RU2605365C1 - Decoder with basic cluster list processing - Google Patents

Abstract

FIELD: radio engineering and communications.

SUBSTANCE: invention relates to communication engineering and can be used when designing and upgrading existing systems for digital information transfer. Decoder enables to correct deletion, rate of which is determined by ratio n-k; significantly reduce processing time of code combinations in decoder due to exclusion from computation process procedures for searching for inverse matrix for permuted generating matrix of code and further formation based thereon of an equivalent code matrix; decoder operates only with basic cluster (always with a single list), without spending, when processing each new received vector, time for preparing a new list by selecting most probable vectors.

EFFECT: technical result consists in improvement of reliability of receiving information and data processing speed.

1 cl, 1 dwg, 8 tbl

Description

The invention relates to communication technology and can be used in the design of new and modernization of existing discrete information transmission systems.

Known devices for erasing recovery and error correction using indexes of soft symbol solutions to increase the likelihood of correct reception of information (see R. Morelos-Zaragoza. The art of noise-resistant coding. Methods, algorithms, application. - M.: Technosfera, 2005, p. 103- 105; as well as devices according to RF patents for inventions No. 2166235; 2209519; 2209520; 2256294; 2344556; 2490804).

In addition, decoding devices for ordered statistics are known (see R. Morelos-Zaragoza. The art of noise-resistant coding. Methods, algorithms, application. - M.: Technosphere, 2005, pp. 213-216).

The closest device of the same purpose is a decoder with ordered symbol statistics (see RF patent for the invention No. 2490804), containing a receiving unit, the first output of which is connected to a signal analyzer, as well as a drive, a cluster definition unit and a code combination drive, one output of which connected to the first input of the erasure correction unit, characterized in that a special rating unit, a special character unit, an evaluation ranking unit, a forbidden combination unit, an equivalent code unit, a shortener code extender and a correction vector block, while the second output of the reception block is connected to the input of the special symbol block, one output of which is connected to the input of the code combination drive, and the other is connected to the first input of the cluster definition block, while the second input of this block is connected to one the output of the block of special evaluations, while the other output of this block is connected through a series-connected drive and the unit for ordering ratings to the first input of the equivalent code block, whose service output is connected to the input of the block of forbidden combinations, and the output of this block is connected to the service input of the equivalent code block, the output of which is connected to the second input of the erasure correction block, while the second input of the equivalent code block is connected to the first output of the correction vector block by the shortened code generator, and one input of this block is connected to the output of the cluster definition block, while the other input of the correction vector block is connected to the other output of the code combination drive, and the output of the corre The projection vector is connected to the third input of the erasure correction unit.

The disadvantages of the work of analogs, including the prototype of the proposed decoder, include the incomplete use of the redundancy introduced in the code due to the use of the Hamming metric that does not take into account the spectral characteristics of the code, the need to search for the inverse matrix in the permutation decoding procedure by the values of soft decision indices (IMR ) to assess the feasibility of switching to equivalent code combinations. This leads to the fact that with an increase in the multiplicity of errors corrected by the code, the computational complexity of the decoder becomes exponential.

EFFECT: increased reliability of information reception and data processing speed. The block diagram of the decoder is shown in figure 1. To achieve a technical result, the decoder with the processing of the list of the base cluster contains a receiving unit 1, the first output of which is connected to the first input of the cluster number determination unit 3, through the one output of the soft decision index formation unit 2, while the second the output of the receiving unit 1 through the drive 10 code combinations is connected to the first input of the error correction unit 13, into which the cluster number verification unit 4, the key combination unit 5, the re-entry unit 6 are additionally introduced ode to the base cluster, base cluster unit 7, linearity check unit 8, permutation matrix transpose unit 11, error allocation unit 9, reverse permutation unit 12, while the first output of the cluster number determination unit 3 is connected to the input of the cluster number check unit 4, and the output of this block 4 is connected to the second input of the cluster number determination block 3, the second output of which through the key combination block 5 is connected to the first input of the transition block 6 to the base cluster, the first output of this block 6 through the block 7 of the base cluster is connected to the input of linearity checking block 8, while its single output through error highlighting block 9 is connected to the first input of reverse permutation block 12, while the other output of linearity checking block 8 is connected to one input of transposition matrix transposition block 11, and the output of this block 11 connected to the second input of the reverse permutation block 12 and the output of this block 12 is connected to the second input of the error correction block 13, while the third output of the linearity check block 8 is connected to the second input of the transition to base cluster unit 6, w swarm whose output is connected to another input unit 11 transpose of the permutation matrix, wherein the third transfer unit 6 included in the base cluster is connected to another output of the unit 2 forming the soft decisions indices. The operation of the decoder with processing the list of the base cluster is illustrated by the example of the BCH code (15, 5, 7) with the generating polynomial g (x) = 2467 ₈ and the generating matrix G of the form:

The set of code combinations of the code is divided into clusters by allocating f any digits, where 1 <f≤k. Let f = 3 and discharges a ₁ , a _2, a ₃ are allocated as discharges of any cluster in the system (see table 1). The full set of code combinations, divided into clusters in accordance with the selected rule, is presented in Tables 1-8, and the numbers of all clusters in the binary number system form the set of elements of the field GF (2 ^f ) = GF (2 ³ ). A cluster with number zero is called basic. An analysis of the elements of the columns of the clusters shows that not always the combination of columns when they are rearranged, in accordance with the values of the IMR, leads to the formation of a complete set of elements of the GF field (2 ^kf ), which means that such a combination of columns cannot lead to one of the equivalent code samples and therefore should be replaced by another combination by iterative transformations of the nearest neighboring columns. For example, column a ₇ combined separately with columns a ₅ , a ₈ , a ₁₁ , and a ₁₅ does not provide a complete set of field elements GF (2 ^kf ) = GF (2 ² ). A sign of an unsuccessful combination of columns is the absence of elements of a unit matrix. The number of such unsuccessful combinations according to the WRI values for all columns is about 20% of the total possible number of combinations of columns. If necessary, the column at the right extreme position of the number of elements nk is replaced by the column at the first position of the number of redundant elements, and so on. As a rule, an unsuccessful combination of columns is eliminated in one iteration.

It is noticeable that the column a _{8 of} all clusters does not provide the desired result for any combination; therefore, it is advisable to discharge bit a ₈ under the parity bit of the cluster number, while the relation a ₁ ⊕ a ₂ ⊕ a ₃ = a ₈ is satisfied for all clusters. For other codes or for different numbering of clusters, a similar relationship is established by the structure of the base cluster.

Let a vector of the form

Given the property a ₁ ⊕ a ₂ ⊕ a ₃ = a ₈ V _code = V _per , i.e. the vector transmitted over the communication channel exactly corresponds to the V _code vector. Suppose that during the transmission of the vector V _Lane in the communication channel acted vector of the form errors

Receiving unit 1 receives a vector of the form V _per ⊕V _err = V _ave:

and the block for generating soft decision indices (IIR) 2 for each bit from V _pr will form integer indices (see A. Gladkikh, A. A. Gladkikh, Fundamentals of the theory of soft decoding of redundant codes in an erasing communication channel. - Ulyanovsk: UlSTU , 2010 .-- 379 p., See p. 212).

The cluster number determination unit 3 allocated symbols and indices a ₁ = 0 with index 5; and ₂ = 0 with index 3; a ₃ = 1 with index 6 and a ₈ = 0 with index 6. Hard decisions V _pr are fixed in the drive 10 code combinations and in block 6 transition to the base cluster. In block 3 of determining the cluster number, and in block 4 of checking the cluster number, the symbols of the cluster number (positions a ₁ and a ₂ , a ₃ ) are checked for parity. If the parity rule is satisfied, the decoder implements the following steps to restore the vector V, _etc. Otherwise, the cluster number is restored due to the interaction of block 3 and block 4 of the decoder using an arsenal of iterative transformations in accordance with the rule

возвращает знак своего аргумента; L(d₁) - оценка надежности символа, участвующего в формировании проверочного бита; L(d₂) - оценка надежности проверочного символа; µ - число исключенных из преобразований единичных символов при условии, что они имеют высокий показатель ИМР.where is the function

returns the sign of its argument; L (d ₁ ) - assessment of the reliability of the character involved in the formation of the check bit; L (d ₂ ) - assessment of the reliability of the verification symbol; µ is the number of single characters excluded from the transformations, provided that they have a high index of IMR.

For example, in the resulting sequence a ₁ , a ₂ , and _{3, the} symbol a ₃ = 1 with index 6 is the most reliable. The information value is a ₃ = 1, therefore µ = 1. The sequence to be corrected takes the form: -5 -3 | -6. In this sequence, the units are represented by the + sign, and the zeros by the - sign, a vertical line separates the parity symbol -6 from the characters of the cluster number.

At the first step of iterative transformations we get:

L (d ₁ ) = [- 3 + 0] | -6≈3 - the new value of the posterior estimate for the symbol is 5;

L (d ₂ ) = [- 5 + 0] | -6≈5 is the new value for the -3 symbol.

The second step of the iteration:

L (d ₁ ) = [- 3 + -5] | -6≈-2 - correction value for the -5 symbol;

L (d ₂ ) = [- 5 + 3] | -6≈2 - correction value for the +4 symbol.

The third step of the iteration:

L (d ₁ ) = [- 3 + 2] | -6≈1 - correction value for the -5 symbol;

L (d ₂ ) = [- 5-2] | -6≈6 - correction value for the +4 symbol.

The result of the transformations are the actions (-5 + 1 = -4) and (-3 + 6 = + 3). As a result, instead of a distorted sequence -5 -3 +6 | -6 get the restored character sequence -4 +3 +6 | -6. Therefore, the number of the cluster to which the combination belongs is 011 ₂ = 3 ₁₀ .

Block 5 key combinations, having received the checked value of the cluster 011 ₂ = 3 ₁₀ determines for V _pr belonging to the third cluster, the key combination of this cluster by multiplying the vector V ₃ = 01100 by the generating matrix σ. The result is a key combination

In block 6 transition to the base cluster, a combination of V _ol with the restored cluster number by bitwise addition with a combination of V _CL3 form a combination belonging to the base cluster

By ranking symbol V ₀ their descending WRI in block 6 is formed of key combinations ranked _Ranjit vector V, wherein the symbols are not considered as cluster numbers _1, a _2, a _3.

Based on the procedure for generating the V _rank in block 6 of the decoder, a permutation matrix P of dimension (nf) × (nf) is generated. In block 7 of the base cluster, by multiplying the cluster combinations (matrix) by P, a combination configuration of the form (rearranged cluster 000 ₂ = 0 ₁₀ ) is obtained:

In block 8 of linearity checking, the result of the permutation is estimated by highlighting the columns at the positions of the leftmost digits (in the example, positions a ₁₁ and a ₁₂ ) and revealing the signs of the identity matrix (inverse identity matrix). If the condition is not satisfied in blocks 6 and 7 are replaced and a ₁₃ to ₁₂ and so on up to those long as the condition does not hold an identity matrix formation. In the example, the condition is satisfied (see the bottom two lines at positions a ₁₁ and a ₁₂ ). Error separation occurs in block 9 of error isolation by comparing the vector V _rank , in which the elements a ₁₁ and a ₁₂ coincide with the elements of the second row of rearranged combinations of the zero cluster, in fact with the reference rearranged vector

.This vector is allocated from the rows of the rearranged cluster 0 ₁₀ . Comparison leads to a rearranged error vector $$V_{\mathrm{about}w}^{,}$$

.

, получая истинный вектор ошибок после обратных перестановок, выполняемых в блоке 12In the transposition matrix transposition block 11, the matrix P ^{T is} obtained from the matrix P and, taking into account the added symbols, the cluster numbers process the vector $$V_{\mathrm{about}w}^{,}\times P^T$$

getting the true error vector after the reverse permutations performed in block 12

Decoding is completed in block 13 by adding the received vector with the found error vector

The proposed decoder allows you to:

- in most cases, correct erasures, the multiplicity of which is determined by the ratio n-k;

- in comparison with analogs, it is possible to significantly reduce the processing time of code combinations in the decoder due to the exclusion from the computational process of searching for the inverse matrix for the rearranged generating matrix: the code and the subsequent formation on this basis of the matrix of the equivalent code;

- the decoder works only with the base cluster (always with a single list), without spending time processing each new received vector to compile a new list by selecting the most probable vectors.

Claims (1)

A decoder with processing the list of the base cluster, comprising a reception unit, the first output of which is connected to the first input of the cluster number determination unit through one output of the soft decision index formation unit, while the second output of the reception unit through the code combination drive is connected to the first input of the error correction unit, which differs in addition, a cluster number check block, a key combination block, a transition to the base cluster block, a base cluster block, a linearity check block, a block are transposed I am a permutation matrix, an error allocation block, a reverse permutation block, while the first output of the cluster number determination unit is connected to the input of the cluster number verification unit, and the output of this block is connected to the second input of the cluster number determination unit, the second output of which is connected to the cluster key combination to the first input of the transition block to the base cluster, the first output of this block through the base cluster block is connected to the input of the linearity checking block, while its single output through the error allocation block is connected to the first input of the reverse permutation block, while the other output of the linearity check block is connected to one input of the transposition matrix transposition block, and the output of this block is connected to the second input of the reverse permutation block and the output of this block is connected to the second input of the error correction block, while the third output of the block linearity checking is connected to the second input of the transition block to the base cluster, the second output of which is connected to another input of the transposition block of the permutation matrix, while the third input of the transition block An ode to the base cluster is connected to another output of the soft decision index formation block.

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