An Enhanced Colour Shift Keying Modulation Scheme for High Speed Wireless Visible Light Communications

This paper presents a new colour shift keying (CSK) modulation format for wireless visible light communication (VLC), based on four colours instead of the three colours used in the existing IEEE 802.15.7 CSK physical layer standard. The new four colour system uses a novel intensity modulation and direct detection approach to realise a four-dimensional signalling scheme which uses the available colour and signal spaces efficiently. The bit error rate evaluation of both the existing and proposed system shows that the new four colour scheme achieves a significant 4.4 dB electrical SNR gain over the three colour scheme for an AWGN channel. The performance of existing and proposed CSK systems is examined over a range of dispersive optical wireless channels including the channel crosstalk and insertion losses, which reveals that the four colour CSK scheme is more power efficient and reliable than the three colour scheme for a particular amount of delay spread that the optical wireless channel may have.