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This paper presents tracking performance of a simple algorithm for adaptation of complex base band weights of the transmit antenna in a fading channel. The transmit antenna at the base station updates its weights on the basis of feedback from the mobile to converge to its optimal weights. The first feedback consists of a bit that indicates which of the two normalized perturbed weights sent along with the pilot signal from the base station delivered more power to the mobile. The second is sent when the power difference between the powers delivered by the two normalized perturbed weights decreases as compared to the previous minimum. It makes a coarse stochastic gradient algorithm and converges to those weights that maximize the power delivered to the receiver. Simulations in slow and fast fading channels of this algorithm show improved performance as compared to gradient sign feedback algorithm.
Date of Conference: 24-26 Dec. 2004