Logical topology optimization of free space optical networks with tracking transceivers

This paper proposes a transceiver system for automatic tracking and dynamic routing for free space optical (FSO) communication. The proposed transceiver architecture has M transmitters and M receivers in a M×M configuration that has the capability to dynamically orient themselves at different angles to establish a link between two nodes. It also addresses the problem of optimizing and designing logical topologies for FSO communications using tracking transceivers. Whereas the physical topology consists of nodes, transmitters and receivers that can orient themselves in different directions, the logical topology consists of a set of lightpaths and the set of nodes originating or terminating the lightpaths. A lightpath in a logical topology is a combination of one or more physical links using transmitters and receivers with the same wavelength. For a given physical topology and traffic pattern, the main challenge is to establish an optimal logical topology so as to minimize congestion. We formulate a mixed integer linear programming (MILP) methodology for constructing logical topologies in FSO networks with tracking transceivers. The main objective of the mathematical formulation is to minimize the maximum offered load on any physical link so as to minimize congestion in the network. Given a fixed number of resources, in comparison to a fixed FSO architecture, the proposed architecture reduces the blocking probability further as well as increases the percentage recovery of traffic affected by a single link failure.