Document Type

Technical Report

Publication Date

3-12-2002

Technical Report Number

TR2002-423

Abstract

Wireless local-area networks (WLANs) are increasingly common, but little is known about how they are used. A clear understanding of usage patterns in real WLANs is critical information to those who develop, deploy, and manage WLAN technology, as well as those who develop systems and application software for wireless networks. This paper presents results from the largest and most comprehensive trace of network activity in a large, production wireless LAN. For eleven weeks we traced the activity of nearly two thousand users drawn from a general campus population, using a campus-wide network of 476 access points spread over 161 buildings. Our study expands on those done by Tang and Baker, with a significantly larger and broader population. We found that residential traffic dominated all other traffic, particularly in residences populated by newer students; students are increasingly choosing a wireless laptop as their primary computer. Although web protocols were the single largest component of traffic volume, network backup and file sharing contributed an unexpectedly large amount to the traffic. Although there was some roaming within a network session, we were surprised by the number of situations in which cards roamed excessively, unable to settle on one access point. Cross-subnet roams were an especial problem, because they broke IP connections, indicating the need for solutions that avoid or accommodate such roams.

Comments

A major revision of this paper appeared in Mobicom 2002. The Mobicom paper contained two erroneous figures, however; another report, TR2002-432, is the final corrected version.

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