Effective and comprehensive solution to traffic grooming and wavelength assignment in SONET/WDM rings

In high-speed SONET/WDM rings, the dominant system cost may be the cost of electronic components, or in other words, the cost of SONET ADMs (S-ADMs). The number of S-ADMs can be dramatically reduced by using wavelength ADMs (WADMs) and grooming traffic (i.e., multiplexing lower rate signals) appropriately. In this paper, we propose optimal or near-optimal algorithms for traffic grooming and wavelength assignment to reduce both the number of wavelengths and the number of S-ADMs. The algorithms proposed are generic in that they can be applied to both unidirectional and bidirectional rings with an arbitrary number of nodes under both uniform and non-uniform traffic with an arbitrary grooming (multiplexing) factor. Lower bounds on the number of wavelengths and S-ADMs required for a given traffic pattern are derived, and used to determine the optimality of the proposed algorithms. Our study shows that these lower bounds can be closely approached in most cases or even achieved in some cases using the proposed algorithms. In addition, even when using the minimum number of wavelengths, the savings in S-ADMs due to traffic grooming (and the use of WADMs) are significant, especially for large networks.