Channel-Adapted Spatial Modulation for Massive MIMO Visible Light Communications

Massive multi-input multi-output (MIMO) has great potential to improve transmission rate of visible light communication (VLC) systems. However, high inter-channel interference (ICI) is the main factor that seriously influences the transmission performance. In this letter, with the channel state information (CSI) known at the transmitters, a general criterion of balancing the spectral efficiency and the error performance is established by analyzing the special features of MIMO-VLC. Based on the criterion, a channel-adapted spatial modulation (CASM) for massive MIMO-VLC is proposed, so as to find the optimal combinations of active light-emitting diodes under the controlled ICI. Simulation results show that CASM achieves more bit-error-rate gains over optical multi-stream spatial modulation (OMS-SM) with the same spectral efficiency, or even considering 10% reduction in the spectral efficiency of CASM caused by updating the CSI. Moreover, the higher spectral efficiency, the more gains of CASM over OMS-SM.