A PF Scheduling with Low Complexity for Downlink Multi-User MIMO Systems

In downlink multi-user multiple-input/multiple- output (MU-MIMO) systems with BD where there are a lot of users, selecting a user set supported by a base station (BS) is very critical to maximize the total throughput. The optimal user selection algorithm, which requires exhaustive search, is computationally prohibitive in real systems. In this paper, we propose a user selection algorithm with low complexity, where the product of eigenvalues of effective channels is utilized as a selection metric. We adopt the concept of principal angles between subspaces to obtain the product of eigenvalues of effective channel matrix at each iteration. Contrary to conventional low complex user selection algorithms, the proposed algorithm is straightforward to apply to PF scheduling because the proposed selection metric indicates data rate in high SNR regime. Computational complexity analysis and simulation results show that the proposed algorithm achieves almost the same the system throughput of capacity-based algorithm in high SNR regime with considerable reduction in complexity.