Transmit antenna subset selection for high-rate MIMO-OFDM systems in the presence of nonlinear power amplifiers

The deployment of antenna subset selection on a per-subcarrier basis in MIMO-OFDM systems could improve the system performance and/or increase data rates. This paper investigates this technique for the MIMO-OFDM systems suffering nonlinear distortions due to high-power amplifiers. At first, some problems pertaining to the implementation of this antenna selection approach, including power imbalance across transmit antennas and non-causality of per-subcarrier antenna selection criteria, are identified. Next, an optimal selection scheme is devised by means of linear optimization to overcome those disadvantages. This scheme optimally allocates data subcarriers under a constraint that all antennas have the same number of data symbols. The formulated optimization problem could be applied to the systems with an arbitrary number of multiplexed data streams and with different antenna selection criteria. Finally, a reduced-complexity strategy that requires smaller feedback information and lower computational effort for solving the optimization problem is developed. The improved performance of the proposed antenna selection scheme over its counterpart is analyzed directly in nonlinear fading channels. Simulation results demonstrate that a significant improvement in terms of error performance could be achieved in the proposed system compared to the system without a balance constraint.