The widespread deployment of LEDs for illumination purposes has open the door to the use of these devices for visible light communications (VLC). Most lighting fixtures are mounted with phosphor-based white LEDs, and a driver connected to the LED is also required for VLC. This paper shows that the parasitic effects introduced by this setup change the frequency response of the intrinsic LED. A linear model to characterize the whole setup is proposed, as well as a methodology to extract its parameters. This methodology allows the designer to characterize the frequency response of LEDs without the additional difficulty of knowing the specific parasitic components introduced by the setup. The proposed model offers an accurate estimation of the slope of the LED frequency response in order to broaden the frequency range in which the model is useful to characterize and simulate VLC links. This was corroborated with the characterization of three commercial white LEDs whose measured and modeled frequency responses matched perfectly.

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LED lighting has become the standard solution for illumination purposes thanks to its energy efficiency. Nowadays, there is growing interest in the use of LEDs for data transmission to develop future-generation communication systems. The low cost and widespread deployment of phosphor-based white LEDs make them the best candidate for visible light communications (VLC), although they have a limited modulation bandwidth. This paper presents a simulation model of a VLC link based on phosphor-based white LEDs and a method to characterize the VLC setup used to perform the data transmission experiments. Specifically, the simulation model incorporates the frequency response of the LED, the noise levels coming from the lighting source and the acquisition electronics, and the attenuation due to both the propagation channel and the angular misalignment between the lighting source and the photoreceiver. In order to validate the suitability of the model for VLC, carrierless amplitude phase (CAP) and orthogonal frequency division multiplexing (OFDM) modulation signals were employed for data transmission, and simulations with the proposed model and measurements over the equivalent scenario show high agreement.