Investigation of the Method of Calculating Clutter Losses in Recommendation ITU-R P.452 Using 3D Maps

Spectrum sharing remains one of the most important goals for wireless communication systems. Exclusive use of spectrum has been a long-standing principle; it forces different systems or operators to use appropriate spectrum masks to avoid imposing harmful interference on each other. To decide the mask, an accurate prediction model of path loss is required. A lot of channel models have been proposed and roughly speaking there are two categories. One covers the models such as Cost 231-hata [1] and Recommendation ITU-R M.1225 [2], which are appropriate for evaluating the capacities of wireless communication systems [3]. The other covers those proposed for evaluating inter-system interference [4, 5]. The former predict average path loss under a given environment; typical parameters include distance between transmitter and receiver, antenna heights, center frequency, and surrounding building heights. These models are not suitable for inter-system interference studies since some paths in the field may have smaller loss than predicted, which results in harmful interference effects such as smaller coverage areas and lower achievable throughputs. In this paper, we focus on the prediction model of path loss given in Recommendation ITU-R P.452 [4]. This model uses a path profile for calculating the path loss between two points. To determine path status such as LOS or NLOS and to calculate diffraction losses and some other loss components, this method utilizes a uniform ground level, and so does not consider the heights of surrounding objects such as buildings and trees. The model lumps the effect of objects around the transmitter and receiver into the term of clutter loss. Clutter loss values are calculated from clutter heights, distances to clutters, and base station (BS) heights. In Recommendation ITU-R P.452, these parameters except BS heights are specified for area types such as dense urban, urban, and suburban. The following two points needs to be investigated in detail to confirm the validity of the method. • Clutter height for dense urban areas is 25m, but present urban areas contain many buildings much higher than 25m. • Local fluctuations in ground height are not considered in defining clutter losses.