R1-2601864
discussion
Waveform and frame structure for 6GR sensing
From NEC
Summary
NEC presents 13 Observations and 9 Proposals on 6G RAN ISAC waveform and frame structure, advocating for an evolution from existing 3GPP OFDM-based waveforms with targeted enhancements for longer CP, OTFS for high mobility, and TDM-based sensing resource allocation.
Position
NEC proposes adopting conventional OFDM-based waveforms (CP-OFDM, DFT-S-OFDM) as the baseline sensing waveform, requiring balanced performance and forward compatibility with existing 3GPP communication frameworks. They propose studying OFDM-based longer cyclic prefix (CP) schemes to support long-range sensing (multi-kilometer coverage), noting that NCP and ECP fail to meet these requirements (e.g., NCP supports only ~703 m at 15 kHz SCS in FR1), and require the CP length design of sensing symbols to be associated with the number of sensing symbols within a slot. NEC prioritizes studying TDM-based multiplexing between sensing and communication resources over FDM and SDM approaches, citing independent signal generation and maximized resource efficiency, and proposes studying at least symbol-level allocation based on TDD pattern configuration. They propose the study scope include both Continuous Waveform (CW) and Pulse Waveform (PW) transmission schemes, and propose studying OTFS-based waveform transmission for high-mobility scenarios due to its delay-Doppler domain robustness. They further propose studying dynamic waveform switching between candidate waveforms adaptively based on application, mobility conditions, and sensing accuracy requirements.
Key proposals
- Proposal 1 (Sec 2.1): The sensing waveform should achieve balanced performance, low implementation complexity, and good forward compatibility with existing 3GPP communication.
- Proposal 2 (Sec 2.2): Adopt the conventional OFDM-based waveform (e.g., CP-OFDM, DFT-S-OFDM) as the starting point for the sensing waveform study.
- Proposal 5 (Sec 2.3): The Study of sensing waveform transmission should allow for both Continuous Waveform (CW) and Pulse Waveform (PW).
- Proposal 3 (Sec 2.2): Study the OFDM-based longer CP schemes for 6GR sensing to support long-distance sensing and communication-sensing integration in the same slot.
- Proposal 4 (Sec 2.2): Study the CP length design of sensing symbols associated with the number of sensing symbols within a slot.
- Proposal 6 (Sec 2.3): Study the OTFS-based waveform transmission in 6GR sensing.
- Proposal 7 (Sec 2.3): Study the TDMed multiplexing between sensing resource and communication resource of ISAC in a first priority.
- Proposal 8 (Sec 2.3): Study at least the symbol-level definition or allocation for sensing resource and communication resource of ISAC based on TDD pattern configuration.
- Proposal 9 (Sec 2.3): 6GR sensing could study the dynamic waveform switching between the candidate waveforms based on the application.
- Proposal 1 (Sec 3): The sensing waveform should achieve balanced performance, low implementation complexity, and good forward compatibility with existing 3GPP communication.