Generalised Spatial Carrierless Amplitude and Phase Modulation in Visible Light Communication

Abstract

Generalised spatial carrierless amplitude and phase modulation (GS-CAP) is developed in this paper to improve the spectral efficiency of the conventional CAP in indoor visible light communication. The proposed GS-CAP preserves the attractive low complexity transceiver of CAP by exploiting the spatial domain for performance improvement. Bit error rate (BER) analysis is derived for the performance evaluation of the proposed GS-CAP and is shown to be in excellent agreement with the simulation results. The impact of different system parameters, such as the number of active light emitting diodes (LEDs) and the number of receiving photodiodes (PDs), on the performance of GS-CAP are investigated. In addition, a precoding technique is developed for improving the BER performance of GS-CAP when the channel gains are similar. Finally, it is found that for different GS-CAP system configurations with the same spectral efficiency, the configuration with the smallest number of active LEDs results in optimum power efficiency and BER performance.