Low Complexity Transmit Antenna Selection with Power Balancing in Ofdm Systems
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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 9, NO. 10, OCTOBER 2010
Low Complexity Transmit Antenna Selection with Power Balancing in OFDM Systems
Ki-Hong Park, Student Member, IEEE, Young-Chai Ko, Senior Member, IEEE, and Mohamed-Slim Alouini, Fellow, IEEE
Abstract—In this paper, we consider multi-carrier systems with multiple transmit antennas under the power balancing constraint, which is defined as the constraint that the power on each antenna should be limited under a certain level due to the linearity of the power amplifier of the RF chain. 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. More specifically, in order to solve the subcarrier imbalance across the antennas, we operate a two-step reallocation procedure to minimize the loss of spectral efficiency. We also provide an analytic lower bound on the spectral efficiency for the proposed scheme. From selected numerical results, we show that our suboptimal scheme offers almost the same spectral efficiency as the optimal one. Index Terms—Transmit antenna selection, orthogonal frequency division multiplexing, power balancing constraint, adaptive modulation.
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I. I NTRODUCTION HE design of the transmitter or receiver with multiple antennas is an important problem since it has a major impact on the performance of wireless communication systems. In order to obtain considerable improvements, perfect channel state information should be used at the transmitter. However, in practice, the limitation on the feedback overhead and the need of calibrations for channel reciprocity lead to the development of transmit diversity systems with partial channel knowledge [1]. Transmit antenna selection (TAS) can significantly reduce the feedback load since only the information
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 9, NO. 10, OCTOBER 2010
Low Complexity Transmit Antenna Selection with Power Balancing in OFDM Systems
Ki-Hong Park, Student Member, IEEE, Young-Chai Ko, Senior Member, IEEE, and Mohamed-Slim Alouini, Fellow, IEEE
Abstract—In this paper, we consider multi-carrier systems with multiple transmit antennas under the power balancing constraint, which is defined as the constraint that the power on each antenna should be limited under a certain level due to the linearity of the power amplifier of the RF chain. 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. More specifically, in order to solve the subcarrier imbalance across the antennas, we operate a two-step reallocation procedure to minimize the loss of spectral efficiency. We also provide an analytic lower bound on the spectral efficiency for the proposed scheme. From selected numerical results, we show that our suboptimal scheme offers almost the same spectral efficiency as the optimal one. Index Terms—Transmit antenna selection, orthogonal frequency division multiplexing, power balancing constraint, adaptive modulation.
T
I. I NTRODUCTION HE design of the transmitter or receiver with multiple antennas is an important problem since it has a major impact on the performance of wireless communication systems. In order to obtain considerable improvements, perfect channel state information should be used at the transmitter. However, in practice, the limitation on the feedback overhead and the need of calibrations for channel reciprocity lead to the development of transmit diversity systems with partial channel knowledge [1]. Transmit antenna selection (TAS) can significantly reduce the feedback load since only the information