Joint Power Reduction and Time-Domain Scheduling for Interference Mitigation in Macro-Pico Heterogeneous Networks with Differential Evolution

Heterogeneous Network (HetNet) in 3GPP is a promising way to increase network coverage and capacity compared to macro cellular-only network. In order to further increase network capacity and balance cell load, Cell Range Expansion (CRE) and time-domain Inter-Cell Interference Coordination (ICIC) have been introduced into LTE-Advanced. The goal of our research is to mitigate the interference towards the User Equipments (UEs) served by the picocells and maintain the throughput of macrocells at the same time. We solve the problem by reducing the transmission power of macro Base Stations (BSs) in some subframes based on the proposed utility function, and accordingly scheduling picocell CRE UEs in these subframes. The existence of optimal solutions to the problem is discussed, and the Differential Evolution (DE) is applied to find the optimal transmission power which maximizes the utility function. System level simulation results show that the proposed algorithm can not only increase the total network´s capacity but also improve the load balance between macrocell and picocell.