A BIPCM Scheme Based on OCT Precoding for a 256-QAM OFDM-VLC System

A bit-interleaved polar-coded modulation (BIPCM) scheme based on orthogonal circulant matrix transform (OCT) precoding is proposed and experimentally demonstrated in an orthogonal frequency-division multiplexing (OFDM) visible light communication system. It exhibits the advantages of high reliability, low latency, and low computational complexity. To overcome the fading effect on a mapped bit-level, the scheme employs the Monte Carlo method to jointly design a polar code concatenated with 256-ary quadrature-amplitude modulation. In addition, OCT precoding is used to mitigate the frequency selective fading effect across OFDM subcarriers. The experimental results show that the system can achieve a net data rate of 343 Mb/s over 80-cm free-space transmission with a bit error rate below $1\times 10^{-3}$ . At the receiver, it is the number of complex multiplications is reduced by 33% in comparison with BIPCM using an optimized quadratic polynomial permutation interleaver.