LDPC code inspection matrix generation method

A technology for checking matrix and decoder, which is applied in the direction of error detection coding, check code calculation, coding and other directions applying multiple parity bits, and can solve problems such as unstable characteristics

Inactive Publication Date: 2009-09-09
MITSUBISHI ELECTRIC CORP
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Problems solved by technology

[0029] For this reason, the inspection matrix obtained from the above-mentioned maximum value of "rate" becomes fluid, and there is a problem of unstable characteristics
Moreover, because the derivation of the order assignment of the variable nodes and the derivation of the order assignment of the check nodes are repeated within a predetermined number of times, the traditional LDPC code check matrix generation method still has the problem of requiring a certain amount of time for search processing.

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Embodiment 1

[0058] Before explaining the method for generating the check matrix for LDPC codes of this embodiment, it is possible to determine the position of the encoder in the method for generating a check matrix for LDPC codes of this embodiment and the conventional method for generating a check matrix for "Irregular-LDPC codes" Be explained. Furthermore, the structure of the LDPC encoding / decoding system is the same as that described above Figure 13 same.

[0059] In the encoder 101 on the transmission side, an inspection matrix H is generated by the LDPC code inspection matrix generation method of this embodiment described later. Then, the generator matrix G is obtained based on the following conditions.

[0060] G: k×n matrix (k: information length, n: code word length)

[0061] GH T =0(T is transpose matrix)

[0062] Thereafter, in the encoder 101, a message (m 1 m 2 ...m k ), using the generator matrix G above to generate the codeword C.

[0063] C=(m 1 m 2 ...m k )G ...

Embodiment 2

[0101] In Embodiment 2, the Euclidean geometric code is used according to the above-mentioned Embodiment 1, and the arrangement of value 1 in one row or one column is divided to generate a check matrix of "Irregular-LDPC code".

[0102] First, the ensemble of generating functions λ(x) and generating functions ρ(x) is derived by the check matrix generating method using the LDPC code in Embodiment 1. figure 2 Indicates the totality of generating functions λ(x) and generating functions ρ(x) when rate=0.5. Again, σ GA Indicates the noise dispersion value at the "threshold" derived from the Gaussian approximation, SNR norm (GA) represents the difference between the SNR of the "threshold" derived by the Gaussian approximation and the SNR of the Shannon limit, x represents the weight, λ x and ρ x Represents the weight distribution of variable nodes and check nodes, respectively.

[0103] In addition, it is assumed that the Euclidean geometric code used as a reference is EG(2, 2 ...

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Abstract

The check matrix generation method for LDPC codes of the present invention analyzes the "Sum-Product Algorithm" of LDPC codes by assuming that the log-likelihood ratio of the input and output data in the decoder can be approximated to a Gaussian distribution, and obtains the error that becomes zero. SNR threshold (threshold), by using a linear programming method to search for the optimal population of the weight of the row and the weight of the column, so that the Gaussian noise becomes the maximum when the encoding rate is fixed, and the check matrix for the LDPC code is generated according to the population .

Description

technical field [0001] The invention relates to a method for generating a check matrix for an LDPC code in an encoder using an LDPC (Low-Density Parity-Check code) code as an error correction code. Background technique [0002] Figure 13 is a diagram representing an LDPC encoding / decoding system. Figure 13 Middle: 101 is an encoder, 102 is a modulator, 103 is a communication path, 104 is a demodulator, and 105 is a decoder. Here, before explaining the conventional check matrix generation method for LDPC codes, the flow of encoding and decoding when LDPC codes are used will be described. [0003] First, an inspection matrix H is generated in the encoder 101 on the transmitting side by a predetermined method described later. Then, the generator matrix G is solved based on the following conditions. [0004] G: k×n matrix (k: information length, n: code word length) [0005] GH T = 0 (T is the transpose matrix) [0006] Thereafter, in the encoder 101, a message (m 1 m 2...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03M13/19H04L1/00G06F11/10H03M13/11H03M13/25
CPCH03M13/1148H03M13/1177H03M13/1151H03M13/033
Inventor 松本涉
Owner MITSUBISHI ELECTRIC CORP
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