Overview of 5G URLLC

Abstract

We will present an overview of PHY/MAC design aspects for Ultra-Reliable Low Latency Communications (URLLC) with particular focus on the 3GPP New Radio (NR) mobile communications standard. The major use cases and enablers for URLLC will be analyzed thanks to existing results from the literature, both for single link and multi-cell cases. Ultra-reliability requires high diversity order, where both micro and macro diversity need to be considered to mitigate both small and large scale fading effects, respectively. On the other hand, Short Transmission Time Interval (TTI), low protocol delays and preemptive scheduling are key enablers for low latency transmission. Moreover, we will present some results of ongoing research in the field of multi-service scheduling where URLLC are multiplexed with eMBB traffic. Nevertheless, also non-scheduled protocols will be considered for contention-based massive Machine Type Communications (mMTC) and to ease the burden on the control signaling reliability.