Research Of Technology About Data Broadcast In Mobile Database

In pace with rapid development in the computer technology, the mobile communication technology and the Internet technology, the mobile database is extensively applied. In the public information issue application, the widespread database system issue data through the broadcast to the client side, the client side monitor the broadcast channel, the client side reading the required data when data arrival. It is very important to gain the most recent data to the mobile client, the visits of the obsolete information is insignificant, therefore the broadcast is more advantageous to service data fresh and the validity. Meanwhile in the wireless unit, the downstream communication always far more than the upstream communication, moreover the expenses of the mobile client accepts data from the server also far to be smaller than the transmission expenses, even if under the separation condition, the mobile client also to be possible to selective receive the broadcast data which transmits from the server. Therefore, may use this kind of the asymmetry of the network, the data server organize the data which the mobile client interested, and sent to the mobile client by the periodic broadcast.In the data broadcast, the visits probability of the data record is various, therefore the index tree may be built through visit probability. The structure of the index tree decides the average index number to be visited, but even regarding the same index structure, the average visit time is different if the broadcast sequence is different. If we want to design the most superior broadcast sequence for the existed index structure, we should consider not only the existed index point, but also the structure of the index tree. The mobile client may selectively to intercept the channel by the index broadcast, the average cost can be reduced through the establishment base on the data accessing probability of the index tree.This dissertation according to the character of the different visit probability of the record in the data broadcast, through the research on index broadcast technology of the data broadcast, including the existed index tree base on the data accessing probability, and introduce the data broadcast algorithm with very low data average...