A WTRU receives a control message intended for the WTRU in a shared physical radio resource space in a transmission time interval (TTI) monitored by the WTRU. The WTRU determines whether the control message is intended for the WTRU based on WTRU identity-masked cyclic redundancy check bits. The WTRU processes the control message. The control message has radio resource assignment information and a separate indication indicating whether the control message is a type of control message associated with an uplink or a downlink transmission. The WTRU processes a downlink transmission received in assigned radio resources in the TTI on a condition that the indication indicates that the control message type is associated with a downlink transmission. The WTRU transmits an uplink transmission in assigned radio resources in a subsequent TTI on a condition that the indication indicates that the control message type is associated with an uplink transmission.