Multiple LDPC decoder of very low bit-error rate

Abstract

The error correcting capability of LDPC based systems at low noise levels is often dominated by the so-called error floor, a region in the BER vs. noise level plot, where BER reduction slows down as the noise level decreases. The error floor behavior is commonly attributed to the sub-optimality of iterative decoding algorithms on graphs with cycles, which become trapped to local minimum solutions. Trapping of the decoder depends on several factors, including the decoding algorithm. A particular received word that is not decoded by a certain algorithm may be decoded successfully by a different algorithm. The proposed Multiple Decoder exploits this diverse behavior, by decoding a particular received word with N different algorithms, composing an LDPC decoder that achieves very low BER in the error floor region of operation, less iterations and higher throughput than the equivalent single decoder system.