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—Several spectrum measurement campaigns have been performed in diverse locations and scenarios in order to assess the degree to which spectrum is currently used in real wireless communication systems. Although such measurement campaigns follow similar approaches, there is a lack of common and appropriate evaluation methodology, which would be desirable not(More)
Energy detection constitutes a preferred approach for spectrum sensing in cognitive radio due to its simplicity and applicability (it works irrespective of the signal format to be detected) as well as its low computational and implementation costs. The main drawback, however, is its well-known detection performance limitations. Various alternative detection(More)
— Cognitive Radio (CR) has been identified as a promising solution to the so-called spectrum scarcity problem. The basic idea of this paradigm is to allow unlicensed users to access in an opportunistic and non-interfering manner some licensed bands that are temporarily unoccupied by licensed users. CR is expected to significantly increase current spectrum(More)
Cognitive radio terminals sense the spectrum to detect temporarily unoccupied spectrum gaps and transmit. The behavior of a network of cognitive radio terminals therefore depends on the spectrum occupancy perceived by each terminal at its local environment. In this context, this work explores (via empirical measurements) the spectrum occupancy that would be(More)
Cognitive radio is an enabling technology to solve the spectrum scarcity problem in wireless communication. This is based on the concept of opportunistic spectrum access. Spectrum sensing is one of the most important functions in cognitive radio (CR) implementation. In this paper, we propose a multiple energy detectors (MED) based scheme with improved(More)
Cognitive radio has been claimed to be a hopeful solution to the existing conflicts between spectrum demand growth and spectrum underutilization. The basic underlying idea of cognitive radio is to allow unlicensed users to access in an opportunistic and non-interfering manner some licensed bands temporarily unoccupied by licensed users. The cognitive radio(More)
This paper presents an empirical time-dimension model of spectrum use in the context of dynamic spectrum access. Concretely, a discrete-time two-state Markov chain with novel duty cycle models is proposed as an adequate mean to accurately describe spectrum occupancy in the time domain. The validity and accuracy of the proposed model is assessed and(More)
Heterogeneous wireless systems are envisaged as the integration and joint cooperative management of diverse radio access networks and technologies through which network providers can satisfy the wide variety of user/service demands in a more efficient manner by exploiting their varying characteristics and properties. To achieve this objective, a key tool is(More)
—The spectrum occupancy models widely used to the date in Dynamic Spectrum Access/Cognitive Radio (DSA/CR) research frequently rely on assumptions and oversimplifications that have not been validated with empirical measurement data. In this context, this work presents an empirical time-dimension model of spectrum use appropriate for DSA/CR studies.(More)