Spectrally efficient revised PAM-DMT for IM/DD Optical Wireless Communication systems

Abstract The incessant demand for higher data rates has made Visible Light Communication (VLC) technology to gain enormous prevalence in contemporary communication systems. These VLC systems are lagging in terms of spectral efficiency due to the inevitable Hermitian symmetry imposed to satisfy the unipolar constraint of those systems. Therefore, in this work, a new waveform named revised Pulse Amplitude Modulated Discrete Multitone (rPAM-DMT) that provides more spectral efficiency by utilizing all subcarriers without Hermitian symmetry is pioneered for VLC systems. The generation of rPAM-DMT at transmitter and detection at the receiver are analytically explained. Simulation results for Bit Error Rate (BER) show that as spectral efficiency increases rPAM-DMT outperform PAM-DMT and Asymmetrically Clipped Optical OFDM (ACO-OFDM) under Additive White Gaussian Noise (AWGN) channel. Further, the proposed waveform is validated on a VLC testbed designed with Universal Software-defined Radio Peripheral (USRP) hardware, which is controlled by using Lab-view software.