Distributed downlink beamforming with cooperative base stations
Ng, B. L.
Evans, J. S.
Hanly, S. V.
IEEE Transactions on Information Theory
Ng, B. L., Evans, J. S., Hanly, S. V., & Aktas, D. (2008). Distributed downlink beamforming with cooperative base stations. Information Theory, IEEE Transactions on, 54(12), 5491-5499.
Please cite this item using this persistent URLhttp://hdl.handle.net/11693/11693
In 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.