are client-server based, which is feasible for relatively slow role-playing games. Those have modest bandwidth and latency requirements and are paid for by their customers. For MMOGs with higher realtime requirements and/or a smaller number of customers willing to pay, peer-to-peer networking seems to be a

Messaging is a basic service in sensornets. Yet the unique system and application prop-erties of sensornets pose substantial challenges for the messaging design: Firstly, dynamic wireless links, constrained resources, and application diversity challenge the architecture and protocol design

I herewith certify that all material in this dissertation which is not my own work has been properly acknowledged.

In presenting this thesis in partial fulfilment of the requirements for a Postgraduate degree

April 29, 2011Für UnsShe had never before seen a rabbit with either a waistcoat-pocket, or a watch to take out of it, and burning with curiosity, she ran across the field after it Lewis CarrollThe following document, written under the supervision of Dr. reviewed by:

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Abstract—Mathematical models play a pivotal role in understanding and designing advanced low-power wireless systems. However, the distributed and uncoordinated operation of traditional multi-hop low-power wireless protocols greatly complicates their accurate modeling. This is mainly because these protocols build and maintain substantial network state to cope with the dynamics of low-power wireless links. Recent protocols depart from this design by leveraging synchronous transmissions (ST), whereby multiple nodes simultaneously transmit towards the same receiver, as opposed to pairwise link-based transmissions (LT). ST improve the one-hop packet reliability to an extent that efficient multi-hop protocols with little network state are feasible. This paper studies whether ST also enable simple yet accurate modeling of these protocols. Our contribution to this end is twofold. First, we show, through experiments on a 139-node testbed, that characterizing packet receptions and losses as a sequence of independent and identically distributed (i.i.d.) Bernoulli trials—a common assumption in protocol modeling but often illegitimate for LT—is largely valid for ST. We then show how this finding simplifies the modeling of a recent ST-based protocol, by deriving (i) sufficient conditions for probabilistic guarantees on the end-toend packet reliability, and (ii) a Markovian model to estimate the long-term energy consumption. Validation using testbed experiments confirms that our simple models are also highly accurate; for example, the model error in energy against real measurements is 0.25%, a figure never reported before in the related literature. I.

Hiermit versichere ich, die vorliegende Master-Thesis ohne Hilfe Dritter nur mit den angegebenen Quellen und Hilfsmitteln angefertigt zu haben. Alle Stellen, die aus Quellen entnommen wurden, sind als solche kenntlich gemacht. Diese Arbeit hat in gleicher oder ähnlicher Form noch keiner Prüfungsbehörde vorgelegen. Darmstadt, den 17. Mai 2011 (Marcel Lucas) The popularity of Networked Virtual Environments (NVE) increased remarkably in recent years where a plethora of players participate concurrently. Traditional approaches applying the Client/Server pattern swiftly reach their limit in terms of scalability and maintainability. Hence, different approaches are based on Peer-to-Peer (P2P) technology. In particular, fast-paced NVEs stress these systems and most likely cause high overlay maintenance overhead. This Master’s Thesis presents a novel approach to spatial Publish/Subscribe (Pub/Sub) in P2P NVEs. The unstructured P2P system BubbleStorm offers flexible and scalable means and is therefore used as a fundamental base for the developed Pub/Sub system. As the evaluation of the subscription is performed

the required type of information while trading off precision for costs. We previously introduced application-specific integrated aggregation (ASIA) as a means for collecting metadata in distributed event-based systems. In this paper, we show how ASIA can support IT Service Management in monitoring

in these networks, and (3) the extremely limited computational and energy resources available. Until now, the burden of handling these issues was put on the software application developer. This dissertation presents three novel programming models and middleware systems that address these challenges: Limone, Agilla