A wireless transmit/receive unit (WTRU) may detect cell congestion by selecting a preamble type as a function of priority level, transmitting the preamble to a serving cell, receiving a random access response (RAR) from the serving cell, determining a congestion state of the serving cell as a function of the received RAR, and/or responding to the congestion state of the serving cell. RACH functionality may be improved by allocating one or more sets of Physical RACH (PRACH) resources to a WTRU. The WTRU may configure the additional PRACH resources based on the allocation. A WTRU may determine a second set of PRACH resources based at least in part on a first set of PRACH resources. A WTRU may determine additional sets of PRACH preambles and may utilize modified PRACH preambles and/or modified PRACH preamble formats. The WTRU may signal additional PRACH resources.