Power Consumption of a LiFi Transmitter

Improved energy efficiency is one of the challenges for a future-generation communication network. This paper addresses whether optical wireless communication can save energy in delivering high-speed internet access by using light to transmit data. Light Fidelity (LiFi) needs a more reliable model of the power consumed by an LED that is being modulated (Watt/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> per bit/s), i.e., one that is more reliable than commonly used in scientific literature. Many earlier publications stated that the optical power is proportional to the average intensity signal (1st moment), while the electrical power would be proportional to the variance, i.e., to the average of the square of the signal. This frequently made assumption for the electrical power is surprising, as it suggests that an light emitting diode (LED) can violate the Law of Conservation of Energy. It also ignores the Shockley diode equation and it fails to account for the energy needed to generate a photon. Nevertheless, many results and papers on LiFi borrow their solutions from radio frequency (RF), and have been optimized as if power is proportional to the variance. An LED differs from a 50 Ω antenna in non-linearity. Moreover, its performance depends on biasing. This paper proposes a more realistic power consumption model for LiFi.