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Wideband MIMO antenna system with dual polarization for WiFi and LTE applications

INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES 2016年第3期8卷 643-650页

作者： Moradikordalivand, Alishir Leow, Chee Yen Abd Rahman, Tharek Ebrahimi, Sepideh Tien Han Chua Univ Teknol Malaysia Fac Elect Engn Wireless Commun Ctr Skudai 81310 Johor Malaysia Islamic Azad Univ Young Researchers & Elite Club Arak Branch Arak Iran Islamic Azad Univ Dept Engn Aligoudarz Branch Aligoudarz Iran

In this paper a wideband multi-input multi-output (MIMO) antenna system for WiFi-LTE wireless access point (WAP) application is proposed. The MIMO antenna system consists of two common element microstrip-fed monopole antennas with dual polarization. Physically closed integration of MIMO antenna elements requires a special technique to increase the isolation between the antennas. A novel structure of parasitic element is introduced to improve the isolation between the antennas. The proposed MIMO antenna system is simulated and optimized using CST Microwave Studio. The designed antenna system is fabricated and measured to verify the simulation results. Reflection coefficient of less than 210 dB and isolation more than 15 dB are achieved in the operating frequency range of 2.3-2.9 GHz which covers WiFi 2.4 GHz and LTE 2.6 GHz bands. The proposed system also provides dual polarization with 10 dB polarization diversity gain and envelope correlation coefficient less than 0.15. Each individual antenna has a gain of 5.1 dB and 68% efficiency.

关键词： Isolation Microstrip-fed multiple-input multiple-output Parasitic element Printed monopole antenna

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Compact band-notched UWB antenna for MIMO applications in portable wireless devices

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2016年第6期58卷 1390-1394页

作者： Sipal, Deepika Abegaonkar, Mahesh P. Koul, Shiban K. IITD CARE Hauz Khas New Delhi 110016 India

A compact 5.5 GHz band-notched ultra-wideband (UWB) 2-element antenna with high isolation for multiple-input multiple-output (MIMO) portable wireless devices in wireless personal area network (WPAN) application is proposed. The MIMO antenna is designed for 3.1-10.6 GHz range on Neltec substrate with compact dimension of 43 x 20 mm(2) and is tested experimentally. For the rejection band at 5.5 GHz, a slot of length 1.0 is etched into the radiator. Simple structure, i.e., receded steps at ground are used to improve isolation by 3 dB between two UWB antennas. The simulated and measured results show |S-11|-10 dB and |S-21|-20 dB in most of the frequency range excluding the reject band at 5.5 GHz in UWB range. The measured, simulated and calculated results show that the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1390-1394, 2016

关键词： multiple-input multiple-output broadband UWB WPAN

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Dual-Polarized Spatial Modulation Performance Analysis over Nakagami-m Fading Channels 9

Dual-Polarized Spatial Modulation Performance Analysis over ...

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9th International Conference on Wireless Communication and Signal Processing (WCSP)

作者： Lyu, Zhilan Zhao, Kanglian Li, Wenfeng Zhou, Haibo Nanjing Univ Sch Elect Sci & Engn Nanjing Jiangsu Peoples R China

ISBN: (纸本)9781538620625

By combining the polarized modulation and the spatial modulation technique, dual-polarized spatial modulation (DPSM) has been recently proposed for MIMO transmission to improve the spectral efficiency and reduce the space occupancy. The performance of DPSM over correlated Rayleigh and Rice fading channels has been studied, showing that DPSM technique outperforms uni-polarized SM technique. For a general investigation, in this paper, we study the performance of DPSM scheme over Nakagami-m fading channel, which is a more general model than Rayleigh and Rice channel. A tight upper bound of average bit error rate (ABER) for DPSM scheme over Nakagami-m fading channel is derived, based on the ABER framework. In addition, we present detailed analysis of performance for different shape parameter m in the channel model. Finally, we validate the accuracy of the theoretical derivation through the results of the numerical simulations.

关键词： multiple-input multiple-output Nakagami-m fading dual-polarized spatial modulation (DPSM) performance anlysis

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Compact MIMO Antenna with Pattern Diversity 10

Compact MIMO Antenna with Pattern Diversity

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10th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT)

作者： Ding, Chao Feng Zhang, Xiu Yin Xue, Cheng Dai South China Univ Technol Sch Elect & Informat Engn Guangzhou 510640 Peoples R China

ISBN: (纸本)9781538627204

In this paper, a dual-element MIMO antenna without adding any decoupling structure is presented. The MIMO antenna consists of two symmetric inverted-L elements with the antenna spacing of only 9 mm (0.1 lambda at 3.5 GHz). The isolation between antennas is reduced by pattern diversity. vertical bar S-11 vertical bar < -10 dB and vertical bar S-21 vertical bar < -16 dB are achieved over the band from 3.48-3.6 GHz. Compared with the antenna without decoupling, the isolation is improved by 11 dB, whereas the envelope correlation coefficient (ECC) is reduced from 0.14 to 0.04.

关键词： Pattern diversity multiple-input multiple-output antenna

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Joint Secure AF Relaying and Artificial Noise Optimization: A Penalized Difference-of-Convex Programming Framework

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IEEE ACCESS 2016年 4卷 10076-10095页

作者： Yang, Jiaxin Li, Qiang Cai, Yunlong Zou, Yulong Hanzo, Lajos Champagne, Benoit McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 0E9 Canada Univ Elect Sci & Technol China Sch Commun & Informat Engn Chengdu 611731 Peoples R China Zhejiang Univ Dept Informat Sci & Elect Engn Hangzhou 310027 Zhejiang Peoples R China Nanjing Univ Posts & Telecommun Sch Telecommun & Informat Engn Nanjing 210003 Jiangsu Peoples R China Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

Owing to the vulnerability of relay-assisted communications, improving wireless security from a physical layer signal processing perspective is attracting increasing interest. Hence, we address the problem of secure transmission in a relay-assisted network, where a pair of legitimate user equipments (UEs) communicate with the aid of a multiple-input multiple output (MIMO) relay in the presence of multiple eavesdroppers (eves). Assuming imperfect knowledge of the eves' channels, we jointly optimize the power of the source UE, the amplify-and-forward relaying matrix, and the covariance of the artificial noise transmitted by the relay, in order to maximize the received signal-to-interference-plus-noise ratio at the destination, while imposing a set of robust secrecy constraints. To tackle the resultant non-convex optimization problem with tractable complexity, a new penalized difference-of-convex (DC) algorithm is proposed, which is specifically designed for solving a class of non-convex semidefinite programs. We show how this penalized DC framework can be invoked for solving our robust secure relaying problem with proven convergence. In addition, to benchmark the proposed algorithm, we subsequently propose a semidefinite relaxation-based exhaustive search approach, which yields an upper bound of the secure relaying problem, however, with significantly higher complexity. Our simulation results show that the proposed solution is capable of ensuring the secrecy of the relay-aided transmission and significantly improving the robustness toward the eves' channel uncertainties as compared with the non-robust counterparts. It is also demonstrated the penalized DC-based method advocated yields a performance close to the upper bound.

关键词： Amplify-and-forward difference-of-convex eavesdropping multiple-input multiple-output physical layer security relaying robust optimization

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A General MIMO Framework for NOMA Downlink and Uplink Transmission Based on Signal Alignment

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2016年第6期15卷 4438-4454页

作者： Ding, Zhiguo Schober, Robert Poor, H. Vincent Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Univ Lancaster Sch Comp & Commun Lancaster LA1 4WA England Univ Erlangen Nurnberg Inst Digital Commun D-91054 Erlangen Germany Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

The application of multiple-input multipleoutput (MIMO) techniques to nonorthogonal multiple access (NOMA) systems is important to enhance the performance gains of NOMA. In this paper, a novel MIMO-NOMA framework for downlink and uplink transmission is proposed by applying the concept of signal alignment. By using stochastic geometry, closed-form analytical results are developed to facilitate the performance evaluation of the proposed framework for randomly deployed users and interferers. The impact of different power allocation strategies, namely fixed power allocation and cognitive radio inspired power allocation, on the performance of MIMO-NOMA is also investigated. Computer simulation results are provided to demonstrate the performance of the proposed framework and the accuracy of the developed analytical results.

关键词： multiple-input multiple-output multiuser superposition transmission (MUST) non-orthogonal multiple access (NOMA) signal alignment stochastic geometry

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Partitioned scheduling for sphere decoding with runtime constraints for practical MIMO communication systems

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2016年第9期29卷 1474-1481页

作者： Kim, T. H. Kim, J. W. Korea Aerosp Univ Sch Elect & Informat Engn Goyang South Korea

This paper presents an effective scheduling scheme for sphere decoding (SD) with runtime constraints, targeting the practical multiple-input multiple-output (MIMO) communication systems where neither the interleaving scheme nor its block size cannot be designed freely. The proposed scheme imposes runtime constraints on SD to distribute the errors due to the early termination of SD. Because the distributed errors may be corrected effectively by forward error correction, the error-rate performance can be improved;experimental results show that the performance improvement is approximately 2dB in terms of the signal-to-noise ratio to achieve a bit-error rate of 10(-4) in 4 x 4 16-QAM MIMO systems. Copyright (C) 2015 John Wiley & Sons, Ltd.

关键词： sphere decoding multiple-input multiple-output symbol detection maximum-likelihood decoding

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An efficiency comparative analysis of isolated multi-source grid-connected PV generation systems based on a HF-link micro-inverter approach

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SOLAR ENERGY 2016年 127卷 239-249页

作者： Aganza-Torres, A. Cardenas, V. Pacas, M. Gonzalez, M. Univ Autonoma San Luis Potosi Ctr Invest & Estudios Posgrad Fac Ingn Ave Dr Manuel Nava 8 San Luis Potosi 78290 Mexico Univ Siegen Chair Power Elect & Elect Dr Holderlinstr 3 D-57068 Siegen Germany

For solar photovoltaic grid-connected generation systems, four inverter configurations are currently available in the market for different power ranges of the required system. However, a power gap exists within the lower range of the commercial power scale, particularly between micro-inverters and string inverters, leaving room for innovation and development of flexible and modular converters in this power range. This paper presents three different isolated multi-source grid-connected PV generation systems based on a single-phase high-frequency link micro-inverter scheme, to evaluate the feasibility for reducing the mentioned power gap by using higher power density systems based on a micro-inverter approach instead of derating the currently available string inverters, which are optimized for higher input voltage and power conditions compared with micro-inverters. Losses estimations, peak and weighted efficiencies are presented for multiple-input multiple-output, multiple-input Single-output and Single-input Single-output generation systems with different number of input power sources. Analysis and discussion for each system are presented, showing that a multiple-input Single output system scheme presents a feasible alternative to a higher power density converter, reducing the inverter market power gap, with attractive features for renewable energy sources such as modularity and flexibility. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Grid-connected system HF-link multi-port converter multiple-input multiple-output multiple-input Single-output Single-input Single-output Power density increase

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Optimization of a MIMO amplify-and-forward relay system with channel state information estimation error and feedback delay

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EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2016年第1期2016卷 1页

作者： Zhang, Ying Zhao, Danni Zhao, Huapeng Chen, Yinjiang Kang, Ning Univ Elect Sci & Technol China Coll Elect Engn Xiyuan Ave Chengdu 610066 Peoples R China

This paper addresses the robust design of a multiple-input multiple-output amplify-and-forward relay system against channel state information (CSI) mismatch due to estimation error and feedback delay. The estimation error and feedback delay are expressed using appropriate models, from which we derive the conditional mean square error (MSE) between the desired and the received signals upon the estimated CSI. The conditional MSE is then minimized to optimize the relay beamforming matrix with relay transmission power constraint. It is shown that the proposed optimization problem reduces to the conventional minimum MSE problem when CSI mismatch vanishes. By analyzing the structure of the optimal beamforming matrix, the optimization problem is simplified so that it can be directly solved using the genetic algorithm (GA). To further reduce the computational load, we develop a relaxed version of the optimization problem. It is found that the relaxation enables us to efficiently solve the problem using water filling strategy. Computer simulations show that both GA and water filling solutions are superior to conventional solutions without CSI mismatch consideration, while the water filling is 1000 times faster than the GA.

关键词： Channel state information mismatch Conditional expectation multiple-input multiple-output Minimum mean square error Relay network

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Degrees of Freedom of Two-Cluster MIMO Multiway Relay Interference Channels Using Blind Interference Neutralization

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KSII TRANSACTIONS ON INTERNET AND INFORMATION SYSTEMS 2016年第1期10卷 168-186页

作者： Zhang, Bowei Feng, Wenjiang Dong, Tingting Deng, Yina Chongqing Univ Coll Commun Engn Chongqing 400044 Peoples R China

In this paper, we investigate the degrees of freedom (DoF) of a two-cluster multiple-input multiple-output (MIMO) multiway relay interference channel (mRIC), where there are two relays and two users per cluster. In this channel, users within the same cluster exchange messages among themselves with the help of two relays. We first obtain the DoF upper bound of the considered MIMO mRIC based on cut-set bound. Then, we propose a novel transmission strategy, blind interference neutralization (BIN), to approach the DoF upper bound. This new method utilizes the overheard information at two relays and focuses on the beamforming matrix designs at two relays so that the channel state information (CSI) at users is not required. Through theoretical analysis and numerical simulations, we show that the DoF upper bound can be obtained by using the BIN scheme. From simulation results, we show that the proposed BIN scheme can provide significant performance gain over the conventional time division multiple access (TDMA) scheme in terms of DoF. In addition, we show that the BIN scheme is a superior approach to the existing signal space alignment (SSA) schemes for the considered mRIC.

关键词： multiway relay interference channel degrees of freedom multiple-input multiple-output interference neutralization signal space alignment

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