Mission Reliability for URLLC in Wireless Networks

Achieving connectivity reliability for ultra-reliable low-latency communication (URLLC) is one major challenge for future wireless communications systems. The current understanding of reliability does not sufficiently cover time-related aspects, e.g., time-varying channels or the duration of a certain condition in a wireless system. Moreover, different applications require diverse execution periods during which no failure is allowed, which we denote as
mission duration
. In this letter, we focus on time-related aspects and introduce the performance metric
mission reliability
to wireless communications systems and employ its connection to the
mean time to first failure
, reflecting the expected time until the first failure occurs. As diversity is accepted to be essential for reliability, their evaluation is presented regarding a multi-connectivity system with Rayleigh fading, reflecting frequency diversity. We demonstrate the trade-off between mission duration, mission reliability, and the number of links used for multi-connectivity, which can stimulate the discussion on URLLC and advance the design of future wireless systems.