Albert Rafetseder

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Hands-on experience is a critical part of research and education. Today’s distributed testbeds fulfill that need for many students studying networking, distributed systems, cloud computing, security, operating systems, and similar topics. In this work, we discuss one such testbed, Seattle. Seattle is an open research and educational testbed that utilizes(More)
Content Distribution Networks serve a large share of today’s Internet traffic from a multitude of locations, each in relative proximity to the respective consumers. In this paper, we analyze the performance of the YouTube video platform using Seattle, a distributed Internet testbed running on donated resources (like SETI@home), including equipment on the(More)
The recent shift from specialized video streaming solutions to user-friendly Web-based video delivery platforms has attracted large audiences to these platforms. However, this could also result in future bandwidth bottlenecks and a degradation of network parameters if traffic demands continue to rise. Due to the reliable TCP protocol the influence of(More)
High quality and sustained multi media experience is expected to be a major feature of the Future Mobile Internet (FMI). Currently deployed novel mobile network technologies such as LTE (Long Term Evolution) make use of the Internet and its best-effort TCP/IP protocol stack to enable applications. The orientation towards TCP/IP is logical due to the success(More)
In this paper, we present a generic framework for performance evaluation of video streams. We embrace the perspective of a streaming application, and model the playback buffer level at given network and playback conditions. That way, our model enables flexible, adaptable evaluation of a wide variety of streaming methods and protocols. We test our model on(More)
Applications such as software updaters or a run-away web app, even if low priority, can cause performance degradation, loss of battery life, or other issues that reduce a computing device’s availability. The core problem is that OS resource control mechanisms unevenly apply uncoordinated policies across different resources. This paper shows how handling(More)
The Internet today consist of many heterogeneous infrastructures, owned and maintained by separate and potentially competing administrative authorities. On top of this a wide variety of applications has different requirements with regard to quality, reliability and security from the underlying networks. The number of stakeholders who participate in(More)
Modern computing devices, including smartphones, laptops, and tablet computers, are equipped with an increasing number of sensors and data sources, ranging from accelerometers to 3G radio information. But different devices and platforms such as Android and iOS use very different interfaces for sensors access. There is no common way to access and facilitate(More)
Smartphones contain sensors that provide information about the user of the device. Studying smartphones, therefore, provides an invaluable window into the behavioral patterns of users. In this work, we describe an open infrastructure that provides research communities with principled access to mobile devices and their sensors. Our platform, the Sensibility(More)
To further the knowledge of basic game mechanics and improve future video game Quality of Experience (QoE) studies we present a model and simulation for End-to-End (E2E) lag in networked and cloud computer games. E2E lag describes the latency between a user’s action and the display of the action’s results on the screen, thus providing both a basic measure(More)