WO2024072324A1

WO2024072324A1 - Device, positioning system and method of determining a position of the device for vehicular communication

Info

Publication number: WO2024072324A1
Application number: PCT/SG2023/050633
Authority: WO
Inventors: Chengming JIN; Wee Peng Tay; Kai Zhao; Keck Voon LING; Jun Lu
Original assignee: Nanyang Technological University
Priority date: 2022-09-26
Filing date: 2023-09-19
Publication date: 2024-04-04

Abstract

Aspects concern a device for determining its position for vehicular communication, the device comprises a receiver module configured to receive the following as inputs: a first positioning reference data from a first transmitter at a first time; a second positioning reference data from a second transmitter at a second time; a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment; and calculate a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time; an fusion filtering module configured to receive the first reference signal timing difference and the second reference signal timing difference; and determine a current location of the device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

Description

DEVICE, POSITIONING SYSTEM AND METHOD OF DETERMINING A POSITION OF THE DEVICE FOR VEHICULAR COMMUNICATION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The application claims the benefit of priority of Singapore patent application No. 10202251155U, filed 26 September 2022, the content of it being hereby incorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

[0002] The disclosure relates to a device, system and method of determining a position of a device for vehicular communication. In particular, the vehicular communication may include, but is not limited to, communication between two or more vehicles, vehicle to pedestrian, and vehicle to infrastructure. In some embodiments, the vehicular communication may include a vehicle-to-everything protocol.

BACKGROUND

[0003] The following discussion of the background is intended to facilitate an understanding of the present disclosure only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or is part of the common general knowledge of the person skilled in the art in any jurisdiction as of the priority date of the disclosure.

[0004] As part of the expansion of the Long-Term Evolution (LTE) platform to new services, and to keep track with the increasing needs of the automotive industry, 3rd Generation Partnership Project (3GPP) is developing functionality to provide enhancements specifically for vehicular communications. Such vehicular communications may include direct communication between vehicles, vehicle to pedestrian, and vehicle to infrastructure. The vehicular communication may include cellular communications with networks.

[0005] In recent years, Cellular Vehicle-to-Everything (C-V2X) protocol was developed within the 3GPP, as an alternative option to the Dedicated short-range communications (DSRC) and Cooperative Intelligent Transport Systems (C-ITS). The initial C-V2X standard defined in the document Rel-14.C-V2X introduces different communication modes of Vehicle - to-Vehicle (V2V) communication, Vehicle-to-Infrastructure (V2I) communications within the radio spectrum 5.9 GHz frequency band, Vehicle-to-Network (V2N) communication using the licensed mobile spectrum, and Vehicle-to-Barrier (V2B) communication [1].

[0006] Moreover, Hybrid Automatic Repeat Request (HARQ) protocols, which combine Automatic Repeat Request (ARQ) and Forward Error Correction (FEC), are developed to enhance the reliability and increase the throughput performance and energy efficiency of C- V2X communications [2].

[0007] The 3 GPP has enabled positioning in LTE networks as a mandate by the US Federal Communications Commission. Since then, many possible positioning methods have been incorporated. The positioning methods supported by 3GPP fifth generation (5G) network can be mainly divided into angle -based methods, received signal strength (RSS) based positioning, and timing estimation-based trilateration techniques.

[0008] To estimate a position of a device, a timing estimation-based method may be used. Currently, a timing estimation-based method may involve a 5G receiver to track some reference signals, so that time of arrival (ToA) of tracked reference symbols can be obtained. However, in the symbol tracking process, one or more tracking loops will be unlocked or interrupted when experiencing short-term 5G signal outages.

[0009] Besides the above interruption to tracking, other problems such as loop bandwidth, high dynamics and high noise which may cause one or more difficulties in the receiving of signals by 5G receivers. In a high noise environment, the receiver may need to be configured to decrease the bandwidth of the tracking loops so as to mitigate the impact of noise. However, if the receiver is configured to be mobile and in high dynamics, a large loop bandwidth is required. Therefore, in high noise and high dynamic conditions, loss of lock or interruption of tracking loops may again result.

[0010] In view of at least the aforementioned problems, there exists a need to provide a solution to enable or provide a more robust system, device or method for obtaining positional measurements and/or estimate the position of a user equipment so as to mitigate the adverse effects of interruption of tracking loops.

SUMMARY

[0011] A technical solution may be provided in the form of a 5G vehicle-to-everything (5G- V2X) positioning system. The positioning system may include a user equipment, also referred to as a target equipment. The user equipment may comprise a 5G receiver integrated with an inertial measurement unit (IMU) to receive data from transmitters and an intermediate user equipment RSU network and a gNodeB network, in the form of a protocol for the UE to determine its position is defined. It makes full use of RSU network and gNodeB network. Meanwhile, integrating 5G DD measurements with IMU is able to output high-precision, high- availability UE dynamic estimates. Compared with conventional 5G receivers, proposed 5G/IMU integration is able to feedback receiver's dynamic conditions to 5G receiver's code and carrier phase tracking loops, consequently, reducing loop bandwidth and improving code and carrier phase tracking performance.

[0012] In some embodiments, the disclosure includes the use of a feedback mechanism wherein the receiver's dynamic information due to its relative movement with respect to the transmitter may be implemented as a feature to facilitate an ultra-tight coupling framework, achieving ultra-tight integration to solve the problem of loss of lock of tracking loops. In the tracking loop, the loop filter may be regarded as a compromise between loop bandwidth and noise suppression, providing such dynamic information will allow reducing the loop bandwidth, so that noise performance can be improved at the receiver.

[0013] According to an aspect of the disclosure there is provided a device for determining its position for vehicular communication, the device comprises a receiver module configured to receive the following as inputs: a first positioning reference data from a first transmitter at a first time; a second positioning reference data from a second transmitter at a second time; a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment; and calculate a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time; and a fusion filter module configured to receive the first reference signal timing difference and the second reference signal timing difference; and determine a current location of the device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

[0014] In some embodiments, the device comprises an inertial measurement unit (IMU) arranged in data communication with the fusion filter module, the IMU configured to receive at least one parameter associated with the current location of the device and determine an acceleration data and angular rate as output. [0015] In some embodiments, the first reference signal timing comprises a first carrier phase measurement and a first code phase measurement, and the second reference signal timing difference comprises a second carrier phase measurement and a second code phase measurement.

[0016] In some embodiments, the further comprises an inertial navigation system (INS), the INS configured to receive the acceleration data and the angular rate as input and determine a current position, a current velocity, and a current attitude of the device as output.

[0017] In some embodiments, the INS is configured to determine the current position, the current velocity, and the current attitude of the device based on a dead reckoning process.

[0018] In some embodiments, the fusion filter module is an extended Kalman filter module, wherein the extended Kalman filter module is configured to receive the current position, the current velocity, and the current attitude of the device as input to determine an estimate position, an estimate velocity, and an estimate attitude as outputs.

[0019] In some embodiments, at least one of the first transmitter and the second transmitter is an 5G-NR base station. The 5G-NR base station may be is a gNodeB base station.

[0020] In some embodiments, the intermediate user equipment comprises a roadside unit (RSU).

[0021] In some embodiments, the IMU comprises an accelerometer and a gyroscope, and the at least one parameter associated with the current location of the device comprises at least one of an accelerometer bias and a gyroscope bias.

[0022] In some embodiments, the receiver module is a 5G software defined radio (SDR) receiver.

[0023] According to another aspect of the disclosure there is provided a system for determining a position of a target device for vehicular communication, the system comprising a first transmitter configured to send a first positioning reference data to the target device, the target device configured to receive the first positioning reference data at a first time; a second transmitter configured to send a second positioning reference data to the target device, the target device configured to receive the second positioning reference data at a second time; at least one intermediate user equipment configured to send a positioning assistance data associated with the first positioning reference data and the second positioning reference data to the target device; wherein the target device is any of the device as described. [0024] In some embodiments, the system is a 5G-vehicle to everything (V2X) positioning system.

[0025] In some embodiments, at least one of the first transmitter and the second transmitter is a 5G-NR base station. The 5G-NR base station may be a gNodeB base station.

[0026] In some embodiments, the intermediate user equipment comprises a roadside unit (RSU).

[0027] According to another aspect of the disclosure, there is a method for determining a position of a target device for vehicular communication, the method comprises obtaining, at the target device, a first positioning reference data from a first transmitter at a first time; obtaining, at the target device, a second positioning reference data from a second transmitter at a second time; obtaining, at the target device, a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment; calculating, by a processor of the target device, a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time; determining, by the processor of the target device, a current location of the target device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

[0028] In some embodiments, the determining of the current location further comprises a step of receiving at least one parameter associated with the current location of the device and determine an acceleration data and angular rate as output.

[0029] In some embodiments, the first reference signal timing difference comprises a first carrier phase measurement and a first code phase measurement, and the second reference signal timing difference comprises a second carrier phase measurement and a second code phase measurement.

[0030] According to another aspect of the disclosure there is provided a computer-readable medium comprising program instructions, which, when executed by one or more processors, cause the one or more processors to perform any of the method as described.

BRIEF DESCRIPTION OF THE DRAWINGS [0031] The disclosure will be better understood with reference to the detailed description when considered in conjunction with the non-limiting examples and the accompanying drawings, in which:

- FIG. 1 shows a schematic block diagram of a device for determining its position for vehicular communication;

- FIG. 2A shows a system architecture diagram of a system for determining a position of a target device for vehicular communication, in the form of a 5G-V2X network; FIG. 2B illustrates a specific flowchart of a method for determining the position of a target device based on the system illustrated in FIG. 2A;

- FIG. 3 shows a schematic diagram of a setup for obtaining 5G positioning signals or data and/or deriving carrier phase and code phase measurements;

- FIG. 4A shows an experimental setup of a device (UE) and system for determining the position of the UE; FIG. 4B and FIG. 4C show graph plots based on positioning measurements obtained; and

- FIG. 5 illustrates a general flowchart of a method for determining a position of a target device for vehicular communication.

DETAILED DESCRIPTION

[0032] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure. Other embodiments may be utilized and structural, logical changes may be made without departing from the scope of the disclosure. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0033] Embodiments described in the context of one of the systems or methods are analogously valid for the other systems or methods.

[0034] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0035] In the context of some embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0036] As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0037] As used herein, the term “processor(s)” includes one or more electrical circuits capable of processing data, i.e. processing circuits. A processor may include analog circuits or components, digital circuits or components, or hybrid circuits or components. Any other kind of implementation of the respective functions which will be described in more detail below may also be understood as a "circuit" in accordance with an alternative embodiment. A digital circuit may be understood as any kind of a logic implementing entity, which may be special purpose circuitry or a processor executing software stored in a memory, or a firmware.

[0038] As used herein, the term “vehicular communication” include communication between a vehicle and at least one of the following: one or more other vehicles (V2V), one or more base stations, one or more infrastructure (V2I), one or more roadside units, one or more buildings. It is contemplated that the term may further include cellular Vehicle-to-Everything (C-V2X) communication protocol. The communication between the vehicle and the various variations may include safety and traffic information.

[0039] As used herein, the term “roadside unit”, abbreviated as RSU, refers to a communicating device equipped with wireless data transceiving capabilities, located proximity to a roadside so as to provide connectivity and information support to one or more vehicles, including safety warnings and traffic information. In the context of the present disclosure, an RSU may be configured to communicate with one or more other RSUs to form an RSU network. An RSU may be regarded as an intermediate user equipment in the context of the present disclosure, the intermediate user equipment used to facilitate the accurate determination (via estimation or otherwise) of the position of a target device.

[0040] As used herein, the term “user equipment”, abbreviated as UE, broadly refers to a radio frequency receiver. The UE may include a memory, at least one receiver, which may in some embodiments form part of a transceiver, at least one processor communicatively coupled the memory and the at least one transceiver and configured to receive positioning reference data, such as 5G signals. [0041] As used herein, the term “data” may be understood to include information in any suitable analog or digital form, for example, provided as a file, a portion of a file, a set of files, a signal or stream, a portion of a signal or stream, a set of signals or streams, and the like. The term data, however, is not limited to the aforementioned examples and may take some forms and represent any information as understood in the art.

[0042] As used herein, the term “obtain” refers to the processor which actively obtains the inputs, or passively receives inputs from one or more sensors or data source. The term obtain may also refer to a processor, which receives or obtains inputs from a communication interface, e.g. a user interface. The processor may also receive or obtain the inputs via a memory, a register, and/or an analog-to-digital port.

[0043] As used herein, the term “module” refers to, or forms part of, or include an Application Specific Integrated Circuit (ASIC); an electric al/electronic circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip. The term module may include memory (shared, dedicated, or group) that stores code executed by the processor.

[0044] In the following, embodiments will be described in detail.

[0045] According to an aspect of the disclosure, there is a device 100 for determining its position for vehicular communication. Referring to FIG. 1, the device 100 may be an integrated user equipment comprising a receiver module 102, an inertial measurement unit (IMU) 104, an inertial navigation system (INS) 106, and a fusion filtering module integrated as a single unit. [0046] The receiver module 102 may be an M-channel 5G receiver. In some embodiments, the M-channel device may be a 2-channel device configured to receive the following as inputs: a first positioning reference data from a first transmitter at a first time; a second positioning reference data from a second transmitter at a second time; a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment. The receiver module 102 may then be configured to calculate a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time. [0047] In some embodiments, the M-channel device may be configured to receive data from more transmitters, for example, a 4-channel device may be configured to receive data from 4 transmitters, 8-channel device may be configured to receive data from 8 transmitters, and so on.

[0048] In some embodiments, the receiver module 102 may be a 5G receiver module. The 5G receiver module 102 may be a software defined radio (SDR) 5G receiver module.

[0049] In some embodiments, for each channel of the M-channel 5G receiver module, there may comprise one or more circuitries implementing a phase-locked loop (PLL) and a delay- locked loop (DLL). Each of the PLL and the DLL may comprise a low pass filter (LPF), a summing point and an accumulator. In the context of a total of M channels, the M-channel 5G receiver is capable of receiving and processing signals from a maximum of M number of transmitters simultaneously. In some embodiments, the LPF, the summing point and the accumulator may be integrated as one single unit.

[0050] In some embodiments, the M number of transmitters, which include the first transmitter and the second transmitter, may be 5G base stations, for example 5G-NR base stations, or functional equivalents. In some embodiments, the transmitters may be gNodeB units. The gNodeB units may be implemented as a physical entity, such as a transmitter tower, or as a virtual entity.

[0051] In some embodiments, the fusion filtering module may include a Bayes filtering algorithm, for example, a Kalman filtering (KF) algorithm. In some embodiments, the fusion filtering algorithm may include an extended Kalman Filter (EKF) filtering algorithm. It is appreciable that the EKF is an extension of the KF algorithm for non-linear systems where non-linearity are approximated using the first or second order derivative. It is appreciable that other filters, such as particle filter, or any filter that makes use of user information, may be contemplated.

[0052] In the embodiment shown in FIG. 1, the fusion filtering module is an extended Kalman filter (EKF) module 108.

[0053] In some embodiments, the inertial measurement unit (IMU) 104, the inertial navigation system (INS) 106, and/or the fusion filtering module may be combined to form a data processing module. In some embodiments, the data processing module may form part of one or more processors. [0054] The extended Kalman filter (EKF) module 108 may be configured to receive the first reference signal timing difference (RSTD) and the second reference signal timing difference; and determine a current location of the device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data. In some embodiments, the EKF module 108 may be one or more processors configured to receive positioning data from the 5G receiver and/or other positioning assistance data from one or more intermediate user equipment. The EKF module 108 may be configured to update the current position of the device 100 at every pre-determined interval or iteration. In some embodiments, the positioning assistance data may be 5G data packets or signals emitted from the one or more intermediate user equipment, the 5G data packets or signals emitted continuously or at every pre-determined interval. The 5G data packet may include information associated with the first positioning reference data and the second positioning reference data. In some embodiments, the information may include the time of arrival of the first positioning reference data and the second positioning reference data received from the first transmitter and second transmitter respectively.

[0055] The IMU 104 may be arranged in data communication with the EKF module 108, the IMU 104 configured to receive at least one parameter associated with the current location/position of the device 100 and determine an acceleration data and angular rate as output. In some embodiments, the IMU 104 and/or the device 100 may comprise one or more sensors such as an accelerometer and a gyroscope. Such sensors may be used to assist in determining the position of the device 100. The one or more sensors may include at least one hardware sensor, at least one software sensor, or a combination of the at least one hardware and software sensors. In some embodiments, the at least one parameter associated with the current location of the device comprises at least one of an accelerometer bias and a gyroscope bias.

[0056] The INS 106 may be configured to receive the acceleration data and the angular rate from the IMU 104 as input and determine a current position, a current velocity, and a current attitude of the device as output.

[0057] In some embodiments, the INS 106 may be configured to determine the current position, the current velocity, and the current attitude of the device based on a dead reckoning process. In some embodiments, the dead reckoning process for position determination may include a process of calculating a current position of a moving object (i.e. the device 100) by using a previously determined position, and incorporating estimates of speed, velocity, heading (or direction or course), and elapsed time.

[0058] In some embodiments, the EKF module 108 is configured to receive the current position, the current velocity, and the current attitude of the device 100 from the INS 106 as input to determine an estimate position, an estimate velocity, and an estimate attitude as outputs. [0059] In some embodiments, the intermediate user equipment comprises a roadside unit (RSU). The RSU may be configured to communicate with the device 100, which may be installed or within a vehicle when the device 100 is in range. The RSU may include other device(s) in a known location. The device 100 may be configured to observe the reference signal timing difference (RSTD) of the positioning reference signals (PRSs) transmitted by the transmitters, and determine synchronization timing errors between the transmitters. The RSU may send or transmit location information to the device 100 via a sidelink channel and interface (e.g., such as via PC5, or other device-to-device (D2D) technology). In other words, the RSU, and one or more additional intermediate user equipment, may provide positioning assistance data associated with one or more transmitters.

[0060] In some embodiments, one or more RSUs may form an RSU network.

[0061] Referring back to FIG. 1, various connections between the various modules are numbered as ports 1 to 11. The connections may be data connections. The data connection and data between different elements/features may be summarized as follows:

[0062] Port 1 denotes data flow from the IMU module 104 to INS module 106. In some embodiments, acceleration information a^b and angular rate w^b may be the data output from the IMU module 104 to the INS module 106. The acceleration information a^b and angular rate w^b may be obtained from various sensors of the device 100, or the sensors may be integrated within the IMU module 104 itself.

[0063] Port 2 denotes data flow from the INS module 106 to a summation module 110. The INS module 106 outputs the IMU module 106 position p, velocity v and attitude information ψ based on the dead reckoning process as described. Port 4 is the data flow from the INS module 106 to the EKF module 108 based on the same output of the IMU module position p, velocity v and attitude information ψ . In some embodiments, the position p, the velocity v and the attitude information ψ may be used to determine a state of the device 100, for example, using a discrete-time model. [0064] Port 3 denotes data flow from the EKF module 108 to the IMU module 104, in the form of a feedback data. In some embodiments, the feedback data may be obtained from one or more sensors of the IMU module 104, such as accelerometers and gyroscopes, to determine accelerometers biases b_a and gyroscope's bias b_g.

[0065] Port 5 denotes data flow from the EKF module 108 to the summation module 110. The EKF module 108 outputs estimated position, velocity, and attitude updates.

[0066] Port 6 denotes data output from the summation module 110. The output may comprise updated UE position, for example, in the form of positional coordinates, velocity, and attitude information of the device 100. In some embodiments, the summation module 110 may be an integrated circuit chip. In some embodiments, the summation module 110 may be configured to receive the output from port 2, and the output from port 5, as inputs, and then calculate or derive a difference between the output from port 2 and port 5. In summary, the summation 110 may be configured to receive a calculated position, velocity and attitude information of the device 100 from port 2, with adjustments from port 5 as feedback to finetune the calculated position, velocity and attitude information of the device 100.

[0067] Port 7 denotes data flow from the EKF module 108 to the receiver module 102 to the PLL in each channel, and feeds back EKF updated velocity information.

[0068] Port 8 denotes data flow from the 5G receiver 102 PLL in each channel to the EKF module 108, it output 5G double-difference (DD) carrier phase measurements, in the form of a reference signal timing difference (RSTD). For example, the RSTD for the carrier phase measurement (ca) obtained with respect to the ith transmitter, at the device 100, considering the signal received by the user device and the bth intermediate user equipment at the first channel of the device 100 may be denoted as

[0069] Port 9 denotes data flow from the 5G receiver 102 DLL in each channel of the M- channel, to the EKF module 108. The port is configured to output 5G DD code phase measurements, in the form of another RSTD. For example, the RSTD for the code phase measurement (co) obtained with respect to the ith transmitter, at the device 100, considering the signal received by the user device and the bth intermediate user equipment at the first channel of the device 100 may be denoted as

[0070] Port 10 denotes data flow from the EKF module 108 to the 5G receiver 102 DLL in each channel of the M-channel EKF module 108. The updated velocity information by the EKF module 108 may be updated or revised at every pre-determined interval. [0071] Port 11 denotes data flow from an RSU network to the device 100, which may be an onboard user equipment (UE). The data may comprise a time of arrival (ToA) parameter or value, within possible measuring accuracy information of signal transmitted by the ith gNodeB out of a total of I gNodeB units, where I is an integer greater or equal to 1, i.e. I ≥ 2.

[0072] It may be appreciable in the design that the DLL and PLL loops in each channel of the M-channel device 100 may configure a small loop bandwidth, since the device 100 dynamics, i.e. velocity, is compensated by the feedback from port 7 and port 10.

[0073] In some embodiments, the first positioning reference data may be used to determine a first reference signal timing difference, the first reference signal timing difference comprising the first carrier phase measurement and the first code-based measurement

Likewise, the second positioning reference data may be used to determine a second

reference signal timing difference, the second reference signal timing difference comprising the second carrier phase measurement and the second code -based measurement

[0074] FIG. 2A shows a system architecture of a system 200 for determining a position of a target device for vehicular communication. The target device may be the device 100. In some embodiments, the device 100 may be a smartphone device held by a user of a vehicle, the smartphone device equipped with sensors, and communication circuits to implement the 5G receiver 102, IMU 104, INS 106, and EKF module 108. In other embodiments, the device 100 may be a dedicated device optimized for the purpose for determining a position of the vehicle, such dedicated device may be installed and/or mounted on the vehicle.

[0075] The system 200 shown in FIG. 2 may be a 5G-V2X network implemented within a certain area. The 5G-V2X network may comprise a gNodeB network 202, an RSU network 204 and the target device 100, which may be also referred to as a user equipment (UE). In FIG. 2A, the gNodeB network comprises gNodeBi, gNodeB2, . . ., gNodeBi, gNodeBi.

[0076] Without the loss of generality, suppose there are I gNodeB s and J RSUs in the system 200. It is appreciable the parameters I and J are positive integers I ≥ 2, J ≥ 1.

[0077] On the network level, a UE 100 positioning process 250 may be divided into the following steps: [0078] In step 251: Nearby / gNodeBs periodically transmit 5G positioning reference signal (PRS) to the UE 100. The period may be pre-determined or may be defined based on infrastructure requirements/parameters .

[0079] In step 252: During each positioning iteration, the UE 100 will monitor each of the gNodeBs and receive all possible signals available. As an example, the UE 100 may be configured to demodulate the 5G PRS from a gNodeB set, the gNodeB set mathematically expressed as {X0|X0 G gNodeB,, 1 ≤ z ≤ I}.

[0080] In step 253: During each positioning iteration, the nearby J RSUs will monitor these gNodeBs and receive the available 5G signals. For instance, in each RSU/ where 1 ≤ j < J, the UE 100 may be configured to demodulate the 5G PRS from a gNodeB set { X_j |X_j G gNodeB, , 1 ≤ i ≤ I}. Therefore, for a certain jth RSU, i.e. RSU/, the RSU will obtain a ToA set {TOA/, i |1 ≤ i ≤ I}.

[0081] In step 254: During each positioning iteration, the RSU/ will broadcast TOA_j,i measurements for each of the ith gNodeB to the UE 100, with possible measuring accuracy to the UE 100 via vehicle to infrastructure (V2I) or vehicle to node (V2N) communications. The UE 100 will then locate, find or determine a subset of gNodeBs, the subset of gNodeBs which may be demodulated by the UE 100 and comprise at least one RSU. The communications between the UE 100 and the RSU network may make use of or be based on a Hybrid Automatic Repeat Request (HARQ) scheme to enhance the reliability and increase the throughput performance and energy efficiency of the 5G-V2X communications.

[0082] In step 255: At a final step of each positioning iteration, the UE 100 can obtain 5G DD code and carrier phase measurements which will be described with reference to FIG. 3. Subsequently, a 5G/IMU integrated positioning may be applied to estimate UE's position, velocity and attitude.

[0083] FIG. 3 illustrates an embodiment of obtaining double-difference (DD) code and carrier phase measurements, specifically 5G DD code and carrier phase measurements by using additional measurements from the RSU/, which may function as an intermediate user equipment.

[0084] As shown in FIG. 3, there is one gNodeB pair including gNodeB; and gNodeB,, besides the UE 100, there is an intermediate UE, in the form of an RSU, configured to receive and measure the ToA of the 5G signals transmitted from gNodeB; and gNodeB,. Mathematically, the distance between the receiver and transmitter can be expressed in equations (1) to (4) as follows:

where ToAui denotes the ToA of signal transmitted by gNodeBi and measured at the UE 100, ToAbi is the ToA of signal transmitted by gNodeBi and measured by the RSU, δT_ui represents UE's clock offset with respect to (w.r.t.) gNodeBi, δTbi denotes the RSU's clock offset w.r.t. gNodeBi, r_ui and rbi denote the distance between gNodeBi and UE 100 and the RSU 204, respectively. It is worth noting that the units of the time measurements and clock offset in equations (1) to (4) are converted into meters (m). ToDi and ToDi denote the times of departure associated with the time(s) the 5G signals are sent out from the gNodeBi and gNodeBi respectively.

Based on (3) and (4), the clock offset estimate from the RSU may be expressed mathematically as Equation (5)

Equation (5) may be rewritten as Equation (6), as follows:

where denotes the Reference Signal Time Difference (RSTD) measurement between

gNodeBi and gNodeBi as measured at the RSU end.

Based on (1) and (2), the RSTD measurement between gNodeBi and 1 at the UE end, RSTD^, is expressed as Equation (7) as follows:

Based on Equations (6) and (7), the 5G DD measurement of gNodeBi and gNodeBi,

is expressed as Equation (8) as follows:

[0085] In one embodiment, suppose there are (I - 1) gNodeB units and one reference gNodeBi unit, and {i ∈ Z|2 ≤ i ≤ I}, then (I -1) 5G code phase based DD measurements may be obtained, i.e [k] 12 ≤ i ≤ 1} and (I -1) 5G carrier phase based DD measurements

[k] | 2 ≤ i ≤ 1} during the k-th measurement update cycle. An assumption is that

each gNodeB coordinates are known to the UE 100.

[0086] Referring back to FIG. 1, the proposed extended Kalman filter (EKF) architecture comprises the UE 100 and an RSU network, the RSU network comprises a plurality of RSUs. The latter is responsible for sharing with the port 11. The determination of the current

location of the UE 100 may be determined as follows.

[0087] Suppose the rotation rate of the earth is negligible, the UE 100 is moving in a horizontal plane, its height does not change over time and z-axis of the body frame of the UE 100 is constantly perpendicular to the horizontal plane. Therefore, the UE 100 states, x n, expressed in the Local Navigation Frame are defined as [3]

where y is the heading, v represents the 2-dimensional (2-D) velocity, and p represents the 2- D position of the device. b_a denotes the biases of IMU accelerometers in x- and y-axes. b_g is the gyroscope's bias in z-axes.

Based on (9), at the k-th processing time step, the UE state's discrete-time model can be expressed as

where At is the update time of IMU, a^b denotes IMU accelerations in x- and y-axes of body frame, and is the corresponding coordinate transformation matrix, it is used to transform a vector from body frame to local navigation frame. n_x denotes random noise of system state x. [0088] Once the UE 100 receives the RSTD measurements from gNodeBi, gNodeBi and corresponding measurements from the RSU, the 5G DD measurements, i.e.

≤ i ≤ 1} and can be obtained. Therefore, the measurement models are

given by

where 0,- denotes the heading in the UE 100 and gNodeBi direction, n_co,i and n_ca,i are code phase and carrier phase measurement noise, respectively.

In summary, the discrete-time dynamic model of the UE 100 is given by (10) to (14), and corresponding measurement model is given by (15) and (16). Therefore, an EKF can be applied to estimate system state x n. One distinguishing feature of proposed integration architecture is that no clock related state is needed in (9), because 5G DD measurements described with reference to Equations (1) to (8) do not contain clock offset errors.

[0089] In some embodiments, where each of the gNodeB position is known to the UE 100, the observation equations may be mathematically expressed in Equation (17) as follows:

where x is the unknown UE coordinates. Newton’s method can be applied to resolve nonlinear equations (17). At the (k - 1 )-th iteration cycle, the linearized equations may be mathematically expressed in Equation (18) as follows:

where b is mathematically expressed in Equation (20), wherein

are the unit vector of gNodeBi w.r.t. the UE 100 in x, y and z directions, respectively.

Then, the least squares estimates (LSE) may be expressed mathematically in Equations (21) and (22) as follows:

[0090] FIGS. 4A to 4C show an experimental setup of a device (UE) and system for determining the position of the UE, as well as results, in the form of graph plots based on positioning measurements obtained. The experimental setup is based on an experiment in which 5G DD carrier phase measurements' accuracy is investigated. Emulated 5G signals comprising 5G Synchronization Signal Block (SSB) and PRS are adopted.

[0091] FIG. 4 A shows a particular experimental setup comprising four gNodeBs 202 numbered gl, g2, g3, and g4, one RSU 204 and one UE 100. The 5G signals are generated, transmitted, and received from equipment simulating the gNodeBs, such as, but not limited to, National Instruments™ (NI) Universal Software Radio Peripheral (USRP) 2954R with a GPS- disciplined oscillator (GPSDO). The received data samples may then be post-processed using the 5G code and carrier phase SDR that was coded using a simulation software, such as MATLAB™. During the experiments, the UE 100 may be configured or controlled to move along a relatively straight line (see direction marked A) and eventually stops at a certain point, i.e. covering a predetermined distance.

[0092] Based on an assumption that the UE 100 starting point, and the RSU 204 and gNodeBs 202 coordinates are known, the estimated UE trajectories in the 2-D plane using gNodeB 1 ~ 3 and gNodeB 1 ~ 4 (referenced as gl, g2, g3, g4) are shown in FIG. 4B, with the positioning errors shown in FIG. 4C. The update rate of the position estimate may be set higher than 100 Hz due to more allocated 5G PRSs across the signal frames compared with other reference signals.

[0093] These experimental results indicate that the accuracy of the 5G DD measurements is at the sub-meter level, and its update rate can be higher than 100 Hz. In addition, from FIG. 4C, it may be appreciable and noted that there is no obvious clock error term inside the 5G DD measurements. [0094] It is contemplated that the device 100 or UE described in the disclosure is considered as a 5G receiver, and the 5G RSU network can be comprised of one or more RSUs or additional 5G gNodeBs.

[0095] In some embodiments, the UE 100 and RSU network may receive transmitted 5G signal from transmitters, e.g. gNodeBs, and the proposed 5G/IMU integration architecture may be an SDR solution, it can be applied to any 5G receiver, which can receive signals from multiple transmitters. The proposed 5G DD measurements may be capable of providing submeter level positioning accuracy. Therefore, the proposed integration solution can be used in many scenarios, some potential application scenarios of this design include user localization service, positioning in the smart factory in a 5G network.

[0096] According to another aspect of the disclosure, there is a method 500 for determining a position of a device for vehicular communication. The device may be the device 100 as described. The method may be implemented for the device 100 in the system 200 as described. [0097] The method 500 may comprise the following steps

[0098] Step 502: obtaining, at the target device, a first positioning reference data from a first transmitter at a first time;

[0099] Step 504: obtaining, at the target device, a second positioning reference data from a second transmitter at a second time;

[00100] Step 506: obtaining, at the target device, a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment;

[00101] Step 508: calculating, by a processor of the target device, a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time;

[00102] Step 510: determining, by the processor of the target device, a current location of the target device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

[00103] In some embodiments, the method 500 may be implemented in a computer-readable medium comprising program instructions, which, when executed by one or more processors, cause the one or more processors to perform the method 500.

[00104] While the disclosure has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims. The scope of the disclosure is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

REFERENCES

[1] S. A. Abdel Hakeem, A. A. Hady, and H. Kim, “5G-V2X: Standardization, architecture, use cases, network- slicing, and edge-computing,” Wireless Networks, vol. 26, no. 8, pp. 6015- 6041, 2020.

[2] P. Szilagyi, B. Heder, and C. Vulkan, “Improved reliability of C-V2X communication based on LTE SC-PTM,” in 2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC). IEEE, 2018, pp. 1-7.

[3] P. Groves, Principles of GNSS, Inertial, and Multisensor Integrated Navigation Systems, 2008.

[4] C. Jin, I. BAJAJ, K. Zhao, W. P. Tay, and K. V. Ling, “Methods And Communication Apparatuses For 5G-Based Positioning,” World Intellectual Property Organization, International Publication Number: WO 2022/115041 Al, Jun 2022

Claims

1. A device for determining its position for vehicular communication, the device comprises a receiver module configured to receive the following as inputs: a first positioning reference data from a first transmitter at a first time; a second positioning reference data from a second transmitter at a second time; a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment; and calculate a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time; and a fusion filter module configured to receive the first reference signal timing difference and the second reference signal timing difference; and determine a current location of the device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

2. The device of claim 1, further comprising an inertial measurement unit (IMU) arranged in data communication with the fusion filter module, the IMU configured to receive at least one parameter associated with the current location of the device and determine an acceleration data and angular rate as output.

3. The device of claim 1 or 2, wherein the first reference signal timing comprises a first carrier phase measurement and a first code phase measurement, and the second reference signal timing difference comprises a second carrier phase measurement and a second code phase measurement.

4. The device of any one of the preceding claims, further comprising an inertial navigation system (INS), the INS configured to receive the acceleration data and the angular rate as input and determine a current position, a current velocity, and a current attitude of the device as output.

5. The device of claim 4, wherein the INS is configured to determine the current position, the current velocity, and the current attitude of the device based on a dead reckoning process.

6. The device of claim 5, wherein the fusion filter module is an extended Kalman filter module, wherein the extended Kalman filter module is configured to receive the current position, the current velocity, and the current attitude of the device as input to determine an estimate position, an estimate velocity, and an estimate attitude as outputs.

7. The device of any one of the preceding claims, wherein at least one of the first transmitter and the second transmitter is an 5G-NR base station.

8. The device of claim 7, wherein the 5G-NR base station is a gNodeB base station.

9. The device of any one of the preceding claims, wherein the intermediate user equipment comprises a roadside unit (RSU).

10. The device of claim 2, wherein the IMU comprises an accelerometer and a gyroscope, and the at least one parameter associated with the current location of the device comprises at least one of an accelerometer bias and a gyroscope bias.

11. The device of any one of the preceding claims, wherein the receiver module is a 5G software defined radio (SDR) receiver.

12. A system for determining a position of a target device for vehicular communication, the system comprising a first transmitter configured to send a first positioning reference data to the target device, the target device configured to receive the first positioning reference data at a first time; a second transmitter configured to send a second positioning reference data to the target device, the target device configured to receive the second positioning reference data at a second time; at least one intermediate user equipment configured to send a positioning assistance data associated with the first positioning reference data and the second positioning reference data to the target device; wherein the target device is a device of any one of claims 1 to 11.

13. The system of claim 12, wherein the system is a 5G-vehicle to everything (V2X) positioning system.

14. The system of claim 13, wherein at least one of the first transmitter and the second transmitter is a 5G-NR base station.

15. The system of claim 14, wherein the 5G-NR base station is a gNodeB base station.

16. The system of any one of claims 12 to 15, wherein the intermediate user equipment comprises a roadside unit (RSU).

17. A method for determining a position of a target device for vehicular communication, the method comprises obtaining, at the target device, a first positioning reference data from a first transmitter at a first time; obtaining, at the target device, a second positioning reference data from a second transmitter at a second time; obtaining, at the target device, a positioning assistance data associated with the first positioning reference data and the second positioning reference data, the positioning assistance data obtained from at least one intermediate user equipment; calculating, by a processor of the target device, a first reference signal timing difference and a second reference signal timing difference based on the first time and the second time; determining, by the processor of the target device, a current location of the target device based on the first reference signal timing difference, the second reference signal timing difference, and the positioning assistance data.

18. The method of claim 17, wherein the determining of the current location further comprising a step of receiving at least one parameter associated with the current location of the device and determine an acceleration data and angular rate as output.

19. The method of claim 17 or claim 18, wherein the first reference signal timing difference comprises a first carrier phase measurement and a first code phase measurement, and the second reference signal timing difference comprises a second carrier phase measurement and a second code phase measurement.

20. A computer-readable medium comprising program instructions, which, when executed by one or more processors, cause the one or more processors to perform the method of any one of claims 17 to 19.