Once the Raman distributed amplification is optimized, the design of the system can be done leveraging on two fixed numbers: the receiver sensitivity and the maximum peak power acceptable along the link to maintain nonlinear effects penalties within the limit compatible with the design. In our case, we have assumed to have a high-efficiency APD at the receiver with a sensi- tivity of -28 dBm. Since we have the demux and a series of other small losses between the last EDFA and the APD, the power that has to exit from the last EDFA is equal to -20 dB (compare Table 6.7, the detection chain). On the other hand, always assuming a link 10,0001 long, by considering under com- pensation for 2000 ps/nm; chirped RZ pulses with 25% duty cycle; and an electronic equal- izer at the receiver composed by a nine taps FFE and a four taps DFE, the peak power along the line cannot overcome 5 mW per channel per span to maintain the SPM and the FWM related penalties within 2 dB each. The SNo has the following expression: Gp(GR -1)NFR+(Gp-1)NFp] (6.78) where B is the optical noise bandwidth defined mainly by the cascade of the multiplexer and the demultiplexer Prec is the power on the receiver; this is a design parameter that has to be chosen to satisfy the receiver power budget and to optimize the system performances. In our case we select -20 dBm, against a sensitivity of -28 dBm and a saturation power of -10 dBm arec represents the total optical loss between the output of the last EDFA amplifier and the APD, in our case the loss of the AWG and of all the monitoring taps and connectors GB, GR GE, Gp are respectively the gains of the EDFA booster, the Raman gain, the gain of the EDFA in-line amplifier, and the gain of the last EDFA, that is differ- ent from the others since the signal at the exit of the last span is not equal to the signal at the exit of the booster, but is equal to Preclarec in order to minimize the ASE power NF B NFR NF, NF are respectively the noise factors of the EDFA booster, of the Raman amplification, of the 