A wireless transmit/receive unit, WTRU, and a method for use by a WTRU for uplink transmission, are disclosed. The WTRU transmits, to a Node-B, a first type message, a second type message, and a third type message, wherein the first type message indicates that the WTRU has uplink buffered data available for transmission, wherein the second type message includes a plurality of indications, wherein each indication indicates an amount of uplink buffered data associated with at least one priority, and wherein the third type message indicates an amount of uplink buffered data and has less information than the second type message. The WTRU receives, from the Node-B, in response to the transmitted first type message, the transmitted second type message, or the transmitted third type message, an uplink data scheduling message, and the WTRU transmits, to the Node-B, uplink data over an uplink channel based on the received uplink data scheduling message.