Characterization by Measurement of a CDMA 1x EVDO Network Presenter: Mingzhe Li Wireless Internet Conference (WICON’06) Boston, Massachusetts, August 2006 Mark Claypool, Robert Kinicki, William Lee, Mingzhe Li, and Gregory Ratner CS Department at Worcester Polytechnic Institute Worcester, MA USA

WICON’06 – Boston, Massachusetts 2 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.

WICON’06 – Boston, Massachusetts 3 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

WICON’06 – Boston, Massachusetts 4 Outline Introduction Methodology –Testbed –Tools –Experiment Design Analysis Conclusion and future work

WICON’06 – Boston, Massachusetts 5 Testbed Sierra Wireless Aircard 580 PCMCIA EVDO Network Card Gnu Linux kernel Mbps uplink Measure downlink network to the laptop

WICON’06 – Boston, Massachusetts 6 Tools MeasurementsTools TCP ThroughputGnu Wget. RTT and loss rateStandard Linux ping. npathLoosely based on pathrate Bandwidth estimation using packet pair/train

WICON’06 – Boston, Massachusetts 7 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

WICON’06 – Boston, Massachusetts 8 Outline Introduction Methodology –Testbed –Tools –Experimental Desgin Analysis Conclusion and future work

WICON’06 – Boston, Massachusetts 9 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

WICON’06 – Boston, Massachusetts 10 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

WICON’06 – Boston, Massachusetts 11 TCP Throughput  TCP throughput are consistent between tests  Slightly higher TCP throughput for weekend

WICON’06 – Boston, Massachusetts 12 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.

WICON’06 – Boston, Massachusetts 13 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.

WICON’06 – Boston, Massachusetts 14 Bandwidth Estimation  Median of estimated bandwidth is consistent  5 th percentile of estimated bandwidth varies. Tests of a weekday

WICON’06 – Boston, Massachusetts 15 Bandwidth Estimation (cont.) Tests for weekday and weekend at 5:30pm  Bandwidth estimations are consistent.  Only a small percentage of packet pairs get low estimatiions

WICON’06 – Boston, Massachusetts 16 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.

WICON’06 – Boston, Massachusetts 17 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

Characterization by Measurement of a CDMA 1x EVDO Network Presenter: Mingzhe Li Wireless Internet Conference (WICON’06) Boston, Massachusetts, August 2006 Mark Claypool, Robert Kinicki, William Lee, Mingzhe Li, and Gregory Ratner CS Department at Worcester Polytechnic Institute Worcester, MA USA