In the case of signal distortions from nonlinear propagation, the behavior of
a system based on coherent detection in the absence of ODC is very similar
to the case of EPD discussed in previous section. As shown in Figure 2.25(c),
a dispersion compensation free system using coherent detection imple ments
an “all-postcompensation” dispersion map, whereas EPD implements an “all-
precompensation” map, both of which are, in general, not optimum for nonlinear
transmission. Nonlinearity compensation using digital signal processing at the
receiver can be based on backward propagation of single-channel nonlinear trans-
mission [278, 280]. Knowing the transmission line parameters and the signal
power evolution along the link, reverse propagation can be com ...