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Postprint This is the accepted version of a paper published in IEEE Communications Magazine. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination. Access to the published version may require subscription. Abstract— One of the key challenges of the emerging Cognitive Radio based IEEE 802.22(More)
— Recently, secondary usage of spectrum has been considered in order to better exploit spectral resources and overcome the under-utilization of licensed spectrum. Since the licensed user still keeps primary access rights to its spectrum in such a secondary usage scenario, potential Secondary Users (SUs) have to vacate the spectrum in case the licensed user(More)
— While essentially all of the frequency spectrum is allocated to different applications, observations provide evidence that usage of the spectrum is actually quite limited, particularly in bands above 3 GHz. In this paper we present a Cognitive Radio approach for usage of Virtual Unlicensed Spectrum (CORVUS), a vision of a Cognitive Radio (CR) based(More)
Dynamic Spectrum Access (DSA) approaches, which propose to opportunistically use underutilized portions of licensed wireless spectrum such as cellular bands, are increasingly being seen as a way to alleviate spectrum scarcity. However, before DSA approaches can be enabled, it is important that we understand the dynamics of spectrum usage in licensed bands.(More)
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)
— Cognitive Radios have been advanced as a technology for the opportunistic use of under-utilized spectrum. Cognitive Radio are able to sense the spectrum and detect the presence of Primary Users. However, Primary Users of the spectrum are skeptical about the robustness of this sensing process and have raised concerns with regards to interference from(More)
Frequency Assignment is an important approach to mitigate multicell interference in cellular systems. In this paper, we consider the frequency assignement in such systems with frequency hopping. In particular we focus our attention on cognitive radio cellular systems as one of the very promising future access technologies, taking IEEE 802.22 as an example,(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)
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)