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

Abstract

This invention provides a channel estimation method and system for an orthogonal frequency division multiplexing (OFDM) system in a high-speed mobile multipath environment, belonging to the field of communication technology. The method involves configuring the number of time-domain and frequency-domain pilot sampling intervals; sampling the data received by the OFDM system at the pilot positions according to the configured pilot intervals to obtain time-frequency domain channel estimates; transforming the time-frequency domain channel estimates to the time-delay Doppler domain; estimating the time-delay Doppler domain channel based on its stationarity and compactness; and converting the estimated time-delay Doppler domain channel back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot positions of the OFDM system, thus completing the OFDM system channel estimation. This invention utilizes the quasi-invariant characteristics of the time-delay Doppler domain channel in a high-speed mobile multipath environment to counteract estimation errors when directly estimating the channel of fast-fading channels in the time-frequency domain, thereby improving the channel estimation accuracy of the OFDM system in a high-speed mobile multipath environment.

Description

Technical Field

[0001] This invention relates to the field of communication technology, specifically to a channel estimation method and system for orthogonal frequency division multiplexing systems in high-speed mobile multipath environments. Background Technology

[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 emerge in future 6G and other communication systems poses challenges to OFDM. In particular, Doppler frequency shift introduces inter-carrier interference (ICI) and leads to rapid channel fading, complicating the accurate estimation of the channel's time-frequency (TF) domain response—the channel transfer function (CTF).

[0003] To support reliable CTF estimation, several estimators currently available for OFDM systems include 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, which rely on large amounts of training data, may not generalize to different channel conditions.

[0004] Recently, researchers proposed the Delay-Doppler (DD) Domain Multicarrier (DDMC) scheme, which offers higher reliability in high-mobility scenarios compared to OFDM. This is because the DDMC scheme is designed based on the channel's DD domain response—the Channel Spread Function (CSF). Unlike the CTF, which is typically considered invariant only within the coherent region, the CSF can be considered quasi-invariant in a stationary region larger than the coherent region.

[0005] Therefore, by taking advantage of the stationarity of the CSF, the CSF can be estimated using discrete pilots in an OFDM system, and then the CTF of the data symbols can be estimated based on the estimated CSF. Summary of the Invention

[0006] The purpose of this invention is to provide a channel estimation method and system for orthogonal frequency division multiplexing systems in high-speed mobile multipath environments, so as to solve at least one of the technical problems existing in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

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

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

[0010] Based on the configured number of pilot intervals, the time-frequency domain channel estimate at the pilot position is obtained by sampling from the data received by the orthogonal frequency division multiplexing system;

[0011] The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain. Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated.

[0012] The estimated time-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, thus completing the channel estimation of the orthogonal frequency division multiplexing system.

[0013] Furthermore, configure the number of time-domain and frequency-domain pilot sampling intervals, including:

[0014] Let M be the number of subcarriers in the OFDM system under consideration, N be the number of OFDM symbols, Δf be the subcarrier spacing, and T be the OFDM symbol length. Then, the OFDM system has N×M time-frequency domain elements, 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 pilot symbols, 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] Furthermore, the time-frequency domain channel estimate at the pilot location is obtained by sampling, including:

[0016]

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

[0018]

[0019] Furthermore, the obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain, including:

[0020]

[0021] In the formula, k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the serial numbers of the time-delay Doppler domain resource grids, and l i =MΔfτ i and k i =NTν i Let the normalized delay and Doppler of the i-th multipath be represented. and DFT represents the scaling factor. N {·} and IDFT M {·} represent the N-point Discrete Fourier Transform and the M-point Inverse Discrete Fourier Transform operations, respectively.

[0022] Furthermore, based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated, including:

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

[0024] At that time, the Doppler domain channel satisfied the compactness condition. and When the time-delay Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, it can be directly... One period is considered as an estimate of the system's time delay Doppler channel, that is:

[0025]

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

[0027] At that time, the Doppler domain channel satisfied the compactness condition. and τ i ∈ When the Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, estimates of the number of multipath paths, multipath fading, time delay, and Doppler effect can be calculated and obtained. This directly yields an estimate of the time-delay Doppler channel:

[0028]

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

[0030] Performing a two-dimensional Fourier transform operation on the obtained time-delay Doppler domain channel estimate yields:

[0031]

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

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

[0034] The configuration module is used to configure the number of pilot sampling intervals in the time and frequency domains.

[0035] A module is used to sample the time-frequency domain channel estimate at the pilot position from the data received by the orthogonal frequency division multiplexing system according to the configured number of pilot intervals;

[0036] The estimation module is used to transform the obtained time-frequency domain channel estimate to the time-delay Doppler domain, and estimate the time-delay Doppler domain channel based on the stationarity and compactness of the time-delay Doppler domain channel.

[0037] The conversion module is used to convert the estimated time-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, thus completing the channel estimation of the orthogonal frequency division multiplexing system.

[0038] Thirdly, the present invention provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in the first aspect.

[0039] Fourthly, the present invention provides a computer device including a memory and a processor, wherein the processor and the memory communicate with each other, the memory stores program instructions executable 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] Fifthly, the present invention provides an electronic device, comprising: 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 to cause the electronic device to execute instructions for implementing the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in the first aspect.

[0041] The beneficial effects of this invention are: in high-speed mobile multipath environments, the quasi-invariant CSF can be used to reduce the error of directly estimating the rapidly changing CTF, and a more accurate CTF channel estimate can be obtained, thereby providing a channel estimation basis for realizing reliable transmission of OFDM systems in high-speed mobile multipath environments.

[0042] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment, as described in an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram illustrating the configuration of time-domain and frequency-domain pilot sampling intervals as described in an embodiment of the present invention.

[0046] Figure 3 The diagram shows a comparison of the mean square error performance of this invention with linear interpolation-based estimators and minimum mean square error estimators when both the normalized time delay and Doppler are integers.

[0047] Figure 4 This diagram illustrates the bit error rate performance comparison between the present invention and estimators based on linear interpolation and minimum mean square error estimators when both normalized delay and Doppler are integers.

[0048] Figure 5 The diagram illustrates the mean square error performance comparison between the present invention and estimators based on linear interpolation and minimum mean square error estimators when the normalized time delay is an integer, normalized, and Doppler non-integer.

[0049] Figure 6 The diagram illustrates the bit error rate performance comparison between the present invention and estimators based on linear interpolation and least mean square error estimators when the normalized delay is an integer, normalized, and Doppler non-integer. Detailed Implementation

[0050] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

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

[0052] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0053] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated 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, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0055] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, 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 accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0057] Example 1

[0058] In this embodiment 1, a channel estimation system for an orthogonal frequency division multiplexing (OFDM) system under high-speed mobile multipath environment is first provided, including: a configuration module for configuring the number of time-domain and frequency-domain pilot sampling intervals; an sampling module for sampling the time-frequency domain channel estimate at the pilot position from the data received by the OFDM system according to the configured number of pilot intervals; an estimation module for transforming the obtained time-frequency domain channel estimate to the time-delay Doppler domain, and estimating the time-delay Doppler domain channel based on the stationarity and compactness of the time-delay Doppler domain channel; and a conversion module for converting the estimated time-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, thus completing the channel estimation of the OFDM system.

[0059] In this embodiment, the above-described system is used to implement a channel estimation method for an orthogonal frequency division multiplexing (OFDM) system in a high-speed mobile multipath environment. The method includes: configuring the number of time-domain and frequency-domain pilot sampling intervals; sampling the data received by the OFDM system at the pilot positions according to the configured pilot intervals to obtain time-frequency domain channel estimates; transforming the obtained time-frequency domain channel estimates to the time-delay Doppler domain; estimating the time-delay Doppler domain channel based on the stationarity and compactness of the time-delay Doppler domain channel; and converting the estimated time-delay Doppler domain channel back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot positions of the OFDM system, thus completing the OFDM system channel estimation.

[0060] Configure the number of pilot sampling intervals in the time and frequency domains, including:

[0061] Let M be the number of subcarriers in the OFDM system under consideration, N be the number of OFDM symbols, Δf be the subcarrier spacing, and T be the OFDM symbol length. Then, the OFDM system has N×M time-frequency domain elements, 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 pilot symbols, 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 estimate obtained at the pilot location is as follows:

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

[0064]

[0065] The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain, including:

[0066]

[0067] In the formula, k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the serial numbers of the time-delay Doppler domain resource grids, and l i =MΔfτ i and k i =NTv i Let the normalized delay and Doppler of the i-th multipath be represented. and DFT represents the scaling factor. N {·} and IDFT M {·} represent the N-point Discrete Fourier Transform and the M-point Inverse Discrete Fourier Transform operations, respectively.

[0068] Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated, including:

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

[0070] At that time, the Doppler domain channel satisfied the compactness condition. and When the time-delay Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, it can be directly... One period is considered as an estimate of the system's time delay Doppler channel, that is:

[0071]

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

[0073] At that time, the Doppler domain channel satisfied the compactness condition. and When the Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, estimates of the number of multipath paths, multipath fading, time delay, and Doppler effect can be calculated and obtained. This directly yields an estimate of the time-delay Doppler channel:

[0074]

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

[0076] Performing a two-dimensional Fourier transform operation on the obtained time-delay Doppler domain channel estimate yields:

[0077]

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

[0079] Example 2

[0080] In this embodiment 2, a channel estimation method for an orthogonal frequency division multiplexing (OFDM) system under high-speed mobile multipath environment is provided. The method can use the quasi-invariant CSF to reduce the error of directly estimating the fast-changing CTF, and obtain a more accurate CTF channel estimate, thereby providing a channel estimation basis for realizing reliable transmission of OFDM system under 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 includes:

[0082] Step 1: Configure the number of pilot sampling intervals in the time and frequency domains;

[0083] Step 2: Sample the time-frequency domain channel estimate at the pilot position from the data received by the OFDM system according to the configured pilot spacing;

[0084] Step 3: Transform the obtained time-frequency domain channel estimate to the time-delay Doppler domain, and estimate the time-delay Doppler domain channel based on the stationarity and compactness of the time-delay Doppler domain channel.

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

[0086] The "configuring the number of time-domain and frequency-domain pilot sampling intervals" mentioned in step 1 includes:

[0087] Let M be the number of subcarriers in the OFDM system under consideration, N be the number of OFDM symbols, Δf be the subcarrier spacing, and T be the OFDM symbol length. Therefore, the OFDM system has a total of NM time-frequency domain elements. For example... 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] Step 2, "sampling to obtain the time-frequency domain channel estimate at the pilot location," includes:

[0089]

[0090] Where m = 0, 1, ..., M-1 and n = 0, 1, ..., N-1 represent the serial numbers of the time-frequency domain resource grids. This represents the time-frequency domain channel fading value over NM grid points. This represents the time-frequency domain channel estimate at the pilot location. Furthermore, considering the high-speed mobile multipath environment experienced by the OFDM system, the number of multipaths is P, the multipath indices are i = 1, ..., P, and the fading of the i-th multipath is h. i The time delay is τ i Doppler for v i ,but Can be written

[0091]

[0092] Step 3, "transforming the obtained time-frequency domain channel estimate to the time-delay Doppler domain", includes performing a two-dimensional Fourier transform operation on (2), which expands to:

[0093]

[0094] In the formula, k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the sequence number of the time-delay Doppler domain resource grid. i =MΔfτ i and k i =NTν i Let represent the normalized delay and Doppler of the i-th multipath. and This represents the scaling factor. Note that the result obtained in step 3... Since the period is along the time-delay Doppler domain, the "Periodic" annotation is used, and it is represented as:

[0095]

[0096] in,

[0097] Step 3, "estimating the time-delay Doppler domain channel based on the stationarity and compactness of the time-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 time-delay Doppler domain channel satisfies the compactness condition and And 2) When the time-delay Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, it can be directly... One period is considered as an estimate of the system's time delay Doppler channel, that is:

[0101]

[0102] in, The estimate for (3) can be easily obtained from the estimate for (1). This invention does not make specific requirements on the estimation method for (1). Thus, in Example 1, the estimation of the delay-Doppler domain channel based on the stationarity and compactness of the delay-Doppler domain channel has been completed.

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

[0104] When 1) the time-delay Doppler domain channel satisfies the compactness condition and When the delay-Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, the multipath number, multipath fading, delay, and Doppler can be estimated according to the algorithm designed in (3). This allows for the direct estimation of the time-delay Doppler channel.

[0105]

[0106] This embodiment provides the following estimates of the number of multipath paths, multipath fading, time delay, and Doppler effect based on the algorithm designed in (3). Algorithm implementation example:

[0107] Step 31: Obtain the result based on any energy threshold. i = 0;

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

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

[0110] Step 34: Obtain for

[0111] Step 35: Obtain for

[0112] Step 36: Obtain

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

[0114] Based on steps 31-37, it is easy to obtain estimates of the number of multipath paths, multipath fading, time delay, and Doppler. Finally, it is substituted into (6). Thus, in Example 2, the estimation of the delay-Doppler domain channel based on the stationarity and compactness of the delay-Doppler domain channel has been completed.

[0115] Therefore, based on Examples 1 and 2, this method can be applied to different systems with normalized time delay and Doppler conditions, and can estimate the time delay Doppler domain channel based on the stationarity and compactness of the time delay Doppler domain channel.

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

[0117] Performing a two-dimensional Fourier transform operation on the time-delay Doppler domain channel estimate obtained from (5) or (6), we get:

[0118]

[0119] Thus, the corresponding result can be obtained from (7). Figure 2 At the non-pilot position (i.e., mod(n,d) t )≠0,mod(m,d tThe time-frequency domain channel estimate of (≠0).

[0120] Figure 3 and Figure 4 The diagrams show a comparison of the channel estimation method for an OFDM system in a high-speed mobile multipath environment with the MSE and BER based on traditional linear interpolation and minimum mean square error estimators, respectively, when the normalized time delay is an integer and the Doppler is a non-integer value. Under extensive repeated experiments... with h TF The mean square interpolation of [m,n] is called the mean square error (MSE), and the ratio of the bit difference between the transmitted bits and the demodulated bits is called the bit error rate (BER). The scenario considered is a vehicle-to-everything (V2X) communication scenario, where M = 128 and N = 64. The maximum speed of the moving body is 250 km / h. Figure 2 The time-frequency domain sampling intervals are respectively 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, our proposed method outperforms linear interpolation methods in both MSE and BER. Linear interpolation methods encounter error ceilings in MSE and BER in high SNR regions because they struggle to adapt to the rapidly time-varying characteristics of channel fading in the time-frequency domain. In contrast, our proposed method effectively utilizes the time-invariance of the delay-Doppler domain channel, achieving accurate time-frequency domain channel estimation and reliable data transmission.

[0122] Secondly, such as Figure 3 and Figure 4 As shown, when both the normalized Doppler and the time delay are integers, following the method in Example 1 of Embodiment 2, the MSE of this method is almost identical to that of the linear optimal estimator—the MMSE estimator—in the high SNR region. It is worth noting that this method has lower complexity than the MMSE estimator and does not require the receiver to acquire channel statistics.

[0123] In addition, such as Figure 5 and Figure 6 As shown, when the normalized Doppler is a non-integer, according to steps 31-37 of Example 2 in Embodiment 2, the MSE of this method differs somewhat from that of the MMSE estimator, but the BER is almost the same as that of the MMSE estimator. Furthermore, steps 31-37 of Example 2 in Embodiment 2 are merely "estimates of the number of multipaths, multipath fading, time delay, and Doppler based on the algorithm designed in (3)". The algorithm implementation described above, through other methods, allows for further improvement of MSE performance under this condition to match... Figure 3 Similar levels to those in China.

[0124] Therefore, it can be found that in high-speed mobile multipath environments, this method can utilize the stable characteristics of dual-selection channels to provide MSE and BER performance that is far superior to linear interpolation estimators and close to optimal estimators (MMSE estimators). Moreover, it does not require channel statistical prior information, has lower complexity, and has greater potential for application in OFDM communication systems in practical high-speed mobile multipath environments.

[0125] Example 3

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

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

[0128] Based on the configured number of pilot intervals, the time-frequency domain channel estimate at the pilot position is obtained by sampling from the data received by the orthogonal frequency division multiplexing system;

[0129] The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain. Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated.

[0130] The estimated time-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, thus 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, wherein the processor and the memory communicate with each other, and the memory stores program instructions that can be executed by the processor. 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 above, the method including:

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

[0134] Based on the configured number of pilot intervals, the time-frequency domain channel estimate at the pilot position is obtained by sampling from the data received by the orthogonal frequency division multiplexing system;

[0135] The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain. Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated.

[0136] The estimated time-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, thus 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, 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 to cause the electronic device to execute instructions for implementing the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described above. The method includes:

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

[0140] Based on the configured number of pilot intervals, the time-frequency domain channel estimate at the pilot position is obtained by sampling from the data received by the orthogonal frequency division multiplexing system;

[0141] The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain. Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated.

[0142] The estimated time-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, thus completing the channel estimation of the orthogonal frequency division multiplexing system.

[0143] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0145] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0146] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0147] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within 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 and frequency domains; Based on the configured number of pilot intervals, the time-frequency domain channel estimate at the pilot position is obtained by sampling from the data received by the orthogonal frequency division multiplexing system; The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain. Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated. The estimated time-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, thus completing the channel estimation of the orthogonal frequency division multiplexing system. Configure the number of pilot sampling intervals in the time and frequency domains, including: Let M be the number of subcarriers in the OFDM system under consideration, N be the number of OFDM symbols, Δf be the subcarrier spacing, and T be the OFDM symbol length. Then, the OFDM system has N×M time-frequency domain elements, 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 pilot symbols, 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; The time-frequency domain channel estimate obtained at the pilot location is as follows: Where m = 0, 1, ..., M-1 and n = 0, 1, ..., N-1 represent the index of the time-frequency domain resource grid. This represents the time-frequency domain channel fading value of N×Y grid points. Let P represent the time-frequency domain channel estimate at the pilot location; considering the high-speed mobile multipath environment experienced by the OFDM system, the number of multipaths is P, the multipath indices are i = 1, ..., P, and the fading of the i-th multipath is h. i The time delay is τ i Doppler for v i ,but for: The obtained time-frequency domain channel estimate is transformed to the time-delay Doppler domain, including: In the formula, k = 0, 1, ..., N-1 and l = 0, 1, ..., M-1 represent the serial numbers of the time-delay Doppler domain resource grids, l i =MΔfτ i and k i =NTv i Let the normalized delay and Doppler of the i-th multipath be represented. and DFT represents the scaling factor. N {·} and IDFT M {·} represent the N-point Discrete Fourier Transform and M-point Inverse Discrete Fourier Transform operations, respectively; Based on the stationarity and compactness of the time-delay Doppler domain channel, the time-delay Doppler domain channel is estimated, including: When normalized delay l i and Doppler K i When it is an integer: At that time, the Doppler domain channel satisfied the compactness condition. and When the time-delay Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, it can be directly... One period is considered as an estimate of the system's time delay Doppler channel, that is: Normalized delay l i For integers, normalized Doppler k i When it is a non-integer: At that time, the Doppler domain channel satisfied the compactness condition. and When the Doppler domain channel satisfies the stationarity condition within the NT time and MΔf bandwidth, estimates of the number of multipath paths, multipath fading, time delay, and Doppler effect can be calculated and obtained. This directly yields an estimate of the time-delay Doppler channel: The estimated time-delay Doppler domain channel is converted back to the time-frequency domain to obtain the time-frequency domain channel at the non-pilot location of the OFDM system, including: Performing a two-dimensional Fourier transform operation on the obtained time-delay Doppler domain channel estimate yields: IDFT N {·) and DFT M {·} represent the N-point inverse discrete Fourier transform and the M-point discrete Fourier transform operations, respectively. Thus, the time-frequency domain channel estimate corresponding to the non-pilot position is obtained.

2. A channel estimation system for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment based on the method described in claim 1, characterized in that, include: The configuration module is used to configure the number of pilot sampling intervals in the time and frequency domains. A module is used to sample the time-frequency domain channel estimate at the pilot position from the data received by the orthogonal frequency division multiplexing system according to the configured number of pilot intervals; The estimation module is used to transform the obtained time-frequency domain channel estimate to the time-delay Doppler domain, and estimate the time-delay Doppler domain channel based on the stationarity and compactness of the time-delay Doppler domain channel. The conversion module is used to convert the estimated time-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, thus completing the channel estimation of the orthogonal frequency division multiplexing system.

3. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in claim 1.

4. A computer device, characterized in that, The system includes a memory and a processor, which 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 claim 1.

5. An electronic device, characterized in that, include: The device includes 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 to enable the electronic device to execute instructions for implementing the channel estimation method for an orthogonal frequency division multiplexing system in a high-speed mobile multipath environment as described in claim 1.

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