Indoor gigabit 2×2 imaging multiple-input–multiple-output visible light communication

We propose and experimentally demonstrate a 2 x 2 imaging multiple-input-multiple-output （MIMO） Ny quist single carrier visible light communication （VLC） system based on spectral efficient 64/32-ary quadrature amplitude modulation, as well as pre- and post-equalizations. Two commercially available red-green- blue light-emitting diodes （LEDs） with 3 dB bandwidth of I0 MHz and two avalanche photodiodes with 3 dB bandwidth of i00 MHz are employed. Due to the limited experiment condition, three different colors/ wavelengths are transmitted separately. The achieved data rates of red, green, and blue LED chips are 1.5 , 1.25, and 1.25 Gb/s, respectively. The resulting bit error ratios are below the 7% pre-forward error correction limit of 3.8 × 10-3 after 75 cm indoor transmission. To the best of our knowledge, this is the first experimental investigation of imaging MIMO system, and it is the highest data rate ever achieved in MIMO VLC system.