Radio propagation studies in a small city for universal portable communications

Time-delay spread and signal level measurements were performed in the streets of a small city at 850 MHz. The maximum root mean square (RMS) time-delay spread observed was 640 ns. However, this dropped to 330 ns for cell radii of 150 m, which is considered a likely size for personal communications systems. RMS delay spread was under 110 ns for cell radii under 75 m or where there was a strong line-of-sight path. When both the transmitter and receiver were on the same road, received power levels followed a two-path model, together with about 0.02 dB/m additional attenuation. A weak but consistent relationship of a decade of increase in RMS time-delay spread for about an 80 dB decrease in received power levels was also found at this site