| 1. |
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| 2. |
- Dai, Liang, et al.
(author)
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On the randomized Kaczmarz algorithm
- 2014
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In: IEEE Signal Processing Letters. - 1070-9908 .- 1558-2361. ; 21:3, s. 330-333
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Journal article (peer-reviewed)
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Naghsh, Mohammad Mahdi, et al.
(author)
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A Doppler robust design of transmit sequence and receive filter in the presence of signal-dependent interference
- 2014
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 62:4, s. 772-785
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Journal article (peer-reviewed)abstract
- In this paper, we study the joint design of Doppler robust transmit sequence and receive filter to improve the performance of an active sensing system dealing with signal-dependent interference. The signal-to-noise-plus-interference (SINR) of the filter output is considered as the performance measure of the system. The design problem is cast as a max-min optimization problem to robustify the system SINR with respect to the unknown Doppler shifts of the targets. To tackle the design problem, which belongs to a class of NP-hard problems, we devise a novel method (which we call DESIDE) to obtain optimized pairs of transmit sequence and receive filter sharing the desired robustness property. The proposed method is based on a cyclic maximization of SINR expressions with relaxed rank-one constraints, and is followed by a novel synthesis stage. We devise synthesis algorithms to obtain high quality pairs of transmit sequence and receive filter that well approximate the behavior of the optimal SINR (of the relaxed problem) with respect to target Doppler shift. Several numerical examples are provided to analyze the performance obtained by DESIDE.
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| 8. |
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| 9. |
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| 10. |
- Naghsh, Mohammad Mahdi, et al.
(author)
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Radar Code Design for Detection of Moving Targets
- 2014
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In: IEEE Transactions on Aerospace and Electronic Systems. - 0018-9251 .- 1557-9603. ; 50:4, s. 2762-2778
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Journal article (peer-reviewed)abstract
- In this paper, we study the problem of pulsed-radar transmit code design for detection of moving targets in the presence of signal-dependent clutter. For unknown target Doppler shift, the optimal detector does not lead to a closed-form expression. Therefore, we resort to average and worst case performance metrics of the optimal detector for code design. We propose several algorithms under two novel frameworks to solve highly nonconvex design problems. We also consider low peak-to-average-power ratio (PAR) code design.
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| 11. |
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| 12. |
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| 13. |
- Naghsh, Mohammad Mahdi, et al.
(author)
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Unified Optimization Framework for Multi-Static Radar Code Design using Information-Theoretic Criteria
- 2013
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 61:21, s. 5401-5416
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Journal article (peer-reviewed)abstract
- In this paper, we study the problem of code design to improve the detection performance of multi-static radar in the presence of clutter (i.e., a signal-dependent interference). To this end, we briefly present a discrete-time formulation of the problem as well as the optimal detector in the presence of Gaussian clutter. Due to the lack of analytical expression for receiver operation characteristic (ROC), code design based on ROC is not feasible. Therefore, we consider several popular information-theoretic criteria including Bhattacharyya distance, Kullback-Leibler (KL) divergence, J-divergence, andmutual information (MI) as design metrics. The codeoptimization problems associated with different information-theoretic criteria are obtained and cast under a unified framework. We propose two general methods based on Majorization-Minimization to tackle the optimization problems in the framework. The first method provides optimal solutions via successive majorizations whereas the second one consists of a majorization step, a relaxation, and a synthesis stage. Moreover, derivations of the proposed methods are extended to tackle the code design problems with a peak-to-average ratio power (PAR) constraint. Usingnumerical investigations, a general analysis of the coded system performance, computational efficiency of the proposed methods, and the behavior of the information-theoretic criteria is provided.
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| 14. |
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| 15. |
- Sedighi, Saeid, et al.
(author)
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DoA Estimation Using Low-Resolution Multi-Bit Sparse Array Measurements
- 2021
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In: IEEE Signal Processing Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1070-9908 .- 1558-2361. ; 28, s. 1400-1404
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Journal article (peer-reviewed)abstract
- This letter studies the problem of Direction of Arrival (DoA) estimation from low-resolution few-bit quantized data collected by Sparse Linear Array (SLA). In such cases, contrary to the one-bit quantization case, the well known arcsine law cannot be employed to estimate the covaraince matrix of unquantized array data. Instead, we develop a novel optimization-based framework for retrieving the covaraince matrix of unquantized array data from low-resolution few-bit measurements. The MUSIC algorithm is then applied to an augmented version of the recovered covariance matrix to find the source DoAs. The simulation results show that increasing the sampling resolution to 2 or 4 bits per samples could significantly increase the DoA estimation performance compared to the one-bit sampling regime while the power consumption and implementation costs is still much lower in comparison to the high-resolution sampling implementations.
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| 16. |
- Sedighi, Saeid, et al.
(author)
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On the Performance of One-Bit DoA Estimation via Sparse Linear Arrays
- 2021
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In: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X .- 1941-0476. ; 69, s. 6165-6182
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Journal article (peer-reviewed)abstract
- Direction of Arrival (DoA) estimation using Sparse Linear Arrays (SLAs) has recently gained considerable attention in array processing thanks to their capability to provide enhanced degrees of freedom in resolving uncorrelated source signals. Additionally, deployment of one-bit Analog-to-Digital Converters (ADCs) has emerged as an important topic in array processing, as it offers both a low-cost and a low-complexity implementation. In this paper, we study the problem of DoA estimation from one-bit measurements received by an SLA. Specifically, we first investigate the identifiability conditions for the DoA estimation problem from one-bit SLA data and establish an equivalency with the case when DoAs are estimated from infinite-bit unquantized measurements. Towards determining the performance limits of DoA estimation from one-bit quantized data, we derive a pessimistic approximation of the corresponding Cramér-Rao Bound (CRB). This pessimistic CRB is then used as a benchmark for assessing the performance of one-bit DoA estimators. We also propose a new algorithm for estimating DoAs from one-bit quantized data. We investigate the analytical performance of the proposed method through deriving a closed-form expression for the covariance matrix of the asymptotic distribution of the DoA estimation errors and show that it outperforms the existing algorithms in the literature. Numerical simulations are provided to validate the analytical derivations and corroborate the resulting performance improvement.
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| 17. |
- Soltanalian, Mojtaba, et al.
(author)
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A fast algorithm for designing complementary sets of sequences
- 2013
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In: Signal Processing. - : Elsevier BV. - 0165-1684 .- 1872-7557. ; 93:7, s. 2096-2102
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Journal article (peer-reviewed)abstract
- In this paper, we introduce a fast computational frequency-domain approach for designing complementary sets of sequences. Following the basic idea of CAN-based algorithms, we propose an extension of the CAN algorithm to complementary sets of sequences (which we call CANARY). Moreover, modified versions of the proposed algorithm are derived to tackle the complementary set design problems in which low peak-to-average-power ratio (PAR), unimodular or phase-quantized sequences are of interest. Several numerical examples are provided to show the performance of CANARY.
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| 18. |
- Soltanalian, Mojtaba, et al.
(author)
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A Recursive Method for Enumeration of Costas Arrays
- 2014
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Reports (other academic/artistic)abstract
- In this paper, we propose a recursive method for finding Costas arrays that relies on a particular formation of Costas arrays from similar patterns of smaller size. By using such an idea, the proposed algorithm is able to dramatically reduce the computational burden (when compared to the exhaustive search), and at the same time, still can find all possible Costas arrays of given size. Similar to exhaustive search, the proposed method can be conveniently implemented in parallel computing. The efficiency of the method is discussed based on theoretical and numerical results.
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| 19. |
- Soltanalian, Mojtaba, et al.
(author)
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Approaching peak correlation bounds via alternating projections
- 2014
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In: Proc. 39th International Conference on Acoustics, Speech, and Signal Processing. - Piscataway, NJ : IEEE. - 9781479928934 ; , s. 5317-5321
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Conference paper (peer-reviewed)abstract
- In this paper, we study the problem of approaching peak periodic or aperiodic correlation bounds for complex-valued sets of sequences. In particular, novel algorithms based on alternating projections are devised to approach a given peak periodic or aperiodic correlation bound. Several numerical examples are presented to assess the tightness of the known correlation bounds as well as to illustrate the effectiveness of the proposed methods for meeting these bounds.
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| 20. |
- Soltanalian, Mojtaba, et al.
(author)
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Computational Design of Sequences With Good Correlation Properties
- 2012
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 60:5, s. 2180-2193
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Journal article (peer-reviewed)abstract
- In this paper, we introduce a computational framework based on an iterative twisted approximation (ITROX) and a set of associated algorithms for various sequence design problems. The proposed computational framework can be used to obtain sequences (or complementary sets of sequences) possessing good periodic or aperiodic correlation properties and, in an extended form, to construct zero (or low) correlation zone sequences. Furthermore, as constrained (e. g., finite) alphabets are of interest in many applications, we introduce a modified version of our general framework that can be useful in these cases. Several applications of ITROX are studied and numerical examples (focusing on the construction of real-valued and binary sequences) are provided to illustrate the performance of ITROX for each application.
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| 21. |
- Soltanalian, Mojtaba, et al.
(author)
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Design of perfect phase-quantized sequences with low peak-to-average-power ratio
- 2012
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In: Proc. 20th European Signal Processing Conference. - 9781467310680 ; , s. 2576-2580
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Conference paper (peer-reviewed)abstract
- Perfect phase-quantized unimodular sequences with entries in {x ∊ C | xm = 1} have optimalpeak-to-average-power ratio (PAR); however, they are extremely rare. For active sensing or communication systems which are able to tolerate sub-optimal PAR values, we show how to construct phase-quantizedsequences possessing both virtually perfect periodic autocorrelation and low PAR. Numerical examples are provided to illustrate the performance of the proposed methods.
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| 22. |
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| 23. |
- Soltanalian, Mojtaba, et al.
(author)
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Designing unimodular codes via quadratic optimization
- 2014
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 62:5, s. 1221-1234
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Journal article (peer-reviewed)abstract
- The NP-hard problem of optimizing a quadratic form over the unimodular vector set arises in radar code design scenarios as well as other active sensing and communication applications. To tackle this problem (which we call unimodular quadratic program (UQP)), several computational approaches are devised and studied. Power method-like iterations are introduced for local optimization of UQP. Furthermore, a monotonically error-bound improving technique (MERIT) is proposed to obtain the global optimum or a local optimum of UQP with good sub-optimality guarantees. The provided sub-optimality guarantees are case-dependent and may outperform the pi/4 approximation guarantee of semi-definite relaxation. Several numerical examples are presented to illustrate the performance of the proposed method. The examples show that for several cases, including rank-deficient matrices, the proposed methods can solve UQPs efficiently in the sense of sub-optimality guarantee and computational time.
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| 24. |
- Soltanalian, Mojtaba, et al.
(author)
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Joint design of the receive filter and transmit sequence for active sensing
- 2013
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In: IEEE Signal Processing Letters. - 1070-9908 .- 1558-2361. ; 20:5, s. 423-426
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Journal article (peer-reviewed)abstract
- Due to its long-standing importance, the problem of designing the receive filter and transmit sequence for clutter/interference rejection in active sensing has been studied widely in the last decades. In this letter, we propose a cyclic optimization of the transmit sequence and the receive filter. The proposed approach can handle arbitrary peak-to-average-power ratio (PAR) constraints on the transmit sequence, and can be used for large dimension designs (with variables) even on an ordinary PC.
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| 25. |
- Soltanalian, Mojtaba, et al.
(author)
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MERIT : A monotonically error-bound improving technique for unimodular quadratic programming
- 2014
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In: Proc. 39th International Conference on Acoustics, Speech, and Signal Processing. - Piscataway, NJ : IEEE. - 9781479928934 ; , s. 5656-5660
-
Conference paper (peer-reviewed)abstract
- The NP-hard problem of optimizing a quadratic form over the unimodular vector set arises in radar code design scenarios as well as other active sensing and communication applications. To tackle this problem, a monotonically error-bound improving technique (MERIT) is proposed to obtain the global optimum or a local optimum of UQP with good sub-optimality guarantees. The provided sub-optimality guarantees are case-dependent and may outperform the pi/4 approximation guarantee of semi-definite relaxation.
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| 26. |
- Soltanalian, Mojtaba, et al.
(author)
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On meeting the peak correlation bounds
- 2014
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 62:5, s. 1210-1220
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Journal article (peer-reviewed)abstract
- In this paper, we study the problem of meeting peak periodic or aperiodic correlation bounds for complex-valued sets of sequences. To this end, the Welch, Levenstein, and Exponential bounds on the peak inner-product of sequence sets are considered and used to provide compound peak correlation bounds in both periodic and aperiodic cases. The peak aperiodic correlation bound is further improved by using the intrinsic dimension deficiencies associated with its formulation. In comparison to the compound bound, the new aperiodic bound contributes an improvement of more than 35% for some specific values of the sequence length n and set cardinality m. We study the tightness of the provided bounds by using both analytical and computational tools. In particular, novel algorithms based on alternating projections are devised to approach a given peak periodic or aperiodic correlation bound. Several numerical examples are presented to assess the tightness of the provided correlation bounds as well as to illustrate the effectiveness of the proposed methods for meeting these bounds.
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| 27. |
- Soltanalian, Mojtaba, et al.
(author)
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On Prime Root-of-Unity Sequences with Perfect Periodic Correlation
- 2014
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In: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 62:20, s. 5458-5470
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Journal article (peer-reviewed)abstract
- In this paper, Perfect Root-of-Unity Sequences (PRUS) with entries in $\alpha_p = \{ x \in \complexC ~ |~ x^p =1\}$ (where $p$ is a prime) are studied. A lower bound on the number of distinct phases that are used in PRUS over $\alpha_p$ is derived. We show that PRUS of length $L \geq p(p-1)$ must use all phases in $\alpha_p$. Certain conditions on the lengths of PRUS are derived. Showing that the phase values of PRUS must follow a given difference multiset property, we derive a set of equations (which we call the principal equations) that give possible lengths of a PRUS over $\alpha_p$ together with their phase distributions. The usefulness of the principal equations is discussed, and guidelines for efficient construction of PRUS are provided. Through numerical results, also contributions are made to the current state-of-knowledge regarding the existence of PRUS. In particular, a combination of the developed ideas allowed us to numerically settle the problem of existence of PRUS with $(L,p)=(28,7)$ within about two weeks--- a problem whose solution (without using the ideas in this paper) would likely take more than three million years on a standard PC.
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| 28. |
- Soltanalian, Mojtaba, et al.
(author)
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Perfect root-of-unity codes with prime-size alphabet
- 2011
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In: ICASSP2011, the 36th International Conference on Acoustics, Speech and Signal Processing, Prague, Czech Republic. - 9781457705397 ; , s. 3136-3139-
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Conference paper (peer-reviewed)abstract
- In this paper, Perfect Root-of-Unity Codes (PRUCs) with entries in alpha(p) = {x is an element of C | x(p) = 1} where p is a prime are studied. A lower bound on the number of distinct phases in PRUCs over alpha(p) is derived. We show that PRUCs of length L >= p(p - 1) must use all phases in alpha(p). It is also shown that if there exists a PRUC of length L over alpha(p) then p divides L. We derive equations (which we call principal equations) that give possible lengths of a PRUC over alpha(p) together with their phase distribution. Using these equations, we prove for example that the length of a 3-phase perfect code must be of the form L = 1/4 (9h(1)(2) + 3h(2)(2)) for (h(1), h(2)) is an element of Z(2) and we also give the exact number of occurences of each element from alpha(3) in the code. Finally, all possible lengths (<= 100) of PRUCs over alpha(5) and alpha(7) together with their phase distributions are provided.
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| 29. |
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| 30. |
- Soltanalian, Mojtaba
(author)
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Signal Design for Active Sensing and Communications
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Man-made active sensing systems such as active radar and sonar have been a vital part of our civilization's advancement in navigation, defense, meteorology, and space exploration. Modern active sensing systems rely heavily on the significant progress in the science and technology of communications made within the last century. Not surprising, the fast growing communications technology has changed each and every aspect of our everyday lives. This thesis is concerned with signal design for improving the performance of active sensing and communication systems: The target detection and estimation performance of the active sensing systems can be considerably improved by a judicious design of the probing signals. Similarly, signal design has a crucial role in the implementation and efficiency of communication systems.Signal optimization for active sensing and communications usually deals with various measures of quality. This thesis focuses on several quality measures including (i) correlation and spectral metrics, (ii) signal-to-noise ratio (SNR) and mean-square error (MSE) performance metrics, (iii) information-theoretic criteria, (iv) sparsity-related metrics, and (v) beam-pattern matching metrics. The associated problems are studied and several novel algorithms are proposed to tackle the generally difficult arising problems.
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| 31. |
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| 32. |
- Soltanalian, Mojtaba, et al.
(author)
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Training Signal Design for Correlated Massive MIMO Channel Estimation
- 2017
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In: IEEE Transactions on Wireless Communications. - : IEEE Press. - 1536-1276 .- 1558-2248. ; 16:2, s. 1135-1143
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Journal article (peer-reviewed)abstract
- In this paper, we propose a new approach to the design of training sequences that can be used for an accurate estimation of multi-input multi-output channels. The proposed method is particularly instrumental in training sequence designs that deal with three key challenges: 1) arbitrary channel and noise statistics that do not follow specific models, 2) limitations on the properties of the transmit signals, including total power, per-antenna power, having a constant-modulus, discrete-phase, or low peak-to-average-power ratio, and 3) signal design for large-scale or massive antenna arrays. Several numerical examples are provided to examine the proposed method.
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