Wireless Local Area Network Location Research Articles

A Novel Location Estimation for Indoor WLAN Rectangular Node Geometry

Indoor Wireless Local Area Network location estimation using received signal strength indication (RSSI) has gained importance due to its low cost and implementation simplicity. This paper presents RSSI based localisation accuracy for user nodes arranged in varying rectangular geometrical configuration. The rectangular node emplacement is commonly used node emplacement pattern in computational and cyber environments such as libraries, labs. The location estimation for nodes in different node arrangement is a challenging task due to multi user interference and multi path propagation. The proposed work is backed up by our preceding article to investigate path loss variations for varying aspect ratio of rectangular receiver node configurations. The Cramer–Rao lower bound of range estimate between access point and the receiver nodes is computed to assess localisation performance. Proposed statistical approach has a better performance compared to a geometric technique to find range estimate using multilateration with linearization algorithm. Results also show that location accuracy attains the maximum accuracy for the highest value of aspect ratio of node geometry equal to 2.80. The work is also useful in resource management and to design a better interior space to place nodes to access quality signals.

Hybrid WLAN-RFID Indoor Localization Solution Utilizing Textile Tag

This letter presents a novel hybrid configuration for indoor positioning, utilizing the passive radio frequency identification (RFID) and wireless local area network (WLAN). Our architecture is based on a mobile device with a WLAN receiver, a textile RFID tag, and one or several RFID readers communicating with the mobile. The proposed passive textile RFID tag provides a very cost effective, power efficient, and easily implemented solution for human positioning and tracking applications. In addition, the joint utilization of two technologies increases the accuracy of the indoor positioning service. Our main contribution comes from the innovative RFID-WLAN hybrid architecture based on received signal strengths and able to improve the localization accuracy compared to pure RFID and pure WLAN location solutions. The proposed algorithm is tested with real-field measurements.

Characterization of Smart Phone Received Signal Strength Indication for WLAN Indoor Positioning Accuracy Improvement

Considering that indoor positioning applications based on wireless local area network location fingerprinting would be mainly used on the mobile devices. This paper investigates the differences of received signal strength indication (RSSI) between different smart phones and the distributions of RSSI are also analyzed. The statistical analysis of experimental results shows the differences of RSSI between different smart phones are not trivial. Nearly 65% of the RSSI histograms are significantly peaked relative to Gaussian distribution and 65% of them are left-skewed distribution. Therefore, taking skewness and kurtosis coefficients into account, Gaussian distribution is not sufficient to ensure an accurate modeling of the RSSI. The impacts of human behavior on RSSI distribution are explored and two types of human behavior are revealed to be the cause of bi-modal distribution. The statistical data analysis could enable smart phone indoor positioning systems designers to improve positioning performance and to model location fingerprinting based indoor positioning systems.

Sensor Measurements for Wi-Fi Location with Emphasis on Time-of-Arrival Ranging

Wireless local area network (WLAN) location is the perfect complement to global positioning system (GPS) receivers for providing users with location information. WLAN operates in many areas in which GPS receivers cannot establish a lock, such as in indoor environments and metropolitan (obstruction by tall buildings) areas. There are many references to WLAN location in scientific literature. Most of this literature concentrates on signal-strength-based approaches. The advantage of signal strength approaches is that they are easy to implement, usually only requiring software modifications. In this paper, we discuss a novel time of arrival (TOA) approach that Intel research has developed. Although this approach typically requires minor silicon or firmware modifications to implement, it can deliver significant performance improvements over signal-strength-based measurements, as shown in this paper. Currently, Intel is introducing this method as an approach to add fine-accuracy location into the IEEE WLAN standard, 802.11 v.