Research On Data Dissemination In Mobile Computing Environment

With the development of wireless communication technologies, the applications of mobile computing are more and more wide. People can access information any time, any where via wireless networks. However, 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. Due to these features, the traditional request-response data dissemination technology is no longer suitable for mobile computing environment. Therefore the research on data dissemination in mobile computing environment has important significance in both theory and practice.In this paper, an adaptive hybrid broadcast algorithm is proposed, which focuses on the channel and data allocation of periodic broadcast and on-demand broadcast. Due to the skew feature of clients' access pattern, the algorithm adopts skewed data allocation in periodic broadcast channels, which makes frequently requested items broadcast more frequently. While determining the number of periodic broadcast data and on-demand broadcast data, the algorithm considers the relationship between the response time of on-demand broadcast channels and the requests arrival rate, and gets the optimal cut-point after a spot of comparison. According to the changes of system load and clients' access patterns, the adaptive hybrid broadcast algorithm can adjust the channel and data allocation and minimize the average access time.Tuning time is used to indicate the energy consumption of mobile hosts. Decrease tuning time can increase the use time of mobile hosts. After the algorithm determines the channel and data allocation, periodic channels adopt index to decrease tuning time.The performance of the adaptive hybrid data broadcast algorithm is analyzed by simulation. Experimental results show that the proposed approach performs better than other scheduling algorithms on average access time. The index in periodic channel decreases tuning time.