Reduced decoding time of LDPC code using convolutional code with Vitrebi decoding in Underwater Communication

Low Density Parity Check code is the more efficient technique to attain the minimal error rate in the underwater channel. To reduce the processing delay in the LDPC decoding, convolutional code with high code rate is used. The result showed that the BER of 10-4 can be obtained with Eb/No value of 20 for code rate of ½ and 12 for code rate of 1/8. It is also showed in result that the decoding time is reduced one-third for data size of 500 and one-tenth for the data size of 1500 bits.

A decoding method of an n length binary BCH code through (n + 1)n length binary cyclic code

For a given binary BCH code Cn of length n = 2 s - 1 generated by a polynomial of degree r there is no binary BCH code of length (n + 1)n generated by a generalized polynomial of degree 2r. However, it does exist a binary cyclic code C (n+1)n of length (n + 1)n such that the binary BCH code Cn is embedded in C (n+1)n . Accordingly a high code rate is attained through a binary cyclic code C (n+1)n for a binary BCH code Cn . Furthermore, an algorithm proposed facilitates in a decoding of a binary BCH code Cn through the decoding of a binary cyclic code C (n+1)n , while the codes Cn and C (n+1)n have the same minimum hamming distance.