  The optimal design of aperiodic/irregular clustered phased arrays for base
stations (BSs) in multi-user multiple-input multiple-output (MU-MIMO)
communication systems is addressed. The paper proposes an ad-hoc synthesis
method aimed at maximizing the users traffic capacity within the cell served by
the BS, while guaranteeing the sufficient level of signal at the terminals.
Towards this end, the search of the optimal aperiodic clustering is carried out
through a customized tiling technique able to consider both single and multiple
tile shapes as well as to assure the complete coverage of the antenna aperture
for the maximization of the directivity. Representative results, from a wide
set of numerical examples concerned with realistic antenna models and benchmark
3GPP scenarios, are reported to assess the advantages of the irregular array
architectures in comparison with regular/periodic layouts proposed by the
standard development organizations, as well.
