Kronecker Structured Linear Precoding with Local Feedback for the 3-cell Downlink

In this paper, we propose a structured linear interference alignment scheme that can achieve 2 degrees of freedom in the 3-cell downlink network with arbitrary time-invariant channels using only local feedback. The scheme employs a finite number of channel extensions and results in an equivalent channel matrix that is 2-level decomposable. The linear precoders at the transmitters are constructed from the Kronecker products of 2 matrices of specific dimensions. This structured precoding scheme enables inter-cell interference cancellation and the achievement of the degrees of freedom of the network using only “in-cell” channel state information, without the need for any information exchange between base stations. Simulation results validate the proposed scheme.