Resource Allocation Scheme for Minimizing Uplink Interference in Hierarchical Cellular Networks

Hierarchical cellular networks (HCNs), in which femtocells are deployed in the coverage of a conventional macrocell, offer a cost effective solution to achieve high user capacity and extended service coverage. Since a large number of femtocells can be installed by users without cell planning, interference between macrocells and femtocells causes a severe problem. Especially, the macro MS which is located near femtocells or transmits uplink data with large power may make strong uplink interference to neighbor femtocells. This uplink interference results in decreasing the system capacity of femtocells. In this paper, we propose novel resource allocation schemes which minimize the uplink interference from macro MSs to femtocells in TDMA (time division multiple access) based HCNs. This paper introduces two resource allocation schemes: optimization scheme and heuristic scheme. The simulation results show that our proposed schemes can contribute to increase the system capacity of femtocells. In addition, the heuristic scheme is more practical than the optimization scheme in view of computational time.