Performance of service-node-based mobile prepaid service

In the recent years, mobile prepaid service has become an important mobile application with rapid growth of subscription rate. The most widely deployed prepaid solution today is the service node approach that deducts and updates the prepaid credit during a phone call. Implementation of the service node approach may generate large number of credit checks that significantly degrades the performance of a service node. We investigate how the number of credit checks affects the workload of the service node and the bad debt that a service provider may bear. We propose an analytic model to derive the optimal credit checking/updating frequency for the service node approach. The analytic analysis is validated against simulation experiments. Our study indicates that the number of credit checks increases rapidly when the call pattern is irregular. We also observe that in order to reduce the checking cost of the service node, the prepaid service provider should encourage the customer to make long calls by giving them discounts.