Method of performing random access procedure in wireless communication system

A mobile communication terminal, comprising:

• a display;
• a transceiver;
• and
• a processor operatively connected to the display and transceiver, the processor including a contention resolution timer, the processor configured to
• initiate a random access procedure from a medium access control (MAC) layer of the mobile communication terminal, the random access procedure including starting the contention resolution timer, and
• stop the contention resolution timer and determine that the random access procedure was successfully completed upon receipt of a physical downlink control channel (PDCCH) transmission addressed to a cell-radio network temporary identity (C-RNTI) of the mobile communication terminal and containing a UL grant.