Performance analysis of down link time switched transmit diversity (TSTD) in W-CDMA system

The TSTD scheme is a simple, effective transmit diversity method that can increase down-link capacity in CDMA systems. It shows considerable gain compared to non-diversity mode with or without power control for 8 kbps voice services as well as 64 kbps data services. In comparison to other open loop transmit diversity schemes, TSTD has similar performance in mobile speeds from 3 km/h up to 120 km/h, and requires least complexity. It requires only one switch and one additional RF/IF block in the base station (BS) and no additional components in the mobile station (MS) because channel estimation and modulation for each slot is performed basically slot by slot basis. From the viewpoint of both complexity and performance, the TSTD scheme can be one of candidates of down link transmit diversity schemes in 3/sup rd/ generation CDMA systems.