Abstract: An enhanced STBC algorithm by Pre-Rake technique is proposed for the time-division duplex (TDD) CDMA system. By theoretical analysis and simulation, the new algorithm achieves both transmit diversity gain and multipath diversity gain. Further more, Pre-RAKE simplifies the receiver of mobile unit, it also reduce the multiple-access interference. The effects of vehicular speed are also presented in the paper. Simulation results show that Pre-RAKE scheme gives a close performance to the RAKE combiner.

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