Design, Implementation and Experimental Results of a Wireless Sensor Network for Underground Metro Station

Wireless sensor networks provide a prominent approach for environmental monitoring system in many different scenarios. Typically, sensors communicate through a mesh network architecture, in which each device functions also as a relay for other devices. The usage of multi-hop wireless paths raises the challenge of achieving robust communication and low energy consumption while optimizing the system maintenance costs due to battery replacements and network management. In this paper, we present the design and implementation of a wireless monitoring system deployed in an underground metro station, developed as a flexible cross-layer solution able to integrate time synchronization, duty-cycling and lightweight routing mechanisms. We provide detailed description of the system together with experimental results on the achievable energy efficiency improvement and on the adaptability of the routing protocol to the dynamicity observed in the station environment, providing relevant insights into properties and challenges of real WSN deployments.