R1-2601783
discussion
6G Bandwidth Operation
From FUTUREWEI
FUTUREWEI's prior position on
10.5.1.3
at
RAN1#124
· AI-synthesized, paraphrased
verify sources →
Proposes a 6GR framework where a single cell maps to multiple component carriers to handle fragmented irregular spectrum, preserving the 5G NR BWP definition as a contiguous spectrum part within a carrier. Requires UE operation with more than one active BWP simultaneously in a multi-carrier cell, introducing intra-cell CA with one Primary BWP (PBWP) for control, RS, and RRC connectivity and one or more Secondary BWPs (SBWPs) for data exchange. Requires the PBWP to remain active during SBWP activation/deactivation to minimize disruptions and transition latency. Proposes studying two HARQ solutions for multiple active BWPs: single TB transmission over multiple active BWPs with one HARQ process per TB, versus one TB transmission per active BWP with one HARQ process per BWP. Proposes improving BWP DCI-based switching reliability via two-stage DCI or MAC CE, and proposes studying BWP association with QoS for improved performance.
Summary
This Futurewei contribution on 6G Bandwidth Operation contains 10 proposals and 2 observations. It advocates for a simplified 6GR bandwidth operation framework that addresses lessons learned from 5G NR BWP, focusing on energy efficiency, reduced complexity, and improved spectrum utilization for diverse device types including lower-tier UEs with narrow bandwidth capabilities.
Position
Futurewei proposes that 6GR bandwidth operation study focus on BW determination and adaptation optimizing energy efficiency and spectrum utilization for diverse device types. They identify specific 5G NR BWP design disadvantages—excessive RRC configuration parameters, long switching delays causing service interruptions, DCI-based switching reliability issues, and fragmentation from redundant BWP types—and require 6GR solutions to reduce complexity, overhead, switching latency, and interruptions while increasing reliability. They study two distinct post-initial-access framework options: Option A (single active logical contiguous virtual resource across multiple carriers) and Option B (multiple independent contiguous physical frequency resources each active within one carrier). They propose studying initial DL BW and initial UL BW as contiguous PRB regions supporting synchronization, system information, paging, and random access, with co-location and center-frequency alignment for TDD to simplify initial access. They require supporting HARQ process continuity during BW switching and propose studying two TB transmission schemes for intra-cell carrier aggregation: single TB over separated allocations with a single HARQ process versus separate TBs per allocation with independent HARQ processes.
Key proposals
- Proposal 1 (Sec 3.1): 6GR BW operation study should focus on BW determination and adaptation that optimize energy efficiency and improve spectrum utilization for diverse device types while keeping mobile broadband requirements high priority.
- Proposal 2 (Sec 3.4): 6GR BW operation solutions should aim to reduce complexity and overhead, switching latency and interruptions, while increasing reliability and avoiding unnecessary device-type and feature fragmentation.
- Observation 1 (Sec 3.2): In 5G NR the BWP concept was introduced to support diverse UE bandwidth capabilities and promote UE energy savings by allowing the device to monitor and process a narrower portion of the carrier bandwidth.
- Observation 2 (Sec 3.5): DL paging channels included in the initial DL BW may reduce BW switching for UEs in IDLE/INACTIVE state.
- Proposal 3 (Sec 3.5): Study the determination of initial DL BW and initial UL BW as contiguous PRB regions that can support the resources needed for basic initial access and essential IDLE/INACTIVE operations.
- Proposal 4 (Sec 3.5): For TDD operation, study whether keeping the initial DL BW and initial UL BW co-located within the same carrier and aligned in center frequency can simplify initial access for diverse UE types.
- Proposal 5 (Sec 3.6): Study two options for the 6GR BW operation framework after initial access: BW-operation Option A: a single active logical contiguous (virtual) resource across multiple carriers and BW-operation Option B: multiple independent contiguous physical frequency resources each active within one carrier.
- Proposal 6 (Sec 3.6): 6GR BW operation should have a simpler design and configuration across multiple bandwidth configurations while reducing interruptions, for instance supporting the continuity of HARQ processes.
- Proposal 7 (Sec 3.6): Study whether/how UE can support maintaining parts of the 6GR BWP active during BW adaptation to minimize disruptions and transition latency.
- Proposal 8 (Sec 3.6): If DCI-based BW switching is supported, 6GR should improve its reliability, for instance using two-stage DCI or MAC CE.
- Proposal 9 (Sec 3.6): In one cell with multiple active BWP(s) study and compare the following solutions: One TB transmission over two separated spectrum allocations (single HARQ process) and Two TB transmissions separately, one in each separate spectrum allocation (one HARQ process per TB).
- Proposal 10 (Sec 3.6): Study whether and how BW operation association with QoS could lead to improved performance.