Transmit MMSE Pre-Rake pre-processing with simplified receivers for the downlink of MISO TDD-CDMA systems

In this paper, we introduce an optimised transmit pre-processing technique to reduce multiple access interference in the downlink of TDD-CDMA systems with multiple transmit antennas employed at the base station. In this system, signal preprocessing is performed at the base station, so that a simplified receiver structure that consists of a one-finger correlator can be utilized at the mobile station. Analytic solution for the optimised transmit pre-processing technique is derived by minimizing the transmit mean square error (MMSE). Numerical results are also provided and these demonstrate significant performance improvement when compared to the conventional Rake system and the Pre-Rake MRC transmit diversity system.