R1-2500619
LS out
[Draft] Reply LS on LMF-based AI/ML Positioning for Case 3b
From ZTE
Summary
This document is a Liaison Statement reply from RAN1 to SA2 regarding LMF-based AI/ML positioning for Case 3b in Rel-19. It outlines current progress and future work plans for data types and procedures, detailing agreements on channel measurements, timing references, and training data components, while noting that RAN load considerations are not yet agreed upon.
Position
ZTE presents the consolidated RAN1 agreements on data types and procedures for LMF-based AI/ML positioning Case 3b. They define the mandatory model input data types as timing information and paired timing/power information, specifically utilizing UL SRS-RSRPP and DL PRS-RSRPP as starting points. They require timing information to be represented relative to the existing UL RTOA reference time T0+tSRS. They propose enhancing measurements with time-domain channel responses, specifying parameters Nt'<=24 and Nt={32, 64, 128}. They clarify that RAN1 has no agreement on considering RAN load for measurement reporting. For model training, they define data samples comprising Part A (measurements) and Part B (labels), reusing existing TS 38.455 IEs for timestamps and quality indicators. They mandate that inference reports from gNB to LMF include channel measurements and timestamps, with quality indicators as optional.
Key proposals
- Proposal 1 (Sec 1.1): Defines Case 3b data types to include timing information and paired timing/power information, using UL SRS-RSRPP and relative timing to T0+tSRS as starting points.
- Proposal 2 (Sec 1.1): States that RAN1 has no agreement on considering RAN load for measurement information reporting to the LMF.
- Proposal 3 (Sec 1.1): Agrees that for gNB channel measurements, timing information is represented relative to the existing UL RTOA reference time T0+tSRS defined in TS 38.215.
- Proposal 4 (Sec 1.1): Specifies that power information for model input uses DL PRS-RSRPP and UL SRS-RSRPP defined in TS 38.215, with reporting mapping tables from TS 38.133.
- Proposal 5 (Sec 1.1): Proposes enhancing measurements with Nt' values of estimated channel response in the time domain, selected from Nt consecutive values with timing granularity T.
- Proposal 6 (Sec 1.1): Sets candidate parameter values for time domain channel measurements: Nt'<=24, Nt = {32, 64, 128}, and timing granularity factor k as FFS.
- Proposal 7 (Sec 1.2): Defines training data samples for Case 3b to include Part A (channel measurement, quality indicator, timestamp) and Part B (ground truth label, quality indicator, timestamp).
- Proposal 8 (Sec 1.2): Reuses existing IE 'Time Stamp' in TS 38.455 for the timestamp of channel measurement generated by TRP/gNB.
- Proposal 9 (Sec 1.2): Reuses existing IE 'Timing Measurement Quality' in TS 38.455 for the quality indicator of timing information in Part A.
- Proposal 10 (Sec 1.2): Agrees that for model inference, gNB reports to LMF must mandatorily include channel measurement and timestamp, with optional quality of channel measurement.
- Proposal 11 (Sec 1.2): Identifies that ground truth labels for Case 3b can be generated by PRU, Non-PRU UE with estimated location, or LMF, assuming user data privacy is preserved.
- Proposal 12 (Sec 1.2): Proposes studying the necessity and detailed assistance/measurement information from UE/PRU/gNB to LMF for performance monitoring of LMF-side models.