A Novel Multiple Access Scheme for Ethernet Passive Optical Network

Professor : Ho-Ting WuSpeaker ： Rui-Yi Jian

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Outline

Introduction Operation Steps Conclusion

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Outline

Introduction Operation Steps Conclusion

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Introduction

Propose a novel multiple access scheme to efficiently share the upstream channel in an EPON

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Propose

The multiple access scheme contains three parts that operate autonomously but are closely related to each other Parameter-based CAC Mechanism EDA BGP Scheme

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Terminology OLT

Optical Line Terminal ONU

Optical Network Unit SLA

Service Level Agreement RTT

Round-Trip Time BG

Bandwidth Guaranteed 2004 – 08 – 11

Generally three class of traffic

Expedited Forwarding (EF) Voice or Video

Assured Forwarding (AF) Best Effort (BE)

Email

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Outline

Introduction Operation Steps Conclusion

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Operation Steps

Parameter-based CAC Mechanism EDA BGP Scheme

Bandwidth Guaranteed Polling

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Parameter-based CAC Mechanism

Call Admission Control Admits customers in consideration of SL

A, through which ONUs can be divided into two disjoint groups served by the OLT differently BG ONUs Non-BG ONUs

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CAC - Parameter

<C, D> C specifies the minimum peak bandwidth an

ONU requests D indicates the maximum waiting delay an O

NU can tolerate E(Di)

the worst case average delay E(Di) for each ONU that the OLT pre-calculate

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CAC Mechanism -Initialization

Ci* , the OLT re-calculate

Check the utilizationof network

EDA

Evenly Distributed Algorithm Determines the polling sequence of ON

Us for the scheduling scheme

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EDA – Step1

Process the BG ONUs from the one with maximum entries to the one with minimum entries

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EDA – Step2 (1/3)

After determining the first entry Ei[1] and other entries Ei[j] (j=2,3,…Ni) for BG ONUi with Ni entries, fill the Table with this ONU’s ID i

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EDA – Step2 (2/3)

Let entry i to be the first entry of ONU i Ei[1] = i

If the entry i is occupied by other ONU Ei[1] = i ± n ,

n = 1,2,3,…

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ONU2

ONU6

EDA – Step2 (3/3)

Other entries Ei[j] (j=2,3,…Ni) , and N is the total entry number of the Entry Table

Ei[j]=mod(Ei[l]+int(j-1)*N/Ni , N )

Ei[j]=mod((Ei[l]+int(j-1)*N/Ni) ± n, N )

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ONU3j = 3Ni = 4N = 8

EDA – Step3

All entries that are not occupied by BG ONUs will be blank in the Entry Table, then assigned to non-BG ONUs dynamically

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EDA – Step4

The List for non-BG ONUs is sequenced in ascending order based on non-BG ONUs’ IDs

The total number of the elements in the List is not fixed

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EDA – Benefit

It will benefit to the BG ONUs with high traffic since the packets in the buffer can be allowed to transmit after the same intervals

Thus there will be no burst, caused by the scheduling, introduced to the data transmission

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BGP Scheme

Bandwidth Guarantee Polling The proposed scheme is able to guaran

tee bandwidth for high-demand users , and provide a best-effort service to low-demand users

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BGP - Steps

The Entry Table & List will determine the scheduling order of ONUs

The OLT sending a control message locate which ONU occupies this entry grants a transmission window to the ONU

Duration of the transmission window The ONU starts to transmit data frames reports its buffer occupancy status

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BGP - Benefit

Entries in the Table that are not occupied by BG ONUs or the superfluous transmission window in one entry that is occupied yet unconsumed by an ONU can be assigned to non-BG ONUs dynamically

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BGP - Problem

How to defined a threshold to determine whether to use the superfluous transmission window or give it up

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Outline

Introduction Operation Steps Conclusion

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Conclusion

This scheme can guarantee bandwidth for high-demand customers while providing best-effort service to low-demand customers based on the SLA

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