Modeling and Analysis of Transmitter Performance in Visible Light Communications

This paper addresses the power penalty in a visible light communication (VLC) emitter that re-uses illumination light emitting diodes (LEDs) for high-speed communications. We quantify the effect of modulation depth for two widely explored modulation schemes in VLC, namely orthogonal frequency division multiplexing (OFDM) and pulse amplitude modulation (PAM). Extra power is dissipated in the LED and in the modulator due to such modulation. Two popular high-speed VLC transmitter topologies, namely a Bias Tee and a Serial FET, are compared in terms of efficiency, extra energy per symbol/bit and complexity. This paper presents a theoretical model and compares it to simulation results. We show that PAM outperforms OFDM in terms of better bit error rate, larger dynamic range for modulation depth, less extra power loss, thus higher power efficiency for communication over an additive white Gaussian noise channel.