RRC-NAS State Synchronization for Reliable 5G Data Transmission

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Solution Overview

Problem

The inconsistency between the RRC state of a terminal device and the state understood by the network device in the RRC inactive and idle states with suspend indication affects subsequent data transmission in 5G systems.

Innovation Solution

The RRC layer of the terminal device sends a first state indication to the NAS layer to ensure consistency, transferring to a corresponding first NAS state, aligning the RRC and NAS states to match the network's understanding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the terminal device determines the state to transfer to based on whether User Plane CIOT Optimization is used, then the terminal device can autonomously manage its state, but the state of the terminal device becomes inconsistent with the state that the network device understands

Engineering Contradiction:
Improveautonomous state managementVSAvoidstate consistency
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The patent introduces a feedback mechanism where the RRC layer sends state indication information to the NAS layer, and the NAS layer sends state information to the RRC layer, ensuring both layers have consistent understanding of the current state and preventing the inconsistency between terminal and network device states

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses the RRC layer as an intermediary that receives state indication from the network device and forwards it to the NAS layer, ensuring the terminal's internal state management aligns with the network's understanding

Inventive Principle:
Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the RRC connection is suspended in RRC inactive state or idle state with suspend indication, then energy consumption is reduced, but subsequent data transmission may be affected by state inconsistency

Engineering Contradiction:
Improveenergy consumptionVSAvoiddata transmission reliability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The feedback mechanism ensures that when the terminal transitions to low-power states (RRC inactive or idle with suspend indication), the state information is properly synchronized between RRC and NAS layers, preventing transmission failures and ensuring reliability while maintaining energy efficiency

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4236594B1Wireless communication method, terminal device and computer-readable storage medium
Publication Date: 2025.10.29 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP4236594B1 patent drawingFigure 1~3
  • EP4236594B1 patent drawingFigure 4~5

AI summary

Provided are a radio communication method and a terminal device. The method comprises: sending (210), by a radio resource control (RRC) stratum of a terminal device, a first state indication to a non-access stratum (NAS) of the terminal apparatus, the first state indication is used for indicating a first RRC state; and transferring (220), by the NAS of the terminal device according to the first state indication, the NAS of the terminal device to a first NAS state.