Performance of visible light communications with dimming controls

Visible light communications (VLC) have gained popularity as an alternative to RF. Understanding the underlying communications is key to the design of MAC protocols for arbitrating access across lights in multiple rooms. We consider the interference across two rooms from VLC emitters. The emitters use Binary Pulse Position Modulation (BPPM); the pulse width is varied to provide different dimming levels. We use a modified ray-tracing algorithm to calculate the channel impulse response between the emitters and receivers that are located at different positions within a room. We analyze the performance observed at the receivers in the presence of (i) illumination and (ii) transmissions from an interfering VLC emitter. We find that in the former case, the VLC emissions from the interferer do not impact the reception at the target receiver. In the latter case, the performance is degraded and it depends on the position of the receiver.