Adaptive Limited Feedback for Sum-Rate Maximizing Beamforming in Cooperative Multicell Systems

• Published in: IEEE transactions on signal processing Vol. 59; no. 2; pp. 800 - 811
• Main Authors: Bhagavatula, R, Heath, Robert W
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Array signal processing; Base station cooperation; Base stations; Beamforming; Channels; Coding, codes; Cooperation; Detection, estimation, filtering, equalization, prediction; Encoding; Exact sciences and technology; Feedback; feedback-bit partitioning; Information, signal and communications theory; limited feedback; Links; Materials; Miscellaneous; Partitioning; Partitioning algorithms; Sampling, quantization; Signal and communications theory; Signal processing; Signal to noise ratio; Signal, noise; Stations; Strategy; Telecommunications and information theory; Upper bound; Parameter estimation; Partition method; Data compression; Base station; Wireless telecommunication; Loss rate; feedback-bit partitioning; limited feedback; Cell network; Random vector; Beam forming; Signal quantization; Channel estimation; Handover; Linear antenna arrays; Mobile radiocommunication; Base station cooperation; Vector quantization; Eigenvector; Cooperative systems; Algorithm; Bit allocation; Upper bound; Simulation; Signal processing; Signal to noise ratio
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2010.2090346

Base station cooperation improves the sum-rates that can be achieved in cellular systems. Conventional cooperation techniques require sharing large amounts of information over finite-capacity backhaul links and assume that base stations have full channel state information (CSI) of all the active users in the system. In this paper, a new limited feedback strategy is proposed for multicell beamforming where cooperation is restricted to sharing only the CSI of active users among base stations. The system setup considered is a linear array of cells based on the "soft hand-off model," where each cell contains single-antenna users and multi-antenna base stations. Beamforming vectors are designed using a generalized eigenvector approach to maximize the sum-rate in a single-interferer scenario, at high signal to noise ratio. Users are assumed to feedback quantized CSI of the desired and interfering channels using a finite-bandwidth feedback link. An upper bound on the mean loss in sum rate due to random vector quantization is derived. A new feedback-bit allocation strategy, to partition the available bits between the desired and interfering channels, is developed to reduce the mean loss in sum-rate due to quantization for the soft hand-off model. The proposed feedback-bit partitioning algorithm is shown, using simulations, to yield sum-rates close to the those obtained using full CSI at base station.