IMS 緊急電話之位置回報機制

Abstract

在UMTS (Universal Mobile Telecommunications System) 系統中，網際網路IP多媒體子系統 (IP Multimedia Subsystem; IMS) 負責提供多媒體服務。在IMS中，緊急電話是由E-CSCF (Emergency-Call Session Control Function) 所建立。E-CSCF會根據發話者所在位置轉接緊急電話到最近的公眾安全應變中心 (Public Safety Answering Point; PSAP)。在緊急電話建立完成後， PSAP會透過位置輪詢 (Location Polling) 機制來持續追蹤發話者的位置。本論文針對位置追蹤進行效能分析，並提出主動位置回報 (Active Location Reporting) 機制以提升位置追蹤的效能。研究結果顯示，主動位置回報機制在效能上較位置輪詢機制有顯著地改善。

The IP Multimedia Core Network Subsystem (IMS) provides multimedia services for Universal Mobile Telecommunications System (UMTS). In IMS, an emergency call is established by an Emergency-Call Session Control Function (E-CSCF). The E-CSCF dispatches the call to the nearest Public Safety Answering Point (PSAP) according to the location of the caller. After emergency call setup, the caller’s location is tracked by the PSAP through Location Polling. This thesis investigates the performance of location tracking. Then we propose the Active Location Reporting scheme to improve the performance of location tracking. Our study indicates that the Active Location Reporting scheme may significantly outperform the Location Polling scheme.