Joint MS Offloading and Interference Coordination for Heterogeneous Ultra Dense Networks

Heterogeneous ultra dense network (HUDN) is a promising technique to improve network capacity for the fifth generation mobile communication system. However, HUDNs face the challenges of severe inter-cell interference and imbalanced load. To maximize the system utility, the mobile station (MS) offloading and interference coordination should be considered jointly. This paper applies cell range expansion (CRE) in HUDNs to balance cell loads. First, the interference source of MSs is analyzed for a HUDN with CRE, based on which the initial idea of frequency domain interference coordination is proposed. Then, a joint MS offloading and interference coordination optimization problem is formulated, which is NP hard. Therefore, a heuristic algorithm is proposed to solve the problem step by step. The simulation results show that the proposed scheme can improve the SINR and rate of MSs when compared to the traditional frequency domain ICIC scheme.