Research On Application Of Broadcasting Technology In Mobile Databases

The development and combination of the computer technology and wireless communication technology make it possible a bran-new computing environment—mobile computing becomes realistic. In mobile computing environment, people hope they can access information or data anywhere and anytime. But there are new challenges for the data transmission, organizing, accessing and management. Because of the inherent properties of the mobile environment such as mobility, frequent disconnection, low bandwidth of the wireless network, network heterogeneity, unbalanced network communication, user scalability, limited power etc. So, many concepts on mobile databases have been proposed. The study of mobile database has become a hot spot.Because the wireless mobile communication network is unbalanced and requires good scalability of users, it's suitable to transfer information with the data broadcast method in mobile computing environment. In order to reduce turning time in the mobile clients, indexes can be added into the broadcast. But the addition of index increases the length of the broadcast message, thus increase the access time of mobile clients. People have made a lot research and put forward many methods of broadcast turning on reducing accessing time. However, how to optimize both tuning time and accessing time of mobile clients has become a tough researching topic on broadcasting technology.In order to improve average responding time, reducing the usage of network bandwidth and improve data availability, mobile clients usually cache part of the data locally. This paper make some improvement based on PIX Algorithm to decide which data should be cached. And, at the same time, how to keep cache consistent is an important study topic. We use the method based on broadcasting cache invalidating report form the servers to keep caches consistent. Many paper have posted the method on periodically broadcasting cache-invalidating reports and promptly broadcasting cache invalidating reports. We provide a method on broadcasting cache invalidating reports with variant periods and analyses its performance and availability.