A bayesian approach to windowed DMRS channel estimation for uplink MU-MIMO systems

To support the increased data streams required for 6G networks, demodulation reference signals (DMRSs) from multiple users must be transmitted simultaneously on the same resource element in multi-user multiple-input multiple-output (MU-MIMO) systems. Therefore, the DMRSs of multiple users are efficiently multiplexed in the code domain via orthogonal cover code (OCC) to minimize pilot interference. In this paper, we investigate uplink DMRS-based channel estimation for MU-MIMO systems with Type II OCC pattern, leveraging statistical channel state information (SCSI) to enhance performance. Specifically, we propose a SCSI-assisted Bayesian channel estimator (SA-BCE) based on the minimum mean square error criterion to suppress the pilot interference and noise. Furthermore, we extend the SA-BCE to windowed SA-BCE (SA-WBCE) to alleviate the energy leakage caused by the limited number of subcarriers and antennas, thereby reducing computational complexity. Simulation results demonstrate that the SA-BCE and SA-WBCE significantly outperform state-of-the-art benchmarks in MU-MIMO systems.