Characterisation of the Satellite-to-Indoor Propagation Channel

Reliable propagation models are required for the design of satellite broadcast to mobile or satellite navigation systems at S-band in the indoor environment. In particular, these models will support the development of hybrid satellite systems including complementary ground components. Apart from the effects of shadowing and multipath encountered in LMS (land mobile satellite) urban and suburban environments, the satellite-to-indoor channel is affected by high building penetration losses, but also lower Doppler spread due to static or quasi-static situation of the user terminal. Results from a measurement campaign simulating a satellite-to- indoor link are presented. Cluster-based wideband measurements were carried out with a channel sounder placed inside several buildings (airports, shopping mall, office buildings...), receiving the signal from the transmitter located in a helicopter hovering over the building at different (azimuth, elevation) combinations in igloo configuration. The measured data has been analysed with direct methods and iterative super-resolution algorithm in order to derive building penetration losses, time spreading and angle-of-arrival information. Super-resolution techniques make it possible to identify rays and clusters of rays, and thus give added value to the development of models. The super-resolution information is effectively used for evaluation of inter-cluster and intra-cluster azimuth angle of arrival distributions. The availability of spatial information in MIMO and SIMO measurements helps developing and validating site-specific models based on ray-tracing techniques given that the measured echoes are fully characterized in terms of amplitude, phase, delay and angle of arrival. Furthermore, the parameters corresponding to a directional statistical channel model have been extracted for each scenario thanks to the availability of this type of information. The results obtained contribute to a better characterisation of the satellite-to-indoor propagation channel.