  When different radio applications share the same spectrum, the separation by
attenuating material is a way to mitigate potential interference. The indoor
restriction for WLAN devices in 5150-5350 MHz is an example for a regulatory
measure that aims at having WLAN devices operating in an environment that
provides sufficient attenuation to enable sharing with other services. In this
paper we investigate whether an attenuating environment can be automatically
detected without user interaction. Instead of detecting an indoor location, we
are directly looking for a detection of an attenuating environment. The basic
idea is that signals from global navigation satellite services (GNSS) can be
received practically everywhere on earth where there is a view to the sky.
Where these signals are attenuated, the receiving device is assumed to be in an
attenuating environment. In order to characterize such environment, we evaluate
the detectable GNSS satellites and their carrier-to-noise density. Example
measurements show that GNSS raw data can help to distinguish between
low-attenuating locations and higher-attenuating locations. These measurements
were conducted with GNSS receiver in an off-the-shelf Android tablet in order
to show the feasibility of the approach.
