Optical transmission method and optical transmission system

Patent metadata

Field	Value
Publication number	US-10128940-B2
Application number	US-201515302382-A
Country	US
Kind code	B2
Filing date	Apr 16, 2015
Priority date	May 8, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

An optical transmission method wavelength-multiplexing and transmitting multiple channels including data. The data are composed of data areas independent between the channels and data areas non-independent between the channels. Data patterns of the data areas non-independent between the channels are variable. The data patterns of the data areas non-independent between the channels are set so that in time periods of the non-independent data areas on an optical transmission section, a time period during which polarization states of the multiple channels are correlated in the optical transmission section has a length such that an error rate is less than or equal to a threshold value, the error rate being determined from a temporal distribution of bit errors obtained from a result of error decision after demodulation in an optical receiver.

First claim

The invention claimed is:

1. An optical transmission method for wavelength-multiplexing and transmitting a plurality of channels including data, the plurality of channels having polarization states, the data being composed of independent data areas and non-independent data areas, the independent data areas including data having values that are independent between the channels and the non-independent data areas including data having values that are not independent between the channels, the method including:
performing data pattern processing for making data patterns of the non-independent-data areas variable,
setting the polarization states of the plurality of channels,
transmitting an optical signal on an optical transmission section,
receiving the optical signal at an optical receiver, and
setting the data patterns of the non-independent data areas so that in time periods of the non-independent data areas on the optical transmission section, a time period during which polarization states of the plurality of channels are correlated in the optical transmission section has a length such that an error rate is less than or equal to a threshold value, the error rate being determined from a temporal distribution of bit errors obtained from a result of error decision after demodulation in the optical receiver.

2. The optical transmission method of claim 1 , wherein in each of the plurality of channels, data are assigned to two or more polarization states.

3. The optical transmission method of claim 1 , wherein data pattern processing is performed differently between the plurality of channels to make the data patterns of the non-independent data areas variable.

4. The optical transmission method of claim 1 , wherein the data are framed data.

5. The optical transmission method of claim 1 , wherein the data are modulated according to polarization multiplexing binary phase-shift keying (BPSK), polarization multiplexing quadrature phase-shift keying (QPSK), or polarization multiplexing m-ary quadrature amplitude modulation.

6. The optical transmission method of claim 1 , wherein the data patterns of the non-independent data areas can be changed by switching between a fixed pattern and a random pattern random in each of polarization components and between the polarization components.

7. The optical transmission method of claim 6 , wherein the random pattern is a mixed pattern including a fixed pattern as a part of the random pattern.

8. The optical transmission method of claim 7 , wherein the mixed pattern is composed of a combination of one or more fixed patterns and one or more random patterns.

9. The optical transmission method of claim 6 , wherein the random pattern is generated by performing distribution or cyclic shift of one or more pseudo random patterns generated by one or more generator polynomials, and an amount of the cyclic shift is changed depending on a channel number.

10. The optical transmission method of claim 7 , wherein in the mixed pattern, in either one of the polarization components of the channel, a proportion of the random pattern is greater than a proportion of the fixed pattern.

11. The optical transmission method of claim 7 , wherein in the mixed pattern, a combination ratio of the fixed pattern and the random pattern is variable.

12. The optical transmission method of claim 8 , wherein at least one of the fixed pattern and the random pattern constituting the mixed pattern is composed of two or more types of patterns.

13. The optical transmission method of claim 6 , wherein the data patterns of the non-independent data areas are changed depending on a signal communication state.

14. The optical transmission method of claim 6 , wherein the data patterns of the non-independent data areas are changed with lapse of time.

15. The optical transmission method of claim 6 , wherein a number of channels on which data patterns including the fixed pattern are transmitted is limited to an arbitrary number or less.

16. An optical transmission system capable of wavelength-multiplexing and transmitting a plurality of channels including data, the plurality of channels having polarization states, the data being composed of independent data areas and non-independent data areas, the independent data areas including data having values that are independent between the channels and the non-independent data areas including data having values that are not independent between the channels, the optical transmission system comprising:
a first optical transmission device including a data pattern processor that performs data pattern processing for making data patterns variable on the non-independent data areas, and a polarization multiplexing optical modulator for setting the polarization states;
an optical transmission section including an optical fiber and an optical repeater;
and a second optical transmission device including an optical receiver that receives an optical signal transmitted through the optical transmission section,
wherein the data pattern processor sets the data patterns of the non-independent data areas so that in time periods of the non-independent data areas on the optical transmission section, a time period during which polarization states of the plurality of channels are correlated in the optical transmission section has a length such that an error rate is less than or equal to a threshold value, the error rate being determined from a temporal distribution of bit errors obtained from a result of error decision after demodulation in the optical receiver.

17. The optical transmission system of claim 16 , wherein in each of the plurality of channels, the first optical transmission device assigns data to two or more polarization states.

18. The optical transmission system of claim 16 , wherein the first optical transmission device switches the data patterns of the non-independent data areas between a fixed pattern and a random pattern random in each of polarization components and between the polarization components, by the data pattern processing.

Assignees

• Mitsubishi Electric Corp

Inventors

• Goto Hiroki
• Yoshida Tsuyoshi
• Onohara Kiyoshi
• Sugihara Takashi
• Kubo Kazuo
• Kobayashi Tatsuya
• Matsuda Keisuke
• Binkai Masashi

Classifications

• H04J14/06 Primary

  Polarisation multiplex systems · CPC title

• H04B10/6166

  Polarisation demultiplexing, tracking or alignment of orthogonal polarisation components · CPC title

• H04B10/2572

  due to forms of polarisation-dependent distortion other than PMD · CPC title

• H04B10/50

  Transmitters · CPC title

• H04B10/2543

  due to fibre non-linearities, e.g. Kerr effect · CPC title