.ppt

Tools and Techniques for Measurement of IEEE 802.11 Wireless Networks

The Second International Workshop On Wireless Network Measurement (WiNMee 2006 ) April 3, 2006 Boston, Massachusetts, USA

Feng Li, Mingzhe Li, Rui Lu, Huahui Wu, Mark Claypool and Robert Kinicki

{lif,lmz,kkboy,flashine,claypool,rek}@cs.wpi.edu

Computer Science DepartmentWorcester Polytechnic Institute

Worcester, MA, 01609 USA

http://perform.wpi.edu/tools


WinMee 2006, Boston, MA, April 03, 2006

2

Motivation

• The growing popularity of wireless local area network (WLAN) has an increased need for effective measurement tools.

• Not many measurement tools and techniques meet the needs for WLAN measurement studies.

• Need flexible, inexpensive way of measure wireless networks.


3

Outline

• Motivation • Techniques and Tools

– Sniffer and Host Access Points– Measurement Tools

• Case Studies– Wireless Streaming Video– Wireless Handheld Games– Wireless Access Point Queue

• Conclusions


4

Deployed Tools and Techniques

Notes: Tools and configuration samples are available at http://perform.wpi.edu/tools



5

Techniques: Wireless Sniffer

• Purpose– Monitor network traffic at the data-link layer and above.– Passively measure black-box devices.

• Problem– Commercial wireless sniffers are costly and not flexible.

• Approach – Hardware requirement: Commercial PC/Laptop, PrismGT

PCI/PCMCIA cards.

– Software: Linux SuSE 9.2 with Kernel 2.6.


6

Techniques: Host Access Point

• Purpose– Understanding the internal allocation of buffers within a real

wireless access point.– Providing tuning techniques to access points.

• Problem– Commercial Access Points are “black boxes”.– Even some “open box” Access Points are not completely

open.

• Approach– A host computer acting as an access point and take care of

IEEE 802.11 management functions.– Hardware: Ordinary desktop/laptop with wireless NIC. – Software: Linux SuSE9.2 with kernel 2.6.


7

Tools: Cross Layered Measurement

• Measuring the cross layer performance for wireless applications.

Layer Tools Performance Measures

ApplicationMedia Tracker

Real TrackerEncoding Bitrate, Frame Rate, Playout Bitrate, etc.

Network Layer

UDP Ping Round Trip Time, Packet Loss, Throughput.

UDP Heartbeat

UDP LoadOne Way Latency, Packet Loss, Throughput, etc.

MAC Layer WRAPI+ *

Received Signal Strength Indicator (RSSI), Transmitted Frame Count, Failed Frame Transmission Count, etc.

* Notes: WRAPI+ is a realtime monitor application based on the WRAPI Library from UCSD (http://sysnet.ucsd.edu/pawn/wrapi/) .

http://sysnet.ucsd.edu/pawn/wrapi/


8

Outline

• Motivation • Techniques and Tools

– Sniffer and Host Access Points– Measurement Tools

• Case Studies– Wireless Streaming Video– Wireless Handheld Games– Wireless Access Point Queue

• Conclusions


9

Case Studies: WLAN Streaming Video

• Purpose – Show the importance of gathering wireless LAN measurements

from multiple layers of the protocol.

• Experiment Setup

WPI Campus LAN

Streaming Server

Access point

80 feet , 3 min

Media TrackerUDP Ping

WRAPI+, etc

100M bps

Start


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Case Studies: WLAN Streaming Video (2)


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Case Studies: WLAN Streaming Video (3)

Application Layer:

• Video Encoding Bit Rate

• Gathered by Media Tracker

Network Layer:

• UDP Ping Packet Loss Rate

• Gathered by UDP Ping

MAC Layer:

• Received Signal Strength Indicator (RSSI)

• Gathered by WRAPI+


12

Case Studies: Wireless Handheld Games

• Purpose – Demonstrate the ability to passively gather wireless

layer traffic from commercial devices. • Experiment Setup

Nintendo DS

Nintendo DS Nintendo DS

Sniffer: Dell Insprion 8600Netgear WG 511 NIC Linux SuSE 9.2

• Super Mario (3rd person action game)

• Rogue Agent(1st person shooter game)


13

Case Studies: Wireless Handheld Games (2)

Updated figures at

http://web.cs.wpi.edu/~claypool/papers/tools/


14

Case Studies: Wireless Access Point Queue

• Purpose– Demonstrate ability to change AP settings. – Confirm QFind methodology.

• Experiment Set up

100M bps

UDP traffic generatorWindows XP/SP2

HOST AP :Linux Kernel 2.6

UDP traffic ReceiverWindows XP/SP2


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Case Studies: Wireless Access Point Queue (2)

• Set different IP queue length for Host AP.

• Estimate the queue size though Qfind metheod

qp = Dq X T / s

• Modified the Linux kernel in Host AP to report the queue length every 200ms.

IP queue size = 1000 packets

IP queue size = 100 packets


16

Conclusions

• Wireless measurement for the masses – Tools and configuration samples are available at


• Enable cross layer approaches – Bottom-up information to applications

– Top-down adjustments based on applications.

• Facilitate “black box” analysis of commercial products– Wireless access points.

– Wireless applications, cards and devices.

Tools and Techniques for Measurement of IEEE 802.11 Wireless Networks

The Second International Workshop On Wireless Network Measurement (WiNMee 2006) April 3, 2006 Boston, Massachusetts, USA

Feng Li, Mingzhe Li, Rui Lu, Huahui Wu, Mark Claypool and Robert Kinicki

{lif,lmz,kkboy,flashine,claypool,rek}@cs.wpi.edu

Computer Science DepartmentWorcester Polytechnic Institute

Worcester, MA, 01609 USA


Thank You !

http://www.winmee.org/

http://www.winmee.org/


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