A method for estimating distance, in one dimension, to a transmitter for a receiver in motion relative to that transmitter is given with simulation data. The method relies on a stateful preprocessor filter and does not require envelopment of the transmitter.

Les systèmes de localisation en temps réel (Real-Time Locating System - RTLS) sont de plus en plus employés dans l'industrie. Ils permettent l'automatisation de diverses tâches telles que l'identification et le suivi des objets au long de la chaîne d'approvisionnement, la surveillance d'équipements dans les usines et la sécurisation des biens. Ces systèmes sont basés sur des capteurs électroniques sans fil à faible puissance et à faible coût avec des antennes intégrées. Dans notre contexte, deux types de capteurs sont utilisés. Les tags de référence sont généralement fixés sur les murs tandis que les tags mobiles sont fixés sur les objets qui doivent être suivis. Notre système RTLS (Real Time Localisation System) exploite la puissance du signal reçu (Received Signal Strength Indication - RSSI) pour calculer la localisation des tags mobiles. Toutefois, la performance de ce système peut être influencée par plusieurs facteurs. Tout d'abord, par rapport à l'antenne, la non-uniformité du diagramme de rayonnement et le non-alignement de la polarisation des antennes peuvent affecter la puissance du signal reçu. De plus, l'impact de l'environnement résulte sur des multi-trajets qui dégradent la précision de la localisation. Dans la première partie de ce travail, nous proposons une solution pour le tag de référence en utilisant un plan réflecteur en métal pour améliorer son diagramme de rayonnement. Nous avons effectué plusieurs expériences utilisant un logiciel de simulation et nous démontrons que l'utilisation d'un plan réflecteur en métal améliore considérablement la précision de la localisation de notre système. Dans la deuxième partie, nous proposons d'utiliser des techniques de diversité d'antenne pour le tag mobile afin de minimiser les effets des multi-trajets et d'améliorer le diagramme de rayonnement afin de couvrir tout l'espace souhaité pour la localisation. Nos solutions se composent de trois antennes intégrées sur le boîtier en plastique du tag, alliant la diversité de diagramme et de polarisation. Nous proposons une première structure avec trois antennes PIFAs manufacturées et fixées à l'extérieur du boîtier, un deuxième système avec deux antennes IFAs et enfin une antenne patch triangulaire sur un substrat permettant de plier les antennes, de façon à pouvoir rentrer la structure dans le boîtier du tag. Ces systèmes ont été simulés dans différents configurations de scénario afin de valider l'amélioration apportée par nos solutions. Finalement, des expérimentations ont été menées afin de comparer les systèmes proposés dans un environnement réel. Les résultats montrent que l'erreur de localisation a été divisée par un facteur proche de trois par rapport au système d'origine. / Real-Time Locating Systems (RTLS) have been increasingly employed by the industry. They allow the automation of several tasks such to identify and track objects throughout the supply chains, to watch equipment under surveillance in factories and to secure goods. These systems are usually based on low-power and low-cost wireless electronic sensors with integrated antennas. In our context, two types of sensors are used. The reference tags are generally fixed on the walls whereas mobile tags are fixed on objects that must be tracked. In particular, our RTLS uses the Received Signal Strength Indication (RSSI) to compute the location of mobile tags at 2.4GHz frequency band. However, the performance of such system can be influenced by several factors. On the one hand, the non-uniformity of the radiation pattern and the antenna polarization mismatch can affect the received signal power. On the other hand, the impact of the environment results in multipaths, which degrade the localization precision. In the first part of this thesis, we propose an approach based on a metal plane reflector to improve the radiation pattern of reference tags. We performed several experiments using a microwave simulator and we show that the metal plane reflector considerably improves the localization accuracy of our system. In the second part, we propose to use antenna diversity techniques on mobile tags to minimize multipath effects while improving the radiation pattern. Our three solutions are based on integrated antennas fixed on the tag's plastic case, combining pattern and polarization diversity. Firstly, we propose a structure composed of three Planar Inverted-F Antennas (PIFAs) manufactured and fixed outside of the plastic case. Secondly, we propose a system composed of two Inverted-F Antennas (IFAs). Then, we propose a system composed of a triangular patch antenna on a substrate that allows it to be fixed inside the plastic case. We simulated those systems in different scenarios to analyze and validate the localization improvements brought by our solutions. Finally, we performed real experiments to compare the efficiency of the proposed systems in a real environment. Our results show that the localization error was reduced approximately by a factor of three in comparison to the original system.

With the advent of wireless sensor technologies becoming more and more common-place in wearable devices and smartphones, indoor localization is becoming a heavily researched topic. One such application for this topic is in the medical field where wireless sensor devices that are capable of monitoring patient vitals and giving accurate location estimations allow for a less intrusive environment for nursing home patients. This project explores the usage of using received signal strength indication (RSSI) in conjunction with an inertial navigation system (INS) to provide location estimations without the use of GPS in a Particle Filter with a small development microcontroller and base station. The paper goes over the topics used in this thesis and the results.

Context: Wireless Sensor Networks (WSN) are applied to collect information by distributed sensor nodes (anchors) that are usually in fixed positions. Localization (estimating the location of objects) of moving sensors, devices or people which recognizes the location’s information of a moving object is one of the essential WSN services and main requirement. To find the location of a moving object, some of algorithms are based on RSSI (Received Signal Strength Indication). Since very accurate localization is not always feasible (cost, complexity and energy issues) requirement, RSSI-based method is a solution. This method has two specific features: it does not require extra hardware (cost and energy aspects) and theoretically RSSI is a function of distance. Objectives: In this thesis firstly, we develop an RSSI-based localization algorithm (server side application) to find the position of a moving object (target node) in different situations. These situations are defined in different experiments so that we observe and compare the results (finding accurate positioning). Secondly, since RSSI characteristic is highly related to the environment that an experiment is done in (moving, obstacles, temperature, humidity …) the importance and contribution of “environmental condition” in the empirical papers is studied. Methods: The first method which is a common LR (Literature Review) is carried out to find out general information about localization algorithms in (WSN) with focus on the RSSI-based method. This LR is based on papers and literature that are prepared by the collaborating company, the supervisor and also ad-hoc search in scientific IEEE database. By this method as well as relevant information, theoretical algorithm (mathematical function) and different effective parameters of the RSSI-based algorithm are defined. The second method is experimentation that is based on development of the mentioned algorithm (since experiment is usually performed in development, evaluation and problem solving research). Now, because we want to compare and evaluate results of the experiments with respect to environmental condition effect, the third method starts. The third method is SMS (Systematic mapping Study) that essentially focuses on the contribution of “environmental condition” effect in the empirical papers. Results: The results of 30 experiments and their analyses show a highly correlation between the RSSI values and environmental conditions. Also, the results of the experiments indicate that a direct signal path between a target node and anchors can improve the localization’s accuracy. Finally, the experiments’ results present that the target node’s antenna type has a clear effect on the RSSI values and in consequence distance measurement error. Our findings in the mapping study reveal that although there are a lot of studies about accuracy requirement in the context of the RSSI-based localization, there is a lack of research on the other localization requirements such as performance, reliability and stability. Also, there are a few studies which considered the RSSI localization in a real world condition. Conclusion: This thesis studies various localization methods and techniques in WSNs. Then, the thesis focuses on the RSSI-based localization by implementing one algorithm and analyzing the experiments’ results. In our experiments, we mostly focus on environmental parameters that affect localization’s accuracy. Moreover, we indicate some areas of research in this context which need more studies.

Wireless communication is becoming more common, a relatively new technology within the area is Bluetooth Low Energy. It’s been developed to be energy efficient and in regard to compatibility. Alongside the growth of wireless technology, scientists and companies are looking for new areas of use. One of these is localization, which means to determine the position of a moving device with the use of stationary devices, an example of this would be GPS.This report means to evaluate indoor localization using Bluetooth Low Energy and was made for Combitech AB in Jönköping. The purpose of the work was to determine with what accuracy and precision the position of a moving device could be estimated. The report will answer the following questions: With what accuracy and precision can the position of a device be determined within a test area of varying size using Bluetooth Low Energy? Is the accuracy and precision affected by the environment?The authors chose an inductive reasoning and therefore intended to answer the questions with the help of experimental studies. A system consisting of both software and hardware was developed and was then used to conduct multiple rounds of tests, where the size of the area and the environment was varied.By evaluating the data gathered from said tests and comparing it to theoretical studies and prior research credible results were obtained. The accuracy appears to decrease as the distance between the units is increased, however a deeper analysis shows that the difference is smaller below 500 cm. No correlation is found between environment and accuracy. When three stationary units, forming a triangle with 400 cm between the vertices, are used to determine the position of a fourth the achieved accuracy is 65 cm. During the tests the precision is not shown to decrease with distance, it seems to vary independently. However, as the environment is changed a noticeable difference is observed. In a gymnasium the standard deviation was calculated to 0.38 RSSIwhereas in an office environment it was 0.99 RSSI. In regard to the given results the authors conclude that Bluetooth Low Energy shows some potential for the use in indoor positioning systems. A possible scenario where the technology would be well suited would be when the units need to work of a coin cell battery for a large period of time, while the system must support multiple types of units and a rough estimation of the position is adequate. / Trådlös kommunikation blir allt mer vanlig i vår vardag, en relativt ny teknik inom detta område är Bluetooth Low Energy som utvecklats med avseende på energieffektivitet och kompabilitet. Parallellt med den trådlösa teknikens spridning letar forskare, såväl som företag, efter nya användningsområden. En av dessa är lokalisering, vilket innebär att med fasta enheter avgöra rörliga enheters position, ett exempel på detta är GPS. Detta arbete handlar om att utvärdera inomhuslokalisering med Bluetooth Low Energy och gjordes på uppdrag av Combitech AB i Jönköping. Syftet var att undersöka med vilken noggrannhet och precision en rörlig enhets position kunde avgöras. Rapporten kommer att besvara följande frågeställningar: Med vilken noggrannhet och precision kan man med Bluetooth Low Energy avgöra en enhets position inom ett testområde med varierande storlek? Påverkas noggrannhet och precision av omgivningen?Författarna valde en induktiv metod och ämnade därför besvara frågeställningarna med hjälp av experimentella studier. Ett testsystem bestående av hård- samt mjukvara utvecklades varpå tester utfördes i flera omgångar, där storlek på område och omgivning varierades. Genom utvärdering av testdata i förhållande till teoretiska studier och tidigare forskning kunde trovärdiga resultat nås. Noggrannheten tycks minska då avståndet mellan enheter ökas, djupare analys pekar på en mindre förlust under 500 cm. Det observeras dock inget samband mellan noggrannhet och omgivning. Då tre fasta enheter placeras med ett inbördes avstånd på 400 cm kan positionen avgöras med 65 cm noggrannhet. Precisionen påverkas under testerna inte av avstånd, signalstyrkevärdena varierar helt oberoende av detta. Vid skifte av omgivning tydliggörs dock en markant skillnad i resultat. I en idrottshall beräknades standardavvikelsen till 0,38 RSSI medan den i en kontorsmiljö var 0,99 RSSI.Författarna drar utifrån det uppnådda resultat slutsatsen att Bluetooth Low Energy har viss potential att användas för inomhuslokalisering. Exempel på ett möjligt scenario där tekniken anses väl lämpad är då de fasta enheterna måste drivas av knappcellsbatterier under en lång tidsperiod, att systemet skall stödja en mängd olika enheter samt att en grov uppskattning av position är tillräcklig.

Do we always have to be lost in the halls of a big school on an already stressful first day of class? This paper has evaluated a prototype indoor navigation system that uses a ANT wireless protocol. The protocol has been placed into nodes (small electrical devices, hardware) which are then placed around an area of interest (a map), like beacons, using RSSI (signal from the nodes) to help determine where the subject is located. The mobile application is made specific to Android with a search algorithm that is based off of vector analysis with weighted percentages. The idea being that if the position of each node is available, knowing the location between the nodes should be easily achievable. The nodes were build successfully along with an android application to verify each nodes functionally and see the nodes RSSI values. The algorithm works as expected but due to several factors was not able to be fully realized. In the actual test the system results where slow and did not update in real time. It was found that the ANT protocol does not have a fast packet reception when using the continuous scan feature made available by ANT. The results of the search algorithm were not good enough for a real time indoor navigation prototype. The search algorithm was slow. The system needs more inputs to accurately locate a subject indoors.

The intent of this master’s thesis is to look for the best solution of finding lost items of everyday use. Described solution is based on GPS for outdoor and Bluetooth Low Energy for indoor localization. User of this system will be able to find his/her lost items using smartphone application.

A wireless sensor network is a network of distributed nodes each equipped with its own sensors, computational resources and transceivers. These sensors are designed to be able to sense specific phenomenon over a large geographic area and communicate this information to the user. Most sensor networks are designed to be stand-alone systems that can operate without user intervention for long periods of time. While the use of wireless sensor networks have been demonstrated in various military and commercial applications, their full potential has not been realized primarily due to the lack of efficient methods to self organize and cover the entire area of interest. Techniques currently available focus solely on homogeneous wireless sensor networks either in terms of static networks or mobile networks and suffers from device specific inadequacies such as lack of coverage, power and fault tolerance. Failing nodes result in coverage loss and breakage in communication connectivity and hence there is a pressing need for a fault tolerant system to allow replacing of the failed nodes. In this dissertation, a unique hybrid sensor network is demonstrated that includes a host of mobile sensor platforms. It is shown that the coverage area of the static sensor network can be improved by self-organizing the mobile sensor platforms to allow interaction with the static sensor nodes and thereby increase the coverage area. The performance of the hybrid sensor network is analyzed for a set of N mobile sensors to determine and optimize parameters such as the position of the mobile nodes for maximum coverage of the sensing area without loss of signal between the mobile sensors, static nodes and the central control station. A novel approach to tracking dynamic targets is also presented. Unlike other tracking methods that are based on computationally complex methods, the strategy adopted in this work is based on a computationally simple but effective technique of received signal strength indicator measurements. The algorithms developed in this dissertation are based on a number of reasonable assumptions that are easily verified in a densely distributed sensor network and require simple computations that efficiently tracks the target in the sensor field. False alarm rate, probability of detection and latency are computed and compared with other published techniques. The performance analysis of the tracking system is done on an experimental testbed and also through simulation and the improvement in accuracy over other methods is demonstrated.

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Denna studie har undersökt möjligheten att implementera ett trådlöst kommunikationssystem i en ugnsmiljö. Den trådlösa kommunikationstekniken som har använts är av standarden IEEE 802.15.4. För denna undersökning har ett trådlöst mätsystem för temperatur konstruerats. För att hålla nere temperaturen på detta mätsystem har kapslingsmaterialen keramik och glasull använts. Resultatet av mätningarna visar att kvalitén på radiokommunikationen kan förväntas vara god för de testade förhållande med kapsling och en temperatur upp till 200 grader. För de testade förhållandena i ugnsmiljön visar mätresultat att positionering är av större betydelse än värmeutvecklingen och kapslingen. / This study has explored the possibility to implement a wireless communication system in an ovenenvironment. For this exploration a wireless measurement system for temperature have beenconstructed. The technology of use is a radio communication system with the standard IEEE 802.15.4. The high temperature in the oven environment is kept down at the electronic by using anenclosure. The enclosure material that have been examined is a ceramic layer and a fibreglasslayer. The result of this study shows that the quality of the radio communication for the tested enclosureis expected to be good for temperatures up to 200 degrees. For the test cases the relation betweenthe radio module’s positioning is more important than the increase of temperature and the use ofan enclosure.