Optimizing throughput performance of FMIPv6 over legacy 802.11 networks using iterative scanning

Predictive handover protocols like FMIPv6 have been proposed to provide seamless handover to MNs with minimum handover latency and packet losses. An essential prerequisite of FMIPv6 protocol is the advance discovery of candidate access points while the MN is still connected to its Present Access Router, a process which is carried out by the underlying data link layer protocol. The FMIPv6 standard only specifies the seamless handover operation at the network layer and does not take into consideration the impact of the relevant mechanism, such as the advance access point discovery process, on the overall seamless operation in terms of packet losses. At the data-link layer, the MN may repeatedly preform channel scanning operations to discover the in-range candidate APs. During the scan process, a MN is unable to transmit or receive packets leading to service quality degradation.This paper will analyze the implication of the IEEE 802.11 scanning process, that is carried out in advance to the actual initiation of the FMIPv6 handover process as part of the candidate access points discovery process. The impact of such a scan process is assessed on the overall seamlessness of the FMIPv6 protocol and its impact on the user’s QoE. In this regard, an iterative channel scanning solution approach would be described, which has been proposed to offset the adverse affects of 802.11 channel scanning process on the overall seamlessness of the FMIPv6 protocol in a legacy 802.11 network, especially during the candidate AP discovery process. A detailed evaluation of the performance of our proposed scheme will be presented based on extensive simulation analysis.     

Optimized fast handover scheme in Mobile IPv6 networks to support mobile users for cloud computing

In the future cloud computing, users will heavily use mobile devices. Mobile networks for cloud computing should be managed efficiently as well as support seamless services to mobile users regardless of their locations and movements. Hence, in mobile networks for cloud computing, it is important to support seamless mobility management to mobile users who request real-time services such as VoIP, streaming, and interactive game playing. To support seamless mobility management for various wireless technologies in cloud computing, Mobile IPv6 (MIPv6) and fast handovers for MIPv6 (FMIPv6) have been studied. FMIPv6 has been emerged to reduce long handover latency and packet loss in MIPv6. FMIPv6 may provide seamless handover by minimizing the handover latency, and prevent packet loss through buffering and tunneling. FMIPv6 uses anticipation based on layer 2 trigger information, and consists of two operation modes such as the predictive mode and the reactive mode. Several works have been done to evaluate the performance of FMIPv6 in different network environments. However, the previous works did not consider the probability of predictive mode failure (PPMF) that distinguishes two operation modes. Even in the most previous work, two operation modes of FMIPv6 are evaluated separately. However, to accurately analyze the overall performance of FMIPv6, two operation modes should be analyzed altogether. In this paper, FMIPv6 combining two operation modes is analyzed considering the PPMF that is affected by the radius of a cell, velocity of mobile nodes, and the layer 2 triggering time. The effect of system parameters, such as the PPMF, the time required to process additional layer 3 signaling, and the layer 2 trigger time, is analytically investigated with respect to the signaling cost and the packet delivery cost. Analytical results show a trade-off between performance and system parameters. Then we show methods to optimize overhead of FMIPv6. Finally, mobile networks for cloud computing can be efficiently managed through the optimized FMIPv6.     

移动WiMAX网络中跨层快速切换的研究*

针对移动WiMAX网络中,基于FMIPv6和DAD (duplicate address detection)机制的快速切换存在着开销大和检测时延长的问题,提出了一种跨层快速切换的策略。新策略在FMIPv6基础上,使用了mSCTP协议和ODAD (optimistic DAD)机制,成功地消除了FMIPv6协议中建立隧道的开销和减少了DAD地址检测的时延。仿真结果显示,新的切换策略将切换时延和分组丢失分别降低了65%和60%。     

基于Delaunay三角剖分的FMIPv6快速切换机制

针对快速移动IPv6（FMIPv6)中预测新接入路由器(NAR) 出错时的丢包问题,提出了一种基于Delaunay三角剖分的快速切换机制(TFMIPv6)。该机制通过Delaunay三角剖分算法将网络分割成虚拟的三角拓扑结构,在相邻的接入路由器间建立隧道,通过目标接入节点候选表来协助移动节点快速重构两个新的转交地址,并将切换过程中到达的包缓存在两个可能的NAR中。仿真结果表明,TFMIPv6能获得比FMIPv6更小的切换延时及丢包率。     

动态的基于快速切换的层次型移动组播协议*

为了提高移动IPv6网络中组播的服务质量,提出一种动态的基于快速切换的层次型移动组播协议——DFHMM。协议设置两级组播代理,对外屏蔽节点的域内切换;利用移动锚点担当区域组播移动代理,提供配置的高灵活性和通信的强鲁棒性;使用基于链路层触发的快速切换机制,缩短组播服务的中断时间。给出了协议的体系结构、切换流程、数据结构和操作细节。     

移动环境下源特定的IP组播实现机制

移动IP和IP组播技术是下一代网络中的热点研究问题。如何将这两者结合起来,为移动节点提供有效的组播支持,已经引起了很多人的兴趣。但是,由于设计移动组播路由协议时遇到诸多的困难,比如处理组播源的切换问题,研究工作进展非常缓慢。详细讨论了各种在移动环境下源特定的组播实现机制,自身所具有的优点和存在的不足,并综合对比了它们的主要性能。希望通过这种系统的讨论,能够帮助大家在以后的研究中更好地把握住发展方向。     

移动IPv6协议的切换时延性能比较分析

移动IPv6中的切换时延对于特定网络情景中的性能起着很大的作用,它会导致数据包的丢失和严重的端对端性能下降,文章对移动IPv6中的各种协议的切换时延作了性能分析比较,介绍了移动IPv6的基本知识及快速切换的重要性,阐述了层次化移动IPv6和快速移动IPv6的工作原理,采用网络仿真工具NS-2对三种移动IPv6协议的切换性能进行了比较和仿真,实验结果表明快速移动MIPv6具有良好的性能。     

基于PMIPv6协议的QoS上下文转移方案

在IETF的NetLMM（Network-based Localized Mobility Management）工作组中,Proxy Mobile IPv6（PMIPv6）由于不需要移动节点对IP移动性的支持而引起人们的关注。基于PMIPv6框架,提出一种新的QoS上下文转移解决方案。它的优点是在移动节点执行切换的同时为实时应用提供服务质量保证。采用这种方法可以减少移动节点切换后重新发起信令建立QoS转发处理所带来的延时,减少了移动节点会话的QoS服务中断。理论分析和仿真实验表明,本方案可以显著降低实时业务切换时的延迟和开销,并且有较低的丢包率,实现了移动节点的平滑切换。     

基于混合应答机制的层次型可靠移动组播算法

由于移动主机位置的不断改变引起组播树的频繁重构,已有的可靠组播算法已不适用于主机移动的无线网络环境.首先提出了前向网络签署的移动组播机制,然后在基于区域的层次型网络结构中,集成前向网络签署和远程签署,采用ACK和NAK相结合的应答机制,在子网局部范围内使用组播恢复机制和应答抑制机制,提出了一个新的支持主机移动的可靠移动组播算法.在重传延迟、重传开销、协议开销和服务中断时间这些方面的模拟结果和分析显示,该算法是一个高效的、可扩展的可靠移动组播算法.     

An enhanced framework for providing multimedia broadcast/multicast service over heterogeneous networks

Multimedia broadcast multicast service （MBMS） with inherently low requirement for network resources has been proposed as a candidate solution for using such resources in a more efficient manner. On the other hand, the Next Generation Mobile Network （NGMN） combines multiple radio access technologies （RATs） to optimize overall network performance. Handover performance is becoming a vital indicator of the quality experience of mobile user equipment （UE）. In contrast to the conventional vertical handover issue, the problem we are facing is how to seamlessly transmit broadcast/multicast sessions among heterogeneous networks. In this paper, we propose a new network entity, media independent broadcast multicast service center （MIBM-SC）, to provide seamless handover for broadcast/multicast sessions over heterogeneous networks, by extensions and enhancements of MBMS and media independent information service （MIIS） architectures. Additionally, a network selection scheme and a cell transmission mode selection scheme are proposed for selecting the best target network and best transmission mode. Both schemes are based on a load-aware network capacity estimation algorithm. Simulation results show that the pro- posed approach has the capability to provide MBMS over heterogeneous networks, with improved handover performance in terms of packet loss rate, throughput, handover delay, cell load, bandwidth usage, and the peak signal-to-noise ratio （PSNR）.     

MIPv6与FMIPv6切换性能分析与优化

随着移动通信的迅速发展,越来越多的移动设备提出了接入互联网的需求。移动IPv6的切换性能是保证移动互联网服务质量的重要因素之一。该文描述了MIPv6及FMIPv6的切换流程,分析了MIPv6及FMIPv6的切换性能及其切换过程中存在的问题,提出和归纳了一些优化思想和改进方法。     

基于上下文传输的FMIPv6安全快速切换机制

提出了一种基于上下文传输的FMIPv6安全快速切换机制。使用上下文传输协议传送移动节点MN的身份认证信息,是新接入网络在家乡网络不参与的情况下快速认证MN。并采用签名证书和对称密钥机制实现上下文传输的安全性和可靠性。文章通过安全性分析,说明此方法的安全性和可行性。     

HMRSVP：层次化移动资源预留协议

本文提出了一种新的资源预留协议--移动资源预留协议（HMRSVP）。此协议建立在层次化移动IPv6（HMIPv6）框架与快速切换技术（FHMIPv6）基础之上。此协议能够让移动节点在进行子网间切换的时候获得更加平滑的切换性能。同时，本文还和现有基于HMIPv6和FHMIPv6的IntServ方案进行了性能比较分析。     

移动IPv6的切换优化方案

移动节点在两个子网之间移动时将产生切换,而基本的移动IPv6切换延迟太大,不能满足实时业务的要求,因此IETF提出了移动IPv6快速切换协议.本文对移动IPv6的切换原理和性能进行了分析,对目前快速移动IPv6和层次移动IPv6切换进行了比较,并提出快速层次移动IPv6的切换方案,减小移动IPv6的切换时延,提高网络性能.     

移动家乡代理接入死锁的解决方法

针对网络移动由于家乡代理位于移动网络或本身就是移动路由器而可能出现的接入死锁问题,提出基于接入路由器树状模型和基于树根节点配置移动路由器转交地址的死锁解决方案。分析结果表明,该方案在保障移动网络节点和Internet上任意节点会话连续性的同时,实现了浮动嵌套移动网络节点之间的相互可访问性,而且通信延时、数据包包头损耗率以及网络切换延时与网络移动基本支持协议和返回路由头路由优化方案相比大大减小,嵌套层次越深,端到端通信节省的时间和空间开销越大。     

一种基于HIP的移动性管理机制

主机标识协议（Host Identity Protocol,HIP）是一种综合解决主机移动、多宿主及安全问题的有效方案,为了解决现有HIP机制在处理主机移动时存在切换延迟大、丢包率高等问题,提出了一种高效的基于HIP的移动性管理机制。该机制在基于HIP的层次化设计模型基础上,采用FMIPv6中的快速切换思想,引入了链路层触发机制、预先绑定更新机制和分组缓存转发机制。有效解决了移动主机在不同区域范围内的切换问题,降低了切换延迟和丢包率,改善了移动主机的切换性能,实现了透明、平滑、快速的网络切换。     

基于邻居信息交换的组播快速切换算法

切换延迟和丢包率是决定移动组播算法是否能够满足实时性组播应用要求的重要指标.提出了一种基于邻居信息交换的组播快速切换算法M-FMIPv6/NIE.在二层触发器事件发生之前,通过邻居接入路由器之间定时的信息交换,可以提前进行新转交地址的配置和请求加入组播树等操作.性能分析和仿真结果表明,M-FMIPv6/NIE的组播服务中断时间小于现有的组播快速切换算法,并且在缓存数量和丢包率等方面也具有较佳的性能.     

An approach to support IP multicasting in networks with mobile hosts

It is an efficient way for a mobile host to obtain multicast service via a local multicast router on the visited network.However,there is a possibility for a temporary disruption of multicast service due to the join latency and other issues in handoff procedure.This paper proposes a scheme to solve such a problem. A smooth handoff mechanism is introduced to avoid unnecessary data loss.Besides,any mobility agent capable of multicast can be appointed to provide service to mobile hosts,which makes it possible to deploy the protocol widely.Discrete-event simulations were conducted to survey the performance of the proposed scheme.The simulation results show that the scheme has better performance than the compared approaches.