Energy-Efficient Resource-Allocation Model for OFDMA Macrocell/Femtocell Networks

Femtocells (FCs) are introduced to enhance the indoor coverage and system capacity of traditional cellular networks. However, the network performance could be significantly deteriorated due to the increase in cochannel interference in dense deployment. In the literature, three spectrum usage schemes that deal with the cross-tier interference have been proposed, i.e., orthogonal assignment, underlay, and controlled underlay using mainly closed-access FCs. This paper targets the optimization of resource allocation, together with the selection of base stations (BSs) in two-tier networks assuming hybrid access FCs, to reduce the cross-tier interference. Moreover, this model aims to achieve effective spatial reuse between the macrocell (MC) and FCs while guaranteeing quality-of-service (QoS) transmissions by means of joint power control in both tiers. Simulations are conducted to show a comparison with the other three approaches.