The present invention relates to a method and a user equipment for use in a wireless communication system that allow for improved uplink transmit diversity performance by using downlink measurements for making informed decisions on whether or not to change precoding vector for uplink transmission. The user equipment measures (32) downlink characteristics, such as received power, on a plurality of antennas of the user equipment. Based on the measured downlink characteristics a precoding vector for unlink transmission is determined (38). The determined precoding vector is then used to perform uplink transmission (31).