Results 91 to 100 of about 2,215 (138)
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Clipping on COFDM with phase on demand
IEEE Communications Letters, 2003This letter presents a simple and effective peak reduction method to achieve a desired peak-to-average power ratio (PAPR). The method is called phase on demand in which a fixed phase vector is added to input vectors only if it helps reduce the peak of the orthogonal frequency-division multiplexing (OFDM) signal otherwise no phase is added.
S. M. Ju, Shu Hung Leung
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28th European Microwave Conference, 1998, 1998
Propagation aspects are inspected for the MMDS range from 2 to 60 GHz. The differences between the free air propagation and the delivering via cable are shown, too. Deutsche Telekom has tested different kinds of digital modulation in a difficult environment. The single-carrier QAM was compared with the multi-carrier QAM (COFDM). These measurements were
B. Boelike, R. Burow, D. Haenssgen
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Propagation aspects are inspected for the MMDS range from 2 to 60 GHz. The differences between the free air propagation and the delivering via cable are shown, too. Deutsche Telekom has tested different kinds of digital modulation in a difficult environment. The single-carrier QAM was compared with the multi-carrier QAM (COFDM). These measurements were
B. Boelike, R. Burow, D. Haenssgen
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Performance of the COFDM systems with waveform shaping
Proceedings of ICC'97 - International Conference on Communications, 2002This paper explains the advantages of using a method for waveform shaping in COFDM. It is shown that such data shaping decreases the side lobes of the transmitted signal and minimizes the need for a guard band between OFDM systems. Classical OFDM systems based on DFT make use of a guard interval in order to improve the performance in multipath fading ...
Valter Benedetto +3 more
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Symbol Synchronization Technique in COFDM Systems
IEEE Transactions on Broadcasting, 2004In this paper we focus our research on the symbol timing synchronization technique in COFDM systems. A new method utilizing pilots to do coarse symbol timing is proposed. It overcomes the problem of fluctuation of the estimated symbol start position with cyclic prefix correlation method.
Bo Ai 0001, Jianhua Ge, Yong Wang 0013
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Novel Asterisk 16QAM Constellation for COFDM
IEEE Communications Letters, 2010We propose a new QAM constellation called A16QAM. This constellation leads to the better average SER and the better CFM than the existing S16QAM, while having the same OFDM PMEPR upper-bounds as S16QAM. In addition, the OFDM PMEPR built by A16QAM is upper bounded by 4.0 and 2.0, if the information symbols are coded using Golay sequences and Golay ...
Xian Liu, Hsiao-Chun Wu
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Synchronization requirements for COFDM systems with transmit diversity
GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489), 2004COFDM in combination with transmit and receive diversity is an attractive technique to increase robustness and throughput of wireless data transmission. In this paper we examine whether the sensitivity of COFDM to synchronization errors is further aggravated by these multiinput multioutput (MIMO) scenarios.
Michael Speth, Heinrich Meyr
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Turbo Equalization for Clipped and Filtered COFDM Signals
2007 IEEE International Conference on Communications, 2007Clipping and filtering is an attractive method for the reduction of the PAPR of OFDM signals before transmission. However, the resulting in-band distortion noise impacts the error rate performance. Since the optimum soft iterative equalization scheme has a prohibitively high computational complexity, we present two equalization algorithms for clipped ...
Peter Zillmann +2 more
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Proceedings of 13th International Conference on Digital Signal Processing, 2002
The impact of tone interference on COFDM systems is studied. Some interference suppression methods are proposed and their performance is assessed through a case study. Various error-correcting techniques are shown to make COFDM suitable for use in the presence of narrowband interferers.
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The impact of tone interference on COFDM systems is studied. Some interference suppression methods are proposed and their performance is assessed through a case study. Various error-correcting techniques are shown to make COFDM suitable for use in the presence of narrowband interferers.
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On the iterative mitigation of clipping noise for COFDM transmissions
European Transactions on Telecommunications, 2008AbstractLarge peak‐to‐average power ratio (PAPR) of multicarrier communication systems is a widely discussed topic in the literature and remains the major drawback of the orthogonal frequency division multiplexing (OFDM) modulation. Deliberate amplitude clipping has been found as a suitable way to reduce output signal peaks at the transmitter side ...
Romain Dejardin +2 more
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Flexible-length Fast Fourier Transform for COFDM
2008 15th IEEE International Conference on Electronics, Circuits and Systems, 2008Integrated circuits to support digital communication standards are commonly based on a Fast Fourier Transform (FFT) of some length. Flexible length makes the design more usable for configurable algorithm-specific circuits. The paper disc uses the algorithmic, functional and structural aspects of a FFT design that can be configured from 16 to 8 k points
Krittanon Chalermsuk +4 more
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