Power control for diversity reception in time-division duplex CDMA

Power control possibilities are explored for the downlink of a time-division duplex (TDD) CDMA system while employing three different kinds of multipath diversity combining schemes namely the RAKE, the pre-RAKE and the transmit antenna pre-selection. In the latter two, knowledge of the channel characteristics is employed at the base-station to provide maximum decoupling between users on the downlink. Performance of the these receivers is compared in a Rayleigh fading urban environment. It is shown that power control is absolutely indispensable in the latter two schemes and results in considerable performance gains as compared to the RAKE receiver.