Spectrally Efficient Enhanced PAM-OFDM Based on RF Wireless Communication System

An efficient modulation scheme called enhanced pulse amplitude modulation based orthogonal frequency division multiplexing (ePAM-OFDM) is proposed in this paper. It has been proved that clipping and simple reordering, the half-length of the PAM-OFDM time domain signal is enough to carry all the information. This idea allows for increasing spectral efficiency (SE) by (100%) when compared with PAM-OFDM and quadrature amplitude modulated biased OFDM (QAM-OFDM) for the same modulation order. Moreover, the proposed scheme has an improved energy efficiency compared to spectrally equivalent PAM-OFDM, and it reduces the transmitted energy by half compared to QAM-OFDM when the comparison is set at the same spectral efficiency. Hence, ePAM-OFDM can relatively close the gap in performance between PAM-OFDM and QAM-OFDM scheme. The comparisons of these schemes are explored by theoretical analysis and computer simulations over additive white Gaussian noise AWGN and Rayleigh fading channels.