Block transmission with linear frequency domain equalization for dispersive optical channels with direct detection

Block transmission with frequency-domain equalization (FDE) has been proven as an attractive alternative to orthogonal frequency division multiplex (OFDM) for radio frequency (RF) communication, especially at 60 GHz. In this paper, we show that FDE can be advantageously applied for optical transmission over dispersive channels as well, and in particular, in direct-detection systems. We review the optimal coefficients for zero forcing (ZF) and minimum mean square error (MMSE) equalization - both in the case of symbol-spaced and fractionally-spaced sampling, and present promising results for an illustrative visible-light communications (VLC) link based on non-return-to-zero (NRZ) on-off keying (OOK).