Non-linear distortion compensator, method of compensating non-linear distortion, and optical receiver

Patent metadata

Field	Value
Publication number	US-9363014-B2
Application number	US-201414461167-A
Country	US
Kind code	B2
Filing date	Aug 15, 2014
Priority date	Sep 11, 2013
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A non-linear distortion compensator includes: a non-linear distortion calculator that calculates non-linear distortion occurred in a received optical signal based on signal information after recovery of a carrier wave in a carrier wave phase recovery which recovers a phase of the carrier wave of the received optical signal; and a non-linear compensator that compensates the non-linear distortion of the received optical signal based on the non-linear distortion obtained by the non-linear distortion calculator.

First claim

What is claimed is:

1. A non-linear distortion compensator comprising:
a discriminator configured to discriminate signal information after recovery of a carrier wave in a carrier wave phase recovery being configured to recover a phase of the carrier wave of a received optical signal as a specific symbol according to a modulation format of the received optical signal, the modulation format being a phase modulation format or a quadrature amplitude modulation format;
a non-linear distortion calculator configured to receive the result of the discrimination from the discriminator, and to calculate non-linear distortion occurred in the received optical signal based on the signal information after recovery of the carrier wave; and
a non-linear compensator configured to compensate the non-linear distortion of the received optical signal based on the non-linear distortion obtained by the non-linear distortion calculator,
wherein the received optical signal is a signal with an error correction code, and
wherein the discriminator further comprises:
a soft decision discriminator configured to perform soft decision on the signal information;
a soft decision error corrector configured to perform error correction on a soft decision result obtained by the soft decision discriminator based on the error correction code;
a hard decision discriminator configured to perform hard decision on an error correction result obtained by the soft decision error corrector; and
a hard decision error corrector configured to perform error correction on a hard decision result obtained by the hard decision discriminator based on the error correction code.

2. The non-linear distortion compensator according to claim 1 ,
wherein the discriminator further comprises:
a symbol mapper configured to map an error correction result obtained by the hard decision corrector to the specific symbol.

3. The non-linear distortion compensator according to claim 1 ,
wherein the discriminator configured to output a symbol as the result of the discrimination, the symbol being at least one of symbols set on a complex plane as a discriminated symbol and a distance of the discriminated symbol from the input signal information on the complex plane being in minimum.

4. The non-linear distortion compensator according to claim 3 ,
wherein a multivalued level of the symbol set on the complex plane is lower than a multivalued level of the received optical signal.

5. A method of compensating non-linear distortion, the method comprising:
recovering a phase of a carrier wave of a received optical signal;
discriminating signal information after the recovery of a carrier wave as a specific symbol according to a modulation format of the received optical signal, the modulation format being a phase modulation format or a quadrature amplitude modulation format;
calculating non-linear distortion occurred in the received optical signal based on the signal information after the recovery of the carrier wave; and
compensating the non-linear distortion of the received optical signal based on the non-linear distortion obtained by the calculation,
wherein the received optical signal is a signal with an error correction code, and
wherein the discriminating further comprises:
performing soft decision on the signal information;
performing error correction on a soft decision result obtained by the soft decision discriminator based on the error correction code;
performing hard decision on an error correction result obtained by the soft decision error corrector; and
performing error correction on a hard decision result obtained by the hard decision discriminator based on the error correction code.

6. An optical receiver comprising:
a carrier wave phase recovery configured to recover a phase of a carrier wave of a received optical signal; and
the non-linear distortion compensation apparatus according to claim 1 .

Assignees

• Fujitsu Ltd

Inventors

• Oyama Tomofumi
• Tanimura Takahito
• Nakashima Hisao

Classifications

• H04B10/2543 Primary

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

• H04B10/6165

  Estimation of the phase of the received optical signal, phase error estimation or phase error correction · CPC title

• H04L1/0047

  Decoding adapted to other signal detection operation (in conjunction with sequence estimation or equalization H04L25/03286) · CPC title

• H04B10/0795

  Performance monitoring; Measurement of transmission parameters · CPC title

• H04B10/6163

  Compensation of non-linear effects in the fiber optic link, e.g. self-phase modulation [SPM], cross-phase modulation [XPM], four wave mixing [FWM] · CPC title