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39 results for “Bit Error Rate (BER)”
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Research ArticleOpen accessIn the abstractSolving the Near-Far Problem in Dynamic Frequency Hopping-Optical Code Division Multiple Access using Power ControlW. J.M. Al-galbi, M. Mokhtar, A. F. Abas et al.Problem statement: In this study, a distributed power control algorithm is proposed for Dynamic Frequency Hopping Optical-CDMA (DFH-OCDMA) system. Approach: In general, the DFH-OCDMA can support higher number of simultaneous users compared to other OCDMA techniques. However, the performance of such system degrades significantly as the received power does lower than its minimum threshold. Results: This may obviously occur in … …Journal of Computer Science, Vol. 5, Issue 6 · 30 Jun 2009 · 7,521 accessesView PDFCite
Research ArticleOpen accessIn the abstractProtection for an Immediate Split Structure of Tree-Based EPON Architecture-Ideal Condition AnalysisMohammad Syuhaimi Ab-Rahman, Siti Asma Che Aziz, Kasmiran JumariProblem statement: Ethernet Passive Optical Network (EPON) was proposed to overcome the bandwidth bottleneck at the Access Networks due to its simplicity, cost effective and wide spread deployment. A failure in access networks can cause serious problems, because access network transmit aggregated high speed traffic from hundreds of subscribers. Protection and restoration mechanisms have been applied in backbone networks, but … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 2 · 30 Jun 2009 · 8,276 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
Research ArticleOpen accessIn the abstractMAI Cancellation in DS/CDMA using a new Approach on WDSY. Jabrane, R. Iqdour, B. Ait Es said, N. NajaThe steeping chip weighting waveforms are used in Multiple Access Interference cancellation by emphasizing the received spreading signal, therefore, that allows to solve the problem of orthogonality for the chip waveforms. The goal of this study was to elaborate a useful method based on fuzzy systems to determine the despreading sequences weighted by the steeping chip weighting waveforms for Direct … …American Journal of Applied Sciences, Vol. 4, Issue 10 · 31 Oct 2007 · 6,884 accessesView PDFCite
Research ArticleOpen accessIn the abstractA Switching Mechanism Detection to Reduce Complexity in Multiuser Detection for DS-CDMA SystemsRekha Agarwal, B. V.R. Reddy, K. K. AggarwalWe present a reduced complexity switching mechanism which uses either matched filter or Parallel Interference Cancellation (PIC) detector based on channel characteristics. The main criterion of taking PIC detector is that it has less Bit Error Rate (BER) and less processing delay than other nonlinear multiuser detectors. This proposed detector reduces overall complexity while maintaining the same performance as PIC … …Journal of Mathematics and Statistics, Vol. 2, Issue 2 · 30 Jun 2007 · 6,641 accessesView PDFCite
Research ArticleOpen accessIn the abstractTurbo-coding of Coherence Multiplexed Optical PPM CDMA System With Balanced DetectionK. Chitra, V.C. RavichandranThe effects of turbo-coding on the coherence multiplexed optical PPM CDMA systems are shown by evaluating bit error rate (BER) with respect to system parameters such as interleaver length (K), number of simultaneous users (N), code length (f), initial pulsewidth (t0) and normalized threshold (θ) by including the effects of thermal noise and shot noise. Turbo-codes increase the number of … …American Journal of Applied Sciences, Vol. 4, Issue 5 · 31 May 2007 · 6,617 accessesView PDFCite
Research ArticleOpen accessIn the abstractNeural Networks for Interferences Suppression in DS/CDMA with Rayleigh Fading Channel and Power Control ErrorY. Jabrane, R. Iqdour, B. Ait Essaid et al.The exponential chip weighting waveforms have been designed with the purpose of multiple access interferences (MAI) rejection based on the concept that the optimum despreading sequence in reference emphasizes the transitions in the received spreading signal of interest. The despreading sequence weighted by exponential chip waveforms was determined by only one parameter. The objective of this study, was to introduce … …Journal of Computer Science, Vol. 3, Issue 3 · 31 Mar 2007 · 6,382 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 · 6,847 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 · 7,039 accessesView PDFCite