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To facilitate coherent detection of orthogonal frequency division multiplexed transmissions, pilot symbols can be transmitted in some of the subcarriers. Their placement to minimise the mean squared error in channel estimation is considered. Such problems have been widely addressed previously for channels subject to wide sense stationary uncorrelated scattering processes. While the stationarity assumption...
A novel, reduced complexity iterative channel estimation algorithm for OFDM systems using superimposed pilots is proposed. It utilizes past channel estimations of double correlated channel as a side information to reduce number of iterations. Since pilots are available at all positions of the time-frequency OFDM grid in superimposed technique, the performance of the channel estimation does not degrade...
Recursive minimum mean-square-error estimation (MMSE) with low-complexity computation is considered for online implementation of channel acquisition in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. The channel correlation matrix is estimated by three approaches respectively, i.e., averaging measurements, direct tracking signal subspace of measurements...
In this paper, we propose two robust frequency offset estimation methods for OFDM systems in single frequency network (SFN) with large delay spread. Conventional guard-interval-based (GIB) estimation method is very sensitive to intersymbol interference (ISI) caused by long and strong echoes of the SFN channel. In order to minimize ISI-dependent performance degradation, we first introduce a suboptimal...
The second-order statistics (SOS) of the received signal are very often used in blind and semi-blind channel estimation. In this paper, an analysis of signal perturbation in SOS of the received signal is first conducted, revealling that, even in the noise-free case, some SOS-based blind and semi-blind algorithms are subject to a signal perturbation error. Based on the analysis, a very efficient transmit...
The long term evolution of evolved universal mobile telecommunications system terrestrial radio access, is based on OFDM techniques owing to its inherent flexibility and attractive implementation potential. This paper addresses the issue of time synchronization which is imposed severely challenges particularly in the downlink of LTE systems and the means of time offset estimation exploring different...
In this paper a front-end noise power and SNR estimation method based on one OFDM preamble is proposed and compared with previously published SNR estimators - none of which are front-end estimator. The estimator makes use of two identical halves property of time synchronization preamble used in OFDM systems and relies on autocorrelation of the same. The current estimator is compared with two existing...
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