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128 results for “modulation”
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Research ArticleOpen accessIn the abstractMultiple Input Multiple Output System with Space Time Block Coding and Orthogonal Frequency Division MultiplexingP. Ramesh Kumar, R. M.S. ParvathiProblem statement: A large amount of research has been performed to achieve very high data rate networks to support reliable transmission of video, data and speech at high rates to many users. One way to increase the data rate in a wireless system is to use multiple transmit and/or receive antennas (MIMO structure). Indeed, it has been shown that the … …Journal of Computer Science, Vol. 8, Issue 4 · 26 Jan 2012 · 6,763 accessesView PDFCite
Research ArticleOpen accessIn the abstractPerformance Analysis of IEEE 802.16d using Forward Error CorrectionVenkatesh Sekar, V. Palanisamy, K. BaskaranProblem statement: Worldwide Interoperability for Microwave Access is the broadband wireless technology for terrestrial broadcast services in Metropolitan Area Networks. This BWA technology is based on Orthogonal Frequency Division Multiplex (OFDM) technology and considers the radio frequency range up to 2-11 GHz and 10-66 GHz. The objective of this research work is the performance analysis of AWGN, SUI-1 and SUI-2 … …Journal of Computer Science, Vol. 7, Issue 3 · 9 Mar 2011 · 7,343 accessesView PDFCite
Research ArticleOpen accessIn the abstractThe Flavonoid, Quercetin, Inhibits HIV-1 Infection in Normal Peripheral Blood Mononuclear CellsMadhavan P.N. Nair, Zainulabedin M. Saiyed, Nimisha H. Gandhi, C. N. RamchandProblem statement: Flavonoids and related polyphenols, have been known to possess cardioprotective, anti-tumor, anti-inflammatory, anti-allergic and anti-viral activities. Previous studies have shown that flavonoid, quercetin significantly downregulates expression of pro-inflammatory cytokines in cultured cells via modulation of NFκB and p38MAPK signaling pathways. In the current study, we hypothesize that quercetin exerts anti-HIV activity by differential modulation of pro-and anti-inflammatory cytokine … …American Journal of Infectious Diseases, Vol. 5, Issue 2 · 30 Jun 2009 · 12,190 accessesView PDFCite
Research ArticleOpen accessIn the abstractWeighted Semi-Blind Channel Identification by Cross Relation MethodMohamed Tahar Taba, S. FemmamProblem statement: The bandwidth efficiency of many communication systems could be improved if the transmission channel was estimated blindly without resort to training sequences. GMSK was a spectrum-efficient modulation scheme and it was adopted as the modulation standard of GSM systems. Approach: However, because of its phase modulation, Gaussian filtering and partial response signalling properties, Results: The simulation results showed … …American Journal of Applied Sciences, Vol. 6, Issue 6 · 30 Jun 2009 · 6,895 accessesView PDFCite
Research ArticleOpen accessIn the abstractControl Strategy for Discontinuous Conduction Mode Boost Rectifier with Low Total Harmonic Distortion and Improved Dynamic ResponseH.S. AthabDue to its simplicity, the discontinuous conduction mode boost rectifier is potentially the least expensive active line-harmonics reducing circuit. Problem statement: The line current however, shows considerable distortion when the peak input voltage is close to the output voltage, As a result, the input power factor is poor. This study proposes a simple, low-cost method to reduce the line harmonics. … …American Journal of Engineering and Applied Sciences, Vol. 1, Issue 4 · 31 Dec 2008 · 7,424 accessesView PDFCite
Research ArticleOpen accessIn the abstractMicroarray Analysis of Human Vascular Smooth Muscle Cell Responses to Bacterial LipopolysaccharideJoe Minta James, J. Yun, Sandy Der, Shikha RanaAccumulating evidence suggest a causal role of bacterial and viral infections in atherogenesis. Bacterial lipopolysaccharide (LPS) has been shown to stimulate resting vascular smooth muscle cells (SMC) with the production of inflammatory cytokines and modulation of quiescent cells to the proliferative and synthetic phenotype. To comprehensively identify biologically important genes associated with LPS-induced SMC phenotype modulation, we compared the transcriptomes … …American Journal of Immunology, Vol. 3, Issue 2 · 31 Dec 2007 · 6,998 accessesView PDFCite
Research ArticleOpen accessIn the abstractOpiates Upregulate Adhesion Molecule Expression in Brain MicroVascular Endothelial Cells (BMVEC): Implications for Altered Blood Brain Barrier (BBB) PermeabilityMadhavan P.N. Nair, Supriya D. Mahajan, Jessica L. ReynoldsThe blood-brain barrier (BBB) is an intricate cellular system composed of vascular endothelial cells and perivascular astrocytes that restrict the passage of immunocompetent cells into the central nervous system (CNS). Expression of the adhesion molecules, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on brain microvascular endothelial cells (BMVEC) and their interaction with human immunodeficiency virus (HIV-1) … …American Journal of Infectious Diseases, Vol. 2, Issue 2 · 30 Jun 2006 · 6,614 accessesView PDFCite
Research ArticleOpen accessIn the abstractDetermination of Absorption Coefficients and Thermal Diffusivity of Modulated Doped GaAlAs/GaAs Heterostructure by Photothermal Deflection SpectroscopyS. Aloulou, M. Fathallah, M. Oueslati, A. SfaxiWe report in this study theoretical and experimental studies of photothermal deflection spectroscopy (PDS) for planar doped heterostructures AlGaAs/GaAs. The PDS spectra at T=300K are recorded by varying the wavelength of the excited radiation for different modulation frequencies. They show two different regions related to the fundamental electronic transitions from GaAs and Si doped AlGaAs. The DX levels have been … …American Journal of Applied Sciences, Vol. 2, Issue 10 · 31 Oct 2005 · 7,264 accessesView PDFCite
Research ArticleOpen accessIn the abstractComparison of Bit Error Rate Performance of Multi Tone Channel Utilising De-OQPSK and De-Off Set 16 QAM with Guard IntervalIbrahim A.Z. QatawnehDigital communications systems use Multi tone Channel (MC) transmission techniques with differentially encoded and differentially coherent demodulation. Today there are two principle MC application, one is for the high speed digital subscriber loop and the other is for the broadcasting of digital audio and video signals. In this study the comparison of multi carriers with OQPSK and Offset 16 QAM … …Journal of Computer Science, Vol. 1, Issue 3 · 30 Sep 2005 · 6,849 accessesView PDFCite
Research ArticleOpen accessIn the abstractImplementation of a Novel Concatenated FEC by RS and Irregular Turbo Codes on OFDM SystemsA. Shanmugam, A. R. Abdul Rajak, S. Vishwanath, R. UpendraCode Division Multiple Access (CDMA) performs well in a multi-cellular environment where a single frequency is used in all cells. Code Division Multiple Access (CDMA) has severe problems associated with multipath and Channel news. One possible problem is that the receiver may require a very large dynamic range in order to handle the large signal strength variation among users. Due … …American Journal of Applied Sciences, Vol. 2, Issue 5 · 31 May 2005 · 7,042 accessesView PDFCite