Date Added: May 2012
Two-tier femtocell networks have been shown to provide superior performance in terms of indoor user coverage and data rate as compared to conventional macrocellular networks. Nevertheless, when macrocells and femtocells share the whole spectrum, macrocellular communication links suffer severely from inter-tier interference, further exacerbated in dense femtocell network deployments. Therefore, it is of interest to investigate optimal sub-channel allocation strategies and characterize their dependence on network density in two-tier femtocell networks. In this paper, the authors consider a joint sub-channel scheme, in which the whole spectrum is shared by both tiers, as well as a disjoint sub-channel scheme, whereby disjoint sets of sub-channels are assigned to each tier.