Abstract: A queueing model is developed for the database system which supports mobility management in personal communication systems (PCS). The end-to-end service delay is defined as the performance metric. The accuracy of the analytical model is validated by simulation. It is found that the analytical results show a close agreement to those from simulation over a significant range of system parameters. Three database system architectures proposed for PCS are studied, namely, the flat database system in GSM, the two-level hierarchical architecture, and the three-level hierarchical architecture. Based on the queueing model, the delay performance of these three architectures are compared. It is observed that the hierarchical architecture provides the best system performance and supports the highest user density. This is because the service arrival rate to the higher level large database is significantly reduced, due to the localized nature of calls and users in PCS.