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A cognitive radio system coexisting with various systems must perform a spectrum sensing for finding a white space (WS). In this paper, we propose a new two-stage spectrum sensing method using an energy detection (ED) based on fast Fourier transform (FFT). In the case that an unknown signal is present the FFT band, false signals are detected in the surrounding FFT bins of the received signal due to...
A cognitive radio system coexisting with various systems must perform a spectrum sensing for finding a white space (WS). In this paper, we propose a new two-stage spectrum sensing method using an energy detection (ED) based on fast Fourier transform (FFT). In the case that an unknown signal is present the FFT band, false signals are detected in the surrounding FFT bins of the received signal due to...
Today, communication systems face major shortages in availability of free spectrum. Cognitive radio has evolved as the most feasible technology which can empower us to effectively utilize the available spectrum. A vital component of a Cognitive Radio Network is spectrum sensing, i.e. its ability to detect the presence of a primary user. This paper employs an adaptive threshold detection algorithm...
This paper proposes a new algorithm for jammer detection in wide-band (WB) cognitive radio networks. We consider a WB which comprises of multiple fixed length narrow-band sub-bands (SB). These SBs are occupied by narrow-band signals which can be legitimate users or a jammer. To reduce the overhead of the analog-to-digital conversion (ADC), compressed sensing (CS) is performed first. CS allows us to...
In this paper, we study an implementation of the Benjamini-Hochberg's procedure for cooperative multiband spectrum sensing in cognitive radio. We propose to use equal gain combining on forwarded p-values from cooperative cognitive radio (CR) users as the test statistic at the fusion center. By doing so, the distribution of the test statistic under the null hypothesis at the fusion center does not...
We evaluate an estimation scheme of unknown signal's bandwidth estimation with an energy detector based on a windowed fast Fourier transform (FFT) for cognitive radio system. When the cognitive node obtains the spectrum sensing results after a received time domain signal is processed with FFT, the detection results have a detection error at the adjacent FFT bins of the received signal frequency with...
This paper describes the implementation and the experimental performance of a spectrum sensing scheme, based on a Constant False Alarm Rate (CFAR) algorithm, for cognitive radio in TV white space (TVWS) operation. We use various signal profiles, representing an incumbent or primary user (PU) in the channel, along with a physical testbed to experimentally measure the detection of a PU signal over the...
Recently maritime cognitive radio network is proposed to provide high bandwidth and low communication cost for maritime users. Spectrum sensing is one of the key issues to develop cognitive radio networks. Radio propagation is one of the main differences between maritime and land environment. Traditional detectors such as matched filter, energy detector and cyclostationary detector are not robust...
Recent years have shown a growing interest in the concept of cognitive radios (CR), in order to access the electromagnetic spectrum in an opportunistic way. Such systems require efficient spectrum detectors able to work in low signal-tonoise ratio (SNR) environments, with little or no information about the signals. In this paper, using the theory of higher-order statistics (HOS), a two-stage spectrum...
In this paper, a number of spectrum sensing schemes implementation in ultra wideband and Cognitive radio component (UWB-CR) under different fading settings condition are studied. The sensing performance of different detectors is compared in conditions of probability of miss detection curves. Numerically simulation results are shown that the selection of detector rely on the scenario, the detector...
Cognitive radio is an emerging technology for sensing and dynamic access of spectrum in mobile radio environments. It aims at dynamically allocating unused bandwidth among secondary users without causing harmful interference to the primary users. This approach, which has clear economical benefits, has recently attracted significant research effort. In this paper, we propose a new approach to dynamic...
The ability of adapting to the environment in the most efficient way is a crucial issue in Cognitive Radio (CR) networks. For this purpose, an accurate estimation of the characteristics and activity of the Primary Users (PUs) is required. A system that takes into account heterogeneous PUs with several features is developed. A new scheme is integrated in the system to exploit these motleys and to improve...
One of the key requirements in cognitive radio is accurate detection of vacant spectrum bands. In this paper, an energy detector based on a tree-structured quadrature mirror filter bank (TQMFB) is proposed for detecting the center frequencies of the channels (frequency bands). Simulation results are presented to show the trade off between the window size, k, and the error in estimating the center...
Accurate and efficient spectrum sensing is a critical component of cognitive radio, which is a technology poised to improve dynamic resource management in future wireless networks. Autocorrelation exploitation has been shown to provide improvements in sensing performance over simple methods like energy detection. A new upper bound on the performance of autocorrelation-based detectors based on an NP...
With recent advances in wireless applications like multimedia applications & rich Web services, spectrum scarcity is increasing with every passing day. The scarcity of spectrum is not due to its rareness; it is mainly due to its inefficient utilization. Cognitive radio is a promising solution to this problem. It is, ideally, an intelligent radio which senses the spectrum and opportunistically...
A cognitive radio (CR) is able to sense spectral environment over a wide range of frequencies, and provide opportunistic access to frequency bands temporarily unoccupied by an incumbent. Accurate channel sensing is the first important task for a CR, and energy detector is often used for this purpose. While a normal energy detector works well with well chosen window size based on prior knowledge about...
Cognitive radio (CR) is viewed as a novel approach for improving utilization of the precious radio spectrum. Spectrum sensing is one of the most important technologies in cognitive radio. A general presentation of OFDM technology and cooperative spectrum sensing are given in the first instance. In order to improve detection probability and reduce equipment complex and computation complex, to combine...
This paper discusses an interference DAA (Detection And Avoidance) technique for coexisting pulse based UWB and OFDM systems when the both systems are operated in the same frequency band. In a UWB transmitter-receiver, utilization of the OFDM system is detected by correlating with the GI (Guard Interval) signals. And also timing of the GI period is detected for interference mitigation. The UWB signal...
Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, these may not...
Welch spectrum estimator may be used for spectrum monitoring and sensing. Conventionally, the detection threshold is set assuming that the noise power is estimated from noise-only samples. The forward consecutive mean excision (FCME) algorithm is a method for automatically making decisions based on the decision variables, without estimation of the noise power a priori. In this paper, we propose the...
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