Design of a Cyclic Shifted LACO-OFDM for Optical Wireless Communication

Abstract

This paper proposes a cyclic shifted layer asymmetrically clipped optical orthogonal frequency division multiplexing system (CS-LACO-OFDM) for optical wireless communications. The transmitted signal in CS-LACO-OFDM is generated by combining the signal of the first layer and signals of the remaining L-1 layers with cyclic shift equivalents, where L is the number of the CS-LACO-OFDM layers. In particular, the sets of cyclic shift value in CS-LACO-OFDM are modulated on the odd subcarriers of the first layer with complex-valued symbols. Information on cyclic shift sets can be easily detected with the help of modulated symbols conveyed in the first layer without increasing the receiver complexity. Simulation results show that the CS-LACO-OFDM has a similar peak-to-average power ratio performance as LACO-OFDM with separate selective mapping scheme when the number of candidate signals is the same but at remarkably low computational complexity. Furthermore, the average bit error rate of CS-LACO-OFDM over all layers is minimized by the proposed optimal optical power allocation. INDEX TERMS Hybrid modulation, peak-to-average power ratio, cyclic shift, visible light communication, layer asymmetrically-clipped optical orthogonal frequency division multiplexing.