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94 results on '"Molaei, Amir Masoud"'

1. Near-Field Localization with Antenna Arrays in the Presence of Direction-Dependent Mutual Coupling

Author

Ebadi, Zohreh, Molaei, Amir Masoud, Alexandropoulos, George C., Abbasi, Muhammad Ali Babar, Cotton, Simon, Tukmanov, Anvar, and Yurduseven, Okan

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

Localizing near-field sources considering practical arrays is a recent challenging topic for next generation wireless communication systems. Practical antenna array apertures with closely spaced elements exhibit direction-dependent mutual coupling (MC), which can significantly degrade the performance localization techniques. A conventional method for near-field localization in the presence of MC is the three-dimensional (3D) multiple signal classification technique, which, however, suffers from extremely high computational complexity. Recently, two-dimensional (2D) search alternatives have been presented, exhibiting increased complexity still for direction-dependent MC scenarios. In this paper, we devise a low complexity one-dimensional (1D) iterative method based on an oblique projection operator (IMOP) that estimates direction-dependent MC and the locations of multiple near-field sources. The proposed method first estimates the initial direction of arrival (DOA) and MC using the approximate wavefront model, and then, estimates the initial range of one near-field source using the exact wavefront model. Afterwards, at each iteration, the oblique projection operator is used to isolate components associated with one source from those of other sources. The DOA and range of this one source are estimated using the exact wavefront model and 1D searches. Finally, the direction-dependent MC is estimated for each pair of the estimated DOA and range. The performance of the proposed near-field localization approach is comprehensively investigated and verified using both a full-wave electromagnetic solver and synthetic simulations. It is showcased that our IMOP scheme performs almost similarly to a state-of-the-art approach but with a 42 times less computational complexity., Comment: 13 pages, 11 figures, submitted to an IEEE Transactions

Published
2024

2. Near-Field Localization with an Exact Propagation Model in Presence of Mutual Coupling

Author

Ebadi, Zohreh, Molaei, Amir Masoud, Abbasi, Muhammad Ali Babar, Cotton, Simon, Tukmanov, Anvar, and Yurduseven, Okan

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

Localizing near-field sources considering practical arrays is important in wireless communications. Array-based apertures exhibit mutual coupling between the array elements, which can significantly degrade the performance of the localization method. In this paper, we propose two methods to localize near-field sources by direction of arrival (DOA) and range estimations in the presence of mutual coupling. The first method utilizes a two-dimensional search to estimate DOA and the range of the source. Therefore, it suffers from a high computational load. The second method reduces the two-dimensional search to one-dimensional, thus decreasing the computational complexity while offering similar DOA and range estimation performance. Besides, our second method reduces computational time by over 50% compared to the multiple signal classification (MUSIC) algorithm., Comment: Proceedings of 2024 IEEE 99th Vehicular Technology Conference (VTC2024-Spring)

Published
2024

10. Near-Field Bistatic Microwave Imaging with Dynamic Metasurface Antennas

Author

Molaei, Amir Masoud, primary, Hoang, The Viet, additional, Fromenteze, Thomas, additional, Skouroliakou, Vasiliki, additional, Kumar, Rupesh, additional, Zhao, Mengran, additional, García-Fernández, María, additional, Álvarez-Narciandi, Guillermo, additional, Fusco, Vincent, additional, and Yurduseven, Okan, additional

Published
2024
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15. Two-Dimensional Direction-of-Arrival Estimation Using Direct Data Processing Approach in Directional Frequency Analysis and Recording (DIFAR) Sonobuoy.

Author

Nemati, Amirhossein, Zakeri, Bijan, and Molaei, Amir Masoud

Subjects
ACOUSTIC radiators, DIRECTION of arrival estimation, ACOUSTIC field, FOURIER transforms, PASSIVE components, FAST Fourier transforms
Abstract

Today, the common solutions for underwater source angle detection require manned vessels and towed arrays, which are associated with high costs, risks, and deployment difficulties. An alternative solution for such applications is represented by acoustic vector sensors (AVSs), which are compact, lightweight and moderate in cost, and which have promising performance in terms of the bearing discrimination in two or three dimensions. One of the most popular devices for passive monitoring in underwater surveillance systems that employ AVSs is the directional frequency analysis and recording (DIFAR) sonobuoy. In this paper, direct data-processing (DDP) algorithms are implemented to calculate the azimuth angle of underwater acoustic sources by using short-time Fourier transform (STFT) via the arctan method instead of using fast Fourier transform (FFT). These algorithms for bearing estimation use the 'Azigram' to plot the estimated bearing of a source. It is demonstrated that by knowing the active sound intensity of the sound field and applying the inverse tangent to its real part, this matrix can be obtained. Announcing the time and frequency of the source simultaneously is one of the main advantages of this method, enabling the detection of multiple sources concurrently. DDP can also provide more details about sources' characteristics, such as the frequency of the source and the time of the source's presence. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Real-time Radar Algorithms for Multistatic Millimetre-wave Imaging with Sparse Apertures

Author

Skouroliakou, Vasiliki, Molaei, Amir Masoud, Fusco, Vincent, and Yurduseven, Okan

Subjects
compressive sensing, imaging, radar
Abstract

A majority of radar algorithms leverage frequency domain image reconstruction, based on Fourier transformation, to achieve fast image acquisition. Particularly, in applications like security screening, real-time operation is a key-characteristic, hence the execution time of the reconstruction algorithm is a significant aspect. This paper proposes two computationally efficient techniques to address three-dimensional (3D) image reconstruction in the frequency domain when sparse MultipleInput Multiple-Output (MIMO) apertures are used. The reconstruction fidelity of both methods is demonstrated by simulation results. The proposed algorithms are readily compatible with Synthetic Aperture Radar (SAR) measurement setups as well, hence their performance is also validated using an available set of experimental measurements. This paper focuses on the execution time of each method, when the algorithm is parallelized and executed on a single graphical process unit (GPU), arguing that three-dimensional scenes can be reconstructed with high accuracy in a few milliseconds using very low-cost hardware.

Published
2022
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33. Fourier-based Radar Processing for Multistatic Millimetre-wave Imaging with Sparse Apertures

Author

Skouroliakou, Vasiliki, Molaei, Amir Masoud, Fusco, Vincent, and Yurduseven, Okan

Subjects
ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION
Abstract

Fourier-based radar processing algorithms have attracted a lot of interest among imaging techniques mostly because they are extremely fast. Moreover, such techniques can be integrated with a Multiple-Input Multiple-Output (MIMO) effective aperture, able to alleviate the hardware constraints, to form a cost-effective imaging system that can retrieve an estimation of the scene in real-time. The proposed technique leverages the phase center approximation and a multistatic-tomonostatic data conversion to render the back-scattered measurements compatible with fast Fourier processing. Whereas the phase center approximation is applicable for imaging in the far-field of the synthesized aperture, in the near-field, a more sophisticated aperture design should be considered to reduce the distortion in the reconstructed images. This paper presents a theoretical study for a sparse aperture design and the optimization of the aperture layout in the context of the phase center approximation validity for near-field imaging facilitated by Fourier-based reconstructions. Furthermore, it proposes a GPU accelerated reconstruction algorithm able to form 3D images in a few milliseconds with low-cost hardware

Published
2022
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45. Multistatic MIMO Sparse Imaging Based on FFT and Low-Rank Matrix Recovery Techniques

Author

Hu, Shaoqing, Molaei, Amir Masoud, Yurduseven, Okan, Meng, Hongying, Nilavalan, Rajagopal, Gan, Lu, and Chen, Xiaodong

Abstract

This article proposes a simple sparse imaging scheme using a linear sparse aperiodic array and a new fast Fourier transform matched filtering (FFTMF) algorithm for a THz multistatic multiple-input and multiple-output (MIMO) imaging system. The simple linear sparse aperiodic array and multipass interferometric synthetic aperture focusing technique are used to achieve fast sampling, low system cost, and high imaging performance. Unlike a traditional generalized synthetic aperture focusing technique (GSAFT) for multistatic MIMO imaging, which is time-consuming and exhibits increased reconstruction time with increased data volume, the proposed FFTMF image reconstruction algorithm is capable of providing comparable image quality but significantly reducing the reconstruction time. For example, we show that for an image of 300 $\times320$ mm with a pixel size of $0.75\times0.83$ mm, the reconstruction time is reduced from about 1.50 min to 0.25 s in the 220-GHz five-pass synthetic imaging experiments. The proposed imaging algorithm uses internal zero padding, a multipass interferometric synthetic aperture focusing technique, and a wideband imaging technique to improve the imaging performance under a low-cost, sparse sampling scheme. It shows a strong antinoise ability and a high tolerance to target focusing distance. In addition, integrated with an algorithm of principal component pursuit by alternating directions method (PCPADM), sparse imaging is available to further save system cost and sampling data without a loss of image quality while the novel use of an error matrix provides an additional detection capability for imaging systems.

Published
2023
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