Satellite-to-Indoor Broadband Channel Measurements at L- and C-band for GNSS Application

Kurzfassung

The global positioning system (GPS) made outdoor localisation broadly available and is widely employed for numerous applications. Low cost devices available on the mass market are able to track satellite signals with received power levels as low as −159 dBm. With these high sensitivity receivers (standalone or in combination with other sensors) indoor reception of GPS signals becomes possible in many cases. But position errors due to signal blocking, diffraction and refraction still impede navigation by a global navigation satellite system (GNSS) indoors, so new algorithms have to be developed to mitigate such errors. The first step towards new algorithms is to understand the propagation characteristics of the satellite-to-indoor channel. One possible approach to gain knowledge about the propagation medium is to perform channel sounder measurements. In such a measurement campaign the transmitted signal is known to the receiver and the channel impulse response (CIR) can be calculated straightforward. Because a measurement shows all details of the real propagation medium, channel sounder measurements for the satellite navigation multipath channel like in [1], [2] or [3] are substantially needed. Currently the European Space Agency is discussing the use of C-band at 5 GHz for navigation purposes in the European GNSS evolutions program [4] and [5]. To obtain insights into the wireless satellite-to-indoor channel characteristic, the German Aerospace Center (DLR) performed channel sounder measurements at centre frequencies 1.51 GHz (L-band) and 5.2 GHz (C-band) using a broadband signal with the goal to compare the propagation medium for a moving receiver. The approach taken for this measurement campaign is to use elevated transmitter positions. As this does not imply a high flying platform like a zeppelin as in [1] or a helicopter as in [2] or [6], the measurement campaign focused on wave propagation in and into the building rather than the complete satellite-to-indoor propagation.