Robust Channel Feedback for Collaborative Uplink Beamforming

We present a new algorithm for collaborative uplink transmit beamforming with robustness against mismatches in the channel state information. The beamforming coefficients are computed at the base station using the uplink measurements and fed back to the cooperating terminals. This can be considered as a robust feedback of the channel state. Our beamformer is derived by minimizing the total transmitted power while preserving the received signal at the base station for all the channel realizations within a prescribed uncertainty set. The problem is formulated as a second-order cone program that can be efficiently solved using interior point methods. Simulations results are presented showing the superior performance of our technique compared to classical transmit beamforming.