Multiple-Threshold Rank-Detection for Reduced-Rank MIMO Channels

In practical multi-input-multi-output (MIMO) systems, the channel matrices often have reduced rank especially for propagation environments with limited scattering. For this scenario, reliable detection of the channel rank is essential in achieving the high performance provided by the MIMO configuration. In traditional rank detection schemes, a single threshold is used and the channel rank is detected as the number of singular values of the observation matrix that are larger than the threshold. In this work, we propose a multiple-threshold-based rank detection scheme, where each threshold corresponds to one possible rank value. The thresholds are optimized based on the derived lower bounds on the rank detection probability for different channel rank values. Simulation results show that the proposed detection scheme outperforms existing schemes in the probability of correct rank detection.