Semi-blind full-duplex relay system with ICA based joint CFO mitigation and equalization

We propose a semi-blind independent component analysis (ICA) based receiver structure for an uplink orthogonal frequency division multiplexing (OFDM) based wireless system with multiple users, an amplify-and-forward (AF) relay in full-duplex mode, and a multi-antenna base station. We propose a one-step solution to mitigate multiple integer CFOs without explicit CFO estimation. Also, channel equalization is performed jointly with CFO mitigation by using ICA. A non-redundant precoding designed offline is applied to the transmitted signals, requiring no real-time training or extra transmission power, to enable integer CFO mitigation and ambiguity elimination for the ICA output signals at the base station. Simulation results show that the proposed scheme provides a bit error rate (BER) performance comparable to the ideal case with perfect channel state information (CSI) and no CFO. It is also much more robust against the fractional CFO estimation error than existing methods. Furthermore, the effect of imperfect self-interference cancellation at the full-duplex relay on performance is investigated.