ASON管理系统的设计和实现

文章提出了一种分层的域间自动交换光网络管理系统方案，设计了相关的网络管理信息模型，并对ASON管理系统的关键实现技术进行了介绍，最后给出了所实现的ASON管理系统的部分试验结果。     

A call admission and rate control scheme for multimedia support over IEEE 802.11 wireless LANs

Quality of service (QoS) support for multimedia services in the IEEE 802.11 wireless LAN is an important issue for such WLANs to become a viable wireless access to the Internet. In this paper, we endeavor to propose a practical scheme to achieve this goal without changing the channel access mechanism. To this end, a novel call admission and rate control (CARC) scheme is proposed. The key idea of this scheme is to regulate the arriving traffic of the WLAN such that the network can work at an optimal point. We first show that the channel busyness ratio is a good indicator of the network status in the sense that it is easy to obtain and can accurately and timely represent channel utilization. Then we propose two algorithms based on the channel busyness ratio. The call admission control algorithm is used to regulate the admission of real-time or streaming traffic and the rate control algorithm to control the transmission rate of best effort traffic. As a result, the real-time or streaming traffic is supported with statistical QoS guarantees and the best effort traffic can fully utilize the residual channel capacity left by the real-time and streaming traffic. In addition, the rate control algorithm itself provides a solution that could be used above the media access mechanism to approach the maximal theoretical channel utilization. A comprehensive simulation study in ns-2 has verified the performance of our proposed CARC scheme, showing that the original 802.11 DCF protocol can statically support strict QoS requirements, such as those required by voice over IP or streaming video, and at the same time, achieve a high channel utilization. Hongqiang Zhai received the B.E. and M.E. degrees in electrical engineering from Tsinghua University, Beijing, China, in July 1999 and January 2002 respectively. He worked as a research intern in Bell Labs Research China from June 2001 to December 2001, and in Microsoft Research Asia from January 2002 to July 2002. Currently he is pursuing the PhD degree in the Department of Electrical and Computer Engineering, University of Florida. He is a student member of IEEE. Xiang Chen received the B.E. and M.E. degrees in electrical engineering from Shanghai Jiao Tong University, Shanghai, China, in 1997 and 2000, respectively, and the Ph.D. degree in electrical and computer engineering from the University of Florida, Gainesville, in 2005. He is currently a Senior Research Engineer at Motorola Labs, Arlington Heights, IL. His research interests include resource management, medium access control, and quality of service (QoS) in wireless networks. He is a Member of Tau Beta Pi and a student member of IEEE. Yuguang Fang received a Ph.D degree in Systems and Control Engineering from Case Western Reserve University in January 1994, and a Ph.D degree in Electrical Engineering from Boston University in May 1997. From June 1997 to July 1998, he was a Visiting Assistant Professor in Department of Electrical Engineering at the University of Texas at Dallas. From July 1998 to May 2000, he was an Assistant Professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology. In May 2000, he joined the Department of Electrical and Computer Engineering at University of Florida where he got the early promotion with tenure in August 2003 and has been an Associate Professor since then. He has published over one hundred (100) papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He is currently serving as an Editor for many journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing, and ACM Wireless Networks. He is also actively participating in conference organization such as the Program Vice-Chair for IEEE INFOCOM’2005, Program Co-Chair for the Global Internet and Next Generation Networks Symposium in IEEE Globecom’2004 and the Program Vice Chair for 2000 IEEE Wireless Communications and Networking Conference (WCNC’2000).     

基于软件定义的网络准入控制体系

网络准入控制主要通过安全认证与控制实现端点的安全接入,各类准入控制技术不断涌现和发展以解决局域网边界安全问题,然而随着网络复杂性和部署管理便捷性要求的提升,固定的准入控制手段已不能适应种类繁多的安全场景需求。综述准入控制框架及技术发展,提出一种基于软件定义思想的准入控制体系,阐述其模型、架构、主要技术及应用场景,通过资源编排、资产管理与态势统一呈现等设计适应不同用户环境的安全准入和资产管理需求。     

一种软件源的可信管控模型设计

基于对目前可信计算信任链及度量基准值采集流程存在的问题,提出了软件源的可信管控模型,实现软件的安全认定、度量基准值统一计算采集以及可信第三方的集中管控,为软件的可信运行奠定了基础,降低了可信度量值采集工作的复杂度,对软件源的可信管控实施具有一定的指导意义。此外,进行了软件可信表征格式和基于可信表征的可信度量流程设计,将软件源的可信延伸至软件加载的可信和软件运行的可信,较大程度地提升了软件全生命周期的可信证明强度。     

TTP总线在分布式飞控计算机系统中的应用

TTP总线具有高确定性、低时延、容错支持等优点,在构建有硬实时需求的安全关键分布式容错系统中有较大优势。文章简要总结了飞控计算机系统对系统总线的需求,介绍了TTP总线分布式时钟同步与确定性通信技术,分析了TTP总线容错特性与安全性,设计了基于TTP总线的三余度分布式飞控计算机系统,测试验证了系统中的TTP总线同步精度、通信延迟与抖动、TTP总线对飞控功能的支持等,能够满足飞控计算机系统的通信需求。     

基于流量工程的软件定义网络控制资源优化机制

针对软件定义网络(SDN)分布式控制平面中由于网络分域管理所引发的控制扩张问题,该文提出了一种基于流量工程的SDN控制资源优化(TERO)机制。首先基于数据流的路径特征对流请求的控制资源消耗进行分析,指出通过调整控制器和交换机的关联关系可以降低控制资源消耗。然后将控制器关联过程分为两个阶段：先设计了最小集合覆盖算法来快速求解大规模网络中控制器关联问题;在此基础上,引入联合博弈策略来优化控制器和交换机的关联关系以减少控制资源消耗和控制流量开销。仿真结果表明,与现有的控制器和交换机就近关联机制相比,该文机制能在保证较低控制流量开销的前提下,节省约28%的控制资源消耗。

     

GMPLS的一种镜像保护恢复机制

对通用多协标记交换(GMPLS)在控制平面的保护恢复技术作了系统的分析和研究;引进了一种对链路信息进行备份恢复的镜像恢复机制,并对此机制进行了分析,提出了改进方案,有效地解决了"多余备份"的现象.     

MAX6625型温度传感器的原理及应用

MAX6625是美国Maxim公司生产的一种新型智能温度传感器,它在风扇控制、温度告警、系统温度测量及工业设备中得到了广泛应用.介绍MAX6625的功能和结构,分析MAX6625的工作原理,给出采用MAX6625进行温度测控的电路及编程.     

ISD2500与ATmega8单片机配合使用的智能语音系统设计

提出了一种利用ATmega8单片机对ISD2500系列语音芯片进行控制的智能语音系统,此系统使用灵活,易于功能升级,具有良好的应用前景.提供了硬件连接电路和关键源程序.     

采用RF2607的WLAN自动增益控制设计

介绍了宽动态变化范围的新型可变增益放大器RF2607的特性、功能,给出了利用RF2607设计无线局域网(WLAN)通信中自动增益控制部分的实用电路.