R1-2508647
discussion
On 6G waveforms
From Ericsson
Summary
Ericsson presents 18 observations and 6 proposals on 6G waveforms. In downlink, they argue against DFT-s-OFDM due to complexity and lack of advantage over CP-OFDM. In uplink, they propose enhanced evaluation methodologies for PAPR reduction and advocate for multi-layer DFT-s-OFDM transmission to improve coverage and throughput.
Position
Ericsson proposes deprioritizing the study of DFT-s-OFDM for the downlink, arguing it offers no significant advantage over CP-OFDM for use cases including NES, NTN, ISAC, and FR3, and would unnecessarily complicate 6GR system design and multiplexing of common channels/signals. For uplink low-PAPR techniques, they propose that evaluation methodology should include throughput metrics in addition to Net Gain to capture the best combination of frequency resources and MCS, and they require MPR-based system-level simulations for broader insights. Ericsson supports the introduction of multi-layer DFT-s-OFDM for uplink transmissions, presenting system-level simulation results showing up to ~125% cell-edge and ~20% median user throughput gains over CP-OFDM for 2TX UEs using specific power class and scaling models (PC3 Rel-16 MODE0, PC2 Rel-15). They argue that multi-layer DFT-s-OFDM and CP-OFDM are complementary and that supporting both avoids the added complexity of fast CP-OFDM/DFT-s-OFDM switching mechanisms for MIMO.
Key proposals
- Proposal 1 (Sec 2.1): RAN1 to deprioritize the study of DFT-s-OFDM for downlink due to lack of any significant advantage compared to CP-OFDM even for the potential use cases such as NES, NTN ISAC, and FR3, and for the transmission of common channels/signals as well as to keep the 6GR system design to a reasonable complexity.
- Proposal 2 (Sec 2.2.1.1): For uplink low-PAPR proposals, throughput should be evaluated in addition to Net Gain to select and compare the best combination of frequency resources (BW) and spectral efficiency (MCS).
- Proposal 3 (Sec 2.2.1.2): To obtain broader insights with respect to the evaluations of different uplink low-PAPR proposal for 6GR, RAN1 to consider MPR-based system-level simulations in addition to link-level simulations.
- Proposal 4 (Sec 2.2.2.1): RAN1 to consider system-level evaluations for studying the multi-layer DFT-s-OFDM in the uplink by accounting for MPR based on RF power class and RF power scaling models with system-level parameter settings in Table 4 as a starting point.
- Proposal 5 (Sec 2.2.2.1): RAN1 to consider at least UE power class 2 with Rel-15 power scaling model and power class 3 with Rel-16 MODE0 scaling for 2TX antenna configurations at the UEs in the system-level evaluations of multi-layer DFT-s-OFDM in the uplink.
- Proposal 6 (Sec 2.2.2.3): Support multi-layer DFT-s-OFDM and multi-layer CP-OFDM for uplink transmissions in 6GR.