Approaches to enhancing autonomous power control at Femto under co-channel deployment of Macrocell and Femtocell

For co-channel deployment of Macrocell and indoor Femtocell, in order to mitigate downlink (DL) interference toward user equipments (UEs) of Macrocell, DL power control (PC) at Femto has been considered as the primary inter-cell interference cancelation (ICIC) strategy in 3GPP standardization. Further, currently, the 3GPP-agreed baseline for backhaul is that there is no direct X2/S1 interface between Macrocell and Femtocell, which means the real-time Macro-Femto coordination does not exist. Thus, autonomous triggering of Femto DL ICIC and autonomous PC at Femto have been recommended in 3GPP standardization. In this paper, to enhance the feasibility and performance of Femto's autonomous PC, we firstly design a strategy for Femto to properly determine the self-configured threshold used to autonomously trigger DL ICIC. Then, more importantly, to improve the autonomous parameter-estimation approaches used for implementing autonomous PC at Femto, an effective strategy is designed for Femto to autonomously estimate whether there exists at least one indoor victim Macro UE (MUE). Simulations show that the proposed strategies work well and provide obviously enhanced ICIC benefit for the focused autonomous Femto PC scheme.