Interference power statistics in ad-hoc and sensor networks

There exist accurate calculation methods for estimation of interference power sum statistics in fixed-topology wireless networks based on the log-normal shadowing radio model. Here we publish essential additions to these estimation methods to expand their use to sensor networks and ad-hoc networks with changing topology. In our calculations we take into account radio propagation conditions, density of nodes, size of the network, traffic load per node and MAC protocol characteristics. The accuracy of our calculation method is verified by simulations. We highlight the influence of MAC protocols on interference and show that an increase in network size or in node density does not necessarily lead into higher interference values. Our results can be deployed to estimate the network capacity. Ramin Hekmat received M.Sc. degree in electrical engineering from Delft University of Technology (TU Delft) in the Netherlands in 1990. He worked since then for several telecommunication companies in the Netherlands and the United States in Research and Development as well as managerial positions. In September 2005 he obtained Ph.D. degree for his work related to Ad-hoc Networks form TU Delft. Currently he is working as assistant professor in the faculty of Electrical Engineering, Mathematics and Computer Science of TU Delft. His prime research interest includes multi-user communication systems, wireless communications and peer-to-peer networks. Email: r.hekmat@ewi.tudelft.nl Mailing address: Delft University of Technology Electrical Engineering, Mathematics and Computer Science P.O. Box 5031 2600 GA Delft The Netherlands. Piet Van Mieghem has obtained the Master and Ph. D. in Electrical Engineering from the K.U.Leuven (Belgium) in 1987 and 1991, respectively. He has joined the Interuniversity Micro Electronic Center (IMEC) from 1987-1991. He was a visiting scientist at MIT, department of electrical engineering from 1992-1993. From 1993 to 1998, he was working in Alcatel Corporate Research Center in Antwerp where he has gained experience in performance analysis of ATM systems and network architectural concepts of both ATM networks (PNNI) and the Internet. Currently, he is full professor at Delft University of Technology with a chair in telecommunication networks. The main theme of the research is evolution of the Internet architecture towards a broadband and QoS-aware network. Email: p.vanmieghem@ewi.tudelft.nl Mailing address: Delft University of Technology Electrical Engineering, Mathematics and Computer Science P.O. Box 5031 2600 GA Delft The Netherlands.     

基于FPGA的802.11p MAC协议实验平台研究

目前对于802.11p MAC 协议的研究多是通过计算机仿真或理论分析的方式进行,缺乏对其实际性能进行验证的有效手段。通过对802.11p MAC标准基本机制的分析和研究,基于FPGA平台设计和实现了MAC协议实体,并构建了包含上位机软件、MAC实体、信道模拟及各种通信接口在内的完整的测试环境。为 MAC 相关算法和机制的研究构建了真实的分析验证平台,研究成果可直接应用于实际通信系统,缩短原型系统的开发周期。     

大型医院内部网络系统集成的设计与应用

文中叙述了一个大型医院内部网络系统集成的设计方案,指出了网络总体结构设计、网络路由设计、网络安全设计是医院网络系统集成建设的重中之重,并给出了这三个部分的具体设计方案.最后给出了网络拓扑图及具体设备选型及实施方案.     

Fiber Channel协议中CRC编码的硬件实现

介绍了光缆通道（Fiber Channel）协议中CRC校验编码的原理和硬件的实现。并结合仿真结果对面向字节的CRC-32编码器进行了论述。     

I-MAC: an incorporation MAC for wireless sensor networks

This paper proposes an innovative MAC protocol called I-MAC. Protocol for wireless sensor networks, which combines the advantages of collision tolerance and collision cancellation. The protocol increases the number of antenna in wireless sensor nodes. The purpose is to monitor the occurrence of packet collisions by increasing the number of antenna in real time. The built-in identity structure is used in the frame structure in order to help the sending node to identify the location of the receiving node after a data packet collision is detected. Packets can be recovered from where the conflict occurred. In this way, we can monitor the conflict for a fixed period of time. It can improve the channel utilisation through changing the transmission probability of collision nodes and solve the problem of hidden terminal through collision feedback mechanism. We have evaluated our protocol. Our results show that the throughput of I-MAC is 5 percentage points higher than that of carrier sense multiple access/collision notification. The network utilisation of I-MAC is more than 92%.     

基于UWB的Ad hoc无线网络

介绍了采用超宽带(UWB)技术的Ad hoc无线网络,重点阐述了网络的两个关键技术MAC协议和路由算法协议.     

基于P2P架构和SIP协议的多媒体邮件网络研究

文中提出了一种在P2P架构上的基于SIP协议的多媒体邮件网络,他可以克服IP网络上的服务器瓶颈问题和H.323协议的繁琐及低效率问题.同时介绍了本网络采用该P2P架构和SIP协议的优势所在.在此基础上,还介绍了本网络如何对多媒体信息流的获取、存储管理以及播放.最后,对各个功能模块进行了总体介绍.     

针对蓝牙设备的测试分析

本文首先简单介绍了蓝牙的基本概况,然后深入阐述了蓝牙测试模式的建立和测试方案的分析,并讨论了蓝牙协议测试的统一接口-测试控制接口,对L2CAP一致性测试结构进行了分析和论述,为广大从事蓝牙设备测试的工程师提供了一个有益的借鉴.     

ATM的技术优势

介绍了ATM与IP的结合技术,ATM与SDH、FR技术的优缺点,以及ATM与各兆以太网的竞争,并对发展趋势作了预测。     

无线Ad Hoc网络MAC层速率自适应技术研究

目前的IEEE802.11标准虽然在物理层提供了对多速率的支持,但是在MAC（媒体接入控制,Media Access Control）层却没有规定速率自适应的方法。研究了无线Ad Hoc网络（自组织网）中的速率自适应技术,针对RBAR协议存在的不足提出了一种改进的MAC层速率自适应协议,该协议实现简单,与标准的兼容性好,对信道的变化适应能力更强。仿真结果表明,该协议比RBAR协议具有更好的性能。