以太网供电电源的设计与实现

以太网供电技术的核心是利用信号线传输直流电能,它既省去了架设供电线路的成本,又为供电的集中管理创造了条件,在通讯设备繁多、使用环境复杂的背景下具有较高的使用价值。给出了基于以太网供电协议IEEE802.3at的以太网供电系统设计方案。选用德州仪器公司(TI)的TPS23851作为供电设备控制芯片,用以对受电设备进行识别、分级、供电、检测等操作;受电设备选用TPD2376-H用以辅助供电设备完成供电协议要求的供电操作;后级的DC-DC降压变换器选用Power Integrations的DPASwitch424,将直流电压变换为适宜于以太网供电的电压等级。基于以上方案,研制了一套以太网供电系统,系统能满足IEEE802.3at标准要求,实现了以太网供电功能。     

Ad Hoc网络数据链路层协议的研究

本文主要研究二进制指数退避算法BEB及乘性增加线性减少算法MILD,重点分析两种算法在Ad Hoc网络中的效能。采用计算机仿真软件OPNET验证此算法,通过仿真平台了解两种算法的优缺点,比较不同的算法对网络的公平性、吞吐量、延迟及系统丢包率的影响。仿真结果表明,MILD算法能够在高负载场景的网络下使移动Ad Hoc网络有效的提高吞吐量、降低平均时延和丢包量等。但是MILD算法也有自身的缺点,在轻负荷网络中,该算法的因无法快速调节竞争窗口而导致性能急剧下降。     

IEEE802.11MAC层性能仿真及分析

介绍了NS2的工作原理及仿真的基本流程,阐述了IEEE802.11MAC协议和其两种基本访问控制方式,并在一定的拓扑环境下模拟仿真试验,分析和评价网络的性能,最后总结了NS2网络仿真技术的实用价值.     

WiMAX标准体系研究

WiMAX得到了业界的广泛支持，其标准化进程不断推进。文中给出了WiMAX标准化组织IEEE 802．16工作组和WiMAX论坛的组织机构，分析了两大组织之间的相互关系，探讨了WiMAX最新标准化进展，从空中接口标准、一致性标准和共存标准三方面介绍了IEEE 802．16系列标准现状。     

基于随机Petri网的IEEE 802.11DCF协议建模

本文首先提出了增强广义随机Petri网,增加了标识相关弧多样性和实施函数等特性,扩充了广义随机Petri网的模型功能,并给出了EGSPN的性能分析方法,建立了基于随机Petri网的802.11协议模型,并以RTS/CTS访问方式下协议性能计算及结果分析为例验证了该方法的有效性。     

IEEE软件工程标准综述

简要介绍了ＩＥＥＥ软件工程标准的发展历史,以及ＩＥＥＥ现行的全部３８项正式软件工程标准和２项试用软件工程标准的内容。     

移动宽带无线城域网关键技术及其展望

本文应用产业竞争模型、产业创新理论和交易成本理论证明:创意产业集聚区之所以形成,除了因为它具有外部性规模经济的优势外,还因为它促进内部的竞争,推动创新和节约交易成本。竞争、创新和节约也是创意产业集聚区形成的3个重要机理。     

Wi-Fi as a Commercial Service: New Technology and Policy Implications

While Wi-Fi has enjoyed explosive growth and deployment for use in residential homes, the rollout of commercial Wi-Fi service has been more limited. Part of the holdback on large-scale commercial deployment has been the strategic concern that the commons model to spectrum management lacks the incentives for service providers to invest due to the limited ability to manage interference in the unlicensed band. Today, however, this situation appears to have changed. To explain the new confidence by service providers in commercial Wi-Fi, the activities of the Wi-Fi Alliance and IEEE 802.11 standards body are analyzed to show how these groups essentially replicate many, but not all, of the functions traditionally employed by an effective band manager that is optimizing efficiency on a licensed spectrum block more typically associated with the deployment of commercial services. Consequently, with the Wi-Fi ecosystem functioning as an effective spectrum manager, it is concluded that the service provider investment in Public Wi-Fi networks is rational and the risk posed by saturation or overuse has been reduced to an acceptable level. The strategic implications of this finding on the Wi-Fi platform are the examined. How the requirements from service providers are already significantly influencing the evolution of the Wi-Fi standard is discussed, and an attempt is made to address the risks and liabilities associated with the unlicensed spectrum management model. Thus, service providers increasingly need functionality in Wi-Fi technology to manage interference, and monitor and improve network performance. The current ideas under discussion are elaborated for the next version of Wi-Fi to support both commercial Wi-Fi requirements, which address the interference concerns, but only up to a point, as the unlicensed model intrinsically leaves some risk to participants of spectrum saturation through overuse.     

IEEE802.11MAC层性能仿真及分析

介绍了NS2的工作原理及仿真的基本流程,阐述了IEEE802.11 MAC协议和其两种基本访问控制方式,并在一定的拓扑环境下模拟仿真试验,分析和评价网络的性能,最后总结了NS2网络仿真技术的实用价值。     

基于ZigBee的城市战红外人体探测系统

针对城市战战场环境复杂,兵力部署多变的特点,提出了一种基于ZigBee技术的红外人体探测系统方案.系统具有低功耗、易部署、抗干扰等特点,可以通过CC2430无线芯片将报警数据传送给监视主机,为指挥员决策提供依据.