Variable Rate Ultra-Reliable and Low-Latency Communication for Industrial Automation

Ultra-reliable low-latency communication (URLLC) is an increasingly important aspect of wireless communications in the 5th generation mobile networks (5G) era. Specifically, in the context of wireless mission-critical communication for factory automation where the most demanding reliability requirement of nine nines figure is considered for isochronous packet delivery in highly constrained latency regime of 1 ms. This paper proposes a closed-loop URLLC scheme for the down-link (DL) of a factory automation network with time-varying fading channel. The proposed scheme consists of two phases: in the first phase the controller entity trains itself about the channel state experienced by the sensor/actuator nodes while in the second phase each of those nodes receives its DL message with a unique transmission rate that is properly adapted to its instantaneous channel state to fulfill the stringent ultra-reliable requirement. Numerical analysis shows that the proposed URLLC scheme can achieve an extended range of spectral efficiency as compared to open-loop protocols with equal-rate transmission and provides robust ultra-reliability across a wide range of data payloads.