Performance evaluation of space time coding techniques for indoor visible light communication systems

In this paper, the performance of visible light communication (VLC) systems, employing Space Time Block Coding (STBC) and Repetition Coding (RC) techniques for an indoor environment is investigated and analyzed. The indoor channel impulse response is taken into account assuming line-of-sight (LOS) and Non-LOS (NLOS) scenarios. The proposed systems employ multiple transmit light emitting diodes (LEDs) with one and two photodetectors (PDs). Various physical arrangements and placements of the LEDs and PD within the indoor scenario are considered. Simulation results show that, for a specific LEDs and PDs arrangement, RC techniques outperform the respective STBC techniques. Furthermore, a 2×2 multiple-input multiple-output (MIMO) VLC system implementing Alamouti STBC is investigated and compared with the RC scheme using a single receiver. It is shown that adding another PD can achieve a signal-to-noise ratio (SNR) improvement of about 5 dB and 2 dB over the Alamouti and RC schemes with a single PD, respectively.