基于分层代理的MIP方案研究

通过对移动蜂窝网络模型的分析,提出了一种基于IPv6协议的分层网络移动IP切换方案,利用网络层快速切换以及层管理域的适当选取,有效地减少了微移动中的切换时延;在域间切换中,引入对端通信节点与网络外部代理的直达路径,降低了三角路由对切换过程的影响。     

基于移动代理的MANET网络管理任务切换

由于自组网(Mobile Ad Hoc Network,MANET)网络的动态移动性,节点从一个网管域移动到新的网管域时,使用移动IP的网管任务切换可以解决异域网络的管理问题,但是由于在网管中,管理者和被管设备都在一个区域中,使用基于移动IP的网管任务切换就具有严重的三角路由问题。将移动代理与网络管理结合起来,提出一种新的网络管理任务切换方案,该方案节省了网络资源,减少了切换时延并降低了管理任务的丢失,同时增加了网络管理的灵活性。     

IP微移动的切换管理

IP微移动是一种能够在移动过程中有效改善移动节点通信质量的移动性管理方式,其核心部分为切换管理。该文首先分析了IP微移动的切换过程,并从网络层切换和链路层切换的关系及其交互性的新视角提出了切换管理的分类方法,详细分析和研究了目前典型的IP微移动协议的特点和存在的问题,并给出对这些协议的性能比较,最后讨论了IP微移动切换管理的未来研究方向。     

移动IP技术在超三代移动通信系统中的应用

阐述了B3G系统中的无缝移动技术，探讨了移动IP在网络切换、移动性管理等方面的策略及对QoS的影响，在分析比较MIPv6基本模型、分层模型和快速切换模型的基础上，提出基于QoS的移动代理扁平架构。     

蜂窝IP的原理及实现机制

移动IP是一种简单可扩展的全球移动解决方案,但是它不能实现快速无缝平滑的切换控制。第三代蜂窝系统中为IP业务提供了平滑移动支持但是网络设施复杂。蜂窝IP提供了第三种解决方案,它结合了前两者的优点,利用了蜂窝系统平滑切换特性、激活和空闲主机的定位管理体现了IP网络快速、灵活和可扩展的要求。     

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.     

分层多跳无线网中结合负载均衡的切换管理

该文主要研究分层多跳无线网络中的切换管理,提出一种新的用户切换管理算法和移动基站路由切换策略.在网络动态变化时,用户切换管理算法可以减少用户的切换次数,使用户负载分布均匀.移动基站路由切换策略则尽可能地从基站本地找出替代路由,可以在较小的开销下达到快速和无缝切换的目的.     

基于位置信息的IP层切换判决机制及性能分析

基于IP的移动性管理技术使得移动终端可以在互联网间漫游，并且不会改变自己的IP地址．当同时存在多种类型无线网络的时候，如何选择最佳的候选网络，何时发起切换等切换判决问题也是提高基于IP的移动性管理性能的重要课题．提出了一种基于位置信息的切换判决算法，使得终端在对自身移动模型预测的基础上，做出正确的切换目标和切换时间的选择，从理论分析和仿真结果可以看出，该算法明显减小了切换次数和丢包率，提高了切换的性能．     

基于IPv6的快速切换改进方案

在移动IP网络中,当前的移动性管理方案由于其基本协议的切换时延较大、丢包率较高而不能适应实时业务和移动通信的要求,所以需要改善移动性管理策略的切换性能,尽量实现无缝切换和零丢包率。提出了一种基于移动IPv6的快速切换的改进方案,采用一种新的地址分配方式使得移动节点能够在移动至新的网络后迅速获取新的转交地址,有效地减少了切换所产生的时延和丢包率,具有较好的切换性能。     

WiMAX跨层切换技术的研究与仿真

介绍了在移动WiMAX网络中引入IP层移动性管理协议FMIPv6来支持以全IP网络为核心网的语音、视频等多媒体实时业务,并将它与IEEE802.21工作组提出的草案MIH(Media Independent Handover)相结合,设计出一种跨层切换方案,并通过NS-2仿真工具对网络间的切换时延和丢包率进行仿真分析和比较,验证了方案的可用性和良好性能.     

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。     

Handoff Performance Improvement with Latency Reduction in Next Generation Wireless Networks

The next generation (NG) wireless networks are expected to provide mobile users with the real-time multimedia services. High sensitivity to time constraints like delay and jitter is one of the important characteristics of the multimedia traffic. In order to maintain a certain quality of service (QoS) level, the handoff latency should be minimized. Furthermore, if the new cell is not ready at the actual handoff time, the handoff call may be even forced terminated. Hence, the handoff preparation latency directly affects the performance of the cellular networks in terms of QoS support and the handoff blocking probability. In this paper, we present the expected visitor list (EVL) method to achieve reduced handoff blocking probability and maintain a certain QoS level in the network by minimizing handoff preparation latency. The handoff signaling decomposition is introduced to make the neighbor cells aware of the resource demands and QoS requirements of the mobile terminal before the actual handoff time. The obtained information about the prospective active mobile terminal is stored in an EVL entry at the neighbor cells. The call admission control (CAC) with QoS-provisioning is run against each EVL entry. According to the CAC result, the network preparation algorithms are executed and the results are stored in the entry. No resource reservation or allocation is performed in advance, and the varying network conditions are reflected to validity and admission status of the entries. The results of handoff preparation algorithms stored in the EVL entry are activated at the actual handoff time and hence the handoff latency is minimized. Performance evaluation through mathematical analysis and extensive simulation experiments show that the EVL method reduces handoff latency and hence handoff call blocking probability significantly without introducing high overhead.Özgür B. Akan received the B.S. and M.S. degrees in electrical and electronics engineering from Bilkent University and Middle East Technical University, Ankara, Turkey, in 1999 and 2001, respectively. He received the Ph.D. degree in electrical and computer engineering from the Broadband and Wireless Networking Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, in 2004. He is currently an Assistant Professor with the Department of Electrical and Electronics Engineering, Middle East Technical University. His current research interests include sensor networks, next-generation wireless networks, and deep space communication networks.Buyurman Baykal received his B.Sc. (High Hons.) degree in Electrical and Electronics Engineering from Middle East Technical University in 1990; M.Sc. (Distinction) and Ph.D. degrees in 1992 and 1995 from Imperial College of Science, Technology and Medicine. Dr. Baykal has research and teaching interests in speech processing, signal processing for telecommunications, and communication networks. He has extensive experience both in the theory and applications of adaptive signal processing techniques to communication applications such as acoustic echo cancellation, noise reduction, channel equalization and digital receiver design through self-conducted research and industry-funded research projects. He conducts research and implementation work on low bit rate speech coding and content based indexing of audio signals. He is also involved in communication network research with particular interest in ATM/IP design aspects, wireless networks and network management issues. Dr. Baykal is an Associate Editor of Computer Networks (Elsevier Science), Sensor Letters (American Scientific Publishing), a past Associate Editor of the IEEE Transactions on Circuits and Systems Part II—Analog and Digital Signal Processing (TCAS-II). He authored and co-authored over 50 technical papers.     

移动IP无缝切换技术研究

移动IP协议是宏移动管理方案,但它不支持无缝切换.针对移动I P的不足,人们提出了许多改进方案来增强其性能.根据切换过程的技术特征,文章从基于缓存和转发机制的切换、基于减少组件延时的切换、基于上下文转移的切换和基于候选访问路由器发现策略的切换等角度,对增强移动IP性能的各种无缝切换技术进行了研究.     

Multicast Handoff Agent Mechanism for All-IP Mobile Network

This paper proposes a mechanism called a Multicast Handoff Agent (MHA) to reduce handoff latency for IP multicast. The MHA acts as a proxy for the Internet Group Management Protocol (IGMP) of mobile nodes and keeps information for members of multicast groups in a cell. When a mobile node moves to other cell, the MHA immediately sends unsolicited reports without waiting for the IGMP query. In addition, our mechanism may conserve battery power since it does not need to reply to a query.The mechanism is evaluated through simulation and analysis and compared with the IGMPv2 for mobility and IGMP traffic. Simulation results show that handoff latency can be largely reduced and the IGMP control traffic can be eliminated on the wireless links during the duration of membership.     

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.     

一种基于无线局域网的移动检测优化方案

无线局域网采用移动IP实现移动性管理.移动IP切换存在切换时延大,数据包易丢失的问题.切换时延由移动检测时延和注册时延组成,而移动检测时延在其中占主要部分.文章提出了一种移动检测优化方案,采用了自适应绑定的算法,同时充分考虑了域内小范围高频度切换的情况,使移动节点在无线局域网环境中进行快速有效的切换.     

An Empirical Analysis of Handoff Performance for SIP,Mobile IP,and SCTP Protocols

Over the last decade, we have witnessed a growing interest in the design and deployment of various network architectures and protocols aimed at supporting mobile users as they move across different types of networks. One of the goals of these emerging network solutions is to provide uninterrupted, seamless connectivity to mobile users giving them the ability to access information anywhere, anytime. Handoff management, an important component of mobility management, is crucial in enabling such seamless mobility across heterogeneous network infrastructures. In this work, we investigate the handoff performance of three of the most widely used mobility protocols namely, Mobile IP, Session Initiation Protocol (SIP), and Stream Control Transmission Protocol (SCTP). Our empirical handoff tests were executed on an actual heterogeneous network testbed consisting of wired, wireless local area, and cellular networks using performance metrics such as handoff delay and handoff signaling time. Our empirical results reveal that Mobile IP yields the highest handoff delay among the three mobility protocols. In addition, we also found that SIP and SCTP yield 33 and 55% lower handoff delays respectively compared to Mobile IP.     

IEEE 802.11 handoff latency improvement using Fuzzy Logic

Multimedia transmissions are delay‐sensitive Internet applications. Because mobile stations are in continual motion, handoff processes are necessary and unavoidable in wireless network environments. Because handoff processes tend to break the communication link, the research has been conducted on reducing the break time and arrival delay during Internet multimedia applications. In this paper, we propose an approach based on Fuzzy Logic to evaluate the average variation in signal strength received by a mobile station and produce a FitAP factor. This factor indicates the possible handoff access point that is suitable for the mobile station. According to the FitAP factor, a mobile station needs only to execute an active scan process once. Therefore, smaller handoff latency is expected. We compare the results from the current cell search scheme with that of the Fuzzy Logic approach. The statistical results show that the proposed method outperforms the current cell search scheme with an improved handoff latency performance. Copyright © 2007 John Wiley & Sons, Ltd.     

移动协议网络层切换时延分析

对移动协议网络层切换时延进行了研究。提出合适的网络模型,从理论上分析了各移动协议的路径更新时间,并采用数值仿真的方法对采用微观移动协议和只使用移动IP协议以及采用不同的微观移动协议的情形进行了比较。研究结果表明路径更新时间与所采用的移动协议的路径更新方法相关;采用微观移动协议时的路径更新时间远小于只使用移动IP协议时的情形;在所有的微观移动协议中,MIP-RR协议中使用的路径更新方法性能最佳。