Adaptive space-time transmit diversity for MIMO systems

Adaptive space-time transmit diversity (ASTTD) is a scheme, which combines the ordinary STTD scheme (open loop transmit diversity) with information feedback from mobile terminals to adaptively adjust the transmit power at each transmit antenna. In comparison with the STTD system, the performance can be improved especially in slow fading channels. In this paper, the application of ASTTD to MIMO (multiple input multiple output) system is investigated through theoretical analysis and numerical simulations. The proposed scheme requires simpler feedback information compared with the closed loop transmit diversity schemes. Furthermore, this scheme can be included in the current 3GPP standard without any change of the air interface. The performances of ASTTD MIMO systems based on the 3GPP standard are also studied through the simulations.