WO2016061796A1

WO2016061796A1 - Channel estimation method and apparatus

Info

Publication number: WO2016061796A1
Application number: PCT/CN2014/089333
Authority: WO
Inventors: 薛鑫; 颜敏; 董超科
Original assignee: 华为技术有限公司
Priority date: 2014-10-23
Filing date: 2014-10-23
Publication date: 2016-04-28
Also published as: CN106576086B; CN106576086A

Abstract

Embodiments of the present invention relate to the technical field of communications. Provided are a channel estimation method and apparatus. The method comprises: obtaining a channel estimation value of a data carrier after conducting initial channel estimation on the data carrier in a received signal and conducting gamma factor elimination processing; obtaining channel estimation values of a null carrier and a pilot carrier after conducting filling processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier; acquiring a modulation mode of the received signal, and determining a tap coefficient of a filter according to the modulation mode; conducting, in the filter, frequency-domain filtering on the channel estimation value of the data carrier and the channel estimation values of the null carrier and the pilot carrier according to the determined tap coefficient; and obtaining a final channel estimation value of the data carrier after conducting gamma factor addition processing on the filtered channel estimation value of the data carrier. In the present invention, frequency-domain filtering is conducted on the basis of an LS algorithm so as to decrease a channel error, thereby reducing the complexity of operations as well as the time delay, and improving the efficiency of channel estimation.

Description

Channel estimation method and device

Technical field

The present invention relates to the field of communications technologies, and in particular, to a method and apparatus for channel estimation.

Background technique

In the WiFi (English: Wireless-Fidelity) chip baseband processing, the channel estimation quality will directly affect the product performance of the chip, so a simple and excellent channel estimation algorithm will greatly enhance the product. Competitiveness. There is a 3dB performance error between the existing LS (English: Least Square) algorithm compared to the ideal channel estimation algorithm. In order to reduce the error, the general processing method is to filter the initial channel estimation value obtained by the LS algorithm to improve the accuracy of the channel estimation value.

At present, the filtering processing method for the initial channel estimation value is: first, the initial channel estimation value is transformed into the time domain by IFFT (English: Inverse Fast Fourier Transform, referred to as: Fast Fourier Transform), and is performed in the time domain. Time domain filtering, retaining multipath information within the length of CP (English: Cycle Prefix, referred to as cyclic prefix), filtering out noise interference outside multipath, and then passing FFT (English: Fast Fourier Transformation, referred to as: Fast Fourier Transform) transforms to the frequency domain channel. In the existing WiFi system, the transmitted signal is processed by CSD (Cyclic Shift Diversity, referred to as diversity cyclic shift), and the processing is equivalent to the distribution of the multipath in the initial channel estimation value in the channel. At both ends, it is necessary to shift the energy of the right end to the left end before the time domain filtering process, and then perform time domain filtering processing, and shift it back to the right end after the time domain filtering process.

The inventors have found that the prior art has at least the following problems:

In the above filtering process, it is necessary to switch back and forth between the time domain/frequency domain, and the energy shift needs to be performed before the time domain filtering and the time domain filtering. From the perspective of hardware implementation, the delay and the resource complexity are both Greatly increased, reducing the efficiency of channel estimation.

Summary of the invention

In order to solve the defects of the prior art, the embodiments of the present invention provide a method and an apparatus for channel estimation. The technical solution is as follows:

The first aspect, a method for channel estimation, includes:

Performing initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier;

And performing a padding process on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier;

Obtaining a modulation mode of the received signal, and determining a tap coefficient of the filter according to the modulation mode;

Performing frequency domain filtering on the channel estimate of the data carrier and the channel estimate of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; time domain characteristics of the filter including diversity Channel multipath information affected by cyclic shift CSD;

After the gamma factor adding process is performed on the filtered channel estimation value of the data carrier, a channel estimation value of the final data carrier is obtained.

In a first possible implementation manner of the first aspect, the null carrier and the pilot carrier in the received signal are padded according to a channel estimation value of the data carrier, and the null carrier and the guide are obtained. The channel estimate of the frequency carrier, including:

Determining a communication standard of the received signal according to a preamble sequence in the received signal;

If the communication standard of the received signal is 802.11ac, determining the locations of the null carrier and the pilot carrier according to the orthogonal frequency division multiplexing OFDM symbols in the received signal;

And performing a padding process on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier. .

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the determining, according to a location of the null carrier and a pilot carrier, and a channel estimation value of the data carrier, Performing a padding process on the null carrier and the pilot carrier in the received signal to obtain channel estimation values of the null carrier and the pilot carrier, including:

If the location of the null carrier and the pilot carrier is located in the guard band, determining a channel estimate of the data carrier closest to the location of the null carrier and the pilot carrier as the channel estimate of the null carrier and the pilot carrier ;

If the location of the null carrier and the pilot carrier is in the non-protection band, determining the null carrier and the channel by linear interpolation according to channel estimation values of the data carriers located at positions before and after the null carrier and the pilot carrier The channel estimate of the frequency carrier.

In a third possible implementation manner of the first aspect, the selecting a tap coefficient of the filter according to the modulation manner includes:

If the modulation mode is low-order modulation, a preset first tap coefficient is selected as the tap coefficient of the filter.

In a fourth possible implementation manner of the first aspect, the selecting a tap coefficient of the filter according to the modulation manner includes:

If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio, a preset second tap coefficient is selected as the tap coefficient of the filter.

In a fifth possible implementation manner of the first aspect, the selecting a tap coefficient in the filter according to the modulation mode and the signal to noise ratio further includes:

If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier are not used. The domain filtering process determines the channel estimate of the data carrier as the channel estimate of the final data carrier.

A second aspect, a device for channel estimation, comprising:

An initial estimation module, configured to perform initial channel estimation on the data carrier in the received signal;

An elimination processing module, configured to obtain a channel estimation value of the data carrier after performing gamma factor elimination processing;

a padding processing module, configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier, to obtain channel estimation values of the null carrier and the pilot carrier;

a first determining module, configured to acquire a modulation mode of the received signal, and determine a tap coefficient of the filter according to the modulation mode;

a filtering module, configured to perform frequency domain filtering on a channel estimation value of the data carrier and a channel estimation value of the null carrier and a pilot carrier in the filter according to the determined tap coefficient; The time domain feature includes channel multipath information affected by the diversity cyclic shift CSD;

And adding a processing module, configured to perform a gamma factor adding process on the filtered channel estimation value of the data carrier, to obtain a channel estimation value of the final data carrier.

In a first possible implementation manner of the second aspect, the padding processing module includes:

a first determining unit, configured to determine the received signal according to a preamble sequence in the received signal Communication standard;

a second determining unit, configured to determine, according to the orthogonal frequency division multiplexing OFDM symbol in the received signal, a location of the null carrier and a pilot carrier if the communication standard of the received signal is 802.11ac;

a padding processing unit, configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain the null carrier and the guide The channel estimate of the frequency carrier.

In conjunction with the first possible implementation of the second aspect, in a second possible implementation of the second aspect, the padding processing unit includes:

a first padding processing subunit, configured to determine, if the location of the null carrier and the pilot carrier is in a guard band, a channel estimation value of a data carrier that is closest to a location of the null carrier and the pilot carrier as the null Channel estimation values for carrier and pilot carriers;

a second padding processing sub-unit, configured to linearly interpolate channel estimation values of data carriers located at positions before and after the null carrier and the pilot carrier if the locations of the null carrier and the pilot carrier are located in the unprotected band In a manner, a channel estimate of the null carrier and the pilot carrier is determined.

In a third possible implementation manner of the second aspect, the first determining module includes:

And a first selecting unit, configured to select a preset first tap coefficient as the tap coefficient of the filter if the modulation mode is low-order modulation.

In a fourth possible implementation of the second aspect, the first determining module includes:

a second selecting unit, configured to select a preset second tap coefficient as the tap of the filter if the modulation mode is high-order modulation and a signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio coefficient.

In a fifth possible implementation manner of the second aspect, the device further includes:

a second determining module, configured to: if the modulation mode is high-order modulation, and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, do not estimate channel values of the data carrier, and the null carrier and pilot The channel estimation value of the carrier performs frequency domain filtering processing, and determines a channel estimation value of the data carrier as a channel estimation value of the final data carrier.

A third aspect, a transceiver device, comprising: a processor and a transceiver,

The processor is configured to perform initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier; and according to the channel estimation value of the data carrier, in the received signal The null carrier and the pilot carrier are padded to obtain the null carrier And a channel estimation value of the pilot carrier; acquiring a modulation mode of the received signal, and determining a tap coefficient of the filter according to the modulation mode; and performing gamma factor addition processing on the filtered channel estimation value of the data carrier, Obtaining a channel estimate of the final data carrier;

The transceiver is configured to perform frequency domain filtering on a channel estimation value of the data carrier and a channel estimation value of the null carrier and a pilot carrier in the filter according to the determined tap coefficient; The time domain characteristics of the device include channel multipath information affected by the diversity cyclic shift CSD.

In a first possible implementation of the third aspect, characterized in that

The processor is further configured to determine a communication standard of the received signal according to a preamble sequence in the received signal; if the communication standard of the received signal is 802.11ac, according to an orthogonal frequency in the received signal Demultiplexing OFDM symbols determining locations of the null carriers and pilot carriers; null carriers and pilots in the received signal based on locations of the null carriers and pilot carriers and channel estimates of the data carriers The carrier performs padding processing to obtain channel estimates of the null carrier and the pilot carrier.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner of the second aspect,

The processor is further configured to determine, if the location of the null carrier and the pilot carrier is in a guard band, a channel estimation value of a data carrier that is closest to a location of the null carrier and the pilot carrier as the null carrier And a channel estimation value of the pilot carrier; if the location of the null carrier and the pilot carrier is in the non-protection band, linearly interpolating according to channel estimation values of the data carriers located at positions before and after the null carrier and the pilot carrier In a manner, a channel estimate of the null carrier and the pilot carrier is determined.

In a third possible implementation of the third aspect, characterized in that

The processor is further configured to: if the modulation mode is low-order modulation, select a preset first tap coefficient as a tap coefficient of the filter.

In a fourth possible implementation of the third aspect, characterized in that

The processor is further configured to: if the modulation mode is high-order modulation and a signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio, select a preset second tap coefficient as the filter Tap coefficient.

In a fifth possible implementation of the third aspect, characterized in that

The processor is further configured to: if the modulation mode is high-order modulation, and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, the channel estimation value of the data carrier and the null carrier and the guide are not used. The channel estimate of the frequency carrier is subjected to frequency domain filtering processing, and the channel estimation value of the data carrier is determined as the channel estimation value of the final data carrier.

The technical solution provided by the embodiment of the present invention obtains a channel estimation value of the data carrier by performing initial channel estimation and gamma factor elimination processing on the data carrier in the received signal, and receiving the channel according to the channel estimation value of the data carrier. The null carrier and the pilot carrier in the signal are padded to obtain channel estimation values of the null carrier and the pilot carrier, and the tap coefficients of the filter are selected according to the modulation mode of the received signal, and the channel estimation value of the data carrier is obtained. And performing frequency domain filtering on the channel estimates of the null carrier and the pilot carrier, and performing gamma factor addition processing on the channel estimation value of the filtered data carrier to obtain a channel estimation value of the final data carrier. On the basis of the LS algorithm, only the frequency domain filtering can reduce the channel error of the channel estimation value of the data carrier, reduce the complexity and delay of the operation, and improve the efficiency of channel estimation.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present invention. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work.

1 is a flowchart of a method for channel estimation according to Embodiment 1 of the present invention;

2 is a flowchart of a method for channel estimation according to Embodiment 2 of the present invention;

3 is a schematic diagram of a simulation result provided in a method for channel estimation according to Embodiment 2 of the present invention;

4 is a schematic diagram of another simulation result provided in the method for channel estimation according to Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram of another simulation result provided in the method for channel estimation according to Embodiment 2 of the present invention; FIG.

6 is a schematic diagram of another simulation result provided in the method for channel estimation according to Embodiment 2 of the present invention;

7 is a schematic diagram of another simulation result provided in the method for channel estimation according to Embodiment 2 of the present invention;

8 is a schematic structural diagram of an apparatus for channel estimation according to Embodiment 3 of the present invention;

FIG. 9 is a schematic structural diagram of a transceiver device according to Embodiment 4 of the present invention.

detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Example 1

The embodiment of the present invention provides a method for channel estimation, as shown in FIG. 1 . The method includes:

101: Perform initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier;

Step 102: Perform padding processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier, and obtain channel estimation values of the null carrier and the pilot carrier.

103: Obtain a modulation mode of the received signal, and determine a tap coefficient of the filter according to the modulation mode;

104: Perform frequency domain filtering on the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; the time domain characteristic of the filter includes multiple channels affected by the diversity cyclic shift CSD Path information

105: Perform gamma factor adding processing on the channel estimation value of the filtered data carrier, and obtain a channel estimation value of the final data carrier.

In the embodiment of the present invention, the channel estimation value of the data carrier is obtained by performing initial channel estimation and gamma factor elimination processing on the data carrier in the received signal, and performing null carrier and pilot carrier in the received signal according to the channel estimation value of the data carrier. After filling, the channel estimation values of the null carrier and the pilot carrier are obtained, and the tap coefficients of the filter are selected according to the modulation mode of the received signal, and the channel estimation value of the data carrier and the channel estimation values of the null carrier and the pilot carrier are performed in the frequency domain. Filtering, and performing gamma factor addition processing on the channel estimation value of the filtered data carrier to obtain a channel estimation value of the final data carrier. On the basis of the LS algorithm, only the frequency domain filtering can reduce the channel error of the channel estimation value of the data carrier, reduce the complexity and delay of the operation, and improve the efficiency of channel estimation.

Example 2

The embodiment of the present invention provides a method for channel estimation, as shown in FIG. 2 . The method includes:

201: Perform initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier.

After receiving the received signal, the receiver converts the received signal into a frequency domain signal by FFT. The operation of the LS algorithm is performed on each data carrier portion of the frequency domain signal.

In addition, since the channel characteristic of Wifi is a slowly changing channel, in order to reduce PAPR at the transmitting end (English) Text: Peak to Average Power Ratio (abbreviation: peak-to-average power ratio) increases the gamma factor processing, and changes the slowly changing channel to a sudden change channel. In the filtering process, the channel is first restored to a slowly changing channel, so the gamma must be eliminated first. The effect is to interpolate the null carrier position in the initial channel estimate with the pilot position and add back the gamma effect after the subsequent filtering operation.

Wherein, the method for performing gamma factor elimination processing on the initial channel estimation value is:

The gamma value corresponding to the initial channel estimation value is determined according to the position of the different subcarriers of the OFDM symbol in the received signal, wherein the gamma value may include: +1/-1/+j/-j. In the embodiment of the present invention, the manner of the removal process is the initial channel estimation value divided by the gamma value corresponding to the channel estimation value of the data carrier.

Therefore, the removal process can be specifically:

The gamma value corresponding to the data carrier is determined according to the position of the different subcarriers of the OFDM symbol in the received signal, and the channel estimation value of the data carrier is divided by the gamma value to obtain a channel estimation value of the removed data carrier.

Step 202: Perform padding processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier, and obtain channel estimation values of the null carrier and the pilot carrier.

In this step, the channel estimates of the null carrier and the pilot carrier in the received signal are calculated to better optimize the filtered performance of the channel estimate for the data carrier. Step 202 can be implemented by the following steps:

2021: Determine a communication standard of the received signal according to the preamble sequence in the received signal;

2022: If the communication standard of the received signal is 802.11ac, the positions of the null carrier and the pilot carrier are determined according to the orthogonal frequency division multiplexing OFDM symbols in the received signal.

2023: Perform padding processing on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier.

Wherein, the manner of padding processing can be selected according to the positions of the null carrier and the pilot carrier:

If the location of the null carrier and the pilot carrier is in the guard band, the channel estimate of the data carrier closest to the location of the null carrier and the pilot carrier is determined as the channel estimate of the null carrier and the pilot carrier.

If the locations of the null carrier and the pilot carrier are in the non-protection band, the channel estimates of the null carrier and the pilot carrier are determined by linear interpolation according to the channel estimation values of the data carriers located at the positions of the null carrier and the pilot carrier. .

Wherein, the method for linear interpolation is not limited, and a null carrier or a pilot carrier may be selected. The data channel information of each data carrier before and after the position is linearly interpolated, and the channel information of the N data data carriers before and after the null carrier or the pilot carrier position may be selected for linear interpolation.

For example, when the channel information of each data carrier before and after the null carrier or the pilot carrier position is selected for linear interpolation, the channel information of the null carrier or the pilot position carrier may be determined according to (a+b)/2. Where: a and b respectively represent channel information of one data carrier before and after the null carrier or pilot carrier position.

Further, if the communication standard of the received signal is 802.11n, the following steps are performed:

If the communication standard of the received signal is 802.11n, the channel information in the null carrier position and the pilot position in the initial channel estimation value is not padded.

203: Acquire a modulation mode of the received signal, and determine a tap coefficient of the filter according to the modulation mode.

The modulation mode of the received signal can be determined by detecting the MCS (Modulation and Coding Scheme, hereinafter referred to as: Modulation and Coding Scheme) value in the HT/VHT-SIG domain. The modulation method may include a low-order modulation method or a high-order modulation method. The low-order modulation mode may include the following methods: BPSK (English: Binary Phase Shift Keying, referred to as: Binary Phase Shift Keying) or QPSK (English: Quadrature Phase Shift Keying, referred to as: Quadrature Phase Shift Keying) or 16QAM (English: Quadrature Amplitude Modulation, abbreviation: Quadrature Amplitude Modulation); The high-order modulation mode can include the following modes: 64QAM or 256QAM.

When the detected modulation mode is a low-order modulation mode, the tap coefficient 17 with the best filtering effect in the simulation process is selected as the selection result.

Correspondingly, step 203 can be implemented by the following steps:

2031: If the modulation mode is low-order modulation, the preset first tap coefficient is selected as the tap coefficient of the filter. Wherein, the first tap coefficient is a tap coefficient of 17.

As shown in FIG. 3, a schematic diagram of a simulation result is shown in the figure, which is an ideal channel estimation, a conventional LS, in a scenario where the modulation mode is low-order modulation (BPSK/QPSK/16QAM) single-antenna transmission and reception in MCS0~4. The channel estimation algorithm, the prior art channel estimation algorithm, and the performance comparison of the channel estimation algorithm in the embodiment of the present invention with the tap coefficient of 17 are selected. By the filtering processing of the tap coefficient 17, the performance is improved by >=1 dB than the LS scheme;

As shown in FIG. 4, another simulation result diagram is shown in the figure, which is ideal for the scenario of MCS4 (16QAM) MIMO (Multiple-Input Multiple-Output, Multiple Input Multiple Output). Channel estimation, traditional LS channel estimation algorithm, and performance comparison of the channel estimation algorithm in the embodiment of the present invention with a tap coefficient of 17, through the filtering processing of the tap coefficient 17, Can be 1dB better than the LS scheme.

When the modulation mode is a high-order modulation mode, it is necessary to jointly determine the tap coefficients of the selected filter according to the signal-to-noise ratio of the received signal and the modulation mode. The specific process is: when the detected modulation mode is a high-order modulation mode, comparing the signal-to-noise ratio of the received signal with a preset signal-to-noise ratio, if the signal-to-noise ratio of the received signal is less than or equal to the preset signal-to-noise ratio Then, the tap coefficient 5 with the best filtering effect in the simulation process is selected as the selection result. Among them, the preset signal to noise ratio can be 33dB. Correspondingly, when the modulation mode is high-order modulation mode in step 203, the following steps can be implemented:

2032: If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is less than or equal to the preset signal-to-noise ratio, the preset second tap coefficient is selected as the tap coefficient of the filter.

As shown in FIG. 5, another simulation result diagram is shown in the figure, which is an ideal channel estimation, a conventional LS channel estimation algorithm, a prior art channel estimation algorithm, and a tap coefficient of 5 and 64QAM single antenna transmission and reception scenarios. 17: Performance comparison of the channel estimation algorithm in the embodiment of the present invention. With the tap coefficient 5 filtering process, the performance is improved by about 0.5 dB compared to the LS scheme.

As shown in FIG. 6, another simulation result diagram is shown in the figure, which is an ideal channel estimation when the signal-to-noise ratio is <33 dB in the case of 256QAM modulation, and the conventional LS channel estimation algorithm has a tap coefficient of 5 when the present invention is implemented. Performance comparison of the channel estimation algorithm in the example. The performance is better than the LS scheme by the tap coefficient 5 filtering process.

As shown in FIG. 7 , another simulation result diagram is shown in the figure. The simulation result in the figure shows that different modulation and coding schemes are different for different taps when the signal to noise ratio is lower than the preset signal to noise ratio. The performance comparison of coefficient selection, in which the high-order modulation mode is filtered by the tap coefficient 5, the performance ratio is better than that by the tap coefficient 17 filtering; the low-order modulation mode is filtered by the tap coefficient 17 , and the performance ratio is filtered by the tap coefficient 5 Better.

Further, if the signal to noise ratio of the received signal is greater than the preset signal to noise ratio, step 206 is performed.

204: Perform frequency domain filtering on the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; the time domain characteristic of the filter includes multiple channels affected by the diversity cyclic shift CSD Trail information.

Since the multipath taps of the channel estimates of the data carrier affected by the CSD are distributed at both ends, it is necessary to set parameters for the filter in the filter design so that the time domain characteristics of the filter include diversity cyclic shift CSD influence. The channel multipath information, and the time domain appears to be symmetrical.

Specifically, the time domain representation characteristic of the filter for the 802.11a/n/ac standard is: the duration is 3.2 us; the time-domain performance characteristic of the front-back symmetry is: the passband length is (0.8+0.8) us.

Further, in the filter design, it is necessary to use the MSE (English: Mean Square Error) value of the channel filtered by the filter and the ideal channel, which needs to be lower than the MSE value of the channel before filtering, and the difference As large as possible.

205: Perform gamma factor adding processing on the channel estimation value of the filtered data carrier, and obtain a channel estimation value of the final data carrier.

The gamma factor addition process in this step is opposite to the process of the gamma factor elimination process in step 201. The method for adding the process is the initial channel estimation value multiplied by the gamma value corresponding to the initial channel estimation value, wherein the gamma value may include: 1/-1/+j/-j.

The channel estimation value of the filtered null carrier and the pilot carrier is not useful for restoring the original data in the received signal. Therefore, in this step, only the channel estimation value of the filtered data carrier is selected for the gamma factor addition process and the final result is obtained. The channel estimate of the data carrier.

206: If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is greater than the preset signal-to-noise ratio, the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier are not subjected to frequency domain filtering, and The channel estimate of the data carrier is determined as the channel estimate of the final data carrier.

Among them, the preset signal to noise ratio can be 33dB.

Since the initial channel estimation value that was not filtered during the simulation test is better than the performance of the filtered initial channel estimation value, the initial channel estimation value is not filtered in this case.

Example 3

Embodiments of the present invention provide a device for channel estimation, as shown in FIG. 8. The device includes:

An initial estimation module 801, configured to perform initial channel estimation on a data carrier in the received signal;

The cancellation processing module 802 is configured to obtain a channel estimation value of the data carrier after performing gamma factor elimination processing;

The padding processing module 803 is configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier, and obtain channel estimation values of the null carrier and the pilot carrier.

a first determining module 804, configured to acquire a modulation mode of the received signal, and determine a tap coefficient of the filter according to the modulation mode;

The filtering module 805 is configured to perform frequency domain filtering on the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; the time domain characteristic of the filter includes the diversity cyclic shift CSD Affected channel multipath information;

The adding processing module 806 is configured to perform gamma factor adding processing on the channel estimation value of the filtered data carrier to obtain a channel estimation value of the final data carrier.

The padding processing module 803 includes:

a first determining unit, configured to determine a communication standard of the received signal according to the preamble sequence in the received signal;

a second determining unit, configured to determine a location of the null carrier and the pilot carrier according to the orthogonal frequency division multiplexing OFDM symbol in the received signal if the communication standard of the received signal is 802.11ac;

And a padding processing unit, configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier.

Among them, the filling processing unit includes:

a first padding processing subunit, configured to determine a channel estimation value of a data carrier closest to a location of the null carrier and the pilot carrier as a null carrier and a pilot carrier if the location of the null carrier and the pilot carrier is located in the guard band Channel estimation value;

a second padding processing sub-unit, configured to determine, by linear interpolation, according to channel estimation values of data carriers located at positions before and after the null carrier and the pilot carrier, if the positions of the null carrier and the pilot carrier are located in the non-protection band Channel estimates for the carrier and pilot carriers.

The first determining module 804 includes:

The first selecting unit is configured to select a preset first tap coefficient as the tap coefficient of the filter if the modulation mode is low-order modulation.

The first determining module 804 includes:

The second selecting unit is configured to select a preset second tap coefficient as the tap coefficient of the filter if the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is less than or equal to the preset signal-to-noise ratio.

Wherein, the device further comprises:

The second determining module 807 is configured to: if the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is greater than the preset signal-to-noise ratio, do not perform channel estimation on the data carrier and channel estimation values of the null carrier and the pilot carrier. The domain filtering process determines the channel estimate of the data carrier as the channel estimate of the final data carrier.

Example 4

The embodiment of the invention provides a transceiver device, see FIG.

The transceiver device includes: a processor 901 and a transceiver 902,

The processor 901 is configured to perform initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier; and according to the channel estimation value of the data carrier, the null carrier and the pilot carrier in the received signal After the padding process, the channel estimation values of the null carrier and the pilot carrier are obtained; the modulation mode of the received signal is obtained, and the tap coefficients of the filter are determined according to the modulation mode; and the channel estimation value of the filtered data carrier is added after the gamma factor is added. Obtaining a channel estimate of the final data carrier;

The filter 902 is configured to perform frequency domain filtering on the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; the time domain characteristic of the filter includes the diversity cyclic shift CSD Affected channel multipath information.

The processor 901 is further configured to determine, according to a preamble sequence in the received signal, a communication standard of the received signal; if the communication standard of the received signal is 802.11ac, determine the null carrier according to the orthogonal frequency division multiplexing OFDM symbol in the received signal. And the location of the pilot carrier; according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier, the null carrier and the pilot carrier in the received signal are padded to obtain channel estimation values of the null carrier and the pilot carrier.

The processor 901 is further configured to determine, if the location of the null carrier and the pilot carrier is located in the guard band, the channel estimation value of the data carrier closest to the location of the null carrier and the pilot carrier as the channel of the null carrier and the pilot carrier. Estimated value; if the location of the null carrier and the pilot carrier is in the non-protection band, the null carrier and the pilot carrier are determined by linear interpolation according to the channel estimation values of the data carriers located at the positions of the null carrier and the pilot carrier Channel estimate.

The processor 901 may also select a preset first tap coefficient as the tap coefficient of the filter if the modulation mode is low-order modulation.

The processor 901 is further configured to: if the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is less than or equal to the preset signal-to-noise ratio, select a preset second tap coefficient as the tap coefficient of the filter.

The processor 901 can also perform frequency domain filtering on the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier if the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is greater than the preset signal-to-noise ratio. Processing and determining the channel estimate of the data carrier as the channel estimate of the final data carrier.

In the embodiment of the present invention, the channel estimation value of the data carrier is obtained by performing initial channel estimation and gamma factor elimination processing on the data carrier in the received signal, and performing null carrier and pilot carrier in the received signal according to the channel estimation value of the data carrier. After filling, the channel estimation values of the null carrier and the pilot carrier are obtained, and the tap coefficients of the filter are selected according to the modulation mode of the received signal, and the channel estimation value of the data carrier and the channel estimation values of the null carrier and the pilot carrier are performed in the frequency domain. Filtering, and performing gamma factor addition processing on the channel estimation value of the filtered data carrier to obtain a channel estimation value of the final data carrier. On the basis of the LS algorithm, only the frequency domain filtering is used to reduce the channel error of the channel estimation value of the data carrier, which reduces the complexity and delay of the operation, and improves the efficiency of channel estimation.

A person skilled in the art can understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be executed by a program to instruct related hardware, and the program may be stored in a computer readable storage medium. The storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

A method for channel estimation, characterized in that the method comprises:

Performing initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier;

And performing a padding process on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier;

Obtaining a modulation mode of the received signal, and determining a tap coefficient of the filter according to the modulation mode;

Performing frequency domain filtering on the channel estimate of the data carrier and the channel estimate of the null carrier and the pilot carrier in the filter according to the determined tap coefficient; time domain characteristics of the filter including diversity Channel multipath information affected by cyclic shift CSD;

After the gamma factor adding process is performed on the filtered channel estimation value of the data carrier, a channel estimation value of the final data carrier is obtained.
The method according to claim 1, wherein the null carrier and the pilot carrier in the received signal are padded according to a channel estimation value of the data carrier, and the null carrier and pilot are obtained. The channel estimation value of the carrier, including:

Determining a communication standard of the received signal according to a preamble sequence in the received signal;

If the communication standard of the received signal is 802.11ac, determining the locations of the null carrier and the pilot carrier according to the orthogonal frequency division multiplexing OFDM symbols in the received signal;

And performing a padding process on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain channel estimation values of the null carrier and the pilot carrier. .
The method according to claim 2, wherein said performing null carrier and pilot carrier in said received signal according to said null carrier and a location of a pilot carrier and a channel estimation value of said data carrier The padding process obtains channel estimates of the null carrier and the pilot carrier, including:

If the location of the null carrier and the pilot carrier is located in the guard band, determining a channel estimate of the data carrier closest to the location of the null carrier and the pilot carrier as the channel estimate of the null carrier and the pilot carrier ;

If the location of the null carrier and the pilot carrier is in the non-protection band, determining the null carrier and the channel by linear interpolation according to channel estimation values of the data carriers located at positions before and after the null carrier and the pilot carrier The channel estimate of the frequency carrier.
The method according to claim 1, wherein the selecting the tap coefficients of the filter according to the modulation mode comprises:

If the modulation mode is low-order modulation, a preset first tap coefficient is selected as the tap coefficient of the filter.
The method according to claim 1, wherein the selecting the tap coefficients of the filter according to the modulation mode comprises:

If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio, a preset second tap coefficient is selected as the tap coefficient of the filter.
The method according to claim 1, wherein the selecting the tap coefficients in the filter according to the modulation mode and the signal to noise ratio further comprises:

If the modulation mode is high-order modulation and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, the channel estimation value of the data carrier and the channel estimation value of the null carrier and the pilot carrier are not used. The domain filtering process determines the channel estimate of the data carrier as the channel estimate of the final data carrier.
A device for channel estimation, characterized in that the device comprises:

An initial estimation module, configured to perform initial channel estimation on the data carrier in the received signal;

An elimination processing module, configured to obtain a channel estimation value of the data carrier after performing gamma factor elimination processing;

a padding processing module, configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the channel estimation value of the data carrier, to obtain channel estimation values of the null carrier and the pilot carrier;

a first determining module, configured to acquire a modulation mode of the received signal, and determine a tap coefficient of the filter according to the modulation mode;

a filtering module, configured to: in the filter, the data carrier according to the determined tap coefficient The channel estimation value and the channel estimate of the null carrier and the pilot carrier are subjected to frequency domain filtering; the time domain characteristic of the filter includes channel multipath information affected by the diversity cyclic shift CSD;

And adding a processing module, configured to perform a gamma factor adding process on the filtered channel estimation value of the data carrier, to obtain a channel estimation value of the final data carrier.
The device according to claim 7, wherein the padding processing module comprises:

a first determining unit, configured to determine a communication standard of the received signal according to a preamble sequence in the received signal;

a second determining unit, configured to determine, according to the orthogonal frequency division multiplexing OFDM symbol in the received signal, a location of the null carrier and a pilot carrier if the communication standard of the received signal is 802.11ac;

a padding processing unit, configured to perform padding processing on the null carrier and the pilot carrier in the received signal according to the location of the null carrier and the pilot carrier and the channel estimation value of the data carrier to obtain the null carrier and the guide The channel estimate of the frequency carrier.
The device according to claim 8, wherein the padding processing unit comprises:

a first padding processing subunit, configured to determine, if the location of the null carrier and the pilot carrier is in a guard band, a channel estimation value of a data carrier that is closest to a location of the null carrier and the pilot carrier as the null Channel estimation values for carrier and pilot carriers;

a second padding processing sub-unit, configured to linearly interpolate channel estimation values of data carriers located at positions before and after the null carrier and the pilot carrier if the locations of the null carrier and the pilot carrier are located in the unprotected band In a manner, a channel estimate of the null carrier and the pilot carrier is determined.
The device according to claim 7, wherein the first determining module comprises:

And a first selecting unit, configured to select a preset first tap coefficient as the tap coefficient of the filter if the modulation mode is low-order modulation.
The device according to claim 7, wherein the first determining module comprises:

a second selecting unit, configured to select a preset second tap coefficient as the tap of the filter if the modulation mode is high-order modulation and a signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio coefficient.
The device according to claim 7, wherein the device further comprises:

a second determining module, configured to: if the modulation mode is high-order modulation, and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, do not estimate channel values of the data carrier, and the null carrier and pilot The channel estimation value of the carrier performs frequency domain filtering processing, and determines a channel estimation value of the data carrier as a channel estimation value of the final data carrier.
A transceiver device, characterized in that the transceiver device comprises: a processor and a transceiver,

The processor is configured to perform initial channel estimation and gamma factor elimination processing on the data carrier in the received signal to obtain a channel estimation value of the data carrier; and according to the channel estimation value of the data carrier, in the received signal After the null carrier and the pilot carrier are padded, the channel estimation values of the null carrier and the pilot carrier are obtained; the modulation mode of the received signal is obtained, and the tap coefficients of the filter are determined according to the modulation mode; After the channel estimation value of the data carrier is subjected to gamma factor addition processing, a channel estimation value of the final data carrier is obtained;

The transceiver is configured to perform frequency domain filtering on a channel estimation value of the data carrier and a channel estimation value of the null carrier and a pilot carrier in the filter according to the determined tap coefficient; The time domain characteristics of the device include channel multipath information affected by the diversity cyclic shift CSD.
The transceiver device according to claim 13, wherein

The processor is further configured to determine a communication standard of the received signal according to a preamble sequence in the received signal; if the communication standard of the received signal is 802.11ac, according to an orthogonal frequency in the received signal Demultiplexing OFDM symbols determining locations of the null carriers and pilot carriers; null carriers and pilots in the received signal based on locations of the null carriers and pilot carriers and channel estimates of the data carriers The carrier performs padding processing to obtain channel estimates of the null carrier and the pilot carrier.
The transceiver device according to claim 14, wherein

The processor is further configured to determine, if the location of the null carrier and the pilot carrier is in a guard band, a channel estimation value of a data carrier that is closest to a location of the null carrier and the pilot carrier as the null carrier And a channel estimation value of the pilot carrier; if the location of the null carrier and the pilot carrier is in the non-protection band, linearly interpolating according to channel estimation values of the data carriers located at positions before and after the null carrier and the pilot carrier In a manner, a channel estimate of the null carrier and the pilot carrier is determined.
The transceiver device according to claim 13, wherein

The processor is further configured to: if the modulation mode is low-order modulation, select a preset first tap coefficient as a tap coefficient of the filter.
The transceiver device according to claim 13, wherein

The processor is further configured to: if the modulation mode is high-order modulation and a signal-to-noise ratio of the received signal is less than or equal to a preset signal-to-noise ratio, select a preset second tap coefficient as the filter Tap coefficient.
The transceiver device according to claim 13, wherein

The processor is further configured to: if the modulation mode is high-order modulation, and the signal-to-noise ratio of the received signal is greater than a preset signal-to-noise ratio, the channel estimation value of the data carrier and the null carrier and the guide are not used. The channel estimate of the frequency carrier is subjected to frequency domain filtering processing, and the channel estimation value of the data carrier is determined as the channel estimation value of the final data carrier.