Experimental Investigation into the Influence of LED Bias Setup on VLC Frequency Domain Characteristics: Beyond Non-Negativity

Abstract

Different from the radio frequency bipolar complex signalling, LED-based visible light communication (LED-VLC) meets the non-negativity requirement by adding a bias component (BC) to a bipolar real-valued signal. Although many people know that there is a relationship between BC and LED characteristics, unfortunately, most of them chose to ignore it, and thus there has been little exploration of its impact on VLC. In this paper, we have experimentally measured the frequency domain characteristics of several LEDs commonly used in home and business applications. The numerical calculations show that the logarithmic domain absolute frequency response is approximately linear, where the corresponding intercepts and slopes can be quadratically expressed with respect to BC with a very low fitting error. This experimental investigation reveals that the BC value will remarkably influence the VLC system performance beyond non-negativity, and the LED-VLC transceiver designs should jointly take the BC and LED communication characteristic into consideration.