行動加值服務之內容遞送研究

Abstract

隨著iPhone與Android的推出逐漸取代了過去Symbian、Blackberry、Windows Mobile為主的智慧型手機作業系統，也創造了新的行動加值服務生態系統。數位內容除了原有販售影音服務，消費者開始習慣透過3G行動上網瀏覽網頁以及下載各式各樣的app，並且透過較大螢幕的平板裝置使用電子書與遊戲應用。 在「內容為王」（Content is the King）的時代，以智慧型網路技術為基礎的加值服務已相對式微。3G或Wi-Fi上網已是吃到飽服務，如何在Internet上結合業者提供行動終端平台用內容服務變成更重要的議題。在內容服務方面，內容供應商最在乎的是如何保障智慧財產，以及上架成本（或工具可用性）與市場大小。因此，加值服務平台必須滿足這些需求，才有機會成功創造營收。 本論文探討行動加值服務中內容遞送的議題。我們首先研究Android作業系統，評估其支援OMA的數位版權管理（DRM）以及app防盜拷機制的能力。因為版權保護能力不足，多數廠商都發展了各自的DRM解決方案。然而，為了讓app開發商能夠上架到其他軟體商店，我們提出一個跨商店的交易架構，讓這些有專屬DRM保護的app能在其他通路銷售及運作以擴展市場。 接著，延續內容保護的研究，相對於軟體商店要保護app，電子書服務的DRM保護對象不是電子書閱讀器（app）而是電子書（data），因此在電子書閱讀器（app）實作的DRM保護可以從Android推廣到其它終端平台。然而DRM保護並非免費的午餐，針對電子書閱讀器app實作防盜拷機制而造成效能問題，我們也提出一個改善閱讀體驗的方法。 同時，以往app需開啟或背景執行才能Pull或下載新的內容，新的行動平台（如：iPhone、Android、Windows Phone）已提供app開發者推播（Push）機制。我們探討訂閱型內容在Client-Server兩端的資料同步問題。雖然推播能夠即時更新，降低用戶下載時的等待時間，但耗費較多行動環境的有限資源。特別是Push成本效益與內容時效性如何兼顧，我們最後提出一個稱為Push-N的方案。 本論文提出的研究成果，涵蓋近年來新興的app軟體商店、ePub電子書商店兩個下載類服務，以及推播機制提供新聞訂閱或軟體/電子書更新等，都已經在實務上獲得驗證，並可以在行動電信網路中作為加值服務系統設計與終端優化的重要指引。

Introduction of iPhone and Android phones have resulted in a new mobile Value-Added Service (VAS) ecosystem and significantly affected the smartphone market previously dominated by Symbian, Blackberry, and Windows Mobile. Meanwhile, the large-screen tablet devices more suitable to the e-book and game services have also become popular. With these devices, in addition to the multimedia digital contents, the consumers tend to access the Internet and download various apps through 3G-cellular service. At the age of “Content is King”, VASs based on Intelligent Network (IN) in telecom networks stop growing up the Average Revenue Per User (ARPU). How to generate a new revenue stream in the Internet becomes more critical topic for the mobile operators. For a Content Provider (CP) or a Service Provider (SP), copyright protection, publish cost and target market are major concerns. Therefore, the VAS platforms must meet the requirements. This dissertation studies on the content delivery in mobile VASs. We first study the Android OS, especially evaluating the implementations on OMA Digital Right Management (DRM) and copy-avoidance for apps. We found that DRM is an open issue on Android devices and vendors have proprietary solutions that are incompatible to each other. In order to assist the app developers to publish their apps to multiple appstores, we propose an inter-store transaction mechanism that does not require the app developers to rewrite their programs. Then we extend the study on DRM-protection to e-book service, in which the contents we protect is the data in apps (i.e. the e-book) rather than the apps themselves (i.e. the e-reader). Our e-reader prototypes are implemented on Android devices, iPhone and Window Phones. We find that the DRM-protection in the e-reader drops performance due to data decryption and affects the user experience. To resolve this problem, we also propose a mechanism that improves the e-readers with DRM-protection. On traditional mobile platforms, WAP-Push mechanism invokes apps to pull or download remote contents over IP networks. Innovative iPhone, Android, and Windows Phones have provided a new Push mechanism. We further study the subscription-based service that can push the new contents from the server to the clients. Although the Push mechanism can update the contents in real-time and reduce the user-waiting time on download, the limited resources in mobile environment are wasted. In particular, the timeliness of content updating and cost efficiency of Push mechanism is a trade-off. We finally propose a solution named Push-N that balances the concerned factors. These research results presented in this dissertation have been proved in practice and can be viewed as a useful foundation for design and optimization of VAS in mobile telecom networks.