R1-2602354
discussion
Maintenance on Rel-19 AI/ML
From InterDigital
Summary
InterDigital argues that mandatory PDSCH rate matching for Set A CSI-RS resources in Rel-19 AI/ML beam management negates the efficiency benefits of the feature and wastes resources when transmissions are virtual. The document presents three observations regarding these inefficiencies and two proposals to condition rate matching on the presence of the CSI-ResourcePeriodicityAndOffset parameter.
Position
InterDigital opposes the current framework where PDSCH rate matching is tied to the configuration of Set A, arguing it introduces unintended restrictions and negates the fundamental benefit of AI/ML beam management by wasting resources on virtual CSI-RS. They propose that rate matching behavior should depend on the presence of the CSI-ResourcePeriodicityAndOffset parameter: if configured, rate matching is performed; if absent, rate matching is not performed. This approach allows the utilization of resource elements for PDSCH transmission when Set A resources are not actually transmitted, thereby preserving resource efficiency. They argue that treating virtual CSI-RS resources identically to transmitted ones causes unnecessary performance degradation and constrains UE implementation flexibility.
Key proposals
- Proposal 1 (Discussion): Support virtual resource blocks mapping of PDSCH in TS38.211 such that rate matching is performed only if CSI-ResourcePeriodicityAndOffset is configured for NZP CSI-RS in Set A, and not performed if it is absent.
- Proposal 2 (Discussion): Adopt a Technical Proposal (TP) stating that NZP CSI-RS resources in Set A are not rate matched when CSI-ResourcePeriodicityAndOffset is absent, to allow utilization of REs without actual transmission.
- Proposal 2 (References): Adopt a TP for TS 38.211 Clause 7.3.1.5 clarifying that CSI-RS only configured in Set A is not used to perform PDSCH rate-matching if CSI-ResourcePeriodicityAndOffset is not configured.