Low-PAPR Superimposed Layered ACO-OFDM for VLC Systems

This paper proposes a peak-to-average power ratio (PAPR) reduction scheme for the layered asymmetrically clipped optical orthogonal frequency division multiplexing (LACO-OFDM) through the superimposition of a specially designed periodic signal to generate the superimposed LACO-OFDM (SLACO-OFDM) signal. The sequence of each LACO-OFDM symbol is divided into several groups, and the amplitude of the periodic signal is designed based on the difference between the maximum values in each group and the maximum value of the entire symbol. The period of the periodic signal is selected to ensure that its FFT falls onto the unused subcarriers of the LACO-OFDM signals. Thus, the PAPR of SLACO-OFDM is improved after the superposition without introducing any additional interference. The proposed SLACO-OFDM signal can be directly processed by the successive interference cancellation of a standard LACO-OFDM receiver. Simulation results indicate that the proposed scheme attains a better PAPR reduction performance than the original and discrete Hartley transform based LACO-OFDM.