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113 results for “Channel State”
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Research ArticleOpen accessIn the abstractA Preamble-Based Frequency Offset Compensation Scheme in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing SystemsElnaz Ershadi, Hamidreza BakhshiProblem statement: Combining the properties of Multiple Input Multiple Output (MIMO) systems with those of Orthogonal Frequency Division Multiplexing (OFDM), MIMO-OFDM was considered to be a promising technique in the future of wireless communications. However, its sensitivity to frequency offsets which results in Inter-Carrier Interferences (ICIs) makes it necessary to use an exact frequency offset estimation method for data recovery … …Journal of Computer Science, Vol. 6, Issue 4 · 30 Apr 2010 · 7,570 accessesView PDFCite
Research ArticleOpen accessIn the abstractIterative Channel Estimation Algorithm in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing SystemsMona Nasseri, Hamidreza BakhshiProblem statement: The objective of this study is improving channel estimation accuracy in MIMO-OFDM system because channel state information is required for signal detection at receiver and its accuracy affects the overall performance of system and it is essential to improve the channel estimation for more reliable communications. MIMO-OFDM system was chosen in this study because it has been widely … …Journal of Computer Science, Vol. 6, Issue 2 · 28 Feb 2010 · 8,297 accessesView PDFCite
Research ArticleOpen accessIn the abstractQuantum Key Distribution Using Decoy State ProtocolSellami Ali, Shuhairi Saharudin, M. R.B. WahiddinProblem statement: Quantum key distribution provides unconditional security guaranteed by the fundamental laws of quantum physics. Unfortunately, for real-life experimental set-ups, which mainly based on faint laser pulses, the occasional production of multi-photons and channel loss make it possible for sophisticated eavesdroppers to launch various subtle eavesdropping attacks including the Photon Number Splitting (PNS) attack. The decoy state protocols recently … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 4 · 31 Dec 2009 · 8,434 accessesView PDFCite
Research ArticleOpen accessIn the abstractEfficient Detection Algorithm for a Multiple-Input and Multiple-Output Multiuser Multi-Carrier Code Division Multiple Access in Time-Varying ChannelsFares Sayadi, Mahamod Ismail, Norbahiah Misran et al.Problem statement: Maximum Likelihood (ML) decoding has been applied for the uplink of a Multi-Carrier Code Division Multiple Access (MC-CDMA) system based on Orthogonal Frequency Division Multiplexing (OFDM). Multiple-Input Multiple-Output (MIMO) channel from k users, which moves at vehicular speed, to the Base-Station (BS) is time-varying. For time-varying channels, Sphere Decoding (SD) was introduced to perform ML decoding. Whereas, computational … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 4 · 31 Dec 2009 · 7,576 accessesView PDFCite
Research ArticleOpen accessIn the abstractPore Water Pressure Contribution to Debris Flow MobilityChiara DeangeliProblem statement: Debris flows are very to extremely rapid flows of saturated granular soils. Two main types of debris flow are generally recognized: Open slope debris flows and channelized debris flows. The former is the results of some form of slope failures, the latter can develop along preexisting stream courses by the mobilization of previously deposited debris blanket. The problem … …American Journal of Environmental Sciences, Vol. 5, Issue 4 · 31 Aug 2009 · 6,588 accessesView PDFCite
Research ArticleOpen accessIn the abstractCooperative Sensing in Cognitive Radio Networks-Avoid Non-Perfect Reporting ChannelRania A. Mokhtar, Sabira Khatun, B. M. Ali, A. RamliProblem statement: Cognitive radio is a candidate technology for more efficient spectrum utilization systems based on opportunistic spectrum sharing. However, a common assumption regarding cognitive radios is that they are unlicensed spectrum users that should defer to (avoid interfering with) existing primary sources. Therefore effective sensing of primary users was a major focus of current research. Cooperative spectrum sensing had … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 2 · 30 Jun 2009 · 7,734 accessesView PDFCite
Research ArticleOpen accessIn the abstractIndoor Characterisation using High-Resolution Signal Processing Based on Five-Port Techniques for Signal Input Multiple Output SystemsSmari Mouheddin, Bel hadj Taher JamelProblem statement: The development of wideband mobile communication systems requires a deep knowledge of the characteristics of the indoor mobile radio channel. The characterization of the indoor multi-path propagation structure is important in developing antifading techniques for high-speed digital radio access. The high-resolution of the estimation of the Time of Arrival (ToA) and the Direction of Arrival (DoA) of multi-path … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 2 · 30 Jun 2009 · 7,684 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 · 6,891 accessesView PDFCite
Research ArticleOpen accessIn the abstractGeneric Algorithm with Varying Block Sizes to Improve the Capacity of a Wireless Communications NetworksMahmoud AbdellaouiProblem statement: Channel capacity can be an essential parameter for wireless communication to improve the link quality. Until now, the channel capacity has been evaluated by utilizing Shannon capacity theory, but it presented many limitations and restrictions. The objectives of this study were to: (i) Expose, quantify, present and to give a clear and concise exposition of the mathematical principles … …Journal of Computer Science, Vol. 5, Issue 4 · 30 Apr 2009 · 6,899 accessesView PDFCite
Research ArticleOpen accessIn the abstractA Channel Adaptive Energy Efficient and Fair Scheduling Media Access Control Protocol for Mobile AdHoc NetworksP. Priakanth, P. ThangarajProblem statement: A major drawback in the existing protocols in dealing with energy management issues is that the time varying nature of the wireless channels among the ad hoc nodes is ignored. Approach: This study proposed a channel adaptive energy efficient Medium Access Control (MAC) protocol, for efficient packets scheduling and queuing in an ad hoc network, with time varying … …Journal of Computer Science, Vol. 5, Issue 1 · 31 Jan 2009 · 7,556 accessesView PDFCite