Positioning reference signal adaptation in distributed ranging systems

Abstract

Multiple user equipments (UEs) may initiate independent ranging sessions at approximately the same time and location and may interfere with each other. A UE receiving multiple initial messages for ranging determines whether there is a time separation between the ranging sessions. The UE may further determine whether there is a geographic separation between the ranging sessions, for example, whether the initiating UEs are separated. If there is no separation, the UE separates available ranging signal characteristics, such as frequency bandwidth, timing instance, and identifier, and communicates a different set of ranging signal characteristics to each initiating UE. Multiple ranging sessions may be conducted using different sets of ranging signal characteristics without much risk of interference.

Description

[Technical Field]

[0001] Priority claims

[0001] This application claims priority to U.S. Non-provisional Application No. 17 / 161,343, entitled "POSITIONING REFERENCE SIGNAL ADAPTATION DISTRIBUTED RANGING SYSTEM," filed January 28, 2021, the entire contents of which are incorporated herein by reference.

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

[0003]

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

[0004]

[0004] A common means for determining the location of a device is to use a satellite positioning system (SPS), such as the well-known Global Positioning Satellite (GPS) system or Global Navigation Satellite System (GNSS), which employs several satellites in orbit around the Earth. However, in some scenarios, for example, during adverse weather conditions or in areas with poor satellite signal reception, such as tunnels or parking complexes, location determination signals from the SPS may be unreliable or unavailable. Furthermore, position information generated using an SPS is prone to inaccuracy. 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, for example, via infrastructure components such as roadside units (RSUs). For vehicle safety applications, both positioning and ranging are important. For example, vehicle user equipment (UE) can perform positioning and ranging using sidelink signaling, e.g., broadcasting ranging signals for other vehicle UEs or pedestrian UEs to determine the relative location of transmitters. Accurate and timely knowledge of the relative location or range of nearby vehicles enables automated vehicles to safely operate and negotiate traffic conditions. For example, round-trip time (RTT) is a commonly used technique for determining the range between transmitters. RTT is a two-way messaging technique in which the time between sending a signal from a first device and receiving an acknowledgment from a second device (minus processing delay) corresponds to the distance (range) between the two devices. When multiple nearby UEs are attempting to conduct independent positioning sessions at the same time, interference can occur. Therefore, improvements to reduce the potential interference between separate positioning sessions are desirable. Summary of the Invention

[0006]

[0006] Multiple user equipments (UEs) may initiate independent ranging sessions at approximately the same time and location and may interfere with each other. A UE receiving multiple initial messages for ranging determines whether there is temporal separation between the ranging sessions. The UE may further determine whether there is geographic separation between the ranging sessions, for example, whether the initiating UEs are separated. If there is no separation, the UE separates available ranging signal properties, such as frequency bandwidth, timing instance, and identifier, and communicates a different set of ranging signal properties to each initiating UE. Multiple ranging sessions can be conducted using different sets of ranging signal properties without much risk of interference.

[0007] In one implementation, a method of ranging between user equipment (UE) performed by a receiving UE includes receiving a first initial message from a first UE to initiate a first ranging session, receiving a second initial message from a second UE to initiate a second ranging session, determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold, separating available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different, transmitting a first response message to the first UE comprising the first set of ranging signal characteristics and a second response message to the second UE comprising the second set of ranging signal characteristics. transmitting a ranging message to the second UE; conducting a first ranging session with the first UE using a first set of ranging signal characteristics; and conducting a second ranging session with the second UE using a second set of ranging signal characteristics.

[0008] In one implementation, a user equipment (UE) is configured for UE-to-UE ranging, 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, wherein the at least one processor is configured to: receive a first initial message from a first UE to initiate a first ranging session; receive a second initial message from a second UE to initiate a second ranging session; and determine whether a time separation between the first ranging session and the second ranging session is a predetermined time. the first response message to the first UE, the first response message comprising the first set of ranging signal characteristics, and the second response message to the second UE, the second response message comprising the second set of ranging signal characteristics, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; and conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics.

[0009]

[0009] In one implementation, a user equipment (UE) configured for ranging between UEs includes: means for receiving a first initial message from a first UE to initiate a first ranging session; means for receiving a second initial message from a second UE to initiate a second ranging session; means for determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold; means for separating available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session; means for transmitting a first response message to the first UE comprising the first set of ranging signal characteristics and a second response message to the second UE comprising the second set of ranging signal characteristics, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; and means for conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics.

[0010]

[0010] In one implementation, a non-transitory storage medium including program code stored thereon, the program code operable to configure at least one processor in a user equipment (UE) for ranging between UEs, the program code including: program code for receiving a first initial message from a first UE to initiate a first ranging session; program code for receiving a second initial message from a second UE to initiate a second ranging session; program code for determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold; and program code for determining available ranging signal characteristics. The ranging session includes program code for separating ranging signal characteristics into a first set for a first ranging session and a second set for a second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; program code for transmitting a first response message to the first UE, the first response message comprising the first set of ranging signal characteristics, and transmitting a second response message to the second UE, the second response message comprising the second set of ranging signal characteristics; and program code for conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics.

[0011]

[0011] In one implementation, a method of ranging between UEs performed by an initiating user equipment (UE) includes sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session, receiving a response message from the first UE comprising a set of ranging signal characteristics to be used during the first ranging session that are different from the ranging signal characteristics indicated in the first initial message, and conducting the first ranging session with the first UE using the set of ranging signal characteristics.

[0012]

[0012] In one implementation, a user equipment (UE) is configured for ranging between UEs, the UE including 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, wherein the at least one processor is configured to: send a first initial message to a first UE to initiate a first ranging session; receive a response message from the first UE including a set of ranging signal characteristics to be used during the first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session, the set of ranging signal characteristics being different from the ranging signal characteristics indicated in the first initial message; and conduct the first ranging session with the first UE using the set of ranging signal characteristics.

[0013]

[0013] In one implementation, a user equipment (UE) is configured for ranging between UEs, and the UE includes: means for sending a first initial message to a first UE to initiate a first ranging session; means for receiving a response message from the first UE, the response message including a set of ranging signal characteristics to be used during the first ranging session, the set of ranging signal characteristics being different from the ranging signal characteristics indicated in the first initial message, the first initial message indicating ranging signal characteristics for the first ranging session; and means for conducting the first ranging session with the first UE using the set of ranging signal characteristics.

[0014]

[0014] In one implementation, 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) for ranging between UEs, the program code including: program code for sending a first initial message to a first UE to initiate a first ranging session; program code for receiving from the first UE a response message comprising a set of ranging signal characteristics to be used during the first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session, different from the ranging signal characteristics indicated in the first initial message; and program code for conducting the first ranging session with the first UE using the set of ranging signal characteristics.

[0015]

[0015] 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 figures unless otherwise specified. [Brief explanation of the drawings]

[0016] [Figure 1]

[0016] FIG. 1 illustrates a wireless communication system showing distributed UE communications, including ranging signaling to support multiple ranging sessions. [Figure 2]

[0017] 1 illustrates a ranging session involving four UEs using different types of Listen Before Transmit (LBT) types. [Figure 3] 1 illustrates a ranging session involving four UEs using different types of listen-before-transmit (LBT) types. [Figure 4]

[0018] 1 illustrates several UEs involved in separate ranging sessions separated in time. [Figure 5]

[0019] 1 illustrates several UEs involved in separate ranging sessions that are not separated in time and that use different sets of ranging signal parameters for each ranging session. [Figure 6]

[0020] 1 illustrates an example of a signaling flow for multiple ranging procedures in which different sets of ranging signal parameters are used for a ranging session. [Figure 7]

[0021] 1 is a schematic block diagram illustrating some example features of a UE configured for multiple ranging sessions in which different sets of ranging signal parameters are used. [Figure 8]

[0022] 10 is a flowchart illustrating a method of ranging between UEs performed by a receiving UE in a ranging session.

[0017]

[0023] [Figure 9] 10 is a flowchart illustrating a method for ranging between UEs performed by an initiating UE in a ranging session. DETAILED DESCRIPTION OF THE INVENTION

[0018]

[0024] A distributed approach may be used for ranging and positioning of vehicles, roadside units (RSUs), and pedestrians, avoiding 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 be, for example, directly between vehicles or between vehicles and RSUs or pedestrians. These communications may include messages and information elements (IEs) that vehicles can use to provide information needed for autonomous driving.

[0019]

[0025] For example, for safe operation of an autonomous vehicle, the relative location or range to other vehicles needs to be determined. Various techniques may be used to derive the relative position between vehicles. For example, the relative position 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 as PRS signals herein. PRS signals may be broadcast, for example, by a user equipment (UE) in a vehicle, sometimes referred to as a V-UE, and received by other V-UEs and / or infrastructure, e.g., an RSU, or a UE carried by a pedestrian, using direct communication systems such as dedicated short-range communications (DSRC), cellular vehicle-to-everything (C-V2X) communications, or even 5G new radio (NR) communications. PRS signals may be used to determine the range 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]

[0026] In a distributed system, individual UEs can range with respect 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 signal messages (pre-PRS messages) to request and accept a ranging session is transmitted and received, followed by broadcasting ranging signals (PRS signals) for measurements, followed by a set of post-ranging signal messages (post-PRS messages) that exchange measurement payloads. In RTT-based ranging and positioning, for example, measurements of the time of arrival (TOA) and time of departure (TOD) of the transmitted and received PRS signals are provided in the post-PRS messages and can be used by each pair of UEs to determine the range between them. Pre-PRS and post-PRS messages may be sent over licensed spectrum to ensure reliability, while PRS signals may be broadcast over unlicensed spectrum (e.g., to take advantage of the greater available bandwidth in the UNI-III spectrum, for example).

[0021]

[0027] Although the distributed mechanism ensures minimal overhead, multiple nearby UEs may initiate separate ranging sessions independently of each other. For example, without overhead communication to control the ranging sessions, two UEs may separately broadcast their own pre-PRS signals to the same set of responding UEs, resulting in two independent ranging sessions involving the same responding UE and occurring simultaneously. In dynamic areas, pre-optimization of ranging sessions is not feasible, and therefore ranging sessions are treated separately. Two nearby ranging sessions may interfere with each other, for example, in frequency or in each other's listen-before-transmit (LBT) procedures, or with each other's post-PRS measurement observations. If interference occurs, the accuracy of the RTT-based ranging session may be significantly reduced.

[0022]

[0028] To reduce the likelihood of interference between multiple ranging sessions, a UE that receives requests to initiate ranging sessions from multiple UEs, for example, within a threshold time threshold or distance threshold, may divide available ranging signal characteristics by the number of all initiating UEs. The available ranging signal characteristics may include, for example, one or more of a frequency bandwidth, a PRS timing instance, and a PRS identifier, or a combination thereof. The receiving UE may accept the ranging session and respond to each initiating UE by providing an assigned portion of the ranging signal characteristics to each respective initiating UE.

[0023]

[0029] By splitting ranging signal characteristics among initiating UEs, separate ranging sessions can be conducted with little likelihood of interference between them. Advantageously, in the process of splitting ranging signal characteristics among initiating UEs, existing ranging procedures, such as distributed RTT-based positioning, can minimize or eliminate interference without requiring additional signaling overhead and will have improved LBT efficiency when the LBT is channel-specific, which will improve ranging / positioning accuracy due to reduced inter-PRS time. Furthermore, the process can be employed only when interference is likely to occur, for example, when the initiation messages are close in time or the initiating vehicles are close in space.

[0024]

[0030] 1 illustrates a wireless communication system 100 illustrating distributed communications, including ranging signaling to support multiple ranging sessions and / or positioning, as described herein. The wireless communication system 100 illustrates a first vehicle 102, e.g., V-UE 102, having a first wireless device in wireless communication 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 subsystem thereof, 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]

[0031] The wireless communication system 100 may use, for example, a vehicle-to-everything (V2X) communication standard in which information is passed between vehicles and other entities within a 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, passing speeds, and, as described herein, assist with parking. Low-latency communications are used in V2X and are therefore suitable for precise relative positioning using ranging signals, such as one-way ranging, RTT, and TDOA.

[0026]

[0032] 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 is sometimes referred to as sidelink communication, when the V2X entities are V2X entities. 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]

[0033] The wireless communication system 100 may operate using direct or indirect wireless communication between the UE 102 and the UE 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 TS23.303, using wireless communications under IEEE 1609, Wireless Access in Vehicular Environment (WAVE), Intelligent Transportation Systems (ITS), and IEEE 802.11p over the 5.9 GHz ITS band, or using other wireless connections directly between the entities. Thus, as shown, the UE 102 and the UE 104 may communicate directly using a vehicle-to-vehicle (V2V) communication link 103. The UE 102 and the UE 104 may also communicate directly with a roadside 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 RSU 110 may include a backhaul connection to the network, as shown by the wired connection 111, but may also be via a wireless Uu interface to the base station. The RSU 110 may be used for ranging with the UE 102, 104, or other UEs, and because the location of the RSU 110 may be precisely known, the RSU 110 may be used as an anchor UE, from which the location of the UE 102, 104, or other UEs may be determined. The RSU 110 may be referred to herein as a UE 110. The UEs 102, 104 and UE 110 may use direct communication links to communicate with additional entities, such as additional vehicles, RSUs, or with a UE 112 carried by a pedestrian 114.For example, UE 102 may communicate with UE 112 via V2V communication link 113, UE 104 may communicate with UE 112 via V2V communication link 115, and UE 110 may communicate with UE 112 via V2I communication link 117.

[0028]

[0034] During direct communication with one or more entities in the V2X wireless communication system 100, each entity may provide V2X information, such as an identifier for the V2X entity, 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 use cases.

[0029]

[0035] In other implementations, the UE 102 and the UE 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-anything (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 an NR Node B (gNB) in fifth-generation (5G) wireless access.

[0030]

[0036] The UEs 102 and 104 may initiate and conduct ranging / positioning sessions, including sending pre-PRS messages, broadcasting PRS, and sending post-PRS messages over links 103, 107, 109, 113, or 115, by which the range or relative position between the UEs 102 and 104 may be determined. The PRS broadcast by the UEs 102 and 104 may be a signal suitable for ranging, for example, as 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 employed.

[0031]

[0037] If UEs 102 and 104 broadcast a PRS in V2V link 103, the range or relative position between UE 102 and UE 104 can be determined directly. If UEs 102 and 104 broadcast a PRS in V2I links 107 and 109 or via links 113 and 115, the range or relative position between UE 102 and UE 110 or UE 112, and between UE 104 and UE 110 or UE 112, can be determined directly.

[0032]

[0038] Direct wireless communication between the UEs 102, 104, 110, and 112 does not require any network infrastructure and allows for low-latency communication, which is advantageous for precise ranging or positioning. Thus, such direct wireless communication may be desirable for ranging over short distances, for example, with nearby vehicles or infrastructure.

[0033]

[0039] A UE, for example, any of the V-UE 102, V-UE 104, RSU 110, and UE 112 shown in FIG. 1, may be configured to perform ranging and / or positioning operations, such as RTT-based ranging. During RTT-based ranging, several messages are sent between an initiating UE and a receiving UE, including a pre-PRS message to request and accept a ranging session, a PRS signal for measurements, and a post-PRS message to exchange measurement payloads. The initiating UE sends a pre-PRS message to request a ranging session with another UE. The pre-PRS message may indicate ranging signal characteristics to be used in the ranging session, such as PRS resources including frequency and timing instances and a PRS identifier (ID). The receiving UE responds to the pre-PRS message from the initiating UE, for example, indicating that the receiving UE accepts the request for the ranging session. The pre-PRS message may be transmitted over a licensed spectrum to ensure reliability.

[0034]

[0040] An initiating UE broadcasts a PRS signal, and in response, receiving UEs broadcast their own PRS signals. 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. In some implementations, the angle of departure (AoD) and angle of arrival (AoA) of the broadcasted and received PRS signals may also be measured. The PRS signal may be a signal suitable for ranging, for example, as 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. The PRS signal may be broadcast on an unlicensed spectrum to use a wide frequency band. For example, in some implementations, the PRS may be broadcast on 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. When broadcasting PRS signals over unlicensed spectrum, LBT constraints may be employed.

[0035]

[0041] The initiating UE and receiving UE exchange Post-PRS messages, each indicating the ToD (and AoD, if measured) of its broadcasted PRS and the measured ToA (and Angle of Arrival (AoA), if measured) for the received PRS signal. The Post-PRS messages may be transmitted over licensed spectrum to ensure reliability.

[0036]

[0042] Both the initiating UE and the receiving UE may determine the range between them based on the ToD and ToA of the broadcasted PRS signal. i ToD for traffic lights i and ToA i(where i=1 for the PRS broadcast by the initiating UE and i=2 for the PRS broadcast by the receiving UE), the RTT between the initiating UE and the receiving UE can be determined as the difference between ToD1 and ToA2 - the difference between ToA1 and ToD2. The RTT value is the round trip time for the signal, so the range (distance) between the initiating UE and the receiving UE can be determined as RTT / 2c, where c is the speed of light.

[0037]

[0043] If the locations of one or more UEs are known, the range between the initiating UE and the receiving UE can be used together with the known location of one of the UEs to determine the location of the other UE, and thus the ranging session can be a positioning session. The location of the UE can 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 can be used to determine the locations of the remaining UEs. Angle measurements can be used, for example, to assist in positioning. As an example, the relative locations of the two UEs can be determined based on the range between the two UEs and the measured AoA. Once the relative locations of the UEs are determined, if the actual location of one of the UEs is known (which can be provided, for example, in a pre-PRS message or a post-PRS message), the actual location of the other UE can be determined. For example, if the locations of two UEs are known by a third UE, the range between the third UE and each of the other two UEs will result in 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 insufficient or incorrect. 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 the received signal at different antenna elements of the antenna array and the known orientation of the UE (e.g., determined by a magnetometer). Furthermore, geographic constraints can be used to assist positioning, for example, by constraining the possible locations of a vehicle-based UE to locations accessible to the vehicle, such as roads.

[0038]

[0044] 2 and 3 show ranging sessions 200 and 300 involving four UEs in which pre-PRS, PRS, and post-PRS signals are exchanged. In both ranging sessions 200 / 300, a first pre-PRS signal 202 / 302, a first PRS signal 212 / 312, and a first post-PRS signal 222 / 322 are sent by an initiating UE, and the remaining pre-PRS, PRS, and post-PRS signals are sent by receiving UEs.

[0039]

[0045] Ranging sessions 200 and 300 illustrate different types of LBT that may be employed, for example, during broadcast of PRS signals. Ranging session 200 illustrates, for example, Category 4 LBT, and ranging session 300 illustrates, for example, Category 2 LBT. With Category 2 LBT, the duration for which the channel is sensed as idle before the transmitting UE transmits is deterministic. In contrast, Category 4 LBT uses random backoff with a variable-sized contention window, and the transmitting UE draws a random number N within the contention window. The minimum and maximum values ​​of N specify the size of the contention window. The random number N is used in the LBT procedure to determine the duration for which the channel is sensed as idle before the transmitting UE transmits on the channel. As illustrated by the inter-PRS signal intervals in ranging sessions 200 and 300, respectively, Category 4 LBT generally takes longer than Category 2 LBT. In one implementation, the initiating UE may receive time slots for other UEs so that the others may perform Category 2 LBT.

[0040]

[0046] In a distributed system, two UEs may separately initiate independent ranging sessions at approximately the same time and location. For example, two initiating UEs may each initiate a ranging session by sending a separate pre-PRS message to the same receiving UE. If the ranging sessions are close in time, acceptance of both ranging sessions by the receiving UE may result in interference. For example, the PRS signals in the separate ranging sessions may have overlapping frequencies, and thus the ranging sessions may interfere in frequency. Furthermore, the PRS signals may be transmitted using unlicensed spectrum, and an LBT procedure may be used. If the PRS signals for the ranging sessions are transmitted at approximately the same time, the PRS transmission of one ranging session may interfere with the LBT procedure in the other ranging session, which may increase latency and reduce the accuracy of the ranging measurements.

[0041]

[0047] To reduce the likelihood of interference between multiple ranging sessions, a receiving UE that receives requests to initiate ranging sessions from multiple UEs, e.g., within a threshold time threshold or distance threshold, may divide the available ranging signal characteristics for the PRS signal, e.g., frequency bandwidth, PRS timing instance, and PRS identifier, or a combination thereof, by the number of all initiating UEs. Each initiating UE may be assigned a different portion of the ranging signal characteristics such that the ranging sessions are constructed disjointly, e.g., such that the ranging sessions do not have common PRS characteristics.

[0042]

[0048] 4 illustrates two ranging sessions 400, e.g., several UEs involved in RTT-based ranging, that are separated in time. In FIG. 4, initiating UE1 initiates a first ranging session with nearby receiving UEs, namely, UE-A, UE-B, UE-C, and UE-X, and initiating UE2 initiates a second ranging session with nearby receiving UEs, namely, UE-A, UE-B, UE-C, and UE-Y. Thus, receiving UEs UE-A, UE-B, and UE-C receive pre-PRS messages from both initiating UE1 and initiating UE2, while UE-X receives pre-PRS messages only from initiating UE1 and UE-Y receives pre-PRS messages only from initiating UE2.

[0043]

[0049] Upon receiving pre-PRS messages from both initiating UE1 and initiating UE2, each receiving UE may determine whether the separate ranging sessions may overlap, for example, by determining whether the pre-PRS messages were received within a time threshold, for example, less than one second, of each other. If the pre-PRS messages are not within the time threshold, for example, if the pre-PRS messages are received more than one second apart, the ranging sessions initiated by initiating UE1 and initiating UE2 are considered to be time-separated, and the receiving UE may respond with a pre-PRS message to each initiating UE to accept the ranging session initiated by one UE without considering the other ranging session initiated by the other UE. For example, receiving UE-A may respond with a pre-PRS message to initiating UE1 and a pre-PRS message to initiating UE2 and accept the separate ranging sessions without considering whether the separate ranging sessions may have the same ranging signal characteristics for the PRS signal.

[0044]

[0050] Thus, the first ranging session 402 initiated by UE1 can be accepted by UE-A without considering the ranging signal characteristics assigned to the second ranging session 404 initiated by UE2, and vice versa. As a result, as shown by the ellipses with the same shading in FIG. 4, the PRS signals broadcast by UE1 in the first ranging session 402 and the PRS signals broadcast by UE2 in the second ranging session 404 can have one or more ranging signal characteristics that are the same, but are transmitted at separate times. Because the first ranging session 402 and the second ranging session 404 are separated in time, there is little risk of interference.

[0045]

[0051] Each of the receiving UEs UE-A, UE-B, and UE-C may separately consider whether the pre-PRS messages received from both initiating UE1 and initiating UE2 are outside the time threshold and can be considered to be time-separated.

[0046]

[0052] FIG. 5 illustrates two ranging sessions 500 similar to FIG. 4, with similar designated elements being the same, but not separated in time, eg, RTT-based ranging.

[0047]

[0053] As described above, upon receiving pre-PRS messages from both initiating UE1 and initiating UE2, each receiving UE may determine whether separate ranging sessions may overlap, for example, by determining whether the time instances of the pre-PRS messages were received within a time threshold, e.g., less than one second, of each other. If the pre-PRS messages are within the time threshold, e.g., if the pre-PRS messages were received within one second of each other, the ranging sessions initiated by initiating UE1 and initiating UE2 are considered not time-separated. Thus, the receiving UE may respond with a pre-PRS message to each initiating UE to accept the ranging session, but the receiving UE may consider ranging signal characteristics for the PRS signals in the other ranging sessions. For example, the receiving UE would determine whether ranging signal characteristics for the ranging sessions overlap and would divide the ranging signal characteristics between the ranging sessions. Thus, for example, receiving UE-A may examine all available PRS bandwidth and divide the available PRS bandwidth by the number of all initiating UEs. As an example, if the available PRS bandwidth is 80 MHz, receiving UE-A would divide the available PRS bandwidth by the number of initiating UEs, in this case 2, resulting in 40 MHz. Receiving UE-A would also ensure that the PRS timing instance and PRS ID are not shared by the two ranging sessions. Receiving UE-A may respond with a pre-PRS message to initiating UE1, providing a set of ranging signal characteristics assigned to initiating UE1, and may respond with a pre-PRS message to initiating UE2, providing a different set of ranging signal characteristics assigned to initiating UE2.

[0048]

[0054] 5, a first ranging session 502 initiated by UE1 and a second ranging session 504 initiated by UE2 may both be accepted by UE-A, but with different sets of ranging signal characteristics, as indicated by the differently shaded ellipses in FIG. 5. Thus, the PRS signals in the first ranging session 502 and the second ranging session 504 may be broadcast by UE1 and UE2, respectively, at approximately the same time, but with different ranging signal characteristics. Because the PRS signals in the first ranging session 502 and the second ranging session 504 have different ranging signal characteristics, there is little risk of interference even if they are not time-separated.

[0049]

[0055] In one implementation, the receiving UE may further determine whether the separate ranging sessions initiated by UE1 and UE2 overlap based on distance, for example, whether initiating UE1 and initiating UE2 are geometrically separated. Geometric separation of initiating UEs is important because LBT efficiency is affected when UEs are close to each other. For example, a receiving UE may be involved in two ranging sessions with little geometric separation if the initiating UEs simultaneously initiate LBT for their own sessions. In an overlapping area, the receiving UE would need to perform LBT for both PRS transmissions, which is inefficient. Therefore, the receiving UE may consider both whether the initiating UEs are geometrically separated and whether the pre-PRS messages received from the initiating UEs are time-separated. In some implementations, the receiving UE may treat geometric separation and time separation as a logical OR function or a logical AND function. For example, in some implementations, if there is no geometric or time separation, the receiving UE may accept ranging sessions by assigning each ranging session a different set of ranging signal characteristics for the PRS signals. In another implementation, the receiving UE may accept ranging sessions by assigning each ranging session a different set of ranging signal characteristics for the PRS signals only if there is no geometric or time separation.

[0050]

[0056] The receiving UE may be aware of the locations of the initiating UEs, UE1 and UE2, if the initiating UE provides their locations to the receiving UE in a pre-PRS message, for example, if V2V ranging is enabled. In this case, for example, the receiving UE may consider both whether the initiating UEs are within a distance threshold from each other, for example, whether |UE1 location - UE2 location| < a threshold (e.g., 20 meters). If the initiating UEs are not within the distance threshold from each other, for example, if the initiating UEs are more than 20 meters away, the initiating UEs may be considered to be geometrically separated. Thus, the receiving UE may respond to each initiating UE with a pre-PRS message to accept a ranging session initiated by one UE without considering other ranging sessions initiated by the other UE, for example, as described with reference to FIG. 4. In some implementations, time separation may also be considered by the receiving UE, and a ranging session may be accepted by the receiving UE without considering other ranging sessions if there is also time separation.

[0051]

[0057] On the other hand, if the initiating UEs are within a distance threshold from each other, e.g., less than 20 meters away, the initiating UEs may be considered not geometrically separated. Thus, the receiving UE may respond to each initiating UE with a pre-PRS message to accept the ranging session, but the receiving UE considers ranging signal characteristics for the PRS signals in the other ranging sessions. For example, as described with reference to FIG. 5, the receiving UE would determine whether the ranging signal characteristics for the ranging sessions overlap and would divide the ranging signal characteristics between the ranging sessions. The receiving UE may accept ranging sessions from UE1 and UE2, but with different sets of ranging signal characteristics. In some implementations, time separation may also be considered by the receiving UE. For example, if there is no time separation, the ranging sessions may be accepted by the receiving UE with different sets of ranging signal characteristics.

[0052]

[0058] Each of the receiving UEs UE-A, UE-B, and UE-C may separately consider whether the initiating UE1 and the initiating UE2 are outside a distance threshold from each other and can be considered to be geometrically separated, and / or whether the pre-PRS messages received from both the initiating UE1 and the initiating UE2 are outside a time threshold and can be considered to be time separated.

[0053]

[0059] 6 shows an example of a signaling flow 600 for multiple ranging procedures between an initiating UE1 602 and a receiving UE-A 606 and between an initiating UE2 604 and a receiving UE-A 606, in which different sets of ranging signal parameters are used for the ranging sessions, as described herein. The initiating UEs 602, 604 and the receiving UE 606 may be UE1, UE2, and UE-A, respectively, as shown in FIG. 5, and may be similar to one or more of the vehicular-based UEs (V-UEs) 102 and 104, the RSU 110, or the UE 112 described in FIG. 1. It should be understood that FIG. 6 shows signaling for multiple ranging procedures involving only one receiving UE, e.g., UE-A 606, and that there may be additional receiving UEs, which would involve additional communications similar to those shown in FIG. 6. As shown, communication between UEs 602, 604, and 606 in FIG. 6 may be direct communication between the entities and may not involve an infrastructure device, such as a base station, to forward messages between the entities.

[0054]

[0060] In stage 1A, a first initiating UE 1 602 sends a pre-PRS message to request a ranging session with a receiving UE-A 606. The pre-PRS message may be transmitted over a licensed spectrum. The pre-PRS message may indicate ranging signal characteristics to be used in the ranging session with the initiating UE 1 602, such as PRS resources including frequency and timing instances and a PRS identifier (ID). In some implementations, the pre-PRS message may further include the current location of the initiating UE 1 602.

[0055]

[0061] In phase 1B, a second, initiating UE2 604 also sends a pre-PRS message to request a ranging session with receiving UE-A 606. Similar to phase 1A, the pre-PRS message sent in phase 1B may be transmitted over a licensed spectrum and may indicate ranging signal characteristics to be used in the ranging session with initiating UE2 604, such as PRS resources including frequency and timing instances and a PRS identifier (ID). In some implementations, the pre-PRS message may further include the current location of initiating UE2 604.

[0056]

[0062] In stage 2, the receiving UE-A 606 determines whether the ranging sessions initiated by UE1 602 and UE2 604 are separated in time and / or geographically. For example, the receiving UE-A 606 determines whether the pre-PRS messages received in stages 1A and 1B were received within a time threshold, e.g., |T 1A -T 1B | <Threshold T where T 1A is the time of reception of the pre-PRS message from stage 1A, and T 1B is the time of reception of the pre-PRS message from stage 1B, and Threshold T is a predetermined time threshold, which may be 1 second or any other desired value. If location information is provided in the pre-PRS message from stages 1A and 1B, the receiving UE-A 606 determines whether the initiating UEs (UE1 602 and UE2 604) are within the distance threshold, e.g., |UE1 location - UE2 location | <Threshold D where UE1 location is the location of the starting UE1 602, UE2 location is the location of the starting UE2 604, and Threshold Dis a predetermined distance threshold, which may be 20 meters or any other desired value. In some implementations, if it is determined that the ranging session does not have sufficient time separation, the receiving UE-A 606 may determine whether there is sufficient time separation, which is determined by Threshold T A different time threshold may be used.

[0057]

[0063] In stage 3, if the ranging sessions are not deemed sufficiently time-separated and / or geographically separated as determined in stage 2, the receiving UE-A 606 may partition the available PRS resources based on the number of initiating UEs and assign a different set of PRS characteristics for the ranging sessions with each of the initiating UEs (UE1 602 and UE2 604). Partitioning the PRS resources may include, for example, partitioning the frequency bandwidth between the initiating UEs and ensuring that the PRS timing instances and PRS IDs are different for the initiating UEs. For example, if in stage 2 the receiving UE-A 606 determines that there is not enough time separation, stage 3 may be performed and the available PRS characteristics may be partitioned. If in stage 2 the receiving UE-A 606 determines that there is not enough geometric separation, stage 3 may be performed and the available PRS characteristics may be partitioned unless there is a large time separation between the ranging sessions. If in step 2, receiving UE-A 606 determines that there is sufficient time and / or geographic separation, then step 3 does not need to be performed and the ranging session for both initiating UEs (UE1 602 and UE2 604) may use all available PRS resources. The following steps assume that step 3 has been performed.

[0058]

[0064] In stage 4A, the receiving UE-A 606 sends a pre-PRS message, e.g., a pre-PRS acknowledgement, indicating that the receiving UE-A 606 accepts the request for the ranging session from the initiating UE1 602 and providing a first set of PRS resources, e.g., a frequency bandwidth, a timing instance, and a PRS ID, allocated to the initiating UE1 602 in stage 3. The pre-PRS message of stage 4A may be transmitted on a licensed spectrum. In some implementations, the pre-PRS message may further include the current location of the receiving UE-A 606.

[0059]

[0065] In stage 4B, the receiving UE-A 606 sends a pre-PRS message, e.g., a pre-PRS acknowledgement, indicating that the receiving UE-A 606 accepts the request for the ranging session from the initiating UE2 604 and providing a second set of PRS resources, e.g., a frequency bandwidth, a timing instance, and a PRS ID, assigned to the initiating UE2 604 in stage 3. The second set of PRS resources provided to the initiating UE2 604 in stage 4B is different from the first set of PRS resources provided to the initiating UE1 602 in stage 4A. The pre-PRS message of stage 4B may be transmitted on a licensed spectrum. In some implementations, the pre-PRS message may further include the current location of the receiving UE-A 606.

[0060]

[0066] In stage 5A, initiating UE 1 602 broadcasts a PRS signal using a first set of PRS resources. The PRS signal may be broadcast on an unlicensed spectrum to use a wide frequency band. Initiating UE 1 602 records the ToD, and in some implementations, the AoD, of the PRS signal, and receiving UE-A 606 records the ToA, and in some implementations, the AoA, of the PRS signal.

[0061]

[0067] In phase 5B, initiating UE2 604 broadcasts a PRS signal using a second set of PRS resources. The PRS signal may be broadcast on an unlicensed spectrum to use a wide frequency band. Initiating UE2 604 records the ToD, and in some implementations, the AoD, of the PRS signal, and receiving UE-A 606 records the ToA, and in some implementations, the AoA, of the PRS signal. Because the PRS signal broadcast in phase 5A and the PRS signal broadcast in phase 5B use different sets of PRS resources, there is little chance of interference.

[0062]

[0068] In step 6A, in response to receiving the PRS signal in step 5A, the receiving UE-A 606 broadcasts the PRS signal using a first set of PRS resources. The PRS signal may be broadcast on an unlicensed spectrum to use a wide frequency band. The receiving UE-A 606 records the ToD of the PRS signal, and in some implementations, the AoD of the PRS signal, and the initiating UE 1 602 records the ToA of the PRS signal, and in some implementations, the AoA of the PRS signal.

[0063]

[0069] In step 6B, in response to receiving the PRS signal in step 5B, the receiving UE-A 106 broadcasts the PRS signal using a second set of PRS resources. The PRS signal may be broadcast on an unlicensed spectrum to use a wide frequency band. The receiving UE-A 606 records the ToD of the PRS signal, and in some implementations, the AoD of the PRS signal, and the initiating UE2 604 records the ToA of the PRS signal, and in some implementations, the AoA of the PRS signal.

[0064]

[0070] In stage 7A, the initiating UE1 602 sends to the receiving UE-A 606 a post-PRS message indicating the ToD, and in some implementations, the AoD, of the PRS signal broadcast in stage 5A, and a post-PRS message indicating the ToA, and in some implementations, the AoA, of the PRS signal received in stage 6A.

[0065]

[0071] In stage 7B, the initiating UE2 604 sends to the receiving UE-A 606 a post-PRS message indicating the ToD, and in some implementations, the AoD, of the PRS signal broadcast in stage 5B, and a post-PRS message indicating the ToA, and in some implementations, the AoA, of the PRS signal received in stage 6B.

[0066]

[0072] In step 8A, the receiving UE-A 606 sends to the initiating UE1 602 a post-PRS message indicating the ToA, and in some implementations, the AoA, of the PRS signal received in step 5A, and a post-PRS message indicating the ToD, and in some implementations, the AoD, of the PRS signal broadcast in step 6A.

[0067]

[0073] In step 8B, receiving UE-A 606 sends to initiating UE2 604 a post-PRS message indicating the ToA, and in some implementations, the AoA, of the PRS signal received in step 5B, and a post-PRS message indicating the ToD, and in some implementations, the AoD, of the PRS signal broadcast in step 6B.

[0068]

[0074] In step 9A, the initiating UE 1 602 may determine the range between UE 1 602 and the receiving UE-A 606 based on the ToD and ToA of the PRS signals broadcast in steps 5A and 6A. For example, the range may be determined based on the ToD and ToA of the PRS signals broadcast in steps 5A and 6A. i ToD for traffic lights i and ToA i(where i=1 for the PRS broadcast by the initiating UE1 602 and i=2 for the PRS broadcast by the receiving UE-A 606) based on

[0069]

number

[0070] can be determined as:

[0071]

[0075] If the location of receiving UE-A 606 is known, e.g., provided in a pre-PRS message in stage 4A, along with additional information such as the AoA or AoD, or location and range, of the PRS signals for other receiving UEs (not shown in FIG. 6), or geographical information such as street location, then the location of initiating UE1 602 can be determined, e.g., using multilateration and constraints according to the AoA or AoD of the PRS signals and the geographical information.

[0072]

[0076] In step 9B, initiating UE2 604 may determine the range between UE2 604 and receiving UE-A 606 based on the ToD and ToA of the PRS signals broadcast in steps 5B and 6B in a manner similar to that described in step 9A. The location of initiating UE2 604 may also be determined in a manner similar to that described in step 9A.

[0073]

[0077] In step 9C, receiving UE-A 606 may determine the range between UE-A 606 and initiating UE1 602 and the range between UE-A 606 and initiating UE2 604 based on the ToAs and ToDs of the PRS signals broadcast in steps 5A and 6A, and in steps 5B and 6B, respectively, in a manner similar to that described in steps 9A and 9B. The location of receiving UE-A 606 may also be determined in a manner similar to that described in step 9A, for example, based on the locations of initiating UE1 602 and UE2 604, if provided in steps 1A and 1B.

[0074]

[0078] FIG. 7 shows a schematic block diagram illustrating some example features of a user equipment (UE) 700, which may be a UE in one of the vehicles 102 or 104, an RSU 110, or a UE 112 carried by a pedestrian 114, as shown in FIG. 1, or any of the UEs shown in FIG. 2 or 4-6. The UE 700 may be configured to serve as a receiving UE, e.g., receiving UE-A, or an initiating UE, e.g., initiating UE-1, for multiple ranging sessions that are not separated in time or geography and where different sets of ranging signal parameters are used for the ranging sessions, as described herein. If the UE 700 is a V-UE, it may be configured to control autonomous driving of a vehicle, e.g., vehicle 102. For example, the UE 700 may include a vehicle interface 705, by means of which commands for autonomous driving can be provided to the vehicle and sensory inputs including speed and acceleration can be provided from the vehicle to the UE 700. The UE 700 may include, for example, one or more processors 702, a memory 704, an inertial measurement unit (IMU) 707, which may include, for example, an accelerometer, gyroscope, magnetometer, etc., that may be used to detect the vehicle's orientation relative to a global or local reference frame, and movement or one or more movement characteristics, a satellite positioning system (SPS) receiver 709, for example, for determining a GPS position, and external interfaces, including, for example, a wireless wide area network (WWAN) transceiver 710 and a wireless local area network (WLAN) transceiver 714, that may be operably coupled to a non-transitory computer-readable medium 720 and one or more connections 706 (e.g., buses, lines, fibers, links, etc.) to the memory 704. The UE 700 may further include additional items not shown, such as, for example, a user interface, which may include a display, a keypad such as a virtual keypad on the display, or other input device through which a user may interface with the user device. In some example implementations, all or a portion of the UE 700 may take the form of a chipset or the like.

[0075]

[0079] The transceiver 710 may be, for example, a cellular transceiver configured to transmit and receive direct communications in a wireless network, as shown in FIG. 1. The transceiver 710 may include a transmitter 711 enabled to transmit one or more signals over one or more types of wireless communication networks and a receiver 712 for receiving one or more signals transmitted over the one or more types of wireless communication networks. The transceiver 714 may be, for example, a short-range transceiver and may be configured to transmit and receive direct communications in a wireless network, as shown in FIG. 1. The transceiver 714 may include a transmitter 715 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 716 for receiving one or more signals including, for example, PRS messages, pre-PRS messages, and post-PRS messages transmitted over the one or more types of wireless communication networks. The transceivers 710 and 714 enable the UE 700 to communicate with transportation entities using a D2D communication link, such as DSRC, C-V2X, or 5G NR.

[0076]

[0080] In some embodiments, the UE 700 may include an antenna 709, which may be internal or external. The antenna 709 may be used to transmit and / or receive signals that are processed by the transceiver 710 and / or transceiver 714. In some embodiments, the antenna 709 may be coupled to the transceiver 710 and / or transceiver 714. In some embodiments, measurements of signals received (transmitted) by the UE 700 may be performed at the point of connection between the antenna 709 and the transceiver 710 and / or transceiver 714. For example, measurement reference points for measurements of received (transmitted) RF signals may be the input (output) terminals of the receivers 712, 716 (transmitters 711, 715) and the output (input) terminal of the antenna 709. In a UE 700 with multiple antennas 709 or an antenna array, the antenna connectors may be considered as virtual points representing the aggregate output (input) 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 relative to the antenna array, which may be converted to a local or global reference frame based on the known orientation of the UE700, for example, based on the orientation of the UE700 measured by the IMU707.

[0077]

[0081] The one or more processors 702 may be implemented using a combination of hardware, firmware, and software. For example, the one or more processors 702 may be configured to perform the functions described herein by implementing one or more instructions or program code 708 on a non-transitory computer-readable medium, such as the medium 720 and / or the memory 704. In some embodiments, the one or more processors 702 may represent one or more circuits configurable to perform at least a portion of a data signal calculation procedure or process related to the operation of the UE 700.

[0078]

[0082] The medium 720 and / or memory 704 may store instructions or program code 708, which, when executed by one or more processors 702, include executable code or software instructions that cause the one or more processors 702 to operate as a special-purpose computer programmed to perform the techniques disclosed herein. As shown in UE 700, the medium 720 and / or memory 704 may include one or more components or modules that may be implemented by the one or more processors 702 to perform the methods described herein. While the components or modules are shown as software in the medium 720 executable by the one or more processors 702, it should be understood that the components or modules may be stored in the memory 704 or may be dedicated hardware either within or external to the one or more processors 702.

[0079]

[0083] A number of software modules and data tables may reside in the medium 720 and / or memory 704 and be utilized by the one or more processors 702 to manage both the communications and functionality described herein. It should be appreciated that the organization of the contents of the medium 720 and / or memory 704 shown in the UE 700 is only an example, and thus the functionality of the modules and / or data structures may be combined, separated, and / or structured in different ways depending on the implementation of the UE 700.

[0080]

[0084] The medium 720 and / or memory 704 may include a pre-PRS module 722 that, when implemented by the one or more processors 702, configures the one or more processors 702 to generate and transmit or receive a pre-PRS message via the transceiver 714, e.g., to initiate or accept a ranging session. The pre-PRS message may include ranging signal characteristics to be used in the ranging session and may include location information for the UE 700. For example, when initiating a ranging session, the pre-PRS message may include ranging signal characteristics that are available for the ranging session, and when responding to accept a ranging session, the pre-PRS message may include a set of ranging signal characteristics that are different ranging signal characteristics received in the initial pre-PRS message due to the existence of multiple ranging sessions and assigned to the initiating UE.

[0081]

[0085] The medium 720 and / or memory 704 may include a separation determination module 724 that, when implemented by the one or more processors 702, configures the one or more processors 702 to determine whether there is a temporal and / or geographical separation between the first and second ranging sessions, for example, by determining whether the temporal separation is less than a predetermined time threshold or whether the geographical separation is less than a predetermined distance threshold. For example, the temporal separation may be determined based on a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message and whether the difference is less than a predetermined time threshold. The geographical separation may be determined based on whether a difference between a first location of the first initiating UE and a second location of the second initiating UE is less than a predetermined distance threshold. The first and second locations may be included in initial pre-PRS messages from the first and second initiating UEs, for example.

[0082]

[0086] The medium 720 and / or memory 704 may include a ranging signal characteristic separation module 726 that, when implemented by the one or more processors 702, configures the one or more processors 702 to separate available ranging signal characteristics between multiple ranging sessions, e.g., between a first set for a first ranging session and a second set for a second ranging session, if the temporal and / or geographic separation for the ranging sessions is below a time or distance threshold. The ranging signal characteristics may include, e.g., frequency bandwidth, ranging signal timing instance, ranging signal identifier, or a combination thereof. The processor 702 may be configured to divide the available frequency bandwidth among initiating UEs and ensure that different ranging sessions are assigned different ranging signal timing instances and ranging signal identifiers.

[0083]

[0087] The medium 720 and / or the memory 704 may include a PRS module 728 that, when implemented by the one or more processors 702, configures the one or more processors 702 to broadcast and receive ranging signals from other UEs via the transceiver 714. The ranging signals may be, for example, PRS signals described herein. The one or more processors 702 may be configured, for example, to measure a ToD of the broadcasted ranging signal and a ToA of the received ranging signal, and may be configured to measure an AoD of the broadcasted ranging signal and an AoA of the received ranging signal.

[0084]

[0088] The medium 720 and / or memory 704 may include a post-PRS module 730 that, when implemented by the one or more processors 702, configures the one or more processors 702 to send and receive post-PRS messages to other UEs via the transceiver 714, which may include, for example, indicating the ToD, and in some implementations, indicating the AoD, of the broadcasted ranging signal and indicating the ToA, and in some implementations, indicating the AoA, of the received ranging signal.

[0085]

[0089] The medium 720 and / or the memory 704 may include a ranging module 732 that, when implemented by the one or more processors 702, configures the one or more processors 702 to determine a range to another UE based on the ToDs and ToAs of the broadcasted and received ranging signals measured by the UE 700 and received in the post-PRS messages. The processor 702 may be further configured to determine a position of the UE 700 based on, for example, one or more ranges to the broadcasting UEs and their location information using multilateration or other suitable techniques described herein.

[0086]

[0090] The methods described herein may be implemented by various means depending on the application. For example, these methods may be implemented in hardware, firmware, software, or any combination thereof. In a hardware implementation, the one or more processors 702 may be implemented within 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. The one or more processors 702 may be general-purpose computers that, when programmed to perform particular operations pursuant to instructions from program software, as described herein, operate as special-purpose computers programmed to implement the techniques disclosed herein.

[0087]

[0091] For a firmware and / or software implementation, the 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 methodologies described herein. For example, software code may be stored in non-transitory computer-readable medium 720 or memory 704 coupled to and executed by one or more processors 702. 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 long-term, short-term, volatile, non-volatile, or any other type of memory, and should not be limited to a specific type or number of memories or the type of medium on which the memory is stored.

[0088]

[0092] If implemented in firmware and / or software, the functions may be stored as one or more instructions or program code 708 on a non-transitory computer-readable medium, such as the medium 720 and / or the memory 704. Examples include a computer-readable medium encoded with a data structure and a computer-readable medium encoded with a computer program 708. For example, a non-transitory computer-readable medium having program code 708 stored thereon may include program code 708 for supporting multiple ranging sessions, in which ranging signal characteristics for PRS signals are divided among the multiple ranging sessions, in a manner consistent with disclosed embodiments. The non-transitory computer-readable medium 720 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 708 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 with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0089]

[0093] In addition to being stored on the computer-readable medium 720, the instructions and / or data may be provided as signals on a transmission medium contained in a communications device. For example, a communications device may include a transceiver 710 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.

[0090]

[0094] Memory 704 may represent any data storage mechanism. Memory 704 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 702, it should be understood that all or a portion of the primary memory may be provided within one or more processors 702, or in some cases co-located / coupled with one or more processors 702. 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.

[0091]

[0095] In some implementations, the secondary memory may be operatively capable of receiving, or possibly configurable to couple to, a non-transitory computer-readable medium 720. 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 720, which may include computer-implementable code 708 stored thereon, which, when executed by one or more processors 702, may be operatively enabled to perform all or a portion of the example operations described herein. The computer-readable medium 720 may be part of the memory 704.

[0092]

[0096] FIG. 8 is a flowchart 800 illustrating a method for user equipment (UE)-to-UE ranging performed by a receiving UE, such as UE-A 606, in a ranging session.

[0093]

[0097] At block 802, a first initial message is received from a first UE to initiate a first ranging session, as described in step 1A of Figure 6. The means for receiving the first initial message from the first UE to initiate the first ranging session may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a pre-PRS module 722.

[0094]

[0098] At block 804, a second initial message is received from the second UE to initiate a second ranging session, as described in step 1B of Figure 6. The means for receiving the second initial message from the second UE to initiate the second ranging session may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a pre-PRS module 722.

[0095]

[0099] At block 806, the receiving UE determines that the temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold, as described in stage 2 of FIG. 6 . The means for determining that the temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold may be, for example, one or more processors 702 having dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as separation determination module 724. For example, the receiving UE may determine that the difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than a predetermined time threshold. The means for determining that the difference between the first time of receipt of the first initial message and the second time of receipt of the second initial message is less than a predetermined time threshold may be, for example, one or more processors 702 having dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as separation determination module 724.

[0096]

[0100] In block 808, the receiving UE separates the available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session, where the first set of ranging signal characteristics and the second set of ranging signal characteristics are different, as described in step 3 of FIG. 6. The available ranging signal characteristics may be provided by the first UE in a first initial message and by the second UE in a second initial message, for example. The means for separating the available ranging signal characteristics into the first set for the first ranging session and the second set for the second ranging session, where the first set of ranging signal characteristics and the second set of ranging signal characteristics are different, may be, for example, one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as a ranging signal characteristic separation module 726.

[0097]

[0101] In block 810, the receiving UE transmits a first response message to the first UE comprising the first set of ranging signal characteristics and a second response message to the second UE comprising the second set of ranging signal characteristics, as described in steps 4A and 4B of Figure 6. The means for transmitting the first response message to the first UE comprising the first set of ranging signal characteristics and the second response message to the second UE may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a pre-PRS module 722.

[0098]

[0102] At block 812, the receiving UE conducts a first ranging session with the first UE using a first set of ranging signal characteristics and a second ranging session with the second UE using a second set of ranging signal characteristics, as described in steps 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, and 9C of FIG. 6. The receiving UE may, for example, receive and broadcast ranging signals over an unlicensed spectrum. The means for conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a PRS module 728, a post-PRS module 730, and a ranging module 732. For example, the receiving UE may conduct a first ranging session with the first UE using the first set of available ranging signal characteristics, and a second ranging session with the second UE using the second set of ranging signal characteristics, by receiving a first ranging signal broadcasted from the first UE using the first set of available ranging signal characteristics, e.g., as described in step 5A of FIG. 6; broadcasting a second ranging signal to the first UE using the first set of ranging signal characteristics, e.g., as described in step 6A of FIG. 6; receiving a third ranging signal broadcasted from the second UE using the second set of ranging signal characteristics, e.g., as described in step 5B of FIG. 6; and broadcasting a fourth ranging signal to the second UE using the second set of ranging signal characteristics, e.g., as described in step 6B of FIG. 6.The means for receiving a first ranging signal broadcasted from a first UE using a first set of available ranging signal characteristics, the means for broadcasting a second ranging signal to the first UE using the first set of ranging signal characteristics, the means for receiving a third ranging signal broadcasted from a second UE using the second set of ranging signal characteristics, and the means for broadcasting a fourth ranging signal to the second UE using the second set of ranging signal characteristics can be, for example, a transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as a PRS module 728.

[0099]

[0103] In some implementations, the receiving UE may further determine whether the geographic separation between the first UE and the second UE is less than a predetermined distance threshold, e.g., as described in stage 2 in FIG. 6. For example, the receiving UE may determine that the usable ranging signal characteristics are implemented when both the temporal separation is less than a predetermined time threshold and the geographic separation is less than a predetermined distance threshold, e.g., as described in stage 3 of FIG. 6. The means for determining whether the geographic separation between the first UE and the second UE is less than a predetermined distance threshold may be, for example, one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as separation determination module 724. As an example, the first initial message may include a first location of the first UE and the second initial message may include a second location of the second UE, and the receiving UE may determine whether the geographic separation is less than a predetermined distance threshold by determining that the difference between the first location and the second location is less than a predetermined distance threshold. The means for determining that the difference between the first location and the second location is less than a predetermined distance threshold may be, for example, one or more processors 702 having dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as separation determination module 724.

[0100]

[0104] In one implementation, the available ranging signal characteristics may comprise a frequency bandwidth, and the receiving UE may separate the available ranging signal characteristics by dividing the frequency bandwidth between the first UE and the second UE, for example, as described in stage 3 of Figure 6. The means for dividing the frequency bandwidth between the first UE and the second UE may be, for example, one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as a ranging signal characteristic separation module 726.

[0101]

[0105] In one implementation, the available ranging signal characteristics may comprise ranging signal timing instances, and the receiving UE may separate the available ranging signal characteristics by, for example, providing a first set of ranging signal characteristics with the first set of ranging signal timing instances and providing a second set of ranging signal characteristics with the second set of ranging signal timing instances, as described in stage 3 of Figure 6. Means for providing the first set of ranging signal characteristics with the first set of ranging signal timing instances and providing the second set of ranging signal characteristics with the second set of ranging signal timing instances may be, for example, one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as a ranging signal characteristic separation module 726.

[0102]

[0106] In one implementation, the available ranging signal characteristics may comprise a ranging signal identifier, and the receiving UE may separate the available ranging signal characteristics by, for example, providing a first set of ranging signal characteristics with a first ranging signal identifier and providing a second set of ranging signal characteristics with a second ranging signal identifier, as described in stage 3 of Figure 6. The means for dividing the frequency bandwidth between the first and second UEs may be, for example, one or more processors 702 with dedicated hardware or implementing executable code or software instructions in memory 704 and / or medium 720, such as a ranging signal characteristic separation module 726.

[0103]

[0107] FIG. 9 is a flowchart 900 illustrating a method for user equipment (UE) ranging performed by an initiating UE, such as UE 1 602, in a ranging session.

[0104]

[0108] In block 902, the initiating UE sends a first initial message to the first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session, as described in step 1A of Figure 6. The means for sending the first initial message to the first UE to initiate the first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session, may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a pre-PRS module 722.

[0105]

[0109] In block 904, the initiating UE receives from the first UE a response message comprising a set of ranging signal characteristics to be used during the first ranging session, different from the ranging signal characteristics indicated in the first initial message, e.g., as described in step 4A of Figure 6. Means for receiving from the first UE a response message comprising a set of ranging signal characteristics to be used during the first ranging session, different from the ranging signal characteristics indicated in the first initial message, can be, e.g., the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a pre-PRS module 722.

[0106]

[0110] At block 906, the initiating UE conducts a first ranging session with the first UE using the set of ranging signal characteristics, e.g., as described in steps 5A, 6A, 7A, 8A, and 9A of FIG. 6. The initiating UE may receive and broadcast ranging signals, for example, on an unlicensed spectrum. The means for conducting the first ranging session with the first UE using the set of ranging signal characteristics may be, for example, the transceiver 714 and one or more processors 702 with dedicated hardware or implementing executable code or software instructions in the memory 704 and / or medium 720, such as a PRS module 728, a post-PRS module 730, and a ranging module 732.

[0107]

[0111] In one implementation, for example, as described in stages 3 and 4A of FIG. 6, the ranging signal characteristics indicated in the first initial message to the first UE may comprise a frequency bandwidth, and the set of ranging signal characteristics received from the first UE may comprise a subset of the frequency bandwidth.

[0108]

[0112] In one implementation, for example, as described in stages 3 and 4A of FIG. 6, the ranging signal characteristics indicated in the first initial message to the first UE may comprise a ranging signal timing instance, and the set of ranging signal characteristics received from the first UE may comprise a different ranging signal timing instance.

[0109]

[0113] In one implementation, for example, as described in stages 3 and 4A of FIG. 6, the ranging signal characteristics indicated in the first initial message to the first UE may comprise a ranging signal identifier, and the set of ranging signal characteristics received from the first UE may comprise a different ranging signal identifier.

[0110]

[0114] References throughout this specification to "one example," "an example," "certain examples," or "exemplary implementation" 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," "in certain examples," or "in certain implementations," or other similar phrases, in various places throughout this specification do not necessarily all refer 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.

[0111]

[0115] Some portions of the detailed descriptions contained herein have been presented in terms of algorithms or symbolic representations of operations on binary digital signals stored within 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 once it has been programmed to perform 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. Typically, 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, numerals, or the like. It should be understood, however, that all of these or similar terms are to be associated with appropriate physical quantities and are merely convenient labels. Unless otherwise expressly stated, as will be apparent from the description herein, it should be appreciated that throughout this specification, descriptions utilizing terms such as "processing," "computing," "calculating," "determining," and the like 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, generally represented as electronic or magnetic physical 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.

[0112]

[0116] In the above detailed description, numerous specific details have been 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 to those skilled in the art have not been described in detail so as not to obscure the claimed subject matter.

[0113]

[0117] As used herein, the terms "and," "or," and "and / or" can have a variety of meanings that are expected to depend, at least in part, on the context in which such terms are used. In general, when "or" is used to link a list such as A, B, or C, it shall 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. Furthermore, as used herein, the term "one or more" may be used to describe any feature, structure, or characteristic in the singular, or it may be used to describe multiple 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 that claimed subject matter is not limited to this example.

[0114]

[0118] While what are presently considered to be exemplary features have been illustrated and described, those skilled in the art will recognize 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.

[0115]

[0119] Example implementations are described in the following numbered clauses.

[0116]

[0120] 1. A method of ranging between user equipment (UE) performed by a receiving UE, the method comprising:

[0121] receiving a first initial message from a first UE to initiate a first ranging session;

[0122] receiving a second initial message from a second UE to initiate a second ranging session;

[0123] determining that a temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold;

[0124] separating the available ranging signal characteristics into a first set for a first ranging session and a second set for a second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different;

[0125] sending a first response message to the first UE, the first response message comprising a first set of ranging signal characteristics, and a second response message to the second UE, the second response message comprising a second set of ranging signal characteristics;

[0126] conducting a first ranging session with the first UE using a first set of ranging signal characteristics and conducting a second ranging session with the second UE using a second set of ranging signal characteristics; A method comprising:

[0117]

[0127] 2. The method of clause 1, wherein determining that the temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold comprises determining that the difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than a predetermined time threshold.

[0118]

[0128] 3. The method of any of clauses 1 or 2, further comprising determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold.

[0119]

[0129] 4. The method of clause 3, wherein separating the available ranging signal characteristics is performed when the temporal separation is both less than a predetermined time threshold and the geographic separation is less than a predetermined distance threshold.

[0120]

[0130] 5. The method of clause 3, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein determining whether the geographic separation is less than a predetermined distance threshold comprises determining that a difference between the first location and the second location is less than the predetermined distance threshold.

[0121]

[0131] 6. The method of any of clauses 1 to 5, wherein the available ranging signal characteristics are provided by the first UE in a first initial message and by the second UE in a second initial message.

[0122]

[0132] 7. The method of any of clauses 1 to 6, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein separating the available ranging signal characteristic comprises dividing the frequency bandwidth between the first UE and the second UE.

[0123]

[0133] 8. The method of any of clauses 1 to 7, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein separating the available ranging signal characteristics comprises providing a first set of ranging signal characteristics with the first set of ranging signal timing instances, and providing a second set of ranging signal characteristics with the second set of ranging signal timing instances.

[0124]

[0134] 9. The method of any of clauses 1-8, wherein the available ranging signal characteristics comprise ranging signal identifiers, and wherein segregating the available ranging signal characteristics comprises providing a first set of ranging signal characteristics with a first ranging signal identifier and providing a second set of ranging signal characteristics with a second ranging signal identifier.

[0125]

[0135] 10. The method of any of clauses 1 to 9, wherein conducting a first ranging session with a first UE using a first set of ranging signal characteristics and conducting a second ranging session with a second UE using a second set of ranging signal characteristics comprises receiving and broadcasting ranging signals over an unlicensed spectrum.

[0126]

[0136] 11. Conducting a first ranging session with a first UE using a first set of ranging signal characteristics and conducting a second ranging session with a second UE using a second set of ranging signal characteristics;

[0137] receiving a first ranging signal broadcast from a first UE using a first set of available ranging signal characteristics;

[0138] broadcasting a second ranging signal to the first UE using a first set of ranging signal characteristics;

[0139] receiving a third ranging signal broadcast from a second UE using a second set of ranging signal characteristics;

[0140] broadcasting a fourth ranging signal to the second UE using a second set of ranging signal characteristics; 11. The method of any of clauses 1 to 10, comprising:

[0127]

[0141] 12. A user equipment (UE) configured for UE-to-UE ranging, the UE comprising:

[0142] a wireless transceiver configured to wirelessly communicate with entities in a wireless network;

[0143] At least one memory;

[0144] at least one processor coupled to a wireless transceiver and at least one memory; wherein at least one processor comprises:

[0145] receiving a first initial message from a first UE to initiate a first ranging session;

[0146] receiving a second initial message from a second UE to initiate a second ranging session;

[0147] determining that a temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold;

[0148] separating the available ranging signal characteristics into a first set for a first ranging session and a second set for a second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different;

[0149] sending a first response message to the first UE, the first response message comprising a first set of ranging signal characteristics, and a second response message to the second UE, the second response message comprising a second set of ranging signal characteristics;

[0150] conducting a first ranging session with the first UE using a first set of ranging signal characteristics and conducting a second ranging session with the second UE using a second set of ranging signal characteristics; A user equipment (UE) configured to perform the following:

[0128]

[0151] 13. The UE of clause 12, wherein the at least one processor is configured to determine that a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than a predetermined time threshold, thereby determining that a temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold.

[0129]

[0152] 14. The UE of either clause 12 or 13, wherein the at least one processor is further configured to determine whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold.

[0130]

[0153] 15. The UE of clause 14, wherein the at least one processor is configured to separate available ranging signal characteristics when the temporal separation is both less than a predetermined time threshold and the geographic separation is less than a predetermined distance threshold.

[0131]

[0154] 16. The UE of clause 14, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein the at least one processor is configured to determine whether the geographic separation is less than a predetermined distance threshold by determining that a difference between the first location and the second location is less than a predetermined distance threshold.

[0132]

[0155] 17. The UE of any of clauses 12 to 16, wherein the available ranging signal characteristics are provided by the first UE in a first initial message and by the second UE in a second initial message.

[0133]

[0156] 18. The UE of any of clauses 12 to 17, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein the at least one processor is configured to separate the available ranging signal characteristic by being configured to divide the frequency bandwidth between the first UE and the second UE.

[0134]

[0157] 19. The UE of any of clauses 12 to 18, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein the at least one processor is configured to isolate the available ranging signal characteristics by providing a first set of ranging signal characteristics having the first set of ranging signal timing instances and providing a second set of ranging signal characteristics having the second set of ranging signal timing instances.

[0135]

[0158] 20. The UE of any of clauses 12 to 19, wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein the at least one processor is configured to segregate the available ranging signal characteristics by configuring: providing a first set of ranging signal characteristics with a first ranging signal identifier; and providing a second set of ranging signal characteristics with a second ranging signal identifier.

[0136]

[0159] 21. The UE of any of clauses 12 to 20, wherein at least one processor is configured to receive and broadcast ranging signals over an unlicensed spectrum, thereby conducting a first ranging session with a first UE using a first set of ranging signal characteristics and conducting a second ranging session with a second UE using a second set of ranging signal characteristics.

[0137]

[0160] 22. At least one processor:

[0161] receiving a first ranging signal broadcast from a first UE using a first set of available ranging signal characteristics;

[0162] broadcasting a second ranging signal to the first UE using a first set of ranging signal characteristics;

[0163] receiving a third ranging signal broadcast from a second UE using a second set of ranging signal characteristics;

[0164] broadcasting a fourth ranging signal to the second UE using a second set of ranging signal characteristics; 22. The UE of any of clauses 12 to 21, configured to: conduct a first ranging session with a first UE using a first set of ranging signal characteristics; and conduct a second ranging session with a second UE using a second set of ranging signal characteristics.

[0138]

[0165] 23. A user equipment (UE) configured for UE-to-UE ranging, the UE comprising:

[0166] means for receiving a first initial message from a first UE to initiate a first ranging session;

[0167] means for receiving a second initial message from a second UE to initiate a second ranging session;

[0168] means for determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold;

[0169] means for separating available ranging signal characteristics into a first set for a first ranging session and a second set for a second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different;

[0170] means for transmitting a first response message to the first UE, the first response message comprising a first set of ranging signal characteristics, and a second response message to the second UE, the second response message comprising a second set of ranging signal characteristics;

[0171] means for conducting a first ranging session with a first UE using a first set of ranging signal characteristics and a second ranging session with a second UE using a second set of ranging signal characteristics; A user equipment (UE) comprising:

[0139]

[0172] 24. The UE of clause 23, further comprising means for determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold, wherein the means for isolating the available ranging signal characteristics isolates the available ranging signal characteristics when both the temporal separation is less than a predetermined time threshold and the geographic separation is less than a predetermined distance threshold.

[0140]

[0173] 25. The UE of either clause 23 or 24, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein the means for separating the available ranging signal characteristic comprises means for dividing the frequency bandwidth between the first UE and the second UE.

[0141]

[0174] 26. The UE of any of clauses 23 to 25, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein the means for isolating the available ranging signal characteristics comprises means for providing a first set of ranging signal characteristics having the first set of ranging signal timing instances and providing a second set of ranging signal characteristics having the second set of ranging signal timing instances.

[0142]

[0175] 27. The UE of any of clauses 23 to 26, wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein the means for isolating the available ranging signal characteristics comprises means for providing a first set of ranging signal characteristics having a first ranging signal identifier and providing a second set of ranging signal characteristics having a second ranging signal identifier.

[0143]

[0176] 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) for ranging between UEs;

[0177] program code for receiving a first initial message from a first UE to initiate a first ranging session;

[0178] program code for receiving a second initial message from a second UE to initiate a second ranging session;

[0179] program code for determining that a temporal separation between the first ranging session and the second ranging session is less than a predetermined time threshold;

[0180] program code for separating available ranging signal characteristics into a first set for a first ranging session and a second set for a second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different;

[0181] program code for transmitting a first response message to a first UE, the first response message comprising a first set of ranging signal characteristics, and transmitting a second response message to a second UE, the second response message comprising a second set of ranging signal characteristics;

[0182] program code for conducting a first ranging session with a first UE using a first set of ranging signal characteristics and conducting a second ranging session with a second UE using a second set of ranging signal characteristics; A non-transitory storage medium comprising:

[0144]

[0183] 29. The non-transitory storage medium of clause 28, further comprising program code for determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold, wherein the program code for isolating the available ranging signal characteristics isolates the available ranging signal characteristics when both the temporal separation is less than a predetermined time threshold and the geographic separation is less than a predetermined distance threshold.

[0145]

[0184] 30. The non-transitory storage medium of either clause 28 or 29, wherein the available ranging signal characteristics comprise one or more of a frequency bandwidth, a ranging signal timing instance, and a ranging signal identifier, or a combination thereof, and wherein the program code for separating the available ranging signal characteristics comprises one or more program codes for dividing the frequency bandwidth between the first UE and the second UE, program code for providing a first set of ranging signal characteristics with the first set of ranging signal timing instances and providing a second set of ranging signal characteristics with the second set of ranging signal timing instances, program code for providing the first set of ranging signal characteristics with the first ranging signal identifier and providing the second set of ranging signal characteristics with the second ranging signal identifier, or a combination thereof.

[0146]

[0185] 31. A method of ranging between user equipment (UE) performed by an initiating UE, the method comprising:

[0186] sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session;

[0187] receiving a response message from the first UE comprising a set of ranging signal characteristics to be used during the first ranging session that are different from the ranging signal characteristics indicated in the first initial message;

[0188] conducting a first ranging session with the first UE using a set of ranging signal characteristics; A method comprising:

[0147]

[0189] 32. The method of clause 31, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth.

[0148]

[0190] 33. The method of either clause 31 or 32, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal timing instance, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal timing instance.

[0149]

[0191] 34. The method of any of clauses 31 to 33, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal identifier.

[0150]

[0192] 35. The method of any of clauses 31 to 34, wherein conducting a first ranging session with the first UE using a set of ranging signal characteristics comprises receiving and broadcasting a ranging signal over an unlicensed spectrum.

[0151]

[0193] 36. A user equipment (UE) configured for UE-to-UE ranging, the UE comprising:

[0194] a wireless transceiver configured to wirelessly communicate with entities in a wireless network;

[0195] At least one memory;

[0196] at least one processor coupled to a wireless transceiver and at least one memory; wherein at least one processor comprises:

[0197] sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session;

[0198] receiving a response message from the first UE comprising a set of ranging signal characteristics to be used during the first ranging session that are different from the ranging signal characteristics indicated in the first initial message;

[0199] conducting a first ranging session with the first UE using a set of ranging signal characteristics; A user equipment (UE) configured to perform the following:

[0152]

[0200] 37. The UE of clause 36, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth.

[0153]

[0201] 38. The UE of either clause 36 or 37, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise ranging signal timing instances, and wherein the sets of ranging signal characteristics received from the first UE comprise different ranging signal timing instances.

[0154]

[0202] 39. The UE of any of clauses 36 to 38, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal identifier.

[0155]

[0203] 40. The UE of any of clauses 36 to 38, wherein at least one processor is configured to receive and broadcast ranging signals over an unlicensed spectrum, thereby conducting a first ranging session with a first UE using a set of ranging signal characteristics.

[0156]

[0204] 41. A user equipment (UE) configured for UE-to-UE ranging, the UE comprising:

[0205] means for sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session;

[0206] means for receiving from the first UE a response message comprising a set of ranging signal characteristics that are different from the ranging signal characteristics indicated in the first initial message and that are to be used during the first ranging session;

[0207] means for conducting a first ranging session with a first UE using a set of ranging signal characteristics; A user equipment (UE) comprising:

[0157]

[0208] 42. The UE of clause 41, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth.

[0158]

[0209] 43. The UE of either clause 41 or 42, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise ranging signal timing instances, and wherein the sets of ranging signal characteristics received from the first UE comprise different ranging signal timing instances.

[0159]

[0210] 44. A UE as described in any of clauses 41 to 43, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal identifier.

[0160]

[0211] 45. The UE of any of clauses 41 to 44, wherein the means for conducting a first ranging session with the first UE using the set of ranging signal characteristics comprises means for receiving and broadcasting a ranging signal on an unlicensed spectrum.

[0161]

[0212] 46. ​​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) for ranging between UEs, the UE comprising:

[0213] program code for sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session;

[0214] and program code for receiving, from the first UE, a response message comprising a set of ranging signal characteristics that are different from the ranging signal characteristics indicated in the first initial message and that are to be used during the first ranging session.

[0215] program code for conducting a first ranging session with a first UE using a set of ranging signal characteristics; A non-transitory storage medium comprising:

[0162]

[0216] 47. The non-transitory storage medium of clause 46, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth.

[0163]

[0217] 48. The non-transitory storage medium of either clause 46 or 47, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise ranging signal timing instances, and wherein the set of ranging signal characteristics received from the first UE comprise different ranging signal timing instances.

[0164]

[0218] 49. The non-transitory storage medium of any of clauses 46 to 48, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal identifier.

[0165]

[0219] 50. The non-transitory storage medium of any of clauses 46 to 49, wherein the program code for conducting a first ranging session with a first UE using a set of ranging signal characteristics comprises program code for receiving and broadcasting a ranging signal on an unlicensed spectrum.

[0166]

[0220] Accordingly, it is intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter also include all embodiments falling within the scope of the appended claims and their equivalents. The inventions described in the claims of the present application as originally filed are set forth below. [C1] 1. A method of ranging between user equipment (UE) performed by a receiving UE, the method comprising: receiving a first initial message from a first UE to initiate a first ranging session; receiving a second initial message from a second UE to initiate a second ranging session; determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold; separating available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; sending a first response message to the first UE comprising the first set of ranging signal characteristics and a second response message to the second UE comprising the second set of ranging signal characteristics; conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics; A method comprising: [C2] The method of C1, wherein determining that the temporal separation between the first ranging session and the second ranging session is less than the predetermined time threshold comprises determining that a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than the predetermined time threshold. [C3] The method of C1, further comprising determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold. [C4] The method of claim 3, wherein separating the available ranging signal characteristics is performed when both the temporal separation is less than the predetermined time threshold and the geographic separation is less than the predetermined distance threshold. [C5] The method of C3, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein determining whether the geographic separation is less than the predetermined distance threshold comprises determining that a difference between the first location and the second location is less than the predetermined distance threshold. [C6] The method of C1, wherein the available ranging signal characteristics are provided by the first UE in the first initial message and by the second UE in the second initial message. [C7] 10. The method of claim 1, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein separating the available ranging signal characteristic comprises dividing the frequency bandwidth between the first UE and the second UE. [C8] the available ranging signal characteristics comprise ranging signal timing instances, and wherein separating the available ranging signal characteristics comprises providing the first set of ranging signal characteristics with a first set of ranging signal timing instances and providing the second set of ranging signal characteristics with a second set of ranging signal timing instances. [C9] The method of C1, wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein segregating the available ranging signal characteristics comprises providing the first set of ranging signal characteristics with a first ranging signal identifier and providing the second set of ranging signal characteristics with a second ranging signal identifier. [C10] 10. The method of claim 9, wherein conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics comprises receiving and broadcasting ranging signals over an unlicensed spectrum. [C11] conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics; receiving a first ranging signal broadcast from the first UE using the first set of available ranging signal characteristics; broadcasting a second ranging signal to the first UE using the first set of ranging signal characteristics; receiving a third ranging signal broadcast from the second UE using the second set of ranging signal characteristics; broadcasting a fourth ranging signal to the second UE using the second set of ranging signal characteristics; and The method of claim C1, comprising: [C12] A user equipment (UE) configured for UE-to-UE ranging, the UE comprising: 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; wherein the at least one processor: receiving a first initial message from a first UE to initiate a first ranging session; receiving a second initial message from a second UE to initiate a second ranging session; determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold; separating available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; sending a first response message to the first UE comprising the first set of ranging signal characteristics and a second response message to the second UE comprising the second set of ranging signal characteristics; conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics; A user equipment (UE) configured to perform the following: [C13] The UE of C12, wherein the at least one processor is configured to determine that a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than the predetermined time threshold, thereby determining that the temporal separation between the first ranging session and the second ranging session is less than the predetermined time threshold. [C14] The UE of C12, wherein the at least one processor is further configured to determine whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold. [C15] The UE of C14, wherein the at least one processor is configured to separate the available ranging signal characteristics when both the temporal separation is less than the predetermined time threshold and the geographic separation is less than the predetermined distance threshold. [C16] The UE described in C14, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein the at least one processor is configured to determine whether the geographical separation is less than the predetermined distance threshold by determining that a difference between the first location and the second location is less than the predetermined distance threshold. [C17] The UE of C12, wherein the available ranging signal characteristics are provided by the first UE in the first initial message and by the second UE in the second initial message. [C18] 13. The UE of claim 12, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein the at least one processor is configured to separate the available ranging signal characteristic by dividing the frequency bandwidth between the first UE and the second UE. [C19] 13. The UE of claim 12, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein the at least one processor is configured to isolate available ranging signal characteristics by providing the first set of ranging signal characteristics with a first set of ranging signal timing instances and providing the second set of ranging signal characteristics with a second set of ranging signal timing instances. [C20] 13. The UE of claim 12, wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein the at least one processor is configured to segregate available ranging signal characteristics by providing the first set of ranging signal characteristics with a first ranging signal identifier and providing the second set of ranging signal characteristics with a second ranging signal identifier. [C21] 13. The UE of claim 12, wherein the at least one processor is configured to receive and broadcast ranging signals over an unlicensed spectrum, thereby conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics. [C22] the at least one processor: receiving a first ranging signal broadcast from the first UE using the first set of available ranging signal characteristics; broadcasting a second ranging signal to the first UE using the first set of ranging signal characteristics; receiving a third ranging signal broadcast from the second UE using the second set of ranging signal characteristics; broadcasting a fourth ranging signal to the second UE using the second set of ranging signal characteristics; and and wherein the UE is configured to: conduct the first ranging session with the first UE using the first set of ranging signal characteristics; and conduct the second ranging session with the second UE using the second set of ranging signal characteristics. [C23] A user equipment (UE) configured for UE-to-UE ranging, the UE comprising: means for receiving a first initial message from a first UE to initiate a first ranging session; means for receiving a second initial message from a second UE to initiate a second ranging session; means for determining that a time separation between the first ranging session and the second ranging session is less than a predetermined time threshold; means for separating available ranging signal characteristics into a first set for the first ranging session and a second set for the second ranging session, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different; means for transmitting a first response message to the first UE, the first response message comprising the first set of ranging signal characteristics, and a second response message to the second UE, the second response message comprising the second set of ranging signal characteristics; means for conducting the first ranging session with the first UE using the first set of ranging signal characteristics and for conducting the second ranging session with the second UE using the second set of ranging signal characteristics; A user equipment (UE) comprising: [C24] The UE of C23, further comprising means for determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold, wherein the means for separating the available ranging signal characteristics separates the available ranging signal characteristics when both the temporal separation is less than the predetermined time threshold and the geographic separation is less than the predetermined distance threshold. [C25] 22. The UE of claim 21, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein the means for separating the available ranging signal characteristic comprises means for dividing the frequency bandwidth between the first UE and the second UE. [C26] 10. The UE of claim 9, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein the means for isolating available ranging signal characteristics comprises means for providing the first set of ranging signal characteristics with a first set of ranging signal timing instances and providing the second set of ranging signal characteristics with a second set of ranging signal timing instances. [C27] 10. The UE of claim 9, wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein the means for isolating available ranging signal characteristics comprises means for providing the first set of ranging signal characteristics with a first ranging signal identifier and providing the second set of ranging signal characteristics with a second ranging signal identifier. [C28] 1. A method of ranging between user equipment (UE) performed by an initiating UE, the method comprising: sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session; receiving a response message from the first UE comprising a set of ranging signal characteristics to be used during the first ranging session that are different from the ranging signal characteristics indicated in the first initial message; conducting the first ranging session with the first UE using the set of ranging signal characteristics; A method comprising: [C29] 3. The method of claim 2, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth. [C30] 3. The method of claim 2, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal timing instance, and wherein the set of ranging signal characteristics received from the first UE comprise different ranging signal timing instances. [C31] 3. The method of claim 2, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprises a different ranging signal identifier. [C32] The method of C33, wherein conducting the first ranging session with the first UE using the set of ranging signal characteristics comprises receiving and broadcasting a ranging signal over an unlicensed spectrum. [C33] A user equipment (UE) configured for UE-to-UE ranging, the UE comprising: 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; wherein the at least one processor: sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session; receiving a response message from the first UE comprising a set of ranging signal characteristics to be used during the first ranging session that are different from the ranging signal characteristics indicated in the first initial message; conducting the first ranging session with the first UE using the set of ranging signal characteristics; A user equipment (UE) configured to perform the following: [C34] UE of C33, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth. [C35] UE of C33, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal timing instance, and wherein the set of ranging signal characteristics received from the first UE comprise different ranging signal timing instances. [C36] UE of C33, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprise a different ranging signal identifier. [C37] UE according to C33, wherein the at least one processor is configured to receive and broadcast ranging signals over an unlicensed spectrum, thereby conducting the first ranging session with the first UE using the set of ranging signal characteristics. [C38] A user equipment (UE) configured for UE-to-UE ranging, the UE comprising: means for sending a first initial message to a first UE to initiate a first ranging session, the first initial message indicating ranging signal characteristics for the first ranging session; means for receiving from the first UE a response message comprising a set of ranging signal characteristics to be used during the first ranging session, the set being different from the ranging signal characteristics indicated in the first initial message; means for conducting the first ranging session with the first UE using the set of ranging signal characteristics; A user equipment (UE) comprising: [C39] UE of C38, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a frequency bandwidth, and wherein the set of ranging signal characteristics received from the first UE comprises a subset of the frequency bandwidth. [C40] UE of C38, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal timing instance, and wherein the set of ranging signal characteristics received from the first UE comprise different ranging signal timing instances. [C41] UE of C38, wherein the ranging signal characteristics indicated in the first initial message to the first UE comprise a ranging signal identifier, and wherein the set of ranging signal characteristics received from the first UE comprise a different ranging signal identifier. [C42] 10. The UE of claim 9, wherein the means for conducting the first ranging session with the first UE using the set of ranging signal characteristics comprises means for receiving and broadcasting a ranging signal on an unlicensed spectrum.

Claims

1. 1. A method of ranging between user equipment (UE) performed by a receiving UE, the method comprising: receiving a first initial message from a first UE to initiate a first ranging session; receiving a second initial message from a second UE to initiate a second ranging session; determining that a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than a predetermined time threshold; in response to determining that the difference is less than the predetermined time threshold, transmitting a first response message to the first UE comprising a first set of ranging signal characteristics and transmitting a second response message to the second UE comprising a second set of ranging signal characteristics, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different portions divided from available ranging signal characteristics. conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics after transmitting the first response message to the first UE and the second response message to the second UE; A method comprising:

2. The method of claim 1 , further comprising determining whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold.

3. 3. The method of claim 2, wherein available ranging signal characteristics are separated into the first and second sets when both the difference between the first time of receipt of the first initial message and the second time of receipt of the second initial message is less than the predetermined time threshold and the geographic separation is less than the predetermined distance threshold.

4. 4. The method of claim 3, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein determining whether the geographic separation is less than the predetermined distance threshold comprises determining that a difference between the first location and the second location is less than the predetermined distance threshold.

5. 4. The method of claim 3, wherein the available ranging signal characteristics are provided by the first UE in the first initial message and by the second UE in the second initial message.

6. 4. The method of claim 3, wherein the available ranging signal characteristic comprises a frequency bandwidth, and wherein separating the available ranging signal characteristic comprises dividing the frequency bandwidth between the first UE and the second UE.

7. 4. The method of claim 3, wherein the available ranging signal characteristics comprise ranging signal timing instances, and wherein separating available ranging signal characteristics comprises providing the first set of ranging signal characteristics with a first set of ranging signal timing instances and providing the second set of ranging signal characteristics with a second set of ranging signal timing instances.

8. 2. The method of claim 1 , wherein the available ranging signal characteristics comprise a ranging signal identifier, and wherein segregating the available ranging signal characteristics comprises providing the first set of ranging signal characteristics with a first ranging signal identifier and providing the second set of ranging signal characteristics with a second ranging signal identifier.

9. 10. The method of claim 1, wherein conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics comprises receiving and broadcasting ranging signals over an unlicensed spectrum.

10. conducting the first ranging session with the first UE using the first set of ranging signal characteristics and conducting the second ranging session with the second UE using the second set of ranging signal characteristics; receiving a first ranging signal broadcast from the first UE using the first set of available ranging signal characteristics; broadcasting a second ranging signal to the first UE using the first set of ranging signal characteristics; receiving a third ranging signal broadcast from the second UE using the second set of ranging signal characteristics; and broadcasting a fourth ranging signal to the second UE using the second set of ranging signal characteristics; and The method of claim 1 , comprising:

11. A user equipment (UE) configured for UE-to-UE ranging, the UE comprising: 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; wherein the at least one processor: receiving a first initial message from a first UE to initiate a first ranging session; receiving a second initial message from a second UE to initiate a second ranging session; determining that a difference between a first time of receipt of the first initial message and a second time of receipt of the second initial message is less than a predetermined time threshold; in response to determining that the difference is less than the predetermined time threshold, transmitting a first response message to the first UE comprising a first set of ranging signal characteristics and transmitting a second response message to the second UE comprising a second set of ranging signal characteristics, wherein the first set of ranging signal characteristics and the second set of ranging signal characteristics are different portions divided from available ranging signal characteristics. conducting the first ranging session with the first UE using the first set of ranging signal characteristics and the second ranging session with the second UE using the second set of ranging signal characteristics after transmitting the first response message to the first UE and the second response message to the second UE; A user equipment (UE) configured to:

12. 12. The UE of claim 11, wherein the at least one processor is further configured to determine whether a geographic separation between the first UE and the second UE is less than a predetermined distance threshold.

13. 13. The UE of claim 12, wherein the at least one processor is configured to separate the available ranging signal characteristics when both the difference between the first time of receipt of the first initial message and the second time of receipt of the second initial message is less than the predetermined time threshold and the geographic separation is less than the predetermined distance threshold.

14. 13. The UE of claim 12, wherein the first initial message comprises a first location of the first UE and the second initial message comprises a second location of the second UE, and wherein the at least one processor is configured to determine whether the geographic separation is less than the predetermined distance threshold by determining that a difference between the first location and the second location is less than the predetermined distance threshold.

15. 12. The UE of claim 11, wherein the available ranging signal characteristics are provided by the first UE in the first initial message and by the second UE in the second initial message.

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