Jointly Optimal Routing and Caching with Bounded Link Capacities

We study a cache network in which intermediate nodes equipped with caches can serve requests. We model the problem of jointly optimizing caching and routing decisions with link capacity constraints over an arbitrary network topology. This problem can be formulated as a continuous diminishing-returns (DR) submodular maximization problem under multiple continuous DR-supermodular constraints, and is NP-hard. We propose a poly-time alternating primal-dual heuristic algorithm, in which primal steps produce solutions within 1 - 1/e approximation factor from the optimal. Through extensive experiments, we demonstrate that our proposed algorithm significantly out-performs competitors.