The Experts below are selected from a list of 49077 Experts worldwide ranked by ideXlab platform
Mohamed-slim Alouini - One of the best experts on this subject based on the ideXlab platform.
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On the average outage rate and average outage duration of wireless communication systems with multiple cochannel interferers
IEEE Transactions on Wireless Communications, 2004Co-Authors: Lin Yang, Mohamed-slim AlouiniAbstract:This paper studies the average outage rate [or average level crossing rate (LCR)] and average outage duration (AOD) of wireless communication systems subject to cochannel interference. In particular, it presents closed-form expressions for the LCR and AOD when a minimum Desired Signal power requirement is specified for satisfactory reception. The results are quite general and account for systems operating over independent identically distributed Rician and/or Nakagami fading environments. When applicable, these new expressions are compared to those previously reported in the literature dealing with the LCR and AOD of 1) interference-limited systems when both the Desired and interfering Signals are subject to Rayleigh type of fading and 2) power-limited systems operating over Rician or Nakagami fading channels. Corresponding numerical examples that illustrate applications of the results are also provided and discussed. These results show that specifying a certain minimum Desired Signal power requirement induces a floor on the AOD. They also show that the AOD is essentially affected by the the maximum Doppler frequencies (or equivalently the speed) of the Desired users.
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average outage duration of multiuser wireless communication systems with a minimum Signal power requirement
Vehicular Technology Conference, 2002Co-Authors: Lin Yang, Mohamed-slim AlouiniAbstract:This paper deals with the average outage duration (AOD) of wireless communication systems subject to cochannel interference. In particular, it presents closed-form expressions for the AOD when a minimum Desired Signal power requirement is specified for satisfactory reception. The results are quite general and account for systems operating over Rician and/or Nakagami fading environments. When applicable, these new expressions are compared to those previously reported in the literature dealing with the AOD of (i) interference-limited systems when both the Desired and interfering Signals are subject to Rayleigh type of fading and (ii) power-limited systems operating over Rician or Nakagami fading channels. Corresponding numerical examples that illustrate applications of the results are also provided and discussed. These results show that specifying a certain minimum Desired Signal power requirement induces a floor on the AOD. They also show that the AOD is essentially affected by the the maximum Doppler frequencies (or equivalently the speed) of the Desired users.
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on the difference of two chi square variates with application to outage probability computation
IEEE Transactions on Communications, 2001Co-Authors: M K Simon, Mohamed-slim AlouiniAbstract:An expression for the cumulative distribution function evaluated at zero of the difference of two chi-square variates with different number of degrees of freedom is derived and applied to the outage probability computation of cellular mobile radio systems in fading channels. In particular, a generic result is developed for this probability which takes on several forms, the simplest of which, is a single integral with finite limits and an integrand composed of elementary (exponential and trigonometric) functions. The results are applicable to cellular systems that are subject to independent identically distributed (i.i.d.) interfering Signals and that employ maximal-ratio combining reception over i.i.d. diversity paths. Various fading channel models are assumed for the Desired Signal and interferers. For each Desired Signal/interferer combination, the outage probability is expressed in closed form in terms of a set of parameters that characterize the particular scenario. A tabulation of these various scenarios and their associated parameters for channels of practical interest is included.
Lin Yang - One of the best experts on this subject based on the ideXlab platform.
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On the average outage rate and average outage duration of wireless communication systems with multiple cochannel interferers
IEEE Transactions on Wireless Communications, 2004Co-Authors: Lin Yang, Mohamed-slim AlouiniAbstract:This paper studies the average outage rate [or average level crossing rate (LCR)] and average outage duration (AOD) of wireless communication systems subject to cochannel interference. In particular, it presents closed-form expressions for the LCR and AOD when a minimum Desired Signal power requirement is specified for satisfactory reception. The results are quite general and account for systems operating over independent identically distributed Rician and/or Nakagami fading environments. When applicable, these new expressions are compared to those previously reported in the literature dealing with the LCR and AOD of 1) interference-limited systems when both the Desired and interfering Signals are subject to Rayleigh type of fading and 2) power-limited systems operating over Rician or Nakagami fading channels. Corresponding numerical examples that illustrate applications of the results are also provided and discussed. These results show that specifying a certain minimum Desired Signal power requirement induces a floor on the AOD. They also show that the AOD is essentially affected by the the maximum Doppler frequencies (or equivalently the speed) of the Desired users.
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average outage duration of multiuser wireless communication systems with a minimum Signal power requirement
Vehicular Technology Conference, 2002Co-Authors: Lin Yang, Mohamed-slim AlouiniAbstract:This paper deals with the average outage duration (AOD) of wireless communication systems subject to cochannel interference. In particular, it presents closed-form expressions for the AOD when a minimum Desired Signal power requirement is specified for satisfactory reception. The results are quite general and account for systems operating over Rician and/or Nakagami fading environments. When applicable, these new expressions are compared to those previously reported in the literature dealing with the AOD of (i) interference-limited systems when both the Desired and interfering Signals are subject to Rayleigh type of fading and (ii) power-limited systems operating over Rician or Nakagami fading channels. Corresponding numerical examples that illustrate applications of the results are also provided and discussed. These results show that specifying a certain minimum Desired Signal power requirement induces a floor on the AOD. They also show that the AOD is essentially affected by the the maximum Doppler frequencies (or equivalently the speed) of the Desired users.
Jose C Principe - One of the best experts on this subject based on the ideXlab platform.
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training neural networks with additive noise in the Desired Signal
IEEE Transactions on Neural Networks, 1999Co-Authors: Chuan Wang, Jose C PrincipeAbstract:A global optimization strategy for training adaptive systems such as neural networks and adaptive filters (finite or infinite impulse response) is proposed. Instead of adding random noise to the weights as proposed in the past, additive random noise is injected directly into the Desired Signal. Experimental results show that this procedure also speeds up greatly the backpropagation algorithm. The method is very easy to implement in practice, preserving the backpropagation algorithm and requiring a single random generator with a monotonically decreasing step size per output channel. Hence, this is an ideal strategy to speed up supervised learning, and avoid local minima entrapment when the noise variance is appropriately scheduled.
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training neural networks with additive noise in the Desired Signal
International Joint Conference on Neural Network, 1998Co-Authors: Chuan Wang, Jose C PrincipeAbstract:A new global optimization strategy for training adaptive systems such as neural networks and adaptive filters (finite or infinite impulse response (FIR or IIR)) is proposed in this paper. Instead of adding random noise to the weights as proposed in the past, additive random noise is injected directly into the Desired Signal. Experimental results show that this procedure also speeds up greatly the backpropagation algorithm. The method is very easy to implement in practice, preserving the backpropagation algorithm and requiring a single random generator with a monotonically decreasing step size per output channel. Hence, this is an ideal strategy to speed up supervised learning, and avoid local minima entrapment when the noise variance is appropriately scheduled.
J H Winters - One of the best experts on this subject based on the ideXlab platform.
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Signal acquisition and tracking with adaptive arrays in the digital mobile radio system is 54 with flat fading
IEEE Transactions on Vehicular Technology, 1993Co-Authors: J H WintersAbstract:The author considers the dynamic performance of adaptive arrays in wireless communication systems. With an adaptive array, the Signals received by multiple antennas are weighted and combined to suppress interference and combat Desired Signal fading. In these systems, the weight adaptation algorithm must acquire and track the weights even with rapid fading. The author considers the performance of the least-mean-square (LMS) and direct matrix inversion (DMI) algorithms in the North American digital mobile radio system IS-54. He shows that implementation of these algorithms permits the use of coherent detection, which improves performance by 1 dB over differential detection. Results for two base station antennas with flat Rayleigh fading show that the LMS algorithm has large tracking loss for vehicle speeds above 20 mph, but the DMI algorithm can acquire and track the weights to combat Desired Signal fading at vehicle speeds up to 60 mph with less than 0.2 dB degradation from ideal performance with differential detection. Similarly, interference is also suppressed with performance gains over maximal ratio combining within 0.5 dB of the predicted ideal gain. >
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Signal acquisition and tracking with adaptive arrays in wireless systems
Vehicular Technology Conference, 1993Co-Authors: J H WintersAbstract:The dynamic performance of adaptive arrays in wireless communication systems is considered. With an adaptive array, the Signals received by multiple antennas are weighted and combined to suppress interference and combat Desired-Signal fading. In these systems, the weight adaptation algorithm must acquire and track the weights even with rapid fading. The performance of the least-mean-square (LMS) and direct matrix inversion (DMI) algorithms in the digital mobile radio system IS-54 is considered. Results for two base station antennas with flat Rayleigh fading show that the LMS algorithm has large tracking loss for vehicle speeds above 20 mph, and that the DMI algorithm can acquire and track the weights to combat Desired-Signal fading and suppress interference with close to ideal tracking performance at vehicle speeds up to 60 mph.
Amir Leshem - One of the best experts on this subject based on the ideXlab platform.
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robust adaptive beamforming based on interference covariance matrix reconstruction and steering vector estimation
IEEE Transactions on Signal Processing, 2012Co-Authors: Yujie Gu, Amir LeshemAbstract:Adaptive beamformers are sensitive to model mismatch, especially when the Desired Signal is present in training snapshots or when the training is done using data samples. In contrast to previous works, this correspondence attempts to reconstruct the interference-plus-noise covariance matrix instead of searching for the optimal diagonal loading factor for the sample covariance matrix. The estimator is based on the Capon spectral estimator integrated over a region separated from the Desired Signal direction. This is shown to be more robust than using the sample covariance matrix. Subsequently, the mismatch in the steering vector of the Desired Signal is estimated by maximizing the beamformer output power under a constraint that prevents the corrected steering vector from getting close to the interference steering vectors. The proposed adaptive beamforming algorithm does not impose a norm constraint. Therefore, it can be used even in applications where gain perturbations affect the steering vector. Simulation results demonstrate that the performance of the proposed adaptive beamformer is almost always close to the optimal value across a wide range of Signal to noise and Signal to interference ratios.