Adaptive Power Level Setting of Femtocell Base Stations for Mitigating Interference with Macrocells

Femtocells are expected to increase network capacity, extend macrocell coverage, and introduce new services. Because femtocells share the same frequency band with macrocells in many cases, the femtocell base station (BS) must mitigate the interference with macrocells as well as ensure coverage in customer premises. However, conventional femtocell BS transmit power setting have not adequately accounted for the interference with neighboring macrocell mobile stations (MSs), leading to small femtocell user throughput. In this paper, we describe an adaptive femtocell BS transmit power level setting scheme to mitigate the interference with macrocell MSs. The proposed scheme estimates the path loss between the femtocell BS and the neighboring macrocell MSs on the basis of the received power levels from the neighboring macrocell MSs, thereby it mitigates the interference with macrocell MSs while maintaining good indoor coverage for femtocell MSs. According to the system level simulations of downlink LTE, femtocell user throughput of the proposed scheme at the edge of the macrocells is 36 % to 73 % greater than that of the conventional transmit power level setting scheme.