Coordinated SLNR Based Precoding in Large-Scale Heterogeneous Networks

This paper focuses on the downlink of large-scale two-tier heterogeneous networks composed of a macrocell overlaid by microcell networks. Our interest is on the design of coordinated beamforming techniques that allow to mitigate the intercell interference. Particularly, we consider the case in which the coordinating base stations have imperfect knowledge of the channel state information. Under this setting, we propose a regularized signal-to-leakage-and-noise ratio (SLNR) based precoding design in which the regularization factor is used to allow better resilience with respect to the channel estimation errors. Based on tools from the random matrix theory, we provide an analytical analysis of the signal-to-noise ratio and SLNR performances. These results are then exploited to propose a proper setting of the regularization factor. Simulation results are finally provided in order to validate our findings and to confirm the performance of the proposed precoding scheme.