Systems and methods for autonomous signal modulation format identification

Patent metadata

Field	Value
Publication number	US-9729362-B1
Application number	US-201414221246-A
Country	US
Kind code	B1
Filing date	Mar 20, 2014
Priority date	Mar 20, 2013
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

Systems and methods for autonomous signal modulation format identification are disclosed. In an example embodiment of the disclosed technology, a method includes applying higher-order statistics to an input signal to identify the input signal's modulation format. The method may include applying higher-order statistics to the input signal to calculate higher-order cumulant values for the input signal as higher-order cumulants are indicative of a particular modulation format signature. The method may further include employing a decision tree to determine the modulation format of the input signal.

First claim

What is claimed is:

1. A method for autonomously determining the modulation format of an input signal received at a receiver from a transmitter, the method comprising:
processing the input signal to generate a plurality of estimates of a state of polarization of the input signal;
responsive to generating the plurality of estimates of the state of polarization of the input signal, performing polarization scrambling mitigation on the input signal to generate a plurality of polarization demultiplexed signals;
estimating a frequency offset of each of the plurality of polarization demultiplexed signals, the frequency offset being between the transmitter and a local oscillator of the receiver;
responsive to estimating the frequency offset of each of the plurality of polarization demultiplexed signals, removing the estimated frequency offset of each of the plurality of polarization demultiplexed signals to generate a plurality of frequency offset-compensated signals;
estimating a phase offset of each of the plurality of frequency offset-compensated signals, the phase offset being between the transmitter and the local oscillator of the receiver;
responsive to estimating the phase offset of each of the plurality of frequency offset-compensated signals, removing the estimated phase offset of each of the plurality of frequency offset-compensated signals to generate a plurality of phase noise-compensated signals; and
calculating fourth-order cumulant values of each of the plurality of phase noise compensated signals by applying higher-order statistics to each of the plurality of phase noise-compensated signals; and
responsive to calculating the fourth-order cumulant values, employing a decision tree to identify, from the list comprising OOK, BPSK, QPSK, and 16-QAM, the modulation format of the input signal.

2. The method of claim 1 , wherein
fourth-order cumulant values are indicative of respective particular modulation format signatures.

3. The method of claim 1 , wherein processing the input signal to generate a plurality of estimates of the state of polarization of the input signal comprises operating a cross correlation between the input signal's X and Y polarizations.

4. A method comprising:
autonomously determining an input signal's baud rate with a processing medium, wherein autonomously determining the baud rate of the input signal comprises:
performing coarse estimation of the input signal's chromatic dispersion;
compensating the coarsely estimated chromatic dispersion of the input signal; and
processing the input signal with a weighted baud rate estimator;

after determining the baud rate of the input signal:
further compensating the input signal's chromatic dispersion (CD) with the processing medium to generate a CD-compensated signal; and
performing timing recovery on the CD-compensated signal with the processing medium to generate a timing-recovered signal;

processing the timing-recovered signal with the processing medium to (i) determine a number of multiplexed polarizations of the input signal and (ii) generate a plurality of estimates of the input signal's state of polarization;
responsive to generating the plurality of estimates of the input signal's state of polarization, performing polarization scrambling mitigation on the timing-recovered signal to generate a plurality of polarization demultiplexed signals; and
processing the plurality of polarization demultiplexed signals, with the processing medium, to obtain higher-order cumulants to identify the input signal's modulation format from among 16QAM, BPSK, QPSK and OOK.

5. The method of claim 4 , wherein identifying the modulation format of the input signal by processing the timing-recovered signal to obtain higher-order cumulants further comprises:
processing the timing-recovered signal to provide a plurality of phase noise-compensated signals; and
applying fourth-order statistics to each of the plurality of phase noise-compensated signals to identify, from the list comprising OOK, BPSK, QPSK, and 16-QAM, the modulation format of the input signal.

6. The method of claim 4 , wherein the weighted baud rate estimator is given by

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7. The method of claim 4 further comprising:
responsive to determining the modulation format of the input signal, performing format-optimized demodulation on the input signal with the processing medium, wherein performing optimized demodulation on the input signal comprises:
performing optimized polarization demultiplexing on the input signal based on the identified modulation format of the input signal;
removing the input signal's frequency offset based on the identified modulation format of the input signal;
removing the input signal's phase offset based on the identified modulation format of the input signal; and
correcting one or more instances of intersymbol interference associated with the input signal.

8. The method of claim 4 , wherein the input signal is received at a receiver from a transmitter, and wherein identifying the modulation format of the input signal by processing the plurality of polarization demultiplexed signals to obtain higher-order cumulants further comprises:
estimating a frequency offset of each of the plurality of polarization demultiplexed signals, the frequency offset being between the transmitter and a local oscillator of the receiver;
responsive to estimating the frequency offset of each of the plurality of polarization demultiplexed signals, removing the estimated frequency offset of each of the plurality of polarization demultiplexed signals to generate a plurality of frequency offset-compensated signals;
estimating a phase offset of each of the plurality of frequency offset-compensated signals, the phase offset being between the transmitter and the local oscillator of the receiver;
responsive to estimating the phase offset of each of the plurality of frequency offset-compensated signals, removing the estimated phase offset of each of the plurality of frequency offset-compensated signals to generate a plurality of phase noise-compensated signals; and
applying higher-order statistics to each of the plurality of phase noise-compensated signals to identify, from the list comprising OOK, BPSK, QPSK, 16-QAM, and M-QAM, the modulation format of the input signal.

9. The method of claim 8 , wherein applying higher-order statistics to each of the plurality of phase noise-compensated signals comprises:
calculating fourth-order cumulant values of each of the plurality of phase noise-compensated signals by applying higher-order statistics to each of the plura

Assignees

• Georgia Tech Res Inst

Inventors

• Ralph Stephen
• Mehta Kedar
• Isautier Pierre
• Stark Andrew

Classifications

• H04B10/6165

  Estimation of the phase of the received optical signal, phase error estimation or phase error correction · CPC title

• H04B10/6164

  Estimation or correction of the frequency offset between the received optical signal and the optical local oscillator · CPC title

• H04L27/0012 Primary

  arrangements for identifying the type of modulation · CPC title

• H04B10/6161

  Compensation of chromatic dispersion · CPC title

• H04L7/0075

  with photonic or optical means · CPC title