Mobile wireless sensor networks applied to the survey of water infrastructures

The paper reports our last advances in the realization of mobile wireless sensor networks (WSNs), able to reveal unknown tracks and leakages within underground pipelines used to distribute water. This WSN technology is based on a concept recently proposed by the authors, which makes use of mobile acoustic sensors able to flow within a pipe, transported by the fluid, and equipped with a wireless interface that reports the acquired information to the surface. The paper starts from the early and simplified realization that has been already presented to demonstrate the feasibility of the concept and describes the realization of advanced prototypes, using wireless modules that work in different frequency ranges with specifically designed antennas with the auxiliary possibility to track the position of the device. Ad-hoc solutions have been identified for the construction of the microwave front-end, allowing an improved stability despite the mobility and the rotations. Battery life, compared to application requirements, have been investigated and optimized. Moreover, the technology has been adapted to different operational contexts, making use of different choices of the Physical Layers and various transmission protocol optimizations. At last, results are presented and discussed.