Applied numerical linear algebra
Applied numerical linear algebra
Handbook of Antennas in Wireless Communications
Handbook of Antennas in Wireless Communications
Adaptive Filters: Theory and Applications
Adaptive Filters: Theory and Applications
Discrete Random Signals and Statistical Signal Processing
Discrete Random Signals and Statistical Signal Processing
Digital Beamforming in Wireless Communications
Digital Beamforming in Wireless Communications
Adapting a downlink array from uplink measurements
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
IEEE Journal on Selected Areas in Communications
Stochastic model for the mean weight evolution of the IAF-PNLMS algorithm
IEEE Transactions on Signal Processing
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This paper discusses the constrained stochastic gradient (CSG) algorithm used for controlling antenna arrays, aiming to maximize the signal-to-interference-plus-noise ratio (SINR) in mobile communications. Firstly, analytical expressions for the first moment of the weight vector and the SINR characteristic of the standard CSG algorithm are derived for two interferer signals, considering small step-size conditions and assuming Gaussian signal, interference, and noise. From these model expressions, the CSG algorithm performance is assessed, which predicts undesired behavior (termed here unbalanced behavior, pertaining to an unbalance between maximizing signal power and minimizing interference power) when one or more interference angles-of-arrival are close to the signal angle-of-arrival and the angle-of-arrival spreads of the involved signals are small. Finally, by using the model expressions, an improved CSG (ICSG) algorithm is proposed to compensate the unbalanced behavior of the standard CSG algorithm. The accuracy of the proposed model and the effectiveness of the modified algorithm are assessed through numerical simulations.