Closed loop transmit diversity enhancements for UMTS narrowband and wideband TD-CDMA

The aim of this work is to evaluate the performance gains obtained by using multiple transmit antennas at the Node B in the context of the low chip rate TDD option (1.28 Mcps TDD option) specified in 3GPP RAN WG1. Moreover, the existing high chip rate system (3.84 Mcps TDD option) is also considered as reference. The impact of using multiple transmit antennas at the Node B on different types of receivers, namely joint detection schemes and conventional matched filter, in several propagation environments, for a voice-like service (without channel coding) is characterized. Through simulation results, it is shown that, depending on the number of transmit antennas, it may be possible not to implement a multiuser detection scheme at the mobile station side in TDD mode based systems.