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    Target direct position determination in 2D CW forward scatter radar

    , Article Proceedings International Radar Symposium, 10 May 2016 through 12 May 2016 ; Volume 2016-June , 2016 ; 21555753 (ISSN) ; 9781509025183 (ISBN) Hamdollahzadeh, M ; Adelipour, S ; Behnia, F ; Nayebi, M. M ; Sharif University of Technology
    IEEE Computer Society  2016
    Abstract
    This paper proposes an algebraic solution for the position and velocity of a moving target in forward scatter radar based on a single step direct position determination method. Unlike the conventional two-step method, this direct technique does not require the joint estimation of the Doppler frequency and the angle of arrival, initialization step, convergence considerations and linearization approximations  

    Performance Improvement in Direct Position Determination of Radio Transmitters

    , Ph.D. Dissertation Sharif University of Technology Hamdollahzadeh, Mohammad (Author) ; Behnia, Fereidoon (Supervisor)
    Abstract
    This work is mostly about the analysis of direct position determination (DPD) approach as an emerging approach in source localization. Different aspects of this localization has been considered and some improvement techniques has been addressed. DPD is known as a replacement for the conventional 2-step localization approach in which the location of the target is estimated via the estimation of some interface parameters such as time of arrival, angle of arrival and etc. The main focus of this thesis is on the sensor placement problem in DPD in order to find an optimal configuration for the sensors to achieve the best accuracy in the estimation process. In this regard, the formulas of the... 

    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  2016
    Abstract
    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  

    Optimal sensor configuration for two dimensional source localization based on TDOA/FDOA measurements

    , Article Proceedings International Radar Symposium, 10 May 2016 through 12 May 2016 ; Volume 2016-June , 2016 ; 21555753 (ISSN) ; 9781509025183 (ISBN) Hamdollahzadeh, M ; Adelipour, S ; Behnia, F ; Sharif University of Technology
    IEEE Computer Society  2016
    Abstract
    The Cramer-Rao lower bound for source localization based on Time Difference of Arrival and Frequency Difference of Arrival is investigated in this paper. The result is used for theoretical analysis of optimality in sensor placement. An optimal sensor-target geometry including sensors locations and velocities is presented and its properties is studied  

    Sequential sensor placement in twodimensional passive source localisation using time difference of arrival measurements

    , Article IET Signal Processing ; Volume 12, Issue 3 , 2018 , Pages 310-319 ; 17519675 (ISSN) Hamdollahzadeh, M ; Adelipour, S ; Behnia, F ; Sharif University of Technology
    Institution of Engineering and Technology  2018
    Abstract
    This study presents a new approach to sensor placement strategy in emitter localisation problems based on time difference of arrival measurements. The method addresses a flexible procedure which is capable of positioning the sensors in constrained environments or non-stationary situations where the positions of the sensors are restricted to certain parts of the space and/or need to be changed repeatedly. This method is sequential and has lower computation burden compared to other methods. The validity of the proposed algorithm is assessed by many different numerical scenarios and the results verify its proper operation. © The Institution of Engineering and Technology 2017  

    Optimal sensor placement for multi-source AOA localisation with distance-dependent noise model

    , Article IET Radar, Sonar and Navigation ; Volume 13, Issue 6 , 2019 , Pages 881-891 ; 17518784 (ISSN) Hamdollahzadeh, M ; Amiri, R ; Behnia, F ; Sharif University of Technology
    Institution of Engineering and Technology  2019
    Abstract
    In this study, the optimal sensor placement problem for multi-source angle of arrival localisation is investigated. The authors adopt the A-optimality criterion, maximising the trace of Fisher information matrix, to determine the optimal sensor-target geometry under distance-dependent Gaussian noise model. A recursive representation of the Cramer-Rao lower bound is derived to recast the sensor placement problem into a sequential method, obtaining the optimal sensor geometries in a step by step manner. Note that the state-of-the-art methods are highly sensitive to the source location changes such that they should be relocated by any later changes in target geometries, which is practically... 

    Moving target localization in bistatic forward scatter radars: performance study and efficient estimators

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 56, Issue 2 , 2020 , Pages 1582-1594 Hamdollahzadeh, M ; Amiri, R ; Behnia, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    This paper considers the localization of a moving target using a forward scatter radar consisting of a transmitter and an array antenna receiver. A direct positioning method based on maximum likelihood (ML) estimation is proposed and compared with the conventional two-step method in which the primary parameters, including Doppler shift and angle of arrival, should be determined in the first step. Moreover, closed-form expressions for Cramer-Rao lower bound of both methods are derived. The aforementioned methods are comprehensively compared in terms of positioning accuracy and computational complexity. Theoretical performance study, including determining the minimum required observation time... 

    Optimal sensor placement for multi-source AOA localisation with distance-dependent noise model

    , Article IET Radar, Sonar and Navigation ; Volume 13, Issue 6 , 2019 , Pages 881-891 ; 17518784 (ISSN) Hamdollahzadeh, M ; Amiri, R ; Behnia, F ; Sharif University of Technology
    Institution of Engineering and Technology  2019
    Abstract
    In this study, the optimal sensor placement problem for multi-source angle of arrival localisation is investigated. The authors adopt the A-optimality criterion, maximising the trace of Fisher information matrix, to determine the optimal sensor-target geometry under distance-dependent Gaussian noise model. A recursive representation of the Cramer-Rao lower bound is derived to recast the sensor placement problem into a sequential method, obtaining the optimal sensor geometries in a step by step manner. Note that the state-of-the-art methods are highly sensitive to the source location changes such that they should be relocated by any later changes in target geometries, which is practically... 

    2-D spectral estimation in CW forward scatter radars

    , Article Proceedings International Radar Symposium, 24 June 2015 through 26 June 2015 ; Volume 2015-August , 2015 , Pages 664-669 ; 21555753 (ISSN); 9783954048533 (ISBN); 9783954048533 (ISBN); 9783954048533 (ISBN) Hamdollahzadeh, M ; Bagheri, A. M ; Azarbar, A ; Nayebi, M. M ; Rohling H ; Rohling H ; Rohling H ; Sharif University of Technology
    IEEE Computer Society  2015
    Abstract
    In CW forward scatter radars, Space-Time processing by 2-D FFT is used to estimate Doppler frequency shift and angle of arrival concurrently. 2-D periodogram and 2-D Capon methods are two famous spectral estimation methods which can be substituted for 2-D FFT. Here we will provide analysis of performance for these methods beside their cons and pros  

    Target Detection and Tracking in Forward Scattering Radars

    , M.Sc. Thesis Sharif University of Technology Hamdollahzadeh, Mohammad (Author) ; Nayebi, Mohammad Mahdi (Supervisor)
    Abstract
    Forward scatter radar is a special kind of bistatic radar. It is designed to detect targets near the transmitter-receiver line which is called baseline. It has a number of promising features such as larger target radar cross-section (RCS) than that of traditional radars, applicability of shadow inverse SAR (SISAR) algorithms, high performance in automatic target recognition and identification, and robustness to stealth technology. On the other hand, it also has some inherent limitations, including the absence of range resolution (potentially leading to a high Doppler clutter level) and operation within narrow angles relative to the transmitter-receiver baseline. Target detection in forward... 

    Probability of missed detection as a criterion for receiver placement in MIMO PCL

    , Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) Majd, M. N ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    IEEE  2012
    Abstract
    Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar  

    An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation

    , Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) Ghazanfari, D ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
    2008
    Abstract
    SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity  

    MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak

    , Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) Chitgarha, M. M ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function... 

    Detection-localization tradeoff in MIMO radars

    , Article Radioengineering ; Volume 26, Issue 2 , 2017 , Pages 581-587 ; 12102512 (ISSN) Nazari Majd, M ; Radmard, M ; Chitgarha, M. M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
    2017
    Abstract
    Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance... 

    Antenna placement and power allocation optimization in MIMO detection

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, Issue 2 , April , 2014 , pp. 1468-1478 Radmard, M ; Chitgarha, M. M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive... 

    Ambiguity function of MIMO radar with widely separated antennas

    , Article Proceedings International Radar Symposium ; 16 -18 June , 2014 ; ISSN: 21555753 Radmard, M ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas  

    Choosing the position of the receiver in a MISO passive radar system

    , Article European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 9th European Radar Conference, EuRAD 2012 ; 2012 , Pages 318-321 ; 9782874870293 (ISBN) Chitgarha, M. M ; Majd, M. N ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    2012
    Abstract
    By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only... 

    Adaptive filtering techniques in passive radar

    , Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1067-1078 ; 21555753 (ISSN) ; 9783954042234 (ISBN) Chitgarha, M. M ; Radmard, M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    2013
    Abstract
    One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared  

    Ambiguity function based receiver placement in multi-site radar

    , Article 2016 CIE International Conference on Radar, RADAR 2016, 10 October 2016 through 13 October 2016 ; 2017 ; 9781509048281 (ISBN) Radmard, M ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    2017
    Abstract
    It has been shown that using multiple antennas in a radar system improves the performance considerably, since multiple target echoes are received from different aspect angles of the target. In this way, the target detection is improved. However, when using multiple antennas, some problems, such as designing the transmit signals, synchronization, etc. emerge that should be solved. One of such problems is the receiver placement. Receiver placement deals with choosing a proper position for the receive antenna in order to optimize the whole system's performance. In this paper, a receiver placement procedure based on improving the radar ambiguity function is proposed for the case of a multisite... 

    Improving MIMO radar's performance through receivers' positioning

    , Article IET Signal Processing ; Volume 11, Issue 5 , 2017 , Pages 622-630 ; 17519675 (ISSN) Chitgarha, M. M ; Radmard, M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    Institution of Engineering and Technology  2017
    Abstract
    By employing the MIMO (multiple-input-multiple-output) technology in radar, some new problems emerged, that, in order to benefit the MIMO gains in radar, it was necessary to solve them suitably. One of such obstacles is determining the positions of receive antennas in a MIMO radar system with widely separated antennas (WS MIMO radar), since it is shown that the antennas' positions affect the whole system's performance considerably. In this study, a proper receivers' positioning procedure is proposed. To do this end, four criteria are developed based on the proposed MIMO detector and the MIMO ambiguity function. The simulations verify that the proposed positioning procedure improves the...