Adaptive STBC MIMO-OFDM system design for indoor visible light communications

An adaptive multiple-input multiple-output orthogonal frequency division multiplexing (MIMOOFDM) visible light communication(VLC) system based on space-time block coding (STBC) modulation was proposed in the paper, which can overcome the MIMO channel correlation and achieve reliable communications. Meanwhile, power-and-bit allocation(PBA) was combined with OFDM in order to adapt to the channel and improve the spectral efficiency. Then a 22 MIMO-OFDM VLC transmission over a distance of 80 cm was demonstrated, where the measured bit error rates were all below 7% of the pre-forward-error-correction threshold of 3.810-3. Experimental results show that the STBC MIMO-OFDM system is robust to MIMO channel correlation, where the data rates can be greatly improved by applying the PBA.