In this paper, a novel feedback frequency synchronizer for orthogonal frequency-division multiplexing signals transmitted over multipath fading channels is described. Its derivation is based on maximum-likelihood estimation techniques and assumes an approximate statistical knowledge of the communication channel. The performance of the proposed algorithm is assessed by computer simulation, and is compared with that provided by other synchronization algorithms and with Cramer-Rao bounds.

The expectation-maximization algorithm for maximum a posteriori (MAP) estimation of a random vector is applied to the problem of detection of orthogonal space-time block codes over time-selective Rayleigh fading channels. This results in a soft-in soft-out detection algorithm suitable for iterative detection/decoding schemes. Simulation results show that the error performance of the proposed detection algorithm is very close to that of a MAP detector endowed with an ideal knowledge of the channel state if the fading rate is not too fast.

In this paper, a soft-in soft-out multiuser detector for synchronous co-channel signals transmitted over frequency-flat Rayleigh-fading channels is described. The derivation of the proposed algorithm is based on a generalization of the expectation-maximization (EM) algorithm, called Bayesian EM. Performance results for both uncoded and coded phase shift keying transmissions show the efficacy of the proposed multiuser detection technique over slowly time-varying fading channels in a two-user system.

In this paper a novel soft-in soft-out (SISO) multiuser detector for co-channel signals transmitted over frequency-flat Rayleigh fading channels is described. The derivation of the proposed algorithm is based on a generalization of the expectation-maximization (EM) algorithm, called Bayesian EM (BEM). Performance results for both uncoded and coded PSK transmissions show the efficacy of the proposed multiuser detection technique over slowly time-varying fading channels in a two user system.

Some novel results on the space-time differential modulation schemes described by B.M. Hochwald and W. Sweldens (see ibid., vol.48, p.2041-52, 2000) and V. Tarokh and H. Jafarkhani (IEEE J. Select. Areas Commun., vol.18, p.1169-74, 2000), are derived under the assumption of a quasi-static multiple-antenna channel. First, the optimality (in the maximum-likelihood sense) of the one-shot detection algorithms of Hochwald and Sweldens and of Tarokh and Jafarkhani is proved. Then, the expression of the pairwise error probability for these detectors is derived, and, as a particular case, the bit-error rate is computed for the binary phase-shift keyed scheme of Tarokh and Jafarkhani. Finally, a per-survivor processing (PSP) detection algorithm for this class of modulations is illustrated. Numerical results evidence both the superiority of the PSP strategy over the one-shot space-time differential detectors and the accuracy of the above-mentioned bit-error rate formula.

In this paper, the expectation-maximization (EM) algorithm for maximum a posteriori (MAP) estimation of a random vector is applied to the problem of symbol detection for continuous phase modulation signals transmitted over time-selective Rayleigh-fading channels. This results in a soft-in-soft-out detection algorithm suitable for iterative detection/decoding schemes. Simulation results show that the error performance provided by the proposed solution is very close to that of a MAP detector endowed with an ideal knowledge of the channel state both in uncoded and coded transmissions.

In this paper the expectation-maximization (EM) algorithm for maximum a posteriori (MAP) estimation of a random vector is applied to the problem of detection of space-time block coded (STBC) signals over time-selective Rayleigh fading channels. This results in a soft-in soft-out (SISO) detection algorithm suitable for iterative detection/decoding schemes. Simulation results show that the error performance of the proposed detection algorithm is very close to that of a MAP detector endowed with an ideal knowledge of the channel state if the fading rate is not too fast.

Novel results on the space-time differential detection technique described by V. Tarokh and H. Jafarkhani (see IEEE J. Select. Areas Commun., vol.18, no.7, p.1169-74, 2000) are derived. First, the optimality of the one-shot detection algorithm proposed by Tarokh and Jafarkhani is proved under some assumptions about the channel model and an accurate bit error rate formula for this detector is derived in a particular case. Finally, a per-survivor processing (PSP) receiver, substantially outperforming Tarokh's detector, is derived. Numerical results show both the superiority of the PSP receiver over the one-shot detector and the accuracy of the above mentioned error rate formula.

A soft-input soft-output (SISO) multiuser detection algorithm for synchronous direct sequence-code division multiple access (DS-CDMA) systems operating over a slow Rayleigh fading channel is illustrated. Its derivation is based on the Bayesian expectation maximization (BEM) technique. The proposed detector estimates the fading channel in an iterative fashion and produces the a posteriori probabilities (APPs) of the transmitted symbols. Its error performance is assessed by computer simulation and is compared with that provided by other multiuser detectors.

In this paper the expectation-maximization (EM) algorithm for maximum a posteriori (MAP) estimation of a random vector is applied to the problem of symbol detection for CPM signals transmitted over time-selective Rayleigh fading channels. This results in a soft-in soft-out (SISO) detection algorithm suitable for iterative detection/decoding schemes. Simulation results show that the error performance provided by the proposed solution is very close to that of a MAP detector endowed with an ideal knowledge of the channel state.

In this paper a novel feedback frequency synchronizer for OFDM signals transmitted over multipath fading channels is described. Its derivation is based on maximum likelihood (ML) estimation techniques and assumes an approximate statistical knowledge of the communication channel. The performance of the proposed algorithm is assessed by computer simulation and is compared with that provided by other synchronization algorithms and with Cramer-Rao bounds.

In this paper an expectation-maximization (EM) technique for maximum a posteriori (MAP) estimation is employed to devise novel soft-in soft-out (SISO) algorithms for symbol detection over frequency-flat Rayleigh fading channels. An application of these algorithms to iterative decoding of coded PSK signals is proposed and some performance results are illustrated.

In this paper, reduced complexity statistical models for the representation of wide sense stationary-uncorrelated scattering doubly selective fading channels are developed. Their derivation is based on the evaluation of Fourier integrals by means of Gaussian quadrature rules. The accuracy and the complexity of the proposed models is assessed, and is then compared to that provided by other modeling techniques available in the literature.

In this paper, optimum one-shot detection over known and partially known doubly selective Rayleigh fading channels is investigated. Reduced complexity channel models based on Gauss quadrature rules and Taylor power series are derived and are employed to develop novel analytical tools for the performance analysis of one-shot detectors. Numerical results allow to assess the implicit diversity gain provided by both channel multipath and signal fading and the energy loss due to the mismatch of the receiver filter.

In this paper, an expectation-maximization (EM) technique for maximum a posteriori estimation is employed to devise novel soft-in soft-out algorithms for symbol detection over frequency-flat Rayleigh fading channels. An application of these algorithms to iterative decoding of coded PSK signals is proposed and some performance results are illustrated.

An expectation-maximization (EM) technique for maximum a posteriori (MAP) estimation of a random parameter is employed to devise a per-survivor phase-tracking algorithm for phase-shift-keyed signals transmitted over channels with phase jitter. Simulation results show that the proposed algorithm can provide substantial performance gains over recursive and nonrecursive phase estimators in the presence of a strong phase jitter.

In this paper optimum one-shot detection over known and partially known doubly-selective Rayleigh fading channels is investigated. The performance analysis of the detection algorithms is based on GQR (Gauss quadrature rules) and power series channel models. The proposed methods allow to assess the implicit diversity gain provided by both channel multipath and signal fading and the energy loss due to the mismatch of the receiver filter.

A simple method for the evaluation of the error rate performance of OFDM signals transmitted over doubly-selective fading channels is described. The accuracy of the proposed technique is exemplified by simulation results. Power series models for multipath channels are employed to derive simple expressions for the average signal-to-interference ratio (SIR) and the average error probability.

In this paper reduced complexity statistical models for the representation of wide sense stationary-uncorrelated scattering (WSS-US) doubly-selective fading channels are developed. Their derivation is based on the evaluation of Fourier integrals by means of Gaussian quadrature rules (GQRs). The accuracy and the complexity of the proposed models are assessed and are compared with that provided by other modelling techniques available in the literature.