Design and Implementation of an Integrated Visible Light Communication and WiFi System

Visible light communication by light-emitting diodes (LEDs) has become one of the promising technologies to boost the capacity of mobile networks, due to the low cost and high energy efficiency of LED lamps and the vast unregulated visible light bandwidth. However, VLC is only suitable for downlink data transmissions from LED illumination infrastructures to mobile users. Moreover, due to the line-of-sight (LOS) transmission feature of visible light, the VLC downlink can be easily interrupted by blockage of obstacles or rotation of receivers, which leads to unreliable coverage of mobile users. To overcome the above two drawbacks of VLC, an integrated VLC and WiFi system is designed in this paper. In our proposed system, a 2.5 sublayer called link convergence (LC) layer between the IP layer and the data link layer is designed to integrate WiFi radio and VLC radio. The following key mechanisms are designed in the LC layer to support efficient communications of the integrated system: (a) VLC radio access; (b) VLC ARP table; (c) VLC selective ARQ; (d) VLC link maintenance; (e) handover between WiFi and VLC. Since the integration is above date link layer, no MAC driver or protocol modifications are needed for WiFi in our system. A prototype of our designed integrated system is implemented. Experiment results validate the feasibility and effectiveness of our proposed system.