UE Handover Failure Prevention via Cell Off Indication

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Solution Overview

Problem

Wireless access systems face handover failures due to dynamic cell on/off during handover procedures, leading to inefficient power management and increased power consumption, as user equipment (UE) may continue to attempt handovers to powered-off target cells, causing interference and repeated random access procedures.

Innovation Solution

Implementing a method for user equipment (UE) to receive cell off indication information, such as through a Backoff Indicator field in a random access response message, to discontinue the handover procedure when a target cell is dynamically powered off, thereby preventing handover failures and optimizing power management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If dynamic cell on/off is implemented for power management, then power consumption is reduced, but handover failure rate increases

Engineering Contradiction:

Improvepower consumptionVSAvoidhandover failure rate

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The target base station performs preliminary actions by sending cell off indication information to the user equipment before the handover is completed. This allows the UE to be notified in advance that the target cell will be powered off, enabling the UE to discontinue the handover procedure before failure occurs, thus resolving the contradiction between power management and handover reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A feedback mechanism is established where the target base station provides cell off indication information to the user equipment during the handover process. This feedback loop allows the UE to receive real-time information about the target cell's power state and adjust its handover behavior accordingly, preventing handover failures while maintaining power management efficiency

Inventive Principle:

Principle #23Feedback

2Productivity

If UE continues handover attempts to powered-off cells, then handover completion rate improves, but interference increases and power consumption rises

Engineering Contradiction:

Improvehandover completion rateVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The cell off indication information provides feedback to the UE about the target cell's operational status. When the UE receives this indication, it discontinues the handover procedure, avoiding unnecessary transmission attempts to powered-off cells. This eliminates the harmful interference generated by repeated handover attempts while maintaining high handover completion rates for valid targets

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The user equipment autonomously decides to discontinue the handover procedure upon receiving cell off indication information. This self-service mechanism allows the UE to independently adjust its behavior based on network conditions, avoiding interference without requiring continuous network control intervention

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9445319B2Method and apparatus for controlling and resolving a handover failure when a dynamic cell off is occurred in wireless access system

Publication Date: 2016.09.13 LG ELECTRONICS INC

AI summary

A method and device for preventing a handover failure by a user equipment (UE) in a wireless access system supporting cell-on/off. The method includes: initiating, by a user equipment (UE), a handover procedure to a target Base Station (BS); receiving, by the UE, cell off indication information indicating that a cell of the target BS will be powered off during the handover procedure; and discontinuing, by the UE, the handover procedure according to the cell off indication information.