A low-power termination criterion for iterative LDPC code decoders

This paper introduces a novel criterion for the termination of iterations in iterative LDPC Code decoders. The proposed criterion is amenable for VLSI implementation, and it is here shown that it can enhance previously reported LDPC code decoder architectures substantially, by reducing the corresponding power dissipation. The concept of the proposed criterion is the detection of cycles in the sequences of soft words. The soft-word cycles occur in some cases of low signal-to-noise ratios and indicate that the decoder is unable to decide on a codeword, which in turn results in unnecessary power consumption due to iterations that do not improve the bit error rate. The proposed architecture terminates the decoding process when a soft-word cycle occurs, allowing for substantial power savings at a minimal performance penalty. The proposed criterion is applied to hardware-sharing and parallel decoder architectures.