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The resource of radio frequency spectrum is not efficiently managed, and the increased dependence on wireless devices in the modern era just adds to the problem. The concept of cognitive radio aims to overcome the problem of limited radio frequency spectrum by helping to achieve improved spectral management, utilization, and efficiency. One of the ways to improve the efficiency and utilization of...
The current policies of spectrum allocation leads to inefficient use of spectrum, making it scarce but the truth is, spectrum is not scarce but is underutilized. In today's era dynamic spectrum access is the need of the hour and cognitive radio is a novel technology which improves spectrum utilization. In this paper overview of cognitive radio along with spectrum sensing techniques is taken into account...
Detection of wideband communication signals is critical for cognitive radio (CR) as it enables secondary users to dynamically access the unoccupied bands. However, accurate and fast spectrum sensing is still a challenge in low signal to noise ratio (SNR) environment. To encounter this problem, a feature detector based on compressed sensing (CS) and wavelet transform (WT) (CS-WT feature detector) is...
In dynamic spectrum access paradigm, reliable spectrum sensing is essential for the efficient utilization of the underutilized spectrum as well as the protection of legacy spectrum users. To achieve reliability, it is important for sensing techniques to meet detection requirements, such as the maximum allowed detection time, the probability of misdetection and the probability of false alarm. In this...
In cognitive radios, reliable detection of wireless systems is crucial since these radios share the frequency spectrum with other wireless systems. In a heterogeneous environment, systems with different priorities have different protection requirements and operating parameters.The cognitive radio must guarantee highly reliable communication in the primary systems, but need not necessarily guarantee...
Spectrum sensing is one of the most important technologies in the implementation of cognitive radio system using dynamic spectrum resource management. Since the performance of the widely used energy detector based approach will experience a significant loss under a small noise fluctuation, especially in low SNR, we proposed a two-step spectrum sensing in this paper. With dual-threshold energy detection...
In cognitive radios, reliable detection of wireless systems is crucial since these radios share the frequency spectrum with other wireless systems. At the same time, it is necessary to avoid interference with the primary systems. In a heterogeneous environment, however, systems with different priorities have different protection requirements and operating parameters. The cognitive radio must guarantee...
Cyclostationary detection is regarded as a major method for spectrum sensing in cognitive radio and other applications as well. The rationale behind the detection is that the second order statistic of the interested signal is periodical. The period is therefore used as the critical feature for detection. In practice, due to clock error or oscillator error or other errors, the detector is hardly able...
The spectrum sensing performance of traditional method will be degraded in non-Gaussian background. Fractional low order statistics has the ability of inhibiting alpha-stable distribution noise. By analyzing the fractional low order cyclostationary spectrum sensing algorithm; we find that the correlation of cyclic autocorrelation function vector have a certain amount of loss. In this paper, fractional...
In order to detect the presence of primary user (PU) signal, spectrum sensing is a fundamental requirement to achieve the cognitive radio (CR) goals. This ensures the efficient utilization of the spectrum. There are many methods for signal detection such as cyclostationary detection, cyclic prefix detection, energy detection, and detection based on fractional Fourier transform (FrFT). The aim of this...
We consider a two-stage sensing scheme for cognitive radios where coarse sensing based on energy detection is performed in the first stage and, if required, fine sensing based on cyclostationary detection in the second stage. We design the detection threshold parameters in the two sensing stages so as to maximize the probability of detection, given constraints on the probability of false alarm. We...
The man-induced cyclostationary signatures can provide a robust mechanism for the self-coordination of cognitive radio networks. However, such artificial signatures incur signaling overhead and come at the bandwidth cost. In this paper, we show intrinsic cyclostationary signatures in the Orthogonal Frequency Division Multiplexing (OFDM) system with Cyclic Delay Diversity (CDD). The standard conformable...
In order to detect the presence of the primary user signal, spectrum sensing is a fundamental requirement to achieve the goal of cognitive radio (CR). This ensures the efficient utilization of the spectrum. Cyclostationary detection is the preferred technique to detect the primary users receiving data within the communication range of a CR user at very low SNR. In this work, we investigate the performance...
As we know, cognitive radios should not interfere with the primary users and so, should detect them and vacate the frequency bands when required. In this paper, we propose a novel multiple-antenna receiver diversity scheme based on cyclostationary detection, in order to improve the reliability of primary user detection. We derive closed-form expressions for the probabilities of detection and false...
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