The evolution of the internet has tended to focus on delivering ever faster connectivity to users. In recent years however, there has been growing awareness of the need to also support a massive number of connected devices, and to deliver extremely reliable wireless connections to other devices. These principles, which have become some of the building blocks of 5G, were identified and explained in a groundbreaking ERC-funded project. This project, proposed in 2014 and launched in 2015, correctly anticipated today’s hyperconnected world. “Think about connected simple devices, what we call the Internet of Things (IoT),” says WILLOW project coordinator Petar Popovski, professor of wireless communications at Aalborg University in Denmark. “What we are dealing with here are millions of devices that use small amounts of data, some of which require an ultra-reliable network.” The analogy Popovski uses is with financial institutions. Broadband "is like an investment bank,” he explains. “You go in and borrow EUR 300 000 to buy your house, and the administrative overheads are negligible for this sum.” Now think about 300 000 individuals going into the bank to borrow EUR 1. “This is the same amount, but the overheads are now huge. This is the challenge we face in a world with a massive number of small IoT transmissions.”
A connected world
After correctly anticipating the connectivity challenges facing society, the WILLOW project set about identifying key principles for building new systems. The project recognised that communicating small packets of data required a fundamental rethink. In developing ultra-reliable networks, the project team underlined the importance of machine learning. “Wireless systems need to apply learning and knowledge of the radio environment in order to be able to guarantee that a link can operate 99.999 % of the time,” says Popovski. “We showed in this project that this is absolutely necessary.” Another important concept is multi-connectivity, also called interface diversity. This involves exploiting multiple interfaces (cellular, Wi-Fi, etc.) available on a device, in order to ensure the delivery of information. “We also showed that when transmitting small packets of data, it is essential to know how to code the metadata, which describes what the data is,” adds Popovski.
Shaping the future
Ultimately, WILLOW succeeded in providing models for combining wireless services with demands for ultra-reliable low latency and massive amounts of sporadic transmissions. More than 80 publications have come out of the project, some of which already have a large number of citations. “What we predicted 6 to 7 years ago has in fact turned out to be an important part of 5G,” he explains. Indeed, the project has been critical in inspiring researchers and engineers to build the technology for 5G and beyond-5G wireless systems. Already, massive machine-type communications (mMTC) and ultra-reliable and low-latency communications (URLLC) have become two of the three pillars of 5G. While the results have been of great interest to wireless and electronics engineers, the influence of the project has been wider. Engineers working in fields such as automation and logistics can be profoundly influenced by these concepts. “The audience is now so much broader because so many industries want to digitalise their systems,” notes Popovski. The impact of WILLOW, a critical milestone in the evolution of communication technology, will continue to be felt for years to come. IoT connectivity, as well as ultra-high reliable connections, are set to bring disruptive changes across a range of sectors including energy, transportation, industrial production and health.
WILLOW, 5G, broadband, internet, connectivity, wireless, massive machine-type communications, mMTC, ultra-reliable and low-latency communications, URLLC