The Experts below are selected from a list of 26895 Experts worldwide ranked by ideXlab platform
Hussein Hijazi - One of the best experts on this subject based on the ideXlab platform.
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Joint data QR-detection and Kalman estimation for OFDM time-varying Rayleigh Channel complex gains
IEEE Transactions on Communications, 2010Co-Authors: Hussein HijaziAbstract:This paper deals with the case of a high speed mobile receiver operating in an orthogonal-frequency-division-multiplexing (OFDM) communication system. Assuming the knowledge of delay-related information, we propose an iterative algorithm for joint multi-path Rayleigh Channel complex gains estimation and data recovery in fast fading environments. Each complex gain time-variation, within one OFDM symbol, is approximated by a polynomial representation. Based on the Jakes process, an auto-regressive (AR) model of the polynomial coefficients dynamics is built, making it possible to employ the Kalman filter estimator for the polynomial coefficients. Hence, the Channel matrix is easily computed, and the data symbol is estimated with free inter-sub-carrier-interference (ICI) thanks to the use of a QR-decomposition of the Channel matrix. Our claims are supported by theoretical analysis and simulation results, which are obtained considering Jakes' Channels with high Doppler spreads.
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Joint Data QR-Detection and Kalman Estimation for OFDM Time-varying Rayleigh Channel Complex Gains
IEEE Transactions on Communications, 2010Co-Authors: Hussein Hijazi, Laurent RosAbstract:This paper deals with the case of a high speed mobile receiver operating in an orthogonal-frequency-division multiplexing (OFDM) communication system. Assuming the knowledge of delay-related information, we propose an iterative algorithm for joint multi-path Rayleigh Channel complex gains and data recovery in fast fading environments. Each complex gain time-variation, within one OFDM symbol, is approximated by a polynomial representation. Based on the Jakes process, an autoregressive (AR) model of the polynomial coefficients dynamics is built, making it possible to employ the Kalman filter estimator for the polynomial coefficients. Hence, the Channel matrix is easily computed, and the data symbol is estimated with free inter-sub-carrier-interference (ICI) thanks to the use of a QRdecomposition of the Channel matrix. Our claims are supported by theoretical analysis and simulation results, which are obtained considering Jakes' Channels with high Doppler spreads.
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Bayesian Cramer-Rao Bounds for Complex Gain Parameters Estimation of Slowly Varying Rayleigh Channel in OFDM Systems
Signal Processing, 2009Co-Authors: Hussein Hijazi, Laurent RosAbstract:This paper deals with on-line Bayesian Cramer-Rao (BCRB) lower bound for complex gains dynamic estimation of time-varying multi-path Rayleigh Channel. We propose three novel lower bounds for 4-QAM OFDM systems in case of negligible Channel variation within one symbol, and assuming both Channel delay and Doppler frequency related information. We derive true BCRB for data-aided (DA) context and, two closed-form expressions for non-data aided (NDA) context.
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Analytical Analysis of Bayesian Cramer-Rao Bound for Dynamical Rayleigh Channel Complex Gains Estimation in OFDM System
IEEE Transactions on Signal Processing, 2009Co-Authors: Hussein Hijazi, Laurent RosAbstract:In this paper, we consider the Bayesian Cramer- Rao bound (BCRB) for the dynamical estimation of multi-path Rayleigh Channel complex gains in data-aided (DA) and nondata-aided (NDA) OFDM systems. This bound is derived in an on-line and off-line scenarios for time-invariant and time-varying complex gains within one OFDM symbol, assuming the availability of prior information. In NDA context, whereas this true BCRB is hard to evaluate, we present a closed-form expression of a BCRB, i.e., the Asymptotic BCRB (ABCRB) or the Modified BCRB (MBCRB). We discuss, based on the theoretical and simulation results, the interest of using somepast and future observations in terms of Doppler spread for the complex gains estimation.
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On-line Bayesian Cramer-Rao Bounds for OFDM Slowly Varying Rayleigh Multi-path Channel Estimation
2008Co-Authors: Hussein Hijazi, Laurent RosAbstract:The on-line Bayesian Cramer-Rao (BCRB) lower bound for the dynamic estimation of a time-varying multi-path Rayleigh Channel in 4-QAM OFDM system is considered. In case of negligible Channel variation within one symbol and delay related information, true BCRB for data-aided (DA) context, and two closed-form expressions for non-data aided (NDA) context are derived.
Laurent Ros - One of the best experts on this subject based on the ideXlab platform.
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Joint Data QR-Detection and Kalman Estimation for OFDM Time-varying Rayleigh Channel Complex Gains
IEEE Transactions on Communications, 2010Co-Authors: Hussein Hijazi, Laurent RosAbstract:This paper deals with the case of a high speed mobile receiver operating in an orthogonal-frequency-division multiplexing (OFDM) communication system. Assuming the knowledge of delay-related information, we propose an iterative algorithm for joint multi-path Rayleigh Channel complex gains and data recovery in fast fading environments. Each complex gain time-variation, within one OFDM symbol, is approximated by a polynomial representation. Based on the Jakes process, an autoregressive (AR) model of the polynomial coefficients dynamics is built, making it possible to employ the Kalman filter estimator for the polynomial coefficients. Hence, the Channel matrix is easily computed, and the data symbol is estimated with free inter-sub-carrier-interference (ICI) thanks to the use of a QRdecomposition of the Channel matrix. Our claims are supported by theoretical analysis and simulation results, which are obtained considering Jakes' Channels with high Doppler spreads.
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Bayesian Cramer-Rao Bounds for Complex Gain Parameters Estimation of Slowly Varying Rayleigh Channel in OFDM Systems
Signal Processing, 2009Co-Authors: Hussein Hijazi, Laurent RosAbstract:This paper deals with on-line Bayesian Cramer-Rao (BCRB) lower bound for complex gains dynamic estimation of time-varying multi-path Rayleigh Channel. We propose three novel lower bounds for 4-QAM OFDM systems in case of negligible Channel variation within one symbol, and assuming both Channel delay and Doppler frequency related information. We derive true BCRB for data-aided (DA) context and, two closed-form expressions for non-data aided (NDA) context.
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Analytical Analysis of Bayesian Cramer-Rao Bound for Dynamical Rayleigh Channel Complex Gains Estimation in OFDM System
IEEE Transactions on Signal Processing, 2009Co-Authors: Hussein Hijazi, Laurent RosAbstract:In this paper, we consider the Bayesian Cramer- Rao bound (BCRB) for the dynamical estimation of multi-path Rayleigh Channel complex gains in data-aided (DA) and nondata-aided (NDA) OFDM systems. This bound is derived in an on-line and off-line scenarios for time-invariant and time-varying complex gains within one OFDM symbol, assuming the availability of prior information. In NDA context, whereas this true BCRB is hard to evaluate, we present a closed-form expression of a BCRB, i.e., the Asymptotic BCRB (ABCRB) or the Modified BCRB (MBCRB). We discuss, based on the theoretical and simulation results, the interest of using somepast and future observations in terms of Doppler spread for the complex gains estimation.
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On-line Bayesian Cramer-Rao Bounds for OFDM Slowly Varying Rayleigh Multi-path Channel Estimation
2008Co-Authors: Hussein Hijazi, Laurent RosAbstract:The on-line Bayesian Cramer-Rao (BCRB) lower bound for the dynamic estimation of a time-varying multi-path Rayleigh Channel in 4-QAM OFDM system is considered. In case of negligible Channel variation within one symbol and delay related information, true BCRB for data-aided (DA) context, and two closed-form expressions for non-data aided (NDA) context are derived.
Tomas J Entrambasaguas - One of the best experts on this subject based on the ideXlab platform.
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capacity with explicit delay guarantees for generic sources over correlated Rayleigh Channel
IEEE Transactions on Wireless Communications, 2010Co-Authors: Beatriz Soret, Carmen M Aguayotorres, Tomas J EntrambasaguasAbstract:This work analyzes the joint influence of Channel fading and the data outsourcing process in the QoS metrics of a wireless system. As a first contribution, expressions of the Channel effective bandwidth function (also known as effective capacity) for time-correlated Rayleigh fading under different adaptive rate policies are obtained. This result allows us to analytically evaluate the maximum constant information rate that can be transmitted over the Channel under a probabilistic delay constraint. Later, this Capacity with Probabilistic Delay Constraint CDt, e is generalized for systems with non-constant sources and simple closed-form expressions able to capture the influence of source processes in the probability of over-delay are given. Figures on how much the maximum allowable rate decreases for shorter allowable delays or for more changing rate sources are shown and the expected delay violation is compared to simulations in order to validate our results.
Beatriz Soret - One of the best experts on this subject based on the ideXlab platform.
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capacity with explicit delay guarantees for generic sources over correlated Rayleigh Channel
IEEE Transactions on Wireless Communications, 2010Co-Authors: Beatriz Soret, Carmen M Aguayotorres, Tomas J EntrambasaguasAbstract:This work analyzes the joint influence of Channel fading and the data outsourcing process in the QoS metrics of a wireless system. As a first contribution, expressions of the Channel effective bandwidth function (also known as effective capacity) for time-correlated Rayleigh fading under different adaptive rate policies are obtained. This result allows us to analytically evaluate the maximum constant information rate that can be transmitted over the Channel under a probabilistic delay constraint. Later, this Capacity with Probabilistic Delay Constraint CDt, e is generalized for systems with non-constant sources and simple closed-form expressions able to capture the influence of source processes in the probability of over-delay are given. Figures on how much the maximum allowable rate decreases for shorter allowable delays or for more changing rate sources are shown and the expected delay violation is compared to simulations in order to validate our results.
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On finite state Markov chains for Rayleigh Channel modeling
2009 1st International Conference on Wireless Communication Vehicular Technology Information Theory and Aerospace & Electronic Systems Technology, 2009Co-Authors: José Luis García Ruiz, Beatriz Soret, M. Carmen Aguayo-torres, J. Tomas EntrambasaguasAbstract:The use of finite state Markov chains (FSMC) for the simulation of the Rayleigh Channel has been generalized in the last years. Several parameters influence the construction of the chain. The chain can be defined in terms of the complex Channel response, the envelope of the received signal or the Signal to Noise Ratio. Moreover the partition method has to be selected among various options. This paper presents an evaluation of the FSMC, including a novel partition method that makes a uniform division of the density function of the desired signal and a comparison with other methods of generation of the fading Channel. First and second order statistics and other performance parameters are examined in order to shed more light on the advantages and limitations of the Markov modeling.
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ICC - Capacity with Probabilistic Delay Constraint for Voice Traffic in a Rayleigh Channel
2009 IEEE International Conference on Communications, 2009Co-Authors: Beatriz Soret, Mari Carmen Aguayo-torres, Jose Tomas EntrambasaguasAbstract:The Capacity with Probabilistic Delay Constraint CDt,Ɛ expresses the maximum source rate that may be supported in a wireless system with a probability Ɛ of exceeding certain delay bound Dt. In [1], CDt,Ɛ was calculated for a Rayleigh Channel carrying a constant rate flow. In this work, the potential of the effective bandwidth theory is shown by evaluating this constrained capacity for a variable rate source modeled as an ON-OFF process. Cross relations among ON-OFF process parameters, fading Channel statistics, QoS constraints and maximum allowable mean source rate are displayed by the obtained closed-form expressions. CDt,Ɛ is measured in different scenarios to exhibit to which extent higher time-correlation of the Channel response or longer ON-OFF periods are harmful to the delay behaviour, getting a lower value of the capacity CDt,Ɛ.
E Lutz - One of the best experts on this subject based on the ideXlab platform.
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packet error rate in the non interleaved Rayleigh Channel
IEEE Transactions on Communications, 1995Co-Authors: H Bischl, E LutzAbstract:Two analytical methods for determining the packet error rate in the non-interleaved Rayleigh fading Channel are presented. The first method is an exact evaluation of the packet error rate, whereas the second method is based on a k-state digital Channel model. The fading model is a nonfrequency selective Rayleigh fading with a first-order low pass spectrum for the quadrature fading components. The analytical methods are complemented by simulations. The influence of the fading bandwidth on the packet error rate and the packet throughput is discussed. Block codes as well as convolutional codes are considered. The results show that without forward error correction the throughput for slow fading is higher than for fast fading. With forward error correction the packet error rate is sensitive to the fading bandwidth. Furthermore it is shown that the convolutional code with intra packet interleaving is least sensitive to slow fading. >
