Sidelink positioning with clock error present

Abstract

In one example, a method performed by a first station and comprising: transmitting a first message comprising an indication of whether a clock reconfiguration event occurred at the first station; transmitting a first positioning reference signal (PRS); receiving a second PRS from a second station; and transmitting a second message to the second station comprising a first time at which the first PRS was transmitted by the first station and a second time at which the second PRS was received by the first station to enable the second station to determine a round trip time (RTT) between the first station and the second station based on the first time, the second time, a third time at which the first PRS was received by the second station, a fourth time at which the second PRS was transmitted by the second station, and the indication.

Description

BACKGROUND

[0001] Obtaining accurate positioning information for user equipment (UE) such as cellular telephones or other wireless communication devices is increasingly common in the communication industry. A common means of determining device location 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 uses multiple satellites in orbit around the Earth. Position determination using an SPS is accurate but is sometimes unavailable or undesirable, for example, in urban canyons or areas where satellite signal reception is poor. Other means commonly used to determine device location include terrestrial-based positioning. Terrestrial-based positioning can be based on measurements of signals exchanged between a UE and nearby communication infrastructure having known locations, such as base stations (BSs) or road-side units (RSUs). The accuracy of terrestrial-based positioning can be reduced by various error sources, such as clock error between the UE and the transmitter. SUMMARY

[0002] In one example, a method is provided that includes transmitting, by a first station, a first message including an indication of whether a clock reconfiguration event occurred at the first station, transmitting, by the first station, a first positioning reference signal (PRS), receiving, by the first station and from a second station, a second PRS, and transmitting, by the first station to the second station, a second message including a first time when the first PRS was transmitted by the first station and a second time when the second PRS was received by the first station to enable the second station to determine a round trip time (RTT) between the first station and the second station based on the first time, the second time, a third time when the first PRS was received by the second station, a fourth time when the second PRS was transmitted by the second station, and the indication.

[0003] In some aspects, the indication indicates whether a clock reconfiguration event occurred at the first station prior to the first station transmitting the first positioning reference.

[0004] In some aspects, the clock reconfiguration event is at a local clock source of the first station. The first time and the second time are obtained based on a clock signal of the local clock source of the first station.

[0005] In some aspects, the second station includes a Kalman filter to estimate a clock error between the first station and the second station and stores estimates of the clock difference. The indication enables the second station to perform one of the following based on the indication: reset a previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock difference or use the previous estimate of the clock error to estimate the RTT in a quasi co-location (QCL) operation.

[0006] In some aspects, the first message includes an identifier of the first station to enable the second station to determine a location of the first station based on the identifier.

[0007] In some aspects, the method further includes determining a position of the second station based on the position of the first station and the RTT.

[0008] In some aspects, the first message includes one or more carrier frequencies used in the transmission of the first PRS.

[0009] In some aspects, the first message includes a scheduled time window of the transmission of the first PRS. The first message is transmitted prior to the transmission of the first PRS.

[0010] In some aspects, the first PRS and the second PRS are transmitted via an unlicensed spectrum.

[0011] In some aspects, the first message is transmitted after the transmission of the first PRS.

[0012] In some aspects, the first PRS and the second PRS are transmitted via a vehicle-to- everything (V2X) sidelink and associated sidelink protocols.

[0013] In some aspects, the V2X sidelink is within an intelligent transportation system (ITS) spectrum including 5.9 GHz.

[0014] In some aspects, the first station is part of a road side unit (RSU), wherein the second station is part of a vehicle.

[0015] In one example, a method is provided. The method includes: (1) receiving, by a first station and from a second station, a first message including an indication of whether a clock reconfiguration event occurred at the second station; (2) transmitting, by the first station and to the second station, a first PRS; (3) receiving, by the first station and from the second station, a second PRS; (4) receiving, by the first station and from the second station, a second message including a first time at which the second station received the first PRS and a second time at which the second station transmitted the second PRS; and (5) determining, by the first station and based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and the indication, an RTT between the first station and the second station.

[0016] In some aspects, the indication indicates whether a clock reconfiguration event occurred at the second station prior to the second station transmitting a second positioning reference.

[0017] In some aspects, the clock reconfiguration event is at a local clock source of the second station. The first time and the second time are obtained based on a clock signal of the local clock source of the second station.

[0018] In some aspects, the first station includes a Kalman filter to estimate a clock error between the first station and the second station and to store estimates of the clock difference. The method further includes, based on the indication, performing one of: resetting a previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock difference, or using the previous estimate of the clock error to estimate the RTT in the QCL operation.

[0019] In some aspects, the first message includes an identifier of the second station. The method further includes determining a location of the second station based on the identifier.

[0020] In some aspects, the method further includes determining a location of the first station based on the location of the second station and the RTT.

[0021] In some aspects, the first message includes one or more carrier frequencies used in the transmission of the second PRS.

[0022] In some aspects, the first message includes a scheduled time window of the transmission of the second PRS. The first message is transmitted prior to the transmission of the second PRS.

[0023] In some aspects, the first PRS and the second PRS are transmitted via an unlicensed spectrum.

[0024] In some aspects, the first message is received after the second PRS is received.

[0025] In some aspects, the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocols. The V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0026] In some aspects, the first station is part of a vehicle, and wherein the second station is part of an RSU.

[0027] In some examples, an apparatus including instructions for performing the above methods and a non-transitory computer-readable medium including the instructions are provided. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of a connected vehicle communication system.

[0029] Figure 2 is a block diagram of components of an example user equipment (UE).

[0030] Figure 3 is a block diagram of components of an example road side unit (RSU).

[0031] Figure 4A and Figure 4B An example of a positioning operation that can be performed between an example UE of Figure 2 and an example RSU of Figure 3 is shown.

[0032] Figure 5A 、 Figure 5B 、 Figure 5C 、 Figure 5D and Figure 5E Example techniques to mitigate the impact of clock error on positioning operations are shown.

[0033] Figure 6 Example impact of clock reconfiguration events on positioning operations is shown.

[0034] Figure 7 Example techniques to mitigate the impact of clock reconfiguration events on positioning are shown.

[0035] Figure 8 is a block diagram of an example RSU implementing the techniques described in Figure 7

[0036] Figure 9 is a block diagram of an example UE implementing the techniques described in Figure 7

[0037] Figure 10 is a process flow diagram of an example method for determining a position of a vehicle.

[0038] Figure 11 is a process flow diagram of another example method for determining a position of a vehicle. DETAILED DESCRIPTION

[0039] Several illustrative embodiments will now be described, with reference to the drawings, which form a part of this disclosure. While several embodiments can be described in connection with these specifications, the embodiments are not intended to limit the scope of the disclosure to the particular embodiments. Various modifications in form and detail are possible with the scope of the disclosure and can be resorted to by those skilled in the art.

[0040] ​​Techniques for V2X sidelink positioning are discussed herein. A vehicle can be configured to communicate with a network that includes ground stations such as base stations (BSs) and RSUs. One example of sidelink positioning can be based on measuring the RTT of a pair of signals exchanged between the vehicle and a ground station, such as an RSU or a BS. In such an example, the ground station can transmit a first signal to the vehicle and record a time of departure (ToD) of the first signal, while the vehicle can receive the first signal and record a time of arrival (ToA) of the first signal. In addition, the vehicle can also transmit a second signal to the ground station and record a ToD of the second signal, while the ground station can receive the second signal and record a ToA of the second signal. The ground station can also transmit the recorded ToD of the first signal and the recorded ToA of the second signal to the vehicle via an intelligent transportation system (ITS) message in a V2X implementation. The first and second signals can comprise, for example, positioning reference signals (PRSs), which can be transmitted in a licensed spectrum or an unlicensed spectrum.

[0041] The vehicle can measure the RTT between the vehicle and the ground station based on determining a first time difference between the ToA (recorded at the vehicle) and the ToD (received from the ITS message) of the first signal and a second time difference between the ToD (recorded at the vehicle) and the ToA (received from the ITS message) of the second signal. The vehicle can repeat the RTT measurements with multiple ground stations to determine a time offset between PRSs from the multiple ground stations based on differences between the RTT measurements. The vehicle can then estimate its position based on the time offsets of the multiple ground stations and known locations.

[0042] The accuracy of the RTT measurements, and thus the accuracy of the vehicle’s position estimate, can be degraded due to clock errors / differences between the vehicle and the ground station. Specifically, for the difference between the ToD recorded at the ground station and the ToA recorded at the vehicle for the first signal, and for the difference between the ToD recorded at the vehicle and the ToA recorded at the ground station for the second signal, only when both the ToA and the ToD are measured with respect to the same clock source do they truly represent the time of flight (ToF) between the vehicle and the ground station. However, the vehicle and the ground station have different clock sources, which must be synchronized with each other. Thus, there can be a static clock bias between the two clock sources, and each clock source can have a random clock drift caused by random noise (e.g., thermal noise, phase noise). The clock bias and the clock drift can introduce a clock error between the two clock sources. Thus, the difference between the recorded ToD and ToA includes a first component that represents the ToF of the signal between the ground station and the vehicle and a second component that is caused by the clock error between the two clock sources.

[0043] The vehicle can estimate the distance between the vehicle and the ground station and the clock error based on the RTT measurements of the multiple signals using techniques such as Kalman filtering. Specifically, the ground station and the vehicle can exchange multiple pairs of PRSs and can record the ToDs and ToAs of the multiple pairs of PRSs. The vehicle can use a Kalman filter to generate a first estimate of the clock error and the relative distance of the vehicle from the ground station at a first time based on a first pair of PRSs exchanged between the ground station and the vehicle. The vehicle can then use the estimated clock error and the relative distance, plus other information (e.g., the speed of the vehicle) to estimate the relative distance of the vehicle from the ground station at a second time. The vehicle can also measure the relative distance at the second time based on a second pair of PRSs. The vehicle can compare the measured and estimated relative distances and update the estimate of the clock error based on the comparison. The vehicle can then repeat the relative distance measurement and clock error estimate refinement based on subsequent pairs of first and second signals.

[0044] When the Kalman filter reaches steady state, the estimated clock error can be close to the actual clock error. The vehicle can then use the estimated clock error at the vehicle for quasi co-located (QCL) operations for subsequent signals to refine the RTT measurements from subsequent PRSs exchanged between the vehicle and the ground station. With the QCL operations at the vehicle, the estimated clock error stored at the Kalman filter can be combined with the recorded ToA and ToD to calculate the RTT without applying Kalman filtering to calculate the estimated clock error. This allows for effectively reducing the impact of the clock error on the RTT measurements, as Kalman filtering can be computationally intensive and slow.

[0045] While the QCL operations can provide an effective way to reduce the impact of the clock error on the RTT measurements, the clock error reduction of the QCL operations can be compromised when the estimated clock error no longer corresponds to the actual clock error. This can occur when a clock reconfiguration event occurs at the ground station. The clock reconfiguration event can include various events at the ground station, such as a power-up event of the ground station, a clock synchronization event of the ground station, or a reconfiguration event of a local oscillator, all of which can change the properties of the local clock at the ground station. As the properties of the local clock at the ground station change, the clock error between the ground station and the vehicle can change, and the estimated clock error from the previous exchange of PRSs no longer represents the true clock error. Using the outdated clock error estimate to refine the RTT measurements can increase the error in the RTT measurements and in the positioning operations.

[0046] Examples of the present disclosure provide a positioning method that can solve at least some of the above problems. In one example, a first station, which can be a ground station (e.g., RSU, BS), can transmit a first message including an indication of whether a clock reconfiguration event occurred at the first station. The first station can transmit a first PRS to a second station and receive a second PRS from the second station, which can be a wireless station of a vehicle. The first station can then transmit a second message to the second station indicating a ToD of the first PRS and a ToA of the second PRS at the first station. The second station can then determine an RTT between the first station and the second station based on a first difference between the ToD of the first PRS (from the second message) and the ToA (recorded at the second station), a second difference between the ToD of the second PRS (recorded at the second station) and the ToA (from the second message), and the indication of whether a clock reconfiguration event occurred at the first station prior to the exchange of the first PRS and the second PRS. In some examples, the exchange of PRS can be part of a V2X sidelink positioning operation, where the PRS are transmitted via V2X sidelink within ITS spectrum. Further, the second message can be an ITS message.

[0047] Specifically, the second station can include a Kalman filter to estimate a clock error between the first station and the second station based on previous exchanges of PRS between the two stations and store the estimated clock error. The clock error can include a clock bias / offset between the clock sources of the first station and the second station and a clock drift of the clock sources. If the indication does not indicate that a clock reconfiguration event occurred at the first station prior to the exchange of the first PRS and the second PRS, the second station can perform a QCL operation of the clock error and combine the estimated clock error from the Kalman filter with the ToA and ToD of the first PRS and the second PRS to determine the RTT between the first station and the second station. On the other hand, if the indication indicates that a reconfiguration event occurred at the first station prior to the exchange of the first PRS and the second PRS, the second station can disable the QCL operation and restart the Kalman filter to generate a new estimate of the clock error and the RTT based on the ToA and ToD of the first PRS and the second PRS.

[0048] Further, the first message can include other information, such as an identifier of the first station. The identifier allows the second station to identify the first station and determine the location of the first station based on the identification. For example, the second station can access a database of identifiers of ground stations and their known locations. The second station can then obtain the location of the first station from the database based on the identifier. The second station can then determine its location based on the locations of the plurality of ground stations and their RTTs, as described above.

[0049] Further, the first message can also include transmission configuration information of the first PRS, which can help the second station detect the first PRS. For example, the transmission configuration information can indicate the spectrum resources, such as carrier frequency, used in the transmission of the first PRS. The second station can configure its wireless interface based on the transmission configuration information to demodulate the received radio signal to recover the first PRS. Further, in the case that the first PRS is transmitted on a licensed spectrum and the scheduled time of the transmission of the first PRS is known, the configuration information can indicate the scheduled time of the transmission of the first PRS. In this case, the first station can transmit the first message before the exchange of the first PRS and the second PRS between the two stations, which enables the second station to configure its wireless interface to detect the first PRS at the scheduled time of the transmission. On the other hand, in the case that the first PRS is transmitted on an unlicensed spectrum and the exact time of the transmission is not known, the first station can transmit the first message after the exchange of the first PRS and the second PRS between the two stations.

[0050] With the disclosed techniques, a wireless station on a vehicle can receive an indication of whether a clock reconfiguration event occurred at a ground station and decide, based on the indication, whether to perform a QCL operation of a previous clock error estimate or to re-estimate the clock error. Such an arrangement can reduce the likelihood that the vehicle refines RTT measurements obtained from PRS exchange with the ground station using an outdated clock error estimate, which in turn can improve the accuracy of sidelink positioning operations.

[0051] In the description herein, various examples are described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments can be practiced without the specific details. Furthermore, well-known features can be omitted or simplified in order not to obscure the embodiment being described.

[0052] Figure 1 An example wireless communication 110 in which the disclosed techniques can be used is shown. Referring to Figure 1The wireless communication system 110 includes UEs 112; 113; 114; base transceiver stations (BTSs) 120, 121, 122, 123; RSU 125; network 130; core network 140; and external client 150. The core network 140 (e.g., a 5G core network (5GC)) can include backend devices including an access and mobility management function (AMF) 141, a session management function (SMF) 142, a server 143, and a gateway mobile location center (GMLC) 144, among others. The AMF 141, SMF 142, server 143, and GMLC 144 are communicatively coupled to each other. The server 143 can be, for example, a location management function (LMF) that supports positioning of the UEs 112-114 (e.g., using techniques such as assisted global navigation satellite system (A-GNSS), observed time difference of arrival (OTDOA) (e.g., downlink (DL) OTDOA and / or uplink (UL) OTDOA), etc.), RTT, multi-cell RTT, real-time kinematic (RTK), precise point positioning (PPP), differential GNSS (DGNSS), enhanced cell ID (E-CID), angle of arrival (AoA), and angle of departure (AoD)).

[0053] The LMF can also be referred to as a location manager (LM), a location function (LF), a commercial LMF (CLMF), or a value-added LMF (VLMF). The server 143 (e.g., LMF) and / or one or more other devices of the system 110 (e.g., one or more of the UEs 112-114) can be configured to determine locations of the UEs 112-114. The server 143 can be in direct communication with and / or integrated with the BTS 121 (e.g., a gNode B (gNB)) and / or one or more other BTSs. The SMF 142 can serve as an initial point of contact for a service control function (SCF) (not shown) to create, control, and delete media sessions. The server 143 (e.g., LMF) can be co-located or integrated with a gNB or transmission / reception point (TRP), or can be disposed remotely from the gNB and / or TRP and configured to communicate directly or indirectly with the gNB and / or TRP.

[0054] The AMF 141 can serve as a control node processing signaling between the UEs 112-114 and the core network 140 and providing quality of service (QoS) flow and session management. The AMF 141 can support mobility of the UEs 112-114, including cell change and handover, and can participate in supporting a signaling connection to the UEs 112-114.

[0055] System 110 is capable of wireless communication because components of system 110 can communicate directly or indirectly with one another (at least sometimes using wireless connections), e.g., via BTSs 120-123, RSU 125, and / or network 130 (and / or one or more other devices not shown, such as one or more other transceiver base stations). While BTSs 120-123 are shown as separate from network 130, network 130 can include one or more of BTSs 120-123 and can constitute a radio access network (RAN), e.g., a New Radio (NR) RAN, which can also be referred to as a Fifth Generation (5G) Next Generation RAN (NG-RAN). For indirect communication, the communication can be changed during transmission from one entity to another, e.g., to change header information or change format of data packets. UEs 112-114 can communicate with BTSs 120-122 via a Uu interface, e.g., in Radio Resource Control-encapsulated Long-Term Evolution (LTE) Positioning Protocol (RRC-encapsulated LPP) messages over the Uu interface. UEs 112-114 can also communicate with RSU 125 via PC5 and other sidelink interfaces. The illustrated UEs 112-114 are smartphones, tablets, and vehicle-based devices, but these are just examples because UEs 112-114 do not require to be any of these configurations and other configurations of UEs can be used. The illustrated UEs 112, 113 are mobile wireless communication devices (although they can communicate wirelessly and via wired connections), including mobile phones (including smartphones) and tablets. The illustrated UE 114 is a vehicle-based mobile wireless communication device (although UE 114 can communicate wirelessly and via wired connections). In one example, UE 114 can communicate with RSU 125 via a sidelink, such as a V2X PC5 interface. Other UEs can include wearable devices (e.g., smartwatches, smart jewelry, smart glasses, or smart earpieces). Other UEs can also be used, whether currently existing or developed in the future. Moreover, other wireless devices (whether mobile or not) can be implemented within system 110 and can communicate with one another and / or with UEs 112-114, BTSs 120-123, network 130, core network 140, and / or external client 150. For example, such other devices can include Internet of Things (IoT) devices, medical devices, home entertainment, reduced capability UEs (e.g., NR light UEs), and / or automation devices. Core network 140 can communicate with external client 150 (e.g., a computer system), e.g., to allow external client 150 to request and / or receive location information about UEs 112-114 (e.g., via GMLC 144).

[0056] UE 112-114 or other devices can be configured to operate in various networks and / or for various purposes and / or use various technologies (e.g., 5G, Wi-Fi communication, multiple frequencies of Wi-Fi communication, satellite positioning, one or more types of communication (e.g., Global Mobile System (GSM), Code Division Multiple Access (CDMA), LTE, V2X (e.g., vehicle to pedestrian (V2P), vehicle to infrastructure (V2I), vehicle to vehicle (V2V)), IEEE 112-114 or other devices). Communication can be achieved using cellular networks (such as 802.11p). V2X communication can be cellular (C-V2X) and / or WiFi (e.g., Dedicated Short Range Connectivity (DSRC)). System 110 can support operation on multiple carriers (waveform signals of different frequencies). A multi-carrier transmitter can simultaneously transmit modulated signals on multiple carriers. Each modulated signal can be a CDMA signal, a Time Division Multiple Access (TDMA) signal, an Orthogonal Frequency Division Multiple Access (OFDMA) signal, a Single Carrier Frequency Division Multiple Access (SC-FDMA) signal, etc. Each modulated signal can be transmitted on a different carrier and can carry pilot information, overhead information, data, etc.

[0057] BTS 120–123 and RSU 125 can wirelessly communicate with UE 112–114 in system 110 via one or more antennas. A BTS can also be referred to as a BS, access point, gNB, access node (AB), node B, evolved node B (eNB), etc. For example, each of BTS 120 and 121 can be a gNB or transmitting point gNB, BTS 122 can be a macro cell (e.g., a high-power cellular BS) and / or a small cell (e.g., a low-power cellular BS), and BTS 123 can be an access point (e.g., configured to use methods such as WiFi, WiFi Direct (WiFi-D), Bluetooth). Bluetooth Low Energy (Short-range BS that communicates using short-range technologies such as BLE and Zigbee). One or more of BTS 120-123 can be configured to communicate with UE 112-114 via multiple carriers. BTS 120–123 can be configured as RSU 125. Each of BTS 120, 121 can provide communication coverage for a corresponding geographic area (e.g., a cell). Each cell can be divided into multiple sectors based on the BS antenna.

[0058] BTS 120-123 each include one or more TRPs. For example, each sector within a cell of a BTS can include a TRP, although multiple TRPs can share one or more components (e.g., share one processor but have separate antennas). System 110 can include only macro TRPs, or system 110 can have different types of TRPs, such as macro TRPs, pico TRPs, and / or femto TRPs. Macro TRPs can cover a relatively large geographic area (e.g., a few kilometers in radius) and can allow unrestricted access to terminals with service subscription. A pico TRP can cover a relatively small geographic area (e.g., a pico cell) and can allow restricted access to terminals with service subscription. A femto or home TRP can cover a relatively small geographic area (e.g., a femto cell) and can allow restricted access to terminals associated with the femto cell, such as terminals of a family of a subscriber.

[0059] UE 112-114 can be referred to as a terminal, access terminal (AT), mobile station, mobile device, subscriber unit, etc. UE 112-114 can include various devices listed above and / or other devices. UE 112-114 can be configured to connect indirectly to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. The D2D P2P links can be supported by any suitable D2D radio access technology (RAT), such as LTE Direct (LTE-D), WiFi-D, Bluetooth, etc. One or more of a group of UEs 112-114 utilizing D2D communications can be within the geographic coverage area of a TRP such as one or more of BTSs 120-123. Other UEs in such a group can be outside the geographic coverage area of such TRPs or be otherwise unable to receive transmissions from a BS. A group of UEs 112-114 communicating via D2D communications can utilize a one-to-many (1:M) system in which each UE can transmit to other UEs in the group. The TRPs of BTSs 120-123 can facilitate scheduling of resources for D2D communications. In other cases, D2D communications can be carried out between UEs without the involvement of TRPs. For example, UE 114 can communicate with RSU 125 via a sidelink in licensed and / or unlicensed spectrum.

[0060] Figure 2 An example of a UE 200 is shown, which can implement UEs 112-114 of Figure 1 Reference is made to Figure 2 ​The UE 200 includes a computing platform that includes a processor 210, a memory 211 that includes software (SW) 212, one or more sensors 213, a transceiver interface 214 for a transceiver 215, and a user interface 216. The processor 210, the memory 211, the sensors 213, the transceiver interface 214, and the user interface 216 can be communicatively coupled to each other by a bus 220, which can be configured, for example, for optical and / or electrical communication. One or more components shown (e.g., one or more of the sensors 213) can be omitted from the UE 200.

[0061] The processor 210 can include one or more intelligent hardware devices, such as a central processing unit (CPU), a microcontroller, or an application-specific integrated circuit (ASIC). The processor 210 can include multiple processors, including a general-purpose / application processor 230, a digital signal processor (DSP) 231, a modem processor 232, a video processor 233, and / or a sensor processor 234. One or more of the processors 230-234 can include multiple devices (e.g., a plurality of processors). For example, the sensor processor 234 can include, for example, processors for radar, ultrasound, and / or light detection and ranging (LIDAR). The modem processor 232 can support dual Subscriber Identity Modules or Subscriber Identity Module (SIM) / dual connectivity (or even more SIMs). For example, a SIM can be used by an original equipment manufacturer (OEM), and another SIM can be used by an end user of the UE 200 for connectivity. The memory 211 is a non-transitory storage medium that can include random access memory (RAM), flash memory, disc storage, and / or read-only memory (ROM) 211, among others. The memory 211 stores the SW 212, which can be processor-readable and processor-executable software code containing instructions that are configured to, when executed, cause the processor 210 to perform various functions described herein. Alternatively, the SW 212 can not be directly executable by the processor 210 but can be configured to cause the processor 210 to perform functions, e.g., when compiled and executed. This description can refer only to the processor 210 executing the software, but is also intended to cover

[0062] Figure 2The configuration of the UE 200 shown in FIG. 2 is an example and not limiting of the present disclosure, including the claims, and other configurations can be used. For example, example configurations of the UE include one or more of the processors 230-234 of the processor 210, the memory 211, and the wireless transceiver 240. Other example configurations include one or more of the processors 230-234 of the processor 210, the memory 211, the wireless transceiver 240, and one or more of the sensors 213, the user interface 216, and / or the wired transceiver 250.

[0063] The UE 200 can include a modem processor 232, which can be capable of performing baseband processing of signals received and down-converted by the transceiver 215 and / or a satellite positioning system (SPS) receiver 281 (discussed below). The modem processor 232 can perform baseband processing of signals to be up-converted for transmission by the transceiver 215. Additionally or alternatively, baseband processing can be performed by the processor 230 and / or the DSP 231. However, other configurations can be used to perform baseband processing.

[0064] The UE 200 includes sensors 213, which can include one or more of various types of sensors, such as environmental sensors 260, status sensors 270, and positioning / motion / orientation (PMO) sensors 280. The PMO sensors 280 can include one or more sensors from which positioning and / or motion and / or orientation of the UE 200 can be determined. While each of the sensors 260, 270, 280 can be referred to in the singular, each of the sensors 260, 270, 280 can include more than one sensor, examples of some of which are expressly discussed herein. The sensors 213 can generate analog and / or digital signals indicative, which can be stored in the memory 211 and processed by the processor 210 (e.g., the processor 230, the DSP 231, the video processor 233, and / or the sensor processor 234, as appropriate) to support one or more applications, such as applications directed to positioning, navigation, and / or resource management. The description herein can generally refer to the processor 210 as performing one or more functions performed by one or more of the processors 230-234.

[0065] The sensors 213 can be used for resource management, relative position measurement, relative position determination, motion determination, etc. Information detected by the sensors 213 can be used to determine how to allocate resources of the UE 200, e.g., transmit power, processing power for transmitting and / or receiving communication signals, transmit and / or receive directionality. Throughout this document the complex term “resources” is often used, but the term also includes the singular, i.e., a single resource, e.g., a resource being allocated. Additionally or alternatively, information detected by the sensors can be used for motion detection, relative displacement, dead reckoning, sensor-based position determination, and / or sensor-assisted position determination. The sensors 213 can be used to determine whether the UE 200 is fixed (stationary) or mobile and / or whether to report certain useful information about mobility of the UE 200 to the server 120. For example, based on information obtained / measured by the sensors 213, the UE 200 can inform / report to the server 120 that the UE 200 has detected movement or that the UE 200 has moved and report a relative displacement / distance (e.g., via dead reckoning enabled by the sensors 213, or sensor-based position determination, or sensor-assisted position determination). In another example, for relative positioning information, sensors / inertial measurement units (IMUs) can be used to determine an angle and / or orientation of another device relative to the UE 200, etc. Positioning and / or motion of the UE 200 can be used to determine resource allocation for communications, e.g., resource allocation for communications between vehicles or between a vehicle and an RSU. The UE 200 can be disposed in or integrated with a vehicle, e.g., the UE 200 can be a UE 114 that is a vehicle, in the illustrated example a car, although other forms of vehicles can be used, e.g., a truck or an aerial UE such as a drone. As such, the UE 200 can be configured for various forms of communications, e.g., V2V, V2X (vehicle-to-everything), cellular V2X (CV2X), cellular V2 (CV2V). Figure 1

[0066] ​The environmental sensors 260 can include one or more sensors to measure one or more internal and / or external environmental conditions. In this example, the environmental sensors 260 include a camera 261, a microphone 262, an air flow sensor 263, a temperature sensor 264, a motion sensor 265, and a LIDAR (light detection and ranging) sensor 266. While each of the sensors 261-266 can be referred to in the singular, each of the sensors 261-266 can include more than one sensor, examples of some of which are discussed explicitly herein. For example, the camera 261 can include at least one camera configured (e.g., designed, manufactured, arranged, and directed) to capture images outside the UE 200, and / or can include one or more cameras configured to capture images inside the UE 200 (e.g., in a passenger cabin of a vehicle). As other examples, the microphone 262, the temperature sensor 264, and / or the motion sensor 265 can include multiple microphones, multiple thermometers, and / or multiple motion detectors configured to detect sound, temperature, and / or motion, respectively, outside and / or inside the vehicle. Indeed, any of the sensors 261-265 can include multiple respective sensors outside the vehicle and / or multiple respective sensors inside the vehicle for making respective measurements at multiple locations around the vehicle and / or in different directions relative to the vehicle. The sensors 261-265 are examples, and one or more of the sensors 261-265 can be omitted from the UE 200, and / or one or more other sensors can be included in the UE 200. For example, the environmental sensors 260 can include one or more barometric pressure sensors and / or one or more ambient light sensors and / or one or more other sensors.

[0067] The camera 261 can be configured to capture still images and / or motion images. For example, each camera of the camera 261 can include, e.g., an imaging sensor (e.g., a charge-coupled device or a complementary metal-oxide-semiconductor (CMOS) imager), a lens, analog-to-digital circuitry, or a frame buffer. Additional processing, conditioning, encoding, and / or compression of signals representing captured images can be performed by the general-purpose processor 230 and / or the DSP 231. Additionally or alternatively, the video processor 233 can perform conditioning, encoding, compression, and / or manipulation of signals representing captured images. The video processor 233 can decode / compress stored image data for presentation on a display device (not shown) of the user interface 216, for example.

[0068] The motion detector 265 is configured to detect motion using known techniques. For example, the motion detector 265 can transmit and receive sound waves (e.g., ultrasonic signals) and analyze the received signals for a Doppler effect indicative of motion. The use of multiple motion detectors can facilitate identifying the relative location of an object (e.g., the direction relative to the UE 200).

[0069] The LIDAR sensor 266 is configured to determine a distance to an object, which the processor 210 can use to detect the presence of the object. The use of multiple LIDAR sensors can facilitate identifying the relative location of an object (e.g., the direction relative to the UE 200). The LIDAR sensor 266 can be referred to as a laser radar (LADAR) sensor, which is common when using a LIDAR sensor to detect relatively small objects such as vehicles or other artificial (man-made) objects.

[0070] The status sensor 270 is configured to provide one or more indications of one or more vehicle conditions associated with the vehicle with which the UE 200 is associated. For example, a vehicle condition can include the gear state of the vehicle (e.g., whether the vehicle is in park, drive, or neutral, or which gear the vehicle is currently in). Another vehicle condition can be whether the emergency brake is engaged. Another vehicle condition can be whether the primary brakes are currently engaged and possibly to what extent. Another vehicle condition can be whether the accelerator is currently engaged and possibly to what extent. Another vehicle condition can be the state of the steering wheel (e.g., in which direction it is turned and by how much). Other example vehicle conditions can include whether the right turn indicator is activated, whether the left turn indicator is activated, and / or whether the hazard lights (also known as “four-ways” or emergency flashers, etc.) are activated. Another example vehicle condition can include a tire state (e.g., tire pressure, rate of change of tire pressure (e.g., indicating a flat or blown tire)). Another example vehicle condition is the speed recorded by the speedometer of the vehicle. These vehicle conditions are examples, and one or more other sensors can be provided to sense one or more other vehicle conditions.

[0071] The PMO sensors 280 can include one or more sensors to provide one or more vehicle conditions. For example, the PMO sensors 280 can include one or more sensors to measure information from which a position and / or motion and / or orientation of the UE 200 can be determined and possibly determine a position and / or motion and / or orientation of the UE 200. In this example, the PMO sensors 280 include an SPS receiver 281, a positioning device (PD) 282, an IMU 283, and a magnetometer 284. The components of the PMO sensors 280 shown are examples, and one or more of these components can be omitted and / or one or more other components can be included in the PMO sensors 280. Further, while each of the components 281-284 of the PMO sensors 280 can be referred to in the singular, each of the components 281-284 can include more than one such component, examples of some of which are discussed explicitly herein. Further, the PD 282 can be part of the SPS receiver 281 and / or the IMU 283 and / or part of the processor 210, and can not itself be a sensor (e.g., can not make measurements), but can process information from one or more of the sensors 281, 283, 284 and / or one or more other sensors.

[0072] The IMU 283 can include one or more inertial sensors, such as an accelerometer 287 (e.g., responsive to linear acceleration of the UE 200 in three dimensions) and / or a gyroscope 288. While each of the sensors 287, 288 can be referred to in the singular, each of the sensors 287, 288 can include more than one sensor. The IMU 283 can be configured to provide measurements regarding a direction of motion and / or a speed of motion of the UE 200, which can be used, for example, for relative position determination. For example, the accelerometer 287 and / or the gyroscope 288 of the IMU 283 can detect linear acceleration and rotational velocity of the UE 200, respectively. Linear acceleration and rotational velocity measurements of the UE 200 can be integrated over time (e.g., by the IMU 283 and / or the PD 282) to determine an instantaneous direction of motion and a displacement of the UE 200. The instantaneous direction of motion and the displacement can be integrated to track a position of the UE 200. For example, a reference position of the UE 200 can be determined, e.g., at some time instance, using the SPS receiver 281 (and / or by some other means), and measurements obtained from the accelerometer 287 and the gyroscope 288 after that time instance can be used for dead reckoning to determine a current position of the UE 200 based on movement (direction and distance) of the UE 200 relative to the reference position.

[0073] Magnetometer 284 can determine magnetic field strength in different directions, which can be used to determine an orientation of UE 200, which can be used, for example, to provide a digital compass for UE 200. Magnetometer 284 can include a two-dimensional magnetometer configured to detect and provide an indication of magnetic field strength in two orthogonal dimensions. Additionally or alternatively, magnetometer 284 can include a three-dimensional magnetometer configured to detect and provide an indication of magnetic field strength in three orthogonal dimensions. Magnetometer 284 can provide a means for sensing a magnetic field and providing an indication of the magnetic field to, for example, processor 210. Magnetometer 284 can provide measurements to determine an orientation (e.g., relative to magnetic north and / or true north), which can be used for any of a variety of purposes, such as to support one or more compass applications.

[0074] SPS receiver 281 (e.g., a GPS receiver or other GNSS receiver) can be capable of receiving and acquiring SPS signals 285 via SPS antenna 286. Antenna 286 is configured to convert wireless signals 285 into wired signals, such as electrical or optical signals, and can be integrated with antenna 246. SPS receiver 281 can be configured to process acquired SPS signals 285, in whole or in part, to estimate a location of UE 200. For example, SPS receiver 281 can be configured to use SPS signals 285 to determine a location of UE 200 through trilateration. General-purpose processor 230, memory 211, DSP 231, and / or one or more special-purpose processors (not shown) can be used to process acquired SPS signals, in whole or in part, and / or in conjunction with SPS receiver 281 to calculate an estimated location of UE 200. Memory 211 can store indications (e.g., measurements) of SPS signals 285 and / or other signals (e.g., acquired from wireless transceiver 240) for use in performing positioning operations. General-purpose processor 230, DSP 231, and / or one or more special-purpose processors and / or memory 211 can provide or support a location engine for processing measurements to estimate a location of UE 200. Additionally or alternatively, some or all of the positioning determination signal processing can be performed by PD 282.

[0075] The PD 282 can be configured to determine a position of the UE 200 (including an absolute and / or relative position of the UE 200), a motion of the UE 200, and / or a time. For example, the PD 282 can be in communication with and / or include some or all of the SPS receiver 281. The PD 282 can use measurements from the SPS receiver 281 and / or the IMU 283 and / or the magnetometer 284 to determine a position and / or motion of the UE 200, e.g., using trilateration or dead reckoning. The PD 282 can optionally be in combination with the processor 210 and the memory 211 to perform at least a portion of one or more positioning methods (to determine a position of the UE 200), although the description herein can refer only to the PD 282 being configured to perform or being performing according to the positioning methods. The PD 282 can additionally or alternatively be configured to determine a position of the UE 200 using trilateration with terrestrial-based signals (e.g., at least some of the signals 248 discussed below) to assist in obtaining and using SPS signals 285 or both. The PD 282 can be configured to determine a position of the UE 200 using one or more other techniques (e.g., depending on a self-reported location of the UE (e.g., part of a location beacon of the UE)) and can use a combination of techniques (e.g., SPS and terrestrial positioning signals) to determine a position of the UE 200. The PD 282 can be configured to provide an indication of uncertainty and / or error in a determined position and / or motion.

[0076] Transceiver 215 may include wireless transceiver 240 and / or wired transceiver 250, which are configured to communicate with other devices via wireless and wired connections, respectively. For example, wireless transceiver 240 may include a transmitter 242 and a receiver 244 coupled to one or more antennas 246 for transmitting (e.g., on one or more uplink channels) and / or receiving (e.g., on one or more downlink channels) wireless signals 248 and converting signals from wireless signals 248 into wired (e.g., electrical and / or optical) signals and from wired signals into wireless signals 248. Wireless transceiver 240 may be configured for wireless communication to send communications to and receive communications from various entities such as other UEs or BSs. Therefore, transmitter 242 may include multiple transmitters that may be discrete components or combined / integrated components, and / or receiver 244 may include multiple receivers that may be discrete components or combined / integrated components. The wireless transceiver 240 can be configured to transmit signals according to various RATs (e.g., with TRP and / or one or more other devices), such as 5G NR, GSM, Universal Mobile Telecommunications System (UMTS), Advanced Mobile Telecommunications System (AMPS), CDMA, Wideband CDMA (WCDMA), LTE, LTE-D, 3GPP LTE-V2X (PC5), IEEE 802.11 (including IEEE 802.11p), WiFi, WiFi-D, and Bluetooth. Or Zigbee. NR can use millimeter wave frequencies and / or sub-6 GHz frequencies. Wired transceiver 250 may include transmitter 252 and receiver 254, configured for, for example, wired communication with network 130 to send and receive communications to, for example, a gNB. Transmitter 252 may include multiple transmitters, which may be discrete components or combined / integrated components, and / or receiver 254 may include multiple receivers, which may be discrete components or combined / integrated components. Wired transceiver 250 may be configured for, for example, optical and / or electrical communication. Transceiver 215 may be communicatively coupled to transceiver interface 214, for example, via optical and / or electrical connections. Transceiver interface 214 may be at least partially integrated with transceiver 215.

[0077] The user interface 216 can include one or more of a number of devices, such as a speaker, a microphone, a display device, a vibration device, a keyboard, or a touchscreen. The user interface 216 can include more than one of any of these devices. The user interface 216 can be configured to enable a user to interact with one or more applications hosted by the UE 200. For example, the user interface 216 can store indications of analog and / or digital signals in the memory 211 to be processed by the DSP 231 and / or the general-purpose processor 230 in response to actions from a user. Similarly, applications hosted on the UE 200 can store indications of analog and / or digital signals in the memory 211 to present output signals to a user. The user interface 216 can include an audio input / output (I / O) device including, for example, a speaker, a microphone, digital-to-analog circuitry, analog-to-digital circuitry, amplifiers, and / or gain control circuitry including any of more of these devices. Other configurations of audio I / O devices can be used. Additionally or alternatively, the user interface 216 can include one or more touch sensors capable of responding to touch and / or pressure, such as on a keyboard and / or touchscreen of the user interface 216.

[0078] The UE 200 also includes a clock module 290. The clock module 290 can provide one or more clock signals to various components of the UE 200, including, for example, the processor 210, the sensor 213, the transceiver interface 214, the transceiver 215, and the user interface 216, to control timing of operations of these components. The clock module 290 can also maintain a local clock source. The local clock source can provide time measurements of various events, such as transmission and reception of certain wireless signals. As described below, the time measurements can support V2X-sidekick positioning operations.

[0079] Figure 3 An example of an RSU 300 of an RSU 125 that can implement Figure 1 is shown. Reference is made to Figure 3The RSU 300 includes a computing platform that includes a processor 310, a memory 311 that includes SW 312, and a transceiver 315. The processor 310, the memory 311, and the transceiver 315 can be communicatively coupled to each other by a bus 320, which can be configured, for example, for optical and / or electrical communication. One or more of the illustrated devices (e.g., wired interfaces) can be omitted from the RSU 300. The processor 310 can include one or more intelligent hardware devices, e.g., CPUs, microcontrollers, or ASICs. The processor 310 can include multiple processors. The memory 311 is a non-transitory storage medium that can include RAM, flash memory, disk storage, and / or ROM, among others. The memory 311 stores the SW 312, which can be processor-readable, processor-executable software code containing instructions that are configured to, when executed, cause the processor 310 to perform various functions described herein. Alternatively, the SW 312 can not be directly executable by the processor 310 but can be configured to cause the processor 310 to perform functions, e.g., on compilation and execution. The description can refer only to the processor 310 executing the software, but is also intended to cover any implementation that includes the processor 310 executing software and / or firmware. The description can refer to the processor 310 executing the SW 312 to perform certain functions, but this is also intended to cover any implementation in which the processor 310 executes software and / or firmware to perform certain functions, e.g., in which the processor 310 executes software and / or firmware that causes the processor 310 to perform those functions. The description can refer to the RSU 300 (and thus one of the BTSs 120-123) performing certain functions, which can refer to the processor 310 within the RSU 300 performing those functions, in conjunction with the SW 312 stored in the memory 311. The functions of the processor 310 are discussed more fully below.

[0080] The transceiver 315 can include a wireless transceiver 340 or a wired transceiver 350, the wireless or wired transceiver configured to communicate with other devices through wireless and wired connections, respectively. For example, the wireless transceiver 340 can include a transmitter 342 and a receiver 344 coupled to one or more antennas 346 for transmitting (e.g., on one or more uplink or sidelink channels) and / or receiving (e.g., on one or more downlink or sidelink channels) wireless signals 348 and transducing signals from and into the wireless signals 348. Thus, the transmitter 342 can include multiple transmitters that can be discrete components or combined / integrated components, and / or the receiver 344 can include multiple receivers that can be discrete components or combined / integrated components. The wireless transceiver 340 can be configured to communicate signals (e.g., with the UE 200, one or more other UEs, and / or one or more other devices) in accordance with various RATs, such as 5G NR, GSM, UMTS, AMPS, CDMA, WCDMA, LTE, LTE-D, 3GPP LTE-V2X (PC5), IEEE 802.11 (including IEEE 802.11p), WiFi, WiFi-D, Bluetooth, or Zigbee. The wired transceiver 350 can include a transmitter 352 and a receiver 354 configured for wired communication, e.g., with the network 130 to transmit communications to and receive communications from, e.g., the server 143. The transmitter 352 can include multiple transmitters that can be discrete components or combined / integrated components, and / or the receiver 354 can include multiple receivers that can be discrete components or combined / integrated components. The wired transceiver 350 can be configured for, e.g., optical and / or electrical communication. or Zigbee). The wired transceiver 350 can include a transmitter 352 and a receiver 354 configured for wired communication, e.g., with the network 130 to transmit communications to and receive communications from, e.g., the server 143. The transmitter 352 can include multiple transmitters that can be discrete components or combined / integrated components, and / or the receiver 354 can include multiple receivers that can be discrete components or combined / integrated components. The wired transceiver 350 can be configured for, e.g., optical and / or electrical communication.

[0081] The RSU 300 also includes a clock module 360. The clock module 360 can provide one or more clock signals to various components of the RSU 300, including, e.g., the processor 310 and the transceiver 315, to control timing of operations of these components. The clock module 360 can also maintain a local clock source. The local clock source can provide time measurements for various events, such as transmission and reception of certain wireless signals. As described below, the time measurements can support V2X-sidekick positioning operations.

[0082] Figure 3The configuration of the RSU 300 shown in FIG. 3 is an example and not limiting of the application, including the claims, and other configurations can be used. For example, the description herein discusses the RSU 300 being configured to perform or performing several functions, but one or more of these functions can be performed by the server 143 and / or the UE 200 (i.e., the server 143 and / or the UE 200 can be configured to perform one or more of these functions).

[0083] Figure 4A and Figure 4B An example of positioning operations that can be performed between the UE 200 and the RSU 300 is shown. As Figure 4A shown, multiple RSUs, including RSUs 402 and 404, can be disposed along a road 410. Each of the RSUs 402 and 404 can include Figure 3 the RSU 300. The RSUs 402 and 404 can be configured in traffic lights, for example, or other roadside fixtures, such as a light pole or a road sign. Each of the RSUs 402 and 404 can exchange PRS with a vehicle 412 on the road 410, including PRS 406a and 406b for the RSU 402 and PRS 408a and 408b for the RSU 404, which can include the UE 200. Based on the exchanged PRS, the vehicle 412 can determine RTTs and a time offset of the PRS between the RSUs 402 and 404. With the locations of the RSUs 402 and 404 known, and based on the time offset of the PRS between the RSUs 402 and 404, the vehicle 412 can determine its location based on, for example, OTDOA operations.

[0084] Figure 4B An example of a message flow 420 between an RSU (e.g., the RSU 402) and a vehicle (e.g., the vehicle 412) to support Figure 4A example positioning operations is shown. As Figure 4BAs shown, in stage 422 of the positioning operation, RSU 402 can transmit a message 424 that includes an identifier 426a and transmission configuration information 426b. Identifier 426a can include an identifier of RSU 402, such as a source identifier (source ID), which can be used by vehicle 412 to identify RSU 402 and determine the location of the first station based on the identification. For example, vehicle 412 can access a database that includes identifiers of a set of ground stations, including RSUs 402 and 404, and their known locations. Vehicle 412 can then obtain the location of RSU 402 from the database based on the identifier for OTDOA operations. In addition, transmission configuration information 426b can assist vehicle 412 in detecting PRS from RSU 402. For example, the configuration information can indicate the spectrum resources, such as carrier frequencies, used by the RSU in the transmission of PRS. Vehicle 412 can then configure its wireless interface based on the transmission configuration information to demodulate the received radio signals to recover PRS. In addition, in cases where the RSU transmits PRS on a licensed spectrum and the scheduled time of the RSU’s transmission of PRS is known, the transmission configuration information can indicate the scheduled time of the transmission of PRS.

[0085] In stage 430 of the positioning operation, RSU 402 and vehicle 412 can exchange PRS. Specifically, RSU 402 can transmit PRS 432 to vehicle 412. RSU 402 can record the ToD of PRS 432 at time tl based on its local clock source provided by clock module 360 of RSU 402, while vehicle 412 can record the ToA of PRS 402 at time t2 based on its local clock source provided by clock module 290 of vehicle 412. Figure 3 In addition, vehicle 412 can transmit PRS 434 to RSU 402. Vehicle 412 can record the ToD of PRS 434 at time t3 based on its local clock source provided by clock module 290 of vehicle 412, while RSU 402 can record the ToA of PRS 434 at time t4 based on its local clock source provided by clock module 360 of RSU 402. Figure 2 Figure 2 Figure 3

[0086] In stage 440 of the positioning operation, RSU 402 can provide vehicle 412 with information including times tl and t4 in a message, such as ITS message 442 in V2X implementations. Based on the recorded times tl and t4, vehicle 412 can calculate the RTT between vehicle 412 and RSU 402 based on the following equation:

[0087] RTT RSU-402 = (t4 - t3) + (t2 - tl) (Equation 1)

[0088] ​​​Vehicle 412 can repeat the positioning operation 420 with other RSUs such as RSU 404 and obtain other RTT measurements with the other RSUs. Vehicle 412 can then estimate the time offset of the PRS between RSUs 402 and 404 to vehicle 412 based on the RTT difference. Based on the time offset and the known locations of RSUs 402 and 404, vehicle 412 can estimate its location based on the following equations:

[0089]

[0090] In Equations 1 and 2, AT represents the time offset computed based on the RTT difference between RSUs 402 and 404, x veh and y veh represent the coordinates of vehicle 412 to be determined, x 402 and y 402 represent the known coordinates of RSU 402, and x 404 and y 40 represent the known coordinates of RSU 404, and c represents the speed of light. Equation 2 assumes that PRS 432 and 434 propagate via a direct line-of-sight path between vehicle 412 and RSU 402 (and RSU 404) such that the direct distance between the vehicle and the RSU is represented by the ToF of the PRS (e.g., t4-t3 and t2-t1 in Equation 1).

[0091] In Figure 4B , stage 422 of the positioning operation (in which RSU 402 sends the identifier 426a and sends configuration information 426b) can occur before stage 424 in which RSU 402 and vehicle 412 exchange PRS. Such an arrangement can be provided in cases where the RSU transmits PRS on a licensed spectrum and the scheduled time of the RSU’s transmission of PRS is known, and the transmission configuration information 426b indicates the scheduled time of the transmission of PRS. On the other hand, in cases where PRS is transmitted on an unlicensed spectrum and the exact time of transmission is not known, the RSU can transmit message 424 after the exchange of PRS 432 and 434, and stage 422 can be performed after stage 430. For example, in a V2X implementation, the RSU can be configured to broadcast PRS 432 on an unlicensed spectrum via a sidelink based on a D2D protocol such as PC5. Other messaging protocols and spectrums can be used. Vehicle 412 can then use the same interface to transmit PRS 434. ToA information for the PRS transmissions can then be exchanged using ITS messaging in the V2X spectrum.

[0092] The accuracy of the RTT measurements, and hence the accuracy of the vehicle’s positioning estimate, can be reduced due to clock errors / differences between the vehicle and the ground station. Figure 5A andFigure 5B The impact of clock error on RTT measurement is shown. Specifically, referring to Figure 5A , ToD recorded for PRS 432 and ToA recorded for PRS 432 truly represent the ToF between the vehicle and the RSU 402 only when both ToA and ToD are measured using the same clock source. In Figure 5A , ToD has a timestamp of ti starting from a reference time To, while ToA has a timestamp of t2starting from the same reference time To. Since both ToD and ToA are measured with respect to the same reference time, the difference between ToD and ToA can represent the time taken by PRS 432 when the signal travels from RSU 402 to vehicle 412.

[0093] On the other hand, RSU 402 and vehicle 412 have two different clock sources (e.g., Figure 2 clock module 290 of vehicle 412 and Figure 3 clock module 360 of RSU 402), and the two clock sources are not necessarily synchronized with each other. Thus, there is a static clock bias / offset (T bias ) between the clocks of RSU 402 and the reference time To of RSU 402 and the reference time To’ of vehicle 412. In addition, each clock source can have random clock drifts (e.g., T drift0 , T drift1 , T drift2 , etc.) caused by random noise (e.g., thermal noise, phase noise). The clock bias and clock drifts can introduce clock error between the two clock sources. Thus, the difference between recorded ToD and ToA includes a first component representing the true ToF of PRS 432 between RSU 402 and vehicle 412, and a second component caused by the clock error between the two clock sources. For example, in Figure 5B , the difference between ti (timestamp of ToD of PRS 432 at RSU 402) and t2 (timestamp of ToA of PRS 432 at vehicle 412) includes clock offset T bias and random clock drift T drift0 when ti is recorded and random clock drift T drift2 when t2 is recorded. The actual RTT between vehicle 412 and RSU 402 can be represented by the following equation:

[0094] RTT RSU-402-actual = (t4 - t3) + (t2 - ti) + clock_error (Equation 3)

[0095] In Equation 3, clock_error can represent the clock error between vehicle 412 and RSU 402, and can include clock offset Tbias and random clock drift T drift0 and T drift1 Actual RTT is RTT. RSU-402-actual This can represent the actual relative distance between RSU402 and vehicle 412. As shown in Equation 3, if vehicle 412 uses the time difference between t1 and t2 as the Time of Flight (ToF) from RSU402 to vehicle 412 without considering the clock error component, the clock error may cause an overestimation or underestimation of the relative distance between RSU402 and vehicle 412, and introduce errors into the positioning estimation of vehicle 412.

[0096] To reduce the impact of clock errors on the accuracy of RTT measurements, vehicle 412 can use techniques such as Kalman filtering to estimate the true RTT between vehicle and RSU 402, as well as the clock error based on multiple instances of PRS exchanges between vehicle 412 and RSU 402. Figure 5C An example of a Kalman filter 500 that can be implemented in vehicle 412 is shown. In some examples, the Kalman filter 500 can be implemented as part of SW 212, which can be executed by processor 230. Figure 5C As shown, the Kalman filter 500 may include a prediction module 502, an update module 504, a measurement module 506, and a state storage device 508. At the start of the estimation operation, the measurement module 506 may combine first samples (t1(0), t1(0), t2(0), and t3(0)) of ToA and ToD from the first PRS exchange with a default clock error (error(0)) to generate a first RTT measurement (RTTm(0)) based on the first PRS exchange. The update module 504 may store the first RTT measurement as a first RTT estimate (RTTe(0)) in the state storage device 508 as an initial RTT state variable. The measurement module 506 may also output the first RTT estimate as an RTT output 520 of sample(0).

[0097] The Kalman filter 500 can then revise the RTT estimate and the clock error estimate based on the second samples of ToA and ToD from the second PRS exchange. Specifically, the prediction module 502 can estimate a second RTT (RTT(l)) that would be obtained in the second PRS exchange. This estimate can be based on, for example, the speed of the vehicle 412 and the time elapsed between the first PRS exchange and the second PRS exchange. The measurement module 506 can also perform a measurement of the second RTT (RTTm(l)) based on the second samples of ToA and ToD (tl(l), tl(l), t2(l), and t3(l)) and the default clock error (error(0)). The update module 504 can compare the second RTT measurement (RTTm(l)) to the second RTT estimate (RTTe(l)) to determine a difference between the default clock error and the actual clock error, and can update the clock error state variable to become error(l) based on the difference. The RTT estimate is also revised based on the revised clock error (error(l)) and the second samples of ToA and ToD. The measurement module 506 can recompute the second RTT measurement based on the revised clock error (error(l)) and generate an RTT output 520 for sample(l). The Kalman filtering process can then be repeated for subsequent samples of ToA and ToD (e.g., tl(n), t2(n), t3(n), and t4(n)) to refine the estimate of the clock error.

[0098] Figure 5D The change in the difference between the estimated clock error and the actual clock error from the Kalman filter 500 is shown. In Figure 5D , a plot 512 indicating the difference between the estimated clock bias and the actual clock bias and a plot 514 indicating the difference between the estimated clock drift and the actual clock drift are shown. As Figure 5D shown, both the difference between the estimated clock bias and the actual clock bias and the difference between the estimated clock drift and the actual clock drift are reduced between samples by the Kalman filtering process on multiple samples of ToA and ToD. The Kalman filter process can be repeated for additional samples of ToA and ToD until the Kalman filter reaches a steady state. The steady state can be reached, for example, when the change in the clock error state variable (e.g., error(n-1) and error(n)) between two sets of samples of ToA and ToD is below a threshold. When the steady state is reached, the Kalman filter 500 can stop updating the RTT state variables and the clock error state variables in the state storage 508. The measurement module 506 can then output the RTT measurement generated by the steady state clock error for sample(n) of ToA and ToD as the RTT output 520.

[0099] When the Kalman filter reaches steady state, the vehicle 412 can use the steady-state clock error to refine RTT measurements from subsequent PRS exchanged between the vehicle and the ground station in a QCL operation. Figure 5E An example of a QCL operation performed by a QCL module 530, which can be part of the vehicle 412, is shown. In some examples, the QCL module 530 can be implemented as SW 212 executable on the processor 230. As Figure 5E shown, when the Kalman filter 500 reaches steady state and the steady-state clock error 532 is stored in the state storage 508, the QCL module 530 can disable the update prediction module 502 and the update module 504 of the Kalman filter 500 while enabling the measurement module 506 to directly calculate the RTT output 540 based on subsequent ToA and ToD samples (e.g., t1(n+1), t2(n+1), t3(n+1), t4(n+2), t1(n+2), t2(n+2), t3(n+2), t4(n+2)) and the steady-state clock error 532. The QCL operation can be based on the assumption that the subsequent ToA and ToD samples have the same clock bias and clock drift large-scale properties as the previous ToA and ToD samples. Since the Kalman-filtered RTT and clock error prediction and update operations can be slow and computationally intensive, using the steady-state clock error to directly calculate the RTT allows for an effective reduction of the impact of the clock error on the RTT measurement.

[0100] While the QCL operation can provide an effective way to reduce the impact of the clock error on the RTT measurement, the clock error reduction of the QCL operation can be compromised when the steady-state clock error no longer corresponds to the actual clock error. Figure 6 An example scenario in which the clock error experiences a significant change is shown. As Figure 6 shown, before time T1, the clock of the RSU 402 leads the clock of the vehicle 412 by a clock bias T bias1 , which can be represented in the steady-state clock error after Kalman filtering and used to refine the RTT measurement. Due to a clock reconfiguration event at the RSU 420 at time T1, which can include, for example, a power-up event, a clock synchronization event, or a reconfiguration event of a local oscillator, among others, the phase relationship between the clocks of the RSU 402 and the vehicle 412 changes significantly. After time T1, the clock of the vehicle 412 leads the clock of the RSU 402 by a clock bias T bias2 If the QCL module 530 uses the steady-state clock error representing the clock bias T bias1 after time T1 to refine the RTT measurement, the QCL operation can introduce substantial error to the RTT measurement because the steady-state clock error no longer corresponds to the latest clock bias T bias2 .

[0101] Figure 7 An example of message flow 700 between an RSU (e.g., RSU 402) and a vehicle (e.g., vehicle 412) is shown, which can improve positioning operations by reconfiguring events based on a clock. Message flow 700 is from... Figure 4A It is derived from message stream 420. For example... Figure 7 As shown, in phase 422 of the positioning operation, RSU 402 may send message 702 including clock reconfiguration indication 704. Clock reconfiguration indication 704 may indicate whether a clock reconfiguration event occurred at RSU 402 in phase 424 before sending PRS 432. In some examples, message 702 may be... Figure 4B The message 702 is part of message 424 and includes an identifier 426a (e.g., the source ID of RSU 402) and transmission configuration information 426b (e.g., the spectrum resources used in the transmission of PRS). As described above, the transmission of message 702 and phase 422 can be performed before or after phase 430, in which PRS 432 and 434 are exchanged between RSU 402 and vehicle 412. After phase 430, RSU 402 can send the ToD(t1) of PRS 432 and the ToA(t4) of PRS 434 recorded at RSU 402 to vehicle 412 via ITS message transmission. As described in detail below, vehicle 412 can estimate the RTT between RSU 402 and vehicle 412 based on the ToA and ToD of PRS 432 and 434 and the clock reconfiguration indication 704.

[0102] Figure 8 Support was shown Figure 7 Example message flow 700 RSU 800 example. (e.g.) Figure 8 As shown, in addition to the processor 310, memory 311, transceiver 315, and clock module 360, Figure 8It also includes a detection module 802. The clock reconfiguration event detection module 802 can detect events at the RSU 800 that could cause a clock reconfiguration at the clock module 360, such as a power-on event of the RSU 800, a clock synchronization event of the clock module 360, or a reconfiguration event of the local oscillator of the clock module 360, and stores a clock reconfiguration indication 704. The clock reconfiguration indication 704 can be in the form of a flag bit, which can be deactivated by default and activated when a clock reconfiguration event is detected. The processor 310 can obtain the clock reconfiguration indication 704 from the detection module 802, include the indication in a message 702, and then control the transceiver 315 to send the message to the vehicle 412. After sending message 702, the processor 310 can deactivate the clock reconfiguration indication 704, and subsequently, when another event at the RSU 800 is detected that could cause a clock reconfiguration at the clock module 360, the detection module 802 can activate the clock reconfiguration indication.

[0103] Figure 9 Additional components for vehicle 412 are shown to support positioning operations based on message flow 700. For example... Figure 9 As shown, in addition to the Kalman filter 500 and QCL module 530, vehicle 412 also includes a clock event module 902. Clock event module 902 can extract clock reconfiguration indication 704 from message 702 and determine whether a clock reconfiguration event has occurred before the exchange of PRS between vehicle 412 and RSU 402 in phase 430. If a clock reconfiguration event occurs, clock event module 902 can disable QCL operation and reset the clock error state variable to the default clock error (error(0)), and restart prediction module 502 and update module 504 to re-estimate the clock error between RSU 402 and vehicle 412 based on subsequent samples of ToA and ToD (e.g., t1(n+1), t2(n+1), t3(n+1), t4(n+2), t1(n+2), t2(n+2), t3(n+2), t4(n+2)). Figure 5C As described in [the document]. On the other hand, if no clock reconfiguration event occurs, the clock event module 902 can allow QCL operation to continue, such that an RTT output 540 for subsequent samples of ToA and ToD is generated based on the steady-state clock error 532 stored in the state storage device 508.

[0104] Figure 10 An example method 1000 is shown that can be performed by a first station, which may be a ground station such as RSU 402 and RSU 404 to facilitate positioning operations at a second station, which may be part of a vehicle such as vehicle 412.

[0105] In operation 1002, the first station sends the first message, such as... Figure 7 Message 702, the first message includes an indication of whether a clock reconfiguration event has occurred at the first station. A clock reconfiguration event may include, for example, a power-on event, a clock synchronization event at the first station's local clock source, or a reconfiguration of the oscillator of the local clock source. The first message may include other information, such as an identifier of the first station that allows the second station to determine the location of the first station, the spectrum resources used by the first station to send the PRS to the second station, the scheduling time for the PRS transmission, etc. In some examples, if the PRS is transmitted on licensed spectrum, the first message may be sent before the PRS exchange between the first and second stations. In some examples, if the PRS is transmitted on unlicensed spectrum and the PRS transmission time is unknown, the first message may be sent after the PRS exchange.

[0106] In operation 1004, the first station sends the first PRS to the second station. (Reference) Figure 7 The first PRS can correspond to PRS432. In some examples, the first PRS is sent via the V2X sidelink and the associated sidelink protocol.

[0107] In operation 1006, the first station receives the second PRS from the second station. (Reference) Figure 7 The second PRS can correspond to PRS434. In some examples, the second PRS is sent via the V2X sidelink and the associated sidelink protocol.

[0108] In operation 1008, the first station sends a second message to the second station. This second message includes a first time when the first station sends the first PRS and a second time when the first station receives the second PRS, enabling the second station to determine the RTT between the first and second stations based on the first time, the second time, a third time when the second station receives the first PRS, a fourth time when the second station sends the second PRS, and an indication. The second message may include an ITS message in a V2X implementation.

[0109] Specifically, refer to Figure 7The first time can correspond to the transmission time (t1) of PRS 432 at RSU 402, and the second time can correspond to the reception time (t4) of PRS 434 at RSU 402. Furthermore, the third time can correspond to the transmission time (t3) of PRS 434 at vehicle 412, and the fourth time can correspond to the reception time (t4) of PRS 432 at vehicle 412. The first and second times can be measured using a local clock source of RSU 402 (e.g., clock module 360), while the third and fourth times can be measured using a local clock source of vehicle 412 (e.g., clock module 290). Additionally, clock errors may exist between the two local clock sources, which can include static clock bias / offset between the two local clock sources and dynamic clock drift at the two local clock sources.

[0110] The second station may include a Kalman filter to estimate the clock error and determine the RTT based on the estimated clock error and a first, second, third, and fourth time interval, according to Equation 3. The second station may perform a QCL operation and use the previous clock error estimate to estimate the actual clock error, and use the previous clock error estimate to refine the RTT measurement. However, if an indication from the first message indicates a clock reconfiguration event at the first station, the second station may disable the QCL operation and restart the Kalman filter to generate a current estimate of the clock error between the two stations, and use the current estimate to refine the RTT measurement.

[0111] Figure 11 An example method 1100 that can be performed by a first station (which may be part of a vehicle such as vehicle 412) is shown to estimate the RTT between the first station and a second station, which may be a ground station such as RSU 402 and RSU 404.

[0112] In operation 1102, the first station receives the first message from the second station, such as... Figure 7 Message 702 includes an indication of whether a clock reconfiguration event has occurred at the first station. A clock reconfiguration event may include, for example, a power-on event, a clock synchronization event at the local clock source of the second station, or a reconfiguration of the oscillator of the local clock source. The first message may include other information, such as an identifier of the second station that allows the first station to determine the location of the second station, the spectrum resources used by the second station to send the PRS to the first station, or the scheduling time for the PRS transmission. In some examples, if the PRS is transmitted on licensed spectrum, the first message may be sent before the PRS exchange between the first and second stations. In some examples, if the PRS is transmitted on unlicensed spectrum and the PRS transmission time is unknown, the first message may be sent after the PRS exchange.

[0113] In operation 1104, the first station transmits a first PRS to the second station. With reference to Figure 7 , the first PRS can correspond to PRS 434. In some examples, the first PRS is transmitted via a V2X sidelink and associated sidelink protocol.

[0114] In operation 1106, the first station receives a second PRS from the second station. With reference to Figure 7 , the second PRS can correspond to PRS 434. In some examples, the second PRS is transmitted via a V2X sidelink and associated sidelink protocol.

[0115] In operation 1108, the first station receives a second message from the second station, the second message including a first time at which the second station received the first PRS and a second time at which the second station received the second PRS to enable the second station to determine a RTT between the first station and the second station based on the first time, the second time, a third time at which the second station received the first PRS, a fourth time at which the second station transmitted the second PRS, and an indication. The second message can include an ITS message in a V2X implementation.

[0116] In operation 1110, the first station determines a RTT between the first station and the second station based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and an indication.

[0117] In particular, with reference to Figure 7 , the first time can correspond to a reception of PRS 434 at RSU 402 (t4), while the second time can correspond to a transmission of PRS 432 at RSU 402 (ti). Further, the third time can correspond to a transmission time of PRS 434 at vehicle 412, while the fourth time can correspond to a reception time of PRS 432 at vehicle 412 (t2). The first and second times can be measured using a local clock source of RSU 402 (e.g., clock module 360), while the third and fourth times can be measured using a local clock source of vehicle 412 (e.g., clock module 290). Further, there can be a clock error between the two local clock sources, where the clock error can include a static clock bias / offset between the two local clock sources and a dynamic clock drift at the two local clock sources.

[0118] The second station can include a Kalman filter to estimate the clock error and determine the RTT based on the estimated clock error and the first time, the second time, the third time, and the fourth time based on Equation 3. The second station can perform the QCL operation and use the previous clock error estimate to estimate the actual clock error and use the previous clock error estimate to refine the RTT measurement. However, if the indication from the first message indicates a clock reconfiguration event at the first station, the second station can disable the QCL operation and restart the Kalman filter to generate a current estimate of the clock error between the two stations and use the current estimate to refine the RTT measurement.

[0119] In some examples, the first station can perform the method 1100 for multiple ground stations to obtain different RTT measurements for the multiple ground stations. From the different RTT measurements, the first station can obtain a time offset between the multiple ground stations. Based on the time offset of the multiple ground stations and known locations, the first station can estimate its location based on Equation 1.

[0120] Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software and computers, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0121] As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. As used herein, the terms “comprises”, “comprising”, “includes” and / or “including” specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0122] Also, as used in the description herein and throughout the claims that follow, the meaning of "or" includes any and all combinations of the items that are conjoined by the term. Stated in other terms, the phrase "at least one of A or B" means A or B or both A and B. For example, a processor configured to perform a function with respect to at least one of A or B means the processor can be configured to perform the function with respect to A, or can be configured to perform the function with respect to B, or can be configured to perform the function with respect to both A and B. Similarly, a component to measure at least one of A or B includes a component to measure A (which can or can not be able to measure B), or a component to measure B (which can or can not be able to measure A), or a component to measure both A and B (which can be able to select which or both of A and B to measure).

[0123] Substantial variations can be made in accordance with specific requirements. For example, customized hardware might also be used, and / or particular elements might be implemented in hardware, software (including portable software, such as applets), or both. Further, connection to other computing devices such as network input / output devices can be employed.

[0124] The systems and devices discussed above are examples. Various configurations can omit, substitute, or add various procedures or components as appropriate. For instance, features described with respect to certain configurations can be combined in various other configurations. Different aspects and elements of the configurations can be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims.

[0125] A wireless communication system is a system in which communication is effected with the aid of electromagnetic waves and / or acoustic waves propagating through the atmosphere space, rather than through wires or other physical connections. A wireless communication network can not have all communication sent wirelessly, but is configured to have at least some communication sent wirelessly. Also, the term "wireless communication device" or similar term does not require that the functionality of the device be exclusively or even primarily for communication, or that the device be a mobile device, but rather indicates that the device includes wireless communication capability (one-way or two-way), e.g., including at least one radio (each radio being part of a transmitter, receiver, or transceiver) for wireless communication.

[0126] Specific details are given in the description to provide a thorough understanding of the example configurations (including specific implementations). However, configurations can be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and is not intended to limit the scope, applicability or configurations of the claims. Rather, this description provides a description of the described technologies. Various changes can be made to the function and arrangement of elements without departing from the spirit or scope of the disclosure.

[0127] As used herein, the terms "processor-readable medium," "machine-readable medium," and "computer-readable medium" refer to any medium involved in providing data to a processor for execution and / or to any medium that a processor can read (e.g., as signals). Such media can take many forms, including but not limited to, non-volatile and volatile media, such as optical, magnetic, semiconductor, and electrical media. In many implementations, a computer-readable medium is a physical and / or tangible storage medium. Such media can also take the form of signals, e.g., as electrical signals, optical signals, and / or other signals.

[0128] As used herein, "about" and / or "approximately," when used in reference to a measurable value such as an amount, a temporal duration, and the like, encompasses variations that can exist in the values that are preparatory for testing, e.g., testing a system, device, circuit, method, and other implementations described herein, as would be appreciated by one of ordinary skill in the art. As used herein, "substantially" when used in reference to a measurable value such as an amount, a temporal duration, a physical attribute such as frequency, and the like, also encompasses variations that can exist in the values that are preparatory for testing, e.g., testing a system, device, circuit, method, and other implementations described herein, as would be appreciated by one of ordinary skill in the art.

[0129] A statement that a value exceeds (or is greater than or higher than) a first threshold is equivalent to a statement that the value meets or exceeds a second threshold that is slightly greater than the first threshold, e.g., the second threshold is a value that is higher than the first threshold by the resolution of the computing system. A statement that a value is less than (or within or lower than) a first threshold is equivalent to a statement that the value is less than or equal to a second threshold that is slightly lower than the first threshold, e.g., the second threshold is a value that is lower than the first threshold by the resolution of the computing system.

[0130] Having described several example configurations, various modifications, alternative constructions, and equivalents can be used without departing from the spirit of the disclosure. For example, the above elements can be components of a larger system, wherein other rules can take precedence over or otherwise modify the application of the application. Also, a number of operations can be undertaken before, during, or after the above-described elements are considered. As such, the above description does not limit the scope of the claims.

[0131] Embodiments can include different combinations of features in view of the description. Specific examples are described in the numbered clauses below:

[0132] Clause 1. A method comprising: transmitting, by a first station, a first message comprising an indication of whether a clock reconfiguration event occurred at the first station; transmitting, by the first station, a first positioning reference signal (PRS); receiving, by the first station and from a second station, a second PRS; and transmitting, by the first station to the second station, a second message comprising a first time at which the first PRS was transmitted by the first station and a second time at which the second PRS was received by the first station to enable the second station to determine a round trip time (RTT) between the first station and the second station based on the first time, the second time, a third time at which the first PRS was received by the second station, a fourth time at which the second PRS was transmitted by the second station, and the indication.

[0133] Clause 2. The method of clause 1, wherein the indication indicates whether a clock reconfiguration event occurred at the first station prior to the first station transmitting the first positioning reference.

[0134] Clause 3. The method of clause 2, wherein the clock reconfiguration event is at a local clock source of the first station; and wherein the first time and the second time are obtained based on a clock signal of the local clock source of the first station.

[0135] Clause 4. The method of clause 3, wherein the second station comprises a Kalman filter to estimate a clock error between the first station and the second station and store an estimate of the clock difference; and wherein the indication enables the second station to perform one of the following operations based on the indication: reset a previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock difference, or use the previous estimate of the clock error to estimate the RTT in the QCL operation.

[0136] Clause 5. The method of any of clauses 1-4, wherein the first message includes an identifier of the first station to enable the second station to determine a location of the first station based on the identifier.

[0137] Clause 6. The method of clause 5, further comprising determining a location of the second station based on the location of the first station and the RTT.

[0138] Clause 7. The method of any of clauses 1-6, wherein the first message includes one or more carrier frequencies used in the transmission of the first PRS.

[0139] Clause 8. The method of any of clauses 1-7, wherein the first message includes a scheduled time window of the transmission of the first PRS; and wherein the first message is transmitted prior to the transmission of the first PRS.

[0140] Clause 9. The method of any of clauses 1-8, wherein the first PRS and the second PRS are transmitted via an unlicensed spectrum.

[0141] Clause 10. The method of clause 9, wherein the first message is transmitted after the transmission of the first PRS.

[0142] Clause 11. The method of any of clauses 1-10, wherein the first PRS and the second PRS are transmitted via a vehicle-to-everything (V2X) sidelink and associated sidelink protocol.

[0143] Clause 12. The method of clause 11, wherein the V2X sidelink is within an intelligent transportation system (ITS) spectrum including 5.9 GHz.

[0144] Clause 13. The method of any of clauses 1-12, wherein the first station is part of a road side unit (RSU), and wherein the second station is part of a vehicle.

[0145] Clause 14. A method comprising: receiving, by a first station from a second station, a first message including an indication of whether a clock reconfiguration event occurred at the second station; transmitting, by the first station and to the second station, a first PRS; receiving, by the first station and from the second station, a second PRS; receiving, by the first station from the second station, a second message including a first time at which the second station received the first PRS and a second time at which the second station transmitted the second PRS; and determining, by the first station, an RTT between the first station and the second station based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and the indication.

[0146] Clause 15. The method of clause 14, wherein the indication indicates whether a clock reconfiguration event occurred at the second station prior to the transmission of the second positioning reference at the second station.

[0147] Clause 16. The method of clause 15, wherein the clock reconfiguration event is at a local clock source of the second station; and wherein the first time and the second time are obtained based on a clock signal of the local clock source of the second station.

[0148] Clause 17. The method of clause 16, wherein the first station includes a Kalman filter to estimate a clock error between the first station and the second station and store estimates of the clock difference; and wherein the method further comprises performing one of the following based on the indication: resetting a previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock difference, or using the previous estimate of the clock error to estimate the RTT in the QCL operation.

[0149] Clause 18. The method of any of clauses 14-17, wherein the first message includes an identifier of the second station; wherein the method further comprises determining a location of the second station based on the identifier.

[0150] Clause 19. The method of clause 18, further comprising determining a location of the first station based on the location of the second station and the RTT.

[0151] Clause 20. The method of any of clauses 14-19, wherein the first message includes one or more carrier frequencies used in the transmission of the second PRS.

[0152] Clause 21. The method of any of clauses 14-20, wherein the first message includes a scheduled time window of the transmission of the second PRS; and wherein the first message is transmitted prior to the transmission of the second PRS.

[0153] Clause 22. The method of any of clauses 14-21, wherein the first PRS and the second PRS are transmitted via an unlicensed spectrum.

[0154] Clause 23. The method of clause 22, wherein the first message is received after the second PRS is received.

[0155] Clause 24. The method of any of clauses 14-23, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0156] Clause 25. The method of any of clauses 14-24, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

[0157] Clause 26. An apparatus that is part of a first station and comprises: a memory configured to store a set of instructions; and a processor configured to execute the set of instructions to: transmit a first message, the first message comprising an indication of whether a clock reconfiguration event occurred at the first station; transmit a first PRS; receive a second PRS from a second station; and transmit a second message to the second station, the second message comprising a first time when the first station transmitted the first PRS and a second time when the first station received the second PRS to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time when the second station received the first PRS, a fourth time when the second station transmitted the second PRS, and the indication.

[0158] Clause 27. The apparatus of clause 26, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and an associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0159] Clause 28. The apparatus of clause 26 or 27, wherein the first station is part of a vehicle; and wherein the second station is part of an RSU.

[0160] Clause 29. An apparatus that is part of a first station and comprises: a memory configured to store a set of instructions; and a processor configured to execute the set of instructions to: receive a first message from a second station, the first message comprising an indication of whether a clock reconfiguration event occurred at the second station; transmit a first PRS to the second station; receive a second PRS from the second station; receive a second message from the second station, the second message comprising a first time when the second station received the first PRS and a second time when the second station transmitted the second PRS; and determine an RTT between the first station and the second station based on the first time, the second time, a third time when the first station transmitted the first PRS, a fourth time when the first station received the second PRS, and the indication.

[0161] Clause 30. The apparatus of clause 29, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and an associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0162] Clause 31. The apparatus of clause 28 or 29, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

[0163] Clause 32. An apparatus that is part of a first station and comprises: means for transmitting a first message, the first message comprising an indication of whether a clock reconfiguration event occurred at the first station; means for transmitting a first PRS; means for receiving a second PRS from a second station; and means for transmitting a second message to the second station, the second message comprising a first time when the first station transmitted the first PRS and a second time when the first station received the second PRS to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time when the second station received the first PRS, a fourth time when the second station transmitted the second PRS, and the indication.

[0164] Clause 33. The apparatus of clause 32, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and an associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum comprising 5.9 GHz.

[0165] Clause 34. The apparatus of clause 32 or 33, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

[0166] Clause 35. An apparatus that is part of a first station and comprises: means for receiving a first message from a second station, the first message comprising an indication of whether a clock reconfiguration event occurred at the second station; means for transmitting a first PRS to the second station; means for receiving a second PRS from the second station; means for receiving a second message from the second station, the second message comprising a first time when the second station received the first PRS and a second time when the second station transmitted the second PRS; and means for determining an RTT between the first station and the second station based on the first time, the second time, a third time when the first station transmitted the first PRS, a fourth time when the first station received the second PRS, and the indication.

[0167] Clause 36. The apparatus of clause 35, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and an associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum comprising 5.9 GHz.

[0168] Clause 37. The apparatus of clause 35 or 36, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

[0169] Clause 38. A non-transitory computer-readable medium storing instructions that, when executed by a hardware processor of a first station, cause the hardware processor to: transmit a first message, the first message comprising an indication of whether a clock reconfiguration event occurred at the first station; transmit a first PRS; receive a second PRS from a second station; and transmit a second message to the second station, the second message comprising a first time at which the first station transmitted the first PRS and a second time at which the first station received the second PRS to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time at which the second station received the first PRS, a fourth time at which the second station transmitted the second PRS, and the indication.

[0170] Clause 39. The non-transitory computer-readable medium of clause 38, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0171] Clause 40. The non-transitory computer-readable medium of clause 38 or 39, wherein the first station is part of a vehicle; and wherein the second station is part of an RSU.

[0172] Clause 41. A non-transitory computer-readable medium storing instructions that, when executed by a hardware processor of a first station, cause the hardware processor to: receive a first message from a second station, the first message comprising an indication of whether a clock reconfiguration event occurred at the second station; transmit a first PRS to the second station; receive a second PRS from the second station; receive a second message from the second station, the second message comprising a first time at which the second station received the first PRS and a second time at which the second station transmitted the second PRS; and determine an RTT between the first station and the second station based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and the indication.

[0173] Clause 42. The non-transitory computer-readable medium of clause 41, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

[0174] Clause 43. The non-transitory computer-readable medium of clause 41 or 42, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

Claims

1. A method for positioning, comprising: sending, by a first station, a first message comprising an indication of whether a clock reconfiguration event occurred at the first station, wherein the reconfiguration event was at a local clock source of the first station and changed a property of a local clock of the first station, and wherein the reconfiguration event at the local clock source changed a clock error between the first station and a second station; sending, by the first station, a first positioning reference signal, PRS; receiving, by the first station, a second PRS from the second station; and sending, by the first station, a second message to the second station comprising a first time when the first station sent the first PRS and a second time when the first station received the second PRS to enable the second station to determine a round trip time, RTT, between the first station and the second station based on the first time, the second time, a third time when the second station received the first PRS, a fourth time when the second station sent the second PRS, and the indication, wherein the indication is used by the second station to determine whether to utilize a previous estimate of a clock error associated with the local clock of the first station in conjunction with a quasi co-location, QCL, operation or to disable the QCL operation and generate a new estimate of the clock error.

2. The method of claim 1, wherein the indication indicates whether the clock reconfiguration event occurred at the first station prior to the first station sending the first positioning reference.

3. The method of claim 2, wherein the first time and the second time are obtained based on a clock signal of the local clock source of the first station.

4. The method of claim 3, wherein the second station comprises a Kalman filter to estimate the clock error between the first station and the second station and store a previous estimate of the clock error; and wherein the indication enables the second station to perform one of the following based on the indication: reset the previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock error or use the previous estimate of the clock error to estimate the RTT in a QCL operation.

5. The method of claim 1, wherein the first message comprises an identifier of the first station to enable the second station to determine a location of the first station based on the identifier.

6. The method of claim 5, further comprising determining a location of the second station based on the location of the first station and the RTT.

7. The method of claim 1, wherein the first message comprises one or more carrier frequencies used in transmission of the first PRS.

8. The method of claim 1, wherein the first message comprises a scheduled time window of transmission of the first PRS; and wherein the first message is sent prior to transmission of the first PRS.

9. The method of claim 1, wherein the first PRS and the second PRS are transmitted via an unlicensed spectrum.

10. The method of claim 9, wherein the first message is transmitted after transmission of the first PRS.

11. The method of claim 1, wherein the first PRS and the second PRS are transmitted via a vehicle-to-everything (V2X) sidelink and associated sidelink protocols.

12. The method of claim 11, wherein the V2X sidelink is within an intelligent transportation system (ITS) spectrum including 5.9 GHz.

13. The method of claim 1, wherein the first station is part of a road side unit (RSU), and wherein the second station is part of a vehicle.

14. A method for positioning comprising: receiving, by a first station from a second station, a first message including an indication of whether a clock reconfiguration event occurred at the second station, wherein the reconfiguration event is at a local clock source of the second station and changes a property of a local clock of the second station, and wherein the reconfiguration event at the local clock source changes a clock error between the first station and the second station; transmitting, by the first station to the second station, a first PRS; receiving, by the first station from the second station, a second PRS; receiving, by the first station from the second station, a second message including a first time when the second station received the first PRS and a second time when the second station transmitted the second PRS; and determining, by the first station, an RTT between the first station and the second station based on the first time, the second time, a third time when the first station transmitted the first PRS, a fourth time when the first station received the second PRS, and the indication, wherein the indication is used to determine whether to utilize a previous estimate of a clock error associated with the local clock of the second station in connection with a quasi co-location (QCL) operation or to disable the QCL operation and generate a new estimate of the clock error.

15. The method of claim 14, wherein the indication indicates whether the clock reconfiguration event occurred at the second station prior to the second station transmitting the second positioning reference.

16. The method of claim 15, wherein the first time and the second time are obtained based on a clock signal of the local clock source of the second station.

17. The method of claim 16, wherein the first station includes a Kalman filter to estimate the clock error between the first station and the second station and stores a previous estimate of the clock error; and wherein the method further comprises, based on the indication, performing one of the following: resetting the previous estimate of the clock error stored in the Kalman filter to obtain an updated estimate of the clock error or using the previous estimate of the clock error to estimate the RTT in a QCL operation.

18. The method of claim 14, wherein the first message includes an identifier of the second station; wherein the method further comprises determining a location of the second station based on the identifier.

19. The method of claim 18, further comprising determining a position of the first station based on a position of the second station and the RTT.

20. The method of claim 14, wherein the first message comprises one or more carrier frequencies used in transmission of the second PRS.

21. The method of claim 14, wherein the first message comprises a scheduled time window of transmission of the second PRS; and wherein the first message is transmitted prior to transmission of the second PRS.

22. The method of claim 14, wherein the first PRS and the second PRS are transmitted via unlicensed spectrum.

23. The method of claim 22, wherein the first message is received after reception of the second PRS.

24. The method of claim 14, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within ITS spectrum including 5.9 GHz.

25. The method of claim 14, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

26. An apparatus for positioning, the apparatus being part of a first station and comprising: a memory configured to store a set of instructions; and a processor configured to execute the set of instructions to perform the following: transmit a first message comprising an indication of whether a clock reconfiguration event occurred at the first station, wherein the reconfiguration event is at a local clock source of the first station and changes a property of a local clock of the first station, and wherein the reconfiguration event at the local clock source changes a clock error between the first station and a second station; transmit a first PRS; receive a second PRS from the second station; and transmit a second message to the second station comprising a first time at which the first PRS was transmitted by the first station and a second time at which the second PRS was received by the first station to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time at which the first PRS was received by the second station, a fourth time at which the second PRS was transmitted by the second station, and the indication, wherein the indication is used by the second station to determine whether to utilize a previous estimate of a clock error associated with the local clock of the first station in conjunction with a quasi co-location, QCL, operation or to disable the QCL operation and generate a new estimate of the clock error.

27. The apparatus of claim 26, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within ITS spectrum including 5.9 GHz.

28. The apparatus of claim 26, wherein the first station is part of a vehicle; and wherein the second station is part of an RSU.

29. An apparatus for positioning, the apparatus being part of a first station and comprising: a memory configured to store a set of instructions; and a processor configured to execute the set of instructions to perform the following: receive, from a second station, a first message comprising an indication of whether a clock reconfiguration event occurred at the second station, wherein the reconfiguration event was at a local clock source of the second station and changed a property of a local clock of the second station, and wherein the reconfiguration event at the local clock source changed a clock error between the first station and the second station; transmit, to the second station, a first PRS; receive, from the second station, a second PRS; receive, from the second station, a second message comprising a first time when the first PRS was received by the second station and a second time when the second PRS was transmitted by the second station; and determine an RTT between the first station and the second station based on the first time, the second time, a third time when the first PRS was transmitted by the first station, a fourth time when the second PRS was received by the first station, and the indication, wherein the indication is used to determine whether to utilize a previous estimate of a clock error associated with a local clock of the second station in connection with a Quasi Co-Location, QCL, operation or whether to disable the QCL operation and generate a new estimate of the clock error.

30. The apparatus of claim 29, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum comprising 5.9 GHz.

31. The apparatus of claim 29, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

32. An apparatus for positioning, the apparatus being part of a first station and comprising: means for transmitting a first message comprising an indication of whether a clock reconfiguration event occurred at the first station, wherein the reconfiguration event was at a local clock source of the first station and changed a property of a local clock of the first station, and wherein the reconfiguration event at the local clock source changed a clock error between the first station and a second station; means for transmitting a first PRS; means for receiving, from the second station, a second PRS; and means for transmitting, to the second station, a second message comprising a first time at which the first station transmitted the first PRS and a second time at which the first station received the second PRS, to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time at which the second station received the first PRS, a fourth time at which the second station transmitted the second PRS, and the indication, wherein the indication is used by the second station to determine whether to utilize a previous estimate of a clock error associated with a local clock of the first station in connection with a quasi co-location (QCL) operation, or whether to disable the QCL operation and generate a new estimate of the clock error.

33. The apparatus of claim 32, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

34. The apparatus of claim 32, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

35. An apparatus for positioning, the apparatus being part of a first station and comprising: means for receiving, from a second station, a first message comprising an indication of whether a clock reconfiguration event occurred at the second station, wherein the reconfiguration event is at a local clock source of the second station and changes a property of a local clock of the second station, and wherein the reconfiguration event at the local clock source changes a clock error between the first station and the second station; means for transmitting, to the second station, a first PRS; means for receiving, from the second station, a second PRS; means for receiving, from the second station, a second message comprising a first time at which the second station received the first PRS and a second time at which the second station transmitted the second PRS; and means for determining an RTT between the first station and the second station based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and the indication, wherein the indication is used to determine whether to utilize a previous estimate of a clock error associated with a local clock of the second station in connection with a quasi co-location (QCL) operation, or whether to disable the QCL operation and generate a new estimate of the clock error.

36. The apparatus of claim 35, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum including 5.9 GHz.

37. The apparatus of claim 35, wherein the first station is part of a vehicle, and wherein the second station is part of an RSU.

38. A non-transitory computer-readable medium storing instructions that, when executed by a hardware processor of a first station, cause the hardware processor to perform the following operations: sending a first message comprising an indication of whether a clock reconfiguration event occurred at the first station, wherein the reconfiguration event was at a local clock source of the first station and changed a property of a local clock of the first station, and wherein the reconfiguration event at the local clock source changed a clock error between the first station and a second station; sending a first PRS; receiving a second PRS from the second station; and sending a second message to the second station comprising a first time at which the first station sent the first PRS and a second time at which the first station received the second PRS to enable the second station to determine an RTT between the first station and the second station based on the first time, the second time, a third time at which the second station received the first PRS, a fourth time at which the second station sent the second PRS, and the indication, wherein the indication is used by the second station to determine whether to utilize a previous estimate of a clock error associated with the local clock of the first station in connection with a quasi co-located (QCL) operation or to disable the QCL operation and generate a new estimate of the clock error.

39. The non-transitory computer-readable medium of claim 38, wherein the first PRS and the second PRS are sent via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within an ITS spectrum comprising 5.9 GHz.

40. The non-transitory computer-readable medium of claim 38, wherein the first station is part of a vehicle; and wherein the second station is part of an RSU.

41. A non-transitory computer-readable medium storing instructions that, when executed by a hardware processor of a first station, cause the hardware processor to perform the following operations: receiving a first message from a second station comprising an indication of whether a clock reconfiguration event occurred at the second station, wherein the reconfiguration event was at a local clock source of the second station and changed a property of a local clock of the second station, and wherein the reconfiguration event at the local clock source changed a clock error between the first station and the second station; sending a first PRS to the second station; receiving a second PRS from the second station; receiving a second message from the second station comprising a first time at which the second station received the first PRS and a second time at which the second station sent the second PRS; and determine, based on the first time, the second time, a third time at which the first station transmitted the first PRS, a fourth time at which the first station received the second PRS, and the indication, an RTT between the first station and the second station, wherein the indication is used to determine whether to utilize a previous estimate of a clock error associated with a local clock of the second station in connection with a quasi co-location (QCL) operation or whether to disable the QCL operation and generate a new estimate of the clock error.

42. The non-transitory computer-readable medium of claim 41, wherein the first PRS and the second PRS are transmitted via a V2X sidelink and associated sidelink protocol; and wherein the V2X sidelink is within ITS spectrum including 5.9 GHz.

43. The non-transitory computer-readable medium of claim 41, wherein the first station is part of a vehicle, and wherein the second station is part of a RSU.

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