LYU9903LYU9903QoS Schemes in Wireless QoS Schemes in Wireless

NetworksNetworksHo Pun Mo & Ng MaggieHo Pun Mo & Ng Maggie

Supervised by Prof. Lyu R.T. Michael

6 December, 1999

Outline

• Introduction

• Wireless Networks

• QoS

• Performance Evaluation

• QoS in Wireless Networks

• Application - Video

• Future Work

IntroductionIntroduction

• Concern about QoS and wireless networks

• QoS is not as simple as one would think

• Platform we choose is Linux

• Focus on: investigating and analyzing QoS schemes on wireless networks measuring and comparing performance on wired/wireless networks

Wireless NetworksWireless Networks

• Wireless Local Area Networks (Wireless LANs)

• Wireless Wide Area Networks (Wireless WANs)

Wireless LANsWireless LANs

• Extension to /Alternative for Wired Network

• IEEE 802.11 standard

• Using Radio Frequency (RF)

• connected as infrastructure network

Wireless LANsWireless LANsWhat is Infrastructure Network?

Wired vs Wireless Wired vs Wireless NetworksNetworks

• different physical & datalink protocols

• different hardware

• wireless networks: Roaming

• different performance

Why Wireless?Why Wireless?

• Importance of Wireless LANs:increasing of mobility

• Trend of Wireless LANs:better performancelower cost

Why Wireless?Why Wireless?

• Applications of Wireless LANs:in hospitalsin campusin retail stores & restaurantsin warehousesin old buildings

Wireless DevicesWireless Devices

• Access Points:

Proxim RangeLAN2 Ethernet & Token Ring Access Point

WaveLAN WavePOINT-II Access Point

Wireless DevicesWireless Devices

• PC Cards:

WaveLAN Turbo(Bronze) PC Card Proxim RangeLAN2 7400 PC Card

• Date Rate: 2-6 Mbps

• Range: 40-115m (indoor) 120-540m (outdoor)

• Freq.: 2400-2483.5MHz

• Date Rate: 1.6 Mbps

• Range: 152m (indoor) 305m (outdoor)

•Freq.: 2.4GHz

Pros & Cons of WirelessPros & Cons of Wireless

• Advantages:MobilityFlexibilityEase of InstallationCost of InstallationSecurityEnough Bandwidth for Office Uses

Pros & Cons of WirelessPros & Cons of Wireless

• Disadvantages:Low BandwidthHigh Error Rates & High DelayLimited Range of CoverageLarge Consumption of BatteryUnwanted Interference

What is QoS?What is QoS?

• There are many QoS’s

• We concern about QoS in computer networks

• Some definitions: the collective effect of service performances which determine the degree of

satisfaction of a user of the service

the ability of a network to deliver time-bounded traffic types (e.g. real time video or voice) with predictable latencies

a way to specify an applications network performance requirements, and it is specified by performance parameters

What is QoS?What is QoS?

• What QoS means to us:

QoS is the guarantee of delivering network packets QoS is the guarantee of delivering network packets punctually and the guarantee of delivering an acceptable punctually and the guarantee of delivering an acceptable numbers of network packets in a compromised time numbers of network packets in a compromised time interval, which would not annoy the receivers.interval, which would not annoy the receivers.

Why QoS?Why QoS?

• Statistic from Cisco shows that multimedia applications become more and more popular

Why QoS?Why QoS?

• Which one do you prefer?

Normal Long Delay Lost Frame

How to Achieve QoS?How to Achieve QoS?

• Many ways

Bandwidth reservation + Packet scheduling

• Bandwidth reservationRSVP

• Packet schedulingCBQ

How to Achieve QoS?How to Achieve QoS? ~ Bandwidth ~ Bandwidth ReservationReservation

• RSVPRSVP is a protocol that allows channels or paths on the networks to be reserved for the transmission of video and other high-bandwidth messages.

How to Achieve QoS? ~ How to Achieve QoS? ~ RSVPRSVP

How to Achieve QoS?How to Achieve QoS? ~ Packet ~ Packet

SchedulingScheduling• There are many packet scheduling algorithms

• Some examples: FIFO - First In First Out SFQ - Stochastic Fairness Queuing WFQ - Weighted Fair Queuing CBQ - Class Based Queuing

• Focus on CBQ

How to Achieve QoS? ~ How to Achieve QoS? ~ CBQCBQ

•Hierarchical link-sharing structure

ArchitectureArchitecture ~ Combining RSVP and ~ Combining RSVP and CBQCBQ

Server

Client

Performance EvaluationPerformance Evaluation~ Wired ~ Wired

NetworksNetworks• Scenario:

Server Client

Ethernet

Application:FTP

Application:MP3 player

Performance EvaluationPerformance Evaluation~ Wired ~ Wired

NetworksNetworks• Results with & without QoS

Received Bandwidth of FTP & MP3using QoS with 200Kbit

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Received Bandwidth of FTP & MP3with NO QoS, with 200Kbit

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Performance EvaluationPerformance Evaluation~ Wired ~ Wired

NetworksNetworks• Applied QoS & NoQoS in same experiment

Received Bandwidth of FTP & MP3using NO QoS at first 2min and

using QoS after 2min with 200Kbit

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noqos qos

Performance EvaluationPerformance Evaluation~ Wired ~ Wired

NetworksNetworks• What can you see from the results?

QoS makes MP3 playing smoothly

QoS benefits both MP3 and FTP applications

QoS can be applied on the fly

Performance EvaluationPerformance Evaluation~ Wireless ~ Wireless

NetworksNetworks• Scenario:

Server

Client

Ethernet

Application:FTP

Application:MP3 player

Access Point

Performance EvaluationPerformance Evaluation~ Wireless ~ Wireless

NetworksNetworks• Performance on using the Proxim devices

Received Bandwidth of FTP & MP3 using QoS with200Kbits (using Proxim)

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Received Bandwidth of FTP & MP3 without QoSwith 200Kbits (using Proxim)

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Performance EvaluationPerformance Evaluation~ Wireless ~ Wireless

NetworksNetworks• Performance on using the WaveLAN devices

Received Bandwidth of FTP & MP3 using QoSwith 200Kbits (using WaveLAN)

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0 100 200 300 400 500Time (sec)

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Received Bandwidth of FTP & MP3 without QoSwith 200Kbits (using waveLAN)

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0 100 200 300 400 500 600

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FTPMP3

Performance EvaluationPerformance Evaluation~ Wireless ~ Wireless

NetworksNetworks• With / without QoS in the same experiment

Received Bandwidth of FTP & MP3 with 200Kbits (using Proxim)

Received Bandwidth of FTP & MP3 with 200Kbits (using WaveLAN)

noqosnoqos

qosqos

Performance EvaluationPerformance Evaluation~ Wireless ~ Wireless

NetworksNetworks• What can you see from the results?

QoS makes MP3 playing smoothlyQoS benefits both MP3 and FTP applicationsWired Networks vs Wireless Networks:

Wireless Networks have larger delayProxim vs WaveLAN:

seems Proxim performs better!

QoS in Wireless QoS in Wireless NetworksNetworks

• Problems: Variable bandwidth Roaming Low Reliability and Long Delay Interference Hard disk bottleneck

• Solutions: Renegotiation Apply QoS in Access Points Network Collision Control

Application - VideoApplication - Video

• Real time video player for both wired and wireless networks with QoS enabled

• Design:RPCEnabled QoS

Buffering at both client and server side RAPI

Future WorkFuture Work

• Measure the delay jitter of the QoS systems (both wired and wireless)

• Measure the performance of the QoS systems with router presented

• Finish our video application with QoS enabled• Measure the performance of our video application • Inspect the source code of WaveLAN driver in order to

make it QoS enabled

The EndThe End

Thanks!