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.
this research five grammatical terminology, and predicate and ascribed to it and added and genitive, examined scientific accuracy envisaged in placed and how they conform to the content then proposed five alternative terminology, and proved that this alternative terminology reflects more accurately the content of conventional terminology in Arabic grammar lesson, logical approach relies on analysis of morphological derivation of the term and its language, and recommended research to pursue critical studies in grammatical terminology, because such research has Significant impact in removing the grammatical ambiguity of some scholars, as well as instrumental in the development of methods of teaching Arabic grammar, to return to the relatio
... Show MoreBackground: For various reasons, inguinal hernia repair under local anaesthesia is not well accepted to both patients and surgeons. The patients fear from pain and surgeons need full relaxation and co-operation to do successful hernia repairMethods: purpose of this study is to evaluate the effectiveness of local anaesthesia in inguinal hernia repair.prospective study was made from January 2011-0ctober 2013 , on a total of 50 patients with inguinal hernia operated on under local anaesthesia. Patients were selected primarily on the basis of their willingness to accept the procedure after the technique was described to them.Results: In this study 50 patient and 58 herniorrhaphies done for them during a period of about 34months were evaluate
... Show Moreتنتاب العلاقةَ الأمريكية الإيرانية تجاذباتٌ ومشاحنات أدخلت العالم في حالة من الغموض السياسي، وجعلت بعض المراقبين والمحللين السياسيين لا يستبعدون توجيه الولايات المتحدة الأمريكية أو إسرائيل ضربة عسكرية لإيران، إذ يرى المدقق في واقع تلك العلاقة المضطربة: أن الأمور كلما بلغت حافة الهاوية عادت من جديد إلى ساحة الحوار والمفاوضات، ويبدو: أن الإستراتيجية الأمريكية التي يتبعها الرئيس (باراك أو
... Show MoreVirtual reality technology is the science of the embodiment of things and move spontaneously among non-real from one place to another with the full sense of the form, touch, sound, enables the user tried out and deal with it, like a real natural world and open up new worlds for human ambitious to let him overlooks the supposed world. Internet has become part of our daily lives, especially with the presence of mobile devices; that revolutionized the world of social networking. Access to information and build relationships change in the era of digital technology. The woman is not in isolation from this era; she found to herself a wide area for the production of ideas.
When we talk about woman in the modern means of communication, this a
This paper includes the application of Queuing theory with of Particle swarm algorithm or is called (Intelligence swarm) to solve the problem of The queues and developed for General commission for taxes /branch Karkh center in the service stage of the Department of calculators composed of six employees , and it was chosen queuing model is a single-service channel M / M / 1 according to the nature of the circuit work mentioned above and it will be divided according to the letters system for each employee, and it was composed of data collection times (arrival time , service time, departure time)
... Show More
Lost circulation or losses in drilling fluid is one of the most important problems in the oil and gas industry, and it appeared at the beginning of this industry, which caused many problems during the drilling process, which may lead to closing the well and stopping the drilling process. The drilling muds are relatively expensive, especially the muds that contain oil-based mud or that contain special additives, so it is not economically beneficial to waste and lose these muds. The treatment of drilling fluid losses is also somewhat expensive as a result of the wasted time that it caused, as well as the high cost of materials used in the treatment such as heavy materials, cement, and others. The best way to deal with drilling fluid losses
... Show MoreANN modeling is used here to predict missing monthly precipitation data in one station of the eight weather stations network in Sulaimani Governorate. Eight models were developed, one for each station as for prediction. The accuracy of prediction obtain is excellent with correlation coefficients between the predicted and the measured values of monthly precipitation ranged from (90% to 97.2%). The eight ANN models are found after many trials for each station and those with the highest correlation coefficient were selected. All the ANN models are found to have a hyperbolic tangent and identity activation functions for the hidden and output layers respectively, with learning rate of (0.4) and momentum term of (0.9), but with different data
... Show MoreThe term “non-violence” is a means of political, social, and advocacy that excludes force in reaching its objectives, and lacks infringement of the rights of non-violence. The policy of non-violence is a beautiful logic of the whole of Islamic creation, in that it is an integral part of the whole structure of Islam and it is a policy of brilliant and brilliant saying in the Almighty: `` Neither level nor good or bad, pay what is better, If that between you and him enmity as if he were intimate guardian (Suratvsalat, verse: 34. Has According to the prophet of Islam, it means that God gives to kindness (kindness) what does not give to violence (Sunan Abu Dawood, 4/255). These terms accurately communicate what is meant by violence and n
... Show MoreOne of the most important problems of IRAQI HEALTH MINISTRY and all healthy instruments in IRAQ is Chronic Diseases because it have a negative effects on IRAQI population, this is the aim of our study ,to specify the important Chronic diseases which make the population fell weakly, they are six diseases as the IRAQ ministry of health specified ( Diabetes, blood pressure diseases ,Brain diseases , Cardiology, Asthma, epilepsy) we got these data from IRAQI HEALTH MINISTRY ,bureau of planning and studies ,for the period 2009-2012,as monthly observations , represent sum of peoples have chronic diseases in Baghdad .
Our research obj
... Show MoreInfrastructure, especially wastewater projects, plays an important role in the life of residential communities. Due to the increasing population growth, there is also a significant increase in residential and commercial facilities. This research aims to develop two models for predicting the cost and time of wastewater projects according to independent variables affecting them. These variables have been determined through a questionnaire distributed to 20 projects under construction in Al-Kut City/ Wasit Governorate/Iraq. The researcher used artificial neural network technology to develop the models. The results showed that the coefficient of correlation R between actual and predicted values were 99.4% and 99 %, MAPE was
... Show More