LYU9903LYU9903QoS Schemes in Wireless NetwoQoS Schemes in Wireless Netwo

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Ho Pun Mo & Ng MaggieHo Pun Mo & Ng MaggieSupervised by Prof. Lyu R.T. MichaelSupervised by Prof. Lyu R.T. Michael

21 March, 200021 March, 2000

OutlineOutline Introduction Review –

What we have done in the last semester Preview –

What we will have achieved at the end of this semester

Current Status

IntroductionIntroduction

Our TargetsOur Targets Applying QoS in wireless environment Video application Integrating our QoS scheme (wireless)

and LYU9802’s QoS scheme (wired)

Our DifficultiesOur Difficulties QoS in WLAN is a fresh topic

Few papers/references are available

Must tackle with hardware to achieve good result We have used a few weeks to ponder what we can do

Need to deal with MAC layer Concern on quality control rather than produ

cing a product/applying an algorithm! Must work on a “clean” environment

REVIEWREVIEWWhat we have done in the last What we have done in the last

semestersemester

MeasurementMeasurement Compare the bandwidth usage with and with

out QoS With QoS enabled

Real-time audio application used more bandwidths

The mp3 player could play smoothly

Without QoS enabled Mp3 player and FTP competed for bandwidths The mp3 player had “click” sounds

Ported the System to Ported the System to WirelessWireless Using LYU9802’s QoS scheme in the w

ireless environment and it works! Measurement just like the wired one, e

xcept that more time was needed to play the mp3 and FTP applications

PREVIEWPREVIEWWhat we will have achieved at the What we will have achieved at the

end of this semesterend of this semester

Overview of LYU9802’s Overview of LYU9802’s SchemeScheme Component of their QoS Scheme

Bandwidth Reservation – RSVP Packet Scheduling – CBQ

Application Mp3 player played through wired network

Bandwidth ReservationBandwidth Reservation RSVP

Packet SchedulingPacket Scheduling CBQ

QoS Scheme = RSVP + CBQQoS Scheme = RSVP + CBQ

Server

Client

QoS Scheme for WLANQoS Scheme for WLAN We ain’t focusing on general methods (It

is too harsh! ) Ad-hoc method is used and therefore as

sumptions have been taken Many areas can be improved for the wir

eless environment – we will focus on a specific aspect

For video/audio applications over WLAN

Schemes We Have Schemes We Have Thought OfThought Of Decrease error rate

Hardware-oriented! Improve the hand-off mechanism

Not enough reference! Access points must be involved!

Use a workstation to simulate access point Overhead introduced!

etc.

Scheme We Are Scheme We Are ImplementingImplementing What to do?

In one sentenceReserving bandwidth before sending

How to do? Scenario

At least two notebooks (with wireless equipment) An access point connecting to a wired network A server connecting to the wired network above

AlgorithmAlgorithm Fact

Packets are burst for real-time applications Objective

Reducing collision probability when real-time packets are traveling through the air

Method Broadcasting a “signal” packet between two

consecutive real-time packets While receiving the “signal” packet, one would

stop sending packets for a fixed time

AssumptionsAssumptions The environment is “clean” No node will remove from or enter into

the coverage of the access point Only one real-time client is running

ImplementationImplementation Frame structure

ImplementationImplementation hcf_put_data() hcf_send() hcf_get_data()

Video ApplicationVideo Application Purpose

Demonstration QoS is embedded!

Design Client/server model Decoder is present on the client side

Video ApplicationVideo Application Implementation Detail

Video ServerVideo Server ClientClient

MPEGfile Buffer

pipe

mtvWired network

IntegrationIntegration Integrating our QoS scheme and LYU9

802’s QoS scheme LYU9802’s QoS scheme is applied with

in the wired network Our QoS scheme is applied in the wirel

ess connection Of course, client is a wireless node whil

e server is resided in the wired network

Current StatusCurrent Status

Current StatusCurrent Status Signal packets can be sent A client/server video application has im

plemented (only in wired network, and QoS is not ready!)

Q & AQ & A

Thank You!Thank You!