Accurate indoor positioning of narrowband Internet-of-Things (IoT) sensors has drawn more attention in recent years. The introduction of Bluetooth Low Energy (BLE) technology is one of the latest developments of IoT and especially applicable for Ultra-Low Power (ULP) applications. BLE is an attractive technology for indoor positioning systems because of its low-cost deployment and reasonable accuracy. Efficient indoor positioning can be achieved by deducing the sensor position from the estimated signal Angle-of-Arrival (AoA) at multiple anchors. An anchor is a base station of known position and equipped with a narrowband multi-antenna array. However, the design and implementation of indoor positioning systems based on AoA measurements involve multiple challenges. The first part of this thesis mainly addresses the impact of hardware impairments on the accuracy of AoA measurements. In practice, the subspace-based algorithms such as Multiple Signal Classification (MUSIC) suffer from sensitivity to array calibration errors coming from hardware imperfections. A detailed experimental implementation is performed using a Software Defined Radio (SDR) platform to precisely evaluate the accuracy of AoA measurements. For this purpose, a new Over-the-Air (OTA) calibration method is proposed and the array calibration error is investigated. The experimental results are compared with the theoretical analysis. These results show that array calibration errors can cause some degrees of uncertainty in AoA estimation. Moreover, we propose iterative positioning algorithms based on AoA measurements for low capacity IoT sensors with high accuracy and fair computational complexity. Efficient positioning accuracy is obtained by iterating between the angle and position estimation steps. We first develop a Data-Aided Maximum a Posteriori (DA- MAP) estimator based on the preamble of the transmitted signal. DA-MAP estimator relies on the knowledge of the transmitted signal which makes it impractical for narrowband communications where the preamble is short. For this reason, a Non-Data- Aided Maximum a Posteriori (NDA-MAP) estimator is developed to improve the AoA accuracy. The iterative positioning algorithms are therefore classified as Data-Aided Iterative (DA-It) and Non-Data-Aided Iterative (NDA-It) depending on the knowledge of the transmitted signal that is used for estimation. Both numerical and experimental analyses are carried out to evaluate the performance of the proposed algorithms. The results show that DA-MAP and NDA-MAP estimators are more accurate than MUSIC. The results also show that DA-It comes very close to the performance of the optimal approach that directly estimates the position based on the observation of the received signal, known as Direct Position Estimation (DPE). Furthermore, the NDA-It algorithm significantly outperforms the DA-It because it can use a much higher number of samples; however, it needs more iterations to converge. In addition, we evaluate the computational savings achieved by the iterative schemes compared to DPE through a detailed complexity analysis. Finally, we investigate the performance degradation of the proposed iterative algorithms due to the impact of multipath and NLOS propagation in indoor environments. Therefore, we develop an enhanced iterative positioning algorithm with an anchor selection method in order to identify and exclude NLOS anchors. The numerical results show that applying the anchor selection strategy significantly improves the positioning accuracy in indoor environments. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The diploma thesis focuses on the implementation of production management tools in the form of modern ICT technologies. The final solution, divided into software and hardware part, assists the company in applying the principles of lean manufacturing and the theory of constraints. The work includes a proposal that helps to increase enterprise productivity and eliminates excess inventory in the organization.

The emergence of Bluetooth Low Energy in combination with optimized coders has made it possible to transfer digital audio at very low bitrates, paving the way for small devices with longlasting batteries. The aim of this study is to compare the audio codecs LC3 and aptX, as well as peoples’ attitude towards audio quality in different contexts. Two open source implementations of the codecs are evaluated in terms of time for execution. Furthermore, the perceived audio quality of low bitrates are subjectively compared in a listening test in combination with a questionnaire regarding peoples’ attitude towards audio quality. The results show that LC3 is capable of delivering satisfying audio quality at very low bitrates, whilst also outperforming aptX. It will be interesting to see how LC3 will affect transmission latency, battery life and overall QoS once it is established in everyday products

The development of new energy efficient Wireless Personal Area Network (WPAN) protocols is a big factor for the increased interest in Internet of Things (IoT). However, the many protocols with overlapping applications have led to competing standards and sensor networks using different protocols, even to perform the same tasks. If different sensors in IoT uses different protocols in the same area, a single gateway connecting to all of them must support all their protocols simultaneously. This thesis studies latency, average sending time and range for Bluetooth Low Energy (BLE), 802.15.4 and Zigbee in multiprotocol mode on the nRF52840 System on Chip (SoC). In addition, an 802.15.4-based protocol synchronizing with the BLE frames using Time Division Multiple Access (TDMA) techniques was designed and implemented. This protocol could be used in sensor networks using both the BLE and 802.15.4 protocols to assure the 802.15.4-based devices will not try to transmit during the periods the gateway is busy with other communications. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

The individual monitoring of cross-country skiers’ technique-related parameters is crucial to identifying possible athlete-individual deficits that need to be corrected in order to optimize the athlete’s performance in competition. To be able to record relevant biomechanical parameters during training in the field, the development of measuring systems exploiting the athlete’s full potential is the key. Known mobile monitoring systems for measuring forces on ski poles use comparably heavy uniaxial load cells mounted on the pole with a data logger also attached to the pole or carried by the athlete. Measurements that are more accurate can be acquired using wire-based systems. However, wire-based systems are highly immobile and only usable when the athletes undergo a stationary test, e.g., on a treadmill. This paper focuses on the functional design of a measuring system using specialized, miniaturized electronics for acquiring data from strain sensors. These data are then used to determine the technique-related parameters pole force and angle of bend. The functional design is also capable of transmitting the acquired data wirelessly via Bluetooth to a smartphone that runs a proprietary app. This approach is advantageous regarding mass, dynamic behavior, analyzing functionality, and signal processing compared to the state of the art.

Abstract The Internet of Things (IoT) is already providing solutions to various tasks related to monitoring the environment and controlling devices over wired and wireless networks. It is estimated by several well-known research facilities that the number of IoT devices will be in the order of tens of billions by 2020. This inevitably brings challenges and costs in deployment, management, and maintenance of networks. The focus of this thesis is to provide solutions that mainly help in the deployment and maintenance of various wireless IoT networks. Different applications have different requirements for a wireless link coverage. It is important to utilize suitable radio technology for a particular application in order, e.g., to maximize the lifetime of a device. A wireless body area network (WBAN) typically consists of devices that are within couple of meters from each other. The WBAN is suitable for, e.g., measuring muscle activity and transferring data to a storage for processing. The wireless link can use air as a medium, or alternatively, an induced electric field to a body can be used. In this thesis, it is shown that a location of the electrodes in the body have impact to the attenuation. Home automation IoT applications are typically implemented with mid-range wireless technologies, known as wireless personal area networks (WPAN). In order to minimize and get rid of battery change operations, a wake-up receiver could be utilized in order to improve the device’s energy efficiency. The concept is introduced and performance of the current state-of-the-art works are presented. In addition, a control loop enabling a passive device to have control over an energy source is proposed. Applications that have low bandwidth requirements can be implemented with low-power wide area networks (LPWAN). One technology – LoRaWAN – is evaluated, and it is recommended as based on the results to use it in non-critical applications. / Tiivistelmä Esineiden internet (Internet of Things, IoT) mahdollistaa jo laajan kirjon erilaisia ratkaisuja ympäristön monitorointiin ja laitteiden hallintaan hyödyntäen sekä langattomia että langallisia verkkoja. Usea hyvin tunnettu tutkimusorganisaatio on arvioinut, että vuonna 2020 IoT laitteiden määrä tulee olemaan kymmenissä miljardeissa. Se luo väistämättä haasteita laitteiden sijoittamisessa, hallinnassa ja kunnossapidossa. Tämä väitöskirja keskittyy tarjoamaan ratkaisuja, jotka voivat helpottaa langattomien IoT laitteiden sijoittamisessa ja kunnossapidossa. IoT sovellusten laaja kirjo vaatii erilaisia langattomia radioteknologioita, jotta sovellukset voitaisiin toteuttaa, muun muassa, mahdollisimman energiatehokkaasti. Langattomassa kehoverkossa (wireless body area network, WBAN) käytetään usein hyvin lyhyitä langattomia linkkejä. WBAN on soveltuva esimerkiksi lihasten aktiivisuus mittauksessa ja mittaustiedon siirtämisessä talteen varastointia ja prosessointia varten. Linkki voidaan toteuttaa käyttäen ilmaa rajapintana, tai vaihtoehtoisesti, kehoa. Tässä työssä on näytetty, että käytettäessä kehoa siirtotienä, elektrodien sijainnilla on merkitystä signaalin vaimennuksen kannalta. Kotiautomaatio IoT sovellukset ovat tyypillisesti toteutettu käyttäen langatonta likiverkkoa, jossa linkin pituus sisätiloissa on alle 30 metriä. Jotta päästäisiin eroon pariston vaihto-operaatiosta tai ainakin vähennettyä niiden määrää, herätevastaanotinta käyttämällä olisi mahdollista parantaa laitteiden energiatehokkuutta. Herätevastaanotin konsepti ja tämänhetkistä huipputasoa edustavien vastaanottimien suorituskyky ovat esitetty. Lisäksi, on ehdotettu menetelmä joka takaa energian saannin passiiviselle IoT laitteelle. IoT sovellukset jotka tyytyvät vähäiseen kaistanleveyteen voidaan toteuttaa matalatehoisella laajan alueen verkolla (low-power wide area network, LPWAN). Yhden LPWAN teknologian, nimeltään LoRaWAN, suorituskykyä on evaluoitu. Tulosten perusteella suositus on hyödyntää kyseistä teknologiaa ei-kriittisissä sovelluksissa.

This project investigated the current market regarding wireless net and the communication between the tools used for diagnostics/maintenance and an embedded system. Based on documentation obtained through interviews a demo system was created based on Bluetooth Low Energy (BLE) communication between an embedded system and an Android device. This report intends to describe the tools and methods used in the design of the demo system and the result of an analysis of the BLE communication. Bluetooth Low Energy is an exciting protocol with wide applicability within the industrial field. This project investigated the communicational possibilities between a Smartphone and a Raspberry Pi and based on the results that emerged the conclusion can be drawn that BLE is a protocol with many beneficial applications within industrial IT. / Projektet undersökte dagens marknad gällande trådlösa nät samt kommunikation mellan verktyg som används för diagnostik/underhåll och ett inbyggt system. Utifrån underlaget som erhölls genom intervjuer har ett demosystem skapats som bygger på Bluetooth Low Energy (BLE) kommunikation mellan ett inbyggt system och en Android-enhet. Denna rapport avser redogöra för de verktyg och metoder som använts för att konstruera ett demosystem samt resultatet av en analys av BLE-kommunikationen. Bluetooth Low Energy är ett spännande protokoll med stora tillämpningsmöjligheter inom industrin. Detta projekt har undersökt möjligheterna att kommunicera mellan en Smartphone och en Raspberry Pi och utifrån resultaten som uppkommit kan slutsatsen dras att BLE är ett protokoll som kan ha många och fördelaktiga tillämpningar inom Industriell IT.

This report describes the development process of the mobile application HealthyWay. The application is developed as a Bachelor thesis project together with KTH Royal Institute of Technology. The applications' main function is to be the interface to a number of wearable medical electronic appliances such as bandages and pill boxes. The communication is done through Bluetooth Low Energy. The application was mainly written in 3 di erent languages, QML, C++ and Java. The most stressed point throughout this project was the importance of platform independence. The exibility had to be done on a scalable as well as on a modular level. With this in mind, QT was used to address the requirement of scalability. The modularity was achieved through an organized structure to the program accompanied by easy directives to introduce new devices. The purpose of the application is to increase the quality of life for the user. This intent could however not be concluded due to the lack of testing among users. In its current state, the application is not yet ready for deployment but instead acts as a framework for future prospects. / Den här rapporten beskriver utvecklingsprocessen för en mobilapplikation vid namn Healthy- Way. Applikationen är utvecklad som ett kandidatexamensarbete tillsammans med KTH. Applikationens huvudsakliga uppgift är att vara ett gränssnitt till medicinskt relaterad utrustning såsom plaster och pilleraskar. Kommunikationen mellan dessa sker via Bluetooth Low Energy. Applikationen skrevs huvudsakligen i 3 olika språk, QML, C++ och Java. Den viktigaste punkten genom projektets gång var att applikationen skulle vara oberoende av plattform. Flexibiliteten var tvungen att göras på både en skalbar och modulär nivå. Med detta i åtanke valdes QT för att behandla skalbarheten. Modulariteten uppnåddes genom en välplanerad struktur på programmet tillsammans med instruktioner på hur ny utrustning kan introduceras. Syftet med programmet är att öka livskvaliteten för användaren. Detta syfte kunde däremot inte slutföras på grund av bristande testning hos användare. I dagens läge är applikationen inte redo för att släppas kommersiellt, men tjänar som ett bra ramverk för framtida utveckling.

Internet of Things is the latest phenomenon in the computing industry. Even if it has not been completely defined yet, we are already surrounded by various devices connected to the Internet. This thesis project focuses on low cost and low-power wireless solutions and on the on-line backend behind the architecture. At the same time the present work also deals with Cloud Computing which can provide a highly scalable runtime environment for this backend without building an infrastructure. To handle the huge amount of data collected by billions of devices, BigData services could be used in the same cloud space. The project is a collection of the theoretical background of the Internet of Things; so as a result, it provides the reader with an overview of the concept. It also provides a walktrough of the design, implementation and testing process of a complex agricultural Internet of Things solution.

This thesis focuses on the Internet of Things and some of the most important problems it faces today. Among these are the overdependence on the Cloud and lack of autonomy, poor security and privacy, complicated initialization and power consumption. The work aims to implement a complex IoT solution that solves the discussed problems. The project is part of a collaboration with NXP Semicondutors and will be used to showcase the company's technologies.