Autonomic communications seek to improve the ability of network and services to cope with unpredicted change, including changes in topology, load, task, the physical and logical characteristics of the networks that can be accessed, and so forth. Broad-ranging autonomic solutions require designers to account for a range of end-to-end issues affecting programming models, network and contextual modeling and reasoning, decentralised algorithms, trust acquisition and maintenance---issues whose solutions may draw on approaches and results from a surprisingly broad range of disciplines. We survey the current state of autonomic communications research and identify significant emerging trends and techniques.

No abstract

In terms of scalability, cost and ease of deployment, the Peer-to-Peer (P2P) approach has emerged as a promising solution for video streaming applications. Its architecture enables end-hosts, called peers, to relay the video stream to each other. P2P systems are in fact networks of users who control peers. Thus, user behavior is crucial to the performance of these systems because it directly impacts the streaming flow. To understand user behavior, several measurement studies have been carried out over different video streaming systems. Each measurement analyzes a particular system focusing on specific metrics and presents insights. However, a single study based on a particular system and specific metrics is not sufficient to provide a complete model of user behavior considering all of its components and the impact of external factors on them. In this paper, we propose a comparison and a synthesis of these measurements. First of all, we review video streaming architectures, followed by a survey on the user behavior measurements in these architectures. Then, we gather insights revealed in these measurements and compare them for consensual and contrasting points. Finally, we extract components of user behavior, their external impacting factors and relationships among them. We also point out those aspects of user behavior which require further investigations.

SUMMARYIP networks, and particularly the Internet, were proposed to be a simple and robust support for homogeneous communications. This implies that only basic control mechanisms have to be performed by network elements. Communication management has to be performed by the terminals. However, the integration of new services and the increasing need for QoS require the network to be increasingly more fl exible and adaptive. New algorithms and protocols have been proposed by many research teams to address these issues, but these new algorithms tend to make network management and control more fl exible. Thus, manual confi guration of such fl exible and adaptive network architectures is very complex, if not impossible. Self-management is then a good opportunity to address this new complexity, and then to integrate more easily new services into the network. However, this self-management requires the equipment to carry much more knowledge and information than the actual control and management planes do. Global knowledge management schemes are therefore necessary to achieve this, including new policies for knowledge gathering, computing, sharing and providing. To address this particular need for knowledge management, several studies have proposed building a new plane, called the 'Knowledge Plane' (KP). This paper studies different propositions for this KP, and presents an original vision of what this KP should be. Our vision of the KP relies on the paradigm of situatedness. This paradigm was developed by research studies in the fi eld of multi-agent systems, which tend to solve complex problems using collaborative and autonomous agents (multi-agent technology has been largely described in Artifi cial Intelligence literature). These agents in our proposition are embedded within the network elements themselves. Their role is to share local and situated knowledge composing the global KP. We have also developed, as an illustration, a distributed intrusion detection system (IDS) based on the local IDS Snort.

No abstract

The recent development of communication and sensor technology results in the growth of a new attractive and challenging area â€" wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes’ resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network’s operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks.

SUMMARYIn this paper, we propose a time-based channel reservation algorithm (TCRA) suitable for handover and call admission control procedures in future mobile satellite systems. These systems are characterized by a high rate of handover attempts which can degrade significantly their performance. Therefore, we propose TCRA, a scheme which guarantees a null handover failure probability by using a channel reservation strategy in the cells to be crossed by the user. The performance of TCRA has been compared to the guaranteed handover (GH) scheme. The TCRA reservation method has the advantage of a better channel utilization by locking the resources only for their expected time of use. A mathematical model has been developed for both schemes, and its results have been validated through simulations.

The main goal of wireless sensor networks is to gather information from the region of interest through a large number of micro sensor nodes. This gathering is based on a communication architecture such as client/server which consumes a lot of power and doesn't take in consideration the information properties. In this paper, we propose a new communication architecture for wireless sensor networks based on agents' cooperation. This architecture uses techniques from multi-agent systems and networks in order to ensure an optimal information gathering. It benefits from AODV not only for route discovery but also to define the basic list of cooperating agents, using the RREP control message. These agents create cooperatively a simple message summarizing the important information of multiple nodes, where it is widely known that sending a one big message consumes less energy than sending several small messages of the same quantity of information. In order to appreciate our contribution, we discuss its advantages and its limitations by comparing it to client/server and mobile agent architectures.