Future wireless networks will require advance physical-layer techniques to meet the requirements of Internet of Everything (IoE) applications and massive communication systems. To this end, a massive MIMO (m-MIMO) system is to date considered one of the key technologies for future wireless networks. This is due to the capability of m-MIMO to bring a significant improvement in the spectral efficiency and energy efficiency. However, designing an efficient downlink (DL) training sequence for fast channel state information (CSI) estimation, i.e., with limited coherence time, in a frequency division duplex (FDD) m-MIMO system when users exhibit different correlation patterns, i.e., span distinct channel covariance matrices, is to date very challenging. Although advanced iterative algorithms have been developed to address this challenge, they exhibit slow convergence speed and thus deliver high latency and computational complexity. To overcome this challenge, we propose a computationally efficient conjugate gradient-descent (CGD) algorithm based on the Riemannian manifold in order to optimize the DL training sequence at base station (BS), while improving the convergence rate to provide a fast CSI estimation for an FDD m-MIMO system. To this end, the sum rate and the computational complexity performances of the proposed training solution are compared with the state-of-the-art iterative algorithms. The results show that the proposed training solution maximizes the achievable sum rate performance, while delivering a lower overall computational complexity owing to a faster convergence rate in comparison to the state-of-the-art iterative algorithms.
Through the history of art movements, abstraction has been rotating between appearance and disappearance, mounting and stillness while its performances differed between reduction and simplification on the one hand and between the use of chromatographic and linear abstraction on the other. As a result, to what is mentioned, abstraction has appeared in many different artistic forms underlying the systematicity of the plastic art history.However, according to a contemporary point of view that comes up with the scientific revolution, the art of optical deceiving (illusion) appeared to find a hybrid art form that locates between the geometricity of abstraction and the scientific, visual and psychological foundations that are linked with the i
... Show MorePerhaps going to watch movies in cinemas today has become different from what it was before. The cinematic film, the clarity of the image and the luster of its colors pulled the rug out from under the most important change that occurred in the structure of the contemporary cinematography, which is the sound. The surround sound environment that immerses viewers in the realism of sound that reaches them from all directions, and for this the researcher found it necessary to shed light on this topic because of its importance, so the research problem was represented in the following question: (How are modern sound systems used in the structure of contemporary feature films?) The theoretical framework included two topics: the first: the dialec
... Show MoreThe present research focuses on the study of the effect of mass transfer resistance on the rate of heat transfer in pool boiling. The nucleate pool boiling heat transfer coefficients for binary mixtures (ethanol-n-butanol, acetone-n-butanol, acetone-ethanol, hexane-benzene, hexane-heptane, and methanol-water) were measured at different concentrations of the more volatile components. The systems chosen covered a wide range of mixture behaviors.
The experimental set up for the present investigation includes electric heating element submerged in the test liquid mounted vertically. Thermocouple and a digital indictor measured the temperature of the heater surface. The actual heat transfer rate being obtained by multiplying the voltme
... Show MoreThe research aims to test the impact of servant leadership in management information systems, as well as to identify the level of servant leadership practice and management information systems in the Directorate of Communications and Information Systems in the Iraqi Ministry of Interior, in terms of the importance of the research variables to the directorate and the sample community, as the research adopted the exploratory analytical descriptive approach In his achievement, through a survey of the opinions of an intended quota sample of (266) individuals, By adopting the questionnaire as a main tool for data collection that includes (44) items divided into the two research variables, As well as conducting open interviews to identify the pro
... Show MoreOver the last two decades, several sustainability assessment methods have developed as key accelerators for the development and improvement of sustainable industrial buildings. Some of these systems, like as LEED or BREEAM, are considered international, whereas others, such as Pearl Rating Systems (PRS), are local. Although they all share similar goals, they can lead to the construction of green buildings or the improvement of the efficiency of existing conventional buildings. Each technique has its structure, certification process, and weighting norms. The inequalities have prompted various questions about whether global assessment systems appropriately consider the country’s national settings. This study aims to compare the Pear
... Show MoreINTRODUCTION: A range of tools and technologies are at disposal for the purpose of defect detection. These include but are not limited to sensors, Statistical Process Control (SPC) software, Artificial Intelligence (AI) and machine learning (ML) algorithms, X-ray systems, ultrasound systems, and eddy current systems. OBJECTIVES: The determination of the suitable instrument or combination of instruments is contingent upon the precise production procedure and the category of flaw being identified. In certain cases, defects may necessitate real-time monitoring and analysis through the use of sensors and SPC software, whereas more comprehensive analysis may be required for other defects through the utilization of X-ray or ultrasound sy
... Show MoreA new (Reversed Phase- High Performance Liquid chromatography) RP-HPLC method with Ultraviolet-Visible spectrophotometry has been optimized and validated for the simultaneous extraction and determination of antioxidants present in Iraqi calyces of Hibiscus Sabdraffia Linn. The method is based on using ultrasonic bath for extracting antioxidants. Limit of detection in μg/ml of Vitamin C, Sabdaretine, Gossypetine, Hibiscetine, Anthocyanins, Dephinidin-3-glucoside were113.8294×10-6,123.0453×10-6,70.3681×10-6,59.6730×10-6,148.1710×10-6,and125.3481×10-6 respectively. The concentration of antioxidants found in dry spacemen of calyces of Iraqi Hibiscus Sabdraffia Linn. under study: Vitamin C, Sabdaretine, Gossypetine, Hibiscetine, Anthoc
... Show MoreIn this work, the fusion cross section , fusion barrier distribution and the probability of fusion have been investigated by coupled channel method for the systems 46Ti+64Ni, 40Ca+194Pt and 40Ar+148Sm with semi-classical and quantum mechanical approach using SCF and CCFULL Fortran codes respectively. The results for these calculations are compared with available experimental data. The results show that the quantum calculations agree better with experimental data, especially bellow the Coulomb barrier, for the studied systems while above this barrier, the two codes reproduce the data.