CN101895489B - Filtering method and device for channel estimation - Google Patents

Abstract

The present invention provides a filtering method and filtering device for channel estimation. The method includes: respectively determining a filtering threshold for each code combination transmission channel, and performing channel estimation on each code combination transmission channel according to the respective filtering thresholds of the code combination transmission channels Filtering, retaining the channel estimation taps whose energy value or amplitude value is greater than the filtering threshold in the transmission channel of each code combination. The filtering device above includes a filtering threshold determination module and a channel estimation filtering module. The invention can improve the demodulation performance of the low-power code combination transmission channel service signal under the premise of ensuring the demodulation performance of the high-power code combination transmission channel service signal.

Description

A filtering method and filtering device for channel estimation

technical field

The present invention relates to the technical field of wireless communication, in particular to a filtering method and a filtering device for terminal channel estimation in a Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system.

Background technique

The TD-SCDMA system uses joint detection to demodulate user data, and the premise of the application of the joint detection algorithm is that the channel impulse response of each user can be accurately estimated. The channel estimation of the TD-SCDMA system adopts the classic Steiner estimator. Using this estimator is a low-cost channel estimation method. The Midamble code of each user is constructed according to a certain rule through a basic Midamble code, so that the The matrix of the Midamble code system has circular correlation, so the channel estimation value can be calculated by FFT (Fast Fourier Transform) and IFFT (Inverse Fast Fourier Transform). Firstly, the original channel estimate is estimated, and then the threshold is set according to the peak energy peak value of the channel estimation tap of the received Midamble code data, and the noise is removed through the threshold to obtain the final channel estimate value.

When multiple services are parallel in the TD-SCDMA system, different services are mapped to different Coded Composite Transport Channels (CCTrCH for short), and each CCTrCH corresponds to one or more physical channels, and is sent in one time slot. Different CCTrCHs perform power control respectively. In the case of a large power difference between CCTRCHs, the threshold is set according to the peak energy of each tap. The energy of each tap of a CCTRCH with a smaller power may be below the threshold, and the channel estimation value is all zero, resulting in a smaller power. The CCTRCH cannot be demodulated correctly, thus affecting the signal demodulation quality. As shown in Figure 1, CCTRCH 1 has 1 channel window, and the signal energy is relatively weak. CCTRCH 2 has 5 channel windows, and the signal energy is strong. If the filter threshold Th is set according to the energy peak value Power2 of each tap, then all taps of CCTRCH 1 are Under the threshold value, the channel estimation is all zero, and CCTRCH 1 cannot be demodulated correctly.

Contents of the invention

The applicant has conducted research on the defects of the prior art, corresponding to the prior art, if the threshold is lowered in the way of determining the threshold in the prior art, as shown in Figure 1, the CCTRCH1 can be detected , but the reduction of the threshold will introduce noise, thereby affecting the demodulation performance of the high-power CCTRCH service signal.

The technical problem to be solved by the present invention is to provide a filtering method for channel estimation, which improves the demodulation performance of low-power CCTRCH service signals on the premise of ensuring the demodulation performance of high-power CCTRCH service signals.

In order to solve the above-mentioned technical problems, the present invention provides a filtering method for channel estimation, including: respectively determining a filtering threshold for each code combination transmission channel, and performing channeling on each code combination transmission channel according to the respective filtering thresholds of the code combination transmission channel Estimation filtering, retaining the channel estimation taps whose energy value or amplitude value is greater than the filtering threshold in the transmission channel of each code combination.

Further, the above method also has the following characteristics:

For a code combination transmission channel, determine the filtering threshold of the code combination transmission channel according to the energy value of the channel estimation tap in the code combination transmission channel; reserve the channel estimation taps whose energy value is greater than the filtering threshold in the code combination transmission channel, filter Remove channel estimation taps whose energy value is less than the filtering threshold; or, determine the filtering threshold of the code combination transmission channel according to the amplitude value of the channel estimation tap in the code combination transmission channel; retain the code combination transmission channel with an amplitude value greater than the specified value The channel estimation taps of the filtering threshold are filtered out, and the channel estimation taps whose amplitude values are smaller than the filtering threshold are filtered out.

Further, the above method also has the following characteristics:

When determining the filter threshold according to the energy value of the channel estimation tap in the code combination transmission channel, the filter threshold of the code combination transmission channel is: the product of the energy value of the channel estimation tap with the largest energy in the code combination transmission channel and the filter coefficient λ1, This filter coefficient λ1 is a real number greater than 0 and less than 1; when determining the filter threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, the filter threshold of the code combination transmission channel is: the maximum amplitude in this code combination transmission channel The product of the amplitude value of the channel estimation tap and the filter coefficient U1, the filter coefficient U1 is a real number greater than 0 and less than 1.

Further, the above method also has the following characteristics:

Perform noise removal processing on the filtered channel estimate, specifically including: determining the noise threshold of each code combination transmission channel according to the energy value of the channel estimation tap in each code combination transmission channel; retaining the energy value of each code combination transmission channel greater than the noise threshold Channel estimation taps, filtering out channel estimation taps whose energy value is less than the noise threshold; or, determining the noise threshold of each code combination transmission channel according to the amplitude value of the channel estimation tap in the code combination transmission channel; retaining the amplitude in each code combination transmission channel Channel estimation taps with values greater than the noise threshold, and channel estimation taps with amplitude values smaller than the noise threshold are filtered out.

Further, the above method also has the following characteristics:

When the noise threshold is determined according to the energy value of the channel estimation taps in the code combination transmission channel, for a code combination transmission channel, the product of the energy mean value of the channel estimation taps smaller than the filtering threshold of the code combination transmission channel and the noise coefficient λ2 is used as the noise threshold , λ2 is a real number greater than 1; when determining the noise threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, for a code combination transmission channel, the amplitude mean value of the channel estimation taps smaller than the filtering threshold of the code combination transmission channel and The product of the noise coefficient λ3 is used as the noise threshold, and λ3 is a real number greater than 1.

In order to solve the above technical problems, the present invention also provides a filter device for channel estimation, including a filter threshold determination module and a channel estimation filter module, the filter threshold determination module is used to determine the filter threshold for each code combination transmission channel respectively The channel estimation filtering module is used to perform channel estimation filtering on each code combination transmission channel according to the respective filter thresholds of the code combination transmission channel, and retain channel estimation taps whose energy values or amplitude values in each code combination transmission channel are greater than the filter threshold .

Further, the above filter device also has the following characteristics:

The filtering threshold determination module is also used to determine the filtering threshold of the code combination transmission channel according to the energy value or amplitude value of the channel estimation tap in the code combination transmission channel; When the filtering threshold determination module determines the filtering threshold according to the energy value of the channel estimation tap, retain the channel estimation taps whose energy value is greater than the filtering threshold in the code combination transmission channel, and filter out the channel estimation taps whose energy value is smaller than the filtering threshold; It is also used to reserve the channel estimation taps whose amplitude values are greater than the filtering threshold in the code combination transmission channel when the filtering threshold determination module determines the filtering threshold according to the amplitude value of the channel estimation tap, and filter out the channel estimation taps whose amplitude value is smaller than the filtering threshold The channel estimation taps of .

Further, the above filter device also has the following characteristics:

The filtering threshold determination module is also used to determine the filtering threshold according to the energy value of the channel estimation tap in the code combination transmission channel, the product of the energy value of the channel estimation tap with the largest energy in the code combination transmission channel and the filter coefficient λ1 As the filter threshold of the code combination transmission channel, the filter coefficient λ1 is a real number greater than 0 and less than 1; it is also used to determine the filter threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel. The product of the amplitude value of the channel estimation tap with the largest amplitude and the filter coefficient U1 is used as the filter threshold of the code combination transmission channel, and the filter coefficient U1 is a real number greater than 0 and less than 1.

Further, the above filter device also has the following characteristics:

The device also includes a noise threshold determination module and a noise removal module; the input end of the noise removal module is connected to the output end of the channel estimation filter module; the noise threshold determination module is used to combine the channels in the transmission channel according to the code Estimate the energy value or amplitude value of the tap to determine the noise threshold of the code combination transmission channel; the noise removal module is used to filter the channel estimation when the noise threshold determination module determines the noise threshold according to the energy value of the channel estimation tap. The channel estimation taps output by the module are processed, and the channel estimation taps whose energy value is greater than the noise threshold of each code combination transmission channel in each code combination transmission channel are reserved, and the channel estimation taps whose energy value is smaller than the noise threshold are filtered out; it is also used in the described When the noise threshold determining module determines the noise threshold according to the amplitude value of the channel estimation tap, the channel estimation tap output by the channel estimation filtering module is processed, and the amplitude values in each code combination transmission channel are kept greater than the noise threshold of each code combination transmission channel Channel estimation taps, which filter out channel estimation taps whose amplitude values are smaller than the noise threshold.

Further, the above filter device also has the following characteristics:

The noise threshold determination module is also used to determine the noise threshold according to the energy value of the channel estimation taps in the code combination transmission channel, and the energy mean value of the channel estimation taps smaller than the filtering threshold of the code combination transmission channel in the code combination transmission channel and The product of the noise factor λ2 is used as the noise threshold of this combination transmission channel, and λ2 is a real number greater than 1; it is also used to determine the noise threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, and the code combination transmission channel is smaller than this code. The product of the channel estimation tap amplitude mean of the filtering threshold of the combined transmission channel and the noise coefficient λ3 is used as the noise threshold of the combined transmission channel, and λ3 is a real number greater than 1.

The method of the invention improves the demodulation performance of the low-power CCTRCH service signal under the premise of ensuring the demodulation performance of the high-power CCTRCH service signal.

Description of drawings

FIG. 1 is a schematic diagram of determining a filtering threshold based on energy peak values of all taps in the prior art;

FIG. 2 is a flow chart of a method for performing filtering by channel estimation in an embodiment;

FIG. 3 is a schematic diagram of a filtering method for channel estimation in Embodiment 1;

FIG. 4 is a schematic diagram of a specific filtering process in Embodiment 1;

Fig. 5 is the schematic diagram of filtering result in the specific embodiment one;

Fig. 6 is a schematic diagram of the noise removal process in the second embodiment.

Detailed ways

In this embodiment, the filter device for channel estimation includes a filter threshold determination module, a channel estimation filter module, a noise threshold determination module and a noise removal module, and the input end of the noise removal module is connected to the output end of the channel estimation filter module.

The filter threshold determination module is used to determine the filter threshold for each code combination transmission channel; for a code combination transmission channel, determine the value of the code combination transmission channel according to the energy value or amplitude value of the channel estimation tap in the code combination transmission channel Filter threshold; when determining the filter threshold according to the energy value of the channel estimation tap in the code combination transmission channel, the product of the energy value of the channel estimation tap with the largest energy in the code combination transmission channel and the filter coefficient λ1 is used as the filter of the code combination transmission channel Threshold, λ1 is a real number greater than 0 and less than 1; when determining the filtering threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, the amplitude value of the channel estimation tap with the largest amplitude in the code combination transmission channel and the value of the filter coefficient U1 The product is used as the filtering threshold of the combined transmission channel of this code, and U1 is a real number greater than 0 and less than 1.

Channel estimation filtering module, for when the filtering threshold determination module determines the filtering threshold according to the energy value of the channel estimation tap, retain the channel estimation taps whose energy value is greater than the filtering threshold in the code combination transmission channel, and filter out the channel estimation taps whose energy value is less than The channel estimation tap of the filtering threshold; when the filtering threshold determination module determines the filtering threshold according to the amplitude value of the channel estimation tap, the channel estimation tap whose amplitude value is greater than the filtering threshold in the code combination transmission channel is reserved, Channel estimation taps whose amplitude values are smaller than the filtering threshold are filtered out.

The noise threshold determination module is used to determine the noise threshold of the code combination transmission channel according to the energy value or amplitude value of the channel estimation tap in the code combination transmission channel; specifically: determine the noise according to the energy value of the channel estimation tap in the code combination transmission channel When thresholding, the product of the energy mean of the channel estimation taps less than the filtering threshold of the code combination transmission channel in the code combination transmission channel and the noise coefficient λ2 is used as the noise threshold of the combination transmission channel, and λ2 is a real number greater than 1; according to the code combination When the amplitude value of the channel estimation tap in the transmission channel determines the noise threshold, the product of the amplitude mean value of the channel estimation tap less than the filtering threshold of the code combination transmission channel in the code combination transmission channel and the noise coefficient λ3 is used as the noise threshold of the combination transmission channel , λ3 is a real number greater than 1.

The noise removal module is used to process the channel estimation taps output by the channel estimation filtering module when the noise threshold determination module determines the noise threshold according to the energy value of the channel estimation taps, and retain the energy values in each code combination transmission channel greater than Each code combines the channel estimation taps of the noise threshold of the transmission channel, and filters out the channel estimation taps whose energy value is smaller than the noise threshold; it is also used to determine the noise threshold according to the amplitude value of the channel estimation tap in the noise threshold determination module. The channel estimation taps output by the channel estimation filtering module are processed, and the channel estimation taps whose amplitude value is greater than the noise threshold of each code combination transmission channel in each code combination transmission channel are reserved, and the channel estimation taps whose amplitude value is smaller than the noise threshold are filtered out.

As shown in FIG. 2, in this embodiment, the filtering method for channel estimation includes:

Step 201, determining a filtering threshold for each code combination transmission channel in the initial channel estimation;

For a code combination transmission channel, determine the filtering threshold of the code combination transmission channel according to the energy peak value of the tap with the largest energy value among all channel estimation taps included in it;

Step 202 , performing channel estimation filtering on each combined transmission channel of codes according to the respective filtering thresholds corresponding to the combined transmission channel; the process ends.

For a code combination transmission channel, the channel estimation taps larger than the filtering threshold are reserved, and the channel estimation taps smaller than the filtering threshold are set to 0 to obtain the filtered channel estimation.

The present invention is further described with two specific examples below:

Specific Embodiment 1 As shown in FIG. 3 , the filtering method for channel estimation includes:

Step 301, receive the Midamble code, and calculate the frequency domain value (basic_midamble_fft) of the Midamble code (received_midamble) that receives, and calculate the frequency domain value (basic_midamble_fft) of the basic Midamble code (basic_midamble); The specific calculation method is as follows:

basic_midamble_fft = fft(basic_midamble);

received_midamble_fft = fft(received_midamble);

Step 302, perform initial channel estimation, divide the two frequency domain values obtained in step 301, and then perform IFFT transformation to obtain a time domain value, that is, a channel estimation value channel;

channel=ifft(received_midamble_fft ·/basic_midamble_fft)

Among them, / indicates the division of the corresponding numbers of two arrays;

Step 303, filter the channel estimate after step 302, specifically including the content shown in Figure 4:

Step 401, calculating the energy of all channel estimation taps;

The tap energy of each channel estimation is: power=real(channel).^2+imag(channel).^2;

Step 402, determining the energy peak value of the tap with the largest energy value among all channel estimation taps included in each CCTRCH;

Step 403, calculating the filtering threshold corresponding to each CCTRCH;

For a CCTRCH, the energy peak value of the tap with the largest energy value among all channel estimation taps included in the CCTRCH is multiplied by a filter coefficient as the filter threshold Th1 of the CCTRCH;

Th1=max(power)*λ1

Wherein, the filter coefficient λ1 is a real number, and its value range is 0<λ1<1. The optimal value of the filter coefficient λ1 can also be obtained through the empirical value of the system test.

Step 404, filter the channel estimation of CCTRCH according to the filtering threshold of each CCTRCH;

Compare the energy peak values of all taps in each CCTRCH with the filtering threshold Th1, reserve the channel estimation taps larger than the filtering threshold Th1 as effective taps, set the channel estimation taps smaller than the filtering threshold Th1 to 0, and obtain the filtered channel estimation .

As shown in Figure 5, in the specific embodiment one, P=128 is the basic Midamble code length, and K=8 is the number of channel windows, is the channel estimation window length. As shown in the figure, CCTRCH 1 has one channel window, and CCTRCH 2 has 5 channel windows (that is, the second to sixth channel windows). Through the method of the first embodiment, the filtering threshold determined for CCTRCH 1 is Th1, which is The filtering threshold determined by CCTRCH 2 is Th2, the filtering is performed in CCTRCH 1 according to Th1, and the filtering is performed in CCTRCH 2 according to Th2, so that low-power CCTRCH 1 can also be effectively demodulated.

In the above embodiment, when filtering the channel estimation in step 302, the filtering threshold used for each code combination transmission channel is the product of the energy value of the channel estimation tap with the largest energy in the code combination transmission channel and the filter coefficient λ1. In addition to the above methods, other methods can be used for the selection of the filtering threshold: the energy values of the channel estimation taps in the code combination transmission channel are sorted from large to small, and the mean value and filter coefficient of the last X1 (X1 is an integer greater than 1) energy values The product of M1 (M1 is a real number greater than 1).

In addition, in addition to the above method of using the energy parameter as the filtering threshold, the amplitude value can also be used. For example, the filtering threshold adopted for each code combination transmission channel is the amplitude value of the channel estimation tap with the largest amplitude value in the code combination transmission channel. The product of the coefficient U1 (U1 is a real number greater than 0 and less than 1); or, the average value of the last Y1 (Y1 is an integer greater than 1) amplitude values in the sequence of the amplitude values of the channel estimation taps in the code combination transmission channel from large to small and the product of the filter coefficient N1 (N1 is a real number greater than 1), when filtering, retain the channel estimation taps whose amplitude value is greater than the filtering threshold calculated based on the amplitude value in the code combination transmission channel, and filter out the amplitude value smaller than the filtering threshold The channel estimation taps of .

Specific embodiment two:

The scheme of specific embodiment 2 is on the basis of specific embodiment 1, after specific embodiment 1 completes filter processing, then carry out noise removal, the process of noise removal is:

Step 601, calculating the mean value of the multipath energy of the taps smaller than the filtering threshold in each CCTRCH;

Step 602, use the product of the energy mean value and the noise coefficient λ2 as the noise threshold Th2;

Th2=mean(power<Th1)*λ2

Among them, λ2>1 is the noise threshold coefficient; the optimal value of λ2 can be a real number between 3 and 8, and can also be obtained through the empirical value of the system test.

Step 603, compare the energy peak value of each tap in the filtered channel estimation with the noise threshold Th2, the taps with the energy peak value greater than the noise threshold are valid taps, and keep them; the taps with the energy peak values smaller than the noise threshold are regarded as invalid taps, set to 0. All valid taps that are finally retained constitute the final channel estimate.

Compared with the second embodiment, the specific embodiment 1 further removes the noise to obtain more accurate channel estimation.

In the above-mentioned specific embodiment two, the channel estimation taps less than the filtering threshold of the code combination transmission channel in each code combination transmission channel take the energy mean value, and the product of the energy mean value and the noise coefficient λ2 is used as the noise threshold, and λ2 is greater than 1 real number.

In addition, in addition to the above method of using the energy parameter as the noise threshold, the amplitude value can also be used, and the noise threshold used by each code combination transmission channel can be the following value:

The product of the amplitude mean value of each channel estimation tap smaller than the filtering threshold in the code combination transmission channel and the noise coefficient λ3, where λ3 is a coefficient greater than 1. When performing noise removal, the channel estimation taps whose amplitude values are larger than the noise threshold calculated based on the amplitude mean value in the code combination transmission channel are reserved, and the channel estimation taps whose amplitude values are smaller than the noise threshold are filtered out.

In the above method, the filter thresholds are respectively determined for each code combination transmission channel according to the peak value of the signal, and after filtering the channel estimation taps of each code combination transmission channel, the noise threshold is determined for each code combination transmission channel according to the noise signal, and further removed Noise, under the premise of ensuring the demodulation performance of high-power CCTRCH service signals, improve the demodulation performance of low-power CCTRCH service signals

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention. All changes and deformations should belong to the protection scope of the appended claims of the present invention.

Claims (8)

1. A method of filtering channel estimates, comprising:

determining a filtering threshold for each code combination transmission channel, performing channel estimation filtering on each code combination transmission channel according to the respective filtering threshold of the code combination transmission channel, and reserving a channel estimation tap of which the energy value or amplitude value is greater than the filtering threshold in each code combination transmission channel; wherein,

for a code combination transmission channel, determining a filtering threshold of the code combination transmission channel according to an energy value of a channel estimation tap in the code combination transmission channel; reserving a channel estimation tap with the energy value larger than the filtering threshold in the code combined transmission channel, and filtering the channel estimation tap with the energy value smaller than the filtering threshold; or,

determining a filtering threshold of the code combination transmission channel according to the amplitude value of a channel estimation tap in the code combination transmission channel; and reserving the channel estimation taps with the amplitude values larger than the filtering threshold in the code combination transmission channel, and filtering the channel estimation taps with the amplitude values smaller than the filtering threshold.

2. The method of claim 1,

when determining a filtering threshold according to an energy value of a channel estimation tap in a code combination transmission channel, the filtering threshold of the code combination transmission channel is as follows: the product of the energy value of the channel estimation tap with the maximum energy in the code combination transmission channel and a filter coefficient lambda 1, wherein the filter coefficient lambda 1 is a real number which is larger than 0 and smaller than 1;

when the filtering threshold is determined according to the amplitude value of the channel estimation tap in the code combination transmission channel, the filtering threshold of the code combination transmission channel is as follows: the code combines the product of the amplitude value of the channel estimation tap with the largest amplitude in the transmission channel and the filter coefficient U1, the filter coefficient U1 is a real number greater than 0 and less than 1.

3. The method of claim 1 or 2,

performing noise removal processing on the filtered channel estimation, specifically including: determining the noise threshold of each code combination transmission channel according to the energy value of a channel estimation tap in each code combination transmission channel; reserving channel estimation taps with energy values larger than a noise threshold in each code combination transmission channel, and filtering the channel estimation taps with energy values smaller than the noise threshold; or,

determining the noise threshold of each code combination transmission channel according to the amplitude value of the channel estimation tap in the code combination transmission channel; and reserving channel estimation taps with amplitude values larger than the noise threshold in each code combination transmission channel, and filtering the channel estimation taps with the amplitude values smaller than the noise threshold.

4. The method of claim 3,

when determining a noise threshold according to the energy value of a channel estimation tap in a code combination transmission channel, regarding a code combination transmission channel, taking the product of the energy mean value of the channel estimation tap smaller than the filtering threshold of the code combination transmission channel and a noise coefficient lambda 2 as the noise threshold, wherein lambda 2 is a real number larger than 1;

when the noise threshold is determined according to the amplitude value of the channel estimation tap in the code combination transmission channel, for a code combination transmission channel, the product of the average value of the amplitudes of the channel estimation taps which are smaller than the filtering threshold of the code combination transmission channel and the noise coefficient lambda 3 is used as the noise threshold, and lambda 3 is a real number which is larger than 1.

5. A filtering device for channel estimation comprises a filtering threshold determining module and a channel estimation filtering module,

the filtering threshold determining module is used for determining a filtering threshold for each code combination transmission channel;

the channel estimation filtering module is used for respectively carrying out channel estimation filtering on each code combination transmission channel according to the respective filtering threshold of the code combination transmission channel, and reserving a channel estimation tap of which the energy value or amplitude value is greater than the filtering threshold in each code combination transmission channel; wherein,

the filtering threshold determining module is further configured to determine a filtering threshold of the code combination transmission channel according to an energy value or an amplitude value of a channel estimation tap in the code combination transmission channel;

the channel estimation filtering module is further configured to, when the filtering threshold determining module determines the filtering threshold according to the energy value of the channel estimation tap, reserve the channel estimation tap of which the energy value in the code combination transmission channel is greater than the filtering threshold, and filter the channel estimation tap of which the energy value is less than the filtering threshold; and the filtering threshold determining module is further configured to, when determining the filtering threshold according to the amplitude value of the channel estimation tap, reserve the channel estimation tap of which the amplitude value is greater than the filtering threshold in the code combination transmission channel, and filter the channel estimation tap of which the amplitude value is less than the filtering threshold.

6. Filter device as claimed in claim 5,

the filtering threshold determining module is further configured to, when determining the filtering threshold according to the energy value of the channel estimation tap in the code combination transmission channel, take a product of the energy value of the channel estimation tap with the largest energy in the code combination transmission channel and a filtering coefficient λ 1 as the filtering threshold of the code combination transmission channel, where the filtering coefficient λ 1 is a real number greater than 0 and smaller than 1; and the filter module is further configured to, when determining the filter threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, take a product of the amplitude value of the channel estimation tap with the largest amplitude in the code combination transmission channel and a filter coefficient U1 as the filter threshold of the code combination transmission channel, where the filter coefficient U1 is a real number greater than 0 and smaller than 1.

7. The filtering apparatus of claim 5 or 6, wherein the apparatus further comprises a noise threshold determination module and a noise removal module; the input end of the noise removal module is connected with the output end of the channel estimation filtering module;

the noise threshold determination module is used for determining the noise threshold of the code combination transmission channel according to the energy value or amplitude value of the channel estimation tap in the code combination transmission channel;

a noise removing module, configured to process the channel estimation taps output by the channel estimation filtering module when the noise threshold determining module determines the noise threshold according to the energy values of the channel estimation taps, reserve channel estimation taps in each code combination transmission channel whose energy values are greater than the noise threshold of each code combination transmission channel, and filter channel estimation taps whose energy values are less than the noise threshold; and the noise threshold determining module is further configured to, when determining the noise threshold according to the amplitude value of the channel estimation tap, process the channel estimation tap output by the channel estimation filtering module, reserve the channel estimation tap of which the amplitude value is greater than the noise threshold of each code combination transmission channel in each code combination transmission channel, and filter the channel estimation tap of which the amplitude value is less than the noise threshold.

8. Filter device as claimed in claim 7,

the noise threshold determining module is further configured to determine a noise threshold according to an energy value of a channel estimation tap in the code combination transmission channel, and use a product of an energy average value of the channel estimation tap in the code combination transmission channel, which is smaller than a filtering threshold of the code combination transmission channel, and a noise coefficient λ 2 as the noise threshold of the combination transmission channel, where λ 2 is a real number greater than 1; and when determining the noise threshold according to the amplitude value of the channel estimation tap in the code combination transmission channel, taking the product of the average amplitude value of the channel estimation tap in the code combination transmission channel, which is smaller than the filtering threshold of the code combination transmission channel, and a noise coefficient λ 3 as the noise threshold of the code combination transmission channel, where λ 3 is a real number greater than 1.

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