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spectrum-sensing
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A Fast Soft Decision Algorithm for Cooperative Spectrum Sensing
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 68, Issue 1 , 2021 , Pages 241-245 ; 15497747 (ISSN) ; Fakharzadeh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Hidden Primary User problem caused by fading and shadowing severely affects the detection rate of the cognitive radio systems with a single spectrum sensor. Cooperative Spectrum Sensing has been introduced to tackle this problem by using the spatial diversity of spectrum sensors. It is shown that the use of soft decision algorithms in fusion center has a better performance than hard decision algorithms. The problem of soft decision based on sensor measurements perfectly matches the Machine Learning paradigm. In this brief, a novel fast soft decision algorithm is proposed based on Machine Learning theory for wideband Cooperative Spectrum Sensing, which finds a decision boundary to classify...
Simultaneous Block Iterative Method with Adaptive Thresholding for Cooperative Spectrum Sensing
, Article IEEE Transactions on Vehicular Technology ; Volume 68, Issue 6 , 2019 , Pages 5598-5605 ; 00189545 (ISSN) ; Abtahi, A ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
The effective utilization of the spectrum has become an essential goal in the communications field, which is addressed by the Cognitive Radio (CR) systems. The primary task in a CR system is to sense the spectrum to identify its holes to be exploited by the secondary users. In this paper, we tackle the compressed spectrum sensing problem in a cooperative manner. The CRs distributed in an area take the samples of the signal that has been reached to them through a wireless fading channel. The spectrum has the block-sparse structure. Moreover, the spectrum observed by different CRs in an area share the same block-sparse support. Therefore, we suggest to exploit the joint block-sparsity...
Analytical studies of fragmented-spectrum multi-level OFDM-CDMA technique in cognitive radio networks
, Article 7th IEEE Annual Ubiquitous Computing, Electronics and Mobile Communication Conference, UEMCON 2016, 20 October 2016 through 22 October 2016 ; 2016 ; 9781509014965 (ISBN) ; Sharifi Malvajerdi, S ; Poursaeed, O ; Salehi, J. A
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, we present a multi-user resource allocation framework using fragmented-spectrum synchronous OFDM-CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, a channel sensing and estimation method is used to obtain information of subcarrier availability. Given this information, some real-valued multi-level orthogonal codes, which are orthogonal codes with values of {±1, ±2, ±3, ±4,...}, are provided for emerging new users, i.e., cognitive radio users. Additionally, we have obtained a closed form expression for bit error rate of cognitive radio receivers in terms of detection...
A robust algorithm based on wavelet transform for recognition of binary digital modulations
, Article 2015 38th International Conference on Telecommunications and Signal Processing, TSP 2015, 9 July 2015 through 11 July 2015 ; July , 2015 , Pages 508-512 ; 9781479984985 (ISBN) ; Pezeshk, A. M ; Behnia, F ; Molnar K ; Herencsar N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Automatic Modulation Recognition (AMR) of communication signals has been an important theme in wireless communication systems. Recently, digital modulation recognition has been considered remarkably, due to the vast application of this kind of AMR technique in spectrum sensing and cognitive radio. In this paper, we propose a wavelet-based algorithm for recognition of binary digital modulation schemes including BASK, BFSK and BPSK in presence of Additive White Gaussian Noise (AWGN). In this algorithm, Haar Wavelet Transform (HWT) of the received signal is compared to templates and the similarity of them are measured. Experimental results show a perfect classification of binary digital...
Multi-antenna assisted spectrum sensing in spatially correlated noise environments
, Article Signal Processing ; Volume 108 , December , 2015 , Pages 69-76 ; 01651684 (ISSN) ; Malek Mohammadi, M ; Babaie Zadeh, M ; Skoglund, M ; Sharif University of Technology
Elsevier
2015
Abstract
A significant challenge in spectrum sensing is to lessen the signal to noise ratio needed to detect the presence of primary users while the noise level may also be unknown. To meet this challenge, multi-antenna based techniques possess a greater efficiency compared to other algorithms. In a typical compact multi-antenna system, due to small interelement spacing, mutual coupling between thermal noises of adjacent receivers is significant. In this paper, unlike most of the spectrum sensing algorithms which assume spatially uncorrelated noise, the noises on the adjacent antennas can have arbitrary correlations. Also, in contrast to some other algorithms, no prior assumption is made on the...
A real-time, low-power implementation for high-resolution eigenvalue-based spectrum sensing
, Article Analog Integrated Circuits and Signal Processing ; Volume 77, Issue 3 , December , 2013 , Pages 437-447 ; 09251030 (ISSN) ; Shabany, M ; Sharif University of Technology
2013
Abstract
In this paper, a novel multiple antenna, high-resolution eigenvalue-based spectrum sensing algorithm based on the FFT of the received signal is introduced. The proposed platform overcomes the SNR wall problem in the conventional energy detection (ED) algorithm, enabling the detection of the weak signals at -10 dB SNR. Moreover, the utilization of FFT for the input signal channelization provides a simple, low-power design for a high-resolution spectrum sensing regime. A real-time, low-area, and low-power VLSI architecture is also developed for the algorithm, which is implemented in a 0.18 μm CMOS technology. The implemented design is the first eigenvalue-based detection (EBD) architecture...
Analytical and learning-based spectrum sensing time optimisation in cognitive radio systems
, Article IET Communications ; Volume 7, Issue 5 , 2013 , Pages 480-489 ; 17518628 (ISSN) ; Abdi, Y ; Nasiri Kenari, M ; Sharif University of Technology
2013
Abstract
In this study, the average throughput maximisation of a secondary user (SU) by optimising its spectrum sensing time is formulated, assuming that a priori knowledge of the presence and absence probabilities of the primary users (PUs) is available. The energy consumed to find a transmission opportunity is evaluated, and a discussion on the impacts of the number of PUs on SU throughput and consumed energy are presented. To avoid the challenges associated with the analytical method, as a second solution, a systematic adaptive neural network-based sensing time optimisation approach is also proposed. The proposed scheme is able to find the optimum value of the channel sensing time without any...
A new spectrum sensing method using output analysis of the PFD
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 60, Issue 6 , 2013 , Pages 366-370 ; 15497747 (ISSN) ; Fotowat Ahmady, A ; Forooraghi, K ; Atlasbaf, Z ; Sharif University of Technology
2013
Abstract
In this brief, a new blind spectrum sensing method is proposed based on frequency comparison using a phase frequency detector (PFD). The PFD output patterns are utilized in a way to sense the spectrum with no knowledge of incoming signals, noise, or channel parameters. The detection and false alarm error probabilities are analytically calculated for additive white Gaussian noise and sine-wave input and are simulated for different inputs. It is shown that the required detection and false alarm probabilities can be achieved by changing the system parameters. The results show that the proposed method has lower complexity and outperforms the previous single-antenna blind method over flat fading...
Distributed multiuser sequential channel sensing schemes in multichannel cognitive radio networks
, Article IEEE Transactions on Wireless Communications ; Volume 12, Issue 5 , 2013 , Pages 2055-2067 ; 15361276 (ISSN) ; Sheikholeslami, F ; Nasiri Kenari, M ; Sharif University of Technology
2013
Abstract
Effective spectrum sensing strategies enable cognitive radios (CRs) to identify and opportunistically transmit on under-utilized spectral resources. In this paper, sequential channel sensing problems for single and multiple secondary users (SUs) networks are effectively modeled through finite state Markovian processes. More specifically, a model for single user case is introduced and its performance is validated through analytical analysis. Then, in order to address multiple SUs case, this model is extended to include the modified p-persistent access (MPPA) protocol. Since the scheme utilized experiences a high level of collision among the SUs, to mitigate the problem appropriately,...
A VLSI architecture for multiple antenna eigenvalue-based spectrum sensing
, Article 2012 19th IEEE International Conference on Electronics, Circuits, and Systems, ICECS 2012, 9 December 2012 through 12 December 2012 ; December , 2012 , Pages 153-156 ; 9781467312615 (ISBN) ; Shabany, M ; Sharif University of Technology
2012
Abstract
An Eigenvalue-based detection (EBD) scheme, is proposed as an efficient method to overcome the noise uncertainty and the SNR wall problem in conventional energy detection (ED) schemes. Despite remarkable efforts made to analyze the EBD performance, a VLSI implementation is missing in literature. In this paper, a new FFT-based EBD algorithm is introduced, which eliminates the need for filter banks and discrete wavelet packet transform to channelize the input signal. The proposed method enables the utilization of the EBD algorithm in high-resolution spectrum sensing approaches. Moreover, it enables the detection of signals with SNRs as low as -10 dB. A low-power, area-efficient yet real-time...
Learning-based spectrum sensing time optimization in cognitive radio systems
, Article 2012 6th International Symposium on Telecommunications, IST 2012, 6 November 2012 through 8 November 2012 ; November , 2012 , Pages 249-254 ; 9781467320733 (ISBN) ; Abdi, Y ; Nasiri-Kenari, M ; Sharif University of Technology
2012
Abstract
Powerful spectrum sensing schemes enable cognitive radios (CRs) to find transmission opportunities in spectral resources allocated exclusively to primary users. In this paper, the problem of maximizing the average throughput of a cognitive radio system through optimizing its spectrum sensing time is investigated, and a systematic neural network-based optimization approach is proposed which avoids challenges associated with the conventional analytical solutions. The proposed method exploits a novel learning and optimization cycle to enable an effective cooperation between two kinds of well-known artificial neural networks and finds the optimum value of the channel sensing time without any...
Performance comparison of the neyman-pearson fusion rule with counting rules for spectrum sensing in cognitive radio
, Article Iranian Journal of Science and Technology - Transactions of Electrical Engineering ; Volume 36, Issue E1 , 2012 , Pages 1-17 ; 22286179 (ISSN) ; Tadaion, A. A ; Derakhtian, M ; Aref, M. R ; Sharif University of Technology
2012
Abstract
Distributed spectrum sensing (DSS) is of great importance in Cognitive Radio, especially under fading or shadowing effects. In order to evaluate the performance of a distributed system, it is commonly compared with the centralized system as an upper performance bound. Now the question is whether or not one can obtain a distributed strategy serving as an upper bound to benchmark any distributed strategy, tighter than that of the centralized scheme. Here, we suggest employing the Neyman-Pearson (NP) fusion rule to achieve an upper bound. Furthermore, the analysis of a randomized fusion rule has been provided, which is a long-existing problem in this field. For this purpose, theoretical...
A new spectrum sensing circuit for cognitive radio applications
, Article Proceedings - CIMSim 2011: 3rd International Conference on Computational Intelligence, Modelling and Simulation, 20 September 2011 through 22 September 2011, Langkawi ; 2011 , Pages 404-407 ; 9780769545622 (ISBN) ; Forooraghi, K ; Atlasbaf, Z ; Ahmadi, A. F ; Sharif University of Technology
2011
Abstract
Fast, accurate and efficient sensing is of important aspects in cognitive radio technology. A new sensing circuit is proposed using a phase frequency detector for cognitive radio applications. Using this method, spectral sensing can be done in a very short time by a low cost, low power circuit, compared with available implemented methods. The PFD circuit resolves different frequencies without the need of variable filter bandwidth or the banks of filters. Also it accelerates sensing procedure because of short time needed to detect the signal. Simulations show the accurate operation of this method and comparison with other methods shows faster sweep rates
Cooperative cyclostationary spectrum sensing in cognitive radios at low SNR regimes
, Article IEEE International Conference on Communications, 23 May 2010 through 27 May 2010, Cape Town ; 2010 ; 05361486 (ISSN) ; 9781424464043 (ISBN) ; Nasiri Kenari, M ; Le Ngoc, T ; Sharif University of Technology
2010
Abstract
The paper proposes efficient cooperative cyclostationary spectrum sensing schemes in which each secondary user (SU) performs single-cycle cyclostationary detection for fast and simple implementation, while collaboration between SUs in final decision on the presence or absence of the primary user (PU) is explored to improve its performance. As the SUs simultaneously measure the spectral correlation functions at different cycle frequencies (CF) and exchange their information regarding the measured results, a sufficient number of CFs are effectively examined in a short period of time because of parallel searching, which makes the proposed cooperative spectrum sensing more reliable and faster....
Multiple antenna spectrum sensing in cognitive radios
, Article IEEE Transactions on Wireless Communications ; Volume 9, Issue 2 , 2010 , Pages 814-823 ; 15361276 (ISSN) ; Nasiri-Kenari, M ; Gazor, S ; Sharif University of Technology
2010
Abstract
In this paper, we consider the problem of spectrum sensing by using multiple antenna in cognitive radios when the noise and the primary user signal are assumed as independent complex zero-mean Gaussian random signals. The optimal multiple antenna spectrum sensing detector needs to know the channel gains, noise variance, and primary user signal variance. In practice some or all of these parameters may be unknown, so we derive the Generalized Likelihood Ratio (GLR) detectors under these circumstances. The proposed GLR detector, in which all the parameters are unknown, is a blind and invariant detector with a low computational complexity. We also analytically compute the missed detection and...
Invariant wideband spectrum sensing under unknown variances
, Article IEEE Transactions on Wireless Communications ; Volume 8, Issue 5 , 2009 , Pages 2182-2186 ; 15361276 (ISSN) ; Gazor, S ; Nasiri Kenari, M ; Sharif University of Technology
2009
Abstract
In this paper, we divide a wide frequency range into multiple subbands and in each subband detect whether in a primary user (PU) is active or not. We assume that PU signal at each subband and the additive noise are white zeromean independent Gaussian random processes with unknown variances. We also assume that at least a minimum given number of subbands is vacant of PU signal and propose an invariant Generalized Likelihood Ratio (GLR) detector. The concept of the grouping of subbands allows faster spectrum sensing of a subset of subbands which may be occupied by a specific PU. Also, we evaluate trade-offs involved in the proposed algorithms by simulation. © 2009 IEEE
Wideband spectrum sensing in unknown white Gaussian noise
, Article IET Communications ; Volume 2, Issue 6 , 2008 , Pages 763-771 ; 17518628 (ISSN) ; Gazor, S ; Nasiri Kenari, M ; Sharif University of Technology
2008
Abstract
The spectrum sensing of a wideband frequency range is studied by dividing it into multiple subbands. It is assumed that in each subband either a primary user (PU) is active or absent in a additive white Gaussian noise environment with an unknown variance. It is also assumed that at least a minimum given number of subbands are vacant of PUs. In this multiple interrelated hypothesis testing problem, the noise variance is estimated and a generalised likelihood ratio detector is proposed to identify possible spectrum holes at a secondary user (SU). Provided that it is known that a specific PU can occupy a subset of subbands simultaneously, a grouping algorithm which allows faster spectrum...
Efficient cooperative spectrum sensing in cognitive radio networks
, Article 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC'07, Athens, 3 September 2007 through 7 September 2007 ; December , 2007 ; 1424411440 (ISBN); 9781424411443 (ISBN) ; Nasiri Kenari, M ; Jamshidi, A ; Sharif University of Technology
2007
Abstract
Rcent measurements suggest the possibility of sharing spectrum among different parties subject to interference-protection constraints. In order to enable access to an unused licensed spectrum, a secondary user has to monitor licensed bands and opportunistically transmit whenever no primary signal is detected. In this paper, we study spectrum-sharing between a primary licensee and a group of secondary users. The structure of an asymptotically optimum detector based on the measurements of all secondary users is derived and the effect of the quantization error in such a system is evaluated. The results show the superiority of the proposed detector to other schemes. © 2007 IEEE
Cooperative Spectrum Sensing Based on Learning Techniques for 5G Mobile Communication Networks
, M.Sc. Thesis Sharif University of Technology ; Behroozi, Hamid (Supervisor)
Abstract
In recent years, with the continuous growth and development of wireless communication systems, the demand for the use of radio spectrum has increased significantly, which has led to problems such as a shortage of spectrum. An effective solution to the spectrum shortage problem is to use cognitive radio. One of the main functions of cognitive radio networks is spectrum sensing and our focus in this study is to examine machine learning and deep learning methods to improve cooperative spectrum sensing. Since channel and noise parameters are not accurate in telecommunication systems, we need to use a method to estimate these parameters. In this regard, the structure of Bayesian with neural...
Effective Implementation of Wide-band Spectrum Sensing
, M.Sc. Thesis Sharif University of Technology ; Shabany, Mahdi (Supervisor) ; Fakharzadeh, Mohammad (Supervisor)
Abstract
Ever increasing demand for higher data rate in wireless communication in the face of limited or underutilized spectral resources has motivated the introduction of cognitive radio for dynamic access to spectrum. In dynamic spectrum access a new type of users called secondary users measure the spectrum to see if it is occupied by licensed users (primary users or PU). When channel is empty secondary users can use it to transmit signal. This approach is called spectrum sensing. Hidden PU problem can severely defect detection ability of non-cooperativ spectrum sensing systems. Cooperative spectrum sensing (CSS) uses spatial diversity of spectrum sensors to tackle this problem. There are two kinds...