R1-2600138
discussion
Waveform for 6GR air interface
From Huawei
Summary
This contribution from Huawei proposes and evaluates several waveform and modulation enhancements for 6G, including I/Q-offset DFT-s-OFDM, Pruning QAM, UL multi-layer DFT-s-OFDM, and DL DFT-s-OFDM for signals in BS LP-mode. The document contains 20 Observations and 12 Proposals.
Position
Huawei proposes I/Q-offset DFT-s-OFDM as a generalization of prior low PAPR proposals (including Pi/2 BPSK Truncation and O-QAM modulated DFT-s-OFDM) and supports it as a lower PAPR waveform candidate for RAN4 evaluation. They request RAN1 begin discussion on spec impacts including candidate spectrum adjustment ratios, TB size calculation, and multi-user overlap. They propose Pruning QAM as a new modulation candidate providing lower PAPR under DFT-s-OFDM and better sensing performance under CP-OFDM for ISAC studies. They propose supporting at least 2-layer UL DFT-s-OFDM and 2-layer UL CP-OFDM in 6GR, requiring further study on the maximum number of layers within the 6GR MIMO agenda. They propose studying DL DFT-s-OFDM for additional synch. signal and DL-WUS transmission in BS LP-mode, citing a network gain of around 3 dB compared to CP-OFDM and defining net gain as the performance evaluation criterion.
Key proposals
- Proposal 1 (Sec 2.2.2): Support I/Q-offset DFT-s-OFDM as a lower PAPR waveform candidate for further RAN4 evaluations.
- Proposal 2 (Sec 2.3): RAN1 can start discuss the potential spec impact of low PAPR waveform enhancement schemes, including but not limited to candidate spectrum adjustment ratios, determination of spectrum adjustment ratios, TB size calculation, multi-user overlap.
- Proposal 3 (Sec 2.3): Adopt Table 11 to characterize I/Q-offset DFT-s-OFDM as a RAN1 observation.
- Proposal 4 (Sec 3.2.1): Support pruning QAM as a lower PAPR modulation candidate for RAN4 further evaluations.
- Proposal 5 (Sec 3.2.2): Study pruning QAM under CP-OFDM waveform for ISAC.
- Proposal 6 (Sec 3.2.2): Adopt Table 14 to characterize Pruning QAM as a RAN1 observation.
- Proposal 7 (Sec 4.1): Take net gain as the link level simulation metrics for multi-layer DFT-s-OFDM compare to multi-layer CP-OFDM.
- Proposal 8 (Sec 4.2): CDF-based throughput gain is used as the system level simulation metrics for evaluations of UL multi-layer DFT-s-OFDM/CP-OFDM.
- Proposal 9 (Sec 4.2): With observed coverage net gains, at least both 2-layers uplink DFT-s-OFDM waveform and 2-layer uplink CP-OFDM waveform should be supported in 6GR. The maximum number of layers should be further studied in 6GR MIMO agenda, e.g., codebook design.
- Proposal 10 (Sec 5.1): For DL DFT-s-OFDM additional synch. Signal/DL-WUS, the performance evaluation criterion from waveform perspective is net gain [dB] = Tx power gain relative to the reference – Required SNR degradation relative to the reference. For additional synch. signal and sequence based DL-WUS, the required SNR is for detection rate below 1% and false alarm rate below [1%] assuming same resource overhead. The requirements of RSRP accuracy based on additional synch. signal should be met, e.g. as in TS 38.133.
- Proposal 11 (Sec 5.1): Take Table 17 as a start point for DL DFT-s-OFDM waveform evaluation for additional synch. Signal/DL-WUS.
- Proposal 12 (Sec 5.2): Study DL DFT-s-OFDM for additional synch. Signal/DL-WUS for coverage enhancement, network energy saving and UE energy saving under related agendas, e.g., initial access, DL WUS agenda.