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Mutual-Coupling Isolation Using Embedded Metamaterial EM Bandgap Decoupling Slab for Densely Packed Array Antennas

IEEE ACCESS 2019年 7卷 51827-51840页

作者： Alibakhshikenari, Mohammad Khalily, Mohsen Virdee, Bal Singh See, Chan Hwang Abd-Alhameed, Raed A. Limiti, Ernesto Univ Roma Tor Vergata Elect Engn Dept Via Politecn 1 I-00133 Rome Italy Univ Surrey Inst Commun Syst Home 5G Innovat Ctr Guildford GU2 7XH Surrey England London Metropolitan Univ Sch Comp & Digital Media Ctr Commun Technol & Math London N7 8DB England Edinburgh Napier Univ Sch Engn & Built Environm Edinburgh EH10 5DT Midlothian Scotland Univ Bolton Sch Engn Bolton BL3 5AB England Univ Bradford Fac Engn & Informat Bradford BD7 1DP W Yorkshire England Basra Univ Dept Commun & Informat Engn Coll Sci & Technol Basra 61004 Iraq

This paper presents a unique technique to enhance isolation between transmit/receive radiating elements in densely packed array antenna by embedding a metamaterial (MTM) electromagnetic bandgap (EMBG) structure in the space between the radiating elements to suppress surface currents that would otherwise contribute towards mutual coupling between the array elements. The proposed MTM-EMBG structure is a cross-shaped microstrip transmission line on which are imprinted two outward facing E-shaped slits. Unlike other MTM structures, there is no short-circuit grounding using via-holes. With this approach, the maximum measured mutual coupling achieved is -60 dB @ 9.18 GHz between the transmit patches (#1 & #2) and receive patches (#3 & #4) in a four-element array antenna. Across the antenna's measured operating frequency range of 9.12-9.96 GHz, the minimum measured isolation between each element of the array is 34.2 dB @ 9.48 GHz, and there is no degradation in radiation patterns. The average measured isolation over this frequency range is 47 dB. The results presented confirm the proposed technique is suitable in applications such as synthetic aperture radar and multiple-input multiple-output systems.

关键词： Metamaterial electromagnetic bandgap array antennas decoupling slab mutual coupling synthetic aperture radar multiple-input multiple-output

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Exact Outage Probability Analysis of Dual-Transmit-Antenna V-BLAST With Optimum Ordering

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2019年第1期68卷 977-982页

作者： Ozyurt, Serdar Torlak, Murat Yildirim Beyazit Univ Fac Engn & Nat Sci TR-06010 Ankara Turkey Univ Texas Dallas Dept Elect Engn Richardson TX 75083 USA

An exact outage probability analysis of zero-forcing V-BLAST technique with two transmit antennas and r receive antennas (r >= 2) is provided under a decoding order that is optimum in the sense of minimizing the outage probability. Different from the earlier approximated analyses, an exact closed-form expression on the outage probability is attained without neglecting the effect of error propagation. Assuming a one-bit feedback from the receiver to the transmitter, the optimal power and rate allocation values are numerically computed based on the exact outage probability expression under different objective functions. The presented results are also applicable for the corresponding dual scenarios that may involve antenna selection and/or user scheduling.

关键词： multiple-input multiple-output outage probability zero-forcing V-BLAST optimum ordering order statistics

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Spectrum sensing in cognitive radio using multitaper method based on MIMO-OFDM techniques

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ANNALS OF TELECOMMUNICATIONS 2019年第11-12期74卷 727-736页

作者： Salam, Ahmed O. Abdul Sheriff, Ray E. Al-Araji, Saleh R. Mezher, Kahtan Nasir, Qassim Univ Bradford Fac Engn & Informat Bradford BD7 1DP W Yorkshire England Univ Bolton Sch Engn Bolton BL3 5AB England Khalifa Univ Sci & Technol Coll Engn POB 127788 Abu Dhabi U Arab Emirates Univ Sharjah Coll Engn Sharjah U Arab Emirates

The current inefficient utilization of frequency spectrum has alerted regulatory bodies to streamline improvements. Cognitive radio (CR) has recently received considerable attention and is widely perceived as a promising improvement tool in estimating, or equivalently sensing, the frequency spectrum for wireless communication systems. The cognitive cycle in CR systems is capable of recognizing and processing better spectrum estimation (SE) and hence promotes the efficiency of spectrum utilization. Among different SE methods, the multi-taper method (MTM) shows encouraging results. Further performance improvement in the SE for CR can be achieved by applying multiple antennas and combining techniques. This paper proposes a constructive development of SE using MTM, abbreviated as MTSE, and by employing multiple-input multiple-output (MIMO), parsed into separate parallel channels using singular value decomposition (SVD), and maximum ratio combining (MRC) configurations. Deviating from these improvements, however, multicarrier systems such as orthogonal frequency division multiplexing (OFDM) show inferior sensing performances due to the noise multiplicity generated and combined from all subcarrier channels. By means of the quadrature matrix form, the probabilities for such integrated settings of SE have been derived to reach at their approximate asymptotes. Numerical simulations revealed specific better performances stemmed from coupling the fashionable MTSE and MIMO technologies.

关键词： Cognitive radio Spectrum estimation Multi-taper multiple-input multiple-output Orthogonal frequency division multiplexing Singular value decomposition

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Treating Content Delivery in Multi-Antenna Coded Caching as General Message Sets Transmission: A DoF Region Perspective

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第6期18卷 3129-3141页

作者： Cao, Youlong Tao, Meixia Shanghai Jiao Tong Univ Shanghai Inst Adv Commun & Data Sci Dept Elect Engn Shanghai 200240 Peoples R China

Coded caching can create coded multicasting and, thus, significantly accelerates content delivery in broadcast channels with receiver caches. While the original delivery scheme in coded caching multicasts each coded message sequentially, it is not optimal for multiple-input multiple-output (MIMO) broadcast channels. This paper aims to investigate the full spatial multiplexing gain in multi-antenna coded caching by concurrently transmitting all coded messages. In specific, we propose to treat the content delivery as the transmission problem with general message sets where all possible messages are present, each with different length and intended for different user set. We first obtain inner and outer bounds of the degrees of freedom (DoF) region of a K-user (M, N) broadcast channel with general message sets, with M and N being the number of transmit and receive antennas, respectively. Then for any given set of coded messages, we find its minimum normalized delivery time (NDT) by searching the optimal DoF tuple in the DoF regions. The obtained minimum NDT is optimal at antenna configuration M/N is an element of (0, 1] boolean OR [ K, infinity) and is within a multiplicative gap of M/N to optimum at M/N is an element of (1, K). Our NDT results can be evaluated for any user demand with both centralized and decentralized cache placements.

关键词： Caching multiple-input multiple-output degrees of freedom region normalized delivery time general message sets coded multicasting

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Towards Higher Spectral Efficiency: Spatial Path Index Modulation Improves Millimeter-Wave Hybrid Beamforming

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2019年第6期13卷 1348-1359页

作者： Wang, Jintao He, Longzhuang Song, Jian Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Beijing Natl Res Ctr Informat Sci & Technol Beijing 100084 Peoples R China Tsinghua Univ Shenzhen Res Inst Shenzhen 518057 Peoples R China

The combination of millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems and index modulation (IM) technique has recently constituted a novel form of mmWave hybrid beamforming. Numerous studies have been conducted to show that such a system has the potential to outperform conventional mmWave-MIMOs with respect to spectral efficiency (SE). Most of the current works focused only on designing hybrid beamforming structures to empirically achieve higher SE performance. However, a fundamental question whether IM technique can truly improve the SE of current mmWave hybrid beamforming is still left unanswered. Against such a background, in this paper, we first extend the IM-assisted mmWave system to a more generalized version, i.e., a spatial path index modulation aided mmWave (SPIM-mmWave) system, which subsumes both IM-assisted and conventional mmWave-MIMO systems as its special cases. Based on the framework of SPIM-mmWave, a fundamental study is conducted towards a theoretic condition under which SPIM-mmWave guarantees to outperform conventional mmWave-MIMO schemes. It is demonstrated that, under a specific channel condition and noise level (which will be explicitly given by our study), the SPIM-mmWave guarantees to outperform conventional mmWave-MIMO systems.

关键词： multiple-input multiple-output millimeter wave communications index modulation spatial modulation hybrid beamforming spectral efficiency

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Precoder Design for MIMO Visible Light Communications With Decision-Feedback Receivers

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IEEE PHOTONICS TECHNOLOGY LETTERS 2019年第7期31卷 521-524页

作者： Zhai, Yanrong Tong, Jun Xi, Jiangtao Hangzhou Dianzi Univ Sch Commun Engn Hangzhou 310018 Zhejiang Peoples R China Univ Wollongong Sch Elect Comp & Telecommun Wollongong NSW 2522 Australia

Decision-feedback equalization is considered for point-to-point multiple-input multiple-output visible light communication systems. Based on the geometric mean decomposition (GMD) and uniform channel decomposition (UCD), two precoders under the signal non-negativity and total average power constraints are designed for such systems. The GMD scheme can decompose the channel into multiple parallel sub-channels with equal gains. The UCD scheme further improves performance through power allocation. Simulation results of bit-error-rate and capacity are presented. It is shown that the proposed schemes can outperform conventional linear designs and the UCD scheme performs better than the GMD scheme.

关键词： Visible light communication multiple-input multiple-output uniform channel decomposition geometric mean decomposition decision feedback equalization

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A near maximum likelihood performance modified firefly algorithm for large MIMO detection

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SWARM AND EVOLUTIONARY COMPUTATION 2019年 44卷 828-839页

作者： Datta, Arijit Bhatia, Vimal Indian Inst Technol Indore Discipline Elect Engn Indore Madhya Pradesh India Indian Inst Technol Indore Signals & Software Grp Discipline Elect Engn Indore Madhya Pradesh India

To meet the ever-growing demand for high data rates, employing a large number of antennas at both the transmitter and receiver is a necessity for future advanced wireless systems. multiple-input multiple-output (MIMO) systems, which are equipped with multiple antennas, provide high data rates with high spectral efficiency. However, the design of an efficient, robust and non-erroneous detection algorithm is a huge challenge in large MIMO systems. In this paper, a stochastic bio-inspired meta-heuristic algorithm is proposed for large MIMO detection. The proposed algorithm is motivated by the bioluminescence of fireflies and uses a probabilistic metric to update solutions in the search space. Robustness of the proposed algorithm is verified under channel estimation errors at the receiver. Simulation results reveal that the proposed algorithm outperforms unordered congestion control ant colony optimization, congestion control ant colony optimization, standard particle swarm optimization, binary particle swarm optimization, memetic particle swarm optimization, firefly algorithm, firefly algorithm with neighborhood attraction, minimum mean square error and successive interference cancellation based MIMO detection techniques in terms of bit error rate (BER) performance. The proposed algorithm achieves near maximum likelihood BER performance with lower computational complexity. This makes the proposed algorithm an appropriate candidate for reliable detection in future large MIMO systems.

关键词： Firefly algorithm multiple-input multiple-output Minimum mean square error Channel estimation error Maximum likelihood Successive interference cancellation

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LR-aided sphere decoding of generalized spatial modulation signals

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2019年 109卷 8-16页

作者： Daryanavardan, Negar Derakhtian, Mostafa Neinavaie, Mohammad Gazor, Saeed Shiraz Univ Elect & Comp Engn Shiraz Iran Queens Univ Kingston ON Canada

This paper presents a new low complexity sphere decoding (SD) for the generalized spatial modulation (GSM). We introduce a pre-processing stage using the lattice reduction (LR) aided minimum mean squared error (MMSE) equalization in the GSM systems. This stage speeds up the search in the decoding tree and provides a lattice dependent (LD) initial choice of the radius. Moreover, we derive a lattice independent (LI) initial radius that guarantees the optimal performance at a high signal-to-noise ratio (SNR). We also propose an iterative method to increase the radius in order to achieve the maximum likelihood (ML) performance at all SNRs. We show that the proposed algorithm achieves the ML performance while requiring prominently less computational complexity (CC) than an exhaustive search. In addition, we analyze the CC of the resulting algorithm at high SNRs and we derive an analytical expression for the complexity. The simulation results demonstrate a noticeable decrease in the CC of the proposed sphere decoding algorithm in comparison with its counterparts, particularly at low SNRs. (C) 2019 Published by Elsevier GmbH.

关键词： Computational complexity Sphere decoding multiple-input multiple-output Generalized spatial modulation

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Atmospheric turbulence mitigation using spatial mode multiplexing and modified pulse position modulation in hybrid RF/FSO orbital-angular-momentum multiplexed based on MIMO wireless communications system

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OPTICS COMMUNICATIONS 2019年 436卷 197-208页

作者： Yousif, Bedir B. Elsayed, Ebrahim Eld Alzalabani, Mahmoud M. Kafrelsheikh Univ Fac Engn Elect & Commun Engn Dept Kafrelsheikh 35514 Egypt Mansoura Univ Fac Engn Elect & Commun Engn Dept Mansoura 35516 Egypt

In this paper, the capacity of a free-space optical (FSO) communication over radio frequency (RF) could potentially be increased by the simultaneous transmission of multiple orbital angular momentum (OAM) based on spatial mode multiplexing (SMM) as an additional effective degree of freedom (EDOF) and quadrature amplitude modulation (QAM). This paper describes using hybrid RF/FSO-OAM based on multiple-input multiple-output (MIMO)/SMM using M-ary modified pulse position modulation (MPPM) and spatial PPM (SPPM) for potentially enhancing capacity in wireless communication systems. We present an analytical system design concerning OAM multiplexing and MIMO/SMM processing in free space communications channel under atmospheric turbulence (AT). Here, we assume a new architecture that closes the gap in speeds between millimeter-wave (mm-wave) wireless and optical links. In this study, we highlight recent advances in the use of OAM multiplexing for highcapacity FSO and mm-wave communications. We have developed the MPPM in FSO communication over RF using the source Gaussian model and SMM by proposing a new version of hybrid SPPM and MPPM. The novelty approach presents performance enhancement of the acquisition, pointing, tracking position and AT mitigation of link. We propose to use SMM combined with OAM-QAM based MIMO communications system to mitigate both weak and strong turbulence distortions. Simulation results show that the capacity of OAM-based MIMO system outperforms the capacity of the conventional MIMO system when the propagation distance is larger than a specific threshold. The use of transmitter lenses could enhance the OAM beams with a larger mode spacing (MS) of 2 (OAM l = +1, l = +3, l = +5, l = +7 transmitted) shows a lower power penalty (PP) when the inter-channel crosstalk overwhelms a larger lateral displacement of about 2 mm. Using the lenses at the transmitter to focus OAM beams could reduce power loss and PP in OAM-based FSO links and that this improvement

关键词： Free space optical communications Millimeter-wave communications Orbital angular momentum multiple-input multiple-output Modified pulse position modulation Spatial mode multiplexing

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Low-complexity adaptive tracking control of MIMO nonlinear systems with unknown control directions

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INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL 2019年第7期29卷 2203-2222页

作者： Zhang, Jin-Xi Yang, Guang-Hong Northeastern Univ Coll Informat Sci & Engn Shenyang 110819 Liaoning Peoples R China Northeastern Univ State Key Lab Synthet Automat Proc Ind Shenyang 110819 Liaoning Peoples R China

This paper is concerned with the tracking control problem for a class of multiple-input-multiple-output systems with unmatched disturbances and the unknown additive and multiplicative nonlinearities. The objective is to provide a low-complexity control solution in the sense that (i) approximating structures are not involved, despite unknown nonlinearities and (ii) iterative calculations of command derivatives are avoided in the backstepping design. A robust adaptive control strategy is proposed to fulfill the task. In the control design, a new-type adaptive law is first developed to update Nussbaum gains to handle control direction uncertainties, while ensuring Nussbaum gains bounded. Then, the potential robustness of error constraint techniques is exploited to counteract the effects of unknown nonlinearities and disturbances and achieve predefined transient and steady-state tracking performance. Finally, simulation results are given to illustrate the above theoretical findings.

关键词： adaptive control low-complexity multiple-input multiple-output nonlinear systems unknown control directions

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