無線網路擬真實驗平台的設計與開發

Abstract

近年來無線網路技術的蓬勃發展，愈來愈多學者開始研究無線網路漫遊的相關議題，試圖開發設計更好的方法，來改善在漫遊時會遇到的一些延遲。設計一套新的網路通訊協定或演算法，是需要經過多次實驗來測試，由於無線網路的規模遠大於一間實驗室，架設實際的實驗環境往往是一項大挑戰。因此，許多研究便使用模擬(Emulation)來進行測試。 本論文針對無線網路漫遊，研發一套無線網路擬真實驗的平台，藉此模擬實驗，以減少實際架設環境的不便。藉由使用者圖形化介面(Graphic User Interface)來設計實驗環境以及實驗流程，套用無線傳播模型(Radio Propagation Model)與透過可程式化衰減器(Attenuator)來模擬行動節點(Mobile Node)的移動，並使用訊號隔絕箱(Signal Shielding Box)來確保實驗環境的單純。 我們提供幾個實例研究，除了演示如何使用本平台簡單的架設實驗外，也透過模擬實驗與實際環境實驗的比較，說明使用本平台的模擬實驗來代替實際環境實驗的可能。在實驗結果中顯示，行動節點於本平台的模擬實驗與實際環境實驗所接收到的訊號趨勢圖相去不遠，成功的驗證本平台的可行性。而最後我們也整理了在研究本平台的過程中，我們於實驗中所發現的一些網路的行為。

Due to handheld devices with wireless technology being ubiquitous, research for roaming in wireless networks has remained a topic of discussion. While researchers concentrate on developing new protocols or algorithms, experiments are essential in order to prove validity. However, because of the large scale existence of wireless networks, researchers cannot conduct experiments in a laboratory. To overcome this issue, real world wireless networks can be emulated. This thesis provides an In-Lab Emulation Platform (IE Platform) for roaming experiments in wireless networks and aims to reduce the complexity of conducting experiments in the real world. IE Platform adopts radio propagation models to evaluate the measured signals at a specific location within a specific network environment and emulates these signals with attenuators. In addition, it provides an intuitive approach for users to configure their experimental environment, so users can perform network planning and design mobility patterns of mobile nodes with ease. We provide several case studies to demonstrate how IE Platform makes it easy for users to conduct their experiments and to prove IE Platform is feasible. The results show that the Signal Trend Charts perceived by mobile nodes in emulation and in real world experiments are similar to the others, so we can successfully verify IE Platform’s correctness. Lastly, we list our findings from experiments in the process of developing the IE Platform.