Basestation adaptive antennas for a high-speed FDD/TDMA system

Multipath propagation causes serious performance degradation in a high-speed mobile TDMA system. We have proposed the adaptive antenna which copes with the multipath signals. These considerations have been limited to an uplink channel. We propose the basestation adaptive antennas both for the uplink and downlink channels. We assume an FDD/TDMA system where the frequencies are different between the uplink and downlink channels. The weight vectors proposed in this paper are determined using DOA estimation. The problem of the frequency difference in FDD is removed by this scheme. For the uplink channel, we can realize the path-diversity using the adaptive antenna with several weight vectors. For the downlink channel, we propose a single-beam adaptive antenna and two-beam one. It is shown that the combination of the two-beam basestation adaptive antenna and the mobile terminal with two-input (two antenna) MLSE equalizer shows better performance.

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