A fusion positioning method based on 5G carrier phase

Abstract

The present invention belongs to the field of mobile communication technology, and specifically is a fusion positioning method based on 5G carrier phase. The present invention integrates DL-TDOA and carrier phase measurement technology; at least four 5G base stations (BS) are deployed within the accessible range of the UE. The BS sends a positioning signal modulated by OFDM to the UE, and uses the DL-TDOA positioning method to solve the low-precision spatial position of the UE on the UE side, and obtain the straight-line distance between the UE and each BS; on the UE side, the positioning signal of each BS is used to calculate the carrier phase, and the distance obtained by DL-TDOA is combined to establish a constraint equation, and the three-dimensional spatial coordinates of the UE are solved to achieve high-precision positioning of the UE. The present invention utilizes the characteristics of 5G large bandwidth, increases the equivalent carrier wavelength by combining subcarriers, and reduces the difficulty of solving the carrier integer ambiguity.

Description

Technical Field

[0001] The present invention belongs to the field of mobile communication technology, and in particular relates to a high-precision positioning method integrating DL-TDOA and carrier phase measurement. Background Art

[0002] With the rapid development of information technology, high-precision positioning technology has gained attention in a variety of industries, including smart supermarkets, intelligent manufacturing, and autonomous driving. Traditional GNSS positioning technology is widely used in outdoor high-precision positioning scenarios, with RTK (Real Time Kinematic) carrier phase differential technology providing centimeter-level positioning accuracy. However, for indoor high-precision positioning applications, GNSS signal transmission is limited, and a mature solution currently lacks.

[0003] 5G technology has the advantages of high bandwidth, high carrier frequency, multiple antennas, and high network density. Its integrated coverage brings new possibilities for achieving high-precision indoor positioning. Existing 5G positioning solutions include: 1. Downlink Time Difference of Arrival (DL-TDOA), 2. Angle of Arrival (AOA), and 3. Round Trip Time (RTT). Among these positioning solutions, DL-TDOA can provide meter-level positioning accuracy, but this is not enough to achieve high-precision positioning of the target. Carrier phase positioning technology based on carrier phase observations has good results in satellite positioning systems, and the application of carrier phase positioning technology in mobile communication systems is of great significance.

[0004] The 3rd Generation Partnership Project (3G PP) has identified the first projects for Rel-18, the first standard version of 5G-Advanced, which includes carrier phase positioning technology for high-precision positioning scenarios. However, at this stage, only the relevant standards have been formulated. Therefore, there is currently no mature solution for 5G high-precision positioning, and improving the positioning accuracy of 5G communication systems is an urgent problem that needs to be solved. Summary of the Invention

[0005] In response to the above problems, the present invention aims to provide a high-precision fusion positioning method based on 5G carrier phase measurement.

[0006] The present invention provides a fusion positioning method based on 5G carrier phase measurement, which combines downlink time difference of arrival (DL-TDOA) and carrier phase measurement technology to achieve high-precision positioning. Specifically, it uses four 5G base stations with good geometric distribution around the UE (User Equipment, UE, the user equipment to be located) to obtain DL-TDOA and carrier phase measurement results, establish constraint equations, and jointly solve the UE's three-dimensional spatial coordinates, ultimately achieving high-precision positioning of the UE. The specific steps are:

[0007] (1) Coarse positioning based on DL-TDOA

[0008] DL-TDOA positioning is achieved by detecting the time difference between signals sent by different BSs and reaching the UE, rather than directly using the absolute time of signal transmission for positioning. This can effectively reduce the positioning error caused by clock synchronization problems between the UE and the BS. In the three-dimensional DL-TDOA positioning method, it is assumed that there are four 5G base stations deployed around the UE, denoted as BS1, BS2, BS3, and BS4. The UE coordinates are (x, y, z), and the BS i The coordinates are (x i ,y i ,z i ), i={1,2,3,4}. Taking BS1 as the reference station, τ 12 The difference between the time it takes for the signal sent by BS1 to reach the UE and the time it takes for the signal sent by BS2 to reach the UE, τ 13 , τ 14 Similarly. τ 12 , δ 13 , τ 14 With BS i And the coordinate position of the UE satisfies the following relationship:

[0009]

[0010] Where c represents the speed of light, τ 12 , δ 13 , τ 14 It can be directly calculated from the measured value, and the UE coordinates (x, y, z) are unknown quantities to be determined. i The distance between Expressed as:

[0011]

[0012] Among them, the DL-TDOA ranging error has a mean of 0 and a variance of Normal distribution Generally, the DL-TDOA positioning accuracy is at the meter or sub-meter level.

[0013] (2) Carrier Combination

[0014] In addition to DL-TDOA measurements, the UE receives i Another basic measurement value obtained from the transmitted signal is the carrier phase; the current receiver's measurement accuracy for the carrier phase of the non-integer part can reach the millimeter level, but the inability to accurately estimate the integer number of carrier phase cycles leads to inaccurate positioning, and the resolution of integer ambiguity becomes the key to high-precision positioning systems. The present invention combines the high-frequency subcarriers and low-frequency subcarriers of the OFDM system to form an equivalent carrier with a longer wavelength. At the same distance, the integer ambiguity of the equivalent carrier is lower. The present invention does not require the use of two antennas to transmit two carriers of different frequencies respectively. Multiple antennas will introduce more variables, making the implementation of high-precision positioning more difficult.

[0015] The OFDM system divides the transmission channel into multiple mutually orthogonal sub-channels, and the data stream of each sub-channel is modulated to the corresponding sub-carrier for transmission. Figure 2 The transmitting end signal can be expressed in the time domain as follows:

[0016]

[0017] Among them, f n is the frequency of the nth subcarrier, N is the number of subcarriers, a n For baseband data.

[0018] For a communication system with a transmission bandwidth of at least 80 MHz, let the carrier center frequency be f c =1.96GHz, select frequency as f L =f c -40MHz low-frequency subcarrier, frequency f H =f c +40MHz high frequency subcarrier. These two subcarriers can be combined into a frequency of f c ′ =f H -f L =80MHz equivalent carrier, its wavelength λ ′ =3.75m. Within the same signal transmission distance, the integer ambiguity of the combined carrier will be greatly reduced.

[0019] (3) High-precision position calibration through integer ambiguity search and joint resolution

[0020] BS i The signal transmission diagram between UE and Figure 3 , CH i Indicates BS i Transmission channel with UE, i={1,2,3,4}, i represents BS number. i The clock difference with the UE is δ tThe signal transmission distance d is equal to BS i The actual distance between the UE and the target. N Indicates the whole cycle combined carrier distance contained in the signal transmission distance d, d dec It is the non-integer combined carrier distance within the signal transmission distance d. is the clock error δ t Due to the existence of clock error, the carrier phase observation value of the UE does not represent the true value, but the carrier phase observation value that has been superimposed with the clock error and caused the carrier phase to change. L is the number of cycles of the low-frequency subcarrier, N H N is the number of full cycles of the high frequency subcarrier. C is the number of combined carrier cycles, which satisfies N C :N L :N H =1:3:4 (within a combined carrier wavelength length), the wavelength must satisfy λ′=3λ L =4λ H , the frequency satisfies f c ′=f L / 3=f H / 4, and f c ′=f H -f L . Among them, λ′ is the combined carrier wavelength, λ L is the low-frequency subcarrier wavelength, λ H is the wavelength of the high-frequency subcarrier. In combination with the actual situation, if the high-frequency subcarrier frequency f H =2GHz, low-frequency subcarrier frequency f L =1.92GHz. At this time, the combined carrier frequency f c ′=f H -f L =80MHz, N C :N L :N H =1:24:25 (within the length of one combined carrier wavelength).

[0021] The determination of the integer ambiguity is one of the keys to achieve high-precision positioning of UE, which is mainly achieved through two processes: (1) The integer ambiguity N of the high-frequency subcarrier is determined. Hdec and the low-frequency subcarrier integer ambiguity N Ldec Search; (2) Combined carrier integer ambiguity N C search.

[0022] (1) High-frequency subcarrier integer ambiguity N Hdec and the low-frequency subcarrier integer ambiguity N Ldec search;

[0023] First combine Figure 3 and Figure 4 Introducing N Hdec and N Ldec The search process. Figure 4 It mainly includes variable update and condition judgment. The search variable is the number of low-frequency full-cycle subcarriers N. Ldec and the number of high-frequency integer subcarriers N Hdec Among them, N Ldec and N Hdec All are integers. N Hdec and N Ldec The maximum value is calculated as λ′ / λ H and λ′ / λ L For the same signal transmission distance, the wavelength of the high-frequency subcarrier is different from that of the low-frequency subcarrier, but the number of cycles N of the low-frequency subcarrier is the same. Ldec It will always be less than or equal to the number of high-frequency subcarrier cycles N Hdec For the same signal transmission path, the phase changes of the high-frequency subcarrier and the low-frequency subcarrier are different, but the signal transmission distance d calculated based on the phase change of the high-frequency subcarrier or the low-frequency subcarrier is dec are the same, so when there is no error in the carrier phase measurement, d dec =d Ldec =d Hdec Considering that there may be certain errors in the carrier phase measurement process, the condition for terminating the integer ambiguity search is: N Ldec ≤N Hdec And abs(d Ldec -d Hdec ) <d CAerr .d Ldec is the phase measurement value of the low-frequency subcarrier and N Ldec Calculated signal transmission distance. d Hdec is the phase measurement value of the high frequency subcarrier and N Hdec Calculated signal transmission distance. d CAerr is the distance error caused by the carrier phase measurement error. Assume that the carrier phase observation values ​​of the low-frequency subcarrier and the high-frequency subcarrier are and d Ldec with d Hdec It can be calculated by equations (4) and (5). After the high-frequency subcarrier integer ambiguity search and the low-frequency subcarrier integer ambiguity search are completed, d Ldec d Hdec 、N Hdec 、N Ldec The values ​​of are determined.

[0024]

[0025]

[0026] According to the above search d Ldec d Hdec , the distance d of the non-integer part of the combined carrier dec Ideally, d dec =d Ldec =d Hdec But in reality, d Ldec Will not be with d Hdec Completely consistent, at this time d dec Take the average of the two and define it as d dec =(d Ldec +d Hdec ) / 2.

[0027] (2) Combined carrier integer ambiguity N C search;

[0028] In the case of unknown signal transmission distance, the number of combined carrier cycles N C Possible value is N C =0,1,2,…N. In order to improve the positioning solution speed, combined with the DL-TDOA measurement results d TDOA , for the combined carrier integer ambiguity N C The value range is limited to: N C ∈[N Cmin ,N Cmax ]. For the range of DL-TDOA ranging error ε∈[ε min , ε max ],set up So, N Cmin and N Cmax The calculation method is:

[0029] N Cmin =(d TDOA +ε min -λ′) / λ′, (6)

[0030] N Cmax =(d TDOA +ε max +λ′) / λ′. (7)

[0031] The above are all for BS i The discussion with one of the UE transmission channels is further analyzed below in conjunction with all transmission channels. i The clock is not synchronized with the UE clock. t Indicates BS i The clock difference between UE and BS is c, which represents the speed of light. iThe actual distance d i The following relationship is satisfied:

[0032]

[0033] Among them, BS i The coordinates are (x i ,y i ,z i ), the UE coordinates are (x, y, z), and the combined carrier phase observation value is

[0034] The target equations to be solved are:

[0035]

[0036] Constraints of the equation system:

[0037]

[0038] in, is the combined carrier non-integer cycle distance, is the combined carrier integer ambiguity search value, The UE and BS obtained by DL-TDOA positioning method i The distance [x min ,x max ] is the x-axis coordinate range of the UE, and the same applies to y and z. The value ranges of x, y, and z can be determined in combination with the actual positioning application scenario, which is described in the embodiments of the present invention. t The value range of the clock error is cδ. t When the combined carrier wavelength λ′ exceeds one, the effect is equivalent to the number of combined carrier cycles. Therefore, we can define δ t ∈[0,λ′ / c]. The integer ambiguity after limiting the clock error will be determined in the subsequent search process and will not affect the positioning result. For the above equations with constraints, the known quantities are c, λ′、 ε i 、[x min ,x max ]、[y min ,y max ]、[z min ,z max ] and BS i Coordinate (x i ,y i ,z i ), the unknown quantities to be solved are the UE coordinates (x, y, z) and the distance between UE and BS i The clock difference δ tAmong them, the combined carrier integer ambiguity The value of changes with the whole cycle ambiguity search process. Figure 5 As shown, through multiple layers of cycles Assign a value, and then bring it into the target equation group for solution. When the target equation group finds a solution, the UE coordinates and clock error δ t , combined carrier integer ambiguity Then it is confirmed that the positioning process is completed.

[0039] Compared with existing technologies, the present invention offers the following advantages: It proposes a carrier phase-based fusion positioning method. Leveraging the large bandwidth of 5G communication systems, this method combines subcarriers to increase the equivalent carrier wavelength, reducing the difficulty of resolving integer carrier ambiguities. By combining DL-TDOA and carrier phase measurements, constraint equations are established, and the UE's three-dimensional spatial coordinates are jointly calculated, ultimately achieving high-precision positioning of the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of fusion positioning in an embodiment of the present invention.

[0041] Figure 2 Schematic diagram of an OFDM transmission system in an embodiment of the present invention.

[0042] Figure 3 Schematic diagram of carrier transmission between a base station and user equipment in an embodiment of the present invention.

[0043] Figure 4 This is a flowchart of integer ambiguity search for high-frequency subcarriers and low-frequency subcarriers in an embodiment of the present invention.

[0044] Figure 5 This is a flowchart of the combined carrier integer ambiguity search and joint resolution in an embodiment of the present invention.

[0045] Figure 6 This is a positioning flow chart in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] See also Figures 1 to 6 , which is a high-precision positioning method that integrates DL-TDOA and carrier phase measurement provided in this embodiment, and the specific steps are as follows:

[0047] (1) Determine the location of 5G base stations

[0048] BS i The location of the UE is fixed, and the BS needs to be determined before positioning the UE. i The coordinates (x i ,y i ,z iBS can be obtained through high-precision surveying instruments. i location information, such as total stations, which are widely used in precision engineering surveying fields such as large-scale above-ground buildings and underground tunnel construction.

[0049] (2) Data Collection

[0050] For the DL-TDOA measurement process, BS i At the same time, the downlink positioning reference signal (DL-PRS) is sent. The UE determines the time difference between the UE and the BS based on the arrival time of the DL-PRS signal. i After obtaining the distance difference, the spatial coordinates of the UE are obtained by solving the nonlinear equations. i The location coordinates are known, so the distance between UE and BS can be calculated. i The distance between them is used to calculate the high-precision position coordinates of the UE.

[0051] For the carrier phase measurement process, BS i The UE sends a carrier phase positioning reference signal (C-PRS). As the signal receiving end, the UE down-converts the received signal. The carrier tracking loop processes the down-converted baseband signal and extracts the carrier phase observation value. For each communication link, the carrier phase observation values ​​of the high-frequency carrier and the low-frequency carrier are extracted separately. i A downlink PRS resource set can be configured. The reference signal resource set used for positioning is transmitted periodically, with a minimum transmission period of 4ms and a maximum transmission period of 10240ms. The transmission period is determined based on the positioning delay and the resource usage of the reference signal.

[0052] (3) Integer Ambiguity Search and Joint Resolution

[0053] Integer ambiguity search is performed on the UE side. The integer ambiguity search mainly includes two processes: 1. The integer ambiguity N of the high-frequency subcarrier Hdec , low-frequency subcarrier integer ambiguity N Ldec Search; 2. Combined carrier integer ambiguity N C search.

[0054] The search variable is the number of low-frequency integer subcarriers N Ldec and the number of high-frequency integer subcarriers N Hdec During the search process, N L and N H The values ​​of are all integers. The condition for terminating the integer ambiguity search is: N Ldec ≤N Hdec And abs(d L -d H ) <d CAerr Since UE and BSi There will be a clock error between the UE and the BS, so the carrier phase observation value and the integer ambiguity search value cannot represent the difference between the UE and the BS. i The actual distance between them and the integer ambiguity search value will participate in the high-precision position coordinate solution process of the UE.

[0055] Once the DL-TDOA and carrier phase measurements are determined, a target set of equations is established. Simultaneously, based on the actual application scenario and the DL-TDOA measurement results, constraints are set for the equations, and the UE's three-dimensional spatial coordinates are jointly calculated, ultimately achieving high-precision positioning of the UE.

[0056] Example

[0057] According to the above fusion positioning method based on 5G carrier phase, a wireless communication simulation model is built. The simulation model mainly involves the up-conversion and down-conversion process of the baseband signal. The positioning environment of the present invention is set as an open space with a length of 10m, a width of 10m and a height of 3m. i The coordinates are: BS1 (5, 15, 3), BS2 (15, 15, 3), BS3 (15, 5, 3), BS4 (5, 5, 3), and the UE coordinates are (12, 11, 0). The units of the coordinates are all meters. The UE may be located anywhere in this space. Take the following simulation parameters as an example:

[0058] Parameter Symbol Parameter name Parameter value λ′ Combined carrier wavelength 3.75m <![CDATA[f H ]]> High frequency subcarrier frequency 2GHz <![CDATA[f L ]]> Low frequency subcarrier frequency 1.92GHz M Number of 5G base stations 4 v UE movement speed 0km / h <![CDATA[δ t ]]> <![CDATA[Clock difference between UE and BS i > 3ns <![CDATA[[x min ,x max ]]]> UE x-coordinate value range [5,15] <![CDATA[[y min ,and max ]]]> UE y coordinate value range [5,15] <![CDATA[[z min ,With max ]]]> UE z coordinate value range [-1,3]

[0059] UE coordinates and UE and BS i The clock difference δ t Only used to generate high-frequency subcarrier phase observations Low-frequency subcarrier phase observations Compared with DL-TDOA observations Does not participate in the positioning solution process. Indicates the UE and BS calculated by the DL-TDOA positioning method i The following table shows the distance of i and UE coordinates and clock difference δ t Calculated equivalent observation parameters:

[0060]

[0061]

[0062] Among them, CH i Indicates the UE and BS i The transmission channel, d i Indicates the UE and BS i The actual distance. The value range is During simulation, DL-TDOA observations are simulated by generating random numbers uniformly distributed within this range. For the high-frequency subcarrier integer ambiguity and low-frequency subcarrier integer ambiguity search process, the range error d caused by the carrier phase measurement error is CAerr The calculation method of low-frequency subcarrier phase observation value is the same as that of high-frequency subcarrier phase observation value. The calculation process is:

[0063] 1. Calculate the carrier phase offset caused by the signal transmission distance:

[0064]

[0065] 2. Calculate the high-frequency subcarrier phase offset caused by the clock error.

[0066]

[0067] 3. and Bring in the wireless communication simulation model and start the simulation. After the simulation program is finished, the high-frequency subcarrier phase observation value will be generated.

[0068] After the above parameters are initialized, the position solution is performed. The main difference between the different positioning solution processes is that the DL-TDOA observation values ​​are randomly regenerated. The following table shows the parameters obtained from the two position solutions.

[0069] The parameters obtained from the first position solution are as follows:

[0070]

[0071] The parameters obtained from the second position solution are as follows:

[0072]

[0073]

[0074] It can be seen that when the DL-TDOA observation value When the UE coordinates and the distance between UE and BS change within the specified error range i The clock error can still be calculated with high accuracy. It should be noted that this simulation is mainly used to verify the correctness of the algorithm. i The clock synchronization error between them is not processed, and the default is BS i The clocks are synchronized.

Claims

1. A fusion positioning method based on 5G carrier phase measurement, characterized in that: The system integrates downlink time difference of arrival (DL-TDOA) and carrier phase measurement technologies. Specifically, it uses four 5G base stations (BSs) around the user equipment (UE) to be located to obtain DL-TDOA and carrier phase measurement results, establish constraint equations, and jointly solve the UE's three-dimensional spatial coordinates to ultimately achieve high-precision positioning of the UE. The specific steps are as follows: (1) Coarse positioning based on DL-TDOA; The DL-TDOA positioning method is used to obtain low-precision UE coordinates; four 5G base stations with known locations are deployed around the UE, denoted as BS1, BS2, BS3, and BS4; the UE coordinates are (x, y, z), and the BS i The coordinates are (x i ,y i , z i ), i = {1, 2, 3, 4}; BS1 is used as the reference station, τ 12 The difference between the time it takes for the signal sent by BS1 to reach the UE and the time it takes for the signal sent by BS2 to reach the UE, τ 13 , τ 14 Similarly; τ 12 , τ 13 , τ 14 With BS i And the coordinate position of the UE satisfies the following relationship: Where c represents the speed of light, τ 12 , τ 13 , τ 14 Directly calculate from the measured values, the UE coordinates (x, y, z) are unknown quantities to be determined; the distance between UE and BS i The distance between Expressed as: Among them, the ranging error of DL-TDOA has a mean of 0 and a variance of Normal distribution (2) Carrier Combination By combining the high-frequency and low-frequency subcarriers of the OFDM system to form an equivalent carrier with a longer wavelength, the integer ambiguity of the equivalent carrier is lower at the same distance; The OFDM system divides the transmission channel into multiple mutually orthogonal sub-channels. The data stream of each sub-channel is modulated onto the corresponding sub-carrier for transmission. The transmitting end signal is expressed in the time domain as: Among them, f n is the frequency of the nth subcarrier, N is the number of subcarriers, a n is the baseband data; (3) High-precision position calibration through integer ambiguity search and joint resolution BS i During the carrier transmission process between CH and UE, i Indicates BS i Transmission channel with UE, i = {1, 2, 3, 4}, i represents the BS number; BS i The clock difference with the UE is δ t ;Signal transmission distance d is equal to BS i The actual distance between the UE and the UE; d N Indicates the whole cycle combined carrier distance contained in the signal transmission distance d, d dec is the non-integer combined carrier distance within the signal transmission distance d; is the clock error δ t The distance generated; Due to the existence of clock error, the carrier phase observation value of the UE cannot represent the true value, but the carrier phase observation value that superimposes the clock error and causes the carrier phase to change; Let N L is the number of cycles of the low-frequency subcarrier, N H N is the number of full cycles of the high frequency subcarrier. C is the number of combined carrier cycles, which satisfies N C ∶N L ∶N H =1:3:4 (within a combined carrier wavelength length), the wavelength satisfies λ′=3λ L =4λ H , the frequency satisfies f c ′=f L / 3=f H / 4, and f c ′=f H -f L ; where λ′ is the combined carrier wavelength, λ L is the low-frequency subcarrier wavelength, λ H is the high frequency subcarrier wavelength; The determination of the integer ambiguity is achieved through two processes: (1) the integer ambiguity N of the high frequency subcarrier Hdec and the low-frequency subcarrier integer ambiguity N Ldec Search; (2) Combined carrier integer ambiguity N C search.

2. The fusion positioning method based on 5G carrier phase measurement according to claim 1 is characterized in that The high frequency subcarrier integer ambiguity N in step (3) Hdec and the low-frequency subcarrier integer ambiguity N Ldec Search, the specific process is: The condition for terminating the integer ambiguity search is: N Ldec ≤N Hdec And abs(d Ldec -d Hdec )<d CAerr ;d Ldec is the phase measurement value of the low-frequency subcarrier and N Ldec Calculated signal transmission distance, d Hdec is the phase measurement value of the high frequency subcarrier and N Hdec Calculated signal transmission distance; d CAerr is the distance error caused by the carrier phase measurement error; let the carrier phase observation values ​​of the low-frequency subcarrier and the high-frequency subcarrier be and d Ldec with d Hdec Calculated by equations (4) and (5); after the high-frequency subcarrier integer ambiguity search and the low-frequency subcarrier integer ambiguity search are completed, d Ldec d Hdec 、N Hdec 、N Ldec The values ​​of are determined; According to the above search d Ldec d Hdec , the distance d of the non-integer part of the combined carrier dec Then it is determined that at this time d dec Take the average of the two and define it as d dec =(d Ldec +d Hdec ) / 2.

3. The fusion positioning method based on 5G carrier phase measurement according to claim 2 is characterized in that The combined carrier integer ambiguity N in step (3) C Search, the specific process is: Combined with DL-TDOA measurement results TDOA , for the combined carrier integer ambiguity N C The value range is limited to: N C ∈[N Cmin , N Cmax ]; For the range of DL-TDOA ranging error ε∈[ε min , ε max ],set up So, N Cmin and N Cmax The calculation method is: N Cmin =(d TDOA +e min -λ′) / λ′, (6) N Cmax =(d TDOA +e max +λ′) / λ′ (7) Because BS i The clock is not synchronized with the UE clock. t Indicates BS i The clock difference between UE and BS is c, which represents the speed of light. i The actual distance d i The following relationship is satisfied: Among them, BS i The coordinates are (x i ,y i , z i ), the UE coordinates are (x, y, z), and the combined carrier phase observation value is The target equations to be solved are: Constraints of the equation system: x∈[x min x max ],y∈[y min y max ],z∈[z min ,z max ],δ t ∈[0,λ′ / c], (10) in, is the combined carrier non-integer cycle distance, is the combined carrier integer ambiguity search value, The UE and BS obtained by DL-TDOA positioning method i The distance [x min , x max ] is the x-axis coordinate range of the UE, and the same applies to y and z. The value ranges of x, y, and z can be determined based on the actual positioning application scenario. For the above set of equations with constraints, the known quantities are c, λ′, ε i 、[x min , x max ]、[y min ,y max ]、[z min , z max ] and BS i Coordinate (x i ,y i , z i ), the unknown quantities to be solved are the UE coordinates (x, y, z) and the distance between UE and BS i The clock difference δ t ; Among them, the combined carrier integer ambiguity The value of changes with the whole cycle ambiguity search process; through multiple layers of loops Assign a value, and then bring it into the target equation group for solution; when the target equation group finds a solution, the UE coordinates and clock error δ t , combined carrier integer ambiguity Then it is confirmed and the positioning process is completed.

4. The fusion positioning method based on 5G carrier phase measurement according to claim 3 is characterized in that For a 5G positioning system with a transmission bandwidth of at least 80 MHz, let the carrier center frequency be f c =1.96GHz, select frequency as f L =f c -40MHz low-frequency subcarrier, frequency f H =f c +40MHz high frequency subcarrier, these two subcarriers are combined into a frequency of f c ′=f H -f L =80MHz equivalent carrier; its combined carrier wavelength is 3.75m; DL-TDOA measurement error is less than 3.75m, which indicates that the UE and BS obtained by the DL-TDOA positioning method i The distance error between BS i The clock error between the system and the UE is used as an unknown in the calculation. By combining DL-TDOA and carrier phase measurements, constraint equations are established to jointly calculate the UE's three-dimensional spatial coordinates, thereby achieving target positioning.

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