Method and apparatus for deploying forward error correction in optical transmission networks and the deployment of photonic integrated circuit (PIC) chips with the same

• US 7,570,671 B2
• Filed: 11/12/2003
• Issued: 08/04/2009
• Est. Priority Date: 11/20/2002
• Status: Active Grant

• Current Assignee: Infinera Corp.
• Original Assignee: Infinera Corp.
• Inventors: Sridharan, Satish K., Perkins, Drew D., Jarchi, Michael D.
• Primary Examiner(s): PHAM, BRENDA H
• Application Number:
  US10/712,732
• Publication Number:
  US 20040096213A1
• Time in Patent Office: 2,092 Days
• Field of Search: 370/535, 370/395.5, 370/465, 370/466, 370/471, 370/474
• US Class Current: 370/535
• CPC Class Codes: H04B 10/00 Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end

Abstract

An apparatus and method for uniformly sharing across a plurality of channel signals FEC coding gain which may be achieved through FEC encoding of a higher baud rate electrical data signal or through multiplexed or combined electrical data signals from multiple data sources prior to their subsequent demultiplexing and separate generation into optical channel signals which are multiplexed and launched onto an optical transmission medium. The optical signal generation is achieved through reverse multiplexing of the higher baud rate data signal or of the multiplexed, FEC encoded plural data signals. Effectively, the coding gain power of the FEC encoder is spread over all the signal channels so that each channel can potentially benefit from performance above the average coding gain thereby increasing the coding gain of the worst noise signal channel and correspondingly reducing its BER at the receiver so that, now, the combined multiple channel signals may be propagated further along the optical transmission medium before signal interception is required, such as required channel signal regeneration (3R). By coding gain averaging, the coding gain is taken from the lesser noise affected channels and spread over all the channels so the higher noised ridden channels obtain an effective increase in coding gain which corresponds to a higher reduction in BER at the optical receiver terminal.

Claims

1. A communication method, comprising the steps of:

FEC encoding a signal in a first domain, the signal being a first domain signal;

demultiplexing the FEC encoded first domain signal into N segments in the first domain;

inserting data into each of the N segments, the data indicating a start location associated with said each of the N segments;

converting the N segments in the first domain into N segments in a second domain; and

combining the second domain N segments into a combined signal in the second domain for transport on a transmission medium,

wherein the first domain is an electrical domain and the second domain is an optical domain.

2. The method of claim 1 wherein the first domain signal is at a first baud rate and the first and second domain signal N segments are at second baud rate.

3. The method of claim 2 wherein the first baud rate is higher than the second baud rate.

4. The method of claim 2 wherein the second baud rate is higher than the first baud rate.

5. The method of claim 2 wherein the first and second baud rates are the same.

6. The method of claim 1 wherein the where the step of converting comprises a monolithic photonic integrated circuit (PIC) having integrated N signal channels for converting a respective signal segment in the first domain into a signal segment in the second domain and multiplexing the N channel signal segments to form the combined signal.

7. A method for deploying forward error correction (FEC) in transmission networks, comprising the steps of:

FEC encoding a first multiplexed signal comprising M signals in a first domain at a first baud rate;

demultiplexing the encoded multiplexed signal of the first domain into N signals in the first domain at a second baud rate, each of the N signals carrying a plurality of segments;

inserting data into each of the plurality of segments, the data indicating a start location of said each of the plurality of segments;

converting the first domain N signals into N signals in a second domain; and

combining the second domain N signals at the second baud rate into a combined signal for transport on a transmission medium,

wherein the first domain is an electrical domain and the second domain is an optical domain.

8. The method of claim 7 wherein the first baud rate is higher than the second baud rate.

9. The method of claim 7 wherein the second baud rate is higher than the first baud rate.

10. The method of claim 7 wherein the first and second baud rates are the same.

11. The method of claim 7 wherein the where the step of converting comprises a monolithic photonic integrated circuit (PIC) having integrated N signal channels for converting a respective N signal in the first domain into a N signal in the second domain and multiplexing the N channel signals to form the combined signal.

12. A method for deploying forward error correction (FEC) in transmission networks, comprising the steps of:

decombining an FEC encoded combined signal in a first domain and received from a transmission medium into N segments in the first domain;

converting the N segments in the first domain into N segments in a second domain;

detecting a start location of each of the N segments based on data included in the N segments;

multiplexing the second domain N segments into a multiplexed M signal comprising M signals in the second domain; and

FEC decoding the first domain multiplexed M signal,

wherein the first domain is an optical domain and the second domain is an electrical domain.

13. The method of claim 12 wherein the first domain signal is at a first baud rate and each of the second domain signal N segments are at a second baud rate.

14. The method of claim 13 wherein the first baud rate is higher than the second baud rate.

15. The method of claim 13 wherein the second baud rate is higher than the first baud rate.

16. The method of claim 13 wherein the first and second baud rates are the same.

17. The method of claim 12 wherein the where the step of converting comprises a monolithic photonic integrated circuit (PIC) having integrated N signal channels converting a respective signal segments in the first domain into signal segment a in the second domain and multiplexing the N channel signal segments to form the combined signal.

18. A method for deploying forward error correction (FEC) in transmission networks, comprising the steps of:

providing an FEC encoded combined signal comprising a plurality of M signals combined in a first domain at a second baud rate;

decombining the FEC encoded combined signal of M signals in the first domain into N signals in the first domain;

converting the N signals in the second domain into N signals in a second domain, each of the N signals including a plurality of segments;

inserting data into each of the plurality of segments, the data indicating a start location of said each of the plurality of segments;

multiplexing the second domain N signals into a second domain multiplexed M signal of M signals at a second baud rate; and

FEC decoding the second domain multiplexed M signal,

wherein the first domain is an optical domain and the second domain is an electrical domain.

19. The method of claim 18, wherein the plurality of M signals is a first plurality of M signals, the method further comprising the step of demultiplexing the FEC decoded multiplexed M signal into a second plurality of M signals and forwarding each of the plurality of M signals to a corresponding one of data sinks.

20. The method of claim 18 wherein the first baud rate is higher than the second baud rate.

21. The method of claim 18 wherein the second baud rate is higher than the first baud rate.

22. The method of claim 18 wherein the first and second baud rates are the same.

23. The method of claim 18 wherein the where the step of converting comprises a monolithic photonic integrated circuit (PIC) having integrated N signal channels converting a respective N signal in the second domain into an N signal in the first domain and multiplexing the N channel signals to form the combined signal.

24. A transmission network having a transmitter side and a receiver side, comprising:

said transmitter side comprising;

a plurality data sources for providing a multiplexed M signal including M signals in a first domain and modulated at a first baud rate;

an FEC encoder for encoding the multiplexed M signal;

a demultiplexer circuit that converts the encoded multiplexed M signal into N signal segments, each of the N signal segments being at a second baud rate in the first domain and including data, the data indicating a start location of said each of the N signal segments;

a first converter for converting the N signal segments in the first domain into N signal segments of a second domain; and

a combiner for combining the N signal segments of a second domain into a combined signal in the second domain for transport on a transmission medium;

said receiver side comprising;

a decombiner for receiving said combined signal in the second domain from the transmission medium and decombing said combined signal into N segments in the second domain

a second converter for converting the N segments in the second domain into N segments in the first domain;

a multiplexer for converting the first domain N segments at a first baud rate into a multiplexed M signal at a second baud rate comprising said first domain M signals each at the first baud rate; and

an FEC decoder for decoding the multiplexed M signal,

wherein the first domain is an electrical domain and the second domain is an optical domain.

25. The transmission network of claim 24 wherein said first converter on said transmitter side comprises a monolithic photonic integrated circuit (PIC) having N signal channels for converting a respective N signal segment in the first domain into a respective N signal segment in the second domain and multiplexing the N channel signal segments to form the combined signal.

26. The transmission network of claim 25 wherein said first domain comprises an electrical domain and said second domain comprises an optical domain;

said monolithic photonic integrated circuit (PIC) comprises an array of N laser sources, an array of N optic-electric modulators and an optical combiner to combine N optical signal segments into said combined signal for transport on said transmission medium;

said transmission medium comprising an optical fiber.

27. The transmission network of claim 26 wherein said laser sources comprise an array of DFB lasers or DBR lasers.

28. The transmission network of claim 26 wherein said electro-optic modulators comprise an array of electro-absorption modulators or Mach-Zehnder modulators.

29. The transmission network of claim 26 wherein said optical combiner comprises an arrayed waveguide grating (AWG) or an Echelle grating.

30. The transmission network of claim 24 wherein said second converter on said receiver side comprises a monolithic photonic integrated circuit (PIC) comprising a demultiplexer for decombining the combined signal into N signal segments and converting a respective N signal segment in the second domain into a respective N signal segment in the first domain.

31. The transmission network of claim 30 wherein said first domain comprises an electrical domain and said second domain comprises an optical domain;

said monolithic photonic integrated circuit (PIC) comprises an optical decombiner for decombing said combined signal into N optical signal segments and an array of photodetectors for each converting a respective optical signal segment into a respective electrical signal segment.

32. The transmission network of claim 30 wherein said decombiner comprises an arrayed waveguide grating (AWG) or an Echelle grating.

33. The transmission network of claim 30 wherein said array of photodetectors comprise an array of PIN photodiodes or an array of avalanche photodiodes.