Visible light communication (VLC) can provide short-range optical wireless communication, together with illumination using light-emitting diode (LED) lightings. Since conventional forward error correction (FEC) codes cannot provide two lighting related features, dimming support, and flicker mitigation, the existing coding schemes for reliable VLC usually rely on auxiliary coding techniques, which cause a complicated structure and a low transmission efficiency. In this paper, based on polar codes, an efficient and flicker-free FEC coding scheme for dimmable VLC is proposed to increase the transmission efficiency and simplify the coding structure. Taking advantage of polar codes’ recursive encoding structure, the proposed scheme can guarantee the equal probability and the short runs of 1 s and 0 s for arbitrary code rate without extra coding components. Numerical results show that the proposed scheme can have twice higher transmission efficiency than the existing schemes. Furthermore, at a dimming ratio of @math or @math , the coding gain of the proposed scheme is about 4.6 dB and 1.4 dB higher than that of the Reed–Solomon (RS) codes based scheme and the low-density parity check code based scheme, respectively.
@cite_0: 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.
The similar problems also exist in the joint FEC-RLL coding mechanism proposed by Lu and Li trying to simultaneously achieve bandwidth efficiency, error correction and run-length control @cite_0 . The concatenated convolutional-Miller coding scheme consists of an OOK modulated Miller code serving as the inner code and a convolutional code serving as the outer code. Unfortunately, Miller codes have disappointing power efficiency and bit error rate (BER) performance, which cannot be ignored in practice.