Design and optimization of FSO mesh networks over atmospheric turbulence and misalignment fading channels

In this paper, we design and optimize free-space optics (FSO) mesh networks over atmospheric turbulence and misalignment fading channels. We propose an heuristic algorithm to choose the best sites to install the FSO transceivers and also the best topology for a given traffic load in a region. The algorithm aims to use the least of FSO links as possible since this allows to reduce the network costs. In addition, the algorithm takes into account the influence of turbulence, misalignment, and noise by choosing links with low bit-error rate (BER). The simulation results show that the calculation time of the proposed heuristic algorithm is much smaller than optimal integer linear programming (ILP) model. Since the proposed algorithm runs very fast, even with a large number of choices of FSO sites, it is practical to use it in building quickly a restoration communication networks for replacing a regular one after a disaster. The average BER of all links of the FSO network designed by using the proposed algorithm also meets the requirement of end-to-end BER threshold.