  3GPP is finalising the first release of the 5G New Radio physical layer. To
cope with the demanding 5G requirements on global connectivity and large
throughput, Satellite Communications might be a valuable resource to extend and
complement terrestrial networks. In this context, we introduce an integrated
architecture for 5G-based LEO mega-constellations and assess the impact of
large Doppler shifts and delays on both the 5G waveform and the PHY/MAC layer
procedures.
