Search results for "Intersymbol interference"

showing 7 items of 7 documents

Channel Estimation and Interference Cancellation for MIMO-OFDM Systems

2007

This paper proposes a new channel estimation method and a new interference cancellation scheme for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems in the presence of intersymbol interference (IS1). The proposed channel estimation method uses special training sequences (TSs) to have a desirable crest-factor of the transmitted training signal, and to prevent the influence of ISI on the channel estimation performance. By using the recommended training sequences, the ill-conditioned problem of the least square (LS) filter integrated in the proposed channel estimator can be avoided. The proposed interference cancellation scheme uses the estimated cha…

Block codeComputer Networks and Communicationsbusiness.industryOrthogonal frequency-division multiplexingComputer scienceEstimatorData_CODINGANDINFORMATIONTHEORYMIMO-OFDMInterference (wave propagation)Space–time block codeIntersymbol interferenceSignal-to-noise ratioInterference (communication)Single antenna interference cancellationChannel state informationGuard intervalDemodulationElectrical and Electronic EngineeringTelecommunicationsbusinessNyquist ISI criterionAlgorithmSoftwareComputer Science::Information TheoryCommunication channelIEICE Transactions on Communications
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Filtering out intersymbol interference in spread-spectrum communication systems

1979

In this letter the transfer characteristic of the optimum filter suitable for eliminating intersymbol interference in pseudo-noise spread-spectrum communication systems is determined. Such a characteristic is independent of the code sequence employed.

Intersymbol interferenceComputer scienceElectronic engineeringFilter (signal processing)Direct-sequence spread spectrumElectrical and Electronic EngineeringCommunications systemRaised-cosine filterNyquist ISI criterionPulse shapingComputer Science::Information TheoryRoot-raised-cosine filterElectronics Letters
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MUSIC-LS Modal Channel Estimation for an OFDM-OQAM System

2008

Orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM) signaling over frequency selective multipath channels shows inter-symbol interference (ISI) and Inter-Channel Interference (ICI) that degrade its performance. Channel equalization and channel estimation are needed to combat these intrinsic interferences. In this paper a novel modal channel estimator based on the MUltiple signal classification (MUSIC) and least squares (LS) algorithms for a wideband passband OFDM-OQAM signaling over static multipath channels is presented. The effects of the frequency selective channel on the received signal are described considering a wideband OFDM-OQAM sys…

OFDM-OQAMOrthogonal frequency-division multiplexingComputer scienceSettore ING-INF/03 - TelecomunicazioniSpeech recognitionData_CODINGANDINFORMATIONTHEORYLeast squaresChannel modelingMUSICIntersymbol interferenceInterference (communication)Adjacent-channel interferenceWidebandAlgorithmQuadrature amplitude modulationComputer Science::Information TheoryCommunication channel
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MUSIC-based modal channel estimation for wideband OFDM-OQAM

2008

Orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM) over wideband frequency selective multipath channels suffers from inter-symbol interference (ISI) and inter-carrier interference (ICI) that degrade its performance. Channel estimation and equalization are needed to combat these interferences. In this paper a novel channel estimator for passband OFDM-OQAM signaling over wideband multipath channels, which is based on multiple signal classification (MUSIC) with the Spatial Smoothing technique is presented. Numerical simulation results are presented in the low number of subcarriers, i.e. wideband, scenario.

OFDM-OQAMSettore ING-INF/03 - TelecomunicazioniOrthogonal frequency-division multiplexingComputer sciencebusiness.industryChannel estimationMUSICComputer Science::OtherIntersymbol interferenceInterference (communication)Computer Science::Networking and Internet ArchitectureElectronic engineeringWidebandTelecommunicationsbusinessPassbandQuadrature amplitude modulationSmoothingComputer Science::Information TheoryCommunication channel2008 1st IFIP Wireless Days
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The UWB-OFDM Channel Analysis in Frequency

2009

In this paper, the ultra-wideband channel with orthogonal frequency division multiplexing (UWB-OFDM) is analyzed in the frequency domain. For UWB-OFDM channels with log-normal fading in the time domain, we show that the amplitude of each subcarrier can be approximated by a Nakagami-m random variable, where the fading parameter, the mean power and the correlation coefficient are expressed in terms of the following parameters: time arrival of the clusters, inter-arrival time of rays inside clusters, and power decay constants of rays and clusters.

PhysicsAutomatización y sistemas de controlOrthogonal frequency-division multiplexingTecnologíaNakagami distributionTopologyBanda anchaAutomation Command and control systemSubcarrierComputer Science::OtherSystems engineeringComputer Science::PerformanceIntersymbol interferenceAmplitudeFrequency domainComunicación inalámbricaElectronic engineeringComputer Science::Networking and Internet ArchitectureSistemas de comunicación inalámbricaFadingTime domainIngeniería de sistemas y comunicacionesComputer Science::Information Theory
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Grating compensated dispersion-managed systems incorporating nonlinear optical loop mirrors

2006

In this work, we investigate the use of nonlinear optical loop mirrors (NOLMs) in DM fiber systems compensated by CFGs with GDR by launching a 128-bit Gaussian-shaped pseudo-random bit sequence having pulse width of 5 ps for simulating a 40 Gb/s system. The dispersion map contains a fiber segment of length 10.3 km and a CFG with dispersion of -15.6 ps/nm. We consider a lossless grating and the GDR is modeled by a sinusoidal function for simplicity. We have shown that the use of NOLMs can substantially improve the transmission performance in a grating-compensated DM fiber system even with presence of amplifier noise and random variations of GDR, parameters in CFGs along the propagation dista…

PhysicsIntersymbol interferenceSine waveOpticsbusiness.industryQ factorDispersion (optics)Nonlinear opticsGratingbusinessTelecommunicationsDiffraction gratingPulse-width modulationCLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005.
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Gaussian pulse propagation in dispersion-managed systems using chirped fiber gratings with group delay ripples

2005

We study the propagation of Gaussian-shaped pulses in grating-compensated dispersion-managed systems with group delay ripples (GDR). We show that the intersymbol interference caused by the GDR in gratings can be substantially reduced by nonlinear optical loop mirrors and the 40-Gb/s system performance can achieve transoceanic transmission in the presence of amplifier noise and random variations in ripple period of the gratings along the transmission line.

Physicsbusiness.industryRippleOptical communicationPropagation delayAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsIntersymbol interferenceOpticsTransmission lineChirpElectrical and Electronic EngineeringbusinessDiffraction gratingGroup delay and phase delayIEEE Photonics Technology Letters
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