Propagation loss at 1.8 GHz on microcellular mobile radio channels

This paper reports the analysis of data that were measured on 1.8 GHz microcellular-type channels in four Canadian cities, with one of the objectives being propagation loss modelling. Various transmit configurations are considered, including different antenna heights, different antenna patterns and both horizontal and vertical polarisation. CW as well as wideband (impulse response) data were recorded on both line-of-sight (LOS) and non-line-of-sight (NLOS) channels. The CW results indicate that on about 40% of the streets in an urban area, LOS power loss has a continuous slope that is proportional to Rⁿ, where n is close to 2, as for free space. For the other 60% of the streets, loss is proportional to R^-2 for short ranges. For ranges greater than a breakpoint range, R_b, n takes on greater values that are believed to depend upon position of the mobile station antenna on the vehicle, street geometries, shadowing, and the orientation of structures, such as sign posts and power lines. It was found that the power loss exponent in this region rarely takes on values near 4 nor is R_b often close to the edge of the first Fresnel zone, as would be expected from the flat-earth model, proposed by others for application in microcellular systems. Like the results from the flat-earth model, however, it was found that R_b is greater for higher base station transmit antennas. Results for base station antennas with different radiation patterns and polarisations also indicate that it may be possible to vary these parameters in order to control R_b, and thus cell size, and intra-cell interference