Spectrally Efficient Cooperative Visible Light Communication with Adaptive Power Sharing for a Generalized System

Visible Light Communication (VLC) is among one-of-the top emerging next-generation technology and a key-enabler for the future networks, utilizing the visible light spectrum to achieve nominal data rates of Gbps. The compatibility of VLC with the existing infrastructure proves to be a major thrust in this domain, but suffers from signal fading and considerable interference provided by the nearby illuminants. Thus, a cooperative gain stage becomes essential to boost the signal present in the Non-line-of-sight (NLOS) with minimum power overheads. This paper proposes an optimal solution for the spectral efficiency of the VLC link: by introducing relay-based adaptive power-sharing schemes for improvement in signal strength, under the constraints of LED linear radiation region and threshold power consumption. DCO-OFDM modulation technique has been used to achieve minimum inter-symbol interference owing to its circular convolution properties. The Analytic analysis, as well as simulation results, are presented to show the effect of the scheme over an uncontrolled relay link. Later, a generalized model is proposed, and analytic methodology is adopted to determine optimal power-sharing coefficients. As a Figure of merit, we observe 18.29 % improvement in spectral efficiency at 13 dB of signal to noise ratio (SNR) when compared to an unoptimized collaborative link.