Capacity enhancement of RF wireless mesh networks through FSO links

RF-based technologies are often used to address the last-mile problem. However, RF technologies generally create a bottleneck for the ever-increasing demand for bandwidth, causing the under-utilization of core network resources. Enhancing the capacity of wireless mesh networks can be done efficiently and cost effectively through boosting the capacity of some strategically located links. In this paper, we propose link augmentation via freespace optics (FSO) links. The high capacity of optical links is the key in link capacity enhancement in the resulting hybrid network. Adopting a TDMA-based framework, we formulate the problem of transceiver placement and the scheduling of RF links to maximize network capacity. To avoid the complexity of the ILP, we also propose a randomized greedy heuristic algorithm. In addition, simulated annealing is used to provide a baseline for comparison and to show the efficiency of our heuristic. We show by simulations that our heuristic, which can be implemented efficiently, achieves a high fraction of the optimal network capacity.