Ultra-reliable and low-latency communications: applications, opportunities and challenges

In the upcoming 5G and beyond systems, ultra-reliable and low latency communication (URLLC) has been considered as the key enabler to support diverse mission-critical services, such as industrial automation, remote healthcare, and intelligent transportation. However, the two stringent requirements of URLLC: extremely low latency and ultra-strict reliability have posed great challenges in system designing. In this article, the basic concepts and the potential applications of URLLC are first introduced. Then, the state-of-the-art research of URLLC in the physical layer, link layer and the network layer are overviewed. In addition, some potential research topics and challenges are also identified.