Orthogonal frequency division multiplexing system channel estimation method and system in high-speed mobile multipath environment

Abstract

The invention provides an orthogonal frequency division multiplexing system channel estimation method and system in a high-speed mobile multipath environment, and belongs to the technical field of communication. Time domain and frequency domain pilot frequency sampling interval numbers are configured; according to the configured pilot frequency interval number, sampling data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at a pilot frequency position; transforming the time-frequency domain channel estimation value to a time delay Doppler domain, and estimating a time delay Doppler domain channel according to the stability and compactness of the time delay Doppler domain channel; and converting the estimated time delay Doppler domain channel back to a time-frequency domain to obtain a time-frequency domain channel at a non-pilot frequency position of the orthogonal frequency division multiplexing system, and completing channel estimation of the orthogonal frequency division multiplexing system. According to the method, estimation errors generated when channel estimation is directly carried out on a time-frequency domain fast fading channel can be resisted by utilizing the quasi-invariant characteristic of a time delay Doppler domain channel in the high-speed mobile multipath environment, and the channel estimation precision of an orthogonal frequency division multiplexing system in the high-speed mobile multipath environment is improved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to an orthogonal frequency division multiplexing system channel estimation method and system in a high-speed mobile multipath environment. Background Art

[0002] Orthogonal frequency division multiplexing (OFDM) has been widely used in 4G, WiFi, and 5G systems, and is expected to continue to be used in 6G and future mobile communication networks. However, the high-speed mobile multipath communication environment that will appear in future 6G and other communication systems poses challenges to OFDM. In particular, Doppler shift introduces inter-carrier interference (ICI) and causes fast channel fading, complicating the accurate estimation of the channel's time-frequency (TF) domain response - the channel transfer function (CTF).

[0003] In order to support the realization of reliable CTF estimation, several estimators exist in current OFDM systems, including interpolation-based estimators, minimum mean square error (MMSE) estimators, and machine learning-based estimators. However, interpolation-based estimators may have limited accuracy under fast fading CTF, MMSE estimators require channel statistics that are difficult to obtain, and machine learning methods rely on a large amount of training data and may not be generalized to different channel conditions.

[0004] Recently, researchers have proposed the Delay-Doppler (DD) Domain Multi-Carrier (DDMC) scheme, which can provide higher reliability in high mobility scenarios compared to OFDM. This is because the DDMC scheme is designed based on the DD domain response of the channel, the channel spread function (CSF). Unlike the CTF, which is usually considered invariant only in the coherent region, the CSF can be considered quasi-invariant in the stationary region larger than the coherent region.

[0005] Therefore, by utilizing the stationarity of CSF, the CSF can be estimated using scattered pilots in the OFDM system, and then the CTF of the data symbol can be estimated based on the estimated CSF. Summary of the invention

[0006] The object of the present invention is to provide a channel estimation method and system for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment, so as to solve at least one technical problem existing in the above-mentioned background technology.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an orthogonal frequency division multiplexing system channel estimation method in a high-speed mobile multipath environment, comprising:

[0009] Configure the number of pilot sampling intervals in the time domain and frequency domain;

[0010] According to the configured pilot interval number, sampling is performed from the data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at the pilot position;

[0011] The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, and the delay-Doppler domain channel is estimated according to the stability and compactness of the delay-Doppler domain channel;

[0012] The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

[0013] Furthermore, the number of pilot sampling intervals in the time domain and frequency domain is configured, including:

[0014] Define the number of subcarriers in the OFDM system under consideration as M, the number of OFDM symbols as N, the subcarrier spacing as Δf, and the OFDM symbol length as T. Then there are N×M time-frequency domain elements in the OFDM system, and the pilot sampling interval in the frequency domain is configured as d f , the pilot sampling interval in the time domain is d t , then for the pilot symbol there exists mod(n,d t )=0,mod(m,d t )=0, where m=0,1,…,M-1 and n=0,1,…,N-1 are the resource grid numbers of the symbol in the frequency domain and time domain respectively.

[0015] Further, sampling to obtain a time-frequency domain channel estimation value at the pilot position includes:

[0016]

[0017] Where m = 0, 1, ..., M-1 and n = 0, 1, ..., N-1 represent the sequence number of the time-frequency domain resource grid. represents the channel fading value in the time-frequency domain at N×M grid points, represents the time-frequency domain channel estimation value at the pilot position; considering that the number of multipaths in the high-speed mobile multipath environment experienced by the OFDM system is P, the multipath sequence is i=1,…,P, and the fading of the i-th multipath is h i , the delay is τ i , Doppler is v i ,but for:

[0018]

[0019] Further, the obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, including:

[0020]

[0021] Where k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the sequence number of the delay-Doppler domain resource grid, l i =MΔfτ i and k i =NTν i represents the normalized delay and Doppler of the i-th multipath, and represents the scale factor, DFT N {·} and IDFT M {·} denotes N-point discrete Fourier transform and M-point inverse discrete Fourier transform operations, respectively.

[0022] Furthermore, according to the stability and compactness of the delay-Doppler domain channel, the delay-Doppler domain channel is estimated, including:

[0023] When the normalized delay l i and Doppler k i When it is an integer:

[0024] When the delay-Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, it can be directly One cycle of is regarded as the estimation of the system delay Doppler channel, that is:

[0025]

[0026] Normalized delay l i is an integer, normalized Doppler k i When it is a non-integer:

[0027] When the delay-Doppler domain channel satisfies the compactness condition and τ i ∈ When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, the estimation of the multipath number, multipath fading, delay, and Doppler can be calculated and estimated. Then we can directly obtain the estimation of the delay Doppler channel:

[0028]

[0029] Furthermore, the estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the OFDM system, including:

[0030] Perform a two-dimensional Fourier transform operation on the delay-Doppler domain channel estimate to obtain:

[0031]

[0032] IDFT N {·} and DFT M {·} respectively represent N-point inverse discrete Fourier transform and M-point discrete Fourier transform operations. So far, the time-frequency domain channel estimation value corresponding to the non-pilot position is obtained.

[0033] In a second aspect, the present invention provides an orthogonal frequency division multiplexing system channel estimation system in a high-speed mobile multipath environment, comprising:

[0034] A configuration module is used to configure the number of pilot sampling intervals in the time domain and frequency domain;

[0035] A module is used to sample the data received by the orthogonal frequency division multiplexing system according to the configured pilot interval number to obtain the time-frequency domain channel estimation value at the pilot position;

[0036] An estimation module, used for transforming the obtained time-frequency domain channel estimation value into a delay-Doppler domain, and estimating the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel;

[0037] The conversion module is used to convert the estimated delay Doppler domain channel back to the time-frequency domain, obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, and complete the channel estimation of the orthogonal frequency division multiplexing system.

[0038] In a third aspect, the present invention provides a non-transitory computer-readable storage medium, which is used to store computer instructions. When the computer instructions are executed by a processor, the channel estimation method of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in the first aspect is implemented.

[0039] In a fourth aspect, the present invention provides a computer device comprising a memory and a processor, wherein the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in the first aspect.

[0040] In a fifth aspect, the present invention provides an electronic device, comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes instructions for implementing the channel estimation method of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in the first aspect.

[0041] The beneficial effects of the present invention are as follows: in a high-speed mobile multipath environment, the quasi-invariant CSF can be used to reduce the error of directly estimating the fast-changing CTF, and a more accurate CTF channel estimation value can be obtained, thereby providing a channel estimation basis for realizing reliable transmission of the OFDM system in a high-speed mobile multipath environment.

[0042] Additional advantages of the present invention will be more clearly presented in the following description or learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0044] Figure 1 The present invention is a flowchart of a method for channel estimation of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment according to an embodiment of the present invention.

[0045] Figure 2 It is a schematic diagram of configuring the number of pilot sampling intervals in the time domain and frequency domain according to an embodiment of the present invention.

[0046] Figure 3 It is a schematic diagram showing the comparison of mean square error performance of the present invention compared with the estimator based on linear interpolation and the minimum mean square error estimator when the normalized delay and Doppler are both integers.

[0047] Figure 4 It is a schematic diagram showing the comparison of the bit error rate performance of the present invention compared with the estimator based on linear interpolation and the minimum mean square error estimator when the normalized delay and Doppler are both integers.

[0048] Figure 5 It is a schematic diagram showing the comparison of mean square error performance of the present invention compared with the estimator based on linear interpolation and the minimum mean square error estimator when the normalized delay is an integer and the normalization and Doppler are non-integer.

[0049] Figure 6 It is a schematic diagram showing the comparison of the bit error rate performance of the present invention compared with the estimator based on linear interpolation and the minimum mean square error estimator when the normalized delay is an integer and the normalization and Doppler are non-integer. DETAILED DESCRIPTION

[0050] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below by the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0051] It should be understood by those skilled in the art that unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.

[0052] It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have a meaning consistent with that in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless as defined herein.

[0053] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or groups thereof.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. Different embodiments or examples described in this specification and features of different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

[0055] To facilitate understanding of the present invention, the present invention is further explained below with reference to specific embodiments in conjunction with the accompanying drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0056] Those skilled in the art should understand that the drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily necessary for implementing the present invention.

[0057] Example 1

[0058] In this embodiment 1, first, a channel estimation system for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment is provided, including: a configuration module, used to configure the number of pilot sampling intervals in the time domain and frequency domain; an adoption module, used to sample the data received by the orthogonal frequency division multiplexing system according to the configured number of pilot intervals to obtain a time-frequency domain channel estimation value at the pilot position; an estimation module, used to transform the obtained time-frequency domain channel estimation value into a delay Doppler domain, and estimate the delay Doppler domain channel according to the stability and compactness of the delay Doppler domain channel; a conversion module, used to convert the estimated delay Doppler domain channel back to the time-frequency domain, obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, and complete the channel estimation of the orthogonal frequency division multiplexing system.

[0059] In this embodiment, the above-mentioned system is used to implement a channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment, including: configuring the number of pilot sampling intervals in the time domain and frequency domain; sampling the data received by the orthogonal frequency division multiplexing system according to the configured number of pilot intervals to obtain a time-frequency domain channel estimation value at the pilot position; transforming the obtained time-frequency domain channel estimation value to the delay Doppler domain, and estimating the delay Doppler domain channel based on the stability and compactness of the delay Doppler domain channel; converting the estimated delay Doppler domain channel back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

[0060] Configure the time domain and frequency domain pilot sampling intervals, including:

[0061] Define the number of subcarriers in the OFDM system under consideration as M, the number of OFDM symbols as N, the subcarrier spacing as Δf, and the OFDM symbol length as T. Then there are N×M time-frequency domain elements in the OFDM system, and the pilot sampling interval in the frequency domain is configured as d f , the pilot sampling interval in the time domain is d t , then for the pilot symbol there exists mod(n,d t )=0,mod(m,d t )=0, where m=0,1,…,M-1 and n=0,1,…,N-1 are the resource grid numbers of the symbol in the frequency domain and time domain respectively.

[0062] The time-frequency domain channel estimation value at the pilot position is obtained by sampling, including:

[0063] Where m = 0, 1, ..., M-1 and n = 0, 1, ..., N-1 represent the sequence number of the time-frequency domain resource grid. represents the channel fading value in the time-frequency domain at N×M grid points, represents the time-frequency domain channel estimation value at the pilot position; considering that the number of multipaths in the high-speed mobile multipath environment experienced by the OFDM system is P, the multipath sequence is i=1,…,P, and the fading of the i-th multipath is h i , the delay is τ i , Doppler is v i ,but for:

[0064]

[0065] The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, including:

[0066]

[0067] Where k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the sequence number of the delay-Doppler domain resource grid, l i =MΔfτ i and k i =NTv i represents the normalized delay and Doppler of the i-th multipath, and represents the scale factor, DFT N {·} and IDFT M {·} denotes N-point discrete Fourier transform and M-point inverse discrete Fourier transform operations, respectively.

[0068] According to the stability and compactness of the delay-Doppler domain channel, the delay-Doppler domain channel is estimated, including:

[0069] When the normalized delay l i and Doppler k i When it is an integer:

[0070] When the delay-Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, it can be directly One cycle of is regarded as the estimation of the system delay Doppler channel, that is:

[0071]

[0072] Normalized delay l i is an integer, normalized Doppler k i When it is a non-integer:

[0073] When the delay-Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, the estimation of the multipath number, multipath fading, delay, and Doppler can be calculated and estimated. Then we can directly obtain the estimation of the delay Doppler channel:

[0074]

[0075] The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the OFDM system, including:

[0076] Perform a two-dimensional Fourier transform operation on the delay-Doppler domain channel estimate to obtain:

[0077]

[0078] IDFT N} and DFT M {·} respectively represent N-point inverse discrete Fourier transform and M-point discrete Fourier transform operations. So far, the time-frequency domain channel estimation value corresponding to the non-pilot position is obtained.

[0079] Example 2

[0080] In this embodiment 2, a channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment is provided, which can use the quasi-invariant CSF to reduce the error of directly estimating the fast-changing CTF, obtain a more accurate CTF channel estimation value, and thus provide a channel estimation basis for achieving reliable transmission of the OFDM system in a high-speed mobile multipath environment.

[0081] like Figure 1 As shown, a channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment comprises:

[0082] Step 1: Configure the time domain and frequency domain pilot sampling intervals;

[0083] Step 2, sampling the data received by the OFDM system according to the configured pilot interval number to obtain the time-frequency domain channel estimation value at the pilot position;

[0084] Step 3, transforming the obtained time-frequency domain channel estimation value into the delay-Doppler domain, and estimating the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel;

[0085] Step 4: Convert the estimated delay-Doppler domain channel back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the OFDM system, thereby completing the OFDM system channel estimation.

[0086] Among them, the "configuring the number of time domain and frequency domain pilot sampling intervals" in step 1 includes:

[0087] Define the number of subcarriers in the OFDM system under consideration as M, the number of OFDM symbols as N, the subcarrier spacing as Δf, and the OFDM symbol length as T. Therefore, there are a total of NM time-frequency domain elements in the OFDM system. Figure 2 As shown, the pilot sampling interval (i.e., the distance between two adjacent pilot symbols) in the frequency domain is configured as d f The pilot sampling interval in the time domain (i.e., the distance between two pilot symbols) is d t Then for the pilot symbol there exists mod(n,d t )=0,mod(m,d t )=0, where m=0,1,…,M-1 and n=0,1,…,N-1 are the resource grid numbers of the symbol in the frequency domain and time domain respectively.

[0088] The "sampling to obtain a time-frequency domain channel estimation value at the pilot position" in step 2 includes:

[0089]

[0090] Wherein m=0,1,…,M-1 and n=0,1,…,N-1 represent the sequence numbers of the time-frequency domain resource grids. represents the channel fading value in the time-frequency domain at NM grid points, In addition, considering the high-speed mobile multipath environment experienced by the OFDM system, the number of multipaths is P, the multipath sequence is i=1,…,P, and the fading of the i-th multipath is h i , the delay is τ i , Doppler is v i ,but Can write

[0091]

[0092] The step 3 of "transforming the obtained time-frequency domain channel estimation value into the delay-Doppler domain" includes performing a two-dimensional Fourier transform operation on (2), which is expanded into:

[0093]

[0094] Where k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the sequence number of the delay-Doppler domain resource grid. i =MΔfτ i and k i =NTν i represents the normalized delay and Doppler of the i-th multipath. and represents the scale factor. Note that the value obtained in step 3 is The delay-Doppler domain is periodic, so the “Periodic” annotation is used and expressed as:

[0095]

[0096] in,

[0097] The step 3 of “estimating the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel” includes:

[0098] Two examples are provided below.

[0099] Example 1: Normalized delay l i and Doppler k i When it is an integer.

[0100] When 1) the delay-Doppler domain channel satisfies the compactness condition and and 2) when the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, it can be directly One cycle of is regarded as the estimation of the system delay Doppler channel, that is:

[0101]

[0102] in, is the estimation of (3), which can be easily obtained according to the estimation of (1). The present invention does not make specific requirements on the estimation method of (1). So far, in Example 1, the estimation of the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel has been completed.

[0103] Example 2: Normalized delay l i is an integer, normalized Doppler k i When it is a non-integer.

[0104] When 1) the delay-Doppler domain channel satisfies the compactness condition and and 2) when the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, the estimation of the multipath number, multipath fading, delay, and Doppler can be obtained according to the algorithm designed in (3) Then the estimation of delay-Doppler channel is directly obtained.

[0105]

[0106] This embodiment provides the following: "According to (3) designing an algorithm to estimate the number of multipaths, multipath fading, delay, and Doppler " Algorithm implementation example:

[0107] Step 31: Obtain according to any energy threshold i=0;

[0108] Step 32: For the i-th multipath, find Conditional, so that The largest k and l values ​​are denoted as k0,l0;

[0109] Step 33: Find k∈{k0-1,k0+1} such that The largest k value is denoted as k'0;

[0110] Step 34: Get for

[0111] Step 35: Get for

[0112] Step 36: Get

[0113] Step 37: For l = l0, k = 0, 1, ..., M-1, let

[0114] According to steps 31-37, it is easy to get the estimation of multipath number, multipath fading, delay and Doppler Finally, it is substituted into (6). So far, in Example 2, the delay-Doppler domain channel is estimated according to the stationarity and compactness of the delay-Doppler domain channel.

[0115] To this end, based on Example 1 and Example 2, the present method can be applied to normalized delays and Doppler conditions of different systems, and can estimate the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel.

[0116] Step 4 of "converting the estimated delay-Doppler domain channel back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the OFDM system" includes:

[0117] Performing a two-dimensional Fourier transform operation on the delay-Doppler domain channel estimate obtained by (5) or (6) yields:

[0118]

[0119] So far, we can get from (7) the corresponding Figure 2 In the non-pilot position (i.e. mod(n,d t )≠0,mod(m,d t)≠0) is the time-frequency domain channel estimation value.

[0120] Figure 3 and Figure 4 The following are the MSE comparison diagram and BER diagram of the OFDM system channel estimation method in a high-speed mobile multipath environment provided by this embodiment and the MSE comparison diagram based on the traditional linear interpolation and minimum mean square error estimator when the normalized delay is an integer and the Doppler is a non-integer. With h TF The average square interpolation of [m,n] is called the mean square error MSE, and the bit difference ratio between the transmitted bit and the demodulated bit is called the bit error rate BER. The scenario considered is the vehicle network communication scenario, M=128, N=64, The maximum speed of the moving body is 250km / h, Figure 2 The time and frequency domain sampling intervals in are set to d t =4,d f =4, the number of multipaths is P=5, and the modulation method is QPSK.

[0121] First, if Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown in the figure, the proposed method outperforms the linear interpolation method in terms of both MSE and BER. The linear interpolation method suffers from an error floor of MSE and BER in the high SNR region because it is difficult to adapt to the fast time-varying characteristics of the channel fading in the time-frequency domain. In contrast, the proposed method effectively utilizes the time-invariance of the delay-Doppler domain channel, achieves accurate channel estimation in the time-frequency domain, and realizes reliable data transmission.

[0122] Secondly, if Figure 3 and Figure 4 As shown, when the normalized Doppler and the delay are both integers, according to the method of Example 1 in Embodiment 2, the MSE of this method is almost the same as the MSE of the linear optimal estimator in the high SNR region, namely, the MMSE estimator. It is worth noting that this method has lower complexity than the MMSE estimator and does not require the receiver to obtain statistical information of the channel.

[0123] In addition, if Figure 5 and Figure 6 As shown, when the normalized Doppler is non-integer, according to the method of steps 31-37 of Example 2 in Example 2, the MSE of this method is somewhat different from that of the MMSE estimator, but the BER is almost the same as that of the MMSE estimator. In addition, steps 31-37 of Example 2 in Example 2 are only "estimation of the number of multipaths, multipath fading, delay, and Doppler obtained by designing an algorithm according to (3)". "The algorithm embodiment, through other methods, the MSE performance under this condition can be further improved to the same level as Figure 3 similar level.

[0124] To this end, it can be found that in a high-speed mobile multipath environment, this method can utilize the stationary characteristics of the dual-selection channel to provide MSE and BER performance that is far superior to the linear interpolation estimator and close to the optimal estimator (MMSE estimator), without the need for channel statistical prior information and with lower complexity, and has greater potential for application in OFDM communication systems in actual high-speed mobile multipath environments.

[0125] Example 3

[0126] This embodiment 3 provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the channel estimation method of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described above is implemented. The method includes:

[0127] Configure the number of pilot sampling intervals in the time domain and frequency domain;

[0128] According to the configured pilot interval number, sampling is performed from the data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at the pilot position;

[0129] The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, and the delay-Doppler domain channel is estimated according to the stability and compactness of the delay-Doppler domain channel;

[0130] The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

[0131] Example 4

[0132] This embodiment 4 provides a computer device, including a memory and a processor, the processor and the memory communicate with each other, the memory stores program instructions executable by the processor, the processor calls the program instructions to execute the above-mentioned orthogonal frequency division multiplexing system channel estimation method in a high-speed mobile multipath environment, the method comprising:

[0133] Configure the number of pilot sampling intervals in the time domain and frequency domain;

[0134] According to the configured pilot interval number, sampling is performed from the data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at the pilot position;

[0135] The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, and the delay-Doppler domain channel is estimated according to the stability and compactness of the delay-Doppler domain channel;

[0136] The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

[0137] Example 5

[0138] This embodiment 5 provides an electronic device, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes instructions for implementing the above-mentioned orthogonal frequency division multiplexing system channel estimation method in a high-speed mobile multipath environment, the method comprising:

[0139] Configure the number of pilot sampling intervals in the time domain and frequency domain;

[0140] According to the configured pilot interval number, sampling is performed from the data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at the pilot position;

[0141] The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, and the delay-Doppler domain channel is estimated according to the stability and compactness of the delay-Doppler domain channel;

[0142] The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

[0143] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0144] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0145] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0146] These computer program instructions can also be loaded onto a computer or other programmable data processing device, and a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0147] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative work on the basis of the technical solution disclosed in the present invention should be included in the scope of protection of the present invention.

Claims

1. A channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment, characterized in that: include: Configure the number of pilot sampling intervals in the time domain and frequency domain; According to the configured pilot interval number, sampling is performed from the data received by the orthogonal frequency division multiplexing system to obtain a time-frequency domain channel estimation value at the pilot position; The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, and the delay-Doppler domain channel is estimated according to the stability and compactness of the delay-Doppler domain channel; The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, thereby completing the channel estimation of the orthogonal frequency division multiplexing system.

2. The channel estimation method of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment according to claim 1, characterized in that: Configure the time domain and frequency domain pilot sampling intervals, including: Define the number of subcarriers in the OFDM system under consideration as M, the number of OFDM symbols as N, the subcarrier spacing as Δf, and the OFDM symbol length as T. Then there are N×M time-frequency domain elements in the OFDM system, and the pilot sampling interval in the frequency domain is configured as d f , the pilot sampling interval in the time domain is d t , then for the pilot symbol there exists mod(n, d t )=0,mod(m,d t )=0, where m=0, 1, ..., M-1 and n=0, 1, ..., N-1 are the resource grid numbers of the symbol in the frequency domain and the time domain respectively.

3. The channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment according to claim 1, characterized in that: The time-frequency domain channel estimation value at the pilot position is obtained by sampling, including: Where m=0, 1, ..., M-1 and n=0, 1, ..., N-1 represent the sequence number of the resource grid in the time-frequency domain. represents the channel fading value in the time-frequency domain at N×M grid points, represents the time-frequency domain channel estimation value at the pilot position; considering that the number of multipaths in the high-speed mobile multipath environment experienced by the OFDM system is P, the multipath sequence is i=1,...,P, and the fading of the i-th multipath is h i , the delay is τ i , Doppler is v i ,but for:

4. The channel estimation method for an OFDM system in a high-speed mobile multipath environment according to claim 3, characterized in that: The obtained time-frequency domain channel estimation value is transformed into the delay-Doppler domain, including: Where k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the sequence number of the delay-Doppler domain resource grid, l i =MΔfτ i and k i =NTv i represents the normalized delay and Doppler of the ith multipath, and Represents the scale factor, DFT N {·} and IDFT M {·} denotes N-point discrete Fourier transform and M-point inverse discrete Fourier transform operations, respectively.

5. The channel estimation method for an OFDM system in a high-speed mobile multipath environment according to claim 4, characterized in that: According to the stability and compactness of the delay-Doppler domain channel, the delay-Doppler domain channel is estimated, including: When the normalized delay l i and Doppler k i When it is an integer: When the delay-Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, it can be directly One cycle of is regarded as the estimation of the system delay Doppler channel, that is: Normalized delay l i is an integer, normalized Doppler k i When it is a non-integer: When the delay-Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationary condition within the NT time and MΔf bandwidth, the estimation of the multipath number, multipath fading, delay, and Doppler can be calculated and estimated. Then we can directly obtain the estimation of the delay Doppler channel:

6. The channel estimation method for an OFDM system in a high-speed mobile multipath environment according to claim 5, characterized in that: The estimated delay-Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot position of the OFDM system, including: Perform a two-dimensional Fourier transform operation on the delay-Doppler domain channel estimate to obtain: IDFT N {·} and DFT M {·} represents N-point inverse discrete Fourier transform and M-point discrete Fourier transform operations respectively. Thus, the time-frequency domain channel estimation value corresponding to the non-pilot position is obtained.

7. An orthogonal frequency division multiplexing system channel estimation system in a high-speed mobile multipath environment, characterized in that: include: A configuration module is used to configure the number of pilot sampling intervals in the time domain and frequency domain; A module is used to sample the data received by the orthogonal frequency division multiplexing system according to the configured pilot interval number to obtain the time-frequency domain channel estimation value at the pilot position; An estimation module, used for transforming the obtained time-frequency domain channel estimation value into a delay-Doppler domain, and estimating the delay-Doppler domain channel according to the stability and compactness of the delay-Doppler domain channel; The conversion module is used to convert the estimated delay Doppler domain channel back to the time-frequency domain, obtain the time-frequency domain channel at the non-pilot position of the orthogonal frequency division multiplexing system, and complete the channel estimation of the orthogonal frequency division multiplexing system.

8. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by the processor, the channel estimation method of the orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in any one of claims 1-6 is implemented.

9. A computer device, characterized in that: It includes a memory and a processor, the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the orthogonal frequency division multiplexing system channel estimation method in a high-speed mobile multipath environment as described in any one of claims 1-6.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes instructions for implementing the channel estimation method of an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in any one of claims 1-6.

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