Wi-Fi直連（Wi-Fi Direct）是由Wi-Fi聯盟所提出的技術，旨在增強裝置對裝置使用Wi-Fi來進行溝通。Wi-Fi直連的好處是他不需要透過基地台即可以讓裝置之間進行通訊。當緊急情況發生時，即可利用Wi-Fi直連的技術讓網路拓撲自動地形成。因此在本篇論文當中，我們針對Wi-Fi直連提出了能夠自動化地建立群組並串連這些群組。為了延長整體網路拓撲的壽命（lifetime），我們也提出了翻修網路拓撲的功能。除此之外，整體的方法能夠運行在未修改Android作業系統的行動裝置上。我們整體方法由三個部分所組成，單一叢集的建立、多叢集的連線以及網路拓撲的翻修。實驗結果顯示我們提出的方法不但能夠運行在市面上的智慧型手機裝置，並且還可以縮短了網路建立的時間且延長了整體網路的壽命。

Wi-Fi Direct is a new technology defined by the Wi-Fi Alliance to enhance the Device–to-Device (D2D) communications in Wi-Fi. The advantage of Wi-Fi Direct is that the device can communication each other without requiring the presence of an Access Point. When the emergency scenario like the natural disaster occurs, it can exploit Wi-Fi Direct technology to construct a wireless network without needing any pre-built infrastructure. Hence, in this thesis, we propose a method to automatically create the group and connect different groups on Wi-Fi Direct. To extend the lifetime of the network, we also propose network topology renovation. Moreover, our method can apply to non-rooted Android mobile devices. Our method consists of three phases—single cluster formation, connection of multi-cluster, and network topology renovation. The experimental results show that our method, which works on the commercial mobile devices, can shorten the network formation time and increase the network lifetime.

Acknowledgement iii
Abstract iv
Table of Contents vi
List of Figures viii
Chapter 1. Introduction 1
Chapter 2. Wi-Fi Direct Technology 3
2.1. Device Discovery 4
2.2. Service Discovery 5
2.3. Group Formation Protocol 6
2.3.1. Standard Procedure 6
2.3.2. Persistent Procedure 9
2.3.3. Autonomous Procedure 9
2.4. Wi-Fi Direct Implementation Problems in Android 10
2.4.1. Limitation of IP Address Assignment 11
Chapter 3. Related Work 12
Chapter 4. Problem Statement 16
4.1. Single group communication 16
4.2. Multi-group communication 16
4.3. IP Conflict Problem 16
Chapter 5. Proposed method 19
5.1. Role definition 19
5.1.1. Role Communication 22
5.2. Network topology 24
5.3. Automatic Cluster Formation and Renovation 25
5.3.1. Single Cluster Formation 25
5.3.2. Connection of Multi-Cluster 30
5.3.3. Topology Renovation 33
Chapter 6. Experimental Evaluation 49
6.1. Experiment Environment 49
6.2. Compared methods 49
6.3. Performance Evaluation 56
Chapter 7. Conclusion 66

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