Achievable data rates for two transmit antenna broadcast channels with WCDMA HSDPA feedback information

GRACIELA CORRAL BRIONES; ALEXIS DOWHUSZKO; J. HAMALAINEN; R. WICHMAN

Lab. of Digital Commun. Res., Cordoba Nat. Univ., Argentina

Conferencia; 2005 IEEE International Conference on Communications, 2005. ICC 2005.; 2005

Previous works have shown that in case of multiple transmit antenna broadcast channels, the total system throughput can be greatly improved by combining spatial prefiltering (SP) with multiuser scheduling (MS) [G. Caire et al., 2003], [D. Samardzija et al., 2003]. However, most of the studies assume full channel state information at the transmitter (CSIT). In this paper, we study the achievable data rates within the current WCDMA HSDPA specification and present different schemes based on the WCDMA closed-loop transmit diversity (CLTD) modes. Although the achievable throughput is interference limited at high SNR due to partial CSIT, we show that at moderate power regimes a significant performance gain can be achieved by the proper combination of SP and MS concepts, compared to the systems that only transmit to the user with the best channel condition in each transmission time interval (TTI).