URLLC

Definition

The fifth generation of mobile communications, 5G, represents a significant advance over previous mobile communications standards. The International Telecommunication Union (ITU) has defined profiles for three areas of application: Enhanced mobile broadband (eMBB) with high and efficient data transfer rates, massive machine-type communications (mMTC), which allows a large number of devices to be networked (see Internet of Things), and ultra-reliable low-latency communications (URLLC). 5G technology is the first generation of mobile communications to support all three profiles and, increasingly, various mixed forms. URLLC offers high-performance data transmission that meets the highest reliability requirements while ensuring minimal signal delay (latency) between end devices and the base station. The profile is therefore designed for time-critical applications that depend on minimal delay times and require robust, fail-safe mobile communication. 

The ITU has defined a target of 1 millisecond for the latency of ultra-reliable real-time communications. For 4G, the target was 10 milliseconds. In practice, however, it is much higher. URLLC’s minimum requirement for data transfer reliability has been set at 99.999 percent at a data transfer rate of up to 20 Gbit/s.  

Current applications and opportunities

A pilot project in the field of semi-autonomous driving is currently underway in the Swiss town of Schaffhausen, where the Swiss Transit Lab is testing a semi-autonomous bus that connects the railway station with an outlying suburb via four stations. The minibus runs without a driver, but in critical situations it can be controlled remotely from the head office via mobile communications. The Swiss Transit Lab, together with SBB and the canton of Zurich, is launching a similar experiment this year in the valley region of Furttal. Here, four semi-autonomous robotic taxis to begin with – and later also robo-buses – will supplement public transport for local links to the communities around Otelfingen. In this application, the advantageous features of the URLLC configuration come into play, because speedy and extremely reliable transfer of the data about the situation on the road is necessary for remote control. This is especially the case in critical traffic situations. 

In the EU, the US, Canada, the UK and China, pilot projects are underway on platooning, which enables heavy goods vehicles to move as a group. With platooning, multiple lorries are connected via mobile communications to form a road train. The frontmost vehicle controls the entire column and sends control commands in real time via 5G to the vehicles that follow.  Lower air resistance means that energy consumption can be reduced and roads can be used more effectively. 

URLLC offers great potential for many 5G-based applications that were not possible with previous generations of mobile communications. In industrial automation, for example, production chains and robot assembly lines can be monitored and controlled. Wireless controls give robot units greater mobility, allowing them to be used for a wider range of applications. In healthcare, ultra-reliable low-latency communications can support remote diagnosis and, in the future, remote surgery, in which medical staff must safely perform remote procedures with minimum latency. This could improve access to healthcare services in remote areas. 

Challenges 

The biggest challenge for a reliable URLLC application is achieving comprehensive and reliable coverage of Switzerland with the 5G network. Owing to restrictive environmental regulations and lengthy approval processes, the expansion and modernisation of 5G is proceeding at a slower rate than its technical development. Compared to neighbouring countries, precautionary emission limits for radiation exposure (plant limit values) are very strict and limit the performance of the transmitter facilities. Not only does this mean less capacity per transmitter site, it also reduces the coverage, which has to be compensated for by additional transmitter sites. This requires higher investment compared to other countries. 

Mobile communications coverage is a shared medium, which means that all customers share the available capacity and bandwidth of a transmitter facility. In principle, this also applies to 5G. Therefore, at times of high demand for data transmission, the maximum data rate may not be achievable. However, 5G offers the option of unbundling data streams by creating virtual networks, in a process known as network slicing. This means that a separate network can be provided for security-related requirements, such as those of emergency services (police, ambulance, fire and rescue service), which meets the increased requirements in terms of guaranteed bandwidth, latency or security, even when there is high general demand.  

Focus on industry

The market launch of ultra-reliable low-latency communications in industry is still ahead of us. Companies that strive for digital transformation across the board stand to benefit. Because this is a global standard, locally produced and networked machines can also be used anywhere in the world. In addition, URLLC enables real-time control of industrial processes. This is particularly important for applications that require precise timing and high reliability, such as smart factories or robot assembly lines. In addition, private 5G networks can ensure local mobile phone coverage on company premises, which contributes to low latency while at the same time increasing cybersecurity and data protection.  

Increasing automation has the potential to replace jobs involving simple, monotonous tasks. On the other hand, new jobs are being created in research and development as well as in the operation of URLLC-controlled facilities. Knowledge of communication technology, mechanical engineering, electrical engineering and computer science is required.  

International perspective

Research and development takes place in the laboratories of manufacturers such as Ericsson, Nokia, Samsung and Huawei, which are mainly based abroad. Huawei has been operating a research laboratory in Zurich with over 100 employees since 2020. At Swiss universities, particularly ETH Zurich and various universities of applied sciences such as OST in Rapperswil, more than a dozen research groups are working on the further development of 5G-enabled applications in various areas. 

Future applications

In the future, URLLC solutions are also planned in the areas of infrastructure and public services. For example, the federal government wants to replace the current Polycom radio system for the emergency services with a 5G-based security communication system by 2035. In addition to call data, this network will also process images, drone recordings of damage sites and other critical information and make them available to all participants in real time in the event of an incident. Meanwhile, SBB’s communication network, which is still based on the 2G standard, is also set to be brought up to 5G standard as part of the Future Railway Mobile Communication System (FRMCS) project. This will open up new possibilities for real-time control of train traffic and for line utilisation. 

5G networks and the future 6G network will increasingly integrate software-based network components. This makes it possible to adapt the networks flexibly and responsively to changing requirements. The communications industry also expects major advances from AI-supported systems that independently search for the best configuration for optimal data volume and speed. This will also enable more comprehensively networked applications such as holograms in image transmission. 

URLLC is one of the possible configurations of 5G. The high degree of flexibility and the wide range of possible applications enable mobile-based data transfers in many industries while their various properties give them a high disruptive potential. As 5G networks continue to expand around the world, we can expect an increasing number of innovative offers and services that will drive the digital transformation forward.