LTE-based Satellite Communications in LEO Mega-Constellations

摘要

The integration of satellite and terrestrial networks is a promising solutionfor extending broadband coverage to areas not connected to a terrestrialinfrastructure, as also demonstrated by recent commercial and standardisationendeavours. However, the large delays and Doppler shifts over the satellitechannel pose severe technical challenges to traditional terrestrial systems, asLTE or 5G. In this paper, two architectures are proposed for a LEOmega-constellation realising a satellite-enabled LTE system, in which the on-ground LTE entity is either an eNB (Sat-eNB) or a Relay Node (Sat-RN). Theimpact of satellite channel impairments as large delays and Doppler shifts onLTE PHY/MAC procedures is discussed and assessed. The proposed analysis showsthat, while carrier spacings, Random Access, and RN attach procedures do notpose specific issues, HARQ requires substantial modifications. Moreover,advanced handover procedures will be also required due to the satellites'movement.