CRAWDAD tools/analyze/pcap/wifidelity (v. 2008-10-05)

Wifidelity toolkit - Trace statistics and timing.

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.

Lastmodified :

2008-05-16

Dataname :

tools/analyze/pcap/wifidelity

File :

Wifidelity-0.04.tar.gz

Releasedate :

2008-04-30

Change :

the initial version.

References :

schulman-fidelity
The WiFidelity web page

Website :

http://www.cs.umd.edu/projects/wifidelity/

Keyword :

802.11
802.11 frames
RFMON
packet trace
signal strength
tcpdump

License :

This software is released under the GNU GPL.

Build :

- 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

Output :

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

Parameters :

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.

Usage :

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

Example :

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

Algorithm :

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.