Optimal FSO relay nodes placement with link obstacles and infeasible regions

Optimal relay placement is studied for free-space optical multi-hop communication when obstacles and infeasible regions exist. We propose an optimization framework to find the optimal relay locations in the specified available regions and make laser links bypass obstacles of various shapes. A grouping optimization technique is proposed to reduce the optimization time when the number of relays is large, and we numerically demonstrate that this technique can provide solutions close to the optimal solutions, and its average searching time grows linearly with the number of relays. Simulation results show that our proposed optimization framework can effectively provide good solution to the problem of optimal relay placement in limited available regions, and enable the laser links to bypass obstacles in order to achieve minimum end-to-end outage probability.