Transmit Antenna Shuffling for Orthogonal Space–Time Block Code Systems Using Uneven Power Amplifiers

A transmit antenna shuffling method combined with an orthogonal space-time block code (OSTBC) is proposed for a system using <inline-formula><tex-math notation="LaTeX">$M$</tex-math></inline-formula> transmit antennas with asymmetric power amplifiers (PAs) having uneven gains. Considering the uneven gains of PAs, we design an optimal antenna shuffling method with <inline-formula><tex-math notation="LaTeX">$\lceil {log}_2(M!) \rceil$</tex-math> </inline-formula>-bit feedback to maximize the detection signal-to-noise ratio (SNR). To reduce the feedback, a suboptimal method with <inline-formula><tex-math notation="LaTeX">$\lceil {log}_2M\rceil$</tex-math></inline-formula> -bit feedback is proposed. A theoretical analysis and numerical results verify that antenna shuffling can significantly improve the detection SNR of the OSTBC system with uneven PA gains and that the SNR loss of the suboptimal method is marginal.