SUCCESS-DWA: A Highly Scalable and Cost-Effective Optical Access Network

1. SUCCESS-DWA: A Highly Scalable and Cost-Effective Optical Access Network Speaker：Tse-Hsien Lin Teacher：Ho-Ting Wu Date：93.10.21

2. Outline • Overview • SUCCESS-DWA PON Architecture • Stanford University Access – Dynamic Wavelength Allocation • The Upstream Scenario • Performance • Wavelength Plan • Conclusions

3. Overview • Passive Optical Network (PON) • The Time-Division Multiplexed (TDM) PON • The Wavelength-Division Multiplexed (WDM) PON • Arrayed Waveguide Grating (AWG)

4. Passive Optical Network • In a PON, all components between the end users and the central office (CO) are passive

5. The TDM PON • In a TDM PON, end users share the bandwidth in time domain • In the CO, an optical line terminal (OLT) transmits the downstream traffic to the end users and manages the upstream traffic flows from the end users

6. The TDM PON • Downstream • The traffic is broadcast in nature • Each Optical network unit (ONU) receives a copy of the downstream data, extracts only the traffic targeting itself • Upstream • Traffic from the ONUs to the OLT is centrally scheduled by the OLT

7. The TDM PON

8. The WDM PON • What’s is WDM • At the same time, The fiber can carry Independent data streams on different wavelengths • WDM PONs create point-to-point links between the CO and end user, no sharing is needed

9. The WDM PON • A straightforward approach for increasing capacity is to assign different wavelengths to each user for down/upstream transmissions • When a user is idle, the corresponding transceiver in the CO is also idle and cannot be used to support other users • Disadvantage • High Cost • Waste Bandwidth

10. Arrayed Waveguide Grating • The AWG is a wavelength-routing device • Every second wavelength is routed to the same output port • This period of the wavelength response is called free spectral range (FSR)

11. SUCCESS-DWA PON Architecture • TL = Tunable laser CH X = Thin-film WDM filter

12. Downstream • Two TLs must not access the same ONU simultaneously • The AWG does allow all TLs to simultaneously transmit on the same wavelength • All TLs share the load, shifting bandwidth back and forth across the separate physical PONs -- DWA

13. Functional diagrams of the OLT and ONU

14. The Upstream Scenario • Each user is equipped with a fixed-wavelength transmitter that corresponds to the upstream group

15. The Upstream Scenario • Additionally, upstream and downstream AWGs pass completely different wavelengths and require different channel spacings • Only one Photodetector (PD) and its corresponding receiver module are activated in the initial deployment

16. Performance • We compare the performance of a four-TL SUCCESS-DWA PON to four TDM PONs • Both TDM and SUCCESS-DWA PONs are subject to the exact same traffic patterns in any given simulation run • The traffic model is the α-stable self-similar traffic model

17. Performance

18. Wavelength Plan • A trade-off lies between number of the AWG channels and maximum modulation bandwidth

19. Conclusions • SUCCESS-DWA can viewed as a scalable network taking advantage of both TDM and WDM • The scheduling algorithm in the OLT is responsible for managing the traffic flow for fair access of end users

20. Reference • Yu-Li Hsueh, Matthew S. Rogge, Wei-Tao Shaw, and Leonid G. Kazovsky, “SUCCESS-DWA: A Highly Scalable and Cost-Effective Optical Access Network”, IEEE Optical Communication August 2004 • Glen Kramer and Gerry Pesavento, “Ethernet Passive Optical Access Network (EPON): Building a Next-Generation Optical Access Network”, IEEE Communications Magazine February 2002 • http://www.eas.asu.edu/trace/optical/applet1.html