With 6G, the starting signal has been given for the next generation of mobile communication: One terabit of data, i.e. 1,000 gigabits, is to be transmitted within one second. Dr.-Ing. habil. Ivan Ndip, an expert in antennas and high-frequency systems at the Fraunhofer Institute for Reliability and Microintegration IZM in Berlin, explains in an interview why 6G is being developed and why it is already being used now, even though 5G is not yet widely available.

What does 6G mean?
Dr. Ndip: 6G is the sixth generation of mobile communication. With 5G, we are talking about a data rate of up to 20 Gbit/s and a latency of around 1 ms. With 6G, we have the ambitious goal of achieving one Tbit/s and a latency of around 100 µs - fifty times the data rate and a tenth of the latency of 5G. There are many applications in the areas of Industry 4.0, medicine, autonomous driving, smart city and entertainment that would benefit from this - but there are also major challenges that need to be solved first.

Dr.-Ing. habil. Ivan Ndip has been at the Fraunhofer Institute for Reliability and Microintegration IZM for almost 20 years and has headed the RF & Smart Sensor Systems department since 2014.

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5G should already enable real-time communication, for example for autonomous vehicles. What will we need 6G for?

Dr. Ndip: What is the goal of autonomous driving? The aim is to greatly reduce the number of accidents. Autonomous driving is primarily a collective aspect. What 5G will achieve is a maximum data rate of around 20 Gbit/s. When a car drives autonomously, it has to communicate its position to other road users in real time, it has to be able to measure distances and look around 360° at the same time. It must also know the road very well and be able to look into the distance, but of course also very close and very precisely. This requires sensors, which we are also developing at Fraunhofer IZM: a combination of radar and camera. These sensors collect an enormous amount of data that needs to be shared simultaneously. However, uploads and downloads must also take place in real time: City maps, for example, are downloaded in very high resolution. 20 Gbit/s is nowhere near enough for all these processes. In addition, the cars must react reliably to unforeseen circumstances autonomously with an extremely short delay. Therefore, in addition to the very high data rates, a very low latency is also required.

Unfortunately, the specifications of 5G do not make it possible to build infrastructures and networks that simultaneously guarantee hundreds of Gbit/s and extremely low latency. We therefore believe that true autonomous driving will probably not be possible with 5G. And we don't even know if the specifications we have for 5G today will even be met. The necessary collective or networked intelligence does not yet exist. Nor does 5G provide us with the data rates and latency required for this. That's why we need 6G.

We can find other applications in telemedicine, for example in the field of tele-surgery: the doctor performing the operation would no longer need to be on site. This is already possible with 5G, but there are many limitations due to the maximum data rate and latency associated with 5G. Robots perform the operations while the doctor is somewhere else and controls certain devices. To do this, they use an ultra-high-resolution screen or a mixed reality headset to see exactly what is happening inside the body with the help of 3D holograms. He must be able to recognize the finest details. To do this, it needs data in real time and uncompressed with a transmission rate of several hundred Gbit/s to over 1 Tbit/s and a latency of less than 1 ms. There's no way 5G can do that! 6G is coming to fulfill the expectations raised by 5G.

6G will also enable the development of highly miniaturized wearable medical sensors, clothing-integrated sensors and implantable sensors that can continuously monitor the vital signs of healthy and sick people. These sensors could be networked with each other via a so-called 6G Terahertz Body Area Network. With the help of high-speed 6G networks, vital parameters can be transmitted to doctors with extremely little delay for remote medical monitoring in real time.

Furthermore, 6G opens up a wide range of applications that combine the enormous bandwidth advantage of the terahertz band and new methods of artificial intelligence. For example, in the area of digital twins. These are the virtual counterparts of devices, machines, objects, processes or even living beings. With the help of sensors, artificial intelligence, communication and localization technologies, among other things, they are created as digital duplicates. Due to the extremely high data rates and very low latency that 6G will offer, it would be possible to monitor, simulate and analyze reality in a virtual world without temporal or spatial restrictions using digital twins. This will have a significant impact in many areas of Industry 4.0, the automotive industry, medicine, education and entertainment.

It can therefore be assumed that 6G will enable applications that will completely change our lives, our society and the economy in a way that humanity has never seen before.

6G and its benefits

Dr. Ndip: "Before the population can enjoy the benefits of a new generation, there is a lot of work behind it, which is implemented by researchers."

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Why are we looking at 6G when we haven't even implemented 5G yet?

Dr. Ndip: Although 6G is not expected to be introduced until 2030, there are still so many unanswered questions, for example about hardware development for mobile communications above 100 GHz, as it is expected that the D-band (0.11 THz to 0.17 THz) will probably be used. Never before have such frequencies been used for mobile communications. Therefore, the research and development community is starting much earlier to answer the software and hardware questions up to the applications. 10 years before market launch - that's typical. About five years before launch, the specifications are defined - then trials can follow. Before the public can enjoy the benefits of a new generation, there is a lot of work behind it, which is implemented by researchers. The Innovation Campus Electronics and Microsensor Technology Cottbus (iCampus Cottbus), for example, was set up for this purpose, in which Fraunhofer is researching the networking technologies and sensor technology of tomorrow with the BTU Cottbus-Senftenberg and two Leibniz institutes.

What new business models will emerge with 6G?

Dr. Ndip: Since 5G, packaging and connection technology has played a very important role in the development of wireless systems for mobile communication applications. As it is no longer trivial to produce a high-frequency front-end module for mobile communication, material, PCB and component manufacturers are challenged. This also opens up new business opportunities for SMEs, which played virtually no role in 1G to 4G. This is already creating many new business models, and it will be the same with 6G. As mentioned, frequencies in the 0.11 THz to 0.17 THz range are expected to be used for 6G: The higher the frequencies, the smaller the components. This means that we will be able to build very small systems for 6G. Such miniaturized 6G systems can be integrated into existing devices/machines and introduce new upgrades without changing the aesthetics or significantly altering the form factor of the devices/machines. As a result, countless new applications could emerge, especially in the vertical industry. This could lead to an explosion of new business models.

What technological solutions exist today for 6G?

Dr. Ndip: There are no complete solutions for 6G today. However, new concepts are being investigated to solve fundamental challenges. First of all, the enormous free-space attenuation must be overcome. To do this, we need to build multi-antenna architectures with hundreds of antennas per mobile base station, so-called massive MIMO (Multiple Input Multiple Output) architectures. We need to clarify how many basic elements we need to build and how we can interconnect them so that long transmissions, very good beamforming and low energy consumption are ultimately possible. In addition, any interference must not restrict the electromagnetic signal.

The first step is therefore to develop new massive MIMO system architectures for the efficient realization of the hardware. The second step is to implement the system architecture. And this is where Fraunhofer IZM comes into play: We will provide the necessary packaging technologies for system integration, new terahertz integrated massive MIMO antenna arrays and new radio frequency design methods so that 6G front-end modules can be built.

We have already proposed solutions for this: Our 6G project (6GKom) - the first BMBF-funded project in Germany to develop 6G terahertz modules - started on October 1, 2019. Fraunhofer IZM has already patented high-frequency system integration solutions for the realization of such modules. They are based on miniaturized fan-out packaging platforms with integrated antennas, which do not yet exist today.

The 6GKom project

Dr. Ndip: "In 6GKom, we want to develop a hardware basis for 6G at an early stage."

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What exactly is behind the 6GKom project?

Dr. Ndip: The project is coordinated by Fraunhofer IZM and is being worked on together with IHP, TU Berlin, TU Dresden and the University of Ulm. 6GKom is supported by an industrial advisory board consisting of 15 companies from the fields of material development, package development, chip design and production as well as test environments. There are also users from the automotive, aerospace, agricultural machinery and telecommunications sectors.

In 6GKom, we want to develop a hardware basis for 6G at an early stage. We want to research and develop an efficient, broadband and miniaturized MIMO D-band module with integrated beamforming capability. This module will enable data rates of several terabits/second and very precise localization applications for future 6G mobile communications. Furthermore, we want to research new baseband architectures, taking into account the parasitic terahertz effects in the D-band modules, and also develop corresponding test procedures and environments.

In order to achieve these goals, the consortium has already analyzed possible application scenarios together with the industrial advisory board and developed the necessary specifications. Based on this, a scalable massive MIMO system architecture has been developed. A novel chip-package-antenna co-design and an integration approach are currently being researched, which will make it possible to develop a broadband, miniaturized and powerful D-band module. Fraunhofer IZM's patented fan-out wafer-level packaging system integration platform with integrated antennas is used for the hardware implementation of the chip-package-antenna co-design and the integration approach. In contrast to existing package platforms, this has very good high-frequency characteristics and enables higher system miniaturization, reliability and cost reduction. In order to test the module in the D-band with regard to its suitability for mobile communications, we will investigate and develop new signal processing algorithms.

What exactly is the technical difference between 5G and 6G?

Dr. Ndip: There are many differences between 5G and 6G. Let me just mention a few. First of all, the frequency spectrum: until 4G, all mobile communication took place in the sub-6 GHz range. In 5G, we are at 26 GHz, 28 GHz and 39 GHz, i.e. above the 6 GHz spectrum for the first time. And in 6G, as mentioned, we intend to go into the terahertz range, probably in the D-band (0.11 THz to 0.17 THz). In addition, 6G could also use VLC (Visible Light Communication), a promising optical communication approach for short-range communication using visible light between approximately 400 and 800 THz.

Both 5G and 6G will continue to use the frequencies below 6 GHz .

Secondly, the data rate: 5G is expected to achieve a peak data rate of approximately 20 Gbit/s, where 6G is expected to achieve a peak data rate of more than 1 Tbit/s. There is also a significant difference between the data rate per user: in 5G about 100 Mbit/s is expected, while for 6G about 1 Gbit/s is expected.

Thirdly, the latency: 5G is expected to have a latency of approximately 1 ms and higher. 6G would achieve far less than 1 ms, probably 100 µs. Extremely low latency is very important for applications such as holographic communication, virtual, augmented and mixed reality as well as remote medical diagnosis and surgery. In these medical applications, the network must simultaneously offer very high reliability, low latency and extremely high data rates. In contrast to 5G, 6G is being developed in such a way that all of these requirements are met simultaneously.

There will also be a big difference in terms of the number of connected devices per square kilometer as well as energy efficiency. However, I believe that it is still too early to quantify most of these differences.

The interview was conducted by Olga Putsykina, Fraunhofer IZM.