Low complexity robust coordinated beamforming in multicell network with channel uncertainties

Multicell coordinated beamforming, where multiple base stations (BSs) collaborate with each other in the beam-vectors design to mitigate the intercell interference (ICI), has been a subject of great attention recently. With perfect channel information available at the base stations, we first present a fast converging algorithm that solves the weighted sum rate maximization (WSRM) problem. Then, the assumption is relaxed to the case where the error vectors in the channel estimates are assumed to lie in an uncertainty set bounded by an ellipsoid. We propose a linear beamforming across a set of coordinated cells only with limiting backhaul signaling. This robust beamforming method allows that all existing (perfect Channel state information (CSI)) beamforming algorithms can be also usable in imperfect CSI condition with only adding an extra step that used for computing worst-case CSI. Indeed in proposed algorithm, beam vectors first computed based on estimated CSI, and then worst-case CSI is computed, beam vectors recomputed again and this process is repeated alternatively until convergence occurs. We evaluate robust beam design through simulation and observe that the proposed strategies has sufficient robust in front of channel uncertainties.