A multiple antenna broadcast channel with perfect channel state informationat the receivers is considered. If each receiver quantizes its channelknowledge to a finite number of bits which are fed back to the transmitter, thelarge capacity benefits of the downlink channel can be realized. However, therequired number of feedback bits per mobile must be scaled with both the numberof transmit antennas and the system SNR, and thus can be quite large in evenmoderately sized systems. It is shown that a small number of antennas can beused at each receiver to improve the quality of the channel estimate providedto the transmitter. As a result, the required feedback rate per mobile can besignificantly decreased.
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