R1-2508564
discussion
Feature Lead summary #3 on 6G waveform
From Nokia
Summary
This is the Feature Lead summary document (R1-2508564) from Nokia, serving as moderator for the 6G waveform study in 3GPP RAN1 #123. It consolidates 44 Tdocs with 287 observations and 285 proposals across 41 pages, aiming to facilitate discussion and agreement on 6G waveform topics including DL/UL PAPR reduction, DFT-s-OFDM applicability, other waveforms, and UL multi-layer DFT-s-OFDM.
Position
Nokia, as moderator, proposes deprioritizing DL DFT-s-OFDM study for PDCCH/PDSCH/PBCH communication, presenting a technical case against it due to comparable PAPR with CP-OFDM using transparent techniques, lack of meaningful NES gain, and constraints on UE frequency domain resource allocation and SU/MU-MIMO precoding. They propose CP-OFDM as the baseline DL waveform with DFT-s-OFDM studied as potential addition, and support both CP-OFDM and DFT-s-OFDM as UL baselines. They require Net Gain evaluation as the primary criterion for low-PAPR proposals, calculated as Tx power gain minus link loss relative to reference at target KPI, using realistic PA models with RAN4 metrics. They support FDSS and FDSS-SE for 6G Radio with transparent filtering approach, propose dynamic waveform switching using DCI from first release, and require high power class as baseline. They deprioritize Zak-OTFS study, arguing CP-OFDM outperforms it with realistic assumptions. For UL multi-layer DFT-s-OFDM, they propose considering fully coherent and partially coherent UEs, evaluating net gain separately for power-limited and power non-limited UEs, with CP-OFDM supported for all layers.
Key proposals
- Proposal 1 (Sec 7): CP-OFDM waveform as defined in 5G NR is supported for communications in 6G downlink; DFT-s-OFDM or any other OFDM-based waveform will be studied as a potential additional waveform for downlink.
- Proposal 12 (Sec 7): Orthogonal multiple access (OMA) is the baseline for 6GR; evaluate OMA proposals using 5G NR as the benchmark, considering spectrum efficiency, coverage, NW and UE side complexity, compatibility with other areas, flexible resource allocation, and efficient 5G/6G spectrum sharing.
- Proposal 3 (Sec 8.1): RAN1 to deprioritize DFT-s-OFDM study for DL due to comparable PAPR with CP-OFDM using transparent reduction techniques, no meaningful NES gain, and higher baseband complexity.
- Proposal 4 (Sec 8.1): Downlink transmit power gain needs to be calculated under realistic PA constraints while ensuring compliance with ACLR and EVM limits, evaluated using Net Gain metric (Tx power gain – link loss at 10% BLER).
- Proposal 8 (Sec 8.2): For uplink low-PAPR proposals, the evaluation criterion is PAPR reduction and SINR degradation @10% BLER; Net gain including MPR can be evaluated by RAN4.
- Proposal 1 (Sec 6): Target use cases are recommended to be clarified and distinguished between multi-layer CP-OFDM and multi-layer DFT-s-OFDM before starting detailed design for multi-layer DFT-s-OFDM.
- Proposal 4 (Sec 5): RAN1 to deprioritize studying Zak-OTFS because CP-OFDM outperforms it with realistic simulation assumptions and it would introduce additional complexity.
- Proposal 11 (Sec 7): Support dynamic waveform switching using DCI introduced to 6G in the first release.
- Proposal 6 (Sec 3.1): For downlink low-PAPR proposals the evaluation criterion is PAPR reduction and SINR degradation @10% BLER.
- Proposal 3 (Sec 4.2): 6GR could study to support dynamic waveform switching during initial access for uplink.
- Proposal 4 (Sec 3.3): Study and evaluate CP-OFDM waveform enhancement techniques including PAPR/CM reduction techniques such as Selected Mapping (SLM) and Tone Reservation (TR) for coverage enhancement.
- Proposal 5 (Sec 5): Discontinue the study for potential support of 'other waveforms' in 6GR due to deviation from single technology framework goal and increased risk of RAT divergence.
- Proposal 15 (Sec 7): For enhance the sensing, new waveform different to OFDM can be studied, such as LFM, AFDM and OCDM.