Variable DMRS Mapping for Early PDCCH Detection in CORESET

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Solution Overview

Problem

Existing 5G NR systems face challenges in reducing physical downlink control channel (PDCCH) decoding complexity and power consumption due to fixed density demodulation reference signals (DMRS) that do not adapt to varying channel conditions or UE-specific requirements.

Innovation Solution

Implementing variable density DMRS that adjusts DMRS density based on relative symbol position within a control resource set (CORESET) and aggregation level, allowing for semi-static or dynamic indication to enhance channel estimation accuracy while minimizing power consumption and signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fixed density DMRS is used, then channel estimation is performed with consistent resource allocation, but PDCCH decoding complexity and power consumption increase without adaptation to channel conditions

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by transitioning from fixed density DMRS to variable density DMRS, where the DMRS density is dynamically adjusted based on channel conditions, aggregation level, and symbol position. This allows the system to adapt the reference signal density to actual needs, improving channel estimation accuracy when required while reducing power consumption when channel conditions permit lower density.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of DMRS density from a fixed value to a variable parameter that depends on multiple factors including channel conditions, aggregation level, and relative symbol index. This parameter change enables the system to optimize the balance between channel estimation accuracy and power consumption by adjusting density according to actual operational requirements.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If high DMRS density is used throughout CORESET, then channel estimation accuracy is improved, but resource overhead and decoding complexity increase

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoiddecoding complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by assigning different DMRS densities to different locations within the CORESET. Specifically, earlier symbols receive higher DMRS density for accurate channel estimation, while later symbols use lower density. This localized differentiation optimizes channel estimation where most needed while reducing overall complexity and resource overhead.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses partial action by applying high DMRS density only to the extent necessary for reliable PDCCH detection. Rather than uniformly high density throughout the CORESET, the system applies high density selectively to initial symbols and reduces density in subsequent symbols, achieving sufficient channel estimation accuracy with reduced overall complexity.

Inventive Principle:

Principle #16Partial or excessive action

3Use of energy by moving object

If variable density DMRS is implemented, then power consumption is reduced through early PDCCH detection, but signaling overhead for indicating density patterns increases

Engineering Contradiction:

Improvepower consumptionVSAvoidsignaling overhead

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The patent segments the DMRS density indication into multiple components: a base density level and additional density patterns for specific symbol positions or aggregation levels. This segmentation allows the system to convey variable density information through compact signaling mechanisms, reducing the overall signaling overhead while enabling power-saving early detection capabilities.

Inventive Principle:

Principle #1Segmentation

4Reliability

If DMRS density varies by aggregation level, then decoding reliability is improved for different PDCCH sizes, but configuration complexity increases

Engineering Contradiction:

Improvedecoding reliabilityVSAvoidconfiguration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves universality by creating a unified DMRS density configuration framework that serves multiple aggregation levels simultaneously. The same set of density patterns and indication mechanisms is used across different aggregation levels, allowing the system to improve decoding reliability for various PDCCH sizes without proportionally increasing configuration complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250385820A1Variable density DMRS for pdcch pruning enhancements

Publication Date: 2025.12.18 QUALCOMM INC

AI summary

This disclosure provides methods and apparatuses for efficient decoding of control resource sets (CORESETs) and power saving in User Equipment (UEs) using variable density Demodulation Reference Signals (DMRS). In some examples, a UE obtains, from a network entity, a configuration of a DMRS mapping pattern to resource elements of a CORESET, with the DMRS mapping pattern indicating a variable DMRS density. This density may be dependent upon a relative orthogonal frequency division multiplexing (OFDM) symbol index within the CORESET, or an aggregation level allocated for a physical downlink control channel (PDCCH) in the CORESET. Based at least in part on this DMRS mapping pattern, the UE may perform early detection of the presence or absence of the PDCCH, allowing for early termination of PDCCH monitoring and saving power. If the PDCCH is present, the UE receives from the network entity one or more downlink control information (DCIs) in the CORESET.