Random access channel for OFDM-MIMO system

A wireless transmit/receive unit (WTRU) comprising:

• a processing device and an associated transmitting device configured to access a wireless communication system by selecting a phase of a constant amplitude zero autocorrelation (CAZAC) sequence out of a set of phases of the CAZAC sequence, combining the selected phase of the CAZAC sequence with a cyclic prefix and transmitting the combined selected phase of the CAZAC sequence and the cyclic prefix over a random access channel (RACH);
• the processing device and the associated transmitting device, on a condition that the WTRU does not receive an indication over a shared channel that the selected phase of the CAZAC sequence was received, are further configured to transmit another phase of the CAZAC sequence combined with another cyclic prefix over the RACH at an increased transmission power level;
• and
• the processing device and the associated transmitting device, on a condition that the WTRU does receive an indication over the shared channel that the selected phase of the CAZAC sequence was received, are further configured to transmit a signal including access message data and reference symbols with a transmission timing adjusted in response to a timing advance received with the indication;
• wherein the reference symbols are derived from a CAZAC sequence.