The Experts below are selected from a list of 4647 Experts worldwide ranked by ideXlab platform
Aria Nosratinia - One of the best experts on this subject based on the ideXlab platform.
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spatially correlated mimo broadcast channel with partially overlapping correlation Eigenspaces
International Symposium on Information Theory, 2018Co-Authors: Fan Zhang, Aria NosratiniaAbstract:The spatially correlated MIMO broadcast channel has grown in importance due to emerging interest in massive MIMO and mm-wave communication, but much about this channel remains unknown. In this paper, we study a two-user MIMO broadcast channel where the spatial correlation matrices corresponding to the two receivers have Eigenspaces that are neither identical nor disjoint, but are partially overlapped. Spatially correlated channels occur in e.g. massive MIMO and furthermore different links may credibly have correlation Eigenspaces that are neither disjoint nor equal, therefore this problem is practically motivated. This paper develops a new approach for this scenario and calculates the corresponding degrees of freedom. Our technique involves a careful decomposition of the signaling space to allow a combination of pre-beamforming along directions that depend on the relative positioning of the non-overlapping and overlapping components of the Eigenspaces, along with the product superposition technique. The ideas are demonstrated with a toy example, are developed in two conditions of varying complexity, and are illuminated by numerical results.
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spatially correlated mimo broadcast channel analysis of overlapping correlation Eigenspaces
International Symposium on Information Theory, 2017Co-Authors: Fan Zhang, Mohamed Fadel, Aria NosratiniaAbstract:Antenna correlation is prevalent in higher frequencies as well as in massive MIMO, thus the study of correlated MIMO broadcast channels is becoming a subject of increasing interest. This paper explores the fundamental limits of such systems, focusing on cases where correlation Eigenspaces are neither independent nor identical, so that known beam-space division techniques do not directly apply. We begin by introducing a simple but novel tight outer bound on the degrees of freedom of noncoherent point-to-point MIMO channels under transmit antenna correlation. We then analyze the performance of a two-user MIMO broadcast channel when one correlation eigenspace is a subspace of the other. We extend the result to K-user MIMO broadcast channel. Our results show that it is possible to exploit the differences between the correlation structure of transmit antennas towards different receivers to extract degrees of freedom gains out of the system. The extent of these gains are highlighted via several examples.
Mohammad Reza Yousefi - One of the best experts on this subject based on the ideXlab platform.
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teacher directed learning in view independent face recognition with mixture of experts using overlapping Eigenspaces
Computer Vision and Image Understanding, 2008Co-Authors: Reza Ebrahimpour, Ehsanollah Kabir, Mohammad Reza YousefiAbstract:A model for view-independent face recognition, based on Mixture of Experts, ME, is presented. In the basic form of ME the problem space is automatically divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our proposed model, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a particular partitioning corresponding to predetermined views, a new representation scheme, overlapping Eigenspaces, is introduced, that provides each expert with an eigenspace computed from the faces in the corresponding neighboring views. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding experts are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of the face space improves the performance of the conventional ME for view-independent face recognition. Comparison with some of the most related methods indicates that the proposed model yields excellent recognition rate in view-independent face recognition.
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teacher directed learning in view independent face recognition with mixture of experts using single view Eigenspaces
Journal of The Franklin Institute-engineering and Applied Mathematics, 2008Co-Authors: Reza Ebrahimpour, Ehsanollah Kabir, Mohammad Reza YousefiAbstract:Abstract We propose a new model for view-independent face recognition by multiview approach. We use the so-called “mixture of experts”, ME, in which, the problem space is divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our model, instead of leaving the ME to partition the face space automatically, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a specific view of face, in the representation layer, we provide each expert with its own eigenspace computed from the faces in the corresponding view. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding expert are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of face space improves the performance of the conventional ME for view-independent face recognition. In particular, for 1200 images of unseen intermediate views of faces from 20 subjects, the ME with single-view Eigenspaces yields the average recognition rate of 80.51% in 10 trials, which is noticeably increased to 90.29% by applying the TDL method.
Fan Zhang - One of the best experts on this subject based on the ideXlab platform.
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spatially correlated mimo broadcast channel with partially overlapping correlation Eigenspaces
International Symposium on Information Theory, 2018Co-Authors: Fan Zhang, Aria NosratiniaAbstract:The spatially correlated MIMO broadcast channel has grown in importance due to emerging interest in massive MIMO and mm-wave communication, but much about this channel remains unknown. In this paper, we study a two-user MIMO broadcast channel where the spatial correlation matrices corresponding to the two receivers have Eigenspaces that are neither identical nor disjoint, but are partially overlapped. Spatially correlated channels occur in e.g. massive MIMO and furthermore different links may credibly have correlation Eigenspaces that are neither disjoint nor equal, therefore this problem is practically motivated. This paper develops a new approach for this scenario and calculates the corresponding degrees of freedom. Our technique involves a careful decomposition of the signaling space to allow a combination of pre-beamforming along directions that depend on the relative positioning of the non-overlapping and overlapping components of the Eigenspaces, along with the product superposition technique. The ideas are demonstrated with a toy example, are developed in two conditions of varying complexity, and are illuminated by numerical results.
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spatially correlated mimo broadcast channel analysis of overlapping correlation Eigenspaces
International Symposium on Information Theory, 2017Co-Authors: Fan Zhang, Mohamed Fadel, Aria NosratiniaAbstract:Antenna correlation is prevalent in higher frequencies as well as in massive MIMO, thus the study of correlated MIMO broadcast channels is becoming a subject of increasing interest. This paper explores the fundamental limits of such systems, focusing on cases where correlation Eigenspaces are neither independent nor identical, so that known beam-space division techniques do not directly apply. We begin by introducing a simple but novel tight outer bound on the degrees of freedom of noncoherent point-to-point MIMO channels under transmit antenna correlation. We then analyze the performance of a two-user MIMO broadcast channel when one correlation eigenspace is a subspace of the other. We extend the result to K-user MIMO broadcast channel. Our results show that it is possible to exploit the differences between the correlation structure of transmit antennas towards different receivers to extract degrees of freedom gains out of the system. The extent of these gains are highlighted via several examples.
Reza Ebrahimpour - One of the best experts on this subject based on the ideXlab platform.
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teacher directed learning in view independent face recognition with mixture of experts using overlapping Eigenspaces
Computer Vision and Image Understanding, 2008Co-Authors: Reza Ebrahimpour, Ehsanollah Kabir, Mohammad Reza YousefiAbstract:A model for view-independent face recognition, based on Mixture of Experts, ME, is presented. In the basic form of ME the problem space is automatically divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our proposed model, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a particular partitioning corresponding to predetermined views, a new representation scheme, overlapping Eigenspaces, is introduced, that provides each expert with an eigenspace computed from the faces in the corresponding neighboring views. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding experts are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of the face space improves the performance of the conventional ME for view-independent face recognition. Comparison with some of the most related methods indicates that the proposed model yields excellent recognition rate in view-independent face recognition.
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teacher directed learning in view independent face recognition with mixture of experts using single view Eigenspaces
Journal of The Franklin Institute-engineering and Applied Mathematics, 2008Co-Authors: Reza Ebrahimpour, Ehsanollah Kabir, Mohammad Reza YousefiAbstract:Abstract We propose a new model for view-independent face recognition by multiview approach. We use the so-called “mixture of experts”, ME, in which, the problem space is divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our model, instead of leaving the ME to partition the face space automatically, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a specific view of face, in the representation layer, we provide each expert with its own eigenspace computed from the faces in the corresponding view. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding expert are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of face space improves the performance of the conventional ME for view-independent face recognition. In particular, for 1200 images of unseen intermediate views of faces from 20 subjects, the ME with single-view Eigenspaces yields the average recognition rate of 80.51% in 10 trials, which is noticeably increased to 90.29% by applying the TDL method.
Pierre Magal - One of the best experts on this subject based on the ideXlab platform.
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projectors on the generalized Eigenspaces for neutral functional differential equations in l p spaces
Canadian Journal of Mathematics, 2010Co-Authors: Arnaud Ducrot, Zhihua Liu, Pierre MagalAbstract:We present the explicit formulas for the projectors on the generalized Eigenspaces associated with some eigenvalues for linear neutral functional differential equations (NFDE) in L p spaces by us- ing integrated semigroup theory. The analysis is based on the main result established elsewhere by the authors and results by Magal and Ruan on non-densely defined Cauchy problem. We formulate the NFDE as a non-densely defined Cauchy problem and obtain some spectral properties from which we then derive explicit formulas for the projectors on the generalized Eigenspaces associated with some eigenvalues. Such explicit formulas are important in studying bifurcations in some semi-linear prob- lems.
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projectors on the generalized Eigenspaces for functional differential equations using integrated semigroups
Journal of Differential Equations, 2008Co-Authors: Zhihua Liu, Pierre Magal, Shigui RuanAbstract:The aim of this article is to derive explicit formulas for the projectors on the generalized Eigenspaces associated to some eigenvalues for linear functional differential equations (FDE) by using integrated semigroup theory. The idea is to formulate the FDE as a non-densely defined Cauchy problem and obtain an explicit formula for the integrated solutions of the non-densely defined Cauchy problem, from which we then derive explicit formulas for the projectors on the generalized Eigenspaces associated to some eigenvalues. The results are useful in studying bifurcations in some semi-linear problems.
