Non-Terrestrial Network Realities Call for New 5G Testing Approaches


5G is introducing tight integration with satellites to expand high-speed coverage into hard-to-reach areas and support maritime applications. This presents a whole new set of challenges for satellite transceiver performance.

Next-gen network deployments are ramping up around the world, but there is more to 5G than land-based New Radios and the new Packet Core.

5G is introducing tight integration with satellites to expand high-speed coverage into hard-to-reach areas and support maritime applications. These non-terrestrial networks (NTNs) will also provide backup coverage for emergency communications when local networks are unavailable.

Vertical expansion of the network

As described in 3GPP’s “Study on New Radio (NR) to support non-terrestrial networks,” NTNs include spaceborne platforms such as Low Earth Orbit (LEO) satellites, Medium Earth Orbit (MEO) satellites, and Geosynchronous Earth Orbit (GEO) satellites. They span airborne networks like aircraft and high-altitude base stations.

This is unchartered territory for mobile networks, representing an entirely new area of 5G testing and a unique set of challenges.

Networks for hard-to-reach areas are also harder to test

Compared to terrestrial 5G, NTNs increase the network’s horizontal complexity. Deserts, mountains, high-speed trains, ships, and more are all par for the course. Vertical complexity stems from connectivity that must be supported between land and space.

Obviously, NTN distances are considerably larger than traditional terrestrial networks. Airborne platforms may be positioned at altitudes of around 20km. Satellites can change the game entirely with positions at altitudes of 600km or higher. There are also multi-path routing considerations as satellites communicate with each other in a constellation, and with aircraft and airborne base stations. These dynamic mesh networks also have many links that grow factorially.

All these unique realities add up to new 5G technical issues that can cause communication failures:

  • Large Doppler shifts from fast-moving satellites

  • Bulk delays from distant satellite transmitters

  • Nearly parallel paths because of the long distance to satellites

  • Large propagation attenuation resulting in small signal-to-noise ratio

  • High radio link capacity needed to handle multi-path, mesh networks

  • Large number of fading parameters from signal propagation in space

  • Handovers between terrestrial and satellite links

So how should 5G testing evolve to accommodate so many new complexities?

Evolving NTN testing approaches for a 5G world

In our work with operators, Spirent is advising operators that testing non-terrestrial networks for 5G applications will require capabilities to:

  • Address the multipath effect, fading, and propagation

  • Use emulation for scale and high-capacity network testing

  • Test against actual “field” conditions, not simply generic radio channel models

  • Automate tests and run them 24/7

Instead of emulating unrealistic general channel models to test the entire NTN radio systems, test cases should be designed to saturate the critical parameters that are most likely to cause transmitter and receiver failures. Changing field conditions should determine which parameters must be varied and stressed in the channel models. Systematic testing of those most important parameters simplifies testing and is a traceable, cost-effective test method.

Spirent’s state-of-the-art channel emulation solutions can replicate the comprehensive impairment and spatial conditions of the most complex wireless channels, making it possible to conduct repeatable lab tests that have real-world relevance, lower costs, and improve test program outcomes while minimizing risk.

Download Spirent’s white paper Testing Satellite Communications for 5G Networks to learn more about how 5G testing approaches are evolving to accommodate the unique needs of NTN.

Visit Spirent Vertex® Channel Emulator to learn more about isolating and identifying RF performance issues.




JP Nuutinen image
Jukka-Pekka Nuutinen

Senior Solutions Architect

JP Nuutinen is an industry-renowned subject matter expert in radio channel emulation with over 20 years of experience in engineering and research. He is currently focused on cellular base station (gNodeB) and device test methodology for 5G technologies. Born in Valkeakoski, Finland, JP holds both Masters and Licentiate Technology degrees from Tampere University of Technology. He has more than 20 granted patents in addition to over 30 authored or co-authored publications.