This paper proposes a new detection ordering scheme, which minimizes average error rate of the MIMO system with per antenna rate control. This paper shows an optimal scheme minimizing average error rate expressed by the Q function, and simplifies the optimal scheme by using the minimum equivalent SINR scaled by modulation indices, based on approximated error rate. In spite of reduced complexity, the simplified scheme demonstrates the almost same performance as the optimal scheme. Owing to the diversity of detection ordering, the proposed scheme has over 2 dB higher SNR gain at the BER of 10-3 than the existing ordering schemes in balanced array size systems.

We propose an antenna grouping method that improves the error rate performance of space-time codes in a wide range of mobility environments. The idea is to group symbols to antennas based on limited feedback from the mobile station to utilize all antennas. Our approach requires only two bits of feedback information to achieve better link performance and full rate for a certain four transmit antenna system. Numerical results confirm the bit/frame error gains over the Alamouti-based space-time block code and antenna subset selection strategies.

A minimum mean square error (MMSE) nulling partial parallel interference cancellation (PPIC) receiver for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-CDMA systems is proposed. Our analysis shows that, for multiuser MIMO MC-CDMA systems, interference due to frequency selectivity in multipath fading channel causes detrimental effects on cancelling, thus V-BLAST receiver shows severe performance degradation. The proposed receiver with multistage processing does not produce an error floor in frequency selective fading channel environments and achieves substantial performance gains. The system performance of the proposed receiver was evaluated through computer simulations. The simulation results show that, with two stage PPIC processing, the proposed receiver achieves performance gains of 2.5-4 dB at target BER of 10-3 over the linear MMSE receiver.