  In NR-based Access to Unlicensed Spectrum (NR-U) of 5G system, to satisfy the
rules of Occupied Channel Bandwidth (OCB) of unlicensed spectrum, the channels
of PRACH and PUCCH have to use some sequence repetition mechanisms in frequency
domain. These repetition mechanisms will cause serious cubic metric(CM)
problems for these channels, although these two types of channels are composed
of Constant Amplitude Zero Auto-correlation(CAZAC) sequences.. Based on the
characteristics of CAZAC sequences, which are used for PRACH and PUCCH (refer
to PUCCH format 0 and format 1) in 5G NR, in this paper, we propose some new
mechanisms of CM reduction for these two types of channels considering the
design principles to ensure the sequence performance of the auto-correlation
and cross-correlation. Then the proposed CM schemes are evaluated and the
optimized parameters are further provided considering CM performance and the
complexity.
