CRAWDAD dartmouth/campus dataset (v. 2004-08-05)

Citation Author(s):
Dartmouth College
University of St Andrews
Dartmouth College
Submitted by:
Last updated:
Fri, 08/06/2004 - 08:00
Data Format:
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Measurement trace from wireless network at Dartmouth College.

This dataset includes measurement trace for over 450 access points and several thousand users at Dartmouth College.

last modified: 2006-11-14

reason for most recent change: Infocom 2004 trace is added.

short description: Two-year records showing the location (AP association) of each wireless card seen on campus.

description: Over three years of nearly continuous records showing the location (access-point association) of each wireless card seen on campus. We used this data for our study of location predictors, published in [INFOCOM'04 paper] and a subsequent, expanded [technical report]. This data is derived from the syslog data.

The trace used for this paper is gzipped tar file [51MB].

release date: 2004-08-05

methodology: We extracted user traces from dartmouth/campus/syslog. Each user's trace is a series of locations, that is, access-point names. We introduced the special location 'OFF' to represent the user's departure from the network (which occurs when the user turns off their computer or their wireless card, or moves out of range of all access points). The traces varied widely in length (the number of locations in the sequence). Users with longer traces were either more active (using their card more), more mobile (thus changing access points more often), or used the network for a longer period (some users have been on the network since April 2001, and some others have only recently arrived on campus).

sanitization: Every MAC address has been sanitized, and the IP address or host name of client machines has been removed. To sanitize the MAC address, we randomized the bottom six hex digits. We collected every MAC address from all of our syslog, SNMP, an tcpdump traces, and built a huge table mapping real MACs to randomized MACs, ensuring that all mappings are unique. Each access point name has been blinded in the form: AcadBldg10AP3 where this indicates the third AP in the tenth building of type 'Academic.' The building types are Adm (Admin), Ath (Athletic), Lib (Library), Oth (Other - mainly sysadmin test APs), Res (Residential) and Soc (Social). Refer to note for details.

disruptions to data collection: We have not released syslog trace collected from 2004-07-01 to 2005-08-31.

limitation: Since syslog messages are sent from the APs to a relaying server (ns1), and from ns1 to our syslog recording servers, as UDP messages, it is possible for them to be lost or reordered along the way. The timestamps are applied by the syslog daemon on our host, so the timestamps are monotonically increasing. But, the events may have been recorded out of order, and some may be missing. We believe this effect is small enough to be negligible. We have two syslog recording servers, and we do not see the same event with different timestamps in the two servers. From 10/19/2003 this no longer applies.


format of trace data:

timestamp, associated AP

Dataset Files

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This dataset is part of Community Resource for Archiving Wireless Data (CRAWDAD). CRAWDAD began in 2004 at Dartmouth College as a place to share wireless network data with the research community. Its purpose was to enable access to data from real networks and real mobile users at a time when collecting such data was challenging and expensive. The archive has continued to grow since its inception, and starting in summer 2022 is being housed on IEEE DataPort.

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