A method for a system information (SI) request procedure performed by a user equipment (UE) is provided. The method includes: receiving a system information block type 1 (SIB1) from a cell; transmitting, to the cell, a first message including a common control channel (CCCH) service data unit (SDU), the CCCH SDU including a radio resource control (RRC) SI request message; receiving, from the cell, a medium access control (MAC) control element (CE) including a UE contention resolution identity; and indicating, by a MAC entity of the UE, reception of an acknowledgment for the RRC SI request message to an RRC entity of the UE after determining that the UE contention resolution identity matches a portion of the CCCH SDU. The SIB1 does not include information related to a Random Access (RA) resource specific to SI requested by the RRC SI request message.