Decorrelation Lenses for Massive MIMO Visible Light Communications

Visible light communications (VLC) have garnered increasing attention due to its high data rate, large capacity and enhanced security. However, current VLC systems suffer from limited bandwidth of off-the-shelf light-emitting-diodes (LEDs), and it is still challenging to realize a large number of parallel VLC channels for higher capacity with compact transceivers due to the inter-link interferences. This letter presents a novel decorrelation lens system for cost-effective and compact parallel VLC links. The system is designed to address the challenges associated with densely packed LEDs, where signal separation is critical for minimizing the inter-link interference. We derive the optimal positions of lenses to minimize the receiver size. Average received power and bit error rate are expressed in closed forms. Simulation results demonstrate that massive multiple-input multiple-output communications with densely packed LEDs can be realized when the lenses and photodiode plane are properly placed.