CN114629750A - Channel estimation enhancement method, device, equipment and medium - Google Patents
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Abstract
The embodiment of the invention discloses a method, a device, equipment and a medium for enhancing channel estimation. The method comprises the following steps: performing channel estimation according to a pilot signal in a received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value; performing edge extension on the initial frequency domain channel estimation value to obtain a frequency domain channel estimation extension value; and carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value. The technical scheme improves the precision of channel estimation, protects the edge characteristics of the channel estimation and reduces the bit error rate.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a method, an apparatus, a device, and a medium for enhancing channel estimation.
Background
In a wireless communication system based on an Orthogonal Frequency Division Multiplexing (OFDM) technique, in order to ensure that the communication system has good performance in a wireless channel environment, it is necessary to accurately estimate a channel. The channel estimation generally needs to estimate the wireless channel by using known pilot information, i.e. by using a certain number of pilot subcarriers, and considering that the accuracy of the channel estimation will directly affect the performance of the whole wireless communication system, the enhancement of the channel estimation is always an important issue in the application of the wireless communication technology.
Currently, for enhancement of channel estimation, filtering processing is usually performed on the obtained channel estimation directly, which causes severe loss of edge characteristics of the enhanced channel estimation, increases bit error rate, and affects reception performance of a wireless communication system. Therefore, how to improve the accuracy of channel estimation, protect the edge characteristics of channel estimation, and reduce the bit error rate is an urgent problem to be solved.
Disclosure of Invention
Embodiments of the present invention provide a method, an apparatus, a device, and a medium for enhancing channel estimation, so as to improve accuracy of channel estimation, protect edge characteristics of channel estimation, and reduce a bit error rate.
In a first aspect, an embodiment of the present invention provides a method for enhancing channel estimation, including:
performing channel estimation according to a pilot signal in a received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
performing edge extension on the initial frequency domain channel estimation value to obtain a frequency domain channel estimation extension value;
and carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
In a second aspect, an embodiment of the present invention further provides an apparatus for enhancing channel estimation, including:
the frequency domain channel estimation initial value acquisition module is arranged for carrying out channel estimation according to the pilot signal in the received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
the frequency domain channel estimation extension value acquisition module is used for performing edge extension on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value;
and the frequency domain channel estimation enhancement value acquisition module is configured to perform transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
In a third aspect, an embodiment of the present invention further provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement the method for enhancing channel estimation according to any embodiment of the present invention.
In a fourth aspect, the embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor, implements the method for enhancing channel estimation according to any embodiment of the present invention.
In the technical scheme provided by the embodiment of the invention, a preset algorithm is adopted to carry out channel estimation according to a pilot signal in a received signal to obtain a frequency domain channel estimation initial value, then edge extension is carried out on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value, and transform domain filtering is carried out on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value, so that the precision of channel estimation is improved, the edge characteristic of channel estimation is protected, and the bit error rate is reduced.
Drawings
FIG. 1a is a diagram illustrating a frequency domain channel estimation value in the prior art;
FIG. 1b is a diagram illustrating a time domain channel estimation value in the prior art;
FIG. 1c is a diagram illustrating enhanced time domain channel estimates in the prior art;
FIG. 1d is a diagram illustrating enhanced frequency domain channel estimation in the prior art;
fig. 1e is a schematic diagram of a traffic data signal after channel equalization in the prior art;
fig. 1f is a schematic granularity diagram corresponding to a service data signal after channel equalization in the prior art;
fig. 1g is a schematic diagram of a constellation corresponding to a service data signal after channel equalization in the prior art;
fig. 2 is a flowchart illustrating a method for enhancing channel estimation according to a first embodiment of the present invention;
fig. 3 is a flowchart illustrating a method for enhancing channel estimation according to a second embodiment of the present invention;
fig. 4a is a flowchart illustrating a method for enhancing channel estimation according to a third embodiment of the present invention;
fig. 4b is a schematic diagram of the enhancement value of the frequency domain channel estimation in the third embodiment of the present invention;
fig. 4c is a schematic diagram of the frequency domain channel estimation enhancement value of the prior art in the third embodiment of the present invention;
fig. 4d is a schematic constellation diagram corresponding to the service data signal after channel equalization in the third embodiment of the present invention;
fig. 4e is a schematic diagram of a constellation corresponding to a service data signal after channel equalization in the prior art in the third embodiment of the present invention;
fig. 5 is a schematic structural diagram of an apparatus for enhancing channel estimation according to a fourth embodiment of the present invention;
fig. 6 is a schematic diagram of a hardware structure of an electronic device in the fifth embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently or simultaneously. In addition, the order of the operations may be re-arranged. The process may be terminated when its operations are completed, but could have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.
For ease of understanding, the main inventive concepts of the embodiments of the present invention are briefly described.
After performing Least Square (LS) channel estimation on a pilot signal in a received signal, a frequency domain channel estimation value corresponding to the pilot signal in the received signal can be obtained as shown in fig. 1a, where shown in fig. 1a is only to intercept frequency domain channel estimation values corresponding to the first 1600 frequency points in all pilot signals, the abscissa represents the number of discrete frequency points (unit is one) of the pilot signal, and the ordinate represents the amplitude (unit is db) corresponding to the frequency points, and the following method is generally adopted when enhancing the frequency domain channel estimation value:
firstly, performing zero padding processing on a frequency domain channel estimation value, and obtaining a time domain channel estimation value corresponding to the frequency domain channel estimation value through Inverse Fast Fourier Transform (IFFT), wherein the abscissa represents a sampling point index of a pilot signal, the ordinate represents power (unit is db) corresponding to the pilot signal, and the rectangular box is the time domain channel estimation value corresponding to the frequency domain channel estimation value, considering that the frequency domain channel estimation value may change an original signal amplitude when performing time-frequency domain Transform, so that gain adjustment may be performed after the frequency domain channel estimation value is subjected to Inverse Fast Fourier Transform to obtain a more accurate time domain channel estimation value as shown in fig. 1 b; then, according to the time domain channel estimation value obtained after the inverse fast fourier transform, calculating an impulse response Power spectrum and a noise Power of the pilot signal, so that a Power filtering threshold corresponding to the time domain channel estimation value of the pilot signal can be determined, and performing time domain filtering processing on the time domain channel estimation value according to the Power filtering threshold to obtain an enhanced time domain channel estimation value, wherein the pilot signal in the received data may exist in a plurality, so that the time domain channel estimation value can be subjected to Power Delay Profile (PDP) estimation and then subjected to time domain filtering processing, so that the enhanced time domain channel estimation value shown in fig. 1c is obtained, wherein an abscissa represents a sampling point index ordinate of the pilot signal and an ordinate represents a Power (unit is db) corresponding to the pilot signal; finally, the enhanced time domain channel estimation value is transformed from the time domain to the frequency domain through Fast Fourier Transform (FFT), the zero padding frequency points are truncated and the gain is adjusted, so as to obtain the enhanced frequency domain channel estimation value shown in fig. 1d, wherein the abscissa represents the number of discrete frequency points (unit is one) of the pilot signal, and the ordinate represents the amplitude (unit is db) corresponding to the frequency points.
Comparing the enhanced frequency domain channel estimation value (fig. 1d) with the frequency domain channel estimation value before denoising (fig. 1a) can find that the noise in the frequency domain channel estimation value is effectively suppressed, but because the correction of each frequency point needs to depend on the front and rear frequency points corresponding to the frequency point in the denoising process, although the middle part of the frequency domain channel estimation value is not affected, the edge characteristics at the two ends of the frequency domain channel estimation value are affected, as shown in fig. 1d, the edge energy (amplitude) of the enhanced frequency domain channel estimation value is greatly reduced, that is, after the service data signal in the received data is subjected to channel equalization, the edge characteristics do not have smoothness, that is, the service data signal after channel equalization is shown in fig. 1e, wherein the horizontal coordinate represents the discrete number (unit) of the service data signal after channel equalization, the ordinate represents the amplitude (in db) corresponding to each frequency bin. In order to more obviously observe the unsmooth of the edge characteristics in the period, the service data signals after channel equalization can be displayed in a granularity graph shown in fig. 1f, wherein the abscissa represents the number (in unit) of discrete frequency points of the service data signals after channel equalization, and the ordinate represents the intensity distribution (in unit db) of the service data signals after channel equalization, so that the serious unsmooth phenomenon of the edge can be observed; further, the traffic data signal after channel equalization may also be displayed in a constellation diagram (I-Q plane) as shown in fig. 1g, wherein an abscissa represents an in-phase component (unit is db) of the traffic data signal after channel equalization, and an ordinate represents a quadrature component (unit is db) of the traffic data signal after channel equalization, and it can be seen that each point corresponding to the traffic data signal after channel equalization diverges near a standard constellation point (indicated by an arrow in the figure), so that a bit error rate of received data increases, thereby affecting a receiving performance of the wireless communication system.
At present, in order to improve the accuracy of channel estimation, the edge characteristics of the channel estimation are protected and smoothed, usually after the enhanced frequency domain channel estimation value obtained by fast fourier transform, then, the frequency domain edge of the enhanced frequency domain channel estimation value is smoothed, which is to directly truncate the estimation value with greatly reduced edge energy (amplitude) in the enhanced frequency domain channel estimation value, for example, directly truncating the part with the amplitude below 30dB in fig. 1d, although the problem of the unsmooth edge characteristic of the channel estimation can be solved in this way, since the edge characteristic also contains effective frequency domain channel estimation values, especially in the case that the unsmooth problem of the multipath channel is serious, the direct truncation process may reduce the performance of the edge carrier, generate a higher bit error rate, and further affect the receiving performance of the wireless communication system.
Based on the above considerations, the inventor has creatively proposed a channel estimation enhancement method aiming at the problems that the edge feature loss of channel estimation is serious, the bit error rate is increased, and the influence is caused on the receiving performance of the wireless communication system, and the method specifically comprises the following steps:
performing channel estimation according to a pilot signal in a received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
performing edge extension on the initial frequency domain channel estimation value to obtain a frequency domain channel estimation extension value;
and carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
Example one
Fig. 2 is a flowchart of a channel estimation enhancement method according to an embodiment of the present invention, which is applicable to a case of smoothing a frequency domain channel estimation value of a received signal, and the method can be performed by a channel estimation enhancement apparatus according to an embodiment of the present invention, which can be implemented in software and/or hardware, and can be generally integrated in an electronic device.
As shown in fig. 2, the method for enhancing channel estimation provided in this embodiment specifically includes:
s110, channel estimation is carried out according to the pilot signals in the received signals by adopting a preset algorithm, and a frequency domain channel estimation initial value is obtained.
The preset algorithm refers to any algorithm that can be used to calculate a channel estimation value corresponding to a pilot signal in a received signal, for example, an LS algorithm may be used to perform channel estimation on the pilot signal, which is not specifically limited in this embodiment of the present invention.
The received signal refers to a signal received by a receiving end in a wireless communication system and sent by a sending end, wherein the received signal may include a pilot signal and a traffic signal.
A pilot signal, which refers to a signal transmitted for measurement or monitoring purposes in a wireless communication system, is generally a single frequency, pilot signals of a plurality of different frequencies may be included in a received signal, and the pilot signal exists only on a prescribed subcarrier according to a protocol operating in the wireless communication system.
Channel estimation refers to a process of estimating model parameters of a certain channel model to be assumed from received data. In a communication system, due to the influence of multipath fading, noise and the like, a signal received by a receiving end is often severely distorted, and channel estimation is required to effectively recover original information sent by a sending end.
The initial value of frequency domain channel estimation refers to a frequency domain channel estimation value corresponding to a pilot signal in a received signal, which is determined after a preset algorithm is adopted to perform channel estimation on the pilot signal in the received signal.
And performing channel estimation on the pilot signal in the received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value corresponding to the pilot signal in the received signal.
And S120, performing edge extension on the initial value of the frequency domain channel estimation to obtain a frequency domain channel estimation extension value.
And edge extension, namely performing interpolation processing on the edge of the initial value of the frequency domain channel estimation to obtain channel response estimated values at other positions with equal intervals on the basis of the initial value of the frequency domain channel estimation, and realizing outward extension on the edge of the initial value of the frequency domain channel estimation.
The frequency domain channel estimation extension value refers to a frequency domain channel estimation value obtained by performing edge extension on the frequency domain channel estimation initial value.
And performing edge extension on the initial value of the frequency domain channel estimation to obtain an extended value of the frequency domain channel estimation so as to reduce the damage of edge characteristics when the extended value of the frequency domain channel estimation is subjected to filtering processing, wherein the edge characteristics of the channel estimation value obtained after the filtering processing are smoother.
And S130, carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
Transform-domain filtering, which refers to analyzing the characteristics of a signal by using fourier transform, transforming the signal between time domain and frequency domain, and implementing filtering processing on the signal in the time domain and/or the frequency domain. In the embodiment of the invention, the frequency domain channel estimation extension value can be converted into the time domain, then the denoising processing is carried out by adopting a time domain filtering mode, and the denoised channel estimation extension value is converted back to the frequency domain, thereby obtaining the frequency domain channel estimation enhancement value.
The frequency domain channel estimation enhancement value is a frequency domain channel estimation value obtained by filtering the frequency domain channel estimation extension value to effectively suppress noise interference in the frequency domain channel estimation extension value.
After the frequency domain channel estimation extension value is obtained, the frequency domain channel estimation extension value is subjected to transform domain filtering to obtain a frequency domain channel estimation enhancement value, so that filtering processing of a frequency domain channel estimation value corresponding to a pilot signal in a received signal is realized, and the accuracy of the frequency domain channel estimation value is improved.
As an optional implementation manner, before performing transform domain filtering on the frequency domain channel estimation extension values, the method may further include: if the frequency point number related to the frequency domain channel estimation extension value is less than the pilot frequency point number corresponding to the pilot frequency signal, supplementing the frequency point related to the frequency domain channel estimation extension value so as to enable the supplemented frequency point number to be equal to the pilot frequency point number; performing transform-domain filtering on the frequency-domain channel estimation extension value to obtain a frequency-domain channel estimation enhancement value, which may include: performing inverse fast Fourier transform and gain adjustment on the frequency domain channel estimation extension value to obtain a time domain channel estimation extension value; determining a power filtering threshold, and carrying out filtering processing on the time domain channel estimation extension value according to the power filtering threshold to obtain a time domain channel estimation enhancement value; and performing fast Fourier transform, interception processing and gain adjustment on the time domain channel estimation enhancement value to obtain a frequency domain channel estimation enhancement value.
Supplementing the frequency points related to the frequency domain channel estimation extension value refers to zero-filling the frequency domain channel estimation extension value to the number of pilot points corresponding to the pilot signals when the number of the frequency points related to the frequency domain channel estimation extension value is less than the number of the pilot points corresponding to the pilot signals.
And gain adjustment, namely performing up-regulation or down-regulation on the signal amplification obtained after performing inverse fast Fourier transform on the frequency domain channel estimation extension value. In this case, after the channel estimation value is transformed in the transform domain, the gain of the channel estimation value needs to be adjusted to restore the signal strength to the signal strength before the transform domain.
The time domain channel estimation extension value refers to a channel estimation extension value in the time domain obtained by performing inverse fast fourier transform and gain adjustment on the frequency domain channel estimation extension value.
The power filtering threshold refers to a threshold value corresponding to the noise interference power when the time domain channel estimation extension value is subjected to filtering processing, and the noise interference in the time domain channel estimation extension value can be identified through the threshold value, and further the noise interference is filtered according to the threshold value. The power filtering threshold can be obtained by calculating an impulse response power spectrum and a noise power of the time domain channel estimation extension value.
The time domain channel estimation enhancement value refers to a time domain channel estimation value obtained by filtering the time domain channel estimation extension value to effectively suppress noise interference in the time domain channel estimation extension value.
And (4) intercepting, namely deleting the extending parts of the edges at two ends in the channel estimation value obtained after the time domain channel estimation enhanced value is subjected to fast Fourier transform so as to obtain a frequency domain channel estimation enhanced value.
Before the frequency domain channel estimation extension value is subjected to transform domain filtering, if the number of frequency points related to the frequency domain channel estimation extension value is smaller than the number of pilot points corresponding to the pilot signal, supplementing the frequency points related to the frequency domain channel estimation extension value, namely, zero padding the frequency domain channel estimation extension value to the number of pilot points corresponding to the pilot signal so as to enable the number of frequency points after being supplemented to be equal to the number of pilot points, then performing inverse fast Fourier transform and gain adjustment on the frequency domain channel estimation extension value to obtain a time domain channel estimation extension value, then determining a power filtering threshold, and performing filtering processing on the time domain channel estimation extension value according to the power filtering threshold to obtain a time domain channel estimation enhancement value, and finally performing fast Fourier transform on the time domain channel estimation enhancement value and obtaining the frequency domain channel estimation enhancement value through interception processing and gain adjustment.
Further, after the frequency domain channel estimation enhancement value is obtained, channel equalization processing can be performed on the service data in the received data according to the obtained frequency domain channel estimation enhancement value, that is, the service data is divided by the frequency domain channel estimation enhancement value, so that the corresponding service data after channel estimation processing can be obtained, and the accuracy of the service data in the received data is improved.
The technical scheme provided by the embodiment of the invention adopts a preset algorithm to carry out channel estimation according to a pilot signal in a received signal to obtain a frequency domain channel estimation initial value, then carries out edge extension on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value, in the prior art, after transform domain filtering, the edge characteristic of the channel estimation value is smoothed by a mode of cutting off the estimation value with greatly reduced edge energy (amplitude) in the enhanced frequency domain channel estimation value, thereby reducing the performance of an edge carrier and generating higher bit error rate, and in the technical scheme provided by the embodiment of the invention, before transform domain filtering processing, the edge characteristic is protected by adopting a mode of carrying out proper edge extension on the channel estimation value according to the essential characteristic of a channel, namely the memory effect existing in the filtering process, thereby achieving the effect of lossless filtering, the accuracy of channel estimation is improved, the edge characteristics of the channel estimation are protected, and the bit error rate is reduced.
Example two
Fig. 3 is a flowchart of a method for enhancing channel estimation according to a second embodiment of the present invention. The present embodiment is embodied on the basis of the foregoing embodiment, wherein the edge extension may be performed on the initial value of the frequency domain channel estimation to obtain a value of the frequency domain channel estimation extension, and the method specifically includes:
determining a frequency domain channel estimation value corresponding to each edge extension frequency point;
and generating a frequency domain channel estimation extension value according to the frequency domain channel estimation initial value and the frequency domain channel estimation value corresponding to each edge extension frequency point.
Further, determining the frequency domain channel estimation value corresponding to each edge extension frequency point may include:
and determining the frequency domain channel estimation value corresponding to each edge extension frequency point based on a wiener interpolation method.
As shown in fig. 3, the method for enhancing channel estimation provided in this embodiment specifically includes:
s210, channel estimation is carried out according to the pilot signals in the received signals by adopting a preset algorithm, and a frequency domain channel estimation initial value is obtained.
And S220, determining the frequency domain channel estimation value corresponding to each edge extension frequency point based on a wiener interpolation method.
The edge extension frequency point refers to each frequency point corresponding to an extension part when edge extension processing is carried out on the frequency domain channel estimation value.
When the edge extension is performed on the initial value of the frequency domain channel estimation, the frequency domain channel estimation value corresponding to each edge extension frequency point, that is, the channel estimation value of the subcarrier at the extension position is determined based on a wiener interpolation method, wherein the wiener interpolation is a method for calculating the frequency domain channel estimation value by using the relevant statistical information of the channel, and the relevant function of the channel response can be determined through the frequency domain response of the channel.
Wherein S220 may specifically include the following S221-S224 operations:
and S221, determining a power delay spectrum corresponding to the pilot signal.
The power delay spectrum and the frequency domain correlation coefficient are mutually Fourier transform pairs, and the frequency domain correlation coefficient can be determined through the power delay spectrum and is used for frequency domain channel estimation.
S222, selecting a plurality of points according to the energy distribution of the power time delay spectrum to perform fast Fourier transform to obtain a frequency domain correlation value sequence.
The frequency domain correlation value sequence refers to a frequency domain correlation coefficient sequence determined after the selected points are subjected to fast Fourier transform.
And selecting a plurality of frequency points according to the energy distribution of the power time delay spectrum to carry out fast Fourier transform to obtain a frequency domain correlation value sequence. For example, in the power delay spectrum, the maximum energy position is used as the center, M points are selected in total before and after the power delay spectrum, that is, K points are selected before the center, and P points are selected after the center, wherein the number of points selected before and after the center can be different, M points are respectively extended at two end edges of the frequency domain channel estimation initial value according to the selected total number of points, and then the M points respectively extended at the two end edges are subjected to fast fourier transform, so as to obtain a corresponding frequency domain correlation value sequence.
And S223, determining a frequency domain interpolation coefficient matrix according to the frequency domain correlation value sequence.
The frequency domain interpolation coefficient matrix is a matrix formed by frequency domain interpolation coefficients corresponding to each edge extension frequency point, and the channel estimation value of the subcarrier at the extended position can be determined through the frequency domain interpolation coefficient matrix.
Optionally, determining a frequency-domain interpolation coefficient matrix according to the frequency-domain correlation value sequence may include: determining a frequency domain self-correlation matrix and a frequency domain cross-correlation matrix according to the frequency domain correlation value sequence; and taking the product of the frequency domain cross correlation matrix and the inverse matrix of the frequency domain autocorrelation matrix as a frequency domain interpolation coefficient matrix.
It is assumed that the sequence of frequency domain correlation values can be represented as R k]Wherein k represents the subcarrier index, determining a frequency domain autocorrelation matrix phiFDAnd the frequency domain cross-correlation matrix thetaFD. Frequency domain autocorrelation matrix phiFDEach element in (a) may be represented as:
wherein i and j represent the frequency domain autocorrelation matrix phi respectivelyFDRow and column designations of, N0Representation pilotAnd (4) spacing. Frequency domain cross-correlation matrix ΘFDEach element in (a) may be represented as:
wherein R represents an antenna number, R(r)Representing the autocorrelation matrix on the r-th antenna,
indicating the number of pilots. Taking the product of the frequency domain cross correlation matrix and the inverse matrix of the frequency domain autocorrelation matrix as a frequency domain interpolation coefficient matrix
Namely, it is
And determining a frequency domain autocorrelation matrix and a frequency domain cross-correlation matrix according to the frequency domain correlation value sequence, and multiplying the frequency domain cross-correlation matrix and an inverse matrix of the frequency domain autocorrelation matrix to obtain a frequency domain interpolation coefficient matrix.
And S224, determining the frequency domain channel estimation value corresponding to each edge extension frequency point according to the frequency domain interpolation coefficient matrix and the frequency domain channel estimation initial value.
And multiplying the frequency domain interpolation coefficient matrix by the frequency domain channel estimation initial value to determine the frequency domain channel estimation value corresponding to each edge extension frequency point.
And S230, generating a frequency domain channel estimation extension value according to the frequency domain channel estimation initial value and the frequency domain channel estimation value corresponding to each edge extension frequency point.
According to the initial value of the frequency domain channel estimation and the frequency domain channel estimation value corresponding to each edge extension frequency point, the frequency domain channel estimation value corresponding to each edge extension frequency point is spliced with the initial value of the frequency domain channel estimation, so that the frequency domain channel estimation extension value can be generated, and the edge extension of the initial value of the frequency domain channel estimation is realized.
S240, carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
For those parts of this embodiment that are not explained in detail, reference is made to the aforementioned embodiments, which are not repeated herein.
According to the technical scheme, a preset algorithm is adopted to perform channel estimation according to pilot signals in received signals to obtain a frequency domain channel estimation initial value, then a frequency domain channel estimation value corresponding to each edge extension frequency point is determined based on a wiener interpolation method, a frequency domain channel estimation extension value is generated according to the frequency domain channel estimation initial value and the frequency domain channel estimation value corresponding to each edge extension frequency point, finally, a frequency domain channel estimation enhancement value is obtained by performing transform domain filtering on the frequency domain channel estimation extension value, and transform domain filtering processing is performed after the edge extension of the frequency domain channel estimation initial value, so that the accuracy of channel estimation is improved, the edge characteristics of channel estimation are protected, the bit error rate is reduced, and the receiving performance of a system and the accuracy of data transmission are improved.
EXAMPLE III
Fig. 4a is a flowchart of a method for enhancing channel estimation according to a second embodiment of the present invention. The present embodiment is embodied on the basis of the foregoing embodiment, wherein the determining the frequency domain channel estimation value corresponding to each edge spreading frequency point may specifically be:
determining the frequency domain channel estimation value of the edge extension frequency point matched with the target boundary frequency point according to the frequency domain channel estimation value corresponding to the target boundary frequency point and the pre-configured extrapolation vector matched with the target boundary frequency point;
wherein the sum of the elements in the pre-configured extrapolation vector is 1.
As shown in fig. 4a, the method for enhancing channel estimation provided in this embodiment specifically includes:
s310, channel estimation is carried out according to the pilot signals in the received signals by adopting a preset algorithm, and a frequency domain channel estimation initial value is obtained.
And S320, determining the frequency domain channel estimation value of the edge extension frequency point matched with the target boundary frequency point according to the frequency domain channel estimation value corresponding to the target boundary frequency point and the pre-configured extrapolation vector matched with the target boundary frequency point.
Wherein the sum of the elements in the pre-configured extrapolation vector is 1.
And the target boundary frequency point refers to a frequency point positioned at two end edges in the initial value of the frequency domain channel estimation.
The pre-configured extrapolation vector refers to a vector formed by preset linear extrapolation coefficients corresponding to each target boundary frequency point.
According to the frequency domain channel estimation value corresponding to the target boundary frequency point in the frequency domain channel estimation initial value and the pre-configured extrapolation vector matched with the target boundary frequency point, the frequency domain channel estimation value of the edge extension frequency point matched with the target boundary frequency point can be determined by multiplying the target boundary frequency point and the pre-configured extrapolation vector.
For example, n target boundary frequency points are respectively selected at the left and right edges of the initial value of the frequency domain channel estimation, and an extrapolation vector is preconfigured to be
Wherein the content of the first and second substances,
the vector coefficient of the extrapolated first point in the extended frequency points of the left and right edges, [ eta ]1…ηn]And if the vector coefficients of the nth point are extrapolated from the edge extension frequency points at the left and right ends, the frequency domain channel estimation value of the edge extension frequency point matched with the target boundary frequency point is as follows:
wherein the content of the first and second substances,
representing frequency domain channel corresponding to each target boundary frequency pointEstimate, |LRepresents an L-th order linear extrapolation,
and representing the frequency domain channel estimation value of the edge extension frequency point matched with each target boundary frequency point. The simplest coefficient configuration mode is exemplarily given, 1 target boundary frequency point is respectively selected at the left and right edges of the initial value of the frequency domain channel estimation to perform 1-order linear extrapolation processing, that is, n is 1, l 11, the preconfigured extrapolated vector is set to α1＝…＝η1＝1。
And S330, generating a frequency domain channel estimation extension value according to the frequency domain channel estimation initial value and the frequency domain channel estimation value corresponding to each edge extension frequency point.
S340, carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
Fig. 4b is a schematic diagram of a frequency domain channel estimation enhancement value obtained by performing transform domain filtering on a frequency domain channel estimation extension value in an embodiment of the present invention, and fig. 4c is a schematic diagram of a frequency domain channel estimation enhancement value obtained by directly performing transform domain filtering on a frequency domain channel estimation extension value by using the prior art, that is, without performing edge extension processing, where abscissa in fig. 4b and fig. 4c represents the number (unit is one) of discrete frequency points of a pilot signal, and ordinate represents the corresponding amplitude (unit is db) of the frequency points, and it can be found by comparing two figures that the edges at two ends in fig. 4b are smoother, and the edges at two ends in fig. 4c are forcibly truncated, the smoothness is damaged, which is not favorable for protecting the edge characteristics of a channel estimation value, and after performing edge extension on a frequency domain channel estimation initial value, the edge characteristics of the frequency domain channel estimation enhancement value obtained by performing transform domain filtering on the frequency domain channel estimation extension value are flatter Smooth and improves smoothness.
Further, a service signal after channel equalization is displayed in a constellation diagram, fig. 4d is a constellation diagram obtained by performing channel equalization processing on service data by using a frequency domain channel estimation enhancement value obtained by performing transform domain filtering on a frequency domain channel estimation extension value in the embodiment of the present invention, fig. 4e is a constellation diagram obtained by performing channel equalization processing on service data by using a frequency domain channel estimation enhancement value obtained by truncating an estimation value mode in which edge energy (amplitude) in the frequency domain channel estimation value after enhancement is greatly reduced, fig. 1g is a constellation diagram obtained by performing channel equalization processing on service data by using a frequency domain channel estimation enhancement value obtained without performing any edge band noise suppression processing, wherein horizontal coordinates in fig. 4d and fig. 4e represent an in-phase component (unit is db) of the service data signal after channel equalization, the ordinate represents the orthogonal component (unit is db) of the service data signal after channel equalization, and it can be found by comparing three constellations that although the way of using the estimation value with greatly reduced edge energy (amplitude) in the truncated and enhanced frequency domain channel estimation value can also suppress the divergence of constellation points, there is still statistical deviation compared with the standard constellation points (indicated by arrows in fig. 4 e), and the way of using the edge extension to the frequency domain channel estimation initial value can not only effectively suppress the divergence of constellation points, but also make the constellation points corresponding to each signal feature converge around the standard constellation points (white solid circles in fig. 4 d), and the coincidence degree of the constellation corresponding to the service data after channel equalization and the standard constellation is the best, thereby improving the accuracy of the received data.
Further, the method includes performing channel equalization processing on the service data respectively by using three frequency domain channel estimation enhancement values obtained by performing edge extension processing on a frequency domain channel estimation initial value, using an estimation value mode in which truncated edge energy (amplitude) is greatly reduced, and using a mode in which no edge band Noise suppression processing is performed, and then calculating Error Vector Magnitudes (EVM) corresponding to the service data after the three channel equalization processing and Signal to Noise ratios (Signal Noise ratios, SNRs) under the same Block Error Rate (BLER), so as to obtain calculation results shown in the following table:
| EVM | SNR | |
| without any edge band noise suppression processing | 11.5％ | 2dB(BLER＝10-2) |
| Estimation method for greatly reducing truncation edge energy (amplitude) | 4.5％ | -1.5dB(BLER＝10-2) |
| Method for carrying out edge extension processing on frequency domain channel estimation initial value | 2.5％ | -2.2dB(BLER＝10-2) |
It can be easily found from the calculation results in the table that the error vector magnitude of the service data after channel equalization obtained by performing edge extension processing on the initial value of the frequency domain channel estimation is the smallest, and the service data with lower signal-to-noise ratio can be received under the same block error rate, so that the receiving performance of the system is improved, the bit error rate in the data transmission process is reduced, and the accuracy of data transmission is improved.
For those parts of this embodiment that are not explained in detail, reference is made to the aforementioned embodiments, which are not repeated herein.
In the technical scheme, a preset algorithm is adopted to carry out channel estimation according to the pilot signal in the received signal to obtain a frequency domain channel estimation initial value, then determining the frequency domain channel estimation value of the edge extension frequency point matched with the target boundary frequency point according to the frequency domain channel estimation value corresponding to the target boundary frequency point and the pre-configured extrapolation vector matched with the target boundary frequency point, estimating an initial value according to the frequency domain channel, and frequency domain channel estimation values corresponding to the edge spread frequency points to generate frequency domain channel estimation spread values, and finally, carrying out transform domain filtering on the frequency domain channel estimation spread values to obtain frequency domain channel estimation enhancement values, by carrying out transform domain filtering processing after the initial value edge of the frequency domain channel estimation is extended, the precision of the channel estimation is improved, the edge characteristic of the channel estimation is protected, the bit error rate is reduced, and the receiving performance of the system and the precision of data transmission are improved.
Example four
Fig. 5 is a schematic structural diagram of an apparatus for enhancing channel estimation according to a fourth embodiment of the present invention, where the embodiment of the present invention is applicable to a case of smoothing a frequency domain channel estimation value of a received signal, and the apparatus may be implemented in a software and/or hardware manner, and may be generally integrated in an electronic device.
As shown in fig. 5, the apparatus for enhancing channel estimation specifically includes: a frequency domain channel estimation initial value obtaining module 410, a frequency domain channel estimation extension value obtaining module 420 and a frequency domain channel estimation enhancement value obtaining module 430. Wherein the content of the first and second substances,
a frequency domain channel estimation initial value obtaining module 410 configured to perform channel estimation according to a pilot signal in a received signal by using a preset algorithm to obtain a frequency domain channel estimation initial value;
a frequency domain channel estimation extension value obtaining module 420 configured to perform edge extension on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value;
the frequency domain channel estimation enhancement value obtaining module 430 is configured to perform transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
The technical scheme provided by the embodiment of the invention adopts a preset algorithm to carry out channel estimation according to a pilot signal in a received signal to obtain a frequency domain channel estimation initial value, then carries out edge extension on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value, in the prior art, after transform domain filtering, the edge characteristic of the channel estimation value is smoothed by a mode of cutting off the estimation value with greatly reduced edge energy (amplitude) in the enhanced frequency domain channel estimation value, thereby reducing the performance of an edge carrier and generating higher bit error rate, and in the technical scheme provided by the embodiment of the invention, before transform domain filtering processing, the edge characteristic is protected by adopting a mode of carrying out proper edge extension on the channel estimation value according to the essential characteristic of a channel, namely the memory effect existing in the filtering process, thereby achieving the effect of lossless filtering, the accuracy of channel estimation is improved, the edge characteristics of the channel estimation are protected, and the bit error rate is reduced.
Optionally, the frequency domain channel estimation extension value obtaining module 420 includes: a domain channel estimation value determining unit and a domain channel estimation extension value generating unit, wherein,
a frequency domain channel estimation value determination unit configured to determine a frequency domain channel estimation value corresponding to each edge spread frequency point;
and the frequency domain channel estimation extension value generating unit is configured to generate a frequency domain channel estimation extension value according to the frequency domain channel estimation initial value and the frequency domain channel estimation values corresponding to the edge extension frequency points.
In an embodiment, the frequency domain channel estimation value determining unit is specifically configured to:
and determining the frequency domain channel estimation value corresponding to each edge extension frequency point based on a wiener interpolation method.
Further, the frequency domain channel estimation value determination unit includes: a power time delay spectrum determining subunit, a frequency domain correlation value sequence generating subunit, a frequency domain interpolation coefficient matrix generating subunit and a frequency domain channel estimation value determining subunit, wherein,
a power delay spectrum determining subunit, configured to determine a power delay spectrum corresponding to the pilot signal;
the frequency domain correlation value sequence generating subunit is configured to select a plurality of points according to the energy distribution of the power time delay spectrum to perform fast Fourier transform to obtain a frequency domain correlation value sequence;
a frequency domain interpolation coefficient matrix generation subunit configured to determine a frequency domain interpolation coefficient matrix according to the sequence of frequency domain correlation values;
and the frequency domain channel estimation value determining subunit is configured to determine the frequency domain channel estimation values corresponding to the edge extension frequency points according to the frequency domain interpolation coefficient matrix and the frequency domain channel estimation initial values.
Optionally, the frequency domain interpolation coefficient matrix generating subunit is specifically configured to:
determining a frequency domain self-correlation matrix and a frequency domain cross-correlation matrix according to the frequency domain correlation value sequence;
and taking the product of the frequency domain cross correlation matrix and the inverse matrix of the frequency domain autocorrelation matrix as the frequency domain interpolation coefficient matrix.
In another embodiment, the frequency domain channel estimation value determining unit is specifically configured to:
determining a frequency domain channel estimation value of an edge extension frequency point matched with a target boundary frequency point according to a frequency domain channel estimation value corresponding to the target boundary frequency point and a pre-configured extrapolation vector matched with the target boundary frequency point;
wherein the sum of the additions of the elements in the preconfigured extrapolation vector is 1.
Optionally, the apparatus further includes a frequency point number supplementing module, where the frequency point number supplementing module is configured to, before performing transform domain filtering on the frequency domain channel estimation extension value, if the number of frequency points related to the frequency domain channel estimation extension value is less than the number of pilot points corresponding to the pilot signal, supplement the frequency points related to the frequency domain channel estimation extension value, so that the number of frequency points after being supplemented is equal to the number of pilot points;
the frequency domain channel estimation enhancement value obtaining module 430 is specifically configured to:
performing inverse fast Fourier transform and gain adjustment on the frequency domain channel estimation extension value to obtain a time domain channel estimation extension value;
determining a power filtering threshold, and carrying out filtering processing on the time domain channel estimation extension value according to the power filtering threshold to obtain a time domain channel estimation enhancement value;
and carrying out fast Fourier transform, interception processing and gain adjustment on the time domain channel estimation enhancement value to obtain the frequency domain channel estimation enhancement value.
The channel estimation enhancement device can execute the channel estimation enhancement method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects for executing the channel estimation enhancement method.
EXAMPLE five
Fig. 6 is a schematic diagram of a hardware structure of an electronic device according to a fifth embodiment of the present invention, and as shown in fig. 6, the electronic device includes:
one or more processors 510, one processor 510 being illustrated in FIG. 6;
a memory 520;
the electronic device may further include: an input device 530 and an output device 540.
The processor 510, the memory 520, the input device 530 and the output device 540 in the vehicle-mounted terminal equipment may be connected through a bus or in other manners, and fig. 6 illustrates an example of connection through a bus.
The memory 520 is a non-transitory computer-readable storage medium, and can be used to store software programs, computer-executable programs, and modules, such as program instructions/modules corresponding to the channel estimation enhancement method in the embodiment of the present invention (for example, the frequency domain channel estimation initial value obtaining module 410, the frequency domain channel estimation extension value obtaining module 420, and the frequency domain channel estimation enhancement value obtaining module 430 shown in fig. 5). The processor 510 executes various functional applications and data processing of the electronic device by executing the software programs, instructions and modules stored in the memory 520, namely, implements the enhancement method of channel estimation in the above method embodiments.
The memory 520 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to use of the computer device, and the like. Further, the memory 520 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 520 may optionally include memory located remotely from processor 510, which may be connected to an electronic device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The input device 530 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function control of the electronic apparatus. The output device 540 may include a display device such as a display screen.
Example six
A sixth embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements a method for enhancing channel estimation, as provided in all embodiments of the present invention: that is, the program when executed by the processor implements:
performing channel estimation according to a pilot signal in a received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
performing edge extension on the initial frequency domain channel estimation value to obtain a frequency domain channel estimation extension value;
and carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
Any combination of one or more computer-readable media may be employed. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + +, or the like, as well as conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A method for enhancing channel estimation, comprising:
performing channel estimation according to a pilot signal in a received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
performing edge extension on the initial frequency domain channel estimation value to obtain a frequency domain channel estimation extension value;
and carrying out transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
2. The method of claim 1, wherein performing edge extension on the initial frequency-domain channel estimate value to obtain a frequency-domain channel estimate extension value comprises:
determining a frequency domain channel estimation value corresponding to each edge extension frequency point;
and generating a frequency domain channel estimation extension value according to the frequency domain channel estimation initial value and the frequency domain channel estimation value corresponding to each edge extension frequency point.
3. The method of claim 2, wherein determining the frequency domain channel estimation value corresponding to each edge spread frequency point comprises:
and determining the frequency domain channel estimation value corresponding to each edge extension frequency point based on a wiener interpolation method.
4. The method of claim 3, wherein determining the frequency domain channel estimation value corresponding to each edge spread frequency point based on wiener interpolation method comprises:
determining a power time delay spectrum corresponding to the pilot signal;
selecting a plurality of points according to the energy distribution of the power time delay spectrum to perform fast Fourier transform to obtain a frequency domain correlation value sequence;
determining a frequency domain interpolation coefficient matrix according to the frequency domain correlation value sequence;
and determining the frequency domain channel estimation value corresponding to each edge extension frequency point according to the frequency domain interpolation coefficient matrix and the frequency domain channel estimation initial value.
5. The method of claim 4, wherein determining a frequency domain interpolation coefficient matrix from the sequence of frequency domain correlation values comprises:
determining a frequency domain self-correlation matrix and a frequency domain cross-correlation matrix according to the frequency domain correlation value sequence;
and taking the product of the frequency domain cross correlation matrix and the inverse matrix of the frequency domain autocorrelation matrix as the frequency domain interpolation coefficient matrix.
6. The method of claim 2, wherein determining the frequency domain channel estimation value corresponding to each edge spread frequency point comprises:
determining a frequency domain channel estimation value of an edge extension frequency point matched with a target boundary frequency point according to a frequency domain channel estimation value corresponding to the target boundary frequency point and a pre-configured extrapolation vector matched with the target boundary frequency point;
wherein the sum of the additions of the elements in the preconfigured extrapolation vector is 1.
7. The method of claim 1, further comprising, prior to transform-domain filtering the frequency-domain channel estimate extension values:
if the number of the frequency points related to the frequency domain channel estimation extension value is less than the number of the pilot frequency points corresponding to the pilot frequency signals, supplementing the frequency points related to the frequency domain channel estimation extension value so as to enable the number of the supplemented frequency points to be equal to the number of the pilot frequency points;
performing transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value, including:
performing inverse fast Fourier transform and gain adjustment on the frequency domain channel estimation extension value to obtain a time domain channel estimation extension value;
determining a power filtering threshold, and carrying out filtering processing on the time domain channel estimation extension value according to the power filtering threshold to obtain a time domain channel estimation enhancement value;
and carrying out fast Fourier transform, interception processing and gain adjustment on the time domain channel estimation enhancement value to obtain the frequency domain channel estimation enhancement value.
8. An apparatus for enhancing channel estimation, comprising:
the frequency domain channel estimation initial value acquisition module is arranged for carrying out channel estimation according to the pilot signal in the received signal by adopting a preset algorithm to obtain a frequency domain channel estimation initial value;
the frequency domain channel estimation extension value acquisition module is used for performing edge extension on the frequency domain channel estimation initial value to obtain a frequency domain channel estimation extension value;
and the frequency domain channel estimation enhancement value acquisition module is configured to perform transform domain filtering on the frequency domain channel estimation extension value to obtain a frequency domain channel estimation enhancement value.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method according to any of claims 1-7 when executing the program.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to any one of claims 1-7.
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