Dynamic CFRA Resource Updates for Conditional Handover

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Solution Overview

Problem

Conditional handover (CHO) in 5G wireless systems faces challenges with outdated contention-free random access (CFRA) resources, leading to increased costs and potential fallback to contention-based random access due to longer resource reservation times and higher risks of resource obsolescence, especially in scenarios with high mobility and frequent handovers.

Innovation Solution

The method involves the network autonomously updating CFRA resources by receiving a pool of resources from a target cell, allowing the source cell to dynamically allocate new CFRA resources based on measurement reports from UEs, reducing the number of reserved resources and avoiding race conditions, thereby ensuring efficient and timely updates of CFRA resources during CHO.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If CFRA resources are reserved for longer periods to ensure availability during CHO, then handover reliability is improved, but resource obsolescence risk increases and costs increase

Engineering Contradiction:
Improvehandover reliabilityVSAvoidresource obsolescence
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent implements dynamic CFRA resource management where the source cell autonomously updates CFRA resources based on current network conditions and UE measurement reports. Instead of static long-term reservation, the system dynamically adjusts resource allocation timing and quantities, allowing resources to be refreshed before obsolescence occurs while maintaining handover reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system employs feedback mechanisms through UE measurement reports that provide real-time information about target cell conditions. The source cell uses this feedback to determine when and how to update CFRA resources, creating a closed-loop system that prevents resource obsolescence by triggering updates based on actual network state changes rather than fixed timing.

Inventive Principle:
Principle #23Feedback

2Reliability

If CFRA resources are reserved for more UEs and longer durations, then handover success rate is improved, but network overhead and costs increase

Engineering Contradiction:
Improvehandover success rateVSAvoidnetwork overhead
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The source cell autonomously manages CFRA resource updates without requiring target cell intervention or extensive signaling. The system self-determines when updates are needed based on measurement reports and self-executes the resource reassignment, eliminating unnecessary overhead while ensuring handover success through timely resource availability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the temporal parameters of resource reservation from long-term static allocation to short-term dynamic allocation. By adjusting the timing and duration of resource reservations based on actual handover needs and network conditions, the system maintains high handover success rates while minimizing the total resource reservation time and associated overhead.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the network autonomously updates CFRA resources, then resource freshness is improved, but signaling overhead increases

Engineering Contradiction:
Improveresource freshnessVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The source cell performs preliminary CFRA resource updates based on prediction from measurement reports before handover execution is needed. By proactively refreshing resources in advance based on trending data from UEs, the system ensures resource freshness is maintained without requiring frequent reactive signaling updates during critical handover moments.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3716682B1Updating contention free random access resources during conditional handover
Publication Date: 2025.03.26 NOKIA TECHNOLOGIES OY
  • EP3716682B1 patent drawingFigure 1
  • EP3716682B1 patent drawingFigure 2a
  • EP3716682B1 patent drawingFigure 2b

AI summary

Systems, methods, apparatuses, and computer program products for updating contention free random access (CFRA) resources during conditional handover are provided.