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83 results for “Communication Channel”
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Research ArticleOpen accessIn the abstractPerformance Evaluation of Multi-Pulse Based Code Excited Linear Predictive Speech Coder with Bitrate Scalable Tool over Additive White Gaussian Noise and Rayleigh Fading ChannelsSuphattharachai ChomphanProblem statement: In the modern speech communication technology, the speech coding with bitrate scalability was needed. However, various types of noises in the communication channels cause damages in the transmitted information especially speech data. Tonal-language speech was also affected by this situation. Approach: Based on the high pitch delay resolution technique, the MPCELP speech coding was proposed over the environment … …Journal of Computer Science, Vol. 6, Issue 12 · 6 Nov 2010 · 7,085 accessesView PDFCite
Research ArticleOpen accessIn the abstractProtocol of Secure Key Distribution Using Hash Functions and Quantum Authenticated Channels (KDP-6DP)Mohammed Munther A. Majeed, Khalid A.S. Al-Khateeb, Mohamed R. Wahiddin, Magdy M. SaebProblem statement: In previous researches, we investigated the security of communication channels, which utilizes authentication, key distribution between two parties, error corrections and cost establishment. In the present work, we studied new concepts of Quantum Authentication (QA) and sharing key according to previous points. Approach: This study presented a new protocol concept that allows the session and key generation on-site … …Journal of Computer Science, Vol. 6, Issue 10 · 24 Aug 2010 · 8,271 accessesView PDFCite
Research ArticleOpen accessIn the abstractAn Efficient Causal Protocol with Forward Error Correction for Mobile Distributed SystemsEduardo Lopez Dominguez, Saul E. Pomares Hernandez, Gustavo Rodriguez Gomez et al.Problem statement: Causal ordering is used in Mobile Distributed Systems (MDS) to reduce the non-determinism induced by four main aspects: host mobility, asynchronous execution, unpredictable communication delays and unreliable communication channels. Some causal protocols have been proposed for MDS. All of these protocols in order to ensure the causal order in unreliable channels use the method of Automatic Repeat Request … …Journal of Computer Science, Vol. 6, Issue 7 · 31 Jul 2010 · 8,239 accessesView PDFCite
Research ArticleOpen accessIn the abstractPerformance of Orthogonal Frequency Division Multiplexing System Based on Mobile Velocity and SubcarrierZulkeflee Bin Khalidin, Haitham J. TahaProblem statement: Nowadays, the mobile telecommunications industry faces the problem of providing the technology that be able to support a wide variety of services ranging from voice communication with a bit rate of a few kbps to wireless multimedia in which bit rate up to 2 Mbps. Approach: This study introduced a new performance study to enhance the Orthogonal Frequency … …Journal of Computer Science, Vol. 6, Issue 2 · 28 May 2010 · 7,037 accessesView PDFCite
Research ArticleOpen accessIn the abstractUnequally Error Protected Wireless Data Transmission Using Channel State Information and Adaptive EncodersYaseen H. Tahir, Chee Kyun Ng, N. K. Noordin et al.Problem statement: Higher data transmission rate with Quality of Services (QoS) guarantee is an important objective for wireless broadband communication systems. Unlike other communication system, real-time transmission requires high data rate and good error performance to ensure good quality of service. This study describes the design problem of real-time wireless data transmission which provides higher achievable data rate with Unequal … …Journal of Computer Science, Vol. 5, Issue 12 · 31 Dec 2009 · 7,250 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 abstractConvolution Coder Software Implementation Using VIiterbi Decoding AlgorithmO. O. Khalifa, T. Al-maznaee, M. Munjid, A. H.A. HashimIn this study, Convolutional coder software implementation using Viterbi decoding algorithm for bitstream that had been encoded using forward error correction was presented. It discussed the detailed description and steps involved in simulating a communication channel using convolutional encoding with Viterbi decoding. The steps involved generating random binary data, convolutionally encoding the data, passing the encoded data through a noisy … …Journal of Computer Science, Vol. 4, Issue 10 · 31 Oct 2008 · 6,740 accessesView PDFCite
Research ArticleOpen accessIn the abstractPerformance of Unequal Error Protection Using Maximum A- posteriori Probability Algorithm and Modified MAP in Additive White Gaussian Noise and Fading ChannelT. Gnanasekaran, K. DuraiswamyProblem statement: In this study we propose a method to improve the performance of Maximum A-Posteriori Probability Algorithm, which is used in turbo decoder. Previously the performance of turbo decoder is improved by means of scaling the channel reliability value. Approach: A modification in MAP algorithm proposed in this study, which achieves further improvement in forward error correction by means … …Journal of Computer Science, Vol. 4, Issue 7 · 31 Jul 2008 · 6,686 accessesView PDFCite