Timing determination for signals in sidelink positioning

Abstract

A ranging session between multiple user equipments (UEs) is initiated using an initial message that includes an identifier (ID) of each of an initiating UE and one or more responding UEs. Each UE in the ranging session independently determines a signaling timing instance for each UE in the ranging session based on the UE ID in the initial message. Signaling information, such as an identifier of a ranging signal, may also be independently determined by each UE based on the UE ID. The order of the UE IDs and the number of responding UEs provided in the initial message may also be used to determine the signaling timing instance and the signaling information. The UE may, for example, use a general multivariate deterministic function together with the UE ID as an input to derive the timing instance for itself and the other UEs in the ranging session separately.

Description

[Technical Field]

[0001] Priority claims This application claims priority to U.S. Non-Provisional Application No. 17 / 160,135, filed January 27, 2021, entitled "TIMING DETERMINATION FOR SIGNALS IN SIDELINK POSITIONING," which is incorporated herein by reference in its entirety.

[0002] The subject matter disclosed herein relates to wireless communication systems, and more particularly, to methods and apparatus for user equipment distance determination in a distributed wireless communication system. [Background technology]

[0003] Obtaining precise location information for user equipment, such as mobile phones or other wireless communication devices, is becoming commonplace in the communications industry. For example, obtaining highly accurate positions of vehicles or pedestrians is essential for autonomous vehicle driving and pedestrian safety applications.

[0004] A common means for determining a device's location is to use a satellite positioning system (SPS), such as the well-known Global Positioning Satellite (GPS) system or the Global Navigation Satellite System (GNSS), which utilizes several satellites in Earth orbit. However, in some scenarios, for example, in poor weather conditions or in areas with poor satellite signal reception, such as tunnels or parking complexes, the positioning signal from the SPS may be unreliable or unavailable. Furthermore, location information generated using an SPS is prone to inaccuracies. For example, off-the-shelf GPS positioning devices have an accuracy of a few meters, which is not optimal for ensuring safe autonomous driving and navigation.

[0005] Cooperative or autonomous driving requires communication between vehicles, which can be direct or indirect via infrastructure components such as roadside units (RSUs). In vehicle safety applications, both positioning and ranging are important. For example, a vehicle user equipment (UE) may perform positioning and ranging using sidelink signaling, e.g., broadcasting ranging signals to other vehicle UEs or pedestrian UEs to determine the relative location of the transmitter. Accurate and timely knowledge of the relative location or distance to nearby vehicles enables autonomous vehicles to safely navigate and navigate traffic situations. Round trip time (RTT) is a commonly used technique, for example, to determine the distance between transmitters. RTT is a two-way messaging technique in which the time between transmitting a signal from a first device and receiving an acknowledgment from a second device (minus processing delays) corresponds to the distance (range) between the two devices. Summary of the Invention [Problem to be solved by the invention]

[0006] During a ranging session, multiple messages are exchanged between the participating UEs. For example, the timing of various messages should be controlled to avoid interference. When multiple nearby UEs are involved in a ranging session, the message overhead of controlling the timing for message exchanges may become excessively large. [Means for solving the problem]

[0007] A ranging session between multiple user equipments (UEs) is initiated using an initial message including the identifiers (IDs) of an initiating UE and one or more responding UEs. Each UE in the ranging session independently determines a signaling timing instance for each UE in the ranging session based on the UE ID in the initial message. Signaling information, such as a ranging signal identifier, may also be independently determined by each UE based on the UE ID. The order of the UE IDs and the number of responding UEs provided in the initial message may also be used to determine the signaling timing instance and the signaling information. A UE may separately derive timing instances for itself and other UEs in the ranging session, for example, using a general multivariate deterministic function together with the UE ID as input.

[0008] In one implementation, a method for measuring distance between UEs performed by an initiating user equipment (UE) includes the steps of: sending an initial message to one or more responding UEs to initiate a ranging session, wherein the initial message comprises an identifier (ID) of the initiating UE and the ID of each of the one or more responding UEs; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs; and performing the ranging session with each of the one or more responding UEs using the determined timing instances for messages in the ranging session.

[0009] In one implementation, user equipment (UE) are configured to perform a ranging session between UEs, the UE being an initiating UE in the ranging session, the UE including a wireless transceiver configured to wirelessly communicate with an entity in a wireless network, at least one memory, and at least one processor coupled to the wireless transceiver and the at least one memory, the at least one processor being configured to: send an initial message to one or more responding UEs to initiate the ranging session, the initial message comprising an identifier (ID) of the initiating UE and the ID of each of the one or more responding UEs; determine timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs; and perform the ranging session with each of the one or more responding UEs using the determined timing instances for the messages in the ranging session.

[0010] In one implementation, user equipment (UE) is configured to perform ranging between UEs, the UE is an initiating UE in a ranging session, and the UE includes: means for sending an initial message to one or more responding UEs to initiate the ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs; means for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs; and means for performing the ranging session with each of the one or more responding UEs using the determined timing instances for the messages in the ranging session.

[0011] In one implementation, a non-transitory storage medium has program code stored therein, the program code operable to configure at least one processor in a user equipment (UE) to perform ranging between UEs, the UE being an initiating UE in a ranging session, the non-transitory storage medium including: program code for sending an initial message to one or more responding UEs to initiate the ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs; program code for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs; and program code for performing the ranging session with each of the one or more responding UEs using the determined timing instances for the messages in the ranging session.

[0012] In one implementation, a method for measuring distance between user equipments (UEs) performed by a responding UE includes the steps of receiving an initial message from an initiating UE to initiate a ranging session, wherein the initial message comprises an identifier (ID) of the initiating UE and each of the IDs of one or more responding UEs; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the IDs of each of the one or more responding UEs; and performing the ranging session with the initiating UE using the determined timing instances for messages in the ranging session.

[0013] In one implementation, user equipment (UE) are configured to perform a ranging session between the UEs, where the UE is a responding UE in the ranging session, and the UE includes a wireless transceiver configured to communicate wirelessly with an entity in a wireless network, at least one memory, and at least one processor coupled to the wireless transceiver and the at least one memory, where the at least one processor is configured to receive an initial message from an initiating UE to start the ranging session, where the initial message comprises an identifier (ID) of the initiating UE and the IDs of each of one or more responding UEs, determine timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the IDs of each of the one or more responding UEs, and perform the ranging session with the initiating UE using the determined timing instances for the messages in the ranging session.

[0014] In one implementation, user equipment (UE) is configured to perform a ranging session between UEs, where the UE is a responding UE in the ranging session, and the UE includes: means for receiving an initial message from an initiating UE to start the ranging session, where the initial message includes an identifier (ID) of the initiating UE and an ID of each of one or more responding UEs; means for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the IDs of each of the one or more responding UEs; and means for performing the ranging session with the initiating UE using the determined timing instances for the messages in the ranging session.

[0015] In one implementation, a non-transitory storage medium has program code stored therein, the program code operable to configure at least one processor in a user equipment (UE) to perform a ranging session between UEs, the UE being a responding UE in the ranging session, the non-transitory storage medium including: program code for receiving an initial message from an initiating UE to start the ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of one or more responding UEs; program code for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the IDs of each of the one or more responding UEs; and program code for performing the ranging session with the initiating UE using the determined timing instances for the messages in the ranging session.

[0016] Non-limiting and non-exhaustive aspects are described with reference to the following figures, in which like reference numerals refer to like parts throughout the various views unless otherwise specified. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a wireless communication system showing distributed UE communications, including ranging signaling. [Figure 2] FIG. 10 is a signaling graph illustrating the timing and frequency of various messages that may be sent and received by an initiating UE and three responding UEs for a ranging or positioning session. [Figure 3] FIG. 1 illustrates an example of a multivariate deterministic function that may be used. [Figure 4] 1 illustrates an example of a signaling flow for a ranging procedure using a deterministic function to determine timing instances of signaling during a ranging and / or positioning session. [Figure 5]1 is a schematic block diagram illustrating some example features of a user equipment (UE) configured to use a deterministic function to determine timing instances of signaling during a ranging session. [Figure 6] 10 is a flowchart illustrating a method of ranging between UEs performed by an initiating UE in a ranging session. [Figure 7] 10 is a flowchart illustrating a method for measuring distance between UEs performed by a responding UE in a ranging session. DETAILED DESCRIPTION OF THE INVENTION

[0018] A distributed approach may be used for ranging and positioning of vehicles, roadside units (RSUs), and pedestrians, which may eliminate the need for a centralized base station to coordinate and relay communications. Such communications may be used, for example, for autonomous driving and vehicle safety applications. Communications used in the distributed approach may occur, for example, directly between vehicles or between vehicles and RSUs or pedestrians. These communications may include messages and information elements (IEs), which vehicles may use to provide information necessary for autonomous driving.

[0019] For example, for safe operation of an autonomous vehicle, the relative position or distance to other vehicles must be determined. Various techniques may be used to derive relative locations between vehicles. For example, the relative locations of vehicles may be derived using ranging signaling. Ranging signals may be referred to as physical ranging signals, positioning ranging signals, positioning reference signals, or physical reference signals, and may be collectively referred to herein as PRS signals. PRS signals may be broadcast by user equipment (UE) in a vehicle, sometimes referred to as V-UE, and received by other V-UEs and / or infrastructure, e.g., RSUs, or UEs carried by pedestrians, using direct communication systems such as, for example, Dedicated Short-Range Communications (DSRC), cellular Vehicle-to-Everything (C-V2X) communications, and even 5G New Radio (NR) communications. The PRS signals are used to determine the distance to the broadcasting vehicle using, for example, one-way ranging, round trip time (RTT) positioning operations, or other standard positioning operations such as time of arrival (TOA), time difference of arrival (TDOA), or observed time difference of arrival (OTDOA).

[0020] In a distributed system, individual UEs can measure distances relative to other nearby UEs using messages and positioning signals transmitted directly to the other UEs. In an RTT-based ranging session, for example, multiple messages and signals are transmitted and received by each UE. For example, an initial set of pre-ranging signaling messages (pre-PRS messages) is transmitted and received to request and accept a ranging session, followed by broadcast of ranging signals (PRS signals) for measurements, and then a set of post-ranging signaling messages (post-PRS messages) exchanging measurement payloads. In RTT-based ranging and positioning, for example, time-of-arrival (TOA) and time-of-departure (TOD) measurements of the transmitted and received PRS signals are provided in post-PRS messages and can be used by each pair of UEs to determine the distance between them. While pre-PRS and post-PRS messages can be transmitted over licensed spectrum to ensure reliability, PRS signals can be broadcast over unlicensed spectrum (e.g., in the UNI-III spectrum, where wider bandwidth is available).

[0021] A ranging session may involve one initiating UE and one or more responding UEs. To initiate a ranging session without the assistance of a gNB or base station in the wireless network, the initiating UE broadcasts a pre-PRS message that is received by one or more responding UEs. Conventionally, the pre-PRS message broadcast by the initiating PRS includes information necessary for engaging in a ranging session, including identification, signaling, and timing information for various messages. As an example, the pre-PRS message broadcast by the initiating UE conventionally includes identification information such as a Layer 2 (L2) identifier for the initiating UE, sometimes referred to herein as UE ID, and a set of UE IDs of other UEs with which the initiating UE chooses to measure distance. The pre-PRS message further includes signaling information such as the PRS broadcast order for the UE, the PRS bandwidth or channel, the PRS sequence ID (i.e., PRS ID) of the initiating UE, and the PRS IDs of the other UEs. The pre-PRS message further includes timing instructions for various messages including pre-PRS, PRS, and post-PRS for all responding UEs.

[0022] As can be seen, the pre-PRS message may have a relatively large overhead. Moreover, when several responding UEs are involved in a ranging session, the size of the pre-PRS message broadcast by the initiating UE may increase significantly. When multiple ranging or positioning sessions are initiated separately, there is a possibility of contention of the relatively large pre-PRS messages. Therefore, it is desirable to reduce the size of the pre-PRS message transmitted by the initiating UE to initiate the ranging message.

[0023] Thus, in one implementation, as discussed herein, an initiating UE may send an initial pre-PRS message to one or more responding UEs, including the IDs of the initiating UE and the responding UE. Each UE may use the IDs of the initiating UE and the responding UE as inputs to determine timing instances for the remaining messages in the ranging session, e.g., the timing instance of the pre-PRS message for each responding UE, the timing instance of the broadcast of the PRS (estimated if on an unlicensed spectrum), and the timing instance of the post-PRS message. For example, each UE may use a multivariate deterministic function that uses a vector of the IDs of the initiating UE and the responding UE, as well as the order of the IDs, as inputs to determine timing instances for the remaining messages in the ranging session. Each UE uses the multivariate deterministic function and the ID input to uniquely derive timing instances for itself and other UEs. The UE may further use the multivariate deterministic function and the ID input to determine signaling information, such as a PRS sequence ID. Thus, the initial pre-PRS message sent by the initiating UE does not need to include timing instructions, and in some implementations, any signaling information, for the various messages in the ranging session, thereby reducing the size of the pre-PRS message payload.

[0024] FIG. 1 illustrates a wireless communication system 100 illustrating distributed communications, including ranging signaling, using a deterministic function to determine timing instances of messaging during ranging and / or positioning sessions, as described herein. The wireless communication system 100 illustrates a first wireless device, e.g., a first vehicle 102, with a V-UE 102 communicating wirelessly with another V-UE 104, depicted as a second vehicle. The V-UE 102 and V-UE 104 may comprise, but are not limited to, an on-board unit (OBU), a vehicle or its subsystem, or various other communication devices. The V-UEs 102 and 104 function and provide communications on behalf of their associated vehicles and, therefore, may be referred to herein simply as vehicles 102 and 104 or UEs 102 and 104. The first vehicle 102 and second vehicle 104 may be, for example, two vehicles traveling on a road with other vehicles not shown.

[0025] The wireless communication system 100 may use, for example, the Vehicle-to-Everything (V2X) communication standard, which transfers information between vehicles and other entities in the wireless communication network. V2X services include, for example, services for Vehicle-to-Vehicle (V2V), Vehicle-to-Pedestrian (V2P), Vehicle-to-Infrastructure (V2I), and Vehicle-to-Network (V2N). The V2X standard aims to develop autonomous or semi-autonomous driving systems, such as Advanced Driver Assistance Systems (ADAS), which can be used to assist drivers with critical decisions such as lane changes, speed changes, and overtaking speeds, and to assist with parking, as discussed herein. The low-latency communications used in V2X make it suitable for accurate relative positioning using ranging signals, such as one-way ranging, RTT, and TDOA.

[0026] Generally, there are two modes of operation for V2X services as defined in 3rd Generation Partnership Project (3GPP®) TS 23.285. One mode of operation uses direct wireless communication between V2X entities, which may be referred to as sidelink communication. The other mode of operation uses network-based wireless communication between the entities. The two modes of operation may be combined, or other modes of operation may be used if desired.

[0027] The wireless communication system 100 may operate using direct or indirect wireless communication between the vehicle 102 and the vehicle 104. For example, the wireless communication may be via the Proximity-based Services (ProSe) Directional Communication (PC5) reference point, e.g., as defined in 3GPP TS 23.303, using wireless communication over the 5.9 GHz ITS band under IEEE 1609, Wireless Access in Vehicular Environments (WAVE), Intelligent Transport Systems (ITS), and IEEE 802.11p, or using other wireless connections directly between the entities. Thus, as shown, the vehicle 102 and the vehicle 104 may communicate directly using a vehicle-to-vehicle (V2V) communication link 103. The vehicle 102 and the vehicle 104 may also communicate directly with a road-side unit (RSU) 110 via vehicle-to-infrastructure (V2I) communication links 107 and 109, respectively. The RSU 110 may be, for example, a fixed infrastructure entity that may support V2X applications and exchange messages with other entities that support V2X applications. The RSU may be a logical entity that may combine V2X application logic with the functionality of a base station in a RAN, such as an eNB, ng-eNB, or eLTE (referred to as an eNB-type RSU) or gNB, or a UE (referred to as a UE-type RSU). The vehicles 102, 104 and the RSU 110 may use direct communication links to communicate with additional entities, such as an additional vehicle, an RSU, or a UE 112 carried by a pedestrian 114. For example, the vehicle 102 may communicate with the UE 112 via a V2V communication link 113, the vehicle 104 may communicate with the UE 112 via a V2V communication link 115, and the RSU 110 may communicate with the UE 112 via a V2I communication link 117.

[0028] During direct communication with one or more entities in the V2X wireless communication system 100, each entity may provide V2X information, such as the V2X entity's identifier, as well as other information, in messages such as Common Awareness Messages (CAMs) and Decentralized Notification Messages (DENMs) or Basic Safety Messages (BSMs), which may be used, for example, for ADAS or safety applications.

[0029] In other implementations, the vehicles 102 and 104 may communicate with each other indirectly, e.g., through the RSU 110 via V2I communication links 107 and 109, respectively, or through other network infrastructure (not shown), e.g., using cellular vehicle-to-everything (CV2X). For example, the vehicles may communicate through base stations in a Radio Access Network (RAN), such as an evolved Node B (eNB) or next-generation evolved Node B (ng-eNB) in LTE wireless access and / or evolved LTE (eLTE) wireless access or NR Node B (gNB) in fifth-generation (5G) wireless access.

[0030] The vehicles 102 and 104, as well as the RSU 110 and the UE 112, may engage in a ranging / positioning session that includes transmitting and receiving pre-PRS messages, broadcasting a PRS, and transmitting post-PRS messages over links 103, 107, 109, 113, 115, or 117, using which distance or relative location between the entities may be determined. By way of example, the PRS broadcast by the vehicles 102 and 104 may be any signal suitable for ranging, such as those defined for DSRC or C-V2X. The PRS may be broadcast over licensed or unlicensed spectrum. For example, in some implementations, the PRS may be broadcast over one or more Unlicensed National Information Infrastructure (UNII) radio bands, including, for example, one or more of the UNII-1 radio band, the UNII-2A radio band, the UNII-2B radio band, or the UNII-3 radio band. When broadcasting over unlicensed spectrum, a listen before transmit (LBT) protocol may be utilized.

[0031] If vehicles 102 and 104 broadcast a PRS in V2V link 103, the distance or relative location between vehicles 102 and 104 can be determined directly using, for example, one-way ranging. If vehicles 102 and 104 broadcast a PRS in V2I links 107 and 109 or via links 113 and 115, the distance or relative location between vehicle 102 and RSU 110 or UE 112 and between vehicle 104 and RSU 110 or UE 112 can be determined directly using one-way ranging.

[0032] Direct wireless communication between the vehicles 102 and 104 and the RSUs 110 and UEs 112 does not require any network infrastructure and enables low-latency communication that is advantageous for accurate ranging or positioning. Thus, such direct wireless communication may be desirable for ranging over short distances, for example, with nearby vehicles or infrastructure.

[0033] Any of the UEs shown in FIG. 1, for example, V-UE 102, V-UE 104, RSU 110, and UE 112, may be configured to perform ranging and / or positioning operations, such as RTT-based ranging.

[0034] 2 shows, by way of example, a signaling graph 200 illustrating the timing and frequency of various messages that may be sent and received by an initiating UE and three responding UEs for a ranging or positioning session. For example, FIG. 2 illustrates an RTT-based ranging session 204, during which several messages are transmitted between the initiating and responding UEs, including a pre-PRS message 206 to request and accept the ranging session, a PRS signal 208 for measurements, and a post-PRS message 210 to exchange measurement payloads. In FIG. 2, signaling from the initiating UE is shown in white boxes, signaling from the first responding UE is shown in gray boxes, signaling from the second responding UE is shown in shaded boxes, and signaling from the third responding UE is shown in black boxes.

[0035] As shown, UEs, including the initiating UE and the responding UE, may broadcast capability messages 202. The capability messages may include information that is not part of the ranging session but that can be used by the initiating UE to start a ranging session with a selected UE. For example, the capability messages may include a UE ID (e.g., an L2 ID), the ranging capabilities of the UE, the channel the UE is configured to use, etc. While FIG. 2 illustrates the capability messages 202 as having the same order as the messages in the ranging session 204, it should be understood that the order may actually be different.

[0036] The pre-PRS message 206 (e.g., a pre-ranging message) is used by a UE to request and accept a ranging session. As shown, the pre-PRS message 206 may be transmitted over a licensed spectrum to ensure reliability. The pre-PRS message 206 may be broadcast or unicast using a radio resource control (RRC) connection. The initiating UE broadcasts the initial pre-PRS message 206 (shown by the white box) to indicate the ranging session between the initiating UE and the responding UE, which may provide information for the ranging session. For example, the pre-PRS message 206 from the initiating UE may include the identities of the participating UEs, i.e., the initiator ID and the responder ID. The pre-PRS message may include the PRS ID used by the initiating UE and, in some implementations, the PRS ID to be used by the responding UE. If the PRS ID is fixed across multiple PRS exchanges (e.g., for multiple units in the ranging session 204), the initiating UE may include an ID associated with the current PRS exchange, e.g., a session ID. The initiating UE determines when the PRS signal 208 is transmitted, which may be configured, for example, by higher layers at the initiating UE. The initiating UE may indicate the timing of the PRS by transmitting a time slot number close to the desired PRS transmission time. In some implementations, the time slot may be affected by local clock error. In some implementations, the initiating UE may further provide the timing of the PRS to be transmitted by the responding UE. The initiating UE may further indicate the frequency to be used by the initiating UE to broadcast the PRS signal 208. For example, the PRS frequency may be selected from an available set of total bandwidth, or the PRS frequency may be selected by detecting interference and choosing one or more channels whose average interfering reference signal received power (RSRP) is below a threshold. The initiating UE may indicate the number of PRS cycles it will perform during the ranging session 204. The number of PRS cycles may be configured by higher layers.The pre-PRS message for each PRS cycle may, for example, indicate the current PRS cycle in relation to the total PRS cycles requested, with the current cycle number incrementing after the completion of each cycle.

[0037] The initial pre-PRS message from the initiating UE is received and decoded by the responding UE, which is identified in the initial pre-PRS message. The responding UE may transmit a response pre-PRS message 206 (shown by a gray, diagonal, and black box) acknowledging the initial pre-PRS message, which may provide additional information for the ranging session. For example, each responder UE may determine the timing of its PRS signal 208 based, for example, on the initiating UE's PRS timing plus a delay, which may be based on hardware constraints and interference levels, as well as the number and order of responding UEs. For example, the delay may be relatively small when the PRS processing time is small and surrounding interference is small, or relatively large when the PRS processing time is large and surrounding interference is large. The responding UE may indicate the determined time of its PRS by transmitting a time slot number close to the determined PRS transmission time. In some implementations, the time slot may be affected by local clock error. Each responding UE may indicate the PRS ID it uses, or may indicate that it will use the PRS ID indicated in the initial pre-PRS message. If the PRS ID is fixed across multiple PRS exchanges (e.g., multiple PRS cycles in the ranging session 204), the responding UE may include an ID associated with the current PRS exchange, e.g., a session ID, received in the initial pre-PRS message from the initiating UE. Each responding UE may further indicate the frequency used to broadcast its PRS signal 208. The responding UE may broadcast a pre-PRS message 206, which may be received by the initiating UE (and other responding UEs). In some implementations, each responding UE may transmit the pre-PRS message 206 using unicast with the RRC connection.

[0038] PRS signals 208 are exchanged by participating UEs. The initiating UE and responding UE know the expected timing of the PRS signals and know the PRS ID (and any session IDs exchanged and used) and the frequency used to broadcast the PRS signals 208. The PRS signals 208 may be broadcast on an unlicensed spectrum, which may be subject to LBT restrictions. For example, the initiating UE broadcasts its PRS signal 208 (shown by the white box) at a determined time indicated in the initial pre-PRS message 206. In some implementations, the initiating UE broadcasts its PRS signal at the determined time plus a random wait time due to LBT restrictions when PRS signals are deployed in an unlicensed spectrum. In some implementations, the LBT may be a Category 2 LBT with a fixed-time slot of Clear Channel Assessment (CCA) or a Category 4 LBT with a variable-time slot of CCA. The initiating UE uses the PRS signal corresponding to the PRS ID and uses the frequency resources indicated in the initial pre-PRS message 206. The initiating UE saves the time instance at which the PRS signal is broadcast, and the responding UE saves the time instance at which the PRS signal is received, which in some implementations may be subject to local clock error.

[0039] Like the initiating UE, each responding UE broadcasts its PRS signal 208 (shown by a gray, diagonal, and black box) at the determined time indicated in the initial pre-PRS message 206. The determined time indicated (or assigned by the initiating UE) in the pre-PRS message 206. In some implementations, each responding UE may broadcast its PRS signal at the determined time plus a random waiting time due to LBT constraints when PRS signals are deployed in unlicensed spectrum. In some implementations, the LBT may be a Category 2 LBT with a fixed-time slot CCA or a Category 4 LBT with a variable-time slot CCA. Each responding UE uses a PRS signal corresponding to the PRS ID and uses the frequency resources indicated in its pre-PRS message 206. Each responding UE saves the time instance at which its PRS signal is broadcast, and the initiating UE (and optionally other responding UEs) save the time instance at which the PRS signal is received. In some implementations, the time instance may be subject to local clock inaccuracy.

[0040] Thus, each UE records the time of departure (ToD) of its broadcasted PRS signal and measures the time of arrival (ToA) of PRS signals received from other UEs. The PRS signal may be any signal suitable for ranging, such as those defined for DSRC or C-V2X. The PRS signal may be, for example, a pseudo-noise (PN) sequence. The ToA and ToD resolution of the PRS signal increases with increasing frequency bandwidth. In some implementations, the angle of departure (AoD) and angle of arrival (AoA) of the broadcasted and received PRS signal may also be measured. Broadcasting in the unlicensed spectrum is advantageous because wider frequency bands become available. For example, in some implementations, the PRS may be broadcast in one or more UNII radio bands, including, for example, one or more of the UNII-1 radio band, the UNII-2A radio band, the UNII-2B radio band, or the UNII-3 radio band.

[0041] A post-PRS message 210 is transmitted by each UE to exchange measurement payloads. As shown, the post-PRS message 210 may be transmitted over a licensed spectrum to ensure reliability. In some implementations, the post-PRS message 210 may be broadcast or unicast using an RRC connection. The initiating UE transmits its post-PRS message 210 (shown in a white box) and indicates when it broadcasts the PRS signal 208 (ToD) and when the PRS signal from the responding UE was received (ToA). In some implementations, the ToA may be calculated as a relative time with respect to the ToD of that broadcast PRS signal, and that relative time may be given. In some implementations, that relative time may be approximated to the nearest multiple of the timescale shared by the initiating and responding UEs. In some implementations, the initiating UE may provide an indication of its location in the post-PRS message 210, if known. For example, the location of the initiating UE may be its location at a particular time, such as the broadcast time of its PRS signal or the time of arrival of a PRS signal from a responding UE.

[0042] Like the initiating UE, each responding UE transmits its post-PRS signal 210 (shown with a gray, diagonal, and black box) to provide a measurement payload. Each responding UE may indicate whether it received a PRS signal from the initiating UE, when it broadcasts the PRS signal 208 (ToD), and when the PRS signal from the initiating UE (and optionally from other responding UEs) was received (ToA). In some implementations, the ToD may be calculated as a relative time with respect to the ToA of the PRS signal from the initiating UE (and optionally with respect to the ToA of the PRS from the other responding UEs). In some implementations, the relative time may be approximated to the nearest multiple timescales shared by the initiating and responding UEs. In some implementations, the responding UE may provide an indication of its location in the post-PRS message 210, if known. For example, the provided location of the responding UE may be its location at a particular time, such as the time of arrival of the PRS signal from the initiating UE or the time of departure of its broadcast PRS signal.

[0043] After receiving the post-PRS messages, the initiating UE may calculate its distance (and in some implementations its position), for example using a Kalman filter, and then transmit the next cycle of pre-PRS messages at a time indicated by higher layers or automatically determined by the initiating UE.

[0044] The time between the first pre-PRS message 206 and the last post-PRS message 210 may be the duration of the ranging session, for example, 100 msec. In some implementations, multiple instances of the pre-PRS message 206, PRS 208, and post-PRS message 210 may be used in a single ranging session 204 for greater accuracy.

[0045] Both the initiator UE and the responder UE may determine the distance between themselves and each other UE in the ranging session based on the ToD and ToA of the broadcast PRS signal. For example, the RTT between any pair of UEs (which may be any pair of initiator and responder UEs) may be calculated based on the ToD and ToA of the PRS signal. i ToD for traffic lights i and ToA i (where i=1 for the PRS broadcast from the first UE and i=2 for the PRS broadcast by the second UE), it can be determined as the difference between ToD1 and ToA2 minus the difference between ToA1 and ToD2, for example: RTT = (ToD1- ToA2) - (ToA1- ToD2) Equation 1

[0046] Since the RTT value is the round trip time of a signal, the range (distance) between UE1 and UE2 may be determined as RTT / 2c, where c is the speed of light.

[0047] If the locations of one or more UEs are known, the ranging session may be a positioning session, since the distance between the initiating UE and the receiving UE may be used, along with the known location of one of the UEs, to determine the location of the other UE. The location of the UE may be provided to the other UE through messaging, for example, in a pre-PRS message or a post-PRS message. If the locations of multiple UEs are known, multilateration may be used to determine the locations of the remaining UEs. Angle measurements, for example, AoD and AoA, may be used, for example, to assist in positioning. As an example, the relative locations of the two UEs may be determined based on the distance between them and the measured AoA. Using the determined relative locations of the UEs, the actual location of the other UE may be determined if the actual location of one of the UEs (e.g., which may be provided in a pre-PRS message 206 or a post-PRS message 210) is known. When the locations of two UEs are known by a third UE, the distance between the third UE and each of the other two UEs yields two possible locations for the third UE, which can be resolved based on AoD / AoA information. AoD can be useful, for example, when the resolution of AoA is low or inaccurate. AoD can be measured, for example, based on the known orientation of the UE (e.g., determined by a magnetometer) and the direction of the transmitted signal relative to the UE (e.g., relative to the UE's antenna array used for beamforming). AoA can be measured based on the phase difference of received signals at different antenna elements of the antenna array and the known orientation of the UE (e.g., determined by a magnetometer). In addition, geographic constraints can be used to assist positioning, for example, by constraining the possible locations of a vehicle-based UE to locations accessible to vehicles, such as roads.

[0048] As discussed above, the initiating UE broadcasts a pre-PRS message that conventionally includes a relatively large payload size containing identification, signaling, and timing information to be used for various messages in the ranging session. When there are multiple responding UEs involved in the ranging session, the payload size of the pre-PRS message can significantly increase overhead and the possibility of collisions with messages in other simultaneous ranging sessions.

[0049] To reduce the size of the pre-PRS message 206 transmitted by the initiating UE, each UE in the ranging session may separately determine the timing instance of signaling in the ranging session based on a vector of UE IDs of the initiating UE and responding UE provided in the pre-PRS message from the initiating UE. In some implementations, additional information, such as a PRS identifier or other signaling information, may be separately determined by each UE based on the vector of UE IDs provided in the pre-PRS message. If each UE separately determines the timing instance for signaling (and signaling information), the initial pre-PRS message 206 does not explicitly include this information, significantly reducing the size of the pre-PRS message 206 transmitted by the initiating UE.

[0050] For example, a multivariate deterministic function may be shared and used by each UE to reduce the payload size of a pre-PRS message from the initiating UE. The multivariate deterministic function may, for example, use a vector of UE IDs provided by the initiating UE in the pre-PRS message 206 to generate a unique timing instance for signaling in the ranging session. The initiating UE may obtain the UE IDs, for example, from a capabilities message 202 sent by each responding UE. The capabilities message 202 may further include an indication of the timing determination capability of the responding UE (e.g., whether the UE is capable of using a multivariate deterministic function to determine the timing of messages in the ranging session). In some implementations, the order of UE IDs in the vector of UE IDs may contribute to generating a unique timing instance. The multivariate deterministic function may, for example, be a hash function or another type of function that associates a set of input data (e.g., a vector of UE IDs) with timing information for all supporting messages in the ranging session. Any desired multivariate deterministic function may be used, as may be generated by one skilled in the art, but it must provide a one-to-one mapping (invertible) of outputs for each set of inputs. A multivariate deterministic function may be invertible so that it uniquely produces a set of outputs from a set of inputs in a reproducible manner (e.g., (1,2,3) = f(4,5,6), (1,2,4) = f(4,5,8)), and the input values ​​can be uniquely inferred from the output values, e.g., the mapping can be reversed. The inputs and outputs may be vectors, and the function f may operate as an invertible function in vector space.

[0051] As an example, a multivariate deterministic function may be written as follows, using a vector of UE IDs as input: F(a, b, c, d, e, f, ...) = (x, y, z, w, v, ...) Equation 2

[0052] where (a, b, c, d, e, f, ...) are inputs to the multivariate deterministic function F (e.g., a vector of UE IDs including the initiator UE ID and responder UE ID as provided in the pre-PRS message from the initiator UE), and (x, y, z, w, v, ...) are outputs of the multivariate deterministic function F (e.g., timing instances for the remaining signaling in the ranging session and signaling information such as PRS IDs).

[0053] 3 shows an example of a multivariate deterministic function F that may be used. For example, the input to the multivariate deterministic function F may be provided as a vector of UE IDs 302, including, for example, the L2 ID of the initiating UE (24 bits), the number of responding UEs M (which is implicit in the vector of IDs), the L2 ID of the responding UE R1-RM (24*M bits, where M is the number of responding UEs), and the specific order of the responding UEs (which is implicit in the vector of IDs).

[0054] As indicated by arrow 305, the multivariate deterministic function F may map inputs to outputs of the multivariate deterministic function F, and may include, for example, a broadcast time instance 304 (an integer for the slot number) for the pre-PRS message 206, including the pre-PRS message 206 broadcast timing for each responding UE, a PRS ID 306 (an integer for the PRS ID of the initiating UE and the responding UE), a broadcast timing 308 for the PRS signal 208 for the initiating UE (an integer for the slot number, which may be an approximation if unlicensed spectrum is used due to LBT constraints), and a broadcast time instance 310 (an integer for the slot number) for the post-PRS message 210, including the post-PRS message 210 broadcast timing for the initiating UE and each responding UE. In some implementations, the broadcast timing 308 may include the PRS signal 208 from the responding UE, for example, if licensed spectrum is used, or may be an approximation if unlicensed spectrum is used due to LBT constraints.

[0055] The use of a multivariate deterministic function shared by all UEs in a ranging session allows each UE to independently generate timing information for supporting messages in the ranging session with little or no risk of error. Thus, the size of the pre-PRS message 206 broadcast by the initiating UE can be significantly reduced, thereby reducing contention with messages from other ranging sessions and allowing for improved scalability while increasing reliability.

[0056] 4 shows an example signaling flow 400 of a ranging procedure using a deterministic function to determine timing instances of signaling during a ranging and / or positioning session, as described herein. The ranging procedure includes an initiator UE1 402 and multiple responding UEs UE2 404, UE3 406, and UE4 408. The initiator and responding UEs 402, 404, 406, and 408 may be similar to one or more of the vehicle-based UEs (V-UEs) 102 and 104, the RSU 110, or the UE 112, as described in FIG. 1. While FIG. 4 shows signaling for several responding UEs, it should be understood that additional (or less) signaling than that shown in FIG. 4 may be involved if additional or fewer responding UEs are desired to be included in the ranging session. As shown, the communication between UEs 402, 404, 406, and 408 in FIG. 4 may be direct communication between the entities and may not involve an infrastructure device, such as a base station, to transfer messages between the entities.

[0057] In stage 1, each initiating UE 402 and responding UEs 404, 406, and 408 broadcasts a capability message to be received by other nearby UEs. The capability message may not be part of the ranging session but may include information that can be used by the initiating UE to start a ranging session with a selected UE. For example, the capability message may include a UE ID (e.g., an L2 ID), the UE's ranging capability, the channel the UE is configured to use, and an indication of timing determination capability (e.g., whether the UE is capable of using a multivariate deterministic function to determine the timing of messages in the ranging session). If multiple multivariate deterministic functions are available, the capability message may indicate which multivariate deterministic function the UE is configured to perform. The capability message in stage 1 may be broadcast periodically by the UE.

[0058] In stage 2, the initiating UE1 402 prepares and broadcasts a pre-PRS message to request a ranging session with the selected responding UEs 404, 406, and 408. The pre-PRS message may be broadcast over a licensed spectrum. As discussed above, the pre-PRS message prepared and broadcast by the initiating UE1 402 may include signaling information such as the UE IDs (e.g., L2 IDs) of the initiating UE1 402 and the responding UEs 404, 406, and 408, and a PRS bandwidth or channel for the initiating UE1 402, and in some implementations, the PRS IDs of the initiating UE1 402 and the responding UEs 404, 406, and 408. The pre-PRS message from initiator UE1 402 may include an indication of which multivariate deterministic function should be used by the responding UE to determine the timing instance (e.g., if there are multiple available multivariate deterministic functions), but does not include timing information for signaling in the ranging session and may not include any signaling information such as a PRS ID. In some implementations, the pre-PRS message may further include the current location of initiator UE1 402, for example, if known.

[0059] In stage 3, which includes stages 3A, 3B, 3C, and 3D, each UE 402, 404, 406, and 408 determines timing instances for messages in the ranging session based on the UE IDs of the initiator UE 1 402 and responder UEs 404, 406, and 408 provided in the pre-PRS messages in stage 2. In some implementations, the vector of UE IDs can be used to determine timing instances for messages in the ranging session, such as the timing instance of the pre-PRS message from the responder UE 404, 406, and 408 (and in some implementations, from the initiator UE 1 402), the timing instance or approximate timing instance of the PRS from the initiator UE 1 402 (and in some implementations, from the responder UE 404, 406, and 408), and the timing instance of the post-PRS message from the initiator UE 1 402 and responder UE 404, 406, and 408. Additionally, signaling information such as PRS IDs of the initiating UE1 402 and the responding UEs 404, 406, and 408 may be determined based on the UE IDs of the initiating UE1 402 and the responding UEs 404, 406, and 408 provided in the pre-PRS messages in stage 2. In some implementations, the order of the UE IDs and / or the number of responding UEs may be used to determine the timing instance for signaling in the ranging session. A unique timing instance (and optionally a PRS ID) may be determined separately by each UE using a shared multivariate deterministic function, such as a hash function or other similar function. Although stage 3A by the initiating UE1 402 is shown as being performed after broadcasting the pre-PRS start message in stage 2, it should be understood that in some implementations, the initiating UE1 402 may perform stage 3A before stage 2 and may broadcast the pre-PRS message from stage 2 in accordance with a unique timing instance determined by the multivariate deterministic function.Furthermore, if the pre-PRS message from stage 2 is broadcast at a determined unique timing instance, the responding UEs 404, 406, and 408 may similarly determine a unique timing instance for the pre-PRS message from the initiating UE 1 402 using a multivariate deterministic function and the time of receipt of the pre-PRS message for clock alignment with the initiating UE 1 402 and other responding UEs.

[0060] In stage 4, each responding UE 404, 406, and 408 broadcasts a pre-PRS message in response to the initial pre-PRS message at a unique time instance for each responding UE determined in stages 3B, 3C, and 3D. The response pre-PRS message may, for example, acknowledge the initiating pre-PRS message from stage 2 and may provide signaling information such as the PRS bandwidth or channel used by the responding UE. The stage 4 pre-PRS messages may be transmitted in a licensed spectrum. In some implementations, any pre-PRS messages broadcast by the responding UE may further include the current location of the responding UE, if known.

[0061] In stage 5, PRS signals are broadcast by initiating UE1 402 and responding UEs 404, 406, and 408. The PRS signals may be broadcast in an unlicensed spectrum to use a wide frequency band. For example, the first PRS signal from initiating UE1 402 may be broadcast at a time instance uniquely determined in stage 3. Subsequent PRS signals from responding UEs 404, 406, and 408 may be broadcast in a specified order, for example, based on a vector of UE IDs and on an LBT constraint, for example, as determined in stage 3. Alternatively, subsequent PRS signals from responding UEs 404, 406, and 408 may be broadcast at a time instance uniquely determined in stage 3, which may be an approximate time instance if the PRS signals are broadcast in an unlicensed spectrum. Each broadcasting UE records the ToD, and in some implementations, the AoD, of the broadcast PRS signal, and each receiving UE records the ToA, and in some implementations, the AoA, of each received PRS signal.

[0062] In stage 6, post-PRS messages are broadcast by initiator UE1 402 and responder UEs 404, 406, and 408 at unique time instances for each UE determined in stages 3A, 3B, 3C, and 3D. The post-PRS messages may be transmitted, for example, in licensed spectrum. The post-PRS messages from each UE indicate the ToD, and in some implementations, the AoD, of the PRS signals broadcast by the UE, and further indicate the ToA, and in some implementations, the AoA, of each PRS signal received by the UE.

[0063] In stage 7, which includes stages 7A, 7B, 7C, and 7D, the initiator UE 1 402 and each responder UE 404, 406, and 408 determine the distance between itself and the other UEs in the ranging session based on the ToD and ToA of the PRS signals broadcast in stage 5. For example, the distance can be determined by the PRS i ToD for signals i and ToA i (where i=1 for the PRS broadcast from the first UE and i=2 for the PRS broadcast from the second UE):

[0064]

number

[0065] If the location of one or more UEs is known, e.g., provided in a pre-PRS message in stage 2 or 4, and / or angular information such as the AoA or AoD of the PRS signal, and / or geographic information such as street location is known, the relative or actual location of the UE may be determined, e.g., using multilateration and constraints according to the AoA or AoD of the PRS signal and geographic information.

[0066] In some implementations, steps 2-7 may be repeated for multiple instances of pre-PRS, PRS, and post-PRS messages during a ranging session for greater accuracy.

[0067] 5 shows a schematic block diagram illustrating some example features of a user equipment (UE) 500, which may be a UE in a vehicle 102 or 104, an RSU 110, or a UE 112 carried by a pedestrian 114, as shown in FIG. 1, or any UE shown in FIG. 4. The UE 500 may be configured to act as an initiating UE or a responding UE in a ranging session, in which a deterministic function, as discussed herein, is used to determine timing instances of signaling during the ranging session. If the UE 500 is a V-UE, it may be configured to control autonomous driving of a vehicle, e.g., the vehicle 102. For example, the UE 500 may include a vehicle interface 505 through which commands may be given to the vehicle for autonomous driving and sensory inputs, including speed and acceleration, may be provided from the vehicle to the UE 500. For example, the UE 500 may include one or more processors 502, memory 504, an inertial measurement unit (IMU) 507 that may include, for example, an accelerometer, gyroscope, magnetometer, etc., which may be used to detect orientation with respect to a global or local reference frame and vehicle motion or one or more motion characteristics, a satellite positioning system (SPS) receiver 509 for determining, for example, a GPS position, and external interfaces including, for example, a wireless wide area network (WWAN) transceiver 510 and a wireless local area network (WLAN) transceiver 514 that may be operatively coupled with one or more connections 506 (e.g., buses, lines, fibers, links, etc.) to the non-transitory computer-readable medium 520 and the memory 504. The UE 500 may further include additional items not shown, such as a user interface that may include, for example, a display, a keypad, or other input device, such as a virtual keypad on a display, through which a user may interface with the user device. In some example implementations, all or a portion of the UE 500 may be in the form of a chipset or the like.

[0068] The transceiver 510 may be, for example, a cellular transceiver configured to transmit and receive direct communications in a wireless network, such as shown in FIG. 1. The transceiver 510 may include a transmitter 511 enabled to transmit one or more signals over one or more types of wireless communication networks and a receiver 512 for receiving one or more signals transmitted over the one or more types of wireless communication networks. The transceiver 514 may be, for example, a short-range transceiver and may be configured to transmit and receive direct communications in a wireless network, such as shown in FIG. 1. The transceiver 514 may include a transmitter 515 enabled to transmit one or more signals, including PRS signals and pre-PRS and post-PRS messages, over one or more types of wireless communication networks, and a receiver 516 for receiving one or more signals, including, for example, PRS messages and pre-PRS and post-PRS messages, transmitted over the one or more types of wireless communication networks. The transceivers 510 and 514 enable the UE 500 to communicate with transportation entities using a D2D communication link, such as DSRC, C-V2X, or 5G NR.

[0069] In some embodiments, the UE 500 may include an antenna 509, which may be internal or external. The antenna 509 may be used to transmit and / or receive signals processed by the transceiver 510 and / or transceiver 514. In some embodiments, the antenna 509 may be coupled to the transceiver 510 and / or transceiver 514. In some embodiments, measurements of signals received (transmitted) by the UE 500 may be performed at the connection point of the antenna 509 and the transceiver 510 and / or transceiver 514. For example, the measurement reference points for received (transmitted) RF signal measurements may be the input (output) terminals of the receivers 512, 516 (transmitters 511, 515) and the output (input) terminal of the antenna 509. In a UE 500 with multiple antennas 509 or an antenna array, the antenna connectors may be considered to be virtual points representing the aggregate outputs (inputs) of the multiple antennas. The phase difference of the received signal at multiple antennas or antenna arrays may be used to determine the AoA of the signal with respect to the antenna array, which may be converted to a local or global reference frame based on the known orientation of the UE 500, for example based on the orientation of the UE 500 to a global or local reference frame as measured by the IMU 507.

[0070] The one or more processors 502 may be implemented using a combination of hardware, firmware, and software. For example, the one or more processors 502 may be configured to perform the functions discussed herein by implementing one or more instructions or program code 508 on a non-transitory computer-readable medium, such as the medium 520 and / or the memory 504. In some embodiments, the one or more processors 502 may represent one or more circuits configurable to perform at least a portion of a data signal computation procedure or process related to the operation of the UE 500.

[0071] The medium 520 and / or memory 504 may store instructions or program code 508, including executable code or software instructions that, when executed by the one or more processors 502, cause the one or more processors 502 to operate as special-purpose computers programmed to perform the techniques disclosed herein. As shown in the UE 500, the medium 520 and / or memory 504 may include one or more components or modules that can be implemented by the one or more processors 502 to perform the methods described herein. While the components or modules are shown as software in the medium 520 executable by the one or more processors 502, it should be understood that the components or modules may be stored in the memory 504 or may be dedicated hardware either within the one or more processors 502 or external to the processor(s).

[0072] A number of software modules and data tables may reside in the medium 520 and / or memory 504 and may be utilized by the one or more processors 502 to manage both the communications and functionality described herein. It should be understood that the organization of the contents of the medium 520 and / or memory 504 as shown in the UE 500 is merely exemplary, and that the functionality of the modules and / or data structures may be combined, separated, and / or structured in various ways depending on the implementation of the UE 500.

[0073] The medium 520 and / or memory 504 may include a pre-PRS module 522 that, when implemented by the one or more processors 502, configures the one or more processors 502 to generate and transmit or receive a pre-PRS message via the transceiver 514, e.g., to initiate a ranging session or accept a ranging session. The one or more processors 502 may be configured to broadcast the pre-PRS message via the transceiver 514 at a specific timing instance determined using the timing determination module 524. The pre-PRS message may include UE IDs of the initiating UE and the responding UE, e.g., in a vector of UE IDs. The UE IDs may be L2 IDs, e.g., that may be obtained from a capability message periodically broadcast by the UE. The pre-PRS message sent by the initiating UE may include an indication that the timing instance for messages in the ranging session is determined using a function that uses the IDs of the initiating UE and the responding UE. The pre-PRS message may include an indication of a channel for a ranging signal to be broadcast by the UE, but may not include any timing information for the ranging session. In some implementations, the pre-PRS message may include location information of the UE 500, if known.

[0074] The medium 520 and / or the memory 504 may include a timing determination module 524 that, when implemented by the one or more processors 502, configures the one or more processors 502 to determine timing instances for messages from an initiating UE and one or more responding UEs in a ranging session based on the UE IDs of each of the initiating UE and one or more responding UEs. The one or more processors 502 may be configured to determine timing instances for messages in a ranging session based on the UE IDs, the order of UE IDs provided in the pre-PRS message, and the number of responding UEs. The timing instances may be uniquely determined. For example, a multivariate deterministic function, such as a hash function, may be used to determine timing instances for messages in a ranging session based on the UE IDs, and the multivariate deterministic function may be shared, i.e., commonly used, by each UE in the ranging session. The multivariate deterministic function may use a vector of UE IDs, including an implicit order of UE IDs and the number of responding UEs, as inputs and may output timing instances for the pre-PRS and post-PRS messages. The timing instance of one or more PRS signals (or approximate timing instance if the PRS is transmitted in unlicensed spectrum) may also be output. Signaling information such as the PRS ID of each UE in the ranging session may also be output.

[0075] The medium 520 and / or memory 504 may include a PRS module 526 that, when implemented by the one or more processors 502, configures the one or more processors 502 to broadcast ranging signals to other UEs and receive them via the transceiver 514, e.g., in an unlicensed spectrum. The one or more processors 502 may be configured to broadcast ranging signals via the transceiver 514 at or approximately at a particular timing instance determined using the timing determination module 524 and / or based on LBT considerations if the PRS signals are broadcast in an unlicensed spectrum. The ranging signals may be, for example, PRS signals as discussed herein. The one or more processors 502 may be configured, for example, to measure the ToD of the broadcast ranging signal and the ToA of the received ranging signal, and may be configured to measure the AoD of the broadcast ranging signal and the AoA of the received ranging signal.

[0076] The medium 520 and / or memory 504 may include a post-PRS module 528 that, when implemented by the one or more processors 502, configures the one or more processors 502 to transmit to, and receive via the transceiver 514, a post-RS message that may include, for example, the ToD, and in some implementations the AoD, of the broadcast ranging signal, as well as the ToA, and in some implementations the AoA, of the received ranging signal. The one or more processors 502 may be configured to broadcast the post-PRS message via the transceiver 514 at a particular timing instance determined using the timing determination module 524.

[0077] The medium 520 and / or the memory 504 may include a ranging module 530 that, when implemented by the one or more processors 502, configures the one or more processors 502 to determine a distance to another UE based on the ToD and ToA of the broadcasted and received ranging signal as measured by the UE 500 and received in the post-PRS message. The processor 502 may be further configured to determine a location of the UE 500 based on, for example, one or more distances to the broadcasting UE and its location information using multilateration or other suitable techniques discussed herein, such as using angular information and geographic information.

[0078] The medium 520 and / or memory 504 may include a capabilities module 532 that, when implemented by the one or more processors 502, configures the one or more processors 502 to broadcast and receive via the transceiver 514 a capability message that includes a UE ID, e.g., an L2 ID, a bandwidth or channel that the UE is configured to use, a timing determination capability, e.g., an indication that the UE can use a deterministic function to determine timing instances of messages in a positioning session, and in some implementations which deterministic function the UE is configured to use.

[0079] The methods described herein may be implemented by various means depending on the application. For example, the methods may be implemented in hardware, firmware, software, or any combination thereof. In a hardware implementation, the one or more processors 502 may be implemented with one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or combinations thereof.

[0080] For a firmware and / or software implementation, methods may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. Any machine-readable medium tangibly embodying instructions may be used in implementing the methods described herein. For example, software code may be stored in non-transitory computer-readable medium 520 or memory 504 coupled to and executed by one or more processors 502. The memory may be implemented within the one or more processors or external to the one or more processors. The term “memory,” as used herein, may refer to any type of long-term, short-term, volatile, non-volatile, or other memory and should not be limited to any particular type of memory or any particular number of memories, or to any particular type of medium on which the memory is stored.

[0081] If implemented in firmware and / or software, the functions may be stored as one or more instructions or program code 508 on a non-transitory computer-readable medium, such as medium 520 and / or memory 504. Examples include computer-readable media encoded with data structures and computer-readable media encoded with a computer program 508. For example, a non-transitory computer-readable medium having program code 508 stored thereon may include program code 508 for supporting ranging sessions that use a deterministic function to determine timing instances of signaling during the ranging session, in a manner consistent with the disclosed embodiments. The non-transitory computer-readable medium 520 includes a physical computer storage medium. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such non-transitory 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 store desired program code 508 in the form of instructions or data structures and that can be accessed by a computer; disk and disc, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, 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.

[0082] In addition to being stored on the computer-readable medium 520, the instructions and / or data may be provided as signals on a transmission medium included in a communications device. For example, a communications device may include a transceiver 510 having signals indicative of instructions and data. The instructions and data are configured to cause one or more processors to implement the functions outlined in the claims. That is, the communications device includes a transmission medium with signals indicative of information to perform the disclosed functions.

[0083] Memory 504 may represent any data storage mechanism. Memory 504 may include, for example, primary memory and / or secondary memory. Primary memory may include, for example, random access memory, read-only memory, etc. While shown in this example as being separate from one or more processors 502, it should be understood that all or a portion of the primary memory may be provided within one or more processors 502 or may otherwise be co-located / coupled with one or more processors 502. Secondary memory may include, for example, the same or similar type of memory as the primary memory and / or one or more data storage devices or systems, such as, for example, disk drives, optical disk drives, tape drives, solid-state memory drives, etc.

[0084] In some implementations, the secondary memory may operatively receive, or in some cases may be configurable to couple to, a non-transitory computer-readable medium 520. Thus, in some example implementations, the methods and / or apparatuses presented herein may take the form, in whole or in part, of a computer-readable medium 520 on which computer-implementable code 508 may be stored, which, when executed by one or more processors 502, may be operable to perform all or a portion of the example operations as described herein. The computer-readable medium 520 may be part of the memory 504.

[0085] FIG. 6 is a flowchart 600 illustrating a method for measuring distance between user equipments (UEs) performed by an initiating UE in a ranging session, such as a V-UE 102, a V-UE 104, an RSU 110, or a UE 112.

[0086] At block 602, an initial message is sent to one or more responding UEs to initiate a ranging session, e.g., as discussed in stage 2 of FIG. 4, where the initial message comprises an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs. The ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, a vector of IDs. The ID may be an L2 ID. In some implementations, e.g., as discussed in stage 2 of FIG. 4, the initial message may further comprise an indication that a timing instance for messages in the ranging session is determined using a function that uses the ID of the initiating UE and the ID of each of the one or more responding UEs as input. In some implementations, e.g., as discussed in stage 2 of FIG. 4, the initial message may further comprise an indication of a channel for a ranging signal to be broadcast by the initiating UE. For example, as discussed in stage 2 of FIG. 4, the initial message may not include any timing information for the ranging session. The means for sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and the IDs of each of the one or more responding UEs, may be, for example, a transceiver 514 and one or more processors 502 having dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a pre-PRS module 522 in the UE 500.

[0087] In block 604, a timing instance is determined for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs, e.g., as discussed in stage 3A of FIG. 4 . In some embodiments, block 604 may be performed before block 602. In some implementations, the timing instance for the messages in the ranging session is determined further based on the order of the IDs of the initiating UE and each of the one or more responding UEs. In some implementations, the timing instance for the messages in the ranging session is uniquely determined. The means for determining the timing instance for messages in the ranging session from each of the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as timing determination module 524 in UE 500.

[0088] At block 606, a ranging session may be performed with each of the one or more responding UEs using the determined timing instances for messages in the ranging session, e.g., as discussed in stages 4, 5, 6, and 7A. Means for performing a ranging session with each of the one or more responding UEs using the determined timing instances for messages in the ranging session may be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a PRS module 526, a post-PRS module 528, and a ranging module 530 in the UE 500.

[0089] In one implementation, as discussed in stages 3A, 3B, 3C, and 3D, timing instances for messages in the ranging session may be determined using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, where each of the one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session. The means for using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of the one or more responding UEs, where each of the one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session, may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a timing determination module 524 in UE 500.

[0090] In some implementations, the UE may further determine a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs, for example, as discussed in stage 3A of Figure 4. The means for determining a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a timing determination module 524 in the UE 500.

[0091] In some implementations, the ranging session may be performed by receiving an initial response message from each of the one or more responding UEs based on the determined timing instance, as discussed in step 4 of FIG. 4, broadcasting a ranging signal and receiving a response ranging signal broadcast by each of the one or more responding UEs, as discussed in step 5 of FIG. 4, transmitting a post-ranging signal message to each of the one or more responding UEs based on the determined timing instance, as discussed in step 6 of FIG. 4, and receiving a response post-ranging signal message from each of the one or more responding UEs based on the determined timing instance, as discussed in step 7A of FIG. 4, and determining a distance to each of the one or more responding UEs. By way of example, the post-ranging signal message may comprise a time of departure of the ranging signal and a time of arrival of the reply ranging signal received from each of the one or more responding UEs, the reply post-ranging signal message from each of the one or more responding UEs may comprise a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and determining the distance to each of the one or more responding UEs may use the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the reply post-ranging signal message. Means for receiving an initial response message from each of the one or more responding UEs based on the determined timing instance may be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a pre-PRS module 522 in the UE 500.The means for broadcasting the ranging signal and the means for receiving the reply ranging signal broadcasted by each of the one or more responding UEs may be, for example, a transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a PRS module 526 in the UE 500. The means for transmitting a post-ranging signal message to each of the one or more responding UEs based on the determined timing instance and means for receiving a reply post-ranging signal message from each of the one or more responding UEs based on the determined timing instance may be, for example, a transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a post-PRS module 528 in the UE 500. The means for determining the distance to each of the one or more responding UEs may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a ranging module 530 in the UE 500.

[0092] In some implementations, the UE may further receive a capability message from each of the one or more responding UEs before sending the initial message, each capability message comprising the ID of the responding UE, e.g., as discussed in stage 1 of FIG. 4. Each capability message may further include an indication that the responding UE is capable of determining a timing instance for messages in the ranging session based on the ID of the initiating UE and the ID of each of the one or more responding UEs. Means for receiving a capability message from each of the one or more responding UEs before sending the initial message, each capability message comprising the ID of the responding UE, may be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a capabilities module 532 in the UE 500.

[0093] FIG. 7 is a flowchart 700 illustrating a method for measuring distance between user equipments (UEs) performed by a responding UE in a ranging session, such as a V-UE 102, a V-UE 104, an RSU 110, or a UE 112.

[0094] At block 702, an initial message is received from an initiating UE to initiate a ranging session, e.g., as discussed in stage 2 of FIG. 4, where the initial message comprises an identifier (ID) of the initiating UE and an ID of each of one or more responding UEs. The ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, a vector of IDs. The ID may be an L2 ID. In some implementations, e.g., as discussed in stage 2 of FIG. 4, the initial message may further comprise an indication that timing instances of messages in the ranging session are determined using a function that uses the ID of the initiating UE and the ID of each of the one or more responding UEs as input. In some implementations, e.g., as discussed in stage 2 of FIG. 4, the initial message may further comprise an indication of a channel for a ranging signal to be broadcast by the initiating UE. For example, as discussed in stage 2 of FIG. 4, the initial message may not include any timing information for the ranging session. The means for receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and the IDs of each of one or more responding UEs, may be, for example, a transceiver 514 and one or more processors 502 having dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a pre-PRS module 522 in the UE 500.

[0095] At block 704, a timing instance is determined for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs, e.g., as discussed in step 3B of FIG. 4. In some implementations, the timing instance for the messages in the ranging session is further determined based on the order of the IDs of the initiating UE and each of the one or more responding UEs. In some implementations, the timing instance for the messages in the ranging session is uniquely determined. The means for determining the timing instance for messages in the ranging session from each of the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as timing determination module 524 in UE 500.

[0096] At block 706, a ranging session may be performed with the initiating UE using the determined timing instances for messages in the ranging session, e.g., as discussed in stages 4, 5, 6, and 7B. Means for performing a ranging session with the initiating UE using the determined timing instances for messages in the ranging session may be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a PRS module 526, a post-PRS module 528, and a ranging module 530 in the UE 500.

[0097] In one implementation, as discussed in stages 3A, 3B, 3C, and 3D, timing instances for messages in the ranging session may be determined using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, where the initiating UE and each of the one or more responding UEs use the multivariate deterministic function to determine timing instances for messages in the ranging session. The means for using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of the one or more responding UEs, where the initiating UE and each of the one or more responding UEs use the multivariate deterministic function to determine timing instances for messages in the ranging session, may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a timing determination module 524 in UE 500.

[0098] In some implementations, the UE may further determine a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs, for example, as discussed in stage 3A of Figure 4. The means for determining a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a timing determination module 524 in the UE 500.

[0099] In some implementations, the ranging session may be performed by transmitting an initial response message to the initiating UE based on the determined timing instance as discussed in step 4 of Figure 4, receiving a ranging signal broadcast by the initiating UE and broadcasting a response ranging signal as discussed in step 5 of Figure 4, receiving a post-ranging signal message from the initiating UE based on the determined timing instance as discussed in step 6 of Figure 4 and transmitting a response post-ranging signal message to the initiating UE based on the determined timing instance as discussed in step 7B of Figure 4. As an example, the post-ranging signal message received from the initiating UE may comprise a time of departure of the ranging signal and a time of arrival of the response ranging signal, and the response post-ranging signal message sent to the initiating UE may comprise a time of arrival of the ranging signal and a time of departure of the response ranging signal broadcast by each of one or more responding UEs, and determining the distance to the initiating UE may use the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the response post-ranging signal message. The means for transmitting an initial response message to the initiating UE based on the determined timing instance can be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a pre-PRS module 522 in the UE 500. The means for receiving the ranging signal broadcast by the initiating UE and the means for broadcasting the response ranging signal can be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a PRS module 526 in the UE 500.The means for receiving a post-ranging signaling message from the initiating UE based on the determined timing instance and the means for transmitting a response post-ranging signaling message to the initiating UE based on the determined timing instance may be, for example, a transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a post-PRS module 528 in the UE 500. The means for determining a distance to the initiating UE may be, for example, one or more processors 502 with dedicated hardware or implementing executable code or software instructions in memory 504 and / or medium 520, such as a ranging module 530 in the UE 500.

[0100] In some implementations, as discussed in stage 1 of FIG. 4 , the UE may further broadcast a capability message before receiving the initial message, where the capability message comprises the ID of the responding UE. The capability message may further comprise an indication that the responding UE is able to determine a timing instance for messages in the ranging session based on the ID of the initiating UE and the ID of each of the one or more responding UEs. The means for broadcasting a capability message before receiving the initial message, where the capability message comprises the ID of the responding UE, may be, for example, the transceiver 514 and one or more processors 502 with dedicated hardware or implementing executable code or software instructions in the memory 504 and / or medium 520, such as a capabilities module 532 in the UE 500.

[0101] References throughout this specification to "one example," "an example," "some examples," or "exemplary implementations" mean that a particular feature, structure, or characteristic described with respect to a feature and / or example may be included in at least one feature and / or example of the claimed subject matter. Thus, appearances of the phrases "in one example," "an example," "some examples," or "in some implementations" or other similar phrases in various places throughout this specification are not necessarily all referring to the same features, examples, and / or limitations. Furthermore, particular features, structures, or characteristics may be combined in one or more examples and / or characteristics.

[0102] Some portions of the detailed descriptions contained herein are presented in terms of algorithms or symbolic representations of operations on binary digital signals stored in the memory of a particular apparatus or special-purpose computing device or platform. In the context of this particular specification, the term particular apparatus or the like includes a general-purpose computer that, when programmed, performs particular operations pursuant to instructions from program software. Algorithmic descriptions or symbolic representations are examples of techniques used by those skilled in the signal processing or related arts to convey the substance of their work to others skilled in the art. An algorithm, as used herein, and generally, is considered to be a self-consistent sequence of operations or similar signal processing leading to a desired result. In this context, operations or processing involve physical manipulations of physical quantities. Usually, though not necessarily, such quantities may take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, primarily for reasons of common usage, to refer to such signals as bits, data, values, elements, symbols, characters, terms, numbers, numeric values, or the like. It should be understood, however, that all of these or similar terms are to be associated with the appropriate physical quantities and are merely convenient labels. Unless otherwise expressly indicated, and as will be apparent from the description herein, it will be understood that throughout this specification, descriptions utilizing terms such as "processing," "calculating," "computing," "determining," etc. refer to the actions or processes of a particular apparatus, such as a special purpose computer, a special purpose computing apparatus, or a similar special purpose electronic computing device. Thus, in the context of this specification, a special purpose computer or a similar special purpose electronic computing device is capable of manipulating or transforming signals, which are typically represented as physical electronic or magnetic quantities within a memory, register, or other information storage, transmission, or display device of the special purpose computer or similar special purpose electronic computing device.

[0103] In the foregoing detailed description, numerous specific details are set forth to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other instances, methods and apparatuses that would be known by those skilled in the art have not been described in detail so as not to obscure the claimed subject matter.

[0104] As used herein, the terms "and," "or," and "and / or" can have a variety of meanings, which are expected to depend at least in part on the context in which such terms are used. Typically, when "or" is used to link a list such as A, B, or C, it is intended to mean A, B, and C, which is used herein in an inclusive sense, as well as A, B, or C, which is used herein in an exclusive sense. Additionally, as used herein, the term "one or more" may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe a plurality of features, structures, or characteristics, or some other combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and claimed subject matter is not limited to this example.

[0105] While what are presently considered to be exemplary features have been illustrated and described, it will be understood by those skilled in the art that various other modifications may be made and equivalents may be substituted without departing from the claimed subject matter. Additionally, many modifications may be made to adapt a particular situation to the teachings of the claimed subject matter without departing from the central concept described herein.

[0106] Example implementations are described in the following numbered clauses.

[0107] 1. A method for measuring distance between user equipment (UE) performed by an initiator UE, comprising: sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and the ID of each of the one or more responding UEs; determining a timing instance for a message in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; performing a ranging session with each of the one or more responding UEs using the determined timing instances for messages in the ranging session.

[0108] 2. The method of clause 1, wherein the step of determining a timing instance for a message in the ranging session comprises using a multivariate deterministic function to determine a timing instance for a message in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the one or more responding UEs uses the multivariate deterministic function to determine a timing instance for a message in the ranging session.

[0109] 3. The method of any of clauses 1 or 2, wherein the step of determining timing instances for messages in the ranging session is further based on an order of IDs of each of the initiating UE and one or more responding UEs.

[0110] 4. Any of the methods of clauses 1 to 3, wherein timing instances for messages in a ranging session are uniquely determined.

[0111] 5. The method of any of clauses 1 to 4, further comprising determining a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs.

[0112] 6. The method of any of clauses 1 to 5, wherein the initial message further comprises an indication that a timing instance for messages in the ranging session is determined using a function that uses as input the ID of the initiating UE and the ID of each of the one or more responding UEs.

[0113] 7. The method of any of clauses 1 to 6, wherein the initial message further comprises an indication of a channel for the ranging signal to be broadcast by the initiating UE.

[0114] 8. Any of the methods of clauses 1 to 7, wherein the initial message does not include timing information for the ranging session.

[0115] 9. The step of performing a ranging session comprises: receiving an initial response message from each of the one or more responding UEs based on the determined timing instance; broadcasting a ranging signal; receiving a response ranging signal broadcast by each of one or more responding UEs; transmitting a post-ranging signaling message to each of the one or more responding UEs based on the determined timing instance; receiving a response post-ranging signaling message from each of the one or more responding UEs based on the determined timing instance; and determining a distance to each of the one or more responding UEs.

[0116] 10. The method of clause 9, wherein the post-ranging signal message comprises a time of departure of the ranging signal and a time of arrival of the reply ranging signal received from each of the one or more responding UEs, the reply post-ranging signal message from each of the one or more responding UEs comprises a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and the step of determining a distance to each of the one or more responding UEs uses the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the reply post-ranging signal message.

[0117] 11. The method of any of clauses 1 to 10, further comprising receiving a capability message from each of one or more responding UEs before sending the initial message, each capability message comprising the identity of the responding UE.

[0118] 12. The method of clause 11, wherein each capability message further comprises an indication that the responding UE is capable of determining a timing instance for messages in the ranging session based on the identity of the initiating UE and the identity of each of the one or more responding UEs.

[0119] 13. A user equipment (UE) configured to perform a ranging session between UEs, the UE being an initiating UE in the ranging session; a wireless transceiver configured to wirelessly communicate with entities in a wireless network; at least one memory; at least one processor coupled to the wireless transceiver and the at least one memory, the at least one processor sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs; determining a timing instance for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; The UE is configured to perform a ranging session with each of the one or more responding UEs using the determined timing instances for messages in the ranging session.

[0120] 14. The UE of clause 13, wherein at least one processor is configured to determine timing instances for messages in the ranging session by being configured to use a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session.

[0121] 15. The UE of either clause 13 or 14, wherein the at least one processor is configured to determine a timing instance for messages in the ranging session further based on an order of IDs of the initiating UE and each of the one or more responding UEs.

[0122] 16. The UE of any of clauses 13 to 15, wherein timing instances for messages in a ranging session are uniquely determined.

[0123] 17. The UE of any of clauses 13 to 16, wherein the at least one processor is further configured to determine a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs.

[0124] 18. The UE of any of clauses 13 to 17, wherein the initial message further comprises an indication that a timing instance for messages in the ranging session is determined using a function that uses as input an ID of the initiating UE and an ID of each of the one or more responding UEs.

[0125] 19. The UE of any of clauses 13 to 18, wherein the initial message further comprises an indication of a channel for the ranging signal to be broadcast by the initiating UE.

[0126] 20. The UE of any of clauses 13 to 19, wherein the initial message does not include timing information for the ranging session.

[0127] 21. At least one processor: receiving an initial response message from each of the one or more responding UEs based on the determined timing instance; Broadcast a ranging signal, receiving a response ranging signal broadcast by each of the one or more responding UEs; transmitting a post-ranging signaling message to each of the one or more responding UEs based on the determined timing instance; receiving a response post-ranging signaling message from each of the one or more responding UEs based on the determined timing instance; Determine the distance to each of the one or more responding UEs 21. The UE of any of clauses 13 to 20, configured to perform a ranging session by being configured to:

[0128] 22. The UE of clause 21, wherein the post-ranging signal message comprises a time of departure of the ranging signal and a time of arrival of the reply ranging signal received from each of the one or more responding UEs, the reply post-ranging signal message from each of the one or more responding UEs comprises a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and the at least one processor is configured to determine a distance to each of the one or more responding UEs based on the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the reply post-ranging signal message.

[0129] 23. The UE of any of clauses 13 to 22, wherein the at least one processor is further configured to receive a capability message from each of the one or more responding UEs before the initial message is sent, each capability message comprising an ID of the responding UE.

[0130] 24. The UE of clause 23, wherein each capability message further comprises an indication that the responding UE is capable of determining a timing instance for messages in the ranging session based on the identity of the initiating UE and the identity of each of the one or more responding UEs.

[0131] 25. A user equipment (UE) configured to perform ranging between UEs, the UE being an initiator UE in a ranging session; means for sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and the ID of each of the one or more responding UEs; means for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; and means for performing a ranging session with each of the one or more responding UEs using the determined timing instances for messages in the ranging session.

[0132] 26. The UE of clause 25, wherein the means for determining timing instances for messages in the ranging session comprises means for using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session.

[0133] 27. The UE of either clause 25 or 26, wherein the means for determining timing instances for messages in a ranging session further uses an order of IDs of the initiating UE and each of the one or more responding UEs.

[0134] 28. A non-transitory storage medium having program code stored thereon, the program code operable to configure at least one processor in a user equipment (UE) to perform ranging between UEs, the UE being an initiating UE in a ranging session, the non-transitory storage medium comprising: program code for sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and the ID of each of the one or more responding UEs; program code for determining a timing instance for a message in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; and program code for performing a ranging session with each of one or more responding UEs using the determined timing instances for messages in the ranging session.

[0135] 29. The non-transitory storage medium of clause 28, wherein the program code for determining timing instances for messages in a ranging session comprises program code for using a multivariate deterministic function to determine timing instances for messages in a ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, wherein each of the one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session.

[0136] 30. The non-transitory storage medium of either clause 28 or 29, wherein the program code for determining timing instances for messages in a ranging session further uses an order of IDs of the initiating UE and each of the one or more responding UEs.

[0137] 31. A method for measuring distance between user equipment (UEs), performed by a responding UE, comprising: receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and each ID of one or more responding UEs; determining a timing instance for a message in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; performing a ranging session with the initiating UE using the determined timing instance for messages in the ranging session.

[0138] 32. The method of clause 31, wherein determining timing instances for messages in the ranging session comprises using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, wherein each of the initiating UE and one or more responding UEs uses a multivariate deterministic function to determine timing instances for messages in the ranging session.

[0139] 33. The method of any of clauses 31 or 32, wherein the step of determining timing instances for messages in the ranging session is further based on an order of identities of each of the initiating UE and one or more responding UEs.

[0140] 34. The method of any of clauses 31 to 33, wherein timing instances for messages in a ranging session are uniquely determined.

[0141] 35. The method of any of clauses 31 to 34, further comprising determining a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on an identity of the initiating UE and an identity of each of the one or more responding UEs.

[0142] 36. The method of any of clauses 31 to 35, wherein the initial message further comprises an indication that a timing instance for messages in the ranging session is determined using a function that uses as input the identity of the initiating UE and the identity of each of the one or more responding UEs.

[0143] 37. The method of any of clauses 31 to 36, wherein the initial message further comprises an indication of a channel for the ranging signal to be broadcast by the initiating UE.

[0144] 38. Any of the methods of clauses 31 to 37, wherein the initial message does not include timing information for the ranging session.

[0145] 39. The step of performing a ranging session comprises: sending an initial response message to the initiating UE based on the determined timing instance; receiving a ranging signal broadcast by an initiating UE; broadcasting a reply ranging signal; receiving a post-ranging signaling message from the initiating UE based on the determined timing instance; sending a response post-ranging signaling message to the initiating UE based on the determined timing instance; and determining a distance to the initiating UE.

[0146] 40. The method of clause 39, wherein the post-ranging signal message received from the initiating UE comprises a time of departure of the ranging signal and a time of arrival of the reply ranging signal, the reply post-ranging signal message sent to the initiating UE comprises a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and the step of determining a distance to the initiating UE uses the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the reply post-ranging signal message.

[0147] 41. The method of any of clauses 31 to 40, further comprising broadcasting a capability message before receiving the initial message, the capability message comprising the identity of the responding UE.

[0148] 42. The method of clause 41, wherein the capability message further comprises an indication that the responding UE is capable of determining timing instances for messages in the ranging session based on an identity of the initiating UE and an identity of each of the one or more responding UEs.

[0149] 43. A user equipment (UE) configured to perform a ranging session between UEs, the UE being a responding UE in the ranging session; a wireless transceiver configured to wirelessly communicate with entities in a wireless network; at least one memory; at least one processor coupled to the wireless transceiver and the at least one memory, the at least one processor receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of one or more responding UEs; determining a timing instance for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; The UE is configured to perform a ranging session with the initiating UE using the determined timing instance for messages in the ranging session.

[0150] 44. The UE of clause 43, wherein at least one processor is configured to determine timing instances for messages in the ranging session by being configured to use a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the initiating UE and one or more responding UEs uses a multivariate deterministic function to determine timing instances for messages in the ranging session.

[0151] 45. The UE of either clause 43 or 44, wherein the at least one processor is configured to determine timing instances for messages in the ranging session further based on an order of IDs of the initiating UE and each of the one or more responding UEs.

[0152] 46. ​​A UE according to any of clauses 43 to 45, wherein timing instances for messages in a ranging session are uniquely determined.

[0153] 47. The UE of any of clauses 43 to 46, wherein the at least one processor is further configured to determine a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs.

[0154] 48. The UE of any of clauses 43 to 47, wherein the initial message further comprises an indication that a timing instance for messages in the ranging session is determined using a function that uses as input an ID of the initiating UE and an ID of each of the one or more responding UEs.

[0155] 49. The UE of any of clauses 43 to 48, wherein the initial message further comprises an indication of a channel for the ranging signal to be broadcast by the initiating UE.

[0156] 50. The UE of any of clauses 43 to 49, wherein the initial message does not include timing information for the ranging session.

[0157] 51. At least one processor: Sending an initial response message to the initiating UE based on the determined timing instance; receiving a ranging signal broadcast by the initiating UE; broadcast a response ranging signal; receiving a post-ranging signaling message from the initiator UE based on the determined timing instance; transmitting a response post-ranging signaling message to the initiating UE based on the determined timing instance; Determine distance to initiating UE 51. The UE of any of clauses 43 to 50, configured to perform a ranging session by being configured to:

[0158] 52. The UE of clause 51, wherein a post-ranging signal message received from the initiating UE comprises a time of departure of the ranging signal and a time of arrival of the reply ranging signal, and wherein a reply post-ranging signal message sent to the initiating UE comprises a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and wherein at least one processor is configured to determine a distance to the initiating UE based on the time of departure and time of arrival of the ranging signal and the time of arrival and time of departure of the reply post-ranging signal message.

[0159] 53. The UE of any of clauses 43 to 52, wherein the at least one processor is further configured to broadcast a capability message before receiving the initial message, the capability message comprising an identity of the responding UE.

[0160] 54. The UE of clause 53, wherein the capability message further comprises an indication that the responding UE is capable of determining timing instances for messages in the ranging session based on an identity of the initiating UE and an identity of each of the one or more responding UEs.

[0161] 55. A user equipment (UE) configured to perform a ranging session between UEs, the UE being a responding UE in the ranging session; means for receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and each ID of one or more responding UEs; means for determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; and means for performing a ranging session with an initiating UE using the determined timing instance for messages in the ranging session.

[0162] 56. The UE of clause 55, wherein the means for determining timing instances for messages in the ranging session comprises means for using a multivariate deterministic function to determine timing instances for messages in the ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the initiating UE and one or more responding UEs uses the multivariate deterministic function to determine timing instances for messages in the ranging session.

[0163] 57. The UE of either clause 55 or 56, wherein the means for determining timing instances for messages in a ranging session further uses an order of IDs of the initiating UE and each of the one or more responding UEs.

[0164] 58. A non-transitory storage medium having program code stored thereon, the program code operable to configure at least one processor in a user equipment (UE) to conduct a ranging session between the UEs, the UE being a responding UE in the ranging session, the non-transitory storage medium comprising: program code for receiving an initial message from an initiating UE to start a ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of one or more responding UEs; program code for determining a timing instance for a message in the ranging session from the initiating UE and each of the one or more responding UEs based on an ID of the initiating UE and an ID of each of the one or more responding UEs; and program code for performing a ranging session with an initiating UE using the determined timing instances for messages in the ranging session.

[0165] 59. The non-transitory storage medium of clause 58, wherein the program code for determining timing instances for messages in a ranging session comprises program code for using a multivariate deterministic function to determine timing instances for messages in a ranging session based on an ID of the initiating UE and an ID of each of one or more responding UEs, and wherein each of the initiating UE and one or more responding UEs uses a multivariate deterministic function to determine timing instances for messages in the ranging session.

[0166] 60. The non-transitory storage medium of either clause 58 or 59, wherein the program code for determining timing instances for messages in a ranging session further uses an order of IDs of each of the initiating UE and one or more responding UEs.

[0167] It is therefore intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter may include all embodiments falling within the scope of the appended claims and equivalents thereof. [Explanation of symbols]

[0168] 100 Wireless Communication System 102 vehicles, V-UE 103 V2V communication link 104 vehicles, V-UE 107 V2I communication links 109 V2I communication links 110 RSU 112 UE 113 V2V communication link 114 Pedestrians 115 V2V communication link 117 V2I communication link 202 Ability Message 204 Ranging Sessions 206 pre-PRS messages 208 PRS signal 210 post-PRS messages 302 UE ID Vector 304 Broadcast Time Instance 306 PRS ID 308 Broadcast Timing 310 Broadcast Time Instance 500 UE 502 processor 504 memory 505 Vehicle Interface 506 Connection 507 IMU 508 Program Code 509 SPS receiver, antenna 510 WWAN transceiver 511 Transmitter 512 receiver 514 WLAN transceiver 515 Transmitter 516 Receiver 520 Medium 522 pre-PRS module 524 Timing Decision Module 526 PRS module 528 post-PRS message module 530 Ranging Module 532 Ability Module

Claims

1. 1. A method for measuring distance between user equipments (UEs), performed by an initiator UE, comprising: sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs, and the initial message does not include timing information for the ranging session; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs using a multivariate deterministic function; performing the ranging session with each of the one or more responding UEs using the determined timing instances for the messages in the ranging session.

2. The method described in claim 1, wherein each of the one or more responding UEs uses the multivariate deterministic function to determine the timing instance for the message in the ranging session, and the timing instance for the message in the ranging session is uniquely determined.

3. 2. The method of claim 1, wherein determining the timing instance for the messages in the ranging session is further based on an order of the IDs of the initiating UE and each of the one or more responding UEs.

4. 10. The method of claim 1, further comprising: determining a ranging signal identifier in the ranging session for the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs.

5. 2. The method of claim 1, wherein the initial message further comprises an indication that the timing instance for the messages in the ranging session is determined using a function that uses the ID of the initiating UE and the ID of each of the one or more responding UEs as inputs.

6. The method of claim 1 , wherein the initial message further comprises an indication of a channel for a ranging signal to be broadcast by the initiating UE.

7. performing the ranging session, receiving an initial response message from each of the one or more responding UEs based on the determined timing instance; broadcasting a ranging signal; receiving a response ranging signal broadcast by each of the one or more responding UEs; transmitting a post-ranging signaling message to each of the one or more responding UEs based on the determined timing instance; receiving a response post-ranging signaling message from each of the one or more responding UEs based on the determined timing instance; and determining a distance to each of the one or more responding UEs.

8. 8. The method of claim 7, wherein the post-ranging signal message comprises a time of departure of the ranging signal and a time of arrival of the reply ranging signal received from each of the one or more responding UEs, the reply post-ranging signal message from each of the one or more responding UEs comprises a time of arrival of the ranging signal and a time of departure of the reply ranging signal broadcast by each of the one or more responding UEs, and determining the distance to each of the one or more responding UEs uses the time of departure and the time of arrival of the ranging signal and the time of arrival and the time of departure of the reply post-ranging signal message.

9. 2. The method of claim 1, further comprising receiving a capability message from each of the one or more responding UEs before sending the initial message, each capability message comprising an ID of the responding UE.

10. a user equipment (UE) configured to perform a ranging session between UEs, the UE being an initiator UE in the ranging session; a wireless transceiver configured to wirelessly communicate with entities in a wireless network; at least one memory; at least one processor coupled to the wireless transceiver and the at least one memory, the at least one processor comprising: sending an initial message to one or more responding UEs to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and an ID of each of the one or more responding UEs, the initial message not including timing information for the ranging session; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs using a multivariate deterministic function based on the ID of the initiating UE and the ID of each of the one or more responding UEs; and performing the ranging session with each of the one or more responding UEs using the determined timing instances for the messages in the ranging session.

11. The UE of claim 10, wherein the at least one processor is further configured to perform the method of any one of claims 2 to 9.

12. 1. A method for measuring distance between user equipment (UE), performed by a responding UE, comprising: receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and each ID of one or more responding UEs, and the initial message not including timing information for the ranging session; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs based on the ID of the initiating UE and the ID of each of the one or more responding UEs using a multivariate deterministic function; performing the ranging session with the initiating UE using the determined timing instances for the messages in the ranging session.

13. a user equipment (UE) configured to perform a ranging session between the UEs, the UE being a responding UE in the ranging session; a wireless transceiver configured to wirelessly communicate with entities in a wireless network; at least one memory; at least one processor coupled to the wireless transceiver and the at least one memory, the at least one processor comprising: receiving an initial message from an initiating UE to initiate a ranging session, the initial message comprising an identifier (ID) of the initiating UE and each ID of one or more responding UEs, the initial message not including timing information for the ranging session; determining timing instances for messages in the ranging session from the initiating UE and each of the one or more responding UEs using a multivariate deterministic function based on the ID of the initiating UE and the ID of each of the one or more responding UEs; performing the ranging session with the initiating UE using the determined timing instances for the messages in the ranging session; and The UE is configured to:

14. A non-transitory storage medium containing program code, the program code being stored on the non-transitory storage medium, the program code being operable to configure at least one processor in a user equipment (UE) to perform the method of any one of claims 1 to 9. Non-transitory storage medium.

15. A non-transitory storage medium containing program code, the program code stored on the non-transitory storage medium, the program code operable to configure at least one processor in user equipment (UE) to perform the method of claim 12. Non-transitory storage medium.

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