激光束的相干合成技术

本文可实现激光束相干合成的一些有用的技术作了总结，对由Ｓｃｈｕｓｔｅｒ等人 掾联ＭＯＰＡ系统进行成对共线光束合成的功率定标模型作了分析，最后，对与位相控制概念有关的作了讨论。     

光缆双向数模混合传输系统设计

讨论了利用ＷＤＭ技术、数字复接及解复接技术、信号合成与分离技术、信号调制解调技术、ＰＣＭ编解码技术和光纤发射与接收技术等技术，用一根光纤进行多路模拟和多路数字信号双向传输试验的系统设计和电路设计。最后提供了试验结果。     

Robust JPEG image transmission using unequal error protection and code combining

JPEG image transmission over noisy channels is highly problematic due to the sensitivity of the JPEG bit stream to error propagation. The use of resynchronization markers and channel coding do not alleviate the problem completely thus making retransmissions inevitable. In packetized image transmission, image packets are repeated n times, to ensure reliable transmission. This paper proposes a new unequal error protection (UEP) scheme which jointly optimizes the allocation of channel code rates and number of repeats to image packets, subject to a constraint on the maximum overall transmission rate. The coding scheme used is the rate compatible punctured convolutional code coupled with the code‐combining technique. An unequal allocation of headers to the image packets is also performed in order to reduce the overall distortion due to error propagation. Simulation results show that the proposed UEP scheme provides a gain of more than 8 dB in peak‐to‐peak signal‐to‐noise ratio over a tandem scheme. The flexibility of the proposed scheme, and the major performance gains obtained, make the scheme appealing for applications like, web‐based image browsing, multi‐hop networks, and wireless image transmission. Copyright © 2007 John Wiley & Sons, Ltd.     

Interference analysis and capacity for forward link 3G CDMA network with adaptive antennas

In code division multiple access (CDMA) systems, the capacity of forward link (FL) communication to mobile receivers is limited primarily by co‐channel interference (CCI). Adaptive antenna arrays (AAAs) that use antenna arrays along with advanced signal processing at the base station (BS) have been proposed to mitigate this limitation. For a 3G CDMA cellular network, where each BS equipped with an AAA serves mixture of voice and data users within its coverage, we study FL capacity and investigate the effects of different factors (array topology, multipath angle spread, data rate, and beamforming algorithm) on this capacity under Rayleigh fading channel. By modeling the instantaneous signal‐to‐interference power ratio received at the mobile, we derive the system outage equation that considers blocking of either desired voice or data user. Simulation results show that for the same element spacing and number of antenna elements per cell, the uniform circular array (UCA) topology results in larger capacity than the sectorized uniform linear array (ULA) topology does, and that a larger angle spread or data user rate reduces FL capacity. Copyright © 2007 John Wiley & Sons, Ltd.     

一种新颖的光罩可制造性规则检查方法与系统

介绍了一种较为先进的光罩可制造性规则检查的方法及其系统构成.实验结果表明,通过整合各种EDA工具,在光罩检验前就可发现这些可能给光罩检验造成困难的图形,为后续光罩检验步骤提供参考,显著提高了光罩检验的效率.     

一种适合增强干扰消除合并算法的同步方法

在GSM/EDGE基站,通常配备两个接收天线,以便在噪声和干扰受限的场景应用的合并算法,前者采用MRC算法,后者采用IRC算法。随着小区不断变小容量要求的不断提高,同频干扰成为抑制容量的主要因素。尤其是针对典型城区应用场景,基站需要配备性能增强的干扰消除合并技术,即EIRC。由于其增益相对于IRC来说大幅提高,所以适合IRC,MRC的同步精度就会制约EIRC的使用,另外由于EIRC对时偏较敏感,需要高精度的同步算法,文中提出了针对8PSK PS业务的新同步算法,可以较好地解决这一问题。     

CDMA通信中的空—时MRC和MMSE处理

本文针对两种不同的空－时数据结构,研究了直序扩频码分多址（DS－CDMA）通信中的最大比合并（MRC）和最小均方误差（MMSE）空0－时Rake滤波技术,分析了空－时数据结构对空－时MRC和MMSE Rake接收机完成性能的影响,并通过计算机对两种空－时数据结构空的空－时接收机的完成性能进行了比较。     

一种基于0.18-μm CMOS工艺的新型超宽频带毫米波混频器设计与分析

本文提出了一种超宽频带毫米波混频器电路.混频器采用分布式拓扑结构和中频功率合成技术,具有宽带宽和高转换增益.该混频器采用TSMC 0.18-μm CMOS工艺设计并制造,芯片总面积为1.67mm².测试结果表明:混频器工作频率从8GHz到40GHz,中频频率为2.5GHz时的转换增益为-0.2dB至4dB,其本振到中频端口和射频到中频端口间的隔离度均大于50dB.整个电路的直流功耗小于32mW.     

基于非均匀星座的改进ARQ方案及其性能分析

本文针对调制阶数大于4的MPSK和MQAM调制，在重传中采用非均匀星座图和符号比特重新排序，提出了一种改进的ARQ方案。通过对AWGN信道下ARQ方案进行理论分析和数值仿真，表明基于非均匀星座的新方案在信道条件较差时能有效地提高重要比特的可靠性，若重传中结合符号比特重排和分组合并，则可使接收端解调合并后的比特可靠性趋于均匀且总体得到提高，从而有效地减少重传次数，提高系统的吞吐率。由于本文所提方案并不改变调制解调规则和数据分组长度，故容易实现和控制。