Reference Cell Availability Checks for DRX Uplink Timing

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Solution Overview

Problem

Existing wireless communication networks, particularly those utilizing the unlicensed spectrum, face challenges in determining reliable reference cell timing due to issues with synchronization signal availability and channel access failures during discontinuous reception in DRX modes, which are not adequately addressed by current specifications.

Innovation Solution

Proposes various approaches for determining reference cell availability and timing advance in DRX operation, including criteria for evaluating SSB and TRS availability based on successful channel access within specific time thresholds, and using aperiodic CSI-RS for timing tracking, to ensure accurate uplink transmission timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the network operates in unlicensed spectrum with DRX mode, then energy efficiency is improved, but reference cell timing reliability deteriorates due to channel access failures

Engineering Contradiction:

Improveenergy efficiencyVSAvoidreference cell timing reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by determining reference cell availability in advance before uplink transmissions. The UE checks whether the reference cell is available during DRX active times before attempting uplink transmission, preventing timing errors caused by channel access failures. This advance verification ensures that energy efficiency is maintained through DRX operation while reliability is preserved by avoiding transmissions when reference cell timing is unavailable.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If SSB burst transmission is performed in unlicensed spectrum, then synchronization signal availability is improved, but channel access failures increase due to LBT requirements

Engineering Contradiction:

Improvesynchronization signal availabilityVSAvoidchannel access failures

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial action by checking reference cell availability based on partial reception of synchronization signals rather than requiring complete successful reception. The UE determines reference cell availability if at least one SSB is received within the burst, even if other SSBs fail due to LBT. This partial verification approach maintains synchronization signal availability while accommodating the inherent channel access failures in unlicensed spectrum.

Inventive Principle:

Principle #16Partial or excessive action

3Measurement precision

If DRX active time is extended to ensure reference cell availability, then timing accuracy is improved, but energy consumption increases

Engineering Contradiction:

Improvetiming accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the reference cell availability determination based on DRX configuration parameters. The network configures specific DRX active times and measurement timing configurations that balance timing accuracy requirements with energy consumption constraints. The UE uses these configured parameters to determine reference cell availability only during specified active times, achieving timing accuracy while maintaining energy efficiency through controlled DRX operation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250247804A1Reference cell timing determination

Publication Date: 2025.07.31 APPLE INC

AI summary

The present application relates to devices and components including apparatus, systems, and methods to determine availability of a reference cell for determining a timing of an uplink transmission in a user equipment transmission occasion.