A method and apparatus for supporting Adaptive Modulation and Coding (AM&C) and Hybrid Automatic Repeat Request (H-ARQ) functions in a cellular system including at least one wireless transmit/receive unit (WTRU) and a Node B. A signal is received at the WTRU indicating a need for AM&C and H-ARQ control signaling. An AM&C and H-ARQ control signaling transport channel (TrCH) is dynamically allocated by informing a transport format selection process of the need for AM&C and H-ARQ control signaling. The transport format is selected for required transmission time intervals (TTIs) which assign transport format combinations (TFCs) to establish the AM&C and H-ARQ control signaling transport channel.