Optimal user node placement for multi-hop FSO broadcasting communications under weak turbulence conditions

Abstract

Optimal node placement is studied for multi-hop free-space optical communications where any node can be a user. The lognormal weak turbulence channel is assumed. First, the problem of node placement is formulated as a constrained multi-objective optimization problem. Then, according to the priority of each user, the multi-objective problem is simplified to a constrained single-objective problem where the objective function is the sum of the weighted outage probabilities of all the users. Iteration is applied to obtain the optimal node placement solution. More importantly, as a generalization of prior results, we deduce that the optimal node placement in high signal-to-noise ratio scenario is irrelevant to the number of users or the priority of users. Simulation results agree with the proposed analytical results.