1 Improving Chromatic Dispersion Tolerance in Long-Haul Fibre Links using Coherent OOFDM M. A....
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Transcript of 1 Improving Chromatic Dispersion Tolerance in Long-Haul Fibre Links using Coherent OOFDM M. A....
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Improving Chromatic Dispersion Tolerance in Long-Haul Fibre Links
using Coherent OOFDM
M. A. Jarajreh, Z. Ghassemlooy, and W. P. NgM. A. Jarajreh, Z. Ghassemlooy, and W. P. Ng
Optical Communications Research GroupOptical Communications Research Grouphttp://soe.unn.ac.uk/ocr/
School of Computing, Engineering and Information School of Computing, Engineering and Information SciencesSciences
University of Northumbria at Newcastle, University of Northumbria at Newcastle, UKUK
Contents OFDM and Optical OFDM (OOFDM) Applications of OOFDM Modems Coherent -OOFDM (CO-OOFDM)Modems Design CO-OOFDM Modems - Modelling (Matlab and VPi) Motivation Results
Back-to-Back Performance Back-to-Back Performance Effect of Number of Sub-carriers and CP on CD ToleranceEffect of Number of Sub-carriers and CP on CD Tolerance Effect of Number of Sub-carriers ON Transmission performanceEffect of Number of Sub-carriers ON Transmission performance Effect of Sampling Speed on CD ToleranceEffect of Sampling Speed on CD Tolerance Effect of Sampling Speed on Transmission Performance in Fibre LinksEffect of Sampling Speed on Transmission Performance in Fibre Links The Effect of Adaptively Modulated CO-OOFDM on CD ToleranceThe Effect of Adaptively Modulated CO-OOFDM on CD Tolerance
Conclusions
OFDM
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Orthogonal Frequency Division Multiplexing (OFDM)
Harmonically related narrowband sub-carriers The sub-carriers spaced by 1/Ts The peak of each sub-carrier coincides with trough of
other sub-carriers
Splitting a high-speed data stream into a number of low-speed streams
Different sub-carrier transmitted simultaneously
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What is OOFDM By introducing OFDM in the optical domain, Optical OFDM
(OOFDM) was generated
Advantages of OOFDM Cost-effective High-speed Excellent flexibility and robustness
Optical OFDM
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Access and local area networks
IMDD modems
Future high-capacity long-haul networks Coherent modems
Combating optical fibers dispersion and polarization mode dispersion
Applications of OOFDM Modems
Coherent -OOFDM Modems Design
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CO-OOFDM modem diagram used in numerical simulations,
(dotted line is either fibre or integrated optics)
CO-OOFDM Modems - Modelling Matlab: easy to model the OFDM modem
32-QAM modulation
32-QAM detection with additive noise
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-5 -4 -3 -2 -1 0 1 2 3 4 5-5
-4
-3
-2
-1
0
1
2
3
4
5
REAL
IMA
G
-8 -6 -4 -2 0 2 4 6 8-8
-6
-4
-2
0
2
4
6
8
REAL
IMA
G
CO-OOFDM Modems – Modelling
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Screen shots (Coherent OFDM System)
(Virtual Photonic Inc.) VPi Software
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• The achievable signal transmission capacity of an Optical Orthogonal Frequency Division Multiplexing (OOFDM) modem over Single Mode Fibre (SMF) links is affected considerably by:• Fibre Chromatics Dispersion (CD)
• Number of sub-carriers• Cyclic prefix
• Fibre nonlinearity• Optical launch power
• Numerical simulations are undertaken to investigate the above-mentioned effects on the system performance of Coherent OOFDM
Motivation
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Results
Work will be presented
Back-to-back Performance
Effect of number of subcarriers and Cyclic Prefix (CP) on Chromatic Dispersion (CD) Tolerance
Effect of sampling speed on CD tolerance
The result of utilizing AM-CO-OOFDM on CD tolerance
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Simulation ParametersParameters Values
No. of subcarriers 64Wavelength 1550 nmLight source Laser diode
Photodetector PINPhotodetector responsivity
0.9
Fibre span 80 kmChromatic dispersion 17 ps/nm/km
Fibre loss 0.2 dB/kmADC/DAC
- sampling rate- clipping ratio- quantization
12.5 GS/s13 dB10 bits
Data rates- DBPSK- DQPSK- 16-QAM- 32-QAM- 64-QAM
- 128-QAM- 256-QAM
10 Gb/s20 Gb/s 40 Gb/s50 Gb/s60 Gb/s70 Gb/s80 Gb/s
Low pass filter order and 3-dB bandwidth
2nd & 6.5GHz
EDFA spanEDFA gain
EDFA noise figure
80km16 dB6 dB
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Back-to-Back Performance
Quantization and clipping effects were switched off
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30OSNR (dB)
BE
R
256 QAM
64QAM
32QAM16QAMDQPSK
128QAMDBPSK
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Effect of Number of Sub-carriers and CP on CD Tolerance
Cyclic prefix is more effective if compared with the number of subcarriers in combating dispersion
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Effect of Number of Sub-carriers ON Transmission performance
With -6dBm launch power, 64 subcarriers is the optimum number of subcarriers
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Effect of Sampling Speed on CD Tolerance
Lower sampling speed can increase CD tolerance for a fixed number of subcarriers
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Effect of Sampling Speed on Transmission Performance in Fibre
Links
With the presence of non-linearity, lower sampling speed does not mean higher performance
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The Effect of Adaptively Modulated CO-OOFDM on CD Tolerance
Adaptively modulating the CO-OOFDM subcarriers increases CD tolerance
2020
Conclusions
For coherent OOFDM modems, for a given modulation format, increasing the number of sub-carriers or cyclic prefix length, increases dispersion tolerance effectively
A longer length CP is more effective in combating fibre dispersion than use of large number of sub-carriers
For coherent OOFDM Modem the optimum launched power is -6 dBm
For a given number of subcarriers sampling speed can increase the system dispersion tolerance
Utilizing CO-AMOOFDM increases the system tolerance to CD
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Email: Email: [email protected]
Web: Web: http://soe.unn.ac.uk/ocr/
Tel: 00 44 191 227 4902Tel: 00 44 191 227 4902
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