A high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation

Abstract

This invention discloses a high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency-space modulation, covering the fields of communication, time-frequency, delay Doppler, and ranging. This method, incorporating the characteristics of high-mobility communication systems, employs OTFS modulation technology, source coding and channel coding for signal transmission, and OTFS channel estimation and OTFS equalization for signal reception. This method generates an integrated communication and navigation signal, achieving high-precision distance measurement and high-quality communication between communicating parties. This method ultimately solves the channel delay estimation problem in high-mobility wireless communication systems and enables ranging in these systems.

Description

Technical Field

[0001] The present invention relates to the fields of communication, time frequency, delay Doppler, ranging, and more particularly to a communication and navigation integrated high-precision ranging method based on orthogonal time-frequency-air modulation. Background Art

[0002] In recent years, public demand for ubiquitous location-based services has continued to grow. However, satellite navigation, with its insufficient coverage in indoor scenarios and elsewhere, has been unable to meet these needs. Due to the wide coverage of communication signals, the large number of users, and the wide bandwidth of signals, using communication signals for positioning can effectively complement satellite navigation. Against this backdrop, with the rapid development of communication and positioning technologies, the coupling between communication and navigation has deepened, giving rise to integrated communication and navigation technology, which has become a research hotspot both domestically and internationally.

[0003] The sixth generation mobile communication system (6G) has become a global research hotspot. To meet the emerging demands of diverse scenarios, research is needed on integrated communication and navigation technologies. High mobility is a key 5G application scenario, requiring high data rates in highly mobile and delay-spread wireless channels. Orthogonal frequency division multiplexing (OFDM) modulation suffers from poor Doppler resistance in these channels. Orthogonal time-frequency space (OTFS) modulation, however, addresses OFDM's poor Doppler resistance by combining quadrature amplitude modulation (QAM) information symbols in the delay-Doppler domain with sensing capabilities that utilize the delay-Doppler effect of echoes for target detection. This non-traditional waveform design for integrated communication and navigation has garnered significant attention. Summary of the Invention

[0004] The present invention addresses the problem of proposing an effective ranging method for high-mobility communication systems. This method can address ranging issues in these systems. With limited modifications, it can improve the channel delay estimation capability of these systems, thereby enabling them to achieve a certain level of ranging capability.

[0005] The technical solution adopted in the present invention is:

[0006] A communication and navigation integrated high-precision ranging method based on orthogonal time-frequency and air-conditioning modulation includes the following steps:

[0007] (1) The sender and receiver establish a communication link;

[0008] (2) The sender first performs LTE source coding on the user data, then performs QAM channel coding, performs OTFS modulation on the coded signal, and sends the resulting communication and navigation integrated signal to the receiver via a high-mobility channel; the LTE source coding uses Turbo coding;

[0009] (3) The receiver performs OTFS demodulation and OTFS channel estimation on the received signal. The OTFS channel estimation uses the orthogonal matching pursuit algorithm to estimate the channel delay based on the pilot response matrix of the signal. The final measured distance is the electromagnetic wave speed multiplied by the delay, thereby obtaining the ranging information;

[0010] (4) Based on the OTFS channel estimation, the receiver performs OTFS equalization on the communication and navigation integrated signal and finally outputs the user data.

[0011] Furthermore, LTE source coding uses a 1 / 3 code rate Turbo encoder. The LTE Turbo encoder consists of two 8-state convolutional encoders in parallel and is divided into two by an interleaver.

[0012] Furthermore, the OTFS modulation of the sender is to perform an inverse symplectic finite Fourier transform on the encoded data and then perform a Heisenberg transform; the OTFS demodulation of the receiver is to perform a Wigner transform and a symplectic finite Fourier transform on the received signal.

[0013] Furthermore, the OTFS channel estimation in step (3) is specifically as follows:

[0014] (301) Initialize the stopping criteria thresholds α and β and the noise variance σ 2 , and according to the input-output relationship of OTFS, the pilot signal input in the DD domain is used Get the pilot response matrix:

[0015]

[0016]

[0017] Where α and β are tuning factors that affect the number of paths to be estimated, (i, j) is the coordinate of the pilot in the DD domain, l is the index of the delay grid in the DD domain, indicating the lth delay grid, k is the index of the Doppler grid, and h is the index of the Doppler grid. p is the path gain, ψ p is the phase shift caused by Doppler shift, φ p is the initial phase, is the path Doppler expressed in the DD domain, is the integer part, For the fraction part, is the path delay expressed in the DD domain, N is the total number of delay grids, M is the total number of Doppler grids, and P is the total number of multipaths;

[0018] (302) Initialization: is the index of the multipath, indicating the Paths;

[0019] (303) Order h′ is The column vector set of , initially there is only the first column, indicating that the traversal starts from the first delay index of the first path;

[0020] (304) Calculate R using h′ h′，γ (k+κ), forming the vector R h′，γ , R h′，γ (k+κ) is the number of delay grids on the lth delay grid. with γ N Normalized cross-correlation function between (k+κ), where k is the integer part and κ is the fractional part;

[0021]

[0022] (305) Determine whether all column vectors of h′ are positive or negative to R h′，γ (k+κ) calculation is completed, if not, return to step (304); if the traversal is completed, execute step (306);

[0023] (306)Use |R h′，γ | Maximum value found

[0024] (307) If Indicates the estimated channel gain of the previous path, indicating is the largest of all paths, jump to step (308); otherwise, estimate according to the following formula renew renew

[0025]

[0026] (308) Determine whether the stopping criteria are met. If yes, Jump to step (303); otherwise jump to step (304); until all l traversals are completed, output for all Path parameters The stopping criteria are: The delay l estimation algorithm stops when at least one of the following conditions is met:

[0027]

[0028] Furthermore, OTFS equalization selects a frequency domain equalizer.

[0029] Compared with the background technology, the present invention has the following advantages:

[0030] (1) The present invention proposes a high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency and air-conditioning modulation, which solves the ranging problem of high-mobility wireless communication systems. It has a wide range of applications, requires little hardware modification, and is easy to implement.

[0031] (2) The present invention proposes a high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency and air-conditioning modulation, which is completely based on the communication link, does not add additional overhead to the original system, and can simultaneously complete distance measurement and communication.

[0032] (3) The present invention proposes a high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency and air-conditioning modulation, which can achieve high-precision ranging, and the signal processing is simple and convenient. The technical solution of the present invention has high practicality and economic benefits and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation.

[0034] Figure 2 This is a schematic diagram of OTFS modulation and demodulation.

[0035] Figure 3 It is the flow chart of ranging algorithm. DETAILED DESCRIPTION

[0036] The following is combined with Figures 1 to 3 The present invention is further described in detail.

[0037] A communication and navigation integration technology based on orthogonal time-frequency and air-conditioning is applicable to high-mobility scenarios and has high-precision ranging accuracy. The present invention aims to solve the ranging problem of high-mobility communication systems.

[0038] A high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation is described. The specific process is as follows:

[0039] Figure 1 Flowchart of the method of the present invention. The workflow of the method of the present invention is as follows:

[0040] (1) The sender is called A and the receiver is called B. The signal sender and receiver establish a communication link.

[0041] (2) At sender A, the user data is first LTE source coded. LTE source coding uses Turbo coding. LTE uses a 1 / 3 code rate Turbo encoder as the basis of the channel coding scheme. The LTE Turbo encoder consists of two 8-state convolutional encoders in parallel and is divided into two by an interleaver. Then QAM channel coding is performed. The coded signal is modulated by OTFS and reaches the receiver B after passing through the channel. Figure 2 As shown, OTFS modulation performs an inverse sigmoid Fourier transform (ISFFT) on the input data, and then performs a Heisenberg transform. The sender A sends an integrated communication and navigation signal, which reaches the receiver B through the channel.

[0042] (3) Receiver B performs Wigner transform and sigmoid Fourier transform (SFFT) on the received signal, and then performs OTFS channel estimation on the received signal. OTFS channel estimation uses the orthogonal matching pursuit algorithm to estimate the channel delay based on the pilot response matrix of the signal. The final measured distance is the electromagnetic wave speed multiplied by the delay, thereby obtaining the ranging information;

[0043] Specifically, the present invention proposes a method of utilizing with γ N (k+κ) cross-Doppler domain element channel estimation method, this method is designed based on the OMP algorithm idea, and its core idea is to find with γ N The cross-correlation function R of (k+κ) h′，γ The largest atom (k+κ) is used as the result to construct a sparse approximation. Figure 3 As shown in Figure 2, the specific process of OTFS channel estimation is as follows:

[0044] (301) Initialize the stopping criteria thresholds α and β and the noise variance σ 2 , and according to the input-output relationship of OTFS, the pilot signal input in the DD domain is used Get the pilot response matrix:

[0045]

[0046]

[0047] Where α and β are tuning factors that affect the number of paths to be estimated, (i, j) is the coordinate of the pilot in the DD domain, l is the index of the delay grid in the DD domain, indicating the lth delay grid, k is the index of the Doppler grid, and h is the index of the Doppler grid. p is the path gain, ψ p is the phase shift caused by Doppler shift, φp is the initial phase, is the path Doppler expressed in the DD domain, is the integer part, For the fraction part, is the path delay expressed in the DD domain, N is the total number of delay grids, M is the total number of Doppler grids, and P is the total number of multipaths;

[0048] (302) Initialization: is the index of the multipath, indicating the Paths;

[0049] (303) Order h′ is The column vector set of , initially there is only the first column, indicating that the traversal starts from the first delay index of the first path;

[0050] (304) Calculate R using h′ h′，γ (k+κ), forming the vector R h′，γ , R h′，γ (k+κ) is the number of delay grids on the lth delay grid. with γ N Normalized cross-correlation function between (k+κ), where k is the integer part and κ is the fractional part;

[0051]

[0052] (305) Determine whether all column vectors of h′ are positive or negative to R h′，γ (k+κ) calculation is completed, if not, return to step (304); if the traversal is completed, execute step (306);

[0053] (306)Use |R h′，γ | Maximum value found

[0054] (307) If Indicates the estimated channel gain of the previous path, indicating is the largest of all paths, jump to step (308); otherwise, estimate according to the following formula renew renew

[0055]

[0056] (308) Determine whether the stopping criteria are met. If yes, Jump to step (303); otherwise jump to step (304); until all l traversals are completed, output for all Path parameters The stopping criteria are: The delay l estimation algorithm stops when at least one of the following conditions is met:

[0057]

[0058] (4) Receiver B performs OTFS equalization on the integrated communication and navigation signal based on the OTFS channel estimation, ultimately outputting user data. The present invention uses a frequency-domain equalizer. The frequency-domain response of the channel can be directly obtained through the pilot signal inserted into each symbol. This allows equalization of the integrated communication and navigation signal to be accomplished using a simple single-point equalizer, a major advantage of the OTFS system.

[0059] Specifically, the present invention uses estimated, near-perfect channel parameters to perform an inversion operation on the received signal, accurately recovering the communication information and achieving a low bit error rate. The received signal is derived from a two-dimensional convolution of the transmitted signal and the channel. A two-dimensional deconvolution operation is then performed in the frequency domain, resulting in the product of the transmitted signal and the channel's frequency domain response.

[0060] Based on the above steps (1) to (3), the distance measurement between two nodes can be completed, and based on the above steps (1) to (4), the communication between the two nodes can be completed.

Claims

1. A high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation, characterized in that: The following steps are involved: (1) The sender and receiver establish a communication link; (2) The sender first performs LTE source coding on the user data, then performs QAM channel coding, performs OTFS modulation on the coded signal, and sends the resulting communication and navigation integrated signal to the receiver via a high-mobility channel; Among them, LTE source coding uses Turbo coding; (3) The receiver performs OTFS demodulation and OTFS channel estimation on the received signal. The OTFS channel estimation uses the orthogonal matching pursuit algorithm to estimate the channel delay based on the pilot response matrix of the signal. The final measured distance is the electromagnetic wave speed multiplied by the delay, thereby obtaining the ranging information; (4) The receiver performs OTFS equalization on the communication and navigation integrated signal based on the OTFS channel estimation and finally outputs the user data; Among them, the OTFS channel estimation in step (3) is specifically: (301) Initialize the stopping criteria thresholds α and β and the noise variance σ 2 , and according to the input-output relationship of OTFS, the pilot signal input in the DD domain is used Get the pilot response matrix: Where α and β are tuning factors that affect the number of paths to be estimated, (i, j) is the coordinate of the pilot in the DD domain, l is the index of the delay grid in the DD domain, indicating the lth delay grid, k is the index of the Doppler grid, and h is the index of the Doppler grid. p is the path gain, ψ p is the phase shift caused by Doppler shift, φ p is the initial phase, is the path Doppler expressed in the DD domain, is the integer part, For the fraction part, is the path delay expressed in the DD domain, N is the total number of delay grids, M is the total number of Doppler grids, and P is the total number of multipaths; (302) Initialization: is the index of the multipath, indicating the Paths; (303) Order h′ is The column vector set of , initially there is only the first column, indicating that the traversal starts from the first delay index of the first path; (304) Calculate R using h′ h′,Υ (k+κ), forming the vector R h′,Υ , R h′,Υ (k+κ) is the number of delay grids on the lth delay grid. With Υ N Normalized cross-correlation function between (k+κ), where k is the integer part and κ is the fractional part; (305) Determine whether all column vectors of h′ are positive or negative to R h′,Υ (k+κ) calculation is completed, if not, return to step (304); if the traversal is completed, execute step (306); (306)Use |R h′,Υ | Maximum value found (307) If Indicates the estimated channel gain of the previous path, indicating is the largest of all paths, jump to step (308); otherwise, estimate according to the following formula renew renew (308) Determine whether the stopping criteria are reached. If yes, Jump to step (303); otherwise jump to step (304); until all l traversals are completed, output for all Path parameters The stopping criteria are: The delay l estimation algorithm stops when at least one of the following conditions is met:

2. The high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation according to claim 1, characterized in that: LTE source coding uses a 1 / 3 code rate turbo encoder. The LTE turbo encoder consists of two 8-state convolutional encoders in parallel and is split into two by an interleaver.

3. The high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation according to claim 1, characterized in that: The OTFS modulation at the sender is to perform an inverse symplectic finite Fourier transform on the encoded data, followed by a Heisenberg transform; the OTFS demodulation at the receiver is to perform a Wigner transform and a symplectic finite Fourier transform on the received signal.

4. The high-precision ranging method for integrated communication and navigation based on orthogonal time-frequency modulation according to claim 1, characterized in that: OTFS equalization selects frequency domain equalizer.

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