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36 results for “fading”
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Research ArticleOpen accessIn the keywordsPerformance Evaluation of Wireless Sensor Network Channel in Agricultural ApplicationNaseer Sabri, S. A. Aljunid, R. B. Ahmad et al.Problem statement: In this study, the behavior of small scale fading channel due to a moving sink node of a Wireless Sensor Network (WSN) or moving of surrounding objects is presented. Approach: Specifically, this research introduces the effects of multipath and scattering on the transmitted signal due to mobile sink node within forest or closed field filled of reflectors and … …American Journal of Applied Sciences, Vol. 9, Issue 1 · 24 Nov 2011 · 7,096 accessesView PDFCite
Research ArticleOpen accessIn the keywordsAdaptive Channel Equalization Using Multiplicative Neural Network for Rayleigh Faded ChannelP. Sivakumar, N. Chithra, S. N. Sivanandam, M. RajaramProblem statement: Digital transmission over band-limited communication channel largely suffers from ISIS and various noise sources. The presence of ISI and noise causes bit errors in the received signal. Equalization is necessary at the receiver to overcome these channel impairment to recover the original transmitted sequence. Traditionally equalization is considered as equivalent to inverse filtering and implemented using linear-perform under … …Journal of Computer Science, Vol. 7, Issue 11 · 18 Aug 2011 · 6,931 accessesView PDFCite
Research ArticleOpen accessIn the keywordsA New Approach for Sub-Channels Assignment in Downlink Fourth Generation Mobile SystemsFakhreddine Khelifa, Abdelaziz SametProblem statement: We proposed a new heuristic method for subchannels allocation problem in the context. Approach: In this system, OFDM transmission method has been used, in order to reduce the effect of multipath fading, OFDMA to achieve multiple access schemes and flexibility in resource allocation. Results: An adaptive method for subchannels allocation is necessary in order to exploit the multiuser … …Journal of Computer Science, Vol. 7, Issue 9 · 23 Jul 2011 · 6,588 accessesView PDFCite
Research ArticleOpen accessIn the keywordsPerformance Analysis of Global Search Algorithm Based Multiuser Detector for Multi Carrier Code Division Multiple Access System under Clipping NoiseS. Sivanesskumar, R. SukaneshProblem statement: Multi Carrier Code Division Multiple Access (MC-CDMA), a promising technology for the 4G communication systems. The major limitation of MC-CDMA system is the Multiple Access Interference (MAI) which is due to near-far effect, frequency offset and nonlinear power amplification due to clipping noise. Approach: The performance of MC-CDMA under clipping noise using Global search algorithm based Multiuser detector … …Journal of Computer Science, Vol. 7, Issue 5 · 7 May 2011 · 6,687 accessesView PDFCite
Research ArticleOpen accessIn the keywordsComparison 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 · 6,847 accessesView PDFCite
Research ArticleOpen accessIn the keywordsThe Impact of Radio Propagation Models on Ad Hoc Networks PerformancesA. Rhattoy, A. ZatniProblem statement: Wireless networks are characterized by a dynamic topology triggered by the nodes mobility. Thus, the wireless multi-hops connection and the channel do not have determinist behaviour such as: Interference or multiple paths. Moreover, the nodes’ invisibility makes the wireless channel difficult to detect. This wireless networks’ behaviour should be scrutinized. Approach: In our study, we mainly focus on … …Journal of Computer Science, Vol. 8, Issue 5 · 2 Mar 2012 · 6,848 accessesView PDFCite
Research ArticleOpen accessIn the abstractBlind Pre-Coder for MIMO System Capacity EnhancementEman Al Khader, Shereen S. IsmailIn this study, linear scheme at the transmitter is proposed as a blind pre-coder to improve the performance and enhance the channel capacity of MIMO systems with certain configurations for transmitting and receiving antennas over fading channels. This is accomplished by generating a specific linear pre-coder matrix without having any prior information about the Channel State (CS) matrix. Simulation results … …American Journal of Engineering and Applied Sciences, Vol. 10, Issue 1 · 11 Jan 2017 · 7,688 accessesView PDFCite
Research ArticleOpen accessIn the abstractA Review on OFDM and PAPR Reduction TechniquesArun Kumar, Manisha GuptaOFDM is a multi carrier transmission technique where a single set of data is transmitted over a number of sub-carrier. OFDM takes the advantage of multi-path propagation and reduces the fading effect. The idea of OFDM is to split the total transmission bandwidth into a number of orthogonal subcarriers which reduces the inter-symbol-interference, power consumption and increases the capacity and … …American Journal of Engineering and Applied Sciences, Vol. 8, Issue 2 · 4 Jun 2015 · 8,394 accessesView PDFCite
Research ArticleOpen accessIn the abstractEnhanced Channel Estimation and Performance Analysis Using H-Infinity Filter for MIMO-Orthogonal Frequency Division Multiplexing SystemsJoseph Gladwin Sekar, Salivahanan SankarappanThis paper, deals with H-infinity channel estimation technique for Orthogonal Frequency Division Multiplexing (OFDM) systems, in fading channel. Channel estimation is important for wireless applications because, in practical transmission scenario, channel correlation functions are either not known or cannot be easily estimated. It is therefore desirable to have an estimator which is robust to mismatches between the assumed and the … …Journal of Computer Science, Vol. 11, Issue 2 · 29 Jan 2015 · 6,823 accessesView PDFCite
Research ArticleOpen accessIn the abstractNEURO FUZZY BASED PERFORMANCE ANALYSIS OF MULTIBAND ULTRA WIDE BAND ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEMG. Joselin Retna Kumar, K. S. ShajiThis study proposes an efficient channel-estimation scheme for Multiband (MB) Orthogonal Frequency Division Multiplexing (OFDM)-based Ultra Wide Band (UWB) communication systems. One of the challenges in wireless system is the frequency selective fading caused due to multipath channel between the transmitter and receiver. The signal bandwidth in broad band cellular wireless systems typically exceeds the coherence bandwidth of the multipath … …Journal of Computer Science, Vol. 10, Issue 8 · 5 Mar 2014 · 6,616 accessesView PDFCite