Optimizing Regenerator Cost in Traffic Grooming

In optical networks regenerators have to be placed on light-paths every d nodes in order to regenerate the signal. In addition, grooming enables the use of the same regenerator by several light-paths. Up to g (the grooming factor) light-paths can use the same regenerator. In this paper, the authors consider the problem of minimizing the number of regenerators used in traffic grooming in optical networks. Starting from the 4-approximation algorithm for d = 1 and a path topology, they provide an approximation algorithm with the same approximation ratio for d = 1 and the ring and tree topologies.