Combined distributed ranging sessions involving common devices

Abstract

Independent ranging sessions initiated by multiple initiating user equipments (UEs) are detected and combined into a single combined ranging session to reduce overhead. When the UE detects multiple ranging cycles within a predefined time, the independent ranging sessions can be determined to be close and simultaneous. The UE can send a message to each initiating UE indicating that the ranging sessions should be combined, and the initiating UE terminates the initiation of any further ranging sessions. The combined ranging session can be initiated by the UE and can include all participating UEs from the independent ranging sessions. The combined ranging session continues until it is determined that one or more UEs in the combined ranging session are not receiving ranging signals from other UEs.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Non-provisional Application No. 17 / 184,403, entitled “COMBINED DISTRIBUTED RANGING SESSIONS INCLUDING COMMON DEVICES,” filed February 24, 2021, which is assigned to the assignee of this application and is expressly incorporated by reference in its entirety herein.

[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] Obtaining precise location information for user equipment, such as cellular telephones 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] 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, location determination signals from an SPS may be unreliable or unavailable, for example during adverse weather conditions or in areas with poor satellite signal reception, such as tunnels or parking complexes. Furthermore, position information generated using an SPS is prone to inaccuracies. For example, off-the-shelf GPS positioning devices have an accuracy of a few meters, which is not optimal for ensuring safe autonomous driving and navigation.

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

[0006] Independent ranging sessions initiated by multiple initiating user equipments (UEs) are detected and combined into a single combined ranging session to reduce overhead. When the UE detects multiple ranging cycles within a predefined time, the independent ranging sessions can be determined to be close and simultaneous. The UE can send a message to each initiating UE indicating that the ranging sessions should be combined, and the initiating UE terminates the initiation of any further ranging sessions. The combined ranging session can be initiated by the UE and can include all participating UEs from the independent ranging sessions. The combined ranging session continues until it is determined that one or more UEs in the combined ranging session are not receiving ranging signals from other UEs.

[0007] In one embodiment, a method for ranging between user equipment (UE) performed by a first UE includes receiving initiation messages for initiating separate ranging sessions from multiple UEs, sending a message to the multiple UEs indicating that the first UE will initiate a combined ranging session to combine the separate ranging sessions, and performing the combined ranging session by the multiple UEs.

[0008] In one embodiment, a first UE configured to perform ranging between user equipment (UE) comprises 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 initiation messages for initiating separate ranging sessions from a plurality of UEs, send a message to the plurality of UEs indicating that the first UE will initiate a combined ranging session to combine the separate ranging sessions, and conduct the combined ranging session by the plurality of UEs.

[0009] In one embodiment, in a first UE configured for ranging between user equipment (UE), the first UE includes means for receiving initiation messages for initiating separate ranging sessions from a plurality of UEs, means for sending a message to the plurality of UEs indicating that the first UE will initiate a combined ranging session to combine the separate ranging sessions, and means for conducting the combined ranging session by the plurality of UEs.

[0010] In one embodiment, a non-transitory storage medium having program code stored thereon is operable to configure at least one processor in a user equipment (UE) for ranging between the UEs, the program code including instructions for receiving initiation messages for initiating separate ranging sessions from a plurality of UEs, sending a message to the plurality of UEs indicating that the first UE will initiate a combined ranging session to combine the separate ranging sessions, and conducting the combined ranging session by the plurality of UEs.

[0011] In one embodiment, a method for ranging between user equipment (UE) performed by a first UE includes the steps of sending an initiation message to a second UE to initiate a first ranging session, receiving a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE, and performing the combined ranging session by the second UE.

[0012] In one embodiment, a first UE configured to perform ranging between user equipment (UE) comprises 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 send an initiation message to a second UE to initiate a first ranging session, receive a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE, and conduct the combined ranging session by the second UE.

[0013] In one embodiment, in a first UE configured for ranging between user equipment (UE), the first UE includes means for sending an initiation message to a second UE for initiating a first ranging session, means for receiving a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE, and means for conducting the combined ranging session by the second UE.

[0014] In one embodiment, a non-transitory storage medium having program code stored thereon is operable to configure at least one processor in a user equipment (UE) for ranging between the UEs, the program code including instructions for sending an initiation message to a second UE for initiating a first ranging session, receiving a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE, and conducting the combined ranging session by the second UE.

[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 description of the drawings]

[0016] [Figure 1] 1 illustrates a wireless communication system showing distributed communications, including ranging signaling to support multiple ranging sessions and / or positioning. [Diagram 2] FIG. 13 shows a signaling graph illustrating the timing and frequency of various messages that may be sent and received by an initiating UE and three responding UEs for a ranging or positioning session. [Figure 3A] FIG. 1 illustrates a system including multiple UEs participating in two independent ranging sessions that are initiated separately. [Figure 3B] 3B is a diagram similar to FIG. 3A, but showing a system in which independent ranging sessions are combined into a single combined ranging session. [Figure 4] FIG. 1 illustrates a visibility map that can be generated to determine the number of ranging signals missed during a combined ranging session. [Diagram 5] FIG. 1 illustrates a signaling flow for combining independent ranging sessions into a single ranging session. [Figure 6] 1 is a schematic block diagram illustrating certain example features of a UE configured to combine independent ranging sessions into a single ranging session. [Figure 7] 11 is a flowchart showing a method of ranging between UEs. [Figure 8] 11 is a flowchart showing a method of ranging between UEs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A distributed approach may be used for ranging and positioning of vehicles, road side units (RSUs), and pedestrians, avoiding the need for a central 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) by which vehicles can provide information necessary for autonomous driving.

[0018] For example, for safe operation of an autonomous vehicle, the relative location or distance to other vehicles needs to be determined. Various approaches may be used to derive the relative position between vehicles. For example, the relative position of the 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 by a user equipment (UE) in a vehicle, sometimes referred to as a V-UE, using direct communication systems, such as, for example, Dedicated Short-Range Communications (DSRC), Cellular Vehicle-to-Everything (C-V2X) communications, and even 5G New Radio (NR) communications, and may be received by other V-UEs, and / or UEs carried by infrastructure, such as, for example, an RSU, or pedestrians. The PRS signals are used to determine the distance to the broadcasting vehicle using, for example, one-way ranging, round trip time (RTT) positioning operations, or other standard positioning operations such as time of arrival (TOA), time difference of arrival (TDOA) or observed time difference of arrival (OTDOA).

[0019] In a distributed system, individual UEs can range to other nearby UEs using messages and positioning signals sent directly to the other UEs. For example, in an RTT-based ranging session, multiple messages and signals are sent and received by each UE. For example, an initial set of pre-ranging signal messages (pre-PRS messages) are sent and received to request and approve a ranging session, then ranging signals (PRS signals) for measurements are broadcast, and then a set of post-ranging signal messages (post-PRS messages) that exchange measurement payloads are broadcast. For example, for RTT-based ranging and positioning, time of arrival (TOA) and time of departure (TOD) measurements of the transmitted and received PRS signals can be provided in the post-PRS messages and used by each pair of UEs to determine the distance between the UEs. The pre-PRS and post-PRS messages can be sent over licensed spectrum to ensure reliability, while the PRS signals can be broadcast over unlicensed spectrum (e.g., to enjoy a larger available bandwidth in the UNI-III spectrum, for example). Ranging sessions in a distributed system, i.e., without infrastructure assistance for coordinating messaging, may result in multiple simultaneous ranging sessions that may include overlapping sets of participating UEs. Each ranging session may include multiple messages and ranging signals exchanged between participating UEs, and each ranging session may include multiple participating UEs. Thus, when multiple ranging sessions occur simultaneously, the signaling overhead may become excessively large and may impair ranging and positioning of UEs.

[0020] Although the distributed mechanism ensures that overhead is minimized, 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 broadcast their own pre-PRS signals separately to the same set of responding UEs, resulting in two independent ranging sessions involving the same responding UE and occurring simultaneously. The number of messages exchanged within each separate ranging session may be large, especially when there are multiple responding UEs. Furthermore, some signaling, such as PRS signals, may be broadcast over unlicensed spectrum, which may cause transmission delays due to the Listen-Before-Transmit (LBT) procedure used with unlicensed spectrum. Thus, when there are multiple overlapping ranging sessions, there may be significant overhead. The overhead may impair ranging and positioning in the session, for example, due to additional delays in receiving signaling.

[0021] Thus, in one embodiment, as discussed herein, independent ranging sessions can be combined into a single ranging session, thereby reducing the amount of signaling that must be exchanged between UEs. For example, a responding UE that receives multiple PRS pre-messages from multiple initiating UEs for separate ranging sessions can send a message to the initiating UE indicating that the separate ranging sessions should be combined and that the responding UE will initiate the combined ranging session. The responding UE then becomes the initiating UE by sending a PRS pre-message to initiate the combined ranging session. Upon receiving a message from the responding UE that the ranging sessions are combined, the original initiating UE ceases initiating the ranging session and becomes the responding UE for the combined ranging session.

[0022] FIG. 1 illustrates a wireless communication system 100 illustrating distributed communication, including ranging signaling to support multiple ranging sessions and / or positioning, as described herein. The wireless communication system 100 illustrates a first vehicle 102 having a first wireless device, e.g., V-UE 102, in wireless communication with another V-UE 104, illustrated as a second vehicle. The V-UE 102 and V-UE 104 may include, but are not limited to, an on-board unit (OBU), a vehicle or its subsystems, or various other communication devices. The V-UEs 102 and 104 function and provide communication on behalf of their associated vehicles, and thus may be referred to herein simply as vehicles 102 and 104 or UEs 102 and 104. The first UE 102 and second UE 104 may be, for example, two vehicles traveling on a road with other vehicles not illustrated.

[0023] 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 in a wireless communication network. V2X services include, for example, vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P), vehicle-to-infrastructure (V2I), and vehicle-to-network (V2N) services. The V2X standard aims to develop autonomous or semi-autonomous driving systems, such as advanced driver assistance systems (ADAS), that can be used to help drivers with critical decisions such as lane changes, speed changes, overtaking speeds, and assist with parking, as discussed herein. Low latency communications are used in V2X, and thus are suitable for precise relative positioning, for example, using ranging signals such as one-way ranging, RTT, TDOA, and the like.

[0024] Generally, there are two modes of operation of V2X services as defined in 3rd Generation Partnership Project (3GPP®) TS 23.285. One mode of operation uses direct wireless communication between the V2X entities, which may be referred to as sidelink communication. The other mode of operation uses network-based wireless communication between the entities. If desired, the two modes of operation may be combined or other modes of operation may be used.

[0025] The wireless communication system 100 can 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) Direct Communication (PC5) reference point defined in 3GPP TS 23.303, using wireless communication on the 5.9 GHz ITS band under IEEE 1609, Wireless Access in Vehicular Environments (WAVE), Intelligent Transport Systems (ITS), and IEEE 802.11p, or using other wireless connections directly between the entities. Thus, as shown, the UE 102 and the UE 104 can communicate directly using a vehicle-to-vehicle (V2V) communication link 103. The UE 102 and the UE 104 can also communicate directly with a roadside unit (RSU) 110 via vehicle-to-infrastructure (V2I) communication links 107 and 109, respectively. The RSU 110 may include a backhaul connection to the network, shown by wired connection 111, but this may be via a wireless Uu interface to a base station. 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 the 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 be used for ranging with the UE 102, 104, or other UEs, and since the location of the RSU 110 is precisely known, the RSU 110 may be used as an anchor UE by which the location of the UE 102, 104, or other UEs can be determined. The RSU 110 may be sometimes referred to as a UE 110 herein.The UEs 102, 104 and UE 110 may use the direct communication links to communicate with additional entities, such as an additional vehicle, a UE 112 carried by an RSU or a pedestrian 114. For example, the UE 102 may communicate with the UE 112 via a V2V communication link 113, the UE 104 may communicate with the UE 112 via a V2V communication link 115, and the UE 110 may communicate with the UE 112 via a V2I communication link 117.

[0026] 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 of the V2X entity, as well as other information in messages, such as Common Awareness Messages (CAMs) and Distributed Notification Messages (DENMs) or Basic Safety Messages (BSMs), which may be used for, for example, ADAS or safety use cases.

[0027] In other embodiments, the UE 102 and the UE 104 may communicate indirectly with each other, e.g., through the RSU 110 via V2I communication links 107 and 109, respectively, or through other network infrastructure (not shown), e.g., using cellular vehicle-to-everything (CV2X). For example, the vehicles may communicate through base stations in a Radio Access Network (RAN), such as an evolved Node B (eNB) or next generation evolved Node B (ng-eNB) in LTE wireless access and / or an evolved LTE (eLTE) wireless access or NR Node B (gNB) in fifth generation (5G) wireless access.

[0028] The UEs 102 and 104 can initiate and conduct a ranging / positioning session, including sending a pre-PRS message, broadcasting a PRS, and sending a post-PRS message over links 103, 107, 109, 113, or 115 that can determine the distance or relative position between the UEs 102 and 104. The PRS broadcast by the UEs 102 and 104 may be any signal suitable for ranging, for example, as defined for DSRC or C-V2X. The PRS may be broadcast on licensed or unlicensed spectrum. For example, in some embodiments, the PRS may be broadcast on 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 broadcasted on an unlicensed spectrum, a Listen Before Transmit (LBT) protocol may be utilized.

[0029] If UEs 102 and 104 broadcast a PRS in V2V link 103, the distance or relative position between UEs 102 and 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 distance and 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.

[0030] Direct wireless communication between the UEs 102 and 104 and the UEs 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.

[0031] For example, a UE, such as any of 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.

[0032] FIG. 2 illustrates, by way of example, a signaling graph 200 showing the timing and frequency of various messages that may be sent and received by an initiating UE (UEX) and three responding UEs (UEA, UEB, and UEC) for a ranging or positioning session. For example, FIG. 2 illustrates a possibility message 201 and an RTT-based ranging session 202 during which multiple messages are sent between the initiating and responding UEs, including a pre-PRS message 204 to request and approve the ranging session, a PRS signal 206 for measurements, and a post-PRS message 208 to exchange measurement payloads. Each set of pre-PRS 204, PRS 206, and post-PRS 208 can be considered to be a single unit or PRS cycle. Each PRS cycle includes a pre-PRS message 204, a PRS signal 206, and a post-PRS message 208, and thus may be referred to herein as a ranging session 202. The ranging sessions (PRS cycles) may be periodic with period T_r, and the possibility messages may be periodic with period T_c, where T_r>T_c. In Fig. 2, signaling from the initiator UEX is shown by a white box labeled "X", signaling from the first responder UEA is shown by a gray box labeled "A", signaling from the second responder UEB is shown by a shaded box labeled "B", and signaling from the third responder UEC is shown by a black box labeled "C". The signaling from the initiator UEX is the first box in each of the pre-PRS message 204, PRS signal 206, and post-PRS message 208, followed by the responding UEs (UEA, UEB, and UEC).

[0033] As shown, UEs, including initiating and responding UEs, may broadcast a possibility message 201. The possibility message is not part of a ranging session, but may include information that may be used by the initiating UE to initiate a ranging session with a selected UE. For example, the possibility message may be on the ITS spectrum and may include the UE ID, the ranging capability of the UE, the channel the UE is configured to use, MIMO (multiple-input multiple-output) capability, etc. The possibility message may additionally indicate whether the UE needs to determine its location, or if its location is known, it may act as an anchor UE for positioning other UEs. The possibility message may additionally indicate whether the UE is capable of combining a ranging session or allowing the initiated ranging session to be combined with another ranging session. It should be understood that while FIG. 2 illustrates the possibility message 201 as having the same order as the messages in the ranging session 202, the order may actually be different.

[0034] A PRS pre-message 204 (e.g., a pre-ranging message) is used by UEs to request and acknowledge a ranging session. As shown, the PRS pre-message 204 may be transmitted on a licensed spectrum to ensure reliability. The PRS pre-message 204 may be broadcast or unicast, for example, by a radio resource control (RRC) connection. An initiator UEX broadcasts an initial PRS pre-message 204 (PrePRSRequest) to initiate a ranging session between an initiating UE and a responding UE and to provide information for the ranging session (illustrated by a white box labeled X). For example, the PRS pre-message 204 from an initiating UE may include the IDs of the participating UEs, i.e., initiator and responder IDs. The PRS pre-request message may include a ranging session ID, a channel for the PRS broadcast by the initiator UEX and responder UE, a PRS broadcast time, a maximum listen before transmit (LBT) time, etc. The PRS pre-request message from the initiator UEX may include, for example, the PRS ID to be used by the initiating UE and, in some embodiments, the PRS ID to be used by the responding UE. If the PRS ID is fixed across multiple PRS exchanges (e.g., for multiple units in the ranging session 202), the initiating UE may include an ID associated with the current PRS exchange, such as, for example, a session ID. The initiating UE may determine when the PRS signal 206 will be transmitted, which may be configured, for example, at higher layers in the initiating UE. The initiating UE may indicate the timing of the PRS by sending a time slot number that is close to the desired PRS transmission time. In some embodiments, the time slot may be subject to local clock error. The initiating UE may further provide the timing at which the PRS will be sent by the responding UE and the maximum LBT time or other maximum predetermined delay for the broadcast of the PRS. The initiating UE may further indicate the frequency that will be used to broadcast the PRS signal 206 by the initiating UE and the responding UE.For example, the frequency of the PRS may be selected from an available set of total bandwidth, or the frequency of the PRS may be selected by detecting interference and choosing one or more channels whose average interfering reference signal received power (RSRP) is below a threshold. The initiating UE may indicate the number of PRS cycles to be performed during the ranging session 202. The number of PRS cycles may be configured by higher layers. For example, the PRS pre-message for each PRS cycle may indicate the current PRS cycle relative to the total PRS cycles requested, where the number of current cycles increments after the completion of each cycle.

[0035] An initial PRS pre-request message from the initiating UE is received and decoded by the responding UEs identified in the initial PRS pre-message. In response, the responding UEs can send PRS pre-messages 204 (illustrated by gray, shaded, and black boxes labeled A, B, and C, respectively) that can acknowledge the PRS pre-request message, which can additionally provide information for the ranging session. For example, each responding UE can determine the timing of its PRS signal 208 based on, for example, the timing of the initiating UE's PRS timing plus a delay that can be based on hardware constraints and interference levels as well as the number and order of responding UEs. For example, the delay can be relatively low when the PRS processing time is small and ambient interference is low, and relatively high when the PRS processing time is high and ambient interference is high. The responding UE can indicate the determined time of its PRS by sending a time slot number that is close to the determined PRS transmission time. In some embodiments, the time slots may be subject to local clock error. Each responding UE may indicate the PRS ID it will use, or may indicate that it will use the PRS ID indicated in the initial PRS pre message. If the PRS ID is fixed across multiple PRS exchanges (e.g., for multiple PRS cycles within the ranging session 202), the responding UE may include an ID associated with the current PRS exchange, such as, for example, a session ID, received in the initial PRS pre message from the initiating UE. The responding UE may broadcast a PRS pre message 204 that can be received by the initiating UE (and other responding UEs). In some embodiments, each responding UE may transmit the PRS pre message 204 using unicast over an RRC connection to the initiating UE.

[0036] PRS signals 206 are exchanged by participating UEs. The initiating UE and responding UE know the expected timing and frequency of the PRS signal and know the PRS ID (and any session ID used by the exchanged signals) used to broadcast the PRS signal 206. The PRS signal 206 may be, for example, a quadrature phase shift keying (QPSK) modulated pseudo-noise (PN) sequence and may include a ranging session ID. The PRS signal 206 may be broadcast on an unlicensed spectrum that may be subject to LBT constraints. In some embodiments, when using an unlicensed spectrum, the initiator UEX may reserve the transmissions of the responding UEs UEA, UEB, and UEC, such that the responding UEs may not need to perform an LBT. For example, the initiator UEX broadcasts its PRS signal 206 (white box labeled X) at a determined time indicated in the initial pre-PRS message 204. In some embodiments, the initiating UE broadcasts its PRS signal at a determined time plus a random waiting time due to LBT constraints when the PRS signal is deployed in an unlicensed spectrum. In some embodiments, the LBT may be a Category 2 LBT with fixed-window clear channel assessment (CCA) or a Category 4 LBT with variable-window CCA. The initiating UE uses the PRS signal corresponding to the PRS ID and uses the frequency resources indicated in its initial PRS pre-message 204. The initiating UE stores the time when the PRS signal was broadcast and the responding UE stores the time when the PRS signal was received. In some embodiments, the time may be subject to local clock error.

[0037] Similar to the initiating UE, each responding UE broadcasts its PRS signal 206 (indicated by the gray, shaded, and black boxes labeled A, B, and C, respectively) at the time and frequency assigned by the initiating UE in the initial PRS pre-message 204. In some embodiments, each responding UE may broadcast its PRS signal at a determined time plus a random waiting time due to LBT constraints when the PRS signal is deployed in an unlicensed spectrum. In some embodiments, the LBT may be a Category 2 LBT with a fixed-window CCA or a Category 4 LBT with a variable-window CCA. Each responding UE uses a PRS signal corresponding to the PRS ID indicated in its PRS pre-message 204. Each responding UE stores the time its PRS signal was broadcast, and the initiating UE (and optionally other responding UEs) stores the time the PRS signal from each responding UE was received. In some embodiments, the time may be subject to local clock error.

[0038] In this way, each UE records the time of departure (ToD) of its broadcast PRS and measures the time of arrival (ToA) of PRS signals received from other UEs. The PRS signals may be any signal suitable for ranging, such as QPSK modulated PN sequences, e.g., as defined for DSRC or C-V2X. The ToA and ToD resolution of the PRS signals increases with increasing frequency bandwidth. In some embodiments, the angle of departure (AoD) and angle of arrival (AoA) of the PRS signals being broadcast and received may also be measured. Broadcasting on unlicensed spectrum is advantageous because of the availability of wider frequency bands. For example, in some embodiments, the PRS may be broadcast on one or more UNII radio bands, including, e.g., 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.

[0039] A PRS-post message 208 is sent by each UE to exchange measurement payloads. As shown, the PRS-post message 208 may be transmitted over licensed spectrum to ensure reliability. In some embodiments, the PRS-post message 208 may be broadcast or unicast over an RRC connection. The initiator UE X sends its PRS-post message 208 (shown as a white box labeled X) to indicate when it broadcasts the PRS signal 206 (ToD) and when the PRS signal from the responding UE is received (ToA). In some embodiments, the ToA may be calculated as a relative time to the ToD of its broadcast PRS signal, and the relative time may be provided. In some embodiments, the relative time may be approximated to the nearest multiple of a time scale shared by the initiating UE and the responding UE. In some embodiments, the initiating UE may provide an indication of its location in the PRS-post message 208, if known. For example, the location of the initiating UE may be a location at a particular time, such as the broadcast time of its PRS signal or the time of arrival of the PRS signal from the responding UE. The post-PRS message 208 may further include the AoD of that PRS signal 206 and the AoA of the PRS signal 206 received from the responding UE, the orientation of the initiating UE, a broadcast indication of the PRS signal 206, a reception indication of the PRS from the responding UE, and other relevant measurements such as, for example, map information, location of reflectors relative to the UE, etc.

[0040] Like the initiating UE, each responding UE sends its post-PRS signal 208 (indicated by gray, shaded, and black boxes labeled A, B, and C, respectively) to provide a measurement payload. Each responding UE can indicate whether it received a PRS signal from the initiating UE, and can indicate when it broadcast the PRS signal 206 (ToD) and when the PRS signal from the initiating UE (and optionally from other responding UEs) was received (ToA). In some embodiments, the ToD may be calculated as a relative time to the ToA of the PRS signal from the initiating UE (and optionally to the ToA of the PRS from the other responding UEs). In some embodiments, the relative time may be approximated to the nearest multiple of a time scale shared by the initiating UE and the responding UE. In some embodiments, the responding UE can provide an indication of its location in the post-PRS message 208, if known. For example, the location of the responding UE provided may be a location at a particular time, such as the time of arrival of the PRS signal from the initiating UE, or the time of departure of its broadcast PRS signal. The post-PRS message 208 may further include the AoD of that PRS signal 206 and the AoA of the PRS signal 206 received from the initiator UE (and optionally from other responding UEs), the orientation of the initiating UE, a broadcast indication of the PRS signal 206, a reception indication of the PRS from the responding UEs, and other relevant measurements, such as, for example, map information, location of reflectors relative to the UE, etc.

[0041] After receiving the PRS post-message, the initiating UE may calculate its distance (and in some embodiments its location), for example using a Kalman filter, and then transmit the next cycle of PRS pre-messages at a time either dictated by higher layers or determined autonomously by the initiating UE.

[0042] The time between the first pre-PRS message 204 and the last post-PRS message 208 may be the duration of the ranging session, which may be, for example, 100 milliseconds. The duration of each broadcast 206 signal 206 may be, for example, 47 microseconds. In some implementations, multiple PRS cycles, such as, for example, multiple instances of pre-PRS message 204, PRS 206, and post-PRS message 208, may be used together to provide greater accuracy.

[0043] Both the initiating UE and the responding UE can determine the distance between itself and each other UE in the ranging session based on the ToD and ToA of the broadcast PRS signal. For example, the RTT between any pair of UEs (which may be any pair of an initiating UE and a responding UE) can be calculated by multiplying the RTT by the PRS i Signal ToD i and ToA i (i=1 for the PRS broadcast from the first UE and i=2 for the PRS broadcast by the second UE), it can be determined as the difference between ToD1 and ToA2 minus the difference between ToA1 and ToD2. RTT=(ToD1-ToA2)-(ToA1-ToD2) Equation 1

[0044] The RTT value is the round trip time of a signal, therefore the range or distance between UE1 and UE2 can be determined as RTT / 2c, where c is the speed of light.

[0045] If the location of one or more responding UEs is known, the distance between the initiating UE and the responding UE can be used along with the known location of one responding UE to determine the location of the other UE, thus making the ranging session a positioning session. A responding UE with a known location that can be used for positioning may be referred to herein as an anchor UE. The location of the anchor UE may be provided to other UEs through messaging, for example in a pre-PRS message or a post-PRS message. If the distance to multiple anchor UEs is determined, the locations of the multiple anchor UEs may be used in multilateration to determine the location of the initiating UE (or other responding UEs).

[0046] For example, angle measurements such as AoD and AoA can be used, for example, to assist in positioning. As an example, the relative positions of the two UEs can be determined based on the distance between the two UEs and the measured AoA. With the relative positions of the UEs determined, if the actual position of one UE is known (e.g., may be provided in the pre-PRS message 204 or post-PRS message 208), the actual position of the other UE can be determined. If the positions of the two UEs are known by a third UE, the distance between the third UE and each of the other two UEs generates two possible positions of the third UE, which can be resolved based on the AoD / AoA information. AoD can be useful, for example, when the resolution of the AoA is unsatisfactory or inaccurate. AoD can be measured, for example, based on the known orientation of the UE (e.g., determined by a magnetometer) and the direction of the transmitted signal relative to the UE (e.g., relative to the UE's antenna array used for beamforming). The AoA may be measured based on the phase difference of received signals at different antenna elements of an antenna array and the known orientation of the UE (e.g., determined by a magnetometer). Additionally, geographic constraints can be used to assist the positioning, for example, by constraining the possible positions of the vehicle based on locations that are accessible to the vehicle, such as roads.

[0047] As mentioned above, due to the distributed mechanism for ranging, it is possible that multiple UEs can approximately simultaneously initiate independent ranging sessions involving at least some of the same responding UEs. For example, two initiating 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 UEs and occurring at the same time.

[0048] 3A illustrates a system 300 including multiple UEs participating in two independent ranging sessions separately initiated by UE1 302 and UE2 304, which may be, by way of example, a pedestrian UE, a vehicular UE, etc. For example, initiating UE1 302 and initiating UE2 304 may not be able to detect each other due to distance, for example, and may initiate the ranging session by sending a PRS pre-message (indicated by arrows 303 and 305, respectively) to responding UEs including UEA 310A, UEB 310B, and UEC 310C, which may each be an RSU, a pedestrian UE, a vehicular UE, etc., collectively referred to as UE 310. The PRS pre-messages 303 and 305 may be broadcast or unicast messages.

[0049] Two simultaneous ranging sessions involving the same set of responder UEs, as shown in Figure 3A, result in significant overhead. For example, each PRS cycle in a ranging session initiated by UE1 302 includes a UE1 PRS pre-message, a UEA / UEB / UECPRS pre-message, a UE1 PRS signal, a UEA / UEB / UEC PRS signal, a UE1 PRS post-message, and a UEA / UEB / UECPRS post-message, while each PRS cycle in another ranging session initiated by UE2 304 includes a UE2 PRS pre-message, a UEA / UEB / UECPRS pre-message, a UE2 PRS signal, a UEA / UEB / UEC PRS signal, a UE2 PRS post-message, and a UEA / UEB / UECPRS post-message. For example, since the PRS signals are constrained by the LBT procedure, the resulting large signaling overhead will impair the ranging and positioning of the initiating UEs UE1 and UE2.

[0050] Therefore, it may be desirable to combine the two ranging sessions, for example, by changing the initiating UEs, for example, from two initiating UEs (UE1 302 and UE2 304) to a single initiating UE, for example, UEA 310A.

[0051] FIGURE 3B illustrates, by way of example, a system 350 in which independent ranging sessions, such as those illustrated in FIGURE 3A, are combined into a single ranging session. System 350 is similar to system 300 illustrated in FIGURE 3A, and like designations are the same.

[0052] In Fig. 3B, after the existence of multiple proximity ranging sessions, such as the ranging sessions initiated by UE1 302 and UE2 304 in Fig. 3A, is confirmed, UEA 310A can combine the two ranging sessions into a single ranging session including both initiating UEs, such as UE1 302 and UE2 304 and the responding UE 310. As shown in Fig. 3B, UEA 310A, which was the responding UE in both ranging sessions initiated by UE1 302 and UE2 304 in Fig. 3A, can act as the initiating UE for the combined ranging session in Fig. 3B. The responding UE (e.g., UEA 310A) can initiate a new combined ranging session including participants (shown in Fig. 3A) from the separate ranging sessions. 3B, for example, UEA 310A may send a PRS pre-message (indicated by arrows 353-1, 353-3, 353-B, 353-C (sometimes collectively referred to as PRS pre-message 353)) to responding UEs of the new joint ranging session, such as, for example, UEl 302, UE2 304, UEB 310B, and UEC 310C. The PRS pre-message 353 may be a broadcast or unicast message.

[0053] A joint ranging session may then proceed with UEA-310A acting as an initiating UE and UE1 302, UE2 304, UEB 310B, and UEC 310C acting as responding UEs. The joint ranging session may include pre-PRS messages, PRS signals, and post-PRS messages as described above. The post-PRS messages in the joint ranging session are broadcast so that the original initiating UEs (UE1 302 and UE2 304), acting as responding UEs in the joint ranging session, receive PRS measurement information from each responding UE to determine their distances to, and in some embodiments the locations of, the other new initiating UE (UEA-310A) and the other responding UEs UEB 310B and UEC 310C.

[0054] The initiating UE of the combined ranging session (e.g., UEA 310A) may subsequently initiate combined ranging sessions for a predetermined time or until the participants of the combined ranging session are no longer visible to the other participants. For example, in a combined ranging session, the PRS signals from each participant (e.g., from initiating UEA-310A and responding UE1 302, UE2 304, UEB 310B, and UEC 310C) should be visible to each of the other participants. When the PRS signals from the participants of the combined ranging session become invisible to the other group members, for example, more than N times, the combined ranging session may end and the original initiating UEs 302 and 304 may begin initiating separate ranging sessions again. For example, the initiating UEA 310A of the combined ranging session can send a message (e.g., a V2X message) to the original initiating UEs 302 and 304 indicating that the combined ranging session should be separated, and the UEA 310A can stop initiating the new combined ranging session and the original initiating UEs 302 and 304 can begin initiating a separate ranging session with appropriate responding UEs, which may be a different set of responding UEs than those included in the combined ranging session.

[0055] For example, in one embodiment, an initiating UE (e.g., UE A 310A) of a joint ranging session can monitor which PRS signals from other participants are seen (or lost) in each joint ranging session. FIG. 4 illustrates, by way of example, a visibility map 400 that can be generated to determine the number of PRS signals lost during each joint ranging session. As illustrated, each participating UE of the joint ranging session can be included in the visibility map 400, although in some embodiments, only the original initiating UEs, e.g., UE1 and UE2, and the initiating UE A can be considered. Along each row, the visibility map 400 indicates whether the UE receives a PRS signal from another participating UE. For example, in row 402, the initiating UE A 310A is shown as receiving PRS signals from UE1, UE2, and UE C, but not from UE B. Ideally, the visibility of the PRS signals is symmetric, ie, if the PRS signal from UEB 310B is visible to UEA 310A, then the PRS signal from UEA 310A should be visible to UEB 310B.

[0056] The initiating UEA 310A may monitor multiple instances of the combined ranging session, and if the number of PRS signals missed from other participants in the combined ranging session exceeds a predefined threshold N, the combined ranging session may be separated. In some embodiments, the threshold N may be used for all combined ranging sessions, or the threshold N may be used for a modest number of previous combined ranging sessions, such as, for example, N of the last 10 combined ranging sessions. In some embodiments, the initiating UEA 310A may additionally or alternatively monitor post-PRS messages from each responding UE to determine the number of PRS signals missed by each responding UE, and may separate the combined ranging session if the responding UE misses more than the threshold number of PRS signals. In particular, the initiating UEA 310A may take into account the number of PRS signals missed by the original initiating UE, e.g., UE1 and UE2, while the number of PRS signals missed by other responding UEs, e.g., UEs and UEC, may be irrelevant to whether the combined ranging session should be separated or not. In another embodiment, each responding UE, particularly the original initiating UEs, e.g., UE1 and UE2, may separately monitor the number of missed PRS signals and may send a message to the initiating UE A 310A indicating when more than a threshold number of PRS signals are missed. Note that the PRS signals from the original initiating UEs 302 and 304 may not be visible to each other, and therefore it may not be desirable to consider PRS signals missed between the original initiating UEs when determining whether a threshold number of PRS signals have been missed.

[0057] The initiating UEA 310A may determine whether other participating UEs, and in particular the original initiating UEs, e.g., UE1 and UE2, have received PRS signals from other UEs based on their post-PRS messages or other messages provided by other UEs. Multiple visibility maps may be combined to determine whether the total number of PRS signals of all combined ranging sessions (or a modest number of previous combined ranging sessions) is greater than a threshold. For example, the initiating UEA 310A may only monitor the number of PRS signals that it has missed, or the number of PRS signals that a combination of participating UEs, e.g., the original initiating UEs, e.g., UE1 and UE2, have missed. In some embodiments, the initiating UEA 310A may only consider the PRS signals that the original initiating UEs, e.g., UE1 and UE2, have missed.

[0058] FIG. 5 illustrates an example of a signaling flow 500 for combining independent ranging sessions into a single combined ranging session. For example, the UE entities 302, 304, 310A, 310B, and 310C may be V-UEs, RSUs, and / or pedestrian UEs, such as UEs 102, 104, 110, or 112 shown in FIG. 1 and discussed in FIG. 3A and FIG. 3B and FIG. 4. The original initiating UEs may be UE1 302 and UE2 304, and the original responding UEs may be UE A 310A, UE B 310B, and UE C 310C. It should be understood that there may be additional (or fewer) responding UEs with additional (or fewer) communications similar to those shown in FIG. 5. As illustrated, the communications between the UEs in FIG. 6 may be direct communications between the entities and may not involve infrastructure devices, such as base stations, to forward messages between the entities. It should be further understood that FIG. 5 illustrates signaling for combining independent ranging sessions, and that additional or other communications may be transmitted between one or more of the UEs illustrated in FIG. 5 in broadcast, unicast, multicast, or other sidelink signaling, or through one or more infrastructure devices, such as RSU 110 or a base station.

[0059] In phase 1A, one or more ranging and / or positioning sessions are performed by UE1 302 acting as an initiating UE and UEA 310A, UEB 310B, and UEC 310C acting as responding UEs. Participating UEs in phase 1A ranging session can be identified / selected based on a possibility message, such as message 201 shown in FIG. 2, in which the UEs provide their identifiers, ranging capabilities, configured channels, etc. For example, the possibility message from responding UEs, such as UEA 310A, UEB 310B, and UEC 310C, can further indicate whether the UEs are capable of combining ranging sessions, while the possibility message from initiating UE1 302 can indicate whether the initiated ranging session can be combined with another ranging session. Phase 1A ranging session may not include UE2 304. For example, as discussed in FIG. 2, each ranging session may include, for example, an initial pre-ranging message (e.g., PRS pre-message) from an initiating UE and a response pre-ranging message (e.g., PRS pre-message) from a responding UE. Each ranging session may further include ranging signals (PRS signals) from the initiating UE and the responding UE, and post-ranging signals (PRS post-messages) from the initiating UE and the responding UE carrying measurement information of the ranging signals, as discussed in FIG. 2. The initiating UE may determine a distance to each responding UE using the measurement information. The responding UE may similarly determine distances or timing information to the initiating UE and other responding UEs that may be used for clock synchronization. The post-ranging message from the anchor UE may include location information by which a position of the UE may be determined based on the location information and the determined distance to the anchor UE.

[0060] In phase 1B, similar to phase 1A, one or more ranging and / or positioning sessions are conducted by UE2 304 acting as an initiating UE and UEA 310A, UEB 310B and UEC 310C acting as responding UEs. Participating UEs in the phase 1B ranging session may be identified / selected based on a possibility message, such as message 201 shown in FIG. 2, in which the UEs provide their identifiers, ranging capabilities, configured channels, etc. For example, the possibility message from responding UEs, such as UEA 310A, UEB 310B and UEC 310C, may further indicate whether the UEs are capable of combining ranging sessions, while the possibility message from initiating UE2 304 may indicate whether the initiated ranging session may be combined with another ranging session. The phase 1B ranging session may not include UE1 302. The ranging and / or positioning session initiated by UE2 304 may be contiguous and simultaneous with the ranging and / or positioning session of phase 1A.

[0061] In stage 2A, the UEA 310A decides to combine the simultaneous ranging sessions initiated by the UEs 302 and 304. The UEA 310A can determine whether to combine the simultaneous ranging sessions, for example, when the possibility messages (e.g., in message 201 in FIG. 2) from the initiating UEs 1 302 and UE2 304 indicate that the ranging sessions initiated by them may be combined with other ranging sessions. For example, the UEA 310A can confirm the existence of multiple simultaneous ranging sessions by receiving pre-PRS messages from the initiating UEs 302 and 304 in the ranging sessions of stage 1A and stage 1B. The UEA 310A can confirm the existence of multiple independent ranging sessions, for example, based on the pre-PRS messages in each ranging session, which may enumerate all participating UEs (including the initiating UEs 302 and 304 and the responding UEs 310, respectively). For example, in some embodiments where the pre-PRS messages 303 and 305 are unicast, the UEA 310A can verify the presence of multiple adjacent ranging sessions by sending multiple PRS cycles in both phase 1A and phase 1B ranging sessions within a certain time period. For example, the UEA 310A can detect whether the number of PRS signals received from the initiating UEs 302 and 304 exceeds a predetermined number (X) within a certain time period, such as every second (X can be any value between 0 and 10, given that the PRS period is 100 ms, i.e., 100 ms=1 s / 10 PRS). In some embodiments, the UEA 310A can detect the number of pre-PRS and / or post-PRS messages received from the initiating UEs 302 and 304 in the phase 1A and phase 1B ranging sessions within a certain time period. The post-PRS messages can include, for example, the time of departure (ToD) of the broadcast PRS signal and can be used to aid in determining the number of PRS cycles from each initiating UE.In some embodiments, the UEA 310A may further detect the number of PRS broadcast from responding UEs, such as UEB 310B and UEC 310C, within the time period. If the UEA 310A detects multiple PRS cycles from multiple ranging sessions within the time period, the UEA 310A may determine that the independent ranging sessions from stages 1A and 1B are simultaneous and should be combined.

[0062] In stage 2B, one or more other responding UEs, denoted as UE B 310B, may also determine that the ranging sessions from stages 1A and 1B should be combined as described in stage 2A.

[0063] In stage 3A, the UEA 310A may send a combining message (e.g., a V2X message) to each of the initiating UEs 302 and 304 indicating that the ranging sessions will be combined. The UEA 310A may indicate whether it can act as a positioning anchor for the positioning of the UEs 302 and 304 (i.e., the location of the UEA 310A is precisely known). The UEA 310A may further measure one or more power characteristics of the PRS signals broadcast by each of the initiating UEs 302 and 304 during the ranging sessions of stages 1A and 1B and may provide an indication of the power characteristics of the PRS signals from the initiating UEs 302 and 304 in the combining message of stage 3A. For example, the UEA 310A may measure the RSRP of the PRS signals from both UE1 302 and UE2 304 and determine an average of the RSPR of the PRS signals. The UEA 310A may include the average RSRP of the PRS signals from UE1 302 and UE2 304 in the combined message.

[0064] In stage 3B, if the UEB 310B has determined to combine the ranging sessions in stage 2B, the UEB 310B may also send a combining message (e.g., a V2X message) to each of the initiating UEs 302 and 304 indicating that the ranging sessions are combined, and may provide an indication of whether the UEB 310B can act as a positioning anchor, as well as an indication of the measured power characteristics of the PRS signals, such as the average RSRP of the PRS signals from UE1 302 and UE2 304 as measured by the UEB 310B.

[0065] In steps 4A and 4B, the initiating UE 302 and the initiating UE 304 can select an initiating UE for a combined ranging session and stop initiating an independent ranging session, respectively. Thus, when a message for combining ranging sessions is received from the UE A 310A, the two initiating UEs, e.g., UE A 302 and UE B 304, stop initiating new ranging sessions, i.e., any subsequent initiation of a ranging session by the two initiating UEs, e.g., UE A 302 and UE B 304, is monitored. The initiating UEs 302 and 304 wait to become responding UEs of the combined ranging session and select an initiating UE for the combined ranging session. For example, if only one responding UE (e.g., UE A 310A) sends a combined message, the UEs 302 and 304 can select that single responding UE. If the initiating UEs 302 and 304 receive combining messages from two or more responding UEs indicating that their ranging sessions will be combined, e.g., in stages 3A and 3B, the initiating UEs 302 and 304 can determine which responding UE will serve as the new initiating UE in the combined ranging session based on criteria such as anchor status and power characteristics provided in the combining messages from each responding UE. For example, responding UEs that have the capability to serve as anchor points for positioning may be prioritized over responding UEs that cannot serve as anchor points and / or responding UEs with high average RSRP may be prioritized over responding UEs with low average RSRP. In some embodiments, the initiating UEs 302 and 304 can determine which responding UE will be the new initiating UE based on a combination of criteria that may be ordered, such as anchor with high average RSRP>anchor with low average RSRP>non-anchor with high average RSRP>non-anchor with low average RSRP. Other criteria, combinations of criteria, or orders may be used as desired.

[0066] In stage 5, each initiating UE 302 and 304 provides a response combined message (e.g., a V2X message) to the selected responding UE (e.g., UEA 310A in FIG. 5) indicating that it will be the responding UE and providing an indication that the responding UE should initiate a combined ranging session. The responding UE that sent the combined message to the initiating UEs 302 and 304 can initiate a combined ranging or positioning session if it receives a response message from the initiating UEs 302 and 304.

[0067] In stage 6, UEA 310A initiates one or more joint ranging or positioning sessions including the original initiating UEs, i.e., UEl 302 and UE2 304, along with UEB 310B and UEC 310C as responding UEs. The joint ranging sessions may be similar to the independent ranging sessions of stages 1A and 1B, except that UEA 310A initiates the ranging session and the previous initiating UEs (UE1 302 and UE2 304) serve as responding UEs. For example, as discussed in FIG. 2, each ranging session may include, for example, an initial pre-ranging message (such as a pre-PRS message) from the initiating UE and a response pre-ranging message (such as a pre-PRS message) from the responding UE. Each ranging session may further include a ranging signal (PRS signal) from the initiating UE and the responding UE, and a post-ranging signal (post-PRS message) from the initiating UE and the responding UE carrying measurement information of the ranging signal, as discussed in FIG. 2. The post-ranging message from the anchor UE may include location information by which the UE's position can be determined based on the location information and the determined distance to the anchor UE. The post-PRS message in the joint ranging session is broadcast as discussed above for the previous initiating UEs (UE1 302 and UE2 304) acting as responding UEs in the joint ranging session to receive PRS measurement information from each responding UE to determine their distances to the other new initiating UE (UEA-310A) and other responding UEs UEB 310B and UEC 310C, and in some embodiments, their positions. UEA 310A, UEB 310B, and UEC 310C may similarly determine distances or timing information to the participating UEs that can be used for clock synchronization.

[0068] In step 7A, the initiating UEA 310A may determine whether the coupled ranging session of step 6 should be separated. In some embodiments, as illustrated by optional step 7B, other UEs may determine whether the coupled ranging session of step 6 should be separated. It should be understood that while FIG. 5 illustrates steps 7A and 7B as being performed after step 6, in practice steps 7A and 7B are performed simultaneously with the coupled ranging session of step 6. In step 7A, for example, the initiating UEA 310A of the coupled ranging session may continue to initiate the coupled ranging session for a predetermined time or until a participant of the coupled ranging session is no longer visible by the other participant. For example, the initiating UEA 310A may monitor which PRS signals from other participants are visible (or lost) in each coupled ranging session, for example, as described above with reference to FIG. 4. The initiating UEA 310A may monitor multiple coupled ranging sessions, and if the number of PRS signals from other participants of the coupled ranging session exceeds a predetermined threshold N, the coupled ranging session may be separated. In some embodiments, the threshold N may be used for all combined ranging sessions, or for a modest number of prior combined ranging sessions, such as, for example, N of the last 10 combined ranging sessions. In some embodiments, the initiating UEA 310A may additionally or alternatively monitor the post-PRS messages from each responding UE to determine the number of PRS signals each responding UE has missed, and may separate the combined ranging session when more than a threshold number of PRS signals are missed by the responding UE. In another embodiment, each responding UE may separately monitor the number of missed PRS signals (e.g., as shown by step 7B) and may send a message to the initiating UEA 310A indicating when more than a threshold number of PRS signals are missed. The initiating UEA 310A may determine whether other participating UEs have received PRS signals based on their post-PRS messages or other messages provided by other UEs.The initiating UEA 310A may, for example, only monitor the number of PRS signals that it itself has missed or that any combination of participating UEs (which may include or exclude the original initiating UEs 1 and 2) have missed. In some embodiments, the initiating UEA 310A may only consider the PRS signals that the original initiating UEs 1 and 2 have missed.

[0069] In stage 8, when the UEA 310A determines that the coupled ranging session should be separated, the UEA 310A sends a separation message (e.g., a V2X message) to the original initiating UEs 302 and 304 indicating that the coupled ranging session should be separated, and stops initiating the coupled ranging session.

[0070] At steps 9A and 9B, the original initiating UEs 302 and 304 begin initiating separate ranging sessions with suitable responding UEs, which may be the same or a different set of responding UEs than those included in the joint ranging session.

[0071] Thus, the decision to merge and separate ranging sessions can be performed autonomously and without central network assistance. Multiple proximate ranging sessions can be combined to reduce signaling overhead and, as a result, increase ranging accuracy between UEs across groups, and can be separated when the benefits of combined ranging sessions are reduced or lost.

[0072] FIG. 6 is a schematic block diagram illustrating certain exemplary features of a user equipment (UE) 600, which may be a UE 112 carried by an RSU 110 or a pedestrian 114 in a vehicle 102 or 104 as shown in FIG. 1, or any UE shown in FIG. 3A, FIG. 3B, FIG. 4, or FIG. 5. The UE 600 may be configured to act as a responding UE, such as, for example, responding UE A 310A, or as an initiating UE, such as, for example, initiating UE 1 302, where multiple independent and simultaneous ranging sessions are combined into a single combined ranging session as discussed herein. If the UE 600 is a V-UE, it may be configured to control autonomous driving of a vehicle, such as, for example, the vehicle 102. For example, the UE 600 may include a vehicle interface 605, whereby commands for autonomous driving may be provided to the vehicle and sensory inputs including speed and acceleration may be provided from the vehicle to the UE 600. The UE 600 may include, for example, one or more processors 602, a memory 604, an inertial measurement unit (IMU) 607 that may include, for example, an accelerometer, gyroscope, magnetometer, etc. that can be used to detect an orientation relative to a global or local reference frame and motion of the vehicle or one or more motion characteristics, a satellite positioning system (SPS) receiver 609 for determining, for example, a GPS position, and external interfaces including, for example, a wireless wide area network (WWAN) transceiver 610 and a wireless local area network (WLAN) transceiver 614 that may be operatively coupled to the non-transitory computer-readable medium 620 and the memory 604 by one or more connections 606 (e.g., buses, lines, fibers, links, etc.). The UE 600 may further include additional items not shown, such as a user interface that may include, for example, a display, a keypad, or other input devices, such as a virtual keypad on a display, through which a user may interface with the user device. In some example implementations, all or a portion of UE 600 may be in the form of a chipset or the like.

[0073] The transceiver 610 may be, for example, a cellular transceiver configured to transmit and receive direct communications within a wireless network, as shown in FIG. 1. The transceiver 610 may include a transmitter 611 enabled to transmit one or more signals over one or more types of wireless communication networks, and a receiver 612 for receiving one or more signals transmitted over one or more types of wireless communication networks. The transceiver 614 may be, for example, a short-range transceiver, and may be configured to transmit and receive direct communications within a wireless network, as shown in FIG. 1. The transceiver 614 may include a transmitter 615 enabled to transmit one or more signals including ranging signals (PRS signals) and pre-ranging (pre-PRS) and post-ranging (post-PRS) messages, and combine and separate messages across one or more types of wireless communication networks, and a receiver 616 for receiving one or more signals including, for example, PRS and pre-PRS and post-PRS messages, and combine and separate messages transmitted across one or more types of wireless communication networks. The transceivers 610 and 614 enable the UE 600 to communicate with transportation entities using a D2D communication link, such as DSRC, C-V2X, or 5G NR.

[0074] In some embodiments, the UE 600 may include an antenna 609, which may be internal or external. The antenna 609 may be used to transmit and / or receive signals processed by the transceiver 610 and / or the transceiver 614. In some embodiments, the antenna 609 may be coupled to the transceiver 610 and / or the transceiver 614. In some embodiments, measurements of signals received (transmitted) by the UE 600 may be performed at the connection points of the antenna 609 and the transceiver 610 and / or the transceiver 614. For example, the measurement reference points for received (transmitted) RF signal measurements may be the input (output) terminals of the receivers 612, 616 (transmitters 611, 615) and the output (input) terminal of the antenna 609. In a UE 600 with multiple antennas 609 or antenna arrays, the antenna connectors may be considered to be virtual points representing the aggregate output (input) of the multiple antennas. The phase difference of the received signals at multiple antennas or antenna arrays can be used to determine the AoA of the signal relative to the antenna array, which can be transformed to a global or local reference frame based on the known orientation of the UE 600, for example based on the orientation of the UE 600 relative to the global or local reference frame as measured by the IMU 607.

[0075] The one or more processors 602 may be implemented using a combination of hardware, firmware, and software. For example, the one or more processors 602 may be configured to perform functions described herein by implementing one or more instructions or program code 608 on a non-transitory computer-readable medium, such as the medium 620 and / or the memory 604. In some embodiments, the one or more processors 602 may represent one or more circuits configurable to perform at least a portion of a data signal computation procedure or process related to the operation of the UE 600.

[0076] The medium 620 and / or memory 604 may store instructions or program code 608, including executable code or software instructions that, when executed by the one or more processors 602, cause the one or more processors 602 to operate as a special purpose computer programmed to perform the techniques disclosed herein. As shown in the UE 600, the medium 620 and / or memory 604 may include one or more components or modules that may be implemented by the one or more processors 602 to perform the methods described herein. Although the components or modules are shown as software in the medium 620 executable by the one or more processors 602, it should be understood that the components or modules may be stored in the memory 604 or may be dedicated hardware either within the one or more processors 602 or external to the processor.

[0077] A number of software modules and data tables may be present in the medium 620 and / or memory 604 and utilized by the one or more processors 602 to manage both the communications and functionality described herein. It should be understood that the organization of the contents of the medium 620 and / or memory 604 as shown in the UE 600 is merely exemplary, such that the functionality of the modules and / or data structures may be combined, separated, and / or structured in various ways depending on the implementation of the UE 600.

[0078] The medium 620 and / or memory 604 may include a PRS pre-message module 622 that, when implemented by the one or more processors 602, configures the one or more processors 602 to generate and transmit or receive a pre-ranging message, such as a PRS pre-message, via the transceiver 614, for example, to initiate or acknowledge a ranging session. The PRS pre-message may be broadcast, multicast, or unicast (by an RRC connection). In some aspects, the PRS message may be transmitted and received over a licensed spectrum. The PRS pre-message may be an initiating PRS pre-message to initiate a ranging session or a responding PRS pre-message to acknowledge the initiating PRS pre-message. The PRS pre-message may include identifiers of the initiating UE and one or more responding UEs. The participating UEs may be determined, for example, from a possibility message received by the UE 600 or from monitoring multiple simultaneous ranging sessions and identifying participating UEs from the simultaneous ranging sessions. The PRS pre-message may further include ranging signal characteristics used for the ranging session and may include location information of the UE 600. For example, the pre-PRS message may include an identifier of the ranging signal as well as timing information (e.g., time slot number) of the ranging signal and the frequency that will be used to broadcast the ranging signal. For example, the frequency may be selected from an available bandwidth set and may be selected by sensing interference and choosing a channel that has an average interference RSRP below a threshold. In some embodiments, the pre-PRS message may include an indication of the number of PRS cycles requested and the current PRS cycle.

[0079] The medium 620 and / or memory 604 may include a PRS module 624 that, when implemented by the one or more processors 602, configures the one or more processors 602 to broadcast and receive a ranging signal to other UEs in a ranging session via the transceiver 614 as discussed herein. The ranging signal may be, for example, a PRS signal as discussed herein. The ranging signal may be broadcast at a determined time and at a frequency indicated via a PRS pre-message with an identifier. The ranging signal may be broadcast and received over an unlicensed spectrum and may be broadcast pursuant to Category 2 or Category 4 LBT constraints. For example, the one or more processors 602 may be configured to measure the ToD of the broadcast ranging signal and the ToA of the received ranging signal, and may be configured to measure the AoD of the broadcast ranging signal and the AoA of the received ranging signal.

[0080] The medium 620 and / or memory 604 may include a PRS post-message module 626 that, when implemented by the one or more processors 602, configures the one or more processors 602 to send and receive post-ranging messages to other UEs in a ranging session via the transceiver 614, as discussed herein. The PRS post-message may include, for example, an indication of the ToD, and in some embodiments, the AoD, of the broadcast ranging signal, and an indication of the ToA, and in some embodiments, the AoA, of the received ranging signal. In some embodiments, the ToD and ToA indications may be the difference between the ToD and the ToA. In some embodiments, the PRS post-message may include an indication of the location of the UE.

[0081] The medium 620 and / or memory 604 may include a ranging / positioning module 628 that, when implemented by the one or more processors 602, configures the one or more processors 602 to determine a distance to another UE based on the ToD and ToA of the broadcast and received ranging signals as measured by the UE 600 and received in a PRS post-message from the other UE. The processor 602 may be further configured to determine a position of the UE 600 based on, for example, one or more distances to the broadcasting UEs and their location information using multilateration or other suitable techniques discussed herein. For example, the one or more processors 602 may implement a Kalman filter or an extended Kalman filter to determine the distance to the other UE and / or the position of the UE 600.

[0082] The medium 620 and / or memory 604 may include a session combining module 630 that, when implemented by the one or more processors 602, configures the one or more processors 602 to ascertain the presence of independent and concurrent ranging sessions initiated by different initiating UEs. The one or more processors 602 may be configured to determine the presence of independent and concurrent ranging sessions based on a pre-PRS message of each ranging session, which may enumerate all participating UEs, including the different initiating UEs. In some embodiments, the one or more processors 602 may be configured to determine the presence of independent and concurrent ranging sessions by detecting whether the number of PRS cycles in both ranging sessions exceeds a threshold within a certain time period. The number of PRS cycles may be determined by monitoring the number of PRS signal broadcasts or post-PRS messages, etc. If the number of PRS cycles from multiple ranging sessions exceeds a threshold within the time period, it may be determined that the independent ranging sessions may be considered simultaneous and should be combined. The one or more processors 602 may be configured to send a combining message to the initiating UE via the transceiver 614, or receive a combining message from another UE if the UE 600 is the initiating UE, in each ranging session indicating that the ranging sessions should be combined and that the UE 600 may initiate a combined ranging session. The combining message may include an indication of whether the location of the UE is known, such that the UE may act as a positioning anchor. The one or more processors 602 may further be configured to measure one or more power characteristics, such as, for example, a signal strength characteristic such as RSPR, of the ranging signal broadcast by the initiating UE in each ranging session. The signal strength characteristic determined by the one or more processors 602 may be an average or other combination of the measured power characteristics of the multiple ranging sessions. The combining message may provide an indication of the signal strength characteristics of the ranging signal from the initiating UE.The one or more processors 602 may be further configured to receive a response message from the initiating UE via the transceiver 614 indicating that the initiating UE approves the combining of the ranging session and that the UE 600 will initiate the combined ranging session. The one or more processors 602 may be configured to initiate the combined ranging session, for example, by sending an initial pre-PRS message including all participating UEs from the independent ranging sessions. The one or more processors 602 may be further configured to select an initiating UE for the combined ranging session when multiple UEs send combining messages to the UE 600, where the selection may be based on whether the UE can serve as an anchor point for positioning and on signal strength characteristics. The one or more processors 602 may be further configured to send a response message to the other UE via the transceiver 614 indicating that the UE 600 approves the combining of the ranging session and that the other UE is selected to initiate the combined ranging session. The one or more processors 602 may be further configured to send or receive, via the transceiver 614, an indication of the availability of the coupled ranging session in a possibility message (such as that shown by message 201 in FIG. 2).

[0083] The medium 620 and / or the memory 604 may include a session separation module 632 that, when implemented by the one or more processors 602, configures the one or more processors 602 to determine whether the coupled ranging session should be separated. The one or more processors 602 may be configured to determine a number of ranging signals broadcast by one or more UEs that are not received by the one or more UEs in the coupled ranging session and whether the number is greater than a threshold. The one or more processors 602 may be configured to send a separation message to the previous initiating UE via the transceiver 614 indicating that the coupled ranging session is terminated and that the UE should initiate an independent ranging session. If the UE 600 is one of the original initiating UEs, the one or more processors 602 may further be configured to receive a message via the transceiver 614 indicating that the coupled ranging session is terminated and that the UE 600 should initiate an independent ranging session.

[0084] The methods described herein may be implemented by various means depending on the application. For example, the methods may be implemented in hardware, firmware, software, or any combination thereof. In the case of a hardware implementation, the one or more processors 602 may be implemented in 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 602 may be general-purpose computers that, when programmed to perform specific operations pursuant to instructions from program software as described herein, operate as special purpose computers programmed to implement the techniques disclosed herein.

[0085] In the case of 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 methods described herein. For example, software code may be stored in a non-transitory computer-readable medium 620 or memory 604 connected to the one or more processors 602 and executed by the one or more processors 602. 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 refers to any type of long-term memory, short-term memory, volatile memory, non-volatile memory, or other memory, and should not be limited to any particular type of memory or any particular number of memories, or to any particular type of medium on which the memory is stored.

[0086] If implemented in firmware and / or software, the functions may be stored as one or more instructions or program code 608 on a non-transitory computer readable medium, such as the medium 620 and / or memory 604. Examples include computer readable media encoded with data structures and computer readable media encoded with a computer program 608. For example, the non-transitory computer readable medium on which the program code 608 is stored may include the program code 608 for facilitating combining multiple independent ranging sessions into a single combined ranging session in a manner consistent with the disclosed embodiments. The non-transitory computer readable medium 620 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 608 in the form of instructions or data structures and that can be accessed by a computer, where disk and disc as used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0087] In addition to being stored on the computer-readable medium 620, the instructions and / or data may be provided as signals on a transmission medium included in a communications device. For example, a communications device may include a transceiver 610 having signals indicative of the 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.

[0088] Memory 604 may represent any data storage mechanism. Memory 604 may include, for example, primary memory and / or secondary memory. Primary memory may include, for example, random access memory, read-only memory, etc. Although shown in this example as separate from the one or more processors 602, it should be understood that all or a portion of the primary memory may be provided within or otherwise co-located / coupled with the one or more processors 602. 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.

[0089] In some implementations, the secondary memory may operatively receive or otherwise be configurable to couple to a non-transitory computer readable medium 620. Thus, in some exemplary implementations, the methods and / or apparatus presented herein may take the form, in whole or in part, of a computer readable medium 620 on which computer implementable code 608 may be stored, which when executed by one or more processors 602 may be effectively enabled to perform all or a portion of the exemplary operations as described herein. The computer readable medium 620 may be part of the memory 604.

[0090] FIG. 7 is a flow chart 700 illustrating a method for ranging between UEs performed by a first UE, such as UEA 310A.

[0091] At block 702, a first UE receives an initial message for initiating separate ranging sessions from a plurality of UEs, as discussed in steps 1A and 1B of Figure 5. The means for receiving an initial message for initiating separate ranging sessions from a plurality of UEs may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622.

[0092] In block 704, the first UE sends a message to the multiple UEs to combine separate ranging sessions, indicating that the first UE will initiate a combined ranging session, as discussed in stage 3A of FIG. 5. The first UE and the multiple UEs may, for example, each be one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit. Means for sending a message to the multiple UEs to combine separate ranging sessions, indicating that the first UE will initiate a combined ranging session, may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0093] At block 706, the first UE conducts a joint ranging session with the multiple UEs as discussed in step 6 of Figure 5. The means for conducting a joint ranging session with the multiple UEs may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622, a PRS module 624, a post-PRS message module 626, and a ranging / positioning module 628.

[0094] In one embodiment, the first UE may determine that the separate ranging sessions are concurrent before sending a message to the multiple UEs for combining the separate ranging sessions, e.g., as discussed in stage 2A of Figure 5. The means for determining that the separate ranging sessions are concurrent before sending a message to the multiple UEs for combining the separate ranging sessions may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0095] In one embodiment, the first UE may determine that the multiple UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the multiple UEs to combine the separate ranging sessions, e.g., as discussed in stage 2A of Figure 5. The means for determining that the multiple UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the multiple UEs to combine the separate ranging sessions may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0096] In one embodiment, the first UE may send an initial message to the multiple UEs to initiate a joint ranging session, e.g., as discussed in step 6 of FIG. 5. The means for sending an initial message to the multiple UEs to initiate a joint ranging session may be, e.g., the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622. For example, the first UE may receive a response message from the multiple UEs indicating that each UE of the multiple UEs agrees that the first UE will initiate a joint ranging session, e.g., as discussed in step 5 of FIG. 5, prior to sending an initial message to the multiple UEs to initiate a joint ranging session. Means for receiving response messages from the plurality of UEs indicating that each UE of the plurality of UEs agrees that the first UE will initiate the combined ranging session prior to sending an initial message to the plurality of UEs to initiate the combined ranging session may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0097] In another embodiment, the first UE may conduct a combined ranging session with the multiple UEs by receiving an initial message from the second UE for initiating a combined ranging session with the multiple UEs, including the multiple UEs and the second UE, as discussed in steps 3A, 3B, 4A, 4B, 5, and 6 of Figure 5. Means for receiving an initial message from the second UE for initiating a combined ranging session with the multiple UEs, including the multiple UEs and the second UE, may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622.

[0098] In one embodiment, the message to the multiple UEs for combining separate ranging sessions indicating that the first UE will initiate a combined ranging session further indicates that the first UE will become a positioning anchor, e.g., as discussed in steps 3A and 6 of FIG. 5, and the combined ranging session with the multiple UEs includes a combined positioning session using the first UE as a positioning anchor.

[0099] In one embodiment, the first UE may determine signal strength characteristics of ranging signals in separate ranging sessions initiated by the multiple UEs as discussed in steps 2A and 3A of Figure 5, and the message to the multiple UEs for combining the separate ranging sessions further indicates the signal strength characteristics of the ranging signals in the separate ranging sessions. The means for determining signal strength characteristics of ranging signals in separate ranging sessions initiated by the multiple UEs may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as the session combining module 630.

[0100] The combined ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs, and the plurality of responding UEs, e.g., as discussed in step 6. In some embodiments, the first UE may determine that the ranging signals broadcast in the plurality of combined ranging sessions are not received by another UE more than a predetermined threshold number of times, e.g., as discussed in step 7A of FIG. 5. The first UE may send a second message to the plurality of UEs to separate the combined ranging session, indicating that the plurality of UEs will initiate separate ranging sessions, as discussed in step 8 of FIG. 5. The means for determining that a ranging signal broadcast in multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times and the means for sending a second message to multiple UEs to separate the combined ranging sessions indicating that the multiple UEs will initiate separate ranging sessions may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session separation module 632.

[0101] In one embodiment, the first UE may receive possibility messages from the plurality of UEs indicating availability of combining ranging sessions, e.g., as discussed by message 201 of Figure 2 and stage 2A of Figure 5, where the message sent to the plurality of UEs to combine the separate ranging sessions is at least in part responsive to the possibility messages indicating availability of combining ranging sessions. The means for receiving possibility messages from the plurality of UEs indicating availability of combining ranging sessions, where the message sent to the plurality of UEs to combine the separate ranging sessions is at least in part responsive to the possibility messages indicating availability of combining ranging sessions, may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as the session combining module 630.

[0102] FIG. 8 is a flow chart 800 illustrating a method for UE-to-UE ranging performed by a first UE, such as UE 1 302. As shown in FIG.

[0103] In block 802, the first UE sends an initial message to the second UE to initiate a first ranging session, as discussed in step 1A of Figure 5. Means for sending an initial message to the second UE to initiate a first ranging session may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622.

[0104] In block 804, the first UE receives a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with the second ranging session initiated by the third UE, as discussed in stage 3A of FIG. 5. The first UE, the second UE, and the third UE may each be, for example, one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit. Means for receiving a message from the second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with the second ranging session initiated by the third UE may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0105] At block 806, the first UE conducts a combined ranging session with the second UE as discussed in step 6 of Figure 5. The means for conducting the combined ranging session with the second UE may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622, a PRS module 624, a post-PRS message module 626, and a ranging / positioning module 628.

[0106] In one embodiment, the second UE may determine that the first ranging session and the second ranging session are concurrent before sending a message to combine the first ranging session and the second ranging session, e.g., as discussed in stage 2A of Figure 5. In one embodiment, the second UE may determine that the first UE and the third UE have initiated separate ranging sessions more than a predetermined number of times before sending a message to combine the first ranging session and the second ranging session, e.g., as discussed in stage 2A of Figure 5.

[0107] In one embodiment, the first UE may receive an initial message from the second UE to initiate a coupled ranging session, e.g., as discussed in step 6 of FIG. 5. Means for receiving an initial message from the second UE to initiate a coupled ranging session may be, e.g., the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or the medium 620, such as a pre-PRS message module 622. For example, the first UE may send a response message to the second UE indicating that the second UE will initiate a coupled ranging session, e.g., as discussed in step 5 of FIG. 5. Means for sending a response message to the second UE indicating that the second UE will initiate a coupled ranging session may be, e.g., the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or the medium 620, such as a session combining module 630. For example, the initial message may be sent by broadcasting an initial message to initiate a first ranging session to the second UE and the fourth UE, and the first UE may receive a second message to combine the first ranging session with a second ranging session initiated by the third UE from the fourth UE indicating that the fourth UE will initiate a combined ranging session, e.g., as discussed in stage 3B of FIG. 5. The first UE may send a response message to the second UE indicating that the second UE will initiate a combined ranging session, e.g., as discussed in stage 5 of FIG. 5. The first UE may receive an initial message to initiate a combined ranging session including the second UE, the third UE, and the fourth UE, from the second UE, e.g., as discussed in stage 6 of FIG. 5.Means for receiving a second message from the fourth UE indicating that the fourth UE will initiate a combined ranging session to combine the first ranging session with the second ranging session initiated by the third UE may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630. Means for receiving an initial message from the second UE to initiate a combined ranging session including the second UE, the third UE, and the fourth UE may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a pre-PRS message module 622. In one example, the message from the second UE may indicate that the second UE will be a positioning anchor, the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and a response message to the second UE indicating that the second UE will initiate a combined ranging session is sent in response to the second UE indicating that the second UE will be a positioning anchor, the combined ranging session including a combined positioning session using the second UE as a positioning anchor, e.g., as discussed in step 4A of FIG. 5. In another example, the message from the second UE may further indicate a first value of a signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and a response message to the second UE indicating that the second UE will initiate a joint ranging session is sent in response to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic, for example, as discussed in step 4A of FIG. 5.

[0108] The combined ranging session includes all UEs participating in the first ranging session and the second ranging session, including the first UE, the second UE, the third UE, and the plurality of responding UEs, e.g., as discussed in step 6. In some embodiments, the first UE may receive a second message to separate the combined ranging session from the second UE indicating that the first UE will initiate a ranging session in response to the second UE determining that a ranging signal broadcast in the plurality of combined ranging sessions is not received by another UE more than a predetermined threshold number of times, e.g., as discussed in step 7A of FIG. Means for receiving a second message from the second UE to separate the combined ranging session indicating that the first UE will initiate a ranging session in response to the second UE determining that the ranging signal broadcast in the multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session separation module 632.

[0109] In one embodiment, the first UE may send a possibility message indicating availability for combining a ranging session, for example, as illustrated by message 201 in Figure 2 and discussed in stage 2A of Figure 5. Means for sending a possibility message indicating availability for combining a ranging session may be, for example, the transceiver 614 and one or more processors 602 having dedicated hardware or implementing executable code or software instructions in the memory 604 and / or medium 620, such as a session combining module 630.

[0110] References throughout this specification to "one example," "an example," "some examples," or "exemplary embodiments" 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, the appearances of the phrases "in one example," "an example," "in a particular example," or "in some embodiments" 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] Some portions of the detailed description contained herein are presented in terms of algorithms or symbolic representations of operations on binary digital signals stored in a memory of a specific apparatus or a dedicated computing device or platform. In the context of this particular specification, the term specific apparatus or the like includes a general purpose computer after it has been programmed to perform certain operations according 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 is herein, and generally, considered to be a self-consistent sequence of operations or similar signal processing that produces 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 that can be stored, transferred, combined, compared, or otherwise manipulated. It has proven convenient at times, primarily for reasons of common usage, to refer to such signals as bits, data, values, elements, symbols, characters, terms, numbers, numeric values, or the like. It should be understood, however, that all of these or similar terms should be associated with the appropriate physical quantities and are merely convenient labels. Unless otherwise indicated, and as will be apparent from the description herein, it should be understood 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, which are typically represented as physical electronic or magnetic quantities in the memory, registers, or other information storage, transmission, or display devices of the special purpose computer or similar special purpose electronic computing device.

[0112] In the above detailed description, numerous specific details are set forth to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other instances, methods and apparatuses that would be known by those skilled in the art have not been described in detail so as not to obscure the claimed subject matter.

[0113] The terms "and," "or," and "and / or" as used herein may include a variety of meanings that are expected to depend at least in part on the context in which such terms are used. Typically, when "or" is used to link a list such as A, B, or C, it is intended to mean A, B, and C, which are used herein in an inclusive sense, as well as A, B, or C, which are used herein in an exclusive sense. In addition, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe a plurality of features, structures, or characteristics, or some other combination of features, structures, or characteristics. It should be noted, however, that this is merely an illustrative example and that claimed subject matter is not limited to this example.

[0114] While what are presently considered to be exemplary features have been illustrated and described, it would be understood by those skilled in the art that various other modifications may be made and equivalents may be substituted without departing from the claimed subject matter. Additionally, many modifications may be made to adapt a particular situation to the teachings of the claimed subject matter without departing from the central concept described herein.

[0115] Example implementations are described in the following numbered sections.

[0116] 1. A method of ranging between user equipment (UE) performed by a first UE, comprising: receiving initial messages from a plurality of UEs for initiating separate ranging sessions; sending a message to a plurality of UEs to combine separate ranging sessions, the message indicating that a first UE will initiate a combined ranging session; conducting a joint ranging session with a plurality of UEs; A method comprising:

[0117] 2. The method of claim 1, further comprising determining that the separate ranging sessions are simultaneous before sending a message to the multiple UEs for combining the separate ranging sessions.

[0118] 3. The method according to claim 1 or 2, further comprising the step of determining that the plurality of UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the plurality of UEs for combining the separate ranging sessions.

[0119] 4. The method of any one of clauses 1 to 3, further comprising sending an initial message to the multiple UEs for initiating a joint ranging session.

[0120] 5. The method of claim 4, further comprising the step of receiving response messages from a plurality of UEs indicating that each of the plurality of UEs agrees that the first UE will initiate the joint ranging session before sending an initial message to the plurality of UEs for initiating the joint ranging session.

[0121] 6. The step of conducting a joint ranging session with a plurality of UEs includes: The method of any one of clauses 1 to 5, comprising receiving an initial message from a second UE for initiating a joint ranging session with the plurality of UEs, the plurality of UEs including the second UE.

[0122] 7. The method of any one of clauses 1 to 6, wherein the message to the multiple UEs for combining separate ranging sessions indicating that the first UE will initiate a combined ranging session further indicates that the first UE will become a positioning anchor, and the combined ranging session with the multiple UEs includes a combined positioning session using the first UE as a positioning anchor.

[0123] 8. determining signal strength characteristics of ranging signals in separate ranging sessions initiated by the plurality of UEs; 8. The method of any one of clauses 1 to 7, wherein the message to the multiple UEs for combining the separate ranging sessions further indicates signal strength characteristics of the ranging signals in the separate ranging sessions.

[0124] 9. The method of any one of clauses 1 to 8, wherein the joint ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs and the plurality of responding UEs.

[0125] 10. The method is determining that the ranging signal broadcast in the multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times; sending a second message to the plurality of UEs to separate the joint ranging session, the second message indicating that the plurality of UEs will start separate ranging sessions; The method of claim 9, further comprising:

[0126] 11. The method of any one of clauses 1 to 10, further comprising receiving possibility messages from a plurality of UEs indicating availability of combining the ranging sessions, wherein the message sent to the plurality of UEs for combining the separate ranging sessions is at least in part responsive to the possibility messages indicating availability of combining the ranging sessions.

[0127] 12. The method of any one of clauses 1 to 11, wherein the first UE and the plurality of UEs are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0128] 13. A first user equipment (UE) configured for UE ranging, 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 to the at least one memory, the at least one processor comprising: receiving, via a wireless transceiver, initial messages from a plurality of UEs for initiating separate ranging sessions; sending a message to a plurality of UEs via a wireless transceiver, the message indicating that a first UE will initiate a combined ranging session; Conducting joint ranging sessions with multiple UEs The first UE is configured to:

[0129] 14. The first UE of claim 13, wherein the at least one processor is further configured to determine that the separate ranging sessions are simultaneous before sending messages to the multiple UEs for combining the separate ranging sessions.

[0130] 15. The first UE of clause 13 or 14, wherein the at least one processor is further configured to determine that the multiple UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the multiple UEs for combining the separate ranging sessions.

[0131] 16. The first UE of any one of clauses 13 to 15, wherein the at least one processor is further configured to send an initial message to the multiple UEs to initiate a joint ranging session.

[0132] 17. The first UE of claim 16, wherein the at least one processor is further configured to receive response messages from a plurality of UEs indicating that each of the plurality of UEs agrees that the first UE will initiate the joint ranging session before sending an initial message to the plurality of UEs to initiate the joint ranging session.

[0133] At least one processor: A first UE according to any one of clauses 13 to 17, configured to conduct a joint ranging session with a plurality of UEs by being configured to receive, via a wireless transceiver, an initial message from a second UE for initiating a joint ranging session with a plurality of UEs, including the plurality of UEs and the second UE.

[0134] 19. A first UE as described in any one of clauses 13 to 18, wherein the message to the multiple UEs for combining separate ranging sessions indicating that the first UE will initiate a combined ranging session further indicates that the first UE will become a positioning anchor, and the combined ranging sessions with the multiple UEs include a combined positioning session using the first UE as a positioning anchor.

[0135] At least one processor: and further configured to determine signal strength characteristics of ranging signals in separate ranging sessions initiated by the plurality of UEs; 20. The first UE of any one of clauses 13 to 19, wherein the message to the multiple UEs for combining the separate ranging sessions further indicates signal strength characteristics of the ranging signals in the separate ranging sessions.

[0136] 21. The first UE of any one of clauses 13 to 20, wherein the joint ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs and the plurality of responding UEs.

[0137] At least one processor: determining that the ranging signal broadcast in the multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times; sending, via the wireless transceiver, a second message to separate the combined ranging session to the plurality of UEs indicating that the plurality of UEs will initiate separate ranging sessions; The first UE of claim 21, further configured to:

[0138] 23. The first UE of any one of clauses 13 to 22, wherein the at least one processor is further configured to receive, via the wireless transceiver, possibility messages from the multiple UEs indicating availability of combining the ranging sessions, and wherein messages sent to the multiple UEs to combine the separate ranging sessions are at least in part responsive to the possibility messages indicating availability of combining the ranging sessions.

[0139] 24. The first UE of any one of clauses 13 to 23, wherein the first UE and the plurality of UEs are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0140] 25. A first user equipment (UE) configured for UE ranging, comprising: means for receiving initial messages from a plurality of UEs for initiating separate ranging sessions; means for sending a message to a plurality of UEs indicating that a first UE will initiate a combined ranging session; means for conducting a joint ranging session with a plurality of UEs; A first UE comprising:

[0141] 26. The first UE of clause 25, further comprising means for determining that the separate ranging sessions are concurrent before sending a message to the multiple UEs for combining the separate ranging sessions.

[0142] 27. The first UE of claim 25 or 26, further comprising means for determining that a plurality of UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the plurality of UEs for combining the separate ranging sessions.

[0143] 28. The first UE of any one of clauses 25 to 27, further comprising means for sending an initial message to the plurality of UEs for initiating a joint ranging session.

[0144] 29. The first UE of claim 28, further comprising means for receiving response messages from a plurality of UEs indicating that each of the plurality of UEs agrees that the first UE will initiate the joint ranging session before sending an initial message to the plurality of UEs for initiating the joint ranging session.

[0145] 30. A means for conducting a joint ranging session with a plurality of UEs, comprising: 30. The first UE of any one of clauses 25 to 29, comprising means for receiving an initial message from a second UE for initiating a joint ranging session with a plurality of UEs, the plurality of UEs including the second UE.

[0146] 31. A first UE as described in any one of clauses 25 to 30, wherein the message to the multiple UEs for combining separate ranging sessions indicating that the first UE will initiate a combined ranging session further indicates that the first UE will become a positioning anchor, and the combined ranging sessions with the multiple UEs include a combined positioning session using the first UE as a positioning anchor.

[0147] 32. The method according to claim 1, further comprising: determining signal strength characteristics of ranging signals in separate ranging sessions initiated by a plurality of UEs; 32. The first UE of any one of clauses 25 to 31, wherein the message to the multiple UEs for combining the separate ranging sessions further indicates signal strength characteristics of the ranging signals in the separate ranging sessions.

[0148] 33. The first UE of any one of clauses 25 to 32, wherein the joint ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs and the plurality of responding UEs.

[0149] 34. Means for determining that a ranging signal broadcast in a plurality of combined ranging sessions is not received by another UE more than a predetermined threshold number of times; means for sending a second message to the plurality of UEs indicating that the plurality of UEs will initiate separate ranging sessions to separate the combined ranging session; The first UE of clause 33, further comprising:

[0150] 35. A first UE as described in any one of clauses 25 to 34, further comprising means for receiving possibility messages from a plurality of UEs indicating availability of combining the ranging sessions, wherein messages sent to the plurality of UEs for combining separate ranging sessions are at least in part responsive to the possibility messages indicating availability of combining the ranging sessions.

[0151] 36. The first UE of any one of clauses 25 to 35, wherein the first UE and the plurality of UEs are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0152] 37. A non-transitory storage medium having program code stored thereon, the program code operable to configure at least one processor in a first user equipment (UE) for ranging between UEs, the program code comprising: receiving initial messages from a plurality of UEs for initiating separate ranging sessions; sending a message to a plurality of UEs to combine separate ranging sessions, the message indicating that a first UE will initiate the combined ranging session; Conducting joint ranging sessions with multiple UEs A non-transitory storage medium containing program code, the program code including instructions for performing the steps of:

[0153] 38. A non-transitory storage medium including the program code of claim 37, further comprising program code for determining that the separate ranging sessions are concurrent before sending messages to the multiple UEs for combining the separate ranging sessions.

[0154] 39. A non-transitory storage medium including the program code described in clause 37 or 38, further comprising program code for determining that a plurality of UEs initiate separate ranging sessions more than a predetermined number of times before sending a message to the plurality of UEs for combining the separate ranging sessions.

[0155] 40. A non-transitory storage medium comprising the program code of any one of clauses 37 to 39, further comprising program code for sending an initial message to a plurality of UEs for initiating a joint ranging session to the plurality of UEs.

[0156] 41. A non-transitory storage medium including the program code described in clause 40, further comprising program code for receiving response messages from a plurality of UEs indicating that each of the plurality of UEs agrees that the first UE will initiate the joint ranging session before sending an initial message to the plurality of UEs for initiating the joint ranging session.

[0157] 42. Program code for conducting a joint ranging session with a plurality of UEs, comprising: A non-transitory storage medium comprising the program code of any one of clauses 37 to 41, comprising program code for receiving an initial message from a second UE for initiating a joint ranging session with a plurality of UEs, the plurality of UEs including the second UE.

[0158] 43. A non-transitory storage medium comprising program code according to any one of clauses 37 to 42, wherein a message to a plurality of UEs for combining separate ranging sessions indicating that the first UE will initiate a combined ranging session further indicates that the first UE will become a positioning anchor, and the combined ranging sessions with the plurality of UEs include a combined positioning session using the first UE as a positioning anchor.

[0159] 44. The method further comprising: determining signal strength characteristics of ranging signals in separate ranging sessions initiated by a plurality of UEs; A non-transitory storage medium comprising the program code of any one of clauses 37 to 43, wherein the message to the multiple UEs for combining the separate ranging sessions further indicates signal strength characteristics of the ranging signals in the separate ranging sessions.

[0160] 45. A non-transitory storage medium comprising program code according to any one of clauses 37 to 44, wherein the joint ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs and the plurality of responding UEs.

[0161] 46. ​​Determining that a ranging signal broadcast in a plurality of combined ranging sessions is not received by another UE more than a predetermined threshold number of times; sending a second message to the plurality of UEs to separate the combined ranging session, the second message indicating that the plurality of UEs will initiate separate ranging sessions; 46. ​​A non-transitory storage medium comprising the program code according to claim 45, further comprising program code for performing the steps:

[0162] 47. A non-transitory storage medium comprising the program code of any one of clauses 37 to 46, further comprising program code for receiving possibility messages from a plurality of UEs indicating availability of combining the ranging sessions, wherein messages sent to the plurality of UEs for combining separate ranging sessions are at least in part responsive to the possibility messages indicating availability of combining the ranging sessions.

[0163] 48. A non-transitory storage medium including program code according to any one of clauses 37 to 47, wherein the first UE and the plurality of UEs are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0164] 49. A method of ranging between user equipment (UE) performed by a first UE, comprising: sending an initial message to a second UE to initiate a first ranging session; receiving a message from a second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE; conducting a joint ranging session with a second UE; A method comprising:

[0165] 50. The method of clause 49, wherein the second UE determines that the first ranging session and the second ranging session are simultaneous before sending a message to combine the first ranging session and the second ranging session.

[0166] 51. The method of clause 49 or 50, wherein the second UE determines that the first UE and the third UE have initiated separate ranging sessions more than a predetermined number of times before sending a message to combine the first ranging session and the second ranging session.

[0167] 52. The method of any one of clauses 49 to 51, further comprising receiving an initial message from a second UE for initiating a joint ranging session.

[0168] 53. The method of clause 52, further comprising sending a response message to the second UE indicating that the second UE will initiate a joint ranging session.

[0169] 54. The step of sending the initial message includes a step of broadcasting an initial message for starting a first ranging session to the second UE and the fourth UE, and the method further comprises: receiving a second message from a fourth UE indicating that the fourth UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by the third UE; sending a response message to the second UE indicating that the second UE will initiate a joint ranging session; receiving an initial message from a second UE for initiating a joint ranging session; Further comprising: The method of clause 53, wherein the joint ranging session includes the second UE, the third UE, and the fourth UE.

[0170] 55. The method of clause 54, wherein the message from the second UE indicates that the second UE will be a positioning anchor, the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and the response message to the second UE indicating that the second UE will initiate a combined ranging session is in response to the second UE indicating that the second UE will be a positioning anchor, and the combined ranging session includes a combined positioning session using the second UE as a positioning anchor.

[0171] 56. The method of clause 54, wherein the message from the second UE further indicates a first value of a signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and the step of sending a response message to the second UE indicating that the second UE will initiate the combined ranging session is in response to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic.

[0172] 57. The method of any one of clauses 49 to 56, wherein the joint ranging session includes all UEs participating in the first ranging session and the second ranging session, including the first UE, the second UE, the third UE, and a plurality of responding UEs.

[0173] 58. The method is The method of clause 57, further comprising receiving a second message from the second UE indicating that the first UE will initiate a ranging session in response to the second UE determining that a ranging signal broadcast in the multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times.

[0174] 59. The method of any one of clauses 49 to 58, further comprising sending a possibility message indicating availability for combining ranging sessions.

[0175] 60. The method of any one of clauses 49 to 59, wherein the first UE, the second UE, and the third UE are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0176] 61. A first user equipment (UE) configured for UE ranging, 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 to the at least one memory, the at least one processor comprising: sending, via the wireless transceiver, an initial message to a second UE to initiate a first ranging session; receiving, via the wireless transceiver, a message from a second UE indicating that the second UE will initiate a combined ranging session, for combining the first ranging session with a second ranging session initiated by a third UE; conducting a joint ranging session with a second UE; The first UE is configured to:

[0177] 62. The first UE of clause 61, wherein the second UE determines that the first ranging session and the second ranging session are simultaneous before sending a message to combine the first ranging session and the second ranging session.

[0178] 63. The first UE of clause 61 or 62, wherein the second UE determines that the first UE and the third UE have initiated separate ranging sessions more than a predetermined number of times before sending a message to combine the first ranging session and the second ranging session.

[0179] 64. The first UE of any one of clauses 61 to 63, wherein the at least one processor is further configured to receive an initial message from the second UE to initiate the combined ranging session.

[0180] 65. The first UE of clause 64, wherein the at least one processor is further configured to send a response message to the second UE indicating that the second UE will initiate a joint ranging session.

[0181] 66. The at least one processor is configured to broadcast an initial message for initiating a first ranging session to a second UE and a fourth UE, thereby sending the initial message, and the at least one processor is configured to: receiving, via the wireless transceiver, a second message from a fourth UE indicating that the fourth UE will initiate a combined ranging session, for combining the first ranging session with a second ranging session initiated by the third UE; sending a response message to the second UE via the wireless transceiver indicating that the second UE will initiate a joint ranging session; receiving an initial message for initiating a joint ranging session from a second UE via the wireless transceiver;

[0023] The method according to claim 1, further comprising: The first UE of clause 65, wherein the joint ranging session includes the second UE, the third UE, and the fourth UE.

[0182] 67. The first UE of clause 66, wherein the message from the second UE indicates that the second UE will be a positioning anchor and the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and the at least one processor is configured to send a response message to the second UE indicating that the second UE will initiate a combined ranging session in response to the second UE indicating that the second UE will be a positioning anchor, and the combined ranging session includes a combined positioning session using the second UE as a positioning anchor.

[0183] 68. The first UE of clause 66, wherein the message from the second UE further indicates a first value of a signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and the at least one processor is configured to send a response message to the second UE indicating that the second UE will initiate a combined ranging session in response to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic.

[0184] 69. The first UE of any one of clauses 61 to 68, wherein the joint ranging session includes all UEs participating in the first ranging session and the second ranging session, including the first UE, the second UE, the third UE, and multiple responding UEs.

[0185] 70. At least one processor: The first UE of claim 69, further configured to receive, via the wireless transceiver, from the second UE, a second message for separating the coupled ranging session indicating that the first UE will initiate a ranging session in response to the second UE determining that a ranging signal broadcast in the multiple coupled ranging sessions is not received by another UE more than a predetermined threshold number of times.

[0186] 71. The first UE of any one of clauses 61 to 70, wherein the at least one processor is further configured to send, via the wireless transceiver, a possibility message indicating availability for combining the ranging session.

[0187] 72. The first UE of any one of clauses 61 to 71, wherein the first UE, the second UE, and the third UE are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0188] 73. A first user equipment (UE) configured for UE ranging, comprising: means for sending an initial message to the second UE to initiate a first ranging session; means for receiving a message from a second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE; means for conducting a combined ranging session with the second UE; A first UE comprising:

[0189] 74. The first UE of clause 73, wherein the second UE determines that the first ranging session and the second ranging session are simultaneous before sending a message to combine the first ranging session and the second ranging session.

[0190] 75. The first UE of clause 73 or 74, wherein the second UE determines that the first UE and the third UE have initiated separate ranging sessions more than a predetermined number of times before sending a message to combine the first ranging session and the second ranging session.

[0191] 76. The first UE of any one of clauses 73 to 75, further comprising means for receiving an initial message from a second UE for initiating a joint ranging session.

[0192] 77. The first UE of clause 76, further comprising means for sending a response message to the second UE indicating that the second UE will initiate a joint ranging session.

[0193] 78. The means for sending the initial message includes broadcasting an initial message for initiating a first ranging session to the second UE and the fourth UE, and the first UE: means for receiving a second message from the fourth UE indicating that the fourth UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by the third UE; means for sending a response message to the second UE indicating that the second UE will initiate a joint ranging session; means for receiving an initial message from a second UE for initiating a combined ranging session; Equipped with The first UE of clause 77, wherein the joint ranging session includes the second UE, the third UE, and the fourth UE.

[0194] 79. The first UE of clause 78, wherein the message from the second UE indicates that the second UE will be a positioning anchor and the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and the means for sending a response message to the second UE indicating that the second UE will initiate a combined ranging session is responsive to the second UE indicating that the second UE will be a positioning anchor, and the combined ranging session includes a combined positioning session using the second UE as a positioning anchor.

[0195] 80. The first UE of clause 78, wherein the message from the second UE further indicates a first value of a signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and the means for sending a response message to the second UE indicating that the second UE will initiate a combined ranging session is responsive to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic.

[0196] 81. The first UE of any one of clauses 73 to 80, wherein the joint ranging session includes all UEs participating in the first ranging session and the second ranging session, including the first UE, the second UE, the third UE, and multiple responding UEs.

[0197] 82. The first UE of clause 81, further comprising means for receiving from the second UE a second message for separating the coupled ranging session indicating that the first UE will initiate a ranging session in response to the second UE determining that a ranging signal broadcast in a plurality of coupled ranging sessions is not received by another UE more than a predetermined threshold number of times.

[0198] 83. The first UE of any one of clauses 73 to 82, further comprising means for sending a possibility message indicating availability of combining ranging sessions.

[0199] 84. The first UE of any one of clauses 73 to 83, wherein the first UE, the second UE, and the third UE are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0200] 85. A non-transitory storage medium having program code stored thereon, the program code operable to configure at least one processor in a first user equipment (UE) for ranging between UEs, the program code comprising: sending an initial message to a second UE to initiate a first ranging session; receiving a message from a second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE; conducting a joint ranging session with a second UE; A non-transitory storage medium containing program code, the program code including instructions for performing the steps of:

[0201] 86. A non-transitory storage medium including the program code of claim 85, wherein the second UE determines that the first ranging session and the second ranging session are simultaneous before sending a message to combine the first ranging session and the second ranging session.

[0202] 87. A non-transitory storage medium including the program code described in clause 85 or 86, in which the second UE determines that the first UE and the third UE have initiated separate ranging sessions more than a predetermined number of times before sending a message to combine the first ranging session and the second ranging session.

[0203] 88. A non-transitory storage medium including the program code of any one of clauses 85 to 87, further comprising program code for receiving an initial message from a second UE for initiating a joint ranging session.

[0204] 89. A non-transitory storage medium including the program code of clause 88, further comprising program code for sending a response message to the second UE indicating that the second UE will initiate a joint ranging session.

[0205] 90. The program code for sending the initial message includes program code for broadcasting an initial message to the second UE and the fourth UE for initiating a first ranging session, and the non-transitory storage medium includes: receiving a second message from the fourth UE indicating that the fourth UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by the third UE; sending a response message to the second UE indicating that the second UE will initiate a joint ranging session; receiving an initial message from a second UE for initiating a joint ranging session; and further comprising program code for: A non-transitory storage medium including the program code of claim 89, wherein the joint ranging session includes a second UE, a third UE, and a fourth UE.

[0206] 91. A non-transitory storage medium comprising the program code of clause 90, wherein the message from the second UE indicates that the second UE will be a positioning anchor and the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and program code for sending a response message to the second UE indicating that the second UE will initiate a combined ranging session is in response to the second UE indicating that the second UE will be a positioning anchor, and the combined ranging session includes a combined positioning session using the second UE as a positioning anchor.

[0207] 92. A non-transitory storage medium comprising the program code of clause 90, wherein the message from the second UE further indicates a first value of a signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and the program code for sending a response message to the second UE indicating that the second UE will initiate a combined ranging session is responsive to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic.

[0208] 93. A non-transitory storage medium comprising the program code of any one of clauses 85 to 92, wherein the combined ranging session includes all UEs participating in the first ranging session and the second ranging session, including the first UE, the second UE, the third UE, and a plurality of responding UEs.

[0209] 94. A non-transitory storage medium including the program code described in clause 93, further comprising program code for receiving from the second UE a second message for separating the coupled ranging session indicating that the first UE will initiate a ranging session in response to the second UE determining that a ranging signal broadcast in the multiple coupled ranging sessions is not received by another UE more than a predetermined threshold number of times.

[0210] 95. A non-transitory storage medium comprising the program code of any one of clauses 85 to 94, further comprising program code for sending a possibility message indicating availability for joining a ranging session.

[0211] 96. A non-transitory storage medium including the program code of any one of clauses 85 to 95, wherein the first UE, the second UE, and the third UE are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

[0212] It is intended therefore that the claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter may include all embodiments falling within the scope of the appended claims and equivalents thereof. [Explanation of symbols]

[0213] 1A stage Phase 1B 2A stage 2B stage 3A stage 3B stage 4A stage 4B stage 5 stages 6 stages 7A stage 7B stage 8 stages 9A stage 9B stage 100 Wireless communication system 102V-UE 103 Link 104V-UE 107 Link 109 Links 110 Roadside Unit (RSU) 111 Wired connection 112UE 113 V2V communication link 114 Pedestrians 115 V2V communication link 117 V2I communication link 200 Signaling Graph 201 Possible Message 202 Ranging Sessions 204 PRS Pre-Message 206 PRS signal 208 PRS post signal 300 Systems 302UE1 303 PRS Pre-Message 304UE2 305 PRS Pre-Message 310UE 310A UEA 310B UEB 310C UEC 350 System 353 PRS Pre-Message 353-1 PRS Pre-Message 353-3 Message before PRS 353-B Pre-PRS Message 353-C Pre-PRS Message 400 Visibility Map 402 lines 500 Signaling Flow 600 User Equipment (UE) 602 Processor 604 Memory 605 Vehicle Interface 606 Connection 607 Inertial Measurement Unit 608 Instructions or Program Code 609 Satellite Positioning System (SPS) Receiver 610 Wireless Wide Area Network (WWAN) Transceiver 611 Transmitter 612 Receiver 614 Wireless Local Area Network (WLAN) Transceiver 615 Transmitter 616 Receiver 620 Non-transitory computer-readable medium 622 PRS Pre-Message Module 624 PRS Module 626 PRS Rear Message Module 628 Ranging / Positioning Module 630 Session Binding Module 632 Session Isolation Module

Claims

1. A method of ranging between user equipment (UE) performed by a first UE, comprising: receiving initial messages from a plurality of UEs for initiating separate ranging sessions; sending a message to the plurality of UEs indicating that the first UE will initiate a combined ranging session; and conducting the joint ranging session with the plurality of UEs; A method comprising:

2. The method of claim 1 , further comprising: determining that the separate ranging sessions are concurrent before sending the message to the multiple UEs to combine the separate ranging sessions.

3. 2. The method of claim 1, further comprising: determining that the plurality of UEs initiate separate ranging sessions more than a predetermined number of times before sending the message to the plurality of UEs to combine the separate ranging sessions.

4. sending an initial message to the plurality of UEs to initiate the joint ranging session; and receiving a response message from the plurality of UEs indicating that each UE of the plurality of UEs agrees that the first UE will initiate the joint ranging session before sending the initial message to the plurality of UEs to initiate the joint ranging session.

5. The step of conducting the joint ranging session with the plurality of UEs includes:

2. The method of claim 1, comprising: receiving an initial message from the plurality of UEs including the plurality of UEs and a second UE for initiating the joint ranging session with the plurality of UEs from the second UE.

6. 2. The method of claim 1, wherein the message to the multiple UEs for combining the separate ranging sessions indicating that the first UE will initiate the combined ranging session further indicates that the first UE will be a positioning anchor, and the combined ranging session with the multiple UEs includes a combined positioning session using the first UE as the positioning anchor.

7. determining signal strength characteristics of ranging signals in the separate ranging sessions initiated by the plurality of UEs; 2. The method of claim 1, wherein the message to the multiple UEs for combining the separate ranging sessions further indicates the signal strength characteristics of the ranging signals in the separate ranging sessions.

8. the joint ranging session includes all UEs participating in the separate ranging sessions, including the first UE, the plurality of UEs, and a plurality of responding UEs; The method comprises: determining that the ranging signal broadcast in the multiple combined ranging sessions is not received by another UE more than a predetermined threshold number of times; sending a second message to the plurality of UEs to separate the combined ranging session, the second message indicating that the plurality of UEs will initiate separate ranging sessions; The method of claim 1, further comprising:

9. 2. The method of claim 1, further comprising receiving a possibility message from the plurality of UEs indicating availability of combining the ranging sessions, wherein the message sent to the plurality of UEs to combine the separate ranging sessions is at least in part responsive to the possibility message indicating availability of combining the ranging sessions.

10. The method of claim 1 , wherein the first UE and the plurality of UEs are each one of a vehicle-based UE, a pedestrian-based UE, or a roadside unit.

11. A first user equipment (UE) configured for UE ranging, 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, via the wireless transceiver, initial messages from a plurality of UEs for initiating separate ranging sessions; sending a message to the plurality of UEs via the wireless transceiver indicating that the first UE will initiate a combined ranging session; and conducting the joint ranging session with the plurality of UEs; The first UE is configured to:

12. A first UE as described in claim 11, further configured to execute a method according to any one of claims 2 to 10.

13. A method of ranging between user equipment (UE) performed by a first UE, comprising: sending an initial message to a second UE to initiate a first ranging session; receiving a message from a second UE indicating that the second UE will initiate a combined ranging session to combine the first ranging session with a second ranging session initiated by a third UE; conducting the joint ranging session with the second UE; A method comprising:

14. receiving an initial message from the second UE for initiating the joint ranging session; and sending a response message to the second UE indicating that the second UE will initiate the joint ranging session, wherein the sending of the initial message includes broadcasting the initial message to the second UE and a fourth UE to initiate the first ranging session, the method comprising: receiving a second message from the fourth UE indicating that the fourth UE will initiate the combined ranging session to combine the first ranging session with the second ranging session initiated by the third UE; sending the response message to the second UE indicating that the second UE will initiate the joint ranging session; receiving an initial message from the second UE for initiating the joint ranging session; Further comprising: The method of claim 13 , wherein the joint ranging session includes the second UE, the third UE, and the fourth UE.

15. 15. The method of claim 14, wherein the message from the second UE indicates that the second UE will be a positioning anchor and the second message from the fourth UE does not indicate that the fourth UE will be a positioning anchor, and wherein sending the response message to the second UE indicating that the second UE will initiate the combined ranging session is in response to the second UE indicating that the second UE will be a positioning anchor, and the combined ranging session includes a combined positioning session using the second UE as the positioning anchor.

16. 15. The method of claim 14, wherein the message from the second UE further indicates a first value of a signal strength characteristic of a ranging signal in the first ranging session and the second ranging session measured by the second UE, and the second message from the fourth UE indicates a second value of the signal strength characteristic of the ranging signal in the first ranging session and the second ranging session measured by the fourth UE, and wherein the step of sending the response message to the second UE indicating that the second UE will initiate the combined ranging session is in response to the first value of the signal strength characteristic being greater than the second value of the signal strength characteristic.

17. A first user equipment (UE) configured for UE ranging, 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, via the wireless transceiver, an initial message to a second UE to initiate a first ranging session; receiving, via the wireless transceiver, a message from a second UE indicating that the second UE will initiate a combined ranging session, to combine the first ranging session with a second ranging session initiated by a third UE; conducting the joint ranging session with the second UE; The first UE is configured to:

18. A first UE as described in claim 17, further configured to execute a method according to any one of claims 14 to 16.

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