Indoor Localization Using Multiple Wireless Technologies

Abstract

Abstract-Indoor localization techniques using location fingerprints are gaining popularity because of their cost-effectiveness compared to other infrastructure-based location systems. However, their reported accuracy fall short of their counterparts. In this paper, we investigate many aspects of fingerprint-based location systems in order to enhance their accuracy. First, we derive analytically a robust location fingerprint definition, and then verify it experimentally as well. We also devise a way to facilitate under-trained location systems through simple linear regression technique. This technique reduces the training time and effort, and can be particularly useful when the surrounding or setup of the localization area changes. We further show experimentally that because of the positions of some access points or the environmental factors around them, their signal strength correlates nicely with distance. We argue that it would be more beneficial to give special consideration to these access points for location computation, owing to their ability to distinguish locations distinctly in signal space. The probability of encountering such access points will be even higher when we denote a location's signature using the signals of multiple wireless technologies collectively. We present the results of two well-known localization algorithms (K-Nearest Neighbor and Bayesian Probabilistic Model) when the above factors are exploited, using Bluetooth and Wi-Fi signals. We have observed significant improvement in their accuracy when our ideas are implemented.

An ETX Based Positioning System for Wireless Ad-Hoc Networks

“…Therefore, they find applicability in localizing inexpensive nodes in ad-hoc networks. Generally, various link layer metrics, e.g., RSS [4], ordered sequence of RSSs [15], Signal Strength Difference (SSD) [16], Signal-to-Noise Ratio (SNR), signal quality, etc. are utilized as location estimation parameters.…”

“…These location fingerprinting solutions try to build a positioning system on top of existing infrastructure (e.g., Wi-Fi networks) [20,21,16]. Some locationdependent signal parameters (e.g., RSS) are collected at a number of locations as location fingerprints in an "offline training phase".…”

“…The signal parameters measured during the location determination phase is compared with the data of the radio-map collected beforehand, which is just pattern matching in signal space. Although RSS is reported to vary with many factors [15,24], fingerprinting techniques based on RSS is quite popular in existing literature [20,21,16] which provide reasonable average accuracy (2 ∼ 4 m). Our results here show similar trend (see Table 2).…”

Why The Accuracy Of The Received Signal Strengths As A Positioning Technique Was Not Accurate?

“…There exits two categories of positioning systems: indoors techniques [16] [24][25] [26] and outdoor techniques. We focus here on the outdoor techniques.…”

Fingerprint-Based Location Estimation with Virtual Access Points

“…Note that our Bluetooth adapters provide absolute RSS metric. In addition, rather than using pure RSS values, we have utilized Signal Strength Differences (SSD) [8] to denote a location's fingerprint, which give better performance.…”