An Upper Bound on SNR for Limited Feedback MIMO Beamforming systems


B. Mondal and Robert W. Heath Jr


In Proc. of IEEE Information Theory Workshop, San Antonio, Texas, October 24-29, 2004.


Multiple-input multiple-output (MIMO) wireless systems can achieve significant diversity and array gain by using transmit beamforming and receive combining. In the absence of full channel knowledge at the transmitter, limited information of the beamforming vector can be made available to the transmitter using a low-rate feedback channel, called limited feedback. In this paper the performance of MIMO beamforming systems employing limited feedback is studied from the point-of-view of signal-to-noise ratio (SNR). An upper bound on the average signal-to-noise ratio (SNR) of such systems is derived as a function of the feedback rate. This analysis quantifies the impact of the feedback rate and the number of transmit and receive antennas on the performance of the system. Simulations have shown that vector quantization based codebook design can closely achieve the performance bound implying the bound is tight at all feedback rates.

Preprint is available here.