<p><span>Medium access control (MAC) protocol design plays a crucial role to increase the performance of wireless communications and networks. The channel access mechanism is provided by MAC layer to share the medium by multiple stations. Different types of wireless networks have different design requirements such as throughput, delay, power consumption, fairness, reliability, and network density, therefore, MAC protocol for these networks must satisfy their requirements. In this work, we proposed two multiplexing methods for modern wireless networks: Massive multiple-input-multiple-output (MIMO) and power domain non-orthogonal multiple access (PD-NOMA). The first research method namely Massive MIMO uses a massive number of antenna elements to improve both spectral efficiency and energy efficiency. On the other hand, the second research method (PD-NOMA) allows multiple non-orthogonal signals to share the same orthogonal resources by allocating different power level for each station. PD-NOMA has a better spectral efficiency over the orthogonal multiple access methods. A review of previous works regarding the MAC design for different wireless networks is classified based on different categories. The main contribution of this research work is to show the importance of the MAC design with added optimal functionalities to improve the spectral and energy efficiencies of the wireless networks.</span></p>
Summary:
The A. H. 7th century had witnessed an obvious development
in the Yemeni scientific process. The most important reason
being the establishment of the Resooliy State (A. H. 626-858)
which had achieved economic and scientific prosperity in
various fields of knowledge. Its sultans had participated in
building schools, purchasing books, summoning of scientists,
presenting gifts, and encouraging scientific journeys in and out
of Yemen. Therefore, studies had thrived and authorship
widened, and there appeared not a few number of scientists..
The Importance of Effort and its Impact in Building the Society in the Light of
the Holy Book and Sunna.
Thank for God and peace be upon Prophet Muhammad, His hose hold and
Companions.
This research is to refute a fault : that Islam as a religioncalls for laziness and
dependence and this in first, Second, to show the originality of the Islamic method in
building and construction.
This research Starts with an introduction in which I refer to the nature of the
Islamic method and its way of work in life: that it is a divine method that is achieved
by the effort of the people them selfves and not through a divine extraordinary power:
The research explains the shift in the peoples life who were addressed by this<
Background: The bond strength of root canal sealers to dentin and gutta-percha seems to be an important property for maintaining the stability of root canal filling, which potentially influences both leakage and root strength. The objective of this, in vitro, study was to evaluate the shear bond strength of three different endodontic sealers (Gutta-Flow, AH Plus, Apexit Plus) to dentin, in the presence and absence of the smear layer and gutta percha. Material and Methods: After slicing off the occlusal 2mm of 60 extracted human maxillary premolar teeth, the exposed dentin served as the tested surfaces; the teeth were fixed with cold cure acrylic, and were divided into two groups according to the smear layer presence, group A without smear
... Show MoreThe experiment was condncted in greenhouse of Botanical Garden at Biology Garden Dept,College of Education for Pure Science (Ibn-Al-Haitham),University of Baghdad , during the growing season 2013-2014 to study the role of salcylic acid in three concentrations (0.12and24) ppm and two levels of NPKZn fertilizer ( 0. 160) kg.H‾1 and four concentrations of sodium chloride (0.50.100and150) Mmol and the intreaction between salcylic acid and NPKZn on some of morphological parameters of Allium cepa. The experiment was performed with random compelete block design (RCBD)with three replications and the results showed the
... Show MoreHypertension is a major health problem throughout the world because of its high prevalence and its association with increased risk of cardiovascular diseases. It is defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg. The aim of this study was to compare the efficacy, safety and cardiovascular disease risk lowering ability, of three antihypertensive drug regimens.
A retrospective study was carried out on 66 hypertensive patients, divided in to three groups based on their antihypertensive drug regimens (ACE inhibitors, β-blockers treated and combination antihypertensive therapy, the combination therapy consist of two or more of the following antihypertensive drugs ACE inhibitor di
... Show More The visual impression represents a compound process of a group of concepts that might be secondary and interrelated to constitute, in reality, a cognitive image stored in the memory that can be retrieved according the implications of the situation in which the individual lives in his environment, as it awakens in him an image from the sub consciousness, thus it gets stimulated, and it is among the tangible things.
Since we live in our contemporary world under the development of knowledge, micro and wide technology of the devices, tools, materials, mechanisms, current developments and openness… etc. this transformation created visual impressions that the individual in general and the consumer in specific enjoys concerning his
The purpose of this study is to show the constants and variables geography in Russian
policy in light of variables geostrategic witnessed by the world, especially after the collapse
of the Soviet Union and the disintegration to fifteen Republic became the Russian Federation
and the heir to the Soviet Union, Geography particularly important because the impact of its
data in policy making less change ofothers, and explain the political choices cannot achieve
security through its relationship constants geographical (natural or human) paint forms of
economic activity and determine the points they national security. issue is the geographical
this or that country is determined by its policy also specifies the way in which
The experiment for the growing season. 2015-2016 to study the effect of gibberellic acid at concentrations (0 and 50)mgL-1 and BL at five concentrations (0, 0.5 ,1 ,2 and 3)mg.L-1 and their interaction on some chemical characteristics for Dill plant . The experiment was designed according to Randomized Complete Block Design (RCBD) with three replicates per treatment, using less significant difference at the level of probability (0.05) , the results showed the following:- 1- The effect of brassinolide with it,s concentrations led to obtain on a significant increase in all the studied characteristics, so the superiority of the concentration of 2 mg.L -1 of brassinolide in each of nitrogen, potassium and protein, And the superi
... Show MoreBackground: Fenugreek herb is one of the most abundant plants in our country. The dried ripe seeds of this plant are the effective medicinal part the plant.
Aim of the work: The aim of this study is to determine the pharmacological effect of a new chemical substance that has been extracted from crude fenugreek seeds which has a hormonal like action and to assess the safety of this experimental material in order to recommend it in future as a stimulator for ovulation or a contraceptive pill.
Materials and Methods: Sixty uncoupled female rats and mice were enrolled in this study, categorized into groups as mentioned in the text. Prolactin, estradiol and progesterone serum levels where measured for all gr
This cross-sectional, questionnaire-based study evaluated the knowledge, attitude and practice towards breast cancer and breast self-examination [BSE] among 387 [302 females and 85 males] educated Iraqis affiliated to 2 Iraqi universities. The participants were categorized into 3 occupations: student [71.3%], teaching staff [10.3%] and administrative staff [18.3%]. About half of the participants had a low knowledge score [< 50%]; only 14.3% were graded as [Good] and above. Almost 75% of the participants believed that the best way to control breast cancer was through early detection and other possible preventive measures. Most participants [90.9%] had heard of BSE, the main source of informatio
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