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Mobile wireless sensor networks (MWSNs) will enable information systems to gather detailed information about the environment on an unprecedented scale. These selforganising, distributed networks of sensors, processors and actuators that are capable of movement have a broad range of potential applications, including military reconnaissance, surveillance, planetary exploration and geophysical mapping. In many of the foreseen applications a certain geometric pattern will be required for the task. Hence, algorithms for maintaining the geometric pattern of an MWSN are investigated. In many tasks such as land mine detection, a group of nodes arranged in a line must provide continuous coverage between each end of the formation. Thus, we present algorithms for maintaining the geometric pattern of a group of nodes arranged in a line. An MWSN may also need to form a geometric pattern without assistance from the user. In military reconnaissance, for example, the nodes will be dropped onto the battlefield from a plane and land at random positions. The nodes will be expected to arrange themselves into a predetermined formation in order to perform a specific task. Thus, we present algorithms for forming a circle and regular polygon from a given set of random positions. The algorithms are distributed and use no communication between the nodes to minimise energy consumption. Unlike past studies of geometric problems where algorithms are either tested in simulations where each node has global knowledge of all the other nodes or implemented on a small number of robots, the robustness of our algorithms has been studied with simulations that model the sensor system in detail. / The nodes locate their neighbours using simulated vision where a ray-tracer is used to generate images of a model of the scene that would be captured by each node's cameras. The simulations demonstrate that the algorithms are robust against random errors in the sensors and actuators. Even though the nodes had incomplete knowledge of the positions of other nodes due to occlusion, they were still able to perform the assigned tasks.

In wireless ad hoc networks, the resources such as bandwidth, power, computing ability, etc., for end users are limited by the environments and hardware. In addition, the mobility of each user is different. Furthermore, the varied wireless networks with different properties such as transmission rate, coverage, power and protocols make it rarely difficult to establish and maintain the communications through the multiple intermediate nodes which are mobile devices. This dissertation will focus on the following three issues: 1. Most homogeneous wireless networks only considering one or less resources of the mobile device can not select and distribute the routes. In addition, it can cause the load of the intermediate nodes to increase. 2. The various wireless networks have different characteristics of resources. The route selection and distribution algorithms proposed before in homogeneous wireless networks are not adapted for the heterogeneous wireless networks. 3. Most route selection and distribution algorithms are designed for specific type of wireless environments (such as only for proactive type or reactive type). For different environment and different mobility, its cost will be different. To allow an environment-aware based adaptive management for heterogeneous wireless networks with different characteristics of resources becomes an important issue. In homogeneous wireless ad hoc networks, the resources of the mobile devices such as bandwidth, power, computing ability, etc., are limited and different by the environments and hardware. To evaluate the individual resource of each mobile device, the route distribution and selection algorithm considering the multiple resource variations in wireless ad hoc networks is proposed. First, the evaluation and management for individual resource of each mobile device such as bandwidth, power, and computing ability, are proposed. Second, according to the proposed algorithm, a mobile device can be estimated whether it supports the QoS or not. In addition, these resources evaluation results are transformed as the bottleneck resource information. At last, according to the bottleneck resource information of all the found routes, the route distributed through different intermediate nodes with most resources is selected for load distribution and balance. Considering the wireless network infrastructure today including 3G wireless communication, IEEE 802.11 wireless local area network, and wireless ad hoc networks, the characteristics such as transmission rates, bandwidth, power consumption, and transmission range of these wireless structures are not the same. In other words, the routing selection algorithm for homogeneous wireless networks may not be flexible for another wireless network. In this thesis, these different wireless network structures are integrated into one heterogeneous wireless network. Individual characteristics such as transmission rates, bandwidth, power consumption, and transmission range of these wireless structures are evaluated. According to the adaptive resource evaluation and route selection algorithm for the heterogeneous wireless networks, the route with the lowest cost and most resources is selected based on the integrated information of each resource estimation and the bottleneck information of each route found. Besides considering the characteristic of the heterogeneous wireless networks, the module (type) of the route selection and distribution algorithms also induces different costs and performance. The existing algorithms can be defined and divided into two typical types: proactive (table-driven) protocol and reactive (source initiated) protocol. The proactive type protocol pays the memory and periodical update (bandwidth consumption) costs for selecting the routing directly. In opposite, the reactive type protocol saves the costs but may increase the overhead for finding a routing path to the destination. To decrease the total costs of finding and maintaining routing paths, the environment-aware based adaptive management for heterogeneous wireless networks is proposed in this thesis. Corresponding to the movement of the users, the appropriate type of the routing algorithm should be selected for reducing the total costs of finding routing paths. In the adaptive management, we propose the type selection process to individually evaluate the cost of the two type protocols (proactive and reactive) via considering the protocols and the mobility of the users. According to the evaluation results, the appropriate protocol with less cost will be selected for finding and maintaining the routes in the heterogeneous wireless networks. According to the simulation, the routing selection and distribution algorithm proposed in this dissertation can not only effectively distribute the routing paths but also balance the load within homogeneous or heterogeneous wireless networks. Corresponding to the mobility of the users, the suitable type of routing protocol can be selected. Furthermore, the cost for routing paths searching, selection and maintenance is decreased. The block rate of these routing paths is reduced. Overall, according to the simulation, this dissertation makes the major contributions as follows: 1. The individual resource evaluations and managements for the mobile devices in the homogeneous wireless networks are proposed. The routes which satisfy the QoS can be selected and distributed according to the proposed algorithm. 2. The various wireless networks with different are integrated into a heterogeneous wireless network. The route search, selection, and maintenance algorithm for the hybrid properties heterogeneous wireless networks is proposed. 3. The classification to separate and classify the route search and selection algorithms is proposed. Corresponding to the mobility of the users, the environment-aware based adaptive management for heterogeneous wireless networks is proposed to reduce the costs caused by route search, selection, and maintenance.

With increased popularity and pervasiveness, mobile networking had become a definite trend for future networks. Users strongly demand the retaining of the connectivity and the QoS (Quality of Service) of ongoing services while roaming across different points of attachment. Efficient handover schemes and service paradigms are essential to the above vision. We will contribute to the QoS provisioning in mobile wireless networks from two complementary perspectives: one is the improved handover schemes at the client end for shorter latency and less packet loss, and the other is the service migration at server end for improved QoS. There are time-consuming procedures involved in the handover process. Various research works had devoted to the acceleration of movement detection and registration. However, a time-consuming operation, duplicate address detection, was overlooked by most studies. A novel scheme featuring anycast / multicast technique is developed and presented in this dissertation. The proposed approach switches to anycast / multicast addressing during handover and switches back to normal unicast addressing after all required operations are completed. By switching to anycast / multicast addressing, a mobile node can continue the reception of packets from its corresponding node before its new care-of address is actually validated. As a result, transmission disruption can be effectively minimized. In addition, simple but effective buffer control schemes are designed to reduce possible packet loss and to prevent the out-of-order problem. Analytical study reveals that improved performance can be guaranteed, as reflected in the simulation results. The establishment of mobility-supported Internet protocols, such as IPv4 and IPv6, had made it possible that an ongoing service can be retained while a mobile node is roaming across different access domains. However, limited efforts had been paid to server sides if we consider the topological change due to node mobility. In the global network environment, the weighted network distance between a client and its server could change dramatically for reasons of topology change or node mobility. A new network service framework highlighting the concept of service migration is presented in this dissertation. The proposed framework take into account essential service quality factors, such as server loading, bandwidth, delay, and so on, and then dynamically migrates an ongoing service from a distant server to a new server with shorter ¡§weighted network distance¡¨ to the client. As a result, the individual service connection, as well as the global network environment, will benefit from the service migration, in terms of improved service quality and bandwidth utilization. This dissertation explains the general architecture of the proposed framework and focuses on the technical details of the core component - service migration module. Our experiences on the functional prototypes for service migration are also reported. The success of the prototyping system is an indication of the feasibility and effectiveness of the proposed scheme.

Turbo codes have been the subject of much research in recent years, producing results very close to the theoretical limit set by Shannon. The codes have been successfully implemented in satellite and video conferencing systems and provision has been made in 3rd generation mobile systems. These codes have not been used for short frame systems due to the delay at the decoder. In this thesis, comprehensive comparisons of the two common decoding algorithms are made, with reference to short frames. The effects of increasing memory size of component codes, frame sizes, utilising puncturing and errors in channel estimation are investigated over AWGN and Rayleigh fading channels. The decoder systems are compared for complexity as well as for equal numbers of iterations. Results show that less complex decoder strategies produce good results for voice quality bit error rates. Investigations are also made into the effects of errors in signal-to-noise ratio estimation at the SOVA turbo decoder, showing this decoding algorithm to be more resilient than Log-MAP decoders in published literature. The decoders are also tested over channels displaying inter-symbol interference. Channels include a time-invariant channel and three ETSI standard time-varying channels simulating indoor, pedestrian and vehicular situations, upgraded for more realistic Doppler effect. To combat these types of channels, a derivative of turbo codes, turbo equalisation is often used. To keep receiver delay to a minimum, decision feedback equalisation is used here. Results show that the combination can produce improvements in decoded results with increasing turbo iterations where ISI is low, but that iterative improvements do not occur under harsh circumstances. The combination produces much superior results compared with codes on their own under even the most extreme circumstances.

Mobile Ad hoc Network (MANET) routing protocols are designed to provide connectivity between wireless mobile nodes that do not have access to high-speed backbone networks. While many unicast MANET protocols have been explored, research involving multicast protocols has been limited. Existing multicast algorithms attempt to reduce routing overhead, but few, if any, attempt to reduce data overhead. The broadcast nature of wireless communication creates a unique environment in which overlaps in coverage are common. When designed properly, a multicast algorithm can take advantage of these overlaps and reduce data overhead. Unlike a unicast route, in which there is one path between a sender and receiver, a multicast tree can have multiple branches between the sender and its multiple receivers. Some of these paths can be combined to reduce redundant data rebroadcasts. The extensions presented in this thesis are a combination of existing and original routing techniques that were designed to reduce data rebroadcasts by aggregating multicast data flows. One such optimization takes advantage of the multipoint relay (MPR) nodes used by the Optimized Link State Routing (OLSR) unicast protocol. These nodes are used in unicast routing to reduce network broadcast, but can be used to help create efficient multicast data flows. Additionally, by listening to routing messages meant for other nodes, a host can learn a bit about its network and may be able to make routing changes that improve the multicast tree. This protocol was implemented as a software router in Linux. It should be emphasized that this is a real implementation and not a simulation. Experiments showed that the number of data packets in the network could be reduced by as much as 19 percent. These improvements were accomplished while using only a small amount of routing overhead. / Master of Science

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The 21st Century Live Play (21CLP) program is developing a mobile, low cost, wireless networking system that supports applications to provide a number of services for military use. 21CLP is a joint Defense Advanced Research Projects Agency (DARPA) and Central Test and Evaluation Investment Program (CTEIP) project. The Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Code 382 has been assigned as the program manager for a T&E version of the 21CLP system. The 21CLP vision is a common instrumentation function that links, in real-time, live land, air and maritime entities together with a virtual battlespace in any location where forces are deployed or being trained, weapons systems are being tested and evaluated, and ultimately where missions are being conducted. This vision will be realized with an embedded, mobile, distributed, untethered system that requires little or no site preparation.

Le passage à l’échelle des protocoles de routage est un des problèmes les plus critiques pour les réseauxmobiles sans fil à grande envergure. Dans ce cadre, le concept de clusterisation peut être mis à profit dans lafonction de routage afin d’améliorer les performances de ces réseaux. En premier lieu, cette thèse présentenotre algorithme de clusterisation à 1-saut alpha-SSCA (α-Stability Structure Clustering Algorithm) qui apour objectif d’améliorer la stabilité de la structure des clusters. Un algorithme générique de clusterisationà K-sauts est également proposé en ayant le même but de stabilité visé par alpha-SSCA tout en réduisant lenombre de clusters générés et en étant indépendant de la métrique d’élection des cluster-heads. Ensuite, nousprésentons notre proposition d’un protocole de routage à état des liens des clusters qui exploite les apports denotre mécanisme de clusterisation α-SSCA. Ce protocole, appelé CLSR (Cluster-based Link State Routing),vise à réduire le trafic de contrôle afin d’améliorer les performances du réseau à large échelle. Nous avonsproposé aussi une version hiérarchique du protocole CLSR. Ce protocole de routage introduit une hiérarchiedans la structure des clusters qui permet de réduire le nombre de clusters en groupement des clusters prochesdans un même cluster. L’objectif principal de ce protocole hiérarchique est d’améliorer la scalabilité de CLSRquand le nombre de noeuds dans le réseau augmente considérablement. / Scalability is one of critical challenges for routing protocols in large scale mobile wireless networks. In thiscontext, clustering technique seems a promising approach to overcome the scalability problem. First, we proposea one hop clustering algorithm, alpha-SSCA (alpha-Stability Structure Clustering Algorithm), whichaims to improve the stability of the clusters structure. Second, we present a proposal of a generic K-hopsclustering algorithm which is independent of the metrics used to elect cluster-heads. The main contributionof this last algorithm is to enhance the stability of the clusters structure while reducing the number of clusters.Clustering mechanism is introduced in our proposed routing protocol CLSR (Cluster-based Link StateRouting) in order to reduce the control overhead. The main objective of CLSR is to take profit of the stablestructure of clusters to enhance the network scalability.We propose also a second proactive link-state protocolwhich is based on hierarchical clustering. This protocol makes use of hierarchical clustering to more reducethe routing overhead.

Wireless communication systems are increasingly deployed by family, businesses, government and SOHO users because of the freedom wireless communications afford, simplicity of installation and ease of use. Along with its rapid development, the security problem in wireless communication network has attracted more and more attention. It has been estimated that the IEEE 80.211 standard is susceptible to attacks both on data content and user authentication, such as eavesdropping, spoofing and Denial of Service. These attacks are due to the standard's inherent flaws and space signal sharing caused by the omni-directional antenna it usually uses. In recent years, few studies have been undertaken which examine the use of the smart directional antenna to mitigate the security risks in mobile wireless computing networks. One of the major reasons is the antenna size, as portability is a key requirement. Due to the dielectric-material embedding and FDTD optimal design technology, a smart antenna with controllable directionality can now achieve an overall volume reduction of 80%. This has promise for application in the wireless security realm. This thesis provides a conventional background in wireless computing networks and security theory. In addition, security level definition, program in Matlab™ and corresponding experimental results are provided. To show the effectiveness of improving security in WLAN with the use of a smart directional antenna, this thesis proposes a model for predicting electromagnetic environments using a directional transmission antenna based on the Finite Element method. To validate the numerical results, a new experimental method (using Network Stumbler software) to measure the signal strength in different locations is introduced. Results from experiments using the two methods are consistent. The latter method gives the users the possibility of using a laptop (with an appropriate wireless card, software and roguing around) to detect the real-time signal strength in different locations instead of using expensive measure apparatus. Such an advantage can be valuable for the efficient implementation of indoor wireless networks for security purposes. Finally, it contributes a security solution using DE-ESMB and DE-ESPAR smart antennas in WLAN. Through these simulated and experimental results, one can conclude that the security performance in WLAN can be greatly improved by using smart directional antenna. There are five chapters in this thesis: Chapter 1 introduces the wireless communication network. Information about architecture, topology and popular wireless standards is presented in this chapter. Chapter 2 investigates the security problem in IEEE 802.11 Standards. Recent improvements in security, and their limitations, are also included. This problem is investigated by performing laboratory experiments, including a real attack on 802.11 Standards and packet capture experiments using AiroPeek NX software. Chapter 3 describes the useful parameters of smart directional antennas, and then presents the security level definition in WLAN. Simple software in Matlab™ to determine the security level according to the beamwidth of the adopted antenna is also introduced. Chapter 4 is the important part of this thesis. Simulation results of signal strength in different locations using FEMLAB™ are presented, which are consistent with the follow-up experimental results carried out in a typical office area. This chapter also describes the final security solution using the newly-designed DE-ESMB and DE-ESPAR directional antennas. Chapter 5 is a summary of the thesis. It presents the conclusions and suggests area of future research for improving the security level using smart antennas in WLAN.

Wireless sensor networks (WSNs) have been used in many applications by deploying tiny and stationary sensors. In recent years, a lot of studies proposed to introduce mobility capability to sensor nodes in order to exploit the advantages of mobility, particularly to restore connectivity in disjoint WSNs. While the studies demonstrated various capabilities of the proposed connectivity algorithms via simulation, real node and testbed implementations were mostly lacking due to unavailability of proper mobile nodes. Since this may hinder the direct applicability of the algorithms in realistic settings, testbeds which can be constructed with low-cost and commercial-off-the-shelf (COTS) hardware are required for realistic evaluations of the connectivity restoration algorithms. In this thesis, we design a low-cost mobile sensor node called iRobotSense, by integrating iRobot Create platform with IRIS sensor. Then, a mobile sensor network (MSN) testbed of iRobotSense nodes is used to implement and evaluate a widely used connectivity restoration algorithms, namely PADRA. Furthermore, all of the previous works exploiting mobility of the nodes to achieve recovery in a partitioned network have assumed reachability of the nodes to the selected destinations via a direct path movement. However, in real-world applications, such assumption makes the schemes impractical in case of encountering obstacles or intolerable terrains. Besides, even if direct path movement is successful, optimal energy efficiency cannot be attained by neglecting the elevation or friction of the terrain. Thus, in the recovery efforts, terrain type, elevation as well as the obstacles should be taken into account. In this thesis, we re-design an existing connectivity restoration approach in disjoint MSNs to fit these requirements and evaluate the performance issues when realistic terrains are assumed. Rather than following a direct path, movement trajectory is determined based on a path planning algorithm which considers the risk and elevation of terrain sections to be visited while avoiding obstacles and highly elevated terrain sections.