GNSS Independent Random Access Schemes for Beam Hopping Satellite Systems

This paper investigates the application of the random access procedure (RAP) to beam hopping satellite systems. Furthermore, modifications are proposed to support global navigation satellite systems (GNSS) independent operation in low Earth orbit (LEO) constellations. In such a case, the time and frequency offsets that stem from the orbital motion are not perfectly compensated during the RAP. To handle the residual errors, the pre-compensation mechanism and the physical random access channel (PRACH) have been modified. The experimental validation shows that the solution described in this work enables to realize the first step of the RAP in presence of user equipment (UE) positioning errors.