Achieving FEC and RLL for VLC: A Concatenated Convolutional-Miller Coding Mechanism

Run-length limited (RLL) codes are widely used in visible light communications to avoid long runs of 1s and 0s that potentially cause the flicker. This letter explores the serial concatenation of convolutional codes and Miller codes to simultaneously achieve forward error correction and RLL control. Miller codes with high bandwidth efficiency are much ignored in practice due to their disappointing power efficiency. The novelty of this letter is that we identity the merit of this previously unfavorable RLL code (i.e., trellis structure and soft decidability), exploit some important coding principles (i.e., interleaved serial concatenation and soft-iterative decoding), and assemble it to a powerful turbo structure that makes it outperform the existing favorable choices. A modified Bahl-Cocke-Jelinek-Raviv decoding algorithm is developed for the proposed concatenation. Analysis and simulations confirm that the new system is capable of solid RLL control and a superb performance better than the existing schemes.