Abstract: Since maximal preamble arrival time difference is much more significant in satellite beam cells than that in terrestrial case, current preamble formats in 5G cannot be directly applied to B5G low earth orbit satellite networks, which can easily cause timing advance (TA) estimation failures. To cope with this challenge, by investigating 2-step TA estimation procedure and inter-preamble interference, an enhanced preamble format design is proposed, whose core idea lies in flexible cascading of sub-sequences and differential power allocation among them. Simulation results show that our proposal can achieve a much lower missed detection rate of preamble with TA estimation accuracy taken into account, compared with benchmarks when 32 users access and signal to noise ratio is -10dB, which decreases the failure probability of random access.

Key words: low earth orbit satellite, random access, preamble design, timing advance estimation