Multi-Layer Superimposed PAPR Reduction for ACO-OFDM VLC Systems

Abstract

Light emitting diode (LED) is employed to transmit signals for visible light communication (VLC) systems. Asymmetrically clipped optical-orthogonal frequency division multiplexing (ACO-OFDM) is one of multi-carrier modulations to improve data rates. However, ACO-OFDM signals provide high peak-to-average power ratio (PAPR), and are clipped off to work in a nonlinear LED with a limited range of linearity. In this paper, a non-redundant multi-layer superimposed PAPR reduction approach is proposed for ACO-OFDM VLC systems, where two non-redundant signal streams are superimposed with the ACO-OFDM signal stream for PAPR reduction, requiring no pilot and no side information. A number of multi-layer signals are designed to reduce large-amplitude source signals and enhance small-amplitude source signals. The source signals are not interfered by the designed multi-layer signal streams in frequency domain, as odd subcarriers are occupied by source signals, while even subcarriers are occupied by the designed signals. Simulation results show that the proposed approach outperforms a number of existing methods in the literature, and provides performance better than ACO-OFDM with no PAPR reduction, in terms of bit error rate (BER) and complementary cumulative distribution function (CCDF) of PAPR reduction.