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—Communication between cars can be exploited for various applications. Security enhancements as well as interactive games played by occupants of different cars are only two examples. The IEEE 802.11p standard will specify physical and MAC-layer for such scenarios. As one of the design goals is to partially reuse existing WLAN technology we investigate in(More)
—Several measurement campaigns have shown that numerous spectrum bands are vacant although licenses have been issued by the regulatory agencies. Dynamic spectrum access (DSA) has been proposed in order to alleviate this problem and increase the spectral utilization. In this paper we present our spectrum measurement setup and discuss lessons learned during(More)
Dynamic spectrum access (DSA) has been proposed as a solution to the spectrum scarcity problem. However, the models for spectrum use, that are commonly used in DSA research, are either limited in scope or have not been validated against real-life measurement data. In this paper we introduce a flexible spectrum use model based on extensive measurement(More)
—There is need to develop better models and characterization methods for spectrum usage and radio environments of cognitive radios. Currently different theoretical and simulation based approaches towards enabling dynamic spectrum access would greatly benefit from the possibility to generate synthetic data for testing purposes. Such Radio Environment Maps(More)
—Dynamic spectrum access is an integral part of the Cognitive Radio paradigm. However, efficient spectrum sensing techniques are crucial on the way towards systems, which use idle spectrum bands opportunistically and increase the overall spectral efficiency. Current spectrum occupancy was evaluated in few measurement campaigns at different locations mostly(More)
In order to opportunistically exploit unused radio spectrum nodes of dynamic spectrum access (DSA) networks monitor the spectrum around them. Such cognitive radios can greatly benefit from a spatial characterization of spectrum use. However, there is need to find an efficient way to describe spatial use, something which has not been studied in details so(More)
—At present wireless devices are able to select their working frequency only to a limited extend although several measurements have shown that the current spectrum regulations are inefficient. Dynamic spectrum access is seen as a promising approach that might solve this inefficiency. Spectrum sensing is one of the main tasks involved. We compare in this(More)
—Several measurement studies have found a large amount of underutilized radio spectrum. More flexible regulation employing dynamic spectrum access (DSA) has been proposed as solution to this problem. The analysis of several aspects of DSA systems, e.g., cooperative sensing, requires good spatial models of spectrum usage. However, only very focused models(More)
Reliable network simulators are important tools for research and development in the field of wireless communication. Although the ns-2 simulator is quite popular for testing wireless network protocols in industry and academia, it is more than clear that it needs numerous improvements in order to produce results fitting to realistic scenarios. There are many(More)