A method and wireless transmit/receive unit (WTRU) for uplink transmission are disclosed. A WTRU receives configuration information. The configuration information includes logical channel priority information and a maximum number of hybrid automatic repeat request (HARQ) transmissions. The WTRU receives an uplink grant for a transmission time interval (TTI). The WTRU identifies a HARQ process to use for uplink transmission for the TTI. The WTRU selects data for uplink transmission for the TTI. For a new uplink transmission, data associated with a highest priority is selected. The WTRU initializes a transmission counter. The transmission counter indicates a number of transmissions associated with the selected data. The WTRU transmits the selected data over an uplink channel based on the received uplink grant using the identified HARQ process.