Analysis of the energy latency trade-off in wireless sensor networks

Wireless Sensor Networks (WSNs) haben im letzten Jahrzehnt eine erhebliche Aufmerksamkeit erlangt. Diese Netzwerke zeichnen sich durch begrenzte Energieressourcen der Sensorknoten aus. Daher ist Energieeffizienz ein wichtiges Thema in Systemdesign und -betrieb von WSNs. Diese Arbeit konzentriert sich auf großflächige Anwendungen von WSNs wie Umwelt- oder Lebensraumüberwachung, die in der Regel den Ad-hoc-Einsatz von Knoten in großen Anzahl erfordern. Ad-hoc-Einsatz und Budgetbeschränkungen hindern Entwickler an der Programmierung der Knoten mit zusätzlichen Informationen wie beispielsweise Routingtabellen, Positionskoordinaten, oder Netzwerkgrenzen. Um diese Informationen zu beschaffen, ist es üblich verschiedene Initialisierungsschemen mit erheblichen Auswirkungen auf den Energieverbrauch und den Programmieraufwand zu implementieren. In Anbetracht dieser Beschränkungen ist ein neues Paradigma für die Initialisierung und den Betrieb von WSNs notwendig, das sich durch einfachen Einsatz und minimalen Energieaufwand auszeichnet. In dieser Arbeit nutzen wir Sink-Mobilität, um den Initialisierungsoverhead und den operativen Overhead zu reduzieren. Unser erster großer Beitrag ist ein Boundary Identification Schema für WSNs mit dem Namen "Mobile Sink based Boundary Detection" (MoSBoD). Es nutzt die Sink-Mobilität um den Kommunikationsoverhead der Sensorknoten zu reduzieren, was zu einer Erhöhung der Laufzeit des WSN führt. Außerdem entstehen durch das Schema keine Einschränkungen in Bezug auf Nodeplacement, Kommunikationsmodell, oder Ortsinformationen der Knoten. Der zweite große Beitrag ist das Congestion avoidance low Latency and Energy efficient (CaLEe) Routingprotokoll für WSNs. CaLEe basiert auf der virtuellen Partitionierung eines Sensorsbereich in Sektoren und der diskreten Mobilität der Sink im WSN. Unsere Simulationsergebnisse zeigen, dass CaLEe, im Vergleich zum derzeitigen State-of-the-art, nicht nur eine erhebliche Reduzierung der durchschnittlichen Energy Dissipation per Node erzielt, sondern auch eine geringere durchschnittliche End-to-End Data Latency in realistischen Szenarien erreicht. Darüber hinaus haben wir festgestellt, dass kein einziges Protokoll in der Lage ist, eine Best-Case-Lösung (minimale Data Latency und minimale Energy Dissipation) für variierende Netzwerkkonfigurationen, die beispielsweise mithilfe der Parameter Kommunikationsbereich der Nodes, Nodedichte, Durchsatz des Sensorfelds definiert werden können, bieten. Daher ist der dritte Hauptbeitrag dieser Arbeit die Identifikation von (auf unterschiedlichen Netzwerkkonfigurationen basierenden) „Operational Regions“, in denen einzelne Protokolle besser arbeiten als andere. Zusammenfassend kann man sagen, dass diese Dissertation das klassische Energieeffizienzproblem der WSNs (Ressource-begrenzte Knoten) aufgreift und gleichzeitig die End-to-End Data Latency auf einen annehmbaren Rahmen eingrenzt.Wireless Sensor Networks (WSN) have gained a considerable attention over the last decade. These networks are characterized by limited amount of energy supply at sensor node. Hence, energy efficiency is an important issue in system design and operation of WSN. This thesis focuses on large-scale applications of WSN, such as environment or habitat monitoring that usually requires ad-hoc deployment of the nodes in large numbers. Ad-hoc deployment and budget constraints restrict developers from programming the nodes with information like routing tables, position coordinates of the node, boundary of the network. In order to acquire this information, state-of-the-art is to program nodes with various initialization schemes that are heavy both from WSN’s (energy consumption) and programmer’s perspectives (programming effort). In view of these particular constraints, we require a new paradigm for WSN initialization and operation, which should be easy to deploy and have minimal energy demands. In this thesis, we exploit sink mobility to reduce the WSN initialization and operational overhead. Our first major contribution is a boundary identification scheme for WSN, named “Mobile Sink based Boundary detection” (MoSBoD). It exploits the sink mobility to remove the communication overhead from the sensor nodes, which leads to an increase in the lifetime of the WSN. Furthermore, it does not impose any restrictions on node placement, communication model, or location information of the nodes. The second major contribution is Congestion avoidance low Latency and Energy efficient (CaLEe) routing protocol for WSN. CaLEe is based on virtual partitioning of a sensor field into sectors and discrete mobility of the sink in the WSN. Our simulation results showed that CaLEe not only achieve considerable reduction in average energy dissipation per node compared to current state-of-the-art routing protocols but also accomplish lesser average end-to-end data latency under realistic scenarios. Furthermore, we observe that no single protocol is capable of providing best-case solution (minium data latency and minimum energy dissipation) under varying network configurations, which can be defined using communication range of the nodes, node density, throughput of the sensor field etc. Therefore, the third major contribution of this thesis is the identification of operational regions (based on varying network configurations) where one protocol performs better than the other. In summary, this thesis revisits the classic energy efficiency problem of a WSN (that have resource-limited nodes) while keeping end-to-end data latency under acceptable bounds

MeshScan: a Fast and Efficient Handoff Scheme for IEEE 802.11 Wireless Mesh Networks

As a next generation network solution, Wireless Mesh Networks (WMN) provides fast Internet access to a large area, which is from university campus to city scale. In order to provide an uninterrupted Internet experience to a mobile client, a process called handoff is required to maintain the network connection from one Mesh Node (MN) to another MN. Ideally, handoff should be completely transparent to mobile users. A critical application like VoIP will require a handoff capability that transfers a call from one mesh node (MN) to another in less than 50 msec. However the current IEEE 802.11 standards do not address the handoff well. Studies have revealed that standard handoff on IEEE 802.11 WLANs incurs a latency of the order of hundreds of milliseconds to several seconds. Moreover, the discovery step in the handoff process accounts for more than 99% of this latency. The study addresses the latency in the discovery step by introducing an efficient and powerful client-side scan technique called MeshScan which replaces the discovery step with a unicast scan that transmits Authentication Request frames to potential MNs. A prototype of MeshScan has been developed based on the MadWifi WLAN driver on Linux operating systems. The feasibility of MeshScan to support fast handoff in WMNs has been demonstrated through extensive computer simulations and experiments under same given conditions. The results from the simulations and experiments show that the latency associated with handoff can be reduced from seconds to a few milliseconds by using the MeshScan technique. Furthermore, it is shown that MeshScan can continue to function effectively even under heavy traffic loads

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

IoT Applications Computing

The evolution of emerging and innovative technologies based on Industry 4.0 concepts are transforming society and industry into a fully digitized and networked globe. Sensing, communications, and computing embedded with ambient intelligence are at the heart of the Internet of Things (IoT), the Industrial Internet of Things (IIoT), and Industry 4.0 technologies with expanding applications in manufacturing, transportation, health, building automation, agriculture, and the environment. It is expected that the emerging technology clusters of ambient intelligence computing will not only transform modern industry but also advance societal health and wellness, as well as and make the environment more sustainable. This book uses an interdisciplinary approach to explain the complex issue of scientific and technological innovations largely based on intelligent computing

Human-Computer Interaction

In this book the reader will find a collection of 31 papers presenting different facets of Human Computer Interaction, the result of research projects and experiments as well as new approaches to design user interfaces. The book is organized according to the following main topics in a sequential order: new interaction paradigms, multimodality, usability studies on several interaction mechanisms, human factors, universal design and development methodologies and tools