The Experts below are selected from a list of 14619 Experts worldwide ranked by ideXlab platform
El A Gamal - One of the best experts on this subject based on the ideXlab platform.
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the capacity region of a class of three receiver broadcast channels with degraded message sets
IEEE Transactions on Information Theory, 2009Co-Authors: Chandra Nair, El A GamalAbstract:Korner and Marton established the capacity region for the two-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a Straightforward Extension of the Korner-Marton region to more than two receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of three-receiver broadcast channels with two-degraded message sets and show that it can be strictly larger than the Straightforward Extension of the Korner-Marton region. The idea is to split the private message into two parts, superimpose one part onto the ldquocloud centerrdquo representing the common message, and superimpose the second part onto the resulting ldquosatellite codeword.rdquo One of the receivers finds the common message directly by decoding the ldquocloud center,rdquo a second receiver finds it indirectly by decoding a satellite codeword, and a third receiver finds it by jointly decoding the transmitted codeword. This idea is then used to establish new inner and outer bounds on the capacity region of the general three-receiver broadcast channel with two and three degraded message sets. We show that these bounds are tight for some nontrivial cases. The results suggest that finding the capacity region of the three-receiver broadcast channel with degraded message sets is at least as hard finding as the capacity region of the general two-receiver broadcast channel with common and private message.
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the capacity region of a class of 3 receiver broadcast channels with degraded message sets
International Symposium on Information Theory, 2008Co-Authors: Chandra Nair, El A GamalAbstract:Korner and Marton established the capacity region for the 2-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a Straightforward Extension of the Korner-Marton region to more than 2 receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of 3-receiver broadcast channels with 2 degraded message sets and show that it can be strictly larger than the Straightforward Extension of the Korner-Marton region. The key new idea is indirect decoding, whereby a receiver who cannot directly decode a cloud center, finds it indirectly by decoding satellite codewords. This idea is then used to establish new inner bounds on the capacity region of the general 3-receiver broadcast channel with 2 and 3 degraded message sets. These bounds are tight for some nontrivial cases.
Chandra Nair - One of the best experts on this subject based on the ideXlab platform.
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an achievability scheme for the compound channel with state noncausally available at the encoder
arXiv: Information Theory, 2010Co-Authors: Chandra Nair, Abbas El Gamal, Yeowkhiang ChiaAbstract:A new achievability scheme for the compound channel with discrete memoryless (DM) state noncausally available at the encoder is established. Achievability is proved using superposition coding, Marton coding, joint typicality encoding, and indirect decoding. The scheme is shown to achieve strictly higher rate than the Straightforward Extension of the Gelfand-Pinsker coding scheme for a single DMC with DM state, and is optimal for some classes of channels.
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the capacity region of a class of three receiver broadcast channels with degraded message sets
IEEE Transactions on Information Theory, 2009Co-Authors: Chandra Nair, El A GamalAbstract:Korner and Marton established the capacity region for the two-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a Straightforward Extension of the Korner-Marton region to more than two receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of three-receiver broadcast channels with two-degraded message sets and show that it can be strictly larger than the Straightforward Extension of the Korner-Marton region. The idea is to split the private message into two parts, superimpose one part onto the ldquocloud centerrdquo representing the common message, and superimpose the second part onto the resulting ldquosatellite codeword.rdquo One of the receivers finds the common message directly by decoding the ldquocloud center,rdquo a second receiver finds it indirectly by decoding a satellite codeword, and a third receiver finds it by jointly decoding the transmitted codeword. This idea is then used to establish new inner and outer bounds on the capacity region of the general three-receiver broadcast channel with two and three degraded message sets. We show that these bounds are tight for some nontrivial cases. The results suggest that finding the capacity region of the three-receiver broadcast channel with degraded message sets is at least as hard finding as the capacity region of the general two-receiver broadcast channel with common and private message.
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the capacity region of a class of 3 receiver broadcast channels with degraded message sets
International Symposium on Information Theory, 2008Co-Authors: Chandra Nair, El A GamalAbstract:Korner and Marton established the capacity region for the 2-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a Straightforward Extension of the Korner-Marton region to more than 2 receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of 3-receiver broadcast channels with 2 degraded message sets and show that it can be strictly larger than the Straightforward Extension of the Korner-Marton region. The key new idea is indirect decoding, whereby a receiver who cannot directly decode a cloud center, finds it indirectly by decoding satellite codewords. This idea is then used to establish new inner bounds on the capacity region of the general 3-receiver broadcast channel with 2 and 3 degraded message sets. These bounds are tight for some nontrivial cases.
Zhen Zhong - One of the best experts on this subject based on the ideXlab platform.
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closed form solutions for matrix linear systems using double matrix exponential functions
International Journal of Systems Science, 2009Co-Authors: Bin Zhou, Guangren Duan, Zhen ZhongAbstract:The article presents closed form solutions for a class of matrix linear systems whose state variable is a matrix. The formulation evaluates the state response of the system in terms of the original system matrices. The proposed solutions naturally fit systems which are most described conveniently by matrix processes. Its formulation uses a compact notation referred to as double matrix exponential functions, which is an Extension of normal matrix exponential function. It is a Straightforward Extension of the solutions for ordinary vector linear systems studied in the past several decades and will play an important role in the design of matrix linear systems using original system matrices.
Bin Zhou - One of the best experts on this subject based on the ideXlab platform.
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closed form solutions for matrix linear systems using double matrix exponential functions
International Journal of Systems Science, 2009Co-Authors: Bin Zhou, Guangren Duan, Zhen ZhongAbstract:The article presents closed form solutions for a class of matrix linear systems whose state variable is a matrix. The formulation evaluates the state response of the system in terms of the original system matrices. The proposed solutions naturally fit systems which are most described conveniently by matrix processes. Its formulation uses a compact notation referred to as double matrix exponential functions, which is an Extension of normal matrix exponential function. It is a Straightforward Extension of the solutions for ordinary vector linear systems studied in the past several decades and will play an important role in the design of matrix linear systems using original system matrices.
Noah Simon - One of the best experts on this subject based on the ideXlab platform.
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convex modeling of interactions with strong heredity
Journal of Computational and Graphical Statistics, 2016Co-Authors: Asad Haris, Daniela Witten, Noah SimonAbstract:We consider the task of fitting a regression model involving interactions among a potentially large set of covariates, in which we wish to enforce strong heredity. We propose FAMILY, a very general framework for this task. Our proposal is a generalization of several existing methods, such as VANISH, hierNet, the all-pairs lasso, and the lasso using only main effects. It can be formulated as the solution to a convex optimization problem, which we solve using an efficient alternating directions method of multipliers (ADMM) algorithm. This algorithm has guaranteed convergence to the global optimum, can be easily specialized to any convex penalty function of interest, and allows for a Straightforward Extension to the setting of generalized linear models. We derive an unbiased estimator of the degrees of freedom of FAMILY, and explore its performance in a simulation study and on an HIV sequence dataset. Supplementary materials for this article are available online.
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convex modeling of interactions with strong heredity
arXiv: Machine Learning, 2014Co-Authors: Asad Haris, Daniela Witten, Noah SimonAbstract:We consider the task of fitting a regression model involving interactions among a potentially large set of covariates, in which we wish to enforce strong heredity. We propose FAMILY, a very general framework for this task. Our proposal is a generalization of several existing methods, such as VANISH [Radchenko and James, 2010], hierNet [Bien et al., 2013], the all-pairs lasso, and the lasso using only main effects. It can be formulated as the solution to a convex optimization problem, which we solve using an efficient alternating directions method of multipliers (ADMM) algorithm. This algorithm has guaranteed convergence to the global optimum, can be easily specialized to any convex penalty function of interest, and allows for a Straightforward Extension to the setting of generalized linear models. We derive an unbiased estimator of the degrees of freedom of FAMILY, and explore its performance in a simulation study and on an HIV sequence data set.
