Limited feedback beamforming over temporally-correlated channels
IEEE Transactions on Signal Processing
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Event-driven optimal feedback control for multiantenna beamforming
IEEE Transactions on Signal Processing
Differential feedback of MIMO channel gram matrices based on geodesic curves
IEEE Transactions on Wireless Communications
M-DCSK-based chaotic communications in MIMO multipath channels with no channel state information
IEEE Transactions on Circuits and Systems II: Express Briefs
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This paper describes a feedback assisted stochastic gradient algorithm for transmission tracking of the dominant channel subspaces for multiple-input-multiple-output (MIMO) communications systems. Subspace tracking is introduced as a means of tracking multiple transmission weights, being the MIMO generalization of beam steering in the familiar multiple-input-single-output case. The subspace solution approximates that of water filling (WF) in some cases, without the complete rate/power allocation required by WF. The gain of subspace tracking in low rank systems is demonstrated, particularly, in the case where the number of transmit antennas exceeds the number of receive antennas. Simulations of ergodic capacity show the utility of both subspace tracking in general and of the specific adaptation algorithm, and simulations of frame-error rates show the utility in a specific coding example.