Blind Handover Coverage Estimation for Wireless Networks

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Solution Overview

Problem

The existing blind handover feature in wireless communications systems is ineffective when used with RAS-SON algorithms, as it assumes overlapping coverage areas, leading to increased dropped calls due to the lack of coverage overlap between cells using different frequency bands or radio access technologies.

Innovation Solution

A method is introduced to estimate the coverage in the target cell before initiating a blind handover, ensuring that the estimated coverage meets a criterion, thereby allowing simultaneous use of RAS-SON algorithms and blind handover while maintaining fast handover capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If RAS-SON algorithms are used to dynamically adjust cell coverage areas, then network performance and load distribution are improved, but coverage overlap between cells is reduced, leading to increased dropped calls during blind handover

Engineering Contradiction:
Improvenetwork performanceVSAvoidhandover success rate
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary coverage estimation for the target cell before initiating blind handover. The network node estimates the coverage area of the target cell using RAS-SON algorithm data, and only initiates handover if the estimated coverage meets a predetermined criterion (sufficient overlap with source cell). This preliminary check prevents handovers to cells with inadequate coverage, resolving the contradiction between dynamic cell shaping and handover reliability.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If conventional measurement configuration is performed before handover, then handover reliability is improved, but handover delay increases

Engineering Contradiction:
Improvehandover reliabilityVSAvoidhandover delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs coverage estimation of the target cell in advance, storing this information for future handover decisions. When handover is needed, the pre-stored coverage information is used immediately without requiring new measurements, thus maintaining reliability while minimizing delay.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of performing actual measurements at handover time, the system uses pre-collected coverage information (a copy of measurement data) to make handover decisions. This copying approach eliminates the need for real-time measurements during handover, reducing delay while maintaining decision accuracy.

Inventive Principle:
Principle #26Copying

3Speed

If blind handover is initiated without coverage estimation, then handover speed is improved, but handover success rate deteriorates due to insufficient coverage overlap

Engineering Contradiction:
Improvehandover speedVSAvoidhandover success rate
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The system performs coverage estimation in advance and stores the results, so that when blind handover is needed, the decision can be made immediately using pre-computed coverage information. This eliminates the need for time-consuming measurements at handover moment while ensuring coverage adequacy, thus maintaining both speed and success rate.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3272149B1Initiating blind handover
Publication Date: 2020.07.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3272149B1 patent drawingFigure 1~2
  • EP3272149B1 patent drawingFigure 3
  • EP3272149B1 patent drawingFigure 4~5

AI summary

The disclosure relates to a method (20) for initiating a blind handover of a terminal (2) in a wireless communications system (1). The terminal (2) is served by a first cell using a first frequency band and a first radio access technology, wherein the wireless communications system (1) employs a method for dynamically changing coverage in at least one of the first cell and a second cell. The method (20) comprises estimating (21) the coverage in the second cell, wherein at least one of a second frequency band and a second radio access technology of the second cell may differ from the first frequency band and the first radio access technology, an initiating (22) the blind handover for the terminal (2) to the second cell only if the estimated coverage in the second cell meets a criterion. A wireless communications system (1), computer programs and computer program products are also provided.