Experimental spectrum sensor testbed for constructing indoor Radio Environmental Maps

In this paper we describe an experimental testbed to empirically study the construction of Radio Environmental Maps (REMs) in indoor environments. The testbed allows investigating the characteristics and modeling of the radio environment for indoor scenarios. The deployed system is a network of over 80 heterogeneous wireless spectrum sensors with significantly different measurement capabilities in an office building consisting of multiple rooms. As application examples we consider two scenarios, one illustrating the indoor propagation conditions and another showing temporal aspects of primary node activities as observed by sensing devices. The observed phenomena strongly indicate that development of general radio environment map solutions for indoor use are extremely challenging, unless heterogeneity of spectrum sensors and non-linearity of propagation conditions is considered. Our measurement results advocate dynamic construction of REMs instead of static solutions. We strongly believe that the deployed testbed and obtained experimental data can further facilitate research in the area of REMs.