R1-2509256
LS out
Draft reply LS on 6GR system parameter evaluations
From NTT DOCOMO
Summary
This document from NTT DOCOMO (R1-2509256) is a draft reply LS to RAN4 containing 135 proposals and 5 observations from the RAN1#123 meeting on 6G radio (FS_6G_Radio). It covers RAN1's agreements on candidate waveforms, modulation schemes, SSB structures, and numerologies for 6GR.
Position
NTT DOCOMO supports using CP-OFDM and DFT-s-OFDM waveforms as defined in 5G NR as the basis for 6GR uplink and downlink, while keeping other OFDM-based waveforms not precluded. They propose specific evaluation criteria for uplink low-PAPR waveforms using Net Gain [dB] = Tx power gain relative to the reference – SNR degradation relative to the reference @10% BLER, requiring realistic PA model and RAN4 metrics. They support QPSK to 1024QAM for DL and pi/2 BPSK to 256QAM for UL DFT-s-OFDM as basis for study, with FFS on enhancements and other modulation schemes. They request study of constellation shaping (probabilistic and geometric) compared with non-shaping using NR MCS table, including PAPR/CM for DFT-s-OFDM and higher-order modulations (4096QAM DL, 1024QAM UL) under realistic conditions. They propose studying on-demand sync signal mechanisms and longer periodicities (20ms+) for energy efficiency, and they adopt NR frame structure with specific SCS values per frequency range including FFS on additional SCS options (7.5kHz for sub-1GHz FDD, 30/60/120kHz for around 15GHz) subject to RANP decision.
Key proposals
- Proposal 2 (Sec 3): CP-OFDM and DFT-s-OFDM waveforms as defined in 5G NR are supported as the basis for 6GR for uplink.
- Proposal 5 (Sec 3): CP-OFDM waveform as defined in 5G NR is supported as the basis for 6GR for downlink.
- Proposal 9 (Sec 3): For uplink low-PAPR proposals, the link level performance evaluation criterion is Net Gain assuming same spectrum efficiency as the reference.
- Proposal 17 (Sec 4): For 6GR DL, 5G NR uniform QPSK, 16QAM, 64QAM, 256QAM and 1024QAM are supported as basis for study for data channel.
- Proposal 23 (Sec 4): For 6GR constellation shaping evaluation for CP-OFDM, and improved MCS table, the proposed scheme will be compared with non-shaping with NR MCS table considering BLER, HARQ, throughput, complexity, and spec impact.
- Proposal 35 (Sec 4): For 6GR constellation shaping study, proponent is encouraged to provide details for the PS/GS schemes including probabilistic shaping and geometric shaping specifics.
- Proposal 59 (Sec 4): For 6GR constellation shaping evaluation for DFT-s-OFDM, evaluation shall further consider PAPR/CM of the resulting waveform, EVM, MPR/A-MPR.
- Proposal 62 (Sec 4): For the study of uniform 4096QAM for DL and uniform 1024QAM for UL, need to study performance, complexity, requirements, benefit/necessity, and challenges under realistic PA model.
- Proposal 66 (Sec 5): Identify the high-level aspects which impact on the 6GR sync signal structure and associated periodicity.
- Proposal 80 (Sec 5): Study and evaluate on-demand sync signal(s) mechanisms for 6GR energy efficiency.
- Proposal 85 (Sec 5): Study and evaluate NW energy savings and impact on UE performance with respect to 20ms and longer periodicities of sync signal(s) at least for initial access.
- Proposal 104 (Sec 6): 6GR takes the following SCS as start point for discussion for all signals/channels except PRACH, specifying 15kHz for FDD sub-6GHz, 30kHz for TDD sub-6GHz, 30/60kHz around 7GHz, and 120kHz for 24.25-52.6GHz.
- Proposal 125 (Sec 6): For communication, 6GR considers NR frame structure used as a starting point for the study item, maintaining 10ms radio frames, 1ms subframes, and 14-symbol slots.
- Proposal 131 (Sec 6): A slot is defined as supporting 14 consecutive symbols for normal CP case and all subcarrier spacings.
- Proposal 135 (Sec 6): RAN1 assumes 400MHz maximum channel bandwidth at network side and 30kHz SCS around 7GHz, and studies whether and how to enable UE to support 400MHz bandwidth.