A New Scheme to Realize Crosstalk-Free Permutation in Vertically Stacked Optical MINs*

Vertical stacking is a novel alternative for constructing nonblocking multistage interconnection networks (MINs). Rearrangeably nonblocking optical MINs are attractive since they have lower complexity than their strictly nonblocking counterparts. In this paper, we study the realization of crosstalk-free permutations in rearrangeably nonblocking, self-routing banyan-type optical MINs built on vertical stacking. An available scheme for realizing crosstalk-free permutation in this type of optical MINs requires to first decompose a permutation into multiple crosstalk-free partial permutations based on the Euler-Split technique, and then to realize them crosstalk-free in different planes (stacked copies) of the MIN simultaneously. The overall time complexity of this scheme to realize a crosstalk-free permutation in an N × N optical MIN is O(N log N) which is dominated by the complexity of crosstalk-free decomposition. In this paper, we propose a new scheme for realizing permutations in this class of vertically stacked optical MINs crosstalk-free. The basic idea of the new scheme is to classify permutations into permutation classes such that all permutations in one class share the same crosstalk-free decomposition pattern. By running the Euler-Split based crosstalk-free decomposition only once for a permutation class and applying the obtained crosstalk-free decomposition pattern to all permutations in the class, crosstalk-free decomposition of permutations can be realized in a more efficient way. We show that the number of permutations in a permutation class is huge (N!)^N when log₂N is even and (2N!)^N/2 when log₂N is odd), and thus the average time complexity of crosstalk-free decomposition of a permutation becomes O(N).     

High Performance Wireless Switch Protocol for IEEE 802.11 Wireless Networks

All mobile stations (STAs) in IEEE 802.11 infrastructure wireless local area networks (IWLAN) are coordinated by an access point (AP). Within the 2.4 GHz unlicensed industry, science, and medicine (ISM) band defined in the IEEE 802.11 2.4 GHz physical layer (PHY) specifications, three channels are available for concurrently transferring data packets at the coverage area of an AP. In most of small/medium enterprises or home environments, an AP with one selected channel is sufficient for covering whole service area, but this implies that the radio resources for the remaining two channels are wasted. In order to overcome the drawback, we propose a new and simple media access control (MAC) protocol, named wireless switch protocol (WSP), for increasing the throughput of IEEE 802.11 IWLAN network to support high quality multimedia traffic. This is achieved by allowing any pair of STAs in IWLAN to exchange data packets in one of other idle channels after their handshake with each other in the common channel controlled by AP. Simulation results show that the total network throughput of WSP depends on the time taken by channel switching, and on the ‘Intranet’ and ‘Internet’ traffic distribution, where the Intranet and Internet mean data transmission between STAs in IWLAN and between the STA and wired host, respectively. When all data packets are Intranet traffic and the traffic load is heavy, the ratio of Goodput for the proposed WSP to that of IEEE 802.11 standard approximates 400%. In the worse case of all Internet traffic, the proposed WSP still obtains the similar throughput as that of IEEE 802.11 standard.Jenhui Chen was born on October 12, 1971 in Taipei, Taiwan, Republic of China. He received the Bachelor’s and Ph.D. degree in Computer Science and Information Engineering (CSIE) from Tamkang University in 1998 and 2003, respectively. In the Spring of 2003, he joined the faculty of Computer Science and Information Engineering Department at Chang Gung University and served as the Assistant Professor. He occupies the supervisor of Network Department in the Information Center, Chang Gung University. Dr. Chen once served the reviewer of IEEE Transactions on Wireless Communications, ACM/Kluwer Mobile Networks and Applications (MONET), and Journal of Information Science and Engineering. His main research interests include design, analysis, and implementation of communication and network protocols, wireless networks, milibots, and artificial intelligence. He is a member of ACM and IEEE.Ai-Chun Pang was born in Hsinchu, Taiwan, R.O.C., in 1973. She received the B.S., M.S. and Ph.D. degrees in Computer Science and Information Engineering from National Chiao Tung University (NCTU) in 1996, 1998 and 2002, respectively. She joined the Department of Computer Science and Information Engineering, National Taiwan University (NTU), Taipei, Taiwan, as an Assistant Professor in 2002. Her research interests include design and analysis of personal communications services network, mobile computing, voice over IP, and performance modeling.Shiann-Tsong Sheu received his B.S. degree in Applied Mathematics from National Chung Hsing University in 1990, and obtained his Ph.D. degree in Computer Science from National Tsing Hua University in May of 1995. From 1995 to 2002, he was an Associate Professor at the Department of Electrical Engineering, Tamkang University. Since Feb. 2002, he has become a Professor at the Department of Electrical Engineering, Tamkang University. Dr. Sheu received the outstanding young researcher award by the IEEE Communication Society Asia Pacific Board in 2002. His research interests include next-generation wireless communication, WDM networks and intelligent control algorithms.Hsueh-Wen Tseng received his B.S. degree in electrical engineering from Tamkang University, Taipei country, Taiwan, in 2001 and M.S. degree in electrical engineering from National Taiwan University of Science and Technology, Taipei, Taiwan, in 2003. He is currently pursuing the Ph. D. degree at the Department of Computer Science and Information Engineering, National Taiwan University, Taipei, Taiwan. His research interests include design, analysis and implementation of network protocols and wireless communications.     

A 1.9-GHz Direct Conversion Transmitter IC with Low Power On-Chip Frequency Doubler

A direct conversion transmitter IC including a proposed frequency doubler, a quadrature modulator, and a 3-bit variable attenuator was fabricated using BiCMOS technology with f of 12 GHz. This architecture employing frequency doubler is intended for realizing wireless terminals that are low in cost and small in size. The architecture is effective for reducing serious interference between PA and VCO by making the VCO frequency different from that of PA. The proposed frequency doubler comprises a current-driven 90° phase-shifter and an ECL-EXOR circuit for both low power operation and wide input power range of local oscillator (LO). The proposed frequency doubler keeps high output power even when rectangular wave from LO is applied owing to use of the current-driven 90° phase-shifter instead of a voltage-driven 90° phase-shifter. An LO leakage of less than –25 dBc, an image rejection ratio in excess of 45 dBc, and a maximum attenuation of 21 dB were measured. The transmitter IC successfully operates at LO power above –15 dBm and consumes 68 mA from 2.7 V power supply voltage. An active die size is 1.5 mm×3 mm.     

发展中的RF MEM5开关技术

射频MEMS开关是用MEMS技术形成的新的电路元件,与传统的半导体开关器件相比具有插入损耗低、隔离度大、线性度好等优点,将对现有雷达和通信中RF结构产生重大的影响.介绍了射频MEMS开关的工作原理、优化设计,分析了可靠性问题,举例说明了射频MEMS开关的应用,指出了其发展所面临的问题.     

非线性阻抗变换式斩波电路

利用非线性阻抗元件的导通，关断及储能的特性，设计了一个非线性阻抗变换环节，并融合到斩波电路中，有效地拓宽了降压斩波输出电压的调节范围，并提高了输出电流。同时也有利于改善系统的功率因数品质。     

下一代光因特网体系结构的选择与比较

下一代光因特网(NGOI)体系结构的基本特征是两层(业务层和传送层)和三个平面(数据平面、控制平面、管理平面)。分析和归纳了四种主流的面向下一代光因特网体系结构模型。提出了一种基于通用多协议标记交换(GMPLS)技术和光电混合交换技术的集成光因特网模型,该模型与其它模型相比较,结合了光电两个领域的技术优势,具有网络综合性能高,容易实现,扩展性好等优点。     

大口径线性连续衰减器技术的研究

讨论了用于标定激光测距机测程所必须用到的连续衰减器的设计、制作与标定中的几个关键技术问题。研究了大口径线性连续衰减器为实现0 2～10dB线性连续可变的透过率控制技术。分析了连续衰减值的正交多项式曲面拟和差值算法。给出了实用化的标定结果。     

一个光时分多路技术原理实验

光时分多路(OTDM)技术是电时分多路技术扩展到光范畴内的一种技术。本文给出一个每支路速率为34Mb/s的光时分多路原理实验的结果。实验中应用普通半导体激光器,而不是用锁模半导体激光器。应用具有极低反射的4×1光纤藕合器进行光脉冲信号的汇合,消除反射对光源稳定工作的影响。为了避免波形复盖,减小交叉干扰,每一支路的光脉冲均为RZ码。光时分多路技术可以克服光纤通信系统中电子速率瓶颈问题,将使光纤系统的速率大大提高。     

Pockels光纤传感器在电力工业中的新应用

本文通过Pockels光纤传感器原理构成和真空灭弧室等效电路的分析,计论了一种利用多通道于Pockels光纤传感监测系统监测高压大电流真空开闭设备中灭弧窒真空度的新方法。     

CMOS模拟开关的导通与截止特性

本文对CMOS模拟开关漏电流、导通电阻、电阻偏差,分布电容及外接负载等对模拟信号传输的影响进行了比较深入的分析,提出了改进开关性能的途径。