High Performance TCP Communication over Mobile IP Handoff

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16560327
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Communication/Network engineering
• Research Institution: The University of Electro-Communications
• Principal Investigator: KUMEKAWA Kazuya The University of Electro-Communications, Graduate School of Information Systems, Research Associate, 大学院・情報システム学研究科, 助手 (30313430)
• Co-Investigator(Kenkyū-buntansha): KATO Toshihiko The University of Electro-Communications, Graduate School of Information Systems, Associate Professor, 大学院・情報システム学研究科, 助教授 (90345421)
• Project Period (FY): 2004 – 2005
• Keywords: Mobile IP / Handoff / TCP

Research Abstract

Recently, the mobile communication environment is widely spread. An example is the 3rd generation cellular network, and the Mobile IP is adopted as one of the basic protocols for such a network. In the Mobile IP network environment, it is often the case that packet losses are caused by the transmission errors in wireless links and/or the handoff during terminal movement.
In such an environment, TCP is also commonly used to access WWW servers and to transfer e-mail. However, the packet losses are described above invoke the congestion control function of TCP frequently, and as the result, the throughput of TCP communication over mobile environment is degraded heavily.
So far, there have been a lot of studies for this problem, but most of them focus mainly on the packet losses caused by transmission errors. However, in the Mobile IP networks, the packet losses caused by handoff also invoke serious throughput degradation. In this research, we propose a TCP communication procedure improving the throughput even when there are packet losses caused by the Mobile IP handoff.
Our procedure allows foreign agents to collectively work as a supervisor host in M-TCP procedure and to suspend TCP communication by making a correspondent node in persist mode. Our procedure also allows foreign agents to coordinate during the Mobile IP registration procedure and a home agent to restart the TCP communication immediately by sending a window update instead of the mobile node.
We have also shown the performance evaluation by using modified ns-2 simulator. We have concluded that our procedure outperforms both the conventional TCP over Mobile IP and the "M-TCP over Mobile IP" i.e. foreign agents support only the original M-TCP functions without allowing home agent to send any window update, which is a part of our proposal.