Radiowave Propagation in Urban Environments with Application to Public-Safety Communications

We characterized key elements that pose challenges to public-safety radio communications into and out of large buildings, including the strong attenuation of radio signals caused by losses and scattering in the building materials and structure, and the large signal variability that occurs throughout these large structures. We analyzed measurements of continuous-wave radio signals, and provided the parameters for representative log-normal distributions for six frequency bands, ranging from 430 MHz to 4.9 GHz. The data were collected in experiments in which radio-frequency transmitters were carried throughout large urban structures, and receiving systems were placed outside the structures. In other experiments, the radio transmitters were carried through urban streets, with receivers at locations on the streets within the same urban environment. The transmitters were tuned to frequencies near public-safety and cell-phone bands, as well as those of unlicensed bands.