NZ-OA: non-zero-padding overlap-add method for chromatic dispersion compensation

Chromatic dispersion (CD) compensation is a critical, yet power-intensive operation in coherent optical communication systems. Transform-based methods, such as the FFT and FNT, often rely on overlap-save (OS) or zero-padding overlap-add (ZP-OA) techniques for blockwise equalization in the receiver’s DSP. However, these methods only achieve (N − N_Overlap) effective points with N-point transforms, limiting the efficiency. In this letter, we propose the non-zero-padding overlap-add (NZ-OA) method, which achieves N effective points using weighted Fourier transform (WFT) and weighted Fermat number transform (WFNT). The NZ-OA method reduces computational complexity by 41.7% in the 400 km DFT/WFT scenario, and by 15.7% in the 50 km FNT/WFNT scenario when the non-prime Fermat modulus q = 2 ³² + 1 is employed. © 2026 Optica Publishing Group