Figure 2: The regenerative channel model.

(a) The regenerative transfer functions, plotted for the ideal regenerator and RFT: y=x+α sin(βx) with the alphabet shown by vertical lines; (b) the graphical interpretation of the stability analysis; (c) the scheme with regenerative filters (denoted by F) placed equidistantly along the line; noise distortions are effectively filtered by the ideal regenerators (see constellations before and after noisy transmission with attraction regions shown by straight lines); and (d) numerically calculated Shannon capacity and gain (compared with the linear AWGN channel) for RFT channel with R=20 and R=10 filters (showed by red and green colours, respectively) for both the superstable (dashed-dotted) αβ=1 and stable (dotted) αβ=0.5 mapping. The upper bounds of regeneration efficiency for the given number of the ideal filters R=10 and R=20 are shown by solid green and red curves, respectively.