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CN-121994224-A - Tunnel positioning terminal with self-adaptive Doppler frequency shift compensation function and compensation method thereof

CN121994224ACN 121994224 ACN121994224 ACN 121994224ACN-121994224-A

Abstract

The invention belongs to the technical field of wireless positioning, and discloses a tunnel positioning terminal with self-adaptive Doppler frequency shift compensation and a compensation method thereof, wherein the tunnel positioning terminal comprises Doppler frequency shift real-time modeling and dynamic calculation of a frequency shift compensation value through a self-adaptive compensation module; the self-adaptive compensation module specifically comprises a Doppler pre-transformation unit, a dimension reduction processing unit, a dimension reduction STAP signal processing module, a self-adaptive frequency offset compensation execution unit and a low-power consumption management unit, wherein the Doppler pre-transformation unit is used for carrying out discrete Fourier transformation on a received signal in a Doppler domain and decomposing a full-dimension space-time data matrix into a plurality of independent Doppler slices, the dimension reduction processing unit is used for constructing a dimension reduction covariance matrix in each Doppler slice to carry out self-adaptive weight calculation, the signal receiving is optimized based on the dimension reduction STAP signal processing module, multipath interference is restrained, and the self-adaptive frequency offset compensation execution unit is used for carrying out low-power consumption management, wherein the power management strategy and the low-power management are included. The invention adopts the compensation method, optimizes the signal receiving path based on the dimension-reducing STAP signal processing algorithm of the pre-Doppler conversion, and realizes the self-adaptive Doppler frequency shift compensation.

Inventors

  • GUO CHENGJUN

Assignees

  • 电子科技大学

Dates

Publication Date
20260508
Application Date
20260225

Claims (10)

  1. 1. The tunnel positioning terminal with the adaptive Doppler frequency shift compensation and the compensation method thereof are characterized by comprising the following steps: Step S1, a speed sensor is built in a terminal, and the moving speed and the moving direction are monitored in real time; S2, modeling Doppler frequency shift in real time, and dynamically calculating a frequency shift compensation value through an adaptive compensation module; the self-adaptive compensation module specifically comprises a Doppler pre-transformation unit and a dimension reduction processing unit; the Doppler pre-transformation unit is used for carrying out Discrete Fourier Transform (DFT) on the received signal in a Doppler domain and decomposing the full-dimensional space-time data matrix into a plurality of independent Doppler slices; The dimension reduction processing unit is used for constructing a dimension reduction covariance matrix in each Doppler slice and carrying out self-adaptive weight calculation; Step S3, optimizing signal reception and restraining multipath interference based on a dimension reduction STAP signal processing module; s4, performing adaptive frequency offset compensation; and S5, low power consumption management, including power management strategies and low power management.
  2. 2. The tunnel positioning terminal with adaptive doppler shift compensation and the compensation method thereof according to claim 1, wherein in step S1, a high-precision speed sensor is built in the terminal, and the moving speed and direction are monitored in real time, and the specific process is as follows: s11, fusing an inertial sensor IMU and a wheel speed meter with a GNSS to carry out Doppler speed measurement, and starting a triaxial accelerometer, a triaxial gyroscope and a magnetometer after a terminal is started; s12, outputting a high-precision speed vector and a course angle through extended Kalman filtering; And S13, the terminal reads the wheel speed signal through the CAN bus and predicts Doppler frequency shift.
  3. 3. The tunnel locating terminal with adaptive Doppler shift compensation and its compensation method as claimed in claim 2, wherein the relative speed obtained by the terminal speed measuring module is used And known signal carrier frequency Calculating the expected Doppler shift The following is shown: ; Wherein, the Is Doppler shift, hz; the terminal speed, m/s; Carrier frequency, hz, of the radio signal; Is the included angle between the signal incident angle and the moving direction; the light velocity is 3X 10 8 m/s.
  4. 4. The tunnel locating terminal for adaptive Doppler shift compensation and the compensation method thereof according to claim 1, wherein in step S2, doppler shift is modeled in real time, and complex multidimensional matrix inversion operation is converted into a plurality of parallel one-dimensional processes by projecting a full-dimensional matrix into Doppler subspace, and a shift compensation value is dynamically calculated by the following steps: s21, dynamically calculating theoretical Doppler shift based on the relative motion speed and signal carrier frequency; step S22, a dual-mode compensation strategy is adopted, PLL compensation is used for low-dynamic scenes, FFT-VV joint compensation algorithm is used for high-dynamic scenes, and frequency offset capturing and phase compensation are achieved.
  5. 5. The tunnel positioning terminal with adaptive doppler shift compensation and the compensation method thereof according to claim 1, wherein in step S3, signal reception is optimized based on a dimension-reduced STAP signal processing module, and multipath interference is suppressed, specifically comprising the following steps: step S31, sampling the received signals in N continuous symbol periods, and extracting the time delay, amplitude and phase information of multipath components by using a channel estimator; Step S32, based on a multipath separation algorithm, outputting complex envelope signals of a main path as M equivalent space channels, and constructing an equivalent space-time data matrix; And S33, designing a space-time adaptive filter weight by adopting a minimum variance undistorted response MVDR criterion, and realizing the joint optimization of the Doppler domain and the space domain.
  6. 6. The tunnel locating terminal with adaptive Doppler shift compensation and the compensation method thereof according to claim 5, wherein in step S31, the received signal is received The following is shown: ; Wherein, the Attenuation is the kth path amplitude; is the delay of the kth path; is Doppler shift; phase for the kth path; Is a noise signal; For transmitting signals.
  7. 7. The tunnel positioning terminal for adaptive doppler shift compensation and the compensation method thereof according to claim 6, wherein in step S32, complex envelope signals of a dominant path are output as M equivalent spatial channels based on a multipath separation algorithm, and an equivalent space-time data matrix is constructed by the following specific procedures: Step S321, by continuously comparing Multipath parameter estimation is carried out by each sampling window, and separation is carried out A plurality of dominant paths; step S322, envelope each path Consider an equivalent spatial channel output, wherein, Is the complex envelope of the mth path; Is the first The amplitude of the strip path; is Doppler shift frequency; an initial phase for the mth path; Step S323, constructing equivalent space-time data vector The following is shown: ; Wherein, the Represents the kronecker product; is a time tap vector, and T represents a transpose operation.
  8. 8. The tunnel locating terminal for adaptive Doppler shift compensation and the compensation method thereof according to claim 6, wherein in step S33, the MVDR criterion is adopted to design the space-time adaptive filter weight, so as to realize the joint optimization of the Doppler domain and the space domain, and the specific process is as follows: s331, designing an MxL-order space-time adaptive filter, wherein M is the number of equivalent channels, and L is the number of time taps; Step S332, designing an FIR filter bank, wherein each path corresponds to one time domain filter, and updating a filter coefficient on line by using a Least Mean Square (LMS) or Recursive Least Square (RLS) algorithm with the aim of stabilizing the phase of an output signal; step S333, updating the space-time adaptive filter weight based on the MVDR criterion, and adopting a recursive least square RLS algorithm to realize the adaptation to the rapid time-varying of the channel caused by the high-speed movement of the terminal in the tunnel.
  9. 9. The adaptive doppler shift compensated tunnel locating terminal and its compensation method according to claim 8, wherein in step S333, the filter weight vector defining the time n is The input signal vector is The desired signal is Introducing forgetting factor lambda (0 < lambda less than or equal to 1) for weighting the historical data; the filter weight vector update rule is as follows: (1) Calculating an estimation error at the current input The following is shown: ; Wherein H represents conjugate transpose operation; (2) Using covariance matrix at current time And input vector Updating Kalman gain The following is shown: ; (3) According to the error signal And gain vector Updating filter weights The following is shown: ; Wherein, the Representing complex conjugate operations; (4) Updating covariance matrix The following is shown: ; The filter weight tracks the channel variation in real time, and dynamically compensates Doppler frequency shift caused by the motion of the terminal while restraining multipath interference, so as to ensure the maximization of the output signal-to-noise ratio.
  10. 10. The tunnel positioning terminal and the compensation method thereof according to claim 1, wherein in step S4, the adaptive frequency offset compensation is performed as follows: Step S41, dynamically adjusting the frequency of a local oscillator or applying complex exponential rotation to a baseband signal in a digital down-conversion stage to realize zero frequency offset of a received signal; Step S42, adopting a pre-Doppler STAP method, firstly Doppler filtering and then space processing, and obtaining the calculation complexity from Down to Reduces the occupation of FPGA resources, wherein, In order to be the number of doppler channels, Is a subarray array after dimension reduction, and ; And S43, estimating residual frequency offset through a PLL by adopting a closed-loop feedback correction mechanism, and dynamically adjusting a compensation value to ensure compensation accuracy.

Description

Tunnel positioning terminal with self-adaptive Doppler frequency shift compensation function and compensation method thereof Technical Field The invention relates to the technical field of wireless positioning, in particular to a tunnel positioning terminal with self-adaptive Doppler frequency shift compensation and a compensation method thereof. Background In closed traffic scenes such as tunnels, high-precision positioning of moving carriers such as vehicles has important significance for guaranteeing traffic safety and improving traffic efficiency, and Doppler frequency shift compensation effect is one of key factors influencing positioning precision. Currently, the technical development in the related art presents the following status quo, but there are also many defects and shortcomings to be solved. In the aspect of development of the prior art, in the field of Doppler frequency shift compensation, the traditional technical scheme mostly adopts a realization mode of fixed compensation values, and the mode has obvious limitations, cannot adapt to dynamically-changed application scenes, and is difficult to meet actual positioning requirements. At the level of signal processing technology, some researches have been attempted to apply space-time adaptive processing (STAP) technology to positioning-related signal optimization, but such technology has not been effectively applied in a special environment of a tunnel. In the aspect of dynamic positioning precision, the problem of performance attenuation of the existing positioning technology in a high-speed moving scene is remarkable, the positioning precision is obviously reduced, and the existing positioning technology cannot be adapted to core application scenes such as high-speed running of vehicles in tunnels. The method mainly comprises the following three aspects of low compensation precision, direct precision attenuation in the dynamic positioning process caused by the traditional technical scheme with fixed compensation value, serious signal interference problem, obvious multipath effect, greatly reduced positioning signal quality and further aggravated positioning error caused by the fact that the tunnel is used as a closed space, and poor environment and scene adaptability, wherein the traditional various positioning and compensation methods do not fully consider complex environment characteristics in the tunnel, cannot effectively adapt to dynamic complex scenes such as high-speed running of a vehicle, and cannot meet the reliability and precision requirements in practical application. In summary, the doppler shift compensation technology in the dynamic positioning under the current tunnel environment has obvious technical shortboards, and the compensation precision, the anti-interference capability and the scene adaptability of the related technical scheme cannot be matched with the actual application requirements, so that the high-efficiency doppler shift compensation technology capable of adapting to the tunnel environment is needed to be provided, and the problems in the prior art are solved. Disclosure of Invention The invention aims to provide a tunnel positioning terminal with self-adaptive Doppler frequency shift compensation and a compensation method thereof, which combine the self-adaptive Doppler frequency shift compensation with a dimension-reducing STAP algorithm to be applied to the tunnel positioning terminal, thereby solving the problem of low dynamic positioning precision in a tunnel. In order to achieve the above object, the present invention provides a tunnel positioning terminal with adaptive doppler shift compensation and a compensation method thereof, comprising the following steps: Step S1, a speed sensor is built in a terminal, and the moving speed and the moving direction are monitored in real time; S2, modeling Doppler frequency shift in real time, and dynamically calculating a frequency shift compensation value through an adaptive compensation module; the self-adaptive compensation module specifically comprises a Doppler pre-transformation unit and a dimension reduction processing unit; the Doppler pre-transformation unit is used for carrying out Discrete Fourier Transform (DFT) on the received signal in a Doppler domain and decomposing the full-dimensional space-time data matrix into a plurality of independent Doppler slices; The dimension reduction processing unit is used for constructing a dimension reduction covariance matrix in each Doppler slice and carrying out self-adaptive weight calculation; Step S3, optimizing signal reception and restraining multipath interference based on a dimension reduction STAP signal processing module; s4, performing adaptive frequency offset compensation; and S5, low power consumption management, including power management strategies and low power management. Preferably, in step S1, a high-precision speed sensor is built in the terminal, and the moving speed and direction are monitore