Aperiodic CSI-RS Slot Mapping Across Mixed OFDM Numerologies

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Solution Overview

Problem

The current aperiodic CSI-RS triggering procedure in NR is not well-defined for cases where DCI and CSI-RS are transmitted on carriers with different numerologies, leading to ambiguity in slot determination and increased UE implementation complexity and memory consumption.

Innovation Solution

A predefined rule is introduced to map the PDCCH reception slot in one numerology to a reference slot in the CSI-RS numerology, using a slot offset to determine the aperiodic CSI-RS slot, minimizing UE buffering needs and reducing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If aperiodic CSI-RS triggering is implemented with mixed numerologies between PDCCH and CSI-RS carriers, then system flexibility and adaptability are improved, but slot determination ambiguity and UE implementation complexity increase

Engineering Contradiction:

Improvesupport for mixed numerologiesVSAvoidUE implementation complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary mapping rule that translates PDCCH slot indices from one numerology to corresponding CSI-RS slot indices in another numerology. This intermediary mechanism resolves the ambiguity by providing a deterministic translation function between different numerology domains, allowing UEs to correctly identify CSI-RS slots without complex real-time calculations or additional signaling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter representation by introducing a slot offset parameter that adjusts the mapping between PDCCH and CSI-RS slots. By modifying how slot timing is represented and calculated across different numerologies, the system enables flexible numerology combinations while maintaining deterministic slot determination through parameter-based adjustments rather than complex algorithms.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If aperiodic CSI-RS triggering is implemented with mixed numerologies, then system flexibility is improved, but UE memory consumption increases

Engineering Contradiction:

Improvesupport for mixed numerologiesVSAvoidUE memory consumption

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent extracts the numerology conversion logic from the UE's memory-intensive buffering operations. By separating the slot determination function into a dedicated mapping rule that operates on slot indices rather than requiring buffering of multiple numerology timelines, the solution reduces UE memory consumption while maintaining support for mixed numerologies.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by pre-defining the slot mapping rules between different numerologies through RRC configuration. This allows UEs to determine CSI-RS slots through simple offset calculations based on pre-configured parameters, eliminating the need for complex real-time computations or large memory buffers that would otherwise be required to handle numerology conversions dynamically.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If slot determination rules are not well-defined for mixed numerologies, then implementation flexibility is maintained, but reliability of CSI-RS reception deteriorates

Engineering Contradiction:

Improveimplementation flexibilityVSAvoidCSI-RS reception reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent creates a universal slot determination mechanism that works across all numerology combinations. The mapping rule serves multiple functions: it determines CSI-RS slots for any PDCCH-CSI-RS numerology pair, handles both same-numerology and different-numerology cases, and provides a unified approach that maintains reliability while preserving implementation flexibility through standardized procedures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250365753A1Triggering of aperiodic channel state information reference signals with mixed numerology

Publication Date: 2025.11.27 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Devices, systems, and methods described herein may improve aperiodic CSI-RS handling in mixed numerology environments. An exemplary method includes operations of receiving a downlink control information (DCI) message carried by a Physical Downlink Control Channel (PDCCH) on a second carrier, wherein the second carrier uses a second OFDM numerology, obtaining an aperiodic CSI-RS slot offset from the DCI message, determining a reference slot in the first numerology, determining the slot of the aperiodic CSI-RS based on the reference slot and the aperiodic CSI-RS slot offset, and receiving or transmitting the aperiodic CSI-RS in the determined slot.