Abstract

GPS currently provides accurate localisation for external applications however it fails to function internally due to the direct line-of-sight requirement by satellites. This exposes a need to produce a reliable, low cost, accurate system for internal use. As with GPS, internal localisation signals suffer from attenuation, reflection, refraction and multi-path propagation due to objects in the environment i.e. walls, furniture, people. The significant impact factor is the movement of people as they cause signal distortion and create uncertainty in location data. Due to this uncertainty, many methods used for localisation have compromised on accuracy for low cost or power consumption. For example, many commercial systems available incorporate higher costs for proprietary hardware to boost the signals and therefore increase accuracy. This paper provides a review of the most common techniques for internal localisation which use wireless access points (APs). In addition, the paper proposes a new approach to internal localisation which aims at increasing the accuracy of detection whilst keeping minimum system cost.