Browsing by Author "Peng, Nan-Fu"

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Deriving the Vehicle Speeds from a Mobile Telecommunications Network
(2013-09-01)
Liou, Ren-Huang
;
Lin, Yi-Bing
;
Chang, Yu-Long
;
Hung, Hui-Nien
;
Peng, Nan-Fu
Vehicle speeds are often measured by intelligent transportation systems (ITSs) by utilizing sensors or software solutions. Our previous work proposed the Lin-Chang-Huangfu (LCH) scheme to compute the cell residence times by the standard counter values in mobile telecommunications switches. In this paper, we use mathematical and statistical developments to investigate the accuracy of the LCH scheme by deriving the bias of the cell residence times computed in this scheme. Then, we extend the LCH scheme with some filtering and compensation techniques for vehicle speed estimation and validate our approach with vehicle detector (VD) measurements at National Highway 3, Longtan Township, Taoyuan County, Taiwan. Our study indicates that the LCH scheme is an effective approach to vehicle speed estimation.
Modeling credit reservation procedure for UMTS online charging system
(2007-11-01)
Son, Sok-Ian
;
Hung, Hui-Nien
;
Lin, Yi-Bing
;
Peng, Nan-Fu
;
Jeng, Jeu-Yih
The IP Multimedia Core Network Subsystem (IMS) provides real-time multimedia services for Universal Mobile Telecommunications System (UMTS). Through Recharge Threshold-based Credit Reservation (RTCR) mechanism, prepaid IMS services can be supported by the Online Charging System (OCS) in UMTS. In RTCR, when the remaining amount of prepaid credit is below a threshold, the OCS reminds the user to recharge the prepaid account. It is essential to choose an appropriate recharge threshold to reduce the probability that the in-progress service sessions are forced-terminated. An analytic model is developed to investigate the performance of RTCR for the OCS. Based on our study, the network operator can select the appropriate parameter values for various traffic conditions.