CN116347352A - Fusion positioning method based on 5G carrier phase - Google Patents
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Abstract
The invention belongs to the technical field of mobile communication, and particularly relates to a fusion positioning method based on a 5G carrier phase. The invention merges DL-TDOA and carrier phase measurement technology; at least four 5G Base Stations (BSs) are deployed within an accessible range of the UE. The BS transmits an OFDM modulated positioning signal to the UE, and a DL-TDOA positioning method is utilized to calculate the low-precision space position of the UE at the UE end so as to obtain the linear distance between the UE and each BS; and calculating carrier phases by using the positioning signals of each BS at the UE end, establishing a constraint equation by combining the distances obtained by the DL-TDOA, solving the three-dimensional space coordinates of the UE, and realizing high-precision positioning of the UE. The invention utilizes the characteristic of 5G large bandwidth, improves the equivalent carrier wave length by combining the subcarriers, and reduces the solving difficulty of the carrier integer ambiguity.
Description
Technical Field
The invention belongs to the technical field of mobile communication, and particularly relates to a high-precision positioning method integrating DL-TDOA and carrier phase measurement.
Background
Along with the rapid development of information technology, high-precision positioning technology is focused on various industries, such as super intelligent business, intelligent manufacturing, automatic driving and other typical positioning application scenes. The traditional GNSS positioning technology is widely applied to outdoor high-precision positioning scenes, wherein RTK (Real Time Kinematic) carrier phase difference technology can provide centimeter-level positioning precision. However, for indoor high-precision positioning application scenarios, GNSS signal transmission is limited, and no relatively mature solution exists at present.
The 5G technology has the advantages of high bandwidth, high carrier frequency, multiple antennas, high network density and the like, and the coverage integration of the 5G technology brings new possibility for realizing indoor high-precision positioning. The existing 5G positioning scheme includes: 1. downlink Time difference of Arrival positioning (Downlink Time Difference of Arrival, DL-TDOA), 2. Angle of Arrival (AOA), 3. Round Trip Time (RTT). In these positioning schemes, DL-TDOA may provide meter level positioning accuracy, but this is not yet sufficient to achieve high accuracy positioning of the target. The carrier phase positioning technology based on the carrier phase observed quantity has good effect in a satellite positioning system, and has important significance in the mobile communication system by applying the carrier phase positioning technology.
The third generation partnership project (3rd Generation Partnership Project,3G PP) has established the first project of the 5G-Advanced first standard version Rel-18, which contains carrier phase location technology for high precision location scenarios, but only relevant standards have been established at this stage. Therefore, there is no mature solution for 5G high-precision positioning, and improving the positioning precision of a 5G communication system is a problem to be solved at present.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a high-precision fusion positioning method based on 5G carrier phase measurement.
The fusion positioning method based on 5G carrier phase measurement, provided by the invention, fuses a downlink arrival time difference (DL-TDOA) and a carrier phase measurement technology to perform high-precision positioning; and particularly, four 5G base stations with good geometric distribution around the UE (User Equipment) are utilized to acquire DL-TDOA and carrier phase measurement results, a constraint equation is established, three-dimensional space coordinates of the UE are jointly solved, and finally high-precision positioning of the UE is realized. The method comprises the following specific steps:
coarse DL-TDOA-based positioning
The DL-TDOA positioning is realized by detecting the time difference of the signals sent by different BSs to reach the UE, and the positioning is not directly performed by using the absolute time of signal transmission, so that the positioning error caused by the clock synchronization problem between the UE and the BS can be effectively reduced. In the three-dimensional DL-TDOA positioning method, four 5G base stations are arranged around the UE and marked as BS 1 、BS 2 、BS 3 、BS 4 . UE coordinates (x, y, z), BS i The coordinates are (x) i ,y i ,z i ) I= {1,2,3,4}. With BS 1 As reference station τ 12 Representing BS 1 Time taken for transmission signal to reach UE and BS 2 The difference in time taken for the transmitted signal to reach the UE τ 13 、τ 14 And the same is true. τ 12 、δ 13 、τ 14 With BS i And the coordinate position of the UE satisfies the following relationship:
wherein c represents the speed of light, τ 12 、δ 13 、τ 14 The UE coordinates (x, y, z) are unknowns to be solved for, which can be calculated directly from the measurements. UE and BS i Distance between
Expressed as:
wherein the DL-TDOA ranging error obeys a mean value of 0 and a variance of 0
Normal distribution->
General DL-TDOA positioningThe precision is in the order of meters or sub meters.
(II) Carrier combination
In addition to DL-TDOA measurements, the UE is from the BS i Another basic measurement value obtained in the transmitted signal is the carrier phase; the carrier phase measurement precision of the current receiver on the non-whole circumference part can reach millimeter magnitude, but the positioning is inaccurate due to the fact that the whole circumference number of the carrier phase cannot be accurately estimated, and the solving of the whole circumference ambiguity becomes the key of a high-precision positioning system. The invention forms the equivalent carrier wave with longer wavelength by combining the high-frequency subcarrier and the low-frequency subcarrier of the OFDM system, and the integer ambiguity of the equivalent carrier wave is lower under the condition of the same distance. According to the invention, two antennas are not required to be used for respectively transmitting two carriers with different frequencies, more variables are introduced by multiple antennas, and the realization of high-precision positioning becomes more difficult.
The OFDM system divides a transmission channel into a plurality of mutually orthogonal sub-channels, and the data stream of each sub-channel is modulated onto a corresponding sub-carrier for transmission, as shown in fig. 2. The sender signal can be expressed in the time domain as:
wherein f n For the frequency of the nth subcarrier, N is the number of subcarriers, a n Is baseband data.
For a communication system with a transmission bandwidth of at least 80MHz, the carrier center frequency is set to be f c =1.96 GHz, the selected frequency is f L ＝f c -40MHz low frequency subcarrier with frequency f H ＝f c +40MHz high frequency subcarrier. The two sub-carriers can be combined into a frequency f c ′ ＝f H -f L Equivalent carrier wave of 80MHz with wavelength lambda ′ =3.75m. Within the same signal transmission distance, the whole-cycle ambiguity of the combined carrier wave is greatly reduced.
(III) performing high-precision position calibration through whole-cycle ambiguity searching and joint calculation
BS i Signaling with UEThe number transmission diagram is shown in figure 3, CH i Representing BS i With the transmission channel of the UE, i= {1,2,3,4}, i denotes BS sequence number. BS (base station) i The clock difference with the UE is delta t . The signal transmission distance d is equal to BS i Actual distance from the UE. d, d N Represents the total combined carrier distance d contained in the range of the signal transmission distance d dec The carrier distances are combined for non-whole cycles within the range of the signal transmission distance d.
Is the clock difference delta t The resulting distance. The carrier phase observations of the UE cannot represent true values due to the presence of clock differences, but are superimposed with carrier phase observations that result in carrier phase changes. N in the figure L For the whole cycle number of the low-frequency subcarrier, N H For the whole cycle number of high-frequency sub-carrier, N C For combining the whole number of cycles of the carrier, they satisfy N C :N L :N H =1:3:4 (within one combined carrier wavelength length), the wavelengths need to satisfy λ' =3λ L ＝4λ H The frequency satisfies f c ′＝f L /3＝f H /4, and f c ′＝f H -f L . Wherein lambda' is the combined carrier wavelength, lambda L Lambda is the wavelength of the low frequency subcarrier H Is a high frequency subcarrier wavelength. In combination with the actual situation, if the high frequency subcarrier frequency f H =2 GHz, low frequency subcarrier frequency f L =1.92 GHz. At this time, the carrier frequency f is combined c ′＝f H -f L ＝80MHz，N C :N L :N H =1:24:25 (within one combined carrier wavelength length).
The determination of the integer ambiguity is one of the keys for realizing high-precision positioning for the UE, and is mainly realized through two processes: (1) High frequency subcarrier integer ambiguity N Hdec Low frequency subcarrier integer ambiguity N Ldec Searching; (2) Combined carrier integer ambiguity N C Searching.
(1) High frequency subcarrier integer ambiguity N Hdec Low frequency subcarrier integer ambiguity N Ldec Searching;
first, combine FIG. 3 and FIG.Introduction to N Hdec And N Ldec Is a search process of (a). FIG. 4 mainly includes variable updating and condition determination, wherein the searched variable is N number of low-frequency whole-cycle subcarriers Ldec And the number of high-frequency whole-cycle subcarriers N Hdec . Wherein N is Ldec And N Hdec Are integers. N (N) Hdec N Ldec The maximum value is calculated by lambda'/lambda respectively H And lambda'/lambda 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 whole cycle number of the low-frequency subcarrier is N Ldec Always less than or equal to the total number of cycles N of the high frequency subcarrier Hdec . The phase change between the high frequency subcarrier and the low frequency subcarrier is different for the same signal transmission path, but the signal transmission distance d is estimated from the phase change amount of the high frequency subcarrier or the low frequency subcarrier dec Is identical, therefore, in the absence of errors in the carrier phase measurement, d dec ＝d Ldec ＝d Hdec . Considering that there may be some error in the carrier phase measurement process, the condition for the end of the integer ambiguity search is: n (N) Ldec ≤N Hdec And abs (d) Ldec -d Hdec )<d CAerr 。d Ldec Based on low frequency subcarrier phase measurements
N Ldec And calculating the signal transmission distance. d, d Hdec For measuring value according to high frequency subcarrier phase>
N Hdec And calculating the signal transmission distance. d, d CAerr Is a distance error caused by a carrier phase measurement error. Setting the carrier phase observation values of the low frequency sub-carrier and the high frequency sub-carrier as +.>
And->
d Ldec And d Hdec Can be represented by (4), (5)And (5) calculating to obtain the product. D after the search of the high-frequency subcarrier integer ambiguity and the low-frequency subcarrier integer ambiguity is completed Ldec 、d Hdec 、N Hdec 、N Ldec Is determined.
According to d searched out above Ldec 、d Hdec Distance d of non-whole circumference part of combined carrier dec And then determining. Ideally, d dec ＝d Ldec ＝d Hdec . In actual case, however, d Ldec Will not be in contact with d Hdec Completely agree with d dec Average of the two, defined as d dec ＝(d Ldec +d Hdec )/2。
(2) Combined carrier integer ambiguity N C Searching;
combining carrier wave whole cycle number N under the condition of unknown signal transmission distance C May take the value N C =0, 1,2, … N. To increase the positioning resolving speed, combining the DL-TDOA measurement result d TDOA For combined carrier integer ambiguity N C Defining the range of values of (2): n (N) C ∈[N Cmin ,N Cmax ]. The value range epsilon for DL-TDOA range error epsilon min ，ε max Setting of
Thus N Cmin And N Cmax The calculation mode of (a) is as follows:
N Cmin ＝(d TDOA +ε min -λ′)/λ′， (6)
N Cmax ＝(d TDOA +ε max +λ′)/λ′。 (7)
all of the above are for BS i The discussion with one of the UE transport channels is further analyzed in connection with all transport channels below. In general, BS i The clock is not synchronous with the UE clock, delta is used t Representing BS i Clock difference between the UE and the clock, c represents the speed of light, and the UE and the BS i Is the actual distance d of (2) i The following relationship is satisfied:
wherein the BS i The coordinates are (x) i ,y i ,z i ) The UE coordinates are (x, y, z) and the combined carrier phase observations are
The set of target equations to be solved is:
constraint conditions of the equation set:
wherein,,
for combined carrier non-whole circumference distance, +.>
Searching value for combined carrier integer ambiguity, < >>
Is UE and BS obtained by DL-TDOA positioning method i Distance of [ x ] min ,x max ]The coordinate ranges of the X-axis of the UE and the y and z are the same. The value ranges of x, y and z can be determined by combining the actual positioning application scene, and in the embodiment of the invention, the method comprises the following steps ofAnd (5) related description. For the clock difference delta t When the signal transmission distance cdelta corresponding to the clock error is within the range of the value of (a) t When more than one combined carrier wavelength lambda' is used, the effect is equivalent to the total number of cycles of the combined carrier>
Thus can define delta t ∈[0,λ′/c]. The integer ambiguity after defining the clock bias will be determined in the subsequent search process and will not affect the positioning result. For the above system of equations with constraints, the known quantity is c,
λ′、/>
ε i 、[x min ,x max ]、[y min ,y max ]、[z min ,z max ]BS (base station) i Coordinates (x) i ,y i ,z i ) The unknown quantity to be solved is the UE coordinates (x, y, z), UE and BS i Clock difference delta between t . Wherein, the combined carrier is whole-cycle ambiguity +.>
The value of (2) is varied with the whole-cycle ambiguity search process. As shown in FIG. 5, the circulation is +.>
And assigning values, and then bringing the values into a target equation set for calculation. When the target equation set finds the solution, the UE coordinates and the clock difference delta t Combined carrier integer ambiguity +.>
And then determining that the positioning process is completed.
Compared with the prior art, the invention has the beneficial effects that: the invention provides a fusion positioning method based on carrier phase. By utilizing the characteristic of large bandwidth of the 5G communication system, the equivalent carrier wave length is improved by combining the subcarriers, and the solving difficulty of the whole-cycle ambiguity of the carriers is reduced. And combining the DL-TDOA and the carrier phase measurement value, establishing a constraint equation, jointly solving the three-dimensional space coordinate of the UE, and finally realizing high-precision positioning on the UE.
Drawings
FIG. 1 is a diagram of a fusion localization scheme in an embodiment of the present invention.
Fig. 2 is a schematic diagram of an OFDM transmission system according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of carrier transmission between a base station and a ue in an embodiment of the present invention.
Fig. 4 is a flowchart of the integer ambiguity search for high frequency subcarriers and low frequency subcarriers in an embodiment of the present invention.
Fig. 5 is a flowchart of combined carrier integer ambiguity search and joint solution according to an embodiment of the present invention.
Fig. 6 is a positioning flow chart in an embodiment of the invention.
Detailed Description
Referring to fig. 1 to 6, a high-precision positioning method for fusing DL-TDOA and carrier phase measurement provided in this embodiment specifically includes the following steps:
first, determining 5G base station position
BS i Is fixed, a BS needs to be determined before locating the UE i Coordinates (x) i ,y i ,z i ). BS acquisition by high precision mapping instrument i Such as total stations widely used in the field of precision engineering measurement of large-scale buildings on the ground, underground tunnel construction and the like.
(II) data acquisition
For DL-TDOA measurement procedure, BS i And simultaneously transmitting a downlink positioning reference signal (DL-PRS). Determining UE and BS according to time difference of DL-PRS signal arrival i The distance difference between them. And after the distance difference is obtained, the space coordinates of the UE are obtained by solving a nonlinear equation set. Due to the BS according to the invention i The location coordinates are known, so that the UE and the BS can be calculated i Distance between the two, the distance value participates in high-precision position coordinate calculation of the UEAnd (5) processing.
For carrier phase measurement procedure, BS i A carrier phase positioning reference signal (C-PRS) is transmitted. As a signal receiving end, the UE down-converts the received signal. And processing the down-converted baseband signal through a carrier tracking loop to extract a carrier phase observation value. For each communication link, carrier phase observations of the high frequency carrier and the low frequency carrier are extracted, respectively. BS (base station) i One downlink PRS resource set may be configured, and a reference signal resource set for positioning may be transmitted in a periodic manner, with a minimum transmission period of 4ms and a maximum transmission period of 10240ms. The transmission period can be determined according to the positioning delay and the condition that the reference signal occupies resources.
(III) integer ambiguity search and joint resolution
The whole-cycle ambiguity search is carried out at the UE end, and mainly comprises two processes: 1. high frequency subcarrier integer ambiguity N Hdec Integer ambiguity N for low frequency subcarrier Ldec Searching; 2. combined carrier integer ambiguity N C Searching.
The variable of the search is N number of low-frequency whole-cycle subcarriers Ldec And the number of high-frequency whole-cycle subcarriers N Hdec . In the searching process, N L And N H The values of (2) are integers. The conditions for the termination of the integer ambiguity search are: n (N) Ldec ≤N Hdec And abs (d) L -d H )<d CAerr . Due to UE and BS i There is a clock skew between the carrier phase observations and the integer ambiguity search values, which are not indicative of UE and BS i The actual distance between the two, the whole-cycle ambiguity search value will participate in the high-precision position coordinate calculation process of the UE.
And after the DL-TDOA measurement value and the carrier phase measurement value are determined, establishing a target equation set to be solved. Meanwhile, by combining an actual application scene and a DL-TDOA measurement result, constraint conditions of an equation set are set, three-dimensional space coordinates of the UE are jointly solved, and finally high-precision positioning is achieved for the UE.
Examples
According to the fusion positioning method based on the 5G carrier phase, a wireless communication simulation model is built, and the simulation model mainly relates to a baseUp-conversion and down-conversion processes of the band signal. Setting the positioning environment of the invention as an open space with the length of 10m, the width of 10m and the height of 3m, BS i The coordinates are: BS (base station) 1 (5,15,3)、BS 2 (15,15,3)、BS 3 (15,5,3)、BS 4 (5, 3), the UE coordinates are (12,11,0), wherein the coordinates are in m. The UE may be in any position in the space. Taking the following simulation parameters as an example:
| parameter symbol | Parameter name | Parameter value |
| λ′ | Combined carrier wave length | 3.75m |
| f H | High frequency subcarrier frequency | 2GHz |
| f L | Low frequency subcarrier frequency | 1.92GHz |
| M | Number of 5G base stations | 4 |
| v | UE movement speed | 0km/h |
| δ t | UE and BS i Is of the clock difference of (1) | 3ns |
| [x min ,x max ] | UE x coordinate range | [5,15] |
| [y min ,y max ] | UE y coordinate range | [5,15] |
| [z min ,z max ] | UE z coordinate range of values | [-1,3] |
Coordinates of UE, and UE and BS i Is delta of the clock difference t For generating high frequency subcarrier phase observations only
Low frequency subcarrier phase observations +.>
With DL-TDOA observations->
Does not participate in the positioning calculation process. Wherein (1)>
Representing UE and BS calculated by DL-TDOA positioning method i Is a distance of (3). The following table shows the transmission through BS i Coordinates and clock difference delta from UE t Calculated etcEffective observation parameters:
wherein CH is i Representing UE and BS i D i Representing UE and BS i Is a function of the actual distance of the sensor. Setting up
The value range of (2) is +.>
In simulation, DL-TDOA observations are simulated by generating random numbers uniformly distributed in the range>
For the searching process of the high-frequency subcarrier integer ambiguity and the low-frequency subcarrier integer ambiguity, the distance error d caused by the carrier phase measuring error CAerr Set to 6mm. The low frequency subcarrier phase observations calculation method is the same as the high frequency subcarrier phase observations calculation method for high frequency subcarrier phase observations +.>
The calculation process is as follows:
1. calculating carrier phase offset caused by signal transmission distance:
2. the high frequency subcarrier phase offset caused by the clock difference is calculated.
3. Will be
And->
The simulation is carried into a wireless communication simulation model and started, and after the operation of a simulation program is finished, a high-frequency subcarrier phase observation value is generated +.>
And after the initialization of the parameters is completed, performing position calculation. The main difference for the different location solutions is that the observations of DL-TDOA are re-randomly generated. The following table shows the parameters obtained from the two position solutions.
The parameters obtained by the first position calculation are as follows:
the parameters obtained by the second position calculation are as follows:
it can be seen that when DL-TDOA observations are made
When the specified error range is changed, the UE coordinates, the UE and the BS i The clock difference of (2) can still be solved with higher accuracy. It should be noted that the simulation is mainly used for checking algorithm correctness, and for BS i Clock synchronization errors between the two are not processed, and BS is defaulted i The clocks are synchronized.
Claims (4)
1. A fusion positioning method based on 5G carrier phase measurement is characterized in that a downlink time difference of arrival (DL-TDOA) and a carrier phase measurement technology are fused; specifically, four 5G Base Stations (BS) around User Equipment (UE) to be positioned are utilized to acquire DL-TDOA and carrier phase measurement results, a constraint equation is established, three-dimensional space coordinates of the UE are jointly solved, and finally high-precision positioning of the UE is realized; the method comprises the following specific steps:
coarse DL-TDOA-based positioning;
acquiring low-precision UE coordinates by adopting a DL-TDOA positioning method; four 5G base stations with known positions are deployed around the UE and marked as BS 1 、BS 2 、BS 3 、BS 4 The method comprises the steps of carrying out a first treatment on the surface of the UE coordinates (x, y, z), BS i The coordinates are (x) i ，y i ，z i ) I= {1,2,3,4}; with BS 1 As reference station τ 12 Representing BS 1 Time taken for transmission signal to reach UE and BS 2 The difference in time taken for the transmitted signal to reach the UE τ 13 、τ 14 And the same is done; τ 12 、τ 13 、τ 14 With BS i And the coordinate position of the UE satisfies the following relationship:
wherein c represents the speed of light, τ 12 、τ 13 、τ 14 Directly calculating from the measured values, wherein the UE coordinates (x, y, z) are unknown quantities to be solved; UE and BS i Distance between
Expressed as:
wherein the ranging error of DL-TDOAObeying mean value 0, variance 0
Normal distribution->
(II) Carrier combination
By combining the high-frequency sub-carrier and the low-frequency sub-carrier of the OFDM system, an equivalent carrier with longer wavelength is formed, and the integer ambiguity of the equivalent carrier is lower under the condition of the same distance;
the OFDM system divides a transmission channel into a plurality of mutually orthogonal sub-channels, and a data stream of each sub-channel is modulated to a corresponding sub-carrier for transmission, and a signal at a transmitting end is expressed as:
wherein f n For the frequency of the nth subcarrier, N is the number of subcarriers, a n Is baseband data;
(III) performing high-precision position calibration through whole-cycle ambiguity searching and joint calculation
BS i In the carrier transmission process with UE, CH i Representing BS i With the transmission channel of the UE, i= {1,2,3,4}, i represents BS sequence number; BS (base station) i The clock difference with the UE is delta t The method comprises the steps of carrying out a first treatment on the surface of the The signal transmission distance d is equal to BS i Actual distance from UE; d, d N Represents the total combined carrier distance d contained in the range of the signal transmission distance d dec Combining carrier distances for non-whole cycles within a signal transmission distance d range;
is the clock difference delta t The distance generated; due to the existence of the clock error, the carrier phase observed value of the UE cannot represent a true value, but is a carrier phase observed value superimposed with the clock error and resulting in a carrier phase change;let N be L For the whole cycle number of the low-frequency subcarrier, N H For the whole cycle number of high-frequency sub-carrier, N C For combining the whole number of cycles of the carrier, they satisfy N C ∶N L ∶N H =1:3:4 (within one 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 The method comprises the steps of carrying out a first treatment on the surface of the Wherein lambda' is the combined carrier wavelength, lambda L Lambda is the wavelength of the low frequency subcarrier H Is a high frequency subcarrier wavelength;
the determination of the integer ambiguity is achieved by two processes: (1) High frequency subcarrier integer ambiguity N Hdec Low frequency subcarrier integer ambiguity N Ldec Searching; (2) Combined carrier integer ambiguity N C Searching.
2. The method of fusion positioning based on 5G carrier phase measurement according to claim 1, wherein the high frequency subcarrier integer ambiguity N in step (three) Hdec Low frequency subcarrier integer ambiguity N Ldec The specific process of searching is as follows:
the conditions for the termination of the integer ambiguity search are: n (N) Ldec ≤N Hdec And abs (d) Ldec -d Hdec )＜d CAerr ；d Ldec Based on low frequency subcarrier phase measurements
N Ldec Calculated signal transmission distance d Hdec For measuring value according to high frequency subcarrier phase>
N Hdec The calculated signal transmission distance; d, d CAerr Distance errors caused by carrier phase measurement errors; setting the carrier phase observation values of the low frequency sub-carrier and the high frequency sub-carrier as +.>
And->
d Ldec And d Hdec Calculated by formulas (4) and (5); d after the search of the high-frequency subcarrier integer ambiguity and the low-frequency subcarrier integer ambiguity is completed Ldec 、d Hdec 、N Hdec 、N Ldec The values of (2) are all determined;
according to d searched out above Ldec 、d Hdec Distance d of non-whole circumference part of combined carrier dec Then confirm, at this time d dec Average of the two, defined as d dec ＝(d Ldec +d Hdec )/2。
3. The method of fusion positioning based on 5G carrier phase measurement according to claim 2, wherein in step (iii), the combined carrier integer ambiguity N C The specific process of searching is as follows:
combining DL-TDOA measurement d TDOA For combined carrier integer ambiguity N C Defining the range of values of (2): n (N) C ∈[N Cmin ，N Cmax ]The method comprises the steps of carrying out a first treatment on the surface of the The value range epsilon for DL-TDOA range error epsilon min ，ε max ]Setting up
Thus N Cmin And N Cmax The calculation mode of (a) is as follows:
N Cmin ＝(d TDOA +ε min -λ′)/λ′， (6)
N Cmax ＝(d TDOA +ε max +λ′)/λ′ (7)
due to BS i The clock is not synchronous with the UE clock, delta is used t Representing BS i Clock difference between the UE and the clock, c represents the speed of light, and the UE and the BS i Is the actual distance d of (2) i The following relationship is satisfied:
wherein the BS i The coordinates are (x) i ，y i ，z i ) The UE coordinates are (x, y, z) and the combined carrier phase observations are
The set of target equations to be solved is:
constraint conditions of the equation set:
x∈[x min ，x max ]，y∈[y min ，y max ]，z∈[z min ，z max ]，δ t ∈[0，λ′/c]， (10)
wherein,,
for combined carrier non-whole circumference distance, +.>
Searching value for combined carrier integer ambiguity, < >>
Is UE and BS obtained by DL-TDOA positioning method i Distance of [ x ] min ，x max ]The coordinate range of the X-axis of the UE, and y and z are the same; the value ranges of x, y and z can be determined by combining with the actual positioning application scene;
for the above system of equations with constraints, the known quantity is c,
λ′、/>
ε i 、[x min ，x max ]、[y min ，y max ]、[z min ，z max ]BS (base station) i Coordinates (x) i ，y i ，z i ) The unknown quantity to be solved is the UE coordinates (x, y, z), UE and BS i Clock difference delta between t The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the combined carrier is whole-cycle ambiguity +.>
The value of (2) is changed along with the whole-cycle ambiguity searching process; by multilayer circulation +.>
Assigning values, and then carrying out calculation by taking the values into a target equation set; when the target equation set finds the solution, the UE coordinates and the clock difference delta t Combined carrier integer ambiguity +.>
And then determining, namely finishing the positioning process.
4. A fused positioning method based on 5G carrier phase measurement according to claim 3, wherein for a 5G positioning system with a transmission bandwidth of at least 80MHz, a carrier center frequency is set to be f c =1.96 GHz, the selected frequency is f L ＝f c -40MHz low frequency subcarrier with frequency f H ＝f c +40MHz high frequency subcarrier, the two subcarriers being combined to a frequency f c ′＝f H -f L Equivalent carrier wave of=80 MHz; the combined carrier wave wavelength is 3.75m; the DL-TDOA measurement error is less than 3.75m, and the error represents the UE and the BS obtained by adopting the DL-TDOA positioning method i A distance error between them; BS (base station) i The clock error between the UE and the UE is used as an unknown number to participate in the calculation; and combining the DL-TDOA and the carrier phase measurement value to establish a constraint equation, and jointly solving the three-dimensional space coordinate of the UE so as to realize the target positioning.
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