Nokia · 10.5.1.2

Nokia proposes retaining Zadoff-Chu as the PRACH sequence due to its CAZAC properties and robustness against frequency offset, while opposing sequences that lack these characteristics. For PRACH configuration, they recommend studying parametrized PRACH format configuration against static formats definitions and support reduced table-based PRACH configurations with separately configurable parameters to enable RO clustering and time adaptation. They require a unified design for terrestrial and non-terrestrial networks where feasible, and propose that SBFD RA support should not increase complexity of basic TDD RA operation. For RACH procedure, they propose 4-step RACH as the sole baseline, requiring Msg3-based identification as the default and restricting Msg1-based identification to coverage extension and OD-SIB1 use cases. For AI/ML, they propose reusing Rel-18/19 BM-Case1 (Spatial-Domain Beam Prediction) and BM-Case2 (Temporal-Domain Beam Prediction), prioritizing spatial beam prediction over temporal, and present simulation results showing 64-65% relative reduction in MSG1 failures using spatial beam prediction compared to classical methods.

Nokia proposes Zadoff-Chu sequences for 6G PRACH preamble due to CAZAC property and frequency offset robustness, and refrains from sequences lacking good cross-correlation under timing errors. They propose 4-step RACH as the sole baseline procedure, with Msg3-based identification as baseline and Msg1-based identification restricted to limited use cases. For the 7 GHz frequency range, they require short PRACH formats based on 30 kHz SCS (baseline from NR) and long PRACH formats based on 5 kHz SCS. They propose supporting PRACH and PUxCH overlapping to enhance RACH capacity through increased time-domain allocations. They propose studying AI/ML-based Spatial-Domain Beam Prediction (BM-Case1) for coverage extension and PRACH attempt reduction, and Temporal-Domain Beam Prediction (BM-Case2) for improving Msg2/3/4 transmission/reception in 4-step RACH.