隨按即說服務之分散式發話權控制之效能分析

隨按即說(Push-to-talk或稱PTT)是一種提供一對一或是一對多的群組通訊的服務。PTT類似於傳統的walkie-talkie的功能，其最主要的特色在於，使用者之間的通訊可以藉由按下通話按鍵快速的被建立而不需要繁複的設定。目前，在行動通訊網路上已經有部分的業者提供PTT的服務，但是缺乏共同的通訊協定。因此，OMA(Open Mobile Alliance)組織的PoC(Push-to-talk over Cellular)計畫，對於PTT的服務訂出了通訊協定的規格。OMA所訂的PoC規格中採用集中式的架構，其缺點為需要額外維護伺服器的成本以及系統延伸性與系統可靠性受限於系統伺服器。因此另一套有別於OMA作法的系統iPTT被設計出來。iPTT是一套採用點對點技術的服務模式，每個裝置之間是透過網際網路連接彼此。Floor control (發話權控制)是在PTT 服務中一個相當重要的功能。所謂的floor control，就是當系統中同時有多位使用者按下說話鍵時，系統要能夠決定出唯一一個使用者取得發話權利。目前，已經有一些分散式floor control的方法被提出來。在這篇論文中，我們訂定了一些評估分散式floor control效能的一些指標，並且利用網路模擬軟體在不同的模擬環境中觀察這些現有的分散式floor control之優缺點。提供未來設計及實作分散式floor control方法的系統業者其參考之依據。

關鍵字

隨按即說；網路電話；群組通話；分散式系統；發話權控制

並列摘要

Push-to-talk (PTT) is a service that provides one-to-one or one-to-many group communication. PTT is similar with traditional walkie-talkie system; the main characteristic of PTT is that the session can be established easily by pushing a button without complicated configurations. At present, PTT service is provided on cellular network. However, the interoperability is bad due to the lack of common protocol. Since, the PoC (Push-to-talk over Cellular) project of OMA (Open Mobile Alliance) defines the protocol of PTT in cellular network. The PoC adopts centralized system architecture so that extra cost of maintaining server is required and scalability and reliability are limited by server. Different from PoC centralized approach, a distributed approach called iPTT is proposed. iPTT is a service model that adopts peer-to-peer technology, all the devices in iPTT are connected via internet. Floor control is an important function in PTT service. When more than one user wants to speak and pushes the button, the floor owner should be decided by the function of floor control. At present, some distributed floor control mechanisms are proposed. In this thesis, we propose some performance evaluation indexes for distributed floor control mechanisms. We try to observe the advantages and drawbacks of existing distributed floor control mechanisms through network simulation tool. We want to provide reference resources for people who will design new floor control approaches.

並列關鍵字

push-to-talk ； voice over IP ； group communication ； distributed system ； floor control

參考文獻

[3] Goode, B., “Voice over Internet Protocol (VoIP),” Proceeding of the IEEE, vol. 90, no. 9, 2002.

[6] IETF. SIP: Session Initiation Protocol. IETF RFC 3261, 2002.

[12] O’Regan, E., and Pesch, D., “Performance Estimation of a SIP based Push-to-Talk Service for 3G Networks”, European Wireless Conference (EW), Barcelona, February 2004.

[13] Parthasarathy, A., “Push to talk over cellular (PoC) server”, IEEE Proceedings, Networking, Sensing and Control 2005, pages 772–776, March 2005.

[16] Stoica, I., Morris, R., Karger, D., Kaashoek, M. F., and Balakrishnan, H., “Chord: A scalable peer-to-peer lookup service for Internet applications.” In Proc. ACM SIGCOMM’01, San Diego, CA, Aug. 2001.

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隨按即說服務之分散式發話權控制之效能分析

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