Methods and devices are provided wherein a user equipment transmits using at least two uplink transmit antennas and receives a set of control signals in the downlink direction from a cellular network. The user equipment estimates a received signal quality for each control signal in said set of control signals and determines, based on said received signal quality, which control signals that have been reliably received. The user equipment derives one or more parameters related to the uplink transmit diversity operation using a subset of control signals from the set of control signals, said subset only including control signals determined as reliably received; and transmits in the uplink direction applying the derived one or more parameters to control the uplink transmit diversity operation. The accuracy of the transmit diversity parameter values derived/set by the UE can be improved. This will enhance the performance of the uplink transmit diversity and will also reduce interference to the neighbor cells.