Cisco BWX 8415 Installation And Commissioning Manual page 30

Chapter 3 Overview
3.5 Beamforming
P R E L I M I N A R Y
3.5 Beamforming
Cisco BWX 8415 Basestation antennas contain eight elements (Figure 3-2), with a gain of 16 dBi. Their
combined effect is to concentrate the downlink data into a beam with maximum gain at the location of
each target SS (Figure 3-3).
Similarly, in the uplink the data transmitted by each SS is received by the eight antenna elements with
different phases due to the differences in propagation distance from an SS to each antenna element. The
contributions from an SS are added up coherently after adjusting their phases for maximum gain. This
effect, which we call beamforming, is equivalent to having up to 18 dB of additional gain in the downlink
and up to 9 dB additional gain in the uplink. It allows the Cisco BWX Mobile WiMAX system to operate
at a much lower power level than would otherwise be necessary for the same results.
Figure 3-2 BWX 8415 Basestation
BWX 8415 Basestation Installation and Commissioning Guide
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