Secondary RAT Node Overload Indication for UE Redirection

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Solution Overview

Problem

In wireless communication networks with multiple Radio Access Technologies (RATs), handovers from an overloaded primary RAT to a secondary RAT can cause 'ping-ponging' due to lack of knowledge about the primary RAT's load condition, reducing network efficiency.

Innovation Solution

A method where a node in the secondary RAT receives overload messages from the primary RAT, sending broadcast messages to User Equipment (UEs) to prevent them from switching back to the overloaded primary RAT, using either UE-assisted or network-based overload indication methods, and stopping these messages when the overload condition ends.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inter-RAT mechanisms redirect UEs to secondary RAT when primary RAT is overloaded, then UE overload protection is improved, but ping-ponging between RATs occurs due to lack of load condition knowledge

Engineering Contradiction:

ImproveUE overload protectionVSAvoidnetwork efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism where the secondary RAT node receives overload indication messages from the primary RAT node and sends broadcast messages to UEs to inform them of the overload condition. This feedback loop allows the secondary RAT to make informed decisions about UE redirection, preventing UEs from repeatedly switching back to the overloaded primary RAT and eliminating ping-ponging behavior while maintaining reliable overload protection.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If secondary RAT has no knowledge of primary RAT load condition, then inter-RAT independence is maintained, but UE switching decisions become suboptimal causing ping-ponging

Engineering Contradiction:

Improveinter-RAT independenceVSAvoidUE switching decision quality

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent introduces an intermediary communication mechanism where the primary RAT node sends overload indication messages to the secondary RAT node. This intermediary information transfer allows the secondary RAT to make informed UE switching decisions without compromising the fundamental independence of the inter-RAT systems. The secondary RAT uses this information to send broadcast messages guiding UEs to remain on or switch to the secondary RAT, improving switching decision quality while maintaining system independence.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP2880918B1Method and apparatus to postpone UE from handover to an overloaded radio network from another radio network

Publication Date: 2017.11.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A node of a secondary RAT that is in communication with a primary node of a primary RAT and UEs that are able to communicate by way of the primary and secondary RATs. The node concludes a network interface unit of the node which receives a message from the primary node that indicates that the primary RAT is in an overload condition. The node includes a processing unit of the node which forms UE messages for the UEs not to try to communicate with the primary RAT, the network interface unit of the node sending the messages to the UEs. A method of a node of a secondary RAT that is in communication with a primary node of a primary RAT and UEs that are able to communicate by way of the primary and secondary RATs.