A new model for optimal planning of synchronous digital hierarchy unidirectional rings

With the technological advances being made in telecommunication transmission, synchronous digital hierarchy (SDH) is replacing plesiochronous digital hierarchy (PDH). Thus, ring network topologies are being widely used by Telebras system operating companies. This paper proposes a model for planning SDH unidirectional rings which allocates and dimensions the equipment to be used, makes the routing in order to meet traffic demands and minimizes the network costs. Mixed integer linear programming is used in which the traffic between network nodes is represented by a multicommodity flow associated to an origin-destination matrix, and the network is represented by a graph. The model for interconnecting unidirectional rings is made with the additional constraint that real variables are used. This is unprecedented in the literature. The paper also presents the results obtained when the model was applied to two urban networks.