Comparative study of MIMO-OFDM uplink scheduling criteria

Uplink scheduling for MIMO-OFDM users is considered in this paper. Each user spatially multiplexes his data over multiple transmit antennas using V-BLAST scheme. This spatial multiplexing (SM) scheme provides high data rates while multi-user diversity obtained from scheduling improves the performance of the uplink system. The greedy scheduler selects one user at a time based on a criterion that minimizes aggregate OFDM symbol error rate. The main results of this study show that the scheduler that maximizes the optimal MIMO capacity doesn´t work well for a V-BLAST system. Instead, a scheduler that maximizes the V-BLAST capacity is derived specifically from the V-BLAST detection algorithm. Furthermore, we propose and compare suboptimal schedulers that are based on the received MIMO-OFDM channels before processing. The result shows that selecting the user with maximum minimum MIMO-OFDM channel singular value performs very close to the optimal selection criteria with less processing.