A method for modifying a signal transmitted from a mobile communication device comprising by perturbing a transmit diversity parameter from its nominal value by modulating the parameter with respect to the nominal value in a first direction for a first feedback interval and then in a second direction for a second feedback interval, receiving a feedback signal including feedback information relating to the perturbed signal as received at a feedback device, and based at least on the feedback information, adjusting the nominal value of the transmit diversity parameter by increasing, decreasing, or preserving the nominal value.