5G-GOA 5G enabled ground segment technologies over the air demonstrator

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5G-GOA develops and implements the necessary modifications in the 5G New Radio standard to enable the direct radio access of terrestrial communication networks via satellite, a 5G RAN via satellite closely following the 3GPP Work Item on Non-Terrestrial-Networks. The hardware and software development relies on and uses existing technologies, hardware and software components already available from the open-source project OpenAirInterface for the prototyping of 5G terrestrial systems. Our solution is directly based on 3GPP discussions and results and covers physical layer techniques (e.g. synchronisation) up to specific protocols and upper layer implementations (e.g., timers and random-access procedure) of the radio access network, as needed. 5G-GOA focuses on geostationary satellite systems.
5G-GOA produces a hardware and software prototype, consisting of at least two user terminals and a gNodeB base station to verify bi-directional end-to-end communications. 5G-GOA plans to demonstrate the solution live, using the developed terminals and the modified 5G base-station connected via a direct satellite link, in addition to performing realistic tests in lab environment as well by using an advanced propagation channel emulator.
In summary, 5G-GOA develops and delivers a gNodeB (gNB) based gateway and the User Equipment (UE) compliant with the 5G New Radio standard release 17 or later for demonstrating the direct radio access connectivity in Non-Terrestrial Networks (NTN).
Importantly, our approach of using the OpenAirInterface software framework with custom off the shelf hardware equipment is motivated by that we believe that by extending an open-source solution with an existing user community will help maximising reuse of the results and achieving a broad impact.


The key challenge of 5G-GOA is the implementation of 5G NR gNB and UE components adapted to geostationary satellite systems while the standardization of these NTN features is still ongoing within 3GPP. More specifically, mitigating satellite RF impairments of the 5G signal represent specific challenges for the implementation, adjacent to the considerable round-trip-times that need to be compensated at the different layers (PHY, MAC and above) at the 5G NR UE and gNB.


5G-GOA helps to enable the direct radio access of terrestrial communication networks via satellite, a 5G RAN via satellite closely following the 3GPP Work Item on Non-Terrestrial-Networks (NTN) and thus supporting the evolution of the 5G New Radio standard regarding NTN.


The 5G-GOA solution is characterised by the following important features:

  • Firstly, an important concept of 5G-GOA is to evolve an existing open source platform, the OpenAirInterface, which has a very considerable supporting community. This approach is expected to support achieving a significant impact; 

  • The main feature of the 5G-GOA platform is that it enables end-to-end testing and performance verification of 5G direct access adapted to geostationary satellite systems both using an emulator environment, and also live, over the air demonstration;

Further important features include the mitigation of satellite RF impairments of the 5G signal as part of the implementation, in combination with the handling of considerable round-trip-times through the compensation at the different layers (PHY, MAC and above) at the 5G NR UE and gNB.

System Architecture

The figure below shows the architecture of the 5G-GOA end-to-end over the air demonstrator with the 5G core of the network on the right hosting the demo applications and being able to visualise key performance indicators, and two end user devices/terminals on the left hand running the user part of the demo application. As it is shown, 5G-GOA plans to verify performance using both an emulator and live, over the air, over a GEO satellite.




The project consists of two phases. The first phase focuses on the platform baseline and technical specification going to detailed design and includes two reviews, a Baseline Design Review and a Critical Design Review. The first phase is planned to last for 8 months.
The second phase focuses on the implementation, verification and demonstration. The second phase has also two reviews, a Demonstration Readiness Review and a Final Review, and is planned to last for 10 months.

Current status

The project completed its mission to provide a protocol stack implementation for use with transparent geostationary satellites for direct connectivity by releasing the suitably modified and extended OAI software implementation in July 2022, thus enabling early experimentation and proof of concepts for the community, shortly after 3GPP Release 17 was formalised and agreed.
It demonstrated 5G New Radio direct connectivity in Stand Alone mode over a geostationary satellite in Ku band at the 39th International Communications Satellite Systems Conference (ICSSC 2022), 18-21 October, Stresa, Italy, which we consider a major achievement. The demonstration used occasional use capacity from the SES Astra 2F satellite and relied on the suitably adapted OpenAirInterface™ software implementation for a 5G base station and a 5G nomadic node, mounted in a van equipped by a 45 cm satellite dish.

The project has published the modified and extended OpenAirInterface™ open-source code that supports 5G Non-Terrestrial Networking according to 3GPP Release 17 supporting direct connectivity over geostationary satellites. The 5G-NR NTN code is available for immediate use in the public OAI repository at: https://gitlab.eurecom.fr/oai/openairinterface5g/-/commits/goa-5g-ntn. The project also created a merge request, so the modifications and improvements will be merged and integrated into the main development branch “develop” of OAI shortly.