Terminal Protocol Layer State Management in RRC Inactive Mode

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Solution Overview

Problem

In next-generation mobile communication systems, there is a need for an efficient method to transition between RRC connected and inactive modes to reduce power consumption and signaling procedures, while ensuring secure data transmission and preventing state inconsistency between protocol layer devices.

Innovation Solution

The proposed solution involves specific operations and procedures for protocol layer devices, including MAC, RLC, and PDCP, during state transitions, with emphasis on encryption and decryption procedures in the RRC inactive mode to prevent unnecessary data transmission and state inconsistencies, and includes connection release and setup procedures that consider security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal continuously receives and identifies base station signals to maintain RRC connected mode, then connection reliability is improved, but power consumption increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidterminal power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic state transitions between RRC connected and inactive modes based on data activity patterns. The terminal adapts its operational state by entering inactive mode during periods of no data transmission to conserve power, while maintaining the ability to quickly resume connected mode when data activity resumes, thus balancing power consumption with connection reliability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary actions by establishing security contexts and maintaining protocol layer states in advance during connected mode. When transitioning to inactive mode, the terminal preserves essential security parameters and protocol states, enabling rapid resumption without full re-establishment, thereby reducing power consumption while maintaining connection reliability

Inventive Principle:
Principle #10Preliminary action

2Use of energy by moving object

If the terminal transitions to RRC inactive mode to save power, then power consumption is reduced, but connection establishment time increases when resuming

Engineering Contradiction:
Improveterminal power consumptionVSAvoidconnection establishment time
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by establishing and preserving security contexts, protocol layer states, and configuration parameters during the initial connected mode. When transitioning to inactive mode, these pre-established elements are maintained in a suspended state, enabling rapid resumption without full re-establishment procedures, thus reducing both power consumption and connection establishment time

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates and maintains copies of essential protocol layer states and security parameters during the transition to inactive mode. These copied states are preserved in the terminal's memory, allowing quick restoration when resuming connected mode, thereby minimizing connection establishment time while maintaining power-saving benefits

Inventive Principle:
Principle #26Copying

3Stability of the object's composition

If protocol layer devices maintain state information during RRC inactive mode, then state consistency is improved, but security risks increase

Engineering Contradiction:
Improvestate consistencyVSAvoidsecurity risks
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the protocol layer state information into different components with different retention policies. Critical security parameters such as security contexts and cryptographic keys are preserved to maintain state consistency, while non-essential data is discarded or reset. This selective segmentation maintains state consistency for essential functions while reducing security risks by eliminating unnecessary stored information

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a discard and recover mechanism where non-essential protocol layer data is discarded during transition to inactive mode, while essential security parameters are preserved. Upon resumption, the terminal recovers only the necessary security contexts and reconstructs non-essential states, thereby maintaining state consistency for critical functions while minimizing security risks from stored data

Inventive Principle:
Principle #34Discarding and recovering

4Reliability

If the terminal performs full PDCP entity re-establishment upon resuming from inactive mode, then data transmission reliability is improved, but signaling overhead increases

Engineering Contradiction:
Improvedata transmission reliabilityVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial action by performing only necessary PDCP entity re-establishment procedures upon resuming from inactive mode. Instead of full re-establishment, the terminal selectively restores only those PDCP parameters and states that are essential for current data transmission requirements. This partial approach maintains data transmission reliability for critical functions while reducing signaling overhead by omitting redundant re-establishment steps

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4156783B1Method and apparatus for operating protocol layer of terminal in inactive mode in next-generation mobile communication system
Publication Date: 2024.08.28 SAMSUNG ELECTRONICS CO LTD
  • EP4156783B1 patent drawingFigure 1
  • EP4156783B1 patent drawingFigure 2
  • EP4156783B1 patent drawingFigure 3

AI summary

A communication method and a system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of things (loT) are provided. The disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The disclosure relates to schemes for improving an operation of a terminal in an RRC inactive mode.