以頻寬整合縮短行動裝置之檔案傳輸時間

Abstract

目前行動裝置配備有多種無線介面，可供人們連線上網際網路。但人們為了省電的目的，通常只有其中一個無線介面被啟用。因此在過去的文獻中，對於同時啟用多種無線網路介面進行傳輸的想法並未被深刻的探討過。然而在許多的應用中如車載網路，能量的消耗已不再成為絕對主要的考慮，使用多重介面傳輸來增加傳送速度則成為一種選擇。 在這篇論文中我們著手研究同時啟用多個無線介面來改善傳輸效率。傳統的檔案傳輸協定中雖然有多重連線的設計但沒有處理同時啟用多種無線傳輸介面的做法，所以我們首先提出了Multipath File Transfer Protocol 來減少檔案傳輸時間。然而在考慮網路狀況變動的情形下，我們提出了Adaptive Multipath File Transfer Protocol。為了更有效率使用無線介面頻寬，我們進而提出了結合UDP傳送及網路編碼的檔案傳輸協定NC-Based Multipath File Transfer Protocol，此檔案傳輸協定更可以進一步的減少檔案傳輸時間。實驗環境設定在netbook透過WiFi和3G網路下載遠端伺服器的檔案。 我們透過實作比較這些檔案傳輸協定。而實驗的結果證實了同時啟用多種無線網路介面進行傳輸是可行的。而在我們的實驗中，我們所提出的協定可以減少40%的原本的FTP的檔案傳輸時間。

In the past, although mobile devices were equipped with multiple radio interfaces, for the sake of power saving, only one was activated for data transmission. The idea of concurrent transmission via multiple radio interfaces has not been seriously studied. However, power consumption no longer is a problem in many application scenarios, e.g. VANETs. In this work, we investigate the performance improvement of concurrent file transfer over two heterogeneous radio networks, e.g. WiFi and 3G. The traditional File Transfer Protocol is modified to utilize two heterogeneous radio connections. We propose Multipath File Transfer Protocol to reduce the file transfer latency. Then, considering the network variation, we propose Adaptive Multipath File Transfer Protocol. Final, we propose NC-Based Multipath File Transfer Protocol to further raise the performance. The experiments are executed over the Internet and a 3G data network to measure the latency and average bandwidth. Our results show that it is possible to integrate the bandwidth of both radio networks. The file transfer latency of our proposed protocols is 60% of file transfer latency of FTP via single interface.