities (N=2×3=6 in this case) for the initiator UE. The total number of PRS transmission opportunities is M×(X−1)+M×(X−1) (in this case 2×3+2×3=12).

[0142] With reference to FIG. 11 , in some designs, a time location of a sidelink PRS pattern may be indicated to a UE group. For example, the sidelink PRS pattern may be determined during group formation and indicated to the UE (e.g., by the initiator UE). In some designs, the time location includes a starting location and duration of the sidelink PRS pattern. In some designs, a PRS opportunity allocation in the sidelink PRS pattern may also be indicated to the UE as part of the pattern information. In some designs, the initiator UE performs channel access for transmitting a PRS at the initiator UE's PRS transmission opportunity. For example, the initiator UE may perform a CAT 4 LBT to transmit its SL PRS (e.g., Type 1 channel access). In some designs, if the initiator UE is successful in the LBT / channel access (which would also initiate a COT), the initiator UE may transmit a PRS. In some designs, the initiator UE may transmit only at the initiator UE's PRS opportunity. In some designs, the responder UE may detect the PRS at the initiator PRS opportunity(s). This detection may indicate that the initiator PRS has been transmitted or may convey whether the initiator PRS has been transmitted (and thus whether the COT has started). The responder UE may detect the initiator PRS only at the initiator PRS opportunity prior to its corresponding PRS opportunity (e.g., in FIG. 11 , this means that UE1 attempts to detect the initiator PRS at PRS transmission opportunity 1 and (optionally) PRS transmission opportunity 7, UE2 attempts to detect the initiator PRS at PRS transmission opportunity 3 and (optionally) PRS transmission opportunity 9, and UE3 attempts to detect the initiator PRS at PRS transmission opportunity 5 and (optionally) PRS transmission opportunity 11). In some designs, if the initiator PRS is detected, the responder UE may transmit its PRS during a subsequent PRS opportunity (which is the responder UE's PRS opportunity).In some designs, the responder UE may transmit a PRS based on CAT 1 LBT (Type 2c channel access) or CAT 2 LBT (Type 2a / 2b channel access) (hence, the PRS transmission of the responder UE is assumed to be in the COT sharing scheme).

[0143] Figure 12 illustrates a sidelink PRS pattern 1200 in accordance with an aspect of the disclosure. The sidelink PRS pattern 1200 is similar to the sidelink PRS pattern 1100 of Figure 11, except that the sidelink PRS pattern 1200 labels PRS transmission opportunities in the format [transmitter]_PRSTxopportunity number, where i denotes the initiator UE, r_1 denotes UE1, r_2 denotes UE2, and r_3 denotes UE3.

[0144] Referring to FIG. 12, four UEs (e.g., one UE type RSU and three vehicle UEs) form a positioning group. The RSU shows a PRS transmission opportunity pattern starting from t1 (the RSU is the initiator). The initiator performs type 1 channel access for its PRS transmission. Assuming that the initiator fails to access the channel for PRS transmission in its first PRS opportunity (i_1) in the opportunity pattern, but succeeds in accessing the channel for PRS transmission in its second PRS opportunity (i_2), the initiator transmits a PRS in its second PRS opportunity (i_2). The responder UE1 detects the initiator PRS in the initiator's first PRS opportunity (i_1). In this case, responder UE1 does not detect the PRS (the initiator does not transmit due to LBT), and therefore responder UE1 does not transmit the PRS at its first PRS opportunity (r_1,1).

[0145] Responder UE2 detects the initiator PRS in the initiator's second PRS opportunity (i_2). Responder UE2 detects the initiator PRS in that opportunity. Therefore, responder UE2 transmits its PRS in its first PRS opportunity (r_2,1). UE2's transmission can follow type 2 channel access (CAT1 or 2 LBT). Initiator UE transmits PRS again in its third PRS opportunity (i_3). This transmission is to keep the channel occupied (transmission can be subject to type 2 channel access). Responder UE3 detects the initiator's PRS in i_3 and may transmit its PRS in r_3,1 if initiator PRS is detected (similar to UE2's behavior and hence COT). Initiator UE stops PRS transmission once all responder UEs have transmitted PRS. In this example, PRS opportunities i_5 and thereafter are not used by the group of UEs.

[0146] 9-10 , in some designs, the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, where each of the N PRS transmission opportunities is paired with one corresponding PRS transmission opportunity associated with each UE of the at least one other UE. An example of this aspect is shown in FIG. 13 .

[0147] FIG 13 illustrates a sidelink PRS pattern 1300 according to an aspect of the disclosure. In FIG 13, the UE group includes X UEs (in this case, X=4 UEs including UEs 1-4), and the sidelink PRS pattern includes a total of 12 PRS transmission opportunities, with three PRS transmission opportunities (N=3) allocated to each of UEs 1-4. The sidelink PRS pattern 1300 labels the PRS transmission opportunities in the format [UE number]_PRSTxopportunity number.

[0148] 13, in some designs, sidelink PRS pattern 1300 may be implemented similarly to sidelink PRS patterns 1100-1200 of FIGS. 11-12, where UE1 is designated as an initiator UE (e.g., during group formation). In this case, a PRS transmission by UE1 will start a COT, and responder UEs 2-4 may detect the initiator PRS at the initiator PRS opportunity and perform CAT1 or CAT2 LBT towards transmitting a PRS at their own respective PRS transmission opportunity if the initiator PRS is detected.

[0149] Referring to FIG. 13, in another design, any UE in a UE group may opportunistically assume the role of an initiator UE (e.g., if there is no active COT, any UE may initiate a COT). For example, each UE performs channel access / LBT (e.g., CAT4) for PRS transmission for its own PRS opportunity, and each UE may also detect PRS transmitted by other UEs in other UEs' PRS opportunities. If the UE succeeds in channel access (e.g., Type 1 CA / CAT4 LBT), the UE transmits the PRS in its own PRS opportunity. If the UE detects a PRS in a PRS opportunity prior to its own PRS opportunity, the UE may determine that a COT for SL PRS transmission has been initiated. The UE may transmit a SL PRS in its own PRS opportunity after successfully performing Type 2c (CAT1 LBT) or Type 2a / 2b channel access (CAT2 LBT). For the sidelink PRS pattern 1300, the PRS transmission opportunities for each UE occur periodically and all UEs have an equal number (>1) of PRS opportunities. In one example (X UEs form a positioning group), there are M PRS transmission opportunities for each UE in the PRS opportunity pattern, thus M×X PRS transmission opportunities in total (i.e., M=3 and X=4, resulting in 3×4=12 PRS opportunities in the sidelink PRS pattern 1300).

[0150] Referring to FIG. 13, in one example, assume that four UEs form a positioning group. One of the UEs (e.g., UE1) shows a PRS transmission opportunity pattern starting from t1. UE1 performs channel access (e.g., Type 1 / CAT4 LBT) for transmitting PRS in the first PRS opportunity (1_1). In this case, assume that UE1 fails channel access (cannot pass LBT for SL PRS transmission in the first PRS opportunity). UE2 detects UE1's PRS in UE1's first PRS opportunity (1_1) and does not detect PRS (UE1 did not transmit). Subsequently or in parallel, UE2 may perform channel access (e.g., Type 1 / CAT 4 LBT) for transmitting PRS in the second PRS opportunity (2_1). Furthermore, assume that UE3 is the first successful channel access in the group of UEs in PRS opportunity 3_2. UE3 transmits SL PRS at PRS transmission opportunity 3_2 (this transmission also starts COT for sharing). UE4 may detect the PRS (successfully) and transmit its PRS at PRS opportunity 4_2, where UE4 may transmit its PRS after performing type 2a / 2b / 2c channel access (CAT1 or 2 LBT). Similarly, UE1 and UE2 transmit their PRS at PRS opportunities 1_3 and 2_3, respectively, following UE4's PRS transmission at 4_2. PRS transmission stops after all UEs in the group have transmitted their PRS.

[0151] 9-10, in some designs, each PRS transmission opportunity may have one or more OFDM symbols. For example, a PRS transmission opportunity may have six OFDM symbols. In some designs, for a scenario in which a UE is designated as an initiator UE (during group formation), the PRS opportunity for the initiator UE may differ (e.g., may be longer) from the PRS opportunity duration for the responder UE. For example, the PRS opportunity for the initiator UE may have six OFDM symbols (a larger number of OFDM symbols may facilitate PRS detection by the responder UE), while the duration of the PRS opportunity for the responder UE may be shorter (e.g., two OFDM symbols). This distinction regarding PRS transmission opportunity duration may be realized for any of the scenarios described above with respect to FIGS. 11-13.

[0152] 9-10 , in some designs, the duration(s) of the PRS transmission opportunity may be (pre)configured. Alternatively, the duration(s) of the PRS transmission opportunity may be determined during UE group formation and indicated to the UEs (e.g., by the initiator UE). In some designs, the duration(s) of the PRS transmission opportunity may be in the smallest unit, such as an OFDM symbol or slot. In some designs, for each UE's SL PRS transmission opportunity, the UE may transmit the PRS (only the PRS) in one or more OFDM symbols. Alternatively, the UE may transmit the PRS and other signal(s) (e.g., a control signal associated with the SL PRS) in its respective PRS transmission opportunity.

[0153] 9-10, in some designs, SL PRS transmissions may still be subject to LBT, but PRS transmissions are more deterministic because the UE knows when it should (or expects to) transmit / receive an SL PRS from another UE. As a result, for a UE transmitting an SL PRS, the candidate time resource locations for that SL PRS transmission are known a priori, and thus the UE has a faster turnaround and can better prepare for a PRS transmission (e.g., generate a PRS waveform, etc.). Also, for a UE monitoring SL PRS from other UEs, the candidate time resource locations for those PRS are also known, and thus blind detection is limited to a subset of time resources, which facilitates PRS detection for the UE and reduces power consumption. Some of the above-described aspects facilitate a COT sharing framework, which reduces uncertainty regarding PRS transmissions in unlicensed spectrum.

[0154] 9-10, in some designs (e.g., for any of the sidelink PRS patterns of FIGS. 11-13), in response to a successful attempt to transmit the first PRS in the first PRS transmission opportunity, the first UE may monitor at least a second PRS transmission opportunity for receiving a second PRS from the second UE in accordance with the sidelink PRS pattern. For example, the monitoring of the second PRS may be performed for an RTT measurement, where the RTT is measured based on a combination of the first PRS and the second PRS. In some designs, if the second PRS is not received in the second PRS transmission opportunity, one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern may be performed by the first UE. In some designs, the first UE's attempt to transmit the third SL PRS may be based either on Type 2 channel access (e.g., if the transmission is considered part of a first UE initiated COT) or on Type 1 channel access (e.g., if the transmission is considered starting a new COT). In one aspect, assume that the second PRS is received from the second UE in a second PRS transmission opportunity. In one example, the second PRS is transmitted according to a contention-based protocol, such as Type 2 channel access (e.g., CAT 1 / 2 LBT). As noted above, the duration of the first PRS transmission opportunity may be different (e.g., longer) than the duration of the second PRS transmission opportunity, especially for scenarios in which the first UE corresponds to a pre-configured initiator UE (e.g., rather than an opportunistic initiator UE for scenarios in which any UE may initiate a COT).

[0155] 9-10 , in some designs as described above (e.g., with respect to any of the sidelink PRS patterns in FIGS. 11-13 ), a time location associated with the sidelink PRS pattern may be determined and shared among the group of UEs during formation of the group of UEs, or the time location may include a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern may include an allocation of a sidelink PRS transmission opportunity to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern may be configured during formation of the group of UEs, or any combination thereof.

[0156] 9-10, in some designs such as those described above, one or more attempts to transmit the first PRS by the first UE are performed according to a contention-based protocol (e.g., type 1 channel access). As described above, in the case of a "pre-configured" initiator UE, the first UE may be the initiator UE, and a channel occupation time (COT) for the sidelink position estimation procedure is started after a successful attempt to transmit the first PRS in the first PRS transmission opportunity, whereby an unsuccessful attempt to transmit the PRS by the second or subsequent UE cancels the COT. In other designs, when an "opportunistic" initiator UE is supported, if a channel occupation time (COT) for the sidelink position estimation procedure is not active, any UE in the group of UEs acts as an initiator UE upon successful transmission of the respective PRS from the respective UE.

[0157] 9-10, in some designs described above (e.g., with respect to any of the sidelink PRS patterns of FIG. 11-13), the second UE (e.g., a responder UE) may selectively attempt to transmit a second PRS in a second PRS transmission opportunity associated with the second UE according to the sidelink PRS pattern based on whether the first PRS was received from the first UE in the first PRS opportunity. In some designs, the second PRS may be transmitted by the second UE in the second PRS transmission opportunity according to a contention-based protocol (e.g., type 2 channel access). In some designs as described above, the second PRS transmission opportunity may be different (e.g., shorter) than the first PRS transmission opportunity (e.g., if the first UE corresponds to a preconfigured initiator UE).

[0158] In the above detailed description, it can be seen that various features are grouped together in each example. This manner of disclosure should not be understood as an intention that the exemplary clauses have more features than are expressly stated in each clause. Rather, various aspects of the disclosure may include fewer than all features of each disclosed exemplary clause. Thus, the following clauses should be considered to be incorporated in the description, and each clause may stand alone as a separate example. Although each dependent clause may refer to a specific combination with one of the other clauses in the clause, the aspect(s) of the dependent clause are not limited to that specific combination. It will be understood that other exemplary clauses may also include combinations of the aspect(s) of the dependent clause with the subject matter of any other dependent clause or independent clause, or combinations of any features with other dependent clauses and independent clauses. Unless a specific combination is not intended (e.g., conflicting aspects such as defining an element as both an insulator and a conductor) is expressly expressed or can be easily inferred, the various aspects disclosed herein expressly include these combinations. It is further contemplated that aspects of a clause may be included in any other independent clause, even if the clause is not directly dependent on the independent clause.

[0159] The following numbered clauses describe implementation examples. Clause 1. A method of operating a first user equipment (UE), the method comprising: determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and performing one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0160] Clause 2. The method of clause 1, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0161] Clause 3. The method of any of clauses 1-2, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each UE of the at least one other UE.

[0162] Clause 4. The method of any one of clauses 1 to 3, further comprising: in response to a successful attempt to transmit the first PRS in the first PRS transmission opportunity, monitoring at least a second PRS transmission opportunity for whether a second PRS has been received from the second UE in accordance with a sidelink PRS pattern; if the second PRS is not received in the second PRS transmission opportunity, performing one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern; and in response to a successful attempt to transmit the third PRS in the third PRS transmission opportunity, monitoring at least a fourth PRS transmission opportunity for whether a fourth PRS has been received from the second UE in accordance with the sidelink PRS pattern.

[0163] Clause 5. The method of clause 4, wherein the second PRS is received from a second UE at a second PRS transmission opportunity.

[0164] Clause 6. The method of clause 5, wherein the second PRS is transmitted according to a contention-based protocol.

[0165] Clause 7. The method of clause 6, wherein the contention-based protocol corresponds to Type 2 channel access.

[0166] Clause 8. The method of any of clauses 4 to 7, wherein the duration of the first PRS transmission opportunity is different from the duration of the second PRS transmission opportunity.

[0167] Clause 9. The method of any of clauses 1 to 8, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location comprises a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern comprises an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0168] Clause 10. The method of any of clauses 1 to 9, wherein the one or more attempts to transmit the first PRS are performed according to a contention-based protocol.

[0169] Clause 11. The method of clause 10, wherein the contention-based protocol corresponds to Type 1 channel access.

[0170] Clause 12. The method of any of clauses 1 to 11, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0171] Clause 13. The method of clause 12, wherein the COT is cancelled if an attempt by the second UE or a subsequent UE to transmit the PRS is unsuccessful.

[0172] Clause 14. The method according to any of clauses 1 to 13, wherein, if the Channel Occupancy Time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0173] Clause 15. The method of any of clauses 1-14, wherein each PRS transmission opportunity of the sidelink PRS pattern comprises one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0174] Clause 16. The method of any one of clauses 1 to 15, wherein only the first PRS is transmitted by the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are transmitted by the first UE at the first PRS transmission opportunity.

[0175] Clause 17. The method of clause 16, wherein the one or more other signals include a control signal associated with the first PRS.

[0176] Clause 18. A method of operating a second user equipment (UE), the method comprising: determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and monitoring the first PRS transmission opportunity for receiving a first PRS from a first UE in accordance with the sidelink PRS pattern.

[0177] Clause 19. The method of clause 18, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0178] Clause 20. The method of any of clauses 18-19, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each UE of the at least one other UE.

[0179] Clause 21. The method of any of clauses 18-20, further comprising selectively attempting to transmit a second PRS in a second PRS transmission opportunity associated with a second UE according to a sidelink PRS pattern based on whether the first PRS is received from the first UE in the first PRS opportunity.

[0180] Clause 22. The method of clause 21, wherein the second PRS is transmitted by the second UE at a second PRS transmission opportunity.

[0181] Clause 23. The method of clause 22, wherein the second PRS is transmitted according to a contention-based protocol.

[0182] Clause 24. The method of clause 23, wherein the contention-based protocol corresponds to type 2 channel access.

[0183] Clause 25. The method of any of clauses 21-24, wherein the duration of the first PRS transmission opportunity is different from the duration of the second PRS transmission opportunity.

[0184] Clause 26. The method of any of clauses 18 to 25, wherein a time location associated with a sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location comprises a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern comprises an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0185] Clause 27. The method of any of clauses 18 to 26, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0186] Clause 28. The method according to any of clauses 18 to 27, wherein, if the Channel Occupancy Time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0187] Clause 29. The method of any of clauses 18-28, wherein each PRS transmission opportunity of the sidelink PRS pattern comprises one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0188] Clause 30. The method of any one of clauses 18 to 29, wherein only the first PRS is received from the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are received from the first UE at the first PRS transmission opportunity.

[0189] Clause 31. A first user equipment (UE) comprising a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and perform one or more attempts to transmit a first PRS in the one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0190] Clause 32. The first UE of Clause 31, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0191] Clause 33. A first UE as described in any of Clauses 31 to 32, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each UE of the at least one other UE.

[0192] Clause 34. The first UE of any of clauses 31 to 33, wherein the at least one processor is further configured to: in response to a successful attempt to transmit the first PRS in the first PRS transmission opportunity, monitor at least a second PRS transmission opportunity for whether a second PRS has been received from the second UE in accordance with a sidelink PRS pattern; if the second PRS is not received in the second PRS transmission opportunity, perform one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern; and in response to a successful attempt to transmit the third PRS in the third PRS transmission opportunity, monitor at least a fourth PRS transmission opportunity for whether a fourth PRS has been received from the second UE in accordance with the sidelink PRS pattern.

[0193] Clause 35. The first UE of clause 34, wherein the second PRS is received from the second UE at a second PRS transmission opportunity.

[0194] Clause 36. The first UE of clause 35, wherein the second PRS is transmitted according to a contention-based protocol.

[0195] Clause 37. The first UE according to clause 36, wherein the contention-based protocol corresponds to type 2 channel access.

[0196] Clause 38. The first UE of any of clauses 34-37, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0197] Clause 39. The first UE of any of clauses 31 to 38, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0198] Clause 40. The first UE of any of clauses 31 to 39, wherein the one or more attempts to transmit the first PRS are performed according to a contention-based protocol.

[0199] Clause 41. The first UE of clause 40, wherein the contention-based protocol corresponds to type 1 channel access.

[0200] Clause 42. A first UE as described in any of clauses 31 to 41, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0201] Clause 43. The first UE as claimed in clause 42, wherein the COT is cancelled if an attempt by the second UE or a subsequent UE to transmit the PRS is unsuccessful.

[0202] Clause 44. The first UE according to any of clauses 31 to 43, wherein if a channel occupation time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0203] Clause 45. The first UE of any of clauses 31-44, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0204] Clause 46. A first UE as described in any of clauses 31 to 45, wherein only the first PRS is transmitted by the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are transmitted by the first UE at the first PRS transmission opportunity.

[0205] Clause 47. The first UE of clause 46, wherein the one or more other signals include a control signal associated with the first PRS.

[0206] Clause 48. A second user equipment (UE) comprising a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and monitor the first PRS transmission opportunity for receiving a first PRS from the first UE in accordance with the sidelink PRS pattern.

[0207] Clause 49. The group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE, the second UE as described in Clause 48.

[0208] Clause 50. The group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each of the at least one other UE, the second UE described in any of Clauses 48 to 49.

[0209] Clause 51. A second UE as described in any of clauses 48 to 50, wherein the at least one processor is further configured to selectively attempt to transmit a second PRS at a second PRS transmission opportunity associated with the second UE according to a sidelink PRS pattern based on whether the first PRS is received from the first UE at the first PRS opportunity.

[0210] Clause 52. The second UE of clause 51, wherein the second PRS is transmitted by the second UE at a second PRS transmission opportunity.

[0211] Clause 53. The second UE of clause 52, wherein the second PRS is transmitted according to a contention-based protocol.

[0212] Clause 54. The second UE according to clause 53, wherein the contention-based protocol corresponds to type 2 channel access.

[0213] Clause 55. The second UE of any of clauses 51-54, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0214] Clause 56. A second UE according to any of clauses 48 to 55, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0215] Clause 57. A second UE according to any of clauses 48 to 56, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0216] Clause 58. A second UE according to any of clauses 48 to 57, wherein, if a channel occupation time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0217] Clause 59. The second UE of any of clauses 48 to 58, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0218] Clause 60. A second UE according to any of clauses 48 to 59, wherein only the first PRS is received from the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are received from the first UE at the first PRS transmission opportunity.

[0219] Clause 61. A first user equipment (UE) including: means for determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and means for performing one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0220] Clause 62. The first UE of Clause 61, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0221] Clause 63. A first UE as described in any of Clauses 61 to 62, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each UE of the at least one other UE.

[0222] Clause 64. The first UE of any of clauses 61 to 63, further comprising: means for monitoring at least a second PRS transmission opportunity for whether a second PRS has been received from the second UE in accordance with a sidelink PRS pattern in response to a successful attempt to transmit the first PRS in the first PRS transmission opportunity; means for performing one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern if the second PRS is not received in the second PRS transmission opportunity; and means for monitoring at least a fourth PRS transmission opportunity for whether a fourth PRS has been received from the second UE in accordance with the sidelink PRS pattern in response to a successful attempt to transmit the third PRS in the third PRS transmission opportunity.

[0223] Clause 65. The first UE of clause 64, wherein the second PRS is received from the second UE at a second PRS transmission opportunity.

[0224] Clause 66. The first UE of clause 65, wherein the second PRS is transmitted according to a contention-based protocol.

[0225] Clause 67. The first UE of clause 66, wherein the contention-based protocol corresponds to type 2 channel access.

[0226] Clause 68. The first UE of any of clauses 64-67, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0227] Clause 69. A first UE according to any of clauses 61 to 68, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0228] Clause 70. The first UE of any of clauses 61 to 69, wherein the one or more attempts to transmit the first PRS are performed according to a contention-based protocol.

[0229] Clause 71. The first UE of clause 70, wherein the contention-based protocol corresponds to type 1 channel access.

[0230] Clause 72. A first UE as described in any of clauses 61 to 71, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0231] Clause 73. The first UE as claimed in clause 72, wherein the COT is cancelled if an attempt by the second UE or a subsequent UE to transmit the PRS is unsuccessful.

[0232] Clause 74. The first UE according to any of clauses 61 to 73, wherein, if a channel occupation time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0233] Clause 75. The first UE of any of clauses 61-74, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0234] Clause 76. A first UE as described in any of clauses 61 to 75, wherein only the first PRS is transmitted by the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are transmitted by the first UE at the first PRS transmission opportunity.

[0235] Clause 77. The first UE of clause 76, wherein the one or more other signals include a control signal associated with the first PRS.

[0236] Clause 78. A second user equipment (UE) comprising: means for determining a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium; and means for monitoring a first PRS transmission opportunity for receiving a first PRS from a first UE in accordance with the sidelink PRS pattern.

[0237] Clause 79. The group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE, the second UE as described in Clause 78.

[0238] Clause 80. The group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each of the at least one other UE, the second UE described in any of Clauses 78 to 79.

[0239] Clause 81. The second UE of any of clauses 78 to 80, further comprising means for selectively attempting to transmit a second PRS at a second PRS transmission opportunity associated with the second UE in accordance with a sidelink PRS pattern based on whether the first PRS was received from the first UE at the first PRS opportunity.

[0240] Clause 82. The second UE of clause 81, wherein the second PRS is transmitted by the second UE at a second PRS transmission opportunity.

[0241] Clause 83. The second UE of clause 82, wherein the second PRS is transmitted according to a contention-based protocol.

[0242] Clause 84. The second UE according to clause 83, wherein the contention-based protocol corresponds to type 2 channel access.

[0243] Clause 85. The second UE of any of clauses 81-84, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0244] Clause 86. The second UE of any of clauses 78 to 85, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is configured during formation of the group of UEs, or any combination thereof.

[0245] Clause 87. A second UE according to any of clauses 78 to 86, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure starts after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0246] Clause 88. The second UE according to any of clauses 78 to 87, wherein, if the channel occupation time (COT) for the sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0247] Clause 89. The second UE of any of clauses 78-88, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0248] Clause 90. A second UE according to any of clauses 78 to 89, wherein only the first PRS is received from the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are received from the first UE at the first PRS transmission opportunity.

[0249] Clause 91. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a first user equipment (UE), cause the first UE to determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and to perform one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern.

[0250] Clause 92. The non-transitory computer-readable medium of clause 91, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0251] Clause 93. A non-transitory computer-readable medium according to any of clauses 91-92, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each of the at least one other UE.

[0252] Clause 94. The non-transitory computer-readable medium according to any of Clauses 91 to 93, wherein the computer-readable medium further includes computer-executable instructions which, when executed by the first UE, cause the first UE to monitor at least a second PRS transmission opportunity for whether a second PRS has been received from the second UE in accordance with a sidelink PRS pattern in response to the attempt to transmit the first PRS in the first PRS transmission opportunity being successful, and if the second PRS is not received in the second PRS transmission opportunity, perform one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE in accordance with the sidelink PRS pattern, and in response to the attempt to transmit the third PRS in the third PRS transmission opportunity being successful, monitor at least a fourth PRS transmission opportunity for whether a fourth PRS has been received from the second UE in accordance with the sidelink PRS pattern.

[0253] Clause 95. The non-transitory computer-readable medium of clause 94, wherein the second PRS is received from the second UE at a second PRS transmission opportunity.

[0254] Clause 96. The non-transitory computer-readable medium of clause 95, wherein the second PRS is transmitted according to a contention-based protocol.

[0255] Clause 97. The non-transitory computer-readable medium of clause 96, wherein the contention-based protocol supports Type 2 channel access.

[0256] Clause 98. The non-transitory computer-readable medium of any of clauses 94-97, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0257] Clause 99. The non-transitory computer-readable medium of any of clauses 91-98, wherein a time location associated with a sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is set during formation of the group of UEs, or any combination thereof.

[0258] Clause 100. The non-transitory computer-readable medium of any of clauses 91-99, wherein the one or more attempts to transmit the first PRS are performed according to a contention-based protocol.

[0259] Clause 101. The non-transitory computer-readable medium of clause 100, wherein the contention-based protocol corresponds to Type 1 channel access.

[0260] Clause 102. The non-transitory computer-readable medium of any of clauses 91-101, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure begins after a successful attempt to transmit the first PRS in the first PRS transmission opportunity.

[0261] Clause 103. The non-transitory computer-readable medium of clause 102, wherein the COT is cancelled if an attempt by the second UE or a subsequent UE to transmit the PRS is unsuccessful.

[0262] Clause 104. The non-transitory computer-readable medium of any of clauses 91 to 103, wherein, if a channel occupation time (COT) for a sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0263] Clause 105. The non-transitory computer-readable medium of any of clauses 91-104, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0264] Clause 106. A non-transitory computer-readable medium according to any of clauses 91 to 105, wherein only the first PRS is transmitted by the first UE in the first PRS transmission opportunity, or the first PRS and one or more other signals are transmitted by the first UE in the first PRS transmission opportunity.

[0265] Clause 107. The non-transitory computer-readable medium of clause 106, wherein the one or more other signals include a control signal associated with the first PRS.

[0266] Clause 108. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a second user equipment (UE), cause the second UE to determine a sidelink positioning reference signal (PRS) pattern for a sidelink position estimation procedure, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communications medium, and to monitor the first PRS transmission opportunity for receiving a first PRS from the first UE in accordance with the sidelink PRS pattern.

[0267] Clause 109. The non-transitory computer-readable medium of clause 108, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities that are split among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding PRS transmission opportunity of one of the N PRS transmission opportunities that are split among the at least one other UE.

[0268] Clause 110. A non-transitory computer-readable medium according to any of clauses 108 to 109, wherein the group of UEs comprises a first UE and at least one other UE including a second UE, and the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, each of the N PRS transmission opportunities being paired with one corresponding PRS transmission opportunity associated with each of the at least one other UE.

[0269] Clause 111. A non-transitory computer-readable medium according to any of clauses 108-110, further comprising computer-executable instructions that, when executed by a second UE, cause the second UE to selectively attempt to transmit a second PRS at a second PRS transmission opportunity associated with the second UE according to a sidelink PRS pattern based on whether the first PRS was received from the first UE at the first PRS opportunity.

[0270] Clause 112. The non-transitory computer-readable medium of clause 111, wherein the second PRS is transmitted by the second UE at a second PRS transmission opportunity.

[0271] Clause 113. The non-transitory computer-readable medium of clause 112, wherein the second PRS is transmitted according to a contention-based protocol.

[0272] Clause 114. The non-transitory computer-readable medium of clause 113, wherein the contention-based protocol supports Type 2 channel access.

[0273] Clause 115. The non-transitory computer-readable medium of any of clauses 111-114, wherein a duration of the first PRS transmission opportunity is different from a duration of the second PRS transmission opportunity.

[0274] Clause 116. The non-transitory computer-readable medium of any of clauses 108 to 115, wherein a time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during formation of the group of UEs, or the time location includes a start time and duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is set during formation of the group of UEs, or any combination thereof.

[0275] Clause 117. The non-transitory computer-readable medium of any of clauses 108 to 116, wherein the first UE is an initiator UE and a channel occupation time (COT) for the sidelink position estimation procedure begins after a successful attempt to transmit the first PRS at the first PRS transmission opportunity.

[0276] Clause 118. The non-transitory computer-readable medium of any of clauses 108 to 117, wherein, if a channel occupation time (COT) for a sidelink position estimation procedure is not active, upon successful transmission of the respective PRS from the respective UE, any UE in the group of UEs acts as an initiator UE.

[0277] Clause 119. The non-transitory computer-readable medium of any of clauses 108-118, wherein each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols.

[0278] Clause 120. A non-transitory computer-readable medium according to any of clauses 108 to 119, wherein only the first PRS is received from the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are received from the first UE at the first PRS transmission opportunity.

[0279] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0280] Moreover, those skilled in the art will appreciate that the various exemplary logic blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, various exemplary components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0281] The various example logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using a general purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0282] The methods, sequences, and / or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a random access memory (RAM), a flash memory, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

[0283] In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium 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. Also, any connection is properly termed a computer-readable medium. For example, if the 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, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of media. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0284] Although the above disclosure illustrates exemplary aspects of the disclosure, it should be noted that various changes and modifications may 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 according to the aspects of the disclosure described herein do not have to be performed in any particular order. Further, although elements of the disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims

1. A method of operating a first user equipment (UE), comprising: determining a sidelink positioning reference signal (PRS) pattern for sidelink position estimation procedures, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium; performing one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE according to the sidelink PRS pattern.

2. The group of UEs includes the first UE and at least one other UE including a second UE, the sidelink PRS pattern includes N PRS transmission opportunities associated with the first UE, the sidelink PRS pattern includes N PRS transmission opportunities divided among the at least one other UE, and each of the N PRS transmission opportunities associated with the first UE is paired with a corresponding one of the N PRS transmission opportunities divided among the at least one other UE, or each of the N PRS transmission opportunities is paired with a corresponding one of the PRS transmission opportunities associated with each of the at least one other UE. The method according to claim 1.

3. Monitoring at least a second PRS transmission opportunity as to whether a second PRS is received from a second UE according to the sidelink PRS pattern in response to a successful attempt to transmit the first PRS in a first PRS transmission opportunity among the one or more PRS transmission opportunities; performing one or more attempts to transmit a third PRS in one or more additional PRS transmission opportunities associated with the first UE according to the sidelink PRS pattern when the second PRS is not received in the second PRS transmission opportunity; monitoring at least a fourth PRS transmission opportunity as to whether a fourth PRS is received from the second UE according to the sidelink PRS pattern in response to a successful attempt to transmit the third PRS in a third PRS transmission opportunity, wherein the second PRS is received from the second UE in the second PRS transmission opportunity, or The second PRS is transmitted according to a contention-based protocol, or the contention-based protocol corresponds to type 2 channel access, or the duration of the first PRS transmission opportunity is different from the duration of the second PRS transmission opportunity, or The method according to claim 1, comprising any combination thereof.

4. A time location associated with the sidelink PRS pattern is determined and shared within the group of UEs during the formation of the group of UEs, or the time location includes a start time and a duration of the sidelink PRS pattern, or the sidelink PRS pattern includes an allocation of sidelink PRS transmission opportunities to the group of UEs, or the duration of each PRS transmission opportunity of the sidelink PRS pattern is set during the formation of the group of UEs, or The method according to claim 1, comprising any combination thereof.

5. The one or more attempts to transmit the first PRS are performed according to a contention-based protocol, or the contention-based protocol corresponds to type 1 channel access, or The method according to claim 1, comprising these combinations.

6. The first UE is an initiator UE, and a channel occupancy time (COT) for the sidelink position estimation procedure is started after an attempt to transmit the first PRS at the first PRS transmission opportunity is successful, or if an attempt to transmit a PRS by a second UE or a subsequent UE is unsuccessful, the COT is cancelled, or The method according to claim 1, comprising any combination thereof.

7. When the channel occupancy time (COT) for the sidelink position estimation procedure is not active, any UE within the group of UEs operates as an initiator UE when the transmission of each PRS from the initiator UE is successful, or each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols, or only the first PRS is transmitted by the first UE at the first PRS transmission opportunity, or the first PRS and one or more other signals are transmitted by the first UE at the first PRS transmission opportunity, or The one or more other signals include a control signal associated with the first PRS, or The method according to claim 1, including any combination thereof.

8. A method of operating a second user equipment (UE), comprising: Determining a sidelink positioning reference signal (PRS) pattern for sidelink position estimation procedures, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium; Monitoring a first PRS transmission opportunity for whether the first PRS has been received from the first UE according to the sidelink PRS pattern.

9. Further comprising selectively attempting to transmit a second PRS in a second PRS transmission opportunity associated with the second UE according to the sidelink PRS pattern, based on whether the first PRS has been received from the first UE in the first PRS opportunity, The second PRS is transmitted by the second UE in the second PRS transmission opportunity, or The second PRS is transmitted according to a contention-based protocol, or The duration of the first PRS transmission opportunity is different from the duration of the second PRS transmission opportunity, or Including any combination thereof, or The contention-based protocol corresponds to type 2 channel access. The method according to claim 8.

10. The first UE is an initiator UE, and the channel occupancy time (COT) for the sidelink position estimation procedure starts after an attempt to transmit the first PRS in the first PRS transmission opportunity is successful. The method according to claim 8.

11. When the channel occupancy time (COT) for the sidelink position estimation procedure is not active, any UE within the group of UEs operates as an initiator UE when the transmission of each PRS from the initiator UE is successful, or Each PRS transmission opportunity of the sidelink PRS pattern includes one or more orthogonal frequency division multiplexing (OFDM) symbols, or Only the first PRS is received from the first UE in the first PRS transmission opportunity, or The first PRS and one or more other signals are received from the first UE in the first PRS transmission opportunity, or Any combination thereof The method according to claim 8

12. A first user equipment (UE), comprising A memory, At least one transceiver, At least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor Determines a sidelink positioning reference signal (PRS) pattern for sidelink position estimation procedures, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium A first UE configured to perform one or more attempts to transmit a first PRS in one or more PRS transmission opportunities associated with the first UE according to the sidelink PRS pattern

13. The first UE according to claim 12, further configured to perform the method according to any one of claims 2 to 7

14. A second user equipment (UE), comprising A memory, At least one transceiver, At least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor Determines a sidelink positioning reference signal (PRS) pattern for sidelink position estimation procedures, the sidelink PRS pattern including at least one PRS transmission opportunity for each of a group of UEs in a shared communication medium A second UE configured to monitor a first PRS transmission opportunity regarding whether a first PRS has been received from the first UE according to the sidelink PRS pattern

15. The second UE according to claim 14, further configured to perform the method according to any one of claims 9 to 11

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