Frequency offset mitigation with multiple receive antenna based blind adaptive subspace multiuser detectors

In this paper, we address the problem of multiuser detection in multiple receive antenna based multicarrier code division multiple access (MC-CDMA) systems. Specifically, we consider frequency selective fading channels with frequency offset and use our previously proposed multiple receive antenna based blind adaptive subspace multiuser detectors to recover transmitted data of the user of interest The adaptive detectors rely on a blind subspace technique to estimate the channel parameters. For performance comparison, we extend maximum ratio combining (MRC) detector, which is often used in conventional single transmit and single receive antenna based MC-CDMA systems to single transmit and multiple receive antenna based MC-CDMA systems and evaluate its theoretical performance. Simulation results show that our blind adaptive subspace-based detection techniques perform better than the new MRC detector (with perfect channel parameters) at high frequency offset.