Performance Investigation of OCT Precoding for MIMO-OFDM Based Indoor Visible Light Communications

In this paper, we propose a MIMO-OFDM indoor VLC system with orthogonal circulant matrix transform (OCT) precoding and angular receivers to significantly improve the achievable aggregate capacity of equivalent parallel channels. Compared with the conventional MIMO-OFDM based VLC systems, the data streams of LED transmitters in our proposed system are linearly pre-processed with the OCT precoding scheme and can be recovered by corresponding linear OCT decoding at receiver. Numerical results show that with 50-MHz modulation bandwidth, the BER performance can be improved to similar to 10(-3) by the receiver module with angular diversity. With the help of OCT precoding, the BER can be further improved to similar to 10(-5) for both center and off-center indoor coverage.