A wireless transmit/receive unit (WTRU) is configured to configure a set of hybrid automatic repeat request (H-ARQ) processes. The WTRU is configured to receive information which limits a particular MAC-d flow to accessing a limited set of H-ARQ processes. The WTRU is configured to determine whether a first H-ARQ process from the set of H-ARQ processes is available for transmitting EU data in a transmit time interval (TTI). The WTRU is configured to determine whether the particular MAC-d flow has access to the first H-ARQ process, based on the information received. The WTRU is configured to transmit data from the particular MAC-d flow in the TTI using the first H-ARQ process, on a condition that the first H-ARQ process is available for transmitting EU data in the TTI and that the particular MAC-d flow has access to the first H-ARQ process.