Accurate models of the cross-correlation of the large-scale-fading in different propagation channels is essential for designing wireless systems using distributed transmission topologies, such as the coordinated multi-point (CoMP) transmission system. In this contribution, a new parameter defined as the normalized power of common paths in two propagation channels is applied to modeling the cross-correlation of the large-scale-fading in different channels. The common paths here are referred to as the paths with identical parameters, i.e.\ the delays, Doppler frequencies, directions of arrival and directions of departure. Under the uncorrelated scattering (US) assumption, a new geometrical approach is proposed for modeling the large-scale-fading cross-correlation. Experimental investigations show that the proposed modeling method can be used to generate channel cross-correlation coefficients consistent with the experimental results to a certain extent. We postulate that the discrepancies observed between the empirical and theoretical results are caused by the unrealistic US assumption.