Throughput analysis of feedback-directed adaptive MIMO-OFDM systems

The throughput performance of adaptive multiinput multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system without channel station information (CSI) in priori is investigated in this research. First, throughput scaling factor (pre-log factor) of an n _t transmit antennas, n _r receive antennas MIMO-OFDM with total N subcarriers is asymptotically equal to n*(1-n*-L/MN), where n* = min(n _t ,n _r ) and M is the number of OFDM blocks experienced a constant channel. Second, feedback directed adaptive schemes can achieve the pre-log factor of the lower bound. Third, diversity-multiplexing gain tradeoff of variable-rate systems has been shown to have the same behavior as MIMO systems employed with random Gaussian codewords. Finally, it is shown that throughput of OFDMA with opportunistic scheduling performs better than traditional OFDM-TDMA scheduling with constant enhancement independent of SNR in multiuser downlink environment. © 2007 IEEE.