Timing Advance Maintenance in RRC Inactive State for Small Data Transmission

Solution Overview

Problem

User equipment (UE) does not support small data transmission in the RRC_INACTIVE state, leading to unnecessary power consumption and signaling overhead due to the need to switch between different states for data transmission, which is inefficient and resource-intensive.

Innovation Solution

A method for maintaining timing advance (TA) validity in the RRC_INACTIVE state through a random access procedure using pre-configured resources and timers, allowing for small data transmission without the need for frequent state changes, ensuring uplink synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If UE switches between RRC states for data transmission, then data transmission capability is achieved, but power consumption and signaling overhead increase

Engineering Contradiction:

Improvedata transmission capabilityVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by maintaining the RRC_INACTIVE state with preserved timing advance information and pre-configured resources, allowing the UE to perform small data transmissions without transitioning to RRC_CONNECTED state. The network device maintains downlink assignment information and timing advance validity in the RRC_INACTIVE state, enabling early data transmission before full connection establishment is required.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the RRC state management by introducing a distinct RRC_INACTIVE state that is separate from both RRC_IDLE and RRC_CONNECTED states. This segmented state allows partial functionality (small data transmission) while maintaining power savings, avoiding the need for complete state transitions and reducing the energy overhead associated with full connection establishment and release.

Inventive Principle:

Principle #1Segmentation

2Productivity

If UE switches between RRC states for data transmission, then data transmission capability is achieved, but signaling overhead increases

Engineering Contradiction:

Improvedata transmission capabilityVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent applies preliminary action by maintaining the RRC_INACTIVE state with preserved timing advance information and pre-configured resources, allowing the UE to perform small data transmissions without transitioning to RRC_CONNECTED state. The network device maintains downlink assignment information and timing advance validity in the RRC_INACTIVE state, enabling early data transmission before full connection establishment is required.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the RRC state management by introducing a distinct RRC_INACTIVE state that is separate from both RRC_IDLE and RRC_CONNECTED states. This segmented state allows partial functionality (small data transmission) while maintaining power savings, avoiding the need for complete state transitions and reducing the energy overhead associated with full connection establishment and release.

Inventive Principle:

Principle #1Segmentation

3Reliability

If pre-configured resource and timer are used to maintain TA validity, then uplink synchronization is achieved, but device complexity increases

Engineering Contradiction:

Improveuplink synchronizationVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing the RRC_INACTIVE state to serve multiple functions simultaneously: it maintains timing advance validity for uplink synchronization, preserves downlink assignment information for data transmission, and enables pre-configured resource utilization. The same state structure handles both synchronization maintenance and data transmission preparation, reducing the need for separate mechanisms and minimizing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20240334359A1Method for timing advance maintenance in uplink synchronization, terminal device, and chip

Publication Date: 2024.10.03 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

A method for timing advance (TA) maintenance in uplink (UL) synchronization, a terminal device, and a chip are provided in embodiments of the disclosure. The method includes the following. A terminal device in a radio resource control (RRC) inactive state triggers a random access procedure in UL small data transmission (SDT) based on a pre-configured resource. In the random access procedure, the pre-configured resource and/or a corresponding first timer is operated to maintain validity of a TA.