Transmission antenna diversity for TDD-CDMA with asymmetric modulation in duplex channel

In this paper we present a new transmission diversity technique for a TDD-CDMA system which consists of different modulation schemes between the forward and the reverse link, where the system utilizes single carrier modulation for reverse link and multi-carrier modulation for forward link, respectively. In mobile communication systems it is desirable to make the mobile unit simple without degrading the system performance. To achieve this goal we propose a new transmission diversity technique to obtain high diversity gain without equipping any diversity functions at the mobile unit. Two types of diversity are utilized for the proposed system, that is, path diversity and antenna diversity are used for the forward link transmission. A method to determine the antenna to be transmitted is presented and computer simulation is carried out to evaluate the system performance under frequency selective fading environment