A Wireless Personal Area Network (WPAN) is an ad hoc network that consists of devices that surround an individual or an object. Bluetooth® technology is especially suitable for formation of WPANs due to the pervasiveness of devices with Bluetooth® chipsets, its operation in the unlicensed Industrial, Scientific, Medical (ISM) frequency band, and its interference resilience. Bluetooth® technology has great potential to become the de facto standard for communication between heterogeneous devices in WPANs. The piconet, which is the basic Bluetooth® networking unit, utilizes a Master/Slave (MS) configuration that permits only a single master and up to seven active slave devices. This structure limitation prevents Bluetooth® devices from directly participating in larger Mobile Ad Hoc Networks (MANETs) and Wireless Personal Area Networks (WPANs). In order to build larger Bluetooth® topologies, called scatternets, individual piconets must be interconnected. Since each piconet has a unique frequency hopping sequence, piconet interconnections are done by allowing some nodes, called bridges, to participate in more than one piconet. These bridge nodes divide their time between piconets by switching between Frequency Hopping (FH) channels and synchronizing to the piconet's master. In this dissertation we address scatternet formation, routing, and security to make Bluetooth® scatternet communication feasible. We define criteria for efficient scatternet topologies, describe characteristics of different scatternet topology models as well as compare and contrast their properties, classify existing scatternet formation approaches based on the aforementioned models, and propose a distributed scatternet formation algorithm that efficiently forms a scatternet topology and is resilient to node failures. We propose a hybrid routing algorithm, using a bridge link agnostic approach, that provides on-demand discovery of destination devices by their address or by the services that devices provide to their peers, by extending the Service Discovery Protocol (SDP) to scatternets. We also propose a link level security scheme that provides secure communication between adjacent piconet masters, within what we call an Extended Scatternet Neighborhood (ESN).

The IEEE802.15.4 Low Rate-Wireless Personal Area Network (LR-WLAN) is characterized by its low power consumption, low cost, and reliable data transfer. LR-WPAN can be used for security monitoring, by automatically setting various sensors which can be placed anywhere in the factory or home. This work implements baseband signal processing and circuit design for the 868/915MHz mode of the IEEE802.15.4 LR-WPAN. The development processes include algorithm design, system simulation, FPGA implementation and system measurements. The receiver algorithm includes packet detection, phase mapping, frequency offset estimation, energy detection, synchronization, despreading and differential decoding. All algorithms are completely described herein. The system simulation match the required specifications after running the algorithms. Additionally, algorithms are composed by the Verilog Hardware Description Language (VHDL) form. The process is designed according to the hardware to identify exactly each link . The simulations performed in this work include behavioral simulation and gate level simulation. Finally, the program is uploaded to the FPGA to verify results of the procedures is verified by Matlab, by determining the effects of transmission on the channel signal, including idle signals, initial phase, frequency offset and noise. The frequency offset arises when the oscillators of the transmitter and receiver do not match. The transmitter signal from the logic analyzer is then input to the FPGA. The signal sent from the logic analyzer is tested to determine whether it retains the original transmission signal homology. Finally, a LR-WPAN baseband circuit is successfully developed through by the above procedures.

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This thesis describes the work process two (WP2) of a project led by the traffic administration in Stockholm to achieve the passengers' thermal comfort in traffic buses.  The purpose of this thesis is to design and implement a measurement system comprised in eight measurement position in a bus. Each position is able to transmit data using a wireless communication protocol, with a central unit collecting all the transmitted data taking into consideration the accuracy of the measurements and filtering out the incorrect data. In order to accomplish this, a literature study is conducted investigating different measurement methods for different parameters, different communication protocols were analysed as well to determine an appropriate communication protocol suitable for climate measurement in a bus environment with passengers present on board.  The output of the HVAC system is also required to help the traffic administration demonstrate the results of adjusting the temperature in the bus to reach the thermal comfort and how it led to saving energy. The system incorporates ZigBee , ESP32 microcontroller in the sender positions and a Raspberry pi operating as a central unit to collect data and store it in a file system providing an accurate data that will help the traffic administration achieve their goals. Unfortunately, there were some diffculties accessing CAN system data to provide the output of the HVAC system. / Detta examensarbete beskriver arbetsprocess två i ett projekt som leds av trafikförvaltningen i Stockholm för att uppnå termiska komfort för passagerare i busstrafik.  Syftet med detta examensarbete är att utforma och implementera ett mätsystem bestående av åtta positioner i en buss. Varje position kan överföra data med hjälp av ett trådlöst kommunikationsprotokoll, en central enhet samlar in all data med hänsyn till mätningens noggrannhet och filtrering av felaktig data. För att uppnå detta utfördes en litteraturstudie för att undersöka mätningsmetoder för de olika parametrar. Olika kommunikationsprotokoll undersöktes för att bestämma en lämplig kommunikationsprotkoll för ett mätsystem som mäter klimat i bussar med passagerare ombord. Uteffekten av HVAC-systemet krävs också för att hjälpa trafikförvaltningen att bestämma fördelarna med att justera temperaturen i bussen för att nå den termiska komforten och hur den ledde till att spara energi. Systemet inkorporerar kommunikaitonsprotokollet ZigBee, ESP32-mikrokontroller i avsändarpositionerna och en Raspberry pi som fungerade som en central enhet för att samla in data och lagra det i ett filsystem med korrekta data som hjälper trafikförvaltningen att uppnå sina mål. Svårigheter uppstod med att få tillgång till CAN-system data för uteffekten av HVAC-systemet.

The widespread use of wireless technologies has led to a tremendous development in wireless communication systems. Currently, an individual mobile user may carry multiple personal devices with multiple wireless interfaces, which can interconnect with each other to form a Wireless Personal Area Network (WPAN) which moves with this user. These devices exist in a heterogeneous environment which is composed of various wireless networks with differing coverage and access technologies and also the topology, device conditions and wireless connections in the WPAN may be dynamically changing. Such individual mobile users require ubiquitous communications anytime, anywhere, with any device and wish content to be efficiently and continuously transferred across the various wireless networks both outside and inside WPANs, wherever they move. This thesis presents research carried out into how to implement ubiquitous communications for WPANs in such an environment. Two main issues are considered. The first is how to initiate content transfer and keep it continuous, no matter which wireless network is used as a user moves or how the WPAN changes dynamically. The second is how to implement this transfer in the most efficient way: selecting the most suitable transfer mode for a WPAN according to the user’s and application’s requirements. User-centric (personal-area-centric) and contentcentric mechanisms are proposed in this thesis to address these issues. A scheme based on a Personal Distributed Environment (PDE) concept and designed as a logical user-based management entity is presented. This is based on three mechanisms which are proposed to overcome the technical problems in practical scenarios, which cannot be solved by existing approaches. A novel mechanism is proposed to combine local direct and global mobile communications, in order to implement ubiquitous communications in both infrastructure-less and infrastructurebased networks. This enables an individual user’s ubiquitous communications to be initiated in an infrastructure-less network environment and kept continuous when they move across infrastructure-based networks. Its advantages are evaluated by a performance analysis model and compared to existing solutions and verified by experiments. A cooperation and management scheme is also proposed for dynamic changes of multiple mobile routers and flexible switching of personal device roles in a WPAN while keeping ongoing ubiquitous communications continuous. This adopts a novel view of WPANs which solves the addressing problems caused by changes of mobile routers and makes these transparent to personal devices in the WPAN and external content sources. It provides an efficient method for changing the mobile router of a single WPAN or a WPAN merging with another moving network. Its benefits are demonstrated through performance analysis models. Finally, a novel user-centric and contentcentric mechanism for decision making, to select the most appropriate mobile router in a dynamically changing WPAN environment is proposed. This selects the most suitable content transfer mode for the WPAN to fulfil an individual user’s various requirements. It has different strategies to suit various types of applications. Selection results are demonstrated to verify the proposed mechanism in multiple scenarios of changing user requirements, applications and WPAN conditions.

Body sensor networking is a rapidly growing technology. Today wearable sensors are used to measure and monitor e.g. pulse, temperature, skin conductance, heart activity, and movement (through GPS or inertial measurement units). Mobile phones can act as coordinating nodes in wireless personal area networks used in home automation, healthcare, sport and wellness e.g. to measure pulse and distance. Integration of data from multiple sources sensors (data fusion) means that data from each sensor node needs to be associated with data from other sensor nodes sampled at approximately the same time. Accurate methods for time synchronization are therefore a necessary prerequisite for reliable data fusion. This thesis studies time synchronization problems in Bluetooth piconets between multiple wireless sensor nodes connected to a mobile phone that acts as coordinating node. Three different algorithms to enable correct data fusion have been developed, implemented and evaluated. The first is a single clock solution that synchronizes multiple wireless sensor nodes based solely on the mobile phone’s clock. The other two algorithms synchronize the clocks in sensor nodes to the clock in the coordinating node. / <p>QC 20130605</p>

Abstract Impulse radio ultra-wideband (IR-UWB) technology, due to its baseband signaling, potentially offers a low cost, low complexity and low power consumption option for different short range sensor network applications. These sensor networks can be applied to many kinds of future implementations, including the Internet of Things (IoT) applications. In the medical and healthcare context, the term wireless body area network (WBAN) is often used, but, as mentioned, the wireless technology itself can be applied to any kind of body, e.g., to car or robot body networks. This thesis studies IR-UWB receivers’ performances in different hospital environment channel models by means of computer simulation. The main focus is on receivers that are capable of detecting the signals specified either in the IEEE 802.15.4-2015 or in the IEEE 802.15.6-2012 standards. The used channel models from two independent research groups include both on-body to on-body and on-body to off-body scenarios in different hospital environments. The evaluations and comparisons of various receivers include energy detector (ED) and rake receivers, the latter with both selective- and partial-rake structures. One of the studied receiver structures is further analyzed as it was noticed that the simulation results did not correspond to the assumed theoretical bit error probability (BEP) curves. Along the standards based studies, some modifications are also suggested for the two existing IR-UWB standards for increased compatibility and improved performance. One of the propositions resulted a Patent Cooperation Treaty (PCT) patent application. Additionally, an extensive survey is provided offering a compilation which includes presentations of IR-UWB research by other researchers, existing standards’ IR-UWB physical layer (PHY) specifications and the main global regulations concerning UWB. / Tiivistelmä Erittäin laajakaistainen impulssiradioteknologia (IR-UWB) tarjoaa potentiaalisen vaihtoehdon yksinkertaisille, edullisille ja matalan tehonkulutuksen omaaville lähetin-vastaanotin-ratkaisuille, jotka soveltuvat lyhyen kantaman sensoriverkkoihin. Nämä sensoriverkot ovat monikäyttöisiä soveltuen esimerkiksi tulevaisuuden esineiden internetin (IoT) tiedonsiirtoratkaisuiksi. Esimerkiksi sairaanhoidon ja terveydenhuollon asiayhteyksissä käytetään monesti termiä langaton kehoverkko (WBAN), joka voidaan asentaa monenlaisiin eri sovelluskohteisiin kuten autoon tai vaikkapa robotin "keholle". Tässä väitöskirjassa on tutkittu tietokonesimulaatioiden avulla erilaisten IR-UWB vastaanotinrakenteiden suorituskykyä sairaalaympäristöä mallintavissa radiokanavissa. Tutkimuksen painopiste on vastaanottimissa, jotka kykenevät vastaanottamaan joko IEEE 802.15.4-2015- tai IEEE 802.15.6-2012-standardeissa määritellyn signaalin. Sairaalaympäristöä mallintavat radiokanavat perustuvat kahden toisistaan riippumattoman tutkijaryhmän mallinnuksiin, jotka sisältävät sekä keholta-keholle että keholta-kehon ulkopuolelle -radiokanavamallit. Energiailmaisin (ED) ja erilaiset harava-vastaanottimet ovat niitä vastaanotinrakenteita, joita tähän väitöskirjaan kuuluvissa artikkeleissa on arvioitu ja vertailtu. Yhtä vastaanotinrakennetta on myös analysoitu tarkemmin, kun havaittiin, etteivät kyseistä rakennetta koskevat simulaatiotulokset vastanneet oletettuja teoreettisia bittivirhetodennäköisyyksiä. Tutkimuksessa kehitettiin lisäksi olemassa olevien standardien ratkaisuihin liittyviä parannusehdotuksia, joita esitettiin muutamissa tähän väitöskirjaan sisällytetyissä artikkeleissa. Yhdestä ehdotuksesta tehtiin myös PCT-sopimuksen alainen patentointihakemus. Lisäksi yhdessä tähän väitöskirjaan sisällytetyssä artikkelissa on paitsi laaja kirjallisuuskatsaus sisältäen katsauksen muiden tekemiin IR-UWB- tutkimuksiin, myös olemassa olevien standardien fyysisten kerroksien määritykset koskien IR-UWB-teknologiaa ja tärkeimmät maailmanlaajuiset UWB-tekniikkaa koskevat signaalin tehotiheysmääräykset.

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.

Computer networks are in the scope of the IEEE organization normalized by the 802 board which currently comprises six working groups for wireless communications. IEEE 802.11 for wireless local area networks, IEEE  802.15 for wireless personal area networks, IEEE 802.16 for wireless metropolitan area networks, IEEE 802.20 for mobile broadband wireless access, IEEE 802.21 for media independent handover and IEEE 802.22 for wireless regional area networks. This master's thesis focuses on a security analysis of particular standards, describes threats, vulnerabilities, current security measures and mutually compares wireless specifications from a security point of view. The conclusion is devoted to overall evaluation of the project, to its contributions, possible enhancements and continuation in the form of consequential studies.