R1-2600034
discussion
On aspects of bandwidth operation in 6GR
From Nokia
Summary
This 3GPP contribution from Nokia discusses bandwidth operation in 6GR, presenting 13 proposals and 7 observations aimed at redesigning the BWP framework to address 5G NR shortcomings. Key themes include simplification, robustness, decoupling UL/DL in TDD, and enabling wider initial BWP for network energy saving.
Position
Nokia proposes a lean 6GR BWP configuration framework that reduces the number of BWP types and eliminates redundant functionality options, making as many parameters cell-specific rather than BWP-specific. They require removing the existing 5G TDD coupling between DL and UL BWPs, enabling independent center frequencies and independent switching per link direction. For switching robustness, they oppose timer-based BW adaptation and propose a proactive DCI-based scheme using UL grant as trigger, where PUSCH acts as implicit ACK to confirm receipt of BW switch commands before the actual switch occurs. They propose decoupling initial BWP bandwidth from CORESET0 bandwidth to enable wider broadcast PDSCH transmissions for network energy saving. They propose studying carrier configuration simplification by replacing pointA and SCS-specific offset with a single absolute frequency parameter for the start of the network carrier, assuming single SCS per band.
Key proposals
- Proposal 1 (Sec 2.2): Simplification through lean configuration, reducing # of BWPs and BWP types, and eliminating redundant functionality options; Redesign the BW adaptation framework to make it robust and minimize service interruption and switching delays; Optimize UL coverage by revisiting UE RF requirements (RAN4); Provide a unified solution for SSB measurements for scenarios where CD-SSB is outside the initial BWP; Remove coupling between UL and DL BWP in TDD.
- Proposal 3 (Sec 3): Study efficient network carrier configuration principles assuming single subcarrier spacing for a given band.
- Proposal 4 (Sec 4): Study support of early CSI acquisition during initial access procedure for fast candidate SCell identification and configuration from IDLE/Inactive mode.
- Proposal 5 (Sec 4.1): Study supporting system design where initial BWP for broadcast PDSCH transmissions can be wider than bandwidth of CORESET0.
- Proposal 6 (Sec 5.1): Minimize the BWP specific parameters and configuration options; Make as many parameters as possible cell-specific.
- Proposal 7 (Sec 5.1): Maximize the coexistence and similarity between initial and non-initial BWPs for parameters and configuration options that require BWP-specific adaptation, e.g., CORESET0 and other CORESETs.
- Proposal 8 (Sec 5.1): Remove the existing coupling between DL and UL BWPs in 5G TDD, whereby DL and UL BWPs are required to switch simultaneously and share the same center frequency.
- Proposal 9 (Sec 5.2.1): For robust BW switching, aim at a proactive scheme for mitigating the potential error cases.
- Proposal 10 (Sec 5.2.1): Do not support timer-based BW adaptation in 6GR.
- Proposal 11 (Sec 5.2.1): Consider DCI based BW-adaptation triggering for 6GR.
- Proposal 12 (Sec 5.2.1): Consider UL grant as a trigger for DL BW switch or UL BW switch.
- Proposal 13 (Sec 5.2.2): Minimize the switching gap due to BWP switching: Divide total switching delay into Processing time only and Switching time; Make the presence of switching gap conditional on link direction (DL/UL) during the switching; Make the presence of switching gap conditional on switching type (BB only or RF).