Intercarrier interference mitigation and multi-user detection employing adaptive ICA for MIMO-OFDM systems in time variant channels

Orthogonal Frequency Division Multiplexing (OFDM) is a widely applied scheme in modern wireless communication systems that effectively operate in frequency selective fading channels. The combination of OFDM and the Multiple-Input-Multiple-Output (MIMO) technique represents a promising candidate for future broadband wireless systems. This paper addresses the InterCarrier Interference (ICI) issue in multi-user MIMO-OFDM systems operating in time-varying frequency selective channel environments. ICI, which is caused by Carrier Frequency Offset (CFO) between local oscillators in the transmitter and the receiver, can lead to severe system performance degradation. In our proposed method, a recently presented Independent Component Analysis (ICA) technique called Complex Optimum Block Adaptive ICA (Complex OBA-ICA) is employed to recover user signals in the presence of ICI and channel induced mixing. Simulation results indicate that the new technique significantly reduces Inter Symbol Interference (ISI) in multi-user MIMO-OFDM systems in dynamic channel environments.