Low complexity transmit antenna selection with power balancing in OFDM systems

In this paper, we consider multi-carrier systems with multiple transmit antennas under a power balancing constraint. Applying transmit antenna selection and fixed-power variable-rate transmission per subcarrier as a function of channel variations, we propose an implementation-friendly antenna selection method which offers a reduced complexity in comparison with the optimal antenna selection scheme, which uses numerical optimization. More specifically, in order to solve the subcarrier imbalance across the antennas, we operate a two-step reallocation procedure in order to minimize loss of spectral efficiency. We also provide an analytic lower bound on the spectral efficiency for the proposed scheme. Although this scheme is suboptimal, we show based on some selected numerical examples that our proposed scheme offers almost the same spectral efficiency as the optimal scheme.