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Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models
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Massive multiple-input multiple-output (massive-MIMO) is considered as the key technology to meet the huge demands of data rates in the future wireless communications networks. However, for massive-MIMO systems to realize their maximum potential gain, sufficiently accurate downlink (DL) channel state information (CSI) with low overhead to meet the short coherence time (CT) is required. Therefore, this article aims to overcome the technical challenge of DL CSI estimation in a frequency-division-duplex (FDD) massive-MIMO with short CT considering five different physical correlation models. To this end, the statistical structure of the massive-MIMO channel, which is captured by the physical correlation is exploited to find sufficiently accurate DL CSI estimation. Specifically, to reduce the DL CSI estimation overhead, the training sequence is designed based on the eigenvectors of the transmit correlation matrix. To this end, the achievable sum rate (ASR) maximization and the mean square error (MSE) of CSI estimation with short CT are investigated using the proposed training sequence design. Furthermore, this article examines the effect of channel hardening in an FDD massive-MIMO system. The results demonstrate that in high correlation scenarios, a large loss in channel hardening is obtained. The results reveal that increasing the correlation level reduces the MSE but does not increase the ASR. However, exploiting the spatial correction structure is still very essential for the FDD massive-MIMO systems under limited CT. This finding holds for all the physical correlation models considered.

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Publication Date
Thu Nov 08 2018
Journal Name
Chemistry – A European Journal
Magnetic Shielding, Aromaticity, Antiaromaticity and Bonding in the Low‐Lying Electronic States of S <sub>2</sub> N <sub>2</sub>
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Aromaticity, antiaromaticity and chemical bonding in the ground (S0), first singlet excited (S1) and lowest triplet (T1) electronic states of disulfur dinitride, S2N2, were investigated by analysing the isotropic magnetic shielding, σiso(r), in the space surrounding the molecule for each electronic state. The σiso(r) values were calculated by state-optimized CASSCF/cc-pVTZ wave functions with 22 electrons in 16 orbitals constructed from gauge-including atomic orbitals (GIAOs). The S1 and T1 electronic states were confirmed as 11Au and 13B3u, respectively, through linear response CC3/aug-cc-pVTZ calculations of the vertical excitation energies for eight singlet (S1–S8) and eight triplet (T1–T8) electronic states. The aromaticities of S

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Publication Date
Wed Jun 01 2016
Journal Name
Arabian Journal Of Geosciences
Geochemistry and petrology of Late Miocene-Pleistocene Dibdibba sandstone formation in south and central Iraq: implications for provenance and depositional setting
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Publication Date
Sat Jun 06 2026
Journal Name
Revista Iberoamericana De Psicología Del Ejercicio Y El Deporte, Issn 1886-8576, Vol. 18, Nº. 3, 2023, Págs. 288-290
The History of Clubs?: Participation in the Iraqi Volleyball Premier League and Its Results for the Period from (1991 to 2022)
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Autorías: Omar Saeed Sabbar, Ali Mousa Jawad, Maher Amer Jabbar. Localización: Revista iberoamericana de psicología del ejercicio y el deporte. Nº. 3, 2023. Artículo de Revista en Dialnet.

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Publication Date
Fri Jun 28 2019
Journal Name
Journal Of The College Of Education For Women
Creative Formation in the Poetry of Thafer Bin Qasim Al-Haddad (529 A.H) (Creative Ingenuity as Model): خلود هاشم جوحي الوائلي
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Through research and research in the creative composition in the poetry of Zafer-Alhaddad it turned out to be superior in its systems, especially that he chose a linguistic and verbal texture accompanied by a cultural dictionary full of creativity and beauty helped this culture arrangement reflects the poetically wonderful and beautiful custom led to the harmony of colors and bodies painted by the poet brush the creative artist evaluates the metaphorical and metaphorical relations that would explain the poets idea, most of which were inspired by the wonderful spirit of nature, its beautiful landscapes and bright colors, especially that we do not forget the beautiful colors and the aesthetic touch that created a fascinating musical intera

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Publication Date
Wed Jul 02 2008
Journal Name
Iraqi Journal Of Science
Petrology, geochemistry and tectonic environment of the Shalair Metamorphhic Rock Group and Kater Rash Volcanic Group, Shalair Valley area, Northeastern Iraq
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Publication Date
Sat Dec 17 2022
Journal Name
Iraqi Journal Of Laser
PDF S and U shape offset studying of the refractive index sensor based on coreless fiber: Aya R. Mejble* Hanan J.Taher
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Abstract:  Two different shapes of offset optical fiber was studied based on coreless fiber for refractive index (RI)/concentration (con.) measurement, and compare them. These shapes are U and S-shapes, both shapes structures were formed by one segment of coreless fiber (CF) was joined between two single mode (SMF) lead in /lead out with the same displacement (12.268µm) at both sides, the results shows the high sensitive was achieved in a novel S-shape equal 98.768nm/RIU, to our knowledge, no one has ever mentioned or experienced it, it’s the best shape rather than the U-shape which equal 85.628nm/RIU. In this research, it was proved that the offset form has a significant effect on the sensitivity of the sensor. Addi

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Publication Date
Sat Jun 06 2026
Journal Name
Journal Of Physical Education
The Effect of Increasing Rehabilitation Program Using Electric Stimulation On Rehabilitating Knee Joint Working Muscles Due to ACL Tear In Athletes
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Publication Date
Sun Nov 27 2022
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The strategic vision and its impact on the growth strategy of insurance companies: Applied research in the Iraqi General Insurance Company
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The subject of the strategic vision is of great importance to all companies because they live in an environment of rapid change in various areas of life. Supports the performance of its operations in a better way, towards appropriate strategic growth and achieving success. The research aims to determine the level of interest of the researched company in the research variables (strategic vision and growth strategy), and the importance of the research came in being an attempt to provide the theoretical and scientific foundations for the research variables (strategic vision and growth strategy). As for the research method, it was relied on the descriptive analytical method, relying on the questionnaire as a means of obtaining data from the

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Publication Date
Thu Jan 01 2015
Journal Name
Journal Of Plant Interactions
Photosynthetic and biochemical characterization of in vitro-derived African violet (<i>Saintpaulia ionantha</i>H. Wendl) plants to ex vitro conditions
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Publication Date
Sat Jun 06 2026
Journal Name
Iraqi Journal Of Science
Elastic Electron Scattering Form Factors and Charge Densities for Some Nuclei in 2s-1d Shell Using the Effect of Occupation Numbers
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Elastic electron scattering form factors, charge density distributions and charge,neutron and matter root mean square (rms) radii for P24PMg, P28PSi and P32PS nuclei arestudied using the effect of occupation numbers. Single-particle radial wave functionsof harmonic-oscillators (HO) potential are used. In general, the results of elasticcharge form factors showed good agreement with experimental data. The occupationnumbers are taken to reproduce the quantities mentioned above. The inclusion ofoccupation numbers enhances the form factors to become closer to the data. For thecalculated charge density distributions, the results show good agreement withexperimental data except the fail to produce the hump in the central region for P28PSinucleus.

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