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Opportunistic Spectrum Sharing in Relay-Assisted Cognitive Systems With Imperfect CSI

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2014年第5期63卷 2224-2235页

作者： Hamdi, Karama Hasna, Mazen O. Ghrayeb, Ali Ben Letaief, Khaled Qatar Univ Dept Elect Engn Doha 2713 Qatar Texas A&M Univ Qatar Dept Elect & Comp Engn Doha Qatar Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Kowloon Hong Kong Peoples R China

In this paper, we consider spectrum sharing between cognitive radio (CR) users and a licensed primary user (PU) to enhance the spectrum efficiency. In the considered scenario, the PU is not able to successfully transmit data to the intended receiver. In this case, the cognitive base station (CBS) in the vicinity of the primary network offers its help to transmit the primary data. In return, the CR system shares the spectrum with the primary system. In particular, we formulate an opportunistic spectrum sharing approach that determines the optimal beamforming weights at the CBS to maximize the overall worst throughput of the CRs while guaranteeing a certain quality of service (QoS) for the PU. Various formulations of beamforming are proposed, which consider different relaying scenarios, including robust designs that are applicable with imperfect channel state information (CSI) at the PU. The original optimization problems are nonconvex and do not have any closed-form solutions. However, using a convex optimization approach, we transform them into convex forms and find approximate solutions using semidefinite programming (SDP) along with randomization techniques. We consider different examples that demonstrate the efficiency of the proposed approach.

关键词： Broadcast channels cognitive radio (CR) multiple-input-multiple-output relaying semidefinite programming (SDP) relaxation spectrum sharing

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High-Spatial-Diversity Imaging Receiver Using Fisheye Lens for Indoor MIMO VLCs

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IEEE PHOTONICS TECHNOLOGY LETTERS 2014年第22期26卷 2260-2263页

作者： Chen, Te Liu, Lu Tu, Bo Zheng, Zhong Hu, Weiwei Peking Univ State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China

This letter proposes an imaging receiver scheme for an indoor multiple-input-multiple-output (MIMO) visible light communication (VLC), in which a fisheye lens with ultrawide field-of-view is used for high-quality imaging, so it can realize omnidirectional receiving and provide high-spatial diversity for decoding of the MIMO signals. In addition, the fisheye lens projects planar and small-sized images, which means that the integration with compact planar receiver array is feasible. Using the polynomial projection model, the optical intensity on the receiving plane is obtained, which is in accordance with the experimental result and shows that the images of the light-emitting diodes are clearly separated. The simulation results indicate that low correlations of the channel matrix are achieved, so high spectral efficiency is realized with various receiver positions under indoor circumstance. Consequently, this fisheyelens-based imaging receiver is a potential candidate for high-performance indoor MIMO VLC applications.

关键词： Visible light communications imaging receiver fisheye lens multiple-input-multiple-output spatial diversity

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Coordinated Multicell Precoding for Weighted Sum Rate Maximization with Per-Cell EE Constraints 80

Coordinated Multicell Precoding for Weighted Sum Rate Maximi...

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80th IEEE Vehicular Technology Conference (VTC Fall)

作者： He, Shiwen Huang, Yongming Wang, Jiaheng Wang, Haiming Jin, Shi Yang, Luxi Southeast Univ Sch Informat Sci & Engn Nanjing 210096 Jiangsu Peoples R China Southeast Univ State Key Lab Millimeter Waves Dept Radio Engn Nanjing 210096 Jiangsu Peoples R China

ISBN: (纸本)9781479944491

Spectral efficiency (SE) and energy efficiency (EE) are both essential in future wireless communications. To improve the system performance on these two metrics, in this paper we consider the weighted sum rate maximization (WSRMax) problem subject to per-cell EE constraints and per-BS transmit power constraints in multicell multiuser downlink systems. This problem is difficult in its original form due to the introduction of new EE constraints. We first reveal that the original problem can be transformed into an equivalent parameterized polynomial form by introducing some auxiliary variables. By exploiting the concavity property with respect to each variable in the equivalent problem, an efficient block coordinate ascent algorithm is then proposed with guaranteed convergence property. Numerical results show that compared with the conventional WSRMax algorithm, in addition to fulfilling the EE requirement of each cell, our algorithm achieves a better system EE performance at the cost of a slight sum rate performance loss at a certain region and offers a new insight on the SE-EE tradeoff in wireless communication systems.

关键词： Weighted Sum Rate Maximization Per-Cell EE Constraints multiple-input-multiple-output

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Experimental Demonstration of 16 Gbit/s millimeter-wave Communications using MIMO Processing of 2 OAM Modes on Each of Two Transmitter/Receiver Antenna Apertures

Experimental Demonstration of 16 Gbit/s millimeter-wave Comm...

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IEEE Global Communications Conference (GLOBECOM)

作者： Ren, Yongxiong Li, Long Xie, Guodong Yan, Yan Cao, Yinwen Huang, Hao Ahemd, Nisar Lavery, Martin J. Zhao, Zhe Zhang, Chongfu Tur, Moshe Padgett, Miles Caire, Giuseppe Molisch, Andreas F. Willner, Alan E. Univ So Calif Dept Elect Engn Los Angeles CA 90089 USA Univ Glasgow Sch Phys & Astron Glasgow G12 8QQ Lanark Scotland Univ Elect Sci & Technol China Chengdu 61731 Peoples R China Tel Aviv Univ Sch Elect Engn IL-69978 Ramat Aviv Israel

ISBN: (纸本)9781479935123

This paper reports an experimental demonstration of a 16 Gbit/s millimeter-wave communication link using MIMO processing of 2 OAM modes on each of two transmitter/receiver antenna apertures. Two groups of multiplexed OAM beams, each containing OAM beams of l = 1 and + 3 are generated and transmitted through two transmitter apertures respectively. The two transmitter apertures are separated with a certain distance such that the two groups of OAM beams are spatially overlapping at the receiver aperture plane. Each channel carries 1-GBaud 16-QAM signals at the same carrier frequency of 28GHz. Our experimental results show that MIMO equalization processing can help mitigate the interferences from the other OAM channels and the BER performance of each channel improves significantly after MIMO processing. Our results indicate that OAM multiplexing and traditional spatial multiplexing combined with MIMO processing can be compatible and complementary with each other.

关键词： Orbital angular momentum multiple-input-multiple-output Millimeter-wave communications Spatial multiplexing

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ROBUST JOINT CFO AND FAST TIME-VARYING CHANNEL TRACKING FOR MIMO-OFDM SYSTEMS

ROBUST JOINT CFO AND FAST TIME-VARYING CHANNEL TRACKING FOR ...

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IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

作者： Mah, Meng Chuan Lim, Heng Siong Tan, Alan Wee Chiat Multimedia Univ Fac Engn & Technol Melaka 75450 Malaysia

ISBN: (纸本)9781479928934

In this paper, a robust joint carrier frequency offset (CFO) and fast time-varying channel tracking algorithm for MIMO-OFDM systems is proposed. The proposed method is robust to noise statistics and noise distribution uncertainties. The extended H filter (EHF) is employed for the joint tracking process as it does not require any knowledge of noise statistics or noise distribution, unlike the conventional extended Kalman filter (EKF). To reduce computational complexity, the tracking of fast time-varying channel gains is facilitated by the basis expansion model (BEM). Simulation results show that the performance of the proposed algorithm without knowledge of noise statistics matches the performance of the existing algorithm under Gaussian noise and is better than that of the existing algorithm under non-Gaussian noise.

关键词： Channel tracking carrier frequency offset extended H-infinity filter multiple-input-multiple-output orthogonal frequency-division multiplexing

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Analysis of Secrecy Rate against Eavesdroppers in MIMO Modulation Systems

Analysis of Secrecy Rate against Eavesdroppers in MIMO Modul...

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International Conference on Wireless Communications and Signal Processing

作者： Yaman Wei Li Wang Tommy Svensson School of Electronic Engineering Beijing University of Posts and Telecommunications Chalmers University of Technology

ISBN: (纸本)9781467376884

In multiple-input-multiple-output (MIMO) wireless communications, Space Shift Keying (SSK), Spatial modulation (SM) and Generalized Space Shift Keying (GSSK) are three novel MIMO modulation techniques, that can greatly reduce the complexity of MIMO systems. This paper investigates the physical-layer security in typical MIMO systems of these three modulations. We present an exhaustive analysis of secrecy rate for multiple antennas destination and eavesdroppers receivers. Without eavesdroppers channel information, both achievable secrecy rate and bit error rate (BER) are studied through joint modulated signal and jamming signal transmission. Our simulation results demonstrate that the proposed proactive source jamming method achieves improvement of secrecy rate and improved BER performance for multi-antenna users.

关键词： multiple-input-multiple-output Space shift keying Spatial modulation Generalized space shift keying Eaves-dropping Secrecy rate

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Coordinated Multicell Precoding for Weighted Sum Rate Maximization with Per-Cell EE Constraints

Coordinated Multicell Precoding for Weighted Sum Rate Maximi...

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IEEE Vehicular Technology Conference

作者： Shiwen He Yongming Huang Jiaheng Wang Haiming Wang Shi Jin Luxi Yang School of Information Science and Engineering Southeast University

ISBN: (纸本)9781479944484

关键词： Weighted Sum Rate Maximization Per-Cell EE Constraints multiple-input-multiple-output

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Experimental Demonstration of 16 Gbit/s millimeter-wave Communications using MIMO Processing of 2 OAM Modes on Each of Two Transmitter/Receiver Antenna Apertures

Experimental Demonstration of 16 Gbit/s millimeter-wave Comm...

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IEEE Global Communications Conference

作者： Yongxiong Ren Long Li Guodong Xie Yan Yan Yinwen Cao Hao Huang Nisar Ahemd Martin J. Lavery Zhe Zhao Chongfu Zhang Moshe Tur Miles Padgett Giuseppe Caire Andreas F. Molisch Alan E. Willner Department of Electrical Engineering University of Southern California School of Electrical Engineering Tel Aviv University School of Physics and Astronomy University of Glasgow

ISBN: (纸本)9781479935130

This paper reports an experimental demonstration of a 16 Gbit/s millimeter-wave communication link using MIMO processing of 2 OAM modes on each of two transmitter/receiver antenna apertures. Two groups of multiplexed OAM beams, each containing OAM beams of l=1 and +3 are generated and transmitted through two transmitter apertures respectively. The two transmitter apertures are separated with a certain distance such that the two groups of OAM beams are spatially overlapping at the receiver aperture plane. Each channel carries 1-GBaud 16-QAM signals at the same carrier frequency of 28GHz. Our experimental results show that MIMO equalization processing can help mitigate the interferences from the other OAM channels and the BER performance of each channel improves significantly after MIMO processing. Our results indicate that OAM multiplexing and traditional spatial multiplexing combined with MIMO processing can be compatible and complementary with each other.

关键词： Orbital angular momentum multiple-input-multiple-output Millimeter-wave communications Spatial multiplexing

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Two-Dimensional Block-Spread CDMA Relay Using Virtual-Four-Antenna STCDTD

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第8期62卷 3813-3827页

作者： Yu, Qi-Yue Meng, Wei-Xiao Adachi, Fumiyuki Harbin Inst Technol Dept Commun Engn Harbin 150080 Peoples R China Tohoku Univ Grad Sch Engn Dept Elect & Commun Engn Sendai Miyagi 9808579 Japan

Cooperative communication networks can exploit the spatial diversity inherent in a multiuser system by allowing users to cooperate and relay other users' messages to a destination. Avoiding the multiple-access interference (MAI) while taking full advantage of the multiuser cooperative multiple-input-multiple-output (Co-MIMO) is still an interesting problem. In this paper, we propose a relay scheme that combines the source user's two antennas and the relay user's two antennas to form a virtual-four-antenna space-time cyclic delay transmit diversity (STCDTD), and explore 2-D block-spread code-division multiple access (CDMA) to achieve MAI-free uplink transmission. The theoretical error probability of the proposed scheme is described, when a signal is transmitted through a multiple-access Rayleigh fading channel. Computer simulations indicate that the proposed scheme is able to avoid the MAI over a slow fading channel and to improve the bit error rate (BER) significantly.

关键词： Cooperative communications multiple-input-multiple-output space-time cyclic delay transmit diversity (STCDTD) 2-D block-spread code-division multiple access (CDMA)

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An UWB diversity antenna array with a novel H-type decoupling structure

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2013年第11期55卷 2715-2720页

作者： Gogosh, Nayab Shafique, M. Farhan Saleem, Rashid Usman, Imran Faiz, A. M. COMSATS Inst Informat Technol Dept Elect Engn Islamabad Pakistan COMSATS Inst Informat Technol Ctr Adv Studies Telecommun Islamabad Pakistan Univ Engn & Technol Dept Telecommun Engn Lahore Pakistan Univ Paris Est Lab ESYCOM F-77454 Marne La Vallee Champs Sur Marn France

This research work addresses the problem of mutual coupling between the antenna elements for ultra wideband diversity applications. A novel H-type decoupling structure has been proposed which successfully suppresses the mutual coupling by 7 to 10 dB as compared to the nondecoupled radiating elements. The decoupling structure has been tested for shared and isolated ground planes. The isolation between the antennas was measured to be more than 25 dB in most of the band. The feasibility of the proposed structure in diversity applications has been analyzed by measuring the envelope correlation coefficient which was found out to be less than -30 dB. (c) 2013 Wiley Periodicals, Inc.

关键词： diversity antenna multiple-input-multiple-output planar antennas ultra wideband antennas

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