All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

40Gb/s & 100Gb/s Transport in the WAN

October 10, 2007

Daniel Bihon

Fujitsu Laboratories of America, Inc.

Richardson, Texas

2 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

Introduction

Today’s networks deploy 2.5Gbps and 10Gbps line rates Networks will migrate to 40Gbps (and in the future to 100Gbps) per

wavelength High demand for transmission capacity Higher rate client interfaces

Transmission Quality and Connectivity Challenges associated with 40Gbps and 100Gbps solution:

•OSNR requirement increases by 6dB and 10dB respectively •Chromatic dispersion tolerance decreases respectively (1/16-th and 1/100 of 10G system) •Similarly PMD tolerance decreases (1/4- and 1/10th of 10G system)• Significant increase to OADM filtering

Counter-measures Advanced multi-level modulation formats

•Low symbol rate Tunable/Adaptive CD compensation Forward error correction (FEC) Coherent detection

•PMD and CD tolerance can be further improved

3 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

Light Properties to Modulate

Modulate one or more light properties Intensity modulation (on-off keying):

•Widely used modulation technique for up to 10Gbps transmission•Easy to modulate and easy to detect

Phase modulation:•Well known technique but was not used in optical communications

•Detection is more difficult compared to on-off keying

Polarization modulation:•Relatively new technique

•Detection is difficult

IntensityIntensity Phase (Frequency)Phase (Frequency)

PolarizationPolarization

4 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

medium

poor

medium

poor

medium medium

very good

medium

good

medium

good

good

good

good

good

Optical nonlinearity tolerance

Optical noise tolerance

: Advantage

PMD tolerance

: Disadvantage

NRZ

Optical spectra

Chromatic dispersion tolerance

MZI out

RZ-DPSKTx out

“1” Phase= “0” Phase= 0

OADM filtering tolerance

RZ-DQPSKMZI outTx out

4 values are mapped to phase 0, /2, , 3/2

good(in linear regime)

medium

poor

good

very poor

Duobinary

good

medium

medium

medium

medium

CS-RZ

Frequency (GHz) Frequency (GHz) Frequency (GHz) Frequency (GHz) Frequency (GHz)

40 Gbps Modulation Formats

RZ-DQPSK is attractive in many aspects for high bit-rate transmission

5 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

100+ Gbps Transmission

Transport on multiple wavelengths Requires synchronization of

wavelengths due to differential propagation delay

Manage a band of wavelengths Simpler Tx/Rx, but low fiber

utilization

Transport on single wavelength Complex Tx/Rx Higher spectral efficiency Higher total transport capacity

over a WDM system Transmission impairments

Parallel Serial

Question: How to transport 100GE in DWDM networks?

6 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.

SP- and DP-QPSK for 40 and 100G

Fujitsu Laboratories is doing intensive research on SP- and DP-QPSK

7 All Rights Reserved, ©2007 Fujitsu Laboratories of America, Inc.