Time-Segmented Overlap-Free Block Filtering with Application to Chromatic Dispersion Compensation

In high-rate or long-haul optical fiber transmissions, correcting chromatic dispersion (CD) is critical but challenging and energy-intensive due to the large filter tap size required for CD compensation (CDC). Overlap-save (OLS) is a common frequency-domain CDC technique that uses fast Fourier transform (FFT). However, hardware constraints-such as power, memory, latency, and chip area-limit the FFT size. This limitation makes OLS too complex or even infeasible in dispersive channels where the number of taps approaches or exceeds the FFT size. We introduce the time-segmented overlap-free (TS-OLF) technique, a novel frequency-domain block filtering method to enable low-complexity CDC under FFT-size limitations. TS-OLF divides the signal into non-overlapping blocks and segments the filter accordingly to enable filtering operations with any FFT size. It aggregates the results of different filter segments directly in the frequency domain, therefore, using a minimum number of FFT operations. We show that TS-OLF achieves consistently lower complexity than OLS when the filter size is more than half the FFT size, and unlike OLS, can handle filter sizes that exceed the FFT size. TS-OLF also outperforms other filter segmenting methods, providing significant complexity improvements.