Search for: direction-of-arrival
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Total 45 records

    Invariancy of sparse recovery algorithms

    , Article IEEE Transactions on Information Theory ; Volume 63, Issue 6 , 2017 , Pages 3333-3347 ; 00189448 (ISSN) Kharratzadeh, M ; Sharifnassab, A ; Babaie Zadeh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    In this paper, a property for sparse recovery algorithms, called invariancy, is introduced. The significance of invariancy is that the performance of the algorithms with this property is less affected when the sensing (i.e., the dictionary) is ill-conditioned. This is because for this kind of algorithms, there exists implicitly an equivalent well-conditioned problem, which is being solved. Some examples of sparse recovery algorithms will also be considered and it will be shown that some of them, such as SL0, Basis Pursuit (using interior point LP solver), FOCUSS, and hard thresholding algorithms, are invariant, and some others, like Matching Pursuit and SPGL1, are not. Then, as an... 

    A computationally efficient direction-of-arrival estimation algorithm, robust against coherent sources and small sample size

    , Article 2013 21st Iranian Conference on Electrical Engineering, ICEE ; 2013 , 14-16 May ; 9781467356343 (ISBN) Rahmani, M ; Bastani, M. H ; Shahraeeni, S ; Sharif University of Technology
    Direction-of-arrival (DOA) estimation algorithms usually impose high computation burden and most of them are incapable of facing the coherent sources. In this paper, a new computationally efficient algorithm that is robust against the coherent sources is proposed. This method is based on a combination of the Maximum Likelihood (ML) and Orthogonal-Matching-Pursuit (OMP) algorithms. Simulation results show that the proposed algorithm has good performance in the small sample size cases and the coherency does not affect its performance  

    Parameter optimization for bistatic PCL radar

    , Article ITST 2006 - 2006 6th International Conference on ITS Telecommunications, Proceedings, Chengdu, 21 June 2006 through 23 June 2006 ; 2006 , Pages 1256-1258 ; 0780395867 (ISBN); 9780780395862 (ISBN) Emadi, M ; Jafargholi, A ; Mousavi, M ; Bayat, S ; Nayebi, M. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    In this paper the accuracy of measurement with respect to some parameters like baseline variance and DOA estimation and bistatic RCS is considered. The Radar designer can find the appropriate parameters to having the minimum error in target localization and maximum coverage range. © 2006 IEEE  

    The direction of arrival estimation in DS-CDMA systems employing the code-matched filters and parallel ESPRIT algorithms

    , Article Proceedings - 2010 IEEE International Conference on Wireless Communications, Networking and Information Security, WCNIS 2010, 25 June 2010 through 27 June 2010, Beijing ; 2010 , Pages 274-279 ; 9781424458516 (ISBN) Samsami Khodadad, F ; Hoseini Karani, S. B ; Safaei, A ; Hadi Karami Ata, M ; Taheri, A ; Sharif University of Technology
    It was shown that the number of array elements must exceed the number of sources for subspace-based direction-of-arrival (DOA) estimation. But this is not practical for a direct-sequence code-division multiple access (DS-CDMA) wireless system, since the number of mobile users is very large. To remove the aforementioned restriction, a DOA estimator, employing the code-matched filters and parallel ESPRIT algorithms, is proposed. This algorithm does not use to search all angles such as MUSIC method. Besides, it is not necessary to use AIC and MDL criterion to estimate the number of sources in the proposed algorithm. Simulation results illustrates the appropriate performance of the new method  

    Reduction of multi-path effect based on correlation decomposition in a DOA estimation system

    , Article Signal Processing and Intelligent Systems Conference, 16 December 2015 through 17 December 2015 ; 2015 , Pages 10-14 ; 9781509001392 (ISBN) Karimi, P ; Farzaneh, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    The multi-path phenomenon is one of the main causes of error in Direction Of Arrival Estimation systems which are located in a complex environment. The received signal in this environment consists of Line Of Sight (LOS) and multi-path components which are delayed versions of the LOS signal with the amplitude and the phase depending on the path length. In order to eliminate the multi-path signal, it is necessary to estimate the amplitude, the phase, and the delay of the signal. To this end, a method based on correlation which has been already used to estimate amplitudes and delays of Line Of Sight and multi-path signals in GPS systems, is implemented. After this estimation process, a phase... 

    Direction of Arrival Estimation and Digital Beamforming in the Presence of Mutual Coupling Effects and Implementation

    , Ph.D. Dissertation Sharif University of Technology Emadi, Mohammad (Author) ; Haj Sadeghi, Khosrow (Supervisor)
    Different beamforming methods are prevalent in wireless and mobile communication systems. However, a lot of practical issues, such as the quality of these methods in compact arrays and the huge computational burden are the major defects of the proposed methods. These problems restrict most of the algorithms to the theoretical domain and render them anappropriate for commercial applications. Therefore, the major focus of this thesis is on the practical issues in the implementation of the digital beam steering and direction of arrival estimation systems for linear, circular and random array configurations. To do so, compact arrays with super directivity are presented and considered. Different... 

    Implementation of Outdoor Sound Source Localization System Using Sound Sensor Arrays

    , M.Sc. Thesis Sharif University of Technology Fathi, Ehsan (Author) ; Gholampour, Eman (Supervisor) ; Sharif Khani, Mohammad (Supervisor)
    Sound source localization has been one of the fundamental problems in many areas, including radar, teleconferencing or videoconferencing, localization of earthquake epicenters and underground explosions, microphone arrays, robots, etc. All of sound source localization ideas are like human auditory system. The human auditory system is a complex and organic information processing system. It can feel the intensity and spatial orientation and other information of sound. The distance of the two ears on our head is about 20cm. When the sound reaches each ear, there are small time difference, intensity difference and phase difference. After analyzing these differences by the brain, the human can... 

    DOA estimation of multi-reflected known signals in compact arrays

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 49, Issue 3 , 2013 , Pages 1920-1931 ; 00189251 (ISSN) Emadi, M ; Sadeghi, K. H ; Sharif University of Technology
    For direction of arrival (DOA) estimation in compact arrays, a new approach based on time delay and amplitude estimation is presented for a known signal. The DOA can be accurately estimated without any calibration sources since the mutual coupling and multipath effects can be eliminated by the inherent mechanism of the proposed algorithm. The algorithm has significantly lower error and much less computational burden compared with the previous methods in high signal-to-noise ratio (SNR) conditions  

    A new iterative position finding algorithm based on Taylor series expansion

    , Article 2011 19th Iranian Conference on Electrical Engineering, ICEE 2011, 17 May 2011 through 19 May 2011 ; May , 2011 , Page(s): 1 ; 9789644634284 (ISBN) Soltanian, M ; Pezeshk, A. M ; Mahdavi, A ; Dallali, M ; Sharif University of Technology
    This paper deals with the problem of estimating the position of emitters using only direction of arrival information. We propose an improvement of newly developed algorithm for position finding of a stationary emitter called sensitivity analysis. The proposed method uses Taylor series expansion iteratively to enhance the estimation of the emitter location and reduce position finding error. Simulation results show that our proposed method makes a great improvement on accuracy of position finding with respect to sensitivity analysis method  

    Recursive sensor placement in two dimensional TDOA based localization

    , Article 24th Iranian Conference on Electrical Engineering, 10 May 2016 through 12 May 2016 ; 2016 , Pages 300-304 ; 9781467387897 (ISBN) Hamdollahzadeh, M ; Adelipour, S ; Behnia, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    This paper presents a new approach to sensor placement strategy in emitter localization problem which is based on Time Difference of Arrival (TDOA) measurements. The advantage of this method is its flexibility and capability of positioning sensors in constrained or non-stationary situations in which the positions of the sensors are restricted to certain portions of the space and/or needed to be changed repeatedly. The validity of the proposed algorithm is assessed by three different simulation scenarios and the results verify its proper operation  

    A novel solution for root-MUSIC with reduced complexity

    , Article 6th Iranian Conference on Radar and Surveillance Systems, ICRSS 2019, 4 December 2019 through 6 December 2019 ; 2019 ; 9781728129372 (ISBN) Eskandari, M ; Karbasi, S. M ; Bastani, M. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    The root-MUSIC algorithm is a popular method to estimate Angle of Arrival (AoA) as an extension of multiple signal classification (MUSIC). In this paper, we have proposed a novel solution for the root-MUSIC algorithm. The new method exhibits a much lower computational complexity, while maintaining the same theoretical performance as the root-MUSIC. © 2019 IEEE  

    High resolution DOA estimation in fully coherent environments

    , Article Progress In Electromagnetics Research C ; Volume 5 , 2008 , Pages 135-148 ; 19378718 (ISSN) Shahi, S. N ; Emadi, M ; Sadeghi, K ; Sharif University of Technology
    Electromagnetics Academy  2008
    A novel method for direction-of-arrival (DOA) estimation is proposed. This technique employs the excellent performance of Bartlett method in coherent environments as well as high resolution and low computational complexity of Beamspace MUSIC. Simulation results show that the use of Beamspace MUSIC with Bartlett yields significantly improved performance compared to the original MUSIC especially in highly correlated situations. © 2008, Electromagnetics Academy. All rights reserved  

    Bistatic ambiguity function and DOA estimation for PCL radar

    , Article APCCAS 2006 - 2006 IEEE Asia Pacific Conference on Circuits and Systems, 4 December 2006 through 6 December 2006 ; 2006 , Pages 840-843 ; 1424403871 (ISBN); 9781424403875 (ISBN) Sargazi Moghadam, M. H ; Jafargholi, A ; Emadi, M ; Nayebi, M. M ; Sharif University of Technology
    in this paper detection and the accuracy of measurement of range, velocity and DOA in PCL radar for optimized parameters is considered. It is shown that, in order to measure the bistatic characteristics of a target, we can process the monostatic ambiguity function and extract the bistatic factors by proposed Algorithm. ©2006 IEEE  

    Evaluation and Improvement of DOA Estimation Methods in Dipole Antenna Arrays with Different Geometries

    , M.Sc. Thesis Sharif University of Technology Sasannia, Zahra (Author) ; Farzaneh, Forouhar (Supervisor)
    In this thesis, some of the well-known DOA algorithms namely Bartlett, Capon, Linear prediction, Maximum Entropy, Pisarenko harmonic decomposition, Minimum norm and MUSIC are analyzed and compared with each other in the identical situations using a uniform linear array. Then based on these comparisons, the appropriate algorithm is selected. In the next step since the linear arrays can't estimate both angles of arrival (Azimuth and Elevation) simultaneously, two dimensional (2D) geometries are introduced and are also compared to each other. Then one of them (circular array) is selected for dipole antenna arrays. The performance of the selected array is evaluated using isotropic elements for... 

    Direction-of-arrival estimation for temporally correlated narrowband signals

    , Article IEEE Transactions on Signal Processing ; Volume 57, Issue 2 , 2009 , Pages 600-609 ; 1053587X (ISSN) Haddadi, F ; Nayebi, M. M ; Aref, M. R ; Sharif University of Technology
    Signal direction-of-arrival (DOA) estimation using an array of sensors has been the subject of intensive research and development during the last two decades. Efforts have been directed to both, better solutions for the general data model and to develop more realistic models. So far, many authors have assumed the data to be independent and identically distributed (i.i.d.) samples of a multivariate statistical model. Although this assumption reduces the complexity of the model, it may not be true in certain situations where signals show temporal correlation. Some results are available on the temporally correlated signal model in the literature. The temporally correlated stochastic Cramér-Rao... 

    Design of Digital Block of Receiver Section of Smart Antenna System

    , M.Sc. Thesis Sharif University of Technology Naderi Shahi, Sina (Author) ; Haj Sadeghi, Khosro (Supervisor)
    In recent years with the increase of cellular phone subscribers, demand for high capacity networks is inevitable. For this reason, different methods have been proposed to increase the channel capacity. One method which has become popular in recent years is utilizing of Smart Antenna Systems. Smart antennas basically attempt to enhance the desired signal power and suppress the interferers by beamforming toward the DOA (direction-of-arrival) of the desired signal and nullsteering in the interferences’ DOAs. Smart Antennas first find the direction of signal sources, and then put the main gain toward the desired signal and put the nulls toward unwanted signals. As a result, we can obtain the... 

    Designi an Adaptive Beamforming Algorithm, Robust Against Direction-of-Arrival Mismatch

    , M.Sc. Thesis Sharif University of Technology Rahmani, Mostafa (Author) ; Bastani, Mohammad Hasan (Supervisor)
    Adaptive beamforming performance is very sensitive to any mismatch between actual and presumed steering vectors of desired signal. In addition to this sensitivity, presence of desired signal in training snapshots dramatically reduces the convergence rate, as compared to the case that signal-free training snapshots are available.
    The present work is aimed at proposing a new adaptive beamformer that is robust against direction-of-arrival (DOA) mismatch and has high convergence rate. This method is based on desired signal elimination from training snapshots and sub-array beamforming technique. To this end, a Blocking matrix that converts primary data to desired signal free data is... 

    Design and Simulation of Smart Patch Antenna Array in 2.4 GHz band

    , M.Sc. Thesis Sharif University of Technology Hosseini, Mahdi (Author) ; Farzaneh, Forouhar (Supervisor)
    Over the past few years , demand for wireless communication services have grown at a formidable rate. As such we need to find new ways to support more and more wireless users in a confined space. this means that the capacity of networks should be significantly increased to overcome formidable rate of subscribers growth. That is why the smart antennas have become very popular in communication systems. Smart antennas are a kind of adaptive antenna arrays with smart signal processing algorithms used to find direction of arrival(DOA) of the signal, and use it to calculate suitable weights to direct the antenna beam on the desired user and nulling interferences. In this thesis, DOA estimation... 

    Online Compensation of Unknown Mutual Coupling Effect in 2-Dimensional Arrival Angle Estimation

    , M.Sc. Thesis Sharif University of Technology Bahrololoom, Ebrahim (Author) ; Nayebi, Mohammad Mehdi (Supervisor)
    In the recent decades, the estimation of direction of arrival has been an active area and some high resolution direction finding methods like MUSIC and ESPIRIT have been developed. These methods suffer from factors like mutual coupling. Direction of arrival estimation in presence of mutual coupling is a widely studied problem. In order to resolve this problem, many array calibration algorithms have been developed. However it may be impossible or difficult to set some calibration source in some situation. In this work we show that the effect of mutual coupling can be dynamically compensated by the inherent mechanism. First we show that how mutual coupling can degrades the performance of... 

    Beamforming and DOA Estimation Using Compressive Sensing and Random Sampling

    , M.Sc. Thesis Sharif University of Technology Zamani, Hojatollah (Author) ; Marvasti, Farrokh (Supervisor)
    Direction Of Arrival (DOA) estimation or direction finding refers to determining the arrival angle of a planar wave impinging on the array of sensors or antennas. The DOA information can be used by the smart antenna system for beam-forming and reliable data transmission. The problem of DOA estimation in propagating plane waves played a fundamental role in many applications including acoustic, wireless communication systems, navigation, biomedical imaging, radar/sonar systems, seismic sensing, and wireless 911 emergency call locating. In the conventional DOA estimating systems, an array of elements (antennas or sensors) is used that are colocated in a uniform pattern called, Uniform Linear...