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Carrier frequency offset

About: Carrier frequency offset is a(n) research topic. Over the lifetime, 4173 publication(s) have been published within this topic receiving 50921 citation(s).

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Papers
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Journal ArticleDOI
T.M. Schmidl1, Donald C. Cox2Institutions (2)
TL;DR: A rapid synchronization method is presented for an orthogonal frequency-division multiplexing (OFDM) system using either a continuous transmission or a burst operation over a frequency-selective channel.

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Abstract: A rapid synchronization method is presented for an orthogonal frequency-division multiplexing (OFDM) system using either a continuous transmission or a burst operation over a frequency-selective channel. The presence of a signal can be detected upon the receipt of just one training sequence of two symbols. The start of the frame and the beginning of the symbol can be found, and carrier frequency offsets of many subchannels spacings can be corrected. The algorithms operate near the Cramer-Rao lower bound for the variance of the frequency offset estimate, and the inherent averaging over many subcarriers allows acquisition at very low signal-to-noise ratios (SNRs).

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3,348 citations


9


Journal ArticleDOI
P.H. Moose1Institutions (1)
TL;DR: It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing.

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Abstract: This paper discusses the effects of frequency offset on the performance of orthogonal frequency division multiplexing (OFDM) digital communications. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal. It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing. Next, the paper describes a technique to estimate frequency offset using a repeated data symbol. A maximum likelihood estimation (MLE) algorithm is derived and its performance computed and compared with simulation results. Since the intercarrier interference energy and signal energy both contribute coherently to the estimate, the algorithm generates extremely accurate estimates even when the offset is far too great to demodulate the data values. Also, the estimation error depends only on total symbol energy so it is insensitive to channel spreading and frequency selective fading. A strategy is described for initial acquisition in the event of uncertainty in the initial offset that exceeds 1/2 the carrier spacing, the limit of the MLE algorithm. >

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2,418 citations


Journal ArticleDOI
Abstract: We present the joint maximum likelihood (ML) symbol-time and carrier-frequency offset estimator in orthogonal frequency-division multiplexing (OFDM) systems. Redundant information contained within the cyclic prefix enables this estimation without additional pilots. Simulations show that the frequency estimator may be used in a tracking mode and the time estimator in an acquisition mode.

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2,189 citations


Journal ArticleDOI
TL;DR: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered and the degradation of the bit error rate is evaluated.

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Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >

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1,796 citations


Journal ArticleDOI
Ananthram Swami1, Brian M. Sadler1Institutions (1)
TL;DR: It is shown that cumulant-based classification is particularly effective when used in a hierarchical scheme, enabling separation into subclasses at low signal-to-noise ratio with small sample size.

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Abstract: A simple method, based on elementary fourth-order cumulants, is proposed for the classification of digital modulation schemes. These statistics are natural in this setting as they characterize the shape of the distribution of the noisy baseband I and Q samples. It is shown that cumulant-based classification is particularly effective when used in a hierarchical scheme, enabling separation into subclasses at low signal-to-noise ratio with small sample size. Thus, the method can be used as a preliminary classifier if desired. Computational complexity is order N, where N is the number of complex baseband data samples. This method is robust in the presence of carrier phase and frequency offsets and can be implemented recursively. Theoretical arguments are verified via extensive simulations and comparisons with existing approaches.

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874 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202169
2020142
2019195
2018172
2017212

Top Attributes

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Topic's top 5 most impactful authors

Young-Hwan You

31 papers, 103 citations

Weile Zhang

28 papers, 336 citations

Feifei Gao

25 papers, 495 citations

Hai Lin

21 papers, 294 citations

Chintha Tellambura

19 papers, 602 citations