Confidence Level for Finite Blocklength Ultra Reliable Communication over Fading Channels

We present the reliability confidence level as a way to quantify reliability for ultra reliable connections in uncertain environments subject to random block-error rate fluctuations. As ultra reliability is usually linked to the low latency constraint, we analyze the reliability confidence level using the latest results on block-error rate in the finite blocklength regime. The analysis is carried out for OFDM-based systems over Rayleigh slow frequency block-fading channels. The reliability confidence level is bounded using analytic expressions which are then applied to solve two optimization problems. We first find the minimal resources (or codeword length) to guarantee a target reliability with a given confidence. We then investigate an optimal resource sharing strategy within the context of 5G New Radio. The solutions for optimization problems are obtained without resorting to cumbersome Monte-Carlo simulations. Numerical evaluations validate the relevance as well as the tightness of the proposed bounds and approximations.