Generalized JSDM with Enhanced Interference Management for Massive MIMO Systems

In this paper, we consider the feedback and precoding designs for massive multiple-input multiple-output (MIMO) systems. Based on a recently introduced two-stage beamforming framework, termed as joint spatial division and multiplexing (JSDM), we propose a generalized JSDM approach to deal with the practical issue that the user’s channel usually has multiple scattering clusters for mobile broadband which may incur significant performance degradation with original JSDM. In particular, we propose a new feedback approach where the users feed back additional channel measurements, referred to as inter-group channel state information (CSI) feedback. To utilize the inter-group CSI, we first provide the joint group precoding (JGP) approaches, then propose a novel virtual user based low-complexity per-group precoding (PGP) method with interference avoidance. Finally, we explore a general PGP approach with power allocations for interference management. Simulation results show that the spectral efficiency is significantly improved with proposed designs.