Joint Interference Cancellation for FTN Signaling in I/Q Imbalanced Environment

The practical implementation of faster-than-Nyquist (FTN) signaling requires overcoming various hardware component challenges. One of the most significant challenges, in-phase and quadrature-phase imbalance (IQI), is addressed in this paper. We propose a joint interference cancellation method based on frequency-domain minimum-mean-square error (MMSE) equalization and decision-directed successive interference cancellation (DDSIC) to remove both inter-symbol interference (ISI) and IQI. By integrating ISI and IQI as the interference component and analyzing them in extended dimension form, the DDSIC algorithm can iteratively eliminate these interferences. The bit error rate (BER) performance of the proposed scheme closely approximates the IQI-free scenario, demonstrating the effectiveness of the joint interference cancellation method.