WO2011088684A1

WO2011088684A1 - Terminal channel estimation method and system for multi-service parallel in td-scdma system

Info

Publication number: WO2011088684A1
Application number: PCT/CN2010/077013
Authority: WO
Inventors: 梁立宏
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-01-19
Filing date: 2010-09-16
Publication date: 2011-07-28
Also published as: CN102131277B; CN102131277A

Abstract

A terminal channel estimation method for multi-service parallel in a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system is disclosed by the present invention, wherein the method includes: performing initial channel estimation, and obtaining channel estimation values; obtaining relative sizes of each Code Combination Transmission Channel (CCTRCH) power; according to the relative sizes of each CCTRCH power, correcting the tap energy of the channel estimation values, and performing the first channel estimation post processing; according to the result of the first channel estimation post processing, performing the second channel estimation post processing, and obtaining the ultimate effective taps. The present invention also provides a terminal channel estimation system for multi-service parallel in a TD-SCDMA system. Based on the system and method in the present invention, the accuracy of channel estimation can be improved, and thus the demodulation performance of low-power services is enhanced.

Description

Terminal channel estimation method and system for multi-service parallel in TD-SCDMA system

The present invention relates to a wireless communication processing technology, and in particular to a terminal channel estimation method and system for multi-service parallel in a TD-SCDMA system. Background technique

The Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system is Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (Frequency Division Multiple Access). , FDMA) and Code Division Multiple Access (CDMA) flexible combination of multiple transmission modes. Its main advantages are mainly reflected in a variety of new technologies such as smart antennas, software radios, and joint detection applications. The joint detection is mainly used to demodulate user data, and the premise of the joint detection algorithm application is to accurately estimate the channel impulse response of each user.

The channel estimation of TD-SCDMA system uses the classic Steiner estimator, which is a low-cost channel estimation method. The Mindamble code of each user is constructed according to a certain rule through a basic Midamble code, so that the receiver is at the receiving end. The Midamble code system matrix has cyclic correlation, so that fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) calculations can be used to quickly obtain channel estimation values. First, the original channel estimation value is estimated, and the threshold is set according to the peak value of the estimated channel energy of 128 channels, or the noise threshold is further set according to the mean value of the tap energy smaller than the peak threshold, and the noise is removed by the noise threshold to obtain the final channel estimation value.

In a TD-SCDMA system, when multiple services are parallel, different services are mapped to different code combined transport channels (CCTRCH), each CCTRCH corresponding to one or more physical channels, and sent in one time slot, for different CCTRCH Power control is performed separately. At CCTRCH When the power difference between the two is large, the threshold energy of the CCTRCH with a small power may be below the threshold according to the peak value of the tap energy of the user. In this case, the channel estimation value is all zero, resulting in power comparison. The signal of the small CCTRCH cannot be correctly demodulated. Summary of the invention

In view of this, the main object of the present invention is to provide a method and system for terminal channel estimation in a multi-service parallel of a TD-SCDMA system, which can effectively prevent the channel estimation value of the low-power CCTRCH from being zero, ensuring low power. The CCTRCH signal can be demodulated normally.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

The present invention provides a terminal channel estimation method for multi-service parallel in a TD-SCDMA system, the method comprising:

Obtain the relative size of each CCTRCH power;

Correcting the tap energy of the channel estimation value according to the relative magnitude of each CCTRCH power, and performing the first channel estimation post-processing;

According to the result of the post-channel estimation post-processing, the second channel estimation post-processing is performed to obtain the final effective tap.

Before the obtaining the relative magnitude of each CCTRCH power, the method further includes: initial channel estimation, obtaining a channel estimation value.

The correcting the tap energy of the channel estimation value includes:

First calculating a tap energy of the channel estimation value according to the channel estimation value, and correcting a tap energy of the channel estimation value by using a linear value of a relative magnitude of each CCTRCH power to obtain a tap energy of the corrected channel estimation value. .

The method for correcting the tap energy of the channel estimation value by using a linear value of a relative magnitude of each CCTRCH power is:

And multiplying the corresponding CCTRCH corresponding tap power by a linear value of a relative magnitude between the powers of the CCTRCHs to obtain a corrected tap power; or The absolute value of the square root gives the corrected tap power.

The first channel estimation post-processing includes:

Calculating a peak threshold for processing after the first channel estimation;

Comparing the tap energy of the corrected channel estimate with the peak threshold, the tap energy of the channel estimate less than the peak threshold is set to 0, and the tap of the channel estimate greater than the peak threshold is active.

The second channel estimation post-processing includes:

And averaging the uncorrected tap energy corresponding to the tap position less than the peak threshold in the first channel estimation post-processing;

Calculating a noise threshold processed after the second channel estimation;

The effective tap energy selected by the first channel estimation post-processing is compared with the noise threshold, and the tap energy of the channel estimation value smaller than the noise threshold is set to 0, and the noise threshold is greater than the effective channel estimation of the final channel estimation.

The present invention further provides a terminal channel estimation system for multi-service parallel in a TD-SCDMA system, the system comprising: an acquisition power relative size module, a first channel estimation post-processing module, and a second channel estimation post-processing module, among them,

The acquiring a power relative size module is connected to the first channel estimation post-processing module, and configured to acquire a relative size of each CCTRCH power;

The first channel estimation post-processing module is connected to the second channel estimation post-processing module, configured to correct the tap energy of the channel estimation value according to the relative magnitude of each CCTRCH power, and perform the first channel estimation post-processing;

The second channel estimation post-processing module is configured to perform a second channel estimation post-processing according to the result of the first channel estimation post-processing to obtain a final effective tap.

The system further includes: an initial channel estimation module, and the first channel estimation The post-processing modules are connected to obtain channel estimation values.

The tap energy of the modified channel estimation value includes:

First calculating a tap energy of the channel estimation value according to the channel estimation value, and then using each of the

A linear value of the relative magnitude of the CCTRCH power corrects the tap energy of the channel estimate to obtain the tap energy of the corrected channel estimate.

The method for correcting the tap energy of the channel estimation value by using a linear value of a relative magnitude of each CCTRCH power includes:

The corrected tap power is obtained by multiplying the respective CCTRCH corresponding tap power by a linear value of the relative magnitude between the powers of the CCTRCHs; or the absolute value of the square root to obtain the corrected tap power.

The first channel estimation post-processing includes:

Calculating a peak threshold for processing after the first channel estimation;

The second channel estimation post-processing includes:

Calculating a noise threshold processed after the second channel estimation;

A method and system for terminal channel estimation in a multi-service parallel of a TD-SCDMA system provided by the present invention, wherein an initial transmission power of each CCTRCH is recorded by a base station, and The power control adjustment amount of the CCTRCH is obtained, and the relative power of each CCTRCH is obtained, and is transmitted to the terminal in the form of signaling. The terminal can correct the corresponding tap power of each CCTRCH according to the CCTRCH power information carried in the previous frame signaling. The corrected tap power p ₀ r_ r _e W«3⁄4 is obtained, and then the threshold of the modified tap is set to complete the first channel estimation post-processing; and the final channel estimation is obtained by the second channel estimation post-processing. Effective tapping. Since the corresponding tap power of each CCTRCH is corrected, it is ensured that the channel estimation value of the low power CCTRCH is not set to zero, so that the low power CCTRCH signal can be normally demodulated; the channel estimation accuracy is improved, thereby improving the low power. Demodulation performance of the business. DRAWINGS

1 is a schematic flow chart of a method for estimating a terminal channel in a multi-service parallel of a TD-SCDMA system according to an embodiment of the present invention;

2 is a schematic diagram of post-multiple CCTRCH channel estimation post-processing before power correction according to an embodiment of the present invention;

3 is a schematic diagram of post-processing of multi-CCTRCH channel estimation after power correction in an embodiment of the present invention;

4 is a schematic flowchart of a first channel estimation post-processing according to an embodiment of the present invention; FIG. 5 is a schematic flowchart of a second channel estimation post-processing according to an embodiment of the present invention; FIG. 6 is a TD-SCDMA system according to an embodiment of the present invention; Schematic diagram of a terminal channel estimation system under multi-service parallelism. detailed description

The basic idea of the present invention is: obtaining the relative magnitude of each CCTRCH power; correcting the tap energy of the channel estimation value according to the relative magnitude of each CCTRCH power, performing the first channel estimation post-processing; processing according to the first channel estimation Result, the second channel is performed Estimate post-processing to get the final effective tap.

Specifically, the base station records the initial transmit power of each CCTRCH and the power control adjustment amount during the duration of the CCTRCH, and obtains the relative power of each CCTRCH, which is transmitted to the terminal in the form of signaling, and the terminal may carry according to the previous frame signaling. Each CCTRCH power information corrects the corresponding tap power of each CCTRCH of the user, obtains the corrected tap power po revised, and further completes the first channel estimation post-processing by setting the threshold of the peak of the tapped taper; Sub-channel estimation post-processing yields the effective tap of the final channel estimate.

The technical solutions of the present invention are further elaborated below in conjunction with the accompanying drawings and specific embodiments. 1 is a schematic flowchart of a method for estimating a terminal channel in a multi-service parallel of a TD-SCDMA system according to the present invention. As shown in FIG. 1, the method for estimating a terminal channel of the present invention includes the following steps:

Step 101: Initial channel estimation, obtaining a channel estimation value;

Specifically, the terminal first calculates the frequency i of the received Midamble code part data received_midamble or the value received_midamble_fft and the frequency i or value of the Midamble code basic_midamble_fft, the mouth formula is as follows:

Received midamble fft = fft(received midamble)

Basic midamble fft = fft(basic_midamble) data; basic midamble ^^ this Midamble code.

The channel estimation value channel is calculated by first dividing the above two frequency domain values, and the obtained result is transformed into the time domain by an inverse fast Fourier transform (IFFT), as shown in the formula:

Channel = ifft(received_midamble_fft · /basic_midamble_fft)

Where / . / indicates that the two arrays are divided by the corresponding number.

Step 102: Obtain a relative size of each CCTRCH power.

Specifically, the base station (Node B ) records the initial transmit power of each CCTRCH and the power control adjustment amount of the CCTRCH duration, and obtains the absolute transmit power of each CCTRCH. Give the terminal.

Step 103, the first channel estimation post-processing;

Specifically, the tap energy of the channel estimation value is corrected according to the relative magnitude between the powers of the respective CCTRCHs, and then the peak threshold is calculated according to the corrected tap energy, and the tap energy of the corrected channel estimation value is compared with the peak threshold, which is smaller than the peak value. The tap energy of the channel estimate of the threshold is set to zero, and the tap of the channel estimate greater than the peak threshold is valid.

The terminal first calculates the tap power of the channel estimation value according to the channel estimation value channel, as shown in the formula:

Power = real(channel ). ^Λ 2 + imag(channel ). ^Λ 2

Correcting the corresponding tap power of each CCTRCH of the user according to each CCTRCH power information carried in the previous frame signaling, specifically: multiplying the corresponding power of each CCTRCH by the linear value of the relative magnitude between the powers of the respective CCTRCHs, and obtaining the corrected Tap power power _ revised. The equivalent correction method can also directly correct the amplitude. The specific method is that the amplitude of the tap is multiplied by the absolute value of the square root of the relative magnitude between the powers of the respective CCTRCHs, and the corrected tap amplitude is obtained, and the correction is further calculated. After the tap power. 2 is a schematic diagram of post-processing of multi-CCTRCH channel estimation before power correction according to an embodiment of the present invention. As shown in FIG. 2, CCTRCH 1 has one channel window, signal energy is weak, CCTRCH 2 has 5 channel windows, and signal energy Stronger, if the channel estimation threshold Th1 is set according to the user tap peak Peak, all taps of CCTRCH 1 are below the threshold, and the channel estimation values will all be zero, so that the signal of CCTRCH 1 cannot be correctly demodulated. 3 is a schematic diagram of post-processing of multi-CCTRCH channel estimation after power correction according to an embodiment of the present invention. After CCTRCH 1 undergoes the correction as described above, as shown in FIG. 3, the tap of CCTRCH 1 after ^^' All of them are above the threshold and the channel estimate will not be set to 0. The signal of CCTRCH 1 can be correctly demodulated.

After the corrected tap power po r — r ^^, the first channel estimation post-processing gate is calculated. Limit, first set the peak threshold Th1 according to all the corrected tap power of the user, as shown in the formula: Thl = max(power revised) * λ\

Where 0 < λ1 < 1 is the peak threshold coefficient;

After the peak threshold Thl is obtained, the tap energy of the corrected channel estimate is compared with the peak threshold Thl:

Specifically, the tap energy p r r re of the corrected channel estimation value is compared with the peak threshold Th1, and the tap energy of the channel estimation value smaller than the peak threshold Th1 is set to 0, and the tap of the channel estimation value larger than the peak threshold is effective.

Step 104, second channel estimation post-processing;

Specifically, the second channel estimation post-processing threshold is first calculated. First, the uncorrected tap energy pow corresponding to the tap position less than the peak threshold in the first channel estimation post-processing is averaged, and then multiplied by a noise threshold coefficient as noise. Threshold Th2, as shown in the formula:

Th2 = mQan(power(find (power _ revised < Thl))) * Λ2

Where λ2>1 is the noise threshold coefficient; mean means the calculated mean; find (power _ revised < Thl) means the tap energy of the channel estimate after the positive power _ revised and the peak threshold Th1, the channel estimate smaller than the peak threshold Th1 Tap position.

Then, the effective tap energy pow selected by the first channel estimation post-processing is compared with the noise threshold Th2, the tap energy of the channel estimation value smaller than the noise threshold Th2 is set to 0, and the last retained tap is the final effective tap.

The terminal channel estimation method of the present invention for multi-service parallel operation in the TD-SCDMA system will be described below by way of a specific embodiment.

Take = , = 8 as an example, where P = 128 is the length of the basic Midamble code, = 16

As shown in FIG. 2, there are two CCTRCHs, the first channel window belongs to CCTRCH 1, the second to sixth channel windows belong to CCTRCH 2, and the energy of CCTRCH 1 is weaker than CCTRCH2. 1. First perform initial channel estimation:

The terminal first calculates the frequency domain value received_midamble_fft of the received Midamble code part data received_midamble and the frequency domain value basic_midamble_fft of the Midamble code, as shown in the formula: received midamble fft = fft(received midamble)

The channel estimation value channel is calculated by first dividing the above two frequency domain values, and then converting the result to the time domain by IFFT, as shown in the formula:

Channel = ifft(received_midamble_fft - /basic midamble fft)

2. Obtain the relative size of each CCTRCH power;

Specifically, the base station (Node B ) records the initial transmit power of the two CCTRCHs and the power control adjustment amount of the two CCTRCH durations, and obtains the absolute transmit power of the two CCTRCHs, and positions the relative power of the CCTRCH 1 to the OdB, CCTRCH 2 The relative power is 6 dB and is finally transmitted to the terminal in the form of signaling.

3. The first channel estimation post-processing; specifically, FIG. 4 is a schematic flowchart of the first channel estimation post-processing in the embodiment of the present invention, as shown in FIG.

Step 401: Calculate a tap energy of the channel estimation value;

Specifically, the terminal first calculates the tap power of all 128 channel estimation values according to the channel estimation value channel, as shown in the formula:

Power = real(channel ). ^Λ 2 + imag(channel ). ^Λ 2

Step 402: Correct the tap energy according to the signaling information;

Specifically, the corrected tap power p ₀ wr _ r _e ; ^ is obtained by multiplying the respective CCTRCH corresponding tap power by the linear value of the relative magnitude between the powers of the respective CCTRCHs. As shown in the formula: Power _ revised = power (17: 96) * 4

Among them, 10*loglO(4)=6dB, 4 is a linear value of the power relative magnitude of CCTRCH 2 of 6dB; power (17:96) represents the tap energy of the channel estimation value of CCTRCH 2, specifically, 17:96 In Figure 2, CCTRCH 2 with 1 channel window (2nd to 6th channel window) from 17th chip to 96th chip, 1 : 16 means that there is a channel window from the 1st chip to the 16th chip (the first channel window) ) CCTRCH 1 ;

Step 403, calculating a peak threshold of the first channel estimation post processing;

Specifically, the peak threshold Thl is set according to all corrected tap powers of the user, as shown in the formula:

73⁄41 = max(power _ revised) * λ\

Where 0 < λ1 < 1 is the peak threshold coefficient;

Step 404, peak threshold comparison;

Specifically, comparing the tap energy p ₀ wr — r^;^ of the corrected channel estimation value calculated in step 402 with the peak threshold Th1 calculated in step 403, the tap energy of the channel estimation value smaller than the peak threshold Th1 is set to 0, which is greater than The tap of the channel estimate of the peak threshold Th1 is valid.

4. The second channel estimation post-processing, specifically, FIG. 5 is a schematic flowchart of the second channel estimation post-processing in the embodiment of the present invention, as shown in FIG.

Step 501: Calculate an energy average of the taps smaller than the peak threshold Thl;

The uncorrected tap energy powe corresponding to the tap position less than the peak threshold in the first channel estimation post-processing is averaged (po wer (fin _ revised < ThT) J).

Step 502, calculating a noise threshold of the second channel estimation post-processing;

The average value calculated in step 501 is multiplied by the noise threshold coefficient to obtain a noise threshold Th2. As the formula shows: Th2 = mean(power(find (power _ revised < Thl))) * Λ2

Where λ2>1 is the noise threshold coefficient. Step 503, comparing noise thresholds;

Comparing the effective tap energy powe selected in step 404 with the noise threshold Th2 calculated in step 502, the tap energy of the channel estimate less than the noise threshold Th2 is set to 0, and the noise threshold Th2 is the effective tap of the final channel estimate.

6 is a schematic structural diagram of a terminal channel estimation system in a multi-service parallel of a TD-SCDMA system according to the present invention. As shown in FIG. 6, the system includes: an initial channel estimation module 61, an acquisition power relative size module 62, and a first channel estimation. a post-processing module 63 and a second channel estimation post-processing module 64;

The initial channel estimation module 61 is connected to the first channel estimation post-processing module 63 for obtaining an initial channel estimation value;

Specifically, the initial channel estimation module 61 first calculates the received Midamble code part data received midamble frequency i or the value received midamble fft and the Midamble code frequency i or the value basic midamble fft, as shown in the formula:

Received midamble fft = fft(received midamble);

Basic midamble fft = fft(basic_midamble) , data; basic midamble ^^ this Midamble code.

Channel = ifft(received_midamble_fft - /basic midamble fft)

The obtaining power relative size module _{62 is} connected to the first channel estimation post-processing module 63 for obtaining a relative size of each CCTRCH power;

Specifically, the initial transmit power of each CCTRCH and the power control adjustment amount of the CCTRCH duration are recorded, and the absolute transmit power of each CCTRCH is obtained, thereby obtaining each The relative magnitude between the powers of the CCTRCH is finally transmitted to the first channel estimation post-processing module 63 in the form of signaling.

The first channel estimation post-processing module 63 is connected to the second channel estimation post-processing module 64 for correcting the tap energy of the channel estimation value according to the relative magnitude between the powers of the respective CCTRCHs, and then calculating according to the corrected tap energy. a peak threshold, comparing the tap energy of the corrected channel estimation value with a peak threshold, setting a tap energy of the channel estimation value smaller than the peak threshold to 0, and a tap of the channel estimation value greater than the peak threshold is valid;

Specifically, the terminal first calculates the tap energy power of the channel estimation value according to the channel estimation value channel, as shown in the formula:

Power = real(channel ). ^Λ 2 + imag(channel ). ^Λ 2;

Correcting the corresponding tap power of each CCTRCH of the user according to each CCTRCH power information carried in the previous frame signaling, specifically: multiplying the corresponding power of each CCTRCH by the linear value of the relative magnitude between the powers of the respective CCTRCHs, and obtaining the corrected Tap power powr_re ;«^. The equivalent correction method can also directly correct the amplitude. The specific method is that the amplitude of the tap is multiplied by the absolute value of the square root of the relative magnitude between the powers of the respective CCTRCHs, and the corrected tap amplitude is obtained, and the correction is further calculated. After the tap power.

Then calculate the post-channel estimation post-processing threshold, first set the peak threshold Thl based on all corrected tap powers, as shown in the formula:

73⁄41 = max(power _ revised) * λ\

Where 0 < λ1 < 1 is the peak threshold coefficient;

Specifically, comparing the tap energy powr _r _ei ^ of the corrected channel estimation value with the peak threshold Th1, the tap energy of the channel estimation value smaller than the peak threshold Th1 is set to 0, and the tap of the channel estimation value larger than the peak threshold is valid. . The second channel estimation post-processing module 64 is configured to calculate a second channel estimation post-processing threshold, and perform a second channel estimation post-processing according to the second channel estimation post-processing threshold to obtain a final effective tap;

Th2 = mQan(power(find (power _ revised < ThV ) * Λ2

Where λ2>1 is the noise threshold coefficient; mean means the calculated mean; find (power _ revised <Th\) means the tap energy of the channel estimate after the positive power comparison and the peak threshold TW, the channel estimation tap position smaller than the threshold ;

Then, comparing the effective tap energy p ₀ W selected by the first channel estimation post-processing with the noise threshold Th2, the tap energy of the channel estimation value smaller than the noise threshold Th2 is set to 0, and the last retained tap is the final effective tap. .

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included. Within the scope of protection of the present invention.

Claims

Claim

A method for estimating a terminal channel in a multi-service parallel of a TD-SCDMA system, the method comprising:

Obtaining a relative size of each code combined transport channel (CCTRCH) power;

2. The method for estimating a terminal channel in a multi-service parallel of a TD-SCDMA system according to claim 1, wherein before the obtaining a relative size of each CCTRCH power, the method further comprises: initial channel estimation, obtaining a channel estimated value.

The terminal channel estimation method in the multi-service parallel of the TD-SCDMA system according to claim 1 or 2, wherein the correcting the tap energy of the channel estimation value comprises: first calculating according to the channel estimation value The tap energy of the channel estimate is used to correct the tap energy of the channel estimate by using a linear value of the relative magnitude of each CCTRCH power to obtain a tap energy of the corrected channel estimate.

4. The method for estimating a terminal channel in a multi-service parallel of a TD-SCDMA system according to claim 3, wherein said tapping energy of said channel estimation value is obtained by using a linear value of a relative magnitude of said respective CCTRCH powers The method of making corrections is:

The terminal channel estimation method in the multi-service parallel of the TD-SCDMA system according to claim 1 or 2, wherein the first channel estimation post-processing comprises:

Calculating a peak threshold for processing after the first channel estimation; Comparing the tap energy of the corrected channel estimate with the peak threshold, the tap energy of the channel estimate that is less than the peak threshold is set to zero, and the tap of the channel estimate that is greater than the peak threshold is valid.

The terminal channel estimation method in the multi-service parallel of the TD-SCDMA system according to claim 1 or 2, wherein the second channel estimation post-processing comprises:

Calculating a noise threshold processed after the second channel estimation;

A terminal channel estimation system for multi-service parallel in a TD-SCDMA system, wherein the system comprises: an acquisition power relative size module, a first channel estimation post-processing module, and a second channel estimation post-processing module. , among them,

The terminal channel estimation system in the multi-service parallel of the TD-SCDMA system according to claim 7, wherein the system further comprises: an initial channel estimation module, connected to the first channel estimation post-processing module , used to obtain channel estimation values.

The terminal channel estimation system in the multi-service parallel of the TD-SCDMA system according to claim 7 or 8, wherein the tap energy of the modified channel estimation value comprises: First calculating a tap energy of the channel estimation value according to the channel estimation value, and then using each of the

10. The terminal channel estimation system for multi-service parallel in a TD-SCDMA system according to claim 9, wherein said tap energy of said channel estimation value is determined by a linear value of a relative magnitude of said respective CCTRCH powers The method of making corrections includes:

The terminal channel estimation system in the multi-service parallel of the TD-SCDMA system according to claim 7 or 8, wherein the first channel estimation post-processing comprises:

Calculating a peak threshold for processing after the first channel estimation;

The terminal channel estimation system in the multi-service parallel of the TD-SCDMA system according to claim 7 or 8, wherein the second channel estimation post-processing comprises:

Calculating a noise threshold processed after the second channel estimation;