Relay node placement in wireless sensor networks for pipeline inspection

Wireless sensor networks (WSNs) provide an effective approach for underground pipeline inspection. Such WSNs comprise of sensor nodes (SNs) and relay nodes (RNs) for information sensing and communication. WSNs can perform accurate and realtime inspection, especially in adverse environments. However, transmitting information between underground and aboveground nodes is very challenging due to the mobility and limited energy supply of the SNs as well as complex radio propagation environment. Therefore, proper deployment of a WSN is critical to provide reliable communications and efficient inspection. This paper presents a methodology for deploying aboveground RNs in WSNs. Specifically, it provides an optimum placement of RNs along with energy use so as to allow reliable communications. This method takes into account characteristics of the wireless channels, energy consumption, pipeline coverage requirements, and SN's transmission power levels. The paper provides a path loss model for radio propagation over multiple transmission media and an algorithm for optimization of RN placement and SN's transmission power. Simulation results show the efficacy of the proposed framework.