  A signal with discrete frequency components, has a zero bispectrum if no
linear combination of the frequencies equals one of the frequency components.
We introduce fractional bispectrum in which for such signals the fractional
bispectrum is nonzero. It is shown that fractional bispectrum has the same
property as bispectrum for Gaussian signals: the fractional bispectrum of a
zero mean Gaussian signal is zero; therefore it can be used to eliminate or
reduce the Gaussian noise.
