re realized with the same DWDM system and using the same fiber, a single parameter replaces the two matrixes: dispersion and noise equivalent factor per kilometer for the links and channel crosstalk (both InB and OutB) and the noise equivalent factor for the OXCs. To simplify the situation, we will assume from now on in this section the last hypothesis. Telecommunication Networks Let us imagine that all the links are already dimensioned, that is, the EDFA amplifiers and the DCF are already individuated and their position stated. The only thing that the dimensioning algorithm can do is to deploy them in the preselected location or do not deploy any equipment in that location depending on the fact that the link using the con- sidered location is loaded or not. Moreover, let us assume that only perfect regenerators are used (implemented by opti- cal-electronic-optical conversion) to simplify the situation with respect to the case of opti- cal regenerators/WCs that realize the regeneration function in an imperfect way. Regenerators can be located only at OXC locations if a suitable OXC is deployed. Moreover, there is a maximum number of regenerators that each OXC can host, depending on the number of ports and on its degree. This is, for sure, a suboptimum approach, mainly due to the fact that a better design the transmission systems would be realized if the dispersion compensators were deployed SO as to realize an optimized map. However, in a transparent network this is practically impossible due to the fact that the real route that signals will follow is not known when the network is built. Let us also assume that all the deployed systems and OXCs are of the same type, and that only one OCh speed is present in the network. Under these simplifying hypotheses, we can write the condition SNo (all in dB) (10.23) where SNo is the optical SN determined by the transmitted power and the ASE noise Pen; are the penalties coming out from different sources SNrif is the reference optical SN Equation 10.22 can be generally writte