In this paper we investigate a generalized three-dimensional (3D) scattering channel model for microcell environments, which idealizes a directional antenna at the center of the semi-spheroid. The joint and marginal PDFs of angle of arrival and Doppler spectra are derived. According to the theory of the relative motion, with the movement at the mobile station, the base station is relatively moving, which will also produce Doppler spectra. Comparisons between our theoretical calculations and customary 3D results show that the analyses are correct and applicable to microcell environments, which promotes the research of the 3D scattering channel models.