Small Data Transmission in RRC Inactive State

Solution Overview

Problem

Current wireless communication systems face inefficiencies in transmitting small data without transitioning to the RRC_CONNECTED state, leading to high power consumption and signaling overhead, and lack effective mechanisms for providing feedback for such transmissions.

Innovation Solution

Implementing a user device and base station system that allows for uplink and downlink transmissions in the RRC_INACTIVE or RRC_IDLE states without entering the RRC_CONNECTED state, using configured grants or pre-configured resources, and providing HARQ feedback through paging occasions using configured or new DCI formats.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE transitions to RRC_CONNECTED state for data transmission, then reliable communication is achieved, but power consumption increases and signaling overhead increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The RRC state is segmented into three distinct states (RRC_IDLE, RRC_INACTIVE, RRC_CONNECTED) with different levels of activity. The patent utilizes RRC_INACTIVE as an intermediate state that provides partial connectivity without full RRC_CONNECTED functionality, allowing data transmission while maintaining lower power consumption and reduced signaling overhead compared to complete state transition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the RRC state based on transmission requirements. For small data transmissions, the UE remains in RRC_INACTIVE state without transitioning to RRC_CONNECTED, enabling flexible adaptation between different operational modes to balance reliability needs with power consumption and signaling overhead.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the UE transitions to RRC_CONNECTED state for data transmission, then communication reliability is improved, but signaling overhead increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The RRC state is segmented into three distinct states (RRC_IDLE, RRC_INACTIVE, RRC_CONNECTED) with different levels of activity. The patent utilizes RRC_INACTIVE as an intermediate state that provides partial connectivity without full RRC_CONNECTED functionality, allowing data transmission while maintaining lower power consumption and reduced signaling overhead compared to complete state transition.

Inventive Principle:

Principle #1Segmentation

3Use of energy by moving object

If HARQ feedback is provided through paging occasions, then power efficiency is improved, but feedback delivery time increases

Engineering Contradiction:

Improvepower efficiencyVSAvoidfeedback delivery time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The system uses periodic paging occasions for HARQ feedback delivery, where the UE monitors for feedback at predetermined time intervals. This periodic monitoring allows the UE to remain in low-power RRC_INACTIVE state while still receiving necessary feedback information, balancing power efficiency with acceptable feedback delivery timing.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20220369136A1Transmission procedures for small data transmissions

Publication Date: 2022.11.17 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

A user device, UE, for a wireless communication system is described. The wireless communication system includes one or more base stations. The UE is in an RRC_INACTIVE state or in an RRC_IDLE state and is to monitor one or more paging occasions. The UE is to perform one or more uplink, UL, transmissions to the base station without entering an RRC_CONNECTED state, e.g., using a configured grant, CG, or pre-configured resources. The UE is to monitor one or more paging occasions following the one or more UL transmissions for a message from the base station, the message being associated with feedback information, e.g., HARQ feedback formation, for the one or more UL transmissions.