Data And Broadcasting Technologies In The Mobile Database Synchronization Study

The emergence and popularization of wireless communications, mobile device and Internet accelerate the development of mobile computing. Different from traditional distributed computing environment, the mobile computing environment has some distinct features: mobility, disconnection, weak connectivity, resource scarcity,diversity and asymmetry of network communication etc. These features restrict the use of existing classical database technologies in mobile environments, and produce new research fields. Due to the good expansibility, data broadcast is used in mobile computing widely. In this paper, several key technologies about data broadcast are investigated.Data broadcasting technologies optimized for the tuning time, using three-stage method analysis and discussion of the single-index algorithm and (1, m) indexing algorithm. Huffman proposed expansion of the index tree based on the d-Huffman tree to organize an alternative B + tree indexes can be better to reduce the tuning time, so as to achieve the purpose of energy saving.In the motion database system the data renewal and data broadcast concurrent processing, causes the motion customer read the data not to be possibly inconsistent, and proposed solves the above problem based on the UF0 mechanism concurrent control strategy. This strategy has the good independence, and its impact to the mobile clients is smaller, and the consistency of data values that are broadcasted to users are increased in larger extent. In order to enhance in the motion computation environment the buffer data efficiency,the strategy can adjust dynamically the frequency and content of data updating record according to the MC number and the data updating frequency, and the MCs will replace the data with its new value instead of clearing invalidated data item in the cache when they receive the update record. Through performance analysis of the approach, it can perfectly adapt to the mobile computing environment which data updating frequency changes continuously. In this thesis, we study the replacement algorithms of cache, and we provide an ideal replacement algorithm―2Q-PIX, which turns out to have better effects by experiments.