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In this paper, we investigate antenna selection strategies for multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) wireless systems from an energy efficiency (EE) perspective. We first derive closed-form expressions of the EE and the energy efficiency-spectral efficiency (EE-SE) tradeoff in conventional antenna selection MIMO-OFDM systems. The obtained results show that these systems suffer from a significant loss in EE. To achieve a better EE performance, we propose an adaptive antenna selection method where both the number of active radio-frequency chains and the antenna indexes are selected depending on the channel condition. This selection scheme could be implemented by an exhaustive search technique for a small number of antennas. Moreover, we develop a greedy algorithm that achieves a near-optimal performance with much lower complexity compared with …