Hybrid visible light and power line communication for indoor multiuser downlink

Visible light communication (VLC) turns indoor light-emitting diode (LED)-based illumination devices into high-speed network portals that, for example, operate in tandem with existing Wi-Fi networks. Since in this scenario, multiple VLC-equipped luminaires would serve overlapping service areas, we suggest the use of power line communication (PLC) to coordinate and provide data to the VLC transmitters. In particular, in this paper, we propose a hybrid VLC-PLC (HVP) system architecture for the indoor downlink transmission and present the analytical framework for the data rate analysis of the HVP system. In our solution, spatial optical OFDM (SO-OFDM) is applied across multiple luminaires, for which we propose several subcarrier allocation schemes to exploit the frequency selectivity of the VLC and PLC channels. Different possible and meaningful variations of the HVP system, including the choice of optical OFDM transmission, relay, and multiple access schemes, are investigated and compared. The numerical results establish achievable rates for relevant communication scenarios and highlight the advantages of the proposed subcarrier allocation scheme in terms of rate and reduced peak power of optical OFDM signals.