February 14, 2022

Tap-proof THz communication for industrial IoT: Fraunhofer HHI coordinates BMBF-funded CERTAIN project

February 14, 2022

In the CERTAIN project, Fraunhofer Heinrich Hertz Institute (HHI) is researching and developing tap-proof THz transmission systems for the Industrial Internet of Things (IoT). The research team is using three future technologies: physical layer security (PLS), terahertz transmission technology and multiple-input multiple-output (MIMO). The researchers will combine these three for the first time, designing a tap-proof wireless transmission concept. They will then implement them in a demonstrator. The project started in October 2020 and will run until September 2023. CERTAIN is funded by the German Federal Ministry of Education and Research (BMBF) with 1.5 million euros.

The IoT is steadily growing and encompasses a wide range of devices - from low-resource sensors in manufacturing to distributed cloud infrastructure. In environments such as Industry 4.0 factory floors, all of these components need to communicate with each other in a highly secure and reliable manner. Until now, this communication has been secured via computationally intensive cryptographic encryption.

The CERTAIN team wants to relax the cryptographic effort. Their approach is threefold. First, they complement conventional cryptographic encryption with what is known as “physical layer security” (PLS). PLS is essentially based on imperfections of the physical transmission layer (e.g. the radio channel). These physical features of the radio channel are unique between a transmitter and a receiver. If used correctly, they can be a low-resource component for tap-proof communications.

The second important component is terahertz transmission technology. The THz frequency band has an inherently high electromagnetic compatibility in the industrial environment while offering significantly higher transmission rates. Currently, IoT applications use a radio channel that allows only moderate transmission rates due to its carrier frequencies of well below 10 GHz. The high-frequency THz band makes data rates of > 100 Gb/s possible. In the context of IoT, this enables the transmission of monitoring/control data to and from IoT terminals without compression and thus low-latency as well as with low resource requirements.

Terahertz transmission technology also enables researchers to use improved multiple antenna methods (MIMO). Due to their up to 100 times shorter wavelength (~ 1 mm), THz links are characterized by high locality, high directivity of the antennas, and smaller geometrical antenna dimensions with the same antenna gain. This enables very compact multi-antenna arrays for MIMO scenarios for the first time. In addition, researchers can leverage specific THz channel properties, such as locality and directivity, to establish tap-proof communication between spatially distributed IoT devices, e.g. within a sprawling factory floor.

The “Optical Submarine and Core Networks” group of the “Photonic Networks and Systems” department at Fraunhofer HHI contributes its expertise in THz transmission technologies to CERTAIN. The team will develop a real-time, FPGA-based THz MIMO demonstrator to validate the coding schemes designed in the project. To do this, the researchers use MIMO and customized, low-resource signal coding.

In addition to Fraunhofer HHI, the University of Siegen and Ulm University are involved in the project. First project results on achievable semantic security for indoor THz communication were recently presented in a joint publication of the project partners “Semantic Security for Indoor THz-Wireless Communication ” at the 17th International Symposium on Wireless Communication Systems (ISWCS) 2021.