CN117527486A - Channel estimation implementation method under high-speed mobile scene - Google Patents

Channel estimation implementation method under high-speed mobile scene Download PDF

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Publication number
CN117527486A
CN117527486A CN202311351653.XA CN202311351653A CN117527486A CN 117527486 A CN117527486 A CN 117527486A CN 202311351653 A CN202311351653 A CN 202311351653A CN 117527486 A CN117527486 A CN 117527486A
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China
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estimation
channel
interpolation
frequency
frequency offset
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Inventor
吉鹏程
王东明
凌捷
王海龙
刘瑜
倪小龙
陈建平
陈巧英
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Nanjing Ticom Tech Co ltd
Southeast University
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Nanjing Ticom Tech Co ltd
Southeast University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/022—Channel estimation of frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • H04L25/0242—Channel estimation channel estimation algorithms using matrix methods
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0024—Carrier regulation at the receiver end
    • H04L2027/0026—Correction of carrier offset

Abstract

The invention discloses a method for realizing channel estimation under a high-speed mobile scene, which is based on a demodulation reference signal DMRS designed by a 5G NR standard for a transmission time slot, when a receiving end of a 5G CP-OFDM system carries out time domain channel estimation interpolation, firstly, frequency offset and maximum Doppler frequency of a received signal are estimated, frequency offset compensation is carried out on the received signal according to an obtained frequency offset estimated value, a coefficient matrix is obtained according to an obtained maximum Doppler frequency estimated value lookup table, time domain MMSE channel estimation interpolation is carried out, the obtained interpolation result is subjected to frequency offset inverse compensation to obtain a complete channel response estimated value, and the method has a certain performance gain compared with the traditional linear estimation interpolation under the high-speed mobile scene, and is suitable for wireless communication under the 5G high-speed mobile scene.

Description

Channel estimation implementation method under high-speed mobile scene
Technical Field
The invention relates to the technical field of wireless communication transmission, in particular to a method for realizing channel estimation in a high-speed mobile scene.
Background
With the development of 5G NR mobile communication technology, wireless communication technology in a high-speed mobile scenario is attracting attention. In a mobile scenario, the channel will produce small scale time domain fading and appear as doppler frequency. When the moving speed between the receiving and transmitting ends increases, the Doppler frequency of the channel increases, and the time domain fading of the channel is aggravated, so that the time domain channel estimation interpolation performance of the receiving end is worsened. Currently, most practical systems for mobile wireless communication adopt a near estimation interpolation or linear estimation interpolation scheme to complete time domain channel interpolation in channel estimation, and only complete interpolation according to the position relationship between demodulation reference signal DMRS and data symbols, so that the system has better performance under a low-speed scene. However, in high speed scenarios, the channel doppler frequency will have a large impact on the performance of both estimation interpolation schemes. Aiming at the time domain fading problem of the channel, the Minimum Mean Square Error (MMSE) estimation generates a channel interpolation matrix by using a time domain correlation function of the channel, and matrix elements are changed along with the change of Doppler frequency of the channel, so that the method is more suitable for a high-speed moving scene. However, implementation of MMSE estimation interpolation requires the use of doppler information and time-dependent functions of the channel, which are often unpredictable before actual transmission, which also makes system implementation of MMSE estimation interpolation difficult.
Meanwhile, some studies have shown that in uplink transmission of wireless communication in a high-speed mobile scenario, the doppler frequency of a base station side received signal will contain an additional frequency offset component. In practical applications, the system often refers to the frequency of the RRU of the base station as a reference frequency. Then in the downlink transmission, the effective carrier frequency of the signal obtained by the user equipment through Automatic Frequency Control (AFC) will contain the doppler frequency of the downlink channel. Therefore, in uplink transmission, the transmitting signal at the user side transmits the carrier frequency obtained by using the AFC, which is equivalent to introducing an additional frequency offset into the uplink receiving signal, and this component also causes interference to time domain channel estimation interpolation at the receiving end. Therefore, before performing time-domain channel estimation interpolation, it is necessary to estimate and compensate for the frequency offset of the received signal, thereby reducing its influence on the time-domain channel estimation interpolation result.
Disclosure of Invention
The invention provides a channel estimation implementation method in a high-speed moving scene, which aims to solve the problems in the prior art, has a certain performance improvement compared with the traditional linear estimation interpolation adopted by most practical systems in the high-speed moving scene, avoids the cost caused by inversion operation and the like in the real-time calculation MMSE coefficient interpolation matrix, reduces the storage cost of the interpolation coefficient matrix and the circulation times during table lookup on the basis of ensuring the performance gain, and simplifies the system implementation process.
A method for realizing channel estimation in a high-speed mobile scene comprises the following steps:
1) Performing frequency offset estimation according to the channel interpolation result of the DMRS symbol, and performing frequency offset compensation according to the result to obtain the channel estimation value of the DMRS symbol after compensating the frequency offsetMeanwhile, the system estimates the Doppler frequency of the channel through a time domain correlation function of the channel corresponding to the uniform Doppler spectrum;
2) The system looks up the table according to the estimation result of the Doppler frequency of the channel to obtain a pre-stored time domain MMSE-sine estimation interpolation matrix, and compensates the channel estimation value of the DMRS symbol after frequency deviationWeighting is performed to obtain channel estimation values of the data symbols,the principle of time domain MMSE channel estimation interpolation is that an interpolation matrix is generated according to a time domain correlation function of a channel, and the matrix form is as follows:
wherein R is HH_time Andare all correlation matrices, sigma x 2 And sigma (sigma) n 2 Respectively representing the variance of the transmitted signal and the noise variable, wherein I represents an identity matrix; and if the Doppler frequency estimation is the same as the Doppler frequency estimation, selecting a correlation function corresponding to the uniform Doppler spectrum to perform MMSE estimation interpolation, generating elements of a correlation matrix by a sinc function and meeting the relation:
R HH_time [p,p']＝sinc[2f d (l p -l p' )T symb ]
wherein p, p' represent subscripts of the DMRS symbol, l p 、l p' The subscript of the OFDM symbol occupied by DMRS symbols p, p' in the slot is indicated, and l indicates the OFDM symbol subscript. At the same time, since the influence of signal-to-noise ratio is considered in the frequency domain channel interpolation, the interpolation can be omitted, i.e. omitted (sigma) n 2 /σ x 2 ) I, where the coefficient interpolation matrix is expressed as
3) Inverse compensation of frequency offset: after finishing the interpolation of the time domain MMSE-sine channel estimation, the frequency offset inverse compensation needs to be carried out on the obtained channel interpolation results of all the resource units, and the complete channel estimation values on all the resource units are obtained because the frequency offset FO affects the received signals:
the frequency offset estimation process according to the channel interpolation result of the DMRS symbol in step 1) is specifically as follows: assuming that the system has R receiving antennas and T transmitting antennas in total, the length of a time domain OFDM symbol of one time slot (slot) is L, the total number of frequency domain subcarriers is K, and P demodulation reference signal DMRS symbols are arranged in one time slot; after the receiving end system completes the frequency domain channel estimation interpolation, a DMRS symbol channel response estimated value is obtained and recorded asWhere r is a receiving antenna index, t is a transmitting antenna index, p is a DMRS symbol index, and k is a frequency domain subcarrier index.
Based on the estimated value pairThe specific process of compensation is as follows:
the phase difference between adjacent DMRS symbol channel responses is entirely introduced by the frequency offset:
wherein a represents an amplitude attenuation factor representation, f o Frequency offset, l p 、l p+1 Respectively representing time domain symbol subscripts occupied by DMRS symbols p and p+1 in time slot, T symb Is an OFDM symbol interval; firstly, calculating cross correlation coefficients of frequency domain channel response estimated values of two adjacent DMRS symbols p and p+1:
wherein, (g) * Representing the conjugate. Accordingly, one OFDM symbol interval T symb The phase difference estimation value in the phase difference can beExpressed as:
wherein angle (g) represents the phase angle. When more than two DMRS symbols are configured in the time slot, repeating the algorithm to obtain phase difference estimated values corresponding to each group of adjacent DMRS symbols, and obtaining a final estimated result through averaging:
for the subsequent compensation operation, the result of the frequency offset estimation is kept in a phase form, and after the estimation result is obtained, the system performs frequency offset compensation on the channel response estimation value of the symbol position of the DMRS, so that the influence on time channel interpolation is reduced:
the specific process of channel Doppler frequency estimation in the step 1) is as follows:
selecting a correlation function corresponding to the uniform Doppler spectrum for Doppler estimation, the correlation function expressed as
R(Δl·T symb )＝sinc(2f d Δl·T symb )
Firstly, calculating an autocorrelation coefficient according to a channel response estimated value of a DMRS symbol:
wherein sigma 2 The noise power obtained by the system estimation;
and calculating cross-correlation coefficients between adjacent DMRS symbols and taking a modulus, wherein the expression is as follows:
the parameter may be defined by R in the frequency offset estimate p,p+1 Taking a mould to obtain;
r is according to the expression of the correlation function 0 、R 1 And Doppler frequency f d The following relationships are satisfied:
meanwhile, taylor expansion of the function sinc (x) at x=0 is
Therefore, doppler frequency estimation value f obtained from DMRS symbols p, p+1 d,p Represented as
When more than two DMRS symbols are configured in a time slot, repeating the algorithm to obtain the doppler frequency estimation value of each group of adjacent DMRS symbols, and obtaining the final estimation result through averaging:
the invention has the beneficial effects that:
(1) The system implementation method of the time domain MMSE channel estimation interpolation is provided, and compared with the traditional linear estimation interpolation adopted by most practical systems, the system implementation method has a certain performance improvement in a high-speed moving scene;
(2) By means of matrix pre-generation and interval division, the cost caused by inversion operation and the like in the MMSE coefficient interpolation matrix is avoided, meanwhile, on the basis of guaranteeing performance gain, the storage cost of the interpolation coefficient matrix and the circulation times during table lookup are reduced, and the system implementation process is simplified.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of steps of a method for implementing MMSE-sinc channel estimation interpolation segmentation;
figure 2 is a schematic diagram of the system BLER performance.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 1 shows a schematic implementation flow of the implementation of MMSE-sinc channel estimation interpolation segmentation in the high-speed mobile scenario of the present patent, and in more detail, the implementation flow includes the following steps:
frequency offset estimation and compensation based on additional DMRS:
assuming that the system has R receiving antennas and T transmitting antennas in total, the time domain OFDM symbol length of one slot (slot) is L, the total number of frequency domain subcarriers is K, and P demodulation reference signal DMRS symbols are set in one slot. After the receiving end system completes the frequency domain channel estimation interpolation, a DMRS symbol channel response estimated value is obtained and recorded asWhere r is a receiving antenna index, t is a transmitting antenna index, p is a DMRS symbol index, and k is a frequency domain subcarrier index. To reduce frequency offset to time domainThe influence of channel estimation interpolation requires estimating the frequency offset component in the received signal and based on the estimated value pair +.>And compensating. In a high-speed mobile scenario, additional DMRS symbols are usually required to be set in one time slot to provide more reference information, so as to adapt to time-varying characteristics of a channel in the high-speed mobile scenario, and frequency offset is estimated by directly using channel response estimated values of the DMRS symbols based on frequency offset estimation of the additional DMRS.
Ideally, the phase difference between adjacent DMRS symbol channel responses is entirely introduced by the frequency offset:
wherein a represents an amplitude attenuation factor representation, f o Frequency offset, l p 、l p+1 Respectively representing time domain symbol subscripts occupied by DMRS symbols p and p+1 in time slot, T symb Is an OFDM symbol interval. Therefore, to obtain an estimated value of the frequency offset, first, the cross correlation coefficient of the frequency domain channel response estimated values of the two adjacent DMRS symbols p, p+1 is calculated:
wherein, (g) * Representing the conjugate. Accordingly, one OFDM symbol interval T symb The phase difference estimate within can be expressed as:
wherein angle (g) represents the phase angle. When more than two DMRS symbols are configured in the time slot, repeating the algorithm to obtain phase difference estimated values corresponding to each group of adjacent DMRS symbols, and obtaining a final estimated result through averaging:
for the subsequent compensation operation, the result of the frequency offset estimation is kept in phase form, and phase-to-frequency conversion is not necessary. After the estimation result is obtained, the system performs frequency offset compensation on the channel response estimation value of the DMRS symbol position, so that the influence on time channel interpolation is reduced:
doppler estimation based on uniform Doppler spectrum:
for time domain channel interpolation, the Doppler frequency f of the channel in the current time slot needs to be known when MMSE-sine estimation interpolation is adopted d Thereby generating an interpolation coefficient matrix. In practical implementations, the system often cannot acquire the doppler frequency in advance, and therefore the doppler frequency needs to be estimated.
Like the MMSE estimation interpolation algorithm, the current doppler estimation is mainly based on the time domain correlation function of the channel, but it cannot be obtained in advance in the actual process. Therefore, one method is to preset a correlation function, and derive a derived relationship between the correlation function value and the doppler frequency according to a preset expression. In view of the adaptability to different channels, a correlation function corresponding to the uniform Doppler spectrum is selected for Doppler estimation, and can be expressed as
R(Δl·T symb )＝sinc(2f d Δl·T symb )
Therefore, to obtain an estimated value of the doppler frequency, an autocorrelation coefficient is first calculated from the channel response estimated value of the DMRS symbol:
wherein sigma 2 Is the noise power estimated by the system. Further, calculating and modulo the cross-correlation coefficient between adjacent DMRS symbols, where the expression is:
the parameter may be defined by R in the frequency offset estimate p,p+1 And (5) taking a mould to obtain the product. R is according to the expression of the correlation function 0 、R 1 And Doppler frequency f d The following relationships are satisfied:
meanwhile, taylor expansion of the function sinc (x) at x=0 is
Therefore, doppler frequency estimation value f obtained from DMRS symbols p, p+1 d,p Can be expressed as
When more than two DMRS symbols are configured in a time slot, repeating the algorithm to obtain the doppler frequency estimation value of each group of adjacent DMRS symbols, and obtaining the final estimation result through averaging:
the DMRS symbol channel estimation values used in the doppler estimation are not yet frequency offset compensated, so this step can be performed simultaneously with the frequency offset estimation.
Time domain segmentation MMSE-sine estimation interpolation:
obtainingAfter the channel Doppler frequency estimation value, the system will look up a table according to the estimation result to obtain a pre-stored time domain MMSE-sine estimation interpolation matrix, and the channel estimation value of the DMRS symbol after compensating the frequency offsetAnd weighting to obtain the channel estimation value of the data symbol. The principle of time domain MMSE channel estimation interpolation is that an interpolation matrix is generated according to a time domain correlation function of a channel, and the matrix form is as follows:
wherein R is HH_time Andare all correlation matrices, sigma x 2 And sigma (sigma) n 2 The variance of the transmitted signal and noise variable is represented, respectively, and I represents the identity matrix. And if the Doppler frequency estimation is the same as the Doppler frequency estimation, selecting a correlation function corresponding to the uniform Doppler spectrum to perform MMSE estimation interpolation, generating elements of a correlation matrix by a sinc function and meeting the relation:
R HH_time [p,p']＝sinc[2f d (l p -l p' )T symb ]
wherein p, p' represent subscripts of the DMRS symbol, l p 、l p' The subscript of the OFDM symbol occupied by DMRS symbols p, p' in the slot is indicated, and l indicates the OFDM symbol subscript. At the same time, since the influence of signal-to-noise ratio is considered in the frequency domain channel interpolation, the interpolation can be omitted, i.e. omitted (sigma) n 2 /σ x 2 ) I, in which case the coefficient interpolation matrix may be expressed as
In practical application, in order to reduce the storage overhead of the pre-generated coefficient matrix and the complexity of the table look-up, the system only generates the coefficient matrix corresponding to the intermittent limited Doppler frequencies. After Doppler estimation is carried out by the system, the Doppler estimation is carried out according to the estimated valueWith Doppler frequency f at maximum velocity d max The ratio of (2) is in the interval to select the corresponding matrix to complete interpolation, and the specific segmentation condition is shown in the following table.
TABLE 1MMSE-sinc interpolation coefficient matrix interval partitioning
After coefficient matrix is obtained, the system compensates the frequency offset according to the interpolation coefficientWeighting is carried out, and the matrix form of the element is expressed as follows:
wherein, (g) T The transpose is represented by the number,dimension K x P->The dimension is k×l for channel estimates over all resource units. And finishing time domain MMSE-sine channel estimation interpolation of all data streams by traversing the receiving antennas and the transmitting antennas.
Inverse compensation of frequency offset:
after finishing the interpolation of the time domain MMSE-sine channel estimation, the frequency offset inverse compensation needs to be carried out on the obtained channel interpolation results of all the resource units, and the complete channel estimation values on all the resource units are obtained because the frequency offset FO affects the received signals:
figure 2 shows the system BLER performance comparison of a time domain MMSE-sinc channel estimation interpolation segmentation implementation with a conventional linear estimation interpolation scheme at a mobile speed of 1000 km/h. It can be seen that the system BLER performance using the time domain channel estimation interpolation scheme of this patent is significantly improved over conventional linear estimation interpolation within the confidence interval. While the linear estimation interpolation scheme has an error floor at a signal-to-noise ratio of 18dB, the system BLER performance of the scheme still has a gain with increasing signal-to-noise ratio, and the signal-to-noise ratio has a gain of about 3dB at a BLER equal to its error floor. The system parameter configuration for corresponding 3 is shown in the following table.
Table 2 simulation system parameter configuration
Simulation system parameters Parameter value Simulation system parameters Parameter value
Emulation channel PUSCH Subcarrier spacing 15kHz
Carrier frequency 700MHz FFT point number 1024
Bandwidth of a communication device 10MHz Number of time slot symbols 14
Modulation scheme QPSK Channel coding LDPC
Number of antennas 1T1R DMRS type Type A, type 1
Additional DMRS symbol number 3 DMRS start symbol subscript 2
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the equipment examples, what has been described above is merely a preferred embodiment of the invention, which, since it is substantially similar to the method examples, is described relatively simply, as relevant to the description of the method examples. The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, since modifications and substitutions will be readily made by those skilled in the art without departing from the spirit of the invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (4)

1. The method for realizing channel estimation in the high-speed mobile scene is characterized by comprising the following steps:
1) Performing frequency offset estimation according to the channel interpolation result of the DMRS symbol, and performing frequency offset compensation according to the result to obtain the channel estimation value of the DMRS symbol after compensating the frequency offsetMeanwhile, the system estimates the Doppler frequency of the channel through a time domain correlation function of the channel corresponding to the uniform Doppler spectrum;
2) The system looks up the table according to the estimation result of the Doppler frequency of the channel to obtain a pre-stored time domain MMSE-sine estimation interpolation matrix, and compensates the channel estimation value of the DMRS symbol after frequency deviationThe principle of the time domain MMSE channel estimation interpolation is to generate an interpolation matrix according to a time domain correlation function of a channel, wherein the matrix is as follows:
wherein R is HH_time Andare all correlation matrices, sigma x 2 And sigma (sigma) n 2 Respectively representing the variance of the transmitted signal and the noise variable, wherein I represents an identity matrix; like Doppler frequency estimation, the corresponding uniform doppler is selectedPerforming MMSE estimation interpolation on the related function of the Doppler spectrum, wherein elements of the related matrix are generated by a sinc function and satisfy the relation:
R HH_time [p,p']＝sinc[2f d (l p -l p' )T symb ]
wherein p, p' represent subscripts of the DMRS symbol, l p 、l p' The subscript of the OFDM symbol occupied by DMRS symbols p, p' in the slot is indicated, and l indicates the OFDM symbol subscript. At the same time, since the influence of signal-to-noise ratio is considered in the frequency domain channel interpolation, the interpolation can be omitted, i.e. omitted (sigma) n 2 /σ x 2 ) I, where the coefficient interpolation matrix is expressed as
3) Inverse compensation of frequency offset: after finishing the interpolation of the time domain MMSE-sine channel estimation, the frequency offset inverse compensation needs to be carried out on the obtained channel interpolation results of all the resource units, and the complete channel estimation values on all the resource units are obtained because the frequency offset FO affects the received signals:
2. the method for implementing channel estimation in a high-speed mobile scenario according to claim 1, wherein: the frequency offset estimation process according to the channel interpolation result of the DMRS symbol in step 1) is specifically as follows: assuming that the system has R receiving antennas and T transmitting antennas in total, the length of a time domain OFDM symbol of one time slot (slot) is L, the total number of frequency domain subcarriers is K, and P demodulation reference signal DMRS symbols are arranged in one time slot; at the receiving sideAfter the end system completes the frequency domain channel estimation interpolation, the DMRS symbol channel response estimated value is obtained and recorded asWhere r is a receiving antenna index, t is a transmitting antenna index, p is a DMRS symbol index, and k is a frequency domain subcarrier index.
3. The method for implementing channel estimation in a high-speed mobile scenario according to claim 2, wherein: based on the estimated value pairThe specific process of compensation is as follows:
the phase difference between adjacent DMRS symbol channel responses is entirely introduced by the frequency offset:
wherein a represents an amplitude attenuation factor representation, f o Frequency offset, l p 、l p+1 Respectively representing time domain symbol subscripts occupied by DMRS symbols p and p+1 in time slot, T symb Is an OFDM symbol interval; firstly, calculating cross correlation coefficients of frequency domain channel response estimated values of two adjacent DMRS symbols p and p+1:
wherein, (g) * Representing the conjugate. Accordingly, one OFDM symbol interval T symb The phase difference estimate within can be expressed as:
wherein angle (g) represents the phase angle. When more than two DMRS symbols are configured in the time slot, repeating the algorithm to obtain phase difference estimated values corresponding to each group of adjacent DMRS symbols, and obtaining a final estimated result through averaging:
for the subsequent compensation operation, the result of the frequency offset estimation is kept in a phase form, and after the estimation result is obtained, the system performs frequency offset compensation on the channel response estimation value of the symbol position of the DMRS, so that the influence on time channel interpolation is reduced:
4. the method for implementing channel estimation in a high-speed mobile scenario according to claim 1, wherein: the specific process of channel Doppler frequency estimation in the step 1) is as follows:
selecting a correlation function corresponding to the uniform Doppler spectrum for Doppler estimation, the correlation function expressed as
R(Δl·T symb )＝sinc(2f d Δl·T symb )
Firstly, calculating an autocorrelation coefficient according to a channel response estimated value of a DMRS symbol:
wherein sigma 2 The noise power obtained by the system estimation;
and calculating cross-correlation coefficients between adjacent DMRS symbols and taking a modulus, wherein the expression is as follows:
the parameter may be defined by R in the frequency offset estimate p,p+1 Taking a mould to obtain;
r is according to the expression of the correlation function 0 、R 1 And Doppler frequency f d The following relationships are satisfied:
meanwhile, taylor expansion of the function sinc (x) at x=0 is
Therefore, doppler frequency estimation value f obtained from DMRS symbols p, p+1 d,p Represented as
When more than two DMRS symbols are configured in a time slot, repeating the algorithm to obtain the doppler frequency estimation value of each group of adjacent DMRS symbols, and obtaining the final estimation result through averaging:
CN202311351653.XA 2023-10-18 2023-10-18 Channel estimation implementation method under high-speed mobile scene Pending CN117527486A (en)

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