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_7: In this letter, we propose an adaptive forward error correction scheme based on low-density parity-check (LDPC) codes to efficiently adjust dimming values in visible light communication (VLC) systems. The proposed code is a quasi-cyclic LDPC code, in which extension and puncturing methods are used to maintain dimming control. The significant advantages of the proposed method are due to the lower number of codes required to support codes with different coding rate and the relatively small performance degradation for dimming control. Simulation results show that our proposed method efficiently maintains the dimming control in VLC systems with LDPC codes.
The other one is an LDPC codes-based scheme proposed by Kim to adaptively adjust dimming values in VLC systems @cite_7 . As shown in Figure , its dimming function is also provided via puncturing methods and CSs, and RLL codes are used to avoid long runs. The significant advantages of the method include the lower number of codes required to support codes with different coding rate and the relatively small performance degradation for dimming control. Nevertheless, with the rate-1 2 LDPC codes, the effect of the puncturing rate and the rate-1 2 Manchester line codes, the overall code rate could be very low. For example, a 3-bit message will be encoded into a 15-bit codeword using the LDPC-based scheme. Furthermore, these two schemes require iterative decoding algorithm, which increases the computational cost and latency.