DFT-spread-OFDM with symmetric extension and frequency-domain spectral shaping (FDSS) for 6G nonlinear satellite downlink

The integration of satellite technology into 5G networks via 3GPP Release 17 enables seamless connectivity in previously unserved regions, but also introduces physical layer challenges such as a high peak-to-average power ratio (PAPR) in OFDM-based waveforms. To address these issues, this paper evaluates frequency-domain spectral shaping (FDSS), an enhancement of DFT-spread-OFDM, for satellite links. Comprehensive link-level simulations are conducted to assess FDSS performance under nonlinear satellite channel conditions, focusing on metrics like out-of-band emissions, error vector magnitude (EVM), and total degradation (TD) across varying power amplifier output back-off (OBO) levels. Results show that for our configurations, FDSS reduces the PAPR by up to 6 dB compared to OFDM and improves both ACLR and EVM compared to conventional OFDM and DFT-s-OFDM, supporting higher efficiency and robustness in non-terrestrial networks. These findings highlight FDSS as a promising candidate waveform for future 6G satellite-integrated systems.