R1-2601905
discussion
Transmission schemes for 6GR UL channels
From TCL
Summary
TCL presents 1 observation and 11 proposals for 6GR uplink channel design, covering PUCCH format simplification, PUSCH/PUCCH DMRS enhancements, uplink transmission schemes with multi-TRP support, and uplink precoding design for CSI acquisition.
Position
TCL observes that the five PUCCH formats in 5G significantly increase UCI multiplexing difficulty, resource configuration overhead, and implementation complexity, and proposes limiting the number of PUCCH formats in 6G. For PUSCH DMRS, TCL proposes studying support for up to 48 antenna ports, a new flexible and extensible DMRS mapping type differing from Type 1 or Type 2, and time-domain/frequency-domain sparse DMRS mapping with dynamic sparsity adjustment based on channel conditions. TCL supports both CP-OFDM and DFT-s-OFDM waveforms as baseline for 6G PUSCH and suggests one low PAPR sequence type is sufficient for DFT-s-OFDM DMRS, with Type 2 refinement or a new design. For uplink transmission schemes, TCL requires PUCCH repetitions to up to two TRPs as a baseline and single-scheduling-trigger dual PUSCH for different TRPs to be supported. For uplink precoding, TCL proposes frequency-selective precoding to address precoding mismatch in frequency-selective channels and requires a unified precoding structure applicable across diverse terminal types including FWA terminals with up to 8Tx configurations.
Key proposals
- Proposal 1 (Sec 2.1): 6G should limit the number of PUCCH formats.
- Proposal 2 (Sec 2.2): For 6G PUSCH transmission, support for up to 48 antenna ports should be studied.
- Proposal 7 (Sec 2.3): For DMRS design for PUCCH, 6G should study to reduce the PUCCH format to eliminate the require for completely different DMRS generation schemes and patterns.
- Proposal 8 (Sec 2.4): For 6GR, supporting PUCCH repetitions to up to two TRPs can serve as the baseline. Considering 6GR requirements such as a 400 MHz bandwidth, some necessary enhancements should be further studied.
- Proposal 10 (Sec 2.5): For uplink CSI acquisition, frequency-selective precoding should be considered for 6GR, and the precoding design should aim to balance overhead, complexity and performance.
- Proposal 3 (Sec 2.2): For 6GR, a flexible and extensible DMRS mapping type should be studied, which may differ from Type 1 or Type 2. Meanwhile, one or two DMRS types are sufficient, and introducing more types is not recommended.
- Proposal 4 (Sec 2.2): For 6G PUSCH transmission, time-domain and frequency-domain sparse DMRS should be studied.
- Proposal 5 (Sec 2.2): For 6G PUSCH transmission, both CP-OFDM and DFT-s-OFDM waveforms can be supported as a baseline and the necessary enhancement can be further studied.
- Proposal 6 (Sec 2.2): For the sequence design of DMRS for PUSCH with DFT-s-OFDM waveform, may be one type of low PAPR sequence is enough, Type 2 with necessary refinement or a new low PAPR sequence design can be considered.
- Proposal 9 (Sec 2.4): For 6GR, single-scheduling-trigger dual PUSCH for different TRPs should be supported. Considering 6GR requirements such as a 400 MHz bandwidth, some necessary enhancements should also be studied.
- Proposal 11 (Sec 2.5): For uplink CSI acquisition, the precoding design should be suitable for diverse terminals, and a unified precoding structure should be applied across different terminal types.