The Internet of Things mission is to connect any objects to the Internet, in order to provide the ability to access everything, everywhere. It will enable people to control and monitor their environment in a very convenient way. In order to fulfill the Internet of Things mission, one idea is to wrap a non-IP based protocol stack in the objects equipped with sensors, actuators and computing resources to enable them to be connected to the Internet through a protocol translation gateway. An alternative and competing idea, is to embed the TCP/IP stack into such smart objects, enabling them to interact with the Internet seamlessly. However, in order to satisfy the Internet of Things needs such as scalability, interoperability and simplicity of configuration and management, the use of IP architecture for smart objects is of interest, since it has proven itself a highly scalable, interoperable and simple communication technology. In particular, the new optimized Internet Protocol, IPv6, which is capable of providing any single object with a unique address, accompanied by many other great features such as plug-and-play and a real end-to-end connectivity, can offer great benefits to the Internet of Things. Nevertheless, most of the smart objects specially deployed in Wireless Sensor Networks a subset of Internet of Things, are not able to adapt the large IPv6 packet because of their Link- Layer limitations. Hence, it is a quite challenging task for these devices to transmit an IPv6 packet. For this reason, the Internet Engineering Task Force organization has offered an IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN) solution in order to solve the IPv6 adaptability problem. This thesis presents the design and deployment of an IPv6-based WSN using this solution. The result of this work is building a 6LoWPAN based on the Contiki OS. This WSN is able to send the measured environment temperature to a web server and control the status of a light through the Internet in a standard, scalable, and seamless way.

Over the past few years, the interest of remote wireless sensor networks has increased with the growth of Internet of Things technology. The wireless sensor network applications vary from tracking animal movement to controlling small electrical devices. Wireless sensors deployed in remote areas where the grid is unavailable are normally powered by batteries, inducing a limited lifespan for the sensor. This thesis work presents a solution to implement solar energy harvesting to a wireless sensor network. By gathering energy from the environment and using it in conjunction with an energy storage, the lifetime of a sensor node can be extended while at the same time reducing maintenance costs. To make sensor nodes in a network energy efficient, an adaptive controller of the nodes energy consumption can be used. A network consisting of a client node and a server node was created. The client node was powered by a small solar cell in conjunction with a capacitor. A linear-quadratic tracking algorithm was implemented to adaptively change the transmission rate for a node based on its current and previous battery level and the energy harvesting model. The implementation was done using only integers. To evaluate the system for extended run-times, the battery level was simulated using MATLAB. The system was simulated for different weather conditions. The simulation results show that the system is viable for both cloudy and sunny weather conditions. The integer linear-quadratic algorithm responds to change very abruptly in comparison to a floating point-version.

In this thesis we develop, evaluate and implement a security solution for Open Controllers wireless sensor network platform. A scenario is used to describe an exemplar application showing how our system is supposed to function. The security of the platform is analyzed using a well-established threat modeling process and attack trees which result in the identification of a number of risks, which could be security weaknesses. These attack trees visualize the security weaknesses in an easy to access way even for individuals without special security expertise. We develop a security solution to counter these identified risks. The developed security solution consists of three different security levels together with a number of new security policies. Each additional level applies different security mechanisms to provide increasingly improved security for the platform. The new security policies ensure that the security solution is continuously secure during its operating time. We implement part of the security solution in the Contiki operating system to assess its function in practice. Finally we evaluate the developed security solution by looking back to the previously identified weaknesses and the implementation proving that the security solution mitigates the risks.

Radio Frequency Identification (RFID) technology is an electronic labeling technique.These electronic labels are called tags and read wirelessly. In this thesis a battery and amicroprocessor are connected to the tag. The work consisted of programming themicroprocessor to transfers sensor data into the tags memory. The tags are placed ontrains and data is collected from sensors at the train's axle. That way sensor data can betransmitted from a train to readers stationed along the railroad tracks.The aim of the project is to predict service intervals. There is currently no possibility tosee wear in real time and stop a train before it breaks. At present, there is a form of heatdetectors located along the railroad tracks to measure temperatures of wheels and axlesof passing trains. These are expensive and have the disadvantage of being able to detecterrors that have already occurred, they can not detect errors that do not radiate heat.The thesis aims to provide a solution for this. By programming a microprocessor totransmit sensor data to the tags memory it is possible for an RFID reader to read thesensor data from the tag. Ensuring that data and identity can be read from the tag atspeeds up to 250 km/h, you can get the status of a trains wagon before it breaks.

Low-power wireless technology enables numerous applications in areas from environmental monitoring and smart cities, to healthcare and recycling. But resource-constraints and the distributed nature of applications make low-power wireless networks difficult to develop and understand, resulting in increased development time, poor performance, software bugs, or even network failures. Network simulators offer full non-intrusive visibility and control, and are indispensible tools during development. But simulators do not always adequately represent the real world, limiting their applicability. In this thesis I argue that high simulation timing accuracy is important when developing high-performance low-power wireless protocols. Unlike in generic wireless network simulation, timing becomes important since low-power wireless networks use extremely timing-sensitive software techniques such as radio duty-cycling. I develop the simulation environment Cooja that can simulate low-power wireless networks with high timing accuracy. Using timing-accurate simulation, I design and develop a set of new low-power wireless protocols that improve on throughput, latency, and energy-efficiency. The problems that motivate these protocols were revealed by timing-accurate simulation. Timing-accurate software execution exposed performance bottlenecks that I address with a new communication primitive called Conditional Immediate Transmission (CIT). I show that CIT can improve on throughput in bulk transfer scenarios, and lower latency in many-to-one convergecast networks. Timing-accurate communication exposed that the hidden terminal problem is aggravated in duty-cycled networks that experience traffic bursts. I propose the Strawman mechanism that makes a radio duty-cycled network robust against traffic bursts by efficiently coping with hidden terminals. The Cooja simulation environment is available for use by others and is the default simulator in the Contiki operating system since 2006.

Trådlösa sensornätverk byggs upp av trådlösa sensorer, som gemensamt arbetar för att lösa en viss uppgift. Ett exempel på en sådan uppgift kan vara insamling av pollennivåer i luften över en stor yta. Sensornoderna vidarebefordrar datan sinsemellan tills den når en datainsamlingsnod någonstans i nätverket där den sedan lagras och efterbehandlas. Generellt gäller att sensornoder är små, billiga, kommunicerar trådlöst och har en väldigt lång livslängd. Traditionellt sett har sen- sornoder också antagits vara statiska (stillastående), vilket medför begränsningar om noderna bärs av exempelvis människor eller monteras på fordon. I detta examensarbete presenteras matmac , ett mac-protokoll som designats för att hantera mobila noder i trådlösa sensornätverk. En referensimplementa- tion av matmac har implementerats i operativsystemet Contiki och utvärderats med varierande konfigurationsparametrar, rörelsehastigheter och dataintensitet i simulatorn Cooja. Resultatet från utvärderingen visar att mekanismerna för mo- bilitetshantering i matmac främjar sensornodernas förmåga att pålitligt överföra data trots att de är mobila.

Wireless sensor networks, networks of nodes communicating wirelessly with sensing capabilities, are becoming more popular and are utilized by an increasing number of applications. Some wireless sensor networks are implemented because the usual network solutions of an always connected network could not be applied. Specifically this thesis is concerned with the case when the connection between the end-user and the network is not always available, i.e., there is only intermittent connectivity. This masters thesis gives an introduction and provides some background knowledge concerning wireless sensor networks, specifically focusing on disconnected operation. A set of building blocks will be presented to help programmers deal with programming disconnected operations. Examples to demonstrate our solution is implemented as shell commands using the Contiki operating system. Our solution was tested in the field and compared against a common, monolithic, programming approach. This practical example shows the potential significance of this thesis project in real world applications and allowed an evaluation of both the qualitative and quantitative aspects of our solution. The results of our evaluation prove that our solution offers an easier interface for the programmer to work with at the cost of possible less memory space. / Trådlösa sensornätverk, nätverk med noder som kommunicerar trådlöst och har sensorer, blir mer populära och används av i ett ökande antal applikationer. Några trådlösa sensornätverk används för att en vanlig nätverkslösning med ständigt uppkopplade noder inte går att genomföra. Det här examensjobbet är specifikt inriktat på fall när en uppkoppling mellan slutanvändaren och nätverket inte alltid är tillgängligt, t.ex. när det bara är tillfällig uppkoppling. Detta examensarbete ger en introduktion och bakgrund till trådlösa sensornätverk med fokus på programmering av frånkopplade operationer. Ett antal byggstenar har tagits fram för att hjälpa programmerare att programmera frånkopplade operationer. Exempel för att styrka vår lösning i vår rapport kommer att implementeras som shellkommandon i operativsystemet Contiki. Vår lösning kommer att testas i verkligheten och jämföras med ett vanligt, monolitisk, programmeringsangreppssätt. Detta praktiska exempel kommer visa den potentiella nyttan av detta examensarbete i verkliga applikationer och tillåta utvärdering av kvalitativa och kvantitativa aspekter på vår lösning. Resultaten från vår utvärdering bevisar att vår lösning erbjuder ett enkelt gränssnitt för programmeraren att arbeta med till en kostnad av möjligen mindre minnesplats.

The purpose of this thesis rose from tackling a specific project led by Cybercom Group. Water Sense was proposed after municipalities expressed the need to conveniently conduct measurements on water in Swedish lakes, and remotely get access to these data. The varying and infrequent nature of measurements result in an inefficient power consumption when a conventional sensor platform is used. Internet of Things is a relatively new and ever-evolving field for wireless sensor networks, where Low Power Wide-Area Network protocols are utilized to cleverly save power. One of these LPWAN protocols is LoRaWAN, a MAC layer protocol that runs on top of the PHY layer protocol LoRa. The chosen platform hardware for sensor nodes is an Adafruit feather equipped with a LoRa radio module, and the Contiki operative system was to be imported and integrated. Contiki OS is developed for small IoT systems with low-power, while offering networking mechanisms and a range of protocols typically utilized in WSNs. The adaptive and modular nature of Contiki allows for custom pairing of protocols to target a specific topology. LoRaWAN has a number of constraints that are disadvantageous for Water Sense, most prominently being a single-hop protocol. Contiki already supports several platforms with drivers, but the CPU and radio module of the Adafruit feather are not one of them. The goal was to integrate the LoRa PHY hardware with Contiki and have an adaptive platform for Water Sense and other scenarios. Unfortunately not all initial goals were achieved, and the physical layer was not fully integrated with Contiki’s APIs. However, the drivers needed for an operational physical layer were completed and range test could be conducted. Therefore, this thesis details the work done for implementing the physical layer and a study on Contiki’s data link protocols in proposed configurations for Water Sense.

Internet of Things (IoT) devices are devices with embedded sensors or software. Their usage is becoming more prevalent. They are used for smart homes, traffic tracking, weather data and sensor networks. Often IoT devices communicate wirelessly using low-power protocols. A wireless connection provides an easy way to eavesdrop on personal data or even hijack connections. Thus security measures need to be taken. Our thesis looks at a specific IoT operating system, Contiki-NG, and describes the porting process of a Transportation Layer Protocol (TLS) protocol library, MbedTLS. The porting process consists of specific modules that need to be adapted to the Contiki-NG environment. After porting, example programs that send and receive datawere written to enable performance testing that includes execution time, runtime memory usage and code space. The results of the tests were analyzed and evaluated. The produced implementation from porting MbedTLS to Contiki-NG provides a secure connection between two hosts running the TLS protocol. The highly configurable nature of MbedTLS allows the implementation to be adapted to comply to the resource constraints of platforms supported by Contiki-NG. / Internet of Things (IoT)-enheter är enheter med inbyggda sensorer eller mjukvara. Deras användning blir allt vanligare. De används för smarta hem, trafikspårning, väderdata och sensornätverk. Ofta kommunicerar IoT-enheter trådlöst med protokoll med låg energiförbrukning. En trådlös anslutning ger ett enkelt sätt att avlyssna personuppgifter eller till och med att kapa anslutningar. Därför måste säkerhetsåtgärder vidtas. Vårt examensarbete täcker ett specifikt IoT-operativsystem Contiki-NG och beskriver en portningsprocess av ett TLS-protokollbibliotek (Transportation Layer Protocol), MbedTLS. Portningen består av specifika moduler som behöver anpassas till den ursprungliga Contiki-NG-miljön. Efter portningen skrevs exempelprogram som skickar och tar emot data för att möjliggöra prestandatestning som inkluderar exekveringstid, minnesanvändning och kodutrymme. Resultaten av testerna analyserades och utvärderades. Den framställda implementeringen från att överföra MbedTLS till Contiki- NG gav en säker anslutning mellan de två ändpunkterna som kommunicerar med TLS-protokollet. Den i hög grad konfigurerbara karaktären hos MbedTLS gjorde det möjligt att anpassa implementeringen för att följa resursbegränsningarna för plattformar som stöds av Contiki-NG.

Immense amounts of water are wasted daily, and it is as important as ever to optimize our water consumption, especially considering that today around 850 million people lack access to clean water. With the rise of the Internet of Things, creating a monitoring system for this purpose becomes easier, but there arises a problem of interfacing water meters to IoT capable devices.In this thesis a framework for IoT smart water monitoring is presented. Both short range and long range communication techniques are shown, compared and discussed. Similarly, different smart water meters and their characteristics are compared.The main goal of this thesis was to implement an interface between a sensor node and the water meter, ensuring the transmission of data in an easy way. To achieve this goal, a M-Bus library integrated into Contiki-OS is presented, thereby showing that it is possible to interface a water meter with a sensor node. The implemented library is capable of changing some of the configurations of the water meter, receiving data from the water meter, as well as forwarding the data via MQTT or CoAP protocols for further processing on the server side. / Stora mängder vatten slösas dagligen och det är viktigt nu att vi optimerar vattenförbrukningen, särskilt med tanke på att cirka 850 miljoner människor idag saknar tillgång till rent vatten. Med uppkomst av Sakernas Internet blir det lättare att skapa ett övervakningssystem för detta ändamål, men det finns fortfarande problem med att ansluta vattenmätare till IoT-kompatibla enheter.I detta arbete presenteras ett ramverk för smart vattenmätning med IoT. Både kortdistansoch långdistanskommunikationsteknik presenteras, jämförs och diskuteras. På samma sätt jämförs olika smarta vattenmätare och deras egenskaper.Huvudsyftet med denna arbetet var att implementera ett gränssnitt mellan en sensornod och vattenmätare, vilket säkerställer överföring av data på ett enkelt sätt. För att uppnå detta mål presenteras ett M-Bus-bibliotek integrerat i ContikiOS, vilket visar att det är möjligt att koppla en vattenmätare till en sensornod. Det implementerade biblioteket kan ändra delar av vattenmätarens konfigurering, ta emot data från vattenmätaren, samt vidarebefordra data via MQTT eller CoAP för vidare bearbetning hos servern.