Availability optimization in a ring-based network topology

Cellular networks are nowadays considered as a major critical infrastructure. Resiliency to failure due to disasters, weather based disruptions or malicious activities is essential. In the case of ring topology, because of delay and availability requirements, a wireless network connected to an aggregation node must sometimes be split into several rings. In this paper, we study the availability optimization in a ring-based network topology for a given number of cellular sites and a given size of rings. We prove that if each ring includes 3 nodes, the problem can be solved in a polynomial time, while for bigger rings, the problem is NP-hard. In this latter case, we provide approximation methods based on linear programming in order to converge to the solution.