Ultra‐Reliable and Low Latency Communication Systems

Ultra‐reliable and low latency communication (URLLC) requires a different angle of cellular communications and networks. Two key metrics for URLLC systems are low latency and high reliability. This chapter deals with user plane latency and reliability, and discusses their key techniques. User plane latency for URLLC communications is composed of transmission processing time, transmission time, and reception processing time. In addition, the latency has deterministic components or stochastic components. The chapter introduces a theoretical background for short packet transmission, analyses latency of 4G and 5G systems, and discusses one 5G key techniques to improve latency. In a cellular network, there are many network components affecting the end‐to‐end latency and each component causes a delay. Multi‐access edge computing (MEC) is typically located at the edge of a network. MEC supports latency‐critical 5G applications and also alleviates the burden of traffics of backhauls.