NEC · 10.5.1.2

NEC proposes Zadoff-Chu (ZC) based sequences as the baseline for 6GR PRACH preamble and considers both long and short NR PRACH preamble formats as starting points. They propose studying configuration of multiple PRACH formats per cell/carrier and increasing PRACH capacity from 64 to 128 candidate sequences. NEC questions whether PRACH configuration should remain under the BWP framework and proposes studying a simplified SSB-RO mapping mechanism or separate PRACH resource allocation per SSB. They require 4-step RACH procedure as baseline and prioritized, while proposing studies on reducing Msg2 payload size and introducing group common Msg4 to handle increased preamble numbers. For energy efficiency, NEC proposes a reference time (SSB or SIB1 transmission time) for clustered PRACH transmission with two options: relative configuration or default availability of only the first resource set(s). They propose studying PRACH resource adaptation with granularities including association period, PRACH periodicity, and SSB index. For coverage, NEC proposes native support of Msg1/2/3/4/5 repetition with joint repetition scheme to avoid resource fragmentation, and separate RSRP threshold configuration per SSB index for PRACH repetition.