Blind channel identification for multicarrier CDMA systems with transmit diversity

Uniting the strengths of multicarrier (MC) modulation and code division multiple access (CDMA), MC-CDMA systems are of great interest for future broadband transmissions. We consider the problem of channel identification and signal detection/combining schemes for MC-CDMA systems which are equipped with multiple transmit antennas and space-time (ST) coding to provide transmit diversity gain to the receiver. In particular, we present a subspace-based blind channel identification algorithm for such systems. We extend several signal combining schemes, including the maximum ratio combining (MRC) and the equal gain combining (EGC), which are often utilized in conventional single-transmit-antenna based MC-CDMA systems, to ST-coded MC-CDMA (STC-MC-CDMA) systems. Numerical examples are presented to evaluate and compare the proposed channel identification and signal combining techniques.