• 5G
• NTN
• March 11, 2025

Navigating the Complexities of Non-Terrestrial Networks (NTN)

The rapid evolution of Non-Terrestrial Networks (NTN) is transforming global connectivity, enabling communication across remote and underserved regions. Unlike terrestrial networks, which rely on ground-based infrastructure, NTN integrates satellite communication (SatCom) and mobile network operator (MNO) infrastructure to provide seamless coverage. However, NTN testing and validation present unique challenges due to the complex interactions between satellites, devices, and terrestrial networks.

This blog has important excerpts from the webinar hosted by RCRWireless where we explored the intricacies of NTN, highlighting the key challenges in NTN testing, the need for advanced validation solutions, and how Simnovus is helping the industry navigate these hurdles. We’ll cover:

• The complexities of SatCom infrastructure
• Key challenges in NTN validation
• Satellite simulation techniques
• The importance of NTN Control Function (NCF) validation
• Addressing radio limitations in NTN testing
• Real-world NTN applications
• Scalable solutions for L2/L3 NTN validation

Understanding SatCom Infrastructure

SatCom infrastructure comprises satellites, ground stations, and network management functions. However, satellites vary in type, characteristics, and use cases, adding complexity. With more components in the network, interoperability becomes crucial. Different satellites and devices must seamlessly work together to ensure a reliable and efficient network.

Historically, cellular and satellite communications operated as separate ecosystems. Now, as these technologies merge, cross-domain understanding is required. Engineers validating base stations must also consider how a satellite’s movement affects devices and infrastructure. Successfully integrating terrestrial and non-terrestrial networks demands collaboration, knowledge-sharing, and advanced NTN testing tools.

Challenges in NTN Testing and Validation

Before testing and validation begin, a key question arises: How can we replicate this infrastructure in a lab environment?

For device manufacturers, simulating network components interacting with their devices is a challenge. For Network Equipment Manufacturers (NEMs), complexity increases further as they must simulate not only a massive number of User Equipment (UEs) but also the SatCom infrastructure. Simulating different satellite types and related infrastructure is critical.

Additionally, radio availability is a key challenge. Few radios support the 3GPP-defined bands for NTN, making real-world NTN testing difficult. Even when these challenges are addressed, expertise in making everything function correctly remains a major hurdle. Teams often struggle to pinpoint root causes when issues arise, and test reproducibility can be difficult. Speed is essential, and manual validation is not suitable.

How Simnovus Helps Overcome NTN Testing Challenges

The Simnovus UE Simulator supports 3GPP Rel 17, including NTN bands n255 and n256, enabling validation of System Information Blocks (SIBs) containing values like TA Common, K Offset, and Ephemeris data.

Simulating Satellites

To test NTN, one approach is using External Satellite Link Emulators. In NTN, the satellite’s position relative to the device is critical. The Simnovus UE Simulator allows configuration of UE coordinates. Based on System Information Block data, the UE automatically pre-compensates for Timing Advance. While effective for a single testbed, this method does not scale well. Traditional channel emulators are expensive, require lab space, and lack UE awareness, making them impractical for large-scale NTN testing.

With Simnovus’ embedded Channel Emulation, external tools and additional learning curves are eliminated.

Defining Satellite Orbits

A key question in NTN testing is: How do you define the satellite’s path for GEO, MEO, or LEO satellites?

With Simnovus, there are multiple approaches:

1. The UE can determine the satellite’s orbit using data from SIB19.
2. Manually define ephemeris using key parameters like inclination and semimajor axis.
3. Use a TLE (Two-Line Element) file, a widely accepted format for orbital elements.
4. Incorporate atmospheric attenuation and ground station position for more realism.

Using this data, the UE Simulator accurately estimates satellite position, incorporating delay and Doppler effects. The UE automatically pre-compensates for Timing Advance, ensuring realistic NTN validation.

Simulating NTN Control Function (NCF)

The NTN Control Function (NCF) is a critical component in the operator’s network providing satellite data to the base station. Validating the base station’s ability to communicate with the NCF is essential. The Simnovus NCF Simulator provides a complete and realistic test environment, transmitting ephemeris data, network management updates, and satellite region transitions to ensure seamless integration.

Overcoming Radio Limitations in NTN Testing

What if your radio does not support NTN bands? Or operates on non-3GPP bands?

Many companies developed solutions using pre-3GPP bands before NTN became standardized. If you need to validate these legacy bands while transitioning to 3GPP NTN bands, Simnovus enables this. Users can configure key parameters such as:  Uplink (UL) and Downlink (DL) frequencies

• Frequency raster
• SSB subcarrier frequency

This ensures thorough implementation verification and a smooth transition to NTN bands.

NTN Use Cases and Real-World Applications

NTN is expected to bridge the digital divide, providing ubiquitous connectivity across diverse environments. Devices using NTN services include:

• Fixed Wireless Access (FWA) CPEs in remote homes
• IoT sensors in isolated locations
• Smartwatches and smartphones requiring seamless connectivity

The Simnovus UE Simulator supports various data types and traffic patterns, making it ideal for NTN validation, whether simulating narrowband UEs sending small data packets or FWA UEs handling higher data rates.

ORU-Simulator for Layer 2 and Layer 3 NTN Testing

For teams focusing on Layer 2 (L2) and Layer 3 (L3) validation, Simnovus offers the ORU-Simulator, which allows validation without physical radios. The ORU-Simulator:

• Simulates ORUs and UEs within a single product.
• Provides advanced UE Simulator features.
• Enables independent L2/L3 validation.

With the Simnovus ORU-Simulator, users gain a scalable, software-driven solution for end-to-end NTN testing.

Conclusion

NTN is revolutionizing global connectivity, but its deployment requires overcoming testing and validation challenges, including satellite simulation, interoperability, and radio compatibility. Simnovus delivers a robust, software-driven solution, ensuring efficient and scalable NTN testing and validation. Whether testing NTN bands, simulating satellites, or conducting L2/L3 testing, Simnovus simplifies NTN validation.

Stay ahead in NTN testing with Simnovus – your trusted partner in Non-Terrestrial Networks validation.