Connectivity of wireless sensor nodes in metal rich environment: Expectations and reality

Connectivity among the nodes of a wireless sensor network (WSN) is essential for reliable transfer of sensed data. Existence of theoretical or empirical radio pathloss models are indispensable for optimal design of WSN. This paper covers the following topics: a)Radio channel measurements and characterization in difficult propagation environment. Measurements are performed in metal rich environment, in particular on a metal bridge segment. Signal pathloss is determined in 868MHz ISM band; b) End-to-end performance measurements in the same environment using commercial (off-the-shelf) communication nodes based on CC1101 transceiver operating at 868MHz band. c) Expected performance based on the measured signal pathloss is compared with actual performance of off-the-shelf nodes. Results presented in this paper were deployed for design and simulation of WSNs used in asset monitoring applications, in particular integrity monitoring of metal bridge structures.