Inactive UE SDT Radio Resource Configuration Between CU and DU

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Solution Overview

Problem

There is a lack of clarity on how a base station including a central unit (CU) and a distributed unit (DU) should configure user equipment (UE) with Small Data Transmission (SDT) configuration parameters for Random Access (RA-SDT) or Configured Grant (CG-SDT) operations, especially when the UE is in an inactive state.

Innovation Solution

The CU determines and configures SDT operations by sending CU-to-DU messages to request and receive SDT DU configurations, while ignoring non-SDT configurations, to manage radio resource configurations effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the base station uses traditional configuration methods for UE in inactive state, then the UE can maintain connection, but the data transmission latency increases and efficiency decreases

Engineering Contradiction:

Improvedata transmission latencyVSAvoiddata communication efficiency

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The network configures SDT parameters and resources in advance while the UE is in connected state, storing them in the inactive state. This preliminary configuration allows the UE to immediately transmit small data packets upon entering inactive state without requiring full connection re-establishment, thereby reducing latency while maintaining efficient communication

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the base station implements SDT configuration for inactive UEs, then data transmission efficiency improves, but the complexity of base station configuration procedures increases

Engineering Contradiction:

Improvedata communication efficiencyVSAvoidbase station configuration complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The configuration procedure is segmented into distinct phases: SDT parameter configuration during connected state, transition to inactive state with stored parameters, and SDT execution in inactive state. This segmentation allows the base station to manage complexity by handling only specific SDT-related configurations rather than complete connection management, simplifying the overall process while maintaining efficiency

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the base station manages both SDT and non-SDT configurations, then versatility is improved, but the difficulty of detecting and measuring configuration states increases

Engineering Contradiction:

Improveconfiguration flexibilityVSAvoidconfiguration state tracking

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The base station extracts and separately manages SDT-specific configuration parameters from the overall UE configuration. By isolating SDT parameters (such as sdta-Config, configuredGrantSDT, randomAccessSDT) into a distinct configuration set, the base station can track and manage SDT state independently from non-SDT configurations, reducing the difficulty of detecting and measuring configuration states while maintaining versatility

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20250351217A1Managing radio resource configurations for data communication in an inactive state

Publication Date: 2025.11.13 GOOGLE LLC

AI summary

A central unit, CU, of a distributed base station that also includes a distributed unit, DU, receives (606), from the DU, i) a small data transmission, SDT, configuration related to SDT operation and ii) a non-SDT configuration related to non-SDT operation; provides (610) the SDT configuration to a UE; and ignores (609), at the CU, the non-SDT configuration.