  5G is envisioned to support three broad categories of services: eMBB, URLLC,
and mMTC. URLLC services refer to future applications which require reliable
data communications from one end to another, while fulfilling ultra-low latency
constraints. In this paper, we highlight the requirements and mechanisms that
are necessary for URLLC in LTE. Design challenges faced when reducing the
latency in LTE are shown. The performance of short processing time and frame
structure enhancements are analyzed. Our proposed DCI Duplication method to
increase LTE control channel reliability is presented and evaluated. The
feasibility of achieving low latency and high reliability for the IMT-2020
submission of LTE is shown. We further anticipate the opportunities and
technical design challenges when evolving 3GPP's LTE and designing the new 5G
NR standard to meet the requirements of novel URLLC services.
