自适应多天线OFDMA蜂窝系统中反馈压缩新方法

在自适应调制和调度的无线通信系统,特别是OFDMA系统中,反馈信息压缩技术已成为研究热点。文中研究了随机波束成形OFDMA系统中分簇反馈压缩技术以及门限信噪比压缩技术,结合二者的优点提出了一种改进方案——分簇门限信噪比压缩技术。仿真证明,采用分簇门限信噪比技术与分簇技术、门限信噪比技术相比,明显降低了反馈量,且在用户较多时系统容量损失很少。     

无线通信中空分复用技术的研究现状

空分复用技术可以极大地提高频谱利用率,已经成为国内外无线通信领域的研究热点,文章讨论了空分复用技术的系统构成,对比了当前空分复用系统各模块关键技术的优缺点,总结了大规模MIMO技术以及广义空间索引调制技术的优势,分析了空分复用技术下一步发展趋势。     

SG-ITOM中基于场景自动化的工具中心系统设计

本文详细阐述了SG-ITOM中的核心模块工具中心的系统设计,明确了系统目标,然后给出了系统功能设计和分功能描述。最后设计了系统分层次的技术架构,并逐层阐述其中的技术实现方案。本文可为研发企业在往后的系统具体实现过程中提供思路和依据。     

《广播电视技术手册》新出两个分册──8分册《节目信号传输》和12分册《工程设计技术》

《广播电视技术手册》新出两个分册──８分册《节目信号传输》和１２分册《工程设计技术》《广播电视技术手册》共１４个分册，现在已经出版了９个。大家已到手的７个是：第１分册《系统与覆盖网》，第２分册《广播中心技术系统》，第３分册《广播节目制作》，第７分册《...     

SDMA系统DL方案阻塞率的仿真

多址接入技术是无线通信系统设计的一个重要因素,未来无线通信系统将广泛采用空分多址（SDMA）接入技术来提高系统容量。比如在频分复用（FDMA）,时分复用（TDMA）,码分复用（CDMA）。介绍了Erlang-B分布这一典型的业务分配模型,并考虑了SDMA系统中DL信道分配机制,给出了理论推导,并采用一般的排队论模型对数字蜂窝移动通信系统中SDMA技术进行仿真。仿真结果表明：采用DL信道分配机制以后,用户可以在同一时间共享同一信道。     

第四代移动通信系统的调制技术

现有通信系统的调制技术限制了信号速率的进一步提高,即将推出的第四代(4G)移动通信系统需要更优良的调制技术。正交频分复用(OFDM)技术是很受欢迎的高速率无线通信技术,结合OFDM的调制技术将在4G系统中得到广泛应用。文中概要介绍了4G系统的特点及关键技术,然后系统介绍了OFDM多载波原理,最后重点介绍了多载波码分多址(MC-CDMA)和正交频分复用时分多址(OFDM-TDMA)两种多载波调制(MCM)技术。     

滤波多音调制系统频偏分析与仿真

滤波多音调制技术通过采用频谱不重叠的多载波调制技术,有效地克服了传统的多载波调制技术正交频分复用的频偏敏感性问题,同时通过不太复杂的均衡技术消除系统的码间干扰。理论分析与仿真证明,滤波多音调制系统有着比正交频分复用系统更好的抗载波频偏的能力。     

基于XQuery查询的表格数据分页的实现

针对Web应用系统中对表格数据分页显示的需求,简要介绍了利用GridView控件的内置分页技术实现分页的方法,提出并实现了一种利用XQuery查询实现装备保障信息综合管理系统中表格数据的分页显示的方法。     

正交频分复用技术原理及应用

正交频分复用(OFDM)由于它在无线通信中的成功应用,近年来备受关注.本文介绍了正交频分复用技术的基本原理、相关技术、优缺点以及在无线通信系统中的应用.指出了OFDM技术将是宽带无线接入系统和下一代移动通信系统的核心技术.     

基于物联网技术的校园节能控制系统硬件设计

文章设计了一种基于物联网技术的校园节能控制系统,给出了该系统的硬件设计方案。系统利用Zig Bee技术、TCP/IP技术、计算机控制技术,实现了对校园能耗实行分项计量,建立了能耗监测平台,确定了分项计量能耗拆分模型。系统有效解决了当前校园能耗管理基础数据缺失、计量混乱等问题,具有实时性好、功率低、可靠性高等优点。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Towards Mobile Ubiquitous Service Environment

In this article we present a perspective on future vision of mobile communications and services which is referred to as Mobile Ubiquitous Service Environment (MUSE). Based on analysis of wireless communications and services, we exploit a conceptual model for MUSE via a top-down approach. The conceptual model consists of three major elements: Terminal Service Environment (TSE), Network Service Environment (NSE) and User Identity (UID). The concept of Always the Best Experience (ABE) is addressed as the hinge in design and development such that the user-centric services could be provided automatically and intelligently in the future diverse wireless world Based on these, we further discuss the issues on design and implementation of architecture of future wireless communication system. Requirements for architecture brought by the new features of MUSE are listed. Moreover, we also address several tradeoffs that should be taken into consideration in design. Finally, the deployment challenges for MUSE, such as reflectiveness of system, security and privacy, as well as peer-to-peer AAA are predicted.Ji Yang received PhD degree on Circuit and System, Bachelor degree on Telecommunication Engineering from Beijing University of Posts and Telecommunications (BUPT) in 2002 and 1993 respectively. Currently, he is an associate professor of BUPT, chief technical supervisor of Wireless Technology Innovation Institute, and vice manager of MTlab of Sino-Germany Software Institute. He leads the research on service and application in Future Forum in China. He also made much contribution to the China Communication Standardization Association (CCSA), including the vision of future Mobile Ubiquitous Service Environment, architecture of future B3G mobile terminal, etc. His research interests include architecture design for mobile ubiquitous networks, theory of self-organization, etc.Zhang Ping is now the professor of Beijing University of Posts and Telecommunications and director of Wireless Technology Innovation (WTI) Institute, BUPT. He has also served on the senior member of C3G Group, China MOST 863 future mobile communication FuTURE project, vice-chairman of China FuTURE Forum, and member of Vision Committee of World Wireless Research Forum(WWRF), he was vice chair of WWRF in 2005. He is also invited as the consultants for many domestic and oversea communication companies. He is very active on the international research activity on Beyond 3G area. He also participated in several European projects such as E2R and MOCCA. Until now, he has published 6 books, around 400 publications in journals and conferences in the area of telecommunications. His main research interests are theory and applications in wireless communication area. He was awarded by government, city of Beijing and Ministry of Information Industry several times for his great contribution to the industry and research activity in China.Hu Zheng is a PH.D candidate in mobile communications engineering in Wireless Technology Innovation Institute (WTI) at Beijing University of Posts and Telecommunications (BUPT). He received B.S degree from Nanjing University of Posts and Telecommunications in 2002, majoring in computer communications engineering. He currently works on serivce aspects of mobile ubiquitous communication system with focus on design and performance evaluation of interaction protocols and services in self-organized service environment.Wang Xu received the B.Tech. degree in electronic engineering from Beijing Polytechnic University (now named as Beijing University of Technology), Beijing, China, in 2002. Now he is working for his Ph.D. degree in Wireless Technology Innovation (WTI) Institute, Beijing University of Posts and Telecommunications (BUPT). His current interests include wireless communications in personal area, ad hoc networks and peer-to-peer system.Li Yinong received the BS degree major in Telecommunication Engineering in 1993 from Beijing University of Posts and Telecommunications, the MS degree and PhD degree major in Telecommunication and Electronic System in 1995 and 2003 from the Beijing University of Posts and Telecommunications. He is currently a lecture of STE (School of Telecommunication Engineering) of BUPT. His main research interests include service modeling, service composition approach, and intelligent service. In BUPT, he has given several lectures to both graduate and undergraduate students such as Information Theory, Speech Recognition, Pattern Recognition and Artificial Intelligence.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

High Speed Curve Interpolating D/A Converter

This paper presents a design of high speed curve interpolating D/A converter. We improve 8-bit data to 12-bit data, so the data resolution increases 16 times than that of original 8-bit data. The curve interpolator is developed from the linear interpolator. The simulation speed curve interpolator is about 500 MHz. The chip is fabricated by 0.8 m double-metal single poly CMOS technology. The active interpolation size of chip is 1 × 1 mm². The power dissipation is 200 mWatts at 5volt and 500 MHz for simulation result and 80 mWatts at 5 volt and 50 MHz for measurement result. The errors of interpolating result of curve interpolators are about 20 times less than that of original signal.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

Modulation instability of dispersion-shifted fiber couplers

The nonlinear coupled-mode equations are rewritten by even and odd modes. We study modulation instability (MI) of dispersion-shifted fiber couplers when either even or odd mode is launched alone by using zero-dispersion waveleng threlatively long (quasi-cw) pulses. The result shows that there are new types of MI in both the normal-dispersion and the anomalous-dispersion regimes. MI is concerned with forth-order dispersion and has no relation with third-order dispersion.Quasi-cw can be changed into pulses array under certain conditions. We can extract super short pulse from this. Furthermore,the bandwidth of gain spectra widens and its strength accretes as the input power increases.     

Experimental study of interband and intraband crosstalk in WDM networks

The impacts of interband and intraband erosstalk are studied and compared experimentally. Results show that interband crosstalk can be removed with narrow-band filters and has no influence on signal. Intraband crosstalk will result in signal eye diagram close and BER increasing. When the polarization states of signal and crosstalk align, intraband crosstalk seriously decreases signal quality. But when they misalign, it has little influence. Coherent and incoherent crosstalk are studied experimentally. Results show that coherent crosstalk is less harmful to system performance than incoherent crosstalk.