2016 Volume 5 Issue 12 Pages 461-466
We numerically evaluate optical transmission characteristics of four- and eight-dimensional modulation formats, and find that they are effectively improved by wavelength-diversity or cross-talk (XT) compensation with 4 × 4 adaptive multiple-input multiple-output (MIMO) equalization. Further, we quantitatively verify that the four-dimensional formats with the diversity configuration is superior to the eight-dimensional formats using dual carriers in terms of the robustness against unbalanced OSNR of the two carriers. We also quantitatively demonstrate the XT compensation effectiveness for the eight-dimensional modulation formats in case that the dual carrier spacing is less than the symbol rate.
