Journal ArticleDOI
A technique for orthogonal frequency division multiplexing frequency offset correction
TLDR
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.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. >read more
Citations
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Journal ArticleDOI
Robust frequency and timing synchronization for OFDM
T.M. Schmidl,Donald C. Cox +1 more
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.
Journal ArticleDOI
ML estimation of time and frequency offset in OFDM systems
TL;DR: In this paper, the joint maximum likelihood (ML) symbol-time and carrier-frequency offset estimator is presented for orthogonal frequency-division multiplexing (OFDM) systems.
Journal ArticleDOI
OFDM and Its Wireless Applications: A Survey
TL;DR: This paper addresses basic OFDM and related modulations, as well as techniques to improve the performance of OFDM for wireless communications, including channel estimation and signal detection, time- and frequency-offset estimation and correction, peak-to-average power ratio reduction, and multiple-input-multiple-output (MIMO) techniques.
Journal ArticleDOI
Optimum receiver design for wireless broad-band systems using OFDM. I
TL;DR: The inner OFDM receiver and its functions necessary to demodulate the received signal and deliver soft information to the outer receiver for decoding are focused on.
Book
Multi-Carrier and Spread Spectrum Systems
Khaled Fazel,Stefan Kaiser +1 more
TL;DR: In this paper, the authors provide an in-depth insight into hybrid multiple access techniques based on multi-carrier (MC) transmission, and present numerous hybrid access and air interface architectures including OFDM/CDMA, MC-CDMA and MT-CDMAC over new techniques such as space-time coding and software radio.
References
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Multicarrier modulation for data transmission: an idea whose time has come
TL;DR: The general technique of parallel transmission on many carriers, called multicarrier modulation (MCM), is explained, and the performance that can be achieved on an undistorted channel and algorithms for achieving that performance are discussed.
Journal ArticleDOI
Data Transmission by Frequency-Division Multiplexing Using the Discrete Fourier Transform
Stephen B. Weinstein,P. Ebert +1 more
TL;DR: The Fourier transform data communication system is described and the effects of linear channel distortion are investigated and a differential phase modulation scheme is presented that obviates any equalization.
Journal ArticleDOI
Synthesis of band-limited orthogonal signals for multichannel data transmission
TL;DR: A principle of orthogonal multiplexing for transmitting a number of data messages simultaneously through a linear band-limited transmission medium at a maximum data rate without interchannel and intersymbol interferences is presented.
Journal ArticleDOI
Digital sound broadcasting to mobile receivers
TL;DR: The authors describe a system that combines the orthogonal frequency-division multiplexing technique and a coding strategy associated with diversity in the frequency domain that is suitable for digital broadcasting through a particularly hostile urban radio channel.