Evaluation of a Real, Low Cost, Urban WSN Deployment for Accurate Environmental Monitoring

There are many areas where Wireless Sensor Networks (WSN) can offer innovative solutions for environmental monitoring applications and the meteorological community, but due to their complexity in terms of energy constraints and low performance devices, very few real deployments can be found. In this paper we will explain in detail the design, implementation and performance evaluation of a sparse WSN that has been working maintenance-free for over 12 months. The network has been designed for environmental monitoring purposes, and several motes, attached to lampposts, accurately measure the Temperature and Relative Humidity at various locations in a local street. Our contribution is an enhanced data gathering application for environmental applications. We will present the different arguments and tradeoffs to be taken into account when designing a network of this type, such as the type of sensors and their calibration, choice of mote and operating system, power supply, special housing required for the mote, data sampling frequency, requirements for the data sink, the structure of the database at the central site, and different issues relating to the exploitation of the meteorological results. We show that a reliable, low cost WSN deployment for environmental monitoring that takes into account the main properties of these networks, such multi-hop routing, low maintenance, low cost and long mote lifetimes, is achievable.