Block transmission with frequency domain equalization in the presence of colored noise

Block transmission with frequency domain equalization has become more and more important over the last years. However, it is usually discussed for dispersive channels with additive white noise. The main emphasis of this paper is on derivation of the optimum equalizer coefficients, if colored noise is considered. Colored noise may especially arise in wireless optical communication links, where large area photodiodes need to be used. Such diodes potentially induce strong f²-noise. We use the minimum-mean square error (MMSE) constraint and prove, that a fractionally spaced equalizer can be regarded as a cascade of a fractionally spaced zero forcing equalizer and a symbol spaced Wiener filter. Exemplarily, the performance of a visible-light communications (VLC) link operating in colored noise is analyzed.