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Channel Estimation Exploiting Channel Sparsity
, M.Sc. Thesis Sharif University of Technology ; Marvasti, Farokh (Supervisor)
Abstract
In this thesis, we investigate the problem of OFDM channel estimation exploiting channel sparsity. Due to the sparse nature of the scattering objects, most of wireless multipath channel have a sparse impulse response. Therefore it is possible to use the methods in the field of sparse signal processing for the purpose of estimating such channels for better accuracy, and efficient spectrum usage.
First of all the problem of OFDM channel estimation using scattered pilots is stated. Then the so-called IMAT methods together with the other sparse signal processing methods are used for the purpose of estimating channel nonzero taps. Furthermore, since efficient use of spectrum in...
First of all the problem of OFDM channel estimation using scattered pilots is stated. Then the so-called IMAT methods together with the other sparse signal processing methods are used for the purpose of estimating channel nonzero taps. Furthermore, since efficient use of spectrum in...
OFDM pilot allocation for sparse channel estimation
, Article Eurasip Journal on Advances in Signal Processing ; Volume 2012, Issue 1 , March , 2012 ; 16876172 (ISSN) ; Amini, A ; Marvasti, F ; Sharif University of Technology
2012
Abstract
In communication systems, efficient use of the spectrum is an indispensable concern. Recently the use of compressed sensing for the purpose of estimating orthogonal frequency division multiplexing (OFDM) sparse multipath channels has been proposed to decrease the transmitted overhead in form of the pilot subcarriers which are essential for channel estimation. In this article, we investigate the problem of deterministic pilot allocation in OFDM systems. The method is based on minimizing the coherence of the submatrix of the unitary discrete fourier transform (DFT) matrix associated with the pilot subcarriers. Unlike the usual case of equidistant pilot subcarriers, we show that non-uniform...
Synthesis and Characterization of Hydrogel Nanocomposites Based on Acrylic Monomers for Flexible Electronics
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Rahmani, Pooria (Supervisor)
Abstract
Hydrogels are three-dimensional polymeric networks capable of absorbing significant amounts of water. Recently, hydrogels based on acrylic monomers have garnered significant attention from researchers for the fabrication of motion sensors that monitor body movements, owing to their inherent ionic conductivity, remarkable flexibility, and biocompatibility. However, one of the common limitations of these hydrogels for practical applications is their inadequate mechanical properties. In this study, hydrophobic physical crosslinks formed from micelles of hydrophobic monomers and coordination-based physical crosslinks induced by trivalent iron ions (Fe³⁺), along with tannic acid (TA)-modified...
Acceleration of Image Reconstruction on the Magnetic Resonance Imaging System
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Nasser (Supervisor) ; Vosughi Vahdat, Bijan (Supervisor) ; Zamani, Pooria ($item.subfieldsMap.e)
Abstract
Magnetic Resonance Imaging ,MRI, although as one of the most advanced medical imaging equipment is well known but compared to other medical imaging systems needs more time to imaging, so it has caused the patient dissatisfaction. According to the recently researches, filling the image data in a space of information that called ‘k-space’, in the process of image reconstruction, is the main reason of slow MRI. Image reconstruction methods for accelerating like half scan based on image reconstruction by using only a part of k-space is used in MRI systems today, but this method is associated with lower SNR image. Recent research on the theory of compressed sensing has been opened a new approach...