NTN-CPD

Space for 5G

Status

Ongoing
Status date

2024-10-22
Activity Code

3A.181

Objectives

The objective of the NTN-CPD project is to define the control plane of the 5G New Radio standard for NTN networks and demonstrate its performance in a a software demonstrator.

To be more specific, the project aims to fulfil the following objectives:

Define a reference NTN architecture based on Non-Geo Stationary Orbits (NGSO).
Review of the 5G NR control plane procedures and signaling.
Identify possible strategies for satellite networks to implement a control plane as close as possible to the current 3GPP 5G specifications.
Identify required modifications to the current 3GPP specifications for having an efficient control plane fit to be deployed on Non-Terrestrial Networks.
Demonstrate such architectures and control plane design in a software demonstrator (e.g., network simulator).

Challenges

The key challenges in the project are to:

Implement a simulation tool, where the NR control plane is simulated with sufficient level of detail across a variety of different simulation scenarios.
Implement the simulation tool with a high-level of performance, such that it can be used to effectively simulate and demonstrate complex NGSO scenarios.
Create a reference NGSO satellite system architecture that can be used to evaluate the NR control plane in NGSO environments and identify possible improvements to the 3GPP specifications.

Benefits

The developed Nova simulator is designed to enable the evaluation of 5G control plane procedures with flexible NGSO constellations, allowing the discovery of possible issues and optimization targets for standardization and industrial purposes. The simulator will be capable of modeling relevant control plane features that may impact the 5G NTN performance in high-speed satellite scenarios, including but not limited to cell access, UE measurements and mobility management. Key benefits of the project include highly dynamic satellite constellation deployments and assessment of such systems and relevant protocols in high detail from both end-user and network perspectives. The research is complemented by visualization and demonstration of the simulations via Magister Simlab.

Features

The NTN-CPDNova simulator introduces features in three different software versions.

The implementation Version 1 of the control plane demonstrator will introduces a selection of NR-NTN Release 17 features and functionality:

RRC signaling
RRC messages
Random Access
Time and frequency synchronization
Mobility
Feeder link
SSB, synchronization signals, and system information
UE measurements
Radio link failure
RRC idle/inactive

Version 2 of the software focuses on 3GPP Release 18 and Release 19 control plane features, especially on VSAT UE operability and regenerative satellite payload:

VSAT
RACH-less handover
Conditional HO enhancements
Satellite switch with re-sync
Regenerative satellite payload
gNB CU-DU split
Inter-satellite links

Version 3 does not contain the implementation of major new features but focuses more on improvements and bug fixes of the code base and parameter optimization of the simulations.

System Architecture

The developed Nova simulation tool targets to enable the evaluation of the control plane of different NGSO satellite constellations, supporting 3GPP specified NTN system architectures, with support for both transparent and regenerative satellite systems. Satellite constellations within one type of orbit are the focus of the simulator, with multi-orbit constellations being supported with no cross-orbit communication. The architecture supports simple Inter-satellite Links (ISLs) and functional splitting of the gNB in regenerative satellite systems. The system architecture reflects the project objectives, with greater focus placed on the control plane rather than the user plane. The architecture focuses on the radio access network, while the core network and backhaul connections are largely simplified. The simulator is designed to accurately simulate subsets of the whole constellation, where the subset of satellites can be dynamically selected, based on the area of interest.

Plan

The project started in May 2024 and with 21 months duration is scheduled to end in January 2026. The work has been divided into the following work packages:

WP1.0: System Scenarios
WP2.0: Technical Specification
WP3.0: Technical Baseline
WP4.0: Demonstrator Design
WP5.0: Demonstrator Implementation
WP6.0: Technology Assessment and Development Plan
WP7.0: Project Management

Current status

The project started officially on 18.4.2024 and an official KO meeting was held on 23.4.2024. System Requirements Review milestone achieved on 11.9.2024.