802.11 Positioning in the Home

Abstract

802.11 positioning systems are established as a lowcost solution to positioning within context aware computing. Prior research has mostly focused on either indoor positioning within commercial environments, where access points are prevalent, or outdoors positioning over large areas, using discovered networks to augment GPS. In this paper we test 802.11 positioning in a medium sized domestic house with only a small number of access points, examining its suitability in a domestic context aware computing system.We use a signal strength fingerprint map approach, in which empirical signal strength data is gathered over the area prior to use. Estimation then involves comparing the online input to the map, and selecting the best position, and direction, based on similarity. We compare different strategies for gathering signal strength, and implementations of the Nearest Neighbor and Bayesian methods. Our results demonstrate that with good placement, only two access points are sufficient to estimate position with an error of less than 4 meters 90% of the time.

IR-UWB tag and reader for RTLS

“…However, these methods do not achieve the accuracy necessary for indoor applications. Reference [1] achieves an accuracy of 2~ 4 meters, while [2] gives position estimates of up to 1 meter accuracy. In an indoor environment where spaces may be less than one square meter, these degrees of accuracy is not enough.…”

“…Various proposed solutions to indoor positioning use Wi-Fi [1], RFID(Radio-Frequency IDentification) [2] or wireless sensor networks [3]. However, these methods do not achieve the accuracy necessary for indoor applications.…”

A fingerprinting‐based indoor localization system using intensity modulation of light emitting diodes

“…Fingerprinting of WiFi signals is one of the techniques that receives the highest attention [3]. Nowadays as most buildings, both residential and commercial, have their own WiFi access points installed for data communication, additional costs for operating a localization system using WiFi signals can be made lower than installing an entirely new system although it may have a high potential to yield more accurate result [6–10]. In addition to WiFi, other types of signal were also investigated and reported in the existing literatures such as Bluetooth [7, 11], GSM [12, 13], UWB [14], ultrasonic [15], ZigBee [16, 17], and RFID [18–20], and so forth.…”