Joint error-brightness control coding for LED based VLC link

We propose the use of constant weight codes to jointly solve the problems of brightness control, data transmission and error correction coding for flicker free Visible Light Communication (VLC) link consisting of white LEDs. This work is unique in that a coding scheme is proposed to address the three problems collectively in single block coding scheme. In addition, recursive as well as iterative algorithms are presented to readily generate the proposed optimal constant weight binary codes with combinatorial code parameters. Instead of using the conventional heuristics or exhaustive search based methods the presented algorithm constructs codewords using an exact approach based on digit place values, making it is easier for hardware implementation. Optimality of the proposed block codes is proved analytically and their key properties are outlined. In addition, we show that the code parameters such as code length, code weight and minimum hamming distance are nicely mapped to the Pascal triangle.