Relay Node Placement in Wireless Sensor Networks: From Theory to Practice

The increasingly wide utilization of Wireless Sensor Networks (WSNs) in industrial applications outstands the significance of the Delay Constrained Relay Node Placement (DCRNP) problem. The unreliable and unpredictable wireless links in WSNs may lead existing algorithms to fail in practice. Therefore, we first conduct extensive real-world deployments under the guidance of existing algorithms to evaluate their performance and to gain some insights for designing practical deployment algorithms. Based on the experiences learned from practical experiments, we first devise a Set-Covering-based Algorithm (SCA) which figures out the DCRNP problem while trying to make the quality of each link better than a given threshold. As our experiments also show that the fault-tolerant topology can significantly improve network reliability, we then design a $k$ -Set-Covering-based Algorithm ( $k$ SCA) to build fault-tolerant WSNs based on the methodology of SCA. Furthermore, the elaborate analysis proves that both SCA and $k$ SCA are polynomial-time algorithms, and their approximation ratios are $\text{O}(\ln n)$ and $\text{O}(\lg n)$ , respectively, where $n$ is the number of sensor nodes. Finally, extensive experiments are performed under the guidance of SCA and $k$ SCA to demonstrate the effectivenesses of these two algorithms.