The Experts below are selected from a list of 26301 Experts worldwide ranked by ideXlab platform
Robert C Qiu - One of the best experts on this subject based on the ideXlab platform.
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generalized time domain Multipath Channel and its application in ultra wideband uwb wireless optimal receiver part iii system performance analysis
IEEE Transactions on Wireless Communications, 2006Co-Authors: Robert C QiuAbstract:This paper deals with the time domain characteristics of UWB Multipath Channel while considering UWB pulse shape distortion and its impact on system performance as well as optimal receiver design. It appears that no deterministic and analytical Channel model in the time domain has ever appeared in the literature, to our best knowledge. A generalized Channel model and some related exact solutions for some specific geometric configurations are discussed, based on the pulse propagation mechanisms of reflection and diffraction. In addition, a system performance framework integrated with the close-form Channel model expressions is also provided, corresponding to the optimal receiver structure and the concrete geometric configurations of a UWB Channel. This work is very important in the design of the optimal UWB systems
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a generalized time domain Multipath Channel and its application in ultra wideband uwb wireless optimal receiver design part ii physics based system analysis
IEEE Transactions on Wireless Communications, 2004Co-Authors: Robert C QiuAbstract:This paper has established a new theoretical framework that allows us to analyze the ultra-wideband system performance using the closed form formulations. A new generalized time-domain Multipath Channel based on the geometric theory of diffraction/uniform theory of diffraction (GTD/UTD) framework is incorporated into the system bit-error rate and signal-to-noise ratio by modifying the existing system model. Closed form expressions for important geometric configurations are derived in the time domain for the first time. Some interesting insights into the physical mechanisms and system analysis are observed through explicit expressions and numerical results.
Eric Simon - One of the best experts on this subject based on the ideXlab platform.
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Complex Amplitudes Tracking Loop for Multipath Channel estimation in OFDM systems over slow to moderate fading
Signal Processing, 2014Co-Authors: Laurent Ros, Hussein Hijazi, Eric SimonAbstract: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.
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Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
IEEE Transactions on Vehicular Technology, 2007Co-Authors: Eric Simon, Laurent Ros, Kosai RaoofAbstract: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.
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Theory of the performance of a DECT receiver in a Multipath Channel
IEEE Transactions on Communications, 2000Co-Authors: A. KukushkinAbstract: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.
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Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
IEEE Transactions on Vehicular Technology, 2007Co-Authors: Eric Simon, Laurent Ros, Kosai RaoofAbstract: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.
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Complex Amplitudes Tracking Loop for Multipath Channel estimation in OFDM systems over slow to moderate fading
Signal Processing, 2014Co-Authors: Laurent Ros, Hussein Hijazi, Eric SimonAbstract: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.
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Synchronization over rapidly time-varying Multipath Channel for CDMA downlink RAKE receivers in Time-Division mode
IEEE Transactions on Vehicular Technology, 2007Co-Authors: Eric Simon, Laurent Ros, Kosai RaoofAbstract: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.