A feedback-type adaptive array antenna for two-frequency duplex communications

A feedback type adaptive array antenna (AAA) system with wide element spacing is analyzed on the downlink channel of a frequency-division duplexed (FDD) cellular system. The AAA is installed on a base station so the downlink channel transfer functions are estimated and fed back on the uplink channel. The widely spaced AAA shows interference suppression as well as diversity effect against multipath fading. We also propose a scheme to apply our AAA system to the handoff mechanism. Moreover, we adopt an extrapolation technique for channel estimation. Computer simulation results showed that the AAA placed only at the base station can cope with cochannel interference and fading for the downlink when the fading speed is slow.