Günter Haring

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In this paper, we develop a performance model of a cell in a wireless communication network where the e ect of hando arrival and the use of guard channels is inlcuded. Fast recursive formulae for the loss probabilities of new calls and hando calls are developed. Monotonicity properties of the loss probabilities are proven. Algorithms to determine the(More)
Over the last decade a large number of routing protocols has been designed for achieving energy efficiency in data collecting wireless sensor networks. The drawbacks of using a static sink are well known. It has been argued in the literature that a mobile sink may improve the energy dissipation compared to a static one. Some authors focus on minimizing(More)
Performance evaluation studies are to be an integral part of the design and tuning of parallel applications Their structure and their behavior are the dominating factors We propose a hierarchical approach to the systematic characterization of the workload of a parallel system to be kept as modular and exible as possible The methodology is based on three di(More)
Congestion severely affects the performance of a wireless sensor network in two aspects: increased data loss and reduced lifetime. This paper addresses these problems by introducing a mobile sink based routing scheme for congestion avoidance and energy efficient routing in wireless sensor networks. The proposed scheme utilizes the sink mobility and an(More)
Mean value analysis (MVA) is a well accepted and widespread technique used in performance modeling of computer and communication systems. In many cases, like for sensitivity analysis or with inaccurate model input parameters, intervals are more appropriateas model inputs than single values. For the exact MVA for separable, closed queueing networks with one(More)
Over the last decades, modeling of user mobility has become increasingly important in mobile networking research and development. This has led to the adoption of modeling techniques from other disciplines such as kinetic theory or urban planning. Yet these techniques generate movement behavior that is often perceived as not “realistic” for(More)
Bounding techniques for queueing network models used to analyze the perfor mance of parallel and distributed computer systems accept single values as model inputs Uncertainties or variabilities in service demands may exist in many types of systems Using models with a single aggregate mean value for each parameter for such systems can lead to inaccurate or(More)