TCP 在可移動網路上之效能分析

Abstract

隨著無限網路技術的進步，這一類的產品已經越來越常出現在我們的日常生活中。從筆記型電腦、手機、PHS、以及PDA漸漸都已經發展出各自的方法能夠連接到Internet。由手機從2G到3G的發展，更可以看出在將來無限傳輸將以IP-network的方式為主流，並且以封包交換的技術作為資料傳輸的方法。 就目前而言，要提供可移動式IP的技術，最基礎的作法就是Mobile IP技術。另一方面，在網路上流通最普遍的終點對終點傳輸協定是TCP。然而由於原本TCP在設計的時候，Mobile IP 還沒有之類的技術還沒有發展出來，因此TCP 在該種網路上傳輸時也會遭遇到一些問題。以往的研究很多都著重於修改TCP或是Mobile IP的技術使他們能夠互相作用的更好。本篇論文則是提出了一個分析的架構來分析在Mobile IP上面的TCP 傳輸效能，藉由此方法可以量化在不同環境下Mobile IP對TCP的影響。作為進一步研究的基礎。

Abstract With the growth of wireless technology, wireless network access has become more and more popular. To date, mobile devices such as notebooks, cell phones, and palmtops can connect to the Internet through specific wireless network systems. With the trend of all-IP network evaluation, there are some issues about reliable packet delivery on wireless networks. Since, in IP networks a popular method to provide mobility is mobile IP; the most common traffic type on IP networks is TCP. The performance of TCP over mobile networks may become more and more important. However, TCP is originally designed for wired end-to-end packet delivery, so many TCP mechanisms will have some problems when using them on wireless networks. Such as high wireless link error rates and packet lost due to mobile node handoff. In this paper we propose an analytical model to derive the Reno TCP performance over mobile IP. By carefully observing the handoff effect to TCP congestion window, the effect of handoff on TCP performance could be calculated. Once the influence of handoff has been quantified, it’s easy to apply mobility issue into TCP performance.