Hybrid Block Diagonalization for Multiuser MIMO System with Domestic Switch Network

Hybrid precoding and combining is a practical technique in MU-MIMO system with significantly reduced complexity. However, it still requires a complex analog network to connect the RF chains and antennas. In this paper, we propose a novel hybrid block diagonalization scheme for the downlink transmission with a compact RF structure. Specifically, proposed structure relies on domestic connection instead of global connection to link RF chains and antennas. Fix-degree phase shifters provide candidate signals and simple on-off switches are used to route the signal to antennas, so RF adders are not required. We formulate how to design the RF precoder and combiner by optimizing the probability distribution through partial cross-entropy minimization. Simulation results verify the performance of proposed scheme with different configurations.