| This dissertation investigates by theoretical analysis, simulation, and measurement the performance of space diversity combining technique using two antennae at the mobile terminal which due to cost and complexity has previously not been considered for high speed data systems. This technique shows great promise to improve the coverage, capacity, and power efficiency of 3rd generation wireless communication systems.; The theory developed showed that correlation of the mean amplitude between the two received signals at the antenna plays in determining the gain acquired by using the diversity, and the effectiveness in combating the fading. For instance, a 90% correlation between the two received signals will yield up to 5 dB gain in the SNR, where a 30% will provide 9 dB gain. In asymmetric data system such the 1xEVDO SNR gain will be translated into throughput improvement and higher system efficiency with a low bit error rate. Using ordinary space diversity on the order of 1 or 2 inches or simple polarization diversity, gains on the order of 3 dB on the forward link were measured. It was demonstrated experimentally that even a relatively small gain of 3 dB improvement in the SNR approximately doubles the throughput at the access terminal.; Based on this work, a number of CDMA carriers and terminal vendors are beginning to consider equipping next generation handsets with diversity receivers and antennas. |
