DRX Reference Signal Configuration for mmWave Beam Training

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Solution Overview

Problem

Millimeter-wave wireless communication systems face challenges in maintaining link quality during discontinuous reception (DRX) mode due to beam degradation and interference, especially in high-frequency bands like 28 GHz, where path loss and mobility affect beam alignment and signal strength.

Innovation Solution

The solution involves configuring reference signals, such as measurement reference signals (MRS), based on DRX parameters to adjust periodicity and density, allowing for beam refinement and recovery during DRX cycles, enabling more frequent training during longer cycles and less frequent training during shorter cycles, and allowing the UE to request adjustments based on mobility and link quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If beam training is performed frequently to maintain link quality during DRX mode, then link reliability is improved, but power consumption and system overhead increase

Engineering Contradiction:
Improvelink qualityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements dynamic beam training adaptation where the beam training periodicity and density are adjusted based on DRX cycle length, UE mobility state, and link quality conditions. During longer DRX cycles or when mobility is detected, beam training is performed more frequently; during shorter DRX cycles or stable conditions, it is reduced. This dynamic adjustment resolves the contradiction by making beam training frequency adaptive rather than fixed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes key parameters including beam training periodicity, reference signal density, and beam refinement frequency based on DRX configuration and channel conditions. By modifying these parameters dynamically according to operational context, the system maintains link reliability during extended DRX periods while reducing unnecessary beam training during shorter cycles, thereby balancing reliability with power consumption.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If beam training periodicity is increased to adapt to mobility and angular changes, then beam alignment accuracy is improved, but signaling overhead and processing complexity increase

Engineering Contradiction:
Improvebeam alignment accuracyVSAvoidsignaling overhead
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs beam training and reference signal measurements in advance during DRX on-duration periods to prepare beam alignment before the UE enters DRX off period. By conducting beam training proactively based on predicted mobility patterns and DRX timing, the system ensures beam alignment is ready before needed, reducing the need for frequent mid-DRX beam training and associated signaling overhead.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from reference signal measurements, mobility indicators, and link quality reports to dynamically adjust beam training periodicity and density. This feedback mechanism allows the system to increase beam training only when and where needed based on actual channel conditions and UE movement, rather than uniformly across all DRX cycles, thereby improving beam alignment accuracy while controlling signaling overhead.

Inventive Principle:
Principle #23Feedback

3Reliability

If reference signal density is increased during DRX cycles, then link recovery capability is improved, but resource consumption and interference increase

Engineering Contradiction:
Improvelink recovery capabilityVSAvoidinterference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments reference signal transmissions into different densities based on DRX cycle phases and link condition states. During DRX on-duration or when link degradation is detected, reference signal density is increased to enable link recovery. During stable link conditions or DRX off periods, reference signal density is reduced. This segmentation approach ensures link recovery capability is available when needed while minimizing interference and resource consumption during stable periods.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements periodic reference signal transmissions synchronized with DRX cycles, where reference signal density is periodically adjusted based on the DRX timing and link quality. This periodic action pattern allows the system to maintain link recovery capability at appropriate intervals while avoiding continuous high-density reference signal transmission that would cause excessive interference and resource consumption.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP3504930B1Beam training for discontinuous reception (DRX) mode operation
Publication Date: 2021.02.17 QUALCOMM INC
  • EP3504930B1 patent drawingFigure 1
  • EP3504930B1 patent drawingFigure 2
  • EP3504930B1 patent drawingFigure 3

AI summary

Aspects of the present disclosure relate to wireless communications and, more particularly, to configuration of reference signals for beam refinement, based on DRX parameters. For example, a method of wireless communications by a base station may include determining a reference signal configuration for a user equipment (UE) based, at least in part, on one or more discontinuous reception (DRX) parameters, and signaling the reference signal configuration and the one or more DRX parameters to the UE.