Cognitive Radio Enhanced Interference Coordination for Femtocell Networks

Adopting small cells, including femtocells, is a promising evolution of future wireless cellular systems to meet the explosive demand for high data rates. As the number of distributively deployed femtocell access points increases rapidly, interference coordination becomes the primary challenge in such heterogeneous networks. In this article, we apply several cognitive radio inspired approaches to enhance the interference coordination for femtocell networks. First, we apply spectrum sensing and statistical analysis to estimate the cross-tier interference between macrocells and femtocells. Based on this, interference coordination is investigated considering two kinds of spectrum sharing approaches. Finally, we introduce a cognitive relay scheme to improve interference coordination performance further.