Cubic Metric Reduction for Repetitive CAZAC Sequences in Frequency Domain

To meet the requirements of Occupied Channel Bandwidth(OCB)of unlicensed spectrum,in NR-based Access to Unlicensed Spectrum(NR-U)of 5G New Radio(NR)system,the channels of PRACH and PUCCH have to employ some frequency domain sequence repetition schemes.These repeti-tion schemes cause serious Cubic Metric(CM)prob-lems for these channels,although these two types of channels are composed of Constant Amplitude Zero Auto-correlation(CAZAC)sequences.Considering the properties of CAZAC sequences,which are used for PRACH and PUCCH(refer to PUCCH format 0 and format 1)in 5G NR system,in this paper,we pro-pose some new schemes of CM reduction for these two channels taking into account the design princi-ples to ensure the sequence performance of the auto-correlation and cross-correlation.Then the recom-mended CM reduction schemes are evaluated and the optimized parameters are further provided considering both CM performance and the complexity.