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The Performance Comparisons between the Unconstrained and Constrained Equalization Algorithms

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The Journal of China Universities of posts and telecommunications 2003年第4期10卷 50-58页

作者： HE Zhong-qiu,LI Dao-ben(school of Information Engineering, beijing university of posts and telecommunications,{2., P. R. China) school of Information Engineering Beijing University of Posts and Telecommunications 北京 100876

This paper proposes two unconstrained algorithms, the Steepest Decent (SD)algorithm and the Conjugate Gradient (CG) algorithm, based on a superexcellent cost function. At thesame time, two constrained algorithms which include the Constrained Steepest Decent (CSD) algorithmand the Constrained Conjugate Gradient algorithm (CCG) are deduced subject to a new constraincondition. They are both implemented in unitary transform domain. The computational complexities ofthe constrained algorithms are compared to those of the unconstrained algorithms. Resultingsimulations show their performance comparisons.

关键词： transform domain adaptive equalization constrained equalization algorithm

An Efficient Algorithm to Solve the Problem of Dropped Call in CDMA Cellular Systems

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The Journal of China Universities of posts and telecommunications 2000年第1期7卷 99-103页

作者： DENG Wei, AI Bo (College of Computer science and Technology, beijing university of posts and telecommunications,{2., P.R. China ) College of Computer science and Technology Beijing University of Posts and Telecommunications Beijing 100876 P.R. China

In the mobile environment, the dropped calls can be resulted from shadowing and rapid signal loss. As the cells shrink to accommodate an increasingly large demand for services, the dropped-call recovery procedure will become more important over the air interface. But in the current protocols, the recovery procedure is too simple to demonstrate the procedure. In this paper, we present a Transparent Reconnection Procedure (TRP) which is an efficient algorithm that can be adapted easily to the benefit of decreased dropped calls. In the simulation of a typical cellular system, it is shown that there are fewer dropped calls using TRP compared to the conventional procedure. This benefit comes at the expense of a slight increase (less than percent 1) in blocked call percentage. It depends on some relevant system parameters, the values of which are decided by the operators accordingly.

关键词： CDMA reconnection TRP soft handoff drop out

Capacity analysis and optimal power allocation for coordinated transmission in MIMO-OFDM systems

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science China(Information sciences) 2012年第6期55卷 1372-1387页

作者： CUI QiMei 1,HUANG XueQing 1,LUO Bing 1,TAO XiaoFeng 1 & JIANG Jun 2.1 Key Laborary of Universal Wireless Communications,beijing university of {2. and {3.,beijing 100876,China 2.StarPoint Communication Software Company Ltd.,beijing 100102.China 1. Key Laborary of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China2. StarPoint Communication Software Company Ltd. Beijing 100102 China

Coordinated transmission in multicell coordination networks has attracted much attentions in recent *** the paper,we investigate one open problem in the above area,which is concerned with how to solve the closed-form optimal power allocation scheme of coordinated transmission in downlink orthogonal frequency-division multiplexing (OFDM) systems with multiple antenna configurations and individual power constraints.A frequency-selective fading multiple-input multiple-output (MIMO) channel is *** derive the closed-form solutions of sum-rate capacity and optimal power allocations for coordinated transmission under the diversity case and the multiplexing case by solving the constrained optimization *** simulations are performed to verify the derived theoretical conclusions by means of comparing the proposed optimal power allocation (OPA) scheme with the other two typical power allocation *** is the power allocation scheme combining traditional water-filling with equal power (WS-EF PA).The other is equal power allocation (EPA) scheme.

关键词： coordinated multi-point transmission multicell cooperation capacity analysis MIMO-OFDM power allocation frequency selective MIMO channel

基于对角隐式Runge-Kutta公式的无约束优化方法

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系统工程与电子技术 2004年第2期26卷 248-252,267页

作者：罗新龙北京邮电大学信息工程学院北京100876

通过把一个无约束优化问题转化为一个等价的常微分方程,利用二阶半对角隐式Runge Kutta公式构造了求解无约束优化问题的LRKOPT算法。LRKOPT算法具有与IMPBOT方法相似的数值特性,但LRKOPT算法可以看成是最速下降方向与牛顿法方向的非线... 详细信息

通过把一个无约束优化问题转化为一个等价的常微分方程,利用二阶半对角隐式Runge Kutta公式构造了求解无约束优化问题的LRKOPT算法。LRKOPT算法具有与IMPBOT方法相似的数值特性,但LRKOPT算法可以看成是最速下降方向与牛顿法方向的非线性组合,而IMPBOT方法为它们两者之间的线性组合。在目标函数为一致凸函数的假设条件下,证明了LRKOPT方法的具有全局收敛和局部超线性收敛性。数值结果表明LRKOPT方法具有很好的数值稳定性并且LRKOPT方法的计算效率优于IMPBOT方法。

关键词：全局收敛超线性收敛对角隐式Runge-Kutta公式无约束优化 LRKOPT算法

Heterodyne mixing and polarization diversity techniques in radio over fiber system with high sensitivity and dispersion tolerance

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science China(Information sciences) 2011年第2期54卷 236-243页

作者： XU Kun, YIN Jie, NIU Jian, SUN XiaoQiang, WU Jian & LIN JinTong Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, beijing university of posts and telecommunications, beijing 100876, China 1. Key Laboratory of Information Photonics and Optical Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

We propose and experimentally demonstrate the heterodyne mixing and polarization diversity tech- niques in radio over fiber (ROF) systems with the advantages of high sensitivity and dispersion endurance. The generation of 2.5 Gb/s optical DPSK and PSK signals, fiber propagation and wireless transmission over 15 GHz subcarrier are illustrated with very low sensitivity of -2. and -3.0}dBm, respectively. Moreover, based on the wireless polarization diversity techniques, we successfully performed the transmission of 1.3.Gb/s uncompressed high definition television (HDTV) signals with high quality.

关键词： radio over fiber heterodyne mixing polarization diversity

Strain distribution and electronic structures of the InAs/GaAs quantum ring molecule in an applied electric field

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science China(Physics,Mechanics & Astronomy) 2010年第9期53卷 1594-1599页

作者： JIA BoYong,YU ZhongYuan,LIU YuMin,YAO WenJie,YE Han & FENG Hao Key Laboratory of Information Photonics and Optical Communications(beijing university of {2. and {3.),Ministry of Education,beijing 100876,China 1. Ministry of Education Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications) Beijing 100876 China

The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element *** our model,three identical InAs quantum rings are aligned vertically and embedded in the cubic GaAs *** the band edge modification induced by the strain,the electronic ground state and the dependence of ground state energy on geometric parameters of the quantum ring molecule are *** change of localization of the wavefunction resulting from the applied electric field along the growth direction is *** ground state energy decreases as the electric field intensity increases in a parabolic-like *** electric field changes the monotonic dependence of the energy level on the inter-ring distance into a non-monotonic ***,the electric field has no effect on the relationships between the energy level and other geometric parameters such as the inner radius and outer radius.

关键词： strain distribution electronic structure quantum ring molecule applied electric field

RETF: a TCP-Friendly Control Scheme Based on Rate Estimation for Stored Video

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The Journal of China Universities of posts and telecommunications 2003年第4期10卷 5-10页

作者： ZHANG Yu-qing,CAI An-ni,SUN Jing-ao(school of Telecommunication Engineering,beijing {2. of {3. and telecommunications, beijing 100876, P.R. China) school of Telecommunication Engineering Beijing University of Posts and Telecommunications 北京 100876

In this paper, a TCP-friendly rate control algorithm is proposed for storedMPEG2.layered video. In this algorithm, RTT is observed at the receiver through the use of probe APPpackets, and the control interval is chosen based on the self-similar nature of MPEG2.traffic . Inaddition, the estimated receiving rate is used as an indication to the network status when nopacket loss is detected . In our simulations, a friendliness of 0.94 is obtained, and the videoquality fluctuations are acceptable with this control algorithm.

关键词： TCP-friendly rate estimation congestion control

The User-level Security of Mobile Communication Systems

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The Journal of China Universities of posts and telecommunications 2002年第3期9卷 62-69页

作者： DUAN Lian, ZHANG Hao liang, WU Wei ling (Information Engineering school,beijing {2. of {3. and telecommunications,beijing 100876, P.R. China) Information Engineering school Beijing University of Posts and TelecommunicationsBeijing 100876 P.R. China

This paper studies the user-level security of mobile systems . The currentmobile phone users trust the invisible security of the 2. systems. The evolution from thesecond-generation mobile systems (2.) to the third generation systems (3.) will introduce thethreats and opportunities of the Internet to the world of mobile communications. From the technicalpoint of view, the new security requirements are similar to the security requirements met with todayin a company Intranet environment. There is, however, one great difference; the charge paid foraccessing the service. In future the users of mobile systems will have to be more aware of thesecurity issues.

关键词： security mobile communication system user

Environment Factors and Development Policies in Chinese Rural telecommunications

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The Journal of China Universities of posts and telecommunications 2003年第4期10卷 101-106,114页

作者： WU Hong,LIANG Xiong-jian(Institution of Information Management science and Information Economics, beijing university of posts and telecommunications,{2., P.R. China) Institution of Information Management science and Information Economics Beijing University of Posts and Telecommunications 北京 100876

Rural telecom development is one of the focal points now. The favorable and unfavorable factors for rural telecom development will coexist with each other in the following years. There are also differences of development between urban telephone service and rural one. This paper studies all these factors and points out the policies for rural telecom development.

关键词： rural telephone environmental factors critical mass