Topology and routing optimization for congestion minimization in optical wireless networks

Optical wireless networks have appealing features such as very high broadband data rates and cost effectiveness. They represent a potential alternative to the last mile (first mile) wireless access problem. However, they are also highly vulnerable to external disturbances such as adverse weather and building sway. In this paper, we develop robust and efficient methods for outdoor optical wireless networks by jointly considering topology optimization and survivability strategies. We propose linearized congestion minimization schemes with working and protection paths (LCM-WP), in which a mixed integer linear program is formulated to choose the optimal working and protection paths for every OD pair such that the network congestion is minimized. In particular, the objective is to minimize the maximum amount of traffic on the links. To solve realistically sized problems, we consider a restricted version of the LCM-WP, in which only limited sets of candidate working and protection paths are considered. A simple algorithm is developed to find candidate working and protection paths for each origin-destination (OD) pair. Implementation of our LCM-WP schemes demonstrates the efficiency of our approach in terms of the number of constraints and solution time. It also shows that our approach is applicable to realistically sized networks. (C) 2010 Elsevier B.V. All rights reserved.