PDC Measurement Control in Split Network Nodes for TSN Synchronization

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Solution Overview

Problem

Existing network communication systems face challenges in accurately compensating for propagation delays in 5G wireless communication systems, particularly in large cells, leading to synchronization errors that exceed the allowed uncertainty budget for Time-Sensitive Networks (TSN), and there is no effective way for the central unit (gNB-CU) to manage or terminate ongoing Propagation Delay Compensation (PDC) measurements when services are released or radio conditions deteriorate.

Innovation Solution

The central unit (gNB-CU) is equipped with the ability to transmit messages to the distributed unit (gNB-DU) to pause or terminate ongoing PDC measurements and receive failure indications, allowing for resource liberation and adaptive management of PDC processes through F1 application protocol procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If legacy TA-based mechanism is used for propagation delay compensation, then synchronization error can be reduced, but implementation inaccuracies introduce up to 540 ns of uncertainty in determining downlink propagation delay

Engineering Contradiction:

Improvepropagation delay measurement precisionVSAvoidsynchronization reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a new PDC measurement mechanism that acts as an intermediary between the legacy TA-based mechanism and the synchronization requirement. The gNB-DU performs dedicated PDC measurements using reference signals, providing a more reliable propagation delay estimate that compensates for the uncertainties in the legacy TA approach.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the measurement parameters by introducing dedicated PDC reference signals and measurement procedures at the gNB-DU, moving away from reusing uplink timing advance parameters. This allows for more accurate and reliable propagation delay compensation tailored specifically for downlink synchronization.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If PDC measurements are continuously performed to maintain synchronization accuracy, then synchronization error is reduced, but network resources are consumed and cannot be released when services are terminated

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidnetwork resource consumption

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent makes the PDC measurement process dynamic by enabling the gNB-CU to configure, activate, and terminate PDC measurements at the gNB-DU based on service requirements. When a service is released, the gNB-CU can send a termination indication to stop PDC measurements, allowing resources to be freed while maintaining accuracy when services are active.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The gNB-CU pre-configures PDC measurement parameters and maintains awareness of active services, allowing it to proactively terminate PDC measurements when services are released. This preliminary configuration enables rapid resource release without affecting ongoing synchronization for active services.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If gNB-CU wants to terminate ongoing PDC measurements when service is released, then resource liberation is enabled, but no mechanism exists to communicate termination requests to gNB-DU

Engineering Contradiction:

Improveresource liberation efficiencyVSAvoidcontrol signaling complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extends the existing F1 application protocol interface between gNB-CU and gNB-DU to include PDC measurement control functionality. The same F1 interface used for general control is enhanced with specific information elements for configuring and terminating PDC measurements, avoiding the need for a separate dedicated control interface.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If gNB-DU needs to report PDC measurement failures to gNB-CU, then measurement reliability is improved, but no failure indication mechanism exists in the current protocol

Engineering Contradiction:

Improvemeasurement reporting reliabilityVSAvoidmeasurement status information

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent implements a feedback mechanism where the gNB-DU reports PDC measurement results and failure indications back to the gNB-CU through the F1 interface. This feedback loop allows the gNB-CU to monitor measurement health and take appropriate actions, improving overall system reliability and preventing loss of synchronization information.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250261147A1Aborting and indicating failure of propagation delay compensation measurement in split network node architecture

Publication Date: 2025.08.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method, system and apparatus are disclosed. According to some embodiments, a central unit, CU, associated with a network node that is configured to communicate with a wireless device is provided. The CU is configured to transmit a first message to a distributed unit, DU, associated with the network node where the first message requests for the DU to at least one of pause and terminate at least one on-going Propagation Delay Compensation, PDC, measurement, and receive a second message from the DU, the second message indicating failure of at least one PDC measurement during a periodic reporting period for PDC measurements.