Robust Transceiver Design Based on Interference Alignment for Multi-User Multi-Cell MIMO Networks With Channel Uncertainty.

In this paper, we first exploit the inter-user interference and inter-cell interference as useful references to develop a robust transceiver design based on interference alignment for a downlink multi-user multi-cell multiple-inputmultiple-output interference network under channel estimation error. At transmitters, we propose a two-tier transmit beamforming strategy, and we first achieve the inner beamforming direction and allocated power by minimizing the interference leakage as well as maximizing the system energy efficiency, respectively. Then, for the outer beamformer design, we develop an efficient conjugate gradient Grassmann manifold subspace tracking algorithm to minimize the distances between the subspace spanned by interference and the interference subspace in the time-varying channel. At receivers, we propose a practical interference alignment based on the fast and robust Fast Data Projection method subspace tracking algorithm to achieve the receive beamformer under channel uncertainty. Numerical results show that our proposed robust transceiver design achieves better performance compared with some existing methods in terms of the sum rate and the energy efficiency.