Performance analysis of applying up-link estimates in the down-link beamforming using a dual polarized array

Abstract

Most of the current and future mobile communications systems are frequency duplex systems, i.e. the up- and down-link are separated in frequency. Since the effect of the radio channel is not constant with frequency, this potentially limits the capacity gain using adaptive antennas. We use 150 MHz measurement data to simulate adaptive beamforming in a suburban environment. The information from the up-link at 1741 MHz is used for beamforming at this frequency as well as on the down-link at 1839 MHz. Our results show a reduction in C/I improvement of up to 10 dB between the up- and down-link.