Cooperative visible light communications

Abstract

In this chapter, we explore the concept of cooperative transmissions in the context of visible light communications (VLC). An indoor office space is considered with two light sources; the one at the ceiling is connected to the backbone network and provides ambient light to the environment while the other one is mounted on the desk and used for task lighting. The system architecture builds upon DC biased optical orthogonal frequency-division multiplexing (DCO-OFDM). The task light performs relaying operation in either amplify-and-forward (AF) or decode-and-forward (DF) mode. Illumination constraints for task lighting are further considered in order to design a cooperative VLC system that provides satisfactory lighting. The communication performance of the system is optimized through a subcarrier-based power allocation mechanism. Numerical results incorporating practical issues such as band-limited channel process and imperfect channel estimation reveal that cooperative VLC systems can significantly outper-form the conventional point-to-point VLC systems.