基于无线Mesh网络技术构建无线城市

无线Mesh网络(WMN)可以和多种无线网络系统,如无线局域网(WLAN)、无线城域网(WMAN)等相结合,改善无线网络的性能,提高网络的覆盖范围.以WMN网络技术在IEEE 802系列标准中的发展为基础,提出了一种无线城市的覆盖方案,最底层网络覆盖采用WiFi+wireless Mesh技术,WiMAX网络与WiFi...     

Use of wireless system in healthcare for developing countries

Healthcare is one of the major applications of wireless systems that possess crucial issues. Specifically developing countries require a low cost and reliable network with efficient protocols. The most challenging concern of Body Area Network (BAN) is heterogeneity, which requires fairness with reliability among all the network nodes. Solutions proposed for these networks either do not provide fair packet transmission or consume high energy and introduce delays. In this paper, we propose a cross layer protocol for healthcare applications meeting the requirements and challenges of the heterogeneous BAN. The protocol is also feasible for developing countries as it can be implemented over existing wireless infrastructure and provides high network reliability with energy efficiency through cooperation and adaptability. Results show that the proposed scheme improves reliability, throughput, Packet Delivery Ratio (PDR), and energy consumption for scalable and mobile networks over conventional BAN protocols.     

基于网络处理器的RPR综合业务接入平台的设计

弹性分组环(RPR)是一种新的城域网技术,文章提出了用网络处理器IXP1 200构建RPR综合业务接入平台的设计方案,并重点讲述了其中微引擎部分的软件设计.     

Real-time support in multihop wireless networks

Personal communications and mobile computing will require a wireless network infrastructure which is fast deployable, possibly multihop, and capable of multimedia service support. The first infrastructure of this type was the Packet Radio Network (PRNET), developed in the 70's to address the battlefield and disaster recovery communication requirements. PRNET was totally asynchronous and was based on a completely distributed architecture. It handled datagram traffic reasonably well, but did not offer efficient multimedia support. Recently, under the WAMIS (Wireless Adaptive Mobile Information Systems) and Glomo ARPA programs several mobile, multimedia, multihop (M³) wireless network architectures have been developed, which assume some form of synchronous, time division infrastructure. The synchronous time frame leads to efficient multimedia support implementations. However, it introduces more complexity and is less robust in the face of mobility and channel fading. In this paper, we examine the impact of synchronization on wireless M³ network performance. First, we introduce MACA/PR, an asynchronous network based on the collision avoidance MAC scheme employed in the IEEE 802.11 standard. Then, we evaluate and compare several wireless packet networks ranging from the totally asynchronous PRNET to the synchronized cluster TDMA network. We examine the tradeoffs between time synchronization and performance in various traffic and mobility environments.     

Mobile IP-DECT internetworking architecture supporting IMT-2000applications

Realistic realization and mass acceptance of mobile data services require networking architectures offering acceptable quality of service and attractive tariffs. A novel strategy for this goal is maximum integration of popular data networking standards and their infrastructure into wireless networks. This article discusses a Mobile IP-based network architecture to provide IP services in DECT to support IMT-2000 applications. DECT offers micromobility within multicell subnets, while Mobile IP supports macromobility between multicell subnets. Incorporating Mobile IP into the DECT handoff mechanism in this way extends DECT micromobility with IP macromobility. Also, utilizing fast, seamless DECT handoff management reduces Mobile IP handoff delay to circumvent TCP throughput degradation during handoff and reduce frequency of Mobile IP signaling over the ether to conserve spectral efficiency. This feature seamlessly unifies DECT with the global Internet. Seamless integration of DECT with the Internet is crucial due to the continuing phenomenal popularity of the Internet and wireless communications, and ubiquity of DECT systems. To achieve the above DECT/IP interworking efficiently, the architecture introduces a network entity called a DECT service switching point, which is an extended DECT central control fixed part. DECT network-level services are mapped onto those of the IETF integrated services architecture to maintain QoS provided by DECT in the backbone Internet. Mobile Resource Reservation Protocol, an extended RSVP tailored to mobile networking, is adopted to provide the needed signaling in IntServ. The proposed architecture preserves traditional non-IP based services such as PSTN voice     

RPR技术及其QoS分析

弹性分组环(RPR)是目前在城域网中进行数据传输的一种新的传输技术。网络的服务质量(QoS)是下一代IP光因特网中一个很重要的问题。RPR作为一种新的光传输技术,必须支持QoS。基于此,主要介绍了RPR网络特点,并回顾和总结了已有的RPR网络QoS方案。最后,提出了MPLSoverRPR的QoS方案。     

An architectural framework for seamless handoff between IEEE 802.11 and UMTS networks

In recent years, Cellular wireless technologies like GPRS, UMTS, CDMA and Wireless Local Area Network (WLAN) technologies like IEEE 802.11 have seen a quantum leap in their growth. Cellular technologies can provide data services over a wide area, but with lower data rates. WLAN technologies offer higher data rates, but over smaller areas, popularly known as ‘Hot Spots’. The demand for an ubiquitous data service can be fulfilled, if it is possible for the end-user to seamlessly roam between these heterogeneous technologies. In this paper, a novel framework is proposed consisting of intra-ISP network called ‘Intermediate Switching Network’(ISN) fused between UMTS and WLAN networks as well as data (Internet) services for providing seamless mobility without affecting user’s activities. The ISN uses MPLS and Multiprotocol-BGP to switch the data traffic between UMTS to IEEE 802.11 networks, as per the movements of the user. The ISN is integrated with the UMTS network at the GGSN-3G and at the Access Point for IEEE 802.11 network respectively. The simulation result shows the improved performance of the ISN based framework over existing schemes.     

Analysis of a contention resolution multiple-access algorithm for handling mixed traffic on wireless networks

Existing wireless standards, like DECT and GSM, are based on TDMA. Packet multiple-access algorithms perform statistical multiplexing, leading to greater efficiency than basic TDMA which assigns a fixed amount of channel resources to each user. Moreover, these methods permit one to handle in a more flexible way different kinds of information. Most of the proposed packet access methods, applied to radio networks, are based on slotted ALOHA algorithms. We propose a methodology for applying packet contention resolution multiple-access techniques to wireless networks. The proposed techniques are able to handle the access of mixed traffic types. We define and analyze a multiple-access algorithm for handling the access of a mixed set of users, including a group of speech users and a population of users that generate a random traffic approximated by a stream of Poisson.     

中国联通兴安盟分公司IP城域网网络优化成果

IP城域网主要承载互联网访问业务,随着网络IP化、业务IP化趋势的加剧,在IP城域网上部署传统的数据业务已经不能满足市场要求,而当一些新型的电信业务,如NGN、3G、IPTV等需要通过IP城域网承载时,现有城域网又无法完成对上述业务的承载工作,这就需要运营商对城域网进行相应的优化改造。本文分析了当前兴安盟联通分公司IP城域网存在的主要问题,探讨了IP城域网优化改造的策略,并针对兴安盟联通分公司IP城域网的实际情况,提出了IP城域网网络优化改造的具体方案。     

An adaptive load-aware routing algorithm for multi-interface wireless mesh networks

In wireless mesh networks, the number of gateway nodes are limited, when the nodes access to the internet by fixed gateway node, different requirements of nodes lead to the dataflow shows heterogeneity. Many new routing metrics and algorithms existing in traditional wired networks and the Ad Hoc network, can not be directly applied to wireless mesh networks, so how to design a routing metric and algorithm which can dynamically adapt to current networks topology and dataflow changes, avoid bottleneck node, and select the most stable and least congestion link to establish a route is very important. In this paper, we presented a new dynamic adaptive channel load-aware metric (LAM) to solve the link load imbalance caused by inter-flow and inner-flow interference, designed a self-adaptive dynamic load balancing on-demand routing algorithm through extending and improving AODV routing method with the LAM, to achieve flow balance, reduce the high packet loss ratio and latency because congestion and Packet retransmission, and can increase Network Throughput.     

用于光城域网的新型RPR技术

介绍IEEE802.17正在进行标准化的弹性分组环(RPR,Resilient Packet Ring)协议,分析其帧结构及主要功能特色,并和SDH与以太网等现有城域网技术作简要对比;可以预见,随着标准化工作的进行,综合多种传输技术优势的RPR会成为创建下一代高速光城域网的首选技术。     

MSTP的新业务及其应用

城域网正在从单纯的传送网向业务网演进,需要新的传送平台的支持.文章分析了基于SDH平台的多业务传送平台(MSTP)提供新业务的原理,并介绍了MSTP上的各种应用,认为融合虚容器(VC)级联、链路容量调整(LCAS)和通用成帧规程(GFP)等相关技术的多业务传送平台(MSTP),可以实现多种业务的综合接入和汇聚;由于MSTP可以内嵌弹性分组环(RPR)、多协议标签交换(MPLS)等技术,因此可以支持如虚拟专用网(VPN)和按需带宽(BoD)等新业务,并适应未来3G业务的发展.     

无线传感器网络与自组织网络的研究现状

传感器网络综合了传感器技术、嵌入式计算技术、分布式信息处理技术和无线通信技术,是计算机科学技术的一个新的研究领域;自组织网络是一种移动、多跳、自律式系统,两者均具有十分广阔的应用前景.文章对传感器网络和自组织网络的概念、特征和发展动态等问题进行了介绍,重点分析了目前这两种网络的关键技术和研究现状.文章认为:传感器网络在特殊领域有着传统技术不可比拟的优势,而无线自组织网络通过临时组网的方式在恶劣环境中支持移动节点之间的无线传输,应用范围广阔.对这些网络的研究是中国未来高技术民用和军事发展的需要.     

利用分组交换网组建金融POS网

首先介绍了当前利用电话网组建的 POS (Point of Sales,销售点终端 )网 ,然后针对该组网方式的缺点 ,分析了用 X.2 5网传送 POS交易数据的优越性 ,提出了一种利用 POSPAD设备 (POS接入公用分组交换网的设备 )通过公用分组交换网组建 POS网的方案。     

无线网格网关键技术及其应用

无线网格网(WirelessMeshNetwork,WMN)是一种新型的无线宽带接入网络,它融合了无线局域网(WirelessLAN,WLAN)和AdHoc网络的优势,是一种大容量、高速率、覆盖范围广的网络,成为宽带接入的一种有效手段。本文主要介绍了无线网格网的研究现状、结构、关键技术以及与其他通信网络的区别,最后介绍了两种无线网格网的技术方案以及应用前景。     

Operations and management of a campus packet network

The operation and management of the Kansas University Packet Switch Network (KUPSN),which provides interactive and file transfer services to its users, is discussed, focussing on the problems encountered and solutions developed. Areas of network management of particular concern are identified, and tools developed to deal with them are described. Management system integration and the evolution of problem-handling procedures are discussed     

Wireless Mesh Network and IEEE 802 Standards

Although the wireless broadband access system is developing rapidly, its development is limited due to some disadvantages , such as small capacity of bandwidth and small coverage . The Wireless Mesh Network (WMN) is one of the important technologies for "last mile "broadband wireless access . The WMN can integrate with multiple wireless systems , such as Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN), and Wireless Metropolitan Area Network (WMAN), to improve the performance of the wireless network and enlarge the coverage range . With the wide applications of the WMN, the IEEE 802 standard group is devoted to promoting the development of the WMN technology and establishing the related technical standards . At present, WMN standards have appeared in IEEE 802.11s , 802.15, 802.16, and 802.20.     

基于RPR的高生存性网络

弹性分组环(RPR)技术定义了一种新型的媒体接入控制(MAC)层协议,采用了共享介质传输和空间复用协议以及低于50 ms的故障恢复保护的弹性机制,支持服务等级协定(SLA,Service Level Agreement),即插即用,基于MAC的高速交换,可承载具有突发性的IP业务,同时支持传统的语音传送,是未来城域网技术的重要发展方向.光纤技术的飞速发展使得RPR不再仅仅局限于城域网,还可以用于广域网.文章在基于RPR的低于50 ms的故障恢复保护的基础上,提出了具有高生存性的解决方案.     

基于 Linux 开源软件的广电核心承载网监控平台的开发与应用

以基于Linux开源软件的广电核心承载网监控平台的开发案例为基础,对IP城域网流控系统架构进行了探讨,结合广电IP城域网的实际网络特性,提出核心承载网监控平台的部署方案,并系统地介绍了该核心承载网监控平台的开发、部署以及实际应用情况。     

Performance Evaluation of Routing Protocols for Ad Hoc Wireless Networks

A mobile ad hoc network is a collection of autonomous mobile nodes that communicate with each other over wireless links. Such networks are expected to play an increasingly important role in future civilian and military settings, being useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable and movement of communicating parties is possible. However, since there is no stationary infrastructure such as base stations, mobile hosts need to operate as routers in order to maintain the information about the network connectivity. Therefore, a number of routing protocols have been proposed for ad hoc wireless networks. In this paper, we study and compare the performance of the following routing protocols AODV, PAODV (preemptive AODV), CBRP, DSR, and DSDV. A variety of workload and scenarios, as characterized by mobility, load and size of the ad hoc network were simulated. Our results indicate that despite its improvement in reducing route request packets, CBRP has a higher overhead than DSR because of its periodic hello messages while AODV's end-to-end packet delay is the shortest when compared to DSR and CBRP. PAODV has shown little improvements over AODV.