What does 6G stand for?

Dr. Ivan Ndip: 6G is the sixth generation of mobile communication. With 5G, we had data rates of up to 20 gigabits per second and latency of around 1 millisecond. We are a bit more ambitious with 6G: one terabit per second at a latency of around 100 microseconds - that is fifty times the speed and only a tenth of the latency of 5G. We can think of so many applications that could benefit from numbers like these: Industry 4.0, medical technology, driverless cars, smart cities, and the entertainment world. But then we're also facing major challenges that we need to overcome first.

If 5G is designed for real-time communication e.g. for autonomous vehicles, why does the world need 6G?

Dr. Ivan Ndip: Ask yourself why we want self-driving cars. One answer is because we want to get the number of accidents down. Driving, whether with a driver or without one, is always a collective experience. 5G brings us a maximum data rate of around 20 gigabits per second. For a car to drive autonomously, it needs to be able to tell its position to the other vehicles on the road; it needs to measure the distance to the objects and obstacles around it; it needs to see the world in every direction. It also has to know the road and its conditions exactly, and it needs to be able to see both far ahead and up close. It needs sensors for that, which we are developing here at Fraunhofer IZM: radars and cameras working in tandem. Sensors like this have to collect and share a mountain of data. At the same time, masses of data have to be uploaded or downloaded in real time, like high-resolution roadmaps. Twenty gigabits per second might sound a lot, but it is far from enough for all of these processes. Driverless cars also need to be able to react extremely quickly to any unexpected event, which means that we need very low latency on top of high transmission rates.

The specifications agreed upon for 5G are unfortunately not enough to create the infrastructure and networks we need to transfer hundreds of gigabits of data every second with extremely low latency. This tells us that 5G will probably not be enough for genuinely autonomous driving. And we don't even know yet whether the specifications for 5G will actually be met in real life. We haven't got the necessary collective or connected intelligence in place yet. Again, 5G does not really give us the data rates or latency we need for this. And this is why we need 6G.

You can think of other applications, like telemedicine. There is the concept of remote surgery, in which the operating surgeon does not have to be physically present. Work like this is being done already with 5G, but there are so many limitations in terms of 5G’s maximum data rate and latency. With 6G, the idea is that the surgery is performed by robots, while the actual surgeon is somewhere else and steers the robots via an ultra-high resolution monitor or a mixed-reality headset that shows what is happening inside the patient with realistic 3D holograms. The surgeon needs to be able to see even minute details brought to her or him in real time and in uncompressed form. We are again speaking of data rates of several hundred gigabits per second or even more than one terabit per second, with latency below one millisecond. This is simply impossible with 5G; 6G is coming to make good on the promises of 5G.

6G will also allow us to invent extremely miniature mobile medical sensors that can be integrated into the clothes we wear - or even implanted in the body - which can help monitor the vital signs of sick or healthy people. Such sensors could be connected in what we call a 6G Terahertz Body Area Network. The high-speed 6G connectivity means that this vital medical data can be transmitted to doctors in real time and with minimal delays to enable diagnostics and health monitoring from a distance.

We are also getting a vast range of other applications with 6G that combine the enormous advantages we have in terms of bandwidth in the terahertz range with new artificial intelligence technologies. Think of digital twins: virtual avatars of devices, machines, objects, processes, or even living beings. You can use, e.g. sensors, AI, communication, or location- tracking technology to create exact digital copies. With the extreme data speeds and the record low latency of 6G, you could model our physical reality in a virtual world without any limitations in terms of time or space in which you could use digital twins to monitor, analyze, or simulate reality. This will revolutionize many aspects of Industry 4.0, the automotive industry, medicine, education, or even entertainment.

We expect that 6G will allow new applications that will impact our lives, our society, and our economy in a way that humanity has never seen before.

But why are we speaking about 6G if we haven’t got 5G finalized in practice yet?

Dr. Ivan Ndip: 6G is scheduled for introduction in 2030, but there are still many unanswered questions. There is the question of hardware for mobile communication at rates above 100 GHz. We expect that we will be using the D-band, that is, frequencies from 0.11 THz to 0.17 THz, which has never been done for mobile communication. This is why the R&D community is starting early and is already thinking about the software and hardware questions, and even possible applications a whole decade before the technology will launch - which is not atypical.
The specifications will be finalized about five years before the launch, which is when trials can start. There is still a lot of work to be done by us researchers before the wider population will get to enjoy the benefits of our work. For instance, we have created the Innovation Campus Electronics and Microsensorics in the Brandenburg city of Cottbus, (iCampus Cottbus), where Fraunhofer has teamed up with the Brandenburg Technical University Cottbus-Senftenberg and two institutes of the Leibniz Association to research the connectivity and sensor technologies of tomorrow.

Will 6G also bring new business models?

Dr. Ivan Ndip: With the arrival of 5G, packaging and interconnection technologies have become paramount in the design of wireless systems for mobile communication. Creating a new high-frequency frontend module for mobile communication has long ceased to be a trivial job, so the ball is in the court of the makers and suppliers of materials, circuit boards, and components. There are many new business opportunities, not least for SMEs, which were mostly pushed to the sidelines when the game was still about 1G to 4G.
There are already many new business models, and it will be the same story with 6G. As I said, 6G will presumably use frequencies between 0.11 THz and 0.17 THz, and the higher the frequencies, the smaller the hardware. We will be able to build very tiny systems for 6G, and such miniature systems can be integrated into existing machines. We are talking about upgrading existing systems without changing their look and feel or really affecting the shape and dimensions of the devices. There will be countless new use cases in the vertical industry, meaning an explosion of new business models.

Are there any technological solutions for 6G that are already around?

Dr. Ivan Ndip: There are no complete solutions in the strict sense, but we are exploring new concepts to overcome the fundamental challenges. The first challenge is free space loss: We need to design multi-antenna architectures with arrays of hundreds of antennas per base station, known as MIMO - Multiple Input Multiple Output - architectures. We need to understand how many of these basic elements we put in and how we connect them to get long transmissions with very good beam formation and low power needs. And the eventual signal should not be affected by disruptions or interference. So the first step has to be to design new massive MIMO system architectures for efficient 6G hardware. The second step would be to actually produce such architectures, and this is where Fraunhofer IZM comes into the picture: We have the packaging capabilities we need for this type of system integration, for novel integrated terahertz MIMO antenna arrays, and novel high-frequency design methods for constructing 6G frontend modules.

We have already proposed some solutions: Our 6G project (6GKom) - the first German project funded by the Federal Ministry of Education and Research to design 6G terahertz modules - was launched back in October 2019. Fraunhofer IZM already holds patents for high-frequency system-integration solutions for such modules, based on miniaturized fan-out packaging platforms with integrated antennae that have not even been built yet.

Can you tell us more about the 6GKom project?

Dr. Ivan Ndip: The project is coordinated by Fraunhofer IZM and includes the Leibniz Association’s Innovations for High-Performance Microelectronics Institute, the Technical Universities in Berlin and Dresden, and the University of Ulm, a city in the German state of Baden-Württemberg. 6GKom also has an advisory body of partners from industry, fifteen companies operating in material, package, and chip development and production and test environments. On top of that, we have potential users from the automotive, aerospace, agriculture, and telecommunications industries.

For 6GKom, we want to be ahead of the curve and design a hardware basis for 6G, specifically an efficient, broadband, miniature MIMO D-band module with integrated beamforming capabilities. With a module like this, we can achieve data rates of several terabits per second for 6G mobile communication and highly precise location tracking. Another thing we are exploring is new base band architectures, taking into account parasitic effects in the terahertz D-band modules, as well as the test procedures and environments needed for that purpose.

To get us there, the consortium has already worked with our industry advisors to analyze possible use cases and define the relevant specifications. From there, we designed a scalable massive MIMO system architecture. Right now, we are working on a novel chip-package co-design and integration concept that will form the basis for the powerful, miniaturized broadband D-band module we are working towards. To turn these designs into actual hardware, we are employing our patented fan-out wafer-level packaging system integration platform with integrated antennas. Compared to existing package platforms, this gives us excellent high frequency performance and makes the system smaller, more reliable, and more economical.

We will also be researching and developing new signal processing algorithms to test the D-band module's fitness for the form of mobile communication we envision.

In a nutshell, how do 5G and 6G differ in terms of technology?

Dr. Ivan Ndip: There are so many differences between 5G and 6G that I need to make a selection.

Let's start with the frequencies: Up to 4G, all mobile communication happened below 6 GhZ. With 5G, we are moving to 26 GHz, 28 GHz, and 39 GHz, taking us above the 6 GHz range for the first time. For 6G, as I’ve said, we’re taking the leap to the terahertz level, presumably in the D-band (0.11 THz to 0.17 THz). 6G could also use Visible Light Communication (VLC), which is a very promising optical technology for near-field communication, using visible light between 400 and 800 THz.

However, both 5G and 6G will also continue to use frequencies below 6 GHz.

Then we have the data rates: For 5G, we expect peak data rates of approximately 20 gigabits per second, while 6G will give us peak rates of more than one terabit per second. There will also be a significant leap when it comes to the data rate per use: 5G will probably bring 100 megabits per second, but 6G should reach around one gigabit per second.

Third, there's the issue of latency: Current expectations for 5G would put latency at approximately one millisecond or more. 6G would achieve far below one millisecond, presumably 100 microseconds. Such extremely low latency is very important for applications like holographic communication, virtual, augmented, and mixed reality, as well as remote diagnostics or surgery. For medical applications like these in particular, the network has to guarantee top reliability, low latency, and extremely high data rates. Compared to 5G, 6G is being designed to fulfill all of these requirements at the same time.

There is also a major difference in terms of the connected devices per square kilometer and in terms of energy efficiency, but it is still to early to put a number on either of these factors.