A cross-layer framework for video-on-demand service in multi-hop WiMax mesh networks

In this work, we introduce a cross-layer framework to favor the video-on-demand service in multi-hop WiMax mesh networks. We first propose a joint solution of admission control and channel scheduling for video streams. The proposed approach guarantees that the required data rate is achieved for video streams, which is crucial for multimedia streaming applications. An efficient and light-weight multicast routing technique is also proposed to minimize the bandwidth cost of joining a multicast tree. Furthermore, we adopt the Patching technique in the application layer to improve the capacity of the video server. Overall, the quality of the video-on-demand service is dramatically improved with the help of the efficient cooperation between the techniques proposed in different layers of the network. Simulation study shows that with the proposed approach, true video-on-demand in WiMax mesh networks can be achieved under high video request arrival rate.     

无线专网技术在智能配网中的应用

随着国家智能电网的建设,新一代配网自动化系统处于试点建设阶段。配电自动化和现代通信技术的结合,特别是无线通信技术,包括3G、WiMax、Wi-Fi等新技术,对于配网自动化,智能化的发展有着重要的意义。与传统通信系统的数据传输相比,无线专网具有低成本、高频谱利用率、高可靠性等优点。该文介绍了三种热门无线专网的技术特性并和传统通信方式进行了分析比较。     

Analysis of frequency‐selective impedance loading of transmission lines for dual‐band couplers

This article proposes an analytical design methodology for dual‐band hybrid couplers and baluns structures for any arbitrary frequency ratio using a stub‐loaded transmission line. An analysis of changing the impedance behavior of the stub, is carried out for the two bands of operation, which along with a dispersive analysis, emphasizes certain conditions where the existing methodology is not applicable. In addition, an extra degree of freedom has been included to increase the solutions for a given frequency ratio, thus providing greater flexibility and feasibility of the proposed structure. The design methodology is experimentally validated with the design and fabrication of dual‐band branch‐line and rat‐race couplers for various commercial frequency bands. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

一种多收发器WiMax mesh网络集中式调度算法

根据IEEE 802.16协议,集中式调度是WiMax mesh网络中的主要带宽调度方式.目前的集中式调度算法只适用于单收发器系统.本文研究多收发器WiMax mesh网络中的调度问题,提出一种集中式调度与信道分配算法.该算法用令牌代表数据包在路由树上的传输,在每个时隙内选择可以并行传输的链路集合并分配信道.模拟实验表明本文提出的算法可以充分利用多收发器系统特性,有效减少总传输时间.     

电网异构无线灾备应急网络组网设计

发生重大灾害时,容易造成建筑和设备损坏,导致电力通信中断,因此需要快速恢复电力通信供应以保障抗灾救险工作.使用WiMax,WiFi和微波技术通过抗灾救险中电力通信需求分析,以及对无线技术的比较,提出了灾备异构无线网络组网方案,并对其运行方式进行讨论.     

WiMax功率放大器测试解决方案

WiMax功率放大器的参数测试往往要求信号源和频谱仪构成不同的配置，这些测试常常是耗时而费力的。对此，R＆S公司提供了一款在外部PC上运行的测试程序DemoMeas_WiMax，与信号源和频谱仪一起，实现WiMax功放所有参数的自动化测试。     

中国3G市场调研

文章是针对目前中国3G的建设及市场需求进行分析,通过对3G发展的简介到目前中国三大营运商对3G建设的投入状况详细总结。概述了3G建网历次招标的情况及相关受益的设备厂商,并对中国3G带来的PCB行业机遇及挑战进行了分析。     

WiMax技术在中海油渤海矿区应用的前景分析

针对近年来渤海矿区现有的有线网络无法满足要求与矿区宽带对网络需求急速发展的矛盾,从中海油自身特点出发,结合WiMax的技术特点和优势,探讨了将其用于中海油渤海矿区通信系统的前景及可能性,并提出了自己的想法。     

基于IEEE802．16的WiMax组网技术

无线宽带城域网正在成为无线接入领域新的热点,基于此重点阐述了WiMax的组网方案,根据尽量对目前正使用网络兼容和补充的原则,提出了WiMax组网分3个阶段进行的策略,并且给出了每阶段的详细组网方案。     

无线城市组网及运营模式的探讨

无线城市是近年来兴起的城市信息化发展热点,本丈分析了建设无线城市的意义和条件．重点讨论了无线城市的组网方式．从建设主体和业务模式两个角度探讨了无线城市的运营模式,为无线城市建设提供了发展思路。