The Experts below are selected from a list of 67113 Experts worldwide ranked by ideXlab platform
M Weinert - One of the best experts on this subject based on the ideXlab platform.
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revealing the substrate origin of the Linear Dispersion of silicene ag 111
Nano Letters, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3 × 3) silicene monolayer on (4 × 4) Ag(111) is investigated using density functional theory. A k-projection technique that includes the k⊥-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1 × 1) silicene but also demonstrate that these originate from the k⊥-dependence of Ag(111) substrate states (modified by interactions with the silicene) and not from a Dirac state.
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Revealing the substrate origin of the Linear Dispersion of silicene/Ag(111)
Nano letters, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3$\times$3) silicene monolayer on (4$\times$4) Ag(111) is investigated using density functional theory. A $k$-projection technique that includes the $k_\bot$-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1$\times$1) silicene, but also demonstrate that these originate from the $k_\bot$-dependence of Ag(111) substrate states (modified by interactions with the silicene) and \textit{not} from a Dirac state.
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revealing the substrate origin of the Linear Dispersion of silicene ag 111
arXiv: Materials Science, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3$\times$3) silicene monolayer on (4$\times$4) Ag(111) is investigated using density functional theory. A $k$-projection technique that includes the $k_\bot$-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1$\times$1) silicene, but also demonstrate that these originate from the $k_\bot$-dependence of Ag(111) substrate states (modified by interactions with the silicene) and \textit{not} from a Dirac state.
Steven D. Blostein - One of the best experts on this subject based on the ideXlab platform.
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Rectangular information lossless Linear Dispersion codes
IEEE Transactions on Wireless Communications, 2010Co-Authors: Steven D. BlosteinAbstract:This paper extends square M×M Linear Dispersion codes (LDC) proposed by Hassibi and Hochwald to T×M non-square Linear Dispersion codes of the same rate M, termed uniform LDC, or U-LDC. This paper establishes a unitary property of arbitrary rectangular U-LDC encoding matrices and determines their connection to the traceless minimal nonorthogonality criterion for space-time codes. The U-LDC are then applied to rapid fading channels by constructing trace-orthonormal versions, or TON-U-LDC for 2L and 4L input symbols, where L is a positive integer. Compared to a variety of state-of-the-art codes, the proposed codes are found to perform well in both block and rapid fading channels. In rapid fading, the symbol-wise time diversity order of a T × M, TON-U-LDC for 2L input symbols is shown to be min (T,2M).
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ISIT - Space-time Linear Dispersion Using Coordinate Interleaving
2006 IEEE International Symposium on Information Theory, 2006Co-Authors: Steven D. BlosteinAbstract:This paper proposes a general coordinate-interleaving method for block-based space-time codes or Linear Dispersion codes, called space-time coordinate interleaving Linear Dispersion codes (ST-CILDC), which enables not only symbol-level diversity but also coordinate-level diversity for high rate block-based space-time code design. This paper analyzes the upper bound diversity order and provides the analysis results of the upper bound statistical diversity order and average diversity order for ST-CILDC systems. Compared with conventional ST-LDC systems, ST-CILDC systems may show either almost doubled average diversity order or extra coding advantage in time varying channels. With trivial extra complexity over ST-LDC systems, ST-CILDC systems maintain the diversity performance in quasi-static block fading channels, and significantly improve the diversity performance in rapid fading channels.
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ICC - Linear Dispersion over time and frequency
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004Co-Authors: Steven D. BlosteinAbstract:High rate Linear Dispersion codes (LDC) for space time channels can support arbitrary numbers of transmit and receive antennas. In contrast to the one-to-one transformations used in interleaving, these codes disperse data in Linear combinations over space and time. To improve performance of orthogonal frequency division multiplexing (OFDM) for wireless fading channels, this paper investigates increasing frequency and time diversity using LDC. To overcome the requirement of constant channel gains over an entire LDC time interval, a new decoding algorithm for a special subclass of LDC is proposed. The newly proposed LDC-OFDM Linearly disperses data over both time and frequency, i.e., over multiple subcarriers and OFDM blocks. Simulations show the bit error rate (BER) performance of rate-one LDC-OFDM with zero padding is superior to that of uncoded OFDM with zero padding. Further, compared to uncoded OFDM, LDC-OFDM may have improved performance without increasing the peak-to-average power ratio (PAPR).
Mohammad Madihian - One of the best experts on this subject based on the ideXlab platform.
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ICC - Optimizing Linear Dispersion Codes for Wideband MIMO Systems
2007 IEEE International Conference on Communications, 2007Co-Authors: Luca Venturino, Xiaodong Wang, N. Prasad, Mohammad MadihianAbstract:We consider the problem of designing space-time- frequency Linear Dispersion (LD) codes in wideband multiple- input multiple-output (MIMO) antenna systems employing orthogonal-frequency-division-multiplexing (OFDM). Three design methods are presented and discussed, which involve: (1) minimizing the average block error rate, (2) maximizing the ergodic mutual information, and (3) a two-step procedure considering the optimization of the mutual information as well as the average block error rate, respectively. For any set of subcarriers, any number of OFDM symbol intervals, any number of transmit/receive antennas and any statistical fading channel model, the corresponding optimized LD code matrices are numerically computed via a stochastic gradient descent algorithm. Code design examples are provided and discussed for communication systems operating over a realistic 3GPP spatial channel model.
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On the optimum design of space-time Linear-Dispersion codes
IEEE Transactions on Wireless Communications, 2005Co-Authors: Jibing Wang, Xiaodong Wang, Mohammad MadihianAbstract:In this paper, we propose to design Linear-Dispersion (LD) codes by minimizing the union bound based on the exact pairwise error probability (PEP). We find that the original programming is not convex, and we present a convex relaxation to the optimization problem. We employ the gradient descent methods to numerically search the optimum Dispersion matrices. Simulation results show that codes optimized by the new criterion generally outperform the codes designed based on algebraic number theory. When the knowledge of spatial-fading correlation is available in advance for the design, significant gain relative to the codes designed without knowledge of channel correlation can be achieved by taking into account the correlation structure while performing the optimization. We demonstrate how to exploit knowledge of transmit and receive correlation in designing the LD codes. Numerical and simulation examples show that knowledge of transmit correlation has a large impact on the optimum performance of the LD codes. Furthermore, additional gain can be achieved from the knowledge of receive correlation.
S Pasupathy - One of the best experts on this subject based on the ideXlab platform.
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Widely Linear MMSE Receivers for Linear Dispersion Space-Time Block-Codes
2016Co-Authors: Amirhossein S Aghaei, Konstantinos N Plataniotis, S Pasupathy, Student Member, Senior Member, Life FellowAbstract:Abstract—This paper proposes a new receiver structure for Linear-Dispersion (LD) codes, subsuming orthogonal, quasi-orthogonal and V-BLAST codes. We suggest to use widely-Linear minimum-mean-squared-error (WL-MMSE) estimates of trans-mitted symbols in lieu of the sufficient statistics for maximum likelihood (ML) detection of these symbols. Proposed structure offers both optimal (ML) and suboptimal solutions. Simulation results show that the suboptimal receiver performs close to the optimal one, while reducing the receiver’s complexity. Structure of the proposed receiver is particularly studied for orthogonal and quasi-orthogonal LD codes. Specifically, it is proved that Alamouti’s combining scheme provides WL-MMSE estimates of the transmitted symbols. Index Terms—Improper complex random vector, Linear dis-persion codes, MIMO systems, space-time codes, widely-Linear estimation. I
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widely Linear mmse receivers for Linear Dispersion space time block codes
IEEE Transactions on Wireless Communications, 2010Co-Authors: Amirhossein S Aghaei, Konstantinos N Plataniotis, S PasupathyAbstract:This paper proposes a new receiver structure for Linear-Dispersion (LD) codes, subsuming orthogonal, quasiorthogonal and V-BLAST codes. We suggest to use widely-Linear minimum-mean-squared-error (WL-MMSE) estimates of transmitted symbols in lieu of the sufficient statistics for maximum likelihood (ML) detection of these symbols. Proposed structure offers both optimal (ML) and suboptimal solutions. Simulation results show that the suboptimal receiver performs close to the optimal one, while reducing the receiver's complexity. Structure of the proposed receiver is particularly studied for orthogonal and quasi-orthogonal LD codes. Specifically, it is proved that Alamouti's combining scheme provides WL-MMSE estimates of the transmitted symbols.
M X Chen - One of the best experts on this subject based on the ideXlab platform.
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revealing the substrate origin of the Linear Dispersion of silicene ag 111
Nano Letters, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3 × 3) silicene monolayer on (4 × 4) Ag(111) is investigated using density functional theory. A k-projection technique that includes the k⊥-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1 × 1) silicene but also demonstrate that these originate from the k⊥-dependence of Ag(111) substrate states (modified by interactions with the silicene) and not from a Dirac state.
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Revealing the substrate origin of the Linear Dispersion of silicene/Ag(111)
Nano letters, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3$\times$3) silicene monolayer on (4$\times$4) Ag(111) is investigated using density functional theory. A $k$-projection technique that includes the $k_\bot$-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1$\times$1) silicene, but also demonstrate that these originate from the $k_\bot$-dependence of Ag(111) substrate states (modified by interactions with the silicene) and \textit{not} from a Dirac state.
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revealing the substrate origin of the Linear Dispersion of silicene ag 111
arXiv: Materials Science, 2014Co-Authors: M X Chen, M WeinertAbstract:The band structure of the recently synthesized (3$\times$3) silicene monolayer on (4$\times$4) Ag(111) is investigated using density functional theory. A $k$-projection technique that includes the $k_\bot$-dependence of the surface bands is used to separate the contributions arising from the silicene and the substrate, allowing a consistent comparison between the calculations and the angle-resolved photoemission experiments. Our calculations not only reproduce the observed gap and Linear Dispersion across the K point of (1$\times$1) silicene, but also demonstrate that these originate from the $k_\bot$-dependence of Ag(111) substrate states (modified by interactions with the silicene) and \textit{not} from a Dirac state.