Conjugate gradient based signal subspace mobile user tracking

Adaptive antennas enable the increase in the system capacity through spatial interference suppression in the beamforming mode. All the spatial domain channel estimators must react fast to abrupt changes in the channel parameters. Additionally, they have to provide accurate enough tracking capabilities. We construct the user tracking system by employing an efficient conjugate gradient (CG) method based on a step-by-step adaptation scheme. Furthermore, the paper investigates the tracking capability and the computational complexity issues of the proposed system. The simulation results confirm that the proposed CG method achieves better tracking performance than gradient methods both in the stationary and non-stationary signal scenario.