Effect of multipath reflection on BER performance of indoor MIMO-VLC system

In the present work, the bit error rate (BER) performance due to multipath reflections, namely, line-of-sight (LOS), LOS plus first reflection (L-R1), LOS with first and second reflection (L-R1–R2) for the indoor MIMO-VLC system has been analysed. In the simulation, two cases have been considered. In case 1, the separation between receivers has been increased from 10 to 20 cm whereas, in case 2, the separation between LEDs has been changed from 0.2 to 0.6 m in the interval of 0.2 m. For case 1, it has been found that there is a significant effect on BER performance for higher order reflection than LOS and lower order reflection when the spatial separation between receivers is increased and hence higher order reflection should not be ignored. We have investigated impulse response, root-mean square delay, BER and bit rate performance for case 2 and it has been observed that the spatial separation between LEDs improves BER but reduces coherence bandwidth of the channel. If the coherence bandwidth becomes less than the signal bandwidth then it may result in signal distortion thereby causing inter-symbol interference. Hence, the optimal spatial separation between LEDs should be chosen for the MIMO-VLC system.