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maximum-likelihood-estimation
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DOA Estimation in Communication Systems Using Deep Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Behrouzi, Hamid (Supervisor) ; Karbasi, Mohammad (Supervisor)
Abstract
The purpose of Direction-of-arrival(DOA) estimation in MIMO communication networks is to find the direction of signals that are mixed together and mixed with noise by using an array of multiple receiving antennas. DOA estimation is an important issue in array signal processing. The traditional methods for DOA estimation try to solve this problem with mathematical algorithms. For example, some of these methods are based on parameter estimation; such as DOA estimation methods using maximum likelihood estimation methods. Some of other traditional methods are based on subspace decomposition; Like the famous MUSIC method. The traditional methods of DOA estimation usually have a drawback, and that...
A probabilistic artificial neural network-based procedure for variance change point estimation
, Article Soft Computing ; Vol. 19, issue. 3 , May , 2014 , pp. 691-700 ; ISSN: 14327643 ; Niaki, S. T. A ; Moghadam, A. T ; Sharif University of Technology
Abstract
Control charts are useful tools of monitoring quality characteristics. One of the problems of employing a control chart is that the time it alarms is not synchronic with the time when assignable cause manifests itself in the process. This makes difficult to search and find assignable causes. Knowing the real time of manifestation of assignable cause (change point) helps to find assignable cause(s) sooner and eases corrective actions to be taken. In this paper, a probabilistic neural network (PNN)-based procedure was developed to estimate the variance change point of a normally distributed quality characteristic. The PNN was selected based on trial and error among different types of...
Comprehensive study of non-uniform circular array interferometer in a real time broadband 3-dimensional direction finder (2-12GHZ)
, Article Progress In Electromagnetics Research C ; Volume 24 , 2011 , Pages 69-81 ; 19378718 (ISSN) ; Soltanian, M ; Salarpour, M ; Pezeshk, A. M ; Sharif University of Technology
2011
Abstract
A comprehensive study is performed to investigate the performance of a non-uniform circular array interferometer in a real time 3-dimensional direction finder. The angular range of view is supposed to be 65 degrees vertically and 120 degrees horizontally, which is suitable for airborne applications. Interferometer is designed to work in the S, C and X bands. Regarding optimization process, the interferometer employs an eight element non-uniform circular array along with a phase reference antenna at the center of the array. Several quantities and parameters are studied, e.g., frequency behavior, origins of phase measurement errors, Signal to Noise Ratio (SNR) effect on phase measurement, and...
Performance of three-level spectrally encoded spread-time CDMA in the presence of multiple interferences
, Article IET Communications ; Volume 5, Issue 10 , 2011 , Pages 1328-1335 ; 17518628 (ISSN) ; Salehi, J. A ; Sharif University of Technology
2011
Abstract
In this study the authors present an in-depth study, analysis and discussion on maximum likelihood (ML)-based receiver for a typical spectrally encoded spread-time CDMA in the presence of multiple narrowband interference (NBI) signals in an additive white Gaussian noise channel. Furthermore, the authors demonstrate that by combining useful properties of ML-based receiver and three-level codes, that is, codes with values of -1, 0, +1, the authors can introduce a new strategy in which superior performance with respect to previous receiver structure based on two-level codes, that is, codes with values of -1, +1, can be attained. With the help of an example, the authors drive, first, the...
A novel Space Time Diversity Generalized Decorrelating Rake receive for multipath downlink DS-CDMA systems
, Article 2011 IEEE GCC Conference and Exhibition, GCC 2011, 19 February 2011 through 22 February 2011, Dubai ; 2011 , Pages 417-420 ; 9781612841199 (ISBN) ; Hosaini, S. N ; Khodadad, F. S ; Baghbanmanesh, M. R ; Sharif University of Technology
2011
Abstract
In this paper a novel Space Time Diversity Generalized Decorrelating Discrete Time Rake (STD-GD-DTR) for Upstream DS-CDMA system is proposed. The chosen algorithm for estimating the correct data is Maximum likelihood. In this method, a robust receiver based on maximum likelihood estimation is represented in which, space time diversity technique has been combined with generalized decorrelating discrete-time RAKE (GD-DTR) receiver to obtain higher performance than other widely used techniques for data estimation. Our proposed STD-GD-DTR ML based receiver provides high gains in the presence of channel estimation errors from similar methods. Simulation results illustrate the appropriate...
Soft context clustering for F0 modeling in HMM-based speech synthesis
, Article Eurasip Journal on Advances in Signal Processing ; Volume 2015, Issue 1 , January , 2015 ; 16876172 (ISSN) ; Sameti, H ; King, S ; Sharif University of Technology
Springer International Publishing
2015
Abstract
This paper proposes the use of a new binary decision tree, which we call a soft decision tree, to improve generalization performance compared to the conventional ‘hard’ decision tree method that is used to cluster context-dependent model parameters in statistical parametric speech synthesis. We apply the method to improve the modeling of fundamental frequency, which is an important factor in synthesizing natural-sounding high-quality speech. Conventionally, hard decision tree-clustered hidden Markov models (HMMs) are used, in which each model parameter is assigned to a single leaf node. However, this ‘divide-and-conquer’ approach leads to data sparsity, with the consequence that it suffers...
A neural network applied to estimate Burr XII distribution parameters
, Article Reliability Engineering and System Safety ; Volume 95, Issue 6 , June , 2010 , Pages 647-654 ; 09518320 (ISSN) ; Hosseinifard, S. Z ; Coit, D. W ; Sharif University of Technology
2010
Abstract
The Burr XII distribution can closely approximate many other well-known probability density functions such as the normal, gamma, lognormal, exponential distributions as well as Pearson type I, II, V, VII, IX, X, XII families of distributions. Considering a wide range of shape and scale parameters of the Burr XII distribution, it can have an important role in reliability modeling, risk analysis and process capability estimation. However, estimating parameters of the Burr XII distribution can be a complicated task and the use of conventional methods such as maximum likelihood estimation (MLE) and moment method (MM) is not straightforward. Some tables to estimate Burr XII parameters have been...
Compressive sensing for elliptic localization in MIMO radars
, Article 24th Iranian Conference on Electrical Engineering, 10 May 2016 through 12 May 2016 ; 2016 , Pages 525-528 ; 9781467387897 (ISBN) ; Amiri, R ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
In this paper, a sparsity-aware target localization method in multiple-input-multiple-output (MIMO) radars by utilizing time difference of arrival (TDOA) measurements is proposed. This method provides a maximum likelihood (ML) estimator for target position by employing compressive sensing techniques. Also, for fast convergence and mitigating the mismatch problem due to grid discretization, we address a block-based search coupled with an adaptive dictionary learning technique. The Cramer-Rao lower bound for this model is derived as a benchmark. Simulations results are included to verify the localization performance
Coupled hidden markov model-based method for apnea bradycardia detection
, Article IEEE Journal of Biomedical and Health Informatics ; Volume 20, Issue 2 , 2016 , Pages 527-538 ; 21682194 (ISSN) ; Masoudi, S ; Shamsollahi, M. B ; Beuchée, A ; Pladys, P ; Ge, D ; Hernández, A. I ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
In this paper, we present a novel framework for the coupled hidden Markov model (CHMM), based on the forward and backward recursions and conditional probabilities, given a multidimensional observation. In the proposed framework, the interdependencies of states networks are modeled with Markovian-like transition laws that influence the evolution of hidden states in all channels. Moreover, an offline inference approach by maximum likelihood estimation is proposed for the learning procedure of model parameters. To evaluate its performance, we first apply the CHMM model to classify and detect disturbances using synthetic data generated by the FitzHugh-Nagumo model. The average sensitivity and...
Binary state reliability computation for a complex system based on extended bernoulli trials: multiple autonomous robots
, Article Quality and Reliability Engineering International ; Volume 33, Issue 8 , 2017 , Pages 1709-1718 ; 07488017 (ISSN) ; Akhavan Niaki, S. T ; Sharif University of Technology
Abstract
Availability of a system is a crucial factor for planning and optimization. The concept is more challenging for modern systems such as robots and autonomous systems consisting of a complex configuration of components. In this paper, a reliability evaluation framework is developed for a system of binary state autonomous robots in an automated manufacturing environment. In this framework, the concepts in functional block diagram, table of truth, and sum of state are employed simultaneously to develop a binary state reliability model. Due to inefficacy of the method for larger number of components involved in complex systems, an extension of the Bernoulli trials is proposed. In an...
Exact solution for elliptic localization in distributed MIMO radar systems
, Article IEEE Transactions on Vehicular Technology ; Volume 67, Issue 2 , February , 2018 , Pages 1075-1086 ; 00189545 (ISSN) ; Behnia, F ; Maleki Sadr, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Elliptic localization is a range-based positioning technique exploiting multiple transmitter-receiver pairs, each of which provides separate bistatic range (BR) measurements. In this paper, a novel computationally efficient solution for locating a single target from BR measurements in distributed MIMO radar systems is proposed. Due to nonconvex nature of the associated maximum likelihood (ML) estimation problem, its globally optimal solution is difficult to obtain. We first reformulate the ML estimation as a nonconvex constrained weighted least squares problem. Owing to special structure of the resulting problem, it is recast as a convex problem, whose exact solution can be obtained in...
Distribution independent blindwatermarking
, Article Proceedings - International Conference on Image Processing, ICIP, 7 November 2009 through 10 November 2009, Cairo ; 2009 , Pages 125-128 ; 15224880 (ISSN); 9781424456543 (ISBN) ; Akhaee, M. A ; Marvasti, F ; IEEE Signal Processing Society; The Institute of Electrical and Electronics Engineers ; Sharif University of Technology
IEEE Computer Society
2009
Abstract
In this paper, a new blind scaling based watermarking approach is presented. The host signal is assumed to be stationary Gaussian with first-order autoregressive model. Partitioning the host signal into two separate parts, the data is embedded in one part and the other is kept unchanged for blind parameter estimation. Driving the distribution of the decision variable we have suggested a maximum likelihood decoding algorithm which is independent of the host signal distribution and can be applied for any transform domains. The proposed algorithm is applied to both artificial Gaussian autoregressive signals as well as various test images. Experimental results confirm the independence of the...
Invariant activity detection of a constant magnitude signal with unknown parameters in white Gaussian noise
, Article IET Communications ; Volume 3, Issue 8 , 2009 , Pages 1420-1431 ; 17518628 (ISSN) ; Tadaion, A. A ; Gazor, S ; Nayebi, M. M ; Sharif University of Technology
2009
Abstract
The authors propose invariant tests for the detection of a complex signal with unknown constant amplitude and unknown phase variation in additive white Gaussian noise (AWGN). The authors show that in this problem, the uniformly most powerful invariant (UMPI) detector does exist only if the number of samples N is two. For more than two samples N≥3, the authors derive the most powerful invariant (MPI) detector in known signal-to-noise ratio (SNR) and use its performance as the upper bound benchmark for any invariant test. In addition, the authors derive the generalised likelihood ratio (GLR) detector and evaluate its performance against the MPI performance bound. This detector is very simple...
Joint compensation of jitter noise and time-shift errors in multichannel sampling system
, Article IEEE Transactions on Instrumentation and Measurement ; Volume 68, Issue 10 , 2019 , Pages 3932-3941 ; 00189456 (ISSN) ; Akhaee, M. A ; Amini, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In high-speed analog-To-digital converters (ADCs), two main factors contribute to high power consumption. The first is the super linear relationship with the sampling rate; i.e., by doubling the sampling rate, the power consumption more than doubles. The second factor arises from the consumption of analog circuitry responsible to mitigate the jitter noise. By employing a multichannel sampling system, one can achieve high sampling rates by incorporating multiple low sampling-rate channels, which results in a linear scaling of power consumption with the number of channels. The main drawback of this system is the timing mismatch between the sampling channels. In this paper, we intend to jointly...
Dandelion: A unified code offloading system for wearable computing
, Article IEEE Transactions on Mobile Computing ; Volume 18, Issue 3 , 2019 , Pages 546-559 ; 15361233 (ISSN) ; Yang, J ; Huang, Z ; Movaghar, A ; Hui, P ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Execution speed seriously bothers application developers and users for wearable devices such as Google Glass. Intensive applications like 3D games suffer from significant delays when CPU is busy. Energy is another concern when the devices are in low battery level, but users need them for urgency use. To ease such pains, one approach is to expand the computational power by cloud offloading. This paradigm works well when the available Internet access has enough bandwidth. Another way is to leverage nearby devices for computation-offloading, which is known as device-to-device (D2D) offloading. In this paper, we present Dandelion, a unified code offloading system for wearable computing. Such...
An approximate ml estimator for moving target localization in distributed mimo radars
, Article IEEE Signal Processing Letters ; Volume 27 , 2020 , Pages 1595-1599 ; Amiri, R ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
This letter deals with the problem of moving target localization in distributed multiple-input multiple-output (MIMO) radar systems using time delay (TD) and Doppler shift (DS) measurements. The proposed solution to this problem consists of two stages. In the first stage, an initial estimation of target location is obtained by solving the formulated maximum likelihood (ML) problem based on the TD measurements. In the second stage, by recognizing the obtained position estimate in the previous stage as a priori data and exploiting the DS measurements, another ML problem is formulated, which is efficiently solved via a tractable numerical method to produce a simultaneous estimation of target...
Estimating the four parameters of the Burr III distribution using a hybrid method of variable neighborhood search and iterated local search algorithms
, Article Applied Mathematics and Computation ; Volume 218, Issue 19 , 2012 , Pages 9664-9675 ; 00963003 (ISSN) ; Abbasi, B ; Niaki, S. T. A ; Abdi, M ; Sharif University of Technology
2012
Abstract
The Burr III distribution properly approximates many familiar distributions such as Normal, Lognormal, Gamma, Weibull, and Exponential distributions. It plays an important role in reliability engineering, statistical quality control, and risk analysis models. The Burr III distribution has four parameters known as location, scale, and two shape parameters. The estimation process of these parameters is controversial. Although the maximum likelihood estimation (MLE) is understood as a straightforward method in parameters estimation, using MLE to estimate the Burr III parameters leads to maximize a complicated function with four unknown variables, where using a conventional optimization such as...
Design and Implementation of Time and Frequency Synchronization in LTE
, Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 23, Issue 12 , January , 2015 , Pages 2970-2982 ; 10638210 (ISSN) ; Shabany, M ; Nezamalhosseini, A ; Gulak, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A novel architecture for efficient time and frequency synchronization, applied to the long-term evolution (LTE) standard, is proposed. For symbol timing, we propose applying a symbol-folding method on top of the sign-bit reduction technique, leading to a novel algorithm for the cyclic prefix-type recognition in LTE. Following the symbol timing, the fractional carrier frequency offset is estimated and compensated using an adaptive gain loop, which allows for a high-accuracy compensation in a short interval. In the frequency domain, for cell search, we propose a sign-bit reduction technique on top of the matched filter method for the primary synchronization signal detection. In addition, we...
Efficient convex solution for 3-D localization in MIMO radars using delay and angle measurements
, Article IEEE Communications Letters ; Volume 23, Issue 12 , 2019 , Pages 2219-2223 ; 10897798 (ISSN) ; Amiri, R ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this letter, an efficient estimator for 3-D target localization in distributed multiple-input multiple-output (MIMO) radars using time delay (TD) and angle of arrival (AOA) measurements is proposed. First, an approximately equivalent maximum likelihood (ML) estimation problem is formulated. Then, the aforementioned ML problem is recast into a convex optimization problem for which we derive a semi closed-form solution that eventually boils down to finding the roots of certain polynomials. Using numerical simulations, we demonstrate that the proposed estimator reaches the Cramer-Rao lower bound (CRLB) up to relatively high Gaussian measurement noise levels. Furthermore, the proposed method...
Efficient joint moving target and antenna localization in distributed MIMO radars
, Article IEEE Transactions on Wireless Communications ; Volume 18, Issue 9 , 2019 , Pages 4425-4435 ; 15361276 (ISSN) ; Behnia, F ; Noroozi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, a novel solution for the problem of joint moving target and antenna localization in the distributed multiple-input multiple-output (MIMO) radar systems is proposed. The localization problem in the presence of antenna location uncertainty is formulated as a maximum likelihood (ML) estimation problem, which is then recast into convex form by defining some auxiliary variables and applying semidefinite relation (SDR) technique. Next, an algebraic closed-form estimator is proposed to jointly estimate the target and the antennas error terms and refine their uncertain values. The proposed method is shown analytically and verified by the numerical simulations to be an efficient...