  We analyse the effects of the propagating Alfv\'en waves, arising due to
non-zero mean magnetic fields, on the nonequilibrium steady states of
three-dimensional (3d) homogeneous Magnetohydrodynamic (MHD) turbulence. In
particular, the effects of Alfv\'en waves on the universal properties of 3dMHD
turbulence are studied in a one-loop self-consistent mode-coupling approach. We
calculate the kinetic- and magnetic energy-spectra. We find that {\em even} in
the presence of a mean magnetic field the energy spectra are Kolmogorov-like,
i.e., scale as $k^{-5/3}$ in the inertial range where $\bf k$ is a Fourier
wavevector belonging to the inertial range. We also elucidate the multiscaling
of the structure functions in a log-normal model by evaluating the relevant
intermittency exponents, and our results suggest that the multiscaling
deviations from the simple Kolmogorov scaling of the structure functions
decrease with increasing strength of the mean magnetic field. Our results
compare favourably with many existing numerical and observational results.
