A Mobile Ad Hoc Network (MANET) is a shared wireless network without any infrastructure, consisting of mobile nodes connected by wireless links. The nodes are free to move and organize themselves arbitrarily. The nodes in the network are therefore depending on each other in order to communicate over multiple hops. Due to the physical characteristics of wireless networks, the channel is time-varying, which makes it hard to both predict and sustain a bit rate level. The nodes’ mobility causes topology changes, and further load and capacity variations. Traditional usage areas are battlefield and disaster areas, while new areas like extended network coverage and gaming are emerging. Quality of Service (QoS) is needed in every network in order to differentiate traffic with different performance requirements, e.g. voice and e-mail applications. Providing QoS in wireless environments with varying conditions is complex, and hard guarantees can not be given. Consequently, the aim is to give differentiated treatment to traffic with different performance requirements. In addition, we can not study the MANET without considering fixed networks. Communication with fixed networks is important, for example by accessing the Internet. In this thesis the Differentiated Services (DiffServ) architecture is applied and adapted to MANETs. Using the same QoS architecture will ease the transition between the wireless and wired domain. But the special characteristics of wireless networks require modifications to the original DiffServ architecture. In investigations there was found restrictions on the number of classes to use, and this number was dependent on the type of traffic in the network. A QoS architecture based on the DiffServ framework is proposed, with an admission control based on the concept of shadow classes, and Explicit Congestion Notification (ECN) to avoid congestion. New flows are tested in a shadow class before getting admission to the network and its designated class. The shadow class has the same scheduling properties as the designated class, but is differentiated by a higher drop probability in the buffers. Both the admission control and ECN are thus build on the same principle by controlling the load from probabilistic functions in the buffers, and are studied to find their individual and combined effects. In wireless environments the probability of a packet loss increases with the number of hops, which gives services an unpredictable performance for users. A predictable service, independent of number of hops, is provided by scheduling based on the path information; the packets are differentiated based on the number of hops made or left to make, increasing the predictability at the cost of performance.

In crucial times, such as natural disasters like Earthquakes, Floods, military attack, rescue and emergency operations, etc., it is not possible to maintain an infrastructure. In these situations, wireless Mobile Ad-Hoc networks can be an alternative to wired networks. In our thesis, due to the importance of MANET (Mobile Ad-hoc Network) applications, we do research on MANET and its subtype IMANET (Internet based Mobile Ad-hoc Network). In MANETs, finding an optimum path among nodes is not a simple issue due to the random mobility of nodes and topology changes frequently. Simple routing algorithms like Shortest Path, Dijksta‟s and Link State fail to find route in such dynamic scenarios. A number of ad-hoc protocols (Proactive, Reactive, Hybrid and Position based) have been developed for MANETs. In this thesis, we have designed an IMANET in OPNET 14.5 and tested the performance of three different routing protocols namely OLSR (Optimum Link State Routing), TORA (Temporarily Ordered Routing Algorithm) and AODV (Ad-hoc On-demand Distance Vector) in different scenarios by varying the number of nodes and the size of the area. The experimental results demonstrate that among the three protocols, none of the routing protocol can ensure good quality HTTP and voice communication in all our considered scenarios.

A packet will be dropped when it arrives at a congested node in a routing path. The authors of [22] proposed the CRP protocol that can alleviate the congestion problem by splitting the traffic to the bypass nodes. In this thesis, we propose a new routing protocol, called MIMO-assisted congestion-adaptive routing protocol (MCRP for short), for multi-hop mobile ad hoc networks (MANETs for short). In MCRP, nodes periodically record the information of their rate-link/range-link neighbors. MCRP alleviates the congestion problem by dynamically adjusting the MIMO antenna mode and splitting the traffic to the downstream range-link neighbors. In addition, MCRP can quickly reestablish the routing path when it is broken due to node failure or mobility. Simulation results show that MCRP outperforms the existing protocols in terms of packet delivery ratio and end-to-end throughput.

Mobile ad hoc network is an architecture which do not exist any infrastructure or centralized administration. There are many routing protocols have been proposed so far, such as AODV, DSR and CGSR. These protocols were classified as reactive in which routes are established only when required. Due to the movement of mobile nodes, network topology changes frequently, and the routing path could be broken easily. This phenomenon will cause higher routing overhead and delivery latency. In conventional routing protocols, the source-destination pair only establishes a single path for data transmission. These routing scheme, however, suffer from the drawback of node movement. When route broken, the source node must reconstruct another new path. This paper presents an adaptive routing protocol named Adaptive Route Selection Scheme of Multiple Paths for Mobile Ad Hoc Network (ARSMA). The aim of the work is to improve the delivery ratio. In the route request phase, source nodes will discovery two routes to the destination node, one for primary path, and the other for the backup path. During the discovery procedure, each node will estimate the link expire time through the movement speed and direction of the precursor node. When a link breakage is about to occur, source node will try to switch the transmission to the backup route.The simulation result shows that ARSMA is able to achieve a remarkable improvement in delivery ratio and end-to-end dealy.

Mobile ad hoc networks are without centralized infrastructure, and suitable for the region that difficultly builds the basic network framework, for example, desert and ocean. The bandwidth in mobile ad hoc networks is likely to remain a scarce resource. A call request of a connection in a wireless network is blocked if there exits no bandwidth route. This blocking does not mean that the total system bandwidth capacity is less than the request, but that there is no path in which each link has enough residual unused bandwidth to satisfy the requirement. Like the routing in a datagram network, if packets of a virtual circuit can stream across multiple paths, we can select multiple bandwidth routes such that the total bandwidth can meet the requirement of a source-destination pair. Therefore, even though there is no feasible single path for a bandwidth-constrained connection, we may still have a chance to accept this one if we can find multiple bandwidth routes to meet the bandwidth constraint. In this dissertation, we propose a bandwidth-constrained routing algorithm to aggregate the bandwidth of multiple wireless links by splitting a data flow across multiple paths at the network layer. That is, it allows the packet flow of a source-destination pair to be delivered over multiple bandwidth routes with enough overall resources to satisfy a certain bandwidth requirement. Our algorithm considers not only the QoS requirement, but also the cost optimality of the routing paths to improve the overall network performance. Extensive simulations show that high call admission ratio and resource utilization are achieved with modest routing overheads. This algorithm can also tolerate the node moving, joining, and leaving. We also propose an algorithm, named efficient utilization polling (EUP), to support asynchronous data traffic at MAC layer by using the characteristics of Bluetooth technology. The algorithm uses a single bit in the payload header to carry the knowledge of queues in slaves for dynamically adapting the polling intervals for achieving the goals of high channel utilization and power conserving. In addition, we propose a differentiation mechanism, named shift-polling window (SPW). Based on EUP, the SPW differentiates the throughput from various classes, and still keeps the link utilization high and almost the same as that of the best-effort services. Extensive simulations are experimented on the behavior of the EUP and SPW by tuning the related parameters, such as polling interval, buffer size, and queue threshold level, etc., in order to verify the expectation of these methods.

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Peer-to-peer (P2P) applications are enormously popular on the Internet. Their uses vary from file sharing to Voice-over-IP to gaming and more. Increasingly, users are moving toward wireless networked devices and wish to continue using P2P applications in these new environments. A mobile ad hoc network (MANET) is an infrastructureless network which allows users to dynamically form a mobile, wireless network. Though P2P and MANETs share some similarities, such as self-organization, dynamism, and resilience to failure, it is necessary to create new P2P algorithms that take advantage of the realities of MANETs. These algorithms must account for the numerous challenges found in these networks, including node mobility, resource constrained nodes, and the necessity of fully distributed algorithms. In this thesis, we propose a framework for mobile P2P computing in MANETs (P2P-MANETs). Our proposal includes the following components. First, nodes must be able to locate and join the P2P overlay. We therefore propose a fully distributed bootstrapping algorithm in which nodes multicast join requests and cache responses. Next, the overlay peers must form a topology of connections between themselves. We propose a fully distributed topology control heuristic which supports the dynamic nature of the P2P-MANET. It is important that peers contribute to the network by sharing their resources and forwarding traffic for others. We therefore propose a dynamically priced incentive scheme which rewards users for contributing to the network. We also propose a path selection algorithm to allow peers to select how many parts of a file to download from which servers and which paths to satisfy the user's preference for download time and cost. Finally, we propose a content distribution system that allows users to download large files through the use of network coding and multicasting. Each of these components is the first proposed for its respective place in a P2P-MANET architecture. Simulation results show that each of the proposed components achieves the goals set out for it and outperforms the comparison schemes. The results also show that the overlay topology and path selection heuristics provide good approximations compared to the optimal solutions. / Thesis (Ph.D, Computing) -- Queen's University, 2010-01-27 12:16:25.352

In this dissertation, we focus on the problem of self-management in distributed systems. In this context, we propose a new methodology for reactive self-management based on multiple criteria decision analysis (MCDA). The general structure of the proposed methodology is extracted from the commonalities of the former well-established approaches that are applied in other problem domains. The main novelty of this work, however, lies in the usage of MCDA during the reaction processes in the context of the two problems that the proposed methodology is applied to. In order to provide a detailed analysis and assessment of this new approach, we have used the proposed methodology to design distributed autonomous agents that can provide self-management in two outstanding problems. These two problems also represent the two distinct ways in which the methodology can be applied to self-management problems. These two cases are: 1) independent self management, and 2) coordinated self-management. In the simulation case study regarding independent self-management, the methodology is used to design and implement a distributed resource consolidation manager for clouds, called IMPROMPTU. In IMPROMPTU, each autonomous agent is attached to a unique physical machine in the cloud, where it manages resource consolidation independently from the rest of the autonomous agents. On the other hand, the simulation case study regarding coordinated self-management focuses on the problem of adaptive routing in mobile ad hoc networks (MANET). The resulting system carries out adaptation through autonomous agents that are attached to each MANET node in a coordinated manner. In this context, each autonomous node agent expresses its opinion in the form of a decision regarding which routing algorithm should be used given the perceived conditions. The opinions are aggregated through coordination in order to produce a final decision that is to be shared by every node in the MANET. Although MCDA has been previously considered within the context of artificial intelligence---particularly with respect to algorithms and frameworks that represent different requirements for MCDA problems, to the best of our knowledge, this dissertation outlines a work where MCDA is applied for the first time in the domain of these two problems that are represented as simulation case studies. / Graduate

In this dissertation we present deterministic algorithms for reliable and efficient communication in ad hoc networks. In the first part of this dissertation we give a specification for a reliable neighbor discovery layer for mobile ad hoc networks. We present two different algorithms that implement this layer with varying progress guarantees. In the second part of this dissertation we give an algorithm which allows nodes in a mobile wireless ad hoc network to communicate reliably and at the same time maintain local neighborhood information. In the last part of this dissertation we look at the distributed trigger counting problem in the wireless ad hoc network setting. We present a deterministic algorithm for this problem which is communication efficient in terms of the the maximum number of messages received by any processor in the system.

Opportunistic Routing (OR) is an effective and enhanced routing scheme for wireless multihop environment. OR is an approach that selects a certain number of best forwarders (candidates) at each hop by taking the advantage of the broadcast nature of the wireless medium to reach the destination. When a set of candidates receive the packet, they coordinate with each other to figure out which one has to forward the packet toward the destination. Most of the research in this area has been done in mesh networks where nodes do not have mobility. In this survey, we propose a new OR protocol for mobile ad hoc scenarios called as Enhanced Mobility-based Opportunistic Routing (EMOR) protocol. To deal with the node mobility, we have proposed a new metric which considers the following: geographical position of the candidates; the link delivery probability to reach them; the number of neighboring nodes of candidates; and the predicted position of nodes using the motion vector of the nodes. We have compared EMOR with five other well-known routing protocols in terms of delivery ratio, end-to-end delay, and expected number of transmissions from source to the destination. Our simulation results show that proposed protocol improves delivery ratio and number of expected transmission in terms of different type of mobility models.