Pinto Galdino Marques, Joao Paulo2025-08-132025-08-132025-08-132025-08-06https://hdl.handle.net/10012/22149Multi-User Multiple-Input Multiple-Output (MU-MIMO) systems provide high performance through the transmission of multiple data streams to users (resp. from users) on the Downlink (DL) (resp. Uplink (UL)) at the same frequency and time. Multiple antennas at the users can further improve performance by enabling the choice between diversity (using the multiple antennas per user to create one data stream with potentially higher rates) and multiplexing (utilizing the antennas to create multiple independent data streams per user). To achieve the potential of MU-MIMO systems with Multi-Antenna (MA) users, the Radio Resource Management (RRM) processes must be carefully executed. In this work, we focus on the DL and UL of realistic MU-MIMO systems with MA users. The necessary RRM processes are user selection, digital beamforming (called here precoding), Power Allocation (PA), Power Distribution (PD) and Modulation and Coding Scheme (MCS) selection. We consider the well-known family of precoding strategies called Zero-Forcing (ZF), which nullifies inter-stream interference. There are three primary ZF-based precoding strategies: Coordinated-Transmit-Receive-1 (CTR1), where we enable only the strongest stream per scheduled user, Block Diagonalization (BD), where all possible streams are enabled per selected user, and Coordinated-Transmit-Receive-Flexible (CTRF), which allows a flexible stream allocation per scheduled user. The latter has the potential for increased performance compared to the other strategies at the cost of higher complexity. Throughout this work, we conduct novel offline (where run time is unimportant) studies to compute the performance of MU-MIMO systems under Proportional Fairness (PF) with those precoding strategies on the DL and UL in realistic systems characterized by 3rd Generation Partnership Project (3GPP)-based scenarios where the Base-Station (BS) has a large number of antennas and employs practical MCSs. To enable the offline study on the DL, we employ heuristics from the literature and adapt them to consider practical systems with MCSs and PF, whereas we propose the necessary tools for the offline UL study. The offline studies allow us to execute performance comparisons of MU-MIMO systems with the precoding strategies (BD, CTR1 and CTRF), which can guide the design of real-time RRM heuristics for both the DL and UL. The DL results indicate that CTRF outperforms the other strategies under PF. However, depending on the network parameters, either CTR1 or BD could replace CTRF given their comparable performance. On the UL, the conclusions are similar, but in the 3GPP Urban Macro scenario, CTR1 presents a comparable performance to CTRF over all considered network parameters, emerging as an alternative to CTRF.enMU-MIMOradio resource managementdownlinkuplinkzero-forcing beamformingmulti-antenna usersMaster Thesis