Mobile transmit beam-forming diversity on UMTS/HSUPA networks

We proposed and demonstrated that beam-forming type Mobile Transmit Diversity (MTD) can extend the cell coverage, increase the uplink data rate, and improve the reverse link capacity for CDMA/EVDO networks. In this paper, we analyze the MTD gain (the reduction of the transmit power), present the MTD simulation, and report the field trial results on a UMTS system test bed and on a HSUPA network. The analysis shows that the diversity gain of MTD consists of the coherent gain from beam-forming and the incoherent gain from fading mitigation (classical diversity). In addition, both coherent and incoherent gains can be enhanced by the pattern difference (diversity) of the two transmit antennas in MTD. The simulation results show that the MTD gain can be enhanced by the antenna pattern of a specialty antenna in the range of 0.4 to 1.6 dB. The simulation also shows that the MTD gains are slightly reduced (0.4 to 0.8 dB) by the macro diversity of soft handover (SHO). The field tests of MTD technology show that the MTD gains on the static tests are around 4.2 dB. The macro diversity of soft HO degrades the diversity gains around 0.2 dB and 0.3 dB for the Pedestrian and Static tests, respectively.