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Luc Vandendorpe - One of the best experts on this subject based on the ideXlab platform.
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robust sum mse optimization for downlink multiuser mimo systems with Arbitrary Power constraint generalized duality approach
IEEE Transactions on Signal Processing, 2012Co-Authors: Tadilo Endeshaw Bogale, Luc VandendorpeAbstract:This paper considers linear minimum mean-square-error (MMSE) transceiver design problems for downlink multiuser multiple-input multiple-output (MIMO) systems where imperfect channel state information is available at the base station (BS) and mobile stations (MSs). We examine robust sum mean-square-error (MSE) minimization problems. The problems are examined for the generalized scenario where the Power constraint is per BS, per BS antenna, per user or per symbol, and the noise vector of each MS is a zero-mean circularly symmetric complex Gaussian random variable with Arbitrary covariance matrix. For each of these problems, we propose a novel duality based iterative solution. Each of these problems is solved as follows. First, we establish a novel sum average mean-square-error (AMSE) duality. Second, we formulate the Power allocation part of the problem in the downlink channel as a Geometric Program (GP). Third, using the duality result and the solution of GP, we utilize alternating optimization technique to solve the original downlink problem. To solve robust sum MSE minimization constrained with per BS antenna and per BS Power problems, we have established novel downlink-uplink duality. On the other hand, to solve robust sum MSE minimization constrained with per user and per symbol Power problems, we have established novel downlink-interference duality. For the total BS Power constrained robust sum MSE minimization problem, the current duality is established by modifying the constraint function of the dual uplink channel problem. And, for the robust sum MSE minimization with per BS antenna and per user (symbol) Power constraint problems, our duality are established by formulating the noise covariance matrices of the uplink and interference channels as fixed point functions, respectively. We also show that our sum AMSE duality are able to solve other sum MSE-based robust design problems. Computer simulations verify the robustness of the proposed robust designs compared to the nonrobust/naive designs.
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Robust Sum MSE optimization for downlink multiuser MIMO systems with Arbitrary Power constraint: Generalized duality approach
IEEE Transactions on Signal Processing, 2012Co-Authors: Tadilo Endeshaw Bogale, Luc VandendorpeAbstract:This paper considers linear minimum meansquare- error (MMSE) transceiver design problems for downlink multiuser multiple-input multiple-output (MIMO) systems where imperfect channel state information is available at the base station (BS) and mobile stations (MSs). We examine robust sum mean-square-error (MSE) minimization problems. The problems are examined for the generalized scenario where the Power constraint is per BS, per BS antenna, per user or per symbol, and the noise vector of each MS is a zero-mean circularly symmetric complex Gaussian random variable with Arbitrary covariance matrix. For each of these problems, we propose a novel duality based iterative solution. Each of these problems is solved as follows. First, we establish a novel sum average meansquare- error (AMSE) duality. Second, we formulate the Power allocation part of the problem in the downlink channel as a Geometric Program (GP). Third, using the duality result and the solution of GP, we utilize alternating optimization technique to solve the original downlink problem. To solve robust sum MSE minimization constrained with per BS antenna and per BS Power problems, we have established novel downlink-uplink duality. On the other hand, to solve robust sum MSE minimization constrained with per user and per symbol Power problems, we have established novel downlink-interference duality. For the total BS Power constrained robust sum MSE minimization problem, the current duality is established by modifying the constraint function of the dual uplink channel problem. And, for the robust sum MSE minimization with per BS antenna and per user (symbol) Power constraint problems, our duality are established by formulating the noise covariance matrices of the uplink and interference channels as fixed point functions, respectively.
Tadilo Endeshaw Bogale - One of the best experts on this subject based on the ideXlab platform.
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robust sum mse optimization for downlink multiuser mimo systems with Arbitrary Power constraint generalized duality approach
IEEE Transactions on Signal Processing, 2012Co-Authors: Tadilo Endeshaw Bogale, Luc VandendorpeAbstract:This paper considers linear minimum mean-square-error (MMSE) transceiver design problems for downlink multiuser multiple-input multiple-output (MIMO) systems where imperfect channel state information is available at the base station (BS) and mobile stations (MSs). We examine robust sum mean-square-error (MSE) minimization problems. The problems are examined for the generalized scenario where the Power constraint is per BS, per BS antenna, per user or per symbol, and the noise vector of each MS is a zero-mean circularly symmetric complex Gaussian random variable with Arbitrary covariance matrix. For each of these problems, we propose a novel duality based iterative solution. Each of these problems is solved as follows. First, we establish a novel sum average mean-square-error (AMSE) duality. Second, we formulate the Power allocation part of the problem in the downlink channel as a Geometric Program (GP). Third, using the duality result and the solution of GP, we utilize alternating optimization technique to solve the original downlink problem. To solve robust sum MSE minimization constrained with per BS antenna and per BS Power problems, we have established novel downlink-uplink duality. On the other hand, to solve robust sum MSE minimization constrained with per user and per symbol Power problems, we have established novel downlink-interference duality. For the total BS Power constrained robust sum MSE minimization problem, the current duality is established by modifying the constraint function of the dual uplink channel problem. And, for the robust sum MSE minimization with per BS antenna and per user (symbol) Power constraint problems, our duality are established by formulating the noise covariance matrices of the uplink and interference channels as fixed point functions, respectively. We also show that our sum AMSE duality are able to solve other sum MSE-based robust design problems. Computer simulations verify the robustness of the proposed robust designs compared to the nonrobust/naive designs.
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Robust Sum MSE optimization for downlink multiuser MIMO systems with Arbitrary Power constraint: Generalized duality approach
IEEE Transactions on Signal Processing, 2012Co-Authors: Tadilo Endeshaw Bogale, Luc VandendorpeAbstract:This paper considers linear minimum meansquare- error (MMSE) transceiver design problems for downlink multiuser multiple-input multiple-output (MIMO) systems where imperfect channel state information is available at the base station (BS) and mobile stations (MSs). We examine robust sum mean-square-error (MSE) minimization problems. The problems are examined for the generalized scenario where the Power constraint is per BS, per BS antenna, per user or per symbol, and the noise vector of each MS is a zero-mean circularly symmetric complex Gaussian random variable with Arbitrary covariance matrix. For each of these problems, we propose a novel duality based iterative solution. Each of these problems is solved as follows. First, we establish a novel sum average meansquare- error (AMSE) duality. Second, we formulate the Power allocation part of the problem in the downlink channel as a Geometric Program (GP). Third, using the duality result and the solution of GP, we utilize alternating optimization technique to solve the original downlink problem. To solve robust sum MSE minimization constrained with per BS antenna and per BS Power problems, we have established novel downlink-uplink duality. On the other hand, to solve robust sum MSE minimization constrained with per user and per symbol Power problems, we have established novel downlink-interference duality. For the total BS Power constrained robust sum MSE minimization problem, the current duality is established by modifying the constraint function of the dual uplink channel problem. And, for the robust sum MSE minimization with per BS antenna and per user (symbol) Power constraint problems, our duality are established by formulating the noise covariance matrices of the uplink and interference channels as fixed point functions, respectively.
George V Eleftheriades - One of the best experts on this subject based on the ideXlab platform.
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Arbitrary Power conserving field transformations with passive lossless omega type bianisotropic metasurfaces
IEEE Transactions on Antennas and Propagation, 2016Co-Authors: Ariel Epstein, George V EleftheriadesAbstract:We present a general theory for designing realistic omega-type bianisotropic metasurfaces (O-BMSs), unlocking their full potential for molding electromagnetic fields. These metasurfaces, characterized by electric surface impedance, magnetic surface admittance, and magnetoelectric coupling coefficient, were previously considered for wavefront manipulation. However, previous reports mainly considered plane-wave excitations, and implementations included cumbersome metallic features. In this paper, we prove that any field transformation that locally conserves real Power can be implemented via passive and lossless meta-atoms characterized by closed-form expressions; this allows rigorous incorporation of Arbitrary source and scattering configurations. Subsequently, we show that O-BMS meta-atoms can be implemented using an asymmetric stack of three impedance sheets, an appealing structure for printed circuit board fabrication. Our formulation reveals that, as opposed to Huygens’ metasurfaces, which exhibit negligible magnetoelectric coupling, O-BMSs are not limited to controlling the phase of transmitted fields, but can rather achieve a high level of control over the amplitude and phase of reflected fields. This is demonstrated by designing O-BMSs for reflectionless wide-angle refraction, independent surface-wave guiding, and a highly directive low-profile antenna, verified with full-wave simulations. This straightforward methodology facilitates the development of O-BMS-based devices for controlling the near and far fields of Arbitrary sources in complex scattering configurations.
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Arbitrary Power conserving field transformations with passive lossless omega type bianisotropic metasurfaces
arXiv: Optics, 2016Co-Authors: Ariel Epstein, George V EleftheriadesAbstract:We present a general theory for designing realistic omega-type bianisotropic metasurfaces (O-BMSs), unlocking their full potential for molding electromagnetic fields. These metasurfaces, characterized by electric surface impedance, magnetic surface admittance, and magnetoelectric coupling coefficient, were previously considered for wavefront manipulation. However, previous reports mainly considered plane-wave excitations, and implementations included cumbersome metallic features. In this work, we prove that any field transformation which locally conserves real Power can be implemented via passive and lossless meta-atoms characterized by closed-form expressions; this allows rigorous incorporation of Arbitrary source and scattering configurations. Subsequently, we show that O-BMS meta-atoms can be implemented using an asymmetric stack of three impedance sheets, an appealing structure for printed circuit board fabrication. Our formulation reveals that, as opposed to Huygens' metasurfaces (HMSs), which exhibit negligible magnetoelectric coupling, O-BMSs are not limited to controlling the phase of transmitted fields, but can rather achieve high level of control over the amplitude and phase of reflected fields. This is demonstrated by designing O-BMSs for reflectionless wide-angle refraction, independent surface-wave guiding, and a highly-directive low-profile antenna, verified with full-wave simulations. This straightforward methodology facilitates development of O-BMS-based devices for controlling the near and far fields of Arbitrary sources in complex scattering configurations.
Jianhui Wang - One of the best experts on this subject based on the ideXlab platform.
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universal expression of efficiency at maximum Power a quantum mechanical brayton engine working with a single particle confined in a Power law trap
Communications in Theoretical Physics, 2015Co-Authors: Yiming Lai, Jianhui WangAbstract:We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an Arbitrary Power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the Power and efficiency, and find that the efficiency at maximum Power is bounded from above by the function: η+ = θ/(θ + 1), with θ being a potential-dependent exponent.
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quantum mechanical engines working with an ideal gas with a finite number of particles confined in a Power law trap
EPL, 2015Co-Authors: Jianhui WangAbstract:Based on quantum thermodynamic processes, we make a quantum-mechanical (QM) extension of the typical heat engine cycles, such as the Carnot, Brayton, Otto, Diesel cycles, etc., with no introduction of the concept of temperature. When these QM engine cycles are implemented by an ideal gas confined in an Arbitrary Power-law trap, a relation between the quantum adiabatic exponent and trap exponent is found. The differences and similarities between the efficiency of a given QM engine cycle and its classical counterpart are revealed and discussed.
Manos M Tentzeris - One of the best experts on this subject based on the ideXlab platform.
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comments on a modified gysel Power divider of Arbitrary Power ratio and real termination impedances
IEEE Microwave and Wireless Components Letters, 2020Co-Authors: Manos M TentzerisAbstract:Without fully understanding the previous works of asymmetric ring hybrids terminated in Arbitrary real impedances, it is insisted that the Gysel Power dividers terminated in Arbitrary real impedances should be first reported in the above article. However, the claim does not seem to be correct. The misinterpreted concept will be clarified.
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compact and wideband general coupled line ring hybrids gcrhs for Arbitrary circumferences and Arbitrary Power division ratios
IEEE Access, 2019Co-Authors: Hee Ran Ahn, Manos M TentzerisAbstract:Coupled-line ring hybrids (CRHs) are presented for Arbitrary circumferences and for Arbitrary Power-division ratios. They each consist of three single transmission-line sections and a set of coupled transmission-line sections with or without two identical capacitances and contain most properties of the conventional ring hybrids. Therefore, they may be called general CRHs and can be designed for the frequency performance better than that of any other conventional one. By adopting the coupled-line sections, the 180° phase shift can be guaranteed, regardless of fabrication technologies, but three or four unknown variables more should be considered additionally, which results in a complicated derivation process. To make it simpler, two conditions of $S_{11}^{e}=S_{22}^{o}$ and $S_{22}^{e}=S_{11}^{o}$ , where $S_{11}$ and $S_{22}$ are scattering parameters, and the superscripts of ${e}$ and ${o}$ are meant as even- and odd-mode excitations, respectively, are newly employed. To verify the suggested theory, two prototypes were tested for the Power-division ratios of 0 and −5 dB without and with capacitances, respectively. The measured results are in good agreement with the predicted ones, and the measured bandwidths with 15-dB return loss are 82.9 % and 97.65 % for the Power-division ratios of 0 and −5 dB, respectively.
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Arbitrary Power division branch line hybrids for high performance wideband and selective harmonic suppressions from 2f_ 0
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Hee Ran Ahn, Manos M TentzerisAbstract:A branch-line hybrid (BH) topology is suggested, consisting of four equal lengths of transmission-line sections (TLs) with two different characteristic impedances and four identical L-sections with each a TL and an open stub. The topology can provide three distinct properties; lower characteristic impedances of TLs, longer electrical paths for the scattering parameters, and additional transmission zeros, enabling high performance of harmonic suppressions from $2f_{0}$ , where $f_{0}$ is a design frequency, wideband and selective harmonic suppressions. A compact equivalent circuit of a TL is suggested for harmonic suppression BH which can be applied for all possible Power-division ratios. As a proof-of-concept demonstration, two prototypes for the Power-division ratios of 0 and 6 dB are tested and measured. The measured frequency responses are in a good agreement with the predicted ones, given fabrication errors.