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Effective capacity region of two-user opportunistic spectrum access

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Science china(Information Sciences) 2011年第9期54卷 1928-1937页

作者： XU YuHua,WANG JinLong & WU QiHui institute of communications engineering,PLA University of Science and Technology,nanjing 210007,china institute of communications engineering PLA University of Science and Technology Nanjing China

The effective capacity region of the two-user opportunistic spectrum access (OSA) system in Rayleigh fading environment is derived in this paper.Although OSA is a contemporary research topic,little attention has been given to the capacity analysis under quality-of-service (QoS) constraints.Hence,we use the effective capacity,which is a powerful tool to analyze the QoS requirements in wireless communication systems,to study the sustainable packet arrival rate of the secondary users while meeting statistical QoS constraints.We derive the effective capacity region of the two-user OSA system and propose a method to obtain the capacity region boundary.In addition,by combining the finite state channel model and the activity of the primary user,an extended finite state channel model for the two-user OSA system is also proposed.

关键词： cognitive radio opportunistic spectrum access effective capacity

Joint subcarrier and power allocation in uplink OFDMA systems based on stochastic game

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Science china(Information Sciences) 2010年第12期53卷 2557-2566页

作者： WU Dan 1,CAI YueMing 1,2 & SHENG YanMing 1 1 institute of communications engineering,PLA University of Science and Technology,nanjing 210007,china 2 National Mobile communications Research Laboratory,Southeast University,nanjing 210096,china institute of communications engineering PLA University of Science and Technology Nanjing China National Mobile communications Research Laboratory Southeast University Nanjing China

In uplink orthogonal frequency division multiplexing access(OFDMA) systems,efficient resource allocation can greatly improve system performance.Therefore,in this paper,we present a game-theoretical approach to achieve a joint subcarrier and power allocation in a distributed way.Particularly,the subcarrier allocation problem is modeled as a multi-player discrete,stochastic and finite strategy game,where each of the subcarriers is viewed as a player to choose the most satisfying user.The subcarriers of each user are allocated with equal power.For the proposed game model,on the one hand,we exploit the support and programming methods to obtain the Nash equilibriums,and analyze their theoretical properties.On the other hand,we propose a lowcomplexity algorithm based on the linear reward-inaction(L R-I) algorithm to search for the Nash equilibriums.And the relationship between the convergence results of this algorithm and the Nash equilibriums is discussed.Extensive simulation results demonstrate the effectiveness of the resource allocation game model and algorithm.

关键词： stochastic game OFDMA subcarrier allocation power allocation learning automata linear reward-inaction

A novel multicluster V-MIMO PCR scheme in large-scale Ad Hoc networks

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Science china(Information Sciences) 2010年第10期53卷 2097-2105页

作者： ZHOU Yao, CAI YueMing & PAN ChengKang Department of Wireless Communication, institute of communications engineering, PLA University of Science and Technology, nanjing 210007, china Department of Wireless Communication Institute of Communications Engineering PLA University of Science and Technology Nanjing China

A multicluster packet collision resolution (PCR) scheme is a kind of recently proposed virtualMIMO techniques. In existing multicluster PCR schemes, a large-scale wireless Ad Hoc network is divided into clusters and the single cluster PCR scheme is applied independently to resolve collisions in each cluster. However, there are still some flaws in existing multicluster PCR schemes. In this paper, by presenting a concise theoretical analysis model and a new CNS algorithm, a novel multicluster PCR scheme is proposed. Analysis and simulation results show that the proposed scheme can obtain high performance gain with low complexity. The proposed scheme is more robust and applicable than existing schemes.

关键词： packet collision resolution virtual-MIMO cooperative communication cooperative nodes selection

The Generalized Mixed Least Square Methodsfor the Estimation of Weights in AHP

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Systems Science and Systems engineering 1998年第4期8卷 385-392页

作者： XU Zeshui(institute of communications engineering, nanjing,210016, china)

This paper proposes a class of generalized mixed least square methods(GMLSM) forthe estimation of weights in the analytic hierarchy process and studies their good properties such asinvariance under transpose, invariance under change of scale, and also gives a simple convergent iterativealgorithm and some numerical examples. The well-known eigenvector method(EM) is then compared.Theoretical analysis and the numerical results show that the iterative times of the GMLSM are generallyfewer than that of the MLSM, and the GMLSM are preferable to the EM in several important respects.

关键词： the analytic hierarchy process(AHP) the generalized mixed least square methods(GMLSM).judgement matrix

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Microstructure and Properties of Mg-12Gd-3Y-0.5Zr Alloys Processed by ECAP and Extrusion

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Journal of Wuhan University of Technology(Materials Science) 2011年第6期26卷 1128-1132页

作者：朱荣 Department of Materials Science and engineering Nanjing University of Science and Technology

Equal channel angular pressing （ECAP） processing and conventional extrusion （Ex） were applied to the Mg-12Gd-3Y-0.5Zr （wt%） magnesium alloy in order to evaluate the potential improvement in the mechanical properties. The ECAP experiment was conducted at 380 ℃ in a die having an included angle of 90° between two channels by the Bc route with the billet rotated by 90° about its longitudinal axis. Subsequently, some billets were processed by conventional extrusion at 300 ℃. The microstructures were examined by X-ray diffraction （XRD）, optical microscopy and transmission electron microscopy （TEM）. The experimental results indicate that the grain size is refined effectively, but the basal planes are highly inclined （about 40o） from the extrusion axis introduced by ECAP, which impairs the grain boundary strengthening effect. The conventional extrusion, following the ECAP, can modify the grains in hard orientation. Based on grain boundary strengthening due to ECAP and texture strengthening due to Ex, the strength is improved effectively. The enhanced activity of the non-basal slips, due to the refined grains and the reduction in c/a ratio, is responsible for good ductility and high strain hardening rate in samples obtained by the two-step process.

关键词： magnesium alloy equal channel angular pressing thermomechanical processing texture

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Computer Aided Analysis of Nonlinear Distortion for Laser Diode under Intensity Modulation

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Chinese Journal of Lasers 1997年第5期6卷 391-396页

作者： ZHANG Zhengxian (Communicatins engineering institute, nanjing 210016, china)HU Gang (Southeast University, nanjing 210018, china) communications engineering Inst Nanjing China

A large signal equivalent circuit model is set up by using normalized rate equations and the practical method to analyze nonlinear distortion for laser diode applying PSPICE is discussed. Simulated results match well ... 详细信息

关键词： laser diode equivalent circuit model nonlinear distortion

Low-complexity distributed differential spacetime coding scheme for amplify-and-forward cooperative networks

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Science in china(Series F) 2009年第8期52卷 1418-1427页

作者： YU XiangBin1,2, BI GuangGuo3 & XU WeiYe4 1 College of Information Science and Technology, nanjing University of Aeronautics and Astronautics, nanjing 210016, china 2 Department of Electronic engineering, City University of Hong Kong, Hong Kong, china 3 National Mobile communications Research Laboratory, Southeast University, nanjing 210096, china 4 Department of Communication engineering, nanjing institute of Technology, nanjing 211167, china College of Information Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing China Department of Electronic engineering City University of Hong Kong Hong Kong China National Mobile communications Research Laboratory Southeast University Nanjing China Department of Communication engineering Nanjing Institute of Technology Nanjing China

By introducing a space-time coding scheme based on amicable orthogonality, we develop a distributed differential space-time coding scheme with the amplify-and-forward （AF） method for wireless cooperative networks. The scheme requires no knowledge of the channel state information at both transmitters and receivers, and effectively decreases the realization complexity due to no channel estimation. Moreover, it has lower decoding complexity and higher coding advantage than the existing scheme, thus avoiding the shortcoming of exponential decoding complexity of some existing schemes. According to the pairwise error probability （PEP） analysis of the system, the power allocations of source and relay terminals are jointly optimized, and as a result, the PEP is minimized, which will provide a helpful guideline for system design. Numerical calculation and simulation results show that the developed scheme is superior to the existing scheme. Moreover, the scheme with optimal power allocation yields obvious performance improvement over that with equal power allocation.

关键词： differential space-time coding cooperative communication amplify-and-forward method power allocation

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A　40　km　Fiber－optic　Microwave　Subcarrier　Multiplexing　Transmission　System　for　Multi－channel　FM－TV

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Chinese Journal of Lasers 1996年第5期5卷 470-474页

作者： ZHANG Zhengxian LIN Zhiyuan LI Zhitang Xu Jie (communications engineering institute, nanjing 210016, china Southeast Universtiy, nanjing 210018, china Wuhan Research institute of Post and Telecommunications, Wuhan 430074, china) china Southeast Univ Nanjing China

Ａ４０ｋｍＦｉｂｅｒ－ｏｐｔｉｃＭｉｃｒｏｗａｖｅＳｕｂｃａｒｒｉｅｒＭｕｌｔｉｐｌｅｘｉｎｇＴｒａｎｓｍｉｓｓｉｏｎＳｙｓｔｅｍｆｏｒＭｕｌｔｉ－ｃｈａｎｎｅｌＦＭ－ＴＶＺＨＡＮＧＺｈｅｎｇｘｉａｎ；ＬＩＮＺｈｉｙ... 详细信息

Ａ４０ｋｍＦｉｂｅｒ－ｏｐｔｉｃＭｉｃｒｏｗａｖｅＳｕｂｃａｒｒｉｅｒＭｕｌｔｉｐｌｅｘｉｎｇＴｒａｎｓｍｉｓｓｉｏｎＳｙｓｔｅｍｆｏｒＭｕｌｔｉ－ｃｈａｎｎｅｌＦＭ－ＴＶＺＨＡＮＧＺｈｅｎｇｘｉａｎ；ＬＩＮＺｈｉｙｕａｎ；ＬＩＺｈｉｔａｎｇ；ＸｕＪ...

关键词： fiber communication microwave subcarrier multiplexing multi-channel FMTV

Performance of iteratively decoded bit-interleaved coded modulation with chaos based interleaving strategies

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Science china(Information Sciences) 2010年第4期53卷 833-841页

作者： ZOU XueLan1*, LIU WeiYan2 & FENG GuangZeng3 1Department of Electronic and Information engineering, Zhejiang institute of Media and communications, Hangzhou 310018, china 2Department of Information engineering, Jiangsu City Vocation College, nanjing 210036, china 3College of Communication and Information engineering, nanjing University of Posts and Telecommunications, nanjing 210003, china Department of Electronic and Information engineering Zhejiang Institute of Media and Communications Hangzhou China Department of Information engineering Jiangsu City Vocation College Nanjing China College of Communication and Information engineering Nanjing University of Posts and Telecommunications Nanjing China

Bit-interleaved coded modulation with iterative decoding (BICM-ID) is a bandwidth efficient trans- mission scheme which is well suitable for next-generation mobile communications. The interleaver design is critical to the high performance of BICM-ID. In this paper we investigate the application of the chaos theory to the interleaver design to further improve the performance of BICM-ID. A new interleaving scheme based on the chaos theory is proposed. Compared with the random interleaver, the proposed approach has the ad- vantages including lower system delay and higher transmission efficiency. Simulation results in both additive white Gaussian noise (AWGN) channel and Rayleigh fading channel are provided, which demonstrates that the new interleaver is better than the random interleaver and exhibits excellent performance when applied to the BICM-ID system.

关键词： chaos interleaving bit-interleaved coded modulation (BICM) iterative decoding