Multiuser MIMO Scheme for Enhanced 3GPP HSDPA

We compare the achievable throughput of space-time multiple access (STMA) scheme versus that of time division multiple access multiple-input multipleoutput (TDMA-MIMO) schemes, illustrated in the third generation partnership project (3GPP) MIMO technical report (TR). These schemes have been proposed to improve 3GPP high speed downlink packet access (HSDPA) channel by employing multiple antennas at both the transmitter and receiver. Our comparisons are focused on the performance in a multiuser environment, which is recently considered using the multiuser scheduling based on TDMA in both the single-input single-output (SISO) and the MIMO schemes for HSDPA. Motivated by those observations, we propose the hybrid STMA (H-STMA) scheme, in which the multiuser scheduling is operated in TDMA or STMA mode depending on the number of loaded users in the system. H-STMA is shown to outperform both TDMA-MIMO and STMA under HSDPA channel parameters. Moreover, we find that it has two practical advantages: the significant reduction of the receiver complexity and the required feedback amount.