Multipath Channel

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Robert C Qiu - One of the best experts on this subject based on the ideXlab platform.

Eric Simon - One of the best experts on this subject based on the ideXlab platform.

  • Complex Amplitudes Tracking Loop for Multipath Channel estimation in OFDM systems over slow to moderate fading
    Signal Processing, 2014
    Co-Authors: Laurent Ros, Hussein Hijazi, Eric Simon
    Abstract:

    This paper deals with Multipath Channel estimation for Orthogonal Frequency-Division Multiplexing systems under slow to moderate fading conditions. Most of the conventionalmethods exploit only the frequency-domain correlation by estimating the Channel at pilot frequencies, and then interpolating the Channel frequency response. More advanced algorithms exploit in addition the time-domain correlation, by employing Kalman filters based on the approximation of the time-varying Channel. Adopting a parametric approach and assuming a primary acquisition of the path delays, Channel estimators have to track the complex amplitudes of the paths. In this perspective, we propose a less complex algorithm than the Kalman methods, inspired by second-order Phase-Locked Loops. An error signal is created from the pilot-aided Least-Squares estimates of the complex amplitudes, and is integrated by the loop to carry out the final estimates. We derive closed-form expressions of the mean squared error of the algorithm and of the optimal loop coefficients versus the Channel state, assuming a Rayleigh Channel with Jakes'Doppler spectrum. The efficiency of our reduced complexity algorithm is demonstrated, with an asymptotic mean squared error lower than the first-order auto-regressive Kalman filters reported in the literature, and almost the same as a second-order Kalman-based algorithm.

  • Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
    IEEE Transactions on Vehicular Technology, 2007
    Co-Authors: Eric Simon, Laurent Ros, Kosai Raoof
    Abstract:

    In this paper, we consider a Time-Division CDMA system operating in downlink mode in a multi-user Multipath Channel scenario. In order to implement RAKE reception, delays, phases and magnitudes of the different paths need to be estimated and the estimates updated. In the context of burst transmissions, delays do not vary during a burst and only phases and magnitudes need to be tracked. In this paper we investigate the issue of phase tracking over rapidly time varying Multipath Channels. We propose a new version of a conventional phase loop that mitigates the interpath interference effect. The optimization is based on the concept of prefiltering. The analysis shows improved tracking performance in comparison with the standard phase recovery algorithm.

A. Kukushkin - One of the best experts on this subject based on the ideXlab platform.

  • Theory of the performance of a DECT receiver in a Multipath Channel
    IEEE Transactions on Communications, 2000
    Co-Authors: A. Kukushkin
    Abstract:

    The performance of a digital enhanced cordless telecommunications (DECT) receiver in a Multipath Channel is studied. The following issues were investigated: irreducible bit-error rate (BER) performance of the differentially coherent detector in Rayleigh and Rician Channels; BER performance in the presence of both the noise in the receiver and a Multipath interference. The theoretical estimates of the irreducible error rate developed in the paper showed reasonable agreement with the data obtained from computer-based simulation of the DECT link through a Rayleigh Multipath Channel. The combined effect from receiver noise and Multipath interference has been studied, and asymptotic formulas for the total error probability have been developed. The results of calculating the error probabilities using these asymptotics demonstrate good agreement with measured data.

Kosai Raoof - One of the best experts on this subject based on the ideXlab platform.

  • Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
    IEEE Transactions on Vehicular Technology, 2007
    Co-Authors: Eric Simon, Laurent Ros, Kosai Raoof
    Abstract:

    In this paper, we consider a Time-Division CDMA system operating in downlink mode in a multi-user Multipath Channel scenario. In order to implement RAKE reception, delays, phases and magnitudes of the different paths need to be estimated and the estimates updated. In the context of burst transmissions, delays do not vary during a burst and only phases and magnitudes need to be tracked. In this paper we investigate the issue of phase tracking over rapidly time varying Multipath Channels. We propose a new version of a conventional phase loop that mitigates the interpath interference effect. The optimization is based on the concept of prefiltering. The analysis shows improved tracking performance in comparison with the standard phase recovery algorithm.

Laurent Ros - One of the best experts on this subject based on the ideXlab platform.

  • Complex Amplitudes Tracking Loop for Multipath Channel estimation in OFDM systems over slow to moderate fading
    Signal Processing, 2014
    Co-Authors: Laurent Ros, Hussein Hijazi, Eric Simon
    Abstract:

    This paper deals with Multipath Channel estimation for Orthogonal Frequency-Division Multiplexing systems under slow to moderate fading conditions. Most of the conventionalmethods exploit only the frequency-domain correlation by estimating the Channel at pilot frequencies, and then interpolating the Channel frequency response. More advanced algorithms exploit in addition the time-domain correlation, by employing Kalman filters based on the approximation of the time-varying Channel. Adopting a parametric approach and assuming a primary acquisition of the path delays, Channel estimators have to track the complex amplitudes of the paths. In this perspective, we propose a less complex algorithm than the Kalman methods, inspired by second-order Phase-Locked Loops. An error signal is created from the pilot-aided Least-Squares estimates of the complex amplitudes, and is integrated by the loop to carry out the final estimates. We derive closed-form expressions of the mean squared error of the algorithm and of the optimal loop coefficients versus the Channel state, assuming a Rayleigh Channel with Jakes'Doppler spectrum. The efficiency of our reduced complexity algorithm is demonstrated, with an asymptotic mean squared error lower than the first-order auto-regressive Kalman filters reported in the literature, and almost the same as a second-order Kalman-based algorithm.

  • Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
    IEEE Transactions on Vehicular Technology, 2007
    Co-Authors: Eric Simon, Laurent Ros, Kosai Raoof
    Abstract:

    In this paper, we consider a Time-Division CDMA system operating in downlink mode in a multi-user Multipath Channel scenario. In order to implement RAKE reception, delays, phases and magnitudes of the different paths need to be estimated and the estimates updated. In the context of burst transmissions, delays do not vary during a burst and only phases and magnitudes need to be tracked. In this paper we investigate the issue of phase tracking over rapidly time varying Multipath Channels. We propose a new version of a conventional phase loop that mitigates the interpath interference effect. The optimization is based on the concept of prefiltering. The analysis shows improved tracking performance in comparison with the standard phase recovery algorithm.