Two-Tier Interference Mitigation with Directional Antennas for Small-Cells in an Apartment Building

In this paper, the three-dimension directional antenna is proposed to be installed on the small-cells to mitigate the two-tier interference of the ultra-dense heterogeneous small-cell network. We investigate the impacts of the three-dimension directional antennas and the resource block (RB) usage ratio on the system capacity and link reliability for the ultra-dense small-cell system in an apartment building. The three-dimension directional antenna can provide the strong signal for users with the high main lobe gain, and mitigate the intra-cell interference among neighboring small-cells with low side lobes. Consequently, the average system throughput can be significantly improved under a link reliability requirement. Simulation results show that our proposed 12-sector directional antenna can improve 229% average system capacity compared to the 3-sector directional antenna under the link reliability requirement. Meanwhile, the omnidirectional antenna cannot afford the reliable service quality for users in the apartment building in the ultra-dense heterogeneous small-cell network.