Dimensioning OLT architectures for UDWDM-PONs employing coherent transceivers

Ultra-Dense Wavelength Division Multiplexing (UDWDM) is a new method for access PON, introducing the wavelength-to-the-user concept. The main technology will be a cost-effective coherent detection scheme providing low-cost terminals, while also furnishing high splitting ratios and long-reach extension. At the outside plant, the Optical Distribution Network based on splitters is kept compatible. In this article, ONU designs implemented with coherent transceivers using one or two lasers are introduced; at the OLT, the corresponding architectures are proposed and dimensioned. The number of wavelength channels needed is evaluated by a heuristic Dynamic Wavelengths Assignment (DWA) scheme. The amount of deployed users, long reach extension, power safety and fiber nonlinearities are studied and considered for the dimensioning of the network.