基于竞争终端个数和跳数的802.11Mesh网络公平性优化机制

设计了一种基于竞争终端个数和跳数的公平性优化机制通过调整MeshAP的协议参数来改善不同跳数间竞争终端的公平性,同时,根据同一MeshAP下竞争终端的个数,按照预先设定的区间,动态调整其下各终端的协议参数,从而在改善系统传输性能的同时,进一步优化不同跳数间竞争终端的公平性.给出了这一机制的详细实现步骤,并利用ns2,对这一新的机制在各种场景下进行了大量的仿真实验.相关实验结果验证了这一优化机制不仅算法简单,系统开销小,适合于复杂多变的无线环境,而且能够根据竞争终端个数动态对无线系统中不同跳数下的竞争终端的公平性进行整体的优化.     

无线局域网技术及应用

无线局域网技术是目前发展迅速的技术，相对于有线局域网有许多优点。随着无线网络产品性能的提高和价格的不断下降，无线局域网技术有着广泛的应用前景。据此对无线局域网的基本概念、特点及其技术作了简单的介绍，提出了无线局域网面向应用的几种解决方案，并对发展前景作了预测。     

FHCF: A Simple and Efficient Scheduling Scheme for IEEE 802.11e Wireless LAN

The IEEE 802.11e medium access control (MAC) layer protocol is an emerging standard to support quality of service (QoS) in 802.11 wireless networks. Some recent work shows that the 802.11e hybrid coordination function (HCF) can improve significantly the QoS support in 802.11 networks. A simple HCF referenced scheduler has been proposed in the 802.11e which takes into account the QoS requirements of flows and allocates time to stations on the basis of the mean sending rate. As we show in this paper, this HCF referenced scheduling algorithm is only efficient and works well for flows with strict constant bit rate (CBR) characteristics. However, a lot of real-time applications, such as videoconferencing, have some variations in their packet sizes, sending rates or even have variable bit rate (VBR) characteristics. In this paper we propose FHCF, a simple and efficient scheduling algorithm for 802.11e that aims to be fair for both CBR and VBR flows. FHCF uses queue length estimations to tune its time allocation to mobile stations. We present analytical model evaluations and a set of simulations results, and provide performance comparisons with the 802.11e HCF referenced scheduler. Our performance study indicates that FHCF provides good fairness while supporting bandwidth and delay requirements for a large range of network loads. Pierre Ansel received a multidisciplinary in-depth scientific training in different fields such as Pure and Applied Mathematics, Physics, Mechanics, Computer Science and Economics from the Ecole Polytechnique, Palaiseau, France. Then, he joined the Ecole Nationale Superieure des Telecommunications, Paris, France in 2005 where he went further into electronics, databases, computer network security and high speed networks. He received a multidisciplinary master of sciences degree and an additional master of sciences degree in telecommunications in 2005. He did a summer internship in 2003 in INRIA, Sophia Antipolis, France where he worked on the Quality of Service in 802.11 networks at Planete Group, France. Then in 2004, he joined France Telecom R&D, Issy-les-Moulineaux, France to work on Intranet Security issues. He designed a WiFi security supervision architecture based on WiFi Intrusion Detection Sensors. He is currently a French civil servant and belongs to the French Telecommunications Corps. Qiang Ni received the B.Eng., M.Sc. and Ph.D. degrees from Hua Zhong University of Science and Technology (HUST), Wuhan City, China in 1993, 1996 and 1999 respectively. He is currently a faculty member in the Electronic and Computer Engineering Division,School of Engineering and Design, Brunel University, West London, U.K. Between 2004 and 2005 he was a Senior Researcher at the Hamilton Institute, National University of Ireland, Maynooth. From 1999 to 2001, he was a post-doctoral research fellow in the multimedia and wireless communication laboratory, HUST, China. He visited and conducted research at the wireless and networking group of Microsoft Research Asia Lab during the year of 2000. From Sept. 2001 until may 2004, he was a research staff member at the Planète group of INRIA Sophia Antipolis France. Since 2002, he has been active as a voting member at the IEEE 802.11 wireless LAN standard working group. His current research interests include communication protocol design and performance analysis for wireless networks, cross-layer optimizations, vertical handover and mobility management in mobile wireless networks, and adaptive multimedia transmission over hybrid wired/wireless networks. He has authored /co-authored over 40 international journal/conference papers, book chapters, and standard drafts in this field. He is a member of IEEE. E-mail: Qiang.Ni@ieee.org Thierry Turletti received the M.S. (1990) and the Ph.D. (1995) degrees in computer science both from the University of Nice – Sophia Antipolis, France. He has done his PhD studies in the RODEO group at INRIA Sophia Antipolis. During the year 1995–96, he was a postdoctoral fellow in the Telemedia, Networks and Systems group at LCS, MIT. He is currently a research scientist at the Planete group at INRIA Sophia Antipolis. His research interests include multimedia applications, congestion control and wireless networking. Dr. Turletti currently serves on the Editorial Board of Wireless Communications and Mobile Computing.     

SW233 PIN驱动器自动测试系统的研制

介绍了一种集成电路自动测试系统，该系统采用计算机并口作通信接口，用VB6编程，实现了对外围测试电路的控制，用IEEE-488接口卡控制测试仪器，可对SW233电路的36个参数进行自动测试，并将测试结果自动保存在数据库中。该测试系统具有自动化程度高、操作方便、测试结果精确等特点。     

基于IEEE1451.2的智能变送器接口模块的设计与实现

IEEE1451.2标准为将不同的智能变送器连接到网络适配器(NCAP)或微处理器制定了一个统一的数字接口,真正实现了现场设备的即插即用。简述了IEEE1451.2标准,重点介绍了智能变送器接口模块(STIM)的软硬件设计思想和测试平台,通过实践验证了采用ADuC812芯片实现智能变送器接口模块的可行性。     

Event-driven,pattern-based methodology for cost-effective development of standardized personal health devices

Experiences applying standards in personal health devices (PHDs) show an inherent trade-off between interoperability and costs (in terms of processing load and development time). Therefore, reducing hardware and software costs as well as time-to-market is crucial for standards adoption. The ISO/IEEE11073 PHD family of standards (also referred to as X73PHD) provides interoperable communication between PHDs and aggregators. Nevertheless, the responsibility of achieving inexpensive implementations of X73PHD in limited resource microcontrollers falls directly on the developer. Hence, the authors previously presented a methodology based on patterns to implement X73-compliant PHDs into devices with low-voltage low-power constraints. That version was based on multitasking, which required additional features and resources. This paper therefore presents an event-driven evolution of the patterns-based methodology for cost-effective development of standardized PHDs. The results of comparing between the two versions showed that the mean values of decrease in memory consumption and cycles of latency are 11.59% and 45.95%, respectively. In addition, several enhancements in terms of cost-effectiveness and development time can be derived from the new version of the methodology. Therefore, the new approach could help in producing cost-effective X73-compliant PHDs, which in turn could foster the adoption of standards.     

基于IEEE 80211e EDCA的下行信道动态无竞争接入机制*

为了改善无线局域网络服务质量,IEEE工作组形成了增补标准IEEE 802.11e,但是其增强的接入机制仍然不能完全满足IPTV、视频点播等类似场景的应用。为此提出了针对这一类应用场景的一种新的简单易行的下行信道动态无竞争接入机制,该机制基于MAC层队列长度信息动态调整下行信道接入参数,能有效地保护下行流媒体数据的传输,通过仿真结果验证了该机制有效并且实用。     

IEEE802.15.4a信道对UWB功率谱影响分析

研究超宽带功率谱密度,从路径损耗模型、多路径模型和小尺度衰落模型方面分析IEEE802.15.4a工作组信道模型.采用直接序列脉冲(direct-sequence pulse-amplitude modulation,DSP-PAM)超宽带(ultra-wideband,UWB)系统的信道响应,仿真分析了8种信道对2～10 GHz超宽带系统功率谱分布情况.仿真结果表明,多路径信道对UWB功率谱影响不大,脉冲UWB具有抗多路径干扰能力强的特点.     

高速数据传输单元

为了满足无人机数据链对下行数据高速实时传输的要求,实现了一种基于PowerPC处理器和IEEE1394总线的高速数据传输单元。首先介绍了无人机数据链对下行数据传输设备的设计需求,其次详细介绍了下行数据传输设备的系统结构和数据传输单元的软硬件实现,最后通过 IEEE1394总线环绕测试的方法,验证了数据传输单元的功能和性能。验证结果表明：该数据传输单元具有设计简单、传输速率高、可靠性高和功耗低的特点,具有广泛的应用前景。