330 research outputs found

    Flexible Application-Layer Multicast in Heterogeneous Networks

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    This work develops a set of peer-to-peer-based protocols and extensions in order to provide Internet-wide group communication. The focus is put to the question how different access technologies can be integrated in order to face the growing traffic load problem. Thereby, protocols are developed that allow autonomous adaptation to the current network situation on the one hand and the integration of WiFi domains where applicable on the other hand

    Energy efficient broadcasting in wireless ad hoc networks

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    In recent years wireless multi-hop networks have attracted significant attention due to their wide range of potential civil and military applications. Broadcasting is a funda- mental data dissemination scheme for these networks. The transmission power control is an important issue in wireless ad hoc networks and still has no satisfactory solution methods. The wireless networking environment presents formidable challenges to the study of broadcasting problems. In particular, the properties of the wireless medium and the presence of battery-powered devices require novel modeling and algorithmic approaches concentrating on judicious use of limited energy resources in wireless net- works. In addition, networks are often required to provide certain quality of service (QoS) guarantees in terms of the end-to-end delay along the individual paths from the source to each of the destination nodes. Moreover, the received signal at each receiv- ing node must be strong enough to be successfully decoded. In this study we address the minimum-energy broadcast problem in multi-hop wireless networks with respect to two different constraints: (i) each node must receive broadcast message within a given delay bound Δ, and (ii) signal-to-interference-plus-noise ratio (SINR) of the received signal must be above a given threshold [y] so that the received signal can be successfully decoded at the receiving node. We propose two distinct algorithms Distributed Tree Expansion (DTE) and SINR-BIP which aim to generate minimum power broadcast tree with respect to constraint (i) and (ii), respectively and exclusively. DTE is based on an implementation of a distributed minimum spanning tree algorithm in which the tree grows at each iteration by adding a node that can cover the maximum number of currently uncovered nodes in the network with minimum incremental transmission power and without violating the delay constraint. In SINR-BIP, we apply the similar idea of well-known Broadcast Incremental Power (BIP) algorithm while considering the SINR values of received powers. In addition, we use an embedded pruning procedure in SINR-BIP, so that the myopic effect of the algorithm is mitigated. Both the algo- rithms DTE and SINR-BIP are constructive in nature since the broadcast tree grows at each iteration. We observed that the DTE outperforms the existing algorithms and the total energy consumptions of the generated broadcast trees by DTE is within 20% percent of the solutions obtained by Integer Programming

    Mobile Ad-Hoc Networks

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    Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks
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