Comparison of constructions of irregular Gallager codes

Regular and Irregular Gallager - type Error - Correcting Codes

The performance of regular and irregular Gallager-type errorcorrecting code is investigated via methods of statistical physics. The transmitted codeword comprises products of the original message bits selected by two randomly-constructed sparse matrices; the number of non-zero row/column elements in these matrices constitutes a family of codes. We show that Shannon's channel capacity may be sat...

Optimized irregular Gallager codes for OFDM transmission

We present an optimized channel coding scheme for OFDM transmitter. Traditional coding methods use regular codes, in the sense that each bit participates in the same way to the channel encoding. Our approach consists in using a priory assumption on the channel available at the transmitter in order to optimize the coding scheme. We have considered the irregular Gallager block codes in our study....

Gallager codes for CDMA applications .I. Generalizations, constructions, and performance bounds

We focus on applications of low-rate Gallager (low-density parity-check) codes in code-division multiple-access schemes. The codes that we present here achieve good performance with relatively short frame-lengths in additive white Gaussian noise channels and, perhaps more importantly, in fading channels. These codes can be decoded with low complexity by using iterative decoding procedures. We p...

Regular and Irregular Gallager-zype Error-Correcting Codes

The Origin of Ldpc Codes

42 JANUARY 2004 1053-5888/04/$20.00©2004IEEE e consider the problem of designing unoriented bipartite graphs with large girth. These graphs are the Tanner graphs associated with the parity-check matrix H of low density parity-check (LDPC) codes or Gallager codes. Larger girth improves the computational and bit error rate (BER) performance of these codes. The article overviews several existing m...