Abstract—In cognitive radio systems, the main requirement of cognitive radio architectures is the ability to detect the presence of the primary user with fast speed and precise accuracy. To achieve that, we suggest a possible two-stage spectrum sensing approach. More specifically, a fast spectrum

Abstract- There are new system implementation challenges involved in the design of cognitive radios, which have both the ability to sense the spectral environment and the flexibility to adapt transmission parameters to maximize system capacity while co-existing with legacy wireless networks

to noise uncertainty, hence it is not reliable at low SNR. Here, we propose a two-stage spectrum sensing technique consisting of a coarse and a fine sensing stage. In the coarse sensing stage, we locate the possible empty channels within a frequency band using an energy detector and then in the fine

Abstract—Dynamic spectrum access (DSA) is a promising approach for mitigating spectrum scarcity. Underlying DSA is the need for fast and reliable spectrum sensing over a potentially large band. In [4], the concept of two-stage sensing scheme was introduced. In this work, we develop models

Abstract — Dynamic spectrum access (DSA) is a promising approach for the more effective use of existing spectrum. Of fundamental importance to DSA is the need for fast and reliable spectrum sensing over a wide bandwidth. A model for two-stage sensing is described based on an analysis of the mean

We propose a model of how humans sense the velocity of moving images. The model exploits constraints provided by human psychophysics, notably that motion-sensing elements appear tuned for two-dimensional spatial frequen-cy, and by the frequency spectrum of a moving image, namely, that its support

detection time. Index Terms — Two-stage spectrum sensing, cognitive radios, energy detection, cyclostationary detection 1.

Abstract—Sensing/monitoring of spectrum-availability has been identified as a key requirement for dynamic spectrum allocation in cognitive radio networks (CRNs). An important issue associated with MAC-layer sensing in CRNs is how often to sense the availability of licensed channels and in which

set of integrated medium access control (MAC) and physical layer (PHY) spectrum sensing techniques that provide reliable access to television (TV) bands. At the MAC level, we propose a two-stage spectrum sensing that guarantees timely detection of incumbents while meeting the quality of service (Qo

. In such situations some criterion is needed to work out an acceptable allocation which is optimum for all characteristics in some sense. In this paper the problems of the optimum allocation in multivariate two-stage and multivariate stratified two-stage sampling are formulated as Nonlinear Programming Problems (NLPP