Terahertz innovation delivers ultra-high mobile data rates
Since the advent of the smartphone, data consumption has exploded. Consumers and businesses increasingly rely on mobile data to deliver a range of services, and this demand is only expected to grow in the future. “From a purely technical point of view, this presents a challenge,” notes ThoR project coordinator Thomas Kürner from the Technical University of Braunschweig (TU Braunschweig) in Germany. “What can we do to facilitate higher data rates?” One way is to increase the efficiency of data transmission systems, in order to squeeze more data into the bandwidth that is currently available. “This is getting more and more difficult to do,” says Kürner. Another way is to increase the bandwidth available. But this is challenging too, as more and more available spectrum gets used up.
High-frequency bandwidth
The idea for the ThoR project came from the discovery that along the spectrum – beyond 275 gigahertz in the terahertz (THz) frequency range – there is still bandwidth available to deliver mobile data services. “This space is not completely unregulated,” adds Kürner. “There are some scientific applications like Earth-exploration satellites or radio astronomy that use bandwidth here. But enough available bandwidth has been found to potentially build systems that could deliver high data rates.” To achieve this, a significant obstacle must be overcome. Using high frequencies can result in significant path loss, or a reduction in power intensity. To mitigate this loss, the potential of high-gain THz antennae to ensure a stable backhaul link can be used. The backhaul link of a mobile network describes the connection of a cell site – usually a cell tower – to the core network. While this link can be achieved via fibre-optic cables, this means digging up streets. In cities especially, connecting every base station of the mobile network by cable is simply not feasible.
THz radio link
The objective of the ThoR project therefore was to demonstrate that a THz radio relay link provided by antennae mounted on two rooftops could provide a viable alternative. The project team was confident that this would create a backhaul connection between mobile radio cells and the nodes of the mobile radio network, without the need for any road construction work. To achieve this, the project brought together a consortium of partners from Europe and Japan. Many of these partners had developed the building blocks for such a prototype. The ThoR project took this work a step further by integrating these elements into a functional, bidirectional THz radio link. Once the technology had been integrated, antennae were installed on two buildings on the university’s campus, at a distance of over 160 metres. Real data, including video, was then transmitted, and the efficacy of the system analysed by Kürner and his team.
High data rates
The project successfully demonstrated the potential of a bidirectional THz radio link to the data network of mobile radio providers. The prototype was shown to be capable of transmitting very high data rates, and scalable so that even higher data rates could be realised. “We were able to show how this technology can efficiently transport wireless communication,” says Kürner. “This could help ensure that all the capabilities that have been promised with 5G and 6G are realised.” Further development of the prototype is still needed before the technology can be brought to market. Kürner and his team are nonetheless confident that the potential of this backhaul innovation is there.
Keywords
ThoR, terahertz, mobile, radio, bandwidth, smartphone
