CN102946369A - Rapid detection method and device based on minimum mean square error (MMSE)-peripheral interface controller (PIC) equalizer - Google Patents

Abstract

The invention discloses a rapid detection method and a device based on a minimum mean square error (MMSE)-peripheral interface controller (PIC) equalizer. The method comprises the following steps of: calculating a sign offset factor according to a coefficient of an MMSE filter, and calculating the assignment constant based on the sign offset factor; and carrying out assignment substitution on the sign estimating variance in the calculating process of sign prior probability based on the assignment constant during detection of signs. By the rapid detection method and device, the sign estimating variance calculation can be improved during MMSE-PIC detection, so that the complexity of the whole detection algorithm is lowered; and besides, the division operation in the sign prior probability calculation can be improved, so that the operating efficiency of the equalizer is improved.

Description

Method for quick and device based on the MMSE-PIC equalizer

Technical field

The present invention relates to the signal equalization technology, particularly relate to method for quick and device based on the MMSE-PIC equalizer.

Background technology

MMSE-PIC(Minimum Mean Square Error-Parallel Interference Cancellation, parallel interference elimination based on minimum-mean square error filters) detection technique is as one of balancing technique commonly used, do not consider the sign condition number, when complexity can be guaranteed, can realize better portfolio effect.This technology is a kind of by symbol detector, obtains transmitted signal by iterative detection.

Wherein, the MMSE-PIC detection technique is mainly carried out according to the following steps:

When (1) iteration begins for the first time, calculate the MMSE filter coefficient according to the residual interference variance, according to symbol posterior probability values structure interference signal vector.

(2) disturb elimination, compute sign estimated value and sign estimation variance.

(3) according to sign estimation value and sign estimation variance, the compute sign prior probability, according to prior probability, compute sign posterior probability, then compute sign posterior probability values and residual interference variance.

(4) next iteration begins, and utilizes symbol posterior probability values and residual interference variance, and update signal is disturbed vector sum MMSE filter coefficient respectively, then carries out (2), (3).When reaching maximum iteration time, the output symbol estimated value.

Traditional MMSE-PIC detection technique need the compute sign estimate variance in the testing process, and the compute sign estimate variance need to be carried out a large amount of multiply-add operations; When the compute sign prior probability, need a large amount of division arithmetics in addition, these computings have increased undoubtedly algorithm complex, have reduced the operational efficiency of processor.

Summary of the invention

Based on this, be necessary for the problems referred to above, a kind of method for quick based on the MMSE-PIC equalizer and device are provided, can improve the efficient of equalizer.

A kind of method for quick based on the MMSE-PIC equalizer comprises:

According to MMSE filter coefficient compute sign displacement factor, calculate the assignment constant by this symbol offset factor;

When symbol detection, utilize described assignment constant, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

Correspondingly, a kind of device for fast detecting based on the MMSE-PIC equalizer comprises:

Constant computation unit is used for according to MMSE filter coefficient compute sign displacement factor, calculates the assignment constant by this symbol offset factor;

The constant assignment unit that links to each other with described constant computation unit is used for utilizing described assignment constant when symbol detection, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

Implement the present invention, have following beneficial effect:

In the MMSE-PIC detection technique, calculating improves to the sign estimation variance, utilizes every one-level to detect the constant that begins to calculate, and all sign estimation variances are carried out assignment operation, eliminate multiplication and add operation, improved the operational efficiency of MMSE-PIC equalizer; In the loop computation to same stage, the division arithmetic in the prior probability calculating is improved to multiplying simultaneously, can reduces whole detection algorithm complexity, improve the arithmetic speed of MMSE-PIC equalizer.

Description of drawings

Fig. 1 is the flow chart that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 2 is the embodiment flow chart that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 3 is the awgn channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 4 is the TU50 channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 5 is the HT100 channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 6 is the schematic diagram that the present invention is based on the device for fast detecting of MMSE-PIC equalizer;

Fig. 7 is the embodiment schematic diagram that the present invention is based on the device for fast detecting of MMSE-PIC equalizer.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing.

Fig. 1 is the flow chart that the present invention is based on the method for quick of MMSE-PIC equalizer, comprising:

S101: according to MMSE filter coefficient compute sign displacement factor, calculate the assignment constant by this symbol offset factor;

S102: when symbol detection, utilize described assignment constant, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

After iteration begins, calculate the MMSE filter coefficient.At this moment, can adopt the mode of calculating the MMSE filter coefficient according to the residual interference variance.According to MMSE filter coefficient compute sign displacement factor μ, then calculate the assignment constant alpha according to the symbol offset factor _T

Symbol offset factor computing formula is as follows:

$\mathrm{\μ}=w_N^H{h}_{N+L+1}$

W represents the MMSE filter coefficient in the following formula; h _N+L+1It is channel matrix H _N(N+L+1) row, N is-symbol correlation length, L is the channel impulse response tap number.

Then calculate the assignment constant alpha according to the symbol offset factor mu _T, this assignment constant calculations is as follows:

a _T=μ(1-μ)

Need to prove that the above-mentioned formula of the present invention is not got rid of other under the principle of the invention, can also make some distortion and improvement, these all belong to protection scope of the present invention.

Then, when symbol detection begins, can utilize the assignment constant alpha of calculating above _T, to the sign estimation variance

Carry out assignment and replace, the concrete mode of replacement comprises:

So far, in traditional MMSE-PIC equalizer, the calculating book of symbol prior probability should be as follows:

$P({\widehat{\mathrm{\α}}}_k/{\mathrm{\α}}_k=\mathrm{\α})=\exp (-\frac{|{{\widehat{\mathrm{\α}}}_k-\mathrm{\μ\α}|}^2}{2{\mathrm{\σ}}_k^2})$

In the middle of the above-mentioned prior art, the sign estimation variance is calculated as denominator.And each sign estimation variance is different.Therefore for each symbol, calculating prior probability all needs to carry out division arithmetic.

After the present invention's improvement, computing formula is as follows:

$P({\widehat{\mathrm{\α}}}_k/{\mathrm{\α}}_k=\mathrm{\α})=\exp (-\frac{|{{\widehat{\mathrm{\α}}}_k-\mathrm{\μ\α}|}^2}{2a_T})$

Following formula is analyzed as can be known, adopted after the replacement method of the present invention, during every one-level detected, all sign estimation variances all were identical, namely for all symbols, were constants as the sign estimation variance of denominator.Therefore can calculate an assignment constant according to the sign estimation variance that calculates among the step S101, and it is preserved.When calculating the prior probability of each symbol, the assignment constant of preservation is put among the prior probability computing.

Therefore, computational methods of the present invention mainly contain 2 improvement: (1) sign estimation variance converts assignment to by complicated calculations and substitutes; (2) calculate the assignment constant that obtains according to the sign estimation variance, in the calculating of substitution prior probability, reduced the complexity of computing, improve arithmetic speed and the efficient of MMSE-PIC equalizer.

Fig. 2 is the embodiment flow chart that the present invention is based on the method for quick of MMSE-PIC equalizer.Compared to Figure 1, Fig. 2 is the flow chart of the preferred embodiment of the present invention.

S201: when every one-level iterative detection begins, according to current MMSE filter coefficient compute sign displacement factor;

S202: calculate the assignment constant by this symbol offset factor;

S203: when symbol detection, obtain the multiplication factor constant according to described assignment constant;

S204: in the MMSE-PIC equalizer, the denominator in all symbol prior probability computing formula replaces with described multiplication factor constant.

At first, the embodiment of the invention adopts the 8PSK modulation.The MMSE-PIC detector, when every one-level iterative detection began, according to MMSE filter coefficient compute sign displacement factor, symbol offset factor computing formula was as follows:

$\mathrm{\μ}=w_N^H{h}_{N+L+1}$

W represents the MMSE filter coefficient in the following formula; h _N+L+1It is channel matrix H _N(N+L+1) row, N is-symbol correlation length, L is the channel impulse response tap number.

Then calculate the assignment constant alpha according to the symbol offset factor mu _T, this assignment constant calculations is as follows:

a _T=μ(1-μ)

Then, carry out assignment operation, the compute sign estimate variance

${\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="HDA00002507598400022.png"\; state="\{\{state\}\}">k</figure-callout>}}^2=a_T$

Secondly, calculate multiplication factor constant q according to the sign estimation variance

$q=\frac{1}{2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="HDA00002507598400022.png"\; state="\{\{state\}\}">k</figure-callout>}}^2}=\frac{1}{2\mathrm{\&mu;}(1-\mathrm{\&mu;})}$

At last, in traditional MMSE-PIC equalizer, shown in being calculated as follows of symbol prior probability:

$P({\widehat{\mathrm{\&alpha;}}}_k/{\mathrm{\&alpha;}}_k=\mathrm{\&alpha;})=\exp (-\frac{|{{\widehat{\mathrm{\&alpha;}}}_k-\mathrm{\&mu;\&alpha;}|}^2}{2{\mathrm{\&sigma;}}_k^2})$

According to multiplication factor constant q, the division arithmetic in the above-mentioned formula is converted into multiplying, the computing formula after the improvement is as follows:

$P\left({\widehat{\mathrm{\&alpha;}}}_k/{\mathrm{\&alpha;}}_k=\mathrm{\&alpha;}\right)=\exp (-q{{|\widehat{\mathrm{\&alpha;}}}_k-\mathrm{\&mu;\&alpha;}|}^2)$

Obviously, computational methods provided by the invention, the way with respect in traditional MMSE-PIC detector does not need a large amount of multiply-add operations, only need to carry out assignment operation and get final product.Therefore the present invention can reduce the complexity that the sign estimation variance is calculated.

In addition, during for compute sign prior probability of the present invention, the division arithmetic in the formula is converted into multiplying; And traditional MMSE-PIC detection algorithm because each sign estimation variance is different, must carry out division arithmetic.Therefore, design of the present invention can reduce the complexity that the symbol prior probability calculates.

At last, the present invention can reduce computational complexity by above-mentioned two-part calculating is made amendment, and whole MMSE-PIC detector arithmetic speed is accelerated.

Fig. 3 is the awgn channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 4 is the TU50 channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer;

Fig. 5 is the HT100 channel design sketch that the present invention is based on the method for quick of MMSE-PIC equalizer.

In various channels, all obtain good test effect below in conjunction with Fig. 3,4,5 explanation embodiments of the present invention.

EDGE(Enhanced Data Rate for GSM Evolution) in the system, adopt the 8PSK modulation, below form provide way of the present invention and existing computational methods, about the contrast of above-mentioned two parts computation complexity.In the EDGE system, a time slot comprises 148 useful data symbols, corresponding 3 bits of symbol.The iterations that detector is considered is 3.

Below numerical value in table 1 and the table 2, all be to consider 3 iteration, calculate 148 operands that symbol needs altogether.

Computational methods	Addition	Multiplication	Division
				Existing way	188700	369408	888
Way of the present invention	3	3	?

In the table 1EDGE system, the contrast of sign estimation variance computation complexity

For the calculating of symbol prior probability, the existing way of main contrast and way of the present invention, needed division arithmetic.

Computational methods	Division
		Existing way	7104
Way of the present invention	3

In the table 2EDGE system, the contrast of symbol prior probability computation complexity

In the table 2, one time division arithmetic is equivalent to 10 multiplyings, the data above therefore contrasting, and way of the present invention can reduce the MMSE-PIC detector complexity.

In the EDGE system, adopt the 8PSK modulation, below the MMSE-PIC detector of form after providing traditional MMSE-PIC detector and utilizing the present invention to improve, detect needed time contrast, these data are used 3000 data blocks based on matlab emulation.

Time	Hour
		Conventional detector	3.5
Detector after the present invention optimizes	2.3

Table 3 detects the required time contrast

Fig. 3 to 5 utilizes computational methods provided by the invention, the MMSE-PIC detector is improved the then performance through obtaining after the decoding, and the performance comparison figure of traditional MMSE-PIC detector.When wherein Fig. 3 had provided the 8PSK modulation, the BLER Performance Ratio under the Gaussian channel; When Fig. 4 had provided the 8PSK modulation, the BLER Performance Ratio under the TU50 channel; BLER Performance Ratio when Fig. 5 has provided the 8PSK modulation under the HT100 channel.Through relatively, utilize the present invention that the MMSE-PIC detector is optimized design, when reducing the processing complexity, can guarantee accuracy of detection.

Fig. 6 is the schematic diagram that the present invention is based on the device for fast detecting of MMSE-PIC equalizer, comprising:

Constant computation unit is used for according to MMSE filter coefficient compute sign displacement factor, calculates the assignment constant by this symbol offset factor;

The constant assignment unit that links to each other with described constant computation unit is used for utilizing described assignment constant when symbol detection, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

Fig. 6 is corresponding with Fig. 1, among the figure unit with operational mode and method in identical.

Fig. 7 is the embodiment schematic diagram that the present invention is based on the device for fast detecting of MMSE-PIC equalizer.

As shown in Figure 7, described constant assignment unit comprises:

Factor calculating unit is used for obtaining the multiplication factor constant according to described assignment constant;

The factor substituting unit that links to each other with described factor calculating unit is used for the MMSE-PIC equalizer, and the denominator in all symbol prior probability computing formula replaces with described multiplication factor constant.

In the middle of embodiment, described constant computation unit also comprises therein:

Calculate preposition unit, be used for when every one-level iterative detection begins, according to current MMSE filter coefficient compute sign displacement factor.

Fig. 7 is corresponding with Fig. 2, among the figure unit with operational mode and method in identical.

The above embodiment has only expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.

Claims (6)

1. the method for quick based on the MMSE-PIC equalizer is characterized in that, comprising:

According to MMSE filter coefficient compute sign displacement factor, calculate the assignment constant by this symbol offset factor;

When symbol detection, utilize described assignment constant, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

2. the method for quick based on the MMSE-PIC equalizer according to claim 1 is characterized in that, utilizes described assignment constant, and the sign estimation variance in the symbol prior probability computational process is carried out the step that assignment substitutes, and comprising:

Obtain the multiplication factor constant according to described assignment constant;

In the MMSE-PIC equalizer, the denominator in all symbol prior probability computing formula replaces with described multiplication factor constant.

3. the method for quick based on the MMSE-PIC equalizer according to claim 1 and 2 is characterized in that, the step according to MMSE filter coefficient compute sign displacement factor comprises:

When every one-level iterative detection begins, according to current MMSE filter coefficient compute sign displacement factor.

4. the device for fast detecting based on the MMSE-PIC equalizer is characterized in that, comprising:

Constant computation unit is used for according to MMSE filter coefficient compute sign displacement factor, calculates the assignment constant by this symbol offset factor;

The constant assignment unit that links to each other with described constant computation unit is used for utilizing described assignment constant when symbol detection, the sign estimation variance in the symbol prior probability computational process is carried out assignment substitute.

5. the device for fast detecting based on the MMSE-PIC equalizer according to claim 4 is characterized in that, described constant assignment unit comprises:

Factor calculating unit is used for obtaining the multiplication factor constant according to described assignment constant;

The factor substituting unit that links to each other with described factor calculating unit is used for the MMSE-PIC equalizer, and the denominator in all symbol prior probability computing formula replaces with described multiplication factor constant.

6. according to claim 4 or 5 described device for fast detecting based on the MMSE-PIC equalizer, it is characterized in that described constant computation unit also comprises:

Calculate preposition unit, when every one-level iterative detection begins, according to current MMSE filter coefficient compute sign displacement factor.

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