Modified Low-Complexity Chase Soft-Decision Decoder of Reed-Solomon Codes

Reed-Solomon (RS) codes are widely used as error-correcting codes in digital communication and storage systems. Algebraic soft-decision decoding (ASD) of RS codes can achieve substantial coding gain with polynomial complexity. Among practical ASD algorithms, the low-complexity chase (LCC) algorithm that tests 2(eta) vectors can achieve similar or higher coding gain with lower complexity. For applications such as magnetic recording, the performance of the LCC decoding is degraded by the inter-symbol interference from the channel. Improving the performance of the LCC decoding requires larger eta, which leads to higher complexity. In this paper, a modified LCC (MLCC) decoding is proposed by adding erasures to the test vectors. With the same eta, the proposed algorithm can achieve much better performance than the original LCC decoding. One major step of the LCC and MLCC decoding is the interpolation. To reduce the complexity of the interpolation, this paper also proposed a prioritized interpolation scheme to test a small proportion of the vectors at a time, starting with the ones with higher reliabilities. For a (458, 410) RS code, by testing 1/8 of the vectors at a time, the area requirement of the MLCC decoder with eta = 8 can be reduced to 57%, and the average decoding latency is reduced to 73%.