Code design for run-length control in visible light communication

Run-length limited (RLL) codes can facilitate reliable data transmission and provide flicker-free illumination in visible light communication (VLC) systems. We propose novel high-rate RLL codes, which can improve error performance and mitigate flicker. Two RLL coding schemes are developed by designing the finite-state machine to further enhance the coding gain by improving the minimum Hamming distance and using the state-splitting method to realize small state numbers. In our RLL code design, the construction of the codeword set is critical. This codeword set is designed considering the set-partitioning algorithm criterion. The flicker control and minimum Hamming distance of the various proposed RLL codes are described in detail, and the flicker performances of different codes are compared based on histograms. Simulations are conducted to evaluate the proposed RLL codes in on-off keying modulation VLC systems. Simulation results demonstrate that the proposed RLL codes achieve superior error performance to the existing RLL codes.