Reliability based optimization in hybrid wireless sensor networks

Sensor nodes in wireless sensor networks (WSNs) are usually battery-powered sensor nodes (BPSNs) and can rarely meet design goals such as network lifetime, energy and reliability. Energy-harvesting sensor nodes (EHSNs) are an alt ernative type of sensor nodes, which are capable of converting different types of energy to electrical energy. They have longer lifetime but higher cost than BPSNs. Combining BPSNs and EHSNs in a heterogeneous WSN has the potential to deal with the conflicting design goals. In addition, consider certain scenarios where replacing batteries of BPSNs is impossible, EHSNs can be deployed instead to satisfy the quality of service (QoS) of applications running on the hybrid WSN. In this work, we study a hybrid WSN including both types of sensor nodes to deal with the network reliability and cost requirements, particularly, the limited lifetime of BPSNs and high cost of EHSNs. The problem is to find the optimal locations for a specific number of EHSNs in the hybrid WSN with the objective to provide the best combination of average path reliability, implementation path cost, and average energy consumption based on the QoS requirements. Both the centrality concept and the multivariable nonlinear programming method are explored to find the optimal positions for EHSNs in the hybrid WSN.