Africa two: a proposal for a concentric two-ring network for the african continent

In the challenging social/geographical environment in Africa, how to design a robust network while tolerating the traffic imbalance is studied in this paper. We propose the Africa TWO network which connects all countries in Africa by employing two concentric rings. We investigate an Integer Linear Programming model and develop heuristic algorithms to deal with some special issues in Africa, such as a large desert in North Africa, high-speed network connectivity to the rest of the world through a few existing undersea fiber cables, and traffic imbalance caused by the differential populations of the various countries. To further exploit the properties of the designed network, we propose Little-Arc-First (LAF) routing algorithm, First-Matching (FM) wavelength assignment, and Sharing Peer Protection (SPP) scheme. The proposed algorithms LAF and FM are more efficient than existing algorithms. Sharing Peer Protection (SPP) scheme achieves high reliability in a cost- effective manner. We also address how to upgrade the network to achieve longer network lifetime for overall economic benefit. Our simulation experiments demonstrate that the concentric two-ring network is a natural candidate not only for the African continent, but can also be extended to other countries and regions.