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On the capacity of orthogonalised correlated MIMO channels under different adaptive transmission techniques

IET COMMUNICATIONS 2007年第3期1卷 464-471页

作者： Musavian, L. Nakhai, M. R. Kings Coll London Ctr Telecommun Res London WC2R 2LS England

Orthogonal space-time block codes (STBCs) are known to orthogonalise the multiple-input multiple-output (MIMO) wireless channel, thus reducing the space-time vector detection to a simpler scalar detection problem. The capacity of STBCs over correlated Rayleigh and Ricean flat-fading MIMO channels under different adaptive transmitting techniques is studied. Three adaptive schemes known as optimal power and rate allocation, total channel inversion with fixed rate policy and its truncated variant are studied. Taking into account the effect of channel correlation, closed-form expressions are obtained for the capacity of orthogonalised Rayleigh and Ricean MIMO channels under these adaptive transmission techniques in order to avoid Monte-Carlo simulations.

关键词： block codes scalar detection problem MIMO communication adaptive codes channel capacity rate allocation wireless channel Rayleigh channels channel allocation multiple-input multiple-output Rayleigh-Ricean flat-fading channel Rician channels STBC orthogonal codes channel inversion channel coding space-time codes adaptive transmission technique space-time block code orthogonalized correlated MIMO channel

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Symbol Error Rate of MIMO MRC Systems over Time-Varying Fading Channels

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WIRELESS PERSONAL COMMUNICATIONS 2011年第4期56卷 669-674页

作者： Rui, Xianyi Yu, Yibiao Soochow Univ Sch Elect & Informat Engn Suzhou 215006 Peoples R China

The outdated channel state information (CSI) at the transmitter and receiver, which is resulted from time variation of channels, is considered in multiple-input multiple-output systems employing maximal ratio combining. Closed-form expressions for the cumulative distribution function of output signal-to-noise ratio and symbol error rate under time-varying channels are presented to evaluate the effect of outdated CSI. The analytical results are compared with Monte Carlo simulations and a good agreement is obtained.

关键词： multiple-input multiple-output Maximal ratio combining Symbol error rate Time-varying fading channel

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A low complexity branch-and-bound-based decoder for V-BLAST systems with PSK signals

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SIGNAL PROCESSING 2009年第2期89卷 197-205页

作者： Minh-Tuan Le Van-Su Pham Mai, Linh Yoon, Giwan Informat & Commun Univ Sch Engn Taejon 305732 South Korea 1 Posts & Telecommun Inst Technol Fac Elect Ha Dong City Ha Tay Vietnam

In this paper, a fist sphere decoder is proposed for the joint detection of phase-shift keying (PSK) signals in uncoded Vertical Bell Laboratories Layered Space Time (V-BLAST) systems. The proposed decoder consists of preprocessing stage and search stage. The preprocessing stage is based oil the enhancement of the ordering mean square error decision feedback equalizer (MMSE-DFE). Its role is to generate a tree structure Suitable for the search stage. The search stage relies on the depth-first brand-and-bound (BB) algorithm with "best-first" orders stored in lookup tables. Simulation results show that the proposed decoder is able to provide the system with the maximum likelihood (ML) performance at low complexity. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Space-time coding multiple-input multiple-output Maximum likelihood detection Diversity Wireless communication

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A Low-Profile Pattern Reconfigurable MIMO Antenna

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IEEE ACCESS 2020年 8卷 34500-34506页

作者： Han, Liping Ping, Yiwei Liu, Yufeng Han, Guorui Zhang, Wenmei Shanxi Univ Coll Phys & Elect Engn Taiyuan 030006 Peoples R China

A low-profile pattern reconfigurable multiple-input multiple-output (MIMO) antenna is demonstrated in this paper. The antenna element is composed of a rectangular monopole and two sets of parasitic strips loaded with PIN diodes. The parasitic strips can operate as a reflector or a director by switching the PIN diodes on or off. As a result, the element provides a bidirectional mode and two directional modes. The MIMO antenna consists of two elements, which are arranged opposite to each other. Two decoupling strips are introduced to improve the isolation between the elements. The simulation and measurement results illustrate that the proposed antenna has nine pattern configurations. The overlapped bandwidth of the nine modes is 10.6%, and the isolation is greater than 16.5 dB. Also, a good diversity performance is obtained.

关键词： MIMO communication Antenna radiation patterns Strips Bandwidth PIN photodiodes Reflection coefficient Low-profile pattern reconfigurable multiple-input multiple-output PIN diode

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On the DoF Region for the Asymmetric MIMO Two-Way X Relay Channel

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IEEE TRANSACTIONS ON COMMUNICATIONS 2018年第1期66卷 119-132页

作者： Liu, Kangqi Yuan, Xiaojun Tao, Meixia Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200240 Peoples R China Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu 611731 Sichuan Peoples R China

In this paper, we study the degrees of freedom (DoF) region for the multiple-input multiple-output two-way X relay channel with asymmetric antenna setting. In this channel model, there are two groups of source nodes, each group contains two source nodes, every source node in one group exchanges independent messages with every source node in another group via a common relay node, and each node has a different number of antennas. First, we derive an outer bound of the DoF region by using the cut-set theorem and the genie-message approach. Then, we obtain an inner bound of the DoF region by proposing a new transmission scheme that collectively utilizes antenna deactivation, pairwise signal alignment, cyclic signal alignment, and generalized signal alignment techniques. In the case of symmetric data exchange, our inner bound coincides with the outer bound, and thus, our proposed transmission strategy is optimal. We also obtain the optimal sum DoF for the special case, where the source nodes within a same group are equipped with the same number of antennas. This paper provides new insights for the study of more complicated relay networks.

关键词： multiple-input multiple-output two-way relay channel interference alignment signal alignment degrees of freedom

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SLNR-Based Transmit Beamforming for MIMO Wiretap Channel

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WIRELESS PERSONAL COMMUNICATIONS 2013年第1期71卷 109-121页

作者： Wang, Kun Wang, Xiyuan Zhang, Xianda Tsinghua Univ Dept Automat Tsinghua Natl Lab Informat Sci & Technol Beijing 100084 Peoples R China

In this paper, a novel closed-form transmit beamforming scheme is proposed for multiple-input multiple-output (MIMO) wiretap channel. The proposed method follows the idea of maximizing signal-to-leakage-plus-noise ratio and does not need additional power allocation. An efficient approach is further developed to implement the generalized eigenvalue decomposition required by our method when n (r) < n (t) (n (t) , n (r) and n (e) denote the antenna numbers at the transmitter, the intended receiver and the eavesdropper, respectively), which has lower complexity than the existing approaches. Moreover, we identify some shortcomings of the generalized singular value decomposition (GSVD) based beamforming method, a common beamforming scheme for MIMO wiretap channel. Finally, simulation results show that the proposed method significantly outperforms GSVD-based method when n (e) < n (t) and has almost the same performance as GSVD-based method when n (e) a parts per thousand yen n (t) .

关键词： multiple-input multiple-output Wiretap channel Transmit beamforming Signal-to-leakage-plus-noise ratio

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Performance Improvement of Radio-Wave Encrypted MIMO Communications Using Average LLR Clipping

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IEICE TRANSACTIONS ON COMMUNICATIONS 2022年第8期E105B卷 931-943页

作者： Okumura, Mamoru Asano, Keisuke Abe, Takumi Okamoto, Eiji Yamamoto, Tetsuya Nagoya Inst Technol Grad Sch Engn Dept Comp Sci & Engn Nagoya Aichi 4668555 Japan Panasonic Corp Digital & AI Technol Ctr Technol Div Yokohama Kanagawa 2248539 Japan

In recent years, there has been significant interest in information-theoretic security techniques that encrypt physical layer signals. We have proposed chaos modulation, which has both physical layer security and channel coding gain, as one such technique. In the chaos modulation method, the channel coding gain can be increased using a turbo mechanism that exchanges the log-likelihood ratio (LLR) with an external concatenated code using the max-log approximation. However, chaos modulation, which is a type of Gaussian modulation, does not use fixed mapping, and the distance between signal points is not constant;therefore, the accuracy of the max-log approximated LLR degrades under poor channel conditions. As a result, conventional methods suffer from performance degradation owing to error propagation in turbo decoding. Therefore, in this paper, we propose a new LLR clipping method that can be optimally applied to chaos modulation by limiting the confidence level of LLR and suppressing error propagation. For effective clipping on chaos modulation that does not have fixed mappings, the average confidence value is obtained from the extrinsic LLR calculated from the demodulator and decoder, and clipping is performed based on this value, either in the demodulator or the decoder. Numerical results indicated that the proposed method achieves the same performance as the one using the exact LLR, which requires complicated calculations. Furthermore, the security feature of the proposed system is evaluated, and we observe that sufficient security is provided.

关键词： radio-wave encryption chaos modulation physical layer security LLR clipping multiple-input multiple-output

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A novel range ambiguity resolving approach for high-resolution and wide-swath SAR imaging utilizing space-pulse phase coding

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SIGNAL PROCESSING 2020年 168卷 107323-000页

作者： Wang, Hanbing Zhang, Yuhong Xu, Jingwei Liao, Guisheng Zeng, Cao Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Shaanxi Peoples R China Xidian Univ Sch Elect Engn Xian 710071 Shaanxi Peoples R China

High-resolution and wide-swath (HRWS) imaging is highly desired in future synthetic aperture radar (SAR) systems. However, it is a contradictory requirement between high azimuth resolution and wide unambiguous swath coverage in a traditional SAR system. This paper proposes a novel solution to realize HRWS imaging by resolving the range ambiguity through a phase coding technique. The phase coding is employed in both spatial channels and slow time pulses. By properly designing the coding scheme, it is possible to separate the echoes from multiple ambiguous range regions from each other in the spatial domain. For each particular range region, the corresponding optimized receive beampattern can be used to extract the desired echoes from the presumed range region and suppress the undesired echoes from other range-ambiguous regions. The residual range-ambiguous echoes are also addressed. Specifically, it is capable of further mitigating the residual range-ambiguous echoes by optimally designing the coding scheme and the transmit beampattern. In the final, a bank of imaging processors can be implemented to obtain the high-resolution images of these range regions, which can be synthesized into a whole HRWS SAR image of the scene of interest. Simulation results have demonstrated the effectiveness of the proposed method. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Synthetic aperture radar High-resolution and wide-swath Space-pulse phase coding Range ambiguity multiple-input multiple-output

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MIMO Architecture for Coherent Optical Wireless Communication: System Design and Performance

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JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2013年第5期5卷 411-420页

作者： Niu, Mingbo Cheng, Julian Holzman, Jonathan F. Univ British Columbia Sch Engn Kelowna BC V1V 1V7 Canada

A coherent multiple-input multiple-output architecture is proposed for optical wireless communications (OWCs) to mitigate atmospheric turbulence effects. Transmitter optical signals operate at distinct carrier frequencies to allow the received optical signals to be separately processed. The accumulated phase noise in each transmission branch can then be independently and electrically compensated. Based on the proposed architecture, several diversity combining techniques are used at the receiver end for system performance evaluation. Three different turbulence models are considered in this paper for different scintillation level ranges, including gamma-gamma turbulence, K-distributed turbulence, and negative exponential turbulence. Closed-form error rate expressions are derived using a series expansion approach. The diversity order in the gamma-gamma turbulence channel is found to depend only on the smaller channel parameter, while the K-distributed and negative exponential turbulence channels are found to have the same diversity order. The presented numerical results demonstrate substantial system performance improvement over single-link coherent OWC.

关键词： multiple-input multiple-output Optical wireless communication Turbulence channels Wavelength diversity

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Experimental Demonstration of High-Speed 4 x 4 Imaging Multi-CAP MIMO Visible Light Communications

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2018年第10期36卷 1944-1951页

作者： Werfli, Khald Chvojka, Petr Ghassemlooy, Zabih Hassan, Navid Bani Zvanovec, Stanislav Burton, Andrew Haigh, Paul Anthony Bhatnagar, Manav R. Northumbria Univ Opt Commun Res Grp Newcastle Upon Tyne NE1 8ST Tyne & Wear England Czech Tech Univ Dept Electromagnet Field Prague 16627 Czech Republic Chinese Acad Sci QIEM Beijing 100864 Peoples R China UCL Dept Elect & Elect Engn London WC1E 6BT England Indian Inst Technol Delhi New Delhi 110016 India

In general, visible light communication (VLC) systems, which utilise white light-emitting diodes (LEDs), only offer a bandwidth limited to the lower MHz region. Therefore, providing VLC-based high data rate communications systems using VLC becomes a challenging task. To address this challenge, we propose a solution based on multiplexing in both the frequency and space domains. We experimentally demonstrate a 4 x 4 imaging multiple-input multiple-output (MIMO) VLC system (i.e., space multiplexing) utilising multiband carrierless amplitude and phase (m-CAP) modulation (i.e., frequency multiplexing). Independently, both MIMO and m-CAP have separately shown the remarkable ability to improve the transmission speeds in VLC systems, and hence, here we combine them to further improve the net data rate. We investigate the link performance by varying the number of sub-carriers m, link distance L, and signal bandwidth B-sig. From all the values tested, we show that a data rate of similar to 249 Mb/s can be maximally achieved for m = 20, B-sig = 20 MHz, and L = 1m, at a bit error rate of 3.2 x 10(-3) using LEDs with similar to 4 MHz bandwidth.

关键词： Modulation bandwidth multi-band carrier-less amplitude and phase modulation multiple-input multiple-output visible light communications

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