集成移动IP的无线局域网

文章分析无线局域网的不足和应采取的相应对策,介绍集成移动IP无线局域网的基本体系结构,研究集成移动IP无线局域网的协议栈,提出新的子层———IP关口层,详细分析无线局域网在IP关口层和数据链路层对移动IP的支持。     

移动IP在无线局域网下的一种快速切换方法

针对移动IP在无线局域网下的应用,提出了一种新的基于链路层的移动IP快速切换方法,通过在无线局域网的无线接入点间加入特定的MAC网桥来减少移动节点在切换时产生的切换时延,进而减少移动节点上行和下行方向上的数据包的丢失,达到对移动IP切换进行优化的目的。此方法在无线局域网实际环境中进行了性能测试,结果证明优化后的时延较之原来普通移动IP切换时延有明显降低。     

一种基于MobiCast的移动IP组播方案

本文提出一种改进的MobiCast方案来实现移动IP组播通信,主要解决MobiCast方案中进行区域间切换时组播数据包丢失问题。与MobiCast方案相比,在区域外地代理(DomainForeignAgent,DFA)处引入一种缓存的机制。当移动节点发生区域间切换时,移动节点的旧区域外地代理采用隧道技术,将移动节点的信息和缓存的组播数据包发送给移动节点的新区域外地代理处,减少移动节点进行区域间切换时丢失的组播数据包。     

一种移动IPv6的切换优化方案

移动节点在两个不同子网之间移动时产生切换。移动节点的切换技术是保证实时业务服务质量的关键问题之一。目前比较经典的三种切换机制是快速移动IPv6、层次型移动IPv6和快速层次移动IPv6。在简单介绍了三种机制原理并分析了它们的不足后,提出了一种自适应移动IPv6切换时延优化方案。     

浅析无线局域网与GPRS互联的方案

本文介绍了WLAN和GPRS相互结合的两种方法,给出了它们各自的技术原理,并比较了这两种方法的优缺点。     

一种基于移动电源的电池电量检测方案的实现

本论文以移动电源芯片中的电池电量检测为核心,分析了目前这类芯片中检测电量的方式及其不足之处,并提出了一种性价比较高的检测设计方案,并对方案的优缺点进行阐述分析,并认为是一种设计相对容易,并能很好提高电池电量检测精度的设计方案。     

一种移动IP快速平滑切换方案

无线IP网络中将采用移动IP实现移动性管理,但该方案应用在高频度切换环境,存在不可接受的切换时延和数据包丢失,很难保证通信业务的服务质量.提出了一种移动IP快速平滑切换方案,该方案利用后注册切换的概念,在切换过程中不存在数据包的丢失,并可以获得很小的切换时延,在实际系统中运行能够达到良好的效果.     

一种分布式全IP无线接入网方案

提出一种独特的无线IP接入网结构。此结构突破了传统的接入网管理域概念,直接在最靠近无线传输点的基站控制器上为用户提供IP网络接入,构成分布式的全IP无线接入网。其支撑协议MPPP(MobilePoint-to-PointProtocol)可充分体现用户移动的个性特征,构成动态逻辑接入网管理域。提出的快速平滑切换可保证用户在大业务量、频繁高速移动中的无损IP业务。     

一种支持无线局域网IP移动性的体系

本首先介绍了在WLAN中引入基于代理服务器体系的动机。然后重点介绍了该体系支持IP移动性的工作机制，最后给出了结论。     

一种基于MPLS的无线接入网微移动方案

将MPLS技术应用到基于IP的无线接入网络是近年越来越受到关注的新课题.本文提出了一种基于MPLS的微移动方案,方案采用在基站进行缓冲的方法降低切换时的分组丢失.最后对方案的性能从算法所产生的网络开销、切换时延与分组丢失几个方面进行了分析和讨论,结果表明本方案适用于高速微蜂窝及微微蜂窝的移动通信环境,并能满足一般的数据及实时业务的需求.     

异构重叠网络下MIP移动检测方法性能比较

未来的通信网络将融合、协同多种异构网络。IETF提出的移动IP(MIP)能够将各种网络统一到单一的IP信息平台。本文重点分析了影响MIP切换时延的移动检测机制：LCS,ECS。提出了异构重叠网络下跨层优化快速检测机制。理论分析和仿真均表明由于得到了来自链路层信息的辅助,该方法能有效地降低切换时延,减少丢包,提高通信服务质量。     

A Layer 3 Movement Detection Algorithm Driving Handovers in Mobile IP

The evolution and the spreading of wireless access technology and the consequent increase of user mobility will make handover procedures critical for the provision of Quality of Service in the next generation wireless Internet. Often, layer 3 handovers are supposed to be driven by access layer procedures. In this way, the movement detection delay can be reduced, but at the expenses of making the Mobile IP protocol dependent of lower layer implementations. Furthermore, this approach may not be effective when users roam among heterogeneous networks. Nevertheless, movement detection algorithms, which operate at the Mobile IP layer, imply appreciable delays, usually intolerable for real time services.In this paper, we propose a Mobile IP handover scheme based on a novel movement detection algorithm at layer 3, able to timely manage migrations by exploiting advertisements losses, combined with a two-timers mechanism.We analyze the performance of our algorithm in terms of handover delay and throughput, and we show that our solution is able to decrease the movement detection delay as much as 47% with respect to other literature solutions that pursue similar approaches. In addition, this feature implies also higher values of the throughput seen by the TCP layer.This work has been carried out in the framework of the FIRB Project PRIMO, co-financed by the Italian Ministry for Education, Higher Education and Research (MIUR).Nicola Blefari Melazzi received his Laurea degree in Electrical Engineering in 1989, magna cum laude with publication of his thesis, and earned the Dottore di Ricerca (Ph.D.) in Information and Communication Engineering in 1994, both at the University of Roma La Sapienza, Italy. In 1993 he joined the University of Roma Tor Vergata, as an Assistant Professor. From 1998 to 2002 he has been an Associate Professor at the University of Perugia. In 2002 he came back to the University of Roma Tor Vergata as a Full Professor of Telecommunications.Dr. Blefari-Melazzi has been involved in consulting activities and research projects, including standardization and performance evaluation work. His research projects have been funded by the Italian Ministry of Education, University and Research, by the Italian National Research Council, by industries, by the European Union and by the European Space Agency. He also reviewed research proposals and research projects.Dr. Blefari-Melazzi served as reviewer, TPC member, session chair and guest-editor to IEEE conferences and journals.His research interests include the performance evaluation, design and control of broadband integrated networks, wireless LANs and satellite networks. He is also conducting research on multimedia traffic modeling, mobile and personal communications, quality of service guarantees and real time services support in the Internet.Mauro Femminella received his Laurea degree in Electronic Engineering in 1999, magna cum laude with publication of his thesis, and earned the Ph.D. degree in Electronic Engineering in 2003, both at the University of Perugia, Italy. He was Consulting Engineer for the University of Perugia, and for the consortia CoRiTel and RadioLabs. Actually he holds a position as contract researcher at the Department of Information and Electronic Engineering at the University of Perugia.He was involved in a number of research projects co-funded by the European Union (programs ACTS and IST), by the Italian Ministry for Education, Higher Education and Research (MIUR), and by the European Space Agency (ESA).He is co-author of a number of papers in international conferences and journals.His research interests focus on design and performance evaluation of satellite networks, content delivery networks, IP quality of service and IP mobility.Fabio Pugini received his laurea degree (M.S.) in Electronic Engineering (magna cum laude) in 2000 from University of Rome La Sapienza. He was with the INFOCOM Dept. of the same University during 2001 and 2002 as Ph.D. student in Computer Science. His main research interests regarded Mobility issues and QoS provision in IP networks. He was consulting engineer for the DIEI Department of the University of Perugia and was involved in the following European Projects: SUITED, WHYLESS.COM, FIFTH. In 2002 he received his M.B.A. degree from University of Rome Tor Vergata. He worked as a system analyst in MBDA Missile Defense Systems and currently he is with McKinsey & Company as a Junior Associate.     

一种新的WLAN环境下移动IPv6的低时延切换方法

提出了一种IEEE 802.11无线局域网环境下移动IPv6的低时延切换方法NDPR.在不依靠链路层触发的条件下,NDPR使用非均匀检测模型来减小切换检测产生的时延,降低了切换检测过程的开销.通过IP地址与MAC地址的映射机制和转交地址的预注册机制,NDPR减小了移动IPv6的移动检测和转交地址配置过程的时延.仿真结果表明,该方法不但能够有效降低节点切换过程的时延,而且其性能优于以往相关的工作.     

A New ARQ Scheme for Reliable Broadcasting in Wireless LANs

This paper proposes a new automatic repeat request (ARQ) scheme for reliable broadcasting in distributed wireless LANs. Unlike traditional ARQ schemes for reliable broadcasting, the proposed scheme is highly efficient in its ARQ control information delivery and only introduces light control overhead in the network. Our simulation results show that as compared with traditional ARQ schemes, the proposed scheme improves the LAN throughput by from several tens to more than one hundred percent, depending on the number of nodes in the LAN.     

Efficient Symbol Detection for OFDM-Based Wireless LANs with Space-Frequency Transmit Diversity Scheme

In this letter, we propose two efficient symbol detection algorithms for OFDM-based wireless LANs with space-frequency transmit diversity (SF-TD) scheme. In case that SF-TD scheme is applied to OFDM-based wireless LANs, the interference caused by insufficient number of sub-carriers may be generated between adjacent sub-carriers, and it degrades the overall system performance seriously. The proposed algorithms eliminate this interference in a parallel or sequential manner and achieve a considerable performance improvement over a conventional detection algorithm     

A New Scheme to Avoid Collisions for Broadcast Packets in Wireless LANs

This paper proposes a new approach to avoiding collisions for broadcast packets in distributed wireless LANs. The basic idea is to use in-band pulses to convey the medium access control information for broadcast packets. The new approach extends the basic functionality of the IEEE 802.11 distributed coordination function (DCF) from the unicast case to the broadcast case and significantly improves the broadcasting efficiency in wireless LANs.     

一种新的基于移动IPv6的快速切换方案

基本的移动IPv6（MIPv6）切换延迟非常大,不能满足实时业务的要求。本文基于对MIPv6的切换时延的分析,提出了一种IEEE802．11无线局域网环境下MIPv6的低时延切换方法,该方法通过结合使用连接触发器和快速路由器公告,并通过IP地址与MAC地址的映射机制来优化切换过程。仿真结果表明,该方法能够有效降低节点切换过程的时延,同时其性能优于以往相关的工作。     

DAWL: A Delayed-ACK Scheme for MAC-Level Performance Enhancement of Wireless LANs

The IEEE 802.11 MAC protocol provides a reliable link layer using Stop & Wait ARQ. The cost for high reliability is the overhead due to acknowledgement packets in the direction opposite to the actual data flow. In this paper, the design of a new protocol as an enhancement of IEEE 802.11 is proposed, with the aim of reducing supplementary traffic overhead and increasing the bandwidth available for actual data transmission. The performance of the proposed protocol is evaluated through comparison with IEEE 802.11 as well as with a SSCOP-based protocol. Results underline significant advantages of the proposed protocol against existing ones, thus confirming the value and potentiality of the approach.Dzmitry Kliazovich received his Masters degree in telecommunication science from Belarusian State University of Informatics and Radioelectronics in 2002. He is currently working towards the Ph.D. degree in University of Trento, Italy. His main research interest lies in wireless networking field with a focus on performance optimization and cross-layer design.Fabrizio Granelli was born in Genoa in 1972. He received the “Laurea” (M.Sc.) degree in Electronic Engineering from the University of Genoa, Italy, in 1997, with a thesis on video coding, awarded with the TELECOM Italy prize, and the Ph.D. degree in Electronic Engineering and Computer Science from the same university in 2001. Since 2000 he is carrying on his teaching activity as Assistant Professor at the Dept. of Information and Communication Technologies (DIT) of the University of Trento (Italy) within the B.Sc. and M.Sc. Degrees in Telecommunications Engineering.The research interests of Dr. Granelli are mainly focused on networking, with particular attention to network modeling and performance evaluation, wireless networks, access control, and next-generation telecommunication networks.He is author of more than 30 refereed papers, published in several international journals and conferences.Dr. Granelli is member of the IEEE Committee on “Communication Systems Integration and Modeling” (CSIM) and of the Technical Programme Committee of the “QoS and Performance Evaluation Symposium” of the International Conference on Communications (ICC 2003 and ICC 2004).     

Novel Sequence Number Based Secure Authentication Scheme for Wireless LANs

Authentication per frame is an implicit necessity for security in wireless local area networks (WLANs). We propose a novel per frame secure authentication scheme which provides authentication to data f...