Designing optimal interlink structures for interdependent networks under budget constraints

In this work, we focus on the problem of obtaining the optimal interlink structures, which maximizes the robustness of networks against random node failures, in a cost constrained setting. Using percolation theory based system equations, we have formulated our objective as a constrained optimization problem and designed algorithms serving two key purposes: i) obtaining the budget limits, Bl and Bu, defined as the minimum budget guaranteeing the existence of a feasible and optimal interlink structure, respectively; and ii) obtaining interlink structures for intermediate budgets. Through these algorithms and associated simulation results, we demonstrate the importance of cost in network design. Furthermore, the designed algorithms have close to optimal performance while being much cheaper than cost agnostic network designs.