An efficient data placement for query-set-based broadcasting in mobile environments

Broadcast is an efficient and scalable method for resolving the bandwidth limitation in a wireless environment. Because the ordering of data items on a broadcast channel affects clients’ access time, deciding data placement in a broadcast channel to reduce clients’ access time is an important issue. Most previous research assumes that each mobile client needs only one data item. However, in many situations, a mobile client might need more than one data item. In this paper, we present a two-stage scheme of initial placement generation and placement refinement to solve the placement problem for query-set-based broadcasting in mobile environment. The first stage employs a constructive method to obtain an initial placement; data items are scheduled using an eigenvector optimization method. The second stage applies a simulated annealing approach to improve the initial placement. Experimental results show that our approach outperforms QEM [7] and IQEM [3] methods in total access time.