We describe Fair Layered Increase/Decrease with Dynamic Layering (FLID-DL), a new multi-rate congestion control algorithm for layered multicast sessions. FLID-DL generalizes the receiver-driven layered congestion (RLC) control protocol introduced by Vicisano, Rizzo, and Crowcroft, ameliorating

(MMOGs) can include millions of concurrent players spread across the world and interacting with each other within a single session. Faced with high resource demand variability and with misfit resource renting policies, the current industry practice is to over-provision for each game tens of self-owned data centres, making the market entry affordable only for big companies. Focusing on the reduction of entry and operational costs, we investigate a new dynamic resource provisioning method for MMOG operation using external data centres as low-cost resource providers. First, we identify in the various types of player interaction a source of short-term load variability, which complements the long-term load variability due to the size of the player population. Then, we introduce a combined MMOG processor, network, and memory load model that takes into account both the player interaction type and the population

platform, the BEA WebLogic server, conducting an in-depth performance analysis of the platform under a number of different workload and configuration scenarios. The methodology we propose is the first one that uses a standard benchmark providing both a representative workload as Message-oriented middleware

Vast majority of wireless appliances used in household, industry and medical field share the ISM frequency band. These devices need to coexist and thus are challenged to tolerate their mutual interference. One way of dealing with this is by using frequency hopping; where the device changes its radio channel periodically. Consequently, communications will not suffer from the same interference each time; instead, it should be fairer and more stable. This thesis investigates the aforementioned problem in the field of low power wireless sensor networks and Internet of Things where Contiki OS is used. We introduce a low-power pseudo-random frequency-hopping MAC protocol which is specifically characterized as a duty cycled asynchronous sender-initiated LPL style protocol. We illustrate two flavors of the protocol; one that does not use any dedicated channel and another which allows dedicated broadcast channels that can implement frequency-hopping as well. We implement

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

Massively multiplayer online games (MMOGs) have become increasingly popular in the recent years, particularly in the form of online role-playing games (MMORPGs). These games support up to several ten thousand players interacting in a virtual game world. The current commercially successful games 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 serious alternative. This work analyzes the implementation of both a client-server and a peer-to-peer networking model for the prototype shooter game Planet π4. Initially, a survey introduces recent academic approaches to peer-to-peer systems specifically designed for games. Of those, one system is selected for implementation with Planet π4. Planet π4 is improved in several aspects for the purpose of analyzing various network implementations. First, its architecture is restructured and cleaned to allow for an easy replacement of the networking component. Second, its core is modified to work in a completely event-based mode, supporting the execution of the game in an discrete-event-based network simulator. Third, a simple artificial intelligence player is developed for workload generation in large (and possibly simulated) networks. Furthermore, the newly developed transport protocol CUSP is applied for the network implementation, thus the game is the first real application using CUSP. Finally the game Planet π4 is integrated with the CUSP network simulator, allowing to run the whole game in a simulated network without the need for modification of its core components. Kurzfassung Massen-Mehrspieler-Onlinespiele (Massively multiplayer online games; MMOGs) wurden in den vergangenen Jahren zunehmend populär, insbesondere in Form von Online-Rollenspielen (MMORPGs). In

unpredictable realworld dynamics. However, common CPS hardware—comprising battery-powered and severely resource-constrained devices interconnected via low-power wireless—greatly complicates attaining the required communication guarantees. VIRTUS fills this gap by providing atomic multicast and view management

Building a more sustainable sensor network via protocol innovation

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

Ultracold atoms in optical lattices provide a highly control-lable environment for the clean experimental realization of various model Hamiltonians from condensed matter and statistical physics. For example, the two-component Bose-Hubbard model, which re-duces to an anisotropic spin-1/2 Heisenberg