An Algorithm with Better Approximation Ratio for Multicast Traffic in Unidirectional SONET/WDM Rings

Abstract

The goal for the problem of efficient grooming of given non-uniform multicast traffic demands on a unidirectional SONET/WDM ring is to try to minimize the network cost as given by (i) the number of wavelengths required per fiber and (ii) the number of electronic Add- Drop Multiplexers (ADMs) required in the ring. The problem with cost function (i) can be reduced to a corresponding traffic grooming problem for unicast traffic which can then be modeled as a standard circular-arc graph coloring problem.The function (ii) is a main research topic in recent studies.The problem is NP hard for both the cost functions. For the problem with fuction (ii), we present a algorithm with better approximation ratio, \( \frac{3}{2}(\frac{N}{{N - 1}} + 1)\). Additionally, we give a lower bound and upper bound for the number of ADMs.