Minimal Relay Node Placement for Ensuring Network Connectivity in Mobile Wireless Sensor Networks.

Connectivity is one of the most challenging issues in Wireless Sensor Network (WSN). Connectivity problems in WSN seek to guarantee a satisfactory communication capability where all mobile sensors can connect to a base station via relay nodes in all data gathering events. In this paper, we focus on minimizing the number of relay nodes while ensuring connectivity in Mobile Wireless Sensor Networks. We propose an improved heuristic algorithm named Clustered Steiner Tree Heuristic (CSTH) to solve this problem in two phases. The first phase is Node Anchoring, which utilizes a greedy approach to find anchor points among clusters of mobile sensors. The second phase is called Steiner Relay Placement, in which a Steiner tree-based heuristic is used to minimize the number of relay nodes while maintaining connectivity in each cluster. Experiments were performed to compare CSTH with previous state-of-the-art heuristics for the problem. Results show that our algorithm can significantly improve the number of required relay nodes as well as computation time.