ALIX: 5G Network Simulator

Protocol-Level 5G TN/NTN Simulator for Advanced Technology Evaluation

ALIX is a 5G TN/NTN system-level simulator that is used for detailed protocol level simulations for 5G Terrestrial and Non-Terrestrial Networks.

Operating on a packet level resolution, ALIX makes it possible to evaluate communication technology performance – including 5G TN/NTN, 5G-Advanced, and 6G NTN protocols – to support standardization, benchmarking, and future network design.

Packet‑level simulations aligned with 3GPP TR 38.811 & TR 38.821

Evaluate DVB-S2X, DVB‑RCS, 5G NR‑NTN

Test emerging technologies before physical prototypes

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Keep Up with 3GPP Standardization

Ensure your solutions remain aligned with the latest 3GPP developments, including 5G NR-NTN, TN/NTN, and emerging 6G. Validate system behavior against evolving specifications and upcoming features.

Evaluate Communication Technologies with Precision

Compare communication technologies – such as DVB standards and 5G NR – using transparent, objective, and reproducible protocol-level evaluations.

Explore, Prototype & Develop Future Technologies

Use ALIX to optimize, refine, and design next-generation network systems. Test ideas early, validate performance, and accelerate R&D without costly hardware iterations.

Key Use Cases for Protocol-Level 5G/6G TN/NTN Simulation

Ensure Alignment with 3GPP 5G TN/NTN Standards

ALIX helps organizations align with evolving 3GPP standards for NTN and future network generations.
- Validate system behavior based on TR 38.811 (NTN channel modeling) and TR 38.821 (NTN scenarios/parameterization)
- Ensure compatibility with 5G NR, 5G‑Advanced, and 6G NTN developments
- Evaluate new protocol features early, before hardware or field testing
Compare Technology Performance with Precision

ALIX provides system-level evaluation for comparing radio technologies, waveforms, and protocol behaviors. Analyze:
- DVB-S2X, DVB-RCS2
- Comparing 5G NR and DVB standards
- 5G TN/NTN scenarios
- HARQ details, link-to-system mapping, and scheduling performance
- PDCP Multi-Connectivity
Analyze Constellation Subsets in Detail

ALIX allows users to zoom in on specific segments of a constellation for focused evaluation.
- Evaluate performance for parts of a constellation
- Study protocol effects under region-specific conditions
- Compare coverage variations
Cut Development Costs with Virtual Prototyping

By testing technology behavior virtually, ALIX minimizes unnecessary hardware or device investments.
- Verify system functionality before prototype development
- Identify issues early through protocol-level fidelity
- Reduce risk in R&D
- Validate new features before building custom equipment
Evaluate End-to-End Performance

Simulate the complete communications chain:
- Protocol stack: from MAC layer scheduling to application services
- Link budget calculations with real-time SINR, throughput, and error rates
- Quality of Service (QoS) mechanisms and priority routing

Verified through ESA, EU Horizon & Industry Collaborations

ALIX has been developed and validated through international projects with the European Space Agency (ESA) and the European Union, demonstrating its reliability, scientific rigor, and relevance for next‑generation 5G/6G NTN development.

ALIX has been advanced & utilized in key ESA and EU Horizon projects, including:

ALIX – Core development of the 5G TN/NTN simulator & contributing to 3GPP standardization
SAIRCC – Including the satellite industry in future railway mobile communication systems
HELENA – NTN innovation & improving the mobility of 5G NTN
DYNASAT – Dynamic spectrum sharing and NTN system optimization
MARINA – Developing a fair method for comparing DVB-S2X and 5G NR technologies
EAGER – Exploring future 5G-Advanced and 6G NTN technologies

Research Papers Featuring ALIX

3GPP 5G NR NTN Technologies in a Geostationary Satellite Scenario / Best Paper Award ASMS/SPSC 2025

3GPP 5G NR NTN Technologies in a Geostationary Satellite Scenario / Lauri Sormunen, Tuomas Huikko, Verneri Rönty, Erno Seppänen, Sami Rantanen, Frans Laakso, Vesa Hytönen, Mikko Majamaa, Jani Puttonen

Best Paper Award / Industrial Relevance, the 12th Advanced Satellite Multimedia Systems Conference and the 18th Signal Processing for Space Communications Workshop 2025

This article presents a thorough performance comparison between DVB Second Generation Satellite Extensions (DVBS2X) and Return Channel via Satellite 2nd Generation (DVBRCS2), and NR NTN in a Geostationary Orbit (GEO) satellite scenario, using system-level simulators (SLS) for evaluation, namely Satellite Network Simulator 3 (SNS3) and ALIX 5G (TN-)NTN SLS, built on the same Network Simulator 3 (ns-3) platform.

Co-existence of Terrestrial and Non-Terrestrial Networks on Adjacent Frequency Bands

Co-existence of Terrestrial and Non-Terrestrial Networks on Adjacent Frequency Bands/ Lauri Sormunen, Henrik Martikainen, Jani Puttonen, Dorin Panaitopol, The 11th Advanced Satellite Multimedia Conference and the 17th Signal Processing for Space Communications Workshop (ASMS/SPSC), 6–8 September 2022.

This paper presents the latest achievements concerning 3GPP Release-17 adjacent band coexistence simulation work on 5G new radio non-terrestrial networks (NTNs) for satellite communications.

The main conclusions can be summarized as follows: (1) NTN UE can reuse the current requirements of the TN UE, (2) the satellite connectivity does not require a dedicated satellite waveform, and (3) TN can co-exist with NTN on adjacent channels with relaxed ACIR requirements for the tested simulation scenario.

Multi-Connectivity in 5G and Beyond Non-Terrestrial Networks

Multi-Connectivity in 5G and Beyond Non-Terrestrial Networks / Mikko Majamaa, Henrik Martikainen, Lauri Sormunen, and Jani Puttonen, Journal of Communications Software and Systems, 2022.

In this paper, an adaptive MC activation scheme for throughput enhancement in 5G and beyond Non-Terrestrial Networks (NTNs) is presented. The algorithm is evaluated by system simulations using different traffic split algorithms, namely, even split, data request per connection and per gNB algorithms. In the considered simulation scenario, the maximum throughput enhancement of 9.1%, compared to when MC is turned off, is experienced when using the adaptive Secondary Node (SN) addition algorithm with the combination of the data request algorithms.

A System Simulator for 5G Non-Terrestrial Network Evaluations

A System Simulator for 5G Non-Terrestrial Network Evaluations / Jani Puttonen, Lauri Sormunen, Henrik Martikainen, Sami Rantanen, Janne Kurjenniemi, IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), Non-Terrestrial Networks in 6G Wireless workshop, June 7-11, 2021.

This article presents a 5G NTN extension to an open-source Network Simulator 3 (ns-3) and its 5G extension (5G LENA). The objective is to use the resulting System Level Simulator (SLS) in 3GPP standardization to evaluate different system concepts and parameterizations.

5G TN/NTN Simulator Based on 3GPP Specifications

FEATURES

3GPP Specification-Based Modeling

ALIX follows 3GPP specifications to ensure accurate, standards‑aligned results. For example:

TR 38.811 in terms of NTN channel modeling
TR 38.821 in terms of NTN scenarios and parameterization

NTN, TN & Hybrid TN/NTN Support

Models a wide range of scenarios across non-terrestrial, terrestrial, and hybrid networks.

Focus on Non-Terrestrial Networks
Also supports TN channel models and TN/NTN scenarios

Higher Layers

Simulates application-level traffic realistically.

Core network simplified
UDP, TCP, traffic generators (applications)

Focus on RAN Features

ALIX simulates the whole protocol stack from MAC layer scheduling to application services.

PHY: Link-to-system mapping, support for NTN-relevant channel models, adaptive Modulation and Coding Schemes (MCS), SNR/SINR, power control
MAC: 5G NR-NTN scheduling, HARQ operation, resource allocation
RLC: UM/AM (Unacknowledged Mode / Acknowledged Mode), radio link data transmission reliability

User-Plane Focus for Real Application Behavior

Real application behavior and user traffic patterns
End-to-end user experience indicators (latency, jitter, throughput)

System-Level Calibration Scenarios Defined by TR 38.821

LEO-600, LEO-1200, GEO
Handheld terminals, VSAT terminals
Frequency reuse factors: 1, 3, 2+2
Frequency bands: S-band, Ka-band
Custom altitude, frequency, and terminal configuration.

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Book an online meeting about ALIX with our simulation experts. We’ll walk you through the simulator’s capabilities and discuss your potential usage scenarios.