Fair Scheduling and Antenna Selection Algorithms for Multiuser MIMO Orthogonal Space Division Multiplexing Downlink

We consider the downlink of a multiuser MIMO system where base station as well as the mobiles are equipped with multiple antennas. We propose simplified algorithms for channel aware multiuser scheduling in conjunction with receive antenna selection (RAS) for two downlink multiuser orthogonal space- division multiplexing techniques: Block diagonalization (BD) and successive optimization (SO). The algorithms greedily maximize the weighted sum rate. To apply the proportional fairness criterion, simplified user scheduling metrics have been proposed for both BD and SO. Two RAS algorithms are proposed, which further enhance the power gain of the equivalent single user channel after orthogonal precoding by selecting a subset of the receive antennas that contributes the most towards the total power gain of the channel. A user grouping technique is used to further lower the complexity of the selection algorithms. We compare various multiuser MIMO scheduling strategies applied to BD and SO transmission techniques through simulation. Simulation results demonstrate the effectiveness of the proposed algorithms in delivering long term fairness in data rates among users. Results also show that the proposed scheduling algorithms perform close to the exhaustive search based algorithms and previously proposed lower complexity scheduling algorithms with much less complexity for a large number of users.