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

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

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  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. Coherent -OOFDM Modems Design • CO-OOFDM modem diagram used in numerical simulations, • (dotted line is either fibre or integrated optics) 6

  7. CO-OOFDM Modems - Modelling • Matlab: easy to model the OFDM modem • 32-QAM modulation • 32-QAM detection with additive noise 7

  8. CO-OOFDM Modems – Modelling Screen shots (Coherent OFDM System) (Virtual Photonic Inc.) VPi Software 8

  9. 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

  10. 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

  11. Simulation Parameters

  12. Back-to-Back Performance • Quantization and clipping effects were switched off

  13. Adjacent Symbol Interference (ASI) Symbol Smearing Due to Channel

  14. Cyclic Prefix Inserted in Guard Interval to Suppress Adjacent Channel Interference

  15. 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

  16. Effect of Number of Sub-carriers ON Transmission performance With -6dBm launch power, 64 subcarriers is the optimum number of subcarriers

  17. Effect of Sampling Speed on CD Tolerance Lower sampling speed can increase CD tolerance for a fixed number of subcarriers

  18. Effect of Sampling Speed on Transmission Performance in Fibre Links With the presence of non-linearity, lower sampling speed does not mean higher performance

  19. The Effect of Adaptively Modulated CO-OOFDM on CD Tolerance Adaptively modulating the CO-OOFDM subcarriers increases CD tolerance

  20. 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

  21. Thank you for your attention ! Any questions?

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

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