Performance comparison of VLC MIMO techniques considering indoor illuminance with inclined LEDs

Abstract

Visible light communication (VLC) is a promising complementary technology to radio frequency (RF) communication. In existing VLC multiple-input multiple-output (MIMO) system, light emitting diodes (LEDs) vertical MIMO (LVM) model is commonly used. However, in LVM model, illuminance distribution is not uniform enough for office and the optical channel is highly correlated, which degrade the system performance, especially in cases with small emitter separation. In this paper, LEDs inclined MIMO (LIM) model is proposed and the performance comparison of LIM and LVM model assuming line-of-sight (LOS) channel characteristics is presented. Theoretical analysis and simulation results show that LIM model outperforms LVM model in many respects. Firstly, LIM model provides more uniform office illuminance distribution than LVM model. In addition, LIM model with spatial modulation (SM) or spatial multiplexing (SMP) can achieve better bit error ratio (BER) performance when the receiver is in the center, especially with higher signal-to-noise ratio (SNR), because the inclined LEDs can reduce the MIMO channel correlation, which compensates the loss of received power. Besides, when the receiver is on the edge, LIM model with RC, SMP or SM all performs better than LVM model since more power is received and the channel correlation is lower. Furthermore, LIM model outperforms LVM model when considering receiver mobility since LIM model can provide a larger reliable communication area on the receiver plane.