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Coupled Few-Mode Multicore Fiber With Low Differential Mode Delay Characteristics

JOURNAL OF LIGHTWAVE TECHNOLOGY 2017年第6期35卷 1222-1227页

作者： Sakamoto, Taiji Mori, Takayoshi Wada, Masaki Yamamoto, Takashi Yamamoto, Fumihiko Nakajima, Kazuhide Nippon Telegraph & Tel Corp Access Network Serv Syst Labs Tsukuba Ibaraki 3050805 Japan

We investigate a coupled few-mode multicore fiber (FM-MCF) design to realize an ultrahigh spatial density space division multiplexing (SDM) transmission line with low differential mode delay (DMD) characteristics. We describe a super-mode-based FM-MCF design that takes account of the DMD between modes in the inter-linearly polarized ( LP) mode group (e.g., between LP01- and LP11 - like super modes). We also show a randomly coupled FM-MCF design based on fiber bending and twisting to reduce the DMD between modes in the intra-LP mode group. We fabricated a coupled three-mode seven-core fiber and realized a low DMD value of less than 0.2 ns/km for allmodes where the intercore nonuniformity induced DMD was successfully suppressed owing to distributed random mode coupling. The fabricated fiber has 21 spatial modes within a 125 mu m cladding, and a relative core density of 21, which is the highest of any reported 125 mu m cladding SDM fiber.

关键词： Differential mode delay multi-core fiber multiple-input multiple-output super-mode

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A Scalable Framework for CSI Feedback in FDD Massive MIMO via DL Path Aligning

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2017年第18期65卷 4702-4716页

作者： Luo, Xiliang Cai, Penghao Zhang, Xiaoyu Hu, Die Shen, Cong ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Fudan Univ Sch Informat Sci & Technol Shanghai 200433 Peoples R China Univ Sci & Technol China Hefei 230022 Peoples R China

Unlike the time-division duplexing systems, the down-link (DL) and uplink (UL) channels are not reciprocal in the case of frequency-division duplexing (FDD). However, some long-term parameters, e.g., the time delays and angles of arrival of the channel paths, enjoy reciprocity. In this paper, by efficiently exploiting the aforementioned limited reciprocity, we address the DL channel state information (CSI) feedback in a practical wideband massive multiple-input multiple-output system operating in the FDD mode. With orthogonal frequency-division multiplexing waveform and assuming frequency-selective fading channels, we propose a scalable framework for the DL pilots design, DL CSI acquisition, and the corresponding CSI feedback in the UL. In particular, the base station (BS) can transmit the FFT-based pilots with carefully selected phase shifts. Then, the user can rely on the so-called time-domain aggregate channel to derive the feedback of reduced dimensionality according to either its own knowledge about the statistics of the DL channels or the instruction from the serving BS. We demonstrate that each user can just feed back one scalar number per DL channel path for the BS to recover the DL CSIs. Comprehensive numerical results further corroborate our designs.

关键词： multiple-input multiple-output MIMO massive MIMO frequency-division duplexing FDD time-division duplexing TDD channel state information CSI feedback TDD reciprocity aligning pilots

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A NOVEL CIRCULARLY POLARIZED MODIFIED SLOT MIMO ANTENNA FOR WLAN APPLICATIONS

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2017年第4期59卷 876-880页

作者： Ghahremani, M. Ghobadi, Ch Nourinia, J. Karamirad, M. Mohammadi, B. Urmia Univ Dept Elect Engn Orumiyeh Iran

The design of a novel circularly polarized (CP) modified slot multiple-input multiple-output (MIMO) antenna for WLAN applications with a small size of 20 x 20 mm(2) is suggested. The MIMO antenna configuration consists of two stepped open-circuit feed-lines to enhance the input matching condition, a square ground plane with circularly etching and two arc-shape slotted stubs along the two opposite edges to produce the CP functionality. To accredit the simulation results, the prototypes of the suggested CP modified slot MIMO antenna are constructed on an inexpensive FR-4 substrate and tested. The outcomes exhibit a 6% (330 MHz, 5.10-5.43 GHz) 3dB axial-ratio bandwidth, and the measured 10-dB impedance bandwidth is 62.9% (4720 MHz, 4,92-9.64 GHz). Antenna feed-lines are Microstrip-Microstrip to gain a high isolation and low envelope correlation between the two input ports. Fine efficiency of the propounded antenna over the working bands are also received. The outcomes demonstrate, which the antenna can be evaluated as a suitable choice for CP MIMO systems. (C) 2017 Wiley Periodicals, Inc.

关键词： circularly polarized multiple-input multiple-output slot antenna WLAN

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Non-Linear and Non-Iterative Based Transceiver Design for SU-MIMO Systems

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Journal of Communications and Information Networks 2018年第2期3卷 84-92页

作者： Raja Muthalagu Department of EEE Birla Institute of Technology and Science(BITS)PilaniDubai CampusDubai International Academic CityDubai 345055UAE

This paper considers the design of a low-complexity and high-performance precoder for multiple-input multiple-output(MIMO)*** precoder is designed by combining both nonlinear and non-iterative processing *** proposed nonlin-ear precoding techniques employ a nonlinear constellation precoding technique based on maximum distance sepa-rable codes at the *** propose to reduce the computational complexity in iterative-based precoding algorithms by using less complex non-iterative singular value decomposition-based joint precoder and decoder pair *** maximum likelihood detection for the lin-ear MIMO channel is *** simulation results showed that the proposed nonlinear and non-iterative precoding schemes outperform the conventional linear MIMO precoder design,even when a reduced-complexity suboptimal strategy is adopted,considering the bit error rate performance.

关键词： multiple-input multiple-output singular value decomposition maximum distance separable codes subcarrier grouping diversity channel selection

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An Efficient Relay Selection and Power Allocation Schemes for Cognitive MIMO DF Relay Networks with Buffers

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2017年第7期42卷 2839-2849页

作者： Al-Eryani, Yasser F. Salhab, Anas M. Zummo, Salam A. King Fahd Univ Petr & Minerals Dept Elect Engn Dhahran 31261 Saudi Arabia

In this paper, decode-and-forward buffer-aided opportunistic relay selection and antenna transmission power allocation for underlay cognitive radio are considered. All the transmitting and receiving nodes are assumed to be equipped with multiple antennas resulting in a multiple-input multiple-output (MIMO) system. First, a low-complexity MIMO-based relay selection scheme that maximizes the single-hop normalized sum rate of the primary network (PN) and secondary network (SN) is proposed. Second, a sub-optimal antenna transmission power allocation scheme that maximizes the normalized sum rate of the PN and SN is proposed. For power optimization, first, optimal expressions for antenna transmission power of both the PN and SN nodes are derived separately. The derived expressions are then used in an iterative algorithm to produce a near-optimum solution that maximizes the normalized sum rate per time slot. Simulation results are provided to evaluate the performance of the proposed MIMO-based relay selection and antenna transmission power allocation schemes and compare their performance with that of the optimal scenario. The findings show that the proposed relay selection and antenna transmission power allocation schemes introduce a satisfactory performance with much lower complexity compared to the optimal schemes. Additionally, results show that using a buffer-aided relaying significantly enhances the SN performance while slightly deteriorates the performance of the PN.

关键词： Cognitive radio Decode-and-forward Buffer-aided multiple-input multiple-output Convex optimization Iterative algorithm

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Beamforming for Dual-Hop MIMO AF Relay Networks With Channel Estimation Error and Feedback Delay

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IEEE ACCESS 2017年 5卷 21840-21851页

作者： Li, Min Bai, Lin Yu, Quan Choi, Jinho Inst China Elect Syst Engn Corp Beijing 100141 Peoples R China Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Beihang Univ Beijing Lab Gen Aviat Technol Beijing 100191 Peoples R China Gwangju Inst Sci & Technol Sch Elect Engn & Comp Sci Gwangju South Korea

This paper concerns the beamforming (BF) design for a dual-hop multiple-input multiple output (MIMO) amplify-and-forward (AF) relay network. Both a general antenna configuration and imperfect channel state information are taking into consideration, where multiple antennas are deployed at the source, relay, and destination, channel impairments exist at the source-relay and relay-destination hops. The BF scheme is optimized to maximize the received signal-to-noise ratio (SNR). In order to evaluate the performance of the relay network, asymptotic average symbol error rate (ASER) at high SNR is derived. Computer simulations are conducted to show the superiority of the designed BF scheme and the impacts of channel impairments and antenna configurations on the performance of the MIMO AF relay systems. It is shown that the diversity order of the relay network can be reduced to one due to the channel impairments.

关键词： multiple-input multiple-output beamforming amplify-and-forward channel state information average symbol error rate

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Generalized OSTBC-based subcarrier intensity-modulated MIMO optical wireless communication system

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2017年第6期30卷 1-9页

作者： Sharma, Nikhil Bansal, Ankur Garg, Parul Netaji Subhas Inst Technol Div Elect & Commun Engn New Delhi India

In this paper, we analyze an optical wireless communication (OWC) system having a source and a destination node, equipped with multiple transmit and receive apertures, respectively. We utilize generalized orthogonal space-time block codes (OSTBCs) of any arbitrary order and subcarrier intensity modulation scheme for data transmission over gamma-gamma (GG) fading optical links using M-ary phase-shift keying (PSK) constellation. A symbol-wise decoding is utilized, and the closed-form expression of the approximate average symbol error rate (SER) of multi-aperture-based OWC system is obtained for the generalized OSTBC and an arbitrary M-PSK constellation. Using the derived SER expression, we analytically evaluate the diversity order and the coding gain of the OWC system with GG atmospheric turbulence. It has been shown by the numerical results that the maximum possible diversity is achieved by using the symbol-wise maximum likelihood decoding in the destination. Copyright (C) 2016 John Wiley & Sons, Ltd.

关键词： orthogonal space-time block codes optical wireless communication subcarrier intensity modulation multiple-input multiple-output

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Effective capacity of MIMO free-space optical systems over gamma-gamma turbulence channels

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OPTICS COMMUNICATIONS 2017年第0期382卷 450-454页

作者： Chen, Li Wang, Weidong Univ Sci & Technol China Chinese Acad Sci Opt Wireless Commun Key Lab Hefei 230027 Anhui Peoples R China

In this paper, we provide the capacity limits of multiple-input multiple-output (MIMO) free-space optical communication (FSO) system in the presence of quality of service (QoS) requirements. Closed-form expression for the effective capacity of MIMO FSO system with equal gain combining (EGC) is derived. In order to provide insights into the impact of various system parameters, asymptotic expressions are further analyzed in the high signal-to-noise ratio (SNR) regime. Special cases are provided according to the derived results at the same time. Numerical results are given to validate all the analytical results, and the influences of QoS requirements and MIMO configurations are also illustrated. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Free-space optical communication multiple-input multiple-output Effective capacity

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Non-Coherent MIMO of Per Transmit Antenna Differential Mapping (PADM) Employing Asymmetric Space-Time Mapping and Channel Prediction

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IEICE TRANSACTIONS ON COMMUNICATIONS 2017年第5期E100B卷 808-817页

作者： Kubo, Hiroshi Yamagishi, Takuma Mori, Toshiki Ritsumeikan Univ Fac Sci & Engn Kusatsu 5258577 Japan

This paper proposes performance improvement schemes for non-coherent multiple-input multiple-output (MIMO) communication systems employing per transmit antenna differential mapping (PADM). PADM is one form of differential space-time coding (DSTC), which generates an independent differentially encoded sequence for each of the multiple transmit antennas by means of space-time coding and mapping. The features of the proposed schemes are as follows: 1) it employs an asymmetric space-time mapping instead of the conventional symmetric space-time mapping in order to lower the required signal to noise power ratio (SNR) for maintaining the bit error rate (BER) performance;2) it employs an analytically derived branch metric criterion based on channel prediction for per-survivor processing (PSP) in order to track fast time-varying channels. Finally, computer simulation results confirm that the proposed schemes improve the required SNR by around 1 dB and can track at the maximum Doppler frequency normalized by symbol rate of 5%.

关键词： multiple-input multiple-output transmit diversity spatial multiplexing differential space-time signal processing maximum-likelihood detection Viterbi detection

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Channel Estimation for Frequency Division Duplexing Multi-user Massive MIMO Systems via Tensor Compressive Sensing

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DEFENCE SCIENCE JOURNAL 2017年第6期67卷 668-673页

作者： Wang, Qingzhu Wei, Mengying Zhu, Yihai Northeast Elect Power Univ Sch Informat Engn Jilin Jilin Peoples R China CRRC Changchun Railway Vehicles Co Ltd Engn Technol Ctr Changchun Jilin Peoples R China

To make full use of space multiplexing gains for the multi-user massive multiple-input multiple-output, accurate channel state information at the transmitter (CSIT) is required. However, the large number of users and antennas make CSIT a higher-order data representation. Tensor-based compressive sensing (TCS) is a promising method that is suitable for high-dimensional data processing;it can reduce training pilot and feedback overhead during channel estimation. In this paper, we consider the channel estimation in frequency division duplexing (FDD) multi-user massive MIMO system. A novel estimation framework for three dimensional CSIT is presented, in which the modes include the number of transmitting antennas, receiving antennas, and users. The TCS technique is employed to complete the reconstruction of three dimensional CSIT. The simulation results are given to demonstrate that the proposed estimation approach outperforms existing algorithms.

关键词： Compressive sensing Tensor decomposition Channel estimation Massive MIMO multiple-input multiple-output

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