What is URLLC?

As per 3GPP Release 15 5G-NR, Ultra-Reliable Low-Latency Communication (URLLC) is a set of features that provide low latency and ultra-high reliability for mission critical applications such as industrial internet, smart grids, remote surgery and intelligent transportation systems.

5G offers three services that could transform current industries and create new industries. They are:

• Enhanced mobile broadband (eMBB): Faster speeds for use cases requiring high data rates like large-scale video streaming, and virtual reality.
• Ultra-reliable low latency communications (URLLC): Low latency for mission-critical services.
• Massive Machine Type Communication (mMTC): Providing internet access for sensing, metering, and monitoring devices.

3GPP has specified URLLC as a key feature for Release 15 5G NR, in addition to eMBB. As per 3GPP Release 14, Latency with 4G LTE is in the 4-millisecond range but with the introduction of URLLC in Release 15, the target is 1-millisecond. URLLC also provides end-to-end security and 99.999 percent reliability.

The design of a low-latency and high-reliability service involves several components: Integrated frame structure, incredibly fast turnaround, efficient control and data resource sharing, grant-free based uplink transmission, and advanced channel coding schemes. But the designing of physical layer will be the most challenging thing as satisfying low latency and ultra-high reliability - two conflicting requirements at the same time is not an easy task.