The rapidly expanding technology of cellular communications, wireless LAN, and satellite services will give mobile users the capability of accessing information anywhere and at any time. This new computing paradigm is called mobile computing. Database systems, wireless communication technologies and advanced applications have give rise to new and challenging problems which have to be dealt with in mobile database system. The existing replication control methods cannot cope with the new characteristics that arise in a mobile environment since the existing replication control method did not reflect the impact of roaming. This paper proposes and discusses modifications that have to be made to replicated database management strategies in order to address the effect of mobility on the existing replication control schemes.
In this paper we propose the replication control scheme/fixed primary (RCS/F) for mobile database system. Firstly, to reflect a property of frequently disconnection, we added new operations include connect, disconnect and urgent. Second, to reduce a wireless communication overhead, we adopt the deferred writing scheme in RCS/F. Lastly, to improve stability, we have suggested one possible variation to the primary copy method, the fixed primary copy method, where the static host acts as the primary copy site constantly.
We examined the performance evaluation of deferred writing scheme compared to immediate writing scheme. Our experimental results showed that the deferred writing scheme outperforms the immediate writing scheme under a wide variety of write ratios and communication delays.
