移动IPv6切换时延优化新方法

移动IPv6中,移动节点(MN)在不同子网间移动时,既不中断与通信对端(CN)的通信,也不用改变其本身的IP地址.但是当MN与其家乡代理(HA)之间相距较远时,移动IPv6切换时延较大,对于实时性要求较高的业务无法适用.本文分析比较了目前移动IPv6常用的切换时延优化方法,提出了一种自适应快速层次移动IPv6切换时延优化方法,减小了移动IPv6切换时延,提高了网络的性能.     

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。     

MIPv4配置转交地址的研究与实现

移动IPv4(MIPv4)中存在外地代理转交地址和配置转交地址配置机制,大多数情况下采用外地代理转交地址机制,在实际应用中灵活性差且部署成本较高。针对这一问题,在RFC2002协议设计的基础上,文章采用DHCP协议实现了配置转交地址机制。在此基础上提出并详细设计了缩短重复地址检测过程的几种可行方案,能够极大地缩短切换时延,满足实际应用的需要。     

基于流的移动IPv6快速切换方法

文章介绍了一种基于流的移动IPv6快速切换方法．即路由器利用IPv6的业务流的信息把各个业务流重定向到移动节点的新转交地址上．这种重定向的方式是在MN绑定更新注册的过程中进行的．使得移动节点在向家乡代理的注册还未完成之前．便能与通信对端进行正常通信，这样大大减少了切换时延．提高了切换效率．另外．本文通过理论分析．将此方法与常规的移动IPv6和分层移动IPv6机制进行了比较．并利用NS-2网络模拟器的仿真数椐对在此方法下不同类型的业务流的传输进行了分析，验证其具有较为良好的性能。     

一种新的分层移动IPv6快速切换方案研究

分层移动IPv6快速切换在一定程度上减少了切换延时，但切换过程中由网络层移动检测和使用重复地址检测（DAD）配置一个新转交地址引起的延时对实时业务仍然有很大的影响。为了减轻这些影响，文中提出了一种更加有效的快速邻居发现和DAD机制，减小了切换延时，提高了网络的性能。     

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。     

基于DAD的HMIPv6切换技术改进

在移动IPv6,尤其是层次化移动IPv6中,地址重复检测严重影响了移动节点的切换,该过程不仅浪费了时间,也增加了因特网的信令负载。本文提出了一个新的重复地址检测机制,在接入路由器和移动锚点中建立重复地址检测表,记录该区域中所有的IPv6地址,当需要进行IPv6地址检测时,只需在这些重复地址检测表中进行搜索来证实地址的唯一性。这种新方法能快速重复地址检测,缩短了重复地址检测时间。     

关于移动IP区域注册的一些探讨

在移动IP中,每当移动节点发生了切换,改变了转交地址的时候,就需要向家乡代理注册。如果访问网络和移动节点家乡网络的距离较远的话,这些注册的时延就可能比较大。同它相比,区域注册减小了移动节点域内切换时延,降低了到家乡网络的信令开销,减少了分组丢失。本文首先介绍区域注册的过程,分析它存在的一些问题,然后介绍优化途径及相应的技术难题。     

一种基于移动IPv6协议的软切换实现方案

移动IPv6协议解决了IPv6网络中移动节点的位置更新和路由可达问题,使移动节点能够在不同IPv6子网间进行切换而不中断当前连接。但是这种切换的时延较长,影响移动IPv6网络的性能。为了减少切换时延,文章在移动IPv6协议中引入软切换技术,提出一种采用绑定更新计时器和路由优先级变换机制的软切换工程实现方案,实验结果表明,该软切换方案可以有效提高移动IPv6网络的性能。     

移动IPv6快速切换在MBWA中的应用

目前的无线局域网和3G网络都还无法满足人们对移动多媒体通信的需求。IEEE802．20——移动宽带无线接入(MBWA)工作组的目标是使高速移动的用户也能获得与有线链路相媲美的数据业务体验。为了支持网络层的移动性，MBWA系统中引入了移动IPv6技术。介绍了一种可以应用于MBWA系统的移动IPv6快速切换机制，此机制是对标准IPv6切换的改进，从而能够在最大程度上减小由于IP协议操作引起的切换时延。     

A cross‐layer partner‐based fast handoff mechanism for IEEE 802.11 wireless networks

In wireless/mobile networks, users freely and frequently change their access points (APs) while they are communicating with other users. To support the mobility of mobile nodes (MNs), Mobile IPv6 (MIPv6) is used to inform the information of MN's home address and current care‐of‐address (CoA) to its home agent. MIPv6 suffers from a long delay latency and high packet losses (PLs) because MIPv6 does not support micromobility. A Hierarchical Mobile IPv6 (HMIPv6) is proposed which provides micromobility and macromobility to reduce handoff latency (HL) by employing a hierarchical network structure. In this paper, we propose a cross‐layer partner‐based fast handoff mechanism based on HMIPv6, called the PHMIPv6 protocol. Our PHMIPv6 protocol is a cross‐layer, layer‐2 + layer‐3, and cooperative approach. A cooperative node, called a partner node (PN), is adopted in the PHMIPv6 protocol. A new layer‐2 trigger scheme used in the PHMIPv6 protocol accurately predicts the next AP and then invites a cooperative PN in the area of the next AP. With the cooperation of the PN, the CoA can be pre‐acquired and duplicate address detection operation can be pre‐executed by the PN before the MN initializes the handoff request. The PHMIPv6 protocol significantly reduces the handoff delay time and PLs. In the mathematical analysis, we verified that our PHMIPv6 protocol offers a better HL than the MIPv6, HMIPv6, and SHMIPv6 protocols. Finally, the experimental results also illustrate that the PHMIPv6 protocol actually achieves performance improvements in the handoff delay time, PL rate, and handoff delay jitter. Copyright © 2009 John Wiley & Sons, Ltd.     

移动IP中的S-MIP切换方法

有两种比较常用的减少切换时延的方法．第一种是通过分层管理的架构来减少家乡网络的注册时间，第二种是通过地址预先配置来减小地址长度的方法来解决延迟的快速切换机制。S-MIP切换方法是建立在分层和快速切换方法之上的。它能够实现与L2层相似的较少的数据包丢失和切换的时延。     

Adaptive Route Optimization in Hierarchical Mobile IPv6 Networks

By introducing a mobility anchor point (MAP), Hierarchical Mobile IPv6 (HMIP6) reduces the signaling overhead and handoff latency associated with Mobile IPv6. However, if a mobile node (MN)'s session activity is high and its mobility is relatively low, HMIPv6 may degrade end-to-end data throughput due to the additional packet tunneling at the MAP. In this paper, we propose an adaptive route optimization (ARO) scheme to improve the throughput performance in HMIPv6 networks. Depending on the measured session-to-mobility ratio (SMR), ARO chooses one of the two different route optimization algorithms adaptively. Specifically, an MN informs a correspondent node (CN) of its on-link care-of address (LCoA) if the CN's SMR is greater than a predefined threshold. If the SMR is equal to or lower than the threshold, the CN is informed with the MN's regional CoA (RCoA). We analyze the performance of ARO in terms of balancing the signaling overhead reduction and the data throughput improvement. We also derive the optimal SMR threshold explicitly to achieve such a balance. Analytical and simulation results demonstrate that ARO is a viable scheme for deployment in HMIPv6 networks.     

Achieving seamless handoffs via backhaul support in Wireless Mesh Networks

In Wireless Mesh Networks (WMNs), mobile clients may experience frequent handoffs due to the relatively small transmission range of the mesh routers. Each handoff may lead to packet delays and/or packet losses, which limits the performance of real-time applications over WMNs. In this work, we propose BASH—a Backhaul-Aided Seamless Handoff scheme. BASH takes advantage of the wireless backhaul feature of WMNs, and allows a mobile station to directly access the backhaul channel to probe the neighboring mesh routers. Our work shows that by utilizing the wireless backhaul, BASH (1) reduces the probing latency and, thus, the Layer-2 handoff latency; (2) allows partial overlap of the Layer-2 and Layer-3 handoffs, reducing the overall handoff latency; and (3) shortens the authentication latency by utilizing the transitivity of trust relationship. The experimental results show that BASH achieves an average Layer-2 handoff of 8.9 ms, which supports real-time applications during the handoff.     

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.     

IEEE802.11切换中一种快速主动扫频算法

提出了一种IEEE802.11切换过程中的快速主动扫频算法。首先STA从扩展了位置信息的邻居AP图中选择被扫频的AP,然后采用单播方式完成扫频。改进算法减轻了由多余信道扫频、等待时延和信道冲突所产生的时延。仿真分析表明,改进算法确保切换完成,并明显地减小了扫频时延。     

Multilayer Hierarchical Model for Mobility Management in IPv6: A Mathematical Exploration

The mobility solution provided by Mobile IPv6 (MIPv6) imposes too much signaling load to the network and enforces large handoff latency to end user. Hierarchical MIPv6 (HMIPv6) on the other hand, is designed by organizing MIPv6 in layered architecture and performs better than MIPv6 in terms of handoff latency and signaling load. Observation shows that, there is still possibility to shrink the handoff latency and the signaling load by further extending HMIPv6 into multiple layers. To explore this possibility of enhanced performance through layered architecture, this paper aimed at mathematical exploration of an N-layered MIPv6 network architecture in order to figure out the optimal levels of hierarchy for mobility management. A widespread analysis is carried out on various parameters such as location update frequency and cost, handoff latency and packet delivery cost. Influence of queuing delay on handoff latency is examined by modeling M/M/1/K queue in the architecture and user mobility is modeled using Markov chain. Analytical investigation reveals that three levels of hierarchy in MIPv6 architecture provide an optimal solution for mobility management.     

Effective Performance Compensation for the Premature Handoff Trigger in FMIPv6 Networks

Handoff trigger in Fast Handoff for Mobile IPv6 commonly use the underlying link-layer (L2) events to make effective handoff decisions. Ideally, with the timely L2 trigger invoking the handoff protocols of upper layer, the specified handoff procedures can be fully accomplished before terminating the current access link for enhancing the network performance. Firing the L2 trigger however is not always preferable owing to the irregular mobility profile acted by the mobile terminals. The premature L2 trigger leads to the unnecessary handoff with serious performance loss and resources waste. To address this issue, a performance compensation scheme for the premature handoff trigger (PC-PHT) is proposed, where the IP prefix in the Router Acknowledgement messages received by the mobile node within a defined time frame after the L2 trigger are firstly analyzed to promptly determine the premature trigger, and then a set of specific performance compensation measures are developed to accelerate the process of re-accessing into the previous served subnet. The simulations conducted on Network Simulator platform indicate that PC-PHT outperforms the compared schemes in the case that the L2 trigger does not correspond to an actual handoff by promptly determining the premature trigger, accelerating the re-accessing process and partially eliminating the performance loss.