UE Security Key Timing for Faster RRC Resume

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Solution Overview

Problem

The current RRC resume procedures in wireless communications networks, particularly in NR and LTE Release 15, involve unnecessary delays due to security key updates being performed before transmitting the RRCResumeRequest, which impacts control latency.

Innovation Solution

Perform security update procedures, such as deriving new security keys and configuring lower layers, either after transmitting the RRC resume request or immediately upon entering the inactive state, to expedite the resume process without delaying the transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If security key updates are performed before transmitting the RRCResumeRequest, then security protection is ensured, but resume time increases

Engineering Contradiction:
Improvesecurity protectionVSAvoidresume time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing security key derivation and configuration during the inactive state before the resume procedure is triggered. The UE derives new security keys and configures lower layers while in RRC_INACTIVE state, so that when resume is needed, these security preparations are already complete, eliminating the delay that would otherwise occur during the resume process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the timing of security updates flexible - the UE can perform security key updates at different moments (upon entering inactive state, during cell reselection, or after resume request transmission). This dynamic approach allows the system to optimize between security preparation time and resume speed based on actual operational conditions.

Inventive Principle:
Principle #15Dynamics

2Reliability

If security updates are performed immediately upon entering inactive state, then security is prepared in advance, but the resume process may be delayed

Engineering Contradiction:
Improvesecurity preparationVSAvoidresume speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent makes the security update timing dynamic by allowing the UE to choose when to perform security key derivation - either immediately upon entering inactive state, during cell reselection events, or after transmitting the resume request. This flexibility enables optimization between advance security preparation and resume speed based on actual operational conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent ensures continuity of useful action by performing security key derivation and lower layer configuration during the inactive state period, so that when resume is triggered, these preparations are already complete. This continuous preparation during idle time eliminates the need to pause resume operations for security setup.

Inventive Principle:
Principle #20Continuity of useful action

3Loss of time

If security key derivation is performed during cell reselection, then resume time is reduced, but security updates may not be completed before resume

Engineering Contradiction:
Improveresume timeVSAvoidsecurity completion
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent implements dynamic timing by allowing the UE to perform security key derivation at different moments including during cell reselection events. The UE can configure lower layers and derive keys whenever convenient, and these preparations will be in place when resume is triggered, ensuring both speed and security completion.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3834447B1User equipment and method in a wireless communications network
Publication Date: 2025.08.27 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3834447B1 patent drawingFigure 1
  • EP3834447B1 patent drawingFigure 2
  • EP3834447B1 patent drawingFigure 3

AI summary

A method performed by a User Equipment, UE, for performing a resume procedure of a connection between the UE and a network node, in a wireless communications network is provided. The resume procedure relates to a transition of the UE from an inactive state to a connected state. While the UE is in inactive state, the UE performs (801b) security update procedures related to security information to be used in the resume procedure of the connection. After receiving a resume command from the network node as a response to the resume request, the UE resumes (802b) the connection between the UE and the network node. The updated security information is used to protect the signalling between the UE and the network node.