A differential positioning system based on PC5 interface

Abstract

The present invention relates to a differential positioning system based on a PC5 interface, including a calibration server, a Beidou reference station, an RSU, and an OBU. The Beidou reference station and the calibration server are connected through a wired or wireless network to establish an NTRIP service. The RTCM differential information observed by the Beidou reference station is transmitted to the calibration server through a designated port. A TCP / IP connection is established between the calibration server and the RSU, and a corresponding relationship between the position information list of the RSU and the position information list of the Beidou reference station and the network coverage is established, and the Beidou reference station RTCM differential information is sent to the corresponding RSU. The system can realize efficient communication of RTCM differential information between the RSU and the mobile user end OBU, provide high-precision positioning coverage under the C‑V2X network, ensure the normal operation of the RTK / RTD module, protect the user's location privacy, save power consumption, have stable performance, and are extremely practical.

Description

Technical Field

[0001] The invention relates to a differential positioning system based on a PC5 interface, belonging to the technical field of vehicle networking communication. Background Art

[0002] The existing mobile communication network 4G / 5G has insufficient coverage, and RTK cannot communicate efficiently with the calibration server, resulting in a decrease in positioning accuracy. At present, global navigation satellite systems such as the Beidou Global Positioning System (BDS) can provide navigation and positioning services with an accuracy of several meters. By installing Beidou reference stations at fixed locations, the known positions are used to correct the errors introduced in the Beidou satellite signals to calculate the error between the observed pseudorange and the theoretical calculated pseudorange, and the error parameters are transmitted to the mobile user end through the network 4G / 5G data link according to the RTCM protocol. The user end combines its own GNSS observation information with the RTCM differential information, and after data processing, calculates and obtains high-precision differential positioning results. The RTK differential correction technology can obtain centimeter-level accuracy. By deploying a continuously operating Beidou reference station (CORS) network to provide RTK services over a large range, the calibration is most accurate when the mobile user end is close to the Beidou reference station that receives its calibration, and the accuracy of the calibration becomes worse as the distance increases. The existing RTK technology configures the 4G / 5G network for the mobile user terminal to establish a data link for RTCM differential information, and needs to report the user's preliminary location information to the calibration server to track the mobile user terminal. By tracking the user's position movement and sending different RTCM differential information, there is a risk of user privacy leakage. Summary of the invention

[0003] The purpose of the present invention is to provide a high-precision positioning technology for vehicles based on the PC5 interface of the C-V2X network, so as to solve the problems of insufficient 4G / 5G coverage of the communication network, inefficient communication, reduced accuracy and privacy leakage, and a differential positioning system based on the PC5 interface.

[0004] A differential positioning system based on a PC5 interface proposed in the present invention includes a calibration server, a Beidou reference station, an RSU, and an OBU. The Beidou reference station and the calibration server are connected through a wired or wireless network to establish an NTRIP service. The RTCM differential information observed by the Beidou reference station is transmitted to the calibration server through a designated port. A TCP / IP connection is established between the calibration server and the RSU, and a corresponding relationship between the RSU location information list and the Beidou reference station location information list and coverage is established, and the Beidou reference station RTCM differential information is sent to the corresponding RSU.

[0005] The RSU includes a C-V2X wireless module, a coding module, a processor, a network module, and a positioning module. The processor coordinates the work of the C-V2X wireless module, the coding module, the network module, and the positioning module. The positioning module obtains the location information of the RSU. The network module receives the RTCM differential information sent by the calibration server, parses the RTCM differential information through the NTRIP client function of the processor, encodes it with the C-V2X encoder, and sends it in a broadcast manner through the PC5 interface of the C-V2X wireless module.

[0006] The OBU includes a C-V2X wireless module, a decoding module, a processor, an RTK / RTD module, and a 4G / 5G module. It receives information through the PC5 interface of C-V2X and decodes it with the decoder of C-V2X to obtain RTCM differential information.

[0007] The OBU can simultaneously obtain the RTCMB differential information through the 4G / 5G module and the RTCMa differential information through the C-V2X module. The processor provides it to the RTK / RTD module according to the principle of RTCMa priority, that is, as long as the RTCMa differential information is obtained, regardless of whether RTCMb is received, only RTCMa will be provided to the RTK / RTD module for differential positioning, and the 4G / 5G module can be turned off to save power consumption and protect privacy.

[0008] There are multiple Beidou reference stations.

[0009] A differential positioning system based on a PC5 interface proposed in the present invention includes a calibration server, a Beidou reference station, an RSU, and an OBU. The Beidou reference station and the calibration server are connected through a wired or wireless network to establish an NTRIP service. RTCM differential information observed by the Beidou reference station is transmitted to the calibration server through a designated port. A TCP / IP connection is established between the calibration server and the RSU, and a corresponding relationship between the RSU location information list and the Beidou reference station location information list and coverage is established, and the Beidou reference station RTCM differential information is sent to the corresponding RSU.

[0010] The system designs a differential positioning system among reference stations, RSUs, and OBUs, and implements differential positioning and communication modes based on the PC5 interface. Through differential data encoding, decoding, and transmission, the system realizes efficient communication of RTCM differential information between RSUs and mobile user-side OBUs, provides high-precision positioning coverage under the C-V2X network, and ensures the normal operation of the RTK / RTD module. At the same time, in the C-V2X mode, there is no need to report the location of the mobile user side, which protects the user's location privacy and solves the problem that when the existing mobile communication network 4G / 5G is insufficiently covered, RTK cannot communicate efficiently with the calibration server, resulting in reduced positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Attached Figure 1 This is a schematic diagram of an application of a differential positioning system based on a PC5 interface proposed in the present invention;

[0012] Attached Figure 2 This is a principle block diagram of a differential positioning system based on a PC5 interface proposed by the present invention;

[0013] Attached Figure 3 This is a flow chart of a differential positioning system based on PC5 interface proposed by the present invention;

[0014] Attached Figure 4 This is a RTCM correspondence diagram between RSU and Beidou reference station in a differential positioning system based on PC5 interface proposed by the present invention. DETAILED DESCRIPTION

[0015] See also Figures 1 to 4 , these four figures provide an overall block diagram of an embodiment of a differential positioning system based on a PC5 interface proposed by the present invention.

[0016] Among them, V2X stands for Vehicle to Everything;

[0017] OBU is On Board Unit, which is installed on the vehicle;

[0018] RSU is a road side unit, installed on the road side;

[0019] RTCM: Radio Technical Commission for Maritime Services (RTCM) protocols is the protocol for the GNSS differential signal format proposed by the International Maritime Radio Technical Commission.

[0020] NTRIP: Networked Transport of RTCM via Internet Protocol RTCM network transmission protocol based on the Internet;

[0021] PC5: Direct communication interface in C-V2X network;

[0022] The system includes a calibration server, a Beidou reference station, an RSU, and an OBU. The Beidou reference station is connected to the calibration server through a wired or wireless network to establish an NTRIP service, wherein the RTCM differential information observed by the Beidou reference station is transmitted to the calibration server through a designated port, the calibration server saves the RTCM differential information and establishes a TCP / IP connection with the RSU, establishes a corresponding relationship between the two according to the location information list of the RSU and the location information list of the Beidou reference station according to the coverage range, and sends the Beidou reference station RTCM differential information to the corresponding RSU. The RSU roadside unit includes a C-V2X wireless module, an encoding module, a processor, a network module, and a positioning module. The processor coordinates the work of the C-V2X wireless module, the encoding module, the network module, and the positioning module. The positioning module obtains the location information of the RSU, the network module receives the RTCM differential information sent by the calibration server, parses the RTCM differential information through the NTRIP client function of the processor, encodes it with the C-V2X encoder, and sends it in a broadcasting manner through the PC5 interface of the C-V2X wireless module.

[0023] The OBU on-board unit includes a C-V2X wireless module, a decoding module, a processor, an RTK / RTD module, and a 4G / 5G module. It is received through the PC5 interface of C-V2X and decoded with the decoder of C-V2X to obtain RTCM differential information. The OBU on-board unit can simultaneously obtain the RTCMb differential information through the 4G / 5G module and the RTCMa differential information through the C-V2X module. The processor provides it to the RTK / RTD module according to the principle of RTCMa priority, that is, as long as the RTCMa differential information is obtained, regardless of whether RTCMb is received, only RTCMa will be provided to the RTK / RTD module for differential positioning, and the 4G / 5G module can be turned off.

[0024] The OBU vehicle-mounted unit differential positioning process is divided into preliminary positioning, uploading preliminary positioning information and obtaining RTCM differential information in 4G / 5G mode, obtaining RTCM differential information in C-V2X mode, and the processor determines RTCMa / RTCMb and RTK / RTD modules for precise positioning. Figure 3As shown. There are two data links for OBU differential positioning: 4G / 5G and C-V2X. The difference between the two is that: to obtain RTCM differential information through 4G / 5G, it is necessary to report its own position data to the calibration server in advance, and the calibration server sends the corresponding RTCM differential information based on the position information; to obtain RTCM differential information through C-V2X, there is no need to report its own position data. The coverage range of V2X's RSU is usually 300m-500m. A Beidou reference station can usually provide RTK services in the range of 10km-50km. Therefore, the coverage range of a single RSU can be considered to have the same RTCM differential information. By establishing a data link between the calibration server and the RSU, multiple RSUs broadcast the RTCM differential information in the corresponding area, such as Figure 4 As shown in the figure, the OBU on the vehicle only needs to receive information from the RSU during movement, and there is no need to report its own OBU location data. The use of 4G / 5G and C-V2X dual-mode in the implementation process can achieve the complementarity of the two networks. When located in the coverage area of ​​the C-V2X network, the C-V2X network is used first, and the 4G / 5G mode can be turned off to save power consumption and protect privacy.

[0025] The system can realize efficient communication of RTCM differential information between RSU and mobile user-side OBU, provide high-precision positioning coverage under the C-V2X network, and ensure the normal operation of the RTK / RTD module. At the same time, there is no need to report the location of the mobile user side in C-V2X mode, which protects the user's location privacy. At the same time, it solves the problem that when the existing mobile communication network 4G / 5G has insufficient coverage, RTK cannot communicate efficiently with the calibration server, resulting in a decrease in positioning accuracy. It can also save power consumption and is highly practical.

Claims

1. A differential positioning system based on PC5 interface, characterized in that: It includes a calibration server, a Beidou reference station, an RSU, and an OBU. The Beidou reference station and the calibration server are connected through a wired or wireless network to establish an NTRIP service. The RTCM differential information observed by the Beidou reference station is transmitted to the calibration server through a designated port. A TCP / IP connection is established between the calibration server and the RSU, and a corresponding relationship between the RSU location information list and the Beidou reference station location information list and network coverage is established, and the Beidou reference station RTCM differential information is sent to the corresponding RSU.

2. A differential positioning system based on PC5 interface according to claim 1, characterized in that: The RSU includes a C-V2X wireless module, a coding module, a processor, a network module, and a positioning module. The processor coordinates the work of the C-V2X wireless module, the coding module, the network module, and the positioning module. The positioning module obtains the location information of the RSU. The network module receives the RTCM differential information sent by the calibration server, parses the RTCM differential information through the NTRIP client function of the processor, encodes it with the C-V2X encoder, and sends it in a broadcast manner through the PC5 interface of the C-V2X wireless module.

3. A differential positioning system based on PC5 interface according to claim 1, characterized in that: The OBU includes a C-V2X wireless module, a decoding module, a processor, an RTK / RTD module, and a 4G / 5G module. It receives information through the PC5 interface of C-V2X and decodes it with the decoder of C-V2X to obtain RTCM differential information.

4. A differential positioning system based on PC5 interface according to claim 3, characterized in that: The OBU can simultaneously obtain the RTCMB differential information through the 4G / 5G module and the RTCMa differential information through the C-V2X module. The processor provides it to the RTK / RTD module according to the principle of RTCMa priority, that is, as long as the RTCMa differential information is obtained, regardless of whether RTCMb is received, only RTCMa will be provided to the RTK / RTD module for differential positioning, and the 4G / 5G module can be turned off.

5. A differential positioning system based on PC5 interface according to claim 1, characterized in that: There are multiple Beidou reference stations.

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