Enhanced IEEE 802.11n quantized feedback beamforming with power allocation

In the IEEE 802.11n draft standard, beamforming is adopted as an optional feature to improve signal reception and simplify receiver design. To facilitate beamforming, either the quantized channel state information or quantized steering matrix need to be fed back to the transmitter. In beamforming mode, the spatial channels are diagonalized, so power allocation can be employed to optimize transmission. In this paper, we propose two types of power loading schemes for IEEE 802.11n. The first one minimizes the arithmetic mean of the bit-error rate (ARITH-BER), and the second one minimizes the weighted arithmetic mean of the mean square error (ARITH-MSE). In each scheme, the power loading information can be combined with the existing feedback protocols, so no (or very little) additional feedback information is required. The simulation results illustrate that these power loading schemes can improve the packet error ratio (PER) performance, sometimes significantly.