Design and evaluation of crash tolerant protocols for mobile ad-hoc networks

Mobile ad-hoc networks are wireless networks operating without any form of supporting infrastructure such as base-stations, and thus require the participating nodes to co-operate by forwarding each other's messages. Ad-hoc networks can be deployed when installing network infrastructure is considered too expensive, too cumbersome or simply too slow, for example in domains such as battlefields, search-and-rescue or space exploration. Tolerating node crashes and transient network partitions is likely to be important in such domains. However, developing applications which do so is a difficult task, a task which can be made easier by the availability of fault-tolerant protocols and middleware. This dissertation studies two core fault-tolerant primitives, reliable dissemination and consensus, and presents two families of protocols which implement these primitives in a wide range of mobile ad-hoc networks. The performance of the protocols is studied through simulation indicating that they are able to provide their guarantees in a bandwidth efficient manner. This is achieved by taking advantage of the broadcast nature and variable message delivery latencies inherent in ad-hoc networks. To illustrate the usefulness of these two primitives, a design for a distributed, fault-tolerant tuple space suitable to implement on mobile ad-hoc networks is presented. This design, if implemented, would provide a simple, yet powerful abstraction to the developer of fault-tolerant applications in mobile ad-hoc networks.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Spatiotemporal Multicast and Partitionable Group Membership Service

The recent advent of wireless mobile ad hoc networks and sensor networks creates many opportunities and challenges. This thesis explores some of them. In light of new application requirements in such environments, it proposes a new multicast paradigm called spatiotemporal multicast for supporting ad hoc network applications which require both spatial and temporal coordination. With a focus on a special case of spatiotemporal multicast, called mobicast, this work proposes several novel protocols and analyzes their performances. This dissertation also investigates implications of mobility on the classical group membership problem in distributed computing, proposes a new specification for a partitionable group membership service catering to applications on wireless mobile ad hoc networks, and provides a mobility-aware algorithm and middleware for this service. The results of this work bring new insights into the design and analysis of spatiotemporal communication protocols and fault-tolerant computing in wireless mobile ad hoc networks

ETS (Efficient, Transparent, and Secured) Self-healing Service for Pervasive Computing Applications

To ensure smooth functioning of numerous handheld devices anywhere anytime, the importance of self-healing mechanism cannot be overlooked. Incorporation of efficient fault detection and recovery in device itself is the quest for long but there is no existing self-healing scheme for devices running in pervasive computing environments that can be claimed as the ultimate solution. Moreover, the highest degree of transparency, security and privacy attainability should also be maintained. ETS Self-healing service, an integral part of our developing middleware named MARKS (Middleware Adaptability for Resource discovery, Knowledge usability, and Self-healing), holds promise for offering all of those functionalities

Optimal fault-tolerant placement of relay nodes in a mission critical wireless network

The operations of many critical infrastructures (e.g., airports) heavily depend on proper functioning of the radio communication network supporting operations. As a result, such a communication network is indeed a mission-critical communication network that needs adequate protection from external electromagnetic interferences. This is usually done through radiogoniometers. Basically, by using at least three suitably deployed radiogoniometers and a gateway gathering information from them, sources of electromagnetic emissions that are not supposed to be present in the monitored area can be localised. Typically, relay nodes are used to connect radiogoniometers to the gateway. As a result, some degree of fault-tolerance for the network of relay nodes is essential in order to offer a reliable monitoring. On the other hand, deployment of relay nodes is typically quite expensive. As a result, we have two conflicting requirements: minimise costs while guaranteeing a given fault-tolerance. In this paper address the problem of computing a deployment for relay nodes that minimises the relay node network cost while at the same time guaranteeing proper working of the network even when some of the relay nodes (up to a given maximum number) become faulty (fault-tolerance). We show that the above problem can be formulated as a Mixed Integer Linear Programming (MILP) as well as a Pseudo-Boolean Satisfiability (PB-SAT) optimisation problem and present experimental results com- paring the two approaches on realistic scenarios