Optimized Hybrid Raman/EDFA Amplifier Placement for DWDM Mesh Networks

The minimization of the number of expensive 3R regenerators required at intermediate nodes is a key task when planning long-haul optical transport networks. Combining Raman amplification with Erbium-doped fiber amplifiers (EDFAs) is one of the strategies that can be exploited to achieve this objective, especially in the presence of long fiber spans. Given that hybrid Raman/EDFA amplifiers are more expensive than EDFAs, their deployment should also be minimized. However, determining the number and location of these amplifiers in a mesh optical network is a complex problem because of the overlap of lightpaths with different source and destination nodes at each link. A method to optimize the placement of hybrid Raman/EDFA amplifiers in mesh optical networks is described in this paper. The proposed method analyzes the network as a whole and determines where to introduce Raman amplification such that the 3R regenerator count is minimized while also keeping the number of hybrid Raman/EDFA amplifiers at a minimum. It is shown that, in a reference mesh optical network, the proposed method clearly outperforms the simpler placement approach based solely on fiber span attenuation.