A PDP resampling shift algorithm and a PDP filtering method, device, filtering equipment and storage medium

Abstract

The scheme discloses a PDP resampling shift algorithm and a PDP filtering method and device, filtering equipment and a storage medium, and the relationship between the power delay profile (PDP) before and after timing adjustment and the timing adjustment amount Delta and the resampling coefficient are obtained according to the PDP resampling shift algorithm; when the sampling point offset of the current and next subframes is not an integer, the timing adjustment amount Delta can not be an integer, so that the timing position of the current and next subframes can be matched by cyclic shift alignment through the timing adjustment amount Delta, and the applicability is stronger; the historical PDP is resampled, so that the filtered historical PDP can include all important path information, thereby reflecting the real channel state, being closer to the real PDP of the current subframe, and improving the accuracy of channel estimation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to a PDP resampling shift algorithm and a PDP filtering method and device, a computer device and a storage medium. BACKGROUND

[0002] In a wireless communication system, a signal may experience direct, reflection, scattering, diffraction and the like in the process of propagation, resulting in the existence of multipath, movement, noise and interference and the like in the signal received by the receiving end. The receiver needs to perform time-frequency offset adjustment and channel estimation on the received signal before demodulation and decoding. The estimation of time offset, frequency offset, channel time delay spread and Doppler spread is collectively referred to as parameter estimation. Parameter estimation is a parameter reflecting the characteristics of the channel, which determines the accuracy of time-frequency offset adjustment, the performance of channel estimation, and thus affects the performance of the receiver.

[0003] The PDP spectrum is not only the direct input of time offset estimation, time delay spread estimation and frequency domain correlation estimation, but also determines the path selection position of frequency offset estimation and Doppler estimation, and determines the filtering coefficients in DFT channel estimation. In the PDP estimation process, the PDPs of different subframes need to be combined to improve the accuracy of PDP estimation. However, if the time offset is fixed, the timing positions of the PDP of the current subframe and the historical PDP may not be aligned after the time offset adjustment at the front end, resulting in that they cannot be directly combined. If the time offset adjusted at the front end is an integer sampling point in the current resolution, the timing positions of the two can be aligned by circularly shifting the historical PDP, but if it is not an integer sampling point, the two cannot be aligned by circular shift. In the usual scheme, the problem faced in this scenario cannot be solved. SUMMARY

[0004] The present application aims to overcome at least one of the above-mentioned defects of the prior art, and provides a PDP resampling shift algorithm and a PDP filtering method, device, filtering equipment and storage medium, which are used to solve the technical problem of timing misalignment before and after time adjustment in the prior art.

[0005] The present application provides a PDP resampling shift algorithm, comprising:

[0006] S100, let the channel time domain impulse response CIR be h, the channel frequency domain response CFR be H, and the frequency domain response H of the kth subcarrier be obtained k ;

[0007] S101, circularly shift the channel time domain impulse response h and the channel frequency domain response H, and the timing adjustment amount of the circular shift is Δ, and the results are represented by h and H respectively, and the frequency domain response H of the kth subcarrier is obtained and ​The time-domain impulse response of the nth path is obtained

[0008] S102, the time-domain impulse response h and the frequency-domain response H are subjected to fast Fourier transform (FFT) to obtain the time-domain impulse response after cyclic shift and the frequency-domain response Fast Fourier transform form

[0009] S103, according to the FFT result , point operation is performed to obtain the power delay profile (PDP)

[0010] S104, according to the PDP, the time-domain impulse response of the nth element of the corresponding PDP is obtained

[0011] S105, according to the time-domain impulse response of the nth element of the corresponding PDP, the relationship between the PDP before and after timing adjustment and the timing adjustment amount Δ is obtained

[0012] S106, according to the relationship between the PDP before and after timing adjustment and the timing adjustment amount Δ, the resampling coefficient coef nl :

[0013] coef nl = |a nl | 2 = |sinc(n-l-Δ)| 2

[0014] Wherein, n and l are both indexes of the path of the time-domain impulse response h, 0≤n, l<N.

[0015] The H of the kth subcarrier in S100 can be expressed as H k :

[0016]

[0017] Wherein, h n is the time-domain impulse response of the nth path, N is the length of IFFT transform, 0≤n<N, 0≤k<N.

[0018] The H of the kth subcarrier in S101 can be expressed as

[0019]

[0020] The time-domain impulse response of the nth path is ​​

[0021]

[0022] By further calculation:

[0023]

[0024] Wherein, m is the index of the radius of the time domain impulse response h, 0≤m<N.

[0025] In order to facilitate subsequent formula derivation, the time domain impulse response CIR and the frequency domain response CFR are converted into the form of fast Fourier transform FFT, and the time domain impulse response CIR and the frequency domain response CFR can be written in the form of matrix:

[0026] H=Fh

[0027] Wherein, F is the fast Fourier transform FFT matrix.

[0028] According to the matrix form of the time domain impulse response CIR and the frequency domain response CFR, the frequency domain response Can be expressed as:

[0029]

[0030] Wherein, E is expressed as:

[0031]

[0032] Corresponding to the time domain impulse response Can be expressed as:

[0033]

[0034] Wherein, F -1 Is the inverse of the matrix F.

[0035] Then, the power delay profile PDP is the diagonal element of :

[0036]

[0037] Wherein, X H Indicates the conjugate transpose matrix of matrix X, Λ=hh H Is the unit matrix, and A=F -1 ·E·F.

[0038] The power delay profile PDP obtained in S103 further includes: making the multipaths of the time domain impulse response uncorrelated, then:

[0039]

[0040] Wherein, Λ=hhH is a unit matrix, h H denotes the conjugate transpose matrix of matrix h, |h0| 2 denotes the power gain of the channel on the 0th path to the signal, |h N-1 | 2 denotes the power gain of the channel on the N-1th path to the signal.

[0041] The time-domain impulse response obtained in S104 is The nth element of the corresponding PDP is expressed as:

[0042]

[0043] wherein A H denotes the conjugate transpose matrix of matrix A, n and l are both indexes of the order of the path of the time-domain impulse response h, and 0≤n, l<N.

[0044]

[0045] Further derivation of the above formula is:

[0046]

[0047] The relationship between the power delay profile PDP before and after timing adjustment and the timing adjustment amount Δ in S105 is expressed as:

[0048]

[0049] Since the PDPs of different subframes need to be combined in the PDP estimation process to improve the accuracy of PDP estimation. However, if the time offset is fixed, the timing positions of the current subframe PDP and the historical PDP may not be aligned after the time offset adjustment at the front end, resulting in that they cannot be directly combined. If the time offset adjusted at the front end is an integer sampling point in the current resolution, the timing positions of the two can be aligned by circularly shifting the historical PDP, but if it is not an integer sampling point, the two cannot be aligned by circular shifting. The timing adjustment amount Δ is set to align the historical PDP and the current instantaneous PDP, and the timing adjustment amount Δ can be an integer or not. The circular shift Δ in S101 is determined according to the timing adjustment amount of the timing position sampling points of the front and rear two subframes in the channel.

[0050] Therefore, the PDP resampling function is added before PDP filtering, and the resampling coefficient is:

[0051] coef nl = |a nl | 2 = |sinc(n-l-Δ)| 2

[0052] The application also provides a PDP filtering method, comprising the PDP resampling shift algorithm, and further comprising:

[0053] S1, receiving subframe signal data from a wireless communication system;

[0054] S2, extracting a pilot signal from the received subframe signal data to perform least square channel estimation (LS) and inverse fast Fourier transform (IFFT) to obtain channel frequency response (CFR) and time domain impulse response (CIR);

[0055] S3, calculating the power of the time domain impulse response (CIR) to obtain a historical PDP;

[0056] S4, calculating the obtained channel frequency response (CFR) and time domain impulse response (CIR) according to steps S100-S106 to obtain an instantaneous PDP and a resampling coefficient (coef) nl ;

[0057] S5, performing filtering processing on the historical PDP;

[0058] S6, resampling the historical PDP so that the historical PDP and the current PDP are aligned in timing position and then filtered together to obtain a filtered PDP;

[0059] S7, performing denoising on the filtered PDP to obtain a denoised PDP.

[0060] Since the historical PDP has no sampling deviation relative to the current instantaneous PDP, it only shows one main path, which corresponds to the strongest path in signal propagation. When the historical PDP and the current instantaneous PDP are directly filtered, the filtered PDP may only reflect one main path, usually the stronger one, due to the two main paths of the current subframe PDP, thus failing to accurately reflect the actual channel state of the current subframe, because it ignores another important path due to timing deviation. Therefore, the historical PDP needs to be resampled according to the timing adjustment amount Δ to match the timing positions of the previous and subsequent subframes.

[0061] After resampling the historical PDP, the historical PDP has two main paths, which are similar to the instantaneous PDP, and can match the timing positions of the previous and subsequent subframes, so that the filtering process can more accurately reflect the channel state of the current subframe, including all important path information. The historical PDP filtered after resampling will be closer to the real PDP of the current subframe, thus improving the accuracy of channel estimation and the performance of the system.

[0062] The application also provides a PDP filtering device comprising:

[0063] an acquisition module configured to receive signal data from a wireless communication system;

[0064] a conversion module configured to obtain channel frequency response (CFR) and channel impulse response (CIR) by least square channel estimation (LS) and inverse fast Fourier transform (IFFT);

[0065] a calculation module configured to calculate power according to the CIR to obtain historical PDP, instantaneous PDP and resampling coefficient coef nl ;

[0066] a filtering module configured to filter the historical PDP;

[0067] a resampling module configured to resample the historical PDP so that the historical PDP is aligned with the timing position of the instantaneous PDP;

[0068] a processing module configured to filter and denoise the resampled historical PDP and instantaneous PDP.

[0069] The application further provides a filtering device, comprising at least one processor and a memory connected in communication with the at least one processor;

[0070] The memory stores instructions executable by the at least one processor, and the instructions are configured to execute the method of any one of the PDP resampling and shifting algorithm and the PDP filtering method.

[0071] The application further provides a non-transitory computer readable storage medium storing a computer program, and the computer program is executed by a processor to implement the steps of the method of the PDP filtering according to any one of the PDP resampling and shifting algorithm and the PDP filtering method.

[0072] The PDP resampling and shifting algorithm and the PDP filtering method, device, filtering device and storage medium have the following advantages: the PDP resampling and shifting algorithm is used to obtain the relationship between the power delay profile (PDP) before and after timing adjustment and the timing adjustment amount Δ and the resampling coefficient, and when the sampling point offset amount of the current and subsequent subframes is not an integer, the timing adjustment amount Δ can not be an integer, so the timing adjustment amount Δ can be used for cyclic shift alignment, the timing positions of the current and subsequent subframes are matched, and the applicability is stronger; the historical PDP is resampled, the historical PDP after filtering can include all important path information, so as to reflect the real channel state, and the real PDP of the current subframe is closer, and the accuracy of channel estimation is improved. BRIEF DESCRIPTION OF DRAWINGS

[0073] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0074] Figure 1 is a step schematic diagram of the PDP resampling shift algorithm.

[0075] Figure 2 is a step diagram of the PDP filtering method.

[0076] Figure 3 is a flowchart of the PDP filtering method.

[0077] Figure 4 is a schematic diagram before and after PDP filtering of example 3 without resampling.

[0078] Figure 5 is a schematic diagram before and after PDP filtering of example 3 after resampling. DETAILED DESCRIPTION

[0079] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings:

[0080] The embodiments of the PDP resampling shift algorithm and the PDP filtering method, device and storage medium provided by the embodiments of the present application are described above, although the logical order is shown in the flowchart, under certain data, the steps shown or described can be completed in an order different from that here.

[0081] Embodiment 1: Reference Figure 1

[0082] As shown in the step schematic diagram of the PDP resampling shift algorithm of Figure 1 , the present application provides a PDP resampling shift algorithm, comprising:

[0083] S100, let the channel time domain impulse response CIR be h, the frequency domain response CFR be H, and the frequency domain response H of the kth subcarrier be obtained k .

[0084] S101, circularly shift the channel time domain impulse response h and the channel frequency domain response H, and the timing adjustment amount of the circular shift is Δ, and the results are represented by h and H respectively, and the frequency domain response H of the kth subcarrier is obtained . , thereby obtaining the time domain impulse response h of the nth path. ​

[0085] S102, performing fast Fourier transform (FFT) on the time-domain impulse response h and the frequency-domain response H to obtain a time-domain impulse response after cyclic shift and a frequency-domain response in the form of fast Fourier transform (FFT);

[0086] S103, performing point number operation according to the FFT result to obtain a power delay profile (PDP);

[0087] S104, obtaining a time-domain impulse response corresponding to the nth element of the PDP;

[0088] S105, obtaining a relationship between the PDP before and after timing adjustment and the timing adjustment amount Δ according to the time-domain impulse response corresponding to the nth element of the PDP;

[0089] S106, obtaining a resampling coefficient coef nl :

[0090] coef nl = |a nl | 2 = |sinc(n-l-Δ)| 2

[0091] wherein n and l are both indexes of the order of the time-domain impulse response h, and 0≤n, l<N.

[0092] The H of the kth subcarrier in S100 can be expressed as H k :

[0093]

[0094] wherein h n is the time-domain impulse response of the nth path, N is the length of IFFT transform, 0≤n<N, and 0≤k<N.

[0095] The H of the kth subcarrier in S101 can be expressed as

[0096]

[0097] The time-domain impulse response of the nth path is:

[0098]

[0099] ​​​By further calculation:

[0100]

[0101] Wherein, m is the index of the radius of time domain impulse response h, 0≤m<N.

[0102] In order to facilitate subsequent formula derivation, the time domain impulse response CIR and the frequency domain response CFR are converted into fast Fourier transform FFT form, the time domain impulse response CIR and the frequency domain response CFR can be written in matrix form:

[0103] H=Fh

[0104] Wherein, F is a fast Fourier transform FFT matrix.

[0105] According to the matrix form of the time domain impulse response CIR and the frequency domain response CFR, the frequency domain response Can be expressed as:

[0106]

[0107] Wherein, E is expressed as:

[0108]

[0109] Corresponding to the time domain impulse response Can be expressed as:

[0110]

[0111] Wherein, F -1 Is the inverse of matrix F.

[0112] Then, the power delay profile PDP is the diagonal element of :

[0113]

[0114] Wherein, X H Indicates the conjugate transpose matrix of matrix X, Λ=hh H Is a unit matrix, A=F -1 ·E·F.

[0115] The power delay profile PDP obtained in S103 further includes: making the multipath of the time domain impulse response uncorrelated, then:

[0116]

[0117] Wherein, Λ=hh H Is a unit matrix, h H Indicates the conjugate transpose matrix of matrix h, |h0|2 denotes the power gain of the signal by the channel on the 0th path, |h N-1 | 2 denotes the power gain of the signal by the channel on the N-1th path.

[0118] The time-domain impulse response obtained in S104 The nth element of the corresponding PDP is expressed as:

[0119]

[0120] wherein A H denotes the conjugate transpose matrix of matrix A, n and l are both indexes of the order of the path of the time-domain impulse response h, and 0≤n, l<N.

[0121]

[0122] Further derivation of the above formula is as follows:

[0123]

[0124]

[0125] The relationship between the power delay profile PDP before and after timing adjustment and the timing adjustment amount Δ in S105 is expressed as:

[0126]

[0127] Since the PDPs of different subframes need to be combined in the PDP estimation process to improve the accuracy of PDP estimation. However, if the time offset is fixed, the timing positions of the PDP of the current subframe and the historical PDP may not be aligned after the time offset adjustment at the front end, resulting in that they cannot be directly combined. If the time offset adjusted at the front end is an integer sampling point in the current resolution, the timing positions of the two can be aligned by circularly shifting the historical PDP, but if it is not an integer sampling point, the two cannot be aligned by circularly shifting.

[0128] The historical PDP and the current instantaneous PDP are aligned by setting the timing adjustment amount Δ, which can be an integer or not. The circular shift Δ in S101 is determined according to the timing adjustment amount of the timing position sampling points of the front and rear two subframes in the channel.

[0129] Therefore, the PDP resampling function is added before PDP filtering, and the resampling coefficient is:

[0130] coef nl = |a nl | 2 = |sinc(n-l-Δ)|2

[0131] Embodiment 2: Reference Figure 2 and Figure 3

[0132] Compared with Embodiment 1, the difference is that, the PDP filtering method steps shown in FIG. 1, the application also provides a PDP filtering method, comprising: Figure 2 and Figure 3 Compared with Embodiment 1, the difference is that, the PDP filtering method steps shown in FIG. 1, the application also provides a PDP filtering method, comprising:

[0133] Compared with Embodiment 1, the difference is that, the PDP filtering method steps shown in FIG. 1, the application also provides a PDP filtering method, comprising:

[0134] S1, receiving subframe signal data from a wireless communication system;

[0135] S2, extracting pilot signals in the received subframe signal data for least square channel estimation LS and inverse Fourier transform FFT to obtain channel frequency domain response CFR and time domain impulse response CIR;

[0136] S3, calculating the power of the time domain impulse response CIR to obtain the historical PDP;

[0137] S4, calculating the obtained channel frequency domain response CFR and time domain impulse response CIR according to steps S100-S106 to obtain the instantaneous PDP and resampling coefficient coef nl ;

[0138] S5, filtering the historical PDP;

[0139] S6, resampling the historical PDP so that the historical PDP and the current PDP timing position are aligned and then filtered together to obtain the filtered PDP;

[0140] S7, denoising the filtered PDP to obtain the denoised PDP.

[0141] Since the historical PDP has no sampling deviation relative to the current instantaneous PDP, it only shows one main path, which corresponds to the strongest path in signal propagation. When filtering the historical PDP and the current instantaneous PDP directly, the filtered PDP may only reflect one main path, usually the stronger one, due to the two main paths of the current subframe PDP, thus failing to accurately reflect the actual channel state of the current subframe, because it ignores another important path that appears due to timing offset. Therefore, the historical PDP needs to be resampled according to the timing adjustment amount Δ to match the timing positions of the front and rear subframes.

[0142] After resampling the historical PDP, it has two main paths that are close to the instantaneous PDP and can match the timing positions of the previous and next subframes. This allows the filtering process to more accurately reflect the channel state of the current subframe, including all important path information. The resampled and filtered historical PDP is closer to the actual PDP of the current subframe, improving channel estimation accuracy and system performance.

[0143] Example 3: Reference Figure 4 and Figure 5

[0144] Compared with the above embodiment, the difference is that, assuming that the current channel is Gaussian white noise (AWGN), the timing positions of the two subframes before and after are offset by 0.5 sampling points. If the historical PDP is not resampled, the two subframes before and after and the filtered PDP are as follows: Figure 4 As shown in the figure, because the current subframe is offset by 0.5 sampling points compared to the previous subframe, the PDP of the current subframe has two main paths, while the historical PDP has no sampling offset and only one main path. Directly filtering the two results in a single main path in the filtered PDP. This results in a significant difference between the filtered PDP and the current subframe's PDP, which cannot accurately reflect the channel status of the current subframe.

[0145] The PDP resampling shift algorithm and PDP filtering method of the present invention are used to resample the historical PDP according to the timing adjustment amount Δ. The PDP before and after filtering is as follows: Figure 5 As shown in Figure 2, the historical PDP after resampling has two main paths, which are similar to the current instantaneous PDP waveform. The filtered PDP can reflect the true state of the current channel.

Claims

1. A PDP resampling shift algorithm, characterized by: S100, let the channel time domain stimulus response CIR be , the frequency domain response CFR is , find the Frequency domain response of subcarriers ; S101, channel time domain impulse response and channel frequency domain response Perform cyclic shift, the timing adjustment of cyclic shift is , the results were respectively and Indicates that the Frequency domain response of subcarriers , thus obtaining the Time domain impulse response of stripe diameter ; S102, the time domain impulse response and frequency domain response Perform fast Fourier transform (FFT) to obtain the time domain impulse response after cyclic shift and frequency domain response Fast Fourier transform form; S103, according to 、 Perform point operations on the Fourier transform FFT results to obtain the power delay spectrum PDP; S104: Obtain a time domain impulse response according to the power delay profile PDP. The corresponding PDP elements; S105: According to the time domain impulse response The corresponding PDP The power delay profile PDP and timing adjustment amount before and after the timing adjustment are obtained by using the following elements: the relationship between; S106: Power delay profile PDP before and after the timing adjustment and the timing adjustment amount The relationship between the two is used to obtain the resampling coefficients : in, and are all time domain impulse responses The serial index of the path, ; Obtaining the power delay profile PDP in S103 includes: Assuming that the multipaths of the time domain impulse response are uncorrelated, we have: in, Representation matrix The conjugate transposed matrix of It represents the power gain of the channel to the signal in the 0th path, represents the power gain of the channel to the signal on the N-1th path; The time domain impulse response is obtained as described in S104 The corresponding PDP The elements are represented as: in, Representation matrix The conjugate transposed matrix of and are all time domain impulse responses The serial index of the path, , ; The power delay profile PDP and timing adjustment amount before and after the timing adjustment in S105 The relationship between them is expressed as: 。 2. A PDP resampling shift algorithm according to claim 1, characterized in that: The cyclic shift in S101 It is determined according to the timing adjustment amount of the timing position sampling points of the first and last two subframes in the channel.

3. A method for PDP filtering, characterized in that: The method comprises a PDP resampling shift algorithm according to any one of claims 1 to 2, further comprising: S1. Receive subframe signal data from a wireless communication system; S2. Extracting a pilot signal from the received subframe signal data, performing least squares channel estimation LS and inverse Fourier transform FFT, and obtaining a channel frequency domain response CFR and a time domain impulse response CIR; S3, calculating the power of the time domain impulse response CIR to obtain a historical PDP; S4. Calculate the channel frequency domain response CFR and time domain impulse response CIR according to steps S100-S106 to obtain the instantaneous PDP and resampling coefficient ; S5, filtering the historical PDP; S6. Resample the historical PDP so that the historical PDP and the current PDP are aligned in timing position, and then filter the historical PDP and the current PDP together to obtain a filtered PDP. S7. De-noise the filtered PDP to obtain a de-noised PDP.

4. The method for PDP filtering according to claim 3, wherein: Resampling the historical PDP in S6 further includes: According to the timing adjustment amount The historical PDP is resampled to match the timing positions of the preceding and following subframes.

5. The method for PDP filtering according to claim 4, wherein: After the historical PDP is resampled, the historical PDP has two main paths, which are close to the instantaneous PDP and are used to accurately reflect the actual channel state of the current subframe.

6. A PDP filter device, characterized in that: A method for PDP filtering according to claim 3 is constructed, comprising: Acquisition module: used to receive signal data from the wireless communication system; Conversion module: Obtain the channel frequency domain response CFR and time domain impulse response CIR through least squares channel estimation LS and inverse Fourier transform FFT; Calculation module: calculate the power according to the time domain impulse response CIR, and obtain the historical PDP, instantaneous PDP and resampling coefficient ; Filtering module: performs filtering processing on the historical PDP; Resampling module: resamples the historical PDP so that the historical PDP is aligned with the instantaneous PDP timing position; Processing module: performs filtering and denoising on the resampled historical PDP and instantaneous PDP.

7. A filtering device, characterized in that: include: at least one processor; and a memory communicatively coupled to the at least one processor; The memory stores instructions that can be executed by the at least one processor, and the instructions are configured to execute the PDP resampling and shifting algorithm and the PDP filtering method according to any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is processed and executed, the steps of the PDP resampling shift algorithm and the PDP filtering method according to any one of claims 1 to 5 are implemented.

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