Soft Convolutional Codes Decoding Algorithm for Concatenated Codes in Visible Light Communication

摘要

In this paper, we propose a new decoding algorithm for soft convolutional codes and concatenated codes in visible light communication (VLC) systems. RLL codes are used to control the dimming in VLC since each codeword has same 1s and 0s, hard RLL decoding and soft RLL decoding are available now. Hard convolutional decoding can be easily combined with RLL decoding based on Viterbi algorithm, however, efficient soft output convolutional decoding combined with RLL codes is worth considering. In our algorithm, the convolutional codes are conjugated to Reed-Solomon (RS) codes and RLL codes, which make use of soft information from the channel to provide coding gain. A modified Bahl, Cocke, Jelinek and Raviv algorithm is proposed to enhance convolutional decoding with the soft RLL decoder to produce soft input for RS decoder. Simulation results show that the bit error rate performance of our proposed algorithm is better than referenced algorithm.