Data-aided multi-symbol phase estimation for optical differential multilevel phase-shift keying signals
AssigneeAlcatel-Lucent USA Inc.
InventorXiang Liu
Life of this patent
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Abstract
A data-aided, multi-symbol phase estimation (MSPE) scheme is described for improving receiver sensitivity in the direct-detection of optical differential multi-level phase-shift keying (ODmPSK) signals including optical differential quadrature phase-shift keying (ODQPSK) signals, ODQPSK signals with amplitude shift keying (ODQPSK+ASK), optical differential 8-level phase-shift keying (OD8PSK) signals with eight phase levels, and optical differential phase-shift keying signals with more than eight phase levels. The use of data-aided MSPE substantially reduces the “differential detection penalty,” with receiver sensitivity approaching that of coherent detection schemes.
Claims32
A method for determining a data content of an optical differential multi-level phase-shift keying (ODmPSK) signal, the method comprising:
- demodulating the ODmPSK signal with optical delay interferometers (ODIs) to generate two quadrature optical components;
- directly detecting the two quadrature optical components to generate an in-phase electrical signal, uI, and a quadrature electrical signal, uQ;
- performing a data-aided multi-symbol phase estimation (MSPE) on the in-phase electrical signal and the quadrature electrical signal to generate at least two improved decision variables;
- and
- recovering a plurality of data tributaries representing the data content based on the improved decision variables.
An apparatus for determining a data content of an optical differential multi-level phase-shift keying (ODmPSK) signal, comprising:
- means for demodulating the ODmPSK signal to generate two quadrature optical components through optical delay interferometers (ODIs);
- means for directly detecting the two quadrature optical components to generate an in-phase electrical signal, uI, and a quadrature electrical signal, uQ;
- means for performing a data-aided multi-symbol phase estimation (MSPE) on the in-phase electrical signal and the quadrature electrical signal to generate at least two improved decision variables;
- and
- means for recovering a plurality of data tributaries representing the data content based on the improved decision variables.
Dependencies are inferred from the claim text.