TDOA-fdof combined positioning method based on lte signals

Abstract

The application belongs to the technical field of radar signal processing, and particularly relates to a TDOA-FDOA joint positioning method based on an LTE signal. The method comprises the following steps: step one, constructing a TDOA-FDOA joint positioning scene based on an LTE signal; step two, determining an initial target state by a least square method under the TDOA-FDOA joint positioning scene based on the LTE signal; and step three, accurately solving the position and speed of the target by a conjugate gradient algorithm according to the initial target state. The TDOA-FDOA joint positioning method based on the LTE signal can utilize rich LTE signals in an external environment to accurately determine the position and speed information of the target, has low operation complexity, low memory demand, and strong robustness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar signal processing, and particularly relates to a TDOA-FDOA joint positioning method based on an LTE signal. BACKGROUND

[0002] Target tracking first needs to determine the initial position of the target, and the use of external radiation source positioning technology can effectively hide the radar of our side in electronic warfare, so that the radar of our side has better radio frequency stealth performance. In terms of signals, the signals irradiated by the external radiation source mainly include frequency modulation broadcast, television signals, GSM, CDMA and LTE communication signals, wherein the LTE signal refers to the mobile communication signal used by the 4th generation communication technology (4G). It is the long-term evolution of the Universal Mobile Telecommunications System (UMTS) technical standard formulated by the 3rd Generation Partnership Project (3GPP) organization, and is a kind of communication signal based on Orthogonal Frequency Division Multiplexing (OFDM) modulation mode, and has two transmission modes of Time Division Duplex (TDD) and Frequency Division Duplexing (FDD). The TDD mode refers to that the uplink and downlink share the same frequency band resource, and use different non-overlapping time slot resources. In contrast, the FDD mode refers to that the uplink and downlink use different frequency band resources. Since the frequency band resource used by the TDD mode LTE signal is the same, it is not conducive to clearly detect the echo information of the target on the Doppler shift, and it also increases the difficulty of obtaining the frequency shift information of the signal. In addition, the LTE signal transmitting base station is rich, has a natural cooperative detection advantage, can effectively improve the target detection capability, and has a wider frequency band bandwidth, faster data transmission speed and higher distance resolution compared with other signals.

[0003] In the algorithm for positioning a target by means of a third-party external radiation source, the time delay (TDOA) information of the echo signal and the direct wave signal is often applicable to fixed target positioning; when a moving target is positioned, the TDOA and frequency difference of arrival (FDOA) information are contained in the measurement information, and through joint TDOA-FDOA observation information, not only the position estimation of the target can be obtained, but also the speed estimation can be obtained, and therefore more accurate target state information can be obtained. From a technical point of view, the direction of arrival-based positioning system is relatively common, such as angle measurement cross positioning and single station angle measurement positioning, but is relatively susceptible to noise, resolution and the like, and has low reliability. Since the TDOA and FDOA information are closely related and have high positioning accuracy, the TDOA-FDOA joint is often applied to target positioning. At present, more experts and scholars study the positioning of a mobile radiation source by using TDOA-FDOA information, but in the single station multi-LTE signal radiation source scene, how to position a moving target has not been reported.

[0004] Therefore, it is desirable to have a technical solution to overcome or at least alleviate at least one of the aforementioned deficiencies of the prior art. SUMMARY

[0005] The purpose of the present application is to provide a TDOA-FDOA joint positioning method based on an LTE signal to solve at least one problem existing in the prior art.

[0006] The technical solution of the present application is:

[0007] A TDOA-FDOA joint positioning method based on an LTE signal, comprising:

[0008] Step one, constructing a TDOA-FDOA joint positioning scene based on an LTE signal;

[0009] Step two, determining an initial target state by a least square method in the TDOA-FDOA joint positioning scene based on an LTE signal;

[0010] Step three, accurately solving the position and speed of the target by a conjugate gradient algorithm according to the initial target state.

[0011] In at least one embodiment of the present application, in step one, the TDOA-FDOA joint positioning scene based on an LTE signal is constructed, comprising:

[0012] Suppose that there are N external radiation sources and an observation point in a three-dimensional space, the external radiation sources emit LTE signals to the observation station through the target to form echo signals, and at the same time, the external radiation sources emit radiation signals to the observation station to form direct wave signals, and the target is positioned by observing the TDOA and FDOA information.

[0013] In at least one embodiment of this application, step two, in a TDOA-FDOA joint positioning scenario based on LTE signals, determines the initial target state using the least squares method, including:

[0014] Let the distance R between the target and the observation station be and the velocity be... Represented as:

[0015] R = ||u||2

[0016]

[0017] In the formula,

[0018] u = (x, y, z) T

[0019]

[0020] Building about Quadratic equation of two variables:

[0021]

[0022] In the formula, (·) T This indicates transpose, where A1, B1, and C1 are respectively:

[0023]

[0024] Among them, s k =(x k ,y k ,z k ) T (k = 1, 2, ..., N) represent the locations of the external radiation sources. Let r be the distance between the external radiation source k and the observation station. k It is the observed value of the path difference between the direct wave signal and the echo signal of the external radiation source k;

[0025] R and R are calculated by combining formulas (1) and (2).

[0026] R and Substitute into the likelihood function:

[0027] X = (D T D) -1 D T B

[0028] In the formula,

[0029]

[0030] Where O is the zero matrix;

[0031] Calculate the initial solution X0 that maximizes the likelihood function.

[0032] In at least one embodiment of this application, R and are calculated by combining formulas (1) and (2). include:

[0033] Let R be a positive real number, and let The principle for choosing the value of R is:

[0034] When Δ < 0, R can only have complex roots:

[0035] like but

[0036] like Then R = 0;

[0037] When △≥0 R Obtained separately and / or

[0038] if as well as If one of them is a positive root, then the positive root is retained;

[0039] if as well as If all are positive roots, then all should be retained for the time being;

[0040] if as well as If all roots are negative, then R = 0;

[0041] The distance between the target and the observation station is calculated using formula (2). R Substitute it into the formula (1) regarding In the equation, the coefficients A2, B2, and C2 are obtained as follows:

[0042]

[0043] In the formula,

[0044]

[0045] In formula (1) These are the observed values ​​of the difference in the rate of change of the path length of the direct wave signal and the echo signal from the external radiation source k. Represented as:

[0046]

[0047] when as well as When both are positive roots, calculate R and

[0048] In at least one embodiment of the present application, in step three, the position and velocity of the target are accurately solved by the conjugate gradient algorithm according to the initial target state, including:

[0049] S31, initialize parameters, including: setting the iteration number as l=0, the running error as 0<ε<<1, and the initial gradient direction as

[0050] The calculation formula of the gradient direction is:

[0051]

[0052] In the formula,

[0053]

[0054]

[0055] Where θ is the observation matrix, H is the measurement matrix, and Q is the covariance matrix of the observation noise, is the distance between the lth external radiation source and the target;

[0056] Step 32, judge whether ||g l ||≤ε, if yes, the optimal solution X of the target state is obtained, otherwise go to step 33;

[0057] Step 33, calculate the search direction:

[0058]

[0059] In the formula,

[0060]

[0061] Step 34, determine the step size factor α l by using the Armijo criterion;

[0062] Step 35, update the target state X l+1 :

[0063] X l+1 = X l + α l d l

[0064] Calculation:

[0065]

[0066] Step 36, set the iteration number l=l+1, and judge whether l<lmax , l max is a preset maximum iteration number, if yes, return to step 32.

[0067] The present application has at least the following beneficial technical effects:

[0068] The TDOA-FDOA joint positioning method based on the LTE signal of the present application can accurately determine the position and speed information of the target by using the rich LTE signals in the external environment, has low computational complexity, low memory requirement, and strong robustness. BRIEF DESCRIPTION OF DRAWINGS

[0069] Fig. 1 is a schematic diagram of the TDOA-FDOA joint positioning scene based on the LTE signal of an embodiment of the present application;

[0070] Fig. 2 is a flowchart of the TDOA-FDOA joint positioning method based on the LTE signal of an embodiment of the present application. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the embodiments of the present application will be described in more detail below in conjunction with the drawings of the embodiments of the present application. In the drawings, the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some of the embodiments of the present application, not all. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below in conjunction with the drawings.

[0072] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0073] The embodiments of the present application will be described in detail below in conjunction with the drawings. Figs. 1-2 The present application will be described in further detail.

[0074] The present application provides a TDOA-FDOA joint positioning method based on the LTE signal, comprising the following steps:

[0075] Step one, construct the TDOA-FDOA joint positioning scene based on LTE signal;

[0076] Step two, in the TDOA-FDOA joint positioning scene based on LTE signal, the initial target state is determined by least square method;

[0077] Step three, according to the initial target state, the position and velocity of the target are accurately solved by conjugate gradient algorithm.

[0078] The TDOA-FDOA joint positioning method based on LTE signal of the application, in step one, the TDOA-FDOA joint positioning scene based on LTE signal is constructed, which includes:

[0079] Suppose there are N external radiators and an observation point in three-dimensional space, the external radiators emit LTE signals to the observation station through the target to form echo signals, and the external radiators emit radiation signals to the observation station to form direct wave signals, and the target is positioned by observing TDOA and FDOA information.

[0080] Among them, the parameters related to LTE signal in the subsequent derivation are mainly the position of external radiator sk , sk represent the position of external radiator k; the parameters related to TODA are mainly R and r k , R is the distance between the target and the observation station, r k is the observation value of the difference between the direct wave signal and the echo signal of external radiator k; the parameters related to FDOA are mainly and The velocity between the target and the observation station, is the observation value of the difference between the direct wave signal and the echo signal of external radiator k.

[0081] The TDOA-FDOA joint positioning method based on LTE signal of the application, in step two, in the TDOA-FDOA joint positioning scene based on LTE signal, the initial target state is determined by least square method X0 , including:

[0082] Let the distance R between the target and the observation station and the velocity be represented as:

[0083] R = ||u||2

[0084]

[0085] In the formula,

[0086] u = (x, y, z)T

[0087]

[0088] Constructing the binary quadratic equation of R and

[0089] where (·) T denotes the transpose, A1, B1, C1 are respectively:

[0090]

[0091] where s k = (x k , y k , z k ) T , (k = 1, 2,..., N) are the positions of the external radiation sources,

[0092] is the distance between the external radiation source k and the observation station, r k is the observed value of the path difference between the direct wave signal and the echo signal of the external radiation source k; R and

[0093] are calculated by combining formula (1) and (2)

[0094] R and are substituted into the likelihood function:

[0095] X = (D T D) -1 D T B

[0096] where,

[0097]

[0098] where O is a zero matrix;

[0099] An initial solution X0 that maximizes the likelihood function is calculated.

[0100] In this embodiment, the TDOA-FDOA joint positioning method based on the LTE signal is characterized in that R and comprise:

[0101] Since R must be a positive real number, let The value principle of R is:

[0102] When Δ < 0, R can only take complex roots:

[0103] If then

[0104] If R=0;

[0105] When △≥0, R respectively and / or

[0106] If and one of them is a positive root, the positive root is retained;

[0107] If and both are positive roots, both are temporarily retained;

[0108] If and both are negative roots, R=0;

[0109] The distance between the corresponding target and the observation station is calculated by formula (2) R , which is substituted into the equation about in formula (1), and the coefficients A2, B2, C2 are solved, respectively:

[0110]

[0111] In the formula,

[0112]

[0113] In formula (1) is the observation value of the difference between the path rate of the direct wave signal and the echo signal of the external radiation source k, is expressed as:

[0114]

[0115] When and both are positive roots, R and

[0116] The TDOA-FDOA joint positioning method based on the LTE signal of the application, in step three, the position and velocity of the target are accurately solved by the conjugate gradient algorithm according to the initial target state, including:

[0117] S31, initialize parameters, including: set the iteration number as l=0, the running error as 0

[0118] The calculation formula of the gradient direction is:

[0119]

[0120] wherein,

[0121]

[0122]

[0123] wherein, θ is an observation matrix, H is a measurement matrix, Q is a covariance matrix of observation noise, is the distance between the lth external radiation source and the target;

[0124] Step 32, judging whether ||g l ≤ε, if yes, the optimal solution X of the target state is obtained, otherwise, entering step 33;

[0125] Step 33, calculating the search direction:

[0126]

[0127] wherein,

[0128]

[0129] Step 34, determining the step factor a l using the Armijo criterion;

[0130] Step 35, updating the target state X l+1 :

[0131] X l+1 = X l + a l d l

[0132] Calculation:

[0133]

[0134] Step 36, setting the iteration number l = l + 1, and judging whether l < l max , l max is the preset maximum iteration number, if yes, returning to step 32.

[0135] The optimal solution of the target state is obtained according to the above steps, and the target position and speed can be obtained according to the optimal solution of the target state.

[0136] The TDOA-FDOA joint positioning method based on the LTE signal of the application uses the FDD mode downlink signal to position the target, considers that in the three-dimensional space, N external radiators emit LTE signals to the target to form echo signals at the observation station, and at the same time, the external radiators emit radiation signals to the observation station to form direct wave signals, and high-precision positioning of the target is performed through observation of TDOA and FDOA information.

[0137] The TDOA-FDOA joint positioning method based on the LTE signal of the application firstly constructs a TDOA-FDOA joint positioning scene based on the LTE signal, then determines the initial target state through the least square method, and finally uses the conjugate gradient target positioning to accurately solve the position and speed of the target. Through the above process, the target is positioned with high precision through observation of TDOA and FDOA information by using the target echo signal and direct wave signal in the case of external radiation of the LTE signal. The application can not only accurately determine the position and speed of the target, but also has low operation complexity, low memory requirement, and strong robustness.

[0138] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1.A TDOA-FDOA joint positioning method based on LTE signals, characterized in that, The application relates to a method for positioning a target based on LTE signals. Step one, constructing a TDOA-FDOA joint positioning scene based on LTE signals; Step two, determining an initial target state by a least square method under the TDOA-FDOA joint positioning scene based on LTE signals; Step three, accurately solving the position and speed of the target by a conjugate gradient algorithm according to the initial target state. In step one, the TDOA-FDOA joint positioning scene based on LTE signals is constructed, which comprises the following steps: Supposing that there are N external radiators and an observation point in a three-dimensional space, the external radiators emit LTE signals which form echo signals after passing through the target and reaching the observation station, and the external radiators emit radiation signals which form direct wave signals after reaching the observation station, and the target is positioned by observing TDOA and FDOA information; In step two, the initial target state is determined by the least square method under the TDOA-FDOA joint positioning scene based on LTE signals, which comprises the following steps: Let R be the distance between the target and the observation station and v the velocity is represented as: R=||u||2 In the formula, u = (x, y, z) T constructing a binary quadratic equation for x = 0 wherein (·) T denotes the transpose, and A1, B1, C1are respectively where s k = (x k ,y k ,z k ) T , (k = 1, 2,..., N) are the positions of the external radiation sources, is the distance between the external radiation source k and the observation station, r k is the observed value of the path difference between the direct wave signal and the echo signal of the external radiation source k. R and R are calculated using the combined equations (1) and (2) Substitute R and into the likelihood function: X = (D T D) -1 D T B In the formula, Wherein, O is a zero matrix; An initial solution X0 which maximizes the likelihood function is calculated; R and R are calculated using the combined equations (1) and (2) comprising: R is a positive real number, let The value of R is as follows: When Δ < 0, R Only complex roots can be obtained: If then If then R = 0; When Δ ≥ 0, R respectively acquire and / or If and if one of them is positive, the positive root is retained; If and are both positive roots, then both are temporarily retained; If and are both negative roots, then R = 0; The distance between the corresponding target and the observation station is calculated by formula (2) R , which is substituted into the equation about A2, B2, C2, respectively, are obtained by solving the equation In the formula, the difference between the path rate of change of the direct wave signal and the echo signal of the external radiation source k, is an observed value of the difference between the path rate of change of the direct wave signal and the echo signal of the external radiation source k, is expressed as: When and are both positive roots, R and 2.The LTE signal based TDOA-FDOA joint positioning method of claim 1, wherein, In step three, the position and speed of the target are accurately solved by the conjugate gradient algorithm according to the initial target state, which comprises the following steps: S31, initializing parameters, including: setting iteration number as l=0, running error as 0<ε<1, and initial gradient direction as The calculation formula of the gradient direction is: In the formula, wherein Θ is an observation matrix, H is a measurement matrix, Q is a covariance matrix of observation noise, is the distance between the lth external source and the target. Step 32, judge whether ||g l ||≤ε, if yes, get the optimal solution X of the target state, otherwise go to step 33; Step 33, calculating a search direction: In the formula, Step 34, determine step factor a using Armijo rule l ; Step 35, update target state X l+1 : X l+1 = X l + a l d l Calculation: Step 36, set iteration number l = l + 1, and judge whether l < l max max max is preset maximum iteration number, if yes, return to step 32.

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