[Tool] tools/analyze/pcap/wifidelity (v. 2008-10-05)

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Release Note: Version 0.04 had a broken score formula in Stats.pm. Please recompute all version 0.04 score plots with the latest version. Thanks to Dan Halperin for finding this bug.

@MISC{tools-analyze-pcap-wifidelity-2008-10-05,
  author = {Aaron Schulman and Dave Levin and Neil Spring},
  title = {{CRAWDAD} tool tools/analyze/pcap/wifidelity (v. 2008-10-05)}, 
  howpublished = {Downloaded from http://crawdad.cs.dartmouth.edu/tools/analyze/pcap/wifidelity},
  month = oct,  
  year = 2008
}
					

The Wifidelity package consists of two tools to identify the completeness and accuracy of 802.11 packet traces. "tracestats" uses 802.11 sequence numbers to quantify completeness, and the "plotscore" script generates a T-Fi plot: an at-a-glance, heatmap visualization of completeness versus load. "tracetiming" uses AP Beacon intervals to quantify packet timestamp accuracy and "plottiming" produces a line plot of timestamp accuracy.

This software is released under the GNU GPL.

- Requirements:

plotscore, plottiming:
	gnuplot >= 4.0

tracestats, tracetiming:
	Perl with 64 bit support
	Perl lib Net::Pcap

- Files:

tracestats - print trace statistics on beacon intervals
tracetiming - print trace timing information on beacon intervals

Wifidelity/Pcap.pm - Pcap interface
Wifidelity/Stats.pm - Statistics
Wifidelity/80211.pm - 802.11 constants
Wifidelity/Timing.pm - Timing

- plotscore, plottiming:
.eps file in the same folder as the input data file

The default package can only parse pcap traces. If you would like to add
a parser for another trace type follow the interface in Pcap.pm. In the future
this procedure will be simplified.

tracestats:
	see ./tracestats -h
tracetiming:
	see ./tracetiming -h
plotscore:
	./plotscore <stats-file> "<title>"
plottiming:
	./plottiming <timing-file> "<title>" <Min us>:<Max us>

For sample T-Fi plots, please visit the tool homepage ( http://www.cs.umd.edu/projects/wifidelity )

Packet traces from 802.11 wireless networks are incomplete
both fundamentally, because antennas do not pick up every transmission,
and practically, because the hardware and software of collection may be
under provisioned. One strategy toward improving the completeness of
a trace of wireless network traffic is to deploy several monitors; these are
likely to capture (and miss) different packets. Merging these traces into
a single, coherent view requires inferring access point (AP) and client
behavior; these inferences introduce errors.

The WiFidelity tool implements methods to evaluate the fidelity of merged
and independent wireless network traces. We show that wireless traces
contain sufficient information to measure their completeness and clock
accuracy. Specifically, packet sequence numbers indicate when packets
have been dropped, and AP beacon intervals help determine the accuracy
of packet timestamps. We also show that trace completeness and clock
accuracy can vary based on load. We apply these metrics to evaluate
fidelity in two ways: (1) to visualize the completeness of different 802.11
traces, which we show with several traces available on CRAWDAD and
(2) to estimate the uncertainty in the time measurements made by the
individual monitors.

[Author] Aaron Schulman

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[Author] Dave Levin

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[Author] Neil Spring

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[Paper] schulman-fidelity

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Packet traces from 802.11 wireless networks are incomplete both fundamentally, 
because antennas do not pick up every transmission, and practically, because 
the hardware and software of collection may be under provisioned. One strategy 
toward improving the completeness of a trace of wireless network traffic is to 
deploy several monitors; these are likely to capture (and miss) different 
packets. Merging these traces into a single, coherent view requires inferring 
access point (AP) and client behavior; these inferences introduce errors. In 
this paper, we present methods to evaluate the fidelity of merged and 
independent wireless network traces. We show that wireless traces contain 
sufficient information to measure their completeness and clock accuracy. 
Specifically, packet sequence numbers indicate when packets have been dropped, 
and AP beacon intervals help determine the accuracy of packet timestamps. We 
also show that trace completeness and clock accuracy can vary based on load. We 
apply these metrics to evaluate fidelity in two ways: (1) to visualize the 
completeness of different 802.11 traces, which we show with several traces 
available on CRAWDAD and (2) to estimate the uncertainty in the time 
measurements made by the individual monitors.