Designing femtocell exclusion zones to minimize power in a heterogeneous network

In this paper, we propose an exclusion zone around each femtocell in a two-tier heterogeneous network, in which macro users enjoy exclusive interference-free access to a frequency band. The femto users, and macro users outside this region, share the remaining spectrum resource. The exclusion zone is a disc centered on the femto base station because here we only consider closed-access femtocells, meaning that the macro users within a femtocell cannot be off-loaded to the femto base station. Under the assumption that the bandwidth dedicated to macro users is proportional to the average probability that a macro user lies in the exclusion zone, the optimal exclusion zone radius that minimizes macro base station power consumption while satisfying all users´ outage constraints is found.