Early detection for decoding LDPC codes

Abstract

The sum-product algorithm used for decoding LDPC codes has an excellent BER performance at the cost of computationally heavy operations. In this paper, we show that early detection methods which are used to reduce the computational complexity of a variety of iterative decoders (especially in turbo decoders) perform well with LDPC codes and present a modified sum-product algorithm with early detection for decoding LDPC codes. Sum-product algorithm performs iterative decoding for each codeword within a predetermined number of iterations. Using a reliability metric, information symbols with high reliability are detected early in each decoding iterations during decoding, and the computational complexity of the sum-product algorithm is reduced as the ratio of early detected information symbols in the codeword is increased.