Ultra-Reliable and Low-Latency Wireless Communication: Tail, Risk and\n Scale

Ensuring ultra-reliable and low-latency communication (URLLC) for 5G wireless\nnetworks and beyond is of capital importance and is currently receiving\ntremendous attention in academia and industry. At its core, URLLC mandates a\ndeparture from expected utility-based network design approaches, in which\nrelying on average quantities (e.g., average throughput, average delay and\naverage response time) is no longer an option but a necessity. Instead, a\nprincipled and scalable framework which takes into account delay, reliability,\npacket size, network architecture, and topology (across access, edge, and core)\nand decision-making under uncertainty is sorely lacking. The overarching goal\nof this article is a first step to fill this void. Towards this vision, after\nproviding definitions of latency and reliability, we closely examine various\nenablers of URLLC and their inherent tradeoffs. Subsequently, we focus our\nattention on a plethora of techniques and methodologies pertaining to the\nrequirements of ultra-reliable and low-latency communication, as well as their\napplications through selected use cases. These results provide crisp insights\nfor the design of low-latency and high-reliable wireless networks.\n