无线接入技术WiMAX研究

本文探讨了WiMAX技术,对WiMAX网络结构进行了分析研究,在此基础上,指出了WiMAX发展前景。     

USB接口与1394接口的比较

USB传输类型包括批量传输、同步传输、中断传输和控制传输,每种传输类型的传输速度、可靠性以及应用范围都不同.控制传输可靠性是最高的,但速度最慢;同步传输速度快,但可靠性低.IEEE1394接口的传输通过分层协议实现,分为物理层、链路层和业务层,它规范了一个三层协议集,将宿主系统经由串行总线与各外围设备的交互动作标准化.     

On service differentiation in mobile Ad Hoc networks

A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile. Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.     

Robust Joint Timing and Frequency Synchronization Algorithm for IEEE802.16e OFDM System

Based on the structures of the short preamble and long preamble,which are defined for synchronization in IEEE802.16e specification,the robust synchronization algorithm for IEEE802.16e OFDM system is proposed.The correlations among the sample sequences in the preamble are investigated,especially the correlation between the first sample sequence and the last sample sequence in the long preamble.The conventional joint timing and frequency synchronization algorithm is reviewed based on the short preamble referring to the algorithm proposed by Schmidl,then a robust joint timing and frequency synchronization algorithm is proposed based on the long preamble.The simulations in the multi-path and frequency selective fading channel show that the proposed algorithm has improved the performances of timing metric plateau,timing offset and synchronization acquisition time even when signal-to-noise ratio is less than-5 dB.     

无线局域网802.1x协议应用与安全性分析

介绍了无线局域网的安全机制及其应用特点,分析了协议中的不足,给出了一种简单的改进措施。     

WLAN技术的应用及其发展趋势

近年来无线局域网技术的发展日益成熟与完善．主要介绍其网络拓扑结构、特点优势、系列标准等。相关技术．     

无线局域网安全问题及解决方案

本研究了无线局域网常用的安全技术，分析了IEEE802．11b存在的主要安全缺陷，提出了一些解决无线安全问题的方案。     

无线网络技术与校园网的组建

介绍无线网络的基本概念,阐述其技术特点、网络标准、应用领域及所需设备,并给出一个组建校园网络的方案设想.     

基于ZigBee的无线火灾报警系统

集成化、网络化和智能化是安防报警系统未来的发展趋势,ZigBee技术是一种全球统一标准的无线技术,成本低、低功耗,支持无线组网。本文依据ZigBee的这些特点,设计了一个基于ZigBee的无线火灾报警系统。     

基于ZigBee技术构建无线传感器网络

基于无线传感器网络和ZigBee协议特点分析了ZigBee协议栈的体系结构、无线传感器网络的组网原理、构建基于ZigBee技术的无线传感器网络的关键技术;采用模块化方法实现了ZigBee协议栈,并结合传感器技术、ZigBee技术、IEEE 802.15.4协议、路由协议设计系统架构、ZigBee无线技术组网及传输模式;重点探讨基于ZigBee技术无线传感器网络的构建与应用.