Daniel Willkomm

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Simulating the physical layer of wireless communication remains a challenge. Communication standards like OFDM or MIMO systems go beyond the simple single narrow frequency band, single antenna model used in popular simulators. Yet, these technologies gain popularity, since they provide researchers with a plethora of possibilities that can be explored to(More)
Energy Framework is an extensible OMNeT++ framework for modeling battery consumption in wireless networks. It is designed so there is a clear separation between model-ing of battery state and energy consuming operations, enabling more sophisticated modeling of system behavior. The Energy Framework is largely implemented in " pure " OM-NeT++; it has been(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)
—The fundamental condition for the legal approval of Dynamic Spectrum Access (DSA) approaches is the protection of the Primary User (PU). However, for DSA to become an attractive service reality, it is crucial to ensure also some Quality of Service (QoS) support for the Secondary User (SU) communication. In this paper, we discuss sensing based opportunistic(More)
The sub-optimal exploitation of radio spectrum is widely accepted. Cognitive radio is a technology that aims to address this issue and improve the overall efficiency of radio spectrum utilization. However, this promising technology is far from being mature at present. In addition to theoretical research, experimentally-driven research is needed to convince(More)
—IEEE 802.11 WLANs are currently one of the most popular wireless technologies, but their immediate success results in dense deployments and high demand of user traffic. This in turn leads to decrease in throughput and poor spectrum utilization. Especially in the 2.4 GHz ISM band, where the spectrum is a very scarce resource, all available WLAN channels(More)
Sensing mechanisms that estimate the occupancy of wireless spectrum are crucial to the success of approaches based on Dynamic Spectrum Access. In this paper, we present key insights into this problem by empirically investigating the design of sensing mechanisms applied to check the availability of excess capacity in CDMA voice networks. We focus on(More)
—The major requirement for Cognitive Radio (CR) based opportunistic spectrum re-usage is reliable protection of the primary communication. This calls for a reliable detection of the presence of the Primary Users (PUs) as well as for an immediate reconfiguration of the secondary communication: Each time the PU has been detected, the Secondary Users (SUs)(More)