Inter-channel interference management for optical super-channels

Patent metadata

Field	Value
Publication number	US-9432124-B2
Application number	US-201414487676-A
Country	US
Kind code	B2
Filing date	Sep 16, 2014
Priority date	Sep 16, 2014
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

The transmission of data from a transmitter to a receiver over an optical super-channel including a set of sub-channels of different frequencies includes partitioning the data into a set of data streams including one data stream for each sub-channel and partitioning each data stream into a set of sub-streams. Each sub-stream of each data stream is encoded with different forward error correction (FEC) codes to produce a set of encoded sub-streams for each data stream, and the set of encoded sub-streams of each data stream are superimposed with different powers to produce a set of encoded data streams. The set of encoded data streams is multiplexed to produce an optical signal transmitted over the set of sub-channels of the optical super-channel.

First claim

We claim:

1. A method for transmission of data from a transmitter to a receiver over an optical super-channel including a set of sub-channels of different frequencies, comprising:
partitioning the data into a set of data streams including one data stream for each sub-channel;
partitioning each data stream into a set of sub-streams;
encoding each sub-stream of each data stream with a corresponding forward error correction (FEC) code to produce a set of encoded sub-streams for each data stream, wherein at least two encoded sub-streams in the set of encoded sub-streams are encoded with different FEC codes;
superimposing the set of encoded sub-streams of each data stream to produce a set of encoded data streams, wherein at least two encoded sub-streams in the set of encoded sub-streams are superimposed with different powers, wherein the superimposing comprises:
determining an inter-channel interference (ICI);
determining a data rates and a power ratio for the data stream according to a spectrum of the ICI and a power of the ICI;
partitioning a first data stream into a first individual sub-stream and a first common sub-stream according to the data rates;
partitioning a second data stream into a second individual sub-stream and a second common sub-stream according to the data rates;
encoding the first individual sub-stream with a first FEC code, encoding the first common sub-stream with a second FEC code, encoding the second individual sub-stream with a third FEC code, encoding the second common sub-stream with a fourth FEC code, wherein the first FEC code is different from the third FEC code, and wherein the second FEC code is different from the fourth FEC code;
superimposing the first individual sub-stream and the first common sub-stream according to the power ratio to produce a first encoded data stream; and
superimposing the second individual sub-stream and the second common sub-stream according to the power ratio to produce a second encoded data stream;

converting and multiplexing the set of encoded data streams to produce an optical signal; and
transmitting the optical signal over the set of sub-channels of the optical super-channel.

2. The method of claim 1 , further comprising:
receiving, de-multiplexing, and converting the optical signal to produce a set of received data streams including one received data stream for each sub-channel, wherein the received data stream includes at least portions of encoded sub-streams transmitted over different sub-channels;
decoding the encoded sub-streams of each received data stream to produce a set of decoded sub-streams; and
combining the decoded sub-streams to produce the data.

3. The method of claim 2 , wherein at least some of the encoded sub-streams of each received data stream are decoded successively.

4. The method of claim 2 , wherein at least some of the encoded sub-streams of each received data stream are decoded jointly.

5. The method of claim 2 , wherein the received data stream for a sub-channel includes at least one inter-channel interference (ICI) sub-stream received due to the ICI and at least one non-ICI sub-stream transmitted over the sub-channel, further comprising:
filtering the ICI sub-stream according to a spectrum of the ICI to equalize an inter-symbol interference (ISI);
decoding the filtered ICI sub-stream to produce a decoded ICI sub-stream; and
decoding the non-ICI sub-stream using the decoded ICI sub-stream.

6. The method of claim 5 , wherein the filtering uses a maximum a posteriori probability (MAP) equalization of ISI of the ICI sub-stream dispersed over L symbols according to a total power of the spectrum of the ICI
Σ k=−L/2 L/2 |h ( k )| 2 ,

wherein h(k) is an impulse response of the ICI sub-stream.

7. The method of claim 1 , further comprising:
filtering the encoded data streams to preserve an inter-channel interference (ICI) during the transmitting and to increase a total power of a spectrum of the ICI optimizing a data rate of the transmitting.

8. The method of claim 1 , wherein the first, the second, the third, and the fourth FEC codes are unique and determined based on the spectrum of the ICI.

9. The method of claim 1 , further comprising:
filtering the first and the second encoded data streams according to the spectrum of the ICI using a non-square-root raised cosine (NS-RRC) filter preserving the ICI during the transmitting.

10. The method of claim 9 , wherein the filtering comprises:
determining iteratively roll-off factors and exponents of the filtering until a termination condition is met, wherein an iteration includes:
determining data rates for the spectrum and the power of the ICI;
adjusting the roll-off factors and exponents of the filtering using gradient update increasing the data rates.

11. The method of claim 1 , further comprising:
determining a spectrum and a power of an inter-channel interference (ICI) using frequency spacing between the sub-channels; and
filtering the encoded data streams to produce the spectrum of the ICI during the transmitting.

12. The method of claim 1 , further comprising:
encoding at least some of the sub-streams of different data streams cooperatively based on a nested joint FEC code;
superposing at least some of the encoded sub-streams of different data streams using a dirty paper coding to reduce an inter-channel interference (ICI).

13. A system for transmission of data over an optical super-channel including a set of sub-channels of different wavelengths, comprising:
a data de-multiplexer (DDM) for splitting the data into a set of data streams including one data stream for each sub-channel;
a set of sub-channel encoders including one sub-channel encoder for each data stream for producing a set of encoded data streams, wherein each sub-channel encoder is configured for partitioning a data stream into sub-streams, encoding each sub-stream with different forward error correction (FEC) codes, and superimposing the encoded sub-streams with different powers to produce an encoded data stream of the set of encoded data streams, wherein the superimposing comprises:
determining an inter-channel interference (ICI);
determining a data rates and a power ratio for the data stream according to a spectrum of the ICI and a power of the ICI;
partitioning a first data stream into a first individual sub-stream and a first common sub-stream according to the data rates;
partitioning a second data stream into a second individual sub-stream and a second common sub-stream according to the data rates;
encoding the first individual sub-stream with a first FEC code, encoding the first common sub-stream with a second FEC code, encoding the second individual sub-stream with a third FEC code, encoding the second common sub-stream with a fourth FEC code, wherein the first FEC code is different from the third FEC code, and wherein the second FEC code is different from the fourth FEC code;
superimposing the first individual sub-stream and the first common sub-stream according to the power ratio to produce a first encoded data stream; and

superimposing the second individual sub-stream and the second common sub-stream according to the power ratio to produce a second encoded data stream;
a set of transmitter optics for generating a set of optical wavelengths corresponding to the set of encoded data streams; and
an optical wavelength multiplexer (WM) for multiplexing the set of optical wavelengths to produce an optical signal and transmitting the optical signal over the sub-channels of the optical super-channel.

14. The system of claim 13 , wherein at least some of the sub-channel

Assignees

• Mitsubishi Electric Res Laboratories Inc

Inventors

• Koike-Akino Toshiaki
• Kojima Keisuke
• Millar David S
• Parsons Kieran

Classifications

• H04B10/516 Primary

  Details of coding or modulation · CPC title

• H04B10/2504

  Electricity · mapped topic

• H04L1/0041 Primary

  Arrangements at the transmitter end · CPC title

• H04L25/03343

  Arrangements at the transmitter end · CPC title

• H04B10/506

  Multiwavelength transmitters · CPC title