wypy : an extensible, online interference detection tool for wireless networks

WiFi networks have become ubiquitous. However, due to the nature of the radio-wave medium, the performance of 802.11 is unpredictable and highly dependent on the environment. This problem is fundamental to 802.11's decentralized, signal-based airspace arbitration mechanism. When devices have incomplete and inconsistent channel conditions for an overlapping interference domain, their signals alone cannot ensure a fair competition for airspace. As a result, competing flows may suffer from unfair bandwidth distribution if the shared airspace is congested. A useful tool to visualize and diagnose problematic wireless networks is the set of devices interfering with each other at a given time. We say two devices a and b interfere when one of two possible situations occur. First, a is able to sense b's radio signals, though not necessarily decode them, resulting in a unable to send data. Second, a and b aren't in radio range, but their destination devices are, resulting in packet collisions. We call such a set of mutually interfering devices the interference neighbourhood. We present wypy, an online system which merges trace-files and produces a map of interfering devices contained within the trace. wypy is able to identify pairs of devices exhibiting either hidden or exposed terminal interference using a pipeline that consists of trace merging and reconstruction, filtering of simultaneously sending devices, throughput and delay signal calculations, and a test for interference correlation. We evaluate wypy using an in-lab testbed set up in known interference scenarios.

Name thesis:degree_name

Master of Science - MSc

Level thesis:degree_level

master's

Discipline thesis:degree_discipline

Computer Science

Grantor dc:publisher

University of British Columbia

Year dc:date

2008

Author dc:creator

• Lotun, Reza M. E.

Statement dc:rights

• Attribution-NonCommercial-NoDerivatives 4.0 International

Licence

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language

eng

Handle dc:identifier

http://hdl.handle.net/2429/515

OAI identifier oai:identifier

oai:circle.library.ubc.ca:2429/515