s. In order to increase the power budget we can follow the same line used for the 4QAM and cut by half the number of channels. Changing two 10 Gbit/s channels with one 100 Gbit/s, a comb of 100 GHz spaced chan- nels at 100 Gbit/s is obtained formed by 45 channels as in the case of 64-4QAM. This allows, with an amplifier output power slightly reconfigured from 20 to 20.5 dBm, to bring the power per channel at the preamplifier output to 4 dBm, bringing the SNo from 17.44 to 21 dB. So high a power per channel, however, creates a very detrimental effect for a polariza- tion modulated system. Applying the method reported in [65] to our case, the propagation of a 33 GHz signal along 3000km with a span length of 70km and a power at the in-line amplifier output of 4 dBm, the depolarization factor 8 pol is about 0,01. Equation 9.28 tells us that, every time there is a part of the information coded in the field polarization, that is, every time there is the need of polarization tracking, high speed polarization fluctuations introduces a plateau in the SNo and thus in the BER. This plateau is expressed by Equation 9.28 itself. The only way to avoid this plateau would be to increase the speed of the polarization tracker to follow these fast fluctuations also, but in the case of Kerr-induced depolarization this is not possible due to the speed of the effect. In our case, the plateau is 20 dB; thus nonlinear polarization fluctuations set an upper limit to the system SNo that is too low to allow transmission at 3000km. The only way to go is to cut the link length. In order to do that, let us imagine placing a double terminal in an intermediate site to regenerate all the signals at half the length. In this situation, maintaining 90 channels at 100 Gbit/s, we have two identical systems 1500km long with a capacity of 9 Tbit/s. Telecommunication Networks Maintaining the amplifiers output power at 21 dBm, the power per channel at the input of a span is 1.45 dBm and the depolarization index is Spol = 0.0012 for a limit SN, = 29.2 dB,