A Variable Descent Search Algorithm for Delay-Constrained Least-Cost Multicast Routing

The rapid evolution of real-time multimedia applications requires Quality of Service (QoS) based multicast routing in underlying computer networks. The constrained Steiner Tree, as the underpinning mathematical structure, is a well-known NP-complete problem. In this paper we investigate a variant of variable neighborhood search, variable descent search, for the delay-constrained least-cost multicast routing problems. The neighborhood structures designed in the variable descent search approaches are based on the idea of path replacement in trees. They are simple, yet effective operators, enabling a flexible search over the solution space of this complex problem with multiple constraints. A large number of simulations demonstrate that our algorithm is highly efficient in solving the delay-constrained, least-cost multicast routing problem in terms of both the total tree cost and the execution time. To our knowledge, this is the first study of variable neighborhood search on the delay-constrained, least-cost multicast routing problem. It outperforms other algorithms and heuristics over a range of problem instances.