Sparse Channel Estimation with Clipping Noise in DCO-OFDM Based VLC Systems

Abstract

In this paper a new computationally efficient and high performance channel estimation algorithm is proposed for DC-biased optical OFDM (DCO-OFDM) systems in indoor visible light communications (VLC) in the presence of a clipping noise. The sparse structure of the channel is taken into consideration in the channel estimation algorithm. The algorithm has an iterative structure and aims at reducing the effect of the clipping noise, inevitably generated by the DCO-OFDM systems. In te algorithm, the clipping noise is estimated in the time-domain and compensated for its effect in the frequency-domain. The initial values of the channel, including sparse channel path gains and the path delays, are determined by the least-squares (LS) and the ESPRIT algorithms, respectively, by making use of the pilots. Computer simulations indicate that the proposed algorithm converge in 3 iterations at most and yields excellent bit error rate (BER) and mean-square error (MSE) performances for DC-biased optical OFDM (DCO-OFDM) based systems.