A Tunable Energy Signal for Intensity Modulation and Direct Detection Systems: Theory, Simulations, and Experiments

In this paper, we propose a novel method to generate real signal for Visible Light Communication (VLC) systems without using traditional hermitian symmetry on the data symbols obtained using M-ary Pulse Amplitude Modulation (PAM) which is named as Auxiliary PAM (Ax-PAM). We mathematically analyse this method to generate a real signal with tunable energy using auxiliary symbols at the transmitter and the corresponding receiver. Simulation results for Bit Error Rate (BER) show better performance over conventional PAM Discrete Multi-Tone (PAM-DMT) and Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM) even under clipping distortion and also demonstrate the tunable energy for the proposed scheme. Furthermore, the proposed scheme is implemented on a VLC test bed designed using Universal Software defined Radio Peripheral (USRP). The experimental results for estimated Signal to Noise Ratio (SNR) and achieved BER for Ax-PAM outperforms PAM-DMT and ACO-OFDM.