Opportunistic Multiple Antenna Systems: Channel Estimation and Experimental Results

In wireless networks, average system through-put can be improved by scheduling transmissions according to instantaneous signal-to-noise ratio (SNR) values of the users assuming that channel fading is fast enough to maintain multiuser diversity. If the fading is slow, opportunistic multiple antenna approaches can introduce artificial fading in the system. These schemes require significant amount of SNR feedback. A novel channel estimation method for opportunistic beamforming is proposed based only on SNR feedback. More importantly, the effectiveness of the proposed channel estimation algorithm is verified using our multiple antenna testbed. The experimental results show that the channel estimation based beamforming can attain true beamforming gains.