RRC Release Cause for Inactive State Transition

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Solution Overview

Problem

Current communication systems in 5G networks face challenges in efficiently transitioning user equipment (UE) between connected and idle states, particularly in differentiating between suspending to an idle state (RRC_IDLE) and an inactive state (RRC_INACTIVE) using RRC release messages.

Innovation Solution

Incorporating a release cause value in RRC release messages to indicate whether the UE should transition to an RRC_INACTIVE state, using explicit or implicit indications such as specific cause values or the presence/absence of a suspend configuration field, allowing for delta-signaling of configuration parameters specific to the RRC_INACTIVE state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If RRC release messages are used to transition UE between connected and idle states, then state transition control is enabled, but signaling overhead increases and power consumption rises

Engineering Contradiction:

Improvestate transition controlVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent extracts and separates the suspend configuration information from the general RRC release message structure. By using dedicated fields (suspendConfig, suspendIndication) specifically for suspend-to-inactive operations, the message can be optimized to include only necessary information, reducing overall signaling overhead while maintaining precise control functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces new parameters (suspendIndication flag, suspendConfig structure with resumeIdentity, ran-NotificationAreaInfo, periodic-RNAU-timer) that change the state transition behavior. These parameter changes enable the network to control whether UE transitions to idle or inactive state, providing flexible operation control without requiring separate message types for each transition scenario.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If explicit indications are used in RRC release messages to differentiate suspend-to-idle and suspend-to-inactive, then state differentiation clarity improves, but signaling overhead increases

Engineering Contradiction:

Improvestate differentiation clarityVSAvoidsignaling overhead

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies partial action by conditionally including suspend configuration fields only when suspend-to-inactive transition is intended. The suspendIndication flag and suspendConfig structure are present only in messages requiring inactive state transition, while standard RRC release messages for idle transition omit these fields, achieving clear differentiation without universal overhead.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the RRC release message into functional components: basic release information (common to all transitions) and suspend-specific configuration (only for inactive transitions). This segmentation allows the network to send minimal messages for simple idle transitions while providing comprehensive configuration only when inactive state with suspend functionality is required.

Inventive Principle:

Principle #1Segmentation

3Productivity

If delta-signaling of configuration parameters is implemented for RRC_INACTIVE state, then signaling efficiency improves, but message complexity increases

Engineering Contradiction:

Improvesignaling efficiencyVSAvoidmessage complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring suspend parameters (resumeIdentity, ran-NotificationAreaInfo, periodic-RNAU-timer) in the suspend configuration message before the UE enters inactive state. When UE needs to resume or update configuration, it can use these pre-configured values or perform incremental updates, avoiding the need to re-transmit complete configuration sets and improving subsequent signaling efficiency.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250151154A1Release cause for transition from connected state

Publication Date: 2025.05.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Systems, methods, and apparatus for handling communications relating to suspending a user equipment in a radio access network (RAN) are disclosed. An example method includes the user equipment receiving a radio resource control (RRC) release message from a network node. The user equipment determines that the RRC release message includes a suspend configuration field. The user equipment applies delta signalling corresponding to a suspend configuration indicated by the suspend configuration field and transitions to an inactive state.