近年來，裝置對裝置通訊技術越趨重要，因為裝置直連的能力使得裝置間不須透過一些基礎設施當作中介設施就可以通訊，例如基地台或是無線接取器。在一些情境下是沒有基礎設施能夠提供通訊服務的，例如自然災害，戰爭或是演唱會場地中太多人要爭取頻寬的時候。因此裝置對裝置通訊技術在此時就變得極為重要，因為基礎設施已經緣於某些原因而失效了。由於現在手機間的Wi-Fi直連技術也已趨成熟，因此針對裝置對裝置通訊而作的應用軟體也越來越多。因應這件事情，我們提出一中介軟體提供多重式跳躍裝置對裝置網路的自動建立、網路的繞徑以及漫遊技術，如此便能降低開發者在實作相關應用軟體時的開發時間以及實作難度。因此開發者便能夠專心於自己的應用軟體方面的設計，而不用擔心到裝置對裝置間通訊連線的問題。此外，為評估我們中介軟體之效能，我們測量了聲音的抖動以及封包傳遞的延遲時間，經過我們實驗證明我們的中介軟體是足夠穩定已提供聲音的傳遞並達到語音通訊。

關鍵字： 中介軟體、裝置對裝置、Wi-Fi直連

Device to device(D2D) technique becomes popular recently because the ability of direct communication without infrastructures, like base station or access point, intervention. In some scenario, there is no infrastructure to provide communication service, such as natural disaster and war, or the infrastructure is overloaded to support all users, such as the concert. D2D technique shows its importance in such case. Nowadays, in pace with Wi-Fi Direct reaching maturity, there are more and more applications supporting for D2D communication. Because of the increase of the number of D2D communication applications, we purpose a middleware on Android to maintain the D2D network and the routing mechanism for other application developers. Our middleware provides the following features: multi-hop D2D network establishment automatically, routing protocols, roaming mechanism. Therefore, developers can implement their D2D network applications without regarding the network establishment and routing issue. Besides, we experiment for the middleware performance, such as jitter and end-to-end delay. After our test, our middleware has been stable enough to provide voice transmission for a long time.

Keywords: Middleware, device-to-device (D2D), Wi-Fi Direct (WFD).

Abstract i
Contents ii
List of Figures iv
List of Tables vi
1 Introduction 1
2 System Architecture 3
3 Middleware Architecture 5
3.1 Overview of Each Module 7
3.1.1 Autonomous Network Formation Protocol 7
3.1.2 Mesh Datagram Protocol (MDP) 7
3.1.3 Roaming Mechanism for Middleware 7
3.2 Interactions among modules 8
4 Multi-Hop D2D Packet Routing and Roaming Support 10
4.1 Intra-D2D Network Packet Routing 10
4.1.1 Routing Information Declaration 10
4.1.2 Packet Routing 12
4.2 Roaming Support for Multi-Hop D2D Communication 13
4.2.1 Public Address Retrieval 14
4.2.2 GD to VD Address Update 15
4.2.3 VD to GD Address Update 15
4.2.4 Packet Routing between VD and Home D2D Network 16
4.3 Entities 18
5 Experimental Evaluation 23
5.1 Experimental Environment 23
5.2 Functional Verification 24
5.3 Performance Evaluation 24
5.3.1 Impact of Communication type 27
5.3.2 Impact of Number of Hops 27
5.3.3 Impact of Network Traffic Loading 29
6 Conclusions 30
A Modules of Serval Mesh 31
A.1 Distributed Numbering Architecture (DNA) 31
A.2 Voice over Mesh Protocol (VoMP) 31

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