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The authors investigate the spectral flatness measure (SFM)-based spectrum sensing technique for cognitive radios. This scheme exploits the fact that under Gaussian noise, the noise-only observations have flattened spectrum, i.e. more white, when compared with that of the observations containing the incumbent or primary signal; hence, an increased SFM under the null hypothesis. Under the null hypothesis,...
The wide proliferation of wireless digital communication services and spectrum scarcity has led to the development of cognitive radio. They can tackle both scarcity as well as growing demand. For efficient utilization of the spectrum, it permits unlicensed users to exploit licensed bands when they are idle. Since licensees are preferred, so the unlicensed users regularly observe the band of licensed...
Spectrum sensing is an enabling technology for cognitive radios. Many sensing algorithms are proposed in the literature, but only a few real time implementation and analysis are reported. There are many challenges when we try to implement the spectrum sensing algorithm in real time. Fading and dynamic noise are major factors, which degrades the performance of sensing algorithm. Multi antenna technology...
As a promising solution to increase usages of the underutilized spectrum, Cognitive Radio Network (CRN) systems face many new practical challenges. Spectrum sensing and associated controlling algorithms are crucial tools toward dynamic spectrum management. Exploring the spatial diversity, distributed cooperative spectrum sensing can effectively overcome the hidden primary user issue. The performance...
In this work, we first analyze the accuracy of different energy detector models in approximating the exact solution in AWGN. These models motivate us to develop approximation analysis to address energy detection for fading channels. Our analysis develops approximation that has almost the same performance as the exact solution in Rayleigh channels. Our new model is simple enough to derive the relationship...
In cognitive radios, energy detector is often considered for spectrum sensing in the literature. However, its performance deteriorates rapidly when noise power is fluctuating. In order to solve this problem, several autocorrelation based detection methods such as statistical covariances based (CAV) detection method and eigenvalue based (MME) detection method have been proposed. However, CAV detector...
In cognitive radio networks, spectrum sensing is a key technology to detect the presence of the primary user. In this paper, a joint energy and autocorrelation based spectrum sensing algorithm is proposed. The proposed detection algorithm is based on the assumption that the primary user's signal is not white. We compare the performance of the proposed detector and the conventional energy detector...
Cognitive radios are devices capable of sensing a large range of frequencies in order to detect the presence of primary networks and reuse their bands when they are not occupied. Due to the large spectrum to be sensed and the high power signal dynamics, low-cost implementations of the analog front-ends leads to imperfections. Two of them are studied in this paper: IQ imbalance and sampling clock offset...
As a growing interest in the cognitive radio technology has been taken based on the idea of opportunistic spectrum use, the spectrum sensing technique for dynamic channel environment is more and more important to ensure that cognitive radios would not interfere with primary systems while it achieves reasonable throughput opportunistically. Architecture based on filter bank allows to sense multi-channels...
Cognitive radio (CR) is currently being seen as the future for wireless communications. Fundamental to the operation of a CR is the sensing of legacy communication. Energy detector (ED) is a simple and effective signal sensing method. However, the ED requires accurate estimation of the noise power. Any error in the estimation, which is common in practice, affects its performance. Communication signals...
Dynamic spectrum sharing is a concept where unlicensed devices are allowed to opportunistically access unused spectrum bands. The goal of this paper is to develop and analyze a novel secondary user sensing strategy that on the average minimizes the need to take sensing measurements and therefore maximizes throughput. In particular, we focus on the IEEE 802.22 standard where the goal is to detect TV...
As the wireless communication services grow quickly, the seriousness of spectrum scarcity has been on the rise gradually. In this context, an emerging technology, cognitive radio (CR) has been come out to solve today's spectrum scarcity problem. Among its fundamental functions, the most important function is spectrum sensing which requires precise accuracy and low complexity. Thus, in this paper,...
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