Soft-Decision Viterbi Decoding Scheme and a New Reliability Metric for 4/6 Modulation Code in Holographic Data Storage

摘要

A soft-decision Viterbi decoding for a 4/6 modulation code is proposed in a holographic data storage system. Since the previous proposed soft-decision Viterbi decoding does not support a higher rate modulation codes than 1/2 rate modulation codes, we propose a new reliability metric to support the 4/6 modulation code. The reliability metric is used to calculate the branch metric on the trellis. For a better coding gain, we find a symbol mapping method for the modulation code which provides a large free distance on the trellis to have the enhanced error correcting capability. Simulation results show that the proposed scheme has about 2 dB coding gains than the conventional soft-decision Viterbi decoding scheme.