Collaborative Approach for Improving the Scheduling and Providing Advanced Security in Wireless Sensor Network

Recent advances in Wireless Sensor Networks (WSN) have focused towards Geographic forwarding mechanism. It is a promising routing scheme in wireless sensor networks, in which the forwarding decision is determined purely based on the location of each node. Such type of Routing in Geographic domain is also useful for large multi-hop wireless networks where the nodes are not reliable and network topology is frequently changing. This routing requires propagation of single hop topology information that is the best neighbor, to make correct forwarding decisions. The research of Geographic routing has now moved towards duty cycled wireless sensor networks (WSNs). In such type of network, sensors are sleep scheduled which helps in reduction of energy consumption. It works by dynamically putting the nodes to sleep when not in use and reactivate it, when required, by using some sleep scheduling algorithms. Geographic routing is usually based on distance which is considered as its main parameter. This routing uses geographic routing oriented sleep scheduling (GSS) algorithm & geographic-distance-based connected-k neighborhood (GCKN) algorithm. The existing research was done to find out the shortest path from source to destination in Duty-Cycled Mobile sensor networks along with geographic routing, using distance as a parameter. But there may be the case when shortest path is available and the nodes are heavily loaded. Therefore, load balancing also proves to be equally important factor. Hence, this research work proposes the system that will calculate the best optimal path from source node to destination by taking into consideration the load on each node and delay incurred by each node in Duty-Cycled Mobile sensor networks along with geographic routing. The experimental results and performance analysis shows that the newly proposed approach achieves the best results in comparison with the existing system

Effective link quality estimation as a means to improved end-to-end packet delivery in high traffic mobile ad hoc networks

Accurate link quality estimation is a fundamental building block in quality aware multi hop routing. In an inherently lossy, unreliable and dynamic medium such as wireless, the task of accurate estimation becomes very challenging. Over the years ETX has been widely used as a reliable link quality estimation metric. However, more recently it has been established that under heavy traffic loads ETX performance gets significantly worse. We examine the ETX metric's behavior in detail with respect to the MAC layer and UDP data; and identify the causes of its unreliability. Motivated by the observations made in our analysis, we present the design and implementation of our link quality measurement metric xDDR – a variation of ETX. This article extends xDDR to support network mobility. Our experiments show that xDDR substantially outperforms minimum hop count, ETX and HETX in terms of end-to-end packet delivery ratio in static as well as mobile scenarios.</p

Application-Driven Wireless Sensor Networks

The growth of wireless networks has resulted in part from requirements for connecting people and advances in radio technologies. Recently there has been an increasing trend towards enabling the Internet-of-Things (IoT). Thousands of tiny devices interacting with their environments are being inter-networked and made accessible through the Internet. For that purpose, several communications protocols have been defined making use of the IEEE 802.15.4 Physical and MAC layers. The 6LoWPAN Network Layer adaptation protocol is an example which bridges the gap between low power devices and the IP world. Since its release, the design of routing protocols became increasingly important and the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) emerged as the IETF proposed standard protocol for IPv6-based multi-hop Wireless Sensor Networks (WSN). This thesis considers that the sensor nodes form a large IPv6 network making use of above technologies and protocols, and that the sensor nodes are enabled to run one or more applications. It is also assumed that the applications and the sensor nodes to which they are associated, are not always active, alternating between active and inactive states. The thesis aims to design a new energy efficient communications solution for WSN by exploring the hypothesis that the network is aware of the traffic generated by the applications running in the sensor nodes. Therefore, the thesis provides two major contributions: 1) a cross-layer mechanism using application layer and network layer information to constrainRPL-defined routing trees (RPL-BMARQ); 2) an Application-Driven WSN node synchronization mechanism for RPL-BMARQ. RPL-BMARQ is designed as an extension to the RPLrouting protocol using information shared by the application and routing layers to construct Directed Acyclic Graphs (DAGs), allowing the nodes to select parents with respect to the applications they run. By jointly considering the neighbors of each node, the applications each node runs, and the forwarding capabilities of a node, we provide a communications solution which enables the data of every application and sensor node to be transferred, while keeping the overall energy consumed low by reducing the time the nodes are active and reducing the total number of multicast packets exchanged. Therefore, RPL-BMARQ helps reducing the network energy consumption since it restricts radio communication activities while maintaining throughput fairness and packet reception ratio high. The mechanism was evaluated using four scenarios with different network topologies and compared against "standard RPL". The results obtained show that the mechanism enables lower energy consumption since the nodes are more often put a sleep, reducing the total number of packets exchanged, while maintaining fairness and query success rates high. The Application-Driven WSN node synchronization mechanism for RPL-BMARQ was designed to maintain the sensor nodes synchronized according to the duty cycle of the applications they run. The mechanism jointly uses cross-layer information and the Exponentially Weighted Moving Average (EWMA) technique for calculating in run-time average network delays which are used to control the time the sensor nodes would sleep in the next cycle in order to wake up just before the next activity period starts. This mechanism enables all the sensor nodes to go asleep and to wake up in synchronism. The mechanism was theoretically evaluated and simulated, and the results obtained show that the synchronization mechanism works as previewed. The results also showed that, when designing WSN applications with this mechanism, the nodes not involved in communications are kept sleeping as much as possible, waking up when necessary and in synchronism. In order to confirm the validity of the mechanisms designed, we also tested them in real environments where the results were confirmed

An Investigation into Possible Attacks on HTML5 IndexedDB and their Prevention

This thesis presents an analysis of, and enhanced security model for IndexedDB, the persistent HTML5 browser-based data store. In versions of HTML prior to HTML5, web sites used cookies to track user preferences locally. Cookies are however limited both in file size and number, and must also be added to every HTTP request, which increases web traffic unnecessarily. Web functionality has however increased significantly since cookies were introduced by Netscape in 1994. Consequently, web developers require additional capabilities to keep up with the evolution of the World Wide Web and growth in eCommerce. The response to this requirement was the IndexedDB API, which became an official W3C recommendation in January 2015. The IndexedDB API includes an Object Store, indices, and cursors and so gives HTML5 - compliant browsers a transactional database capability. Furthermore, once downloaded, IndexedDB data stores do not require network connectivity. This permits mobile web- based applications to work without a data connection. Such IndexedDB data stores will be used to store customer data, they will inevitably become targets for attackers. This thesis firstly argues that the design of IndexedDB makes it unavoidably insecure. That is, every implementation is vulnerable to attacks such as Cross Site Scripting, and even data that has been deleted from databases may be stolen using appropriate software tools. This is demonstrated experimentally on both mobile and desktop browsers. IndexedDB is however capable of high performance even when compared to servers running optimized local databases. This is demonstrated through the development of a formal performance model. The performance predictions for IndexedDB were tested experimentally, and the results showed high conformance over a range of usage scenarios. This implies that IndexedDB is potentially a useful HTML5 API if the security issues can be addressed. In the final component of this thesis, we propose and implement enhancements that correct the security weaknesses identified in IndexedDB. The enhancements use multifactor authentication, and so are resistant to Cross Site Scripting attacks. This enhancement is then demonstrated experimentally, showing that HTML5 IndexedDB may be used securely both online and offline. This implies that secure, standards compliant browser based applications with persistent local data stores may both feasible and efficient

Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC