Abstract
5G and future cellular networks intend to incorporate low earth orbit (LEO) satellite communication systems (SatCom) to solve the coverage and availability problems that cannot be addressed by satellite-based or ground-based infrastructure alone. This integration of terrestrial and non terrestrial networks poses many technical challenges which need to be identified and addressed. To this aim, we design and simulate the downlink of a LEO SatCom compatible with 5G NR, with a special focus on the design of the beamforming codebook at the satellite side. The performance of this approach is evaluated for the link between a LEO satellite and a mobile terminal in the Ku band, assuming a realistic channel model and commercial antenna array designs, both at the satellite and the terminal. Simulation results provide insights on open research challenges related to analog codebook design and hybrid beamforming strategies, requirements of the antenna terminals to provide a given SNR, or required beam reconfiguration capabilities among others.
Highlights
Integrated satellite-terrestrial cellular networks are currently being pursued for long awaited commercial applications
We propose and evaluate a massive MIMO low earth orbit (LEO) satellite communication system operating in the Ku band, based on a hybrid beamforming architecture
We consider a LEO satellite orbiting at a 1,300 km height, covering an ellipsoidal regions of interest (ROI) with semiradius 534.1 and 170.5 km
Summary
Integrated satellite-terrestrial cellular networks are currently being pursued for long awaited commercial applications. LEO constellations seem to be the most promising platforms for satellite-based non-terrestrial networks (NTNs), due to their relatively shorter propagation delay (Kodheli et al, 2017). This propagation delay between ground terminals and LEO satellites (3 ms at 1,000 km above the Earth surface) is nonnegligible, LEO constellations can support continuity and ubiquity of the radio services, and latency critical applications with requirements within tens of ms. Digital precoding stages are designed independently of the analog beam with the purpose of reducing inter-beam interference among the beams illuminating adjacent regions of interest (ROI) (Devillers and Pérez-Neira, 2011) These solutions assume that a single satellite is illuminating a large specific ROI, and handover procedures are put in place to enable satellite switching at the user side before the satellite movement causes loss of coverage
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