Browsing by Author "Tsai, Meng-Hsun"

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Active Location Reporting for Emergency Call in UMTS IP Multimedia Subsystem
(2009-01-01)
Tsai, Meng-Hsun
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Lin, Yi-Bing
;
Wang, Hsiao-Han
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資訊工程學系
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Department of Computer Science
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 paper 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.
Active Location Reporting for Emergency Call in UMTS IP Multimedia Subsystem
(2009-12-01)
Tsai, Meng-Hsun
;
Lin, Yi-Bing
;
Wang, Hsiao-Han
;
資訊工程學系
;
Department of Computer Science
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 (ECSCF). 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 paper 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.
Bearer Reservation with Preemption for Voice Call Continuity
(2009-01-01)
Tsai, Meng-Hsun
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Dai, Hui-Wen
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資訊工程學系
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Department of Computer Science
In Universal Mobile Telecommunications System (UMTS), the core network consists of two service domains: the circuit-switched (CS) and the packet-switched (PS) domains. A call can be set up in either the CS or the PS domain. This call may be switched (transferred) between the CS and the PS domains. A major concern of domain transfer is the switching overhead. In this paper, we propose the Bearer Reservation with Preemption (BRP) scheme to support fast domain transfer, and propose a simulation model to investigate the BRP performance. Our study shows that when user behavior is irregular, the BRP scheme can effectively reduce the re-connection overhead.
Bearer Reservation with Preemption for Voice Call Continuity
(2009-05-01)
Lin, Yi-Bing
;
Tsai, Meng-Hsun
;
Dai, Hui-Wen
;
Chen, Yuan-Kai
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資訊工程學系
In Universal Mobile Telecommunications System (UNITS), the core network consists of two service domains: the circuit-switched (CS) and the packet-switched (PS) domains. A UNITS handset can initiate or receive a call in either the CS or the PS domain. During the call, the user may switch from one domain to another. The switching overhead is an important concern of domain transfer. In this paper, we propose the Bearer Reservation with Preemption (BRP) scheme to support fast domain transfer, and present both analytic model and simulation experiments to investigate the BRP performance. Our study indicates that when user behavior is irregular (i.e., either the variance of the domain residence times or the variance of the call holding times is large), the advantage of the BRP scheme becomes significant.
Eavesdropping through mobile phone
(2007-11-01)
Lin, Yi-Bing
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Tsai, Meng-Hsun
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資訊工程學系
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Department of Computer Science
Mobile telecommunication services have become very popular recently, and many people bring mobile phones with them wherever they go. However, we observe that mobile phones can be modified to become remote microphones for eavesdropping. The eavesdropping technique only requires modifications to the mobile phone to be spied on and does not require any network changes. This paper describes mobile-phone eavesdropping and analyzes how serious it can be. Based on our study, we provide suggestions to avoid being eavesdropped upon.
EFFICIENT ROUTING FOR INTERNATIONAL MOBILE CALL SETUP
(2010-08-01)
Gan, Chai-Hien
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Tsai, Meng-Hsun
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Lin, Yi-Bing
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交大名義發表
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National Chiao Tung University
Mobile telecommunications operators offer telephone services when the subscribers roam to other countries. However, a call setup to a roaming mobile subscriber may result in two expensive international trunk connections. In this article we propose a plug-in solution to avoid the international trunk connections. By adding public switched telephone network gateways, our solution does not need to modify the existing mobile telecommunications systems. In this solution a timer is defined to reduce the call drop probability. A prediction method is proposed to determine the timeout period such that the call drop probability is limited within an acceptable range. Numerical experiments are conducted to indicate the performance of the prediction method. Finally, a prototype implemented at National Chiao Tung University is described.
IMS EMERGENCY SERVICES: A PRELIMINARY STUDY
(2011-02-01)
Lin, Yi-Bing
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Tsai, Meng-Hsun
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Tu, Yuan-Kuang
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資訊學院
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College of Computer Science
Emergency call and walkie-talkie are two services utilized in emergency situations. During Typhoon Morakot in 2009, we experienced the deficiency of emergency call service that cannot continuously track callers in real time and walkie-talkie communications where a speaker may not be granted the permission to talk. These issues can be resolved by the emergency call and push-to-talk over cellular services in IP Multimedia Subsystem. This article conducts a preliminary study on how these two services can be effectively exercised in IMS.
Talk burst control for Push-to-talk over Cellular
(2008-07-01)
Tsai, Meng-Hsun
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Lin, Yi-Bing
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資訊工程學系
;
Department of Computer Science
Push-to-talk over Cellular (PoC) is a "walkie-talkie"-like service designed for mobile networks. In this service, the speak permission is arbitrated through the talk burst control (TBC) mechanism. This paper proposes an analytic model to study the performance of the TBC mechanism with queueing and without queueing. This analytic model is validated against simulation experiments. Through numerical examples, our study provides guidelines to set up the parameters for PoC service.