Recently, wireless sensor networks have become one of the most exciting areas for research and development. However, sensor nodes are battery operated, thus the sensor's ability to perform its assigned tasks is limited by its battery capacity; therefore, energy efficiency is considered to be a key issue in designing WSN applications. Clustering has emerged as a useful mechanism for trade-off between certain design goal conflicts; the network life time, and the amount of data obtained. However, different sources of energy waste still exist. Furthermore, in such dynamic environments, different data rate requirements emerge due to the current network status, thus adapting a response to the changing network is essential, rather than following the same principle during the network's lifespan. This thesis presents dynamic techniques to adapt to network changes, through which the limited critical energy source can be wisely managed so that the WSN application can achieve its intended design goals. Two approaches have been taken to decreasing the energy use. The first approach is to develop two dynamic round time controllers, called the minimum round time controller MIN-RC and the variable round time controller VAR-RC, whereas the second approach improves intra-cluster communication using a Co-Cluster head; both approaches show better energy utilisation compared to traditional protocols. A third approach has been to develop a general hybrid protocol H-RC that can adapt different applications requirements; it can also tolerate different data rate requirements for the same application during the system's lifetime.

Approved for public release, distribution is unlimited / This thesis presents a simulation and performance evaluation analysis of the various routing protocols that have been proposed for the Mobile Ad Hoc Network (MANET) environment using the Network Simulator-2 (NS-2) tool. Many routing protocols have been proposed by the academic communities for possible practical implementation of a MANET in military, governmental and commercial environments. Four (4) such routing protocols were chosen for analysis and evaluation: Ad Hoc On-demand Distance Vector routing (AODV), Dynamic Source Routing (DSR), Destination-Sequenced Distance Vector routing (DSDV) and Optimized Link State Routing (OLSR). NS-2 is developed and maintained by the University of Southern California's Information Sciences Institute (ISI). Leveraging on NS-2's simulation capabilities, the key performance indicators of the routing protocols were analyzed such as data network throughput, routing overhead generation, data delivery delay as well as energy efficiency or optimization. The last metric is explored, especially due to its relevance to the mobile environment. Energy is a scare commodity in a mobile ad hoc environment. Any routing software that attempts to minimize energy usage will prolong the livelihood of the devices used in the battlefield. Three important mobility models are considered, namely, Random Waypoint, Manhattan Grid, and Reference Point Group Mobility. The application of these three models will enhance the realism of simulation to actual real life mobility in an urban or military setup scenario. The performance of the routing protocols in varied node density, mobility speed as well as loading conditions have been studied. The results of the simulation will provide invaluable insights to the performance of the selected routing protocols. This can serve as a deciding factor for the U.S. Department of Defense (DoD) in their selection of the most suitable routing protocols tailored to their specific needs. / Civilian, Defence Science Technology Agency, Singapore

Cognitive radio technology that enables dynamic spectrum access has been a promising solution for the spectrum scarcity problem. Cognitive radio networks enable the communication on both licensed and unlicensed channels, having the potential to better solve the interference and collision issues. Channel assignment is of great importance in cognitive radio networks. When operating on licensed channels, the objective is to exploit spectrum holes through cognitive communication, giving priority to the primary users. In this dissertation, we focus on the development of efficient channel assignment algorithms and protocols to improve network performance for cognitive radio wireless networks. The first contribution is on channel assignment for cognitive radio wireless sensor networks aiming to provide robust topology control, as well as to increase network throughput and data delivery rate. The approach is then extended to specific cognitive radio network applications achieving improved performances. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

In this thesis, focusing on the quality of service (QoS) improvement using per-packet power control algorithm in Ad Hoc Cognitive Packet Networks (AHCPN). A power control mechanism creates as a network-assisted function of ad hoc cognitive packet-based routing and aims at reducing both energy consumption in nodes and QoS requirements. The suggested models facilitate transmission power adjustments while also taking into account the effects on network performance. The thesis concentrate on three main contributions. Firstly, a power control algorithm, namely the adaptive Distributed Power management algorithm (DISPOW) was adopted. Performance of DISPOW was compared to existing mechanisms and the results showed 27, 13, 9, and 40 percent improvements in terms of Delay, Throughput, Packet Loss, and Energy Consumption respectively. Secondly, the DISPOW algorithm was enhanced, namely a Link Expiration Time Aware Distributed Power management algorithm (LETPOW). This approach periodically checks connectivity, transmission power, interference level, routing overhead and Node Mobility in AHCPN. The results show that LETPOW algorithm improves the performance of system. Results show further improvement from DISPOW by 30,25,30,42 percent in terms of delay, packet loss ratio , path lengths and energy consumption respectively. Finally,Hybrid Power Control Algorithm (HLPCA) has presented is a combination of Link Expiration Time Aware Distributed Power management algorithm (LETPOW) and Load Power Control Algorithm (LOADPOW); deal with cross-layer power control applied for transmitting information across the various intermediate layers. LOADPOW emphasis on the concept of transmission Power, Received Signal Strength Indication (RSSI), and the suitable distance between the receiver and the sender. The proposed algorithm outperforms DISPOW and LETPOW by 31,15,35,34,44 percent in terms of Delay, Throughput, Packet Loss,path length and Energy Consumption respectively. From this work, it can be concluded that optimized power control algorithm applied to Ad-hoc cognitive packet network results in significant improvement in terms of energy consumption and QoS.

Les protocoles de routage dans les réseaux peuvent être amenés à changer pour de nombreuses raisons : la détection d'un événement particulier, un changement de topologie planifié ou non, la mobilité des nœuds, l'obsolescence de version, etc. Ces changements ne pouvant être simultanément détectés ou pris en compte par tous les nœuds du réseau, il est nécessaire de considérer le cas où certains nœuds utilisent le protocole de routage initial, tandis que d'autres ont migré vers le nouveau protocole de routage. Les travaux de cette thèse portent sur le problème de boucles de routage susceptibles d'apparaître dans ce contexte, et qui dégradent considérablement les performances du réseau. Nous proposons des solutions d'ordonnancement des nœuds, dans le but de contrôler la migration afin d'éviter ces boucles. Premièrement, nous considérons le contexte des réseaux statiques et des protocoles centralisés avec pour cas particulier le changement de métriques dans le réseau. Nous proposons deux solutions d'évitement des boucles centralisées : SCH-m (amélioration mineure d'un protocole existant), et ACH (nouvelle contribution), basées sur l'identification des boucles de routage dans les composantes connexes que contient l'union des deux protocoles de routage. Nous accélérons la migration du réseau par une opération de fusion étape par étape des différentes transitions produites. Deuxièmement, nous évoluons vers les protocoles distribués en conservant le contexte statique du réseau, et considérons le cas particulier du retrait ou de la panne d'un nœud. Nous proposons également deux solutions : RTH-d (amélioration mineure d'un protocole existant) et DLF (nouvelle contribution traitant les boucles de taille 2) basées sur un échange de messages entre les nœuds tant pour la détection de la panne que pour la notification de la migration. Troisièmement, nous considérons le contexte de mobilité des nœuds, et étudions les performances de DLF-k (version améliorée de DLF qui prend en compte les boucles de taille inférieures ou égales à k, avec k >= 2) sur deux types d'applications : les applications avec un unique nœud mobile qui est la destination, et les applications avec un groupe de nœuds mobiles. / Routing protocols in networks may change for many reasons: detection of a particular event, planned or unplanned change of topology, mobility of nodes, version obsolescence, etc. As these changes can not be simultaneously detected or taken into account by all nodes of the network, it is necessary to consider the case where some nodes use the initial routing protocol, while others have migrated to the new routing protocol. The work of this thesis deals with the problem of routing loops that may appear in this context, and which considerably degrade the performance of the network. We propose node scheduling solutions to control migration to avoid these loops. First, we consider the context of static networks and centralized protocols with the particular case of changing metrics. We propose two centralized avoidance solutions: SCH-m (minor improvement of an existing heuristic), and ACH (new contribution), based on the identification of the routing loops in the strongly connected components contained in the union of the two routing protocols. We accelerate the migration of the network by a step-by-step merge operation of the different transitions produced. Second, we evolve towards the distributed protocols while preserving the static context of the network, and consider the particular case of the withdrawal or breakdown of a node. We also propose two solutions: RTH-d (minor improvement of an existing heuristic) and DLF (new contribution for loops of size 2) based on message exchange of nodes for both failure detection and for migration notification. Thirdly, we consider the context of nodes mobility, and study the performance of DLF- k (improved version of DLF which takes into account loops of size less than or equal to k, with k >= 2) on two types of applications: applications with a single mobile node that is the destination, and applications with a group of mobile nodes.

The Internet traffic is constantly increasing following the emergence of new network applications like social networks, peer-to-peer, IP phone or IP television. In addition, these new applications request better path availability and path quality. Indeed the efficiency of these applications is strongly related to the quality of the underlying network. In that context network operators make use of traffic engineering techniques in order to improve the quality of the routes inside their network, but also to reduce the network cost of increased traffic handling with a better utilization of existing resources. This PhD thesis covers several topics of Traffic Engineering and Fast Restoration in IP/MPLS networks. Our first contribution is related to the definition of a well-engineered network. In the literature mathematical formulation of Traffic Engineering (TE) requirements are very diverse. We have thus performed a comparative study of many objective functions, in order to differentiate them and choose in a rational way the one that best reflects Traffic Engineering goals. We have also designed a method approaching optimal TE, whereby we divide the traffic matrix in N sub-matrices and route them independently, based on the derivatives of the objective function. The second topic addressed in this work concerns link weight optimizers (LWOs). Link weight optimization is the traffic engineering {it "standard"} technique in networks running link state routing protocols (which are widely used in transit networks). These link weight optimizers suffer from several limitations due to the BGP (Border Gateway Protocol) Hot-Potato rule, which is basically not considered by such optimizers. Therefore we have proposed a BGP-aware link weight optimization method that takes problematic Hot-Potato effects into account, and even turns them into an advantage. We have also studied how LWOs behave in big networks which have to use BGP route reflectors. Finally we have studied whether forwarding loops can appear or not when traffic is split among multiple equivalent egress routers, an optional BGP feature that we did use in our Hot-Potato aware LWO. Our last contribution concerns network resilience. We have proposed a solution for a rapid recovery from a link or node failure in an MPLS network. Our solution allows a decentralized deployment combined with a minimal bandwidth usage while requiring only reduced amount of information to flood in the network. This method is the first that makes possible a decentralized deployment combined with an optimal resource consumption. To easily simulate and test the methods proposed in this work, we have also contributed to the development of TOTEM - a TOolbox for Traffic Engineering Methods.

An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any fixed network infrastructure or centralized administration. Due to the limitations in the wireless environment, it may be necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination. In order to enable communication within the network, a routing protocol is needed to discover routes between nodes. The primary goal of ad hoc network routing protocols is to establish routes between node pairs so that messages may be delivered reliably and in a timely manner. The basic access method in IEEE 802.11 ad hoc networks is the Distributed Coordination Function (DCF), which provides a fair medium access. Enhanced Distributed Coordination Function (EDCF) has been developed to provide service differentiation among different traffic flows. In this thesis, we investigate the performance of the EDCF with routing protocols / Direct Sequenced Distance Vector (DSDV) and Dynamic Source Routing (DSR) by simulations.

Delay-tolerant networks (DTNs) have the potential to connect devices and areas of the world that are under-served by traditional networks. The idea is that an end-to-end connection may never be present. To make communication possible, intermediate nodes take custody of the data being transferred and forward it as the opportunity arises. Both links and nodes may be inherently unreliable and disconnections may be long-lived. A critical challenge for DTNs is determining routes through the network without ever having an end-to-end connection. <br /><br /> This thesis presents a practical routing protocol that uses only observed information about the network. Previous approaches either require complete future knowledge about the connection schedules, or use many copies of each message. Instead, our protocol uses a metric that estimates the average waiting time for each potential next hop. This learned topology information is distributed using a link-state routing protocol, where the link-state packets are flooded using epidemic routing. The routing is recomputed each time connections are established, allowing messages to take advantage of unpredictable contacts. Messages are exchanged if the topology suggests that a connected node is "closer" than the current node. <br /><br /> Simulation results are presented, showing that the protocol provides performance similar to that of schemes that have global knowledge of the network topology, yet without requiring that knowledge. Further, it requires a significantly less resources than the epidemic alternative, suggesting that this approach scales better with the number of messages in the network.

Delay-tolerant networks (DTNs) have the potential to connect devices and areas of the world that are under-served by traditional networks. The idea is that an end-to-end connection may never be present. To make communication possible, intermediate nodes take custody of the data being transferred and forward it as the opportunity arises. Both links and nodes may be inherently unreliable and disconnections may be long-lived. A critical challenge for DTNs is determining routes through the network without ever having an end-to-end connection. <br /><br /> This thesis presents a practical routing protocol that uses only observed information about the network. Previous approaches either require complete future knowledge about the connection schedules, or use many copies of each message. Instead, our protocol uses a metric that estimates the average waiting time for each potential next hop. This learned topology information is distributed using a link-state routing protocol, where the link-state packets are flooded using epidemic routing. The routing is recomputed each time connections are established, allowing messages to take advantage of unpredictable contacts. Messages are exchanged if the topology suggests that a connected node is "closer" than the current node. <br /><br /> Simulation results are presented, showing that the protocol provides performance similar to that of schemes that have global knowledge of the network topology, yet without requiring that knowledge. Further, it requires a significantly less resources than the epidemic alternative, suggesting that this approach scales better with the number of messages in the network.

Satellite systems have the advantage of global coverage and offer a solution for providing broadband access to end users. Local terrestrial networks and terminals can be connected to the rest of the world over Low Earth Orbit (LEO) satellite networks simply by installing small satellite interfaces. With these properties, satellite systems play a crucial role in the global Internet to support real-time and non-real-time applications. Routing in satellite networks, and the integration of satellite networks and the terrestrial Internet are the key issues to support these services. Furthermore, the developments in space technologies enable the realization of deep-space missions such as Mars exploration. The Interplanetary Internet is envisioned to provide communication services for scientific data delivery and navigation services for the explorer spacecrafts and orbiters of future deep-space missions. The unique characteristics posed by deep-space communications call for different research approaches from those in terrestrial networks. The objective of this research is to develop advanced architectures and efficient routing protocols for satellite and space networks to support applications with different traffic types and heterogeneous quality-of-service (QoS) requirements. Specifically, a new QoS-based routing algorithm (QRA) is proposed as a connection-oriented routing scheme to support real-time multimedia applications in satellite networks. Next, the satellite grouping and routing protocol (SGRP) is presented as a unicast routing protocol in a two-layer satellite IP network architecture. The border gateway protocol - satellite version (BGP-S) is then proposed as a unified routing protocol to accomplish the integration of the terrestrial and satellite IP networks at the network layer. Finally, a new routing framework, called the space backbone routing (SBR), is introduced for routing through different autonomous regions in the Interplanetary Internet. SBR provides a self-contained and scalable solution to support different traffic types through the Interplanetary Internet.