Flexible optical transmission
15 January 2008
With the advent of the coherent age the implementation of massive digital signal processors (DSP) integrated with high speed AD and DA converters the flexibility of transponders has been facilitated more and more. Today the implementation of variable transponders is mainly based on variable programming of DSP to support different modulation formats and symbol rates. Modulation formats with high flexibility are required such as pragmatic QAM formats and hybrid modulation formats. We report on a recently proposed implementable probabilistic shaping schemes allowing for adjusting the bitrate, compare it with state of the art modulation formats and highlight the individual advantages for the application.