Differential-coding and decoding for quadrature duobinary coherent optical communication systems
AssigneeAlcatel-Lucent USA Inc.
InventorChongjin Xie
Life of this patent
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Abstract
A method comprising, receiving digital-electrical input symbols of a stream of input symbols, the input symbols corresponding to signal points of a symbol constellation. The method also comprises classifying the input symbols, wherein a first symbol class comprises input symbols corresponding to signal points that are variant to rotation of the symbol constellation, and, a second symbol class comprises input symbols corresponding to signal points that are invariant to rotation of the symbol constellation. The method also comprises applying selective differential coding only to those input symbols of the first symbol class.
Claims20
A method, comprising:
- receiving digital-electrical input symbols of a stream of input symbols, the input symbols corresponding to signal points of a symbol constellation;
- classifying the input symbols, wherein a first symbol class comprises input symbols corresponding to signal points that are variant to rotation of the symbol constellation, and a second symbol class comprises input symbols corresponding to signal points that are invariant to rotation of the symbol constellation;
- and
- applying selective differential coding only to those input symbols of the first symbol class.
An apparatus, comprising:
- a digital signal processor (DSP) configured to receive digital-electrical input symbols of a stream of input symbols, the input symbols corresponding to signal points of a symbol constellation;
- a symbol classifier configured to classify the input symbols, wherein a first symbol class comprises input symbols corresponding to signal points that are variant to rotation of the symbol constellation, and a second symbol class comprises input symbols corresponding to signal points that are invariant to rotation of the symbol constellation;
- and
- a selective differential encoder configured to apply selective differential coding only to those input symbols of the first symbol class.
An optical communication system, comprising:
- an optical-to-electrical converter configured to convert a received optical stream of symbols to a digital-electrical stream of received symbols, the received symbols corresponding to signal points of a symbol constellation;
- an electrical-to-optical converter configured to convert a digital-electrical stream of transmitted symbols to a transmitted optical stream of symbols;
- and
- a digital signal processor configured to:
- classify the received symbols and the transmitted symbols, wherein a first symbol class comprises symbols corresponding to signal points of the symbol constellation that are variant to rotation of the symbol constellation, and a second symbol class comprises symbols corresponding to signal points of the symbol constellation that are invariant to rotation of the symbol constellation;
- and
- applying selective differential coding only to those input symbols of the first symbol class.
Dependencies are inferred from the claim text.