R1-2409855
discussion
Discussion on specification support for beam management
From NEC
Summary
NEC's technical document on AI/ML enhancements for NR beam management presents comprehensive specifications for both UE-sided and NW-sided models across spatial and temporal beam prediction cases. The document contains 39 proposals and 14 observations covering beam management lifecycle management, performance monitoring, beam indication enhancements, and beam failure recovery improvements.
Position
NEC advocates FOR UE-centric beam prediction with flexible UE-determined reporting (K-value selection, confidence reporting), comprehensive performance monitoring using RSRP difference metrics, and enhanced TCI framework extensions. They push AGAINST rigid network-only control of prediction parameters and favor Option 3 for UE-initiated applicability reporting, while strongly supporting backward compatibility through simultaneous legacy BM configuration and AI/ML beam management coexistence.
Key proposals
- Proposal 2 (Sec 2.1): The timing information of Set B measurements and Set A predictions should be specified as conditions for BM-Case1 and BM-Case2 and comprised in UE capability reporting
- Proposal 5 (Sec 2.2): For the consistency of NW-side additional conditions across training and inference for UE-sided model for BM-Case 1 and BM-Case 2 based on associated ID, where the NW-side additional conditions may at least impact UE assumption on beams of Set A/Set B
- Proposal 8 (Sec 2.3): For data collection for NW-sided model, also support L1 report leveraging the existing CSI report framework
- Proposal 11 (Sec 2.4.1): For BM-Case1 and BM-Case2, the value of K (i.e., the number of predicted beams to report) should be determined and provided to NW by UE
- Proposal 18 (Sec 2.4.2): For overhead reduction for BM-Case2, support a larger RSRP quantization step size for the historical results obtained earlier, e.g., with a longer time from measurement to model inference
- Proposal 23 (Sec 2.5.1): Support UE to initiate performance monitoring of current AI/ML model if beam failure instance indication or out-of-sync indication is received
- Proposal 27 (Sec 2.5.2): At least for regression-based model (or the model can predict RSRP), support Alt 3: The RSRP difference information between the predicted RSRP and measured L1-RSRP of corresponding beam(s) of a resource set/resources for monitoring
- Proposal 33 (Sec 2.6): RAN1 to discuss the impact of CA and BWP operation on the beam prediction framework
- Proposal 35 (Sec 3.1): To enhance unified TCI state to indicate the predicted beam, support to configure RS in associated Set A as the QCL reference signal in the TCI state
- Proposal 38 (Sec 3.2): At least for BM-Case 2, support beam failure detection based on time-domain prediction
- Proposal 12 (Sec 2.4.1): For report content of inference results for UE-sided model for BM-Case 1, for the RSRP of predicted Top K beam(s) in the report of inference results, Option B should be supported
- Proposal 20 (Sec 2.5.1): For the configuration of monitoring Type 1 Option 2 of UE-side model monitoring, Option 2 can be a baseline and further study Option 1
- Proposal 25 (Sec 2.5.1): Study simultaneous performance monitoring for multiple candidate models, including how to inform the NW the inactive candidate models
- Proposal 36 (Sec 3.1): For BM-Case 2, support to use one MAC CE or DCI to activate/indicate multiple (future) TCI states, and corresponding time period
- Proposal 39 (Sec 3.2): Support predicted beam as the newly identified beam q_new