Review on 5G Non-Terrestrial Networks Using OpenAir Interface: An Experimental Investigation Using GEO Satellites

The Third Generation Partnership Project (3GPP) aims to integrate terrestrial 5G networks with non-terrestrial networks (NTNs). Prototyping and testing play an essential role in demonstrating that new 5G-NTN releases are ready. However, universities and nonprofit research organizations struggle to modify and customize commercial 5G protocol stack implementations for 5G-NTN testing and development, as these solutions are often costly and proprietary. A promising alternative is software-defined radio testbeds that use open-source software. This article describes our protocol stack modification of an open-source 5G-NTN implementation based on OpenAir Interface (OAI), which runs on standard hardware. We use a transparent geostationary satellite to evaluate our 5G-NTN’s performance across different layers in real-world conditions. To validate our testbed, we use various online applications, including voice over IP, web browsing, and video streaming. The results indicate that the current implementation, which operates with a 5MHz bandwidth, is reliable over several hours and maintains a typical geostationary latency of around 530ms while achieving download and upload speeds of 3.6Mb/s. The tests confirm that our 5G-NTN testbed is a reliable alternative to costly commercial solutions.