OpenAirInterface: an open platform to establish tomorrow's 5G

The OpenAirInterface platform offers a 4G system based on a software package. These can be tested and modified independently of each other by user companies. The aim is to establish new functions for the future 5G network. To find out more, we spoke to Christian Bonnet, communications systems researcher at EURECOM.

What is OpenAirInterface?

Christian Bonnet: Behind this name lie two things. The first is the implementation of software for 4G-5G systems. This concerns the software running in a mobile terminal, the software that increments radio transmissions, but also the software in the network core.

The second thing behind OpenAirInterface is an "endowment fund" that was set up by EURECOM at the end of 2014, with the aim of driving an open, global software alliance: the OpenAirInterface Software Alliance (OSA).

How does this software suite work?

CB: This is a software implementation of the components of a complete 4G system. This concerns the modem part of a mobile terminal, the software of radio relay stations and the software of specific routers at the heart of a network. This includes all radio-layer processing (modulation, coding, etc.) for communications protocols. It runs on Intel x86 processors found in PCs and computer farms. Which means it's compatible with cloud developments. To set it up, you need a radio card, connected to the PC that acts as the terminal, and another to the PC that acts as the relay station.

Then, depending on what you want to do, you can take on only part of the software implementation. For example, we can use off-the-shelf mobile terminals and hook up to a network consisting of an OpenAirInterface relay and a commercial network core. Any combination is possible. In this way, we have set up a complete chain for a 4G network that can be upgraded to 5G using all this software.

Who are the contributors to OpenAirInteface?

CB : Since the Alliance was set up, we've had several types of contributor, the main one so far being EURECOM, whose teams developed the first versions of the software package. Researchers, post-docs and PhD students can also contribute to the platform, which provides an experimental environment for their research. What's more, through the Software Alliance we have new types of contributors, not only from industry but also from research laboratories all over the world. We've broadened our base, and this openness means we now have contributions from both the academic and industrial worlds.

What does the Carnot label mean for your activities?

CB : The Carnot label was important in our relationship with the Beijing University of Posts and Telecommunications in China (BUPT), a university specializing in telecommunications. BUPT asked us to refer to a quality label to show that our expertise was recognized. The Carnot label was put forward and recognized by the foreign university. This label not only demonstrates the commitment of OpenAirInterface's developments to the industrial world, but is also a seal of quality recognized far beyond the boundaries of France and Europe.

Why do companies and manufacturers turn to OpenAirInterface?

CB: To develop innovative projects, industrialists need to be informed by advances in scientific research. They come to us because they are aware of our academic excellence, and because they know that we speak the same language as they do. It's in our DNA! Since its creation, EURECOM has been at the crossroads of industry and research, and we know how to speak both languages. We've developed our own platforms, and we've been confronted with problems that industrialists encounter on a daily basis. This makes us a natural interlocutor between these two worlds. We listen carefully to their innovation projects.

Why have you decided to develop your software suite in open source?

CB: It's a well-known model that's beginning to spread. It facilitates access to knowledge and contributions. This software is governed by free software licenses that protect contributors and enable wider dissemination. This has a knock-on effect, speeding up development and accelerating testing, because every piece of software needs to be tested. If you spread the implementation of this software around the world, then everyone will be able to use it more easily. The result is a greater number of software tests, and thus more user feedback to improve existing versions. The whole community benefits. This is a very important point, because even in industry, many components are beginning to be developed using this model.

Beyond this approach, what makes OpenAirInterface unique?

CB : OpenAirInterface has brought an innovation to free software licensing. There are many different types of open source license. It's a very vast world, and the industrial world is linked to large patent portfolios. The context is as follows: on the one hand, there are industrial structures among our partners that rely on patent revenues, and on the other, there is a community that wants free access to software for development purposes. How do we resolve this apparent contradiction?

We have set up a specific license to protect both the software for non-commercial operations - i.e. all research, innovation and testing - as for classic open source software, and when it comes to commercial operations, we set up a patent declaration system. This means that if industrialists implement patented parts themselves, they need only mention them, so that for commercial operations people turn to the rights holders for negotiation. These conditions are known as Frand (fair, reasonnable and non-discriminatory), and are similar to those applied by industry in standardization bodies such as 3GPP. In any case, this approach has been very well accepted. That's why the Alliance's strategic partners include Orange and Nokia (formerly Alcatel-Lucent Bell Labs), who have been convinced by the benefits of this type of software license.

What's the next step in OpenAirInterface's development?

CB : There are several avenues of development. Projects submitted to the European H2020 program, the results of which are awaited, will enable us to make scientific advances and generate spin-offs in software applications. The Alliance has also defined a number of major development areas, divided into projects run jointly by an industrial partner and an academic partner. This structure makes it possible to bring together people from the other side of the world. They volunteer to contribute to one of the steps towards 5G.