  This paper presents an innovative approach leveraging Spectrally Efficient
Frequency Division Multiplexing (SEFDM) with enhancements, including Frequency
Domain Cyclic Prefix (FDCP) and Modified Non-Linear (MNL) acceleration, to
address challenges arising from delay and Doppler shift in mobile communication
channels. Our methodology demonstrates superior performance and enhanced
spectral efficiency while incurring minimal computational overhead. We conduct
a rigorous evaluation of the SEFDM system model, examining the impact of the
MNL acceleration on SEFDM detection, and assessing the effectiveness of FDCP in
mitigating Doppler shift effects. Bit Error Rate (BER) results obtained through
Regularized Sphere Decoding in diverse simulation scenarios affirm the
capability of our proposed solution to effectively manage challenges, ensuring
robust and high-quality connectivity in mobile communication networks.
