  The time-dependent Ginzburg-Landau approach is used to calculate the complex
fluctuation conductivity in layered type-II superconductor under magnetic
field. Layered structure of the superconductor is accounted for by means of the
Lawrence-Doniach model, while the nonlinear interaction term in dynamics is
treated within self-consistent Gaussian approximation. In high-$T_{c}$
materials, large portion of the $H-T$ diagram belongs to vortex liquid phase.
The expressions summing contributions of all the Landau levels are presented in
explicit form which are applicable essentially to the whole phase and are
compared to experimental data on high-$T_{c}$ superconductor
YBa$_{2}$Cu$_{3}$O$_{7-\delta }$. Above the crossover to the "normal phase",
our results agree with the previously obtained.
