  The fifth-generation cellular mobile networks are expected to support mission
critical ultra-reliable low latency communication (URLLC) services in addition
to the enhanced mobile broadband applications. This article first introduces
three emerging mission critical applications of URLLC and identifies their
requirements on end-to-end latency and reliability. We then investigate the
various sources of end-to-end delay of current wireless networks by taking the
4G Long Term Evolution (LTE) as an example. Subsequently, we propose and
evaluate several techniques to reduce the end-to-end latency from the
perspectives of error control coding, signal processing, and radio resource
management. We also briefly discuss other network design approaches with the
potential for further latency reduction.
