隨按即說服務於移動式隨意網路之分散式發話權控制效能分析

Performance Evaluation of Distributed Floor Control for Push-to-Talk Service over MANET

湯雅淳(Ya-Chun Tang)

指導教授 ： 逄愛君

國立臺灣大學/電機資訊學院/資訊工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10374

摘要

隨按即說(Push-to-talk或簡稱為PTT)服務可提供群組通訊，讓使用者之間透過一對一或是一對多的方式互相溝通。PTT類似於傳統的無線對講機，屬於半雙功通訊，也就是在同一個時間點，群組內只允許一名使用者說話，而其他使用者只能聆聽。PTT最主要的特色在於，使用者之間的通訊可以藉由簡單的按下通話按鈕而快速被建立，並不需要其他複雜的設定。目前，針對行動通訊網路，OMA(Open Mobile Alliance)組織的PoC(Push-to-talk over Cellular)計畫已訂定出PTT服務相關的通訊協定規格。OMA所訂的PoC規格是採取集中式的架構，其缺點為需要額外的成本來維護伺服器運作以及受限於伺服器能力的系統擴充度與系統可靠性。因此，有別於OMA作法，另一套採取點對點技術的服務模式被提出，在此分散式架構中，每個裝置之間是透過網際網路互相通訊。在PTT服務中， 發話權控制(Floor control)是一個相當重要的功能。當群組中同時有多名使用者按下通話按鈕時，系統會決定出唯一一個能獲得發話權的使用者。目前的無線網路中，移動式隨意網路因其不需任何基礎建設容易建構的特性而成為許多應用的最佳選擇。在這篇論文中，我們訂定了一些評估分散式floor control效能的指標，並且利用知名的網路模擬軟體NCTUns，設計不同的模擬實驗並觀察分散式floor control在移動式隨意網路上運作的優缺點。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 ； 移動式隨意網路 ； 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 communications. PTT is similar to the traditional walkie-talkie system which is a half duplex communication — while one person speaks, the other(s) just listen. 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. 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 PoC servers is required and scalability and reliability are limited by PoC servers. Different from PoC centralized approach, a distributed peer-to-peer (P2P) mode has been proposed. In P2P PTT, floor control is a critical function to service quality. When more than one user wants to speak and pushes the button, the floor owner should be quickly and properly decided by floor control. The ease of deployment makes Mobile Ad hoc NETwork (MANET) become very popular for many kinds of applications. In this thesis, we propose some performance evaluation indexes for distributed floor control over MANET, and investigate the performance of distributed floor control over MAN through a well-known network simulation tool. The simulation results indicate some guidelines for future design of distributed floor control over MANET.

並列關鍵字

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

參考文獻

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

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

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

[12]Wang, S.-Y., Chou, C.-L., and Lin, C.C. “The Design and Implementation of the NCTUns Network Simulation Engine”, Elsevier Simulation Modelling Practice and Theory, 15 (2007) 57 – 81.

[13]Wang, S.-Y., and Lin, Y.-B., “NCTUns Network Simulation and Emulation for Wireless Resource Management”, Wiley Wireless Communications and Mobile Computing, Vol.5, Issue 8, December 2005, pp. 899–916.