A best first search based optimal wavelength assignment algorithm to minimize the number of SONET ADMs in WDM rings

In WDM rings, determining minimum number of ADMs is NP-hard. The best known algorithm namely, breadth first least interference (BFLI) heuristic gives optimal results in only 77% cases. In this paper, we analyze the problem and suggest a new set covering formulation for minimizing the number of ADMs in WDM rings and use best first search algorithm (A*) with the help of a heuristic (h_LB) to solve it optimally. We establish through experiments that the search algorithm with the heuristic function (h_LB) performs better than BFLI by always giving optimal results.