Performance improvement of the pre-coded multi-user MIMO indoor visible light communication system

Visible light communication has aroused many research interests in recent years. Given the limited modulation bandwidth of LED, multiple input and multiple output (MIMO) technology appears attractive in VLC systems as multiple LED sources are typically employed in indoor environment to supply sufficient illuminance. For a practical indoor system, there generally exist multiple decentralized user terminals, which composed a multi-user (MU) MIMO VLC system together with multiple LED sources. The main difficulty for the MU-MIMO indoor VLC system is the separation of received data for different user terminal, i.e., multi-user interference (MUI). We have recently proposed an asymmetric system configuration to eliminate MUI in indoor VLC systems. By pre-processing the transmitted data in transmitter, the complexity of user terminals belonging to the proposed system is significantly reduced, leading to the reduction of power consumption. In this paper, a novel multidirectional optical receiver with different field of view (FOV) is proposed to improve the performance of the proposed system. Simulation results show that BER and SNR performances of the system are significantly improved and the majority of indoor region can achieve 100 Mbit/s at a BER of 10^-6 when single LED chip´s power is ~10 mW.