A Connected Dominating Set (CDS) can serve as a virtual backbone for a wireless sensor network since there is no fixed infrastructure or centralized management in wireless sensor networks. With the help of CDS, routing is easier and can adapt quickly to network topology changes. The CDS problem has been studied extensively in undirected graphs, especially in unit disk graphs, in which each sensor node has the same transmission range. However, in practice, the transmission ranges of all nodes are not necessarily to be equal. In this paper, we model a network as a disk graph where unidirectional links are considered and introduce the Strongly Connected Dominating Set (SCDS) problem in disk graphs. We propose two constant approximation algorithms for the SCDS problem and compare their performances through the theoretical analysis.
Ding-Zhu Du, My T. Thai, Yingshu Li, Dan Liu, Shiw