Unified Non-Orthogonal Waveform (uNOW) based on DFT-s-OFDM Enhancement for 5G Evolution and 6G

5G New Radio (NR) takes multi-carrier waveform orthogonal frequency division multiplexing with cyclic prefix (CP-OFDM) with high spectral efficiency (SE) as the core waveform, and only supports single-carrier waveform discrete Fourier transform spreading OFDM (DFT-s-OFDM) with high power efficiency (PE) when uplink coverage is limited. 5G Evolution (5GE) and 6G have diversified scenarios, including high-frequency bands and integrated space-terrestrial systems, in which the non-linearity of power amplifiers (PA) restricts the system design. Therefore, high PE or low peak to average power ratio (PAPR) becomes one of the most significant key performance indicators (KPI) for 5GE and 6G waveform design, in addition to the high SE requirement. In this paper, we propose a unified non-orthogonal waveform (uNOW) based on DFT-s-OFDM enhancement with time-domain compression and expansion (TD-CE) as well as frequency-domain spectral shaping (FDSS) to improve PAPR and SE performance, simultaneously. Firstly, we describe the uNOW transmitter structure and two receiver structures, i.e., the linear minimum mean squared error (LMMSE) time-domain equalization (TDE) for time-domain compression and enhanced LMMSE frequency-domain equalization (FDE) for time-domain expansion. Then, the basic principle of uNOW is analyzed, i.e., how TD-CE and FDSS affect the time-domain pulse-shapes to reduce PAPR. Simulation results show that when only TD-CE or FDSS is considered, both PAPR gain and throughput gain are achieved compared with DFT-s-OFDM. When considering both TD-CE and FDSS, the PAPR and throughput gain achieved by uNOW can be significantly improved. Therefore, uNOW can be considered as a promising waveform candidate for 5GE and 6G.