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OTDR-based fault surveillance method for tree-structured passive optical networks

OTDR-based fault surveillance method for tree-structured passive optical networks. K. Yuksel, S. Dupont, L. Robette, D. Hamoir, J.-C. Froidure Multitel asbl, Mons, Belgium. Agenda. Introduction Why monitoring? Why OTDR technique? What difficulties due to p-2-mp architecture? Background

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OTDR-based fault surveillance method for tree-structured passive optical networks

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  1. OTDR-based fault surveillance method for tree-structured passive optical networks K. Yuksel, S. Dupont, L. Robette, D. Hamoir, J.-C. Froidure Multitel asbl, Mons, Belgium

  2. Agenda • Introduction • Why monitoring? • Why OTDR technique? • What difficulties due to p-2-mp architecture? • Background • Operation Principle • Experimental Study and Results • Conclusions e-Photon Project, Summer School 22, 23, 24 September 2004

  3. Introduction Motivations for Physical Layer Monitoring • Financial Losses • Direct  Service interruption • Indirect  Bad impact • Time = Money (« dispatch a repair crew?, where? With what equipment? • QoS Criteria • Physical layer reliability  Service availability and continuity • Bit Rate Increase • FITL systems  Service integration (voice, data, video) e-Photon Project, Summer School 22, 23, 24 September 2004

  4. Introduction OTDR and Network Monitoring • Fast and accurate localisation of the fault • Implementation of automatic test systems • In-service monitoring is possible by using different wavelengths for the OTDR (monitoring) and the data signals Time saved From Nettest e-Photon Project, Summer School 22, 23, 24 September 2004

  5. Introduction Problems Due to Point-to-Multipoint Arch. • Identification of faulty branch • Required high dynamic range and resolution • Fault quantisation • Fault can be masked if at the same position with the end of another branch e-Photon Project, Summer School 22, 23, 24 September 2004

  6. Published Solutions e-Photon Project, Summer School 22, 23, 24 September 2004

  7. Method Reflective Switchable Element (RSE) • Possible states: • Reflective state (presence of the reflection): minimum attenuation • Absorbent state (absence of the reflection): maximum attenuation e-Photon Project, Summer School 22, 23, 24 September 2004

  8. Method Fault detection and Localisation • Fault indication? • Significant difference in the end reflection peak? • Which branch? • Branch under monitoring • Fault location? • Backscattering signature analysis Only one RSE is in « ON » state at a time e-Photon Project, Summer School 22, 23, 24 September 2004

  9. Method Fault quantification [Kapron et al., OFMC’92] [Caviglia et al.,EFOC&N’92] Calculated Fault Loss: • Laf :Apparent fault loss • Lf : Calculated fault loss • N: Number of branches • Rf: Calculated fault reflectance • S: Intrinsic splitting loss • B: single-mode fiber backscatter coefficient normalized to 1ns pulse duration • Hf : Pulse height above the backscatter [dB] • D: Pulse duration [ns] Calculated Fault Reflectance: e-Photon Project, Summer School 22, 23, 24 September 2004

  10. Experimental Study Test Set-Up • Continuous monitoring • No user interaction • Pulse width: 275ns (trade-off between the dynamic range and the spatial resolution) • Monitoring wavelength: 1625 nm (in-service monitoring) e-Photon Project, Summer School 22, 23, 24 September 2004

  11. 13.2km 15.6km 18.4km 20.8km 13.2km 13.2km 13.2km 15.6km 15.6km 15.6km 18.4km 18.4km 18.4km 20.8km 20.8km 20.8km Fault1 Fault2 Fault1 Fault1 Fault2 Branch-1 Branch-1 Branch-1 Branch-1 Branch-2 Branch-2 Branch-2 Branch-2 Fault3 10.4km Branch-3 Branch-3 Branch-3 Branch-3 10.4km 10.4km 10.4km B30 B34 Branch-4 Branch-4 Branch-4 Branch-4 B40 B44 B30 B10 B20 B10 B11 B11 B12 B12 B22 B32 B13 B13 B14 B34 B24 B14 Results Case-1: • Fault1: Reflective fault in Branch-1 • Fault2: Fault at the end of Branch-1 • Fault3: Break in Branch-3 e-Photon Project, Summer School 22, 23, 24 September 2004

  12. Results Case-1 FAULT-1: Reflective fault at 15.6km Network under monitoring e-Photon Project, Summer School 22, 23, 24 September 2004

  13. Results Case-1 Network under monitoring FAULT-1: Reflective fault at 15.6km Presentation of results e-Photon Project, Summer School 22, 23, 24 September 2004

  14. Results Case-1 Network under monitoring FAULT-2: Fault at the end of Branch-1 e-Photon Project, Summer School 22, 23, 24 September 2004

  15. Results Case-1 Network under monitoring FAULT-2: Fault at the end of Branch-1 Presentation of results e-Photon Project, Summer School 22, 23, 24 September 2004

  16. Results Case-1 FAULT-3: Break in Branch-3 Network under monitoring • Fault-1 and Fault-3 are at the same location • Fault-3 can be detected thanks to the updating of reference trace e-Photon Project, Summer School 22, 23, 24 September 2004

  17. Results Case-1 FAULT-3: Break in Branch-3 Network under monitoring Presentation of results e-Photon Project, Summer School 22, 23, 24 September 2004

  18. 13.2km 13.2km 13.2km 13.2km 15.6km 15.6km 15.6km 15.6km 18.4km 18.4km 18.4km 18.4km 20.8km 20.8km 20.8km 20.8km Fault3 Fault2 Fault2 Branch-1 Branch-1 Branch-1 Branch-1 Branch-2 Branch-2 Branch-2 Branch-2 Fault1 Fault1 Fault1 Branch-3 Branch-3 Branch-3 Branch-3 10.4km 10.4km 10.4km 10.4km Branch-4 Branch-4 Branch-4 Branch-4 B40 B44 B10 B30 B20 B11 B32 B22 B12 B13 B34 B24 B14 Results Case-2: • Fault1: Non-reflective fault in Branch-3 at the splitter output • Fault2: Non-reflective fault in Branch-1 at the splitter output • Fault3: Break in Branch-1 e-Photon Project, Summer School 22, 23, 24 September 2004

  19. Results Case-2 FAULT-1: e-Photon Project, Summer School 22, 23, 24 September 2004

  20. Results Case-2 FAULT-2: Network under monitoring e-Photon Project, Summer School 22, 23, 24 September 2004

  21. Results Case-2 FAULT-3: Network under monitoring e-Photon Project, Summer School 22, 23, 24 September 2004

  22. Conclusion OTDR-Based Fault Surveillance Method • Capability of working at networks with branches of equal length • Application possible to multi-staged PONs • Capability of handling realistic cases in installed networks including several faults in the same branch or several faults in different branches at the same position e-Photon Project, Summer School 22, 23, 24 September 2004

  23. Thanks for your attention • Questions? • Remarks? Multitel asbl, Mons, Belgium Monitoring@multitel.be e-Photon Project, Summer School 22, 23, 24 September 2004

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