移动IP中改进TCP性能的几点建议

介绍了TCP性能的控制机制,分析了移动IP中的切换对TCP性能的影响,提出了在移动IP中改进TCP性能的方法。     

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.     

使用EHN-HP机制提高移动切换中TCP性能

移动通讯技术的发展促使传统有线互联网向无线移动网络延伸.TCP协议是现在互联网上使用最为广泛的端到端可靠传输协议,但TCP协议是在有线链路基础上设计的,直接在无线移动网络上使用TCP协议会造成TCP性能的下降.本文详细分析了移动切换对TCP协议造成的影响,比较并分析现有的几种解决方案,针对切换对TCP造成的影响提出了EHN-HP机制.EHN-HP机制在现有的TCP协议上进行改进,增加了切换处理机制(Handoff Process),通过网络模拟器的模拟结果表明,EHN-HP机制有效的改善了TCP协议在切换过程中的性能.     

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。     

基于冗余路由信息和预缓存策略的移动IPv6快速切换方法

研究了FMIPv6(MIPv6 fast handovers)协议中移动节点在预测出错情况下的IP连接恢复问题,提出了一种基于冗余路由信息和预缓存策略的快速切换方法RIRS(router information redundancy scheme).该方法通过构造冗余切换路由表来协助移动节点快速重构新的转交地址,并采用预缓存策略来保护切换过程中到达的数据分组.仿真结果表明,RIRS能够获得比FMIPv6更小的切换延迟及丢包率.     

蜂窝重叠情况下移动IP切换延时分析

从理论上首次对移动 IP 切换过程中的切换延时和乱序分组进行了建模和分析,分别得到了各自的概率分布公式。并且根据这个结果,优化了重叠区域的半径。结果表明:本模型准确地描述了移动 IP 的切换行为,它对于评价移动 IP 的切换性能非常有用。     

MobileIP切换时的TCP／UDP性能分析

这篇文章分析了ModbileIP的基本原理,讨论了移动主机的切换过程,详细分析了现有几种移动切换算法的性能,并在基础上提出利用链路层切换的信息及主动发送代理请求消息减小切换的时延,从而改善移动主机的切换性能的设想。计算机仿真结果表明这种算法能够有效地改善移动主机的TCP／UDP性能。     

未来移动多媒体网络之间无缝切换的挑战

第三代移动通信系统的主要目标是提供多媒体业务,在移动多媒体通信系统中的切换问题非常重要,本文介绍了多媒体业务的特点,移动多媒体业务切换的特殊要求,不同网络间的切换协议。重点介绍了基于IP网络的移动多媒体网络之间无缝切换的各种水平切换和垂直切换方式以及无线TCP的优化。     

未来移动多媒体网络之间无缝切换的挑战

第三代移动通信系统的主要目标是提供多媒体业务，在移动多媒体通信系统中的切换问题非常重要，本介绍了多媒体业务的特点，移动多媒体业务切换的特殊要求，不同网络间的切换协议。重点介绍了基于IP网络的移动多媒体网络之间无缝切换的各种水平切换和垂直切换方式以及无线TCP的优化。     

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。     

Study and enhancement on buffer management for smooth handover in MIPv6

For improving Transfer Control Protocol (TCP) performance in mobile environment,smooth handover with buffer management has been proposed to realize seamless handovers. However in our simulation, even if smooth handover in Mobile IPv6 (MIPv6) is implemented, TCP can not always achieve better performance due to packets forwarding burst. Based on the study of buffer management for smooth handover, this paper proposes an enhanced buffer management scheme for smooth handover to improve TCP performance. In this scheme, a packet-pair probing technology is adopted to estimate the available bandwidth of the new path from Previous router (Prtr) to Mobile Node (MN), which will be used by Prtr to control the buffered packets forwarding. The simulation results demonstrate that smooth handover with this scheme can achieve better TCP performance than the original scheme.     

Mobility Management in Identifier/Locator Split Networks

In the traditional Transmission Control Protocol/Internet Protocol (TCP/IP) stack, IP address represents not only the identifier but also the location of a node so that it can not provide global roaming seamless. To address this problem, MIP (Mobile IP) uses dynamical care-of-address to indicate the location of a mobile node (MN) and stable home address to indicate its identifier. However, such a separation of MIP can not support routing scalability, location privacy, and manageability. In this paper, we propose an identifier/locator split architecture which contains an overlay mapping system to store identifier-to-locator mappings and manage mobile nodes?? behavior. In addition, we design a novel mobility management scheme based on the identifier/locator split architecture (MMILS) which can address the above issues of MIP. To reduce the amount of signaling and enhance the performance, we distinguish micro-mobility and macro-mobility by introducing an Agent Tunnel Router (ATR). For micro-mobility, the ATR keeps the MN??s identifier-to-locator mapping invariable, so it avoids the mapping update in the mapping system and the Tunnel Route (TR) of each correspondent node. For macro-mobility, to support fast update and handover, we design a united mapping table in the ATR. And then, we estimate the number of entries and the required storage space to validate it feasible. To evaluate the efficiency of MMILS, we analyze the signaling cost by establishing an analytical model and implement it in our test-bed. The results demonstrate that the proposed scheme can effectively reduce signaling traffic and has a low handover delay compared to MIP and HMIP (Hierarchical Mobile IP).     

网络切换对TCP吞吐量和公平性的影响分析

无线移动网络的发展日新月异.TCP协议是目前互联网上使用的最为广泛的端到端可靠传输协议,但其应用在无线网络上的时候,TCP性能下降明显.文中详细分析了TCP移动网络的切换对TCP造成影响的几个重要方面.最后通过在NS2上进行实验揭示了对多个TCP流公平性的影响,即切换后RTT越小的TCP流的吞吐量增长的越快,同时静态链路会夺取无线链路的链路资源.     

Design and analysis of an IEEE 802.21-based mobility management architecture: a context-aware approach

Broadband wireless technologies will soon become an integral part of daily life. In this paper we present the design rationale of a context-aware mobility management architecture for seamless handover in heterogeneous networks. Our proposal is a new cross-layer and interactive approach to seamless handover of users and their services. We present a simple though effective analytical model in typical deployment scenarios in heterogeneous networks with the use of the IEEE Media Independent Handover services. Such analytical model is used to evaluate the resulting handover delay when deploying common mobility protocols in our architecture, such as Mobile IP, Hierarchical MIP, and Proxy MIP.     

一种基于femtocell群的缓存切换策略的研究

为了提高局部室内无线通信质量,家庭基站正逐步应用于各类室内无线通信场景。在密集部署femtocell场景中,当用户设备由宏小区层切换至femto层时,密集的femtocell信号会影响用户设备切换的准确性,增加用户设备切换开销和不必要切换概率。针对上述问题,在密集部署femtocell环境下针对切换提出一个femtocell分集理念,在提高切换准确性的同时,降低不必要切换次数,并在此基础上提出了一种缓存切换策略,以提高设备由宏小区层切换至femto层的效率,通过仿真对所提机制的性能进行了验证。     

使用EHN-WS-HP机制提高移动切换的TCP性能

无线移动网络的发展日新月异。TCP协议是目前互联网上使用的最为广泛的端到端可靠传输协议，但其应用在无线网络上的时候，TCP性能下降明显。文中详细分析并比较了现有几种机制在移动切换时的性能，针对现有机制不能有效地感知频繁切换的弱点，提出EHN-WS-HP机制。EHN-WS-HP机制在现有EHN-HP协议上进行改进，增加了抗摆动机制（withstand Swing）以处理频繁的切换。     

VSPLIT: A Cross-Layer Architecture for V2I TCP Services Over 802.11

This article proposes VSPLIT, a new architecture based on TCP cross-layering and splitting techniques for optimizing the transport layer performance in vehicular networks for Internet-based Vehicle-to-Infrastructure (V2I) communications. Our architecture mainly pretends to enhance the performance of TCP handovers in 802.11 networks. VSPLIT includes a cross-layer TCP protocol, called VSPLIT-TCP, that adapts the congestion control during the handover, learning the new characteristics of the network after the handover using the mechanisms provided by the IEEE 802.21 Media Independent Handover (MIH) services. VSPLIT has been implemented and tested in the NS-3 simulator. We include the some of the most interesting performance evaluation results, which show a good performance of our proposal for the intended scenario.     

一种基于分层MAP的MIP切换方案

移动IP是解决无线网络融合的较好方案,但是移动IP切换时延较大,需要改进。文章通过对HMIPv6协议的分析,提出了一种基于分层MAP的MIP切换方案,利用LMAP的引入解决了MAP管理域业务量平衡的问题,提高了系统的鲁棒性。     

Seamless handover in terrestrial radio access networks: a case study

Next-generation networks will overlay heterogeneous networking technologies. In order to enable seamless communications in such an environment, providing support for efficient handover between the various access technologies will play a crucial role. The present article provides a quantitative analysis of it Mobile IPv4-based WLAN-GPRS handover prototype, identifies a number of side effects related to the link layer and routing mechanisms, and presents the impact of handover on UDP and TCP data traffic as well as on Mobile IP signaling itself.     

Signaling cost and performance of SIGMA: A seamless handover scheme for data networks

Mobile IP has been developed to handle mobility of Internet hosts at the network layer. Mobile IP (MIP), however, suffers from a number of drawbacks such as requirement of infrastructure change, high handover latency, high packet loss rate, and conflict with network security solutions. In this paper, we describe and evaluate the performance of SIGMA, a Seamless IP diversity‐based Generalized Mobility Architecture. SIGMA utilizes multihoming to achieve seamless handover of mobile hosts, and is designed to solve many of the drawbacks of MIP, including requirement for changes in infrastructure. We first evaluate the signaling cost of SIGMA and compare with that of hierarchical Mobile IPv6 (an enhancement of Mobile IP) by analytical modeling, followed by comparison of handover performance of SIGMA and Mobile IPv6 enhancements. Criteria for performance evaluation include handover latency, packet loss, throughput, and network friendliness. Our results indicate that in most cases SIGMA has a lower signaling cost than Hierarchical Mobile IPv6. Moreover, for a typical network configuration, SIGMA has a higher handover performance over Mobile IP. Copyright © 2005 John Wiley & Sons, Ltd.