A Study on Radix-2 FFT Based Demodulation Method for Computational Complexity Improvement in LEX-CSK Signal Demodulation

This study introduces a symbol demodulation method based on the fast Fourier transform (FFT) for the orthogonal cyclic shift keying (CSK) modulation. By applying cyclic prefix (CP) insertion to the received signal and zero-padding (ZP) to the reference code, the approach enables an efficient radix-2 FFT algorithm for discrete Fourier transform (DFT) computation. Performance is evaluated against a conventional correlation-based receiver in terms of symbol error rate (SER) and computational complexity. Simulations demonstrate that the proposed method yields comparable SER while reducing computational complexity by approximately three times.