Virtual Center: A characteristic of minimum power broadcast trees in wireless ad hoc networks

In this paper, we explore the structure of optimal solutions of minimum power broadcast tree problem in wireless ad hoc networks and present a new algorithm based on the findings. Our previous work shows that the optimal solutions have common characteristic (Incremental Minimality) which makes it reasonable to design an incremental algorithm to find the minimum power broadcast trees. In this work, we identify one more characteristic (Virtual Center) which complements the incremental minimality. The optimal solutions tend to have a major subtree which can be obtained by an incremental method starting from a center node which may not be the source node of the broadcast. Our finding is about the center node (called as virtual center) and the major subtree (called as virtually centered subtree) rooted at the virtual center. We propose a new algorithm which is based on the concept of virtual center by dynamically changing the center to find the best candidate for the virtual center. The proposed algorithm effectively utilizes the Virtual Center characteristic and the empirical computation results support the validity of the characteristic by superior performance compared to algorithms in literature.