Method for transmitting optical signal with adaptive bitrate using a PDM-QAM modulation scheme and a corresponding transmitter

摘要

The present invention refers to a method for adapting a bitrate of a modulated signal in an optical network using a quadrature amplitude modulation with a given power of two, 2N with N being an natural number larger than one, number of states combined with at least one other coded modulation comprising at least two coded states wherein for a given quadrature amplitude modulation symbol state of a given coded state, only a predetermined number of associated quadrature amplitude modulation symbol states of the other at least one coded state are selected as possible transmitted quadrature amplitude modulation symbol states, said predetermined number being a predetermined power of two, 2M, smaller than the given power of two, 2N, with M being a natural number smaller than N.