Coordinated channel selection in cognitive macro-femto networks

In this paper, we study uplink channel selection in a system where a macro base station (MBS) and a number of cognitive femto base stations (FBSs) share the same spectrum to serve their intended users with quality of service (QoS) requirements. In this system, the MBS may experience significant aggregate interference when multiple FBSs select the same channel to serve their FUs. An FBS also experiences strong interference from nearby femtocells if the same channel is utilized by adjacent FBSs. We investigate how to coordinate the channel selection at FBSs to reduce the interference experienced at the MBS and FBSs. We propose a cluster-based coordination mechanism where the operator groups the set of FBSs into clusters, and FBSs in the same cluster can utilize a set of channels simultaneously without violating the QoS requirements. To find the desired clusters, we employ a graph-theoretic approach and propose an efficient FBS clustering scheme. Simulation results show that the proposed coordination mechanism achieves a better performance compared to the channel selection scheme without coordination.