Results 161 to 170 of about 51,738 (210)
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A hybrid lightwave subcarrier CATV/16-QAM/16-QAM OFDM transmission system
Asia Communications and Photonics Conference 2013, 2013A hybrid lightwave subcarrier CATV/16-QAM/16-QAM orthogonal frequency-division multiplexing (OFDM) transmission system employing light injection/optoelectronic feedback techniques and photonic crystal fiber (PCF) is proposed and demonstrated. Good performance of carrier-to-noise ratio (CNR), composite second order, and composite triple beat were ...
Chia-Yi, Chen +5 more
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International Journal on Wireless & Optical Communications, 2003
A quotient coded quadrature amplitude modulation system having only a finite number of transmitted signal amplitudes is proposed. The expression to estimate the Symbol-Error-Rate (SER) performance of the quotiently coherent demodulated QAM (QQAM) system over a multiplicative Rayleigh fading channel is obtained.
Mingwei Wu +2 more
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A quotient coded quadrature amplitude modulation system having only a finite number of transmitted signal amplitudes is proposed. The expression to estimate the Symbol-Error-Rate (SER) performance of the quotiently coherent demodulated QAM (QQAM) system over a multiplicative Rayleigh fading channel is obtained.
Mingwei Wu +2 more
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ISCAS'99. Proceedings of the 1999 IEEE International Symposium on Circuits and Systems VLSI (Cat. No.99CH36349), 2003
A multicarrier QAM modulator has been developed and simulated. The multicarrier QAM modulator contains four upconversion circuits. Each upconverting circuit accepts 12 b in-phase and quadrature data streams, interpolates those by 16 and upconverts the baseband signal to a selected center frequency.
J. Vankka, M. Kosunen, K. Halonen
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A multicarrier QAM modulator has been developed and simulated. The multicarrier QAM modulator contains four upconversion circuits. Each upconverting circuit accepts 12 b in-phase and quadrature data streams, interpolates those by 16 and upconverts the baseband signal to a selected center frequency.
J. Vankka, M. Kosunen, K. Halonen
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Phase noise effects in QAM systems
Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97, 2002The effects of oscillator phase noise on the performance of digital transmission systems employing QAM are investigated. The model used for the phase noise is a Wiener-Levy process which allows a moment characterization of the filtered phase noise.
CORVAJA, ROBERTO, PUPOLIN, SILVANO
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Error statistic of QAM channel in AM/QAM hybrid optical transmission
IEEE Photonics Technology Letters, 1996The error statistic of the QAM channel in an AM/QAM hybrid optical transmission system is measured. Errors occur randomly in optical transmission without clipping. However, errors are found to occur in bursts when the impulsive noise due to clipping degrades the QAM signal's BER.
K. Maeda, K. Utsumi, K. Fujito
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Performance of block turbo coded 16-QAM and 64-QAM modulations
Proceedings of GLOBECOM '95, 2002We present the results of our investigation concerning the performance of block turbo codes associated with high spectral efficiency QAM modulations. By using a pragmatic approach, simulation results show that all the block turbo coded QAM modulations we have tested are at 2.9/spl plusmn/0.2 dB of their Shannon's limit.
R. Pyndiah, A. Picart, A. Glavieux
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Polarization QAM Modulation (POL-QAM) for Coherent Detection Schemes
Optical Fiber Communication Conference and National Fiber Optic Engineers Conference, 2009A new polarization constellation diagram leads to polarization QAM modulation formats. At 28Gbaud (112Gb/s) POL-QAM 6-4 with six QPSK modulated states-of-polarization enables 1.7-dB higher sensitivity than PDM-QPSK by applying coded-modulation with an inner RS(511,455) FEC.
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2007 IEEE International Conference on Communications, 2007
In this paper, we investigate block-coded QAM constructed by multilevel coding for the noncoherent generalized likelihood ratio test (GLRT) detector. For the AWGN channel, we derive a new GLRT detector and the corresponding distance. The minimum noncoherent distance of block-coded QAM is derived and two construction of noncoherent block-coded QAM (NBC ...
R.-Y. Wei +3 more
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In this paper, we investigate block-coded QAM constructed by multilevel coding for the noncoherent generalized likelihood ratio test (GLRT) detector. For the AWGN channel, we derive a new GLRT detector and the corresponding distance. The minimum noncoherent distance of block-coded QAM is derived and two construction of noncoherent block-coded QAM (NBC ...
R.-Y. Wei +3 more
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IEEE Wireless Communications Letters, 2012
This letter investigates the construction methods of perfect 8-QAM+ sequences, which relate to one of three open problems proposed by Boztas and Parampalli in 2010, and two constructions that transform the known perfect ternary sequences (PTSs) into the required sequences are presented.
Fanxin Zeng +4 more
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This letter investigates the construction methods of perfect 8-QAM+ sequences, which relate to one of three open problems proposed by Boztas and Parampalli in 2010, and two constructions that transform the known perfect ternary sequences (PTSs) into the required sequences are presented.
Fanxin Zeng +4 more
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Capacity/modulation tradeoffs in going from 64 QAM to 256 QAM
IEEE International Conference on Communications, Including Supercomm Technical Sessions, 1990Summary form only given. Increasing the modulation complexity permits significant improvements in bandwidth efficiency. However, the higher level modulation schemes must include additional countermeasures to minimize increased susceptibility to dispersion, loss of threshold, further transmitter power backoff, and increased interference susceptibility. >
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