Disaster-Aware Submarine Fiber-Optic Cable Deployment for Mesh Networks

With the increasing social and economic reliance on the Internet and the significant monetary and non-monetary societal cost associated with service interruption, network survivability is an important element in telecommunication network design. A major cause of Internet service interruption is breakage of fiber-optic cables due to man-made or natural disasters such as earthquakes. In addition to the societal cost, there is also cost of repairing damaged cables paid by the cable owner. A disaster-resilient submarine cable deployment can achieve significant cost saving when disaster strikes. In this study, we investigate a disaster-aware submarine fiber-optic cable deployment optimization problem to minimize such expected costs in case of a disaster. While selecting paths for the cables, our approach aims to minimize the expected cost for both cable owner and the affected society, considering that submarine fiber-optic cables may break because of natural disasters, subject to limitation of available deployment budget and other constraints. In our approach, localized disaster-unrelated potential disconnection (e.g., due to shark bites) are avoided by providing a backup cable along with primary cable. We consider a mesh topology network with multiple nodes located at different sea/ocean shores, submarine fiber-optic cables of irregular shape, and a topography of undersea environment. We present an Integer Linear Program to address the problem, together with illustrative numerical examples. Finally, we validate our approach by applying it to a case study of an existing cable system in the Mediterranean Sea, and the results show that we can significantly reduce overall expected cost at a slight increase in deployment cost. The results demonstrate a potential saving of billions of US dollars for the society in case of a future disaster. In order to achieve such large savings, cable companies may require to lay somewhat longer cables to avoid potential disaster areas, which may increase deployment cost that is relatively smaller compared to potential savings in case of a disaster. Understanding such trade-offs is important for stakeholders, including government agencies, cable industry, and insurance companies, which may have different objectives, but can work together for the overall benefit of the society.