Handling Duplicate EPS Bearer IDs During 5G to LTE Inter-System Change

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Solution Overview

Problem

During inter-system changes from 5G to 4G LTE (EPS) networks, collisions occur due to duplicate EPS bearer IDs, leading to undefined UE behavior and potential service disruptions, as existing mapped EPS bearer contexts are not properly handled.

Innovation Solution

The method involves the UE receiving a mapped EPS bearer context IE to create a new EPS bearer, detecting collisions with existing EPS bearers having the same EBI, and either replacing or deleting the existing EPS bearer through explicit signaling, ensuring no EPS collisions occur during inter-system changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the UE creates a new mapped EPS bearer with a duplicate EBI during PDU session establishment, then the new bearer is established, but a collision occurs with the existing EPS bearer having the same EBI

Engineering Contradiction:

ImprovePDU session establishment speedVSAvoidEPS bearer collision

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The UE performs preliminary detection of EBI duplication before completing the bearer creation process. When a duplicate EBI is detected, the UE proactively deletes the existing EPS bearer with the duplicate EBI before establishing the new mapped EPS bearer, preventing collision from occurring in the first place

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The existing EPS bearer with the duplicate EBI is extracted (deleted) from the system before the new mapped EPS bearer is established. This removes the conflicting element that would cause the collision, allowing the new bearer to be created without interference

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the UE deletes the existing EPS bearer with duplicate EBI, then the collision is resolved, but signaling overhead increases

Engineering Contradiction:

ImproveEPS bearer collision resolutionVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The UE autonomously detects and resolves the EBI duplication conflict without requiring network intervention. The UE independently identifies the duplicate EBI, deletes the conflicting existing bearer, and proceeds with creating the new mapped EPS bearer, eliminating the need for additional signaling messages to the network

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11284458B2Handling of mapped EPS bearer context with duplicate EPS bearer ID

Publication Date: 2022.03.22 MEDIATEK INC

AI summary

A method of handling mapped EPS bearer context with duplicate EPS bearer ID (EBI) for 5GS to EPS inter-system change enhancement is proposed. UE is provided with a mapped EPS bearer context IE by the network to create a new mapped EPS bearer associated with a PDU session. UE detects collision of the new mapped EPS bearer—it has the same EBI as an existing EPS bearer. Upon successfully process the create request, UE either replaces the existing EPS bearer with the new mapped EPS bearer, or deletes the EPS bearer with duplicate EBI by explicit signaling to the network. As a result, when inter-system change from 5G to EPS happens, there is no EPS collision.