A Novel Optimal Precoder and Equalizer in 2\times 2 MIMO VLC Systems for Vehicular Application

Precoding is a technique which exploits transmission diversity by weighting the information stream, i.e. the transmitter sends the coded information to the receiver to achieve pre-knowledge of the channel. Visible light communication (VLC) channels inherently exhibit frequency-selective and multi-path fading effects that result in intersymbol interference (ISI) and thus reduces the data rate. To this end, optical multiple input multiple output (MIMO) can provide spatial diversity and thus achieve a high data rate. Inspired by these facts, we investigate different precoding and equalization schemes for 2 \times 2 MIMO for the vehicle to vehicle (V2V-VLC) system. In this work, we consider three detection schemes, Zero Forcing (ZF), Maximum likelihood (ML), and Minimum Mean Squared Error (MMSE). Also, we consider flickering/dimming control and the nature of outdoor VLC channel as a frequency selective channel. Moreover, we investigate a transceiver considering perfect CSI based on different detection algorithms. Simulation results of the investigated transceiver demonstrate improvements in Bit Error Rate (BER) and Mean Squared Error (MSE) for the MMSE scheme.