On design of communication networks with tree-star configuration

Abstract

Most of present large-scale communication networks adopt a two level hierarchical network whose structure consists of a backbone network in the upper level and a family of local access network in the lower level. This hierarchical structure offers extensive integration and sharing of functions to reduce the overall network costs and to operate the network with flexibility. The topological design is one of the most important problems that arise in connection with the design of two-level hierarchical networks. The objective of this study is to provide some mathematical formulations and efficient solution methods for the topological design problem of a special type of two-level hierarchical network. Unlike the conventional approaches of partitioning the global design problem into the design of backbone network and the design of local access networks, we adopt the unified approach, which the whole design problem is directly dealt with in such a general setting that both a backbone network and local access networks attached to it are to be simultaneously determined. First, we examine the dual based algorithms for the network design related problem We provide a broad overview of major algorithms by briefly describing different types of the dual based algorithms that have been studied and then indicate which characteristics of the exploited special structure of the problems make possible to apply the dual ascent algorithm. Secondly, we focus on the design of a network with a two-level ``tree-star`` hierarchical structure (THNTS) where the upper-level backbone network is tree-shaped, and the lower-level local access networks are of star type. As a means to widen the real-world applicability over the existing network design studies, a backbone node not opened is allowed to be used as a transhipment node bridging the established backbone links. The problem is modelled as a mixed 0-1 linear program, whose special structure is exploited for the development of an effi...