LTE-Advanced network inter-cell interference analysis and mitigation using 3D analogue beamforming

This paper considers the effects of ICI on the LTE-Advanced physical layer downlink channel for different macro cell diameters and base station (BS) antenna heights with a frequency reuse factor of one and three sectors per site. A site-specific 3D ray-tracing tool is used to model the communication channel between the base stations (main and interfering links) and user equipment (UE) terminals. System performance is evaluated in terms of average spectrum efficiency, cell edge throughput, and outage probability. Two 3D analogue beamforming algorithms are proposed to mitigate the harmful effects of ICI. These are applied at the BS and/or the UE and our results are compared with a more traditional fractional frequency reuse deployment. Simulations demonstrate that our proposed beamforming algorithms provide significant system level improvements, especially for low BS antenna heights. With 10x10 and 2x2 antenna arrays at the BS and the UE respectively, the proposed MaxMin-BF algorithms can provide an average spectrum efficiency of 3.6 bps/Hz and a cell edge throughput of 0.56 bps/Hz up to a cell diameter of 1250 m. Importantly, these results satisfy the IMT-Advanced requirements for candidate 4G and beyond radio interface technologies. Furthermore, our results outperform those achieved using fractional frequency reuse.