On the Set of Joint Rayleigh Fading Distributions Achieving Positive Zero-Outage Capacities

With emerging technologies like 6G, many new applications like autonomous systems evolve, which have strict demands on the reliability of communications. It is therefore of great interest, how these strict reliability constraints can be achieved. In this work, we show that the joint distribution of the fading coefficients of different communication channels has a tremendous impact on the outage probability of a communication system. In particular, we consider a system with two slowly fading channels that constitute a diversity system. We present a structure of the joint distribution for which the zero-outage capacity is strictly positive. Interestingly, the set of joint distributions, that lead to positive zero-outage capacities, is larger than a singleton in general. Finally, the results are evaluated for the special case of Rayleigh fading.