Downlink coverage analysis of n-tier heterogeneous cellular networks based on clustered stochastic geometry

Assuming a connected base station at the point of reference (or origin) in the tier of interest, we derive an expression for the downlink probability of coverage over a heterogeneous network, wherein the base station locations result from different point processes, such as Poisson point and Poisson cluster processes. Numerical results show increasing the base station density in each tier lowers the coverage probability, but not as much as increasing the coverage threshold does. We also provide lower and upper bounds for the coverage probability in a two-tier heterogeneous network modeled with Poisson point and cluster processes, and evaluate the effect on those bounds when changing the various parameter values. These results are of potential use for future cellular heterogeneous network designs.