Numerical investigation on design of wide geographical optical-transport networks based on n×40-Gb/s transmission

We report a numerical investigation on the transmission techniques to achieve the highest capacities for n×40-Gb/s systems and such results are used to design the lightpath distribution in a European network operating with Tb/s traffic. We consider the return-to-zero (RZ) transmission assuming different pulse duration to reach the highest capacity both in the case of single-channel and of wavelength-division multiplexing. We assume the transmission in links encompassing G.652 optical fibers since they are the most installed in the world, considering the compensation of the chromatic dispersion with optical-fiber gratings. Both the amplification with erbium-doped fiber amplifier (EDFA) and hybrid Raman/EDFA is considered. We use a novel algorithm for wavelength assignment in optical networks, taking into account both the traffic requirements and the physical impairments of the networks that manifest in the signal transmission. The algorithm is based on the technique of the removing lightpaths. We report an application for a Pan European network with 26 nodes.