利用VoIP進行網路會談(VoIP Conference)在現今的社會已有越來越流行的趨勢，尤其是遠距離語音會議的應用方面，不但能節省費用，還能同時允許多人上線會談，但隨著上線人數的增加，網路的頻寬需求與連線數量相對倍增，通話延遲時間也因頻道擁塞而難以控制，此時會議的品質(QoS)往往大打折扣，網路的負擔也會大幅增加。現行的主要解決方案為選擇網路會議中處理能力較強的使用者設備，將來自個別說話者的聲音經過混音疊加後再轉送給其他使用者，再利用不同架構的multicasting tree廣播語音封包至所有成員，藉此減少網路頻寬與連線數量的負擔，達到增加同時說話人數的目的。但這些作法在使用者所在位置過於分散、遙遠時，仍然會造成許多節點無法達到所需的通話品質。 本研究針對在大型網路語音會談中，與會人數過多造成通話品質不佳之問題，提出了解決方法，我們假設會議中大部份時間僅有一個說話者，首先為每位使用者加上靜音消除機制，只有發話者的封包直接送給其他所有與會人員，如此不但降低網路負擔，更可以刪除混音的需求，大幅降低傳輸時間，此外並以分群組（Cluster）的方式將位於同一地區的使用者分為同一群組，群組內以Full Mesh機制相連，如此便能建立一複雜度較小的MLDST (Minimum Loss Diameter Spanning Tree) 樹狀結構的multicasting tree用以廣播語音封包至所有成員，可以進一步控制傳輸時間及封包遺失率。我們根據使用者之間彼此的連線速度與實際距離來分群組，從群組中選出連線能力較佳的節點作為群組轉送點(Cluster Head)，透過此轉送點收到聲音後做群組內的發送，並藉由一個multicasting tree將封包在嚴格控制延遲時間及封包遺失率之下，將語音封包廣播至其他所有Cluster Head，以確保VoIP網路會議之品質。 我們在PlanetLab這種實際網路的實驗平台上進行實驗，評估本方法的效能，實驗結果顯示我們的方法可以在與會人數達到20人時，仍能有效控制延遲時間在350ms左右，若利用Google雲端運算系統的協助，平均延遲時間將可減少50ms至70ms。由於PlanetLab上的電腦性能普遍不佳，我們預期本技術應用於實際網路時，可以增加與會人數。

網路技術發展的日新月異帶領了眾多新網路服務的崛起，例如即時影音串流這類的多媒體服務。但即時影音串流服務所產生的龐大資料流和傳輸延遲時間的嚴格限制也隨之而來的為網路環境帶來許多挑戰，在這些條件下，傳統Server-client拓樸架構將client要求的影音資料以單一鏈結傳輸時，常會因為頻寬不足而面臨嚴重的封包遺失，或是資料流擁擠造成的額外傳輸延遲使得封包無法達到即時性的需求。P2P網路擁有server-client架構所難以達到的規模伸縮性，且對於節點、鏈結失效所引起的傳輸錯誤也較能容忍，更重要的是，它有效的分散了原本負載在少數link上的龐大資料流。因此P2P架構近年來風行於即時影音串流服務。 目前P2P網路的拓樸多是隨意形成，當網路成員規模龐大時，由傳送端出發到遠方的接收端，途中可能經過無數的鏈結，每一個鏈結都會由於頻寬的不足使得資料流遭受某種程度的品質損害，另一方面，對即時影音服務而言，若資料流的累積延遲時間超出可容忍範圍時，無法為使用者接受。 本研究嘗試找出一個較好的拓樸用以傳輸多媒體資料流，使得位於最遠端節點的累積延遲亦能為使用者接受，且資料品質的損害程度最小。我們將之建置成一NP-Complete複雜度的問題模型，名為MLDST。而解法則是修改Dijkstra single-source shortest-path演算法，並加上每個節點承擔下游節點數量及延遲時間限制而來。我們以PlanetLab環境在實際的網路上進行實驗，證實我們的演算法比傳統的Minimum-Spanning Tree及shortest path spanning tree有更好的影像品質。 / Numerous new network services arise with the advanced development of network technologies, such as real-time multimedia streaming services. But challenges to network environment come along with the enormous traffic of data flows and rigorous restriction to transmission delay of real-time multimedia streaming services. Under this circumstance, conventional server-client topology suffers from serious packet loss and packet delay due to the overload of servers and their accessing links. Also, extra transmission delay may make packets fail to meet the requirement of real-timed services. Peer-to-peer network is more scalable than server-client model, and is much more tolerable to the transmission errors caused by node or link failures. More importantly, it effectively distributes load from the server to peers. As a consequence, peer-to-peer service architecture becomes very popular for real-time multimedia streaming services recently. Peer-to-peer networks are mostly formed in random fashion. As the size of network grows, packets may have to travel through numerous links to reach far-end receivers. The quality of data may be damaged by insufficient bandwidth of links. For real-time multimedia services, it is not acceptable to users if the cumulated packet delay exceeds a tolerable limit. Our research is trying to find a better topology to transmit multimedia data flows which makes the cumulated delay of the most-far-end user be tolerable and the damage of data quality is minimized. The problem is modeled as a MLDST problem, which is a NP-Complete problem. To solve the problem, we modified Dijkstra’s single-source shortest-path algorithm by bounding the node degree and adding delay constraint. The experiments were carried out on real network environment through PlanetLab. Experiments show that our algorithm outperforms traditional MST and shortest path spanning tree.

在vehicular network中應用Peer to peer (p2p)是目前尚在研究的一項領域。不同於一般wired network的環境，vehicular network環境中變動性相當高，且車輛移動速度快，車輛間無法長時間維持連線，所以若要在vehicular network上分享檔案資源，會遭遇到許多問題，像是如何在網路上有效率地搜尋所需要的檔案、相距甚遠的車輛如何分享彼此的資源、在有限的頻寬中如何發揮最大的分享效益，皆是十分重要的課題。本研究提出Urban Multi Layered Chord (UML-Chord)架構，在市區環境的vehicular network中，引入infrastructure-based的架構，以解決ad-hoc環境中只能靠車輛機會相遇時交換訊息，僅能做範圍內搜尋的缺點。另外我們使用multi-layered chord來管理網路上分享的檔案資源，此種結構化的p2p架構可以有比較好的搜尋效率。在檔案傳輸上，我們加入交通號誌的狀況後，讓車輛間連線預估時間(connection lifetime)更加精確，得以選出最適合的節點下載檔案，增加檔案的傳輸效率，提昇整體p2p應用的效能。 / Peer-to-peer (p2p) applications on vehicular network is a significant research topic today .Vehicular network is different from traditional wired network environment in some characteristics. Topology is very dynamic and vehicles driving in high speed, the connection between vehicles can’t maintain in a long time in vehicular network. If we want to share file resources on vehicular network, there are some problems to confronted, like the efficiency of query operations, sharing files with distance vehicles and fully utilizing the limited bandwidth. Our paper proposes an Urban Multi-layered Chord (UML-Chord) method in urban Vehicular network. Introducing infrastructure based architecture to deal with the problem that cars can exchange their files only when they meet each other in ad-hoc mode. In addition, we use multi layered chord to manage file resources which should be shared on Internet. This kind of structured p2p architecture has better efficiency in searching files. For file transfer part, we take stop light into account. We modify connection lifetime, let it be used in choosing appropriated download peers, enhancing the efficiency of p2p application.

功能點分析(Function Point Analysis)為一種考量資訊系統商業實務貢獻的功能複雜度指標，過去數十年來，許多學者對此指標的應用有過廣泛研究，但是，應用於某些領域的系統仍未有深入探討。例如本研究使用的個案，是一個點對點訊息傳遞資訊系統，其特性是採用同儕計算架構(Peer－to－Peer, P2P)，並使用後設資料模型(Meta-data Model)進行資料塑模，使用功能點分析模型進行研究，透過實際的估算步驟，期望能夠提出功能點分析的適用性問題，以求進一步應用於業界及後續學術研究。

近年來網路多媒體應用日漸盛行，從聲音、影像到網路電視的應用，皆流行於人們的生活之中。我們可以使用Skype 軟體撥打免費的網路電話或是節費電話，我們也可以使用軟體透過網路來觀賞電視節目，而大部分這類型的應用軟體皆使用點對點的技術來獲取更好的傳輸效率。點對點技術同樣是一項新的、受歡迎的應用。從一開始使用者使用點對點傳輸軟體來下載檔案、分享資料，到現在使用點對點傳輸軟體來收聽音樂、觀賞電視節目。無線網路，特別是IEEE 802.11 無線網路，近年來同樣地受到使用者的廣泛使用。使用者可以在任何一處使用網路，即使是在行走之中使用。多媒體結合無線網路是一項非常好的應用，然而，無線網路的一些基本問題，例如移動、傳輸不穩定，常常會降低網路的傳輸效率。因此，我們提出一個新的移動式點對點串流協定，來解決無線網路上多媒體應用的傳輸問題，讓影音的撥放可以更順暢。 / Network multimedia applications are popular in recent years. From voice over IP, video over IP, to IPTV, they are in people’s life now. We can use Skype to dial a free network call or a cheap PSTN call, and we can use some applications to watch TV programs from Internet. Most of them use peer-to-peer technology to get better performance. Peer-to-peer technology is also a new and popular technique in recent years. People use peer-to-peer software to download files and share data in the beginning, and now they use peer-to-peer software to listen to music, and to watch TV programs. Wireless networks, especially the IEEE 802.11 network, is also popular now. People can access Internet anywhere even they are walking. It's a good idea to use multimedia streaming applications in wireless networks, but however, the essential problems of wireless networks will reduce the performance of these applications, such as mobility, and channel instability. We propose a new mobile peer-to-peer streaming protocol to solve the performance problems caused by wireless networks and let the media be played more continuously and smoothly.

在目前的網際網路中，點對點(P2P)網路的應用扮演了一個重要的角色。由於在點對點網路架構下，檔案分享系統中檔案的數量以及來源大量增加，造成使用者必須花費更多的時間找尋想要的資源，因此搜尋功能就顯得格外地重要。BitTorrent(BT)作為一個點對點檔案分享系統，用戶量不斷增加，已逐漸成為網路頻寬的主要消耗者之一，但是其協定中沒有提供搜尋的功能，而且檔案分散於各個檔案發佈站之間，以及各發佈站之間無法有效搜尋彼此擁有的檔案資源，導致使用者查詢時效率不佳。因此本研究期望建立一套語意式搜尋機制來幫助使用者解決上述的問題。藉由使用語意網技術(Semantic Web)，針對BT檔案分享系統設計本體論，進行資源描述和建立簡單的分類，利用檔案的metadata來提供搜尋的功能以及彙整各檔案分佈站的檔案資源，做為上述議題的一個解決方案，讓使用者能夠更有效率地找到更完整的資源。 / In current World Wide Web, P2P network application plays an important role. Because the number and origin of files increase greatly in file sharing system under the architecture of P2P, causing users to spend more time searching for the resources they want. Therefore, the search function appears especially important. BitTorrent(BT), one kind of P2P file sharing system, has more and more users and becomes one of the biggest consumer of the network bandwidth. But it doesn't support any search function and shared files disperse between many web sites. Furthermore, these web sites can't exchange the shared files they own efficiently. These problems result in inefficient search performance. My research expects to propose a semantic search method to solve the problems mentioned above. By the means of Semantic Web technology, we design the ontology of BT file sharing system to describe the resources and establish simple taxonomy. In addition, using the metadata of files to provide BT for search function and collect the shared files between web sites. Let users find the shared files more efficiently and completely.

由於網際網路的盛行，許多產品或服務可以開始考慮由網路進行派送。特別是一些可以用0與1位元方式進行編碼的資訊或資料尤為適合。 基於在這樣的大環境之下， 本論文將著重於兩個部份的研究： 第一部份將設計一個新的商業模式，可以當作數位內容的發行商或通路商；第二部份將進一步闡述該商業模式在數位內容產業的應用模式。 本論文研究產生了幾個重要與有趣的研究發現。首先，虛擬通路商將會在未來數位內容的流通與發行上，扮演一個重要的角色。其次，虛擬通路商必須在”四流”(金流、物流、資訊流與商流)上扮演積極的角色，將有更大的機會可以勝出。再者，類似像點對點這樣的資訊科技將會非常適合用來應用在數位流通的議題之上，這些資訊科技也有助於提供虛擬通路商和其他競爭者間的差異化。最後，版權管理機制、智慧財產權管理、代收代付服務、會員募集與清算中心等服務，都是一個虛擬通路商可能應該關注的課題與建構成為核心能力的主要服務。 / Due to the high penetration rate of Internet, a lot of products and services could try to deliver on net; especially for those data or information could be transferred into the bits 0 and 1. Under this kind of circumstance, this research will focus on two parts: the first part is proposing a new business model of digital content distributor based on Gary Hamel’s theory; the second part is further elaborating the application of the business model in digital content industry based on the field studies. The research results in several important implications and discoveries on this topic. First of all, the virtual distributors will play an important role in the publishing of digital content; Secondly, the virtual distributors have to take care of “Four Key Flows”, including money flow、information flow、goods flow and Internet traffic, to enhance her services. Thirdly, some new IT technologies, like P2P technology, is very appropriate to apply into the business model of virtual distributors and it will be helpful to differentiate her services to those potential competitors. Finally, DRM service、Intellectual property management、Payment service、Member collection and Clearing house service are the major tasks that a virtual distributor should focus, but member collection and clearing service for consumers and digital content developers will be the first priority.

網際網路的發達產生許多新的商業模式，線上音樂的興起即是一例，面對紛擾不斷的線上音樂交換，各國因應態度不一，如何兼顧科技發展及保護著作人權益儼然已成重要議題。著作權補償金制度精神在於補償著作權人在利用人合理使用下做遭受經濟上的損失，目前尚無國家對線上音樂交換業者收取補償金，本研究即欲探討補償金之徵收是否能有助於解決線上音樂之爭議、我國著作權法五十條之一修正案是否具可行空間，及線上音樂交換爭議各關係人在補償金制度中能扮演的角色為何。 本研究以次級資料分析之方式，針對補償金、強制授權、概括授權等制度進行探討，並深度訪談施行補償金制度之各關係人意見，研究結果發現補償金制度應用於線上音樂交換確有其空間，亦可有效彌補著作權人之損失，且有助於線上音樂交換業者與著作權人進行理性之談判。線上音樂交換業者亦可提供其科技能力，協助補償金制度施行，仲介團體雖已有徵收及分配權利金之經驗，但在補償金制度施行前仍應做好妥善之準備，俾使補償金制度有效運作。 / There have been great legal debates over the legitimacy of digital music distribution channels such as peer-to-peer file exchange system. Music industries insist that any unauthorized replication of music is illegal, whereas service providers thinks that technology is neutral and should not bear any responsibilities about the contents transferred through the platform it provides. Courts around the world have different opinions on the issue, and no viable solution has been found as yet. Levy systems for copyright has been around for several decades, which recognizes the difficulty of authors (or owners) of copyright to enforce it. Levies will be collected for a host of different sources include blank media, recording devices and so on, which means sale of digital devices such and digital music players/recorders, maybe even the Internet access service or personal computers are subjects to levy collection. Government agencies in Europe, Japan and Canada has long been dealing with such issues and have their levy systems well established, which seems to be a viable solution for the digital music debates. The history of levy system and the implementation in different countries were surveyed in this thesis, and in-depth interviews were conducted to examined the opinions of different parties (regarding the dispute over digital music distribution) by. It is found that a well-designed levy system could ease the tension between music and technology industry, therefore facilitate talks between them in search for a solution based on mutual interests. Another interesting finding is that the attitude toward peer-to-peer service provider is quite different between music industry and musicians. Distinction must be made between music industry and individual musicians if one intend to study the resolution of disputes in digital music distribution.

無線網狀網路(WMNs)為目前熱門的廣域無線網路接取技術。使用者可以透過WMNs隨時在各處使用即時影音播放的服務。相較於傳統的主從式架構，低成本且容易建置的點對點架構更適用於影音串流的應用；在進行即時影音播放的時候，影音播放的品質便為相當重要的目標。因為多媒體應用服務對於延遲及網路傳輸效能相當敏感，且WMNs的傳輸過程中常會面臨同頻道干擾的問題而使得傳輸的效能銳減，當每個網路節點都具有多張無線網路卡時，如何善用WMNs多頻道傳輸的特性提升效能更是顯得特別重要。在本篇論文中，我們利用WMNs多頻道傳輸的特性進行多媒體群播傳輸，參考史坦納樹的概念來改善現有的MAODV路由演算法，以傳輸品質較佳的鏈結改良原本尋找最小跳躍數路徑的方式，建立兩棵完全互斥的群播樹作為點對點傳輸的骨幹網路，並以MDC的概念將影像串流編碼成兩份獨立的子串流分別經由不同的群播樹傳輸。經實驗評估，我們的方法在網路負載較高的環境下能有效的降低延遲並提高整體系統的效能。 / In WMNs, users can enjoy the real-time video streaming service anytime and anywhere through the services. Compared to the client/server model, P2P approaches is more suitable for video streaming applications because of its low cost and easy deployment. But when using the real-time multimedia service in WMNs, the multimedia applications are very sensitive to delay time and the performance of packets transmission. And the performance is significantly influenced by the co-channel interference, so that it is important to know how to transmit by multi-channel to enhance the performance. In our approach, we choose the better quality links for routing instead of the minimum hop-count path in MAODV. Then we distribute the video streaming to receivers by multicast in multi-channel WMNs, and refer to the Steiner tree concept to modify the MAODV routing protocol to construct two disjoint multicast trees as the backbone for the P2P structure. Therefore, we can adopt the MDC scheme to encode the video into two independent sub-streams and transmit separately along these trees. Experiment results show that in higher network traffic load environment, our scheme is more effective to reduce the latency and improve overall system performance.

由於VANET上的行動節點移動速度快，加上受到道路及交通號制的限制，導致網路拓樸快速改變，容易造成網路斷訊，影響資料封包在網路上的傳送效能。在傳統的MANET上有許多用來傳送資料封包的路由機制，並不直接適用在VANET上。隨著Global Position System (GPS)的普及，越來越多的車輛都具備GPS，用以輔助行車定位之用。在本研究中我們將透過GPS取得車輛的地理資訊，提出一個適用於VANET中以車行方向為基礎的貪婪路由演算法(MDBG)。 本論文目的在強化VANET網路上資料封包的路由選擇策略。所提出的路由機制將會透過hello message來取得相鄰車輛的位置和車行方向，並利用目標要求(DREQ)、目標回應(DREP)來獲得目標車輛的資訊。進而運用車輛的車行方向，選擇適當的相鄰車輛找出一條穩定的路由路徑。當來源車輛和目標車輛的車行方向相同時，AODV能有不錯的效能表現。而我們的路由演算法(MDBG)將強化當來源車輛和目標車輛的車行方向相反，並且逐漸遠離時的效能表現。實驗模擬的結果顯示MDBG在封包到達率、吞吐量和平均端對端延遲上較之於AODV及DSR演算法有更優異的表現。 / Packets transmission over VANET is intermittent due to rapid change of network topology. This comes from both high mobility of mobile nodes and road limitation. Intermittent transmission causes inefficient packet delivery. Those routing protocols applicable to MANET might not be suitable for VANET. On the other hand, Global Position System (GPS) is becoming prevalent in assisting positioning for vehicles. In this research, we develop a Moving Direction Based Greedy (MDBG) routing algorithm for VANET. MDBG algorithm is based on the geographical information collected by GPS. The objective of the thesis is to enhance routing decision in packet delivery. The "hello message" is used to retrieve the locations and moving directions of neighboring vehicles. Destination REQuest (DREQ) and Destination REPly (DREP) messages are used to retrieve target vehicle information. The source vehicle will thus use these information together with its own moving direction information to establish a stable routing path by selecting appropriate neighboring vehicles. AODV algorithm is proved to have good performance as both the source vehicle and target vehicle have the same moving direction. MDBG algorithm is proposed to leverage the problem as source vehicle and target vehicle move far apart in opposite directions. Simulation results show that MDBG outperforms both AODV and DSR in packet arrival rate, throughput and average end-to-end delay.