A communication method and system for converging a 5th generation (5G) communication system for supporting higher data rates beyond a 4th generation (4G) system with a technology for Internet of things (IoT) are provided. The communication method and system may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for performing a random access (RA) procedure is provided. The method comprises transmitting a first message of a 2 step RA procedure including an RA preamble and a cell-radio network temporary identifier (C-RNTI), receiving a second message of the 2 step RA procedure on a physical downlink control channel (PDCCH) addressed to the C-RNTI, identifying whether a time alignment timer (TAT) is running or not, and determining that the 2 step RA procedure is completed successfully in case that the TAT is running and the PDCCH schedules an uplink (UL) transport block (TB) for a new transmission.