Building a 5g non-terrestrial network using openairinterface open-source software

Satellite-enabled 5G services have the potential to provide worldwide connectivity. In this paper, we give an introduction on the roadmap in 3GPP standardization of 5G as

well as on the enhancements to support non-terrestrial networks (NTN) in Release 17. We further provide first over-the-air test results of a successfully demonstrated extension of 5G New Radio (NR) to support non-terrestrial networks (NTN). As an proof of

concept, we tested some of the planned extensions for 5G NR for NTN via a geostationary satellite. The 5G base station as well as the 5G user equipment utilized in our experiments were fully software-defined solutions. Both components were based on OpenAirInterface (OAI), an open-source implementation of the 5G New Radio protocol stack, which runs on general purpose platforms.

5G UE demonstrator using OpenAirInterface

OpenAirInterface Team




As the race towards 5G begins, there is emergence of open source software especially in telecommunication world. This movement has already gained lot of momentum especially in areas such as cloud computing, Linux based operating system such as Android and also Internet of Things (IoT) middleware development. However, there are very limited open source projects that are building open source radio access network (RAN) targeting the user equipment (UE). At OpenAirInterface, we are building with our community an entirely open source implementation of UE that runs on general purpose platforms such as Intel/ARM aiming towards future 3GPP Releases.

Project Goals:

The long term goal of our project is to allow collaborative development and testing of advanced wireless technologies including 5G. To enable this we need to share a starting point, a foundation on which to build. The current UE “Project 1B” [1] aims at providing this starting point, leveraging the OpenAirInterface (OAI) software developed since years by EURECOM and its partners in order to provide a stable, standard compliant and field tested LTE-A UE implementation.

The first steps of the project are to improve the stability and performance of a Rel10 Cat4/TM4 UE and then develop and perform Inter-Operability Testing with the additional functionalities of Carrier Aggregation, TDD and full MIMO support.

Once this UE implementation is completed and tested it will be reused by other Open Air Interface Software Alliance (OSA) projects developing LTE-A Pro and 5G features (for ex. Massive MIMO, LTE-LAA, NB-IoT and so on).


OAI UE will run on general purpose platform such as Intel/ARM to leverage development from the community. However, as we go towards higher data rates/low latency, some of the industrial partners will also explore usage of SoC/FPGA (as e.g. Intel/Alterra) chip based compute platforms that can be seamlessly plugged into the generic PC architecture to offload compute intensive blocks such as Turbo decoder. We are open to porting/integration of OAI UE with FPGAs/SoCs from community members on 3rd party platforms. OAI UE will support general purpose RF platforms such as EXMIMO, BladeRF, USRP and LimeSDR running on Intel/ARM PC architecture.


Interoperability tests with commercial network/Testers:

One of the main goals of this project is interoperability with commercial equipment and networks. To that end, we plan to partner with our associate members for extensive testing in remote sites ([email protected], Comm4Innov/[email protected], TCL [email protected] and [email protected]). We plan to replicate our automated test framework across our partner sites all across the globe for community testing/development of the project. We also aim to allow non-regression testing of the OAI UE using Gitlab CI framework using R&S CMW 500 protocol tester. The extensive testing from the community against OAI eNodeB, CMW 500 and other protocol testers and against commercial test networks of Orange and Comm4Innov will significantly improve the stability and community at large could use it against commercial network. We also aim to partner with GENI/FIRE communities through our associate members in order to use OAI UE within their federated testbed deployments for community-driven testing/development of OAI UE.

OAI UE towards 5G:

This project will serve as a baseline for Rel13/14 development and several 3GPP proposals towards 5G. Some of the key proposals include:

  • LTE-License Assisted Access

  • New Waveforms as filtered OFDM

  • NB-IoT

  • Massive MIMO

The above proposals also include feature development on OAI eNodeB and some of these projects might run in parallel with dependencies on each other in terms of software development.


OAI UE will be showcased next year at MWC 2017. However, we plan to test OAI UE within the framework of other open source communities such as Telecom Infra Project, ONOS M-Cord, OpNFV. OAI UE testing against these open source communities is still under investigation/discussion from the OAI community. The OAI UE will also be promoted for use in collaborative research projects as European and other regional initiatives.


This project is sponsored by TCL Communications with extensive participation from several partners such as IIT-H, TU Dortmund and EURECOM. We expect several more individual community developers to join the project for testing/feature development in later stages of the project

Statements from our Alliance members:

“As a connected device manufacturer, TCL is very supportive of building joint projects to advance the technology. With leading Universities, labs and companies involved in Project1B we are confident to deliver a very useful tool to the wireless research and 5G community.”, said Pierre Bonnard, Director of innovation programs at TCL

“Orange is committed to moving beyond an opportunistic approach to open source software use and this project is a prime example of the benefits open source brings to telecommunications. As a mobile operator, Orange sees real value in the open source implementation of a 5G device to be developed by this project, especially for research. In particular, it will allow us to assess the added value of harnessing the tremendous compute and storage capabilities of future 5G devices: on the one hand to improve the Quality of Service of mobile networks, and on the other hand  to explore new businesses at the edge of 5G networks. Additionally, with respect to mobile security, a full blown 5G device implementation will help us to better anticipate and mitigate future cyber-attacks.”, said Christian Gallard, Head of Research Program on Key Technology Enablers for 5G at Orange.

“As a leader in network validation and optimization solution, Ercom has developed UE and network emulation tool able to reproduce the radio and traffic behaviour of tens of thousands of UEs. Developing open-source UE will accelerate the protocol stack development and increase our focus on test and measurement application and associated tool, with enhanced performance and customer experience. This will help our customers test and deploy the adequate quality of service, depending on end-user’s needs. The OAI UE, as a full software solution, is fitting very well with the market needs for labs virtualization”, said Yannick Dupuch, CEO at Ercom.

“As a 4G testbed, providing an operator grade network infrastructure, Com4Innov is offering to OpenAIrInterface a direct connection of their eNobeB to its EPC. The interoperability test of the UE with real frequency bands at 2.6 Ghz and 2.3 Ghz will demonstrate the capability to operate with leading Equipment Manufacturer system which is present in many operators’ network worldwide. The provisioning of credentials using SIM card will complete the test cycle towards the first step of pre-certification. Com4Innov is proud to host the validation support of OpenAirInterface UE allowing the integration of this technology in future commercial devices. ”, said Denis Rousset Director at Com4Innov.

“We are very happy at EURECOM that the OpenAirInterface software that was created here now has gained significant interest from the industry. We are delighted to be part of the first official OAI Alliance project with the aim to develop a UE prototype for 5G. This work complements our existing research themes and will be a basis to experiment with new algorithms and protocols, such as novel receiver architectures for (massive) MIMO.”, said Florian Kaltenberger, Assistant Professor at EURECOM.

We are very excited to be part of OAI UE alliance project. It will serve as a baseline for showcasing the following: (a) LTE eNB and UE demonstration in TV bands for rural communication and enabling low-cost solutions for digital India, (b) CRAN demonstrations using advanced COMP schemes for 5G” , said Kiran Kuchi, Associate Prof, IIT Hyderabad


[1] OAI Project 1B wiki,

5G-EmuSat develops a demonstrator platform implementing the physical layer and the necessary parts of the Media Access Control (MAC) layer allowing the detailed analysis of 5G New Radio (NR) for direct transmission and reception via a satellite channel using the open-source Software Defined Radio software OpenAirInterface (OAI) ([1]).

Concept and Methodology

5G-EmuSat develops a demonstrator platform implementing the physical layer and the necessary parts of the MAC layer of 5G New Radio (NR) for direct transmission and reception via a satellite channel using and extending the open-source SDR software OpenAirInterface (OAI).
Previously, the OAI community developed an open-source implementation of the LTE eNB and LTE User Equipment (UE), as well as the LTE Evolved Packet Core (EPC). Currently, parts of the 5G NR gNB and UE components are under development.

The following activities are planned on physical and MAC layers to achieve a working demonstrator platform for 5G NR connectivity over satellite:

  • Completing the implementation of all relevant 5G NR channels in OAI: PDSCH, PDCCH, PUSCH, PUCCH, PRACH, SS Block;
  • Completing the implementation of the necessary MAC functionalities in OAI: initial timing advance (TA) signaling, TA updates, data connection for a single static user;
  • Closely following the 3GPP standardization process especially regarding 5G NR Non-Terrestrial Networks (NTN) and extensions for direct to UE access;
  • Implementing the relevant 5G NR NTN direct to UE extensions in OAI, according to the finished 3GPP Study Items on impact areas and solutions for NR over satellites ([2], [3]);
  • Functional and performance validation tests of the OAI implementation using a Keysight channel emulator, emulating the satellite propagation channel with long delay;
  • Feeding back the code to the OAI repository that has been verified to be NR standard compliant.
Written by Jane