Belief propagation with Gaussian priors for pilot-assisted communication over fading ISI channels
IEEE Transactions on Wireless Communications
Optimized training and basis expansion model parameters for doubly-selective channel estimation
IEEE Transactions on Wireless Communications
Semiblind bussgang equalization for sparse channels
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
Estimation and equalization of doubly selective channels using known symbol padding
IEEE Transactions on Signal Processing
Optimal training for block transmissions over doubly selective wireless fading channels
IEEE Transactions on Signal Processing
Time-Variant Channel Estimation Using Discrete Prolate Spheroidal Sequences
IEEE Transactions on Signal Processing
Iterative channel estimation for turbo equalization of time-varying frequency-selective channels
IEEE Transactions on Wireless Communications
Optimal placement of known symbols for slowly varying frequency-selective channels
IEEE Transactions on Wireless Communications
IEEE Transactions on Wireless Communications
Rayleigh fading channels in mobile digital communication systems .I. Characterization
IEEE Communications Magazine
Receiver structures for time-varying frequency-selective fading channels
IEEE Journal on Selected Areas in Communications
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Maximum-likelihood semi-blind joint channel estimation and equalization for doubly selective channels and single-carrier systems is proposed. We model the doubly selective channel as an FIR filter where each filter tap is modeled as a linear combination of basis functions. This channel description is then integrated in an iterative scheme based on the expectation-maximization (EM) principle that converges to the channel description vector estimation. We discuss the selection of the basis functions and compare various functions sets. To alleviate the problem of convergence to a local maximum, we propose an initialization scheme to the EM iterations based on a small number of pilot symbols. We further derive a pilot positioning scheme targeted to reduce the probability of convergence to a local maximum. Our pilot positioning analysis reveals that for high Doppler rates it is better to spread the pilots evenly throughout the data block (and not to group them) even for frequency-selective channels. The resulting equalization algorithm is shown to be superior over previously proposed equalization schemes and to perform in many cases close to the maximum-likelihood equalizer with perfect channel knowledge. Our proposed method is also suitable for coded systems and as a building block for Turbo equalization algorithms.