APSK-CSK Systems Based on Kite and Color Wheel Constructions

Abstract

Visible light communications (VLC) technology has emerged as a solution for the radio frequency relief and can be implemented, for example, through light fidelity. In most applications, VLC relies on a backbone technology due to its short-range nature. Hence, a combination technique is required to join the backbone network and VLC, preferably in an amplify-and-forward scenario, to reduce the implementation cost. In this paper, leveraging on the robustness of amplitude phase-shift keying (APSK) against channel nonlinearities, we propose a design framework consisting of a mapping technique using APSK and color shift keying (CSK), referred to as hybrid APSK-CSK scheme, to link a backbone network to VLC. The APSK constellation, made of two rings, is based on the kite structure. The ratio of inner by outer rings radii, $\beta$ , combined with four other parameters, namely, the attenuation coefficient of the backbone channel, $\alpha$ , the amplification coefficient of inner signal, $\delta _i$ , the amplification coefficient of outer signal, $\delta _o$ , and the ratio of the APSK-CSK inner by outer rings, $\gamma$ , are exploited to control lighting, color rendering, and the communication performance. Results reveal that the scheme performance is based on the obtained characteristic equations and provides better lighting comfort as the constellation size increases.