Alamouti scheme with joint antenna selection and power allocation over Rayleigh fading channels in wireless networks

We investigate the Alamouti scheme with joint antenna selection and power allocation over flat-fading Rayleigh channels. Based on the channel state information (CSI) feedbacks, the transmitter selects the optimal two antennas out of all possible antennas to transmit data using space-time block coding (STBC). Then, the transmitter adaptively allocates transmit power among the selected antennas to minimize the symbol-error rate (SER). We derive the SER as either the closed-form expression or the single-fold finite integral when assuming perfect and delayed CSI feedbacks, respectively. Our results show that when the CSI feedback is perfect, the optimal power allocation is to assign all power to the single optimal antenna, such that the selection-combining (SC)-STBC reduces to the simpler selection-combining (SC) scheme. On the other hand, when taking the CSI feedback delay into account, the SC-STBC scheme with dynamic power allocation ensures the better SER performance than the conventional SC scheme and SC-STBC scheme with equal power (EP) allocation.