Interference Modeling and Performance Evaluation of Heterogeneous Cellular Networks

This work considers the development of a realistic statistical model to represent the interference in heterogeneous wireless networks. The considered networks are comprised of one or more femtocells deployed in buildings with unknown internal structures and a preplanned cellular network. The proposed interference model is based on a novel random floor plan generator, which is used to construct a statistical rather than site-specific floor plans. The developed model is augmented with Nakagami fading to represent the femtocell interference signal in the outdoor environment. The model is then utilized to evaluate the performance of the macrocell users where closed-form formulae for the outage probability and signal-to-interference ratio at the receiver front-end are derived. The obtained results reveal that a femtocell signal propagating from an indoor transmitter to an outdoor receiver will experience a composite shadowing/fading process where the Nakagami distribution is adopted for the fading part while the shadowing is modeled by lognormal mixture distribution. Analytical and simulation results show that placing the femtocell base-station (FBS) close to the center of the house can significantly reduce the impact of the interference on the outdoor macrocell users as compared to a randomly placed FBS.