Efficient User Grouping for Hybrid Beamforming in Single Carrier Wideband Massive MIMO Channels

In this paper, three types of user grouping algorithms in which our own performance metric is utilized are investigated for single carrier downlink wideband spatially correlated massive MIMO channels by using hybrid beamforming structure motivated by the joint spatial division and multiplexing (JSDM) framework. The user grouping procedure consists of two stages. Internally, our own metric called as the achievable information rate (AIR) is calculated given a user grouping input by considering both inter-group and inter-symbol interferences. This metric value shows how efficient the given user grouping input is for the user scenario in the system. Externally, three different user grouping algorithms use this value to find the most efficient user grouping for the user scenario in the system. Based on the simulation results, AIR metric based user grouping via merge and split algorithm gives the nearly optimal user grouping set for the hybrid beamforming structure compared to the fully digital block zero forcing with multi-carrier frequency bound