Cross-Tier Interference Management Scheme for Downlink mMIMIO-NOMA HetNet

Abstract

In this paper, a cross-tier interference mitigation framework based on interference alignment and coordinated beamforming (IA-CB) is investigated for downlink non-orthogonal multiple access (NOMA) heterogeneous networks (HetNets). In the proposed technique, named cross-tier IA-CB (CrIA-CB), the conventional IA-CB is extended to eliminate the cross-tier interference between the macro cell (MC) and the underlaid small cells (SC) in HetNets. The proposed CrIA-CB utilizes the degrees of freedom provided by the massive multiple input multiple output (mMIMO) technology for designing the transmit and receive beamforming vectors to null the cross-tier interference at the user side while decreasing the sharing channel state information (CSI) between SCs and MC. Simulation results validate the performance improvement of the proposed technique in terms of system sum rate over the conventional techniques.