Coded color shift keying with frequency domain equalization for low complexity energy efficient indoor visible light communications

The adaptive tri-chromatic color shift keying (CSK) modulation standardized in IEEE 802.15.7 and the advanced quad-chromatic CSK are unable to utilize their entire spectral efficiency range over dispersive indoor VLC channels and incur large power penalties without the use of channel equalization and forward error correction. This degrades the energy efficiency and limits the throughput capability of CSK schemes to approximately half of the data-rates specified in the IEEE standard for multimedia services in wireless personal area networks. To comply with the desire for low latency and minimal implementation complexity in the CSK standardization framework, we consider an industry standard binary convolutional code and frequency domain equalization (FDE) which provide one-shot data packet processing. Our results show that when operating over hybrid indoor visible light communication (VLC) links, the FDE based rate-adaptive coded modulation CSK scheme achieves a significant 11 dB SNR gain over an uncoded, unequalized system.