Conditional Handover Execution in 5G NR User Equipment

Solution Overview

Problem

Current 5G NR handover procedures experience data transmission interruptions due to delayed handover commands, which is not compatible with the requirement of '0ms' latency for seamless mobility, and often result in unnecessary handovers and signaling overheads.

Innovation Solution

A method where the UE receives a handover command with a condition for execution, allowing it to monitor and only perform the handover when the condition is met, thereby reducing data transmission interruption time and avoiding incorrect handovers and signaling overheads, applicable to both NR and LTE systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a handover command is delivered in advance through conditional handover, then data transmission interruption time is reduced, but device complexity and signaling overhead increase due to condition monitoring requirements

Engineering Contradiction:

Improvedata transmission interruption timeVSAvoidcondition monitoring complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The base station performs handover preparation in advance by selecting a target base station and generating a handover command before the handover condition is met. The handover command is delivered to the UE in advance through RRC signaling, containing conditional handover execution conditions. This preliminary action allows the UE to have the handover command ready, reducing data transmission interruption when the condition is satisfied.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE continuously monitors handover execution conditions (such as signal quality thresholds) and compares them against the pre-delivered handover command. When the condition is satisfied, the UE executes the handover. This feedback mechanism ensures handover is performed at the optimal moment while utilizing pre-prepared resources, balancing early preparation with condition-based execution.

Inventive Principle:

Principle #23Feedback

2Speed

If a conservative measurement report threshold is set for early handover preparation, then handover command delivery is accelerated, but unnecessary handovers increase due to premature triggering

Engineering Contradiction:

Improvehandover preparation speedVSAvoidhandover accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The handover execution condition is dynamically adjustable. The base station can configure the UE with execution conditions such as signal quality thresholds or time-to-trigger parameters. These conditions can be adjusted based on network state, UE capabilities, and service requirements, allowing the system to balance between early preparation and accurate triggering rather than using a fixed conservative threshold.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The base station performs handover preparation in advance by selecting a target base station and generating a handover command before the handover condition is met. The handover command is delivered to the UE in advance through RRC signaling, containing conditional handover execution conditions. This preliminary action allows the UE to have the handover command ready, reducing data transmission interruption when the condition is satisfied.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If the UE immediately executes the handover command upon receipt, then handover latency is minimized, but data transmission interruption occurs

Engineering Contradiction:

Improvehandover execution latencyVSAvoiddata transmission continuity

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The base station performs handover preparation in advance by selecting a target base station and generating a handover command before the handover condition is met. The handover command is delivered to the UE in advance through RRC signaling, containing conditional handover execution conditions. This preliminary action allows the UE to have the handover command ready, reducing data transmission interruption when the condition is satisfied.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE continuously monitors handover execution conditions (such as signal quality thresholds) and compares them against the pre-delivered handover command. When the condition is satisfied, the UE executes the handover. This feedback mechanism ensures handover is performed at the optimal moment while utilizing pre-prepared resources, balancing early preparation with condition-based execution.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3562208B1User mobility method and device

Publication Date: 2024.03.13 SHARP KK

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AI summary

The present application provides a method performed by user equipment (UE), comprising: receiving, from a base station, a first radio resource control (RRC) message including a handover command; determining whether a first condition included in the first RRC message is met; and if the first condition is met, sending a handover indication to the base station, the handover indication being used to inform the base station that the UE is about to start performing a handover. The present application further provides UE and a corresponding base station. By means of the technical solution of the present application, the data transmission interruption time in the handover procedure in the NR can be further reduced, and an unnecessary incorrect handover is avoided.