High-availability free space optical and RF hybrid wireless networks

In this article, we introduce hybrid free-space optical and RF wireless links as potential technology for designing next-generation broadband wireless networks. We present various design challenges and potential solutions for real-time link performance characterization and adaptation for enhanced performance during adverse weather conditions. First, we introduce the hybrid wireless architecture and emphasize its significant role in achieving ubiquitous carrier-grade wireless connectivity. Second, we propose a link monitoring scheme that accurately reflects the performance of optical wireless links under various weather conditions. In addition, we examine the role of known link performance restoration schemes - power and data rate control. Third, we propose two novel link restoration schemes that efficiently utilize the hybrid architecture: dynamic load switching and multihop routing. Finally, the article describes an elaborate field testbed based on the hybrid architecture and various link restoration techniques. The dynamic load switching scheme is shown to have a profound impact on the overall hybrid link availability. The results, recorded from the experiments during extreme weather conditions, validate the impact of the hybrid architecture concept and conclusively prove the availability and reliability of the architecture in achieving sustained high-speed wireless connectivity.