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Linearly time-varying channel estimation and training power allocation for OFDM/MIMO systems using superimposed training

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Science china(Information Sciences) 2011年第7期54卷 1456-1470页

作者： zhang han 1,dai xianhua 2.& pan daru 1 1 school of physics and telecommunication engineering,south china normal university,guangzhou 510006,china 2 Department of Information Science and Technology,SUN Yat-sen university,guangzhou 510026,china 1. school of physics and telecommunication engineering South China Normal University Guangzhou 510006 China2. Department of Information Science and Technology SUN Yat-sen University Guangzhou 510026 China

We address the problem of estimating the linearly time-varying (LTV) channel of orthogonal frequency division multiplexing (OFDM)/multiple-input multiple-output (MIMO) systems using superimposed training (ST).The LTV channel is modeled by truncated discrete Fourier *** on this model,a two-step approach is adopted to estimate the LTV channel over multiple OFDM *** also present performance analysis of the channel estimation and derive a closed-form expression for the channel estimation *** is shown that the estimation variances,unlike that of the conventional ST-based schemes,approach to a fixed lower-bound as the training length increases,which is directly proportional to information-pilot power *** wireless communication systems with a limited transmission power,we optimize the ST power allocation by maximizing the lower bound of the average channel *** results show that the proposed approach outperforms the frequency-division multiplexed training schemes.

关键词： OFDM/MIMO systems linearly time-varying channel estimation superimposed training training power allocation

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Superimposed training for channel estimation of OFDM modulated amplify-and-forward relay networks

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Science china(Information Sciences) 2013年第10期56卷 55-66页

作者： zhang han pan daru CUI HaiXia GAO FeiFei school of physics and telecommunication engineering South China Normal University Tsinghua National Laboratory for Information Science and Technology National Mobile Communications Research Laboratory Southeast University

This paper is concerned with the problem of channel estimation for amplify-and-forward(AF)cooperative relay networks with orthogonal frequency division multiplexing(OFDM)*** algorithm is based on both the least square(LS)and minimum mean square error(MMSE)technique with a superimposed training ***,both the source and relay superimpose their own training signal onto data stream prior to transmission so as to estimate the separate channel state information of the source to relay link and the relay to destination *** also present the performance analysis and derive the approximated closed-form expressions for the MSE of separate channel estimation of source to relay link and the relay to destination link,respectively,from which we compute the optimal training signal as well as the relay power-amplifcation *** further improve the performance of channel estimation,we adopt a weighted average process to enhance the estimation performance over multiple OFDM blocks,from which we compute the optimal tracking *** results are provided to corroborate the proposed scheme.

关键词： channel estimation amplify-and-forward relay network OFDM superimposed training

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Electrical contacts in monolayer blue phosphorene devices

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Nano Research 2018年第4期11卷 1834-1849页

作者： Jingzhen Li Xiaotian Sun Chengyong Xu Xiuying zhang Yuanyuan pan Meng Ye Zhigang Song Ruge Quhe Yangyang Wang han zhang Ying Guo Jinbo Yang Feng pan Jing Lu State Key Laboratory for Mesoscopic physics and Department of physics Peking University Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China College of Chemistry and Chemical engineering and Henan Key Laboratory of Function-Oriented Porous Materials Luoyang Normal University Luoyang 471934 China school of Science Nanchang Institute of Technology Nanchang 330099 China State Key Laboratory of Information Photonics and Optical Communications and school of Science Beijing University of Posts and Telecommunications Beijing 100876 China Nanophotonics and Optoelectronics Research Center Qian Xuesen Laboratory of Space Technology China Academy of Space Technology Beijing 100094 China school of physics and telecommunication engineering Shaanxi University of Technology Hanzhong 723001 China school of Advanced Materials Peking University Shenzhen Graduate School Shenzhen 518055 China

Semiconducting monolayer （ML） blue phosphorene （BlueP） shares similar stability with ML black phosphorene （BP）, and it has recently been grown on an Au surface. Potential ML BlueP devices often require direct contact with metal to enable the injection of carriers. Using ab initio electronic structure calculations and quantum transport simulations, for the first time, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor （FET） configuration. ML BlueP has undergone metallization owing to strong interaction with five metals. There is a strong Fermi level pinning （FLP） in the ML BlueP FETs due to the metal-induced gap states （MIGS） with a pinning factor of 0.42. ML BlueP forms n-type Schottky contact with Sc, Ag, and Pt electrodes with electron Schottky barrier heights （SBHs） of 0.22, 0.22, and 0.80 eV, respectively, and p-type Schottky contact with Au and Pd electrodes with hole SBHs of 0.61 and 0.79 eV, respectively. The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode, accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides insight into the ML BlueP-metal interfaces, but also helps in the design of ML BlueP devices.

关键词： monolayer blue phosphorene interface property Schottky barrier field-effect transistor density functional theory quantum transport simulation

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