Code Design in Visible Light Communications Using Color-Shift-Keying Constellations

The IEEE 802.15.7 standard on visible light communications (VLC) proposes color-shift-keying (CSK) as a way to increase data rate while keeping a constant optical power. In this paper, we propose two algorithms to design codes by finite state machines (FSM) using newly introduced CSK constellations. These codes ensure a constant perceived color eliminating the use of the scrambler proposed by the standard. Furthermore, they achieve about 1 to 3 dB of coding gain compared with the standard constellations and are optimally and efficiently softdecision decodable using the Viterbi algorithm.