RRC Inactive Small Data Transmission Across NUL and SUL Carriers

Solution Overview

Problem

In next-generation wireless networks, UEs in the RRC_INACTIVE state face inefficiencies due to unnecessary power consumption and signaling overhead from frequent transitions to RRC_CONNECTED state for small data transmissions, which is exacerbated by the lack of effective mechanisms for small data transmission in this state.

Innovation Solution

A method for a UE to manage data transmission in the RRC_INACTIVE state by utilizing normal (NUL) and supplementary (SUL) frequency carriers, selecting one for small data transmission (SDT) and stopping the procedure under predefined conditions, including cell reselection, AS security errors, or timing advance expiration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If UE transitions to RRC_CONNECTED state for small data transmissions, then data transmission capability is improved, 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 segments the uplink transmission resources into two distinct frequency carriers: Normal Uplink (NUL) and Supplementary Uplink (SUL). This segmentation allows the UE to select the appropriate carrier for small data transmissions while remaining in RRC_INACTIVE state, avoiding full connection resumption and thereby reducing power consumption while maintaining transmission capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary configuration of UL resources including configured grants (CG) and random access (RA) resources on both NUL and SUL carriers during RRC_INACTIVE state. This preliminary setup enables the UE to perform small data transmissions without transitioning to RRC_CONNECTED state, thus reducing signaling overhead and power consumption while maintaining data transmission capability.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If UE transitions to RRC_CONNECTED state for small data transmissions, then data transmission capability is improved, but signaling overhead increases

Engineering Contradiction:

Improvedata transmission capabilityVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the uplink transmission resources into two distinct frequency carriers: Normal Uplink (NUL) and Supplementary Uplink (SUL). This segmentation allows the UE to select the appropriate carrier for small data transmissions while remaining in RRC_INACTIVE state, avoiding full connection resumption and thereby reducing power consumption while maintaining transmission capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary configuration of UL resources including configured grants (CG) and random access (RA) resources on both NUL and SUL carriers during RRC_INACTIVE state. This preliminary setup enables the UE to perform small data transmissions without transitioning to RRC_CONNECTED state, thus reducing signaling overhead and power consumption while maintaining data transmission capability.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple UL frequency carriers are configured, then transmission flexibility is improved, but UE complexity increases

Engineering Contradiction:

Improvetransmission flexibilityVSAvoidUE complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic selection mechanisms where the UE can switch between NUL and SUL carriers based on real-time conditions such as channel quality, transmission requirements, and network configuration. This dynamic adaptability provides transmission flexibility while managing UE complexity through standardized selection criteria and control procedures.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12581482B2Data transmission management in Radio Resource Control (RRC) inactive state

Publication Date: 2026.03.17 SHARP KK

AI summary

A method performed by a user equipment (UE) for transmitting uplink (UL) data in a radio resource control (RRC)_INACTIVE state is provided. The method includes receiving, from a serving cell, a configuration of at least one UL resource associated with a normal UL (NUL) frequency carrier and a supplementary UL (SUL) frequency carrier of a plurality of UL frequency carriers; selecting one of the NUL frequency carrier or the SUL frequency carrier; initiating a small data transmission (SDT) procedure in the RRC_INACTIVE state to transmit, to the serving cell, at least one UL packet on the selected one of the NUL frequency carrier or the SUL frequency carrier via the at least one UL resource; and stopping the SDT procedure in a case that at least one predefined condition is fulfilled.