Hierarchical Interference Alignment for Heterogeneous Networks with Multiple Antennas

In this paper, we investigate an interference management scheme relying on multiple antennas in heterogeneous networks with a mixed macro and pico deployment. Our main contribution is to propose a new interference alignment scheme for the heterogenous network. Specifically, our scheme successively creates transmit beamforming vectors for the pico base stations (BSs) and for the macro base station (BS) using the fact that the macro BS and pico BSs have different number of transmit antennas and different number of supporting users per base stations in heterogeneous networks. We call this scheme as ``textit{hierarchical interference alignment} (HIA)´´. The simulations demonstrate that the proposed HIA scheme provides additional degrees of freedom compared to the conventional interference coordination schemes such as time division resource partitioning.