【作者】 郭少华；

【导师】 徐惠民；

【作者基本信息】 北京邮电大学 ， 电路与系统， 2007， 博士

【摘要】 移动IP是IETF(Internet Engineering Task Force)提出的在网络层解决主机移动性问题的可行解决方案。移动IP与传输媒介无关。该标准是使连接到任何网络上的移动终端使用一个固定的IP地址，并能够在切换链路时仍可保持正常通信的技术。虽然移动IP在网络层解决了主机的移动性问题，但是仍然有很多地方存在缺陷，有待改进。比如说基本移动IP协议中，注册信令开销太大的问题：切换时延太长，丢包率大的问题等等。着眼于上述注册信令开销太大和切换时延太长的问题，本文对移动IP中的移动性管理方案和切换算法进行了深入的研究。本文的主要创作性工作如下：1．针对移动IP注册信令开销太大的问题提出了一种自适应的MIP移动性管理方案，通过代理的级联和自适应调整来减少网络信令开销。并对该方案进行了建模分析。结果表明该自适应移动管理方案可以有效减少移动IP的总体传输开销。2．对HMIPv6的MAP选择算法进行了深入研究。提出了一个两级HMIPv6的MAP选择算法，以及算法中的阈值的动态调整机制，以改进HMIPv6在域外注册开销方面的性能。该算法综合考虑了移动节点的移动特征和通信量特征作为MAP选择的参考，优化了选择策略。仿真结果表明该方案有效的减少了HMIPv6的总体域外注册开销。3．针对移动IP切换时延太大的问题，本文在原IETF的移动IPv4预注册切换方案的基础上提出了一个改进方案。改进方案中加入了一个控制消息RCR。通过这条消息控制GFA更新MN移动绑定列表信息的时间。由此控制oFA端的丢包率和nFA端对缓存大小的需求。分析结果证明了改进方案相比原方案的优越性。更多还原

【Abstract】 MIP was originally designed by IETF to serve the needs of globally mobile users who wish to connect their MNs to the Internet and maintain connectivity as they move from one place to another, establish new links, and move away from previously established links. However, communication quality of MIP degrades because of its high signaling overhead and its long handover delay.At first, the thesis gives an introduction of the basic Mobile IP protocol that IETF suggested. Then we study several key techniques of MIP, including mobility management of MIPv4 and MIPv6, low latency handoff process in this paper. The main research work and conclusions are as follows:1. One of the major problems for the Mobile IP is frequent location update and high signaling overhead. To solve this problem, a regional registration was proposed to employ the hierarchy of the foreign agents (FAs) and the gateway foreign agents (GFAs) to localize registration operation. The system performance is largely dominated by the ability of a GFA and its reliability. In this paper, we propose a new location management scheme for Mobile IP that reduces signaling burdens configuring regional network dynamically according to the characteristics of users and network. Simulation demonstrates that the proposed scheme performs better than other schemes when compared the total signaling cost and the regional network size.2. Based on the analysis of inter-domain registration cost of the mobile node in "Hierarchical Mobile IPv6" (HMIPv6), we proposed an optimized selection algorithm. To make good use of the capability of higher MAP, a dynamic adjustment mechanism for the algorithm was introduced. Theoretical analysis and simulation results showed that the inter-domain registration cost of this algorithm was lower than the traditional mobility based MAP selection algorithm and dynamic adjustment mechanism improves the performance further.3. We present an improvement over the Pre-Registration low latency handoff proposed by the IETF. By applying a control message, the actual handoff latency and buffering requirements decrease. After describing the protocol, we present an analytical model that provides us with results on packet delay and buffering requirements for a CBR packet stream.更多还原