wimax - hybrid scheduler

8/8/2019 WiMAX - Hybrid Scheduler

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QoS Assured Simple Hybrid Uplink Scheduler

for WiMAX Networks

Perumalraja Rengaraju, Carleton University, Canada

Chung-Hong Lung, Carleton University, Canada

Anand Srinivasan, EION wireless Inc., Canada

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Presentation outline

Project goal

Introduction to WiMAX networks

Existing Scheduler Analysis

Proposed solution and Simulation results

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Project goal

To design an Uplink scheduler which assure QoS for all service classes /

Application

The design should be very simple to implement for any real-time devices

Whether any of the homogeneous scheduler meet the requirements?

No..

Design a hybrid uplink scheduler to meet the requirements

QoS assurance and Simple in design

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Introduction to WiMAX networks

In 2004, Fixed WiMAX (IEEE 802.16d) network was introduced. Aim of thisnetwork is to provide the broadband wireless for Fixed and nomadic users.

In 2005, Mobile WiMAX (IEEE 802.16e) network was introduced. It adds the

mobility, improved features (multicast broadcast services MBS) and

improved security support

In the middle of 2009, multihop WiMAX (IEEE 802.16j) network was

introduced. It extends the coverage region by introducing relay station (RS).

End of 2010, multihop WiMAX with Advanced Air Interface (IEEE 802.16m)is expecting to be released and the practical implementations are from 2011

onwards. It supports high bandwidth and mobility

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WiMAX IP based Network Architecture

IEEE 802.16e Network(Point-to-Multi Point)

IEEE 802.16j and IEEE 802.16mmultihop Network

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Protocol stack

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Frame Format of IEEE 802.16e (OFDMA TDD)

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Scans downlink channel

Obtain parameters

Initial ranging

Basiccapabilities exchange

Authentication & Authorization

Registration & IP Connect

Create connection)

Security Association

synchronized

Not synchronized

Initial Ranging slot identified

Wait in the same state

success

failed

failed

success

success

success

failed

failed

Data transfer

success

success

failed

MS Network entry (connectivity) - PMP

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Service Provisioning and Service flow creation

Customer subscribes to the service, tells the service flow information including the number of

UL/DL connections with the data rates and QoS parameters, along with what kindof applications (e.g., Internet, voice, or video), intends to run.

The service provider pre-provision the services by entering the service flow information into the Service

Flow database.

After completing the MS/SS network entry procedure, the BS will downloadthe service flow information from the Service Flow Database (AAA server)

BS will use a Dynamic Service Addition (DSA) message to create service

flows with the pre-provisioned service flow information.

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Service classes and its QoS Parameters

Unsolicited Grant Service (UGS)

Maximum Sustained Traffic Rate, Maximum Latency, Tolerated Jitter, and

Request/Transmission Policy

Extended Real-Time Polling Service (ertPS)

Maximum Sustained Traffic Rate, Maximum Latency, Tolerated Jitter, and

Request/Transmission Policy

real-time Polling Service (rtPS) Minimum Reserved Traffic Rate, Maximum Sustained Traffic Rate, Maximum

Latency, and Request/Transmission Policy

non-real time Polling Service (nrtPS)

Minimum Reserved Traffic Rate, Maximum Sustained Traffic Rate, Traffic Priority,

and Request/Transmission Policy Best Effort service (BE)

Maximum Sustained Traffic Priority, and Request/Transmission Policy

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Service Provisioning UGS

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Service Provisioning rtPS

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Service Provisioning nrtPS

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Service Provisioning BE

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Service flow provisioning for the subscriber

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Admission Controller

In real time, the admission controller allocates resource for the Minimum reserved rate.UGS (min. resv. rate= max. sustained traffic), BE (min. resv. rate=0)

Proposed Admission controller

BE min. resv. rate= R* max. sustained rate

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Bandwidth request, allocation & Scheduling

Bandwidth request

Unicast and multicast polling mechanism

Contention based bandwidth request

Piggyback a BW request message on a data packet.

Grants / allocation

Grant Per Subscriber Station (GPSS)

Grant Per Connection (GPC)

Downlink Scheduling (scheduler resides in the BS)

Since BS knows all traffic information of downlink data for all SSs. the design

of downlink scheduling is simpleUplink Scheduling

Uplink scheduler resides in the SS effectively allocate the available OFDMA

resource to meet the required QoS for each services


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Scheduling Algorithms - Analysis

Schedulers can be classified into channel aware and channel un-aware.

They are further classified into Homogeneous and Hybrid schedulers

Hybrid schedulers combines more than one homogeneous schedulers

Real time

Scheduler


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Proposed Scheduler

Hybrid Scheduler. It Combines Priority and EDD scheduling algorithm

Design of the scheduler is very simple. Easy to implement in real-time devices.

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System Parameters and Traffic Model

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Simulation results Throughput performance

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Simulation results Delay Performance

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Conclusion

Design of the scheduler is simple to implement in real time devices

It eliminates the drawback of real time priority scheduler

It guarantee the delay performance for all service classes

Even though throughput of rtPS and nrtPS is reduced, still it guarantee

the minimum reserved rate.

Here, the admission controller designed in a such a way to restrict the

number BE connections to guarantee the QoS for all service classes.

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Reference

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wimax - hybrid scheduler

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