Mitigating Uplink Interference in Femto-Macro Coexisted Heterogeneous Network by Using Power Control

In the femto-macro coexisted heterogeneous network, the uplink transmission of femtocell user equipment (FUE) interferes with the macrocell base station (MBS) and deteriorates the capacity of macrocell user equipments (MUEs). To mitigate the cross-tier interference, a power control mechanism is proposed to adjust transmission power of FUE. The approach of this paper is to derive the minimum transmission power to achieve the required modulation and coding scheme and the maximum transmission power without violating the maximal tolerable interference of MBS, respectively. By selecting the minimum one among the two derived transmission power and the maximum allowable transmission power of an FUE as the transmission power of each FUE, the cross-tier interference from FUEs to MBS are alleviated. Simulation results show that when femtocells and macrocell are operated in the co-channel allocation approach, the average capacity of MUEs by using the proposed power control mechanism can be increased by 53.4% as compared to that without power control when 40 femtocells are deployed. The cost for the improvement is a reduction in the average FUE capacity by 7.3%. When the hybrid channel allocation approach is employed, the average capacity of MUEs can be further increased by 21.3%. Hence, the proposed power control mechanism is an efficient solution to mitigate the cross-tier interference and improve the average capacity of MUE with an acceptable reduction in the capacity of FUEs for the femto-macro coexisted heterogeneous network.