Heterogeneous Software-Defined Networks: Implementation Of A Hybrid Radio-Optical Wireless Network

Visible light communication (VLC) is an emerging optical wireless technology which has the potential to complement existing radio frequency (RF) communication systems aiming at exploiting the advantages of both networks. The concept of such complementing as hybrid VLC/RF systems is well understood theoretically but not much has been done on practical realization. In this paper, we report implementation details of a hybrid VLC/RF point-to-point system, where two nodes are connected with each other via VLC and RF links. In this implementation, we consider VLC link as primary link therefore it will always be an active link whenever it is available. Nodes are capable of vertical handover between two types of communication links in case of primary (VLC) link failure and restoration. The VLC link state plays important role so we describe a continuous link monitoring protocol and criteria for switching between VLC and RF links. To switch between two links a Linux kernel bonding driver has been used. A simple link monitoring protocol has been implemented for VLC link state and it is passed continuously to bonding driver for decision. Performance of this system has been evaluated for user datagram protocol (UDP) content distribution while handover. Hence, a simple hybrid system capable of handover between VLC and RF links has been achieved.