2 GHz outdoor to indoor propagation at high elevation angles for mobile communications served by high altitude platform stations

High altitude platform stations have been recently proposed as a new means of providing international mobile communications (IMT-2000). One critical issue that has not been resolved yet is the possibility of providing indoor services. This paper examines the penetration into buildings loss at high elevation angles. Two approaches are followed: An empirical model is presented and evaluated through comparison with two measurement campaigns. Furthermore, a 3-D ray-tracing tool was developed In order to simulate a specific environment of 11 buildings and take into account parameters not modeled by the empirical method, such as rooftop diffractions. Both approaches conclude that the penetration loss is an increasing function of the elevation angle, but the range of values obtained shows that indoor coverage is feasible.