Channel Estimation for DCO-OFDM Based VLC Systems in the Presence of Clipping Noise

Abstract

Visible Light Communication(VLC) has been considered as a potential access option for 6G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In VLC system, illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC-Biased optical DCO-OFDM with clipping has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require estimating and tracking the fading channel in order to detect transmitted data coherently. In this work, we propose a pilot-aided iterative channel estimation algorithm to efficiently estimate the optical channel coefficients of a clipped DCO-OFDM system operating with additive white Gaussian noise (AWGN). The estimation algorithm is capable of improving the channel estimation by making use of pilot symbols with interpolation or using the channel estimate of previous OFDM block to obtain the next estimate for the iterative algorithm. In each iteration, the clipping noise is estimated and compensated in the frequency domain. Simulation results verify that the proposed channel estimation algorithm reduces the bit error rate (BER) and mean-square error (MSE) of channel estimate can be significantly.