W-CSCF 之設計及其應用

Abstract

近年來，第二代無線通訊系統已經在全世界發展成熟了，然而，第二代行動使用者渴望著更多的服務來豐富他們的生活。因此，一個新的行動技術；第三代無線通訊系統被發展來提供更高階的服務。第三代通訊發展團體 (3rd Generation Partnership Project，3GPP) 定義了一個網際網路通訊協定多媒體子系統 (IP Multimedia Subsystem，IMS) 來提供多媒體服務，包括語音、影像、即時雙人遊戲、多媒體視訊會議等服務。通話控制功能 (Call Session Control Function，CSCF)是 IMS中最重要的一個功能接點，有三種CSCF被定義：代理伺服器通話控制功能 (Proxy CSCF，P-CSCF)， 保護通話控制功能(Interrogating CSCF，I-CSCF)，和 服務通話控制功能(Serving CSCF，S-CSCF)。 在本論文中，我們提出一個無線區域網路之呼叫通話控制功能(WLAN-based CSCF，W-CSCF)，整合IMS中的I-CSCF 和 S-CSCF，使得無線網路的使用者也能使用到IMS系統所提供的服務。而無線網路使用者必須先透過無線區域網路之封包無線服務端點 (WLAN-based GPRS Support Node，WGSN) 才能連結到W-CSCF。另外，我們實作及按通話 (Push-to-talk，PTT) 這個服務來驗證我們所設計的W-CSCF。並且，我們提出一個方法使得發話者能夠事先得知受發端使用者目前的狀態，進而減少通話錯失的可能。

In recent years, the second generation mobile communication system (2G) is becoming matured worldwide. However, the 2G mobile users may desire more services to facilitate their life. Therefore, a new mobile technology called the third generation (3G) has been developed to provide more value-added applications. The Third Generation Partnership Project (3GPP) defines the IP Multimedia Subsystem (IMS) to support multimedia services, such as voice telephony, video, real-time interactive games and multimedia conferencing. Call Session Control Function (CSCF) is the main function entity in 3G IMS. Three kinds of CSCFs are defined: Proxy CSCF (P-CSCF), Interrogating CSCF (I-CSCF) and Serving CSCF (S-CSCF). In this thesis, we propose a WLAN-based CSCF (W-CSCF) which integrates the I-CSCF and the S-CSCF in the IMS to provide WLAN users to access IMS services. The WLAN user can connect to W-CSCF through WLAN-based GPRS support node (WGSN). We have implemented the Push-to-talk (PTT) service to demonstrate the design of W-CSCF. Moreover, a PTT user is constantly informed the status of the users in the PTT Group to which the user is belonged.