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Achievable rate region for the multiple-access channel with multiple cognitive transmitters

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The Journal of China Universities of Posts and Telecommunications 2013年第3期20卷 20-25,24-25页

作者： GUO Yu-chen niu kai xu wen-jun he zhi-qiang lin jia-ru Key Lab of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications

A scenario where one ＇dumb＇ radio and multiple cognitive radios communicating simultaneously with a common receiver is considered. In this paper, we derive an achievable rate region of the multiple-user cognitive multiple-access channel （MUCMAC） under both additive white Gaussian noise （AWGN） channel and rayleigh fading channel, by using a combination of multiple user dirty paper coding （DPC） and superposition coding. Through cognition, it is assumed that the secondary users （SUs） are able to obtain the message of the primary user （PU） non-causally beforehand. Using this side information, the SUs can perform multiple user DPC to avoid the interference from the SU. Besides, the SUs can also allocate part of their transmit power to aid the PU, using superposition coding. Therefore, the capacity region of traditional multiple-access channel （MAC） can be enlarged. Moreover, some asymptotic results are shown as the number of SUs increases. In the AWGN case, it is illustrated that the maximum achievable rate of the PU grows logarithmically with the increase of the number of SUs, whereas in the Rayleigh case, we show that the cognitive gain will increase with the decreasing of the channel signal to noise ratio （SNR）.

关键词： cognitive radios MAC superposition coding DPC

Multicast resource allocation with min-rate requirements in OFDM systems

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The Journal of China Universities of Posts and Telecommunications 2010年第3期17卷 24-30,51页

作者： xu wen-jun he zhi-qiang niu kai lin jia-ru WU Wei-ling School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article addresses the multicast resource allocation problem with min-rate requirement constraints in orthogonal frequency division multiplexing （OFDM） systems. Due to the prohibitively high complexity for nonlinear and combinatorial optimization, the original problem is relaxed and reformulated to form a standard optimization problem. By theoretical derivation according to the Karush-Kuhn-Tucker （KKT） conditions, two propositions are presented as the necessary criteria for optimality. Furthermore, a two-step resource allocation scheme, including subcarrier assignment and power allocation, is proposed on a basis of the propositions for practical implementation. With the rain-rate based multicast group order, subcarriers are assigned in a greedy fashion to maximize the capacity. When subcarrier assignment is determined, the proposed power allocation can achieve the optimal performance for the rain-rate constrained capacity maximization with an acceptable complexity. Simulation results indicate that the proposed scheme approximates to optimal resource allocation obtained by exhaustive search with a negligible capacity gap, and considerably outperforms equal power distribution. Meanwhile, multicast is remarkably beneficial to resource utilization in OFDM systems.

关键词： OFDM multicast resource allocation min-rate requirements

多中继协作ARQ在Nakagami-m信道中的性能分析

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北京邮电大学学报 2010年第2期33卷 74-77,87页

作者：徐文波林家儒牛凯贺志强泛网无线通信教育部重点实验室(北京邮电大学) 北京100876

为分析采用等增益合并的协作自动重传请求(CARQ)网络在Nakagami-m信道中的性能,利用一种新的近似方案推导出其在高信噪比时的误帧率表达式,其结果适用于任意中继数的情况.仿真结果表明,与传统的自动请求重传(ARQ)网络相比,CARQ可以获得... 详细信息

为分析采用等增益合并的协作自动重传请求(CARQ)网络在Nakagami-m信道中的性能,利用一种新的近似方案推导出其在高信噪比时的误帧率表达式,其结果适用于任意中继数的情况.仿真结果表明,与传统的自动请求重传(ARQ)网络相比,CARQ可以获得更好的性能.

关键词：协作自动重传请求等增益合并中继

Weibull衰落信道下多跳通信系统的性能分析

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北京邮电大学学报 2009年第4期32卷 25-29页

作者：吴联海贺志强牛凯徐文波林家儒北京邮电大学信息与通信工程学院北京100876

分析了在独立不同分布Weibull衰落信道下配有非再生中继的多跳无线通信系统性能.基于调和几何平均不等式,得到了更易于数学处理的端到端信噪比上界.通过计算上界的矩母函数、概率密度函数和矩等闭式表达式,得到了多跳通信系统的平均端... 详细信息

分析了在独立不同分布Weibull衰落信道下配有非再生中继的多跳无线通信系统性能.基于调和几何平均不等式,得到了更易于数学处理的端到端信噪比上界.通过计算上界的矩母函数、概率密度函数和矩等闭式表达式,得到了多跳通信系统的平均端到端信噪比、信道容量和平均误比特率等重要性能界.数值仿真结果表明该界是紧的.

关键词：衰落信道非再生中继信道容量平均误比特率

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高能效功率控制博弈中的斯塔克尔伯格均衡

北京邮电大学学报 2011年第4期34卷 75-79页

作者：王雷许文俊牛凯贺志强林家儒北京邮电大学泛网无线通信教育部重点实验室北京100876

提出了一种针对高能效功率控制博弈框架的新观点.在假设存在更智慧用户的前提下,引入了斯塔克尔伯格均衡(SE)表示博弈结果,证明了SE比纳什均衡(NE)效率更高,并且不需要增加网络的协助.所提观点和方案可视为认知用户根据认知信息改善系... 详细信息

提出了一种针对高能效功率控制博弈框架的新观点.在假设存在更智慧用户的前提下,引入了斯塔克尔伯格均衡(SE)表示博弈结果,证明了SE比纳什均衡(NE)效率更高,并且不需要增加网络的协助.所提观点和方案可视为认知用户根据认知信息改善系统总体性能的实例.仿真结果表明,SE比NE具有更高的效率.与NE相比,在SE时所有用户的效用有了显著增加,发射功率也有了明显下降.

关键词：高效能功率控制纳什均衡斯塔克尔伯格均衡认知无线网络

OFDM系统中考虑信源编码特性的多播资源分配方案

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通信学报 2010年第8期31卷 66-74页

作者：许文俊贺志强牛凯林家儒吴伟陵北京邮电大学信息与通信工程学院北京100876

针对OFDM系统单播以及传统多播没有充分发挥无线传播开放性优势的问题,提出了多个多播组保证组间比例公平的资源分配方案。该方案由子载波分配算法及功率分配算法构成,前者通过修正存在的单播子载波分配算法得到;后者基于理论推导的非... 详细信息

针对OFDM系统单播以及传统多播没有充分发挥无线传播开放性优势的问题,提出了多个多播组保证组间比例公平的资源分配方案。该方案由子载波分配算法及功率分配算法构成,前者通过修正存在的单播子载波分配算法得到;后者基于理论推导的非线性方程组,得到了子载波分配给定条件下的最优功率分配。仿真结果显示,所提方案能够确保完美的多播组间公平性,且和速率容量性能明显优于传统多播方式。结合方案的低复杂度特性,它适合在实际无线系统的音/视频多播中进行应用。

关键词： OFDM 多播资源分配最优功率分配

Growth of high material quality InAs/GaSb type-Ⅱ superlattice for long-wavelength infrared range by molecular beam epitaxy

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Chinese Physics B 2022年第9期31卷 624-627页

作者： Fang-Qi lin Nong Li wen-Guang Zhou Jun-kai jiang Fa-Ran Chang Yong Li Su-Ning Cui Wei-qiang Chen Dong-Wei jiang Hong-Yue Hao Guo-Wei Wang Ying-qiang xu zhi-Chuan niu State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

By optimizing theⅤ/Ⅲbeam-equivalent pressure ratio,a high-quality InAs/GaSb type-Ⅱsuperlattice material for the long-wavelength infrared(LWIR)range is achieved by molecular beam epitaxy(MBE).High-resolution x-ray diffraction(HRXRD),atomic force microscopy(AFM),and Fourier transform infrared(FTIR)spectrometer are used to characterize the material growth *** results show that the full width at half maximum(FWHM)of the superlattice zero-order diffraction peak,the mismatching of the superlattice zero-order diffraction peak between the substrate diffraction peaks,and the surface roughness get the best results when the beam-equivalent pressure(BEP)ratio reaches the optimal value,which are 28 arcsec,13 arcsec,and 1.63?,*** intensity of the zero-order diffraction peak is strongest at the optimal *** relative spectral response of the LWIR detector shows that it exhibits a 100%cut-off wavelength of 12.6μm at 77 ***-quality epitaxial materials have laid a good foundation for preparing high-performance LWIR detector.

关键词： type-Ⅱsuperlattice InAs/GaSb long-wavelength strain-balanced

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多播OFDM系统中比例公平资源分配

北京邮电大学学报 2009年第6期32卷 109-113页

作者：许文俊牛凯贺志强林家儒吴伟陵北京邮电大学信息与通信工程学院北京100876

提出了一种多播正交频分复用(OFDM)系统中的比例公平资源分配算法,该算法包括:子载波分配算法和功率分配算法.前者通过修正已有的单播子载波分配算法而得到,后者采用双重二分法迭代分配功率,属于子载波分配给定条件下的最优多播功率分配... 详细信息

提出了一种多播正交频分复用(OFDM)系统中的比例公平资源分配算法,该算法包括:子载波分配算法和功率分配算法.前者通过修正已有的单播子载波分配算法而得到,后者采用双重二分法迭代分配功率,属于子载波分配给定条件下的最优多播功率分配.仿真结果表明,提出的资源分配算法在保证容量性能的同时能够获得完美的公平性;即使在比例公平的约束下多播仍然比单播获得明显的容量增加,但容量增益的多少与速率比例以及多播组数目直接相关.

关键词：正交频分复用多播资源分配比例公平

In-beam gamma rays of CSNS Back-n characterized by black resonance filter

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Nuclear Science and Techniques 2024年第10期35卷 149-160页

作者： Jin-Cheng Wang Jie Ren Wei jiang Xi-Chao ruan Ying-Yi Liu Hao-Lan Yang Kuo-zhi xu Xin-Yi Pan Qi Sun Jie Bao Han-Xiong Huang Hao-Fan Bai jiang-bo Bai Ping Cao Qi-Ping Chen Yong-Hao Chen wen-Hao Duan An-Chuan Fan rui-rui Fan Chang-Qing Feng Min-Hao Gu Chang-Cai Han Zi-Jie Han Guo-Zhu he Yong-Cheng he Yang Hong Yi-Wei Hu zhi-Jie jiang ling Kang Chang-lin Lan bo Li Feng Li qiang Li Xiao Li Yang Li Jie Liu Rong Liu Shu-Bin Liu Yi-Na Liu Guang-Yuan Luan Chang-Jun Ning Yi-jia Qiu wen-kai Ren zhi-Zhou Ren Zhao-Hui Song Kang Sun zhi-Xin Tan Jing-Yu Tang Sheng-Da Tang Li-jiao Wang Peng-Cheng Wang Zhao-Hui Wang Zhong-Wei wen Xiao-Guang Wu xuan Wu Ze-Peng Wu Cong Xia Li-Kun Xie Han Yi Tao Yu Yong-Ji Yu Guo-Hui Zhang Hang-Chang Zhang Qi-Wei Zhang Xian-Peng Zhang Yu-Liang Zhang zhi-Yong Zhang Mao-Yuan Zhao zhi-Hao Zhou Ke-Jun Zhu Chong Zou Key Laboratory of Nuclear Data China Institute of Atomic EnergyBeijing 102413China Institute of High Energy Physics Chinese Academy of Sciences(CAS)Beijing 100049China Spallation Neutron Source Science Center Dongguan 523803China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Institute of Modern Physics Fudan UniversityShanghai 200433China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China USTC Archaeometry Lab University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Particle Detection and Electronics Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Northwest Institute of Nuclear Technology Xi’an 710024China University of Chinese Academy of Sciences Beijing 100049China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Institute of Advanced Technology University of Science and Technology of ChinaHefei 230027China

The back-streaming white-neutron beamline(Back-n)of the China Spallation Neutron Source is an essential neutronresearch platform built for the study of nuclear data,neutron physics,and neutron *** types of cross-sectional neutron-reaction measurements have been performed at Back-n since early *** measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron *** gamma rays,commonly referred to as in-beam gamma rays,can induce a non-negligible experimental background in neutron-reaction *** the characteristics of in-beam gamma rays is important for understanding the experimental ***,measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons;thus,discriminating between neutron-induced signals and those from in-beam gamma rays is *** this study,we propose the use of the black resonance filter method and a CeBr_(3) scintillation detector to measure the characteristics of the in-beam gamma rays of *** types of black resonance filters,^(181)Ta,^(59)Co,^(nat)Ag,and^(nat)Cd,were used in this *** time-of-flight(TOF)technique was used to select the detector signals remaining in the absorption region of the TOF spectra,which were mainly induced by in-beam gamma *** energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr_(3) scintillation detector and using Monte Carlo *** on the results of this study,the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated,which is beneficial for enhancing both the experimental methodology and data analysis.

关键词： In-beam gamma rays Back-n CeBr_(3)scintillator Black filter resonance technique