Angle and space diversity comparisons in different mobile radio environments

Two types of high-gain multibeam antennas: (1) 24, 15° vertically polarized (Vpol) beams, and (2) 12, 30° Vpol beams were tested and compared to traditional sector antenna configurations. The antennas were tested in dense urban and rural mobile radio environments. A vehicle equipped with a mobile transmitter was driven in the coverage area while the received signal strength (RSS) was recorded on multiple receiver channels attached to multibeam and sector antennas at the base site. The RSS data recorded included fast (Rayleigh) fading and was averaged into local means based on the mobile´s position/speed. The fast fading was extracted from the recorded RSS, and the fading distributions of the two multibeam antennas tested were studied in two distinctly different mobile environments. Fading cumulative distributions for the angular diverse antennas were compared to those of spatially diverse antennas. Angular diversity gain was calculated and compared to traditional space diversity in these mobile environments. Results indicate that angular diversity performance is comparable to space diversity in urban environments (~8 dB). Rural tests typically suggest that both space diversity and angular diversity provide little or no (<2 dB) improvement in fading reduction. A description of the experiment, data reduction and analyses, and calculation of diversity gain are presented