Ng, B. L.Evans, J. S.Hanly, S. V.Aktas, D.2016-02-082016-02-0820080018-9448http://hdl.handle.net/11693/22887In this paper, we consider multicell processing on the downlink of a cellular network to accomplish "macrodiversity" transmit beamforming. The particular downlink beamformer structure we consider allows a recasting of the downlink beamforming problem as a virtual linear mean square error (LMMSE) estimation problem. We exploit the structure of the channel and develop distributed beamforming algorithms using local message passing between neighboring base stations. For 1-D networks, we use the Kalman smoothing framework to obtain a forward-backward beamforming algorithm. We also propose a limited extent version of this algorithm that shows that the delay need not grow with the size of the network in practice. For 2-D cellular networks, we remodel the network as a factor graph and present a distributed beamforming algorithm based on the sum-product algorithm. Despite the presence of loops in the factor graph, the algorithm produces optimal results if convergence occurs.EnglishCooperative base stationsDistributed algorithmDownlink beamformingKalman smoothingLinear mean square error (LMMSE)Localized interferenceMessage passingMulticell processingMultiple-input-multiple-output (MIMO)Sum-product algorithmArticle10.1109/TIT.2008.20064261557-9654