Transmit diversity scheme with power control for wireless communications

In this paper, we present a new transmit diversity scheme with power contro l by using two transmit antennas in which the power control unit is added t o adaptively suit the channel fading variation. Compared to the transmit di versity scheme (STD, one space time coding scheme) proposed by Alamouti and the traditional maximal ratio combining (MRC) diversity scheme employed at the receiver, simulation results indicate that the new scheme has consider able performance gain. We also discuss tile effects of the imperfect channe l parameter Estimation on the performance of the system. Simulation results show that the new system is more robust to the estimation error of channel fading parameters than the STD. As the signal to noise ratio is relatively high, the diversity scheme with power control is more sensitive to the cha nnel estimation error compared to the NRC. But when the channel estimation accuracy is relatively high, the diversity scheme with power control still has better performance than the ideal MRC as the BER is about 1 x 10(-3).