Search

Current Internet architecture is being challenged by the overwhelming multiplication of available content and the increasing requirements of the content delivery applications. Content Delivery Networks have been playing a catalytic role in content delivery solutions, replicating (caching) content at the edges of the network. In this paper, we have investigated the potential benefits offered by adaptability in overlay content replication, considering changing conditions such as the popularity and the size of the content objects and a system of collaborating content caches. Pursuing the understanding of the influence of these parameters we have designed and implemented a simulation framework, with enhanced visualization and parameterization capabilities, and performed a series of experiments, under varying conditions.

Summarization: The use of Wireless Sensor Networks (WSN) in a wide variety of application domains has been intensively pursued lately while Future Internet designers consider WSN as a network architecture paradigm that provides abundant real-life real-time information which can be exploited to enhance the user experience. The wealth of applications running on WSNs imposes different Quality of Service requirements on the underlying network with respect to delay, reliability and loss. At the same time, WSNs present intricacies such as limited energy, node and network resources. To meet the application’s requirements while respecting the characteristics and limitations of the WSN, appropriate routing metrics have to be adopted by the routing protocol. These metrics can be primary (e.g. expected transmission count) to capture a specific effect (e.g. link reliability) and achieve a specific goal (e.g. low number of retransmissions to economize resources) or composite (e.g. combining latency with remaining energy) to satisfy different applications needs and WSNs requirements (e.g. low latency and energy consumption at the same time). In this paper, (a) we specify primary routing metrics and ways to combine them into composite routing metrics, (b) we prove (based on the routing algebra formalism) that these metrics can be utilized in such a way that the routing protocol converges to optimal paths in a loop-free manner and (c) we apply the proposed approach to the RPL protocol specified by the ROLL group of IETF for such low power and lossy link networks to quantify the achieved performance through extensive computer simulations. Presented on: Wireless Networks

Wireless sensor networks are vulnerable to a wide set of security attacks, including those targeting the routing protocol functionality. The applicability of legacy security solutions is disputable (if not infeasible), due to severe restrictions in node and network resources. Although confidentiality, integrity and authentication measures assist in preventing specific types of attacks, they come at high cost and, in most cases, cannot shield against routing attacks. To face this problem, we propose a secure routing protocol which adopts the geographical routing principle to cope with the network dimensions, and relies on a distributed trust model for the detection and avoidance of malicious neighbours. A novel function which adaptively weights location, trust and energy information drives the routing decisions, allowing for shifting emphasis from security to path optimality. The proposed trust model relies on both direct and indirect observations to derive the trustworthiness of each neighboring node, while it is capable of defending against an increased set of routing attacks including attacks targeting the indirect trust management scheme. Extensive simulation results reveal the advantages of the proposed model.

Internet is the most important information exchange means nowadays and has become the core communication environment, not only for business relations, but also for social and human interaction. Yet, the immense success of Internet has created even higher hopes and expectations for new immersive and real-time applications and services. However, there are no guarantees that the current Internet will be able to support them. To face the new requirements coming from these new applications and services, several architectural approaches have been proposed. Evolutionary and clean-slate approaches, based on content-centric architectures, have been proposed for meeting new requirements regarding media. This paper highlights the main architectural functions and presents a revolutionary protocol stack and a holistic architectural approach that targets Future Media Internet (FMI). Among the architectural functions and the holistic approach, the paper presents solutions to overcome the current content delivery limitations, moving intelligence in the network and converting it into a content oriented/centric network, that goes well beyond current CDNs; supporting the functionalities for producing, publishing, caching, finding and consuming content; and a novel Future Media Internet protocol stack and network architecture.

A new soft decision maximum-likelihood decoding algorithm, which generates the minimum set of candidate codewords by efficiently applying the algebraic decoder is proposed. As a result, the decoding complexity is reduced without degradation of performance. The new algorithm is tested and verified by simulation results.

Bandwidth capabilities of next generation networks have turned interactive multimedia services to a cost effective reality, targeting not only large companies, but SMEs and individual users as well. An application with direct social impact is tele-teaching and in the broader sense distance learning. A large numbers of colleges, universities, and other higher education institutions already offer online courses to their local and remote students, via new methods of education. In this paper, combining the WWW, the H.323/MPEG-4 protocol family and the CORBA model, we specify an open system and network architecture towards the Virtual Classroom realisation. Over this architecture an educational process is described using formal Object Modelling Technique (OMT) rules, while educational services are provided as methods of distributed objects. In this way, a framework is proposed in order to allow educational institutes to publish content in an abstract object-oriented manner, so as to become widely available via the well-known WWW interface.

Residential networks are expected to open a huge market and introduce a bright, new era in telecommunications, by exponentially increasing the network usage, via broadband, added value services. Despite the business risks, investments made by the telecommunication industries clearly express the belief that the home networking market is about to take off. In this paper, a home network architecture for the provision of interactive multimedia services is considered and various access and indoor networking alternatives are presented. Then the focus is put on the Residential Gateway (RG), as a single point of networks convergence. Based on prototypes development, laboratory experiments and field trials throughout Europe and USA, a modular and a compact RG hardware architecture are described and compared, while the software architecture to support the RG functionality is described and the main building blocks are analyzed. Finally, a Web browser-based network management and control application that provides a visual metaphor of the RG is presented.

The majority of research and development efforts in the area of Wireless Sensor Networks (WSNs) focus on WSN systems that are dedicated for a specific application. However, this trend is currently being replaced by resource-rich WSN deployments that are expected to provide capabilities in excess of any application's requirements. In this regard, the concept of virtual sensor networking is an emerging approach that enables the decoupling of the physical sensor deployment from the applications running on top of it, allowing in this way the dynamic collaboration of a subset of sensor nodes and helping the proliferation of new services and applications beyond the scope of the original deployment. In this context, the article presents the architecture of a system for the realization of Virtual Sensor Networks (VSNs). The aim of the proposed architecture is to enable the realization of scalable, flexible, adaptive, energy-efficient, and trust-aware VSN platforms, focusing on the reduction of deployment complexity and management cost, and on advanced interoperability mechanisms. The efforts have been put towards specifying a service provisioning architecture and mechanisms for advanced sensor and middleware design.