Channel Orthogonality and Utility-Based UE Pairing Schemes for LTE Uplink MU-MIMO

Multi-User MIMO (MU-MIMO) is a useful technique to enhance uplink capacity in LTE because the base stations employ multiple receive antennas whereas the user equipments transmit with only a single antenna. In this paper we investigate several UE pairing schemes that maximize the total system utility while adhering to the LTE Release-8 constraint of allocating identical contiguous resource blocks (RBs) to the paired UEs. We design pairing decisions using either the wideband or sub- band channel cross-correlation values of the UEs. These mechanisms offer varying trade-offs between performance and complexity.We show that with appropriate modifications, these schemes work well even for finite queue traffic.