R1-2601809
discussion
Discussion on bandwidth operation
From Spreadtrum
Spreadtrum's prior position on
10.5.1.3
at
RAN1#124
· AI-synthesized, paraphrased
verify sources →
Proposes directly adopting the NR mechanism for determining CORESET-0 information via MIB for 6GR initial access. Proposes studying discontinuous frequency resources for initial DL/UL BWP to address the limitation that NR's continuous frequency requirement for BWP/CC restricts effective utilization of operators discrete spectrum resources. Proposes studying the feasibility of center frequency misalignment for DL/UL initial BWP, arguing that NR TDD's alignment requirement may limit 6GR application scenarios, particularly considering SCMC sub-band differences. Proposes that the NR concept of downlink/uplink initial BWP serves as a starting point for 6GR, with additional FFS items on dedicated initial BWP for LPWA and multiple initial BWPs for SCMC.
Summary
This Spreadtrum contribution provides 8 proposals and 2 observations on 6GR bandwidth part (BWP) operation across initial access, idle mode, and connected mode, focusing on reusing NR mechanisms while addressing spectrum fragmentation and BWP switching complexity.
Position
Spreadtrum proposes reusing NR's mechanism for determining CORESET-0 via MIB and the concept of initial DL/UL BWP as a starting point for 6GR. They require that SIB1, Msg2, Msg4, and scheduling PDCCH bandwidths be confined within CORESET-0, while Msg1, Msg3, and PUCCH for Msg4 be confined within the initial uplink BWP. They propose studying discontinuous frequency resources for 6GR initial BWP to address operator spectrum fragmentation, and studying central frequency misalignment between DL and UL initial BWP for TDD, citing the SCMC scenario and agreed asymmetric CBW (400MHz DL / 200MHz UL). They identify specific NR BWP lessons including BB/RF parameter bloat, complicated SCS switching, redundant BWP types, contiguous-only resource restriction, and DCI-based switching reliability gaps in non-overlapped BWP scenarios, and insist on early RAN4 involvement to avoid sub-optimal design.
Key proposals
- Proposal 1 (Sec 2): Adopt NR mechanism of determining CORESET-0 information via MIB for 6GR initial access procedure.
- Proposal 2 (Sec 2): The concept of NR downlink/uplink initial BWP can be a starting point for 6GR.
- Proposal 3 (Sec 2): CORESET-0 re-uses NR mechanism with location reference to SSB; increase RB number for eMBB devices; SIB1, Msg2/4, and scheduling PDCCH bandwidth confined within CORESET-0.
- Proposal 4 (Sec 2): Msg1, Msg3, and PUCCH for Msg4 bandwidths confined within initial uplink BWP.
- Proposal 5 (Sec 2): Paging PDCCH/PDSCH bandwidths confined within initial downlink BWP.
- Proposal 6 (Sec 2): Study discontinuous frequency resources for 6GR initial DL/UL BWP.
- Proposal 7 (Sec 2): Study the feasibility of central frequency misalignment for 6GR DL/UL initial BWP.
- Proposal 8 (Sec 3): Lessons from NR BWP include excessive BWP-specific BB/RF parameters causing long switch latency, complicated SCS switching, redundant BWP types, contiguous frequency restriction, DCI-based switching reliability issues in non-overlapped BWPs, and lack of early RAN4 involvement.