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

This paper presents a new color shift keying (CSK) modulation format for wireless visible light communication (VLC), based on four colors instead of the three colors used in the existing IEEE 802.15.7 CSK physical layer standard. The new four color system uses a novel intensity modulation and direct detection approach to realize a four-dimensional signaling scheme that uses the available color and signal spaces efficiently. The bit error rate evaluation of both the existing and proposed system shows that the new four color scheme achieves a significant 4.4-dB electrical SNR gain over the three color scheme for an additive white Gaussian noise 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 color CSK scheme is more power efficient and reliable than the three color scheme for a particular amount of delay spread that the optical wireless channel may have.