Power delay profiles measured in mountainous terrain (radiowave propagation)

Prediction of multipath delay profiles in mountainous terrain

“…If the target is a single uniform mountain slope, we may approximate in (1), where is the normalized radar cross section of the mountain slope, and is the area of the mountain slope illuminated by the transmitter and visible from the receiver. For general nonuniform mountain slopes, we define the normalized radar cross section [8], and (1) may be written (3) This integral can in principle be evaluated as a sum by defining the elements of area and their orientation using a topographical data base of elevations and an estimate of for each element . In (3), we select only those elements in a range cell for which is constant to within the distance resolution , so that is the weight of the impulse response at time delay relative to the direct path.…”

“…The powers may be added, since there is no phase information in (5), and thus the obtained multipath delay profile represents a spatially averaged result, equivalent to averaging many delay profiles over several wavelengths. The maximum bandwidth should be no more than that equivalent to the space resolution of the terrain data base, e.g., 3 MHz for a 100-m data base. This filtering is equivalent to selecting only those elements in (3) in a range cell for which is constant to within the distance resolution .…”

“…The impulse response data (complex and time-varying) can be used to predict the performance of a digital cellular radio link. Various parameters such as the profile width, rms delay spread, and delay interval [3] can be calculated from the measured impulse response samples, and used as an indicator of potential trouble spots. The three-dimensional (3-D) propagation models for mountainous areas are important, because such areas stress to the limit the multipath handling capabilities of most air interfaces.…”

Specular reflections from high-rise buildings in 900 MHz cellular systems

“…Lorenz [6] plotted scattergrams of the delay spread versus the equivalent path loss. Instead of the delay spread, we rather use the delay windows that are more related to TDMA receiver performance.…”

“…e.g. those described in [2,3,6]). Most of them only collect IRs and need much off-line processing after the measurement campaign in order to get the data of interest.…”