On Power-Latency-Throughput Tradeoff of Diversity Enabled Delay-Bounded Communications

Delay-constrained communications have attracted considerable recent attention because it holds the promise of playing a vital role in time sensitive networking (TSN) and deterministic networking (DetNet). In this paper, we investigate the tradeoff between power, latency, and throughput, which characterizes a fundamental performance limit of diversity enabled delay-bounded communications over fading channels. In particular, we are interested in a typical cross-layer scheduling policy, namely, the age-aware non-FIFO strategy, which is capable of satisfying a hard delay constraint by exploiting the physical-layer diversity methods. Saddle point approximation is adopted to obtain the analytical approximation of the average transmission power as a function of the throughput and the delay threshold normalized to the coherence time. This analytical expression characterizes the power-latency-throughput tradeoff of the diversity enabled delay-bounded communications over the fading channel. To validate our analysis, we present a discretization-based method to conduct the numerical calculation. The numerical results match well with the simulation results, which also shows that the approximation error will vanish with sufficiently small discretization granularity.