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.
Use of Surveillance cameras in houses and markets became common, that resulted to minimize theft and make it a difficult task because it let recording and viewing what is going around. The wide application of these cameras, pushed thieves to seek new ways for abolition of the surveillance system and digital recording of events, such as cutting the signal wire between the camera and Digital video recorder or changing the direction of the camera away from the focus spot or damaging the camera or steal the device which means the loss of the recorded media. This paper focuses on such abolitions and fixed it by suggesting a way to notify the administrator immediately and automatically by Email about any violation of the system using MATLAB, whic
... Show MoreMost of the propositions and researches that dealt with fashions in the Middle East, specifically this region from the world, from a historical perspective have not been sufficient, and were characterized by many aspects of immature thinking, in addition, they have been varied in quality. This can be attributed to many factors including: the focus in the field of researches and Middle East studies is on languages, arts, history, and political thinking of the region. Other factors are the information asymmetry, the differences in sources and references, in addition to differences in the scientific value of these sources added to the difficulty of gathering them at the same time especially that these sources are scattered in many places wh
... Show MoreThis paper presents a proposed method for (CBIR) from using Discrete Cosine Transform with Kekre Wavelet Transform (DCT/KWT), and Daubechies Wavelet Transform with Kekre Wavelet Transform (D4/KWT) to extract features for Distributed Database system where clients/server as a Star topology, client send the query image and server (which has the database) make all the work and then send the retrieval images to the client. A comparison between these two approaches: first DCT compare with DCT/KWT and second D4 compare with D4/KWT are made. The work experimented over the image database of 200 images of 4 categories and the performance of image retrieval with respect to two similarity measures namely Euclidian distance (ED) and sum of absolute diff
... Show MoreBackground: Health information systems in most countries are inadequate in providing the needed management support and the current health information systems are therefore widely seen as management obstacles rather than as tools,Objectives: the current study is an attempt to assess the behavioral and organizational determinants of health information system performance in Iraq.Methods: A cross-sectional study was conducted by interviewed a total of 189 respondents selected from six Iraqi governorates. The Organizational and Behavioral Assessment Tool was used to measure the behavioral and organizational determinants of health information system performance, it is one of the PRISM package tools that are used to assess the health informatio
... Show MoreThe purpose of this work is to concurrently estimate the UVvisible spectra of binary combinations of piroxicam and mefenamic acid using the chemometric approach. To create the model, spectral data from 73 samples (with wavelengths between 200 and 400 nm) were employed. A two-layer artificial neural network model was created, with two neurons in the output layer and fourteen neurons in the hidden layer. The model was trained to simulate the concentrations and spectra of piroxicam and mefenamic acid. For piroxicam and mefenamic acid, respectively, the Levenberg-Marquardt algorithm with feed-forward back-propagation learning produced root mean square errors of prediction of 0.1679 μg/mL and 0.1154 μg/mL, with coefficients of determination of
... Show MoreThe principle in the language is that each word has one meaning. This is because the purpose of language development is for understanding, understanding, and communication between people. The language is sounds with which each people expresses their Arabic language did not stop at this point, but rather needed another next stage or to convey additional features or characteristics that would qualify it. To be the language of the Qur’an and revelation, and capable of carrying this heavy burden.
النظام السياسي في كوريا الشمالة