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Performance of adaptive subcarrier modulated MIMO wireless optical communications in Malaga turbulence

OPTICS COMMUNICATIONS 2019年 435卷 265-270页

作者： Chen, Dan Huang, Genquan Liu, Gaohui Lei, Yu Xian Univ Technol Sch Automat & Informat Xian 710048 Shaanxi Peoples R China Xian Elect Engn Res Inst Xian 710100 Shaanxi Peoples R China

Space diversity of multiple-input multiple-output (MIMO) system combined with the adaptive subcarrier modulation technique can effectively reduce the atmospheric channel fading effects. Malaga turbulent probability density function is obtained based on the MeijerG function. The asymptotic expression of average bit error rate in non-adaptive and adaptive modulated MIMO wireless optical systems are derived respectively, and M-ary phase shift keying (MPSK) and M-ary differential phase shift keying (MDPSK) modulation are used in these two kinds of systems. Under moderate turbulence conditions, error performances are analyzed with numerical simulations between these two systems. The results show that the average bit error performance in the adaptive modulated system can be significantly better than the non-adaptive modulated system. But under the same conditions of modulation order and target bit error rate, error performance of non-adaptive modulation is easier to be affected by transmit and receive aperture number than adaptive modulation in MIMO system.

关键词： Optical communication Malaga turbulence Adaptive modulation multiple-input multiple-output Error performance

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Signal Shaping for Generalized Spatial Modulation and Generalized Quadrature Spatial Modulation

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第8期18卷 4047-4059页

作者： Guo, Shuaishuai Zhang, Haixia Zhang, Peng Dang, Shuping Liang, Cong Alouini, Mohamed-Slim King Abdullah Univ Sci & Technol Comp Elect & Math Sci & Engn Div Thuwal 23955 Saudi Arabia Shandong Univ Sch Control Sci & Engn Shandong Prov Key Lab Wireless Commun Technol Jinan 250061 Shandong Peoples R China Weifang Univ Sch Comp Engn Weifang 261061 Peoples R China

This paper investigates the generic signal shaping methods for the multiple-data-stream generalized spatial modulation (GenSM) and the generalized quadrature spatial modulation (GenQSM). Three cases with different channel state information at the transmitter (CSIT) are considered, including no CSIT, statistical CSIT, and perfect CSIT. A unified optimization problem is formulated to find the optimal transmit vector set under size, power, and sparsity constraints. We propose an optimization-based signal shaping (OBSS) approach by solving the formulated problem directly and a codebook-based signal shaping (CBSS) approach by finding the sub-optimal solutions in discrete space. In the OBSS approach, we reformulate the original problem to optimize the signal constellations used for each transmit antenna combination (TAC). Both the size and the entry of all signal constellations are optimized. Specifically, we suggest the use of a recursive design for the size optimization. The entry optimization is formulated as a non-convex large-scale quadratically constrained quadratic programming (QCQP) problem and can be solved by the existing optimization techniques with rather high complexity. To reduce the complexity, we propose the CBSS approach using a codebook generated by the quadrature amplitude modulation (QAM) symbols and a low-complexity selection algorithm to choose the optimal transmit vector set. The simulation results show that the OBSS approach exhibits the optimal performance in comparison with existing benchmarks. However, the OBSS approach is impractical for large-size signal shaping and adaptive signal shaping with instantaneous CSIT due to the demand of high computational complexity. As a low-complexity approach, the CBSS shows comparable performance and can be easily implemented in large-size systems.

关键词： multiple-input multiple-output generalized spatial modulation generalized quadrature spatial modulation signal shaping preceding maximizing the minimum euclidean distance sparsity constraint

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The performance analysis of multi-hop MIMO free space optical communications with space-time block codes over exponentiated Weibull fading channels

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OPTICS COMMUNICATIONS 2019年 442卷 95-100页

作者： Huang, Chao Wang, Ping Pang, Weina Guo, Lixin Liu, Xiaoxia Xidian Univ Sch Telecommun Engn State Key Lab Integrated Serv Networks Xian 710071 Shaanxi Peoples R China Xidian Univ Sch Phys & Optoelect Engn Xian 710071 Shaanxi Peoples R China

The symbol error rate (SER) performance of decode-and-forward (DF) based multiple-input multiple-output (MIMO) mull-hop free-space optical (FSO) systems is investigated with space-time block coding (STBC) over the exponentiated Weibull (EW) fading channel. The moment generating function (MGF) and Gauss-Laguerre quadrature rule are adopted to derive the end-to-end (EE) analytical SER expressions for this considered FSO communication system. The SER performance is further studied under various hops, STBC schemes, and turbulence conditions detailly. In addition, the asymptotic EE SER expressions are obtained to evaluate the diversity orders. Results show that the SER performances of this FSO system under EW atmospheric turbulence distribution can be improved considerably by employing the STBC scheme, and the diversity order depends not only on the numbers of transmitting and receiving antennas, but also on the channel fading parameters. The SERB of EW distribution are compared with Lognormal (LN) and gamma-gamma (G-G) distributions in weak and strong turbulence atmosphere, respectively. We also verify these analytical results through Monte Carlo simulations. This work is beneficial to the design of FSO system.

关键词： Exponentiated Weibull distribution Multi-hop Free-space optical communications multiple-input multiple-output Space-time block codes

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Tree physiology optimization on SISO and MIMO PID control tuning

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NEURAL COMPUTING & APPLICATIONS 2019年第11期31卷 7571-7581页

作者： Halim, A. Hanif Ismail, I. Univ Teknol PETRONAS Elect & Elect Engn Dept Tronoh 31750 Perak Malaysia

The tuning of proportional-integral-derivative (PID) controller is essential for any control application in order to ensure the best performance by step change or disturbance. This paper presents the tuning of PID controller for single-input single-output (SISO) and multiple-input multiple-output (MIMO) control systems using tree physiology optimization (TPO). TPO is a metaheuristic algorithm inspired from a plant growth system derived based on the idea of plant architecture and Thornley model (TM). The basic principle of TM simplifies the plant growth into shoots and roots part. The plant shoots grow towards sunlight with the help of nutrients supplied by the root system in order to undergo photosynthesis process, a process of converting light photon into carbon. The carbon gain from the shoots extension will be supplied to the root system in order for the root to grow and search for water plus nutrients. As a result, the nutrients are supplied upwards towards shoot system for further extension. This concept runs iteratively in order to ensure optimum plant growth. The iterative search of shoot towards better light supported by the root counterparts leads to an optimization idea of TPO algorithm. TPO also has a unique exploration strategy due to its multiple branches and shoots that can be defined by user. This concept may improve the search mechanism with a better trade-off between diversification and intensification search. A simulation of SISO control system and an industrial application of MIMO control are applied to demonstrate the effectiveness of the proposed algorithm and compared with other optimization methods such as particle swarm optimization, Ziegler-Nichols, Tyreus-Luyben and Chien-Hrones-Reswick methods. The results clearly exhibit the capability of TPO algorithm towards finding the optimum PID parameters for SISO and MIMO process with faster settling time and better performance with respect to other methods.

关键词： Single-input single-output multiple-input multiple-output Tree physiology optimization Particle swarm optimization Ziegler-Nichols Tyreus-Luyben Chien-Hrones-Reswick

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Degrees of Freedom of Multi-Cell MIMO Interference Broadcast Channels With Distributed Base Stations

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KSII TRANSACTIONS ON INTERNET AND INFORMATION SYSTEMS 2019年第2期13卷 635-656页

作者： Huang, Hongbing Liu, Junyi Zhang, Yi Cai, Qing Zhang, Bowei Jiang, Fengwen State Grid Zhejiang Elect Power Co Ltd Informat & Telecommun Branch Hangzhou 310026 Zhejiang Peoples R China Chongqing Univ Coll Commun Engn Chongqing 400044 Peoples R China

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

关键词： Degrees of freedom interference broadcast channel channel state information multiple-input multiple-output interference alignment

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Secure Transmission for Interference Networks: User Selection and Transceiver Design

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IEEE SYSTEMS JOURNAL 2019年第3期13卷 2839-2850页

作者： Zhao, Nan Cao, Qiuyi Gui, Guan Cao, Yang Zhang, Shun Chen, Yunfei Sari, Hikmet Dalian Univ Technol Sch Informat & Commun Engn Dalian 116023 Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Shaanxi Peoples R China Nanjing Univ Posts & Telecommun Nanjing 210028 Jiangsu Peoples R China Univ Warwick Sch Engn Coventry CV4 7AL W Midlands England Sequans Commun F-92700 Colombes France

Interference is usually regarded as a detrimental factor that degrades the performance of a wireless network. However, when it is used properly, the security of transmission can be effectively improved. In this paper, user selection and transceiver design are proposed to guarantee the secure transmission in a multiple-input multiple-output interference network with an eavesdropper. First, user selection is performed to select the most suitable user to transmit confidential information according to the topology and path loss in each time slot among all users. Then, based on user selection, the transceivers of the users are jointly designed to maximize the secrecy rate of the selected user while guaranteeing a minimum transmission rate for other users. Due to the nonconvexity of the optimization problem, it is transformed into a convex second-order cone programming with the help of successive approximations. An alternate iteration algorithm is proposed to obtain the optimal solution. The fairness of the user selection is considered, and a modified scheme is proposed to share the opportunity of secure transmission among users. Finally, simulation results are presented to show the effectiveness and efficiency of the proposed schemes.

关键词： Interference networks multiple-input multiple-output physical layer security secrecy rate transceiver design user selection

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Blind Identification of SFBC-OFDM Signals Based on the Central Limit Theorem

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第7期18卷 3500-3514页

作者： Gao, Mingjun Li, Yongzhao Dobre, Octavia A. Al-Dhahir, Naofal Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Shaanxi Peoples R China Mem Univ Dept Elect & Comp Engn St John NF A1B 3X5 Canada Univ Texas Dallas Dept Elect & Comp Engn Richardson TX 75080 USA

Previous approaches for blind identification of space-frequency block codes (SFBCs) do not perform well for short observation periods due to their inefficient utilization of frequency-domain redundancy. This paper proposes a hypothesis test (HT)-based algorithm and a support vector machine (SVM)-based algorithm for the SFBC signals' identification over frequency-selective fading channels to exploit two-dimensional space-frequency domain redundancy. Based on the central limit theorem, space-domain redundancy is used to construct the cross-correlation function of the estimator and frequency-domain redundancy is incorporated in the construction of the statistics. The difference between two proposed algorithms is that the HT-based algorithm constructs a chi-square statistic and employs an HT to make the decision, while the SVM-based algorithm constructs a non-central chi-square statistic with unknown mean as a strongly distinguishable statistical feature and uses SVM to make the decision. Both the algorithms do not require knowledge of the channel coefficients, modulation type, or noise power, and the SVM-based algorithm does not require timing synchronization. The simulation results verify the superior performance of the proposed algorithms for short observation periods with comparable computational complexity to conventional algorithms, as well as their acceptable identification performance in the presence of transmission impairments.

关键词： Blind identification multiple-input multiple-output orthogonal frequency division multiplexing space-frequency block code support vector machine (SVM)

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Energy Efficient Precoder in Multi-User MIMO Systems With Imperfect Channel State Information

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IEEE WIRELESS COMMUNICATIONS LETTERS 2019年第3期8卷 669-672页

作者： Vaezy, Hossein Omidi, Mohammad Javad Yanikomeroglu, Halim Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

This letter is on the energy efficient precoder design in multi-user multiple-input multiple-output systems which is also robust with respect to the imperfect channel state information at the transmitters. In other words, we design the precoder matrix associated with each transmitter to maximize the general energy efficiency of the network. We investigate the problem in two conventional cases. The first case considers the statistical characterization for the channel estimation error that leads to a quadratically constrained quadratic program with a semi-closed-form solution. Then, we turn our attention to the case which considers only the uncertainty region for the channel estimation error;this case eventually results in a semi-definite program.

关键词： multiple-input multiple-output precoder general energy efficiency

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Decentralized Precoding for Cache-Enabled Ultra-Dense Radio Access Networks

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IEEE WIRELESS COMMUNICATIONS LETTERS 2019年第2期8卷 404-407页

作者： He, Shiwen Chen, Yiyun Ren, Ju Huang, Yongming Yang, Luxi Zhang, Yaoxue Cent S Univ Sch Informat Sci & Engn Changsha 410083 Hunan Peoples R China Jiangxi Univ Finance & Econ Sch Informat Technol Nanchang 330032 Jiangxi Peoples R China Southeast Univ Sch Informat Sci & Engn Nanjing 210096 Jiangsu Peoples R China

This letter studies the fully decentralized optimization of the preceding matrices for the downlink of multiple-input-multiple-output cache-enabled ultra-dense radio access network. To avoid signalling exchange between coordinated edge radio access nodes (RANs), we first construct a virtual downlink cache-enabled ultra-dense radio access network. Following, a new concept of signal-to-interference-leakage-plusnoise ratio is defined. Based on this concept, a virtual weighted sum rate maximization problem is formulated to optimize the precoders. We then propose a computationally efficient decentralized optimization algorithm that achieves stationary point to the problem. Numerical results show that the proposed algorithm can achieve more than 96.15% of the performance of the centralized optimization without any signalling exchange between coordinated edge RANs for multiple-input single-output cases.

关键词： Interference network multiple-input multiple-output edge caching decentralized optimization

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Optical spatial modulation design

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PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 2020年第2169期378卷 20190195-20190195页

作者： Cogalan, T. Haas, H. Panayirci, E. Univ Edinburgh Li Fi R&D Ctr Edinburgh EH9 3J1 Midlothian Scotland Kadir Has Univ Dept Elect & Elect Engn TR-34083 Istanbul Turkey

Visible light communication (VLC) systems are inherently signal-to-noise ratio (SNR) limited due to link budget constraints. One favourable method to overcome this limitation is to focus on the pre-log factors of the channel capacity. multiple-input multiple-output (MIMO) techniques are therefore a promising avenue of research. However, inter-channel interference in MIMO limits the achievable capacity. Spatial modulation (SM) avoids this limitation. Furthermore, the performance of MIMO systems in VLC is limited by the similarities among spatial channels. This limitation becomes particularly severe in intensity modulation/direct detection (IM/DD) systems because of the lack of phase information. The motivation of this paper is to propose a system that results in a multi-channel transmission system that enables reliable multi-user optical MIMO SM transmission without the need for a precoder, power allocation algorithm or additional optics at the receiver. A general bit error performance model for the SM system is developed for an arbitrary number of light-emitting diodes (LEDs) in conjunction with pulse amplitude modulation. Based on this model, an LED array structure is designed to result in spatially separated multiple channels by manipulating the transmitter geometry. This article is part of the theme issue 'Optical wireless communication'.

关键词： light-fidelity multiple-input multiple-output spatial modulation intensity modulation and direct detection pulse amplitude modulation multi-user multiple-input multiple-output

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