Abstract
Next generation satellite payload technology is expected to provide digital processing capabilities. This will pave the way to regard satellites as flying base stations. However, the initial access procedure must be improved. In this work we focus on non-geostationary earth orbit (NGEO) satellite networks. In this scenario, the random access preamble signal and the detection must be robust to large carrier frequency offsets (CFOs). Towards this end, we investigate the adoption of the pruned discrete Fourier transform spread filter bank multicarrier waveform. The proposed design is suitable for the access scheme of forthcoming 5G-based NGEO satellite communications. The reason is twofold. First, it improves the spectral confinement with respect to the standard single-carrier frequency-division multiplexing (SC-FDM) waveform. Second, it achieves a high level of commonality with 5G new radio, by keeping unchanged the subcarrier spacing, the slot duration and the preamble sequence. Remarkably, the new design allows the straightforward application of non-coherent post detection integration (NCPDI) techniques, which divide the correlation in blocks. Numerical results show that the proposed solution reduces out-of-band emissions and the missed detection probability in presence of CFO, with respect to the conventional approach based on SC-FDM and preamble detection with full-length correlation.
Highlights
W ITH the aim of providing service in remote areas and increasing service availability, it is envisioned that satellites will be an integral component of the forthcoming 5G networks
We have proposed a new random access preamble design, where the pruned DFT-s-FBMC scheme is used to convey the same ZC sequences adopted in 5G new radio (5G NR) [7]
We evaluate the random access procedure in presence of large carrier frequency offsets (CFOs) values, which are assumed to produce a constant rotation during the preamble transmission
Summary
W ITH the aim of providing service in remote areas and increasing service availability, it is envisioned that satellites will be an integral component of the forthcoming 5G networks. Ongoing activities and efforts are undertaken by 3GPP to go deeper into the role of satellites in 5G new radio (5G NR) [1] Towards this end, special attention must be paid to the characteristics of the satellite environment, such as Doppler effects, large path loss and long round trip delay (RTD). We focus the attention on nongeostationary earth orbit (NGEO) satellite communications In this scenario, if the UE knows the trajectory of the satellite and is equipped with a global navigation satellite system (GNSS) receiver, the Doppler frequency shift can be compensated. If the UE knows the trajectory of the satellite and is equipped with a global navigation satellite system (GNSS) receiver, the Doppler frequency shift can be compensated In such a case, no obstacles are foreseen to reuse the 5G NR physical random access channel (PRACH) waveform [7]. Depending on the altitude of the satellite and the beam size, the pre-compensation strategy may not be sufficient to cope with the Doppler effects
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