Improved Estimation of Trilateration Distances
for Indoor Wireless Intrusion Detection

Philip Nobles¹, Shahid Ali² and Howard Chivers¹

¹Cranfield University

Defence Academy of the UK

Swindon, UK

{p.nobles, h.chivers}@cranfield.ac.uk

²National University of Sciences and Technology

Pakistan

Abstract

Detecting wireless network intruders is challenging since logical addressing information may be

spoofed and the attacker may be located anywhere within radio range. Accurate indoor geolocation

provides a method by which the physical location of rogue wireless devices may be pinpointed whilst

providing an additional option for location-based access control. Existing methods for geolocation

using received signal strength (RSS) are imprecise, due to the multipath nature of indoor radio propagation

and additional pathloss due to walls, and aim to minimise location estimate error.

This paper presents an approach to indoor geolocation that improves measurements of RSS by averaging across

multiple frequency channels and determining the occurrence of walls in the signal path.

Experimental results demonstrate that the approach provides improved distance estimates for trilateration and

thus aids intrusion detection for wireless networks.

Keywords: intrusion detection, wireless networks, insider threats

Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA),

Vol. 2, No. 1, pp. 93-102, June 2011 [pdf]