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IEEE ACCESS 2017年 5卷 7285-7293页

作者： Sha, Ziyuan Zhu, Xudong Zhao, Peiyao Wang, Zhaocheng Tsinghua Univ Dept Elect Engn Tsinghua Natl Lab Informat Sci & Technol Beijing 100084 Peoples R China

Spatial modulation utilizes the diversity of multiple-input multiple-output channel to improve the spectral efficiency. In time-variant wireless channels, its performance degrades due to the inaccuracy of channel estimation (CE). In this paper, a data-aided channel tracking (DACT) method is proposed to improve its CE accuracy in time-variant wireless channels. Specifically, the demodulated data at current time slot are used to update the subsequent channel state information. Two different DACT methods with different pilot insertion patterns are proposed: 1) feedback DACT (FDACT) where when a symbol error is detected, the receiver will inform the transmitter to insert pilots and estimate the channel again;2) periodical DACT (PDACT) where pilots are inserted periodically. Theoretical analysis of the CE error in time-variant channels is presented, which indicates that the CE accuracy could be significantly improved in comparison to the conventional counterpart. Moreover, the closed-form expressions of bit error rate for FDACT and frame error rate for PDACT are derived. Simulations are conducted to verify the efficiency of the proposed DACT methodologies.

关键词： multi-input multi-output spatial modulation data-aided channel tracking channel estimation time-variant channel

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Compact Sub-6 GHz and mmWave 5G Wideband 2 x 1 MIMO Antenna with High Isolation Using Parasitically Placed Double Negative (DNG) Isolator

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WIRELESS PERSONAL COMMUNICATIONS 2022年第3期122卷 2839-2857页

作者： Sharma, Rashbha Khanna, Rajesh Geetanjali Thapar Inst Engn & Technol Deemed Univ Dept Elect & Commun Engn 32 Bhadson Rd Patiala Punjab India Chitkara Univ Inst Engn & Technol Rajpura Punjab India

In this paper a multiband modified 'W' shaped, multiple input multiple output (MIMO) antenna with a metamaterial inspired isolator for enhanced isolation is proposed for 5G application. The two-element MIMO antenna comprises of a closely placed (edge to edge gap of 0.117 lambda(o), lambda(o) = highest operating wavelength) antenna elements that covers both sub-6 GHz (3.42-4.25 GHz) and millimeter wave (mmWave) range bands (24.8-26.5 GHz) of 5G with bandwidth of 821 MHz and 1630 MHz. The MIMO antenna also covers bands C (7.44-7.92 GHz), X (9.9-10.49 GHz), Ku (12.02-13.39 GHz & 15.92-17.492 GHz), K (19.49-22.42 GHz), partially. The isolation level in all resonating bands remain near to the acceptable value of (|S-12|> -15 dB) however a very significant mutual coupling effect is observed in sub-6 GHz range (|S-12|= -11.92 dB at 3.94 GHz). To improve the isolation in sub-6 GHz band, a metamaterial inspired isolator comprising of Double negative (DNG) unit cells is uniquely placed along the side of the closely positioned antenna elements. Simulated results indicate that isolation level improves to (|S-12|= -16.1 dB at 3.94 GHz) after placing the DNG metamaterial based isolator. The antenna performance parameters such as gain, return loss, bandwidth, Envelope correlation coefficient (ECC), Diversity gain (DG) and radiation efficiency are not affected by placement of isolator. The metamaterial equipped MIMO antenna (Meta-MIMO antenna) has a compact structure of 70 x 40 x 0.8 mm(3), with a high isolation in all bands (|S-12|> -16 dB), peak gain of 7.8dBi, low ECC (< 0.05), high diversity gain (9.98 dB) and efficiency (approximate to 91.38%). Further the proposed Meta-MIMO antenna performance for practical applications is investigated by connecting to different sizes of ground plane, the results indicate that the isolation levels and efficiency do not deteriorate.

关键词： 5G multi-input multi-output Millimeter wave Sub-6 GHz Metamaterials Isolation

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Adaptive actuator failure compensation for a class of MIMO nonlinear time delay systems

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NONLINEAR DYNAMICS 2015年第2期79卷 865-883页

作者： Hashemi, Mahnaz Askari, Javad Ghaisari, Jafar Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran

In this paper, an adaptive actuator failure compensation scheme is proposed for a class of parametric-strict-feedback multi- input multi-output nonlinear systems with unknown time- varying state delays. The considered actuator failures are types of loss of effectiveness, in which unknown system inputs may lose unknown fraction of their effectiveness. The adaptive compensation controller is constructed by utilizing a backstepping design method. The appropriate Lyapunov-Krasovskii functionals are introduced to design new adaptive laws to compensate the unknown actuator failures as well as uncertainties from unknown parameters and state delays. The boundedness of all the closed-loop signals is guaranteed, and the tracking errors are proved to converge to a small neighborhood of the origin. Simulation results are provided to show the effectiveness of the proposed approach.

关键词： Actuator failure multi-input multi-output Nonlinear systems Time-varying state delay Adaptive compensation Backstepping

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Optimizing etching process recipe based on Kernel Ridge Regression

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JOURNAL OF MANUFACTURING PROCESSES 2021年 61卷 454-460页

作者： Chen, Heping Leclair, John Texas State Univ San Marcos TX 78666 USA Samsung Austin TX 78666 USA

Exploring optimal recipes to reduce dimensional variations is critical in etching processes. Variations in critical dimensions that were acceptable previously can become problematic because of smaller node sizes and more complex structures. Dry etch can be a major source of variations and will be the focus of this research. Advanced Process Control (APC) has been widely studied in semiconductor manufacturing. Even though different APC methods have been developed to adjust recipes, it is challenging to explore an optimal recipe to achieve multiple critical dimensions. In this paper, a learning method based on Kernel Ridge Regression (KRR) is proposed to generate optimal recipes for multi-input multi-output (MIMO) systems. A KRR parameter optimization method is developed. To improve the recipe optimization process, a feedback fine tuning method is proposed. Experimental data in a dry etch process were collected and processed for model construction and recipe optimization. The results demonstrate the effectiveness of the proposed method in exploring optimal recipes for MIMO systems.

关键词： Kernel Ridge Regression Etching process Advanced process control multi-input multi-output

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A CPW-fed stepped slot UWB antenna for MIMO/diversity applications

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INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES 2017年第1期9卷 151-162页

作者： Kumar, Raj Pazare, Neha ARDE Pune 411021 Maharashtra India DIAT DU Pune 411025 Maharashtra India

An ultra-wideband (UWB) slot antenna for diversity applications is introduced. The overall structure of the antenna consists of two similar coplanar waveguide (CPW)-fed stepped rectangular slots placed in an orthogonal position. The slots are asymmetric with respect to their placement in the ground plane. The CPW feeds are double stepped and terminated on hexagonal patches for better impedance matching. A wide impedance bandwidth (measured) from 3 to 12 GHz with an isolation better than 15 dB is obtained with this antenna. To improve the isolation, the design is modified and an I-shaped slot strip is introduced between the two slot antennas. With this, the isolation is brought about 25 dB of most of the band, while the impedance bandwidth remains the same (2.8-12 GHz for port 1, measured and 2.9-12 GHz for port 2, measured). The far-field radiation patterns are also measured and a peak gain of about 5 dBi is obtained. Finally, the diversity parameters such as envelope correlation coefficient and capacity loss are calculated and found to have low values. The antenna is expected to be useful for UWB diversity applications with good isolation.

关键词： Slot antenna multi-input multi-output Polarization diversity UWB antenna

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Dynamic modeling, simulation, and MIMO predictive control of a tubular solid oxide fuel cell

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JOURNAL OF PROCESS CONTROL 2012年第8期22卷 1502-1520页

作者： Spivey, Benjamin J. Edgar, Thomas F. Univ Texas Austin Dept Chem Engn Austin TX 78712 USA

Solid oxide fuel cells are a promising option for distributed energy stationary power generation that offers efficiencies up to 50% in stand-alone applications, 70% in hybrid gas turbine applications and 80% in cogeneration. To advance SOFC technology sufficiently for widespread market penetration, the SOFC must demonstrate improved cell lifetime from the status quo. Much research has been performed to improve SOFC lifetime using advanced geometries and materials, and in this research, we suggest further improving lifetime by designing an advanced control algorithm based upon preexisting mechanical stress analysis [1]. Control algorithms commonly address SOFC lifetime related operability objectives using unconstrained, SISO control algorithms that seek to minimize thermal transients. While thermal fatigue may be one thermal stress driver, these studies often do not consider maximum radial thermal gradients or critical absolute temperatures in the SOFC. In addition, researchers often discuss hot-spots as a critical lifetime reliability issue, but as previous stress work demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs modeled after the Siemens Power Generation, Inc. design. In this work, we present a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop simulations with a constrained, MIMO model predictive control algorithm. Closed-loop simulation results demonstrate effective load-following, operability constraint satisfaction, and disturbance rejection. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： multi-input multi-output Model predictive control Distributed parameter models Solid oxide fuel cell Dynamic simulation Nonlinear programming

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Optimal adaptive channel scheduling for scalable video broadcasting over MIMO wireless networks

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COMPUTER NETWORKS 2013年第15期57卷 3039-3050页

作者： Zhou, Chao Zhang, Xinggong Guo, Zongming Peking Univ Inst Comp Sci & Technol Beijing 100871 Peoples R China

Video broadcasting is an efficient way to deliver video content to multiple receivers. However, due to heterogeneous channel conditions in MIMO wireless networks, it is challenging for video broadcasting to map scalable video layers to proper MIMO transmit antennas to minimize the average overall video transmission distortion. In this paper, we investigate the channel scheduling problem for broadcasting scalable video content over MIMO wireless networks. An adaptive channel scheduling based unequal error protection (UEP) video broadcasting scheme is proposed. In the scheme, video layers are protected unequally by being mapped to appropriate antennas, and the average overall distortion of all receivers is minimized. We formulate this scheme into a non-linear combinatorial optimization problem. It is not practical to solve the problem by an exhaustive search method with heavy computational complexity. Instead, an efficient branch-and-bound based channel scheduling algorithm, named TBCS, is developed. TBCS finds the global optimal solution with much lower complexity. The complexity is further reduced by relaxing the termination condition of TBCS, which produces a (1 - epsilon)-optimal solution. Experimental results demonstrate both the effectiveness and efficiency of our proposed scheme and algorithm. As compared with some existing channel scheduling methods, TBCS improves the quality of video broadcasting across all receivers significantly. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.

关键词： Adaptive channel scheduling Scalable video broadcasting multi-input multi-output Unequal error protection Branch-and-bound algorithm

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Energy optimization for full-duplex wireless-powered IoT networks using rotary-wing UAV with multiple antennas

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COMPUTER COMMUNICATIONS 2024年 215卷 62-73页

作者： Fathollahi, Leyla Feghhi, Mahmood Mohassel Atashbar, Mahmoud Univ Tabriz Fac Elect & Comp Engn Tabriz Iran Azarbaijan Shahid Madani Univ Dept Elect Engn Tabriz Iran

In this paper, we propose a novel design for the rotary-wing unmanned aerial vehicle (UAV)-enabled full-duplex (FD) wireless-powered Internet of Things (IoT) networks. In this network, the UAV is equipped with an antenna array, and the K IoT sensors, which are distributed randomly, use single-antenna to communicate. By sending the energy, the UAV as a hybrid access point, charges the sensors and collects information from them. Then, to manage the time and optimize the energy, the sensors are divided into N groups, so that the UAV equipped with multi-input multi-output (MIMO) technology can serve the sensors in a group, during the total time T. We provide a simple implementation of the wireless power transfer protocol in the sensors by using the time division multiple access (TDMA) scheme to receive information from the users. In other words, the sensors of each group receive energy from the UAV, when it hovers over the sensors of the previous group, and also when the UAV flies over the previous group to the current group. The sensors of each group send their information to the UAV, when the UAV is hovering over their group. Under these assumptions, we formulate two optimization problems: a sum throughput maximization problem, and a total time minimization problem. Numerical results show that our proposed optimal network provides better performance than the existing networks. In fact, our novel design can serve more sensors at the cost of using more antennas compared to that of the conventional networks.

关键词： Internet of things Unmanned aerial vehicle multi-input multi-output Wireless power transfer protocol Convex optimization

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Continuous convolution and nonlinear transformation for multi-shaker non-Gaussian random vibration control

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JOURNAL OF VIBRATION AND CONTROL 2022年第1-2期28卷 83-91页

作者： Zheng, Ronghui Lu, Yue Chen, Huaihai Chen, Guoping Nanjing Univ Aeronaut & Astronaut Coll Aerosp Engn State Key Lab Mech & Control Mech Struct Nanjing Peoples R China Shanghai Radio Equipment Res Inst Shanghai Peoples R China

This study proposes a continuous convolution method combined with memoryless nonlinear transformation for multi-input multi-output stationary non-Gaussian random vibration tests. The challenge of the multi-shaker non-Gaussian random vibration test lies in the coupling problems that are manifested in the inherent physical system and in the existence of cross-spectral densities. In the presented method, the independent stationary Gaussian random signals pass through a designed finite impulse response filter with a convolution manipulation first, and then the resulting signals are transformed to the non-Gaussian random signals by the memoryless nonlinear transformation method. The desired drive signals are obtained by the input-output relationship in the frequency domain. The finite impulse response filter is constructed by the frequency sampling technique in which the amplitude characteristics of the filter are determined by the predefined reference power spectral densities. A new monotonic nonlinear transformation function with an approximate kurtosis solution is provided. It only contains one parameter for kurtosis control both in sub-Gaussian and super-Gaussian cases. The memoryless nonlinear transformation is used to maintain the cross-spectral densities, although some distortions are introduced to the power spectra during the transformation process. The inverse system method is used to overcome the coupling problem caused by the inherent physical system. A simulation example and a triaxial vibration test are carried out, and the results indicate the validity and feasibility of the proposed method.

关键词： multi-input multi-output continuous convolution finite impulse response filter non-Gaussian memoryless nonlinear transformation

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Channel-Reconstruction-Based Hybrid Precoding for Millimeter-Wave multi-User MIMO Systems

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2018年第2期12卷 383-398页

作者： Castellanos, Miguel R. Raghavan, Vasanthan Ryu, Jung H. Koymen, Ozge H. Li, Junyi Love, David J. Peleato, Borja Purdue Univ W Lafayette IN 47907 USA Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA Purdue Univ Elect & Comp Engn Dept W Lafayette IN 47907 USA Qualcomm Flarion Technol Inc Bridgewater NJ 08807 USA

The focus of this paper is on multi-user multi-input multi-output transmissions for millimeter-wave systems with a hybrid precoding architecture at the base station. To enable multi-user transmissions, the base station uses a cell-specific codebook of beamforming vectors over an initial beam alignment phase. Each user uses a user-specific codebook of beamforming vectors to learn the top-P (where P >= 1) beam pairs in terms of the observed signal-to-noise ratio (SNR) in a single-user setting. The top-P beam indices along with their SNRs are fed back from each user and the base station leverages this information to generate beam weights for simultaneous transmissions. A typical method to generate the beam weights is to use only the best beam for each user and either steer energy along this beam, or to utilize this information to reduce multi-user interference. The other beams are used as fall-back options to address blockage or mobility. Such an approach completely discards information learned about the channel condition(s) even though each user feeds back this information. With this background, this paper develops an advanced directional precoding structure for simultaneous transmissions at the cost of an additional marginal feedback overhead. This construction relies on three main innovations: first, additional feedback to allow the base station to reconstruct a rank-P approximation of the channel matrix between it and each user;second, a zero-forcing structure that leverages this information to combat multi-user interference by remaining agnostic of the receiver beam knowledge in the precoder design;and third, a hybrid precoding architecture that allows both amplitude and phase control at low complexity and cost to allow the implementation of the zero-forcing structure. Numerical studies show that the proposed scheme results in a significant sum rate performance improvement over naive schemes even with a coarse initial beam alignment codebook.

关键词： Millimeter wave multi-input multi-output multi-user beamforming hybrid precoding phase and amplitude control zeroforcing generalized eigenvector channel estimation

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