Mathias Bohge

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Recent results indicate scalability problems for flat ad hoc networks. To address the issue of scalability, self-organizing hierarchical ad hoc architectures are being investigated. In this paper, we explore the task of providing data and entity authentication for hierarchical ad hoc sensor networks. Our sensor network consists of three tiers of devices(More)
Recently, a lot of research effort has been spent on cross-layer system design. It has been shown that cross-layer mechanisms (i.e., policies) potentially provide significant performance gains for various systems. In this article we review several aspects of cross-layer system optimization regarding wireless OFDM systems. We discuss basic optimization(More)
—One of the major challenges in designing cellular Cognitive Radio (CR) networks is the avoidance of Secondary User (SU) interference to so called Primary Users (PUs) operating in the licensed bands. Usually, SU operation has to be interrupted periodically in order to detect PU activity and avoid the respective frequencies. Recently, Dynamic Frequency(More)
— Dynamic mechanisms such as adaptive modulation and coding or scheduling have been shown to significantly improve the performance of cellular systems. This gain comes at the cost of additional signaling overhead that needs to be delivered from the transmitter to the receiver. In this paper, we explore a resource-constraint control channel that delivers(More)
SUMMARY Soft frequency reuse (SFR) is a common technique for co-channel interference (CCI) mitigation in cellular OFDMA networks. The performance of such networks significantly depends on the configuration of the power profiles that implement the soft frequency reuse patterns. In this paper, we investigate the performance of static soft frequency reuse by(More)
— OFDM systems are known to overcome the impairment of the wireless channel by splitting the given system bandwidth into parallel sub-carriers, on which data symbols can be transmitted simultaneously. This enables the possibility of enhancing the system's performance by deploying adaptive (dynamic) mechanisms, namely power and modulation adaption and(More)
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