For mobile communications to work, getting the timing right is critical. That is because mobile networks are divided into areas, known as radio cells, where base stations are located. These stations broadcast radio signals to mobile devices, such as smartphones, and receive radio signals sent back by these devices. "Neighboring base stations have to agree on whose turn it is and when. Otherwise, they're literally constantly jamming each other," Lenzen explains.
Satellite systems broadcast time signals
To be able to synchronize, the stations need a common time signal. At present, they receive this as standard via so-called GNSS services. GNSS stands for Global Navigation Satellite Systems, which are satellite-based navigation systems such as GPS. "The problem is that these signals are very easy to interfere with. They are also not properly secured so far, and that makes our communication channels vulnerable to attacks," says Lenzen. The fact that GNSS time is not available indoors and in other places without line-of-sight to a sufficient number of satellites also limits the possibilities of 5G, he adds. "Currently, that's why you have to rely on wired connections to a location with reception. But 5G and 6G networks could actually work with temporary base stations, using a directional wireless link instead of cabling. But that won't work without synchronization that is as precise as possible."
Good communication between neighbors
All networks, not only cellular ones, rely on direct neighbor components communicating with each other first and foremost, according to Lenzen. "If you manage to make them as synchronous as possible, many problems can be solved, because then the actual time doesn't matter at all," Lenzen says. This approach is called Gradient Clock Synchronization. "We have developed novel algorithms that can do just that," Lenzen explains. "On the one hand, this leads to lower response times, even in very large systems. On the other hand, it saves the industry a lot of money." That is because GNSS time suffers from poor availability, in addition to the problems already mentioned. "If you depend on it, you need highly stable oscillators as clocks in the base stations. With our solution, employees are no longer dependent on GNSS systems and can therefore work with much cheaper, less stable oscillators," says Lenzen.
But better response times and design advantages are not the only things Lenzen hopes to achieve with his project. GradeSync is also expected to bring innovation in terms of safety. Precise distance information is needed when measuring the synchronization of radio cells. "We are therefore working with CISPA Faculty Dr. Mridula Singh. She is researching solutions for secure range and position determination. If we can incorporate her secure ranging algorithm into our prototype, it will mean a huge leap in technology. So far, there is no implementation of Gradient Clock Synchronizsation, not even an insecure one." Lenzen's research is by no means only of interest in the field of mobile communications. "What we're doing is also relevant to chip manufacturers," Lenzen says.
Startup Timelords works on implementation
In order to align his research approach with the concrete needs of industry and to translate it into applicable products as quickly as possible, Christoph Lenzen has founded the startup "Timelords" together with other CISPA researchers. The basis for the project is Lenzen's long-standing research work on synchronization in distributed networks. In 2017, the CISPA Faculty had received an ERC Starting Grant for his project "A Theory of Reliable Hardware." In it, Lenzen developed a mathematical approach to modeling circuits in processors in such a way that errors do not throw them out of sync, thus avoiding performance degradation. GradeSync is Lenzen's second ERC-funded proof of concept resulting from this original project, along with FastVolt. It is a testament to an idea's viability in the real world. "It's great that the ERC believes in my research and supports our idea. The money helps us enormously," says Lenzen. He hopes that industry will also recognize the potential of his approach and thus help drive it forward.
About the person
Christoph Lenzen's research focuses on the theory of distributed computing, in particular clock synchronization, load balancing, graph problems, fault tolerance and algorithms in hardware. In 2011, he successfully completed his PhD studies at ETH Zurich and subsequently held postdoctoral positions at the Hebrew University of Jeruslem and the Weizmann Institute of Science, followed by the Massachusetts Institute of Technology in 2013. In July 2014, he became a research group leader at the Max Planck Institute for Computer Science in Saarbrücken before joining CISPA as Faculty in 2021.
About the ERC
The ERC, established by the European Union in 2007, is the main European funding organization for excellent frontier research. It funds creative researchers of all nationalities and ages to carry out projects across Europe. The ERC offers four core funding programs: Starting Grants, Consolidator Grants, Advanced Grants and Synergy Grants. Through its Proof of Concept Grant, the ERC helps grantees bridge the gap between their groundbreaking research and the early stages of commercialization. The ERC is governed by an independent governing body, the Scientific Council. Maria Leptin has been the president of the ERC since November 2021. The ERC is led by an independent governing body, the Scientific Council. Since November 2021, Maria Leptin is the President of the ERC. The overall ERC budget from 2021 to 2027 is more than €16 billion, as part of the Horizon Europe programme, under the responsibility of the European Commissioner for Innovation, Research, Culture, Education and Youth, Mariya Gabriel.