Handover Failure Handling in Downlink-Only Cells

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Solution Overview

Problem

In wireless communication networks, handover attempts to cells configured for downlink-only operation fail consistently, leading to inefficient network operations, inconsistent configurations, and unnecessary load on network nodes, especially when these cells are mistakenly assumed to support both uplink and downlink transmissions.

Innovation Solution

A method in a first network node that handles handover preparation failures by transmitting a request to a second network node serving a downlink-only cell, receiving an indication of the failure due to the cell's configuration, and selecting an alternative cell for handover until the downlink-only cell is reconfigured for both downlink and uplink operations, thereby avoiding repeated failed attempts and optimizing network efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If handover requests are sent to downlink-only cells, then handover attempts are made, but handover preparation consistently fails

Engineering Contradiction:
Improvehandover success rateVSAvoidnetwork operation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The source eNodeB checks the uplink/downlink configuration of the target cell before initiating handover preparation. This preliminary check prevents sending handover requests to downlink-only cells, avoiding consistent handover preparation failures and improving overall handover success rate while maintaining network operation efficiency.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If handover requests are sent to downlink-only cells, then handover attempts are made, but unnecessary load is placed on network nodes

Engineering Contradiction:
Improvehandover flexibilityVSAvoidnetwork node load
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The source eNodeB performs preliminary verification of the target cell's uplink configuration before sending handover requests. This preliminary anti-action prevents unnecessary handover attempts to downlink-only cells, reducing wasted signaling traffic and unnecessary load on network nodes while preserving handover flexibility for valid target cells.

Inventive Principle:
Principle #9Preliminary anti-action

3Ease of manufacture

If downlink-only cells are used for carrier aggregation, then cost-effective DL carrier aggregation is enabled, but network inconsistencies occur when handover is attempted

Engineering Contradiction:
Improvedeployment costVSAvoidnetwork configuration consistency
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

Before attempting handover to a target cell used for carrier aggregation, the source eNodeB verifies whether the target cell is configured for uplink operation. This preliminary action prevents handover attempts to downlink-only cells, maintaining network configuration consistency while allowing cost-effective DL carrier aggregation deployment.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3152959B1A first network node and method relating to handover in a wireless communications network
Publication Date: 2018.03.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3152959B1 patent drawingFigure 1a
  • EP3152959B1 patent drawingFigure 1b
  • EP3152959B1 patent drawingFigure 2

AI summary

A method in a first network node for handling a handover preparation failure between a first cell and a second cell in a wireless communication network. The first cell is served by the first network node and the second cell is served by a second network node. The second cell is configured for downlink operation only. The first network node transmits (401) to the second network node a handover request for handover of a user equipment from the first cell to the second cell. The first network node receives (402) from the second network node an indication. The indication indicates the handover preparation failure, and further indicates that the handover preparation failure is caused by the second cell being configured for downlink operation only. The first network node selects (403) a cell for handover based on the received indication.