Direct Satellite Access Using Multi-Dimensional Constellations

Cellular communication systems are currently evolving to provide non-terrestrial networks (NTNs) connectivity. However, due to large link path loss and realistic antenna capabilities of commercial smartphones, direct access to low Earth orbiting (LEO) satellites can so far only provide very small data rates. In this paper, we investigate the potential in using multi-dimensional constellations (MDC) for improving NTN connectivity. MDC allows non-coherent detection over coherent fading blocks, which can reduce the pilot overhead for channel estimation and remove sensitivity to channel estimation quality in low signal-to-noise ratio links. Our simulation results show that the considered MDC scheme can almost double the data rate compared to a NR-type scheme in the considered coverage-limited LEO scenario of small transport block transmission under NTN line-of-sight channel.