Photoluminescence (PL) polarization was experimentally studied for the samples with thick InGaAs epitaxial layers with different concentrations of donors in the transverse magnetic field (the Hanle effect). A well-pronounced W-structure observed in the set of samples under study indicate a strong electron-nuclear spin interaction. Analysis of the Hanle curves measured at different pumping powers provided important parameters of the electron-nuclear spin system, such as the Knight field and kinetic local field. We obtained characteristic values of the electron spin relaxation time by modeling the Hanle curves measured with fast modulation of the excitation polarization at different pumping powers,.