On design and operation of broadband transport networks

Abstract

In the transition period to full and open competition, the competitiveness of a company has become one of the most critical managerial factors. Since a company``s competitiveness comes from its profitability and business efficiency, we study economics involved in constructing and operating telecommunications networks. Some models and solution procedures are investigated to help design hierarchical transport networks and operate for logical topology reconfiguration. In designing a transport network, what should be considered are three kinds of construction related costs: the hub location cost, the conduit establishment cost, and the cabling cost therein. At first, we deals with a fiber transport network with hubbing topology that covers an area which is partitioned into several regions. We add a restrictive condition which states that a single hub should be opened in a region. and that conduit facilities are shared with by fiber cables of both the lower level connection and the upper level connection. We show that such a complex design problem can be transformed into a simple variant of the classical network design model by introducing dummy nodes and arcs and by judiciously redefining commodity-flows. A dual-based heuristic procedure which incorporates the well known Labeling Dual-Ascent Algorithm is developed to provide both a good lower bound and an upper bound of the optimal solution. In addition, we extend the above study into two types of variation considering real-world applicability. The former releases the regional hubbing constraint not specifying the number of open hubs. But costs of the hub level cabling need to be defined independent of the volume of flow therein. The latter considers the practicality that each end office may have direct route paths to some near end offices bypassing hubs. Except the direct paths, all the paths from an end office should be homed to a single hub irrespective of the path destination. Without partitioning into subpr...