Design of Indoor Positioning Systems Based on Location Fingerprinting Technique

Positioning systems enable location-awareness for mobile computers in ubiquitous and pervasive wireless computing. By utilizing location information, location-aware computers can render location-based services possible for mobile users. Indoor positioning systems based on location fingerprints of wireless local area networks have been suggested as a viable solution where the global positioning system does not work well. Instead of depending on accurate estimations of angle or distance in order to derive the location with geometry, the fingerprinting technique associates location-dependent characteristics such as received signal strength to a location and uses these characteristics to infer the location. The advantage of this technique is that it is simple to deploy with no specialized hardware required at the mobile station except the wireless network interface card. Any existing wireless local area network infrastructure can be reused for this kind of positioning system. While empirical results and performance studies of such positioning systems are presented in the literature, analytical models that can be used as a framework for efficiently designing the positioning systems are not available. This dissertation develops an analytical model as a design tool and recommends a design guideline for such positioning systems in order to expedite the deployment process. A system designer can use this framework to strike a balance between the accuracy, the precision, the location granularity, the number of access points, and the location spacing. A systematic study is used to analyze the location fingerprint and discover its unique properties. The location fingerprint based on the received signal strength is investigated. Both deterministic and probabilistic approaches of location fingerprint representations are considered. The main objectives of this work are to predict the performance of such systems using a suitable model and perform sensitivity analyses that are useful for selecting proper system parameters such as number of access points and minimum spacing between any two different locations

X-Band Front-end Module of FMCW RADAR for Collision Avoidance Application

A frequency modulated continuous wave (FMCW) radar front-end module is developed as a laboratory prototype of NECTEC, NSTDA. The performance of proposed prototype is verified by the reflection test of aluminum plates in outdoor environment. The frequency domain data from a spectrum analyzer was measured at every 20 meters of the distance between the front-end prototype and the aluminum plate until the maximum distance of 200 meters is reached. The calculation of the beat frequencies at different range of reflecting aluminum plates is presented. The maximum error between measured and calculated distances does not exceed 5.02 percent. The effect of different radar cross section (RCS) of reflecting objects of 0.3, 0.8 and 1.5 m2 plate area are analyzed. The low value of different received power ratio per one squared meter unit area of 0.66 percent is obtained to prove the consistency of reflected power level over the different size of object under test.

Performance Improvement Design of Bluetooth Low Energy-Based Wireless Indoor Positioning Systems

The systematic design of wireless indoor positioning systems can offer another essential approach to achieving the required performance objectives aside from using suitable location determination algorithms. This manuscript investigates Bluetooth Low Energy- (BLE-) based wireless indoor positioning systems and how adjusting the system design parameters can affect their location determination performance. Without placing emphasis on sophisticated location determination algorithms, this work provides guidelines for how a system designer can control the balance among multiple positioning performance metrics. For example, a balance between the number of installed reference nodes and the accuracy performance can be chosen to control deployment costs, such as the installation expense, infrastructure expense, and installation time. To demonstrate our baseline study, we compare three different designs of BLE wireless indoor positioning system that utilize location determination algorithms based on proximity, trilateration, and scene analysis. These designs are also compared over two different building sizes, which are medium and large. The design model and performance analysis data were based on our actual implementation of the hardware and software system for a BLE wireless indoor positioning system. Specifically, the received signal strength indication data were collected from our prototype reference nodes. The findings from our study indicated that a proximity-based system can only provide fair location accuracy performance (average error distance of 5 m to 7 m) making it unsuitable for applications that require high accuracy. For medium location accuracy performance (average error distance of 3 m to 5 m), the trilateration-based system can achieve the highest efficiency in terms of number of installed reference nodes over the accuracy. The trilateration-based system can reduce the number of installed reference nodes by 154% to achieve the same level of accuracy as the scene analysis-based system. For good location accuracy performance (average error distance ≤ 3 m), the scene analysis-based system yields the highest scalability performance in terms of installed reference nodes. The scene analysis-based system can reduce the number of reference nodes by 40% and 113% to achieve the same accuracy performance when compared with trilateration and proximity-based systems, respectively. Finally, the validation results from the actual installation of Bluetooth-based indoor positioning systems confirmed that our proposed framework can help the system designers to achieve the required performance goal

Robust System Design Using BILP for Wireless Indoor Positioning Systems

In wireless indoor positioning system designs, reference node (RN) failures during the online phase cause received signal strength values to be unavailable. This leads to accuracy performance degradation and a lack of system reliability in smart office systems. Moreover, the major design concern in the reliability of indoor positioning systems under the faulty RNs during the online phase has not been yet investigated in previous works. To address these gaps, we propose a novel mathematical formulation using a Binary Integer Linear Programming (BILP) approach that employs the Simulated Annealing (SA) solution technique. The proposed robust system design aims to put in place a suitable number of RNs and to determine their optimum locations, which may be located on a single floor or on multiple floors. In particular, the proposed system design provisions to support robust operation both during a normal situation and when there are some RN failures. Experimental results and comparative performance evaluation revealed that the proposed robust system design outperformed other system designs and was able to achieve the highest location accuracy performance in both fault-free and RN-failure scenarios. Specifically, when nine of the RNs in a three-story building failed, the proposed system design achieved 84.6%, 54.7%, and 32.9% more accurate performance than the Uniform, the MSMR, and the PhI-Uni, respectively

Robust Floor Determination Algorithm for Indoor Wireless Localization Systems under Reference Node Failure

One of the challenging problems for indoor wireless multifloor positioning systems is the presence of reference node (RN) failures, which cause the values of received signal strength (RSS) to be missed during the online positioning phase of the location fingerprinting technique. This leads to performance degradation in terms of floor accuracy, which in turn affects other localization procedures. This paper presents a robust floor determination algorithm called Robust Mean of Sum-RSS (RMoS), which can accurately determine the floor on which mobile objects are located and can work under either the fault-free scenario or the RN-failure scenarios. The proposed fault tolerance floor algorithm is based on the mean of the summation of the strongest RSSs obtained from the IEEE 802.15.4 Wireless Sensor Networks (WSNs) during the online phase. The performance of the proposed algorithm is compared with those of different floor determination algorithms in literature. The experimental results show that the proposed robust floor determination algorithm outperformed the other floor algorithms and can achieve the highest percentage of floor determination accuracy in all scenarios tested. Specifically, the proposed algorithm can achieve greater than 95% correct floor determination under the scenario in which 40% of RNs failed

Node Calibration in UWB-Based RTLSs Using Multiple Simultaneous Ranging

Ultra-wideband (UWB) networks are gaining wide acceptance in short- to medium-range wireless sensing and positioning applications in indoor environments due to their capability of providing high-ranging accuracy. However, the performance is highly related to the accuracy of measured position and antenna delay of anchor nodes, which form a reference positioning system of fixed infrastructure nodes. Usually, the position and antenna delay of the anchor nodes are measured separately as a standard initial procedure. Such separate measurement procedures require relatively more time and manual interventions. This paper presents a system that simultaneously measures the position and antenna delay of the anchor nodes. It provides comprehensive mathematical modeling, design, and implementation of the proposed system. An experimental evaluation in a line-of-sight (LOS) environment shows the effectiveness of the anchor nodes, whose position and antenna delay values are measured by the proposed system, in localizing a mobile node