Modeling credit reservation procedure for UMTS online charging system

Sok Ian Sou*, Hui-Nien Hung, Yi-Bing Lin, Nan Fu Peng, Jeu Yih Jeng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


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.

Original languageEnglish
Pages (from-to)4129-4135
Number of pages7
JournalIEEE Transactions on Wireless Communications
Issue number11
StatePublished - 1 Nov 2007


  • Charging
  • IP multimedia core network subsystem (IMS)
  • Prepaid services
  • Universal mobile telecommunications system (UMTS)


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