An effective transmission beamforming scheme for frequency-division-duplex digital wireless communication systems

Most wireless communication systems use different carriers for uplinks and downlinks, hence the downlink beamforming can only be performed based on the directions-of-arrival (DOA) information of the uplink signals. In this paper, we propose an effective downlink transmission scheme for TDMA mobile communication systems via the integration of direction finding and blind signal estimation techniques. With an M-element antenna array, our new scheme can estimate up to 2M ²/3 DOAs of direct path and multipath signals, while a conventional DOA estimation algorithm can resolve no more than M DOAs. RF experiments show that by incorporating these additional DOA estimates, much improved interference suppression was obtained