A Beidou ground-based enhanced positioning method and system based on 5G NR

Abstract

The present invention discloses a Beidou ground-based enhanced positioning method and system based on 5G NR, which belongs to the field of Beidou positioning technology. The method includes: receiving the GNSS signal of Beidou satellite through a full-frequency GNSS antenna; receiving the GNSS signal forwarded by the full-frequency GNSS antenna through a 5G NR receiver; demodulating the GNSS signal received by the 5G NR receiver through a 5G NR demodulator and sending it to a 5G NR base station, and the 5G NR base station provides Beidou ground-based enhanced differential service through 5G NR broadcast technology; the user terminal receives the Beidou ground-based enhanced differential service of the 5G NR base station and obtains the GNSS signal for position solution to obtain a dynamic positioning result. The present invention combines 5G NR broadcast technology with Beidou / GNSS technology to realize Beidou ground-based differential data enhancement, reduce the cost of broadcasting Beidou high-precision wide-area data, remote sensing images and video services, and enhance broadcasting efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of Beidou positioning technology, and specifically relates to a Beidou ground-based enhanced positioning method and system based on 5G NR. Background Art

[0002] The development of Beidou space-time information has provided people with more convenient and accurate space and time information services, and promoted technological development and progress in many fields. At present, the Beidou / GNSS base station system that has been built mainly serves the fields of high-precision surveying and mapping such as natural resources, water affairs, and electricity. Beidou's high-precision real-time positioning plays a vital role in improving the intelligence level of intelligent connected vehicles, but the system's carrying capacity, server computing power, and network data link bandwidth cannot support the application needs of millions of terminals in the mass field such as intelligent connected vehicles.

[0003] The BeiDou Satellite-Based Augmentation System is an important part of the BeiDou Satellite Navigation System. Through the satellite navigation augmentation signal repeater carried by the geostationary orbit satellite, it can broadcast various correction information such as ephemeris error, satellite clock error, ionospheric delay, etc. to users, thereby improving the positioning accuracy of the original satellite navigation system. The BeiDou ground-based augmentation method based on 5G has been initially applied. It generally adopts the Continuous Operational Reference System (CORS). Some applications show that 5G+BeiDou has a good effect in enhancing high-precision positioning. CORS consists of one or several fixed, continuously operating GNSS reference stations, and uses computers, data communications and Internet technologies to form a communication network. However, the construction cost is high, which is not conducive to promotion, and the actual use efficiency is not high.

[0004] Therefore, a new Beidou ground-based enhanced positioning system and method is needed to reduce the forwarding cost of location services and thereby improve the efficiency of the system. Summary of the invention

[0005] In view of this, the present invention proposes a Beidou ground-based enhanced positioning method and system based on 5G NR, which is used to solve the problem of low efficiency of the existing Beidou ground-based augmentation method.

[0006] The present invention proposes a Beidou ground-based enhanced positioning method based on 5G NR, the method comprising:

[0007] Receive GNSS signals from Beidou satellites through a full-frequency GNSS antenna;

[0008] Receive GNSS signals forwarded by the full-frequency GNSS antenna through the 5G NR receiver;

[0009] The GNSS signal received by the 5G NR receiver is demodulated by the 5G NR demodulator and sent to the 5G NR base station. The 5G NR base station provides Beidou ground-based enhanced differential service through 5G NR broadcast technology;

[0010] The user terminal receives the Beidou ground-based enhanced differential service from the 5G NR base station in real time and obtains the GNSS signal for position solution to obtain dynamic positioning results.

[0011] Based on the above technical solution, preferably, the 5G NR demodulator is communicatively connected to the 5G NR receiver via a Bluetooth communication link.

[0012] On the basis of the above technical solution, preferably, in the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the 5G NR base station adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission;

[0013] If the signal-to-noise ratio of the signal received by the user terminal during multicast transmission is less than the dynamic switching threshold, the transmission between the 5GNR base station and the user terminal is switched to unicast transmission.

[0014] On the basis of the above technical solution, preferably, the dynamic switching threshold of 5GNR multicast / unicast transmission is set by using an adaptive degradation threshold method, which specifically includes:

[0015] Taking each 5G NR base station as a unit, the downlink power allocation calculation is performed by dividing the 5G NR base station power by the transmit power of the 5G NR base station on each subcarrier at each time;

[0016] Calculate the downlink throughput based on the total request duration, average response time, and number of downlink channels;

[0017] The dynamic switching threshold of 5GNR multicast / unicast transmission is calculated based on the downlink power allocation calculation results, downlink throughput and the initial value of downlink effective resources.

[0018] On the basis of the above technical solution, preferably, the formula for calculating the downlink power allocation by equally dividing the 5G NR base station power by the transmit power of the 5G NR base station on each subcarrier at each time is:

[0019] EPRE=P eNB,max -101g(N)

[0020] Among them, EPRE is the downlink power of each subcarrier, P eNB，max is the maximum cell transmit power of the 5G NR base station; N is the number of subcarriers contained in the bandwidth of the 5G NR base station, and the calculation formula of N is as follows:

[0021]

[0022] Among them, BW is the bandwidth of the 5G NR base station, GuardBW is the protection bandwidth, and SCS is the subcarrier spacing.

[0023] On the basis of the above technical solution, preferably, the formula for calculating the downlink throughput according to the total request duration, the average response time, and the number of downlink channels is:

[0024]

[0025] Where n is the total request duration, L is the average response time, T is the total duration of the request and response, and I is the number of downlink channels.

[0026] On the basis of the above technical solution, preferably, the formula for calculating the dynamic switching threshold of 5G NR multicast / unicast transmission according to the downlink power allocation calculation result, the downlink throughput and the initial value of the downlink effective resources is:

[0027]

[0028] Among them, SINP Threshold is the dynamic switching threshold for 5G NR multicast / unicast transmission, SINR0 is the initial value of downlink effective resources, SINR0=N RB *N slot , N slot is the number of time slots, N RB is the number of RBs corresponding to each time slot; w1 and w2 are weight coefficients, b is the correction constant, and t represents time.

[0029] On the basis of the above technical solution, preferably, the method further comprises:

[0030] Receive the GNSS signal forwarded by the full-frequency GNSS antenna through a measurement receiver;

[0031] The user terminal receives the GNSS signal forwarded by the measurement receiver and performs position calculation to obtain a reference positioning result;

[0032] Compare the dynamic positioning results with the reference positioning results to evaluate the accuracy of dynamic positioning.

[0033] In a second aspect of the present invention, a Beidou ground-based enhanced positioning system based on 5G NR is disclosed, the system comprising:

[0034] Full-frequency GNSS antenna, used to receive GNSS signals from Beidou satellites;

[0035] 5G NR receiver, used to receive GNSS signals forwarded by full-frequency GNSS antennas;

[0036] 5G NR demodulator, used to demodulate the GNSS signal received by the 5G NR receiver and send it to the 5G NR base station;

[0037] 5G NR base station, used to provide Beidou ground-based enhanced differential services through 5G NR broadcast technology and forward GNSS signals;

[0038] The user terminal is used to receive the Beidou ground-based enhanced differential service of the 5G NR base station in real time and obtain the GNSS signal for position solution to obtain dynamic positioning results.

[0039] On the basis of the above technical solution, preferably, in the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the 5G NR base station adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission;

[0040] If the signal-to-noise ratio of the signal received by the user terminal during multicast transmission is less than the dynamic switching threshold, the transmission between the 5GNR base station and the user terminal is switched to unicast transmission.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1) The present invention receives the GNSS signal forwarded by the full-frequency GNSS antenna through a 5G NR receiver, demodulates it through a 5G NR demodulator and sends it to the 5G NR base station, forwards the GNSS signal through the 5G NR broadcast technology of the 5G NR base station, and the user terminal receives the GNSS signal through the 5G NR broadcast technology to achieve positioning; the present invention combines 5G NR broadcast technology with Beidou / GNSS technology to achieve Beidou ground-based differential data enhancement, which can reduce the broadcasting cost of Beidou high-precision wide-area data, remote sensing images and video services, and synergistically enhance the broadcasting efficiency of Beidou high-precision wide-area data, remote sensing images and video services.

[0043] 2) In the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the present invention takes into account the user terminal with the worst receiving condition in the group, and adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission. If the signal-to-noise ratio of the signal received by the user terminal in multicast transmission is less than the dynamic switching threshold, it switches to unicast transmission, thereby realizing dynamic switching of unicast / multicast service mode according to the channel environment, ensuring the normal multicast service, and even the user terminal with the worst receiving condition can receive real-time GNSS signal, thereby improving the reliability of positioning service in harsh channel environment.

[0044] 3) The present invention calculates the downlink power allocation by evenly dividing the 5G NR base station power by the transmission power of the 5G NR base station on each subcarrier at each moment, calculates the downlink throughput according to the total request duration, the average response time, and the number of downlink channels, and calculates the dynamic switching threshold of 5G NR multicast / unicast transmission according to the downlink power allocation calculation result, the downlink throughput, and the initial value of the downlink effective resources, so as to realize the rapid switching of multicast / unicast transmission modes in different channel environments, reduce the channel resource occupancy, increase the data transmission efficiency, and improve the GNSS data relay efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A schematic diagram of the structure of a Beidou ground-based enhanced positioning system based on 5G NR proposed by the present invention;

[0047] Figure 2 This is a flow chart of a Beidou ground-based enhanced positioning method based on 5G NR proposed in the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] See also Figure 1 The present invention proposes a Beidou ground-based enhanced positioning system based on 5G NR, which includes a full-frequency GNSS antenna, a 5G NR receiver, a 5G NR demodulator, a 5G NR base station and a user terminal.

[0050] Full-frequency GNSS antenna, used to receive GNSS signals from Beidou satellites.

[0051] 5G NR receiver, used to receive GNSS signals forwarded by full-frequency GNSS antenna.

[0052] To ensure the quality of GNSS signals, the 5G NR receiver uses a 5G NR high-precision receiver. The 5G NR receiver is connected to the full-frequency GNSS antenna through RF cables, power dividers and other devices, and the 5G NR receiver must be powered normally.

[0053] The 5G NR demodulator is used to demodulate the GNSS signal received by the 5G NR receiver and send it to the 5G NR base station. Before positioning begins, the 5G NR demodulator needs to be set up so that the demodulator and the 5G NR base station can establish a stable data connection. A Bluetooth link also needs to be set up, that is, the data protocol of the 5G NR demodulator is forwarded to the 5G NR receiver using the Bluetooth communication link.

[0054] 5G NR base station, used to provide Beidou ground-based enhanced differential services through 5G NR broadcast technology and forward GNSS signals.

[0055] The 5G NR base stations of the present invention are uniformly constructed in an outdoor macro station manner, and the BBUs are all Huawei 5900 devices, among which: the radio and television tower antenna BBU is placed in the TV tower machine room, the station type is set to S111, the cellular network base station BBU is placed in the TV tower microwave room, the RRU and antenna are placed on the maintenance platform in the 135 antenna area, and the antenna is hung at a height of 225 meters.

[0056] The user terminal is used to receive the Beidou ground-based enhanced differential service of the 5G NR base station in real time and obtain the GNSS signal for position solution to obtain dynamic positioning results.

[0057] In the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the 5G NR base station establishes communication with the user terminal through multicast, and sends GNSS signals to the members of the multicast group according to the request of the user terminal. Considering the different signal reception conditions of different user terminals, the user terminal with the worst reception condition in the group may not be able to receive real-time GNSS signals. Therefore, the present invention adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission. If the signal-to-noise ratio of the signal received by the user terminal in the multicast transmission is less than the dynamic switching threshold, the 5G NR base station and the user terminal are switched to unicast transmission. Dynamic switching of unicast / multicast service mode is realized according to the channel environment to ensure the normal multicast service. Even the user terminal with the worst reception condition can receive real-time GNSS signals, which improves the reliability of positioning services in harsh channel environments.

[0058] Build it Figure 1 After the Beidou ground-based enhanced positioning system based on 5G NR is shown, user terminal adaptation verification, signal reception and positioning performance testing are required.

[0059] (1) User terminal adaptation verification. The present invention takes a smart phone and a Beidou vehicle networking navigation and positioning terminal as test terminals as examples to illustrate the adaptation test of the user terminal.

[0060] When using smartphones as test terminals, two versions supporting NR broadcast are selected, with a system bandwidth of 45MHz, an uplink frequency range of 733-748, a downlink frequency range of 788-803MHz, and a subcarrier spacing of 15kHz; the Application Server is set to support streaming video broadcasting service capabilities. The test terminal is pre-installed with the China Broadcasting Corporation NR multicast broadcast APP that supports broadcasting services.

[0061] When the Beidou Internet of Vehicles navigation and positioning terminal is used as the test terminal, the positioning module / chip of the 5G Beidou vehicle network positioning terminal adopts the MXT206DM module / MXT 2720 chip. The MXT206DM positioning module is a high-precision, high-performance, and high-reliability positioning application module based on the MXT2720 chip. It supports on-chip RTK, supports BDS / GPS / GALILEO / GLONASS / QZSS / NAVIC / SBAS full system multi-frequency points, and can optionally support real-time PPP solution. The user terminal receives Beidou ground-based enhanced differential services by using 5G NR broadcast technology, and uses MXT206DM / MXT2720 for solution to provide high-precision spatiotemporal location services.

[0062] (2) Signal reception and positioning performance test, including 5G NR signal coverage integrity test and user terminal positioning performance test. Start the positioning measurement vehicle, use mobile devices such as smartphones and computers as user terminals to receive the GNSS signals broadcast by the 5G NR base station, test the GNSS signal tracking, the reception of the carrier-to-noise ratio differential data of the 5G NR signal, and the positioning results and status.

[0063] 5G NR signal coverage integrity test. Using dedicated signal testing equipment, we start from the TV tower and drive in different directions to test signal coverage, signal strength, and shielding between high-rise buildings.

[0064] User terminal positioning performance test. The three-dimensional positioning test vehicle equipped with the Beidou vehicle networking navigation and positioning terminal drives along the set route. The Beidou vehicle networking navigation and positioning terminal uses 5G NR broadcast technology to receive the Beidou ground-based enhanced differential service broadcast by the 5G NR base station, obtain GNSS signals, and solve to obtain dynamic positioning results. In order to evaluate the positioning accuracy, a measurement receiver can be added, such as Figure 1As shown, while a 5G NR receiver is used to receive the GNSS signal forwarded by the full-frequency GNSS antenna, a measurement receiver is used to receive the GNSS signal forwarded by the full-frequency GNSS antenna through WHCORS. The user terminal establishes a communication connection with the 5G NR receiver and the measurement receiver through a Bluetooth communication link or a wireless network to receive the GNSS signal. The user terminal receives the GNSS signal forwarded by the measurement receiver and performs position solution to obtain a reference positioning result. The spatial accuracy of the dynamic positioning result is compared with the reference positioning result, and the continuity, integrity, reliability, carrier-to-noise ratio, delay and other information of the 5G NR signal during the driving of the positioning test vehicle are evaluated and analyzed to evaluate the accuracy of the dynamic positioning result.

[0065] The present invention combines 5G NR broadcast technology with Beidou / GNSS technology to achieve Beidou ground-based differential data enhancement, which is suitable for satellite forwarding of data such as high-precision wide-area data, remote sensing images and video services, reducing the broadcasting cost of Beidou high-precision wide-area data, remote sensing images and video services, and making it more practical.

[0066] On the basis of the above system embodiments, the present invention also proposes a Beidou ground-based enhanced positioning method based on 5G NR, such as Figure 2 As shown, the method includes:

[0067] S1. Receive the GNSS signal of Beidou satellite through the full-frequency GNSS antenna.

[0068] Use as Figure 1 The Beidou ground-based enhanced positioning system based on 5G NR is shown, which receives GNSS signals from Beidou satellites through a full-frequency GNSS antenna.

[0069] S2. Receive the GNSS signal forwarded by the full-frequency GNSS antenna through the 5G NR receiver.

[0070] The 5G NR receiver receives the RF signal from the antenna, and processes the received GNSS signal through front-end RF processing and digital signal processing to convert the signal into digital data and separate the required GNSS signal from it.

[0071] S3: The GNSS signal received by the 5G NR receiver is demodulated by the 5G NR demodulator and sent to the 5G NR base station. The 5G NR base station provides Beidou ground-based enhanced differential service through 5G NR broadcast technology.

[0072] The present invention establishes a communication connection between a 5G NR demodulator and a 5G NR receiver through a Bluetooth communication link. In the process of the 5G NR base station providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the user terminal with the worst receiving condition in the group is taken into consideration, and the dynamic switching threshold of 5G NR multicast / unicast transmission is set by an adaptive degradation threshold method. If the signal-to-noise ratio of the signal received by the user terminal in the multicast transmission is less than the dynamic switching threshold, it is switched to unicast transmission, and the unicast / multicast service mode is dynamically switched according to the channel environment to ensure the normal multicast service. Even the user terminal with the worst receiving condition can receive real-time GNSS signals, thereby improving the reliability of positioning services in harsh channel environments.

[0073] Specifically, the steps for calculating the dynamic switching threshold for 5G NR multicast / unicast transmission are:

[0074] a. Calculation of the initial value of downlink effective resources (number of PRBs).

[0075] SINR0=N RB *N slot

[0076] Among them, SINR0 is the initial value of the downlink effective resource, N RB N is the number of RBs corresponding to each time slot. When the subcarrier spacing SCS is 30kHz, RB The value is 78, N slot is the number of time slots, which depends on the subcarrier spacing and has an initial value of 2; therefore, the initial value of SINR0 can be 156.

[0077] b. Taking each 5G NR base station as a unit, the downlink power allocation calculation is performed by dividing the 5G NR base station power by the transmit power of the 5G NR base station on each subcarrier at each time. The calculation formula for downlink power allocation is:

[0078] EPRE=P eNB,max -101g(N)

[0079] Among them, EPRE is the downlink power of each subcarrier, in dBm, P eNB，max is the maximum cell transmit power of the 5G NR base station; N is the number of subcarriers contained in the system bandwidth of the 5G NR base station, and the calculation formula of N is as follows:

[0080]

[0081] Among them, BW is the system bandwidth of the 5G NR base station, GuardBW is the protection bandwidth, and SCS is the subcarrier spacing.

[0082] c. Calculate the downlink throughput based on the total request duration, average response time, and number of downlink channels. The calculation formula for the downlink throughput is:

[0083]

[0084] Where n is the total request duration, L is the average response time, T is the total duration of the request and response, and I is the number of downlink channels.

[0085] d. Calculate the dynamic switching threshold of 5GNR multicast / unicast transmission based on the downlink power allocation calculation results, downlink throughput and the initial value of downlink effective resources.

[0086] The formula for calculating the dynamic switching threshold is:

[0087]

[0088] Among them, SINR Threshold is the dynamic switching threshold of 5G NR multicast / unicast transmission, SINR0 is the initial value of downlink effective resources, w1 and w2 are weight coefficients, b is the correction constant, and t represents time.

[0089] If the SINR of the signal received by the user terminal during multicast transmission is less than the dynamic switching threshold SINR Threshold , switch the transmission between the 5G NR base station and the user terminal to unicast transmission.

[0090] The present invention calculates downlink power allocation in a manner of evenly dividing the 5G NR base station power by the transmission power of the 5G NR base station on each subcarrier at each moment; calculates the downlink throughput according to the total request duration, the average response time, and the number of downlink channels; calculates the dynamic switching threshold of 5G NR multicast / unicast transmission according to the downlink power allocation calculation result, the downlink throughput, and the initial value of the downlink effective resources, so as to realize fast switching of multicast / unicast transmission modes under different channel environments, reduce channel resource occupancy, increase data transmission efficiency, and improve GNSS data relay efficiency.

[0091] S4. The user terminal receives the Beidou ground-based enhanced differential service from the 5G NR base station in real time and obtains the GNSS signal for position solution to obtain dynamic positioning results.

[0092] The present invention receives the GNSS signal forwarded by the full-frequency GNSS antenna through the 5G NR receiver, demodulates it through the 5G NR demodulator and sends it to the 5G NR base station, broadcasts the GNSS signal through the 5G NR broadcast technology of the 5G NR base station, and the user terminal receives the GNSS signal through the 5G NR broadcast technology to achieve differential positioning. By combining 5G NR broadcast technology with Beidou / GNSS technology, Beidou ground-based differential data enhancement is achieved, which is suitable for satellite forwarding of data such as high-precision wide-area data, remote sensing images and video services, which can reduce the cost of Beidou's high-precision wide-area data, remote sensing images and video services, and synergistically enhance the efficiency of Beidou's high-precision wide-area data, remote sensing images and video services, making it more practical.

[0093] The above system embodiments and method embodiments correspond to each other one by one, and please refer to each other for the brief descriptions of different embodiments.

[0094] The present invention also discloses an electronic device, comprising: at least one processor, at least one memory, a communication interface and a bus; wherein the processor, memory, and communication interface communicate with each other through the bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to implement the aforementioned method of the present invention.

[0095] The present invention also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to implement all or part of the steps of the method described in the embodiment of the present invention. The storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk, and other media that can store program codes.

[0096] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be distributed to multiple network units. A person skilled in the art may select some or all of the modules according to actual needs to achieve the purpose of the solution of this embodiment without creative effort.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Beidou ground-based enhanced positioning method based on 5G NR, characterized in that: The method comprises: Receive GNSS signals from Beidou satellites through a full-frequency GNSS antenna; Receive GNSS signals forwarded by the full-frequency GNSS antenna through the 5G NR receiver; The GNSS signal received by the 5G NR receiver is demodulated by the 5G NR demodulator and sent to the 5G NR base station. The 5G NR base station provides Beidou ground-based enhanced differential service through 5G NR broadcast technology; The user terminal receives the Beidou ground-based enhanced differential service from the 5G NR base station in real time and obtains the GNSS signal for position solution to obtain dynamic positioning results; In the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the 5G NR base station adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission; If the signal-to-noise ratio of the signal received by the user terminal during multicast transmission is less than the dynamic switching threshold, the transmission between the 5GNR base station and the user terminal is switched to unicast transmission; The method of setting the dynamic switching threshold of 5G NR multicast / unicast transmission by using an adaptive degradation threshold specifically includes: Taking each 5G NR base station as a unit, the downlink power allocation calculation is performed by dividing the 5G NR base station power by the transmit power of the 5G NR base station on each subcarrier at each time; Calculate the downlink throughput based on the total request duration, average response time, and number of downlink channels; The dynamic switching threshold of 5GNR multicast / unicast transmission is calculated based on the downlink power allocation calculation results, downlink throughput and the initial value of downlink effective resources.

2. The Beidou ground-based enhanced positioning method based on 5G NR according to claim 1, characterized in that: The 5G NR demodulator is communicatively connected to the 5G NR receiver via a Bluetooth communication link.

3. The Beidou ground-based enhanced positioning method based on 5G NR according to claim 1, characterized in that: The formula for calculating the downlink power allocation by equally dividing the 5G NR base station power by the transmission power of the 5G NR base station on each subcarrier at each time is: EPRE=P eNB，max -10lg(N) Among them, EPRE is the downlink power of each subcarrier, P eNB，max is the maximum cell transmit power of the 5G NR base station; N is the number of subcarriers contained in the bandwidth of the 5G NR base station, and the calculation formula of N is as follows: Among them, BW is the bandwidth of the 5G NR base station, GuardBW is the protection bandwidth, and SCS is the subcarrier spacing.

4. The Beidou ground-based enhanced positioning method based on 5G NR according to claim 3 is characterized in that: The formula for calculating the downlink throughput based on the total request duration, average response time, and number of downlink channels is: Where n is the total request duration, L is the average response time, T is the total duration of the request and response, and I is the number of downlink channels.

5. The Beidou ground-based enhanced positioning method based on 5G NR according to claim 4 is characterized in that: The formula for calculating the dynamic switching threshold of 5G NR multicast / unicast transmission based on the downlink power allocation calculation result, the downlink throughput and the initial value of the downlink effective resources is: Among them, SINR Threshold is the dynamic switching threshold for 5G NR multicast / unicast transmission, SINR0 is the initial value of downlink effective resources, SINR0=N RB *N slot , N slot is the number of time slots, N RB is the number of RBs corresponding to each time slot; w1 and w2 are weight coefficients, b is the correction constant, and t represents time.

6. The Beidou ground-based enhanced positioning method based on 5G NR according to claim 1, characterized in that: The method further comprises: Receive the GNSS signal forwarded by the full-frequency GNSS antenna through a measurement receiver; The user terminal receives the GNSS signal forwarded by the measurement receiver and performs position calculation to obtain a reference positioning result; Compare the dynamic positioning results with the reference positioning results to evaluate the accuracy of dynamic positioning.

7. A Beidou ground-based enhanced positioning system based on 5G NR using the method described in any one of claims 1 to 6, characterized in that: The system comprises: Full-frequency GNSS antenna, used to receive GNSS signals from Beidou satellites; 5G NR receiver, used to receive GNSS signals forwarded by full-frequency GNSS antennas; 5G NR demodulator, used to demodulate the GNSS signal received by the 5G NR receiver and send it to the 5G NR base station; 5G NR base station, used to provide Beidou ground-based enhanced differential service through 5G NR broadcast technology and forward GNSS signals; The user terminal is used to receive the Beidou ground-based enhanced differential service of the 5G NR base station in real time and obtain the GNSS signal for position solution to obtain dynamic positioning results.

8. The Beidou ground-based enhanced positioning system based on 5G NR according to claim 7, characterized in that: In the process of providing Beidou ground-based enhanced differential service through 5G NR broadcast technology, the 5G NR base station adopts an adaptive degradation threshold method to set the dynamic switching threshold of 5G NR multicast / unicast transmission; If the signal-to-noise ratio of the signal received by the user terminal during multicast transmission is less than the dynamic switching threshold, the transmission between the 5GNR base station and the user terminal is switched to unicast transmission.

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