Conditional Handover With Candidate-Cell Trigger Conditions

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Solution Overview

Problem

Existing mobile communication systems face challenges in reducing communication interruption time and improving handover reliability, especially in unstable radio environments, due to inaccurate prediction of movement and radio state fluctuations.

Innovation Solution

A method for conditional handover that includes a user equipment receiving a handover command with a list of candidate cells and trigger conditions, allowing the UE to determine the optimal time for handover based on detailed trigger conditions specific to each candidate cell, thereby enhancing reliability and reducing communication disruptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional handover control is used, then the handover process is simple, but communication interruption time increases and handover reliability decreases in unstable radio environments

Engineering Contradiction:

Improvehandover reliabilityVSAvoidhandover control complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring multiple candidate cells and their associated trigger conditions before the actual handover occurs. The network prepares a set of candidate cells with specific trigger conditions (such as measurement thresholds) in advance, so that when handover is needed, the UE can quickly select and execute the appropriate handover without complex real-time decision-making, thereby improving reliability while controlling complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the handover decision process by dividing the target cells into multiple candidate cells, each with specific trigger conditions. Instead of a single handover decision point, the system segments the possible handover scenarios into distinct branches based on different trigger conditions, allowing more reliable handover selection in unstable radio environments

Inventive Principle:

Principle #1Segmentation

2Loss of time

If handover is triggered immediately upon detecting radio link failure, then communication interruption is reduced, but handover accuracy decreases due to unstable radio state fluctuations

Engineering Contradiction:

Improvecommunication interruption timeVSAvoidradio state measurement accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-establishing trigger conditions for each candidate cell before handover is needed. These trigger conditions include measurement thresholds and timing parameters that are configured in advance. When radio link failure occurs, the UE can immediately compare current measurements against these pre-set conditions to determine the optimal handover target, reducing communication interruption time while maintaining accuracy through the pre-configured criteria

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies beforehand cushioning by introducing a time-to-trigger parameter and measurement validity period that act as buffers or cushions. These parameters prevent immediate handover decisions based on transient measurement fluctuations, providing a cushioning effect that filters out noise while still enabling timely handover when genuine radio link failures occur, thus balancing speed and accuracy

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If multiple candidate cells are prepared for handover, then handover reliability improves, but the complexity of selecting the optimal target cell increases

Engineering Contradiction:

Improvehandover reliabilityVSAvoidoptimal cell selection difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the candidate cells into distinct groups, each associated with specific trigger conditions (such as different measurement thresholds or cell types). This segmentation simplifies the selection process by dividing the complex task of evaluating multiple cells into simpler sub-tasks of evaluating specific cell types against their corresponding trigger conditions, thereby reducing selection difficulty while maintaining high reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by assigning different trigger conditions and evaluation criteria to different candidate cells based on their specific characteristics and locations. Each cell or cell group has customized local quality attributes (such as specific measurement thresholds or priority levels), which simplifies the overall selection process by allowing the UE to evaluate cells according to their individual local qualities rather than using a uniform complex evaluation method for all cells

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12432631B2Handover control method

Publication Date: 2025.09.30 KYOCERA CORP

AI summary

A handover control according to a first aspect is a method for performing conditional handover of user equipment from a source cell to which the user equipment is connected to a target cell. The handover control method comprises receiving, by the user equipment, from the source cell, an RRC message for handover, the RRC message including identifiers of a plurality of candidate cells being candidates for the target cell; and transmitting, by the user equipment, a report message including information related to a radio link failure detected in the source cell, to a cell to which the user equipment connects after the radio link failure. The report message includes the identifiers of all the candidate cells included in the RRC message.