Energy-Efficient Precoding Design for Multiuser MISO VLC Systems Based on Joint Detection

In this paper, we study energy-efficient precoding techniques in multiuser multiple-input single-output (MISO) visible light communication (VLC) systems. Under the dual constraints of illumination and communication, an optimal precoding design is proposed for a
$4\times 2$
multiuser MISO VLC system by utilizing the properties of Farey sequence in number theory. It is proved that the received signals constitute a sizeable pulse amplitude modulation constellation and thanks to this nice constellation structure, low-complexity maximum likelihood detection is admitted for signal detection. The simulation results indicate that our proposed optimal precoding design outperforms zero-forcing and time-division multiple access schemes.