Zero-forcing assisted spatial stream allocation in uplink multiuser MIMO systems

This paper introduces a low complexity postprocessing technique allocating spatial streams for uplink transmissions in multiuser (MU) multiple-input multiple-output (MIMO) systems. The scheme is based on zero-forcing (ZF) cancelation of the multiple access interference (MAI) caused by simultaneous transmissions to the access point (AP) equipped with multiple receive antennas from selected users equipped with multiple transmit antennas. The ZF based post-processing at the AP using all channel gain matrices in MU-MIMO is further aided by the singular value decomposition (SVD) preprocessing utilizing local channel state information (CSI) only. Moreover, an antenna selection algorithm is proposed to gain performance advantage from the channel diversity in multiuser environments. Simulation results are provided to demonstrate the potential of our technique in terms of bit error rate performance and capacity.