On performance analysis of LS and MMSE for channel estimation in VLC systems

Channel estimation is a key feature for wireless optical communication systems. This paper presents an evaluation of channel estimation techniques for indoor visible light communication (VLC) systems using a direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) scheme. The VLC system can simultaneously provide illumination and wireless communication at a high data rate. However, the coverage area is limited and the distance is about 3 m. In this paper, performance analysis of two channel estimation methods is presented, one using the least squares (LS) algorithm and the other the minimum mean square error (MMSE) algorithm, to estimate channel response by applying them to various M-QAM modulations. The performance of these two methods is compared by mathematical analysis and by simulation by measuring bit error rate (BER) and mean square error (MSE) versus signal-to-noise ratio (SNR). The results shown that, at higher SNR, the MMSE algorithm outperforms the LS for both BER and MSE.