Reducing energy consumption in mobile ad-hoc sensor networks

PhD ThesisRecent rapid development of wireless communication technologies and portable mobile devices such as tablets, smartphones and wireless sensors bring the best out of mobile computing, particularly Mobile Ad-hoc Sensor Networks (MASNETs). MASNETs are types of Mobile Ad-hoc Networks (MANETs) that are designed to consider energy in mind because they have severe resource constraints due to their lack of processing power, limited memory, and bandwidth as in Wireless Sensor Networks (WSNs). Hence, they have the characteristics, requirements, and limitations of both MANETs and WSNs. There are many potential applications of MASNETs such as a real-time target tracking and an ocean temperature monitoring. In these applications, mobility is the fundamental characteristic of the sensor nodes, and it poses many challenges to the routing algorithm. One of the greatest challenge is to provide a routing algorithm that is capable of dynamically changing its topology in the mobile environment with minimal consumption of energy. In MASNETs, the main reason of the topology change is because of the movement of mobile sensor nodes and not the node failure due to energy depletion. Since these sensor nodes are limited in power supply and have low radio frequency coverage, they easily lose their connection with neighbours, and face diffi culties in updating their routing tables. The switching process from one coverage area to another consumes more energy. This network must be able to adaptively alter the routing paths to minimize the effects of variable wireless link quality, topological changes, and transmission power levels on energy consumption of the network. Hence, nodes prefer to use as little transmission power as necessary and transmit control packets as infrequently as possible in energy constrained MASNETs. Therefore, in this thesis we propose a new dynamic energy-aware routing algorithm based on the trans- mission power control (TPC). This method effectively decreases the average percentage of packet loss and reduces the average total energy consumption which indirectly pro- long the network lifetime of MASNETs. To validate the proposed protocol, we ran the simulation on the Avrora simulator and varied speed, density, and route update interval of mobile nodes. Finally, the performance of the proposed routing algorithm was measured and compared against the basic Ad-hoc On-demand Distance Vector (AODV) routing algorithm in MASNETs.The Ministry of Education of Malaysia: The Universiti Malaysia Sarawak

Réseaux de capteurs pour applications de suivi médical

Le maintien des personnes à domicile est une perspective sérieusement envisagée dans le contexte actuel de vieillissement de la population. Selon les statistiques, près d'un habitant sur trois aurait plus de 60 ans en 2050, contre un sur cinq en 2005. Cependant, les solutions actuelles de téléassistance (bouton alarme sur un collier par exemple) ont montré leurs limites. La thèse consiste à étudier des applications du futur permettant de fournir à une personne maintenue à domicile ou à l’hôpital une meilleure solution alternative fondée sur les réseaux de capteurs, capable de mesurer certains de ses paramètres physiologiques et de transmettre des données importantes aux infirmières ou médecins. Ces applications doivent s’adapter aux besoins médicaux et avoir un coût économique faible. Nous nous sommes focalisés sur des solutions de type réseaux de capteurs qui ont un coût de développement et de mise en œuvre faibles. Ce type de réseaux de capteurs offre de nouveaux services tels que la surveillance médicale et l'amélioration de la sécurité par la propagation d'alertes d'urgence. Cependant, la forte mobilité et le changement rapide de la topologie du réseau présentent un verrou scientifique et social. En outre, l'interférence de différents capteurs augmente la difficulté d'implantation de ce genre de réseaux IEEE 802.15.4. Depuis ces dernières années, plusieurs solutions ont été étudiées, comme nous le verrons dans cette thèse. Nous nous intéressons à la fiabilité de transmission dans cette thèse, car un réseau de capteurs est très limité par la capacité de calcul, de stockage et de transfert. Nous nous interrogeons dans un premier temps sur la meilleure méthode pour la livraison des données. Nous avons sélectionné les protocoles unicast et multicast issus du domaine MANET dans le but de comparer leurs avantages et inconvénients dans le contexte des applications de surveillance médicale. Nous nous sommes intéressés aux mécanismes de mise en place et au renforcement de la route dans chacun des protocoles. Les résultats de cette première étude montrent que les protocoles multicast s’adaptent mieux aux applications, car ils permettent de réduire le nombre de paquets transmis dans le réseau. Même si certains protocoles pourraient amener une meilleure performance (en ce qui concerne le débit utile) que d’autres, aucun protocole ne satisfait une application réelle. Nous travaillons sur l’exploitation d'un réseau hétérogène en distinguant les nœuds forts et les nœuds faibles. Dans ce cadre, nous avons proposé une nouvelle approche, HMR, qui permet de mieux assurer la performance du réseau par rapport aux solutions existantes. Une dernière problématique à étudier dans cette thèse est l’agrégation de données, car les données à transmettre dans le réseau sont souvent périodiquement générées avec des tailles très restreintes (quelques octets, par exemple). Nos études montrent que l’agrégation de données est une bonne solution. Cette thèse a donné lieu à deux publications en conférences internationales avec comité de lecture. ABSTRACT : Keeping people at home is a perspective seriously considered in the current context of population aging. According to statistics, nearly one in three would have more than 60 years in 2050, against one in five in 2005. However, current solutions telecare (alarm button on a necklace, for example) have shown their limits. The thesis consists in studying future applications to provide, to a person kept at home or in the hospital, a better alternative solution based on sensor networks. A solution capable of measuring some of its physiological parameters and transmit important data nurses or doctors. These applications must adapt to the medical needs and have a low economic cost. We focused on solutions for sensor networks having a low-cost of development and implementation. This type of sensor networks offer new services such as medical monitoring and improving security by the propagation of emergency alerts. However, the high mobility and rapid change of the network topology present a scientific and social lock. Furthermore, interference of various sensors increases the difficulty of implantation of such networks IEEE 802.15.4. In recent years, several solutions have been studied, as discussed in this thesis. We are interested in the transmission reliability in this thesis, as a sensor network is very limited computing capacity, storage and transfer. We inquire in the first instance on the best method for data delivery. We selected unicast and multicast protocols from the field MANET in order to compare their advantages and disadvantages in the context of medical monitoring applications. We are interested in mechanisms of implementation and strengthening of the route in each of the protocols. The results of this first study show that the multicast protocols are better suited to these applications because they reduce the number of packets transmitted in the network. Although some protocols may lead to better performance (as regards the throughput) than others, no protocol satisfies a real application. We are working on the operation of a heterogeneous network distinguishing between strong and weak nodes. In this context, we proposed a new approach, HMR, to better ensure network performance over existing solutions. A final issue to consider in this thesis is the aggregation of data, because the data to be transmitted in the network are often periodically generated with very small size (a few bytes, for example). Our studies show that data aggregation is a good solution

Application priority framework for fixed mobile converged communication networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence in order to offer integrated broadband services. These systems will need to offer higher data transmission capacities and long battery life, which is the catalyst for an everincreasing variety of air interface technologies targeting local area to wide area connectivity. Current integrated industrial networks do not offer application aware context delivery and enhanced services for optimised networks. Application aware services provide value-added functionality to business applications by capturing, integrating, and consolidating intelligence about users and their endpoint devices from various points in the network. This thesis mainly intends to resolve the issues related to ubiquitous application aware service, fair allocation of radio access, reduced energy consumption and improved capacity. A technique that measures and evaluates the data rate demand to reduce application response time and queuing delay for multi radio interfaces is proposed. The technique overcomes the challenges of network integration, requiring no user intervention, saving battery life and selecting the radio access connection for the application requested by the end user. This study is split in two parts. The first contribution identifies some constraints of the services towards the application layer in terms of e.g. data rate and signal strength. The objectives are achieved by application controlled handover (ACH) mechanism in order to maintain acceptable data rate for real-time application services. It also looks into the impact of the radio link on the application and identifies elements and parameters like wireless link quality and handover that will influence the application type. It also identifies some enhanced traditional mechanisms such as distance controlled multihop and mesh topology required in order to support energy efficient multimedia applications. The second contribution unfolds an intelligent application priority assignment mechanism (IAPAM) for medical applications using wireless sensor networks. IAPAM proposes and evaluates a technique based on prioritising multiple virtual queues for the critical nature of medical data to improve instant transmission. Various mobility patterns (directed, controlled and random waypoint) has been investigated and compared by simulating IAPAM enabled mobile BWSN. The following topics have been studied, modelled, simulated and discussed in this thesis: 1. Application Controlled Handover (ACH) for multi radios over fibre 2. Power Controlled Scheme for mesh multi radios over fibre using ACH 3. IAPAM for Biomedical Wireless Sensor Networks (BWSN) and impact of mobility over IAPAM enabled BWSN. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in multi radios over fibre performance in terms of application response delay and power consumption by upto 75% and 15 % respectively, reduction in traffic loss by upto 53% and reduction in delay for real time application by more than 25% in some cases