Topology Design and Cross-Layer Optimization for FSO Mesh Networks Impaired by Atmospheric Turbulence and Misalignment Fading

In this paper, we design and optimize freespace optics (FSO) mesh networks over atmospheric turbulence and misalignment fading channels. We propose a heuristic algorithm to choose the best sites to install the FSO transceivers and also the best topology for a given traffic matrix in a region. The algorithmaims to use as few FSO links as possible since this allows us to reduce the network costs. In addition, the algorithm takes into account the influence of turbulence, misalignment, and noise by choosing links with a low bit-error rate (BER). Besides the heuristic, we also propose an optimal integer linear programming model for solving the same problem. The simulation results show that the proposed heuristic runs very fast, even with a large number of choices of FSO sites. Therefore, it is practical to use the heuristic to quickly design a restoration communication network for replacing a regular one affected by a disaster. The average BER of all FSO links of the designed network also meets the requirement of an end-to-end BER threshold.