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Improving Chromatic Dispersion Tolerance in Long-Haul Fibre Links using Coherent OOFDM. M. A. Jarajreh, Z. Ghassemlooy, and W. P. Ng Optical Communications Research Group http://soe.unn.ac.uk/ocr/ School of Computing, Engineering and Information Sciences

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slide1

Improving Chromatic Dispersion Tolerance in Long-Haul Fibre Links using Coherent OOFDM

M. A. Jarajreh, Z. Ghassemlooy, and W. P. Ng

Optical Communications Research Group

http://soe.unn.ac.uk/ocr/

School of Computing, Engineering and Information Sciences

University of Northumbria at Newcastle,

UK

contents
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
    • Effect of Number of Sub-carriers and CP on CD Tolerance
    • Effect of Number of Sub-carriers ON Transmission performance
    • Effect of Sampling Speed on CD Tolerance
    • Effect of Sampling Speed on Transmission Performance in Fibre Links
    • The Effect of Adaptively Modulated CO-OOFDM on CD Tolerance
  • Conclusions
slide3
OFDM
  • 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

3

slide4

Optical OFDM

  • 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
slide5

Applications of OOFDM Modems

  • Access and local area networks
    • IMDD modems
  • Future high-capacity long-haul networks
    • Coherent modems
      • Combating optical fibers dispersion and polarization mode dispersion
coherent oofdm modems design
Coherent -OOFDM Modems Design
  • CO-OOFDM modem diagram used in numerical simulations,
  • (dotted line is either fibre or integrated optics)

6

co oofdm modems modelling
CO-OOFDM Modems - Modelling
  • Matlab: easy to model the OFDM modem
    • 32-QAM modulation
    • 32-QAM detection with additive noise

7

co oofdm modems modelling1
CO-OOFDM Modems – Modelling

Screen shots (Coherent OFDM System)

(Virtual Photonic Inc.) VPi Software

8

slide9

Motivation

  • 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
slide10

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
slide12

Back-to-Back Performance

  • Quantization and clipping effects were switched off
slide15

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

slide16

Effect of Number of Sub-carriers ON Transmission performance

With -6dBm launch power, 64 subcarriers is the optimum number of subcarriers

slide17

Effect of Sampling Speed on CD Tolerance

Lower sampling speed can increase CD tolerance for a fixed number of subcarriers

slide18

Effect of Sampling Speed on Transmission Performance in Fibre Links

With the presence of non-linearity, lower sampling speed does not mean higher performance

slide19

The Effect of Adaptively Modulated CO-OOFDM on CD Tolerance

Adaptively modulating the CO-OOFDM subcarriers increases CD tolerance

slide20

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
slide22

Future Contact

  • Email: Mutsam.jarajreh@Northumbria.ac.uk
  • Web: http://soe.unn.ac.uk/ocr/
  • Tel: 00 44 191 227 4902