Characterization by Measurement of a CDMA 1x EVDO Network

1
Characterization by Measurement of a CDMA 1x EVDO
Network
Mark Claypool, Robert Kinicki, William Lee,
Mingzhe Li, and Gregory Ratner CS Department at
Worcester Polytechnic Institute Worcester, MA
01609 USA

• Presenter Mingzhe Li lmz_at_cs.wpi.edu
• Wireless Internet Conference (WICON06)
• Boston, Massachusetts, August 2006

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Motivation

• EVDO 3G cellular data networks
• Provides more bandwidth
• More applications
• Throughput sensitive
• Latency sensitive
• Multimedia streaming
• Current research of cellular data network
  performance
• Theoretical analysis and simulations
• Measurements studies
• 2G/2.5G networks
• Focus on throughput
• Few latency measurements and bandwidth estimations

• We need more characterization on EVDO networks.

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Introduction

• Measurement based characterization of EVDO
  network
• TCP throughput
• Round trip time
• Loss rate
• Bandwidth estimation
• Gauge the ability of EVDO to support the QoS of a
  range of applications

4
Outline

• Introduction
• Methodology
• Testbed
• Tools
• Experiment Design
• Analysis
• Conclusion and future work

5
Testbed
50 Mbps uplink
Measure downlink network to the laptop
Sierra Wireless Aircard 580 PCMCIA EVDO Network
Card Gnu Linux kernel 2.6.11
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Tools
Measurements Tools
TCP Throughput Gnu Wget.
RTT and loss rate Standard Linux ping.
npath Loosely based on pathrate Bandwidth estimation using packet pair/train
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Experimen design

• Each test includes
• Measure wireless signal strength
• Wget downloads 20 Mbyte file
• Ping server 100 times
• npath capacity estimation
• Packet pairs length 25 packets
• Packet size 1472, 1200, 1000, and 800 bytes
• Repeat 30 times for each packet size
• Each test takes 12 minutes in total
• Run every 30 minutes for a week
• November 28, 2005 to December 4, 2005

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Outline

• Introduction
• Methodology
• Testbed
• Tools
• Experimental Desgin
• Analysis
• Conclusion and future work

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Analysis

• Data collected
• 48 runs each day for 7 days
• All tests with excellent signal strength
• -90 to -83 dBm
• TCP throughput tcpdump and tcptrace
• RTT and packet loss ping
• Network capacity npath.
• Analysis focus
• Week day Wednesday November 30, 2005
• Weekend Saturday December 3, 2005

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TCP Throughput (cont.)

• TCP throughput lower than theoretically EVDO
  networks
• No visual correlation between throughput and the
  time of day
• Satisfactory for most Internet applications

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TCP Throughput

• TCP throughput are consistent between tests
• Slightly higher TCP throughput for weekend

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Round trip time of a weekday

• Average RTT are consistent between tests
• Maximum RTT vary greatly.
• No visual correlation between RTT and the time
  of day.

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CCDF of RTT

• Median RTT 200ms is too high for interactive
  applications.
• Maximum RTT around 1 second can seriously Impact
  the performance of interactive applications.

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Bandwidth Estimation
Tests of a weekday

• Median of estimated bandwidth is consistent
• 5th percentile of estimated bandwidth varies.

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Bandwidth Estimation (cont.)
Tests for weekday and weekend at 530pm

• Bandwidth estimations are consistent.
• Only a small percentage of packet pairs get low
  estimatiions

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Summary and Conclusion

• 3G EVDO network provides higher throughput than
  2G/2.5G cellular networks
• The high RTT may impact the performance of
  interactive applications
• Bandwidth estimations are consistent, suggesting
  packet pairs are sufficient for bandwidth
  estimation.
• Neither throughput, round-trip time, nor
  bandwidth estimation correlates with time of day
  or the day of the week.

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Future work

• More Characterizations
• Mobility
• Poor signal quality
• Variable traffic load
• Comparison with other cellar networks
• Application performance
• Interactive applications (games, VoIP)
• Multimedia streaming applications

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Characterization by Measurement of a CDMA 1x EVDO
Network
Mark Claypool, Robert Kinicki, William Lee,
Mingzhe Li, and Gregory Ratner CS Department at
Worcester Polytechnic Institute Worcester, MA
01609 USA

• Presenter Mingzhe Li lmz_at_cs.wpi.edu
• Wireless Internet Conference (WICON06)
• Boston, Massachusetts, August 2006