  For the fifth generation (5G) wireless network technology, the most important
design goals were improved metrics of reliability and latency, in addition to
network resilience and flexibility so as to best adapt the network operation
for new applications such as augmented virtual reality, industrial automation
and autonomous vehicles. That led to design efforts conducted under the subject
of ultra-reliable low-latency communication (URLLC). The technologies
integrated in Release 15 of the 3rd Generation Partnership Project (3GPP)
finalized in December 2017 provided the foundation of physical layer design for
URLLC. New features such as numerologies, new transmission schemes with
sub-slot interval, configured grant resources, etc., were standardized to
improve mainly the latency aspects.
  5G evolution in Release 16, PHY version finalized in December 2019, allows
achieving improved metrics for latency and reliability by standardizing a
number of new features. This article provides a detailed overview of the URLLC
features from 5G Release 15 and Release 16, describing how these features
permit URLLC operation in 5G networks.
