| dc.description.abstract | With the recent advances in low earth orbit (LEO) constellation, satellite communication (SATCOM) has been included in Non-Terrestrial Network (NTN) and recognized as a promising solution to extend services to unserved area in 5G networks. 3GPP has also considered to develop NR-based NTN, however, part of NR functions should be re-worked duo to SATCOM inherent characteristics. In NR-based NTN, user equipments (UEs) are anticipated to be GNSS-enabled in NTN scenarios in NR Rel-17. Based on the aforementioned features, we propose three novel RACH Occasions (RO) patterns for LEO-NTN.
Though user terminals are assumed to have location information, we design RO patterns with backward compatibility, namely, users who is not aware of its own location are also considered. For UEs with or without GNSS capability (G-UE or nG-UE), we propose to schedule their RO separately, G-RO for G-UE, nG-RO for nG-UE. In this work, we propose three RO patterns that could be flexibly configured by the network. Specifically, scheduling G-RO and nG-RO with same periodicity, we propose RO pair, contrarily with different periodicity, we propose overlapped RO and non-overlapped RO.
To validate the effectiveness of proposed RO patterns, we review the preamble transmission delays through computer simulation. Advantages of scheduling G-RO and nG-RO separately are two-fold. Firstly, simulation results show that average delay of successful preamble transmission for all UEs is reduced. Secondly, nG-UEs are relatively more insusceptible to expected increment of G-UE number in the future. Moreover, we investigate the performance of overlapped RO with different preamble division ratio. | en_US |