RRC Core Network Indication for EPC–5GC Handover Security

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Solution Overview

Problem

Current inter-system handover procedures in 5G networks lack clear indication of the target core network and proper signaling of security parameters, leading to inefficiencies and improper handling of security contexts during intra-RAT, inter-system handovers between Evolved Packet Core (EPC) and 5G Core Network (5GC).

Innovation Solution

Incorporating a modified or new information element in the RRCConnectionReconfiguration message to indicate the target core network and provide necessary security parameters, enabling the user equipment to recognize and apply the correct security contexts for seamless handovers between EPC and 5GC.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current inter-system handover procedures are used without target core network indication, then the handover process can be completed, but the user equipment cannot properly identify and apply the correct security contexts leading to improper security parameter handling

Engineering Contradiction:
Improvesecurity context handlingVSAvoidtarget core network identification
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The target core network type is indicated in advance in the RRCConnectionReconfiguration message before the handover execution. This preliminary indication allows the user equipment to prepare and apply the correct security parameters in advance, ensuring proper security context handling without delays or errors during the actual handover process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A new information element is introduced as an intermediary carrier in the RRCConnectionReconfiguration message to convey the target core network type. This intermediary mechanism enables the network to transmit essential identification information to the user equipment, which then uses this information to correctly identify and apply the appropriate security contexts for the handover.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If security parameters are not properly signaled during inter-system handover, then the handover procedure can proceed, but the user equipment may apply incorrect security contexts causing security issues

Engineering Contradiction:
Improvesecurity parameter handlingVSAvoidsecurity context mapping
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The correct security parameters are signaled in advance along with the target core network type indication. This allows the user equipment to prepare and apply the appropriate security contexts before the handover executes, eliminating the need for complex real-time security parameter determination and reducing the risk of applying incorrect security settings.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the RRCConnectionReconfiguration message is enhanced with target core network indication and security parameters, then handover efficiency and security are improved, but the message structure becomes more complex

Engineering Contradiction:
Improvehandover efficiencyVSAvoidRRC message structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The enhanced RRCConnectionReconfiguration message is segmented into existing fields and a new information element. The new information element is structured as a separate, self-contained component that carries the target core network type and associated security parameters. This segmentation allows the message to maintain its原有 structure while adding necessary functionality, making the complexity manageable and the implementation straightforward.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3804402B1Core network indication and security handling for handover
Publication Date: 2025.08.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3804402B1 patent drawingFigure 1
  • EP3804402B1 patent drawingFigure 2
  • EP3804402B1 patent drawingFigure 3

AI summary

A method for a handover procedure comprises establishing a connection with a source network node of a first core network; receiving a radio resource control (RRC) message including an information element, wherein the information element indicates a second core network associated with a target network node; applying security parameters based on the second core network indicated in the information element; and performing a handover toward the target network node using the applied security parameters. The method provides an indication in RRC connection reconfiguration procedure to indicate the UE the core network of the target network node, so that the UE may recognize that this is an inter-system handover and apply corresponding security parameters for performing the handover without additional signaling.