A general analytical approach to multi-branch selection combining over various spatially correlated fading channels

Driven by the potential application to wireless communications, intensive research efforts have been made on the study of various selective combining (SC) schemes in the past decade. Nevertheless, regardless of its practical importance, performance analysis of multi-branch SC over spatially correlated fading channels is not available in literature except for the simplest case of dual diversity. The major difficulty lies in the fact that SC has its root in the theory of order statistics, and yet systematic methodology has been developed mainly for order statistics obtained from an independent population. In this paper, we formulate the problem in a very general framework, whereby a general solution is derived. The application of the new solution to SC with different modulation schemes and operational environments is elaborated. The fading environments to be addressed include correlated Nakagami, Rayleigh, and Rician channels. Numerical examples are also presented to illustrate the use of the theory.     

基于IP多媒体子系统(IMS)的移动业务

IP多媒体子系统的引进，开启了移动网络与因特网业务融合的时代。本文介绍了IMS的特征，分析了其业务体系架构，重点阐述IMS支持的典型业务。     

Metal gate-HfO/sub 2/ MOS structures on GaAs substrate with and without Si interlayer

In this letter, we studied the effects of post-deposition anneal (PDA) time and Si interface control layer (ICL) on the electrical characteristics of the MOS capacitor with high-/spl kappa/ (HfO/sub 2/) material on GaAs. Thin equivalent oxide thickness (EOT<3 nm) with excellent capacitance-voltage (C-V) characteristics has been obtained. The thickness of the Si ICL and PDA time were correlated with C-V characteristics. It was found that high temperature Si ICL deposition and longer PDA time at 600/spl deg/C improved the C-V shape, leakage current, and especially frequency dispersion (<5%).     

Real-Time Quality Evaluation of Wire Bonding Using Input Impedance

Input impedance characterizes the dynamic property of a linear system. A few existing technologies thus exploit input electrical impedance of wire bonders as the signature to monitor ultrasonic wire bonding processes. However, the waveforms of "impedance" in these technologies are evaluated only approximately. To overcome the shortcoming, we propose a method to detect the true waveforms of both the real and imaginary part of the input impedance. In the method, the voltage and current at the input port of a wire bonder are probed and processed to obtain impedance via Hilbert Transform. Because dynamics of a bonding process represented by these waveforms is fully responsible for the resulted bonding quality, a quality evaluation system based on pattern recognition of these waveforms is further proposed. An artificial neural network using back propagation as training scheme learns from a set of training data to correlate a few features of the impedance waveforms with the bonding strength of the corresponding bond identified by shearing tests. Through a set of verification data, the built system is validated to be capable of evaluating bonding quality right after a bonding process. The proposed method is not only in situ and real-time, but also sensorless, which means that the system is easy to be implemented without interfering operation     

经济而有效地从模拟向数字电视过渡

数字电视正在全球迅速发展。数字电视已经成功地应用于卫星直播,有线电视也在向数字化过渡,数字地面电视亦加快了发展步伐。至1999年底,瑞典、英国和西班牙已成为世界上最早采用数字地面电视的国家。现在,美国已有140多家电视台开播数字地面电视。日本于2000年12月1曰在全国范围内开播数字广播,成为世界卜第一个数字化国家。许多其它国家的广播机构也已经或正在准备向数字过渡。整个广播电视业已经进入从模拟向数字的过渡时期,数字电视时代已经到来。     

Extending Anisotropic Perfectly Matched Layer Absorbing Boundary Condition to Biaxial Media

The absorbing boundary condition required for an anisotropic perfectly matched layer for materials that exhibit a uniaxial and biaxial permittivity tensor is investigated. These materials are used in optical and millimeter wave devices and other particular situations such as in the construction of modern aircraft and automobiles. The derivation presented in this paper may be not suitable for all the arbitrary orientations but for many common situations. The effectiveness of the condition is also illustrated with examples by the finite-difference and finite-element method.     

波峰焊机用三相异步感应式电泵的研究

开发出一种用三相异步感应泵波峰发生器的全自动单／双波峰焊机替代机械泵式波峰焊机，无任何转动部件，无磨损，免维护，提高了整机可行性。     

综合业务电信平台在金融行业应用探讨

本文介绍了我国银行金融业利用通信技术与计算机相结合的综合智能电信平台技术的情况，分析了中国金融行业的新增业务市场，探讨了电信与金融行业结合为社会带来的效益。     

A Novel Smith-Purcell FEL

A novel Smith-Purcell FEL with a relativistic electron beam of middle energy and a quasi-optical resonator composed of diffraction grating and three mirror reflector is described in this paper. Coherent radiation with peak power of tens of KW at 3 mm waveband is successfully detected from an experimental facility characterized by beam energy of 400-500 KeV, pulse length of 70 ns, pulse beam current of 0.2 KA, and pulse guide magnetic field of up to 1.2 T.