User assignment for MU-MIMO downlink system based on Munkres algorithm

This paper investigates user assignment algorithms for the downlink multiuser multiple-input multiple-output system with strong correlation at the transmitter side. In maximizing the ergodic achievable sum rate per group (EASRPG), the Munkres user assignment algorithm (MUAA) efficiently finds the optimal solution for the problem but some user groups of the optimal solution severely degrade the EASRPG due to excessive inter-user interference (IUI) in the multiuser statistical eigen-mode transmission (MU-SET) mode. To overcome this, MUAA with mode switching (MUAA-MS) is proposed to build partial optimal paired groups with the MU-SET mode while the other unpaired users perform the single-user SET mode. Results show a higher EASRPG for MUAA-MS.