Adaptive T-Detector for Intercarrier Interference Mitigation in Spectrally Efficient Frequency Modulation Systems

In this work, we show that the T-Detector, originally developed for time-domain inter-symbol interference (ISI), gener- alizes to frequency-domain intercarrier interference (ICI) without any modification to its fundamental detection procedure, and apply it to Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems, where bandwidth compression introduces significant ICI. The shortening filter is reinterpreted to operate across subcarriers rather than time samples, and a trainable one- tap equalizer is introduced to separate the unknown, random fading distortion from the deterministic ICI structure. The pro- posed receiver architecture is channel- and modulation-agnostic and integrates channel shortening, frequency-domain equaliza- tion, maximum-likelihood sequence detection, and log-likelihood computation for soft decoding, with a computational complexity comparable to that of classical detection schemes. Numerical results demonstrate that the proposed approach proves effective in SEFDM systems, achieving near-optimal performance in both mutual information (MI) and bit-error rate (BER). Finally, we analyze the operational limits of the T-Detector in terms of the maximum bandwidth compression factor for which the achievable MI can still be attained at high SNR.