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TRANSCRIPT
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
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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.
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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
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Deployed Tools and Techniques
Notes: Tools and configuration samples are available at http://perform.wpi.edu/tools
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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.
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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.
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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/) .
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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
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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+
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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)
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Case Studies: Wireless Handheld Games (2)
Updated figures at
http://web.cs.wpi.edu/~claypool/papers/tools/
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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
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Conclusions
• Wireless measurement for the masses – Tools and configuration samples are available at
http://perform.wpi.edu/tools
• 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
http://perform.wpi.edu/tools
Thank You !