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

Speaker： Tse-Hsien Lin

Teacher： Ho-Ting Wu

Date： 93.10.21

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Outline

Overview SUCCESS-DWA PON Architecture

Stanford University Access – Dynamic Wavelength Allocation

The Upstream Scenario Performance Wavelength Plan Conclusions

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Overview

Passive Optical Network (PON) The Time-Division Multiplexed (TDM)

PON The Wavelength-Division Multiplexed

(WDM) PON Arrayed Waveguide Grating (AWG)

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Passive Optical Network

In a PON, all components between the end users and the central office (CO) are passive

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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

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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 centr

ally scheduled by the OLT

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The TDM PON

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The WDM PON

What’s is WDM At the same time, The fiber can carry Ind

ependent data streams on different wavelengths

WDM PONs create point-to-point links between the CO and end user, no sharing is needed

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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

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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)

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SUCCESS-DWA PON Architecture

TL = Tunable laser CH X = Thin-film WDM filter

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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

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Functional diagrams of the OLT and ONU

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The Upstream Scenario

Each user is equipped with a fixed-wavelength transmitter that corresponds to the upstream group

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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

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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

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Performance

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Wavelength Plan

A trade-off lies between number of the AWG channels and maximum modulation bandwidth

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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

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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