Receiver for optical transmission system

Patent metadata

Field	Value
Publication number	US-9432128-B2
Application number	US-201214408282-A
Country	US
Kind code	B2
Filing date	Jul 25, 2012
Priority date	Jun 15, 2012
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

A method of detecting a signal in an optical receiver is described. The method includes converting a received optical signal to a digital electrical signal comprising a plurality of samples, applying a predetermined phase rotation to said samples to obtain amplitude and phase components of phase range adjusted sample values, and performing a first detection process based on the amplitude and phase components of the phase range adjusted sample values.

First claim

The invention claimed is:

1. A method of detecting a signal in an optical receiver, the method comprising:
converting a received optical signal to a digital electrical signal comprising a plurality of samples having in-phase and quadrature components;
applying a predetermined phase rotation to said samples;
converting the in-phase and quadrature components to amplitude and phase components;
applying an inverse of the predetermined phase rotation to the phase components such that phase range adjusted sample values have phases within ranges suitable for detection: and
performing a first detection process based on the amplitude and phase components of the phase range adjusted sample values.

2. The method as claimed in claim 1 , wherein the predetermined phase rotation is determined in a training process.

3. The method as claimed in claim 1 , further comprising retrieving values for the predetermined phase rotation from a look up table, based on a phase of the respective sample.

4. The method as claimed in claim 1 , wherein the first detection process is a Maximum Sequence Likelihood Estimation process.

5. The method as claimed in claim 1 , further comprising:
performing a second detection process based on the in-phase and quadrature components of the digital electrical signal; and
selecting a detector output from outputs of the first and second detection processes.

6. The method as claimed in claim 5 , wherein the second detection process is a Maximum Sequence Likelihood Estimation process.

7. The method as claimed in claim 5 , further comprising:
selecting the detector output based on respective quality measurements of outputs of the first and second detection processes.

8. The method as claimed in claim 1 , wherein the optical receiver is an optical fibre receiver.

9. A detector for detecting an optical signal, the detector comprising a processor that is operative to:
convert a received optical signal to a digital electrical signal comprising a plurality of samples having in-phase and quadrature components;
apply a predetermined phase rotation to said samples;
convert the in-phase and quadrature components to amplitude and phase components;
apply an inverse of the predetermined phase rotation to the phase components such that phase range adjusted sample values have phases within ranges suitable for detection: and
perform a first detection process based on the amplitude and phase components of the phase range adjusted sample values.

10. The detector as claimed in claim 9 , wherein the detector is included in an optical receiver, wherein the optical receiver comprises an optical front end.

11. The detector as claimed in claim 10 , wherein the detector is connected to a linear equalizer for receiving signals from the optical front end.

12. The detector as claimed in claim 10 , wherein the detector is connected to a backpropagation block.

13. The detector as claimed in claim 9 , wherein the predetermined phase rotation is determined in a training process.

14. The detector as claimed in claim 9 , wherein the processor is further operative to retrieve values for the predetermined phase rotation from a look up table, based on a phase of the respective sample.

15. The detector as claimed in claim 9 , wherein the first detection process is a Maximum Sequence Likelihood Estimation process.

16. The detector as claimed in claim 9 , wherein the processor is further operative to:
perform a second detection process based on said in-phase and quadrature components of the digital electrical signal; and
select a detector output from outputs of the first and second detection processes.

17. The detector as claimed in claim 16 , wherein the second detection process is a Maximum Sequence Likelihood Estimation process.

18. The detector as claimed in claim 16 , wherein the processor is further operative to:
select the detector output based on respective quality measurements of outputs of the first and second detection processes.

19. The detector as claimed in claim 9 , wherein the optical receiver is an optical fibre receiver.

20. A non-transitory computer readable storage medium having instructions stored therein, wherein the instructions, when executed by a processor of an optical device, causes the processor to perform operations comprising:
converting a received optical signal to a digital electrical signal comprising a plurality of samples having in-phase and quadrature components;
applying a predetermined phase rotation to said samples;
converting the in-phase and quadrature components to amplitude and phase components:
applying an inverse of the predetermined phase rotation to the phase components such that phase range adjusted sample values have phases within ranges suitable for detection; and
performing a first detection process based on the amplitude and phase components of the phase range adjusted sample values.

21. The non-transitory computer readable storage medium as claimed in claim 20 , wherein the predetermined phase rotation is determined in a training process.

22. The non-transitory computer readable storage medium as claimed in claim 20 , the instructions cause the processor to perform further operations comprising retrieving values for the predetermined phase rotation from a look up table, based on a phase of the respective sample.

23. The non-transitory computer readable storage medium as claimed in claim 20 , wherein the first detection process is a Maximum Sequence Likelihood Estimation process.

24. The non-transitory computer readable storage medium as claimed in claim 20 , the instructions cause the processor to perform further operations comprising:
performing a second detection process based on the in-phase and quadrature components of the digital electrical signal; and
selecting a detector output from outputs of the first and second detection processes.

25. The non-transitory computer readable storage medium as claimed in claim 24 , wherein the second detection process is a Maximum Sequence Likelihood Estimation process.

26. The non-transitory computer readable storage medium as claimed in claim 24 , the instructions cause the processor to perform further operations comprising:
selecting the detector output based on respective quality measurements of outputs of the first and second detection processes.

27. The non-transitory computer readable storage medium as claimed in claim 20 , wherein the optical receiver is an optical fibre receiver.

Assignees

• Marsella Domenico
• Secondini Marco
• Magri Roberto
• Forestieri Enrico
• Ericsson Telefon Ab L M

Inventors

• Marsella Domenico
• Secondini Marco
• Magri Roberto
• Forestieri Enrico

Classifications

• H04B10/616 Primary

  Details of the electronic signal processing in coherent optical receivers · CPC title

• H04B10/695

  Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control · CPC title

• H04B10/6971 Primary

  using equalisation · CPC title