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Analysis and Design of Cyclic Switched-Capacitor DC-DC Converters

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2019年第8期66卷 3227-3237页

作者： Datta, Kishalay Menezes, Vinod Pavan, Shanthi Indian Inst Technol Madras Dept Elect Engn Chennai 600036 Tamil Nadu India Texas Instruments India Ltd Bengaluru 560093 India

We introduce the cyclic switched-capacitor dc-dc converter for single-input multiple-output power delivery. We focus on applications in stacked voltage domain (SVD)-based systems, and show that the cyclic architecture is robust to load current mismatches. We analyze such converters and give intuition for their power losses. We give experimental results from an SVD based power management integrated circuit (PMIC), designed and fabricated in a 130nm CMOS technology. The PMIC is a combination of a 2/3 stage reconfigurable cyclic SC dc-dc converter and a linear regulator. It can drive 3x3mA loads with the input supply voltage varying from 2.35-3.65V.

关键词： DC-DC power converters switched capacitor circuits single-input multiple-output voltage regulators charge recycling voltage stacking power management

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Equalisation of SIMO-OFDM systems with insufficient cyclic prefix in doubly selective channels

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IET COMMUNICATIONS 2009年第12期3卷 1870-1882页

作者： Beheshti, M. Omidi, M. J. Doost-Hoseini, A. M. IUT Dept Elect & Comp Engn ECE Esfahan Iran

Time variations of a doubly selective wireless channel and insufficient cyclic prefix (CP) length of an orthogonal frequency division multiplexing (OFDM) transmission system cause intercarrier interference (ICI) and interblock interference (IBI) as significant limitations. This paper investigates the problem of joint ICI and IBI mitigation in single-input multiple-output OFDM (SIMO-OFDM) systems. It is assumed, unlike most existing literature, that the channel delay spread is larger than the CP, and also the channel varies on each OFDM block. First, doubly selective channel is modelled using basis expansion model (BEM) and a closed-form expression for signal-to-interference-plus-noise ratio (SINR) is derived. Then, a time-domain equaliser is developed, which maximises the SINR for all subcarriers. Moreover, a frequency-domain equalisation approach is proposed which is based on the MSE minimisation per tone. A low-complexity implementation of the pertone equaliser is also derived. An important feature of the proposed equalisers is that no bandwidth expansion or redundancy insertion is required except for the CP. Finally, complexity comparison and simulation results over Rayleigh fading channel are provided to illustrate the effectiveness of the proposed approaches. Since both equalisers are designed in the frequency domain, they provide significant interference cancellation.

关键词： Electromagnetic compatibility and interference ICI signal-to-interference-plus-noise ratio minimisation Optimisation techniques interblock interference insufficient cyclic prefix SIMO-OFDM system Modulation and coding methods single-input multiple-output basis expansion model orthogonal frequency division multiplexing wireless channels doubly selective wireless channel OFDM modulation time-domain analysis time-domain equaliser intercarrier interference Mathematical analysis channel delay spread equalisers IBI time variation frequency-domain analysis bandwidth expansion Radio links and equipment Rayleigh fading channel frequency-domain equalisation approach

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Secrecy Performance Analysis of SIMO Systems Over Correlated κ-μ Shadowed Fading Channels

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IEEE ACCESS 2019年 7卷 86090-86101页

作者： Sun, Jiangfeng Bie, Hongxia Li, Xingwang Zhang, Jiayi Pan, Gaofeng Rabie, Khaled M. Beijing Univ Posts & Telecommun Sch Informat & Commun Engn Beijing 100876 Peoples R China Henan Polytech Univ Sch Phys & Elect Informat Engn Jiaozuo 454000 Peoples R China Beijing Jiaotong Univ Sch Elect & Informat Engn Beijing 100044 Peoples R China Southwest Univ Chongqing Key Lab Nonlinear Circuits & Intelligen Chongqing 400715 Peoples R China Univ Lancaster Sch Comp & Commun Lancaster LA1 4YW England Manchester Metropolitan Univ Sch Elect Engn Manchester M15 6BH Lancs England

In this paper, the secrecy performance of single-input-multiple-output systems over correlated kappa-mu shadowed fading channels is investigated. In particular, based on the classic Wyner's wiretap model, we derive analytical expressions for secure outage probability (SOP) and the probability of strictly positive secrecy capacity (SPSC) over correlated kappa-mu shadowed fading channels. In order to further study the impact of channel parameters on the secrecy performance, novel SOP and the probability of SPSC over independent and identically distributed kappa-mu shadowed fading channels are also obtained. In addition, we discuss the asymptotic expressions of the SOP and the SPSC. The match between the analytical results and simulations is excellent for all parameters under considerations. It is interesting to find that the results show that when the signal-to-noise ratio of the main channel is lower than that of the eavesdropping channel, the larger value of correlation coefficient is helpful to improve the secrecy performance and vice versa.

关键词： single-input multiple-output kappa-mu shadowed fading the probability of strictly positive secrecy capacity (SPSC) secure outage probability (SOP)

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Semi-blind MIMO-OFDM channel estimation using expectation maximisation like techniques

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IET COMMUNICATIONS 2019年第20期13卷 3452-3462页

作者： Ladaycia, Abdelhamid Belouchrani, Adel Abed-Meraim, Karim Mokraoui, Anissa Univ Paris 13 Inst Galilee Sorbonne Paris Cite L2TI Villetaneuse France Ecole Natl Polytech LDCCP lab Elect Engn Dept Algiers Algeria Univ Orleans PRISME Orleans France

This study deals with semi-blind (SB) channel estimation of multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system using maximum likelihood (ML) technique. For the ML cost optimisation function, new expectation maximisation (EM) algorithms for the channel taps estimation are introduced. Different approximation/simplification approaches are proposed for the algorithm's computational cost reduction. The first approach consists of decomposing the MIMO-OFDM system into parallel multiple-input single-output OFDM systems. The EM algorithm is then applied to estimate the MIMO channel in a parallel way. The second approach takes advantage of the SB context to reduce the EM cost from exponential to linear complexity by reducing the size of the search space. Finally, the last proposed approach uses a parallel interference cancellation technique to decompose the MIMO-OFDM system into several single-input multiple-output OFDM systems. The latter are identified in a parallel scheme and with a reduced complexity. The performance of the proposed approaches are discussed, assessed through numerical experiments and compared with respect to the Cramer Rao Bound and to other EM-based solutions reported in the literature.

关键词： OFDM modulation MIMO communication interference suppression channel estimation MISO communication SIMO communication wireless channels radiofrequency interference expectation-maximisation algorithm optimisation approximation theory computational complexity parallel interference cancellation technique single-input multiple-output maximum likelihood technique ML cost optimisation function expectation maximisation algorithms multiple input multiple output orthogonal frequency division multiplexing system semiblind MIMO-OFDM channel taps estimation EM algorithm approximation-simplification approach parallel multiple-input single-output OFDM systems linear complexity single-input multiple-output OFDM system

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BER Analysis for BPSK Based SIM-FSO Communication System Over Strong Atmospheric Turbulence with Spatial Diversity and Pointing Errors

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WIRELESS PERSONAL COMMUNICATIONS 2015年第3期81卷 1143-1157页

作者： Prabu, K. Kumar, D. Sriram Natl Inst Technol Dept Elect & Commun Engn Tiruchirappalli 620015 Tamil Nadu India

Free space optical communication (FSO) has much attention in recent years for the applications viz. inter-satellite, deep space communications, inter and intra chip communications. The performance of FSO systems sternly suffers from atmospheric turbulence due to the random nature of weather conditions. Spatial diversity is an emerging technique for improving the performance of the system over strong atmospheric turbulences. In this paper, the error rate performance of binary phase shift keying based subcarrier intensity modulated free space optical (SIM-FSO) communication system over gamma-gamma channel with pointing errors is investigated. Novel closed-form analytical expressions are derived for the average bit error rate of single-input multiple-output FSO (SIMO-FSO) system with various combining schemes. The error rate performance of SISO and SIMO-FSO systems are compared in terms of 2D and 3D plots.

关键词： Free space optics Pointing errors Strong atmospheric turbulence Bit error rate single-input multiple-output

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Calibration and validation of the dynamic response of two slab track models using data from a full-scale test rig

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ENGINEERING STRUCTURES 2021年 234卷 111980-111980页

作者： Theyssen, Jannik S. Aggestam, Emil Zhu, Shengyang Nielsen, Jens C. O. Pieringer, Astrid Kropp, Wolfgang Zhai, Wanming Chalmers Univ Technol Dept Architecture & Civil Engn Div Appl Acoust S-41296 Gothenburg Sweden Chalmers Univ Technol Dept Mech & Maritime Sci Div Dynam S-41296 Gothenburg Sweden Southwest Jiaotong Univ State Key Lab Tract Power 111Sect 1 North Second Ring Rd Chengdu 610031 Peoples R China

For the development of accurate and reliable simulation models, the procedure of calibration and validation against measurement data is essential. In this paper, a finite element model and a waveguide finite element model of a slab track are calibrated and validated against hammer impact measurement data from a full-scale test rig. The finite element model is three-dimensional, where the rails are modelled as Rayleigh?Timoshenko beams and the concrete slab and support layer are modelled using linear shell elements. In the waveguide finite element model, a constant track cross-section described by two-dimensional finite elements is assumed, and the vibration in the direction perpendicular to the cross-section is described by propagating waves that are decaying exponentially. Measured frequency response functions (FRFs) are compared with the corresponding calculated FRFs from the two modelling approaches. The calibration is conducted in two steps using (i) a parameter study and (ii) a genetic algorithm. For multiple excitation positions and sensor locations, both calibrated models capture the trend of the single-input multiple-output measurements with rather small deviations compared to the overall dynamic range. This implies that both models can successfully represent the dynamic response of the test rig and can be considered as validated.

关键词： Slab Track Track receptance Hammer impact measurements single-input multiple-output Waveguide finite element Finite element Genetic algorithm

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BER analysis of DPSK-SIM over MIMO free space optical links with misalignment

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OPTIK 2014年第18期125卷 5176-5180页

作者： Prabu, K. Kumar, D. Sriram NIT Dept Elect & Commun Engn Tiruchirappalli 620015 Tamil Nadu India

Free-space optics (FSO) is a safe, license-free, high speed and high-bandwidth cordless technique for broadcasting signals at the same speed as fiber optics. But the main drawback of FSO is the dissolution of the signals due to atmospheric turbulence and thus degrading the link performance. So, to enhance the bit error rate (BER) performance, spatial diversity is employed over the FSO links for single-input multiple-output FSO (SIMO-FSO) systems. In this paper, we analyze the BER performance of SIMO-FSO links with spatial diversity and multiple-input multiple-output FSO (MIMO-FSO) systems over gamma-gamma atmospheric turbulence fading channel with misalignment (pointing errors). The closed form expressions are derived for the same with various combining schemes in terms of the Meijer G function and also evaluate the results with 2D and 3D graphs. (C) 2014 Elsevier GmbH. All rights reserved.

关键词： Free space optics Differential phase shift keying subcarrier intensity modulation Strong atmospheric turbulence Pointing errors single-input multiple-output multiple-input multiple-output

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When to Simply Use Passive RIS as Beamformer: An Information-Theoretic Analysis and a Novel single-RF MIMO Transceiver Architecture

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2024年第11期23卷 17157-17173页

作者： Chen, Ru-Han Zhou, Jing Zhu, Yonggang Zhang, Kai Natl Univ Def Technol Res Inst 63 Nanjing 210023 Peoples R China Shaoxing Univ Dept Comp Sci & Engn Shaoxing 312000 Peoples R China

In this paper, for a single-input multiple-output (SIMO) system aided by a passive reconfigurable intelligent surface (RIS), the joint transmission accomplished by the single transmit antenna and the RIS with multiple controllable reflective elements is considered. Relying on a general capacity upper bound derived by using a maximum-trace argument, we respectively characterize the capacity slope of low-signal-to-noise-ratio channels and the exact capacity of rank-one channels, in which the optimal configuration of the RIS is proved to be beamforming-only with carefully-chosen phase shifts. To exploit the potential of modulating extra information on the RIS, by leveraging a strategy named partially beamforming and partially information-carrying based on QR decomposition and successive interference cancellation, we propose a novel transceiver architecture with only a single RF front end at the transmitter, by which the considered channel can be regarded as a concatenation of a vector Gaussian channel and several phase-modulated channels. Especially, we investigate a class of vector Gaussian channels with a hypersphere input support constraint, and not only generalize the existing result to arbitrary-dimensional real spaces but also present its high-order capacity asymptotics, by which both capacities of hypersphere-constrained channels and achievable rates of the proposed transceiver with two different signaling schemes can be well-approximated. Information-theoretic analyses show that the transceiver architecture designed for the SIMO channel has a boosted multiplexing gain, rather than one for the conventionally-used optimized beamforming scheme. Numerical results verify our derived asymptotic results and show notable superiority of the proposed transceiver as compared with the beamforming and the receive spatial modulation schemes.

关键词： Transceivers Wireless communication Vectors Transmitting antennas Radio frequency Array signal processing Receiving antennas Information theory Spatiotemporal phenomena SIMO communication Channel capacity Gaussian noise joint transmission phase-modulated channel reconfigurable intelligent surface single-input multiple-output space-time coding

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Error Rate Analysis of SIMO-CDMA with Complementary Codes Under Multipath Fading Channels

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WIRELESS PERSONAL COMMUNICATIONS 2018年第2期98卷 1663-1677页

作者： Judson, D. Bhaskar, Vidhyacharan St Xaviers Catholic Coll Engn Dept Elect & Commun Engn Nagercoil 629003 Tamil Nadu India San Francisco State Univ Dept Elect & Comp Engn 1600 Holloway Ave San Francisco CA 94132 USA

Broadband communication systems of the current generation are likely to offer higher bit rates for delivering high-speed multimedia services to the end users. The achievable capacity and data rate of wireless communication systems are limited to fading channels varying with time, leading to multiple access interference (MAI) and multipath interference (MPI). In this paper, we investigate downlink single-input multiple output transmission for complementary coded code-division multiple access (CC-CDMA) systems working in channels with multipath fading. Here, parallel interference cancellation is employed for analysis of CC-CDMA with different frequency domain equalization schemes to eliminate MPI and MAI over multipath fading channels. Error rate analysis for CC-CDMA employing receiver diversity is assessed using simulations under varying channel parameters. Further, we compare different equalization schemes to show the superiority of regularized zero forcing in reducing the error rate of CC-CDMA systems.

关键词： single-input multiple-output Parallel interference cancellation Complementary coded code-division multiple access systems Rayleigh fading Rician fading Regularized zero-forcing equalizer

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Secrecy Performance Analysis for SIMO Simultaneous Wireless Information and Power Transfer Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2015年第9期63卷 3423-3433页

作者： Pan, Gaofeng Tang, Chaoqing Li, Tingting Chen, Yunfei Southwest Univ Sch Elect & Informat Engn Chongqing 400715 Peoples R China Southwest Univ Sch Math & Stat Chongqing 400715 Peoples R China Univ Warwick Sch Engn Coventry CV4 7AL W Midlands England

In this paper, a single-input multiple-output (SIMO) simultaneous wireless information and power transfer system consisting of one base station, one desired information receiver and N (N > 1) energy-harvesting receivers is considered. Each link in the considered system suffers not only from small-scale fading but also path-loss. In particular, we focus on the physical layer security performance including secrecy outage and secrecy capacity in the presence of eavesdroppers. We derive the closed-form analytical expression for the exact and the asymptotic secrecy outage probability while considering each eavesdropping link experiences independent but not necessarily identical Rayleigh fading. The closed-form analytical expression for the average secrecy capacity has also been derived for the case that all eavesdropping links experience independent and identical Rayleigh fading. Numerical and Monte Carlo simulation results are presented to verify our derived analytical models.

关键词： Secure communication simultaneous wireless information and power transfer single-input multiple-output secrecy capacity secrecy outage probability

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