User Association-Based Joint Admission and Power Control for Heterogeneous Wireless Networks

Heterogeneous networks (HetNets) principally composed of macro-cells overlaid with small cells can potentially improve the coverage and capacity of existing cellular networks and satisfy the growing demands of data throughput. In HetNets, small cells play a key role in offloading user data traffic from congested macro-cells and extending the limited coverage of macro-cells. However, the use of small cells is still impeded by the issues of coexistence and efficient operation, as small cells are characterized by limited resources, large-scale random deployment, and a lack of coordination. In this paper, we focus jointly on call admission control and the power allocation problem in HetNet, and we propose a new user association scheme by applying the Voronoi diagram, a powerful computational geometry technique, to solve the user connection problem in which a user has several stations within his range from which to choose. Simulation results show that our proposed scheme can significantly increase the number of admitted users and system throughput, lower the call-blocking ratio, and enhance energy efficiency.