URLLC: What it is and how it works

Ultra-Reliable Low Latency Communications (URLLC), a subset of the 5G network architecture, ensures more efficient scheduling of data transfers, achieving shorter transmissions through a larger subcarrier, and even scheduling overlapping transmissions. It supports highly important data transfer that requires low latency, such as self-driving cars and remote surgery.

The 5G network architecture has been designed with three key service areas in mind:

  1. Massive Machine-Type Communications (mMTC). This will be used to connect large numbers of devices and is expected to transform the IoT industry.
  2. Enhanced Mobile Broadband (eMBB). This supports high bandwidth applications such as augmented/virtual reality (AR and VR) and streaming, providing faster download speeds and improved user experiences.
  3. Ultra-reliable Low-Latency Communication (URLLC). This will be used for mission-critical applications which require a guaranteed connection and low latency.

What is URLLC?

URLLC supports use cases that require high network reliability, more than 99.999%, and extremely low latency of approximately 1 millisecond for data transmission. For example, autonomous driving would require a connection capable of this, as there is such high risk involved. Autonomous driving has a whole host of benefits, from timesaving to improving safety by eliminating user error. However, it would need all vehicles to be connected to each other vehicle-to-vehicle, and to roadside systems, vehicle-to-infrastructure, such as traffic light systems, emergency services and road maintenance programmes. Data would need to be shared in real-time, with minimal latency, as safety requirements demand ultra-reliable connections.

Smart factories and Industry 4.0 have similar requirements, where machinery and robotics need to interact with each other in real time. They might also require real-time information from other sensors across the manufacturing facility. Low-latency systems allow these machine-operated systems to work safely and efficiently to enhance production lines.

Other use-cases might include remote and augmented reality healthcare, such as remote surgery, smart electricity distribution and cloud-based gaming and entertainment.

How does it work?

Network slicing, also known as software-defined networking or SDN technology, enables each of the three 5G areas to operate separately within the 5G ecosystem. Each slice essentially acts as its own network, with its own provisioning, security, and quality of service requirements. So mMTC, which requires low-security and low-bandwidth, is separated from URLLC, which provides high-security and high-reliability. Yet each of these slices exists within the same physical network infrastructure.

URLLC demonstrates excellent reliability and low latency. This is defined as having no more than 0.001% of 20 byte packets fail to be delivered after 1 ms. 5G network architecture aims to eliminate these delivery failures and errors using technologies such as beamforming, network slicing and packet retransmission protocols.

To achieve super low-latency transmissions, 5G technology can use grant-free uplink access. In a 4G LTE system, you’d expect the user device and base station to exchange a series of signalling requests, a “handshake”, before exchanging any data. The base station must grant access before the data can be sent, adding latencies of up to 11 ms.

A URLLC 5G system can use grant-free uplink access, whereby base stations can reserve capacity for uplink transmissions. The user device does not need to wait for scheduling requests and grant access, which dramatically reduces end-to-end latency. As for downlink data, resource can be allocated from other network slices. This is known as pre-empting and the device will be notified that the connection type has changed.

Key considerations for URLLC

The introduction of the 5G network brings increased network complexity that enables new technologies to be employed to meet a wide range of consumer and business demands. This in turn, means diversification of the communications industry, with a vast number of opportunities arising as 5G availability becomes more widespread across the globe. In particular, URLLC will give mobile connectivity to mission-critical applications that have been discussed for many years but are just now coming to fruition.

Electronic hardware designers and software engineers will face even greater challenges in terms of developing high-performance devices. New protocols, coding methods and provisioning techniques may be required from software developers for some applications to ensure maximum security and reliability. Existing hardware will also need to be updated to meet the specifications of the 5G frequency bands, as well as the continuously evolving speed and battery-life requirements.

Designing devices for URLLC

URLLC offers an interesting proposition for the Internet of Things (IoT). It opens up new opportunities to create devices in scenarios where hyper-reliability is critical. At Antenova, we’re helping the industry innovate by creating small, high performance antennas that are easy to integrate and pass all the necessary network certification processes.

To see our full range of antennas for cellular devices – including 5G, 4G and 3G – browse our range of antennas or download our antenna comparison guide.

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