A model for optimal provisioning of digital switching facilities in a local telephone network

This paper addresses the problem of planning the introduction of multiple digital switching systems with remote concentrator options into a local telephone network, which essentially consists in finding an optimal network evolution strategy. Such a strategy is defined by the type, location, and time of placement of digital switches and remote concentrators as well as the assignment of concentrators to digital switches. Several mathematical formulations of the problem are discussed, and a practically realistic model is suggested. The model is solved by a heuristic two-level hierarchical optimization procedure, which is computationally efficient and produces good approximate solutions. Computational experiments and practical uses of the model are reported.