Delayed Handover Signalling in Mobile Networks

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Solution Overview

Problem

The existing handover mechanisms in mobile networks, particularly in LTE, result in significant signalling load at the Mobility Management Entity (MME) and Serving Gateway (SGW), especially in deployments with high numbers of handovers due to small cells and high user equipment mobility, or sensitive radio link characteristic settings.

Innovation Solution

A method and node configuration that involves starting a timer upon a user equipment (UE) handover from a source base station to a target base station, delaying control signalling for initiating data path switching until the timer expires, thereby reducing the frequency of notifications to the MME and SGW, and allowing multiple handovers to be hidden from the core network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If immediate handover signalling is performed at the MME and SGW, then the core network is promptly informed of handover events, but the signalling load at the MME and SGW becomes excessively high

Engineering Contradiction:

Improvehandover notification reliabilityVSAvoidsignalling load capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The target eNB performs preliminary action by starting a timer upon receiving handover confirmation from the source eNB. This timer delay mechanism is set up in advance to filter out frequent handovers before they reach the core network, preventing the MME and SGW from being overwhelmed by continuous handover notifications.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The timer mechanism at the target eNB acts as an intermediary between the handover execution and the core network notification. It mediates the handover information by introducing a time filter that determines when notifications are sent to the MME and SGW, thereby reducing signalling load while maintaining necessary network awareness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If handover threshold settings are made sensitive to detect slight radio link changes, then handover responsiveness is improved, but the number of handovers increases significantly

Engineering Contradiction:

Improvehandover response speedVSAvoidnumber of handovers

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The patent converts the harmful effect of frequent handovers caused by sensitive thresholds into a beneficial filtering mechanism. The timer delay at the target eNB transforms the problem of excessive handover notifications into an opportunity to identify and notify only significant handover events, converting noise into useful information.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The timer introduces a periodic action mechanism where handover notifications are suppressed during a defined time window following handover execution. This periodic filtering approach allows the system to respond to genuine handovers while ignoring transient fluctuations caused by sensitive threshold settings.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9578557B2Delayed handover signalling in a mobile network

Publication Date: 2017.02.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

In a mobile network comprising a plurality of base stations and a gateway, a user equipment may perform a handover from a source base station to a target base station. By control signalling, the handover may be notified from the target base station to a control node of the mobile network and then to the gateway so that the gateway may switch to a data path which connects the target base station and the gateway. The notification of the handover may be delayed at the target base station or at the control node, by starting a timer and sending the control signalling for initiating the path switching after expiry of the timer.