Building robust spanning trees in free space optical networks

Free space optical (FSO) technology has been considered as a viable solution for broadband wireless networks. It has high potential for military communications for the next decade. In this paper, we investigate the problem of building robust spanning trees for FSO networks. We adopt algebraic connectivity as robustness measure, and formulate a 0-1 integer linear programming (ILP) problem. We present a fragment selection and merging (FSM) algorithm, which is executed in a distributed and asynchronous fashion to iteratively merge fragments until a spanning tree is formed. Our simulation study shows that FSM can achieve significantly improved connectivity at the cost of slightly degraded average link weight performance, compared to prior approaches. FSM can be used not only for FSO network bootstrapping, but also for auto-reconfiguration in response to network dynamics during operation.