 spacing. Therefore, this model is not applicable to the urban microcellular scenario. Later on, Saunders et al. [15] proposed an attenu- ation function as an explicit solution for multiple diffractions over a series of a large number of obstacles. Also, it extended the solution for arbitrary height and spacing of the series of obstacles using a numerical method [16]. In [17], the authors studied the impact of obstacle height variation when under- going multiple diffractions to predict path loss. Then Tzaras et al. [18] proposed an improved solution, namely, the uniform theory of diffraction (UTD) with slope diffraction coefficient of higher order for a series of obstacles approximated as a knife edge for arbitrary height and spacing. Later Koutitas et al. [19] improved the sloped UTD solution by proposing it for multi-shaped multiple obstacles but it increased the mathematical and computational complexity of the solution. Rodriguez et al. [20-21] proposed a new solution that reduced the mathematical complexity by removing the slope term from the uniform theory of diffraction- physical optics UTD-PO solution. But this solution is only applicable to a series of obstacles, namely, knife-edge of uniform height and spacing. In this paper, we compared UTD-PO and FKE models for path loss prediction due to over-rooftop multiple diffractions over an irregular terrain scenario for mobile radio propaga- tion [22-30]. The results obtained from the models are validated with the meas- urement data available in the literature. A representation of the work presented in this paper is given below. Section II briefly explains the propagation environment for this technique. Section III explains the UTD-PO and FKE models for the computation of path loss over the irregular terrain scenario. In Section IV, both of the models are validated for irregular terrain scenarios, and the results obtained are compared with the available measurement data (Irregular terrain (hills) approximated as a knife edge obstacles) ..... W(n+1) FIGURE 6.1 A