The embodiments provide a method implemented by a first station (STA) for transmitting a frame to an Access Point (AP) as part of an uplink multi-user simultaneous transmission. The method avoids unintentional beamforming at the AP. The method includes receiving a first frame from the AP, where the first frame includes scheduling information for scheduling a simultaneous uplink transmission for the first STA and one or more other STAs, generating a second frame having a common part and a user-specific part, where the second frame is to be transmitted simultaneously with other frames according to the scheduling information, determining a cyclic shift value to be applied to the common part, where the cyclic shift value is determined to be different from one or more cyclic shift values to be applied by each of the other STAs, applying the cyclic shift value to the common part and transmitting the second frame to the AP.