LYU9903 QoS Schemes in Wireless Networks Ho 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

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

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

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

Wireless LANs What is Infrastructure Network?

Wired vs Wireless Networks different physical & datalink protocols different hardware wireless networks: Roaming different performance

Why Wireless? Importance of Wireless LANs:  increasing of mobility Trend of Wireless LANs:  better performance  lower cost

Why Wireless? Applications of Wireless LANs:  in hospitals  in campus  in retail stores & restaurants  in warehouses  in old buildings

Wireless Devices Access Points: Proxim RangeLAN2 Ethernet & Token Ring Access Point WaveLAN WavePOINT-II Access Point

Wireless Devices PC Cards: WaveLAN Turbo(Bronze) PC CardProxim RangeLAN PC Card Date Rate: 2-6 Mbps Range: m (indoor) m (outdoor) Freq.: MHz Date Rate: 1.6 Mbps Range: 152m (indoor) 305m (outdoor) Freq.: 2.4GHz

Pros & Cons of Wireless Advantages:  Mobility  Flexibility  Ease of Installation  Cost of Installation  Security  Enough Bandwidth for Office Uses

Pros & Cons of Wireless Disadvantages:  Low Bandwidth  High Error Rates & High Delay  Limited Range of Coverage  Large Consumption of Battery  Unwanted Interference

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 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.

Why QoS? Statistic from Cisco shows that multimedia applications become more and more popular

Why QoS? Which one do you prefer? NormalLong DelayLost Frame

How to Achieve QoS? Many ways Bandwidth reservation + Packet scheduling Bandwidth reservation RSVP Packet scheduling CBQ

How to Achieve QoS? ~ Bandwidth Reservation 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? ~ RSVP

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

How to Achieve QoS? ~ CBQ Hierarchical link-sharing structure

Architecture ~ Combining RSVP and CBQ       Server Client

Performance Evaluation ~ Wired Networks Scenario: ServerClient Ethernet Application: FTP Application: MP3 player

Performance Evaluation ~ Wired Networks Results with & without QoS

Performance Evaluation ~ Wired Networks Applied QoS & NoQoS in same experiment noqosqos

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

Performance Evaluation ~ Wireless Networks Scenario: Server Client Ethernet Application: FTP Application: MP3 player Access Point

Performance Evaluation ~ Wireless Networks Performance on using the Proxim devices

Performance Evaluation ~ Wireless Networks Performance on using the WaveLAN devices

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) noqos qos

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 Networks: Wireless Networks have larger delay  Proxim vs WaveLAN: seems Proxim performs better!

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

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

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

The End Thanks!