基于SCTP和移动IP的GEO天基网络移动性管理

相比基于低轨(LEO)卫星的天基网络,基于静止轨道(GEO)卫星的天基网络具有空间节点数量少、拓扑结构简单和系统建设成本低的优点。围绕用户终端在GEO天基网络中的移动性管理问题,利用移动IP架构的位置管理功能定位并追踪移动用户终端的网络位置,基于流控制传输协议(SCTP)的多地址归属特性保证移动切换过程中数据传输连接的连续性,提出了一种融合SCTP协议和移动IP架构的GEO天基网络移动性管理方案,具有良好的网络安全特性。测试结果表明,该方案既消除了移动IP架构固有的"三角路由"缺陷,同时具有较高的切换平滑性,是解决GEO天基网络移动性管理问题的有效方案。     

IP移动性的应用层支持方案研究

本文首先介绍了移动IP技术的基本原理,及其在支持IP地址移动性中的不足;接着给出了一种利用应用层协议SIP支持IP移动性的实现方案,并详细分析了SIP支持IP移动性的原理和具体的通信流程。     

移动IP网络的实现方案

随着网络技术与便携式终端的不断发展,在IP网络中实现对移动性的支持变得越来越重要。对数据业务而言,有两种形式的移动性,一种是基于大区的慢速移动,即跨子网的移动;另一种是基于小区的高速移动,即在蜂窝系统中移动。这两者对移动性管理的要求是有所区别的。另外,IP网的移动多媒体通信与纯粹的移动数据通信也不尽相同。移动IP网络面临一系列由于移动性而带来的技术问题,例如无线接口技术,移动终端登记与定位,最佳路由,安全性等问题,本文侧重讨论路由技术。IP地址是地点相关的,当终端移动时,要根据子网的变更修改IP地址。…     

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。     

蜂窝IP技术

本文首先介绍蜂窝IP技术的协议机制，接着详细分析其路由、切换和寻呼等关键技术，并通过性能分析、证明蜂窝IP技术能很好地利用Mobile的全局移动性支持蜂窝系统的移动切换等功能，支持频繁切换下的高速分组数据传输，适应下一代无线分组数据通信发展的需要。     

宽带卫星网络用户的移动性研究

Ka宽带卫星通信系统中,点波束和频率复用技术的应用可以大幅提高系统容量,但是机载、车载用户在不同波束间移动时会面临越区切换的问题。为实现对用户移动性的管理,结合Ka宽带卫星通信网络特点,借鉴地面网络的移动IP技术,提出了一种适用于卫星网络的移动性管理机制。该机制采用双向隧道封装技术,实现移动用户在不同波束之间、信关站之间移动时IP业务的高效传输。基于OPNET建模仿真结果表明,这种机制能够保证用户移动过程中IP业务传输不中断,解决了卫星多波束网络中用户移动性管理的问题。     

基于SIP的应用层与链路层移动性模型研究

SIP（会话初始化协议）被广泛应用于网络电话VoIP（Voiceover IP）的实现，VoIP的移动性支持是一个相当复杂的服务。VoIP的移动性表现主要取决于数据链路层的切换时延。由于VoIp是应用层的一个应用，应用层的移动性也起到至关重要的作用。文章从应用层和数据链路层对不同的VoIP移动性模型做了论述、分析和比较...     

子网移动性管理及其性能优化研究

子网移动性管理的最终目标是移动网络中的所有节点郝可以通过一个永久的IP地址被访问,并且当移动网络的路由器改变接入点时,内部节点仍然可以保持连续的通信。但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,需要对移动性管理策略进行改善。文中介绍一种基于SIP和SCTP协议的混合方法Hybrid—NEMO,解决基于MIPv6的NEMO所存在的问题。通过建立相应模型并进行仿真对比分析,该方案能够保证网络移动切换过程中零丢包率和可控制的时延抖动,完全可以实现网络无缝移动的有关性能指标,从而较好地解决了现有移动网络模型实现无缝移动过程中的不足。     

一种融合FMIPv6和SIP实现实时移动性的研究

分析了当前互联网中两种主要的移动性技术--基于移动IP和移动SIP(会话初始协议),并且指出了单一技术实现实时移动性存在的缺陷。随着移动IP技术的发展,出现了基于移动IP的快速切换FMIPv6。在此基础上,引入了一种同时在网络层和应用层提供实时移动性支持的综合性解决方案--融合FMIPv6和SIP,给出了该综合方案的优点,弥补了单一技术存在的不足,解决了通信过程中实时移动性问题。     

基于SIP的实时移动性管理新架构

文中介绍了移动SIP技术,在应用层提供对实时移动性管理的支持。随着移动IP技术的发展,近年来出现了基于移动IP的快速切换FMIPv6。在FMIPv6技术基础上,引入了一种综合性解决方案——基于SIP的实时移动性管理新架构,详细分析了该方案,并给出该方案的优点,弥补了单一协议的不足,解决了通信过程中实时移动性管理问题。     

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。     

A Robust Analytical Model of Mobile IP Handoff with Multiple Traffic Profiles

Mobile IP has been developed to provide the continuous information network access to mobile users. The performance of Mobile IP mobility management scheme is dependent on traffic characteristics and user mobility. Consequently, it is important to assess this performance in-depth through these factors. This paper introduces a novel analytical model of handoff management in mobile IP networks. The proposed model focuses on the effect the traffic types and their frame error rates on the handoff latency. It is derived based on general distribution of both successful transmission attempts and the residence time to be applicable in all cases of traffic characteristics and user mobility. The impact of the behavior of wireless connection, cell residence time, probability distribution of transmission time and the handoff time is investigated. Numerical results are obtained and presented for both TCP and UDP traffics. As expected, the reliability of TCP leads to higher handoff latency than UDP traffic. It is shown that, higher values of FER increase the probability of erroneous packet transfer across the link layer. A short retransmission time leads to end the connection most likely in the existing FA; however a long retransmission time leads to a large delivery time. The proposed model is robust in the sense that it covers the impact of all the effective parameters and can be easily extended to any distribution.     

Performance Analysis of Handoff Techniques Based on Mobile IP, TCP-Migrate, and SIP

Mobility management protocols operating from different layers of the classical protocol stack (e.g., link, network, transport, and application layers) have been proposed in the last several years. These protocols achieve different handoff performance for different types of applications. In this paper, mobile applications are grouped into five different classes, class A through class E, based on their mobility management requirements. Analytical models are developed to investigate the handoff performance of the existing mobility management protocols for these application classes. The analysis shows that applications of a particular class experience different handoff performance when different mobility management protocols are used. Handoff performance comparisons of different mobility management protocols are carried out to decide on the suitable mobility management protocol for a particular application class. The results of mathematical analysis advocate the use of transport layer mobility management for class B and class C applications, mobile IP for non-real-time class D and class E applications, and session initiation protocol-based mobility management for real-time class D and class E applications. Moreover, through analytical modeling, the parameters that influence the handoff performance of mobility management protocols are identified. These parameters can be used to design new application-adaptive techniques to enhance the handoff performance of the existing mobility management protocols.     

Hybrid mobility management schemes integrating mobile IP and SIP for seamless invocation of services in All-IP network

The growing demand for seamless invocation of different multimedia services from handheld devices anytime anywhere is the main driving force for drawing attention in the area of mobility management. Although Session Initiation Protocol (SIP) based mobility solution is very efficient for real-time services, Mobile IP is required to handle mobility of the mobile node (MN) at the network layer. We have extensively studied and explored some existing mobility management methods integrating the functionalities of Mobile IP and SIP in this paper. These schemes require support of IP encapsulation at the protocol stack of correspondent node (CN). To address the above problem, we have proposed in this paper, certain modification at the IP layer of Base Station (BS) that also reduces the bandwidth consumption. Moreover, service provisioning in a continuous way in public places like airport, university campus etc., requires to integrate some micro-mobility protocol with the existing mobility management methods to reduce the handoff disruption time in case of intradomain handoff. Thus, in this paper, we have proposed two new hybrid mobility management schemes that integrate two existing Mobile IP and SIP-based schemes where the proposed modification in the IP layer of BS is incorporated separately with the micro-mobility protocol Hierarchical Mobile IP (HMIP). The numerical results show that the integration of HMIP into the existing methods reduces both the signaling cost and the delay, mainly the active handoff disruption time. Simulation results on NS-2 demonstrate the performance improvement of the proposed mobility management schemes over the existing methods in terms of handoff delay.     

快速IP切换在无线局域网中的实现

在移动网络中,无缝切换是提供QoS的基础,也是支持实时业务应用(如视频点播和语音传输等)的保证。针对无线局域网(WLAN)的节点切换问题,建立了各种网络模型,提出了链路层、网络层和传输层的解决方案。文章根据切换过程的技术特征,研究了WLAN中网络层切换的各种方案,包括移动IP方案、TAP-DANCE方案以及网络辅助的IP移动支持,具体分析了上述方案的实现过程,比较了性能指标,指出了存在的问题及进一步研究方向。     

A Proactive mobile‐initiated fast handoff scheme using the multihomed approach

Mobile IP (MIP) defines a mobility management for mobile users to continuously access data when the currently attachment is changed to another network. However, when mobile node (MN) roams between network segments, the handoff latency results in packet losses and transmission delay. In this paper, we propose a multihomed fast handoff scheme (MFH‐MIP) to decrease the handoff cost. In the proposed MFH‐MIP scheme, each MN is implemeted with the link layer trigger and multihomed techniques. Based on the link layer trigger, MN can collect signal strengths of nearby access points (APs) and switch to a new link automatically when the old link becomes unsuitable to connect. Using the multihomed technique, MN can prepare for handoff using two (or more) interfaces, in which (i) one is connected with the old link to receive packets and (ii) the other one is used to access nearby APs and select the most suitable one as the new link, in parellel. In this way, MN can continuously transmit and receive packets during handoff. Based on the proposed method, MN can roam smoothly among different networks in the wireless environment. Copyright © 2008 John Wiley & Sons, Ltd.     

Mobile IP中的切换技术

介绍了MobileIP的基本概念和其中的切换问题,分析了影响切换时通信性能的3个因素:移动检测、重新注册以及与上层协议的相互作用,提出了新的切换方案:将链路标识嵌入到FA的代理广播消息中,使得MH可以据此进行快速的移动检测;MH为发送端时,切换后主动发送未应答的TCP包;MH为接收端时,切换后通过主动发送多个TCPSACK包来请求发送端发送已丢失的TCP包。计算机仿真结果表明新的方案具有良好的性能。     

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.     

Integrated Mobility Management Methods for Mobile IP and SIP in IP based Wireless Data Networks

With developments in voice over IP (VoIP), IP-based wireless data networks and their application services have received increased attention. While multimedia applications of mobile nodes are served by Session Initiation Protocol (SIP) as a signaling protocol, the mobility of mobile nodes may be supported via Mobile IP protocol. For a mobile node that uses both Mobile IP and SIP, there is a severe redundant registration overhead because the mobile node has to make location registration separately to a home agent for Mobile IP and to a home registrar for SIP, respectively. Therefore, we propose two new schemes that integrate mobility management functionality in Mobile IP and SIP. We show performance comparisons among the previous method, which makes separate registration for Mobile IP and SIP without integration, and our two integrated methods. Numerical results show that the proposed methods efficiently reduce the amount of signaling messages and delay time related to the idle handoff and the active handoff.