Multipath Doppler frequency shift estimation method, device, and storage medium

Abstract

The present application relates to a method, device and storage medium for estimating multipath Doppler frequency shift. The method comprises: obtaining the size M, N of a preset OTFS orthogonal time-frequency space-delay time-domain symbol matrix #imgabs0#; obtaining the position (m p , n p ); and determining the zero protection zone delay domain length parameter L of the pulse pilot; according to the size M, N of the preset symbol matrix of the symbol matrix #imgabs1#, the position of the pulse pilot (m p , n p ) and the length parameter L, calculate the sequence #imgabs2# step 3, calculate the multipath detection threshold γ according to the sequence #imgabs3#; detect the position of the multipath channel path according to the multipath detection threshold γ, and obtain the detected P multipath path positions m 1 , ..., m P ; Calculate the normalized power e of each path based on the detected multipath path position and the sequence #imgabs4# i ; According to the detected multipath path position and the symbol matrix, the Doppler frequency shift κ of each path is calculated i .

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a method, device, and storage medium for estimating multipath Doppler frequency shift. Background Art

[0002] In wireless communications, when a transmitted wireless signal propagates in a high-speed moving and multipath scenario, due to the multipath effect and the Doppler effect, the received signal is composed of multiple signals with different Doppler frequency shifts and delays. At this time, the channel is a dual-selective channel and has time-varying characteristics.

[0003] Orthogonal Time-Frequency-Space (OTFS) technology is a strong candidate technology for the next generation of wireless communication systems. It is robust under time-varying channels and backward compatible with OFDM (Orthogonal Frequency Division Multiplexing) technology. The channel representation and information symbol multiplexing in OTFS are in the time delay domain, which is the two-dimensional Fourier dual of the time-frequency domain. This gives OTFS two obvious advantages over the wireless communication technologies that are currently in use.

[0004] First, in high mobility scenarios, the response of the channel in the time-frequency domain varies with time. Although traditional communication systems such as OFDM systems have adopted methods such as shortening the frame length and increasing the number of pilots, it is still difficult to overcome the negative impact of time-varying channels. The OTFS system, based on the geometric form determined by the wireless channel, converts the time-frequency channel into a two-dimensional delay-Doppler channel, thereby converting the changing channel parameters into unchanging channel parameters, greatly reducing the difficulty of channel analysis.

[0005] Secondly, OTFS places the modulated symbols in the delayed time domain and disperses them into the time-frequency domain, so it can fully utilize the channel diversity gain under the time and frequency selective channels caused by high mobility scenarios.

[0006] In the demodulation process of the OTFS system, when the Doppler frequency shifts of each path are integers, the inter-symbol interference in the delay time domain can be well eliminated through channel estimation and equalization. However, when the Doppler frequency shift is a fraction, the observed channel will spread over the entire Doppler axis. At this time, the performance of channel estimation and equalization will decrease, resulting in poor detection performance. Summary of the invention

[0007] The present application provides a multipath Doppler shift estimation method, device, and storage medium, which can reduce channel energy diffusion and reduce inter-symbol interference in the delay time domain.

[0008] A multipath Doppler shift estimation method, comprising:

[0009] Step 1: Get the preset OTFS orthogonal time-frequency space-delay time domain symbol matrix The size of M, N; obtain the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot;

[0010] Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix;

[0011] m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix;

[0012] Step 2, according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Where m represents the sequence index;

[0013] Step 3, according to the sequence Calculate and obtain the multipath detection threshold γ;

[0014] Step 4: Detect the position of the multipath channel path according to the multipath detection threshold γ, and obtain the detected P multipath path positions m 1 ,…m P ;m 1 <… <m P ;;P is the number of multipath paths detected;

[0015] Step 5: based on the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path;

[0016] Step 6: Calculate the Doppler frequency shift κ of each path based on the detected multipath path position and the symbol matrix. i .

[0017] The method further comprises:

[0018] Step 7, according to the Doppler frequency shift κ i , and perform Doppler shift compensation.

[0019] The step 4 comprises:

[0020] Define the first path delay l 1 = 0 corresponding to the initial position m of the pilot 1 =m p ;

[0021] Sequentially detect sequence index m from m p +1 to m p +L-1 corresponding sequence Whether it exceeds the multipath detection threshold γ;

[0022] The m that exceeds the multipath detection threshold γ is the position of the multipath path, and finally the position m of the P multipath paths detected is obtained. 1 ,...,m P And m 1 <… <m P .

[0023] The calculation expression of step 2 is:

[0024] Among them, m and n represent index variables;

[0025] The calculation expression of step 3 is: or

[0026] The calculation expression of step 5 is: m i is the delay axis index of the i-th path;

[0027] The calculation expression of step 6 is:

[0028] The step 7 includes: adopting the average distance minimum compensation process: specifically including:

[0029] Step 71A, according to the Doppler frequency shift κ of each path i , calculate the distance function:

[0030] Step 72A, according to the distance function d i (ε) and the normalized power e of each path i , the average distance function is calculated:

[0031] Step 73A, taking the average distance function d w (ε) The minimum compensation frequency deviation, which is used as the first compensation frequency deviation

[0032] Step 74A, using the first compensation frequency deviation Doppler shift compensation is performed on the received signal.

[0033] The step 71A is specifically as follows:

[0034] d i (ε)=|(κ i -ε)-round(κ i -ε)|, i = 1, ..., P,

[0035] where ε∈[-0.5, 0.5), round(·) means rounding to the nearest integer; or

[0036] Step 72A is specifically as follows:

[0037]

[0038] Step 73A is specifically as follows:

[0039]

[0040] The step 7 includes: using the strongest diameter compensation process, specifically including:

[0041] Step 71b, according to the normalized power of each path, obtain the index i of the strongest path m ; m is

[0042] Step 72b, index i of the strongest path m The corresponding Doppler shift As compensation frequency offset Doppler shift compensation is performed on the received signal.

[0043] The step 71b is specifically as follows:

[0044] A multipath Doppler frequency shift estimation device, comprising:

[0045] Acquisition unit, obtains the preset OTFS orthogonal time-frequency space-delay time domain symbol matrix The size of M, N; obtain the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot;

[0046] Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix;

[0047] m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix;

[0048] The first calculation unit, according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Where m represents the sequence index;

[0049] The second computing unit, according to the sequence Calculate and obtain the multipath detection threshold γ;

[0050] The detection unit detects the position of the multipath channel path according to the multipath detection threshold γ, and obtains the detected P multipath path positions m 1 , ..., m p ;m 1 <…<m p ; P is the number of multipath paths detected;

[0051] The third calculating unit is configured to calculate the multipath path position and the sequence according to the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path;

[0052] The fourth calculation unit calculates the Doppler frequency shift k of each path according to the detected multipath path position and the symbol matrix. i .

[0053] A computer-readable storage medium stores a computer program, which implements the steps of the method when executed by a processor.

[0054] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art: In the present application, a preset OTFS orthogonal time-frequency space-delay time domain symbol matrix is ​​obtained The size of M, N; obtain the position of the pulse pilot in the symbol matrix (m p , n p ); and determine the zero protection zone delay domain length parameter L of the pulse pilot; according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Step 3, according to the sequence Calculate the multipath detection threshold γ; detect the position of the multipath channel path according to the multipath detection threshold γ, and obtain the detected P multipath path positions m 1 ,…,m P ;m 1 <…<m P ; According to the detected multipath path position and the sequence Calculate the normalized power e of each path i ; According to the detected multipath path position and the symbol matrix, the Doppler frequency shift κ of each path is calculated iBy utilizing the properties of the OTFS pulse pilot to estimate the Doppler frequency shift of each path when the multipath delay does not overlap, the energy dispersion of the channel can be reduced in the delay time domain, the inter-symbol interference can be reduced, and the system performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0057] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0058] Figure 1 It is a flowchart of a method for estimating multipath Doppler frequency shift provided by an embodiment of the present invention;

[0059] Figure 2 It is a connection diagram of a multipath Doppler frequency shift estimation device provided by an embodiment of the present invention;

[0060] Figure 3 is a flow chart of a Doppler frequency shift estimation method provided by an embodiment of the present invention;

[0061] Figure 4 It is a flowchart of a method for compensating for minimum Doppler frequency shift in average distance provided by an embodiment of the present invention;

[0062] Figure 5 is a flow chart of the strongest Radius Doppler frequency shift compensation method provided by an embodiment of the present invention;

[0063] Figure 6 is a schematic diagram of a pulse pilot pattern provided by an embodiment of the present invention;

[0064] Figure 7 is a diagram of RMSE simulation results of Doppler frequency shift estimation under different pilot powers provided by an embodiment of the present invention;

[0065] Figure 8 It is a diagram of the bit error rate simulation result of the OTFS system after using two methods for compensating Doppler frequency shift provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0067] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0068] Figure 1 A multipath Doppler shift estimation method provided in an embodiment of the present application includes:

[0069] Step 1: Get the preset OTFS orthogonal time-frequency space-delay time domain symbol matrix The size of M, N; obtain the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot;

[0070] Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix;

[0071] m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix;

[0072] Step 2, according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Where m represents the sequence index;

[0073] Step 3, according to the sequence Calculate and obtain the multipath detection threshold γ;

[0074] Step 4: Detect the position of the multipath channel path according to the multipath detection threshold γ, and obtain the detected P multipath path positions m 1 ,…,m P ;m 1 <…<mP ; P is the number of multipath paths detected;

[0075] Step 5: based on the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path;

[0076] Step 6: Calculate the Doppler frequency shift κ of each path based on the detected multipath path position and the symbol matrix. i .

[0077] Wherein, the method further comprises:

[0078] Step 7, according to the Doppler frequency shift κ i , and perform Doppler shift compensation.

[0079] Wherein, the step 4 comprises:

[0080] Define the first path delay l 1 = 0 corresponding to the initial position m of the pilot 1 =m p ;

[0081] Sequentially detect sequence index m from m p +1 to m p +L-1 corresponding sequence Whether it exceeds the multipath detection threshold γ;

[0082] The m that exceeds the multipath detection threshold γ is the position of the multipath path, and finally the position m of the P multipath paths detected is obtained. 1 ,...,m P And m 1 <… <m P .

[0083] The calculation expression of step 2 is:

[0084] Among them, m and n represent index variables;

[0085] The calculation expression of step 3 is: or

[0086] The calculation expression of step 5 is: m i is the delay axis index of the i-th path;

[0087] The calculation expression of step 6 is:

[0088] like Figure 4 As shown, step 7 includes: using the average distance minimum compensation process: specifically including:

[0089] Step 71A, according to the Doppler frequency shift κ of each path i , calculate the distance function:

[0090] Step 72A, according to the distance function d i (ε) and the normalized power e of each path i , the average distance function is calculated:

[0091] Step 73A, taking the average distance function d w (ε) The minimum compensation frequency deviation, which is used as the first compensation frequency deviation

[0092] Step 74A, using the first compensation frequency deviation Doppler shift compensation is performed on the received signal.

[0093] The step 71A is specifically as follows:

[0094] d i (ε)=|(κ i -ε)-roun(κ i -ε)|, i = 1, ..., P,

[0095] where ε∈[-0.5, 0.5), round(·) means rounding to the nearest integer; or

[0096] Step 72A is specifically as follows:

[0097] or

[0098] Step 73A is specifically as follows:

[0099]

[0100] like Figure 5 As shown, step 7 includes: using the strongest diameter compensation process, specifically including:

[0101] Step 71b, according to the normalized power of each path, obtain the index i of the strongest path m ; m is

[0102] Step 72b, index i of the strongest path m The corresponding Doppler shift As compensation frequency offset Doppler shift compensation is performed on the received signal.

[0103] The step 71b is specifically as follows:

[0104] like Figure 2 As shown, a multipath Doppler frequency shift estimation device according to the present invention comprises:

[0105] The acquisition unit 21 acquires a preset OTFS orthogonal time-frequency space-delay time domain symbol matrix The size of M, N; obtain the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot;

[0106] Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix;

[0107] m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix;

[0108] The first calculation unit 22 calculates the symbol matrix The size of the preset symbol matrix is ​​calculated to obtain the sequence Where m represents the sequence index;

[0109] The second calculation unit 23, according to the sequence Calculate and obtain the multipath detection threshold γ;

[0110] The detection unit 24 detects the position of the multipath channel path according to the multipath detection threshold γ, and obtains the detected P multipath path positions m 1 , ..., m P ;m 1 <…<m P ; P is the number of multipath paths detected;

[0111] The third calculating unit 25 calculates the multipath path position and the sequence according to the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path;

[0112] The fourth calculation unit 26 calculates the Doppler frequency shift κ of each path according to the detected multipath path position and the symbol matrix. i .

[0113] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0114] A computer-readable storage medium stores a computer program, which implements the steps of the method when executed by a processor.

[0115] The specific application scenarios of the present invention are described below.

[0116] like Figure 3 As shown in the figure, a method for estimating Doppler frequency shift of each path by using pulse pilot according to the present invention comprises:

[0117] Step 31, obtain the received delay time domain symbol matrix Obtain the preset OTFS delay time domain symbol matrix delay length M and Doppler length N, obtain the position of the pulse pilot in the symbol matrix (m p , n p ) and the parameter L for determining the delay domain length of the pulse pilot zero protection zone; m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is the position of the Doppler axis; where m p , n p and L can be set according to actual needs, M and N are the lengths of the delay and time dimensions respectively, which can be set according to actual needs, and the present invention is not limited to this.

[0118] Step 32, according to the preset symbol matrix size M, N, pulse pilot position (m p , n p ) and parameter L, and the received delay time domain symbol matrix Calculation sequence That is to obtain the power distribution of the received time delay domain symbol matrix in the delay dimension, that is to say, The square of the modulus of is summed along the time dimension, and the calculation expression is:

[0119]

[0120] Step 33, according to the sequence Calculate the multipath detection threshold γ, the calculation expression is:

[0121]

[0122] Step 34, detecting the multipath channel position according to the threshold γ, the specific method is: specifying the first path delay l 1 =0 corresponds to the initial pilot position m 1 =m p , and then detect m=m p +1 to m p +L-1 corresponds to Whether it exceeds the threshold γ, the m that exceeds the threshold is the multipath position, and finally the position m of the P paths detected is obtained 1 ,…,m P And m1<…<m P That is to say, the multipath distribution of the received signal is determined according to the detection threshold and the position of the pulse pilot, assuming that the propagation delays of all paths are different;

[0123] Step 35, based on the multipath position and sequence Calculate the normalized power e of each path i , that is, the Doppler frequency shift and the corresponding normalized power of each path are calculated using the pulse pilot.

[0124] Step 36, calculate the Doppler frequency shift κ of each path according to the multipath position and delay time symbol matrix i The present invention provides two Doppler frequency shift compensation methods.

[0125] The first one is: Figure 4 As shown, the average distance minimum compensation method includes compensating a received signal by a frequency offset so that the average value of the Doppler frequency shift of all paths to the nearest integer Doppler distance after corresponding multipath power weighting is minimized; including:

[0126] Step 361A, according to the Doppler frequency shift κ of each path i , calculate the function, that is, calculate the Doppler shift κ of each path i The distance to the nearest integer Doppler frequency shift as a function of the compensation frequency offset ε i (ε)

[0127] d i (ε)=|(κ i -ε)-round(κ i -ε)|, i = 1, ..., P,

[0128] Where ε∈[-0.5, 0.5), round(·) means rounding to the nearest integer; P is the number of multipaths detected.

[0129] Step 362A, according to the d i (ε) and the normalized power e of each path i, the function is calculated. That is, the weighted average distance d from the Doppler frequency shift of all paths to the nearest integer Doppler frequency shift is calculated. w (ε)

[0130] Step 363A, fetch command Minimum compensation frequency deviation;

[0131] Step 363A, using frequency deviation Doppler shift compensation is performed on the received signal.

[0132] The second method uses the strongest diameter compensation method, such as Figure 5 As shown, by compensating the received signal with a frequency offset, the Doppler frequency shift of the path with the strongest power is made an integer. Specifically:

[0133] Step 361B, obtaining the index i of the strongest path according to the normalized power of each path m , that is, search for the path with the largest power among all paths, the expression is:

[0134]

[0135] Step 362B, using the Doppler shift of the strongest path Doppler frequency shift compensation is performed on the received signal. That is, the i-th m The Doppler shift of the path Compensation frequency offset as the strongest path compensation method Used to compensate for the Doppler shift of the received signal.

[0136] In order to solve the problem of system performance degradation caused by fractional Doppler in OTFS system, the present invention proposes an OTFS Doppler frequency shift estimation and compensation method, which has the following beneficial effects:

[0137] The present invention utilizes the property of OTFS pulse pilot to estimate the Doppler frequency shift and power of each path when the multipath delay does not overlap, and compensates for the fractional Doppler in the OTFS system through an average distance minimum compensation method or a strongest path compensation method. The average distance minimum compensation method makes the Doppler of each path as close to an integer as possible, and the strongest path compensation method makes the Doppler of the path with the largest power an integer. Both methods can reduce the energy diffusion of the channel in the delay time domain, reduce inter-symbol interference, improve the complexity of equalization and detection of the OTFS system under the fractional Doppler condition, and enhance the system performance.

[0138] In order to further illustrate the technical effect of the present invention, the simulation results of the present invention are given below. It should be noted that the parameters and settings in the simulation are only exemplary descriptions and are not equivalent to specific limitations of the present invention.

[0139] The carrier center frequency of the wireless communication system is f c =10GHz, sampling rate f s =2MHz, bandwidth B = 2MHz. The power delay spectrum of the channel is shown in Table 1. The OTFS system uses ideal MMSE detection and sets the maximum mobile speed υ max km / h.

[0140] Table 1 Power delay spectrum of the simulated channel

[0141] Power(dB) 0 -1.4 -1.5 -3.6 Delay(ns) 0 370 1730 2510 Normalized delay 0 1 3 5

[0142] Figure 6 is a schematic diagram of a pulse pilot pattern provided by an embodiment of the present invention; Figure 7 The RMSE curve of Doppler frequency shift estimation method proposed in this chapter is shown under different pulse pilot powers. The pilot power xdB is defined as the power of the pulse pilot equal to the average power of the data part. It can be seen that for every 5dB increase in pilot power, the RMSE curve has a gain of about 2.5dB. When the signal-to-noise ratio is 10dB, the RMSE of Doppler estimation is within 0.05, 0.04 and 0.03 respectively when the pilot power is 20dB, 25dB and 30dB.

[0143] Figure 8 The bit error rate curves of the OTFS system under different conditions are shown. It can be seen that when the Doppler frequency shifts of each path are integers, the bit error rate of the system gradually decreases as the signal-to-noise ratio increases. When the Doppler frequency shifts of each path are fractional, the bit error rate curve shows a tail, and the downward trend becomes gentler as the signal-to-noise ratio increases. After using the average distance minimum compensation method, this phenomenon has been improved. When the signal-to-noise ratio is 28dB, the bit error rate of the compensated system is reduced to about 1 / 4 of the original. The effect of using the strongest path compensation method is slightly inferior to the average distance minimum compensation method, and the bit error rate is reduced to about 1 / 3 of the original, but its implementation is simpler.

[0144] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0145] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0146] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for estimating multipath Doppler frequency shift, characterized in that: include: Step 1: Get the preset OTFS orthogonal time-frequency space-delay time domain symbol matrix Dimensions M, N; Get the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot; Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix; m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix; Step 2, according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Where m represents the sequence index; Step 3, according to the sequence Calculate and obtain the multipath detection threshold γ; Step 4: Detect the position of the multipath channel path according to the multipath detection threshold γ, and obtain the detected P multipath path positions m1, ...m P ; m1<… <m P ; P is the number of multipath paths detected; Step 5: based on the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path; Step 6: Calculate the Doppler frequency shift κ of each path based on the detected multipath path position and the symbol matrix. i .

2. The method according to claim 1, characterized in that The method further comprises: Step 7, according to the Doppler frequency shift κ i , and perform Doppler shift compensation.

3. The method according to claim 1, characterized in that The step 4 comprises: Define the initial pilot position m1=m corresponding to the first path delay l1=0 p ; Sequentially detect sequence index m from m p +1 to m p +L-1 corresponding sequence Whether it exceeds the multipath detection threshold γ; The m that exceeds the multipath detection threshold γ is the position of the multipath path, and finally the positions of the P multipath paths detected are m1,...,m P And m1<… <m P .

4. The method according to claim 1, characterized in that The calculation expression of step 2 is: Among them, m and n represent index variables; The calculation expression of step 3 is: or The calculation expression of step 5 is: i=1,...,P; m i is the delay axis index of the ith path, m j is the delay axis index of the j-th path; The calculation expression of step 6 is:

5. The method according to claim 2, characterized in that: The step 7 includes: adopting the average distance minimum compensation process: specifically including: Step 71A, according to the Doppler frequency shift κ of each path i , calculate the distance function: Step 72A, according to the distance function d i (ε) and the normalized power e of each path i , the average distance function is calculated: Step 73A, taking the average distance function d w (ε) The minimum compensation frequency deviation, which is used as the first compensation frequency deviation Step 74A, using the first compensation frequency deviation Doppler shift compensation is performed on the received signal.

6. The method according to claim 5, characterized in that The step 71A is specifically as follows: d i (e)=|(k i -e)-round(k i -e)|,i=1,...,P, where ε∈[-0.5, 0.5), round(·) means rounding to the nearest integer; or Step 72A is specifically as follows: Step 73A is specifically as follows:

7. The method according to claim 2, characterized in that The step 7 includes: using the strongest diameter compensation process, specifically including: Step 71b, according to the normalized power of each path, obtain the index i of the strongest path m ;;Subscript m means max; Step 72b, index i of the strongest path m The corresponding Doppler shift As compensation frequency offset Doppler shift compensation is performed on the received signal.

8. The method according to claim 7, characterized in that The step 71b is specifically as follows:

9. A multipath Doppler shift estimation device, characterized in that: include: Acquisition unit, obtains the preset OTFS orthogonal time-frequency space-delay time domain symbol matrix Dimensions M, N; Get the position of the pulse pilot in the symbol matrix (m p , n p ); and determining a zero protection zone delay domain length parameter L of the pulse pilot; Wherein, M is the time extension length of the symbol matrix; N is the Doppler length of the symbol matrix; m p is the preset position of the pulse pilot on the delay axis in the symbol matrix; n p is a preset position of the Doppler axis of the pulse pilot in the symbol matrix; The first calculation unit, according to the symbol matrix The size of the preset symbol matrix M, N, the sequence is calculated Where m represents the sequence index; The second computing unit, according to the sequence Calculate and obtain the multipath detection threshold γ; The detection unit detects the position of the multipath channel path according to the multipath detection threshold γ, and obtains the detected P multipath path positions m1, ..., m P ; m1<…<m P ; P is the number of multipath paths detected; The third calculating unit is configured to calculate the multipath path position and the sequence according to the detected multipath path position and the sequence Calculate the normalized power e of each path i ; where i is the path index; e i is the normalized power of the i-th path; The fourth calculation unit calculates the Doppler frequency shift κ of each path according to the detected multipath path position and the symbol matrix. i .

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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