Application of isolated diffraction edge (IDE) method for urban microwave path loss prediction

The multiple knife-edge diffraction is a dominant mechanism for path loss prediction in the microwave frequency band, when vertical plane propagation over rooftops is considered in urban/suburban environments. When the number of knife-edges between transmitter and receiver has a large value, path loss prediction suffers from inaccuracy due to the multiple edge diffractions in the transition regions near shadow boundaries. This paper proposes a heuristic method using the isolated diffraction edges (IDE) selection algorithm for path loss prediction when a number of intervening buildings is up to 100 and buildings are modeled as knife-edges with random heights. The prediction results are compared with the theoretical results from two-dimensional physical optics (PO) for multiple forward diffractions. In most cases, the standard deviation of prediction errors is below 4 dB, and overall prediction results agree well with those of PO integrations even though N has a large value up to 100.