Dissertations / Theses on the topic 'Wireless Sensor Network'

Exploitation of wireless sensor networks (WSNs) in ubiquitous computing environments is continuously increasing for gathering data. Contemporary distributed software systems on WSNs for pragmatic business applications have become extremely adaptive, dynamic, heterogeneous and large scaled. Management of such system is not trivial to fulfil these features, leading to more and more complex management and configuration. Along with encompassing state of art and novel techniques for such diversely dynamic system, in this thesis two alternative techniques namely “task initiation by command” and “run-time task deployment and processing” are compared, for such system’s setup and configuration. Both techniques have their own pros and cons which makes them suitable according to the requirements and contextual situations. A lot of effort has been put to make WSNs more and more efficient in terms of computations and power consumption. Hence comparative analysis of both techniques used in this report to setup and configure WSN can be a benchmark to lead towards most appropriate solution to compensate the need of efficient energy and resource consumption.Both alternative schemes are implemented to setup WSN on Sun Microsystems sunSPOT (Small Programmable Object Technology) sensor nodes which are embedded microcontrollers and programmed them in java (j2me). It performs radio communication between wireless sensors and host via sink node also called base station, along with over the air run-time management of sensors. SunSPOTs built in libraries and KSN libraries are used to implement these alternatives and compare the memory footprint, communication pattern and energy consumption.Exploitation of wireless sensor networks (WSNs) in ubiquitous computing environments is continuously increasing for gathering data. Contemporary distributed software systems on WSNs for pragmatic business applications have become extremely adaptive, dynamic, heterogeneous and large scaled. Management of such system is not trivial to fulfil these features, leading to more and more complex management and configuration. Along with encompassing state of art and novel techniques for such diversely dynamic system, in this thesis two alternative techniques namely “task initiation by command” and “run-time task deployment and processing” are compared, for such system’s setup and configuration. Both techniques have their own pros and cons which makes them suitable according to the requirements and contextual situations. A lot of effort has been put to make WSNs more and more efficient in terms of computations and power consumption. Hence comparative analysis of both techniques used in this report to setup and configure WSN can be a benchmark to lead towards most appropriate solution to compensate the need of efficient energy and resource consumption.Both alternative schemes are implemented to setup WSN on Sun Microsystems sunSPOT (Small Programmable Object Technology) sensor nodes which are embedded microcontrollers and programmed them in java (j2me). It performs radio communication between wireless sensors and host via sink node also called base station, along with over the air run-time management of sensors. SunSPOTs built in libraries and KSN libraries are used to implement these alternatives and compare the memory footprint, communication pattern and energy consumption.

In the recent past, wireless sensor networks have been introduced to use in many applications. To

design the networks, the factors needed to be considered are the coverage area, mobility, power

consumption, communication capabilities etc. The challenging goal of our project is to create a

simulator to support the wireless sensor network simulation. The network simulator (NS-2) which

supports both wire and wireless networks is implemented to be used with the wireless sensor

network. This implementation adds the sensor network classes which are environment, sensor

agent and sensor application classes and modifies the existing classes of wireless network in NS-

2. This NS-2 based simulator is used to test routing protocols – Destination-Sequenced Distance

Vector (DSDV), and Ad-Hoc On-Demand Distance Vector (AODV) as one part of simulations.

Finally, the sensor network application models and the extension methods of this NS-2 based

simulator for simulations in specific wireless sensor network applications are proposed.

Recently, wireless sensor network (WSN) has become a promising technologywith a wide range of applications such as supply chain monitoringand environment surveillance. It is typically composed of multiple tiny devicesequipped with limited sensing, computing and wireless communicationcapabilities. Design of such networks presents several technique challengeswhile dealing with various requirements and diverse constraints. Performanceanalysis techniques are required to provide insight on design parametersand system behaviors.

Based on network calculus, we present a deterministic analysis methodfor evaluating the worst-case delay and buffer cost of sensor networks. Tothis end, three general traffic flow operators are proposed and their delayand buffer bounds are derived. These operators can be used in combinationto model any complex traffic flowing scenarios. Furthermore, the methodintegrates a variable duty cycle to allow the sensor nodes to operate at lowrates thus saving power. In an attempt to balance traffic load and improveresource utilization and performance, traffic splitting mechanisms areintroduced for mesh sensor networks. Based on network calculus, the delayand buffer bounds are derived in non-splitting and splitting scenarios.In addition, analysis of traffic splitting mechanisms are extended to sensornetworks with general topologies. To provide reliable data delivery in sensornetworks, retransmission has been adopted as one of the most popularschemes. We propose an analytical method to evaluate the maximum datatransmission delay and energy consumption of two types of retransmissionschemes: hop-by-hop retransmission and end-to-end retransmission.

We perform a case study of using sensor networks for a fresh food trackingsystem. Several experiments are carried out in the Omnet++ simulationenvironment. In order to validate the tightness of the two bounds obtainedby the analysis method, the simulation results and analytical results arecompared in the chain and mesh scenarios with various input traffic loads.From the results, we show that the analytic bounds are correct and tight.Therefore, network calculus is useful and accurate for performance analysisof wireless sensor network.

Shooter localization systems are used to detect and locate the origin of gunfire. A wireless sensor network is one possible implementation of such a system. A wireless sensor network is sensitive to synchronization errors. Localization techniques that rely on the timing will give less accurate or even useless results if the synchronization errors are too large.

This thesis focuses on the influence of synchronization errors on the abilityto localize a shooter using a wireless sensor network. A localization algorithm

is developed and implemented and the effect of synchronization errors is studied. The localization algorithm is evaluated using numerical experiments, simulations, and data from real gunshots collected at field trials.

The results indicate that the developed localization algorithm is able to localizea shooter with quite good accuracy. However, the localization performance is to a high degree influenced by the geographical configuration of the network as well as the synchronization error.

Skottlokaliseringssystem används för att upptäcka och lokalisera ursprunget för avlossade skott. Ett trådlöst sensornätverk är ett sätt att utforma ett sådant system.Trådlösa sensornätverk är känsliga för synkroniseringsfel. Lokaliseringsmetoder som bygger på tidsobservationer kommer med för stora synkroniseringsfel ge dåliga eller helt felaktiga resultat.

Detta examensarbete fokuserar på vilken inverkan synkroniseringsfel har på möjligheterna att lokalisera en skytt i ett trådlöst sensornätverk. En lokaliseringsalgoritm utvecklas och förmågan att korrekt lokalisera en skytt vid olika synkroniseringsfel undersöks. Lokaliseringsalgoritmen prövas med numeriska experiment, simuleringar och även för data från riktiga skottljud, insamlade vid fältförsök.

Resultaten visar att lokaliseringsalgoritmen fungerar tillfredställande, men att lokaliseringsförmågan till stor del påverkas av synkroniseringsfel men även av sensornätverkets geografiska utseende.

In recent years, the development of wireless sensor networks has made a great progress. Early projects focused on replacement of existing systems equipped with wires. These systems started out as simple static data collection networks with one smart central node that could decide further actions based on the content of the collected data. Through time, the intelligence has become more decentralized, which means the nodes now can cooperate in a more efficient and dynamic manner. The task given is to evaluate TinyOS and NesC on specific hardware from Crossbow Technology Inc, applied on an application called the Open Secure Office Project. This application is designed to enhance the security without negative effects on comfort in a frequently visited open-plan office. Finally, a real world system demonstration should be performed. We propose a solution where there is no urgent need to cover the entire office area with radio signals to maintain a secure sensor system. This is true as long as all entries and exits to the office area are “guarded” by some base station which has as main task to keep track of people and equipment entering or leaving the office. Small scale tests have been performed which show that it is possible to easily develop and maintain a wireless sensor network security system, that could be coordinated by alternative systems.