Uplink Grant Subframe Detection for Handover Interruption

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Solution Overview

Problem

In wireless communication networks, especially in high-density user areas, handover processes between small cells and macro cells often result in radio link failures (RLF) leading to prolonged interruption times due to the need for UE to re-establish radio connections, which can cause data communication disruptions or dropped calls.

Innovation Solution

The solution involves providing UEs with specific information about downlink subframes containing uplink grants beforehand, allowing them to quickly re-establish radio connections without triggering a complete random access procedure, thereby reducing interruption time and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UE performs complete random access procedure to re-establish radio connection after handover, then connection reliability is improved, but interruption time increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidinterruption time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The network pre-configures the UE with information about specific downlink subframes where uplink grants will be transmitted during handover. This preliminary action allows the UE to proactively monitor these designated subframes instead of performing a complete random access procedure, thereby reducing interruption time while maintaining connection reliability through pre-arranged resource allocation.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If UE monitors all downlink subframes for uplink grants during handover, then grant detection reliability is improved, but processing complexity increases

Engineering Contradiction:
Improvegrant detection reliabilityVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of uniformly monitoring all downlink subframes, the network provides targeted information about specific subframes where uplink grants will be transmitted. The UE then concentrates its monitoring efforts on these localized, predetermined subframes, reducing processing complexity while maintaining grant detection reliability through focused resource allocation.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If UE performs complete random access procedure, then interference is reduced, but handover speed decreases

Engineering Contradiction:
ImproveinterferenceVSAvoidhandover speed
Core Design Contradiction:
Object-affected harmful factorsVSSpeed

Solution Approach 1:

The UE skips the lengthy complete random access procedure by utilizing pre-configured uplink grant information. By rushing through the handover process using predetermined resource allocations and monitoring only specific downlink subframes, the UE achieves faster handover speed while the targeted approach to grant detection minimizes unnecessary interference compared to universal monitoring.

Inventive Principle:
Principle #21Skipping (Rushing through)

Data Source

PatentEP2943034B1Identifying a subframe containing information relating to an uplink grant
Publication Date: 2020.08.05 BLACKBERRY LTD
  • EP2943034B1 patent drawingFigure 1~2
  • EP2943034B1 patent drawingFigure 3
  • EP2943034B1 patent drawingFigure 4~5

AI summary

A user equipment (UE) receives a message identifying a subframe containing information relating to an uplink grant to be sent by a target cell.