Joint subcarrier and power allocations in OFDMA-based cognitive femtocell networks

Femtocell networks based on cognitive radio can extend indoor capacity by accessing unused TV or macrocell spectrum bands. In this cognitive femtocell network (CFN), it is a challenging issue to allocate slot and power resources for interference mitigation among femtocells and macrocells. To maximize the capacity of a CFN while avoiding inter-femtocell and cross-tier interferences, we propose a distributed joint resource allocation (DJRA) algorithm that solves slot and power allocation problems. Especially, we solve the optimal downlink (DL) power allocation problem based on an iterative geometric programming approach. Our simulation results verify that this methodology optimizes the DL capacity of each cognitive femtocell base station (CFBS) while rapidly converging towards the desired network performance parameters.