Crosstalk reduction in optical networks using variable subcarrier power levels

Patent metadata

Field	Value
Publication number	US-9312914-B2
Application number	US-201314033090-A
Country	US
Kind code	B2
Filing date	Sep 20, 2013
Priority date	Apr 22, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A method and system for reducing crosstalk among subcarriers of a super-channel may involve adjusting power levels of the subcarriers. In one example, power levels of edge and/or intermediate subcarriers may be reduced relative to center subcarriers in the super-channel band. The adjustment in power level may lead to overall reduction in optical signal-to-noise ratio degradation.

First claim

What is claimed is:

1. A method of reducing crosstalk among subcarriers of a super-channel, the method comprising: receiving a plurality of data streams for transmission over an optical transport network as the super-channel, the super-channel comprising a plurality of subcarrier bands, wherein each of the plurality of subcarrier bands is comprised of a plurality of subcarriers; assigning optical frequencies to the subcarrier bands; adjusting power levels, respectively, for at least some of the subcarrier bands, wherein at least two subcarrier bands have different power levels; optically modulating the data streams into the subcarrier bands using the assigned optical frequencies and the adjusted power levels; and combining the subcarrier bands into the super-channel.

2. The method of claim 1 , wherein adjusting the power levels comprises sending an instruction to a variable optical attenuator associated with an optical transmitter.

3. The method of claim 1 , wherein adjusting the power levels comprises sending an instruction to a wavelength selective switch.

4. The method of claim 1 , further comprising:
when the plurality of subcarrier bands includes an odd number of subcarrier bands greater than 1, excluding a center subcarrier band from adjusting the power levels.

5. The method of claim 4 , wherein a magnitude of an adjusted power level depends upon a position of a subcarrier band in the plurality of subcarrier bands.

6. The method of claim 1 , wherein the adjusted power levels are symmetric with respect to an average optical frequency of the assigned optical frequencies.

7. The method of claim 1 , wherein adjusting the power levels is performed in response to receiving an error rate measurement on data streams transmitted over the optical transport network using the super-channel.

8. An optical transport network for reducing crosstalk among subcarriers of a super-channel, comprising:
a control plane system including a processor configured to access non-transitory computer readable memory media, wherein the memory media store processor-executable instructions, the instructions, when executed by the processor, cause the processor to:
identify a plurality of data streams for transmission over an optical transport network as the super-channel, the super-channel comprising a plurality of subcarrier bands, wherein each of the plurality of subcarrier bands is comprised of a plurality of subcarriers;
assign optical frequencies to the subcarrier bands;
determine adjusted power levels, respectively, for at least some of the subcarrier bands, wherein at least two subcarrier bands have different power levels; and
send an instruction to at least one element in the optical transport network to:
optically modulate the data streams into the subcarrier bands using the assigned optical frequencies and the adjusted power levels; and
combine the subcarrier bands into the super-channel.

9. The optical transport network of claim 8 , wherein the at least one element in the optical transport network comprises a variable optical attenuator associated with an optical transmitter.

10. The optical transport network of claim 8 , wherein the at least one element in the optical transport network comprises a wavelength selective switch.

11. The optical transport network of claim 8 , further comprising instructions to:
when the plurality of subcarrier bands includes an odd number of subcarrier bands greater than 1, exclude a center subcarrier band from the instructions to determine adjusted power levels.

12. The optical transport network of claim 11 , wherein a magnitude of an adjusted power level depends upon a position of a subcarrier band in the plurality of subcarrier bands.

13. The optical transport network of claim 8 , wherein the adjusted power levels are symmetric with respect to an average optical frequency of the assigned optical frequencies.

14. The optical transport network of claim 8 , wherein the instructions to determine adjusted power levels are executed in response to receiving an error rate measurement on data streams transmitted over the optical transport network using the super-channel.

15. A control plane system for reducing crosstalk among subcarriers of a super-channel in an optical transport network, the control plane system for:
identifying a plurality of data streams for transmission over an optical transport network as the super-channel, the super-channel comprising a plurality of subcarrier bands, wherein each of the plurality of subcarrier bands is comprised of a plurality of subcarriers;
assigning optical frequencies to the subcarrier bands;
determining adjusted power levels, respectively, for at least some of the subcarrier bands, wherein at least two subcarrier bands have different power levels; and
sending an instruction to at least one element in the optical transport network for:
optically modulating the data streams into the subcarrier bands using the assigned optical frequencies and the adjusted power levels; and
combining the subcarrier bands into the super-channel.

16. The control plane system of claim 15 , wherein the at least one element in the optical transport network comprises a variable optical attenuator associated with an optical transmitter.

17. The control plane system of claim 15 , wherein the at least one element in the optical transport network comprises a wavelength selective switch.

18. The control plane system of claim 15 , further for:
when the plurality of subcarrier bands includes an odd number of subcarrier bands greater than 1, excluding a center subcarrier band from determining adjusted power levels.

19. The control plane system of claim 18 , wherein a magnitude of an adjusted power level depends upon a position of a subcarrier band in the plurality of subcarrier bands.

20. The control plane system of claim 15 , wherein the adjusted power levels are symmetric with respect to an average optical frequency of the assigned optical frequencies.

21. The control plane system of claim 15 , wherein determining the adjusted power values is performed in response to receiving an error rate measurement on data streams transmitted over the optical transport network using the super-channel.

Assignees

• Fujitsu Ltd

Inventors

• Vassilieva Olga
• Sekiya Motoyoshi

Classifications

• H04B3/32 Primary

  Reducing cross-talk, e.g. by compensating · CPC title

• H04B10/506

  Multiwavelength transmitters · CPC title

• H04B10/564

  Power control · CPC title

• H04B10/0799

  Monitoring line transmitter or line receiver equipment · CPC title