Adaptive beamforming and power allocation for OFDM over wireless networks

Abstract

The performance of a multiuser wireless network using OFDM, combined with power control and adaptive beamforming for uplink transmission is presented. An adaptive power control algorithm is exploited to achieve the desired signal to noise and interference ratio (SINR) at each subchannel and increase the power efficiency of the mobile transmitter. At the receiver side, the base station uses an antenna array to optimize the SNR-power efficiency, and attenuate the interference from other users dramatically. Therefore, we can achieve a better overall error probability with a fixed total power. A distributed iterative algorithm is used to jointly update the transmission power and the beamformer weights at each subchannel so that it can converge to the optimal solution for both power and beamforming vectors at each subchannel. The algorithm uses only the interference measured locally by the transmitter. Unlike most of the loading algorithms which optimize the bit distribution and subchannel power allocation for a single transmitter this approach tries to optimize the power allocation and decrease the interference for the whole network.