HANDLING RANDOM ACCESS CHANNEL RESPONSES

A method and apparatus for supporting a random access using a random access channel (RACH) are disclosed. Each of a plurality of wireless transmit/receive units (WTRUs) sends a random access request to a base station on an uplink RACH preamble. A RACH Response (Access Indication Channel, AICH, message), sent by the base station, is received by each WTRU. The received RACH response signal comprises a control portion (Physical downlink control channel, PDCCH), and a data portion QO (Physical downlink shared channel, PDSCH). The control signal portion of the RACH Response indicates the location of the RACH Response message portion. The RACH Response control signal comprises multiple control channel elements (CCE), where each Q WTRU is allocated a respective CCE to provide its unique RACH Response control signal. The WTRU is configured to locate its intended CCE from among the multiple CCEs sent by the base station. Blind decoding.