Stochastic geometry-based analysis of multiple region reverse frequency allocation scheme in downlink HetNets

Femtocell access points (FAPs) are low-powered and small-sized base stations that provide high data rates and coverage to the indoor users. Because of their operation in the same spectrum as that of macrocells, interference becomes a major problem. Reverse frequency allocation (RFA) is one of the robust schemes, which mitigate the interference by transfering it from the macrocell base station (MBS) to the macrocell user equipments (MUEs), particularly in the downlink. In this paper, we provide a multiple region 2-tier downlink model using the RFA scheme. We derive a closed-form expression for the coverage probability of femtocell user equipment (FUE) using different RFA schemes under open access mode. Where FAPs and MUEs are modeled as independent Poisson point process (PPP). Using simulations, we show that for reasonable values of signal-to-interference ratio, multiple regions enhance the coverage probability of an FUE. It is shown that a 4-region RFA outperforms the other RFA schemes at different densities of FAPs and MUEs as well as for different values of threshold for the same set of parameters.