Reducing Credit Re-authorization Cost in UMTS Online Charging System

During an online charging general packet radio service (GPRS) session, a number of mid-session events, such as changes of quality of service (QoS), could dynamically affect the rating of the in-progress service. When such events occur, the GPRS support node needs to re-authorize the granted credit units with the online charging system (OCS). This paper proposes a threshold-based scheme that utilizes a threshold parameter delta to reduce the signaling traffic for the credit re-authorization procedure. By selecting an appropriate delta value, the signaling overhead in the OCS can be significantly reduced while the inaccuracy of the credit information insignificantly increases. The mobile operator can choose appropriate parameter values in the threshold-based scheme based on our study.