US Patent 7453960 LDPC encoder and encoder and method thereof

A decoder for decoding low-density parity-check codes comprises a first calculator to calculate LLrRml, for each parity check equation, at iteration i−1. A detector detects LLrRml, at iteration i, in response to the first calculator. A second calculator calculates LLrQLm, for each parity check equation, at iteration i in response to the detector. LLrQLm represents information from bit node l to equation node m, one for each connection. LLrRml represents information from equation node m to bit node l, one for each connection. The first calculator is responsive to the second calculator.