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.
This study was conducted to delineate diversity and species composition of non-diatoms planktonic algae in Hoor- Al- Azime marshes, Iran. The samples were collected from four sites at monthly basis from April 2011 to March 2012. A total 88 taxa were identified, out of which (40 taxa, 45.45%) belonging to Cyanophyta followed by Chlorophyta (29 taxa, 32.96%), Euglenophyta (18 taxa, 20.45%) and (1 taxa, 1.14%) of Dinophyta recorded. Comparing species richness (65 taxa, 34.76%) at Shat- Ali (St4) was the highest and the lowest (34 taxa, 18.18%) was observed at Rafi (St2). Species occurrence was associated with temperature where in summer (66 taxa) and (25 taxa) encountered winter. The phy
Summary First: The importance of the study and the need for it: The society is composed of an integrated unit of groups and institutions that seek to achieve a specific goal within a system of salary, and the family remains the most influential institutions on the individual and the unity of society, with the roles and responsibilities of the individual and society, and through the continuation and strength of other social organizations derive their ability On the other hand, any break-up in the institution of the family is reflected negatively on the cohesion of society and its interdependence, and the causes of this disintegration vary from society to another, but family problems remain the main factor in obtaining it. Second: Study Ob
... Show MoreS Khalifa E, AM Sabeeh A, AN Adil A, AW Ghassan H…, 2007
Background. Diabetes mellitus (DM) is a prevalent disease that, if not appropriately managed, can lead to a variety of problems, including diabetic foot. Glycated hemoglobin A1c (HbA1c), FBS, amylase, and lipase are important diabetic management indicators now employed as diagnostic tests. Objective. This study aimed to evaluate the value of amylase and lipase as predictive markers in patients with diabetic foot. Patients and methods. This study included 50 patients who reported to Baghdad Hospital with diabetic feet between November 2023 and February 2025. All patients had their HbA1c, amylase, lipase, and FBS levels tested. Means, independent t-tests, and the F-test were used in the statistical analysis. Results. The study evaluat
... Show MoreBanking institutions are considered one of development foundations,and they also performe active role in supporting national economey and itsinstitutions. Banks became diversed in their activities that specialized Banksbecame one of the constituents of developing work in any activity, especiallyin investiment sector .In view of the importance of insurance sector and thenecessity of developing its divices and its working instituments, studyinginsurance Banking reality became a necessity, because insurance Companies inIraq are suffering of weakness in the level of insurance service, in addition tothe existence of a problem in the relationship between Banks network andinsurance industry.So this research aims to define insurance reality; the
... Show MoreThis paper introduces some properties of separation axioms called α -feeble regular and α -feeble normal spaces (which are weaker than the usual axioms) by using elements of graph which are the essential parts of our α -topological spaces that we study them. Also, it presents some dependent concepts and studies their properties and some relationships between them.
The subject of indication is one of many subjects that the Arabic language interest in and we decide that this research which we called (Indication of the abstract and Augmented Tri verbs) in one of Al-Quran Suras which is Al-moulk to dive in the secrets and knowledge of its meanings and knowledge of its structure in terms of abstraction and increase, And the investigation of our ancient scholars of linguistics and interpreters in its meanings. The verbss were classified according to the structure in which they were presented. The research includes two sections followed by the conclusion of the research, sources and its references. The first section (the indication of the abstract Tri verbs) in the sura is divided into four branches in w
... Show MoreThis study seeks to examine the language context of the prominent Revolution’s poet, Moufdi Zakaria, in his anthology “ The Algerian Odyssey " )إلياذة الجزائر( in which he makes use of the Coranic terms explicitly and implicitly. Besides, it seeks to explore the content of his terms from a lexicographic and semantic point of view in their Islamic and human dimensions