Channel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less number of pilot to mitigate ISI effect. Channel estimation is simulated for different pilot number with 16QAM modulation in Ped-A Rayleigh channel. The STO effect assumed less than the cyclic prefix length to minimize ISI and maintain the orthogonality between subcarriers. The simulation results show that the high number of pilots are needed to achieve good channel estimation in case no synchronization used while similar results are achieved with smaller number of pilots if the propose modification on the synchronization method are used aligned with the channel estimation. The proposed system is evaluated in terms of BER and SNR.
The study showed that there are (28) plant families present in Al-Razzaza Lake. The families are (Amaranthaceae, Amaryllidaceae, Aizoaceae, Apiaceae, Apocynaceae, Asteraceae, Brassicaceae, Boraginaceae, Capparaceae, Caryophyllaceae, Cistaceae, Colchicaceae, Convolvulaceae, Cynomoriaceae, Fabaceae, Frankeniaceae, Lamiaceae, Liliaceae, Malvaceae, Orobanchaceae, Plantaginaceae, Poaceae, Polygonaceae, Ranunculaceae, Solanaceae, Tamaricaceae,Typhaceae, Zygophyllaceae). Asteraceae family is the largest number of species found in abundance in this lake, followed by the Fabaceae family.
An experiment was carried out to study the effects of Time Factor, potassium and Molybdenum on Rhizobium growth. The objective of the experiment, which conducted under laboratory conditions, was to investigate the interaction effects of using three levels of Molybdenum (0, 0.25, 2.50 mg Mo . Kg-1 sterile soil) and four levels of potassium (0, 25, 50, 100 mg K . Kg-1 sterile soil) on the viable counts of Rhizobium growth in the sterile soil after 3, 9, 15 and 21 days of incubation at 28°C. The results indicated that Molybdenum level 2.50 mg Mo . Kg-1 sterile soil and potassium level 50 mg K . Kg-1 sterile soil recorded the biggest significant increase in the viable counts of Rhizobium growth in the sterile soil especially after 15 da
... Show MoreBackground: Asthma is a disease of the airways characterized by chronic inflammation associated with airway hyper-responsiveness and airway wall remodeling. Aims of the study: The aims of this study was to determine the prevalence of oral manifestations , identify different microorganism from oral micro flora and determination of salivary IgA and salivary flow rate in asthmatic patients taking different dose of Prednisolone in comparison with control group. Subjects, materials and methods: The study included 17 patients under treatment with Prednisolone (10-20 mg),15 patients take (20-30 mg) of Prednisolone and other 18 patients take (30 – 40mg) of Prednisolone, and 25 healthy control group (10 male and 15 female). Results : The mo
... Show Moreobjective : To assess for Psychological Problems. The study was carried out from 1st of December 2004 to 15th
March, 2005.
Mythology : A descriptive comparative study was conducted for elder in the geriatric home and the community;
A questionnaire was constructed to achieve the purposes of the study; it includes two parts dealing with the
elder demographic characteristics and psychological problems.
A purposive (no probability) sampling of (100) elderly include (50) elderly from the Geriatric Home and (50)
elderly from the community.
Data were collected and analyzed through a descriptive statistical approach (frequency, percentage, mean and
mean of scores, Standard deviation, Relative Sufficiency).
Result : the
Research Summary
The doctrine of belief in the Last Day is one of the pillars of faith, and the doctrine of resurrection and reckoning are part of this day.
Belief in the Last Day puts a person in constant control over himself, as this control creates in this person happiness and a decent life, and he renounces the world and turns away from all vices and adorns all virtues.
On the other hand, we find that the person who does not believe in this day does not stand before his eyes anything that prevents him from doing injustices and corruption in the land. The doctrine of belief in the Last Day alone is
... Show MoreBackground: Dilated cardiomyopathy (DCM) is a well-recognized cause of cardiovascular morbidity and mortality.Objectives: To evaluate the prognostic implications of the restrictive left ventricular filling pattern (RFP) in dilated cardiomyopathy.Methods: Patients with DCM admitted to Ibn AL-Bitar Hospital for Cardiac Surgery, Baghdad-Iraq, from May 2006 to August 2008, underwent a full clinical evaluation and Doppler echocardiography study. Patients were classified into three groups: Group I had persistent restrictive filling pattern; Group II had reversible restrictive filling pattern; and Group III had nonrestrictive filling pattern. Results: The current study was conducted on a total number of 80 patients with DCM, fifty (62.5 %) were
... Show MoreThe avoidance of failure in construction projects is not an easy task, which makes the failure of the construction project to achieve its objectives a major problem experienced by all countries in the world, especially Iraq. Where nearly two-thirds of the construction projects in the world have been suffered by significant problems as an increase in the cost of the project, delay in the specified duration for execution, and stopping the project. Therefore it is required to study and apply new methods for managing the construction project to ensure its success and achieve its objectives. The aim of this study is to study the Agile project management method and its impact on the construction project. In addition, to identi
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