LYU9903 QoS Schemes in Wireless Networks

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LYU9903QoS Schemes in Wireless Networks

• Ho Pun Mo Ng Maggie
• Supervised by Prof. Lyu R.T. Michael
• 6 December, 1999

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Outline

• Introduction
• Wireless Networks
• QoS
• Performance Evaluation
• QoS in Wireless Networks
• Application - Video
• Future Work

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Introduction

• 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

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Wireless Networks

• Wireless Local Area Networks (Wireless LANs)
• Wireless Wide Area Networks (Wireless WANs)

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Wireless LANs

• Extension to /Alternative for Wired Network
• IEEE 802.11 standard
• Using Radio Frequency (RF)
• connected as infrastructure network

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Wireless LANs
What is Infrastructure Network?
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Wired vs Wireless Networks

• different physical datalink protocols
• different hardware
• wireless networks Roaming
• different performance

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Why Wireless?

• Importance of Wireless LANs
• increasing of mobility
• Trend of Wireless LANs
• better performance
• lower cost

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Why Wireless?

• Applications of Wireless LANs
• in hospitals
• in campus
• in retail stores restaurants
• in warehouses
• in old buildings

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Wireless Devices

• Access Points

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Wireless 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

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Pros Cons of Wireless

• Advantages
• Mobility
• Flexibility
• Ease of Installation
• Cost of Installation
• Security
• Enough Bandwidth for Office Uses

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Pros Cons of Wireless

• Disadvantages
• Low Bandwidth
• High Error Rates High Delay
• Limited Range of Coverage
• Large Consumption of Battery
• Unwanted Interference

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What is QoS?

• There are many QoSs
• 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

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What is QoS?

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

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Why QoS?

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

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Why QoS?

• Which one do you prefer?

Normal
Long Delay
Lost Frame
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How to Achieve QoS?

• Many ways
• Bandwidth reservation Packet scheduling
• Bandwidth reservationRSVP
• Packet schedulingCBQ

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How to Achieve QoS? Bandwidth Reservation

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

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How to Achieve QoS? RSVP
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How to Achieve QoS? Packet Scheduling

• 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

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How to Achieve QoS? CBQ

• Hierarchical link-sharing structure

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Architecture Combining RSVP and CBQ
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Performance Evaluation Wired Networks

• Scenario

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Performance Evaluation Wired Networks

• Results with without QoS

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Performance Evaluation Wired Networks

• Applied QoS NoQoS in same experiment

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Performance Evaluation Wired Networks

• 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

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Performance Evaluation Wireless Networks

• Scenario

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Performance Evaluation Wireless Networks

• Performance on using the Proxim devices

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Performance Evaluation Wireless Networks

• Performance on using the WaveLAN devices

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Performance Evaluation Wireless Networks

• 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)
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Performance Evaluation Wireless Networks

• What can you see from the results?
• QoS makes MP3 playing smoothly
• QoS benefits both MP3 and FTP applications
• Wired Networks vs Wireless NetworksWireless
  Networks have larger delay
• Proxim vs WaveLANseems Proxim performs better!

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QoS in Wireless Networks

• Problems
• Variable bandwidth
• Roaming
• Low Reliability and Long Delay
• Interference
• Hard disk bottleneck
• Solutions
• Renegotiation
• Apply QoS in Access Points
• Network Collision Control

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Application - Video

• Real time video player for both wired and
  wireless networks with QoS enabled
• Design
• RPC
• Enabled QoS
• Buffering at both client and server side
• RAPI

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Future 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

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The End

• Thanks!